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BW специализируется в научных исследованиях и разработках, и снабжаем самым высокотехнологичным карбидовым материалом для поставки режущих / фрезеровочных инструментов для почвы, воздушного пространства и электронной индустрии. В нашу основную продукцию входит твердый карбид / быстрорежущая сталь, а также двигатели, микроэлектрические дрели, IC картонорезальные машины, фрезы для гравирования, режущие пилы, фрезеры-расширители, фрезеры-расширители с резцом, дрели, резаки форм для шлицевого вала / звездочки роликовой цепи, и специальные нано инструменты. Пожалуйста, посетите сайт www.tool-tool.com для получения большей информации.

BW is specialized in R&D and sourcing the most advanced carbide material with high-tech coating to supply cutting / milling tool for mould & die, aero space and electronic industry. Our main products include solid carbide / HSS end mills, micro electronic drill, IC card cutter, engraving cutter, shell end mills, cutting saw, reamer, thread reamer, leading drill, involute gear cutter for spur wheel, rack and worm milling cutter, thread milling cutter, form cutters for spline shaft/roller chain sprocket, and special tool, with nano grade. Please visit our web www.tool-tool.com for more info.

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Mar 16 Mon 2009 19:51
浸硫処理www.tool-tool.com

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硫化鉄被膜、あるいは硫化鉄を含んだ層を形成する処理は鉄基の機械部品の摩擦特性改善に使われる。歴史的には、硫黄系極圧添加剤が示す耐焼き付き性をより確実にするために導入されたようである。硫化鉄が介在した摩擦面は高荷重、あるいは高温下でも平滑状態を維持し焼き付かないといったことが1950年頃までに明らかにされている。
硫化鉄は、摩擦環境で用いられる場合、グラファイトや二硫化モリブデンなどとともに無機系の固体潤滑剤として分類される。しかし、硫化鉄(被膜)は、潤滑油の代替としてよりも、潤滑油(剤)との併用が多い。二硫化モリブデンなどの固体潤滑剤と硫化鉄を併用し両者の利点を相乗的に利用する方法もある。乾燥状態での用途では、低摩擦化よりも、焼き付き防止と同時に摩擦力の保持、あるいは分配が目的の場合が多いようである。
硫化鉄層を形成する処理は、浸硫処理と呼ばれる事が多い。また、鉄の中に硫黄を拡散(浸透)させる処理であるといった表現も用いられる。しかし、処理温度域(通常570℃以下)では鉄に対する硫黄の個溶限が小さいので、処理後に検出される硫黄のほとんどは硫化鉄を形成しており、個溶(浸透)状態の物は少ないと考えられる。他方、処理方法は千差万別で"硫化"処理といった言葉も不適当な場合もある。このような状況下で「浸硫処理」は硫化鉄を含む被膜(層)を形成する処理の総称として慣習的に使われているようである。

●硫化鉄の性質

形成される硫化鉄は酸性水溶液では分解するが、機械設備が使われるような環境では安定な融点1118℃、ビッカース硬度 (Hv)70前後の化合物である。摩擦面では反応により相手材に硫化被膜を形成することが多い。硫化鉄は、摩擦面が高温(実験によっては850℃)になってもその効果が維持されるため、ある温度以下で溶着の抑制剤として働き、それ以上の温度では軟化あるいは融解して、潤滑剤として働くというようにも考えられている。硫化鉄はFeとSの比が1対1に近い組成であるが、処理方法により、結晶質の場合と非結晶質の場合があると考えられている。しかし、構造差による摩擦特性の差は確認されていない。酸化(物)や水分の影響もほとんど受けない。

●処理の種類・分類方法

硫化鉄は常温から900℃程度の温度範囲で比較的簡単に形成できる。そのため、多くの処理技術が提案されているが、再現性などの問題があり、実際に工業化されている技術は比較的少ない。それらのほとんどは表面硬化処理としての窒化、あるいは浸炭焼入れを伴っている。前者は浸硫窒化処理と呼ばれ、硫化と窒化が同じ工程で570℃前後の温度域で行われる。後者では焼戻し後に電解を利用して200℃以下で処理する。それらは電解の方法や処理温度域、あるいは処理液の違いなどから以下の表のように分類できる。

処理温度

主な硬化法

処理環境

寸法変化

金属表面移動

被膜生成

浸硫窒化

～570℃

窒化(軟窒化)

塩浴・ガス・プラズマ

+

-

"浸硫"

陽極電解1

190℃

浸炭焼入れ

塩浴

-

硫化

陽極電解2

～常温

浸炭焼入れ

水溶液

(+～) -

-

硫化

陰極電解

～常温

浸炭焼入れ

水溶液

+

0

"電着・堆積"

寸法変化 : +は増加を表す。金属表面移動 : -は後退、寸法減を表す。

●浸硫窒化処理

浸硫窒化処理では、窒化鉄層の外層に、軟質の硫化鉄層あるいは硫化鉄をふくんだポーラス状の窒化鉄層が形成される。塩浴・大気圧雰囲気ガス・プラズマを使った方法が工業化されている。層厚さは処理時間や鋼種・用途などに依存するが、硬質層も含め、5～25[μm]の範囲が一般的である。処理による寸法変化は層厚さよりも少ない。X線回折では、Fe_(1-x)S、Fe_3N(ε)に加え、Fe_4N(ν')、 Fe_3O_4m、FeOなどが表面層から検出される。表面状態・硫化鉄の含有量・硬質層と軟質層の比率などは処理方法、あるいは条件に依存し、同時に摩擦摩耗特性も変化する。それらの詳細については不明な部分が多い。用途ごとの処理条件は、総被膜厚さや軟質層の比率などから経験的に選択し、実機テストを行い決定されることが多い。
浸硫窒化処理と同じような状態を作り出すために、通常の軟窒化と陽極電解処理を組み合わせることもある。

●陽極電解処理

陽極電解は通常、浸炭焼入れやショットピーニングなどの後工程として、常温水溶液中・あるいは190℃塩浴中で行われる。酸化膜・切削痕などは固々界面に残らず、処理品に密着した被膜が得られる。膜厚は2～8[μm]とするのが一般的である。陽極処理によると、処理浴や処理品材質などに依存するが、被膜形成に伴い鉄が溶出し、寸法変化が負になる場合が多い。金属表面(固々界面)は被膜厚さと同じ程度、あるいはそれ以上"後退"する。
陽極処理では硫化鉄を構成する硫黄はアルカリ金属塩(NaSCN、Na_2S_2O_3など)のチオシアン酸イオン(SCN^-)やチオ硫酸イオン (S_2O_3^2-)などから、そして鉄は処理品から供給される。水溶液を用いる場合はこれらの溶液が、そして塩浴処理では混合塩(NaSCN + KSCN)が用いられる。上述の鉄の溶出と被膜形成には、チオ硫酸塩を硫化剤とした場合、次のような反応の組み合わせが利用できる。

1) Fe {処理品} → Fe^(2+) {処理浴} + 2e^- {処理品}
2) 5Fe {処理品} + 4S_2O_3^(2-) → 5FeS {被膜} + 3SO_4^(2-) {処理浴} + 2e^- {処理品}

(1)は処理の溶出反応、(2)とは初期の硫化反応を示す。硫化鉄被膜が形成された後の固液界面の反応は、次のように、処理品のFeを硫化鉄被膜のFeに置き換えて考える。

1)' Fe {FeS} → Fe^(2+) {処理浴} + 2e^- {処理品}

チオシアン酸塩が硫化剤の場合は次のように記述できる。

7Fe + 6SCN^- → 6FeS + Fe(CN)_6^(4-) + 2e^-

これらを使った解析によると、陽極電解処理では、通電された電気量のほとんどが処理部品の溶出に、そしてごく一部が硫黄の供給(硫化)に使われることが示される。しかし、電気量が硫化のみに使われる、つまり処理品の寸法が大きくなる、とするモデルも多い。実際には寸法が減少するので留意したい。

●陰極電解処理

鉄の錯イオンなどを含む処理浴中で、処理品を陰極として通電し、硫黄と鉄の両方を処理浴から供給し、硫化鉄被膜を部品表面に形成する処理である。そのため、固々界面の状態は維持される。この処理では、鉄鋼以外の金属でも被覆処理でき、寸法変化と被膜厚さが等しいといった特徴がある。

●摩擦特性

摩擦特性の評価例として乾燥状態でのファビリー(ファレックス)試験がある。この試験はφ6[mm]の試験ピンを2つのV ブロックの間に挟んで増加荷重下で回転させ、焼付き性や摩擦係数などを評価する試験である。処理されたピンとブロックの摩擦面は、赤熱する高荷重域でも焼付きを起こさず、平滑状態を保っている。これらの試験では、相手材も含めた反応の繰り返しなどにより、被膜厚さ以上に摩耗が進んだ場合でも、処理効果の持続が観察される。この試験は油中での摩擦で、油切れが起きた場合などもシミュレーションしていると考えられている。

●適用例

家電・電気機器、あるいは輸送・油圧機器などの初期なじみ、摩擦面の平滑化・焼付き・保油・ローラーピッチング強度・潤滑油温域・荷重分配・荷重の保持と解放、原音などで効果が確認されている。処理品としては、クランクシャフト・ベーン・ネジ・シュー・ブッシュ・吸気バルブ・ワッシャ・ロッカーアーム・ピニオンシャフト・シリンダブロック・ヘッド・ギヤ・プランジャ・リミッタ・シフトホーク・ボール・ケージ・ピン・リングなどがある。ただし、これらには浸炭窒化のみが適用されている部品も含まれている。

歡迎來到Bewise Inc.的世界，首先恭喜您來到這接受新的資訊讓產業更有競爭力，我們是提供專業刀具製造商，應對客戶高品質的刀具需求，我們可以協助客戶滿足您對產業的不同要求，我們有能力達到非常卓越的客戶需求品質，這是現有相關技術無法比擬的，我們成功的滿足了各行各業的要求，包括：精密HSS DIN切削刀具、協助客戶設計刀具流程、DIN or JIS 鎢鋼切削刀具設計、NAS986 NAS965 NAS897 NAS937orNAS907 航太切削刀具,NAS航太刀具設計、超高硬度的切削刀具、醫療配件刀具設計、複合式再研磨機、PCD地板專用企口鑽石組合刀具、NSK高數主軸與馬達、專業模具修補工具-氣動與電動、粉末造粒成型機、主機版專用頂級電桿、PCD V-Cut刀、捨棄式圓鋸片組、粉末成型機、主機版專用頂級電感、’汽車業刀具設計、電子產業鑽石刀具、木工產業鑽石刀具、銑刀與切斷複合再研磨機、銑刀與鑽頭複合再研磨機、銑刀與螺絲攻複合再研磨機等等。我們的產品涵蓋了從民生刀具到工業級的刀具設計；從微細刀具到大型刀具；從小型生產到大型量產；全自動整合；我們的技術可提供您連續生產的效能，我們整體的服務及卓越的技術，恭迎您親自體驗！！

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Welcome to BW tool world! We are an experienced tool maker specialized in cutting tools. We focus on what you need and endeavor to research the best cutter to satisfy users’ demand. Our customers involve wide range of industries, like mold & die, aerospace, electronic, machinery, etc. We are professional expert in cutting field. We would like to solve every problem from you. Please feel free to contact us, its our pleasure to serve for you. BW product including: cutting tool、aerospace tool .HSS DIN Cutting tool、Carbide end mills、Carbide cutting tool、NAS Cutting tool、NAS986 NAS965 NAS897 NAS937orNAS907 Cutting Tools,Carbide end mill、disc milling cutter,Aerospace cutting tool、hss drill’Фрезеры’Carbide drill、High speed steel、Compound Sharpener’Milling cutter、INDUCTORS FOR PCD’CVDD(Chemical Vapor Deposition Diamond )’PCBN (Polycrystalline Cubic Boron Nitride) ’Core drill、Tapered end mills、CVD Diamond Tools Inserts’PCD Edge-Beveling Cutter(Golden Finger’PCD V-Cutter’PCD Wood tools’PCD Cutting tools’PCD Circular Saw Blade’PVDD End Mills’diamond tool. INDUCTORS FOR PCD . POWDER FORMING MACHINE ‘Single Crystal Diamond ‘Metric end mills、Miniature end mills、Специальные режущие инструменты ‘Пустотелое сверло ‘Pilot reamer、Fraises’Fresas con mango’ PCD (Polycrystalline diamond) ‘Frese’POWDER FORMING MACHINE’Electronics cutter、Step drill、Metal cutting saw、Double margin drill、Gun barrel、Angle milling cutter、Carbide burrs、Carbide tipped cutter、Chamfering tool、IC card engraving cutter、Side cutter、Staple Cutter’PCD diamond cutter specialized in grooving floors’V-Cut PCD Circular Diamond Tipped Saw Blade with Indexable Insert’ PCD Diamond Tool’ Saw Blade with Indexable Insert’NAS tool、DIN or JIS tool、Special tool、Metal slitting saws、Shell end mills、Side and face milling cutters、Side chip clearance saws、Long end mills’end mill grinder’drill grinder’sharpener、Stub roughing end mills、Dovetail milling cutters、Carbide slot drills、Carbide torus cutters、Angel carbide end mills、Carbide torus cutters、Carbide ball-nosed slot drills、Mould cutter、Tool manufacturer.

ようこそＢｅｗｉｓｅ　Ｉｎｃ.の世界へお越し下さいませ、先ず御目出度たいのは新たな

情報を受け取って頂き、もっと各産業に競争力プラス展開。

弊社は専門なエンド・ミルの製造メーカーで、客先に色んな分野のニーズ、

豊富なパリエーションを満足させ、特にハイテク品質要求にサポート致します。

弊社は各領域に供給できる内容は：

弊社の製品の供給調達機能は：

弊社の全般供給体制及び技術自慢の総合専門製造メーカーに貴方のご体験を御待ちしております。

Bewise Inc. talaşlı imalat sanayinde en fazla kullanılan ve üç eksende (x,y,z) talaş kaldırabilen freze takımlarından olan Parmak Freze imalatçısıdır. Çok geniş ürün yelpazesine sahip olan firmanın başlıca ürünlerini Karbür Parmak Frezeler, Kalıpçı Frezeleri, Kaba Talaş Frezeleri, Konik Alın Frezeler, Köşe Radyüs Frezeler, İki Ağızlı Kısa ve Uzun Küresel Frezeler, İç Bükey Frezeler vb. şeklinde sıralayabiliriz.

BW специализируется в научных исследованиях и разработках, и снабжаем самым высокотехнологичным карбидовым материалом для поставки режущих / фрезеровочных инструментов для почвы, воздушного пространства и электронной индустрии. В нашу основную продукцию входит твердый карбид / быстрорежущая сталь, а также двигатели, микроэлектрические дрели, IC картонорезальные машины, фрезы для гравирования, режущие пилы, фрезеры-расширители, фрезеры-расширители с резцом, дрели, резаки форм для шлицевого вала / звездочки роликовой цепи, и специальные нано инструменты. Пожалуйста, посетите сайт www.tool-tool.com для получения большей информации.

BW is specialized in R&D and sourcing the most advanced carbide material with high-tech coating to supply cutting / milling tool for mould & die, aero space and electronic industry. Our main products include solid carbide / HSS end mills, micro electronic drill, IC card cutter, engraving cutter, shell end mills, cutting saw, reamer, thread reamer, leading drill, involute gear cutter for spur wheel, rack and worm milling cutter, thread milling cutter, form cutters for spline shaft/roller chain sprocket, and special tool, with nano grade. Please visit our web www.tool-tool.com for more info.

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個人分類：學術研究

Mar 16 Mon 2009 19:20
Español Inductor www.tool-tool.com

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Figura 1: Inductores.

Un inductor o bobina es un componente pasivo de un circuito eléctrico que, debido al fenómeno de la autoinducción, almacena energía en forma de campo magnético.

Construcción [editar]

Un inductor está constituido usualmente por una cabeza hueca de una bobina de material conductor, típicamente alambre o hilo de cobre esmaltado. Existen inductores con núcleo de aire o con núcleo de un material ferroso, para incrementar su capacidad de magnetismo entre la Intensidad (inductancia).
Los inductores pueden también estar construidos en circuitos integrados, usando el mismo proceso utilizado para realizar microprocesadores. En estos casos se usa, comúnmente, el aluminio como material conductor. Sin embargo, es raro que se construyan inductores dentro de los circuitos integrados; es mucho más práctico usar un circuito llamado "girador" que, mediante un amplificador operacional, hace que un condensador se comporte como si fuese un inductor. El inductor consta de las siguientes partes:

Pieza polar: Es la parte del circuito magnético situada entre la culata y el entrehierro, incluyendo el núcleo y la expansión polar.

Núcleo: Es la parte del circuito magnético rodeada por el devanado inductor.

Devanado inductor: Es el conjunto de espiras destinado a producir el flujo magnético, al ser recorrido por la corriente eléctrica.

Expansión polar: Es la parte de la pieza polar próxima al inducido y que bordea al entrehierro.

Polo auxiliar o de conmutación: Es un polo magnético suplementario, provisto o no, de devanados y destinado a mejorar la conmutación. Suelen emplearse en las máquinas de mediana y gran potencia.

Culata: Es una pieza de sustancia ferromagnética, no rodeada por devanados, y destinada a unir los polos de la máquina.

También pueden fabricarse pequeños inductores, que se usan para frecuencias muy altas, con un conductor pasando a través de un cilindro de ferrita o granulado.

Energía almacenada [editar]

La bobina almacena energía eléctrica en forma de campo magnético cuando aumenta la intensidad de corriente, devolviéndola cuando ésta disminuye. Matemáticamente se puede demostrar que la energía, $\mathcal{E} \,\!$ , almacenada por una bobina con inductancia $L\,\!$ , que es recorrida por una corriente de intensidad $I \,\!$ , viene dada por:

$\mathcal{E} = {1 \over 2} L I^2\,\!$

Campo magnetico [editar]

Para un solenoide largo en el cual la distancia entre y uno de sus extremos al centro , es mucho mayor que el radio, el campo magnetico es:

      B=μo*n*I, donde μo es =4π*10^-7  T·m/A   ; n, es  el número de espiras por

 unidad de longitud N/L ; 
                      I, la corriente que pasa por el selenoide.

Inductancia [editar]

Autoinductancia, el flujo que atraviesa un circuito puede relacionarse con la corriente en el mismo y con las corrientes que circulan por los circuitos próximos.(No hay cercanía con ningún imán permanente).

$L = \frac{\Phi m}{I} ={4}{\pi }{10^{-7}}{n^2}{A}{l}$ , donde Φm es el flujo magnetico, A el área transversal de la bobina, y l la longitud.

Fuerza electromotriz autoinducida [editar]

Una variación de la intensidad de corriente ( $\quad i(t) = \Delta I/\Delta t$ ) dará como resultado una variación del campo magnético y, por lo mismo, un cambio en el flujo que está atravesando el circuito. De acuerdo con la Ley de Faraday, un cambio del flujo, origina una fuerza electromotriz autoinducida. Esta fuerza electromotriz, de acuerdo con la Ley de Lenz, se opondrá a la causa que lo origina, esto es, la variación de la corriente eléctrica, por ello suele recibir el nombre de fuerza contralectromotriz. Su valor viene dado por la siguiente ecuación diferencial:

$E =- \frac{d\Phi}{dt} = -L \frac{di}{dt}$

donde el signo menos indica que se opone a la causa que lo origina.

En un inductor ideal, la fuerza contra-electromotriz autoinducida es igual a la tensión aplicada al inductor. La fórmula precedente puede leerse de esta manera: Si uno de los bornes del inductor es positivo con respecto al otro, la corriente que entra por el primero aumenta con el tiempo.

Cuando el inductor no es ideal porque tiene una resistencia interna en serie, la tensión aplicada es igual a la suma de la caída de tensión sobre la resistencia interna más la fuerza contra-electromotriz autoinducida.

Comportamientos ideal y real [editar]

Figura 2: Circuito con inductancia.

La bobina ideal (figura 2) puede definirse a partir de la siguiente ecuación:

$u(t) = L{di(t) \over dt} \;$

donde, L es la inductancia, u (t) es la función diferencia de potencial aplicada a sus bornes e i (t) la intensidad resultante que circula.

Comportamiento en corriente continua [editar]

Figura 3. Diagrama cartesiano de las tensiones y corriente en una bobina.

Una bobina ideal en CC se comporta como un cortocircuito (conductor ideal) mientras que la real se comporta como una resistencia cuyo valor R_L (figura 5a) será el de su devanado. Esto es así en régimen permanente ya que en régimen transitorio, esto es, al conectar o desconectar un circuito con bobina, suceden fenómenos electromagnéticos que inciden sobre la corriente (ver circuitos serie RL y RC).

Comportamiento en corriente alterna [editar]

Figura 4. Diagrama fasorial.

En CA, una bobina ideal ofrece una resistencia al paso de la corriente que recibe el nombre de reactancia inductiva, X_L, cuyo valor viene dado por el producto de la pulsación ( $\quad \omega = 2 \pi f \,\!$ ) por la inductancia, L:

$\quad X_L = \omega L \,\!$

Si la pulsación está en radianes por segundo (rad/s) y la inductancia en henrios (H) la reactancia resultará en ohmios.

Al conectar una CA senoidal v (t) a una bobina aparecerá una corriente i (t), también senoidal, esto es, variable, por lo que, como se comentó más arriba, aparecerá una fuerza contraelectromotriz, -e (t), cuyo valor absoluto puede demostrase que es igual al de v (t). Por tanto, cuando la corriente i (t) aumenta, e (t) disminuye para dificultar dicho aumento; análogamente, cuando i (t) disminuye, e (t) aumenta para oponerse a dicha disminución. Esto puede apreciarse en el diagrama de la figura 3. Entre 0º y 90º la curva i (t) es negativa, disminuyendo desde su valor máximo negativo hasta cero, observándose que e (t) va aumentando hasta alcanzar su máximo negativo. Entre 90º y 180º, la corriente aumenta desde cero hasta su valor máximo positivo, mientras e (t) disminuye hasta ser cero. Desde 180º hasta los 360º el razonamiento es similar al anterior.

Dado que la tensión aplicada, v (t) es igual a -e (t), o lo que es lo mismo, está desfasada 180º respecto de e (t), resulta que la corriente i (t) queda retrasada 90º respecto de la tensión aplicada. Consideremos por lo tanto, una bobina L, como la de la figura 2, a la que se aplica una tensión alterna de valor:

$u(t)=V_0 \cdot \sin(\omega t + \beta),$

Figura 5.: Circuitos equivalentes de una bobina real en CC, a), y en CA, b) y c).

De acuerdo con la ley de Ohm circulará una corriente alterna, retrasada 90º (π / 2) respecto a la tensión aplicada (figura 4), de valor:

$i(t)= {u(t) \over R} = I_0 \cdot \sin(\omega t + \beta - {\pi \over 2}),$

donde $I_0 = {V_0 \over X_L}$ . Si se representa el valor eficaz de la corriente obtenida en forma polar:

$\vec{I} = I \ \underline{\mid \beta - 90^\circ}$

Y operando matemáticamente:

$\vec{I} = {V \over X_L} \ \underline{\mid \beta - 90^\circ} = {{V \ \underline{\mid \beta}} \over {X_L \ \underline{\mid 90^\circ}}}$

Por lo tanto, en los circuitos de CA, una bobina ideal se puede asimilar a una magnitud compleja sin parte real y parte imaginaria positiva:

$\vec{X_L} = 0 + X_Lj = X_L \ \underline{\mid 90^\circ}$

En la bobina real, habrá que tener en cuenta la resistencia de su bobinado, R_L, pudiendo ser su circuito equivalente o modelo, el que aparece en la figura 5b) o 5c) dependiendo del tipo de bobina o frecuencia de funcionamiento, aunque para análisis más precisos pueden utilizarse modelos más complejos que los anteriores.

Asociaciones comunes [editar]

Figura 6. Asociación serie general.

Figura 7. Asociación paralelo general.

Al igual que la resistencias, las bobinas pueden asociarse en serie (figura 6), paralelo (figura 7) o de forma mixta. En estos casos, y siempre que no exista acoplamiento magnético, la inductancia equivalente para la asociación serie vendrá dada por:

$L_{AB} = L_1 + L_2 +...+ L_n = \sum_{k=1}^n L_k$

y para la paralelo:

$L_{AB} = {1 \over \sum_{k=1}^n {1 \over L_k} }$

Para la asociación mixta se procederá de forma análoga que con las resistencias.

Si se requiere una mayor comprensión del comportamiento reactivo de un inductor, es conveniente entonces analizar detalladamente la "Ley de Lenz" y comprobar de esta forma como se origina una reactancia de tipo inductiva , la cual nace debido a una oposición que le presenta el inductor o bobina a la variación de flujo magnetico.

Comportamiento a la interrupción del circuito - ANÁLISIS DE TRANSITORIOS [editar]

La alimentación carga el inductor a través la resistencia.

Examinemos el comportamiento práctico de un inductor cuando se interrumpe el circuito que lo alimenta. En el dibujo de derecha aparece un inductor que se carga a través una resistencia y un interruptor. El condensador dibujado en punteado representa las capacidades parásitas del inductor. Está dibujado separado del inductor, pero en realidad forma parte de él, porque representa las capacidades parásitas de las vueltas del devanado entre ellas mismas. Todo inductor tiene capacidades parásitas, incluso los devanados especialmente concebidos para minimizarlas como el devanado en "nido de abejas".

El interruptor se abre. La corriente solo puede circular cargando las capacidades parásitas.

A un cierto momento $\scriptstyle{t_\circ}$ el interruptor se abre. Si miramos la definición de inductancia:

$V = L{dI\over dt}$

vemos que, para que la corriente que atraviesa el inductor se detenga instantáneamente, seria necesario la aparición de una tensión infinita, y eso no puede suceder. ¿Qué hace la corriente? Pues continúa pasando. ¿Por donde? Ella "se las arregla" para continuar. Al principio, el único camino que tiene es a través las capacidades parásitas. La corriente continúa circulando a través la capacidad parásita, cargando negativamente el punto alto del condensador en el dibujo.

En el instante $\scriptstyle{t_\circ}$ el interruptor de abre dejando la inductancia oscilar con las capacidades parásitas.

Nos encontramos con un circuito LC que oscilará a una pulsación:

$\textstyle{\omega = {1\over \sqrt{LC}}}$

donde $\scriptstyle{C}$ es el valor equivalente de las capacidades parásitas. Si los aislamientos del devanado son suficientemente resistentes a las altas tensiones, y si el interruptor interrumpe bien el circuito, la oscilación continuará con una amplitud que se amortiguará debido a las pérdidas dieléctricas y resistivas de las capacidades parásitas y del conductor del inductor. Si además, el inductor tiene un núcleo ferromagnético, habrá también pérdidas en el núcleo.
Hay que ver que la tensión máxima de la oscilación puede ser muy grande. Eso le vale el nombre de sobretensión. Se comprende que pueda ser grande, ya que el máximo de la tensión corresponde al momento en el cual toda la energía almacenada en la bobina $\scriptstyle{{1\over 2}LI^2}$ habrá pasado a las capacidades parásitas $\scriptstyle{{1\over 2}CV^2}$ . Si estas son pequeñas, la tensión puede ser muy grande y pueden producirse arcos eléctricos entre vueltas de la bobina o entre los contactos abiertos del interruptor.
Aunque los arcos eléctricos sean frecuentemente perniciosos y peligrosos, otras veces son útiles y deseados. Es el caso de la soldadura al arco, lámparas a arco, alto horno eléctrico y hornos a arco.
En el caso de la soldadura al arco, el interruptor de nuestro diagrama es el contacto entre el metal a soldar y el electrodo.

Si la tensión es grande pueden producirse arcos en el interruptor o en la bobina.

Lo que sucede cuando el arco aparece depende de las características eléctricas del arco. Y las características de un arco dependen de la corriente que lo atraviesa. Cuando la corriente es grande (decenas de amperios), el arco está formado por un camino espeso de moléculas y átomos ionizados que presentan poca resistencia eléctrica y una inercia térmica que lo hace durar. El arco disipa centenas de vatios y puede fundir metales y crear incendios. Si el arco se produce entre los contactos del interruptor, el circuito no estará verdaderamente abierto y la corriente continuará a circular.
Los arcos no deseados constituyen un problema serio y difícil de resolver cuando se utilizan altas tensiones y grandes potencias.

En el instante $\scriptstyle{t_1}$ se produce un arco que dura hasta el instante $\scriptstyle{t_2}$ . A partir de ese momento, la inductancia oscila con las capacidades parásitas. En punteado la corriente y la tensión que habría si el arco no se produjese.

Cuando las corrientes son pequeñas, el arco se enfría rápidamente y deja de conducir la electricidad.
En el dibujo de la derecha hemos ilustrado un caso particular que puede producirse, pero que solo es uno de los casos posibles. Hemos ampliado la escala del tiempo alrededor de la apertura del interruptor y de la formación del arco.
Después de la apertura del interruptor, la tensión a los bornes de la inductancia aumenta (con signo contrario). En el instante $\scriptstyle{t_1}$ , la tensión es suficiente para crear un arco entre dos vueltas de la bobina. El arco presenta poca resistencia eléctrica y descarga rápidamente las capacidades parásitas. La corriente, en lugar de continuar a cargar las capacidades parásitas, comienza a pasar por el arco. Hemos dibujado el caso en el cual la tensión del arco es relativamente constante. La corriente del inductor disminuye hasta que al instante $\scriptstyle{t_2}$ sea demasiado pequeña para mantener el arco y este se apaga y deja de conducir. La corriente vuelve a pasar por las capacidades parásitas y esta vez la oscilación continúa amortiguándose y sin crear nuevos arcos, ya que esta vez la tensión no alcanzará valores demasiado grandes.
Recordemos que este es solamente un caso posible.
Se puede explicar porqué puede uno recibir una pequeña descarga eléctrica al medir la resistencia de un bobinado con un simple óhmetro que solo puede alimentar unos miliamperios y unos pocos voltios. La razón es que para medir la resistencia del bobinado, le hace circular unos miliamperios. Si, cuando se desconectan los cables del óhmetro, sigue uno tocando con los dedos los bornes de la bobina, los miliamperios que circulaban en ella continuaran a hacerlo, pero pasando por los dedos.

El diodo sirve de camino a la corriente del inductor cuando el transistor se bloquea. Eso evita la aparición de altas tensiones entre el colector y la base del transistor.

La regla es que, para evitar los arcos o las sobretensiones, hay que proteger los circuitos previendo un pasaje para la corriente del inductor cuando el circuito se interrumpe. En el diagrama de la derecha hay un ejemplo de un transistor que controla la corriente en una bobina (la de un relé, por ejemplo). Cuando el transistor se bloquea, la corriente que circula en la bobina carga las capacidades parásitas y la tensión del colector aumenta y puede sobrepasar fácilmente la tensión máxima de la junción colector-base y destruir el transistor. Colocando un diodo, como el diagrama, la corriente encuentra un camino en el diodo y la tensión del colector estará limitada a la tensión de alimentación más los 0,6 V del diodo. El precio funcional de esta protección es que la corriente de la bobina tarda más en disminuir y eso, en algunos casos, puede ser inconveniente. Se puede disminuir el tiempo si, en lugar de un diodo rectificador, se coloca un diodo zener o Transil.
No hay que olvidar que el dispositivo de protección deberá ser capaz de absorber casi toda la energía almacenada en el inductor.

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個人分類：學術研究

Mar 16 Mon 2009 15:53
Esperanto Induktilo www.tool-tool.com

Bewise Inc. www.tool-tool.com Reference source from the internet.

Kutimaj induktoroj

Induktilo aŭ induktoro estas aparato ĉefa celo de kiu estas havi induktancon por elektra kurento. Induktilo kutime estas konstruita surbaze de skeleto aŭ magnetokonduktilo, sur kiun estas volvita drato. La magnetokonduktilo ofte havas grandan magnetan permeablon por pligrandigi la atingatan valoron de la induktanco.

Laŭ sia konstruo estas simila al transformatoro, sed malsimile al transformatoro induktilo povas havi nur unu volvaĵon.

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beeway 發表在痞客邦留言(0) 人氣()

個人分類：學術研究

Mar 16 Mon 2009 15:40
English Inductor www.tool-tool.com

Bewise Inc. www.tool-tool.com
Reference source from the internet.

Inductor

A selection of low-value inductors

Type
Passive

Working principle
Electromagnetic
induction

First production
Michael Faraday(1831)

Electronic
symbol

This box: view • talk

An inductor is a passive electrical
component that can store energy in a magnetic field created by
the electric current
passing through it. An inductor's ability to store magnetic energy is measured
by its inductance, in
units of henries.
Typically an inductor is a conducting wire shaped as a coil, the loops help
create a strong magnetic field inside the coil due to Faraday's law
of induction. Inductors are one of the basic electronic components used in
electronics where current and voltage change with time, due to the ability of
inductors to delay and reshape alternating currents.

An "ideal inductor" has inductance, but no resistance or capacitance, and does not
dissipate energy. A real inductor is equivalent to a combination of inductance,
some resistance due to the resistivity of the wire, and some capacitance. At
some frequency, usually much higher than the working frequency, a real inductor
behaves as a resonant
circuit (due to its self capacitance).
In addition to dissipating energy in the resistance of the wire, magnetic core
inductors may dissipate energy in the core due to hysteresis, and at high
currents may show other departures from ideal behavior due to nonlinearity.

[edit]
Physics

[edit]
Overview

Inductance (L)
(measured in henries) is an effect
resulting from the magnetic field that forms
around a current-carrying conductor that
tends to resist changes in the current. Electric current
through the conductor creates a magnetic flux proportional
to the current. A change in this current creates a change in magnetic flux that,
in turn, by Faraday's
law generates an electromotive force
(EMF) that acts to oppose this change in current. Inductance is a measure of the
amount of EMF generated for a unit change in current. For example, an inductor
with an inductance of 1 henry produces an EMF of 1 volt when the current through
the inductor changes at the rate of 1 ampere per second. The number of loops,
the size of each loop, and the material it is wrapped around all affect the
inductance. For example, the magnetic flux linking these turns can be increased
by coiling the conductor around a material with a high permeability
such as iron. This can increase the inductance by 2000 times, although less so
at high frequencies.

[edit]
Hydraulic model

Electric current can be modeled by the hydraulic analogy. An
inductor can be modeled by the flywheel effect of a heavy turbine rotated by the flow.
When water first starts to flow (current), the stationary turbine will cause an
obstruction in the flow and high pressure (voltage) opposing the flow until it
gets turning. Once it is turning, if there is a sudden interruption of water
flow the turbine will continue to turn by inertia, generating a high pressure to
keep the flow moving. Magnetic interactions such as in transformers are
not modeled hydraulically.

[edit]
Applications

An inductor with two 47mH windings, as may be found in a power supply.

Inductors are used extensively in analog circuits and
signal processing. Inductors in conjunction with capacitors and other
components form tuned circuits which can emphasize or filter out specific
signal frequencies. Applications range from the use of large inductors in power
supplies, which in conjunction with filter capacitors remove residual hum or other fluctuations from the
direct current output, to the small inductance of the ferrite bead or torus installed around a cable to
prevent radio frequency
interference from being transmitted down the wire. Smaller
inductor/capacitor combinations provide tuned circuits used in
radio reception and broadcasting, for instance.

Two (or more) inductors which have coupled magnetic flux form a transformer, which is a
fundamental component of every electric utility power grid. The
efficiency of a transformer may decrease as the frequency increases due to eddy
currents in the core material and skin effect on the windings. Size of the core
can be decreased at higher frequencies and, for this reason, aircraft use 400
hertz alternating current rather than the usual 50 or 60 hertz, allowing a great
saving in weight from the use of smaller transformers^[1].

An inductor is used as the energy storage device in some switched-mode
power supplies. The inductor is energized for a specific fraction of the
regulator's switching frequency, and de-energized for the remainder of the
cycle. This energy transfer ratio determines the input-voltage to output-voltage
ratio. This X_L is used in complement with an active
semiconductor device to maintain very accurate voltage control.

Inductors are also employed in electrical transmission systems, where they
are used to depress voltages from lightning strikes and to limit switching
currents and fault
current. In this field, they are more commonly referred to as reactors.

Larger value inductors may be simulated by use of gyrator circuits.

[edit]
Kind of coils

[edit]
Ferrite honeycomb coil:

The honeycomb coils is wounded in a crisscross manner to reduce distributed
capacitance. It is used in the circuits tuners radio in the ranges of medium and
long waves, thanks to the shape of the winding are achieved inductive high
values in low volume.

[edit]
Toroidal core coil:

A simple coil wound on a cylindrical form creates an external magnetic field
with a north and south pole. A toroidal coil can be created from a cylindrical
coil by bending it into a doughnut shape thereby merging the north and south
poles. In a toroidal coil, the magnetic flux is largely kept internal to the
coil. This results in less magnetic radiation from coil, and less sensitivity to
external fields.

[edit]
Inductor construction

Inductors. Major scale in centimetres.

An inductor is usually constructed as a coil of conducting
material, typically copper wire, wrapped around a core either of air or of
ferromagnetic material.
Core materials with a higher permeability
than air increase the magnetic field and confine it closely to the inductor,
thereby increasing the inductance. Low frequency inductors are constructed like
transformers, with cores of electrical steel laminated to prevent eddy currents. 'Soft' ferrites are widely
used for cores above audio frequencies,
since they don't cause the large energy losses at high frequencies that ordinary
iron alloys do. This is because of their narrow hysteresis curves, and their
high resistivity prevents
eddy currents. Inductors
come in many shapes. Most are constructed as enamel coated wire wrapped around a
ferrite bobbin with wire exposed on the
outside, while some enclose the wire completely in ferrite and are called
"shielded". Some inductors have an adjustable core, which enables changing of
the inductance. Inductors used to block very high frequencies are sometimes made
by stringing a ferrite cylinder or bead on a wire.

Small inductors can be etched directly onto a printed circuit
board by laying out the trace in a spiral pattern. Some such planar
inductors use a planar core.

Small value inductors can also be built on integrated circuits
using the same processes that are used to make transistors. Aluminium interconnect is typically
used, laid out in a spiral coil pattern. However, the small dimensions limit the
inductance, and it is far more common to use a circuit called a "gyrator" which uses a capacitor and active
components to behave similarly to an inductor.

[edit]
In electric circuits

An inductor opposes changes in current. An ideal inductor would offer no
resistance to a constant direct current; however,
only superconducting
inductors have truly zero electrical
resistance.

In general, the relationship between the time-varying voltage
v(t) across an inductor with inductance L and the
time-varying current i(t) passing through it is described by the
differential
equation:

$v(t) = L \frac{di(t)}{dt}$

When there is a sinusoidal alternating current
(AC) through an inductor, a sinusoidal voltage is induced. The amplitude of the
voltage is proportional to the product of the amplitude
(I_P) of the current and the frequency ( f ) of
the current.

$i(t) = I_P \sin(2 \pi f t)\,$

$\frac{di(t)}{dt} = 2 \pi f I_P \cos(2 \pi f t)$

$v(t) = 2 \pi f L I_P \cos(2 \pi f t)\,$

In this situation, the phase of the current
lags that of the voltage by 90 degrees. #

If an inductor is connected to a DC current source, with
value I via a resistance, R, and then the current source short
circuited, the differential relationship above shows that the current through
the inductor will discharge with an exponential decay:

$\ i(t) = I (e^{\frac{-tR}{L}})$

[edit]
Laplace circuit analysis (s-domain)

When using the Laplace transform in
circuit analysis, the transfer impedance of an ideal inductor with no initial
current is represented in the s domain by:

$Z(s) = Ls\,$

where

L is the inductance, and

s is the complex frequency

If the inductor does have initial current, it can be represented by:

adding a voltage source in series with the inductor, having the value:

$L I_0 \,$

(Note that the source should have a polarity that opposes the initial
current)

or by adding a current source in parallel with the inductor, having the
value:

$\frac{I_0}{s}$

where

L is the inductance, and

I₀ is the initial current in the
inductor.

[edit]
Inductor networks

Main article: Series and
parallel circuits

Inductors in a parallel
configuration each have the same potential difference (voltage). To find their
total equivalent inductance (L_eq):

$\frac{1}{L_\mathrm{eq}} = \frac{1}{L_1} + \frac{1}{L_2} + \cdots + \frac{1}{L_n}$

The current through inductors in series
stays the same, but the voltage across each inductor can be different. The sum
of the potential differences (voltage) is equal to the total voltage. To find
their total inductance:

$L_\mathrm{eq} = L_1 + L_2 + \cdots + L_n \,\!$

These simple relationships hold true only when there is no mutual coupling of
magnetic fields between individual inductors.

[edit]
Stored energy

The energy (measured in joules, in SI) stored by an inductor is equal to
the amount of work required to establish the current through the inductor, and
therefore the magnetic field. This is given by:

$E_\mathrm{stored} = {1 \over 2} L I^2$

where L is inductance and I is the current through the
inductor(****).

[edit]
Q factor

An ideal inductor will be lossless irrespective of the amount of current
through the winding. However, typically inductors have winding resistance from
the metal wire forming the coils. Since the winding resistance appears as a
resistance in series with the inductor, it is often called the series
resistance. The inductor's series resistance converts electrical current
through the coils into heat, thus causing a loss of inductive quality. The quality factor (or Q) of
an inductor is the ratio of its inductive reactance to its resistance at a given
frequency, and is a measure of its efficiency. The higher the Q factor of the
inductor, the closer it approaches the behavior of an ideal, lossless, inductor.

The Q factor of an inductor can be found through the following formula, where
R is its internal electrical resistance and ωL is capacitive or
inductive reactance at resonance:

$Q = \frac{\omega{}L}{R}$

By using a ferromagnetic core, the
inductance is greatly increased for the same amount of copper, multiplying up
the Q. Cores however also introduce losses that increase with frequency. A grade
of core material is chosen for best results for the frequency band. At VHF or higher frequencies an air
core is likely to be used.

Inductors wound around a ferromagnetic core may saturate at
high currents, causing a dramatic decrease in inductance (and Q). This
phenomenon can be avoided by using a (physically larger) air core inductor. A
well designed air core inductor may have a Q of several hundred.

An almost ideal inductor (Q approaching infinity) can be created by immersing
a coil made from a superconducting alloy in liquid helium or liquid nitrogen. This
supercools the wire, causing its winding resistance to disappear. Because a
superconducting inductor is virtually lossless, it can store a large amount of
electrical energy within the surrounding magnetic field (see superconducting
magnetic energy storage).

[edit]
Inductance formulae

The table below lists some common formulae for calculating the theoretical
inductance of several inductor constructions.

Construction
Formula
Dimensions

Cylindrical coil^[2]
$L=\frac{\mu_0KN^2A}{l}$

L = inductance in henries (H)

μ₀ = permeability of
free space = 4π × 10^-7 H/m

K = Nagaoka coefficient^[2]

N = number of turns

A = area of cross-section of the coil in square metres
(m²)

l = length of coil in metres (m)

Straight wire conductor
$L = l\left(\ln\frac{4l}{d}-1\right) \cdot 200 \times 10^{-9}$

L = inductance (H)

l = length of conductor (m)

d = diameter of conductor (m)

$L = 5.08 \cdot l\left(\ln\frac{4l}{d}-1\right)$

L = inductance (nH)

l = length of conductor (in)

d = diameter of conductor (in)

Short air-core cylindrical coil
$L=\frac{r^2N^2}{9r+10l}$

L = inductance (µH)

r = outer radius of coil (in)

l = length of coil (in)

N = number of turns

Multilayer air-core coil
$L = \frac{0.8r^2N^2}{6r+9l+10d}$

L = inductance (µH)

r = mean radius of coil (in)

l = physical length of coil winding (in)

N = number of turns

d = depth of coil (outer radius minus inner radius) (in)

Flat spiral air-core coil
$L=\frac{r^2N^2}{(2r+2.8d) \times 10^5}$

L = inductance (H)

r = mean radius of coil (m)

N = number of turns

d = depth of coil (outer radius minus inner radius) (m)

$L=\frac{r^2N^2}{8r+11d}$

L = inductance (µH)

r = mean radius of coil (in)

N = number of turns

d = depth of coil (outer radius minus inner radius) (in)

Toroidal core (circular cross-section)
$L=\mu_0\mu_r\frac{N^2r^2}{D}$

L = inductance (H)

μ₀ = permeability
of free space = 4π ×
10^-7 H/m

μ_r = relative permeability of core material

N = number of turns

r = radius of coil winding (m)

D = overall diameter of toroid (m)

[edit]
See also

Electronic
component

Capacitor

Resistor

Memristor

Electricity

Electronics

Gyrator

Inductance (including
mutual inductance)

Induction coil

Induction
cooking

Induction loop

Magnetic core

Saturable
reactor

Transformer

Reactance
(electronics)

RL circuit

RLC circuit

[edit]
Synonyms

coil

Choke
(electronics)

reactor

[edit]
Notes

^ http://www.wonderquest.com/expounding-aircraft-electrical-systems.htm
^ ^a
^b
Nagaoka,
Hantaro. The Inductance Coefficients of Solenoids[1].
27. Journal of the College of Science, Imperial University, Tokyo, Japan.
p. 18.

[edit]
External links

General

How stuff
works The initial concept, made very simple

Capacitance
and Inductance - A chapter from an online textbook

Spiral
inductor models. Article on inductor characteristics and modeling.

Online coil
inductance calculator. Online calculator calculates the inductance of
conventional and toroidal coils using formulas 3, 4, 5, and 6, above.

AC circuits

beeway 發表在痞客邦留言(0) 人氣()

個人分類：學術研究

Mar 16 Mon 2009 15:22
English Inductor www.tool-tool.com

Bewise Inc. www.tool-tool.com Reference source from the internet.

Inductor

A selection of low-value inductors

Type
Passive

Working principle
Electromagnetic induction

First production
Michael Faraday(1831)

Electronic symbol

This box: view • talk

An inductor is a passive electrical component that can store energy in a magnetic field created by the electric current passing through it. An inductor's ability to store magnetic energy is measured by its inductance, in units of henries. Typically an inductor is a conducting wire shaped as a coil, the loops help create a strong magnetic field inside the coil due to Faraday's law of induction. Inductors are one of the basic electronic components used in electronics where current and voltage change with time, due to the ability of inductors to delay and reshape alternating currents.

An "ideal inductor" has inductance, but no resistance or capacitance, and does not dissipate energy. A real inductor is equivalent to a combination of inductance, some resistance due to the resistivity of the wire, and some capacitance. At some frequency, usually much higher than the working frequency, a real inductor behaves as a resonant circuit (due to its self capacitance). In addition to dissipating energy in the resistance of the wire, magnetic core inductors may dissipate energy in the core due to hysteresis, and at high currents may show other departures from ideal behavior due to nonlinearity.

[edit] Physics

[edit] Overview

Inductance (L) (measured in henries) is an effect resulting from the magnetic field that forms around a current-carrying conductor that tends to resist changes in the current. Electric current through the conductor creates a magnetic flux proportional to the current. A change in this current creates a change in magnetic flux that, in turn, by Faraday's law generates an electromotive force (EMF) that acts to oppose this change in current. Inductance is a measure of the amount of EMF generated for a unit change in current. For example, an inductor with an inductance of 1 henry produces an EMF of 1 volt when the current through the inductor changes at the rate of 1 ampere per second. The number of loops, the size of each loop, and the material it is wrapped around all affect the inductance. For example, the magnetic flux linking these turns can be increased by coiling the conductor around a material with a high permeability such as iron. This can increase the inductance by 2000 times, although less so at high frequencies.

[edit] Hydraulic model

Electric current can be modeled by the hydraulic analogy. An inductor can be modeled by the flywheel effect of a heavy turbine rotated by the flow. When water first starts to flow (current), the stationary turbine will cause an obstruction in the flow and high pressure (voltage) opposing the flow until it gets turning. Once it is turning, if there is a sudden interruption of water flow the turbine will continue to turn by inertia, generating a high pressure to keep the flow moving. Magnetic interactions such as in transformers are not modeled hydraulically.

[edit] Applications

An inductor with two 47mH windings, as may be found in a power supply.

Inductors are used extensively in analog circuits and signal processing. Inductors in conjunction with capacitors and other components form tuned circuits which can emphasize or filter out specific signal frequencies. Applications range from the use of large inductors in power supplies, which in conjunction with filter capacitors remove residual hum or other fluctuations from the direct current output, to the small inductance of the ferrite bead or torus installed around a cable to prevent radio frequency interference from being transmitted down the wire. Smaller inductor/capacitor combinations provide tuned circuits used in radio reception and broadcasting, for instance.

Two (or more) inductors which have coupled magnetic flux form a transformer, which is a fundamental component of every electric utility power grid. The efficiency of a transformer may decrease as the frequency increases due to eddy currents in the core material and skin effect on the windings. Size of the core can be decreased at higher frequencies and, for this reason, aircraft use 400 hertz alternating current rather than the usual 50 or 60 hertz, allowing a great saving in weight from the use of smaller transformers^[1].

An inductor is used as the energy storage device in some switched-mode power supplies. The inductor is energized for a specific fraction of the regulator's switching frequency, and de-energized for the remainder of the cycle. This energy transfer ratio determines the input-voltage to output-voltage ratio. This X_L is used in complement with an active semiconductor device to maintain very accurate voltage control.

Inductors are also employed in electrical transmission systems, where they are used to depress voltages from lightning strikes and to limit switching currents and fault current. In this field, they are more commonly referred to as reactors.

Larger value inductors may be simulated by use of gyrator circuits.

[edit] Kind of coils

[edit] Ferrite honeycomb coil:

The honeycomb coils is wounded in a crisscross manner to reduce distributed capacitance. It is used in the circuits tuners radio in the ranges of medium and long waves, thanks to the shape of the winding are achieved inductive high values in low volume.

[edit] Toroidal core coil:

A simple coil wound on a cylindrical form creates an external magnetic field with a north and south pole. A toroidal coil can be created from a cylindrical coil by bending it into a doughnut shape thereby merging the north and south poles. In a toroidal coil, the magnetic flux is largely kept internal to the coil. This results in less magnetic radiation from coil, and less sensitivity to external fields.

[edit] Inductor construction

Inductors. Major scale in centimetres.

An inductor is usually constructed as a coil of conducting material, typically copper wire, wrapped around a core either of air or of ferromagnetic material. Core materials with a higher permeability than air increase the magnetic field and confine it closely to the inductor, thereby increasing the inductance. Low frequency inductors are constructed like transformers, with cores of electrical steel laminated to prevent eddy currents. 'Soft' ferrites are widely used for cores above audio frequencies, since they don't cause the large energy losses at high frequencies that ordinary iron alloys do. This is because of their narrow hysteresis curves, and their high resistivity prevents eddy currents. Inductors come in many shapes. Most are constructed as enamel coated wire wrapped around a ferrite bobbin with wire exposed on the outside, while some enclose the wire completely in ferrite and are called "shielded". Some inductors have an adjustable core, which enables changing of the inductance. Inductors used to block very high frequencies are sometimes made by stringing a ferrite cylinder or bead on a wire.

Small inductors can be etched directly onto a printed circuit board by laying out the trace in a spiral pattern. Some such planar inductors use a planar core.

Small value inductors can also be built on integrated circuits using the same processes that are used to make transistors. Aluminium interconnect is typically used, laid out in a spiral coil pattern. However, the small dimensions limit the inductance, and it is far more common to use a circuit called a "gyrator" which uses a capacitor and active components to behave similarly to an inductor.

[edit] In electric circuits

An inductor opposes changes in current. An ideal inductor would offer no resistance to a constant direct current; however, only superconducting inductors have truly zero electrical resistance.

In general, the relationship between the time-varying voltage v(t) across an inductor with inductance L and the time-varying current i(t) passing through it is described by the differential equation:

$v(t) = L \frac{di(t)}{dt}$

When there is a sinusoidal alternating current (AC) through an inductor, a sinusoidal voltage is induced. The amplitude of the voltage is proportional to the product of the amplitude (I_P) of the current and the frequency ( f ) of the current.

$i(t) = I_P \sin(2 \pi f t)\,$

$\frac{di(t)}{dt} = 2 \pi f I_P \cos(2 \pi f t)$

$v(t) = 2 \pi f L I_P \cos(2 \pi f t)\,$

In this situation, the phase of the current lags that of the voltage by 90 degrees. #

If an inductor is connected to a DC current source, with value I via a resistance, R, and then the current source short circuited, the differential relationship above shows that the current through the inductor will discharge with an exponential decay:

$\ i(t) = I (e^{\frac{-tR}{L}})$

[edit] Laplace circuit analysis (s-domain)

When using the Laplace transform in circuit analysis, the transfer impedance of an ideal inductor with no initial current is represented in the s domain by:

$Z(s) = Ls\,$

where

L is the inductance, and

s is the complex frequency

If the inductor does have initial current, it can be represented by:

adding a voltage source in series with the inductor, having the value:

$L I_0 \,$

(Note that the source should have a polarity that opposes the initial current)

or by adding a current source in parallel with the inductor, having the value:

$\frac{I_0}{s}$

where

L is the inductance, and

I₀ is the initial current in the inductor.

[edit] Inductor networks

Main article: Series and parallel circuits

Inductors in a parallel configuration each have the same potential difference (voltage). To find their total equivalent inductance (L_eq):

$\frac{1}{L_\mathrm{eq}} = \frac{1}{L_1} + \frac{1}{L_2} + \cdots + \frac{1}{L_n}$

The current through inductors in series stays the same, but the voltage across each inductor can be different. The sum of the potential differences (voltage) is equal to the total voltage. To find their total inductance:

$L_\mathrm{eq} = L_1 + L_2 + \cdots + L_n \,\!$

These simple relationships hold true only when there is no mutual coupling of magnetic fields between individual inductors.

[edit] Stored energy

The energy (measured in joules, in SI) stored by an inductor is equal to the amount of work required to establish the current through the inductor, and therefore the magnetic field. This is given by:

$E_\mathrm{stored} = {1 \over 2} L I^2$

where L is inductance and I is the current through the inductor(****).

[edit] Q factor

An ideal inductor will be lossless irrespective of the amount of current through the winding. However, typically inductors have winding resistance from the metal wire forming the coils. Since the winding resistance appears as a resistance in series with the inductor, it is often called the series resistance. The inductor's series resistance converts electrical current through the coils into heat, thus causing a loss of inductive quality. The quality factor (or Q) of an inductor is the ratio of its inductive reactance to its resistance at a given frequency, and is a measure of its efficiency. The higher the Q factor of the inductor, the closer it approaches the behavior of an ideal, lossless, inductor.

The Q factor of an inductor can be found through the following formula, where R is its internal electrical resistance and ωL is capacitive or inductive reactance at resonance:

$Q = \frac{\omega{}L}{R}$

By using a ferromagnetic core, the inductance is greatly increased for the same amount of copper, multiplying up the Q. Cores however also introduce losses that increase with frequency. A grade of core material is chosen for best results for the frequency band. At VHF or higher frequencies an air core is likely to be used.

Inductors wound around a ferromagnetic core may saturate at high currents, causing a dramatic decrease in inductance (and Q). This phenomenon can be avoided by using a (physically larger) air core inductor. A well designed air core inductor may have a Q of several hundred.

An almost ideal inductor (Q approaching infinity) can be created by immersing a coil made from a superconducting alloy in liquid helium or liquid nitrogen. This supercools the wire, causing its winding resistance to disappear. Because a superconducting inductor is virtually lossless, it can store a large amount of electrical energy within the surrounding magnetic field (see superconducting magnetic energy storage).

[edit] Inductance formulae

The table below lists some common formulae for calculating the theoretical inductance of several inductor constructions.

Construction
Formula
Dimensions

Cylindrical coil^[2]
$L=\frac{\mu_0KN^2A}{l}$

L = inductance in henries (H)
μ₀ = permeability of free space = 4π × 10^-7 H/m
K = Nagaoka coefficient^[2]
N = number of turns
A = area of cross-section of the coil in square metres (m²)
l = length of coil in metres (m)

Straight wire conductor
$L = l\left(\ln\frac{4l}{d}-1\right) \cdot 200 \times 10^{-9}$

L = inductance (H)
l = length of conductor (m)
d = diameter of conductor (m)

$L = 5.08 \cdot l\left(\ln\frac{4l}{d}-1\right)$

L = inductance (nH)
l = length of conductor (in)
d = diameter of conductor (in)

Short air-core cylindrical coil
$L=\frac{r^2N^2}{9r+10l}$

L = inductance (µH)
r = outer radius of coil (in)
l = length of coil (in)
N = number of turns

Multilayer air-core coil
$L = \frac{0.8r^2N^2}{6r+9l+10d}$

L = inductance (µH)
r = mean radius of coil (in)
l = physical length of coil winding (in)
N = number of turns
d = depth of coil (outer radius minus inner radius) (in)

Flat spiral air-core coil
$L=\frac{r^2N^2}{(2r+2.8d) \times 10^5}$

L = inductance (H)
r = mean radius of coil (m)
N = number of turns
d = depth of coil (outer radius minus inner radius) (m)

$L=\frac{r^2N^2}{8r+11d}$

L = inductance (µH)
r = mean radius of coil (in)
N = number of turns
d = depth of coil (outer radius minus inner radius) (in)

Toroidal core (circular cross-section)
$L=\mu_0\mu_r\frac{N^2r^2}{D}$

L = inductance (H)
μ₀ = permeability of free space = 4π × 10^-7 H/m
μ_r = relative permeability of core material
N = number of turns
r = radius of coil winding (m)
D = overall diameter of toroid (m)

[edit] See also

Electronic component
Capacitor
Resistor
Memristor
Electricity
Electronics
Gyrator
Inductance (including mutual inductance)
Induction coil
Induction cooking
Induction loop
Magnetic core
Saturable reactor
Transformer
Reactance (electronics)
RL circuit
RLC circuit

[edit] Synonyms

[edit] Notes

^ http://www.wonderquest.com/expounding-aircraft-electrical-systems.htm
^ ^a ^b Nagaoka, Hantaro. The Inductance Coefficients of Solenoids[1]. 27. Journal of the College of Science, Imperial University, Tokyo, Japan. p. 18.

[edit] External links

General

How stuff works The initial concept, made very simple
Capacitance and Inductance - A chapter from an online textbook
Spiral inductor models. Article on inductor characteristics and modeling.
Online coil inductance calculator. Online calculator calculates the inductance of conventional and toroidal coils using formulas 3, 4, 5, and 6, above.
AC circuits
[2]- Understanding coils and transforms

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Mar 16 Mon 2009 14:20
Deutsch Spule (Elektrotechnik) www.tool-tool.com

Bewise Inc. www.tool-tool.com Reference source from the internet.

In der Elektrotechnik sind Spulen Induktivitäten oder Drosseln. Sie sind Bestandteile elektrischer Baugruppen oder Geräte. Spulen sind passive elektrische Bauelemente.

Eine Spule ist ein Leiter (Draht, meist Kupferlackdraht oder Hochfrequenzlitze), der zu einer oder mehreren Windungen geformt ist. Die Windungsanordnung, ihr Durchmesser, das Wickel- und das Kernmaterial legen die Induktivität und weitere Eigenschaften der Spule fest.

Spulen

Spule als Gedruckte Schaltung mit Ferritkern

Aufbau, Bauteilbezeichnungen [Bearbeiten]

Schaltzeichen für Spulen, links nach IEC 617-4 (1983), rechts nach DIN EN 60617-4 (1997))

Eine klassische Spule ist ein um einen festen Körper (Spulenkörper) gewickelter Draht. Dieser Körper muss nicht zwingend vorhanden sein. Fehlt der Wickelkörper oder ist er aus nichtmagnetischem Material, spricht man im mechanischen bzw. elektrischen Sinne von Luftspulen. Der Spulenkörper dient hier meist nur der mechanischen Stabilisation des Drahtes und hat im Gegensatz zum Spulenkern keinen magnetischen Einfluss.

Spulen gibt es auch in flacher Spiralform und mit rechteckigem oder beliebig anders geformtem Spulenquerschnitt. Sie können als spiralförmige Leiterbahn auch direkt auf einer Leiterplatte realisiert sein.

Spulen besitzen eine bestimmte Induktivität, diese Induktivität kann ihr eigentlicher Zweck (z. B. Drosselspulen, Filterspulen) oder nur sekundäre Eigenschaft sein (z. B. Transformatoren, Zugmagnete, Relaisspulen).

Bei Elektromotoren werden die Spulen als Wicklung und z. B. bei der Pupinspule als Bespulte Leitung bezeichnet.

Neben dem aufgewickelten Draht und dem Spulenkörper weist die Spule im Inneren oft einen (Spulen-)Kern (s. u.) auf, um die Induktivität zu erhöhen.

Das Wort Spule weist auf die Bauform hin (siehe Spule (Rolle)).

Funktionsweise [Bearbeiten]

Eine Eigenschaft von Spulen ist deren Induktivität. Zur Steigerung der Induktivität wird der elektrische Leiter (Spulendraht) mit einer bestimmten Anzahl Windungen auf den Spulenkörper aufgebracht. Durch die magnetische Verkettung (Flussverkettung) der einzelnen Windungen untereinander, bedingt durch die räumlich nahe Anordnung der einzelnen Windungen, steigt die Induktivität von gewickelten Spulen im Quadrat mit der Windungsanzahl. Eine Verdoppelung der Windungszahl bei gleichen geometrischen Abmessungen bewirkt somit eine Vervierfachung der Induktivität.

Wird der Spulendraht von einem sich zeitlich ändernden Strom durchflossen, so entsteht um den elektrischen Leiter ein sich zeitlich ändernder magnetischer Fluss. Jede Änderung des Stromes erzeugt an den Enden des elektrischen Leiters eine Selbstinduktionsspannung. Diese Spannung ist dabei so gerichtet, dass sie ihrer Ursache (dem Strom) entgegen wirkt (Lenzsche Regel). Eine Zunahme der Änderungsrate des Stromes führt zur Erhöhung der Spannung, die dem Strom entgegen wirkt. Der Proportionalitätsfaktor zwischen sich zeitlich änderndem Strom durch den Leiter und der dabei entstehenden Selbstinduktionsspannung wird als Induktivität bezeichnet.

Reale Spulen besitzen neben der Induktivität auch noch andere, im Regelfall unerwünschte elektrische Eigenschaften wie einen elektrischen Widerstand oder parasitäre Kapazitäten.

Soll ein Gebilde aus einem langen aufgewickelten Draht dagegen eine besonders geringe Induktivität haben, müssen diese Gebilde bifilar mit einem gegenläufigen Draht gewickelt werden. So heben sich die entgegengesetzt gerichteten magnetischen Flüsse nahezu auf. Dieses Verfahren wird beispielsweise für manche Drahtwiderstände angewendet, um Widerstände mit besonders geringer parasitärer Induktivität zu erhalten.

Magnetfeld und Stromfluss [Bearbeiten]

Folgende Merksätze können benutzt werden, um festzustellen, welches Ende einer Spule bei einem durch sie fließenden Gleichstrom einen magnetischen Nord- und welches Ende einen Südpol bildet (als Stromrichtung ist die Technische Stromrichtung, d. h. vom Plus- zum Minus-Pol zu benutzen):

Schaut man auf ein Spulenende und wird dieses im Uhrzeigersinn vom elektrischen Strom umflossen, so entsteht dort ein magnetischer Südpol.
Schaut man auf ein Spulenende und wird dieses gegen den Uhrzeigersinn vom elektrischen Strom umflossen, so entsteht dort ein magnetischer Nordpol.

In einer Spule der Länge l mit n Windungen, in der ein elektrischer Strom I fließt, entsteht das Magnetfeld mit der Feldstärke H

$H = I \cdot \frac{n}{l}$ ,

und die Flussdichte B ergibt sich mit der vom Spulenkern (s. u.) abhängigen Materialkonstanten μ_r und der magnetischen Feldkonstanten μ₀ = 4 · π · 10⁻⁷ H/m zu

$B\,$
$=\mu_r \cdot \mu_0 \cdot H$

$=\mu_r \cdot \mu_0 \cdot I \cdot \frac{n}{l}$ .

Spulenkerne [Bearbeiten]

Spulenkerne haben die Aufgabe, die Induktivität der Spule zu verstärken oder zu verringern. Die durch einen magnetischen Kern erreichte Erhöhung der Induktivität führt zu einer Verringerung der für einen bestimmten Induktivitätswert erforderlichen Windungszahl bzw. Leiterlänge und damit zur Verringerung des störenden elektrischen Widerstandes der Spule.

Kerne aus elektrischen Leitern wie Kupfer oder Aluminium, die durch Feldverdrängung die Induktivität verringern, werden zur Abstimmung von Spulen verwendet.

Spule mit Eisenkern [Bearbeiten]

Spule mit Schalenkern aus Pulver-Pressstoff

Wird in eine Spule ein Eisenkern eingesetzt, so wird durch dessen ferromagnetische Eigenschaften die Permeabilität und damit auch die magnetische Flussdichte in der Spule erhöht. Somit kommt man mit wesentlich weniger Windungen aus, um eine benötigte Induktivität zu erreichen. Ab einer bestimmten materialabhängigen Flussdichte tritt eine Sättigungsmagnetisierung des Kerns auf.

Weil das Eisen des Kerns ein elektrischer Leiter ist, fließt in einer von Wechselstrom durchflossenen Spule mit Eisenkern in diesem ein Strom in einer quasi kurzgeschlossenen Windung, dieser heißt Wirbelstrom. Der Wirbelstrom wird geringer, wenn der Kern nicht aus einem Stück Eisen, sondern aus einem Stapel von Eisenblechen besteht, die voneinander, etwa durch eine Lackschicht, isoliert sind. Verhindert wird der Wirbelstrom durch einen Spulenkern aus elektrisch nichtleitendem Material wie beispielsweise Ferrit oder Pulver-Pressstoff.

Diese magnetischen Kernmaterialien weisen typischerweise einen Hysterese-Effekt auf, der zu elektrischen Verlusten führt, weil bei jeder Periode eines Wechselstroms der Kern ummagnetisiert werden muss. Außerdem kommt dadurch eine Verformung der Stromkurve mit zusätzlichen Spitzen in jeder Periode zustande, die bei manchen Anwendungen unwillkommen ist. Die Verluste, die durch Wirbelströme und Hysterese auftreten, nennt man Eisenverluste.

Auch wird das Einschaltverhalten der Induktivität wesentlich komplexer, weil, je nach Zustand des Kerns vor dem Einschalten, gar keine Magnetisierung besteht oder als Remanenz (siehe auch bei Hysterese) schon eine Magnetisierung besteht, die entweder der Strompolarität entsprechen oder auch entgegengesetzt sein kann und dann durch den Strom erst ummagnetisiert werden muss. Diese Effekte führen dazu, dass im Extremfall beim Einschalten Sicherungen ansprechen, obwohl nominell gar nicht zu viel Last angeschlossen ist. Bei Induktivitäten in Wechselstrom-Leistungsanwendungen muss also für den Einschaltfall besondere Vorsorge getroffen werden, siehe beispielsweise bei Trafoschaltrelais. Bei Kleinsignalanwendungen führen die Hystereseeffkte lediglich zu einer verminderten Güte des Bauteils.

Die Elementarmagnete im Eisenkern richten sich nach den Polen der Spule. Ist der Nordpol links, so sind die Nordpole der Elementarmagneten ebnfalls links. Die Feldlinien treten demnach am Nordpol aus und dringen am Südpol wieder in das Spuleninnere ein. Im Spuleninneren verlaufen die Feldlinien von Süd nach Nord. Bei einer langgestreckten Spule mit vielen Windungen ist das Magnetfeld im Inneren homogen, es ähnelt dem Magnetfeld zwischen den Schenkeln eines Hufeisenmagnet. Im Außenraum ähnelt das Spulenfeld dem eines Stabmagneten.

Kerne bei Hochfrequenzspulen [Bearbeiten]

Meist wird für diesen Zweck ein Kern aus gepresstem magnetischem Pulver (Pulverkern) oder Ferrit verwendet. Zur Filterung hochfrequenter Störungen werden unter anderem Toroidspulen bzw. Ringkerndrosseln eingesetzt.

Bei abstimmbaren Spulen werden Ferritkerne mit einem Gewinde verwendet: durch Hinein- oder Herausschrauben kann die Induktivität einer solchen Spule erhöht bzw. vermindert werden. Wenn eine HF-Spule einen Kern aus Aluminium (oder einem anderen elektrisch leitfähigen Material) zum Abgleich hat, verringert das Hineindrehen des Kerns die Induktivität. Das kommt daher, dass der Kern wie eine kurzgeschlossene Sekundärwicklung eines Transformators wirkt. Ein tieferes Hineindrehen bewirkt eine Verdrängung des Magnetfeldes der Spule.

Hochfrequenzspulen [Bearbeiten]

Kreuzwickelspule mit HF-Litze und trimmbarem Eisenkern für den Mittelwellenbereich

Mit zunehmender Frequenz werden die Ströme immer mehr an die Oberfläche des Drahtes verdrängt (Skineffekt). Die Drahtoberfläche entscheidet dann zunehmend über die Güte der Spule. Ab ca. 100 kHz verwendet man zur Verringerung der Verluste daher oft Hochfrequenzlitze als Wickelmaterial; sie besteht aus mehreren, voneinander isolierten feinen Drähten. Ab etwa 50 MHz werden die Spulen meist freitragend mit dickerem Draht ausgeführt. Eine versilberte Oberfläche kann die Verluste zusätzlich vermindern. Kerne für Hochfrequenzspulen bestehen aus einem ferromagnetischen, elektrisch nichtleitenden Material. Damit werden Wirbelströme im Kern verhindert. Auch mit der Bauform kann man eine Spule hochfrequenztauglich machen, indem man bei solchen mit hohen Windungszahlen (beispielsweise für den Mittelwellenbereich) parasitäre Kapazitäten durch besondere Wickelformen verringert (Waben-, Korbboden- oder Kreuzwickelspulen).

Spulen für Oszillatoren [Bearbeiten]

Spulen in Oszillatoren sollen ihre Induktivität möglichst genau einhalten. Luftspulen können bei Erschütterung eine Frequenzmodulation verursachen. Sie werden deshalb auf einen Spulenkörper gewickelt, mit Lack oder Kleber fixiert oder ganz in Wachs eingebettet.

Wechselstromverhalten [Bearbeiten]

Phasenverschiebung zwischen Strom und Spannung durch induktive Belastung

Wird eine Spule an sinusförmige Wechselspannung angelegt, so wechseln der Strom und das Magnetfeld ebenfalls periodisch ihre Richtung. Die Stromänderung verursacht durch Selbstinduktion eine Spannung an den Klemmen. Bei einem Transformator kann sie an einer weiteren Wicklung entnommen werden.

Der Spulenstrom i(t) und die durch Selbstinduktion an den Klemmen erzeugte Spannung u(t) folgen bei einer idealen Spule der Gleichung

$u(t) = L \cdot \frac{\mathrm{d} i(t)}{\mathrm{d}t}$ ,

wobei t die Zeit und L die Selbstinduktivität der Spule ist.

Hier sind Strom und Spannung, wie bei passiven Bauelementen üblich, im Verbraucherzählpfeilsystem angegeben.

Verbraucherzählpfeilsystem: Strom- und Spannungspfeile zeigen im Bauelement in dieselbe Richtung

In Schulliteratur ist ebenfalls der Begriff „Selbstinduktionsspannung“ mit der Bezeichnung $u_i(t) = - L \cdot \frac{\mathrm{d}i(t)}{\mathrm{d}t}$ ^[1] geläufig. Das zugrundeliegende Modell ist jedoch nicht die Netzwerktheorie, sondern die allgemeiner gefasste Feldtheorie. Die induzierte Spannung bezeichnet das Kreisintegral des elektrischen Feldes entlang eines geschlossenen Weges, der die Spulenwicklungen enthält. Man spricht auch von der sogenannten Umlaufspannung u_i(t), für die gilt:

$u_i(t) = \oint_{C} \vec{E} \cdot \mathrm{d} \vec{r} = - N \cdot \frac{\mathrm{d}\Phi(t)}{\mathrm{d}t}$

Dabei wird wie in physikalischen Gleichungen üblich angenommen, dass die genannten Größen rechtshändig zueinander zugeordnet sind, d. h. die Richtungen von elektrischem Feld, Stromflussrichtung und Integrationsweg stehen wie in der Abbildung gezeigt rechtshändig zum magnetischen Feld.

Der Zusammenhang zwischen der induzierten Spannung u_i(t) und der Klemmenspannung u(t) wird anhand der beigefügten Abbildung erläutert:

Zusammenhang von Selbstinduktionsspannung und Klemmenspannung

Integriert man das elektrische Feld $\vec E$ über den mit gestrichelten Linien eingezeichneten Weg, so addieren sich dabei die in den Spulenwicklungen auftretenden Spannungen mit der Klemmenspannung. Sofern man jedoch von einer ideal leitfähigen Spulenwicklung ausgeht, kann innerhalb des Leiters keine elektrische Spannung entstehen (Feldfreiheit im metallischen Leiter). Die induzierte Spannung $- N \cdot \frac{\mathrm{d}\Phi(t)}{\mathrm{d}t}$ muss dementsprechend als Klemmenspannung zwischen den Spulenklemmen abfallen. Die Richtung dieser Spannung entspricht dem gewählten Integrationsweg und verläuft im Beispiel von unten nach oben. Im Netzwerkmodell mit dem Verbraucherzählpfeilsystem ergibt sich ein positives Vorzeichen, da der Zählpfeil für die dort gewählte Klemmenspannung dem Integrationsweg entgegengesetzt von oben nach unten verläuft.

Da der Strom wegen des Energietransports in das magnetische Feld nur allmählich anwachsen bzw. abfallen kann, folgt er dem Verlauf der Spannung stets mit zeitlicher Verzögerung; er ist phasenverschoben. Unter idealen Bedingungen (bei vernachlässigbar kleinem ohmschem Widerstand) eilt die Wechselspannung dem Strom um 90° voraus. Es besteht eine Trägheit der Spule gegen Stromänderungen. (Merksatz: „Bei Induktivitäten die Ströme sich verspäten“.) Mit der Stromänderung ist gemäß der Gleichung

$E_\mathrm{mag} = \tfrac{1}{2} L I^2$

eine Änderung der magnetischen Spulenenergie E_mag (und somit ein Energietransport) verbunden. Rechnerisch folgt die Phasenverschiebung aus den Ableitungsregeln für trigonometrische Funktionen: Wird beispielsweise ein sinusförmiger Strom

$i(t) = I_0 \cdot \sin(\omega t)$

in die Spule eingeprägt, so ergibt sich die Spannung an der Spule durch mathematische Ableitung zu

$u(t) = L \cdot \frac{\mathrm{d} i(t)}{\mathrm{d}t} = \omega L \cdot I_0 \cdot \cos(\omega t)$ .

Das Verhältnis von maximaler Spulenspannung und maximalem Spulenstrom beträgt bei sinusförmiger Anregung

$\frac{U_0}{I_0} = \omega L$ .

Der Spule kann so ein komplexer Wechselstromwiderstand (Impedanz): $\underline {Z} = \mathrm{j} \omega L$ zugeordnet werden, der jedoch im Gegensatz zu einem ohmschen Widerstand keine Leistung in Wärme (Verlustleistung) umsetzt. Das rührt daher, dass während einer Viertelperiode von der Spule Energie aufgenommen und in der nächsten Viertelperiode wieder abgegeben wird. Dadurch pendelt die Energie nur hin und her, ohne verbraucht zu werden. Man nennt diese spezielle Form von Widerstand Blindwiderstand und den Strom Blindstrom.

Für eine Spule der Induktivität L und einen Wechselstrom der Frequenz f errechnet sich der Blindwiderstand (Reaktanz)

$X = \Im{(\underline{Z})}$

zu

$X = 2 \pi f \cdot L = \omega \cdot L$

mit der Dimension [V/A].

ω = 2πf nennt man die Winkelfrequenz oder auch Kreisfrequenz.

Der Blindwiderstand wächst mit steigender Frequenz, wobei der ohmsche Drahtwiderstand gleich bleibt. Daher hat eine für Wechselspannung konzipierte Spule an einer gleichgroßen Gleichspannung (f = 0 Hz) einen sehr viel geringeren Widerstand, da nur noch der Drahtwiderstand den Strom behindert.

Parasitärelemente [Bearbeiten]

Reale Spulen zeigen im Wechselstromkreis ein Phänomen, das mit Hilfe des topologischen Zeigerdiagramms erklärt werden kann. Der äquivalente ohmsche Serienwiderstand (ESR), der als Kupferwiderstand mit Gleichstrom bestimmt werden kann, scheint im Wechselstrombetrieb höher zu sein. Gründe dafür sind bauart- und materialbedingte zusätzliche Verluste (Wirbelstrom- und Ummagnetisierungsverluste im Kern, Skineffekt und Proximity Effect). Sie führen dazu, dass eine geringere Veränderung der Phasenlage des Stromes bzw ein höherer Wirkanteil der elektrischen Leistung auftritt, als es aufgrund des Kupferwiderstandes zu erwarten wäre.

Scheinbar ändert sich demnach der ESR (der Realteil von Z) gegenüber dem mit Gleichstrom bestimmten Wert. Diese parasitären Komponenten können zum Beispiel mit einer Messbrücke nachgewiesen werden, die in der Lage ist, Real- und Imaginärteil getrennt zu messen.

Ein weiterer parasitärer Effekt sind die Kapazitäten zwischen den Wicklungen und Anschlüssen. Diese Parasitärkapazitäten der Spule führen bei Erhöhung der Frequenz zunächst zu einem steileren Anstieg des Scheinwiderstandes, als es aufgrund der Induktivität zu erwarten wäre. Bei der Eigenresonanzfrequenz erlangt er einen Maximalwert, um anschließend wieder zu sinken – nun zeigt die Spule kapazitives Verhalten.

Dieses Phänomen ist nachteilig bei Filter- und Entstöranwendungen, wo es erforderlich ist, dass auch sehr hohe Frequenzen durch die Spule noch ausreichend gedämpft werden. Man verringert den Effekt, indem man die Spule einlagig und langgestreckt oder kreuzlagig ausführt. Auch das verteilte Nacheinander-Bewickeln mehrerer Kammern ist üblich. Oft muss man bei Filteranwendungen (z. B. Netzfilter) verschiedene Spulenbauformen kombinieren, um einerseits hohe Induktivität und andererseits eine geringe parasitäre Kapazität zu erzielen.

Siehe auch: Blindleistungskompensation und komplexe Wechselstromrechnung

Zu- und Abschaltvorgänge bei Gleichspannung [Bearbeiten]

Zu- und Abschaltvorgang an einer realen Spule (R_Draht = 10 Ω) mit „idealer“ Freilaufdiode; oben: Selbstinduktionsspannung, Mitte: Strom, unten: Speisespannung; die Zeitachse ist in auf die Zeitkonstante normierten Einheiten skaliert

Schaltet man eine reale (d. h. verlustbehaftete) Spule an eine Gleichspannung, nimmt der Strom folgenden zeitlichen Verlauf:

$i(t) = I_0 \cdot (1 - \mathrm{e}^{-{t \over \tau}})=\frac{U_0}{R} \cdot (1 - \mathrm{e}^{-{tR \over L}})$

mit

$\tau = \tfrac{L}{R}$ (Zeitkonstante)

L – Induktivität der Spule
t – Zeit
R – Kupferwiderstand der Spule
$I_0 = \tfrac{U_0}{R}$
U₀ – Gleichspannung

Dieser Zusammenhang zeigt, dass sich der in einer Spule fließende Strom nicht sprunghaft ändern kann. Beim Einschalten eines Gleichstromkreises mit einer Spule verhindert die der Betriebsspannung entgegenwirkende Induktionsspannung einen raschen Stromanstieg. Dieser erfolgt nach einer Exponentialfunktion. Wenn R einen hohen Wert annimmt, wird τ kleiner, somit ist der Stromanstieg auf den Endwert I₀ eher abgeschlossen.

Ein plötzliches Abschalten des Spulenstromes ( $-\mathrm{d}i/\mathrm{d}t \to \infty$ ) ist nicht möglich. In der Realität entsteht beim Versuch, den Strom zu unterbrechen, eine Spannungsspitze umgekehrter Polarität, deren Höhe nur von der parasitären Kapazität der Spule und anderen spannungsbegrenzenden Effekten (elektrischer Durchbruch, Überschläge, Schaltlichtbogen) abhängt. Sie können Schäden durch Überspannung verursachen.

Mit Gleichstrom betriebene Spulen werden daher oft durch eine parallelgeschaltete Freilaufdiode geschützt, die beim Abschalten des (Speise-)Stromes das Weiterfließen des (Spulen-)Stromes ermöglicht und die in der Spule gespeicherte magnetische Energie

$W = \tfrac{1}{2} L \; I^2$

größtenteils im Spulendraht und zu einem kleinen Teil in der Diode thermisch umsetzt. Die hohe Spannungsspitze an den Anschlüssen der Spule wird damit verhindert, allerdings dauert es länger, bis der Strom auf geringe Werte abgesunken ist.

Für den Abschaltvorgang mit einer „idealen“ Freilaufdiode gilt:

$i(t)=I_0 \cdot e^{-{t \over \tau}}$

Die Zeitkonstante τ ist der Quotient aus Induktivität und Drahtwiderstand L/R_L, sie kann bei großen Induktivitäten hoher Güte einige Sekunden betragen. Die Zeitkonstante gleicht derjenigen zu Beginn der Einschaltkurve und lässt sich durch eine an den Beginn des Strom/Zeitverlaufs angelegte Tangente bestimmen, bei der diese den Endwert I₀ schneidet. Zu diesem Zeitpunkt t = τ beträgt der Wert der Stromanstiegskurve

$I(t) = 0{,}6321 \cdot I_0$

Die Steilheit der Tangente im Nullpunkt errechnet sich aus

$\tan \alpha = \tfrac{1}{\tau} I_0 \$ [A/s]

Diese Stromanstiegsgeschwindigkeit di/dt (oft angegeben in A/µs) ist ein wichtiger Wert für eine Vielzahl von Anwendungen, wie Thyristorschalter, Schaltnetzteile, Spannungswandler, Entstörglieder. Hier werden überall Spulen zur Energiespeicherung oder zur Begrenzung der Stromanstiegsgeschwindigkeit eingesetzt. Der Spulenstrom steigt in der Praxis aufgrund des meist relativ kleinen Realteiles der Spulenimpedanz zu Beginn fast linear mit der Zeit an. Theoretisch würde der Strom durch eine Spule an konstanter Spannung immer weiter steigen, die gespeicherte Energie würde immer schneller (proportional zum Quadrat der Zeit) größer werden. In der Praxis wird die Energie, die in einer Spule gespeichert werden kann, aus folgenden Gründen begrenzt:

Das gegebenenfalls vorhandene Kernmaterial gerät ab einer bestimmten Flussdichte in Sättigung, wodurch die Induktivität stark sinkt (das führt zu einem schnellen und starken Stromanstieg).
Mit steigender Stromstärke durch die Spule fällt am elektrische Widerstand R des Spulendrahtes schließlich die gesamte Spannung ab, der Strom kann sich nicht weiter erhöhen.

Es wird immer mehr elektrische Leistung in Wärmeleistung (I²·R) umgewandelt und es droht eine Überhitzung.

Aufgrund ihrer oben beschriebenen Eigenschaften können periodisch geschaltete Spulen zur Erzeugung von hohen Spannungen aus kleinen Spannungen benutzt werden (z. B. Zündspule, Spannungswandler, Funkeninduktor, Aufwärtswandler, Schaltregler).

Umgekehrt können sie zur Strombegrenzung in Wechselspannungskreisen (Vorschaltdrossel, Kommutatordrossel), und zur verlustarmen Herabsetzung von Spannungen (Abwärtswandler) und Glättung von Strömen (Siebdrossel) eingesetzt werden.

Bedruckung / Farbcodes [Bearbeiten]

Um die Induktivität einer Spule anzugeben, werden manchmal Farbcodes nach folgendem Schema verwendet:

Farbcode für Spulen gemäß IEC 62-1974

Farbe
Induktivität in µH
Toleranz

1. Ring
2. Ring
3. Ring
(Multiplikator)
4. Ring

„keine“
×
—
—
—
±20 %

silber
—
—
1·10⁻² = 0,01
±10 %

gold
—
—
1·10⁻¹ = 0,1
±5 %

schwarz
0
0
1·10⁰ = 1
—

braun
1
1
1·10¹ = 10
—

rot
2
2
1·10² = 100
—

orange
3
3
1·10³ = 1.000
—

gelb
4
4
1·10⁴ = 10.000
—

grün
5
5
1·10⁵ = 100.000
—

blau
6
6
1·10⁶ = 1.000.000
—

violett
7
7
1·10⁷ = 10.000.000
—

grau
8
8
1·10⁸ = 100.000.000
—

weiß
9
9
1·10⁹ = 1.000.000.000
—

Farbe
1. Ring
(breit)
2. bis 4. Ring
Ziffer
5. Ring
Multiplikator
6. Ring
Toleranz

„keine“
—
—
—
±20 %

silber
Anfang
—
—
±10 %

gold
—
Komma
—
±5 %

schwarz
—
0
10⁰ µH
—

braun
—
1
10¹ µH
±1 %

rot
—
2
10² µH
±2 %

orange
—
3
10³ µH
—

gelb
—
4
10⁴ µH
—

grün
—
5
10⁵ µH
±0,5 %

blau
—
6
10⁶ µH
—

violett
—
7
10⁷ µH
—

grau
—
8
10⁸ µH
—

weiß
—
9
10⁹ µH
—

Die 3. Ziffer ist optional.

Alternativ wird die Induktivität (vor allem bei höheren Werten) durch eine dreistellige Zahl angegeben. Dabei bedeuten

die ersten beiden Ziffern den Wert in µH
die dritte Ziffer die Anzahl der angehängten Nullen

Beispiel: Der Aufdruck „472“ bedeutet 4,7 mH.

Anwendungen [Bearbeiten]

Spulen mit fester Induktivität [Bearbeiten]

Spulen werden u. a. in Transformatoren, Elektromagneten, Dosierpumpen, Relais, Schaltschützen, elektrodynamischen und elektromagnetischen Lautsprechern, dynamischen Mikrofonen (Tauchspule), Stromwandlern, als Ablenkspule an Fernsehbildröhren, in Galvanometern, Drehspulmesswerken, Dreheisenmesswerken, Elektromotoren, Zündspulen und analoganzeigenden Quarzuhren eingesetzt. In elektronischen Schaltungen kommen sie u. a. als frequenzbestimmendes Element oder zu Siebungszwecken zum Einsatz.

Gewundene elektrische Leiter in Drahtwiderständen, Wendelantennen, Spiralantennen, Wanderfeldröhren und Glühwendeln werden nicht als Spulen bezeichnet.

Im Kreis verlaufende Luftspulen werden nach dem mathematischen Körper auch als Toroid bezeichnet.

Veränderliche Induktivitäten [Bearbeiten]

Variometer [Bearbeiten]

UKW-Tuner mit Variometer-Abstimmung

Eine in der Messtechnik und historischen Funktechnik verwendete einstellbare Induktivität wird als Variometer bezeichnet und besteht in einer Ausführungsform aus zwei ineinander geschobenen und hintereinandergeschalteten kernlosen Spulen. Die innere Spule ist drehbar (oder entlang der Längsachse parallel verschiebbar) gelagert. Das Induktivitäts-Maximum wird erreicht, wenn die Windungsebenen parallel und gleichsinnig vom Strom durchflossen werden.

Eine weitere Bauform von Variometern beruht auf der Bewegung von Kernen im Inneren von Zylinderspulen. Diese Kerne können entweder aus hochpermeablem Material sein (Induktivität erhöht sich beim Hineinbewegen) oder aus gut leitendem Metall (Induktivität verringert sich beim Hineinbewegen durch Feldverdrängung). Die erste Variante wird im Lang-, Mittel- und Kurzwellenbereich eingesetzt, die zweite im UKW-Bereich. In der 1960er und 1970er Jahren wurden auf diese Weise z. B. in Autoradios mechanische Senderspeicher mit mehreren Wahltasten realisiert.

Transduktoren [Bearbeiten]

Transduktoren gestatten die Veränderung der Induktivität mittels eines durch eine zweite Wicklung fließenden Gleichstromes. Sie werden auch als Magnetverstärker bezeichnet und beruhen auf der Sättigung des Kernes durch die Vormagnetisierung aufgrund des steuernden Gleichstromes. Durch diese verringert sich die Permeabilität des Kernes und damit die Induktivität der Spule.

Einzelnachweise [Bearbeiten]

↑ Das große Tafelwerk interaktiv. 1. Auflage. Cornelsen, Berlin 2003, ISBN 3-464-57143-2. S. 110

Siehe auch [Bearbeiten]

Generator
Schwingkreis (mit Kapazität)
Detektorempfänger
Die Abhängigkeit des Blindwiderstandes einer Spule von der Frequenz wird zur Trennung oder Zusammenführung von Signalen unterschiedlicher Frequenz verwendet; siehe Tiefpass, Hochpass, Bandpass, Frequenzweiche, Antennenweiche

Weblinks [Bearbeiten]

Commons: Spule – Bilder, Videos und Audiodateien
Wikibooks: Spule als Energiespeicher – einfach erklärt – Lern- und Lehrmaterialien
Wikibooks: Feld einer Zylinderspule – mathematisch erklärt – Lern- und Lehrmaterialien
Anleitung zur Bestimmung der Induktivität einer Spule mit einfachem Messverfahren

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BW специализируется в научных исследованиях и разработках, и снабжаем самым высокотехнологичным карбидовым материалом для поставки режущих / фрезеровочных инструментов для почвы, воздушного пространства и электронной индустрии. В нашу основную продукцию входит твердый карбид / быстрорежущая сталь, а также двигатели, микроэлектрические дрели, IC картонорезальные машины, фрезы для гравирования, режущие пилы, фрезеры-расширители, фрезеры-расширители с резцом, дрели, резаки форм для шлицевого вала / звездочки роликовой цепи, и специальные нано инструменты. Пожалуйста, посетите сайт www.tool-tool.com для получения большей информации.

BW is specialized in R&D and sourcing the most advanced carbide material with high-tech coating to supply cutting / milling tool for mould & die, aero space and electronic industry. Our main products include solid carbide / HSS end mills, micro electronic drill, IC card cutter, engraving cutter, shell end mills, cutting saw, reamer, thread reamer, leading drill, involute gear cutter for spur wheel, rack and worm milling cutter, thread milling cutter, form cutters for spline shaft/roller chain sprocket, and special tool, with nano grade. Please visit our web www.tool-tool.com for more info.

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個人分類：學術研究

Mar 16 Mon 2009 14:10
Dansk Elektrisk spole www.tool-tool.com

Bewise Inc. www.tool-tool.com Reference source from the internet.

Billede af spoler. Fra venstre; luftspole til højttalerdelefilter. Solenoide - har massiv jernkerne. Radio højfrekvensspole variabel via ferritkernen. Radio højfrekvensspole med ferrit-klokke (rødmalet).

Enhver praktisk elektrisk leder besidder i større eller mindre grad en egenskab, som kaldes for selvinduktion (en fysisk størrelse som måles i henry). En spole er en elektrisk leder, som er fremstillet til at have en ganske bestemt selvinduktion.

Indholdsfortegnelse

[skjul]

[redigér] Sådan virker en spole

Da man får mest selvinduktion ud af et givet stykke elektrisk leder ved at vikle det sammen til en "spole", består en elektrisk spole netop af et stykke sammenviklet metaltråd (minder lidt om en skruefjeder).

En spole kan enten være lavet af kraftig ("stiv") metaltråd, som er viklet om en "spoleform" uden andet end tråden selv til at bære vægten (en såkaldt luftspole). Eller en noget tyndere tråd kan være viklet på et lille "bærende stativ" af f.eks. plast.

I midten af spolen kan man anbringe en kerne af enten jern eller ferrit - tilstedeværelsen af en sådan kerne forøger spolens selvinduktion.

[redigér] Spoler og jævnspænding

Forbinder man de to frie ender af lederen i en spole til en jævnspændingskilde, begynder strømmen ikke at flyde med det samme - i stedet stiger strømstyrken lineært (ideel spole uden ohmsk modstand og med en ideel jævnspændingskilde). Hvis spolen har en ohmsk modstand, hvad de fleste spoler har, så vil strømmen først stige lineært og senere stige asymptotisk mod en maksimal værdi bestemt af spændingskilden og spolens modstand.

Mens strømstyrken tiltager, opbygger spolen et magnetfelt - man kan efterfølgende demonstrere at spolen er magnetisk, og af samme grund kaldes en jævnspændingsspole med kerne også for en elektromagnet (eller solenoide).

[redigér] Spoler og vekselspænding

Forbindes spolen til en vekselspændingskilde (hvis spændingen skifter retning med en vis frekvens eller "regelmæssig hyppighed"), behøver strømstyrken gennem spolen ikke nå op i nærheden af den maksimalt mulige. Dog løber der en vis vekselstrøm i spolen, og spolen fungerer i denne situation som en slags "modstand" (reaktans), hvis størrelse afhænger af to ting:

Spolens selvinduktion; jo større selvinduktion, desto større modstand udvirker spolen
Vekselspændingens frekvens; jo højere frekvens, desto større modstand for en given selvinduktion. På grund af denne egenskab bruges spoler ofte i radioteknikken sammen med kondensatorer (kombinationen kaldes svingningskredse) til at gøre f.eks. en radiomodtager følsom for signaler indenfor et bestemt frekvensinterval (radiokanal), og så ufølsom som muligt for alle andre frekvenser.

Formlen for en ideel spoles reaktive modstand (reaktive del af impedansen) som funktion af frekvensen:

X_L = ωL = 2πfL

Faktisk er det mest rigtigt at angive spolens reaktive modstand med komplekse tal:

Z = (0 + iωL) = (0 + i2πfL)

Hvor X_L er den induktive reaktans, Z er spolens impedans, ω er vinkelfrekvensen, f er frekvensen i hertz og L er spolens induktans i henry.

[redigér] Mål og egenskaber for spoler

Selvinduktionen i en spole bestemmes af fire egenskaber ved spolen:

Spolens vindingers diameter; jo større diameter, desto større selvinduktion.
Antallet af vindinger; selvinduktion stiger stort set med vindingsantallet i anden (n²).
Spolens bredde - jo smallere plads vindingerne er lagt i - desto højere selvinduktion.
Det materiale der tjener som evt. "kerne" i spolen. Nogle materialer vil øge selvinduktionen med helt op til 10.000 gange (jern).

Ved at anvende en tynd tråd kan man vikle en spole med mange vindinger i samme rumfang i forhold til en spole med tykkere tråd, og derigennem opnå en stor selvinduktion. Imidlertid vil der være en vis (utilsigtet) elektrisk modstand, og denne såkaldte tabsmodstand "forringer" spolen på to måder:

Når spolen gennemløbes af en elektrisk strøm, går en del af den elektriske energi tabt som varme, der udvikles i spoletråden på grund af den utilsigtede ohmske modstand. Den elektriske energi tabes proportionalt med strømmen i anden (I²).
Bruges spolen i føromtalte radiomodtager, bliver det afstemte kredsløb mindre følsomt over for signaler med den ønskede frekvens, og for følsomt overfor signaler der frekvensmæssigt ligger tæt på den ønskede frekvens. Man siger også at spolens godhed mindskes.

[redigér] Se også

[redigér] Eksterne henvisninger

Erik Hansen: Beregning af en luftspoles størrelse (selvinduktionen)
Formelsamling: Elektronik: Spole
coilws.com: Air coil inductors (pdf) (formel og kriterier)

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弊社は各領域に供給できる内容は：

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Bewise Inc. talaşlı imalat sanayinde en fazla kullanılan ve üç eksende (x,y,z) talaş kaldırabilen freze takımlarından olan Parmak Freze imalatçısıdır. Çok geniş ürün yelpazesine sahip olan firmanın başlıca ürünlerini Karbür Parmak Frezeler, Kalıpçı Frezeleri, Kaba Talaş Frezeleri, Konik Alın Frezeler, Köşe Radyüs Frezeler, İki Ağızlı Kısa ve Uzun Küresel Frezeler, İç Bükey Frezeler vb. şeklinde sıralayabiliriz.

BW специализируется в научных исследованиях и разработках, и снабжаем самым высокотехнологичным карбидовым материалом для поставки режущих / фрезеровочных инструментов для почвы, воздушного пространства и электронной индустрии. В нашу основную продукцию входит твердый карбид / быстрорежущая сталь, а также двигатели, микроэлектрические дрели, IC картонорезальные машины, фрезы для гравирования, режущие пилы, фрезеры-расширители, фрезеры-расширители с резцом, дрели, резаки форм для шлицевого вала / звездочки роликовой цепи, и специальные нано инструменты. Пожалуйста, посетите сайт www.tool-tool.com для получения большей информации.

BW is specialized in R&D and sourcing the most advanced carbide material with high-tech coating to supply cutting / milling tool for mould & die, aero space and electronic industry. Our main products include solid carbide / HSS end mills, micro electronic drill, IC card cutter, engraving cutter, shell end mills, cutting saw, reamer, thread reamer, leading drill, involute gear cutter for spur wheel, rack and worm milling cutter, thread milling cutter, form cutters for spline shaft/roller chain sprocket, and special tool, with nano grade. Please visit our web www.tool-tool.com for more info.

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個人分類：學術研究

Mar 16 Mon 2009 14:02
Česky Cívka www.tool-tool.com

Bewise Inc. www.tool-tool.com Reference source from the internet.

Z Wikipedie, otevřené encyklopedie

Skočit na: Navigace, Hledání

vysokofrekvenční cívka

Projekt Wikiknihy nabízí dokument na téma:

Praktická elektronika

Tento článek pojednává o elektrotechnické součástce. O cívce jakožto načiní a technické pomůcce k navíjení pojednává článek cívka (náčiní).

Cívka je elektrotechnická součástka používaná v elektrických obvodech:

k vytvoření magnetického pole elektrického proudu, které se dále využívá k působení magnetickou silou - cívka slouží jako elektromagnet,
k indukci elektrického proudu proměnným magnetickým polem - cívka slouží jako induktor (nositel indukčnosti).

Obsah

[skrýt]

[editovat] Stavba cívky

Cívka se skládá z vodiče navinutého na izolační nosnou kostru. Vinutí může být jednovrstvé nebo vícevrstvé. V případě vícevrstvých cívek je třeba použít tzv. křížové vinutí, aby se omezila vlastní elektrická kapacita cívky. Navinutý vodič může být i samonosný - bez kostry.

Vodič v cívce má mít co nejmenší rezistivitu, aby v cívce nedocházelo k velkým tepelným ztrátám. Nejčasteji používaným materiálem je měď.

Ke zvětšení magnetických vlastností se dovnitř cívky vkládá jádro z magneticky měkké oceli, tzn. z feromagnetické látky s malou remanentní magnetizací. K omezení vzniku vířivých proudů v jádře se jádro skládá z několika vrstev oddělených izolantem nebo z jemných železných částeček spojených izolační hmotou (tzv. železové jádro).

[editovat] Druhy cívek

Podle rozměrů a tvaru lze rozlišit obyčejnou cívku, solenoid - velmi dlouhá cívka, toroid - cívka stočená do kruhu.

Cívky lze rozdělit podle frekvence střídavého proudu, pro kterou je určena - nízkofrekvenční cívky a vysokofrekvenční cívky.

[editovat] Parametry cívky

Počet závitů
Geometrické vlastnosti (počet závitů na jednotku délky, délka, obsah průřezu)
Indukčnost - vyjadřuje velikost magnetického indukčního toku při jednotkovém elektrickém proudu
Maximální zatížení - největší možný výkon elektrického proudu nepoškozující cívku
Maximální proud - největší proud, který může procházet cívkou

[editovat] Cívka v elektrickém obvodu

[editovat] Elektrotechnická značka

[editovat] Cívka ve stejnosměrném obvodu

V obvodu stálého stejnosměrného proudu se cívka projevuje pouze svým elektrickým odporem.

Kolem cívky se průchodem stejnosměrného proudu vytváří stálé magnetické pole. Magnetický indukční tok závisí přímo úměrně na indukčnosti cívky a velikosti proudu. Indukčnost cívky a tím i magnetické pole je možno zesílit vložením jádra-magnetického obvodu do cívky.

[editovat] Cívka ve střídavém obvodu

V obvodu střídavého proudu vzniká kolem cívky proměnné magnetické pole, které v cívce indukuje elektromotorické napětí. Indukované napětí působí vždy proti změnám, které je vyvolaly (Lenzův zákon), což má za následek vznik impedance, u cívky nazývané induktance, tj. odpor cívky proti průchodu střídavého proudu. Induktance závisí přímo úměrně na indukčnosti cívky a frekvenci střídavého proudu.

Cívka rovněž způsobuje fázový posuv střídavého proudu oproti střídavému napětí o π/2 neboli 1/4 periody.

Proměnného magnetického pole kolem cívky se využívá také v transformátorech při transformaci střídavého elektrického proudu a napětí mezi dvěma obvody. Způsob a velikost transformace ovlivňuje poměr počtu závitů sekundární a primární cívky transformátoru, celková energie transformace je však také výrazně limitována celkovou velikostí a kvalitou magnetického obvodu transformátoru.

[editovat] Cívka v kmitavém obvodu

Důležitou úlohu hraje cívka u elektromagnetického kmitání (rezonance). To vzniká v obvodu s kondenzátorem a cívkou (LC obvody), kde se periodicky opakuje přeměna elektrické energie na magnetickou a opačně. Frekvence elektromagnetického kmitání závisí mj. také na indukčnosti cívky.

[editovat] Spojování cívek

Při sériovém zapojení cívek se zvětšuje celková indukčnost:

L = L₁ + L₂ + ...,

při paralelním zapojení se celková indukčnost zmenšuje:

$\frac {1}{L} = \frac {1}{L_1} + \frac {1}{L_2} + ...$

[editovat] Použití cívky

Cívku lze používat jako samostatnou součástku (elektromagnet, tlumivka) nebo jako součást složeného elektrického zařízení (elektromagnetické relé, transformátor, reproduktor).

Různá provedení cívek

Cívka jako elektromagnet - využívá se magnetická síla magnetického pole kolem cívky v zařízeních jako např.
- elektromotor
- zvonek
- reproduktor
- elektromagnetické relé
- elektromagnetický jeřáb
- vychylovací cívky v monitorech
- zapisovací hlavičky v pevných discích
- deprézské měřící přístroje (galvanometr, ampérmetr, voltmetr, ad.)

Výhodou elektromagnetu je to, že magnetické pole je dočasné, dá se snadno měnit jeho velikost, příp. směr.

Cívka jako induktor - využívá se elektrické napětí indukované proměnným magnetickým polem kolem cívky
- tlumivka - cívka působí proti prudkým změnám v elektrickém obvodu (např. zapnutí/vypnutí obvodu, elektrický výboj, ap.). Změny v elektrickém obvodu vyvolávají změnu magnetického pole kolem cívky a následně se v cívce indukuje elektromotorické napětí působící vždy proti změnám, které je vyvolaly.
- transformátor - obsahuje dvě cívky na společném jádře. Změnou elektrického proudu (střídavým proudem) v jedné cívce se indukuje elektrický proud v druhé cívce, dochází k transformaci proudu a napětí.
- čtecí hlavičky v pevných discích
- v elektromagnetických oscilačních obvodech - cívka a kondenzátor jsou nezbytné součástky pro vznik elektromagnetických kmitů v obvodu (rezonanční LC obvody).

[editovat] Související články

Cívka v učebnici Praktická elektronika ve Wikiknihách

歡迎來到Bewise Inc.的世界，首先恭喜您來到這接受新的資訊讓產業更有競爭力，我們是提供專業刀具製造商，應對客戶高品質的刀具需求，我們可以協助客戶滿足您對產業的不同要求，我們有能力達到非常卓越的客戶需求品質，這是現有相關技術無法比擬的，我們成功的滿足了各行各業的要求，包括：精密HSS DIN切削刀具、協助客戶設計刀具流程、DIN or JIS 鎢鋼切削刀具設計、NAS986 NAS965 NAS897 NAS937orNAS907 航太切削刀具,NAS航太刀具設計、超高硬度的切削刀具、醫療配件刀具設計、複合式再研磨機、PCD地板專用企口鑽石組合刀具、NSK高數主軸與馬達、專業模具修補工具-氣動與電動、粉末造粒成型機、主機版專用頂級電桿、PCD V-Cut刀、捨棄式圓鋸片組、粉末成型機、主機版專用頂級電感、’汽車業刀具設計、電子產業鑽石刀具、木工產業鑽石刀具、銑刀與切斷複合再研磨機、銑刀與鑽頭複合再研磨機、銑刀與螺絲攻複合再研磨機等等。我們的產品涵蓋了從民生刀具到工業級的刀具設計；從微細刀具到大型刀具；從小型生產到大型量產；全自動整合；我們的技術可提供您連續生產的效能，我們整體的服務及卓越的技術，恭迎您親自體驗！！

BW Bewise Inc. Willy Chen willy@tool-tool.com bw@tool-tool.com www.tool-tool.com skype:willy_chen_bw mobile:0937-618-190 Head &Administration Office No.13,Shiang Shang 2nd St., West Chiu Taichung,Taiwan 40356 http://www.tool-tool.com / FAX:+886 4 2471 4839 N.Branch 5F,No.460,Fu Shin North Rd.,Taipei,Taiwan S.Branch No.24,Sec.1,Chia Pu East Rd.,Taipao City,Chiayi Hsien,Taiwan

Welcome to BW tool world! We are an experienced tool maker specialized in cutting tools. We focus on what you need and endeavor to research the best cutter to satisfy users’ demand. Our customers involve wide range of industries, like mold & die, aerospace, electronic, machinery, etc. We are professional expert in cutting field. We would like to solve every problem from you. Please feel free to contact us, its our pleasure to serve for you. BW product including: cutting tool、aerospace tool .HSS DIN Cutting tool、Carbide end mills、Carbide cutting tool、NAS Cutting tool、NAS986 NAS965 NAS897 NAS937orNAS907 Cutting Tools,Carbide end mill、disc milling cutter,Aerospace cutting tool、hss drill’Фрезеры’Carbide drill、High speed steel、Compound Sharpener’Milling cutter、INDUCTORS FOR PCD’CVDD(Chemical Vapor Deposition Diamond )’PCBN (Polycrystalline Cubic Boron Nitride) ’Core drill、Tapered end mills、CVD Diamond Tools Inserts’PCD Edge-Beveling Cutter(Golden Finger’PCD V-Cutter’PCD Wood tools’PCD Cutting tools’PCD Circular Saw Blade’PVDD End Mills’diamond tool. INDUCTORS FOR PCD . POWDER FORMING MACHINE ‘Single Crystal Diamond ‘Metric end mills、Miniature end mills、Специальные режущие инструменты ‘Пустотелое сверло ‘Pilot reamer、Fraises’Fresas con mango’ PCD (Polycrystalline diamond) ‘Frese’POWDER FORMING MACHINE’Electronics cutter、Step drill、Metal cutting saw、Double margin drill、Gun barrel、Angle milling cutter、Carbide burrs、Carbide tipped cutter、Chamfering tool、IC card engraving cutter、Side cutter、Staple Cutter’PCD diamond cutter specialized in grooving floors’V-Cut PCD Circular Diamond Tipped Saw Blade with Indexable Insert’ PCD Diamond Tool’ Saw Blade with Indexable Insert’NAS tool、DIN or JIS tool、Special tool、Metal slitting saws、Shell end mills、Side and face milling cutters、Side chip clearance saws、Long end mills’end mill grinder’drill grinder’sharpener、Stub roughing end mills、Dovetail milling cutters、Carbide slot drills、Carbide torus cutters、Angel carbide end mills、Carbide torus cutters、Carbide ball-nosed slot drills、Mould cutter、Tool manufacturer.

ようこそＢｅｗｉｓｅ　Ｉｎｃ.の世界へお越し下さいませ、先ず御目出度たいのは新たな

情報を受け取って頂き、もっと各産業に競争力プラス展開。

弊社は専門なエンド・ミルの製造メーカーで、客先に色んな分野のニーズ、

豊富なパリエーションを満足させ、特にハイテク品質要求にサポート致します。

弊社は各領域に供給できる内容は：

弊社の製品の供給調達機能は：

弊社の全般供給体制及び技術自慢の総合専門製造メーカーに貴方のご体験を御待ちしております。

Bewise Inc. talaşlı imalat sanayinde en fazla kullanılan ve üç eksende (x,y,z) talaş kaldırabilen freze takımlarından olan Parmak Freze imalatçısıdır. Çok geniş ürün yelpazesine sahip olan firmanın başlıca ürünlerini Karbür Parmak Frezeler, Kalıpçı Frezeleri, Kaba Talaş Frezeleri, Konik Alın Frezeler, Köşe Radyüs Frezeler, İki Ağızlı Kısa ve Uzun Küresel Frezeler, İç Bükey Frezeler vb. şeklinde sıralayabiliriz.

BW специализируется в научных исследованиях и разработках, и снабжаем самым высокотехнологичным карбидовым материалом для поставки режущих / фрезеровочных инструментов для почвы, воздушного пространства и электронной индустрии. В нашу основную продукцию входит твердый карбид / быстрорежущая сталь, а также двигатели, микроэлектрические дрели, IC картонорезальные машины, фрезы для гравирования, режущие пилы, фрезеры-расширители, фрезеры-расширители с резцом, дрели, резаки форм для шлицевого вала / звездочки роликовой цепи, и специальные нано инструменты. Пожалуйста, посетите сайт www.tool-tool.com для получения большей информации.

BW is specialized in R&D and sourcing the most advanced carbide material with high-tech coating to supply cutting / milling tool for mould & die, aero space and electronic industry. Our main products include solid carbide / HSS end mills, micro electronic drill, IC card cutter, engraving cutter, shell end mills, cutting saw, reamer, thread reamer, leading drill, involute gear cutter for spur wheel, rack and worm milling cutter, thread milling cutter, form cutters for spline shaft/roller chain sprocket, and special tool, with nano grade. Please visit our web www.tool-tool.com for more info.

beeway 發表在痞客邦留言(0) 人氣()

個人分類：學術研究

Mar 16 Mon 2009 13:53
Català Inductor www.tool-tool.com

Bewise Inc. www.tool-tool.com Reference source from the internet.

Un inductor és un component electrònic passiu dels circuits elèctrics que, a causa del fenomen de l'autoinducció, emmagatzema energia en forma de camp magnètic creat pel pas del corrent elèctric. Aquest component també acostuma a rebre els noms de bobina o inductància. La capacitat d'un inductor d'emmagatzemar energia es mesura per la seva inductància que s'expressa en henrys (simbolitzat H), una unitat derivada del Sistema Internacional d'unitats.

A la teoria de circuits un inductor ideal tindria inductància però no presentaria resistència ni capacitància, per això no dissiparia energia. En aquest component ideal tota l'energia elèctrica absorbida seria emmagatzemada en forma de camp magnètic. Però els inductors reals, que són fabricats amb un enrotllament de fil conductor, són equivalents a una combinació d'inductància, certa resistència deguda a la resistivitat del fil, i certa capacitància. A algunes freqüències, un inductor real es comporta com un circuit ressonant a causa de la capacitància paràsita. A més de dissipar energia per la resistència elèctrica del fil conductor, el nucli dels inductors també la poden dissipar a causa de la histèresi i a grans corrents també es poden produir pèrdues d'energia a causa de la no linealitat dels circuits.

[edita] Construcció

Inductors corrents.

Un inductor està constituït usualment per una bobina de material conductor, típicament cable de coure. Existeixen inductors amb nucli d'aire o amb nucli d'un material ferrós, per incrementar la seva inductància. Les bobines típiques estan formades per espires, fetes de fil esmaltat, i solen envoltar un nucli de material ferromagnètic. Als motors elèctrics van col·locades a dintre les ranures.

Els inductors poden estar també construïts en circuits integrats, usant el mateix procés utilitzat per realitzar microprocessadors. En aquests casos s'usa, comunament, l'alumini com a material conductor. Tanmateix, és rar que es construeixin inductors dins dels circuits integrats; és molt més pràctic usar un circuit dit "girador" que, mitjançant un amplificador operacional, fa que un condensador es comporti com si fos un inductor.

Petits inductors usats per a freqüències molt altes, poden ser realitzats en ocasions amb un conductor passant a través d'un cilindre de ferrita o granulat.

[edita] L'inductor als circuits elèctrics

Els inductors s'oposen als canvis al corrent elèctric, un inductor ideal no oposaria cap resistència a un corrent continu constant, tanmateix només els inductors superconductors tindrien realment una resitència nul·la.

En general, la relació entre la variació del voltatge en el temps v(t) a través d'un inductor amb una inductància L i una variació del corrent que hi passa al llarg del temps i(t) es descriu per mitjà d'una equació diferencial:

$v(t) = L \frac{di(t)}{dt}$

on

v és el voltatge,di(t)/dt és la derivada del corrent i L és la inductància mesurada en henrys.

Les bobines a les màquines elèctriques poden anar tant en el rotor com en el estator i conformen el circuit elèctric de la màquina. Segons com es vulgui que treballi el motor, les bobines és poden col·locar de dues maneres: Als pols (sortida amb sortida, entrada amb entrada, sortida amb sortida…) o al pols conseqüents (sortida amb entrada, sortida amb entrada, sortida amb entrada …). També és poden fer en sèries paral·leles en les quals hem de mantenir les espires connectades a la xarxa elèctrica.

歡迎來到Bewise Inc.的世界，首先恭喜您來到這接受新的資訊讓產業更有競爭力，我們是提供專業刀具製造商，應對客戶高品質的刀具需求，我們可以協助客戶滿足您對產業的不同要求，我們有能力達到非常卓越的客戶需求品質，這是現有相關技術無法比擬的，我們成功的滿足了各行各業的要求，包括：精密HSS DIN切削刀具、協助客戶設計刀具流程、DIN or JIS 鎢鋼切削刀具設計、NAS986 NAS965 NAS897 NAS937orNAS907 航太切削刀具,NAS航太刀具設計、超高硬度的切削刀具、醫療配件刀具設計、複合式再研磨機、PCD地板專用企口鑽石組合刀具、NSK高數主軸與馬達、專業模具修補工具-氣動與電動、粉末造粒成型機、主機版專用頂級電桿、PCD V-Cut刀、捨棄式圓鋸片組、粉末成型機、主機版專用頂級電感、’汽車業刀具設計、電子產業鑽石刀具、木工產業鑽石刀具、銑刀與切斷複合再研磨機、銑刀與鑽頭複合再研磨機、銑刀與螺絲攻複合再研磨機等等。我們的產品涵蓋了從民生刀具到工業級的刀具設計；從微細刀具到大型刀具；從小型生產到大型量產；全自動整合；我們的技術可提供您連續生產的效能，我們整體的服務及卓越的技術，恭迎您親自體驗！！

BW Bewise Inc. Willy Chen willy@tool-tool.com bw@tool-tool.com www.tool-tool.com skype:willy_chen_bw mobile:0937-618-190 Head &Administration Office No.13,Shiang Shang 2nd St., West Chiu Taichung,Taiwan 40356 http://www.tool-tool.com / FAX:+886 4 2471 4839 N.Branch 5F,No.460,Fu Shin North Rd.,Taipei,Taiwan S.Branch No.24,Sec.1,Chia Pu East Rd.,Taipao City,Chiayi Hsien,Taiwan

Welcome to BW tool world! We are an experienced tool maker specialized in cutting tools. We focus on what you need and endeavor to research the best cutter to satisfy users’ demand. Our customers involve wide range of industries, like mold & die, aerospace, electronic, machinery, etc. We are professional expert in cutting field. We would like to solve every problem from you. Please feel free to contact us, its our pleasure to serve for you. BW product including: cutting tool、aerospace tool .HSS DIN Cutting tool、Carbide end mills、Carbide cutting tool、NAS Cutting tool、NAS986 NAS965 NAS897 NAS937orNAS907 Cutting Tools,Carbide end mill、disc milling cutter,Aerospace cutting tool、hss drill’Фрезеры’Carbide drill、High speed steel、Compound Sharpener’Milling cutter、INDUCTORS FOR PCD’CVDD(Chemical Vapor Deposition Diamond )’PCBN (Polycrystalline Cubic Boron Nitride) ’Core drill、Tapered end mills、CVD Diamond Tools Inserts’PCD Edge-Beveling Cutter(Golden Finger’PCD V-Cutter’PCD Wood tools’PCD Cutting tools’PCD Circular Saw Blade’PVDD End Mills’diamond tool. INDUCTORS FOR PCD . POWDER FORMING MACHINE ‘Single Crystal Diamond ‘Metric end mills、Miniature end mills、Специальные режущие инструменты ‘Пустотелое сверло ‘Pilot reamer、Fraises’Fresas con mango’ PCD (Polycrystalline diamond) ‘Frese’POWDER FORMING MACHINE’Electronics cutter、Step drill、Metal cutting saw、Double margin drill、Gun barrel、Angle milling cutter、Carbide burrs、Carbide tipped cutter、Chamfering tool、IC card engraving cutter、Side cutter、Staple Cutter’PCD diamond cutter specialized in grooving floors’V-Cut PCD Circular Diamond Tipped Saw Blade with Indexable Insert’ PCD Diamond Tool’ Saw Blade with Indexable Insert’NAS tool、DIN or JIS tool、Special tool、Metal slitting saws、Shell end mills、Side and face milling cutters、Side chip clearance saws、Long end mills’end mill grinder’drill grinder’sharpener、Stub roughing end mills、Dovetail milling cutters、Carbide slot drills、Carbide torus cutters、Angel carbide end mills、Carbide torus cutters、Carbide ball-nosed slot drills、Mould cutter、Tool manufacturer.

ようこそＢｅｗｉｓｅ　Ｉｎｃ.の世界へお越し下さいませ、先ず御目出度たいのは新たな

情報を受け取って頂き、もっと各産業に競争力プラス展開。

弊社は専門なエンド・ミルの製造メーカーで、客先に色んな分野のニーズ、

豊富なパリエーションを満足させ、特にハイテク品質要求にサポート致します。

弊社は各領域に供給できる内容は：

弊社の製品の供給調達機能は：

弊社の全般供給体制及び技術自慢の総合専門製造メーカーに貴方のご体験を御待ちしております。

Bewise Inc. talaşlı imalat sanayinde en fazla kullanılan ve üç eksende (x,y,z) talaş kaldırabilen freze takımlarından olan Parmak Freze imalatçısıdır. Çok geniş ürün yelpazesine sahip olan firmanın başlıca ürünlerini Karbür Parmak Frezeler, Kalıpçı Frezeleri, Kaba Talaş Frezeleri, Konik Alın Frezeler, Köşe Radyüs Frezeler, İki Ağızlı Kısa ve Uzun Küresel Frezeler, İç Bükey Frezeler vb. şeklinde sıralayabiliriz.

BW специализируется в научных исследованиях и разработках, и снабжаем самым высокотехнологичным карбидовым материалом для поставки режущих / фрезеровочных инструментов для почвы, воздушного пространства и электронной индустрии. В нашу основную продукцию входит твердый карбид / быстрорежущая сталь, а также двигатели, микроэлектрические дрели, IC картонорезальные машины, фрезы для гравирования, режущие пилы, фрезеры-расширители, фрезеры-расширители с резцом, дрели, резаки форм для шлицевого вала / звездочки роликовой цепи, и специальные нано инструменты. Пожалуйста, посетите сайт www.tool-tool.com для получения большей информации.

BW is specialized in R&D and sourcing the most advanced carbide material with high-tech coating to supply cutting / milling tool for mould & die, aero space and electronic industry. Our main products include solid carbide / HSS end mills, micro electronic drill, IC card cutter, engraving cutter, shell end mills, cutting saw, reamer, thread reamer, leading drill, involute gear cutter for spur wheel, rack and worm milling cutter, thread milling cutter, form cutters for spline shaft/roller chain sprocket, and special tool, with nano grade. Please visit our web www.tool-tool.com for more info.

beeway 發表在痞客邦留言(0) 人氣()

個人分類：學術研究

Mar 16 Mon 2009 13:45
Bosanski Zavojnica www.tool-tool.com

Bewise Inc. www.tool-tool.com Reference source from the internet.

Idi na: navigacija, pretraga

Zavojnice

Zavojnica je elektronski element koji ima određen induktivitet (L). Induktivitet se izražava u henrijima (H), nazvanim po američkom fizičaru Josephu Henryu, a najčešće se upotrebljava jedinica milihenri (mH). Zavojnica se redovito sastoji od žice koja je namotana jednostavno ili unakrsno u jednom ili više slojeva. Nosač ili tijelo zavojnice izrađuje se od impregniranog papira, drveta, sintetičkog ili sličnog materijala. Najčešće ima oblik šupljeg valjka. Vodič od kojega je napravljena zavojnica najčešće je bakreni, izoliran lakom, rjeđe pamukom ili svilom. Kod zavojnica, predviđenih za vrlo visoke frekvencije upotrebljava se posrebrena bakrena žica ili cijev. Samo specijalne zavojnice za ultrakratke valove su bez tijela. Vodič tada mora biti mehanički dovoljno krut da zadrži svoj oblik. Za razliku od otpornika i kondenzatora zavojnice se veoma teško nalaze kao već gotov proizvod u trgovinama, jer svojstva zavojnice ovise o konkretnoj primjeni.

Upotreba i vrste zavojnica [uredi]

U titrajnim krugovima najčešće se upotrebljavaju valjčaste jednoslojne zavojnice. Karakteristike zavojnica ovise o sljedećim parametrima, to su: D - srednji promjer zavojnice, l - dužina zavojnice, d - debljina žice, N - broj namotaja žice, te a - razmak između svakog namotaja. Svi ti spomenuti parametri utiču na veličinu induktiviteta L. Zavojnice možemo podijeliti na one namijenjene za niskofrekventne (NF) i visokofrekventne (VF) strujne krugove. Dok ih s obzirom na izvedbu dijelimo na: zavojnice s jezgrom i zavojnice bez jezgre.

Kao jezgra za NF zavojnice upotrebljavaju se međusobno izolirani transformatorski limovi. Dok se za VF zavojnice upotrebljavaju posebne VF jezgre. Postoje razne vrste materijala za izradu takvih jezgri. Dobivaju se sintetički, a nose nazive "siferit", "feroskuba", itd... Zavojnice se također mogu međusobno spajati, no s time da veza između njih mora biti ostvarena pomoću vodiča, ali i pomoću njihova induktiviteta. Krajnji induktivitet spoja ovisan je o induktivitetu pojedinih zavojnica i o njihovoj međusobnoj vezi. Tačan proračun se može dobiti za sasvim jednostavne slučajeve, kada zavojnice ne djeluju jedna na drugu, bilo da su dovoljno daleko ili oklopljene metalnim oklopom.

Spojevi zavojnica [uredi]

Zavojnice se mogu spajati serijski i paralelno. Kod serijskog spoja zavojnica ukupan induktivitet jednak je zbiru svih induktiviteta pojedinih zavojnica:

$L_u = L_1 + L_2 + \cdots +L_n$

Kod paralelnog spoja induktiviteta odnosno zavojnica, ukupni induktivitet jednak je recipročnoj vrijednosti zbira recipročnih vrijednosti induktiviteta pojedinih zavojnica:

$\frac{1}{L_u} = \frac{1}{L_1} + \frac{1}{L_2} + \cdots + \frac{1}{L_n}$

Za složenije slučajeve spajanja zavojnica u praksi je najjednostavnije izmjeriti zajednički induktivitet kombinacije zavojnica.

Proračun jednoslojne, valjkaste zavojnice [uredi]

Ovo je vrsta zavojnica koja se najčešće upotrebljava u elektrotehnici. Već smo rekli da nekoliko parametara utiče na karakteristike zavojnice: broj zavoja (namotaja), promjer zavojnice, dužina zavojnice, ali ovisi i o omjeru dužine i promjera zavojnice. Taj omjer se zove "K faktor". Induktivitet se jednostavno može izračunati iz matematičke relacije:

L = K * D * N²

U toj formuli L je induktivitet zavojnice izražen u mikrohenrijima, D - promjer zavojnice u centimetrima, N - broj zavoja (namota) i K - faktor koji ovisi o omjeru dužine i promjera zavojnice.

歡迎來到Bewise Inc.的世界，首先恭喜您來到這接受新的資訊讓產業更有競爭力，我們是提供專業刀具製造商，應對客戶高品質的刀具需求，我們可以協助客戶滿足您對產業的不同要求，我們有能力達到非常卓越的客戶需求品質，這是現有相關技術無法比擬的，我們成功的滿足了各行各業的要求，包括：精密HSS DIN切削刀具、協助客戶設計刀具流程、DIN or JIS 鎢鋼切削刀具設計、NAS986 NAS965 NAS897 NAS937orNAS907 航太切削刀具,NAS航太刀具設計、超高硬度的切削刀具、醫療配件刀具設計、複合式再研磨機、PCD地板專用企口鑽石組合刀具、NSK高數主軸與馬達、專業模具修補工具-氣動與電動、粉末造粒成型機、主機版專用頂級電桿、PCD V-Cut刀、捨棄式圓鋸片組、粉末成型機、主機版專用頂級電感、’汽車業刀具設計、電子產業鑽石刀具、木工產業鑽石刀具、銑刀與切斷複合再研磨機、銑刀與鑽頭複合再研磨機、銑刀與螺絲攻複合再研磨機等等。我們的產品涵蓋了從民生刀具到工業級的刀具設計；從微細刀具到大型刀具；從小型生產到大型量產；全自動整合；我們的技術可提供您連續生產的效能，我們整體的服務及卓越的技術，恭迎您親自體驗！！

BW Bewise Inc. Willy Chen willy@tool-tool.com bw@tool-tool.com www.tool-tool.com skype:willy_chen_bw mobile:0937-618-190 Head &Administration Office No.13,Shiang Shang 2nd St., West Chiu Taichung,Taiwan 40356 http://www.tool-tool.com / FAX:+886 4 2471 4839 N.Branch 5F,No.460,Fu Shin North Rd.,Taipei,Taiwan S.Branch No.24,Sec.1,Chia Pu East Rd.,Taipao City,Chiayi Hsien,Taiwan

Welcome to BW tool world! We are an experienced tool maker specialized in cutting tools. We focus on what you need and endeavor to research the best cutter to satisfy users’ demand. Our customers involve wide range of industries, like mold & die, aerospace, electronic, machinery, etc. We are professional expert in cutting field. We would like to solve every problem from you. Please feel free to contact us, its our pleasure to serve for you. BW product including: cutting tool、aerospace tool .HSS DIN Cutting tool、Carbide end mills、Carbide cutting tool、NAS Cutting tool、NAS986 NAS965 NAS897 NAS937orNAS907 Cutting Tools,Carbide end mill、disc milling cutter,Aerospace cutting tool、hss drill’Фрезеры’Carbide drill、High speed steel、Compound Sharpener’Milling cutter、INDUCTORS FOR PCD’CVDD(Chemical Vapor Deposition Diamond )’PCBN (Polycrystalline Cubic Boron Nitride) ’Core drill、Tapered end mills、CVD Diamond Tools Inserts’PCD Edge-Beveling Cutter(Golden Finger’PCD V-Cutter’PCD Wood tools’PCD Cutting tools’PCD Circular Saw Blade’PVDD End Mills’diamond tool. INDUCTORS FOR PCD . POWDER FORMING MACHINE ‘Single Crystal Diamond ‘Metric end mills、Miniature end mills、Специальные режущие инструменты ‘Пустотелое сверло ‘Pilot reamer、Fraises’Fresas con mango’ PCD (Polycrystalline diamond) ‘Frese’POWDER FORMING MACHINE’Electronics cutter、Step drill、Metal cutting saw、Double margin drill、Gun barrel、Angle milling cutter、Carbide burrs、Carbide tipped cutter、Chamfering tool、IC card engraving cutter、Side cutter、Staple Cutter’PCD diamond cutter specialized in grooving floors’V-Cut PCD Circular Diamond Tipped Saw Blade with Indexable Insert’ PCD Diamond Tool’ Saw Blade with Indexable Insert’NAS tool、DIN or JIS tool、Special tool、Metal slitting saws、Shell end mills、Side and face milling cutters、Side chip clearance saws、Long end mills’end mill grinder’drill grinder’sharpener、Stub roughing end mills、Dovetail milling cutters、Carbide slot drills、Carbide torus cutters、Angel carbide end mills、Carbide torus cutters、Carbide ball-nosed slot drills、Mould cutter、Tool manufacturer.

ようこそＢｅｗｉｓｅ　Ｉｎｃ.の世界へお越し下さいませ、先ず御目出度たいのは新たな

情報を受け取って頂き、もっと各産業に競争力プラス展開。

弊社は専門なエンド・ミルの製造メーカーで、客先に色んな分野のニーズ、

豊富なパリエーションを満足させ、特にハイテク品質要求にサポート致します。

弊社は各領域に供給できる内容は：

弊社の製品の供給調達機能は：

弊社の全般供給体制及び技術自慢の総合専門製造メーカーに貴方のご体験を御待ちしております。

Bewise Inc. talaşlı imalat sanayinde en fazla kullanılan ve üç eksende (x,y,z) talaş kaldırabilen freze takımlarından olan Parmak Freze imalatçısıdır. Çok geniş ürün yelpazesine sahip olan firmanın başlıca ürünlerini Karbür Parmak Frezeler, Kalıpçı Frezeleri, Kaba Talaş Frezeleri, Konik Alın Frezeler, Köşe Radyüs Frezeler, İki Ağızlı Kısa ve Uzun Küresel Frezeler, İç Bükey Frezeler vb. şeklinde sıralayabiliriz.

BW специализируется в научных исследованиях и разработках, и снабжаем самым высокотехнологичным карбидовым материалом для поставки режущих / фрезеровочных инструментов для почвы, воздушного пространства и электронной индустрии. В нашу основную продукцию входит твердый карбид / быстрорежущая сталь, а также двигатели, микроэлектрические дрели, IC картонорезальные машины, фрезы для гравирования, режущие пилы, фрезеры-расширители, фрезеры-расширители с резцом, дрели, резаки форм для шлицевого вала / звездочки роликовой цепи, и специальные нано инструменты. Пожалуйста, посетите сайт www.tool-tool.com для получения большей информации.

BW is specialized in R&D and sourcing the most advanced carbide material with high-tech coating to supply cutting / milling tool for mould & die, aero space and electronic industry. Our main products include solid carbide / HSS end mills, micro electronic drill, IC card cutter, engraving cutter, shell end mills, cutting saw, reamer, thread reamer, leading drill, involute gear cutter for spur wheel, rack and worm milling cutter, thread milling cutter, form cutters for spline shaft/roller chain sprocket, and special tool, with nano grade. Please visit our web www.tool-tool.com for more info.

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個人分類：學術研究

Mar 16 Mon 2009 13:35
العربية مستحث www.tool-tool.com

Bewise Inc. www.tool-tool.com Reference source from the internet.

الوشيعة او الملف {Inductor المستحث الكهربائي} وشيعة L هي جهاز كهربائي سلبي يستعمل في الدوائر الكهربائية من أجل قدرته على الحث، الوشيعة تتكون من سلك غالباً ما يكون من النحاس وفيه عدد معين من اللفات nلفة ولها مواصفات المقاومات ولكنها خيالية jwl

المحرض وهو أحد الادوات الالكترونية او الدارات التي من شانها زيادة تدفق سيل التيار في دائرة الموصل .... وهو يستخدم لتقيل الكهرباء نوعا ما بحيث ان الكهرباء التي تدخل الجهاز تتناسب مع معدل صرفها

j: الجزء الخيالي - W : التردد الدائري (W = 2*Pi*f)

ألية عملها : عندما يمر تيار كهربائي متغير I بالسلك يتكون تيار مغناطيسي Φ وبتفير التيار الكهربائي بتغير الزمن يتولد لدينا جهد *توتر* U فتكون لدينا العلاقة : [U(t) = L*(di/dt)]

[عدل] مقالة مماثلة

ملف

歡迎來到Bewise Inc.的世界，首先恭喜您來到這接受新的資訊讓產業更有競爭力，我們是提供專業刀具製造商，應對客戶高品質的刀具需求，我們可以協助客戶滿足您對產業的不同要求，我們有能力達到非常卓越的客戶需求品質，這是現有相關技術無法比擬的，我們成功的滿足了各行各業的要求，包括：精密HSS DIN切削刀具、協助客戶設計刀具流程、DIN or JIS 鎢鋼切削刀具設計、NAS986 NAS965 NAS897 NAS937orNAS907 航太切削刀具,NAS航太刀具設計、超高硬度的切削刀具、醫療配件刀具設計、複合式再研磨機、PCD地板專用企口鑽石組合刀具、NSK高數主軸與馬達、專業模具修補工具-氣動與電動、粉末造粒成型機、主機版專用頂級電桿、PCD V-Cut刀、捨棄式圓鋸片組、粉末成型機、主機版專用頂級電感、’汽車業刀具設計、電子產業鑽石刀具、木工產業鑽石刀具、銑刀與切斷複合再研磨機、銑刀與鑽頭複合再研磨機、銑刀與螺絲攻複合再研磨機等等。我們的產品涵蓋了從民生刀具到工業級的刀具設計；從微細刀具到大型刀具；從小型生產到大型量產；全自動整合；我們的技術可提供您連續生產的效能，我們整體的服務及卓越的技術，恭迎您親自體驗！！

BW Bewise Inc. Willy Chen willy@tool-tool.com bw@tool-tool.com www.tool-tool.com skype:willy_chen_bw mobile:0937-618-190 Head &Administration Office No.13,Shiang Shang 2nd St., West Chiu Taichung,Taiwan 40356 http://www.tool-tool.com / FAX:+886 4 2471 4839 N.Branch 5F,No.460,Fu Shin North Rd.,Taipei,Taiwan S.Branch No.24,Sec.1,Chia Pu East Rd.,Taipao City,Chiayi Hsien,Taiwan

Welcome to BW tool world! We are an experienced tool maker specialized in cutting tools. We focus on what you need and endeavor to research the best cutter to satisfy users’ demand. Our customers involve wide range of industries, like mold & die, aerospace, electronic, machinery, etc. We are professional expert in cutting field. We would like to solve every problem from you. Please feel free to contact us, its our pleasure to serve for you. BW product including: cutting tool、aerospace tool .HSS DIN Cutting tool、Carbide end mills、Carbide cutting tool、NAS Cutting tool、NAS986 NAS965 NAS897 NAS937orNAS907 Cutting Tools,Carbide end mill、disc milling cutter,Aerospace cutting tool、hss drill’Фрезеры’Carbide drill、High speed steel、Compound Sharpener’Milling cutter、INDUCTORS FOR PCD’CVDD(Chemical Vapor Deposition Diamond )’PCBN (Polycrystalline Cubic Boron Nitride) ’Core drill、Tapered end mills、CVD Diamond Tools Inserts’PCD Edge-Beveling Cutter(Golden Finger’PCD V-Cutter’PCD Wood tools’PCD Cutting tools’PCD Circular Saw Blade’PVDD End Mills’diamond tool. INDUCTORS FOR PCD . POWDER FORMING MACHINE ‘Single Crystal Diamond ‘Metric end mills、Miniature end mills、Специальные режущие инструменты ‘Пустотелое сверло ‘Pilot reamer、Fraises’Fresas con mango’ PCD (Polycrystalline diamond) ‘Frese’POWDER FORMING MACHINE’Electronics cutter、Step drill、Metal cutting saw、Double margin drill、Gun barrel、Angle milling cutter、Carbide burrs、Carbide tipped cutter、Chamfering tool、IC card engraving cutter、Side cutter、Staple Cutter’PCD diamond cutter specialized in grooving floors’V-Cut PCD Circular Diamond Tipped Saw Blade with Indexable Insert’ PCD Diamond Tool’ Saw Blade with Indexable Insert’NAS tool、DIN or JIS tool、Special tool、Metal slitting saws、Shell end mills、Side and face milling cutters、Side chip clearance saws、Long end mills’end mill grinder’drill grinder’sharpener、Stub roughing end mills、Dovetail milling cutters、Carbide slot drills、Carbide torus cutters、Angel carbide end mills、Carbide torus cutters、Carbide ball-nosed slot drills、Mould cutter、Tool manufacturer.

ようこそＢｅｗｉｓｅ　Ｉｎｃ.の世界へお越し下さいませ、先ず御目出度たいのは新たな

情報を受け取って頂き、もっと各産業に競争力プラス展開。

弊社は専門なエンド・ミルの製造メーカーで、客先に色んな分野のニーズ、

豊富なパリエーションを満足させ、特にハイテク品質要求にサポート致します。

弊社は各領域に供給できる内容は：

弊社の製品の供給調達機能は：

弊社の全般供給体制及び技術自慢の総合専門製造メーカーに貴方のご体験を御待ちしております。

Bewise Inc. talaşlı imalat sanayinde en fazla kullanılan ve üç eksende (x,y,z) talaş kaldırabilen freze takımlarından olan Parmak Freze imalatçısıdır. Çok geniş ürün yelpazesine sahip olan firmanın başlıca ürünlerini Karbür Parmak Frezeler, Kalıpçı Frezeleri, Kaba Talaş Frezeleri, Konik Alın Frezeler, Köşe Radyüs Frezeler, İki Ağızlı Kısa ve Uzun Küresel Frezeler, İç Bükey Frezeler vb. şeklinde sıralayabiliriz.

BW специализируется в научных исследованиях и разработках, и снабжаем самым высокотехнологичным карбидовым материалом для поставки режущих / фрезеровочных инструментов для почвы, воздушного пространства и электронной индустрии. В нашу основную продукцию входит твердый карбид / быстрорежущая сталь, а также двигатели, микроэлектрические дрели, IC картонорезальные машины, фрезы для гравирования, режущие пилы, фрезеры-расширители, фрезеры-расширители с резцом, дрели, резаки форм для шлицевого вала / звездочки роликовой цепи, и специальные нано инструменты. Пожалуйста, посетите сайт www.tool-tool.com для получения большей информации.

BW is specialized in R&D and sourcing the most advanced carbide material with high-tech coating to supply cutting / milling tool for mould & die, aero space and electronic industry. Our main products include solid carbide / HSS end mills, micro electronic drill, IC card cutter, engraving cutter, shell end mills, cutting saw, reamer, thread reamer, leading drill, involute gear cutter for spur wheel, rack and worm milling cutter, thread milling cutter, form cutters for spline shaft/roller chain sprocket, and special tool, with nano grade. Please visit our web www.tool-tool.com for more info.

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個人分類：學術研究

Mar 16 Mon 2009 12:14
Afrikaans Induktor www.tool-tool.com

Bewise Inc. www.tool-tool.com Reference source from the internet.

'n Induktor is 'n passiewe elektriese komponent wat energie stoor in die vorm van 'n magnetiese veld. Die induktor word in elektriese stroombane gebruik vir die induktiewe eienskap van die induktor.

Induktors

Inhoud

[versteek]

[wysig] Fisika

[wysig] Oorsig

Induktansie, wat in henry gemeet word, is 'n effek van die magnetiese veld wat om 'n stroomdraende geleier gevorm word. 'n Elektriese stroom wat deur 'n geleier vloei veroorsaak 'n magnetiese veld om die geleier. 'n Verandering in die stroom veroorsaak 'n verandering in die magnetiese veld. Hierdie verandering in die magnetiese veld veroorsaak dat daar 'n elektromotoriese krag (emk) geskep word wat teen die stroom verandering werk. Induktansie kwantifiseer die hoeveelheid emk wat geskep word per eenheidsverandering in die elektriese stroom. Byvoorbeeld, 'n induktor met 'n induktansie van 1 henry skep 'n emk van 1 volt as die stroom deur die induktor verander teen 1 ampère per sekonde. Die induktansie van 'n geleier kan vermeerder word deur die geleier in 'n spoel te draai sodat die magnetiese vloed ingeperk word deur die spoel . Andersinds kan die spoel gedraai word om 'n materiaal met 'n hoë permeabiliteit.

[wysig] Energie

Die energie, wat in joules gemeet word, wat gestoor word in 'n induktor word bereken deur die vergelyking:

$E_\mathrm{gestoor} = {1 \over 2} L I^2$

waar

L die induktansie van die induktor is, en

I die stroom is wat deur die geleier vloei.

[wysig] Vervaardiging van induktors

Induktors word gewoonlik vervaardig deur 'n geleidende materiaal, gewoonlik koper in 'n spoel te draai. 'n Ferromagnetiese materiaal soos Ferriet kan as kern gebruik word om die induktansie van die induktor te verhoog. Sommige induktors se kern kan verstel word om 'n verstelbare induktor te maak. Induktors kan ook op stroombaan borde geëts word deur 'n spiraal vormige spoor (trace) (gewoonlik vierkantig of reghoekig). Induktors word op geïntegreerde stroombane vervaardig deur van dieselfde prosesse gebruik te maak as die wat gebruik word om mikroskywe te vervaardig. In die geval word aluminium gewoonlik gebruik as geleier. Werklike induktors word nie gewoonlik gebruik in geïntegreerde stroombane nie, aangesien hulle te groot is op so 'n klein skaal. Vir praktiese doeleindes word 'n stroombaan wat 'n gyrator genoem word gebruik. 'n Gyrator stroombaan gebruik operasionele versterkers en 'n kapasitor om 'n stroombaan te skep wat eienskappe van 'n induktor het. Klein induktors by baie hoë frekwensies word vervaardig deur 'n draad deur 'n ferriet silinder of kraaltjie te druk.

[wysig] In elektriese stroombane

'n Induktor bied weerstand teen verandering in elektriese stroom. 'n Ideale induktor bied geen weerstand teen gelykstroom nie, behalwe wanneer die stroom aan- of afgeskakel word, in die geval is die stroom verandering meer geleidelik. Regte induktors word van materiaal vervaardig wat elektriese weerstand bied teen selfs gelykstroom en is dus nie ideaal nie.

Die verhouding tussen 'n tydvariërende elektriese spanning v(t) oor 'n induktor met induktansie en tydvariërende elektriese stroom i(t) deur die induktor word in die algemeen beskryf deur die differensiaalvergelyking

$v(t) = L \frac{di(t)}{dt}$

Hierdie verhouding staan bekend as Lenz se wet wat rondom 1833, as 'n uitbreiding van Faraday se wet, deur Heinrich Lenz ontdek is.

Wanneer 'n sinusvormige wisselstroom deur die induktor vloei, word 'n sinusvormige spanning geïnduseer. Die amplitude van die spanning het 'n direkte verhouding met die amplitude van die stroom (I_P) en die frekwensie (f) van die sinusvormige stroom deur die volgende verhouding.

$i(t) = I_P sin(2 \pi f t)\,$

$\frac{di(t)}{dt} = 2 \pi f I_P cos(2 \pi f t)$

$v(t) = 2 \pi f L I_P cos(2 \pi f t)\,$

Daar kan duidelik gesien word dat die fase van die stroom die spanning met 90 grade volg.

[wysig] Fasor stroombaananalise en impedansie

Deur van fasors gebruik te maak word die impedansie van 'n induktor gegee deur die volgende vergelyking:

$Z_L = V_l / I_l = j \omega L = j X_L \,$

waar

$X_L = \omega L \,$ die induktiewe reaktansie is,

$\omega = 2 \pi f \,$ die hoek frekwensie is,

L die induktansie is,

f die frekwensie is, en

j die imaginêre eenheid is.

[wysig] Laplace stroombaananalise (s-vlak)

Wanneer die Laplace transform in stroombaan analise gebruik word, word die oordrag impedansie van 'n ideale induktor met nie-ideale stroom voorgestel in die s-vlak deur die vergelyking:

$Z(s) = s L\,$

waar

L die induktansie is, en

s die komplekse frekwensie is.

Wanneer daar 'n aanvanklike stroom deur die induktor vloei, word dit voorgestel deur:

'n spanningsbron in serie met die induktor te plaas met die waarde:

$L I_0 \,$

(Let daarop dat die polariteit van die spanningsbron die aanvanklike stroom teenstaan)

'n stroombron in parallel met die induktor te plaas met die waarde:

$\frac{I_0}{s}$

waar

L die induktansie van die induktor is, en

I₀ die aanvanklike stroom in die induktor is.

[wysig] Induktornetwerke

Die spanningsval oor die induktors in 'n parallelle konfigurasie is dieselfde, maar die stroom deur elke induktor kan verskil. Die totale stroom in die netwerk is die som van die strome in elke induktor. Die ekwivalente totale induktansie (L_tot) van die netwerk word bereken deur:

'n Diagram van veelvuldige induktors in parallel gekoppel.

$\frac{1}{L_\mathrm{tot}} = \frac{1}{L_1} + \frac{1}{L_2} + \cdots + \frac{1}{L_n}$

Die stroom deur die induktors in 'n serie-konfigurasie is dieselfde, maar die spanningsval oor elke induktor kan verskil. Die totale spanningsval oor die netwerk is die som van die spanningsval oor elke induktor. Die ekwivalente totale induktansie (L_tot) van die netwerk word bereken deur:

$L_\mathrm{tot} = L_1 + L_2 + \cdots + L_n \,\!$

Hierdie eenvoudige verhoudings is slegs waar as daar geen gemeenskaplike koppeling van magnetiese velde tussen individuele induktors is nie.

[wysig] Q-faktor

'n Ideale induktor het geen verliese ongeag die hoeveelheid stroom wat deur die induktor vloei. Werklike induktors het wel 'n weerstand teen die vloei van stroom aangesien die spoel van materiaal vervaardig word wat weerstand bied. Aangesien die spoel weerstand in series met die induktor is word dit die series weerstand van die induktor genoem. Die series weerstand van 'n induktor skakel die elektriese stroom deur die spoel om na hitte. Dit veroorsaak 'n verlies in die induktor se kwaliteit. Hierdie kwaliteit word deur die kwaliteit faktor of Q-faktor van die induktor gekwantifiseer. Die Q-faktor van 'n induktor is die verhouding tussen die induktansie en series weerstand van die induktor by 'n spesifieke frekwensie. Die induktor neig na 'n ideale induktor as die Q-faktor groter word. Die Q-faktor van 'n induktor word bereken deur die vergelyking:

$Q = \frac{\omega{}L}{R} \,$

waar

L die induktansie van die induktor is,

R die series weerstand van die spoel materiaal is, en

$\omega = 2 \pi f \,$ die hoek frekwensie is.

Waneer 'n hoë stroom deur 'n induktor vloei wat 'n ferromagnetiese kern het kan dit versadig. Dit veroorsaak dat die Q-faktor van die induktor drasties verminder. Hierdie veskeinsel kan voorkom word deur van lug kern induktor gebruik te maak. Die nadeel is dat lug kern induktor grooter is as ferromagnetiese kern induktors.

Deur gebruik te maak van 'n supergeleier allooi spoel wat in vloeibare helium of vloeibare stikstof gedompel word kan 'n amper ideale induktor gemaak word (Q-faktor wat na oneindig neig). In hierdie super afgekoelde spoel verdwyn die series weerstand. Aangesien hierdie induktor virtueel geen verliese het nie kan energie effektief gestoor word in die magneetveld wat om die induktor vorm.

[wysig] Toepassings

Induktors is verwant aan elektromagnete in struktuur, maar word gebruik met die doel om energie te stoor in die vorm van 'n magneetveld.

Induktors word gebruik in analoog stroombane en sein prosessering. Saam met kapasitors en ander komponente word induktors gebruik om elektriese filters te maak. 'n Elektriese filter kan 'n sein met spesifieke frekwensie uit filter. Induktors wat bekend staan as smoorspoelle word saam met kapasitors gebruik om die ruis van gelykstroom elektriese toevoer uit te filter. Baie klein induktors was bestaan uit 'n ferriet kraaltjie of torus wat om 'n elektriese kabel geplaas word verhoed dat hoë frekwensie interferensie deur die kabel versprei word. Klein induktor en kapasitor kombinasies word in resonante netwerke gebruik vir radio-opvangs en uitsaai.

Twee of meer magneties gekoppelde induktors vorm 'n transformator wat 'n fundamentele komponent is in elektrisiteits voorsiening netwerke is.

'n Induktor kan gebruik word as 'n energie stoor toestel in 'n skakel kragbron. Die induktor word gelaai vir 'n spesifieke fraksie van die skakel kragbron reguleerder frekwensie en ontlaai vir die oorblywende siklus. Die laai/ontlaai verhouding bepaal die uitset tot inset spannings verhouding.

Induktors word ook gebruik in elektrisiteitsvoorsiening netwerke, om stelsel spannings te onderdruk, of stroom te beperk. In die veld staan induktors bekend as reaktors.

Aangesien induktors groot en swaar komponente is word hulle al hoe minder in moderne elektriese toestelle gebruik. Half geleier skakel kragbronne maak gebruik van kleiner transformators wat by hoër frekwensies werk as lineêre kragbronne. Elektriese stroombane word ontwerp om klein induktors te gebruik waar nodig, anders word groot induktors vervang met 'n gyrator stroombaan.

[wysig] Sien ook

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個人分類：學術研究

Mar 16 Mon 2009 12:06
電感元件 www.tool-tool.com

Bewise Inc. www.tool-tool.com Reference source from the internet.

電感元件是一個被動電子元件，電子電路運用其電感屬性，電感元件有許多種形式。通過較小電流，僅充當濾波作用的小電感也稱磁珠（Bead）。通過較大電流，作為電磁鐵使用的電感和在變壓器中使用的電感也稱線圈。配合鐵磁性材料，安裝在變壓器、電動機和發電機中使用的大電感也稱繞組。

電感元件

電感符號

[編輯] 物理

[編輯] 概述

電感，單位亨利，由載流導體周圍形成的磁場產生。通過導體的電流產生與電流成比例的磁通量。一個電流的變化產生一個磁通量的變化, 與此同時也產生一個電動勢以「反抗」這種電流的變化，電感即測量電流單位變化引起的電動勢，比如，當電流以1安培/秒的變化速率穿過一個1亨的電感，則引起1v的感應電動勢。當纏繞導體的導線匝數增多，導體的電感也會變大，不僅匝數，每匝（環路）面積，連纏繞材料都會影響電感大小。此外，用高滲透性材料纏繞導體也會令磁通量增加。

[編輯] 儲存的能量

一個電感元件儲存的能量（單位焦）等於流經它的電流建立磁場所做的功，其值由下式給出：

$E_\mathrm{stored} = {1 \over 2} L I^2$

其中L為電感，I為流經電感的電流

[編輯] 水壓模型

電流可以被模擬為水流一樣，電感元件相當與被水流驅動的渦輪中的「飛輪」（flywheel）。電壓與電流大小的改變成正比，所以電流的急速改變會產生強力的電壓。相似地，流向渦輪的水流被突然干擾時會產生巨大的壓力。於變壓器中的磁力交流沒有被有效地以模型形式模擬出來。

[編輯] 電感元件結構

電感元件. 大刻度為cm.

電感可由電導材料盤繞磁芯製成，典型的如銅線，也可把磁芯去掉或者用鐵磁性材料代替。比空氣的磁導率（permeability）高的芯材料可以把磁場更緊密的約束在電感元件周圍，因而增大了電感。電感有很多種，大多以外層陶瓷線圈（enamel coated wire ）環繞鐵素體（ferrite）線軸製成，而有些防護電感把線圈完全置於鐵素體內。一些電感元件的芯可以調節。由此可以改變電感大小。小電感能直接蝕刻在PCB板上，用一種鋪設螺旋軌跡的方法。小值電感也可用以製造電晶體同樣的工藝製造在集成電路中。在這些應用中，鋁互連線被經常用做傳導材料。不管用何種方法，基於實際的約束應用最多的還是一種叫做「旋轉子」的電路，它用一個電容和主動元件表現出與電感元件相同的特性。用於隔高頻的電感元件經常用一根穿過磁柱或磁珠的金屬絲構成。

[編輯] 在電子電路中

像電容元件反抗電壓的變化一樣，電感元件反抗電流的變化。一個理想電感元件應對直流電不呈電阻性，然而只有超導電感元件才會產生零電阻。

一般來說，隨時間變化的電壓v(t)與隨時間變化的電流i(t)在一個電感為L的電感元件上呈現的關係可以用微分方程來表示：

$v(t) = L \frac{di(t)}{dt}.$

當有正弦交流電穿過電感元件時，會產生正弦電壓。電壓的幅度與電流的幅度(I_P) 與電流的頻率(f)的乘積成比例。

$i(t) = I_P \sin(2 \pi f t)\,$

$\frac{di(t)}{dt} = 2 \pi f I_P \cos(2 \pi f t)$

$v(t) = 2 \pi f L I_P \cos(2 \pi f t)\,$

在這種情況下，電流與電壓的相位相差90度，（電流落後電壓）

[編輯] 拉普拉斯電路分析 (s-域)

當於電路分析中使用拉普拉斯變換，一個沒有初始電流的理想電感元件的阻抗能於s域被表述成 :

$Z(s) = s L\,$

L為電感

s為複頻率

如果電感元件沒有起始電流，那它可以被表述成 :

附加一個電壓來源，以串聯形式與電感元件連接著，電壓來源的值為 :

$L I_0 \,$

(請留意電壓來源應該有與初始電流相反的極性)

或是附加一個電流來源，以並聯形式與電感元件連接著，電流來源的值為 :

$\frac{I_0}{s}$

L為電感

I₀為電感元件的初始電流

[編輯] 電感元件網路

主條目：串聯與並聯電路

並聯電路中的電感元件每個都有相同的電勢差 .其總的等效電感 (L_eq):

$\frac{1}{L_\mathrm{eq}} = \frac{1}{L_1} + \frac{1}{L_2} + \cdots + \frac{1}{L_n}$

通過串聯電感的電流保持不變,但每個電感元件上的電壓可不同.其電壓之和等於總電壓.總電感:

$L_\mathrm{eq} = L_1 + L_2 + \cdots + L_n \,\!$

這種簡單的關係只有在沒有磁場互耦（mutual coupling）的條件下才成立。

[編輯] 品質因數Q

一個理想的電感元件是不會因流經線圈的電流的大小而改變其敏感度。但是於實際環境下，線圈內的金屬線會令電感元件帶有繞組電阻。由於繞組電阻是以串聯著電感元件的電阻形式出現，所以亦被稱為串聯電阻。電感元件的串聯電阻將流經線圈的電流內的電能轉化成熱能，那會形式電感元件的品質下降。所以品質因數才會出現，一個電感元件的品質因數(簡稱Q)是它處於某一特定頻率時，它的電感電抗和電抗之間的比例，這個比例是用來量度電感元件的有效程度。品質因數越高，電感元件的表現越相似現想中電感元件的表現。

電感元件的品質因數Q能由以下方程式可得，R是電感元件的內部電抗 :

$Q = \frac{\omega{}L}{R}$

使用鐵磁性核心而其他部份不變的話，電感會上升，因為品質因數會被提高。但是這種核心會於頻率上升時降低電感。所以於甚高頻(VHF)或更高頻的情況下，空氣核心會被傾向於使用。使用鐵磁性核心的電感元件可能會於大量電流流入時進入飽和狀態，引致電感及品質因數下降。使用空氣核心能避免這種現象。一個經良好設計的含空氣核心的電感元件能有高達幾百的品質因數。

一個近乎理想的電感元件(即近乎無限的的品質因數)可以由以下方法所製 : 將由超導合金所製的線圈浸入液態氦或液態氮中。這會令電線處於極低溫狀態，而繞組電阻會消失。因為超導電感元件的效能極近乎理想中的電感元件，它可以儲存大量電能於磁場內。(見SMES)

[編輯] 公式

1. 基本電感公式對圓柱形纏繞:
$L=\frac{\mu_0\mu_rN^2A}{l}$

L = 電感單位亨利 (H)

μ₀ = 自由空間的磁導率 = 4π × 10^-7 H/m

μ_r = 芯材料的相對磁導率

N = 匝數

A = 環繞的橫斷面積單位平方米 (m²)

l = 盤繞長度單位米s (m)

2. 直線導體的電感:
$L = l\left(\ln\frac{4l}{d1\right) \cdot 200 \times 10^{-9}$ }-

L = 電感單位 H

l = 導體長度單位米

d = 導體直徑單位米

因此一個長10mm，直徑1mm的導體電感為5.38nH，而長度改為100mm後電感為100nH。

相同公式用英制單位:
$L = 5.08 \cdot l\left(\ln\frac{4l}{d1\right)$ }-

L = 電感單位 nH

l = 導體長度單位英寸

d = 導體直徑單位英寸

3. 短圓柱盤繞無芯（空氣）電感元件的電感:
$L=\frac{r^2N^2}{9r+10l}$

L = 電感單位 µH

r = 纏繞的外環半徑單位英寸

l = 纏繞長度單位英寸

N = 匝數

4. 多層空氣芯電感元件:
$L = \frac{0.8r^2N^2}{6r+9l+10d}$

L = 電感單位 µH

r = 纏繞平均半徑單位英寸

l = 繞線物理長度單位英寸

N = 匝數

d = 纏繞深度單位英寸 (即, 外半徑減去內半徑)

5. 平螺旋型空芯電感:
$L=\frac{r^2N^2}{(2r+2.8d) \times 10^5}$

L = 電感單位 H

r = 纏繞平均半徑單位米

N = 匝數

d = 纏繞深度單位米 (即, 外半徑減去內半徑)

因此一個8匝的螺旋型盤繞，平均半徑25mm，深度10mm的電感元件，電感為5.13µH。

同樣的公式改用英制單位:
$L=\frac{r^2N^2}{8r+11d}$

L = 電感單位 µH

r = 纏繞平均半徑單位英寸

N = 匝數

d = 纏繞深度單位英寸 (即, 外半徑減去內半徑)

6. 環形鐵心的繞阻電感(核心物料的的圓形橫切面的相對導率為μ_r)

$L=\mu_0\mu_r\frac{N^2r^2}{D}$

L = 電感單位 H

μ₀ = 真空中的導率 = 4π × 10^-7 H/m

μ_r = 核心物料的相對導率

N = 匝數

r = 纏繞平均半徑單位米

D = 環形線圈的總直徑單位米

[編輯] 應用

電感元件廣泛的應用在模擬電路與信號處理過程中。

電感元件與電容元件及其他一些器件結合可以形成調諧電路，可以放大或過濾一些特定的信號頻率。
大電感可用於電源的閥門（chokes），以前也經常與濾波器聯用用於去處直流輸出的冗餘和波動成分。
磁珠或環繞電纜可產生小電感可阻止傳輸線中的射頻干擾。
小的電容/電感還可結合產生調諧電路用於無線電的收發。
兩個或多個電感元件之間有耦合磁通量可形成變壓器，變壓器是電力電源系統的基本組件。變壓器的效率隨著頻率的增加而減小，但高頻變壓器的體積也變的很小，這也是為什麼一些飛行器用400赫茲交流電而不是通常的50或60赫茲，用小型變壓器而節省了大量的載重。
在開關式電源中，電感元件被做為儲能元件。電感元件隨著調整器的轉換頻率的特定部分而儲能，而在周期後半部分釋放能量。其能量轉換比決定了輸入輸出電壓比。這個 X_L 用於補充主動半導體設備可用來精確控制電壓。

電感元件也被應用於電力傳輸系統，用來降低系統電壓或限制疵電流（fault current），這些通常被用於反應爐。相比其他元件電感元件要顯得大而重，所以在現代設備里以減少了其應用；固態開關電源去掉了大變壓器，電路轉為使用小的電感元件，而大值則由迴轉器（gyrator）電路模擬。

歡迎來到Bewise Inc.的世界，首先恭喜您來到這接受新的資訊讓產業更有競爭力，我們是提供專業刀具製造商，應對客戶高品質的刀具需求，我們可以協助客戶滿足您對產業的不同要求，我們有能力達到非常卓越的客戶需求品質，這是現有相關技術無法比擬的，我們成功的滿足了各行各業的要求，包括：精密HSS DIN切削刀具、協助客戶設計刀具流程、DIN or JIS 鎢鋼切削刀具設計、NAS986 NAS965 NAS897 NAS937orNAS907 航太切削刀具,NAS航太刀具設計、超高硬度的切削刀具、醫療配件刀具設計、複合式再研磨機、PCD地板專用企口鑽石組合刀具、NSK高數主軸與馬達、專業模具修補工具-氣動與電動、粉末造粒成型機、主機版專用頂級電桿、PCD V-Cut刀、捨棄式圓鋸片組、粉末成型機、主機版專用頂級電感、’汽車業刀具設計、電子產業鑽石刀具、木工產業鑽石刀具、銑刀與切斷複合再研磨機、銑刀與鑽頭複合再研磨機、銑刀與螺絲攻複合再研磨機等等。我們的產品涵蓋了從民生刀具到工業級的刀具設計；從微細刀具到大型刀具；從小型生產到大型量產；全自動整合；我們的技術可提供您連續生產的效能，我們整體的服務及卓越的技術，恭迎您親自體驗！！

BW Bewise Inc. Willy Chen willy@tool-tool.com bw@tool-tool.com www.tool-tool.com skype:willy_chen_bw mobile:0937-618-190 Head &Administration Office No.13,Shiang Shang 2nd St., West Chiu Taichung,Taiwan 40356 http://www.tool-tool.com / FAX:+886 4 2471 4839 N.Branch 5F,No.460,Fu Shin North Rd.,Taipei,Taiwan S.Branch No.24,Sec.1,Chia Pu East Rd.,Taipao City,Chiayi Hsien,Taiwan

Welcome to BW tool world! We are an experienced tool maker specialized in cutting tools. We focus on what you need and endeavor to research the best cutter to satisfy users’ demand. Our customers involve wide range of industries, like mold & die, aerospace, electronic, machinery, etc. We are professional expert in cutting field. We would like to solve every problem from you. Please feel free to contact us, its our pleasure to serve for you. BW product including: cutting tool、aerospace tool .HSS DIN Cutting tool、Carbide end mills、Carbide cutting tool、NAS Cutting tool、NAS986 NAS965 NAS897 NAS937orNAS907 Cutting Tools,Carbide end mill、disc milling cutter,Aerospace cutting tool、hss drill’Фрезеры’Carbide drill、High speed steel、Compound Sharpener’Milling cutter、INDUCTORS FOR PCD’CVDD(Chemical Vapor Deposition Diamond )’PCBN (Polycrystalline Cubic Boron Nitride) ’Core drill、Tapered end mills、CVD Diamond Tools Inserts’PCD Edge-Beveling Cutter(Golden Finger’PCD V-Cutter’PCD Wood tools’PCD Cutting tools’PCD Circular Saw Blade’PVDD End Mills’diamond tool. INDUCTORS FOR PCD . POWDER FORMING MACHINE ‘Single Crystal Diamond ‘Metric end mills、Miniature end mills、Специальные режущие инструменты ‘Пустотелое сверло ‘Pilot reamer、Fraises’Fresas con mango’ PCD (Polycrystalline diamond) ‘Frese’POWDER FORMING MACHINE’Electronics cutter、Step drill、Metal cutting saw、Double margin drill、Gun barrel、Angle milling cutter、Carbide burrs、Carbide tipped cutter、Chamfering tool、IC card engraving cutter、Side cutter、Staple Cutter’PCD diamond cutter specialized in grooving floors’V-Cut PCD Circular Diamond Tipped Saw Blade with Indexable Insert’ PCD Diamond Tool’ Saw Blade with Indexable Insert’NAS tool、DIN or JIS tool、Special tool、Metal slitting saws、Shell end mills、Side and face milling cutters、Side chip clearance saws、Long end mills’end mill grinder’drill grinder’sharpener、Stub roughing end mills、Dovetail milling cutters、Carbide slot drills、Carbide torus cutters、Angel carbide end mills、Carbide torus cutters、Carbide ball-nosed slot drills、Mould cutter、Tool manufacturer.

ようこそＢｅｗｉｓｅ　Ｉｎｃ.の世界へお越し下さいませ、先ず御目出度たいのは新たな

情報を受け取って頂き、もっと各産業に競争力プラス展開。

弊社は専門なエンド・ミルの製造メーカーで、客先に色んな分野のニーズ、

豊富なパリエーションを満足させ、特にハイテク品質要求にサポート致します。

弊社は各領域に供給できる内容は：

弊社の製品の供給調達機能は：

弊社の全般供給体制及び技術自慢の総合専門製造メーカーに貴方のご体験を御待ちしております。

Bewise Inc. talaşlı imalat sanayinde en fazla kullanılan ve üç eksende (x,y,z) talaş kaldırabilen freze takımlarından olan Parmak Freze imalatçısıdır. Çok geniş ürün yelpazesine sahip olan firmanın başlıca ürünlerini Karbür Parmak Frezeler, Kalıpçı Frezeleri, Kaba Talaş Frezeleri, Konik Alın Frezeler, Köşe Radyüs Frezeler, İki Ağızlı Kısa ve Uzun Küresel Frezeler, İç Bükey Frezeler vb. şeklinde sıralayabiliriz.

BW специализируется в научных исследованиях и разработках, и снабжаем самым высокотехнологичным карбидовым материалом для поставки режущих / фрезеровочных инструментов для почвы, воздушного пространства и электронной индустрии. В нашу основную продукцию входит твердый карбид / быстрорежущая сталь, а также двигатели, микроэлектрические дрели, IC картонорезальные машины, фрезы для гравирования, режущие пилы, фрезеры-расширители, фрезеры-расширители с резцом, дрели, резаки форм для шлицевого вала / звездочки роликовой цепи, и специальные нано инструменты. Пожалуйста, посетите сайт www.tool-tool.com для получения большей информации.

BW is specialized in R&D and sourcing the most advanced carbide material with high-tech coating to supply cutting / milling tool for mould & die, aero space and electronic industry. Our main products include solid carbide / HSS end mills, micro electronic drill, IC card cutter, engraving cutter, shell end mills, cutting saw, reamer, thread reamer, leading drill, involute gear cutter for spur wheel, rack and worm milling cutter, thread milling cutter, form cutters for spline shaft/roller chain sprocket, and special tool, with nano grade. Please visit our web www.tool-tool.com for more info.

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個人分類：學術研究

Mar 16 Mon 2009 11:58
Русский Линейный фильтр www.tool-tool.com

Bewise Inc. www.tool-tool.com Reference source from the internet.

Линейный фильтр — динамическая система, применяющая некий линейный оператор ко входному сигналу для выделения или подавления определённых частот сигнала и других функций по обработке входного сигнала. Линейные фильтры широко применяются в электронике, цифровой обработке сигналов и изображений, в оптике, теории управления и других областях.

Наиболее часто они используются для того, чтобы подавить нежелательные частоты входного сигнала или для того чтобы выделить нужную полосу частот в сигнале. Существует большое количество различных типов и модификаций линейных фильтров, в статье описаны наиболее распространённые.

Несмотря на природу фильтра — механическую, оптическую, электронную, программную или электрическую, а также на частотный диапазон, в котором они работают, математическая теория линейных фильтров универсальна и может быть применена к любому из них.

Содержание

[убрать]

[править] Классификация по передаточной функции

[править] Импульсная переходная функция

Линейные фильтры разделяются на два больших класса по виду импульсной переходной функции: фильтр с бесконечной импульсной характеристикой (БИХ-фильтры) и фильтр с конечной импульсной характеристикой (КИХ-фильтры). До недавнего времени практическое использование имели только аналоговые БИХ-фильтры, однако с развитием цифровой техники КИХ-фильтры стали применяться повсеместно.

[править] Частотные характеристики

По виду частотной характеристики фильтры подразделяются на:

Фильтр низких частот — пропускает низкие частоты сигнала.
Фильтр высоких частот — пропускает высокие частоты сигнала.
Полосовой фильтр — пропускает ограниченную полосу частот сигнала.
Режекторный фильтр пропускает все частоты, кроме определённой полосы.
Фазовый фильтр пропускает все частоты сигнала, но изменяет его фазу.

Полосовые и режекторные фильтры могут быть сконструированы путём последовательного соединения фильтров низких и высоких частот.

[править] Проектирование фильтров

Линейные фильтры всех видов могут быть однозначно описаны с помощью их амплитудной и фазо-частотной характеристик, либо импульсной характеристики. С математической точки зрения непрерывные БИХ-фильтры описываются линейными дифференциальными уравнениями, а их импульсные характеристики — функции Грина для этих уравнений. Непрерывные фильтры также могут быть описаны с помощью преобразования Лапласа импульсной характеристики (в случае дискретных фильтров используется Z-преобразование).

Для проектирования фильтров широко применяются графические способы, например, с помощью диаграмм Боде или Найквиста, а также проектирование на комплексной плоскости, путём размещения нулей и полюсов передаточной функции фильтра.

Существует ряд различных типов фильтров по виду частотной характеристики, обеспечивающих качественное выполнение тех или иных задач.

Наиболее распространённые типы БИХ-фильтров:

КИХ-фильтры могут быть осуществлены с помощью свёртки сигнала с импульсной характеристикой фильтра.

[править] См. также

歡迎來到Bewise Inc.的世界，首先恭喜您來到這接受新的資訊讓產業更有競爭力，我們是提供專業刀具製造商，應對客戶高品質的刀具需求，我們可以協助客戶滿足您對產業的不同要求，我們有能力達到非常卓越的客戶需求品質，這是現有相關技術無法比擬的，我們成功的滿足了各行各業的要求，包括：精密HSS DIN切削刀具、協助客戶設計刀具流程、DIN or JIS 鎢鋼切削刀具設計、NAS986 NAS965 NAS897 NAS937orNAS907 航太切削刀具,NAS航太刀具設計、超高硬度的切削刀具、醫療配件刀具設計、複合式再研磨機、PCD地板專用企口鑽石組合刀具、NSK高數主軸與馬達、專業模具修補工具-氣動與電動、粉末造粒成型機、主機版專用頂級電桿、PCD V-Cut刀、捨棄式圓鋸片組、粉末成型機、主機版專用頂級電感、’汽車業刀具設計、電子產業鑽石刀具、木工產業鑽石刀具、銑刀與切斷複合再研磨機、銑刀與鑽頭複合再研磨機、銑刀與螺絲攻複合再研磨機等等。我們的產品涵蓋了從民生刀具到工業級的刀具設計；從微細刀具到大型刀具；從小型生產到大型量產；全自動整合；我們的技術可提供您連續生產的效能，我們整體的服務及卓越的技術，恭迎您親自體驗！！

BW Bewise Inc. Willy Chen willy@tool-tool.com bw@tool-tool.com www.tool-tool.com skype:willy_chen_bw mobile:0937-618-190 Head &Administration Office No.13,Shiang Shang 2nd St., West Chiu Taichung,Taiwan 40356 http://www.tool-tool.com / FAX:+886 4 2471 4839 N.Branch 5F,No.460,Fu Shin North Rd.,Taipei,Taiwan S.Branch No.24,Sec.1,Chia Pu East Rd.,Taipao City,Chiayi Hsien,Taiwan

Welcome to BW tool world! We are an experienced tool maker specialized in cutting tools. We focus on what you need and endeavor to research the best cutter to satisfy users’ demand. Our customers involve wide range of industries, like mold & die, aerospace, electronic, machinery, etc. We are professional expert in cutting field. We would like to solve every problem from you. Please feel free to contact us, its our pleasure to serve for you. BW product including: cutting tool、aerospace tool .HSS DIN Cutting tool、Carbide end mills、Carbide cutting tool、NAS Cutting tool、NAS986 NAS965 NAS897 NAS937orNAS907 Cutting Tools,Carbide end mill、disc milling cutter,Aerospace cutting tool、hss drill’Фрезеры’Carbide drill、High speed steel、Compound Sharpener’Milling cutter、INDUCTORS FOR PCD’CVDD(Chemical Vapor Deposition Diamond )’PCBN (Polycrystalline Cubic Boron Nitride) ’Core drill、Tapered end mills、CVD Diamond Tools Inserts’PCD Edge-Beveling Cutter(Golden Finger’PCD V-Cutter’PCD Wood tools’PCD Cutting tools’PCD Circular Saw Blade’PVDD End Mills’diamond tool. INDUCTORS FOR PCD . POWDER FORMING MACHINE ‘Single Crystal Diamond ‘Metric end mills、Miniature end mills、Специальные режущие инструменты ‘Пустотелое сверло ‘Pilot reamer、Fraises’Fresas con mango’ PCD (Polycrystalline diamond) ‘Frese’POWDER FORMING MACHINE’Electronics cutter、Step drill、Metal cutting saw、Double margin drill、Gun barrel、Angle milling cutter、Carbide burrs、Carbide tipped cutter、Chamfering tool、IC card engraving cutter、Side cutter、Staple Cutter’PCD diamond cutter specialized in grooving floors’V-Cut PCD Circular Diamond Tipped Saw Blade with Indexable Insert’ PCD Diamond Tool’ Saw Blade with Indexable Insert’NAS tool、DIN or JIS tool、Special tool、Metal slitting saws、Shell end mills、Side and face milling cutters、Side chip clearance saws、Long end mills’end mill grinder’drill grinder’sharpener、Stub roughing end mills、Dovetail milling cutters、Carbide slot drills、Carbide torus cutters、Angel carbide end mills、Carbide torus cutters、Carbide ball-nosed slot drills、Mould cutter、Tool manufacturer.

ようこそＢｅｗｉｓｅ　Ｉｎｃ.の世界へお越し下さいませ、先ず御目出度たいのは新たな

情報を受け取って頂き、もっと各産業に競争力プラス展開。

弊社は専門なエンド・ミルの製造メーカーで、客先に色んな分野のニーズ、

豊富なパリエーションを満足させ、特にハイテク品質要求にサポート致します。

弊社は各領域に供給できる内容は：

弊社の製品の供給調達機能は：

弊社の全般供給体制及び技術自慢の総合専門製造メーカーに貴方のご体験を御待ちしております。

Bewise Inc. talaşlı imalat sanayinde en fazla kullanılan ve üç eksende (x,y,z) talaş kaldırabilen freze takımlarından olan Parmak Freze imalatçısıdır. Çok geniş ürün yelpazesine sahip olan firmanın başlıca ürünlerini Karbür Parmak Frezeler, Kalıpçı Frezeleri, Kaba Talaş Frezeleri, Konik Alın Frezeler, Köşe Radyüs Frezeler, İki Ağızlı Kısa ve Uzun Küresel Frezeler, İç Bükey Frezeler vb. şeklinde sıralayabiliriz.

BW специализируется в научных исследованиях и разработках, и снабжаем самым высокотехнологичным карбидовым материалом для поставки режущих / фрезеровочных инструментов для почвы, воздушного пространства и электронной индустрии. В нашу основную продукцию входит твердый карбид / быстрорежущая сталь, а также двигатели, микроэлектрические дрели, IC картонорезальные машины, фрезы для гравирования, режущие пилы, фрезеры-расширители, фрезеры-расширители с резцом, дрели, резаки форм для шлицевого вала / звездочки роликовой цепи, и специальные нано инструменты. Пожалуйста, посетите сайт www.tool-tool.com для получения большей информации.

BW is specialized in R&D and sourcing the most advanced carbide material with high-tech coating to supply cutting / milling tool for mould & die, aero space and electronic industry. Our main products include solid carbide / HSS end mills, micro electronic drill, IC card cutter, engraving cutter, shell end mills, cutting saw, reamer, thread reamer, leading drill, involute gear cutter for spur wheel, rack and worm milling cutter, thread milling cutter, form cutters for spline shaft/roller chain sprocket, and special tool, with nano grade. Please visit our web www.tool-tool.com for more info.

beeway 發表在痞客邦留言(0) 人氣()

個人分類：學術研究

Mar 16 Mon 2009 11:52
Português Filtro linear www.tool-tool.com

Bewise Inc. www.tool-tool.com Reference source from the internet.

Um filtro linear aplica uma operação matemática linear a um sinal de entrada. Os filtros lineares são muito comuns na eletrônica e no processamento digital de sinais, porém também são utilizados na engenharia mecânica, física, entre outras.

São comumente utilizados para eliminar as frequências não desejadas de um sinal de entrada ou para selecionar uma frequência de um sinal. Existe uma grande variedade de filtros e tecnologias de filtros.

Independentemente se eles são eletrônicos, elétricos ou mecânicos, ou em quais faixas de frequência trabalhem, a teoria matemática dos filtros lineares é a mesma.

Índice

[esconder]

[editar] Classificação pela função de transferência

[editar] Resposta ao impulso

Os filtros lineares podem ser divididos em duas classes: filtos resposta de impulso infinita (IIR), e resposta de impulso finita (FIR). Em geral, um filtro com uma resposta em frequência compacta possuirá uma resposta de impulso infinita e um filtro com uma resposta de impulso compacta terá uma resposta de impulso finita. Até pouco tempo atrás, apenas os filtros IIR analógicos possuiam uma construção prática. Entretanto, tecnologias como as linha de atraso analógicas e os filtros digitais tornaram a construção de filtros FIR prática.

[editar] Resposta em frequência

Existem vários tipos de filtros lineares, entre eles:

Um filtro passa-baixas permite a passagem de frequências abaixo de sua frequência de corte.
Um filtro passa-altas permite a passagem de frequências acima de sua frequência de corte.
Um filtro passa-faixa permite a passagem apenas de uma faixa de frequências.
Um filtro rejeita-faixa permite a passagem de todas as frequências fora de uma certa faixa.
Um filtro passa-tudo permite a passagem de todas as frequências, porém altera a relação de fase entre elas.
Um filtro de corte é um tipo específico de filtro rejeita-faixa que atua em uma faixa particularmente limitada de frequências.
alguns filtros não são projetados de modo a bloquear nenhuma frequência, mas ao invés disso apenas para variar a amplitude a diferentes frequências: O filtro de pré-enfase, os equalizadores e os controles de tom são exemplos deste gênero de filtros.

Os filtros passa baixa e passa altas podem ser construídos a partir de combinações entre os filtros passa-baixas e passa-altas.

Uma forma popular de filtro de 2 pólos é o filtro Sallen Key. Este é capaz de produzir versões passa-baixas, passa-banda e passa-altas.

[editar] A matemática do projeto de filtros

Os filtros lineares de todos os tipos podem ser completamente descritos através de sua resposta em frequência e de sua resposta em fase, a especificação de um destes pontos define o outro. De um ponto de vista matemático, os filtros IIR de tempo contínuo podem ser descritos através de equações diferenciais lineares, e sua resposta em impulso considerado como uma função de Green da equação. Filtros de tempo contínuo podem também ser descritos através da transformada de Laplace de sua resposta em impulso de tal forma que permita que todas as características do filtro sejam facilmente analizadas considerando a imagem do pólo e do zero em sua transformada de Laplace no plano complexo.

Antes do surgimento das ferramentas de análise computadorizadas, acessórios como o gráfico da resposta em frequência e gráfico de Nyquist eram extensivamente utilizados como ferramentas de projeto. Mesmo hoje em dia, estes ainda são ferramentas muito importantes para a compreensão do comportamento dos filtros.

Muitos projetos de filtros analógicos têm sido desenvolvidos, cada um buscando otimizar certa característica da resposta do sistema. Para filtros práticos, um projeto padrão é muitas vezes desejado, de modo que possa se encaixar nos critérios do projeto, que podem incluir a contagem e preço dos componentes, assim como as características da resposta em frequência.

Alguns filtros IIR clássicos são os seguintes:

Estas descrições se referem às características matemáticas dos filtros (que são a resposta em frequência e fase). Estes podem ser implementados através de circuitos analógicos, ou através de algoritmos em sistemas de processamento digital de sinal.

Os filtros digitais são muito mais flexíveis em seu projeto e uso do que os filtros analógicos, aonde as limitações do projeto permitem seu uso. Notavelmente, não há a necessidade de considerar as tolerâncias dos componentes, e nível de Q muito altos podem ser obtidos.

Os filtros digitais FIR podem ser implementados através da convolução direta da resposta de impulso desejada para o sinal de entrada.

Os filtros digitais IIR também são relativamente fáceis de serem projetados. Entretanto, os filtros digitais IIR possuem seus problemas matemáticos de projeto, em particular relacionados à faixa dinâmica e a problemas de como o final da região de não linearidade.

[editar] Ver também

[editar] Ligações externas

Electronic Filter Design Handbook, Arthur B Williams e Fred J Taylor, Editora McGraw-Hill ISBN 0-07-070441-4

National Semiconductor AN-779 application note describing analog filter theory

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Welcome to BW tool world! We are an experienced tool maker specialized in cutting tools. We focus on what you need and endeavor to research the best cutter to satisfy users’ demand. Our customers involve wide range of industries, like mold & die, aerospace, electronic, machinery, etc. We are professional expert in cutting field. We would like to solve every problem from you. Please feel free to contact us, its our pleasure to serve for you. BW product including: cutting tool、aerospace tool .HSS DIN Cutting tool、Carbide end mills、Carbide cutting tool、NAS Cutting tool、NAS986 NAS965 NAS897 NAS937orNAS907 Cutting Tools,Carbide end mill、disc milling cutter,Aerospace cutting tool、hss drill’Фрезеры’Carbide drill、High speed steel、Compound Sharpener’Milling cutter、INDUCTORS FOR PCD’CVDD(Chemical Vapor Deposition Diamond )’PCBN (Polycrystalline Cubic Boron Nitride) ’Core drill、Tapered end mills、CVD Diamond Tools Inserts’PCD Edge-Beveling Cutter(Golden Finger’PCD V-Cutter’PCD Wood tools’PCD Cutting tools’PCD Circular Saw Blade’PVDD End Mills’diamond tool. INDUCTORS FOR PCD . POWDER FORMING MACHINE ‘Single Crystal Diamond ‘Metric end mills、Miniature end mills、Специальные режущие инструменты ‘Пустотелое сверло ‘Pilot reamer、Fraises’Fresas con mango’ PCD (Polycrystalline diamond) ‘Frese’POWDER FORMING MACHINE’Electronics cutter、Step drill、Metal cutting saw、Double margin drill、Gun barrel、Angle milling cutter、Carbide burrs、Carbide tipped cutter、Chamfering tool、IC card engraving cutter、Side cutter、Staple Cutter’PCD diamond cutter specialized in grooving floors’V-Cut PCD Circular Diamond Tipped Saw Blade with Indexable Insert’ PCD Diamond Tool’ Saw Blade with Indexable Insert’NAS tool、DIN or JIS tool、Special tool、Metal slitting saws、Shell end mills、Side and face milling cutters、Side chip clearance saws、Long end mills’end mill grinder’drill grinder’sharpener、Stub roughing end mills、Dovetail milling cutters、Carbide slot drills、Carbide torus cutters、Angel carbide end mills、Carbide torus cutters、Carbide ball-nosed slot drills、Mould cutter、Tool manufacturer.

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BW is specialized in R&D and sourcing the most advanced carbide material with high-tech coating to supply cutting / milling tool for mould & die, aero space and electronic industry. Our main products include solid carbide / HSS end mills, micro electronic drill, IC card cutter, engraving cutter, shell end mills, cutting saw, reamer, thread reamer, leading drill, involute gear cutter for spur wheel, rack and worm milling cutter, thread milling cutter, form cutters for spline shaft/roller chain sprocket, and special tool, with nano grade. Please visit our web www.tool-tool.com for more info.

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個人分類：學術研究

Mar 16 Mon 2009 11:46
Français Filtre linéaire www.tool-tool.com

Bewise Inc. www.tool-tool.com Reference source from the internet.

Un filtre linéaire est, en traitement du signal, un système qui applique un opérateur linéaire à un signal d'entrée. Les filtres linéaires sont rencontrés le plus souvent en électronique, mais il est possible d'en trouver en mécanique ou dans d'autres technologies.

Sommaire

[masquer]

Classification [modifier]

Réponse impulsionnelle [modifier]

Réponse impulsionnelle est la sortie d'un système dont l'entrée est une impulsion de Dirac(δ). Les filtres linéaires peuvent être divisés en deux groupes : les filtres à réponse impulsionnelle infinie et les filtres à réponse impulsionnelle finie. Pour ceux à réponse impulsionnelle finie, la sortie du système dépend uniquement de l'entrée alors que pour ceux à réponse impulsionnelle infinie, la sortie du système dépend à la fois de l'entrée et des sorties précédentes.

Réponse fréquentielle [modifier]

Du point de vue fréquentiel, il existe plusieurs types courants de filtres linéaires :

Les filtres passe-bas passent les basses fréquences et coupent les hautes
Les filtres passe-haut passent les hautes fréquences et coupent les basses
Les filtres passe-bande ne laissent passer qu'une bande de fréquence limitée
Les filtres coupe-bande, à l'inverse, laissent passer toutes les fréquences, sauf une bande spécifique
Les filtres toutes-bandes n'atténuent aucune fréquence, mais altèrent leur phase.
Certains filtres ne sont pas conçus pour arrêter une fréquence, mais pour modifier légèrement le gain à différentes fréquences, comme les égaliseurs.

Types de filtres linéaires [modifier]

Les filtres linéaires opèrent physiquement soit dans le domaine temporel (électricité, mécanique, son, ...) soit dans le domaine spatial (traitement d'image). La description la plus parlante se situe dans le domaine fréquentiel car elle fait apparaître l'amplification et le déphasage d'une sinusoïde dont la fréquence est inchangée (c'est la caractéristique d'un système linéaire) sous la forme de la fonction de transfert exprimée en fréquences. La transformation de Fourier fait passer au domaine temporel ou spatial dans lequel le filtre est représenté par sa réponse impulsionnelle (pour une présentation différente voir Système mécanique linéaire).

A côté des filtres analogiques traditionnels existent des filtres numériques dans lesquels la convolution avec le signal d'entrée numérisé utilise une matrice et non une fonction mathématique.

Les filtres spatiaux se distinguent en général des filtres temporels par le fait qu'ils portent sur au moins deux variables.

Conception [modifier]

Tout filtre linéaire est entièrement décrit par sa réponse fréquentielle et sa réponse de phase, liée à sa réponse impulsionnelle. Du point de vue mathématique, un filtre continu à réponse impulsionnelle infinie peut être décrit en terme d'équations différentielles linéaires et sa réponse impulsionnelle comme la fonction de Green des équations. Il est également possible d'exprimer la fonction de transfert du filtre à l'aide de la transformée de Laplace de leur réponse impulsionnelle ; cette méthode permet d'analyser simplement le filtre en considérant les pôles et les zéros de la transformée de Laplace.

Avant la généralisation des outils informatiques de synthèse de filtre, les outils graphiques comme le diagramme de Bode ou le diagramme de Nyquist étaient énormément employés. Ils demeurent d'ailleurs une aide essentielle pour appréhender le comportement d'un filtre.

Différentes méthodes de conception de filtres analogiques ont été mises au point, chacune optimisant un point spécifique, comme pas exemple :

Ces méthodes de conception décrivent les propriétés mathématiques du filtre (réponse en fréquence et en phase). Ils peuvent être implémentés, par exemple sous forme de circuits électroniques, par d'autres méthodes.

歡迎來到Bewise Inc.的世界，首先恭喜您來到這接受新的資訊讓產業更有競爭力，我們是提供專業刀具製造商，應對客戶高品質的刀具需求，我們可以協助客戶滿足您對產業的不同要求，我們有能力達到非常卓越的客戶需求品質，這是現有相關技術無法比擬的，我們成功的滿足了各行各業的要求，包括：精密HSS DIN切削刀具、協助客戶設計刀具流程、DIN or JIS 鎢鋼切削刀具設計、NAS986 NAS965 NAS897 NAS937orNAS907 航太切削刀具,NAS航太刀具設計、超高硬度的切削刀具、醫療配件刀具設計、複合式再研磨機、PCD地板專用企口鑽石組合刀具、NSK高數主軸與馬達、專業模具修補工具-氣動與電動、粉末造粒成型機、主機版專用頂級電桿、PCD V-Cut刀、捨棄式圓鋸片組、粉末成型機、主機版專用頂級電感、’汽車業刀具設計、電子產業鑽石刀具、木工產業鑽石刀具、銑刀與切斷複合再研磨機、銑刀與鑽頭複合再研磨機、銑刀與螺絲攻複合再研磨機等等。我們的產品涵蓋了從民生刀具到工業級的刀具設計；從微細刀具到大型刀具；從小型生產到大型量產；全自動整合；我們的技術可提供您連續生產的效能，我們整體的服務及卓越的技術，恭迎您親自體驗！！

BW Bewise Inc. Willy Chen willy@tool-tool.com bw@tool-tool.com www.tool-tool.com skype:willy_chen_bw mobile:0937-618-190 Head &Administration Office No.13,Shiang Shang 2nd St., West Chiu Taichung,Taiwan 40356 http://www.tool-tool.com / FAX:+886 4 2471 4839 N.Branch 5F,No.460,Fu Shin North Rd.,Taipei,Taiwan S.Branch No.24,Sec.1,Chia Pu East Rd.,Taipao City,Chiayi Hsien,Taiwan

Welcome to BW tool world! We are an experienced tool maker specialized in cutting tools. We focus on what you need and endeavor to research the best cutter to satisfy users’ demand. Our customers involve wide range of industries, like mold & die, aerospace, electronic, machinery, etc. We are professional expert in cutting field. We would like to solve every problem from you. Please feel free to contact us, its our pleasure to serve for you. BW product including: cutting tool、aerospace tool .HSS DIN Cutting tool、Carbide end mills、Carbide cutting tool、NAS Cutting tool、NAS986 NAS965 NAS897 NAS937orNAS907 Cutting Tools,Carbide end mill、disc milling cutter,Aerospace cutting tool、hss drill’Фрезеры’Carbide drill、High speed steel、Compound Sharpener’Milling cutter、INDUCTORS FOR PCD’CVDD(Chemical Vapor Deposition Diamond )’PCBN (Polycrystalline Cubic Boron Nitride) ’Core drill、Tapered end mills、CVD Diamond Tools Inserts’PCD Edge-Beveling Cutter(Golden Finger’PCD V-Cutter’PCD Wood tools’PCD Cutting tools’PCD Circular Saw Blade’PVDD End Mills’diamond tool. INDUCTORS FOR PCD . POWDER FORMING MACHINE ‘Single Crystal Diamond ‘Metric end mills、Miniature end mills、Специальные режущие инструменты ‘Пустотелое сверло ‘Pilot reamer、Fraises’Fresas con mango’ PCD (Polycrystalline diamond) ‘Frese’POWDER FORMING MACHINE’Electronics cutter、Step drill、Metal cutting saw、Double margin drill、Gun barrel、Angle milling cutter、Carbide burrs、Carbide tipped cutter、Chamfering tool、IC card engraving cutter、Side cutter、Staple Cutter’PCD diamond cutter specialized in grooving floors’V-Cut PCD Circular Diamond Tipped Saw Blade with Indexable Insert’ PCD Diamond Tool’ Saw Blade with Indexable Insert’NAS tool、DIN or JIS tool、Special tool、Metal slitting saws、Shell end mills、Side and face milling cutters、Side chip clearance saws、Long end mills’end mill grinder’drill grinder’sharpener、Stub roughing end mills、Dovetail milling cutters、Carbide slot drills、Carbide torus cutters、Angel carbide end mills、Carbide torus cutters、Carbide ball-nosed slot drills、Mould cutter、Tool manufacturer.

ようこそＢｅｗｉｓｅ　Ｉｎｃ.の世界へお越し下さいませ、先ず御目出度たいのは新たな

情報を受け取って頂き、もっと各産業に競争力プラス展開。

弊社は専門なエンド・ミルの製造メーカーで、客先に色んな分野のニーズ、

豊富なパリエーションを満足させ、特にハイテク品質要求にサポート致します。

弊社は各領域に供給できる内容は：

弊社の製品の供給調達機能は：

弊社の全般供給体制及び技術自慢の総合専門製造メーカーに貴方のご体験を御待ちしております。

Bewise Inc. talaşlı imalat sanayinde en fazla kullanılan ve üç eksende (x,y,z) talaş kaldırabilen freze takımlarından olan Parmak Freze imalatçısıdır. Çok geniş ürün yelpazesine sahip olan firmanın başlıca ürünlerini Karbür Parmak Frezeler, Kalıpçı Frezeleri, Kaba Talaş Frezeleri, Konik Alın Frezeler, Köşe Radyüs Frezeler, İki Ağızlı Kısa ve Uzun Küresel Frezeler, İç Bükey Frezeler vb. şeklinde sıralayabiliriz.

BW специализируется в научных исследованиях и разработках, и снабжаем самым высокотехнологичным карбидовым материалом для поставки режущих / фрезеровочных инструментов для почвы, воздушного пространства и электронной индустрии. В нашу основную продукцию входит твердый карбид / быстрорежущая сталь, а также двигатели, микроэлектрические дрели, IC картонорезальные машины, фрезы для гравирования, режущие пилы, фрезеры-расширители, фрезеры-расширители с резцом, дрели, резаки форм для шлицевого вала / звездочки роликовой цепи, и специальные нано инструменты. Пожалуйста, посетите сайт www.tool-tool.com для получения большей информации.

BW is specialized in R&D and sourcing the most advanced carbide material with high-tech coating to supply cutting / milling tool for mould & die, aero space and electronic industry. Our main products include solid carbide / HSS end mills, micro electronic drill, IC card cutter, engraving cutter, shell end mills, cutting saw, reamer, thread reamer, leading drill, involute gear cutter for spur wheel, rack and worm milling cutter, thread milling cutter, form cutters for spline shaft/roller chain sprocket, and special tool, with nano grade. Please visit our web www.tool-tool.com for more info.

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個人分類：學術研究

Linear analog electronic filters

Mar 16 Mon 2009 11:37
English Linear filter www.tool-tool.com

Bewise Inc. www.tool-tool.com Reference source from the internet.

A linear filter applies a linear operator to a time-varying input signal. Linear filters are very common in electronics and digital signal processing (see the article on electronic filters), but they can also be found in mechanical engineering and other technologies.

They are often used to eliminate unwanted frequencies from an input signal or to select a desired frequency among many others. There are a wide range of types of filters and filter technologies, of which this article will present an overview.

Regardless of whether they are electronic, electrical, or mechanical, or what frequency ranges or timescales they work on, the mathematical theory of linear filters is universal.

[edit] Classification by transfer function

[edit] Impulse response

Linear filters can be divided into two classes: infinite impulse response (IIR), and finite impulse response (FIR) filters. In general, a filter with a compact frequency response will have an infinite impulse response and a filter with a compact impulse response will have an infinite frequency response.

An FIR filter may be described as a weighted sum of delayed inputs. For such a filter, if the input becomes zero at any time, then the output will eventually become zero as well, as soon as enough time has passed so that all the delayed inputs are zero, too. Therefore the impulse response lasts only a finite time, hence the name finite impulse response. The transfer function of such a filter contains only zeros, and no poles.

In an IIR filter, by contrast, if the input is set to 0, then the output will decay exponentially, but never become precisely zero. Therefore the impulse response extends to infinity, and the filter is said to have an Infinite Impulse Response. The transfer function of such a filter will contain poles as well as zeros.

Until about the 1970s, only analog IIR filters were practical to construct. However, in digital logic, both FIR and IIR filters are straightforward, and both techniques are commonly used in digital filters. Analog FIR filters are still uncommon, though they can be built with analog delay lines.

[edit] Frequency response

Here is an image comparing the most popular IIR filters: Butterworth, Chebyshev, and elliptic filters. The filters in this illustration are all fifth-order low-pass filters. The particular implementation -- analog or digital, passive or active -- makes little difference^[1]; the output from any implementation would still match this image.

As is clear from the image, elliptic filters are sharper than the others, but they show ripples on the whole bandwidth.

There are several common kinds of linear filters:

A low-pass filter passes low frequencies.
A high-pass filter passes high frequencies.
A band-pass filter passes a limited range of frequencies.
A band-stop filter passes all frequencies except a limited range.
An all-pass filter passes all frequencies, but alters the phase relationship among them.
A notch filter is a specific type of band-stop filter that acts on a particularly narrow range of frequencies.
Some filters are not designed to stop any frequencies, but instead to gently vary the amplitude response at different frequencies: filters used as pre-emphasis filters, equalizers, or tone controls are good examples of this

Band-stop and band-pass filters can be constructed by combining low-pass and high-pass filters. A popular form of 2 pole filter is the Sallen-Key type. This is able to provide low-pass, band-pass, and high pass versions. A particular bandform of filter can be obtained by transformation of a prototype filter of that class.

[edit] Mathematics of filter design

Network synthesis filters [hide]

Image impedance filters [hide]

Simple filters[hide]

edit

LTI system theory describes linear time-invariant (LTI) filters of all types. LTI filters can be completely described by their frequency response and phase response, the specification of which uniquely defines their impulse response, and vice versa. From a mathematical viewpoint, continuous-time IIR LTI filters may be described in terms of linear differential equations, and their impulse responses considered as Green's functions of the equation. Continuous-time LTI filters may also be described in terms of the Laplace transform of their impulse response, which allows all of the characteristics of the filter to be analyzed by considering the pattern of poles and zeros of their Laplace transform in the complex plane. Similarly, discrete-time LTI filters may be analyzed via the Z-transform of their impulse response.

Before the advent of computer filter synthesis tools, graphical tools such as Bode plots and Nyquist plots were extensively used as design tools. Even today, they are invaluable tools to understanding filter behavior. Reference books^[2] had extensive plots of frequency response, phase response, group delay, and impulse response for various types of filters, of various orders. They also contained tables of values showing how to implement such filters as RLC ladders - very useful when amplifying elements were expensive compared to passive components. Such a ladder can also be designed to have minimal sensitivity to component variation^[3] a property hard to evaluate without computer tools.

Many different analog filter designs have been developed, each trying to optimise some feature of the system response. For practical filters, a custom design is sometimes desirable, that can offer the best tradeoff between different design criteria, which may include component count and cost, as well as filter response characteristics.

These descriptions refer to the mathematical properties of the filter (that is, the frequency and phase response). These can be implemented as analog circuits (for instance, using a Sallen Key filter topology, a type of active filter), or as algorithms in digital signal processing systems.

Digital filters are much more flexible to synthesize and use than analog filters, where the constraints of the design permits their use. Notably, there is no need to consider component tolerances, and very high Q levels may be obtained.

FIR digital filters may be implemented by the direct convolution of the desired impulse response with the input signal. They can easily be designed to give a matched filter for any arbitrary pulse shape.

IIR digital filters are often more difficult to design, due to problems including dynamic range issues, quantization noise and instability. Typically digital IIR filters are designed as a series of digital biquad filters.

All low-pass second-order continuous-time filters have a transfer function given by

$H(s)=\frac{K \omega^{2}_{0}}{s^{2}+\frac{\omega_{0}}{Q}s+\omega^{2}_{0}}.$

All band-pass second-order continuous-time have a transfer function given by

$H(s)=\frac{K \frac{\omega_{0}}{Q}s}{s^{2}+\frac{\omega_{0}}{Q}s+\omega^{2}_{0}}.$

where

K is the gain (low-pass DC gain, or band-pass mid-band gain) (K is 1 for passive filters)
Q is the Q factor
ω₀ is the center frequency
s = σ + jω is the complex frequency

[edit] See also

[edit] External links and references

^ A sampled data linear filter, such as most digital filters, will have a slightly different response since it is described by the Z transform, not the Laplace transform. The frequency response will repeat if the frequency becomes high enough, and the curves will be slightly different, but the main features are unchanged.
^ A. Zverev, Handbook of Filter Synthesis, John Wiley and Sons, 1967, ISBN 0-471-98680-1
^ Normally, computing sensitivities is a very laborious operation. But in the special case of an LC ladder driven by an impedance and terminated by a resistor, there is a neat argument showing the sensitivities are small. In such as case, the transmission at the maximum frequency(s) transfers the maximal possible energy to the output load, as determined by the physics of the source and load impedances. Since this point is a maximum, all derivatives with respect to all component values must be zero, since the result of changing any component value in any direction can only result in a reduction. This result only strictly holds true at the peaks of the response, but is roughly true at nearby points as well.

Williams, Arthur B & Taylor, Fred J (1995). Electronic Filter Design Handbook. McGraw-Hill. ISBN 0-07-070441-4.

National Semiconductor AN-779 application note describing analog filter theory
Lattice AN6017 application note comparing and contrasting filters (in order of damping coefficient, from lower to higher values): Gaussian, Bessel, linear phase, Butterworth, Chebyshev, Legendre, elliptic. (with graphs).
"Design and Analysis of Analog Filters: A Signal Processing Perspective" by L. D. Paarmann

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Welcome to BW tool world! We are an experienced tool maker specialized in cutting tools. We focus on what you need and endeavor to research the best cutter to satisfy users’ demand. Our customers involve wide range of industries, like mold & die, aerospace, electronic, machinery, etc. We are professional expert in cutting field. We would like to solve every problem from you. Please feel free to contact us, its our pleasure to serve for you. BW product including: cutting tool、aerospace tool .HSS DIN Cutting tool、Carbide end mills、Carbide cutting tool、NAS Cutting tool、NAS986 NAS965 NAS897 NAS937orNAS907 Cutting Tools,Carbide end mill、disc milling cutter,Aerospace cutting tool、hss drill’Фрезеры’Carbide drill、High speed steel、Compound Sharpener’Milling cutter、INDUCTORS FOR PCD’CVDD(Chemical Vapor Deposition Diamond )’PCBN (Polycrystalline Cubic Boron Nitride) ’Core drill、Tapered end mills、CVD Diamond Tools Inserts’PCD Edge-Beveling Cutter(Golden Finger’PCD V-Cutter’PCD Wood tools’PCD Cutting tools’PCD Circular Saw Blade’PVDD End Mills’diamond tool. INDUCTORS FOR PCD . POWDER FORMING MACHINE ‘Single Crystal Diamond ‘Metric end mills、Miniature end mills、Специальные режущие инструменты ‘Пустотелое сверло ‘Pilot reamer、Fraises’Fresas con mango’ PCD (Polycrystalline diamond) ‘Frese’POWDER FORMING MACHINE’Electronics cutter、Step drill、Metal cutting saw、Double margin drill、Gun barrel、Angle milling cutter、Carbide burrs、Carbide tipped cutter、Chamfering tool、IC card engraving cutter、Side cutter、Staple Cutter’PCD diamond cutter specialized in grooving floors’V-Cut PCD Circular Diamond Tipped Saw Blade with Indexable Insert’ PCD Diamond Tool’ Saw Blade with Indexable Insert’NAS tool、DIN or JIS tool、Special tool、Metal slitting saws、Shell end mills、Side and face milling cutters、Side chip clearance saws、Long end mills’end mill grinder’drill grinder’sharpener、Stub roughing end mills、Dovetail milling cutters、Carbide slot drills、Carbide torus cutters、Angel carbide end mills、Carbide torus cutters、Carbide ball-nosed slot drills、Mould cutter、Tool manufacturer.

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BW is specialized in R&D and sourcing the most advanced carbide material with high-tech coating to supply cutting / milling tool for mould & die, aero space and electronic industry. Our main products include solid carbide / HSS end mills, micro electronic drill, IC card cutter, engraving cutter, shell end mills, cutting saw, reamer, thread reamer, leading drill, involute gear cutter for spur wheel, rack and worm milling cutter, thread milling cutter, form cutters for spline shaft/roller chain sprocket, and special tool, with nano grade. Please visit our web www.tool-tool.com for more info.

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Mar 16 Mon 2009 11:27
Русский Цифровой фильтр www.tool-tool.com

Bewise Inc. www.tool-tool.com Reference source from the internet.

Цифровой фильтр — в электронике любой фильтр, обрабатывающий цифровой сигнал с целью выделения и/или подавления определённых частот этого сигнала. В отличие от цифрового аналоговый фильтр имеет дело с аналоговым сигналом, его свойства недискретны, соответственно передаточная функция зависит от внутренних свойств составляющих его элементов.

Содержание

[убрать]

[править] Применения

Цифровые фильтры на сегодняшний день применяются практически везде, где требуется обработка сигналов, в частности в спектральном анализе, обработке изображений, обработке видео, обработке речи и звука и многих других приложениях.

[править] Преимущества и недостатки

Преимуществами цифровых фильтров перед аналоговыми являются:

Высокая точность (точность аналоговых фильтров ограничена допусками на элементы).
В отличие от аналогового фильтра передаточная функция не зависит от дрейфа характеристик элементов.
Гибкость настройки, лёгкость изменения.
компактность — аналоговый фильтр на очень низкую частоту (доли герца, например) потребовал бы чрезвычайно громоздких конденсаторов или индуктивностей.

[править] Недостатки

Недостатками цифровых фильтров по сравнению с аналоговыми являются:

Трудность работы с высокочастотными сигналами. Полоса частот ограничена частотой Найквиста, равной половине частоты дискретизации сигнала. Поэтому для высокочастотных сигналов применяют аналоговые фильтры, либо, если на высоких частотах нет полезного сигнала, сначала подавляют высокочастотные составляющие с помощью аналогового фильтра, затем обрабатывают сигнал цифровым фильтром.
Трудность работы в реальном времени — вычисления должны быть завершены в течение периода дискретизации.
Для большой точности и высокой скорости обработки сигналов требуется не только мощный процессор, но и дополнительное, возможно дорогостоящее, аппаратное обеспечение в виде высокоточных и быстрых ЦАП и АЦП.

[править] Виды цифровых фильтров

[править] КИХ-фильтры

Основная статья: Фильтр с конечной импульсной характеристикой

Фильтр с конечной импульсной характеристикой (нерекурсивный фильтр, КИХ-фильтр) — один из видов электронных фильтров, характерной особенностью которого является ограниченность по времени его импульсной характеристики (с какого-то момента времени она становится точно равной нулю). Такой фильтр называют ещё нерекурсивным из-за отсутствия обратной связи. Знаменатель передаточной функции такого фильтра — некая константа.

[править] БИХ-фильтры

Основная статья: Фильтр с бесконечной импульсной характеристикой

Фильтр с бесконечной импульсной характеристикой (рекурсивный фильтр, БИХ-фильтр) — электронный фильтр, использующий один или более своих выходов в качестве входа, то есть образует обратную связь. Основным свойством таких фильтров является то, что их импульсная переходная характеристика имеет бесконечную длину во временной области, а передаточная функция имеет дробно-рациональный вид. Такие фильтры могут быть как аналоговыми так и цифровыми.

[править] Фильтры на основе модели пространства состояний

[править] Способы реализации цифровых фильтров

Различают два вида реализации цифрового фильтра: аппаратный и программный. Аппаратные цифровые фильтры реализуются на элементах интегральных схем, тогда как программные реализуются с помощью программ, выполняемых процессором или микроконтроллером. Преимуществом программных перед аппаратным является лёгкость воплощения, а также настройки и изменений, а также то, что в себестоимость такого фильтра входит только труд программиста. Недостаток — низкая скорость, зависящая от быстродействия процессора, а также трудная реализуемость цифровых фильтров высокого порядка.

[править] Литература

L.R. Rabiner and R.W. Schafer, Digital Processing of Speech Signals, Prentice-Hall, 1978.
S. Haykin, Adaptive Filter Theory, 3rd Edition, Prentice-Hall, 1996.
Steven W. Smith, The Scientist and Engineer’s Guide to Digital Signal Processing, Second Edition, 1999, California Technical Publishing
Хемминг Р.В. Цифровые фильтры. — М. :Советское радио. 1980.

[править] Внешние ссылки

Цифровая фильтрация
Digital filtering on dsptutor.freeuk.com(англ.)
Digital filtering basics(англ.)
Free filter design software(англ.)

[править] См. также

歡迎來到Bewise Inc.的世界，首先恭喜您來到這接受新的資訊讓產業更有競爭力，我們是提供專業刀具製造商，應對客戶高品質的刀具需求，我們可以協助客戶滿足您對產業的不同要求，我們有能力達到非常卓越的客戶需求品質，這是現有相關技術無法比擬的，我們成功的滿足了各行各業的要求，包括：精密HSS DIN切削刀具、協助客戶設計刀具流程、DIN or JIS 鎢鋼切削刀具設計、NAS986 NAS965 NAS897 NAS937orNAS907 航太切削刀具,NAS航太刀具設計、超高硬度的切削刀具、醫療配件刀具設計、複合式再研磨機、PCD地板專用企口鑽石組合刀具、NSK高數主軸與馬達、專業模具修補工具-氣動與電動、粉末造粒成型機、主機版專用頂級電桿、PCD V-Cut刀、捨棄式圓鋸片組、粉末成型機、主機版專用頂級電感、’汽車業刀具設計、電子產業鑽石刀具、木工產業鑽石刀具、銑刀與切斷複合再研磨機、銑刀與鑽頭複合再研磨機、銑刀與螺絲攻複合再研磨機等等。我們的產品涵蓋了從民生刀具到工業級的刀具設計；從微細刀具到大型刀具；從小型生產到大型量產；全自動整合；我們的技術可提供您連續生產的效能，我們整體的服務及卓越的技術，恭迎您親自體驗！！

BW Bewise Inc. Willy Chen willy@tool-tool.com bw@tool-tool.com www.tool-tool.com skype:willy_chen_bw mobile:0937-618-190 Head &Administration Office No.13,Shiang Shang 2nd St., West Chiu Taichung,Taiwan 40356 http://www.tool-tool.com / FAX:+886 4 2471 4839 N.Branch 5F,No.460,Fu Shin North Rd.,Taipei,Taiwan S.Branch No.24,Sec.1,Chia Pu East Rd.,Taipao City,Chiayi Hsien,Taiwan

Welcome to BW tool world! We are an experienced tool maker specialized in cutting tools. We focus on what you need and endeavor to research the best cutter to satisfy users’ demand. Our customers involve wide range of industries, like mold & die, aerospace, electronic, machinery, etc. We are professional expert in cutting field. We would like to solve every problem from you. Please feel free to contact us, its our pleasure to serve for you. BW product including: cutting tool、aerospace tool .HSS DIN Cutting tool、Carbide end mills、Carbide cutting tool、NAS Cutting tool、NAS986 NAS965 NAS897 NAS937orNAS907 Cutting Tools,Carbide end mill、disc milling cutter,Aerospace cutting tool、hss drill’Фрезеры’Carbide drill、High speed steel、Compound Sharpener’Milling cutter、INDUCTORS FOR PCD’CVDD(Chemical Vapor Deposition Diamond )’PCBN (Polycrystalline Cubic Boron Nitride) ’Core drill、Tapered end mills、CVD Diamond Tools Inserts’PCD Edge-Beveling Cutter(Golden Finger’PCD V-Cutter’PCD Wood tools’PCD Cutting tools’PCD Circular Saw Blade’PVDD End Mills’diamond tool. INDUCTORS FOR PCD . POWDER FORMING MACHINE ‘Single Crystal Diamond ‘Metric end mills、Miniature end mills、Специальные режущие инструменты ‘Пустотелое сверло ‘Pilot reamer、Fraises’Fresas con mango’ PCD (Polycrystalline diamond) ‘Frese’POWDER FORMING MACHINE’Electronics cutter、Step drill、Metal cutting saw、Double margin drill、Gun barrel、Angle milling cutter、Carbide burrs、Carbide tipped cutter、Chamfering tool、IC card engraving cutter、Side cutter、Staple Cutter’PCD diamond cutter specialized in grooving floors’V-Cut PCD Circular Diamond Tipped Saw Blade with Indexable Insert’ PCD Diamond Tool’ Saw Blade with Indexable Insert’NAS tool、DIN or JIS tool、Special tool、Metal slitting saws、Shell end mills、Side and face milling cutters、Side chip clearance saws、Long end mills’end mill grinder’drill grinder’sharpener、Stub roughing end mills、Dovetail milling cutters、Carbide slot drills、Carbide torus cutters、Angel carbide end mills、Carbide torus cutters、Carbide ball-nosed slot drills、Mould cutter、Tool manufacturer.

ようこそＢｅｗｉｓｅ　Ｉｎｃ.の世界へお越し下さいませ、先ず御目出度たいのは新たな

情報を受け取って頂き、もっと各産業に競争力プラス展開。

弊社は専門なエンド・ミルの製造メーカーで、客先に色んな分野のニーズ、

豊富なパリエーションを満足させ、特にハイテク品質要求にサポート致します。

弊社は各領域に供給できる内容は：

弊社の製品の供給調達機能は：

弊社の全般供給体制及び技術自慢の総合専門製造メーカーに貴方のご体験を御待ちしております。

Bewise Inc. talaşlı imalat sanayinde en fazla kullanılan ve üç eksende (x,y,z) talaş kaldırabilen freze takımlarından olan Parmak Freze imalatçısıdır. Çok geniş ürün yelpazesine sahip olan firmanın başlıca ürünlerini Karbür Parmak Frezeler, Kalıpçı Frezeleri, Kaba Talaş Frezeleri, Konik Alın Frezeler, Köşe Radyüs Frezeler, İki Ağızlı Kısa ve Uzun Küresel Frezeler, İç Bükey Frezeler vb. şeklinde sıralayabiliriz.

BW специализируется в научных исследованиях и разработках, и снабжаем самым высокотехнологичным карбидовым материалом для поставки режущих / фрезеровочных инструментов для почвы, воздушного пространства и электронной индустрии. В нашу основную продукцию входит твердый карбид / быстрорежущая сталь, а также двигатели, микроэлектрические дрели, IC картонорезальные машины, фрезы для гравирования, режущие пилы, фрезеры-расширители, фрезеры-расширители с резцом, дрели, резаки форм для шлицевого вала / звездочки роликовой цепи, и специальные нано инструменты. Пожалуйста, посетите сайт www.tool-tool.com для получения большей информации.

BW is specialized in R&D and sourcing the most advanced carbide material with high-tech coating to supply cutting / milling tool for mould & die, aero space and electronic industry. Our main products include solid carbide / HSS end mills, micro electronic drill, IC card cutter, engraving cutter, shell end mills, cutting saw, reamer, thread reamer, leading drill, involute gear cutter for spur wheel, rack and worm milling cutter, thread milling cutter, form cutters for spline shaft/roller chain sprocket, and special tool, with nano grade. Please visit our web www.tool-tool.com for more info.

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Mar 16 Mon 2009 11:21
Português Filtro digital www.tool-tool.com

Bewise Inc. www.tool-tool.com Reference source from the internet.

Um filtro digital é um filtro que processa sinais digitais.

Utilizando um conversor analógico-digital (ADC), digitaliza-se o sinal a filtrar, em seguida este é processado por algum tipo de processador, onde está programado o filtro digital. Para se obter de novo um sinal analógico já filtrado, coloca-se um conversor digital-analógico (DAC).

[editar] Vantagens

Os filtros digitais têm muitas vantagens comparativamente aos analógicos. Por exemplo:

A durabilidade dos componentes electrónicos que constituem um filtro analógico é muito menor que a durabilidade do equipamento de aquisição e processamento de sinal que constitui o filtro digital;
Consegue-se facilmente implementar filtros de ordem elevada;
O SNR (signal-to-noise ratio relação entre a potência do sinal e a potência do ruído) dos filtros digitais é muito maior

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BW Bewise Inc. Willy Chen willy@tool-tool.com bw@tool-tool.com www.tool-tool.com skype:willy_chen_bw mobile:0937-618-190 Head &Administration Office No.13,Shiang Shang 2nd St., West Chiu Taichung,Taiwan 40356 http://www.tool-tool.com / FAX:+886 4 2471 4839 N.Branch 5F,No.460,Fu Shin North Rd.,Taipei,Taiwan S.Branch No.24,Sec.1,Chia Pu East Rd.,Taipao City,Chiayi Hsien,Taiwan

Welcome to BW tool world! We are an experienced tool maker specialized in cutting tools. We focus on what you need and endeavor to research the best cutter to satisfy users’ demand. Our customers involve wide range of industries, like mold & die, aerospace, electronic, machinery, etc. We are professional expert in cutting field. We would like to solve every problem from you. Please feel free to contact us, its our pleasure to serve for you. BW product including: cutting tool、aerospace tool .HSS DIN Cutting tool、Carbide end mills、Carbide cutting tool、NAS Cutting tool、NAS986 NAS965 NAS897 NAS937orNAS907 Cutting Tools,Carbide end mill、disc milling cutter,Aerospace cutting tool、hss drill’Фрезеры’Carbide drill、High speed steel、Compound Sharpener’Milling cutter、INDUCTORS FOR PCD’CVDD(Chemical Vapor Deposition Diamond )’PCBN (Polycrystalline Cubic Boron Nitride) ’Core drill、Tapered end mills、CVD Diamond Tools Inserts’PCD Edge-Beveling Cutter(Golden Finger’PCD V-Cutter’PCD Wood tools’PCD Cutting tools’PCD Circular Saw Blade’PVDD End Mills’diamond tool. INDUCTORS FOR PCD . POWDER FORMING MACHINE ‘Single Crystal Diamond ‘Metric end mills、Miniature end mills、Специальные режущие инструменты ‘Пустотелое сверло ‘Pilot reamer、Fraises’Fresas con mango’ PCD (Polycrystalline diamond) ‘Frese’POWDER FORMING MACHINE’Electronics cutter、Step drill、Metal cutting saw、Double margin drill、Gun barrel、Angle milling cutter、Carbide burrs、Carbide tipped cutter、Chamfering tool、IC card engraving cutter、Side cutter、Staple Cutter’PCD diamond cutter specialized in grooving floors’V-Cut PCD Circular Diamond Tipped Saw Blade with Indexable Insert’ PCD Diamond Tool’ Saw Blade with Indexable Insert’NAS tool、DIN or JIS tool、Special tool、Metal slitting saws、Shell end mills、Side and face milling cutters、Side chip clearance saws、Long end mills’end mill grinder’drill grinder’sharpener、Stub roughing end mills、Dovetail milling cutters、Carbide slot drills、Carbide torus cutters、Angel carbide end mills、Carbide torus cutters、Carbide ball-nosed slot drills、Mould cutter、Tool manufacturer.

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BW специализируется в научных исследованиях и разработках, и снабжаем самым высокотехнологичным карбидовым материалом для поставки режущих / фрезеровочных инструментов для почвы, воздушного пространства и электронной индустрии. В нашу основную продукцию входит твердый карбид / быстрорежущая сталь, а также двигатели, микроэлектрические дрели, IC картонорезальные машины, фрезы для гравирования, режущие пилы, фрезеры-расширители, фрезеры-расширители с резцом, дрели, резаки форм для шлицевого вала / звездочки роликовой цепи, и специальные нано инструменты. Пожалуйста, посетите сайт www.tool-tool.com для получения большей информации.

BW is specialized in R&D and sourcing the most advanced carbide material with high-tech coating to supply cutting / milling tool for mould & die, aero space and electronic industry. Our main products include solid carbide / HSS end mills, micro electronic drill, IC card cutter, engraving cutter, shell end mills, cutting saw, reamer, thread reamer, leading drill, involute gear cutter for spur wheel, rack and worm milling cutter, thread milling cutter, form cutters for spline shaft/roller chain sprocket, and special tool, with nano grade. Please visit our web www.tool-tool.com for more info.

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