二極體電橋：修订间差异
翻譯外文連結 |
（没有差异）
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2019年9月18日 (三) 11:03的版本
 | 此條目目前正依照其他维基百科上的内容进行翻译。 (2019年9月18日) |
 不同封裝的二極體電橋 | |
| Type | 半导体 |
|---|---|
| Invented | Karol Franciszek Pollak（1859年11月15日-1928年12月17日） |
| Electronic symbol | |
 二個輸入端子，交流電輸入，二個輸出端子，幾乎連續的電流輸出 | |
二極體電橋（diode bridge）是用四個（或四個以上）的二極管組成的电桥电路組態，不論輸入電壓的電極性是正是負，輸出都可以維持相同的極性。
二極體電橋最常見的用途是將交流電（AC）轉換為直流電（DC），也稱為橋式整流器。橋式整流器配合二線交流輸入電壓，可以進行全波整流，其他的整流方式可以利用其二次繞組有中心抽頭的变压器，再將輸出接到三端子輸入的整流器，但橋式整流器在成本及重量上都有優勢[1]。
二極體電橋的基本特點就是輸出電壓的極性不會隨輸入電壓而變化。二極體電橋是由波兰電機工程師Karol Pollak發明，在1895年12月在英國申請專利[2]，1896年1月在德國申請專利[3][4]。德國物理學家Leo Graetz在1897年獨立的發明類似的電路，也有發表[5][6]。有些文獻仍把此電路稱為Graetz電路或是Graetz電橋[7]。
在集成电路普及之前，會用四顆二極體組裝二極體電橋。自1950年開始，由四個二極體組成電橋的四端子單一封裝元件開始變成標準商品化的產品，目前已有不同的電壓及電流額定。
除了二極體電橋外，在倍壓器中，二極體也會和電容器配置成電橋組態。
Current flow
According to the conventional model of 电流 flow (originally established by 本傑明·富蘭克林 and still followed by most engineers today[8]), current flows through 導體s from the positive to the negative pole (defined as "positive flow"). In actuality, 自由電子 in a conductor nearly always flow from the negative to the positive pole. In the vast majority of applications, however, the actual direction of current flow is irrelevant. Therefore, in the discussion below the conventional model is retained.
The fundamental characteristic of a diode is that current can flow only one way through it, which is defined as the forward direction. A diode bridge uses diodes as series components to allow current to pass in the forward direction during the positive part of the AC cycle and as shunt components to redirect current flowing in the reverse direction during the negative part of the AC cycle to the opposite rails.
Rectifier
In the diagrams below, when the input connected to the left corner of the diamond is positive, and the input connected to the right corner is negative, current flows from the upper supply terminal to the right along the red (positive) path to the output and returns to the lower supply terminal through the blue (negative) path.
When the input connected to the left corner is negative, and the input connected to the right corner is positive, current flows from the lower supply terminal to the right along the red (positive) path to the output and returns to the upper supply terminal through the blue (negative) path.[9]
In each case, the upper right output remains positive[10], and lower right output negative. Since this is true whether the input is AC or DC, this circuit not only produces a DC output from an AC input, it can also provide what is sometimes called "reverse-polarity protection". That is, it permits normal functioning of DC-powered equipment when 电池 have been installed backwards, or when the leads (wires) from a DC power source have been reversed, and protects the equipment from potential damage caused by reverse polarity.
Alternatives to the diode-bridge full-wave rectifiers are the center-tapped transformer and double-diode rectifier, and 倍壓器 rectifier using two diodes and two capacitors in a bridge topology.
Smoothing
 | 此章節尚無參考來源，內容或許無法查證。 (2017年10月1日) |
With AC input, the output of a diode bridge (called a full-wave rectifier for this purpose; there is also 整流器, which does not use a diode bridge) is polarized pulsating 正弦曲線 voltage of the same amplitude but twice the frequency of the input. It may be considered as DC voltage upon which is superimposed a very large 漣波. This kind of electric power is not very usable, because ripple is dissipated as 废热 in DC circuit components and may cause noise or distortion during circuit operation. So nearly all rectifiers are followed by a series of 带通滤波器 or 带阻滤波器s and/or a 稳压器 to convert most or all of the ripple voltage into a smoother and possibly higher DC output. A filter may be as simple as a single sufficiently large 电容器 or 扼流圈, but most power-supply filters have multiple alternating series and shunt components. When the ripple voltage rises, 交流电功率 is stored in the filter components, reducing the voltage; when the ripple voltage falls, reactive power is discharged from the filter components, raising the voltage. The final stage of rectification may consist of a 齊納二極體-based voltage regulator, which almost completely eliminates any residual ripple.
Polyphase diode bridges
The diode bridge can be generalized to rectify 多相系統 AC inputs. For example, for a three-phase AC input, a half-wave rectifier consists of three diodes, but a full-wave bridge rectifier consists of six diodes.
Half-wave rectifier may be considered as wye connection (star connection), because it returns the current through the centre (neutral) wire. Full-wave is more like delta connection, although it can be connected to the three-phase source of either wye or delta and it does not use the centre (neutral) wire.
Diode switching artifacts and snubber circuits
Power-supply transformers have leakage inductance and parasitic capacitance. When the diodes in a bridge rectifier switch off, these "non-ideal" elements form a resonant circuit, which can oscillate at high frequency. This high-frequency oscillation can then couple into the rest of the circuitry. Snubber circuits are used in an attempt to mitigate this problem. A snubber circuit consists of either a very small capacitor or series capacitor and resistor across a diode.
相關條目
參考資料
- ^ Horowitz, Paul; Hill, Winfield. The Art of Electronics Second. Cambridge University Press. 1989: 44–47. ISBN 0-521-37095-7.
- ^ British patent 24398.
- ^ (Graetz, 1897), p. 327 footnote.
- ^ (Editorial staff). Ein neues Gleichrichter-Verfahren [A new method of rectification]. Elektrotechnische Zeitschrift. 24 June 1897, 18 (25): 359 and footnote （German）.
- ^ See:
- Graetz, L. Electrochemisches Verfahren, um Wechselströme in Gleichströme zu verwandeln [Electrochemical method of changing alternating into direct currents]. Sitzungsberichte der Mathematisch-Physikalischen Classe der Königlich Bayerischen Akademie der Wissenschaften zu München (Transactions of the Mathematical-Physical Classes of the Royal Bavarian Academy of Sciences in Munich). 1 May 1897, 27: 223–228 （German）.
- Graetz, L. Electrochemisches Verfahren, um Wechselströme in Gleichströme zu verwandeln [Electrochemical method of changing alternating into direct currents]. Annalen der Physik und Chemie. 3rd series. 1897, 62: 323–327 （German）.
- Graetz, Leo. Electrochemisches Verfahren, um Wechselströme in Gleichströme zu verwandeln [Electrochemical method of changing alternating into direct currents]. Elektrotechnische Zeitschrift. 22 July 1897, 18 (29): 423–424 （German）.
- ^ Strzelecki, R. Power Electronics in Smart Electrical Energy Networks. Springer, 2008, p. 57.
- ^ Graetz Flow Control Circuit. （原始内容存档于2013-11-04）.
- ^ Stutz, Michael (stutz@dsl.org), "Conventional versus electron flow", All About Circuits, Vol. 1, Chapter 1, 2000.
- ^ Sears, Francis W., Mark W. Zemansky and Hugh D. Young, University Physics, Sixth Ed., Addison-Wesely Publishing Co., Inc., 1982, p. 685.
- ^ bridge rectifier circuit electronics basic. The Geek Pub. [3 September 2019].
- ^ "Rectifier", Concise Encyclopedia of Science and Technology, Third Edition, Sybil P. Parker, ed. McGraw-Hill, Inc., 1994, p. 1589.
外部連結
- Electronics: Bridge Rectifiers (1969) US Air Force Training Film. Old Movies Reborn (Youtube). July 16, 2017.
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