电力电子技术外文翻译.doc

1、晶闸管在晶闸管的工作状态，电流从阳极流向阴极。在其关闭状态，晶闸管可以阻止正向导电，使其不能运行。可触发晶闸管能使导通状态的正向电流在短时间内使设备处于阻断状态。 使正向电压下降到只有导通状态的几伏（通常为1至3伏电压依赖于阻断电压的速度）。一旦设备开始进行，闸极电流将被隔离。晶闸管不可能被闸关闭，但是可以作为一个二极管。在电路的中，只有当电流处于消极状态，才能使晶闸管处于关闭状态，且电流降为零。在设备运行的时间内，允许闸在运行的控制状态直到器件在可控时间再次进入正向阻断状态。在逆向偏置电压低于反向击穿电压时，晶闸管有微乎其微的漏电流。通常晶闸管的正向额定电压和反向阻断电压是相同的。晶闸管额定

2、电流是在最大范围指定RMS和它是有能力进行平均电流。同样的对于二极管，晶闸管在分析变流器的结构中可以作为理想的设备。在一个阻性负载电路中的应用中，可以控制运行中的电流瞬间传至源电压的正半周期。当晶闸管尝试逆转源电压变为负值时，其理想化二极管电流立刻变成零。然而，按照数据表中指定的晶闸管，其反向电流为零。在设备不运行的时间中，电流为零，重要的参数变也为零，这是转弯时间区间从零交叉电流电压的参考。晶闸管必须保持在反向电压，只有在这个时间，设备才有能力阻止它不是处于正向电压导通状态。如果一个正向电压应用于晶闸管的这段时间已过，设备可能因为过早地启动并有可能导致设备和电路损害。数据表指定晶闸管通过的反

3、向电压在这段期间和超出这段时间外的一个指定的电压上升率。这段期间有时被称为晶闸管整流电路的周期。 根据使用要求，各种类型的晶闸管是可得到的。在除了电压和电流的额定率，转弯时间，和前方的电压降以及其他必须考虑的特性包括电流导通的上升率和在关闭状态的下降率。 1。控制晶闸管阶段。 有时称为晶闸管转换器，这些都是用来要是整顿阶段，如为直流和交流电机驱动器和高压直流输电线路应用的电压和电流的驱动。主要设备要求是在大电压、电流导通状态或低通态压降中。这类型的晶闸管的生产晶圆直径到10厘米，其中平均电流目前大约是4000A，阻断电压为5之7KV。 2。逆变级的晶闸管。这些设计有小关断时间，除了低导通状态电

4、压，虽然在设备导通状态电压值较小，可设定为2500V和1500A。他们的关断时间通常在几微秒范围到100s之间，取决于其阻断电压的速率和通态压降。 3。光控晶闸管。这些会被一束脉冲光纤触发使其被引导到一个特殊的敏感的晶闸管地区。光化的晶闸管触发，是使用在适当波长的光的对硅产生多余的电子空穴。这些晶闸管的主要用途是应用在高电压，如高压直流系统，有许多晶闸管被应用在转换器阀门上。光控晶闸管已经发现的等级，有4kV的3kA，导通状态电压2V、光触发5毫瓦的功率要求。 还有其它一些晶闸管，如辅助型关断晶闸管（关贸总协定），这些晶闸管其他变化，不对称硅可控（ASCR）和反向进行，晶闸管（RCT）的。这些

5、都是应用。B部分功率集成电路功率集成电路的种类现代半导体功率控制相当数量的电路驱动，除了电路功率器件本身。 这些控制电路通常由微处理器控制，其中包括逻辑电路。这种在同一芯片上包含或作为功率器件来控制和驱动电路将大大简化了整个电路的设计和扩大潜在的应用范围。这样的整合将会产生一个更便宜和更可靠的电源控制系统。总的来说，将减少复杂性（较少独立电路和使用这类功率集成电路系统组件）。 这样的整合已经被证明有很多应用。 这里有三个类功率积体电路包括所谓的智能或智能开关，高电压集成电路（HVIC能够）和离散模块。功率集成电路领域，特别是智能交换机和HVIC，被认为是500-100 A和目前的水平相差约10

6、00伏或更少。离散模块涵盖更广泛的电压电流范围。 智能开关垂直电力及其他组件的设备，而无需动力装置的垂直过程的顺序是可行的。 如片上的过流和过温传感器，以及驱动部分都是可用的，可以包含例子。PN结形成的N - 漂移地区和P -区域始终是反向偏置，如果垂直功率场效应管的漏极是相对于电源，从而积极为这个路口提供了电气隔离之间的横向和纵向的场效应管。高电压（HVIC）集成电路都采用传统的逻辑设备制造过程，但一些修改，使横向高电压设备也可兼容低电压的设备。两个简单的例子，每个在其中的各种设备之间实现了电气隔离的方式不相同，HVIC有更多的复杂性。 离散模块是由多个芯片安装在一个共同的绝缘基板，密封成一

7、个包。他不包括各种芯片垂直器件，驱动电路芯片和控制电路芯片（甚至一个PWM控制器），以及其他可能的功能。尽管这种方法并不是一个完全集成制造方法，但是我们有潜力，因为它目前广泛应用在智能开关或HVIC。石化商业化所面临的挑战使用整合的电力电子电路面临几个经济和技术方面的挑战。技术问题包括:1。电气隔离从低电压元件高压元件。2。热管理功率器件，通常工作在更高的温度下的成套设备。3。高压导线上的互连芯片运行在低电压设备或低电压地区。4。制造过程中必须提供的设备和组件的完整范围 除了晶体管二极管、电阻、电容此外，功率集成电路使用面临许多经济问题。 这些包括：1。大量的前期开发成本之前，任何生产运行。2

8、。成本差异的三种类型。3。需要大批量应用到恢复大开发费用。在解决挑战的研究进展低压设备与来自高压元素，也可以实现介电分离、PN结分离、或自己分离。介质隔离能实现两种方式。隔离主要由蚀刻切片或晶圆片上面生长着一层二氧化矽。其次，把矽沉积在二氧化硅中。沉积下来的硅退火后的，高温，在再结晶过程中，可以用于制作低压设备。介质隔离是免费的寄生设备，如二极管。C部分硅控整流器（SCR）SCR已成为大功率电器的重要组成部分和信号调理控制的一部分。在某些方面，它是一个固态继电器的替换品，虽然在某些方面还有一些差距。在理想中的标准二极管，是一个单向传导电流的器件。在理想的意义上可控硅整流器，就像是一个二极管不会

9、在任何一个方向进行，直到它被打开或关闭。注相似一个二极管，但添加了终端，叫做门。如果SCR是向前偏见，否则就无法行为。现在，假设一个电压，就放在阴极门。会有一些积极的电压值 - 触发电压 - 其中可控硅将开始进行阳极阴极和行为像一个正常的二极管。即使门电压拿走，它也会继续进行这样一个二极管，这是，一旦打开，将为零，无论门。只有这样，才能把可控硅回“关”是有正向偏压条件下带走。这意味着电压必须跌破的可控硅的正向压降，使低于最低值，电流下降称为维持电流，或从阳极阴极必须实际极性相反。认为可控硅不能轻易被关闭的事实限制了它在直流应用到那些下面的一些减少持有正向电流值的方法可以提供案件。在交流电路中，

10、可控硅整流器自动打开时，在每半个周期的交流电压施加到可控硅的极性就会相反。可控硅的特点及规格如下。1。最大正向电流。有一个最大电流可控硅可以放在正向电流中，不会损坏。此值各不相同，从几百毫安还有千余毫安放大器，大型工业类型。2。反向峰值电压。一个二极管，有一个额外相反偏差电压电压那能适用于控硅整流器无损害。他们的值不同，几个伏特到几千伏特。3。触发电压。最低栅极电压来驱动不同的可控硅导通类型之间的大小，从几伏到40V。4。触发电流。有一个最低的触发电流，在提供电压源前必须SCR可以被关闭。几个值有所不同，从几毫安到几百毫安。5。保持电流。这是指最低阳极对阴极电流必要可控硅保持在正向导电状态进行

11、。该值从20到100毫安。AC操作一个变化中的可控硅的是以半波运行的直流电压RMS操作。触发电压是由一些电路研制生产在一定的外加交流信号选择阶段的脉冲。因此，在可控硅打开一个重复的方式，如图所示。 SCR关闭，当然，在每半个周期当AC极性反转。通过改变部分正半周时，触发应用，有效（RMS）的直流电压值应用于负载可提高。当然，这可能是此直流电压半波整流电路的最大有效值。如果需要更多的电源，可选用可控硅全波桥式电路。触发电压，现在必须在每半个周期产生并应用到可控硅触发（门）终端。在过程控制应用中，控制器的输出信号将被用来驱动电路，改变了在该脉冲被应用到门，从而改变了通电的载入时间。加到负载上的电压

12、脉动直流。此配置不能用于带负荷操作，需要交流电压。触发控制 SCR在过程控制的应用，电路控制信号转换成合适的触发信号传送到SCR是必需的。这样的电路通常是由电子系统组成，该系统使用的控制电压决定交流负载电压。控制信号电压通过一个指示灯来提供相应的驱动器晶体管，从而确保了电源电路控制电路隔离。在低基数驱动电容充电慢，直到不会达到周期后期的可控硅的触发电压（因此低负荷功率）。 一个大控制信号提供在高调速系统中，电容器收取的速率将要快得多。然后，可控硅将打开更长的周期，将提供更多的能力来承担负载。电力电子技术 Power Electronic Technology (II)Part A Thyris

13、tors In the on-state of the thyristor, t he main current flows from the anode to the cathode. In itsoff-state, the thyristor can block a forward polarity voltage and not conduct.The thyristor can be triggered into the on-state by applying a pulse of positive gate current for a short duration provide

14、d that the device is in its forward blocking state. The forward voltage drop in the on-state is only a few volts (typically 1 to 3 V depending on the device blocking voltage rating).Once the device begins to conduct, it is latched on and the gate current can be removed. T he thyristor cannot be turn

15、ed off by the gate, and the thyristor conducts as a diode. Only when the anode current tries to go negative under the influence of the circuit in which the thyristor isconnected does the thyristor turn off and the current go to zero. This allows the gate to regaincontrol in order to turn the device

16、on at some controllable time after it has again entered theforward blocking state.In reverse bias at voltages below the reverse breakdown voltage, only a negligibly smallleakage current flows in the thyristor. Usually the thyristor voltage rating for forward and reverse blocking voltages are the sam

17、e. Usually the thyristor voltage rating for forward and reverse blocking voltages are the same. Using the same arguments as for diodes, the thyristor can be represented by the idealized characteristics in analyzing converter topologies.In an application of resistant load circuit, control can be exer

18、cised over the instant of current conduction during the positive half cycle of source voltage. When the thyristor current tries to reverse itself when the source voltage goes negative, the idealized thyristor would have its current become zero immediately.However, as specified in the thyristor data

19、sheets, the thyristor current reverses itself beforebecoming zero. The important parameter is not the time it takes for the current to become zerofrom its negative value, but rather the turn-off time interval t q from the zero crossover of thecurrent to the zero crossover of the voltage across the t

20、hyristor. D uring t q a reverse voltage must bemaintained across the thyristor and only after this time is the device capable of blocking a forward voltage without going into its on-state.If a forward voltage is applied to the thyristor before this interval has passed, the device may prematurely tur

21、n on and damage to the device and circuit could result. Thyristor data sheets specify with a specified reverse voltage applied during this interval as well as a specified rate-of-rise of voltage beyond this interval. This interval is sometimes called the circuit-commutated-recovery time of the thyri

22、stor.Depending on the application requirements, various types of thyristor are available. Inaddition to voltage and current ratings, turn-off time , and the forward voltage drop, othercharacteristics that must be considered include the rate-of-rise of the current (d i /d t ) at turn-on and the rate-

23、of-rise of voltage (d u /d t ) at turn-off.1. Phase-control thyristors. Sometimes termed converter thyristors, these are used primarily for rectifying line-frequency voltage and current in applications such as phase-controlle drectifiers for dc and ac motor drives and in high-voltage dc power transm

24、ission. T he main device requirements are large voltage and current handling capabilities and a low on-state voltage drop. T his type of thyristor has been produced in wafer diameters of up to 10 cm, where the average current is about 4000 A with blocking voltages of 57 kV.2. Inverter-grade thyristo

25、rs. T hese are designed to have small turn-off times t q in addition tolow on-state voltages, although on-state voltages are larger in devices with shorter values of t.T hese devices are available with ratings up to 2500V and 1500A. Their turn-off times are usually in the range of a few microseconds

26、 to 100 s depending on their blocking voltage ratings and on-state voltage drops.3. Light-activated thyristors. These can be triggered on by a pulse of light guided by optical fibers to a special sensitive region of the thyristor. The light-activated triggering of the thyristor uses the ability of l

27、ight of appropriate wavelengths to generate excess electron-hole pairs in the silicon. The primary use of these thyristors are in high-voltage applications such as high-voltage dc transmission where many thyristors are connected in series to make up a converter valve. Light-activated thyristors have

28、 been reported with ratings of 4kV and 3kA, on-state voltages of about 2V, and light trigger power requirements of 5 mW.There are other variations of these thyristors such as gate-assisted-turn-off thyristors (GATT),asymmetrical silicon-controlled-recrifiers (ASCR), and reverse-conducting-thyristors

29、 (RCT).T hese are utilized based on the application.Part BPower Integrated CircuitsTypes of Power Integrated CircuitsModern semiconductor power control circuits have a considerable amount of control drivecircuitry in addition to the power device itself. The control circuitry often includes logic cir

30、cuitrycontrolled by microprocessors. The inclusion of such control and drive circuitry on the same chipor wafer as the power device would greatly simplify the overall circuit design and broaden the range of potential applications. A cheaper and more reliable power control system would result from su

31、ch integration. Overall, there would be a reduction in the complexity (fewer separate components) of circuits and systems using such power integrated circuits.Such integration has already been demonstrated in many applications. There are three classesof power integrated circuits including so-called

32、smart or intelligent switches , high voltageintegrated circuits (HVICs), and discrete modules. The domain of power integrated circuits,particularly smart switches and HVICs, is considered to be current levels less than 500-100 A andvoltages of approximately 1000 V or less. Discrete modules cover a m

33、uch wider voltage-current range.Smart switches are vertical power devices onto which additional components are added to theextent feasible without requiring major changes to the vertical power device process sequence.F eatures such as on-chip sensors for overcurrents and overtemperature as well as p

34、ortions of drive circuits are examples of things that can be included. The pn junction formed from the N drift region and the P-body region is always reverse biased if the drain of the vertical power MOSFET is positive with respect to the source and thus, this junction provides the electrical isolat

35、ion between the lateral and vertical MOSFETs.High-voltage integrated circuits (HVICs) are made using conventional logic-level devicefabrication process but with some modifications so that lateral high-voltage devices can also befabricated on the wafer compatibly with the low voltage devices. Two sim

36、ple examples differ from each other in the manner in which electrical isolation between the various devices is realized.A ctual HVICs have considerably more complexity.Discrete modules are composed of multiple chips mounted on a common insulating substrateand hermetically sealed into a single packag

37、e. The various chips may include vertical powerdevices, a drive circuit chip, and a control circuit chip (perhaps even a PWM controller), andpossibly other functionality. Although this approach is not a completely integrated fabrication method, we include it because of its potential and its current

38、widespread application compared to smart switches or HVICs.Challenges Facing PIC Commercial CommercializationThe use of power-integrated circuits in power electronics applications faces severalchallenges both technical and economic. T he technical issues include:1. Electrical isolation of high-volta

39、ge components from low-voltage components.2. Thermal management-power devices usually operate at higher temperatures thanlow-voltage devices.3. On-chip interconnections with high-voltage conductor runs over low-voltage devices orlow-voltage regions.4. Fabrication process must provide full range of d

40、evices and components transistors(BJT, MOSFETs, IGBTs) diodes, resistors, capacitors, etc.I n addition, the use of power integrated circuits faces several economic issues. T hese include:1. Large up-front development costs prior to any production runs.2. Cost differentials between the three types of

41、 PICs.3. Need for high volume applications to recover large development expenses.Progress in Resolving ChallengesIsolation of low-voltage devices from high-voltage elements, can be accomplished by eitherdielectric isolation, pn junction isolation, or self-isolation. Dielectric isolation can be imple

42、mented in two ways. The isolation basically consists of etching a pocket in the chip or wafer and then growing a layer of silicon dioxide in it. Next, a layer of silicon is deposited over the SiO 2 . After annealing the deposited silicon at a high temperature, it becomes recrystallized and can then

43、be used for fabricating the low-voltage devices. Dielectric isolation is free of parasitic devices such as diodes.Part CSilicon-Controlled Rectifier (SCR)The SCR has become an important part of high-power electrical signal conditioning andcontrol. In some regards, it is a solid-state replacement for

44、 the relay, although there are someproblems if that analogy is taken too far. The standard diode is, in the ideal sense, a device thatwill conduct current in only one direction. The SCR, again in the ideal sense, is like a diode thatwill not conduct in either direction until it is turned on or “ fir

45、ed. ” Note the similarity to a diode,but with the added terminal, called the gate . If the SCR is forward biased ( that is, positive voltageon the anode with respect to the cathode), it will not conduct. Now, suppose a voltage is placed onthe gate with respect to the cathode. There will be some posi

46、tive value of this voltage the trigger voltage at which the SCR will start conducting anode to cathode and behave like a normal diode.Even if the gate voltage is taken away, it will continue to conduct like a diode; that is, once turned on it will stay on, regardless of the gate. The only way to tur

47、n the SCR back “ off ” is to have the forward-bias condition taken away. This means the voltage must drop below the forward-voltage drop of the SCR so that the current drops below a minimum value, called the holding current , or the polarity from anode to cathode must actually reverse. The fact that

48、 the SCR cannot be turned off easily limits its use in dc applications to those cases where some method of reducing the forward current to below the holding values can be provided. In ac circuits, the SCR will automatically turn off in every half cycle when the ac voltage applied to the SCR reverses polarity.Characteristics and specifications of SCRs are as follows.1. Maximum forward current. There is a maximum current that the SCR can carry in theforward direction without damage. This value varies from a few hundred milliamps tomore than a thousand amps, for large