電氣工程專業(yè)英語(yǔ)unt2

1、電氣工程及其自動(dòng)化專業(yè)英語(yǔ),主編 楊勇 鄧秋玲,Unit 2 Power Electronics,2.1 Introduction,2.2 Power Semiconductor Devices,2.3 Power Electronic Converters,2.4 Further Reading:Electronic Filters,2.1 Introduction,New Words and Expressions,solid-state adj. 固態(tài)的 computation n. 計(jì)算；估計(jì) integration n.結(jié)合；整合；dynamic adj.動(dòng)態(tài)的；n.動(dòng)力學(xué)；merc

2、ury-arc醫(yī)汞弧 valve n. 閥；真空管；semiconductorn.物半導(dǎo)體 switchingn. 開關(guān)；轉(zhuǎn)換； diode n. 二極管 inverter n. 反用換流器（逆變器）；thyristorn. 半導(dǎo)體閘流管；硅可控整流器 inverter thyristor 晶閘管逆變器；可控硅逆變器 transistorn. 晶體管；晶體管收音機(jī)；半導(dǎo)體收音機(jī) transmissionn. 播送；傳送；信息；傳動(dòng)裝置 substantial adj. 結(jié)實(shí)的；重大的 n. 本質(zhì)；,2.1 Introduction,New Words and Expressions,fluor

3、escentfl:resnt lamp ballast 熒光燈鎮(zhèn)流器 mercury n. 水銀；汞 thermionic adj. 物熱電子的；HVDC transmission system 高壓直流輸電系統(tǒng) induction motor 感應(yīng)電動(dòng)機(jī) vacuum n. 真空； adj. 真空的；vt. 用真空吸塵器打掃 dissipate v. 驅(qū)散；rectifier n. 糾正者；整流器 triggered adj. 觸發(fā)的 thyratronartrn n. 電閘流管 ignitron n. 引燃管；放電管 cycloconverter n. 周波變換器；雙向離子變頻器 tria

4、c n. 電三端雙向可控硅開關(guān)元件 a scope of一個(gè)范圍 spectrumn. 譜，光譜；能譜；,2.1 Introduction text,Power electronics is the application of solid-state elec-tronics for the control and conversion of electric power. It also refers to a subject of research in electrical engineering which deals with design, control, comput-ati

5、on and integration of nonlinear, time varying energy processing electronic systems with fast dynamics.,Note：refers to指的是; 此句譯成：電力電子技術(shù)是電氣工程研究課題之一，主要對(duì)具有快速動(dòng)態(tài)響應(yīng)的非線性、時(shí)變能源處理的電子系統(tǒng)進(jìn)行設(shè)計(jì)、控制、計(jì)算和集成。,2.1 Introduction text,Power electronic converters can be found wherever there is a need to change voltage, curren

6、t or frequency of electric power, as shown in Fig.2.1, Fig.2.2 and Fig.2.3. The power range of these converters is from some mill-iwatts (as in a mobile phone) to hundreds of megawatts in a high voltage direct current (HVDC) transmission sys-tem.,Note：found wherever there is a need用在那些需要.的場(chǎng)合，對(duì)電壓、電流或

7、電能的頻率進(jìn)行轉(zhuǎn)換時(shí)，就要用到電力電子轉(zhuǎn)換器。,Note：power range is from.to 這些轉(zhuǎn)換器的功率范圍從毫瓦特（如移動(dòng)電話的功率）到高壓直流輸電系統(tǒng)的數(shù)百兆瓦。,2.1 Introduction text,With “classical” electronics, electrical currents and voltage are used to carry information, whereas with power electronics, they carry power. Thus, the main metric 主要指標(biāo)of power electron

8、ics becomes the efficiency.,Note：評(píng)價(jià)電力電子的主要性能指標(biāo)是效率。,2.1 Introduction text,Applications of power electronics range in size from a switched mode power supply in an alternating current (AC) adapter, battery chargers, fluorescent lamp ballasts, through variable frequency drives and direct current (DC) mo

9、tor drives used to operate pumps, fans, and manufactur-ing machinery, up to gigawatt-scale high voltage direct current power transmission systems used to interconnect electrical grids.,Note：range in size:按大小排列.此句譯為：按大小排列，從AC適配器中的開關(guān)電源、電池充電器、熒光燈鎮(zhèn)流器、到變頻驅(qū)動(dòng)和水泵、風(fēng)機(jī)、機(jī)床的DC電機(jī)驅(qū)動(dòng)，再到用于電網(wǎng)互連、具有千兆瓦規(guī)模的高壓直流電力傳輸系統(tǒng)，都能發(fā)

10、現(xiàn)電力電子技術(shù)的應(yīng)用。,2.1 Introduction text,Then in 1948 the invention of the bipolar junction transistor by Shockley all at once （突然；同時(shí)）reduced the cost and size while increasing the efficiency of transistors beginning a revolution in semiconductor electronics. Shortly after, in the 1950s, semiconductor powe

11、r diodes became available and started replacing vacuum tubes. Then in 1956 the silicon controlled rectifier (SCR) was introduced by General Electric marking the point where semiconductor power electronics really began.,Note：標(biāo)志著半導(dǎo)體電力電子技術(shù)的真正開始：,2.1 Introduction text,Power electronics started with the

12、development of mercury arc rectifier. Invented by Peter Cooper Hewitt in 1902, the mercury arc rectifier was used to convert AC into DC. In 1933 selenium （硒）rectifiers were invented. In 1947 the bipolar point-contact transistor（ 雙極點(diǎn)接觸型晶體管）was invented by Walter H Brattain and John Bardeen under the

13、direction of （在的領(lǐng)導(dǎo)之下） William Shockley at the Bell Telephone Laboratory.,Note： started with 開始于； mercury arc rectifier 汞弧整流器.,2.1 Introduction text,In 1960s the switching speed of bipolar junction tran-sistors (BJTs) allowed for （允許）DC/DC converters to be possible in high frequency, with the metal o

14、xide semi-conductor field effect transistor (MOSFET) introduced in 1960. In 1976 power MOSFET becomes commercially availa-ble. Then in 1982 the insulated gate bipolar transistor (IGBT) was introduced.,Note：commercially available市場(chǎng)上能買到的,2.1 Introduction text,The capabilities and economy of power elec

15、tronics system are determined by the active devices that are available. Their characteristics and limitations are a key element in the design of power electronics systems. Formerly, the mercury arc valve, the high-vacuum and gas-filled diode thermionic rectifiers , and triggered devices such as the

16、thyratron and ignitron were widely used in power electronics.,Note： are determined by 取決于；,Note： gas-filled 充氣的； thermionic rectifiers熱離子整流器,2.1 Introduction text,As the ratings of solid-state devices improved in both voltage and current-handling capacity, vacuum devices have been nearly entirely re

17、placed by solid-state devices. The first high power electronic devices were mercury-arc valves. In modern systems the conversion is per-formed with semiconductor switching devices such as diodes, thyristors and transistors, as pioneered by R. D. Middlebrook and others beginning in the 1950s,Note：is

18、per-formed with用.執(zhí)行，實(shí)現(xiàn)； as pioneered by由.開創(chuàng)的。,2.1 Introduction text,. In contrast to electronic systems concerned with transmission and processing of signals and data, in power electronics substantial amounts of electrical energy are processed. An AC/DC converter (rectifier) is the most typical pow-

19、er electronics device found in many consumer electronic devices, e.g. television sets, personal computers, battery chargers, etc.,Note：In contrast to 與.相比；concerned with涉及 此句譯為：電力電子處理大量的電能。,Note：consumer electronic devices 消費(fèi)電子用品。,2.1 Introduction text,The power range is typically from tens of watts

20、 to several hundred watts. In industry a common applica-tion is the variable speed drive (VSD) that is used to control an induction motor. The power range of VSDs starts from a few hundred watts and end at tens of megawatts. Power electronic devices may be used as switches, or as amplifiers.,2.1 Int

21、roduction text,An ideal switch is either open or closed and so dissipates no power; it withstands an applied voltage and passes no current, or passes any amount of current with no voltage drop. Semiconductor devices used as switches can appro-ximate this ideal property and so most power electronic a

22、pplications rely on switching devices on and off, which makes systems very efficient as no power is wasted in the switching devices.,Note： either open or closed 或打開或關(guān)閉；passes any amount of current with no voltage drop 流過(guò)電流而不引起壓降。,2.1 Introduction text,By contrast, in the case of the amplifier, the c

23、urrent through the device varies continuously according to a controlled input. Power electronics makes up a large part of engin-eering and has close connections with many areas of physics, chemistry, and mechanics. It establishes a rapidly expanding field in electrical engineering and a scope of its

24、 technology covers a wide spectrum.,Note： in the case of 就.來(lái)說(shuō)；,Note：makes up a large part 占.大部分； close connections with與. 有緊密聯(lián)系。,2.2 Power Semiconductor Devices New Words and Expressions,wafern. 圓片；晶片 SCRn. 可控硅整流器 GTOn. 門極可關(guān)斷晶閘管 MCTn. MOS控制晶閘管 IGBTn. 絕緣柵雙極型晶體管 BJTn. 雙極結(jié)型晶體管 FETn. 場(chǎng)效應(yīng)管 semiconductorn

25、. 半導(dǎo)體 freewheelingn. 慣性滑行 adj. 慣性滑行的；隨心所欲的 v. 輕快地行動(dòng) forward-bias正向偏置,2.2 Power Semiconductor Devices New Words and Expressions,kiloamperesn. 千安培 leakagen. 漏，泄漏；漏損量；滲漏物 switch n. 開關(guān)；轉(zhuǎn)換，轉(zhuǎn)換器；vt. ,At turn on, the diode can be considered as an ideal switch because it opens rapidly compared to transients

26、in the circuit. In most of circuits, the leakage current does not have a significant effect on the circuit and thus the diode can be considered as a switch. In the case of reverse-biased voltage, only a small lea-kage current flows through the diode.,2.2 Power Semiconductor Devices TEXT,Note： be con

27、sidered as 可看作； leakage current 漏電流；,Note： In the case of ， 就反向偏置電壓而言。,This current is independent of reverse voltage until the breakdown voltage is reached. After that, the diode voltage remains essentially constant while the current increases dramatically. Only the resistance of the exter-nal circ

28、uit limits the maximum value of the current. Simultaneous large current and large voltage in the breakdown operation of the diode must be avoided.,2.2 Power Semiconductor Devices TEXT,Note： is independent of 與.無(wú)關(guān)； breakdown voltage擊穿電壓； remains essentially constant 基本上不變。,2.2.2 Thyristors and GTOs A

29、s shown in Fig.2.5(b), rectifier thyristors known as silicon-controlled rectifiers (SCRs) are commonly used in adjustable rectifier circuits, especially in high power units up to 100 MVA. Their frequency capabilities are not high, being lower than 10 kHz.,2.2 Power Semiconductor Devices TEXT,Note： k

30、nown as 被稱為是,所謂； up to 高達(dá) ，作后置定語(yǔ)，修飾high power units.,If positive voltage is applied without gate current, the thyristor constitutes the state of forward blocking. A low-power pulse of gate current switches the thyristor to the on-state. The output characteristic of a conducting thyristor in the forw

31、ard bias is very similar to the same curve of the diode with a small leakage current. Thus, the thyristor assumes very low resistance in the forward direction.,2.2 Power Semiconductor Devices TEXT,Note：switches .to .切換到，轉(zhuǎn)到，轉(zhuǎn)變成； is very similar to 與.很相似， 很接近.,Once turned on, the thyristor remains in

32、this state after the end of the gate pulse while its current is higher than the holding level. If the current drops below the holding value, the device switches back to the non-conducting region. Switching off by gate pulse is impossible. Therefore, using the same arguments as for( 至于,關(guān)于)diodes, the

33、 thyristor can be represented by the idealized switch.,2.2 Power Semiconductor Devices TEXT,Note：Once turned on 一旦導(dǎo)通； holding level 保持級(jí)； switches back to轉(zhuǎn)回到。,When a thyristor is supplied by AC, the moment of a thyristor opening should be adjusted by shifting the control pulse relative to the startin

34、g point of the posi-tive alternation of anode voltage. This delay is called the firing angle . The output characteristic of SCR in the reverse bias is very similar to the same curve of the diode with a small leakage current.,2.2 Power Semiconductor Devices TEXT,Note：在交流情況下使用晶閘管時(shí)，它的導(dǎo)通時(shí)刻可以通過(guò)相對(duì)于陽(yáng)極電壓變?yōu)檎?/p>

35、的起始點(diǎn)移動(dòng)控制脈沖來(lái)調(diào)節(jié).,With negative voltage between anode and cathode, this corresponds to the reverse blocking state. If the maximum reverse voltage exceeds the permissible value, the leakage current rises rapidly, as with diodes, leading to breakdown and thermal destruction of the thyristor. Besides the

36、rectifier thyristors, the gate turn-off thyrist-ors (GTOs) are produced as shown in Fig.2.5(c).,2.2 Power Semiconductor Devices TEXT,Note：as with 如同，和-一樣； thermal destruction 熱破壞。,These devices have two adjustable operations: they can be turned on or off by the current gate pulses. The GTO thyristor

37、 turns on similarly to the SCR thyri-stors, i.e. after the current pulse will be applied to the gate electrode. To turn it off, a powerful negative curr-ent control pulse must be applied to the gate electrode. A switching frequency range of a GTO thyristor is a few hundred hertz to tens kilohertz.,N

38、ote：similarly to the SCR thyristors 和SCR相似。,2.2 Power Semiconductor Devices TEXT,Their on-state voltage (23V) is higher than that of SCR. Because of their capability of handling large voltages (up to 5kV) and large currents (up to a few kiloamperes at 10MVA), the GTO thyristors are more convenient t

39、o use than the SCR thyristors in applications where high price and high power are allowed.,Note：由于GTO具有處理高電壓（高達(dá)5千伏）、大電流（達(dá)幾千安培，容量可達(dá)10MVA）的能力，GTO在那些高成本的大功率場(chǎng)合使用，比SCR更為便利。,2.2 Power Semiconductor Devices TEXT,2.2.3 Power MOSFETs and IGBTs As shown in Fig.2.5(d), (e), metal-oxide-semiconductor field-effe

40、ct transistor (MOSFET) is a voltage-controll-ed metal-oxide semiconductor field-effect transistor. The advantages of the MOSFETs are as follows: high switching capability that is the operational frequencies reach gigahertz; simple protection circuits and voltage control; normally off device when the

41、 enhancement mode is used; and easy paralleling to increase the current values.,2.2 Power Semiconductor Devices TEXT,The drawbacks of the MOSFETs are as follows: relatively low power handling capabilities, less than 10kVA, 1000V, and 200A; and relatively high (more than 2V) forward voltage drop. In

42、contrast to MOSFETs, bipolar junction transistors (BJTs) have some advantages. Both BJTs and MOS-FETs have the technical parame-ters and characteristics that complement each other.,2.2 Power Semiconductor Devices TEXT,Note：are as follows如下,Note：BJT和MOSFET的技術(shù)參數(shù)及特性成為互補(bǔ)。,2.2 Power Semiconductor Devices

43、 TEXT,BJTs have lower conduction losses in the on-state, espe-cially at larger blocking voltages, but they have longer switching times. MOSFETs are much faster, but their on-state conduction losses are higher. Therefore, attempts were made to combine these two types of transistors on the same silico

44、n wafer to achieve better technical features.,為了得到更好的技術(shù)性能，人們嘗試將兩者組合在同一硅片上。,These investigations resulted in the development of the insulated gate bipolar transistor (IGBT) as shown in Fig.2.5(f), which is becoming the device of choice in most of new power applications. IGBTs have the highest power c

45、apabilities up to 1700-kVA, 2000V, 800A. Because of the less resistance than the MOSFET, the heating losses of the IGBT are lower too.,Note：device of choice 選擇的裝置。,2.2 Power Semiconductor Devices TEXT,Their forward voltage drop is 23V, that is higher than that of a bipolar transistor but lower than

46、the MOSFET has. Due to the negative temperature coefficient, when a temperature is raised, the power and heating decrease therefore the device withstands the overloading and operates in parallel well.,Note：temperature coefficient溫度系數(shù)；此句譯為：由于IGBT屬于負(fù)溫度系數(shù)半導(dǎo)體材料，當(dāng)溫度上升時(shí)，功耗和熱量會(huì)隨之降低，所以能過(guò)載運(yùn)行，且適合并聯(lián)。,2.2 Power

47、 Semiconductor Devices TEXT,The reliability of the IGBTs is higher than that of the field-effect transistors (FETs) thanks to the absence of a secondary breakdown. They have relatively simple voltage controlled gate driver and low gate current. Unfortunately, IGBTs are not suitable for high frequenc

48、y supply sources.,Note： thanks to由于,2.2 Power Semiconductor Devices TEXT,Note：supply source：電源。遺憾的是IGBT不適合于高頻電源.,2.3 Power Electronic Converters New Words and Expressions,interactionn. 互相影響；utilityn. 功用，效用；公用事業(yè) topologyn. 拓?fù)浣Y(jié)構(gòu) commutation n. 交換；折算； rectifier n. 整流器 invertern. 逆變器 magnitude n. 巨大，重要；

49、chopper n. 斬波器 domesticadj. 家庭的 virtually adv. 實(shí)際上；controllability n. 可操縱性；adequate adj. 足夠的；適當(dāng)?shù)模?electromechanicaladj. 電動(dòng)機(jī)械的；機(jī)電的；電機(jī)的 vehicle n. 車輛；交通工具；傳播媒介，媒介物 householdn. 家庭； adj. 家庭的，；日常的 insufficientadj. 不足的；不夠的,2.3 Power Electronic Converters New Words and Expressions,cope with對(duì)付；stringent adj

50、. 嚴(yán)格的；迫切的 alternatelyadv. 輪流地，交替地；交互 sinkvi. 淹沒(méi)；下落； vt. 使下沉；使下垂 regeneration n. 正反饋 autonomousadj. 自治的；有自主權(quán)的 quadrantn. 四分之一圓；扇形體；象限儀 shuntv. 使轉(zhuǎn)軌；使分流；轉(zhuǎn)向一邊；避開 n. 轉(zhuǎn)軌；分流器 unifyvt. 使聯(lián)合；使相同；使一致；統(tǒng)一 replenish vt. 補(bǔ)充；重新裝滿；把裝滿 specify vt. 指定；詳述 vi. 明確提出，詳細(xì)說(shuō)明 polarity n. 極性,2.3 Power Electronic Converters Tex

51、t,Interaction between the utility supply and the load depends on the topology of the power system, which converts the line feed into the load power. The availability of excellent fast commutation devices and advancements in digital technology have driven a rapid power converter development. The four

52、 main classes of power electronic converters are depicted in Fig.2.6. They are: - AC/DC converters called rectifiers that convert input AC voltage Us to DC with adjustment of output voltage Ud and current Id, as shown in Fig.2.6(a);,Note： line feed 線路饋電;, commutation devices整流裝置,2.3 Power Electronic

53、 Converters Text,- DC/AC converters called inverters that produce out-put AC voltage Us of controllable magnitude and frequ-ency from input DC voltage Ud, as shown in Fig.2.6(b); - AC/AC converters called frequency converters and changers that establish AC frequency, phase, magnitude, and shape, as

54、shown in Fig.2.6(c); - DC/DC converters called choppers that change DC voltage and current levels using the switching mode of semiconductor devices, as shown in Fig.2.6(d).,2.3 Power Electronic Converters Text,2.3.1 Rectifiers and Inverters AC/DC converters serve as rectifiers. They convert AC to DC

55、 in a number of industrial, domestic, agricultural, and other applications. Rectifiers are used as stand-alone units feeding single and multiple DC loads and as input stages of AC systems because of their virtually unlimited output power and fine controllability.,Note：serve as 充當(dāng)， 擔(dān)任；,Note： stand-al

56、one units 獨(dú)立單元。,2.3 Power Electronic Converters Text,Their speed of response is usually adequate to handle electromechanical transients occurring in motor drives and power suppliers. AC/DC line-commutated converters or, as they also called, converters with natural commutation or passive rectifiers,

57、are the most usual choice for applications, where a single-phase and three-phase supply is availa-ble.,Note：AC/DC電網(wǎng)換流換流器，亦稱為自然換流換流器或無(wú)源換流器。在單相或三相電源的場(chǎng)合，通常選擇電網(wǎng)換流換流器。line-commutated converters:電網(wǎng)換流換流器：借助于電網(wǎng)電壓來(lái)實(shí)現(xiàn)換流，不需要器件具有門極可關(guān)斷能力。,2.3 Power Electronic Converters Text,This is due to simplicity of the circ

58、uits requiring a mi-nimum number of active and passive components. Thyristors are the main line-commutated power switches. The term “l(fā)ine-commutated” describes the type of com-mutation, i.e. the transfer of current from one conducting element to the next, as a function of the mains voltage . To turn

59、 on a thyristor, an injection of a current pulse into its gate is required.,Note：the transfer of current from one conducting element to the next電流從一條支路轉(zhuǎn)換到另一條支路。 mains voltage 電網(wǎng)電壓。mains 總輸電線；總管道。,2.3 Power Electronic Converters Text,In low-power applications, vehicle, medicine, and hou-sehold devices, where there is no AC supply or where re-active current and harmonics caused by a line commuta-tion would be unreachable, it is accepted to employ for-ced commutated converters having a more complex cir-cui