电气工程及其自动化专业英语习题部分翻译

电气工程及其自动化专业英语习题部分翻译

Diodes in power electronic applications carry high currents,withstand high reverse voltages and should possess fast switching characteristics.These requirements render power diodes very different than the ordinary signal diodes.It is also difficult to achieve all the above three characteristics in a single device .Hence,several types of power diodes are available suited for particular applications.
The power diode is a high-current ,high-voltage diode with medium fast switching characteristics.The schottky Barrier diode uses a metal-semiconductor junction and has a lower on-state voltage than the p-i-n diodes.It has the high-current capability and fast switching characteristics but is is a low-voltage device and exhibits a much higher leakage current.These diodes are ideally suited for switch-mode power supplies.The on-state power losses,which are calculated by multiplying the on-state voltage drop by the on-state current,determine the package size of all diodes. . 二极管在电力电子应用中携带高电流、承受高的反向电压，应具有快速切换的特点。这些要求致使电力二极管跟平常的信号二极管很不一样。它也很难达到上述三个特征在一个设备。因此，几种类型的功率二极管可用适合特定的应用。
功率二极管是支大电流、高压二极管，带有中快速切换的特点。肖特基二极管的使用金属半导体结,比起PIN结二极管有一个低通电压。…它有支大电流能力和快速切换的特点，但是它是一个低电压装置,并表现出更高的泄漏电流的. 这些二极管很适合大多数的开关型电源。在导通状态，导通损耗是通过电流与导通压将的乘积来计算的,,它决定了二极管包装尺寸。
the boost converter is a voltage step-up and current step-down converter .the current source is synthesized from a DC voltage source by adding a large value inductor in series .in DC regulated power supply applications ,the voltage sink represents a large value capacitor in parallel with the load resistance .in the application of the DC motor control ,the voltage sink represents the back emf of the DC motor .the switching action produces a pulsating current .the capacitive filter smoothens the pulsating current and provides a DC voltage to the load 升压转换器是一个升压和降流的转换器。电流源是一个直流电压源添加一个大值电感串联合成的。 在直流稳压电源的应用,电压降代表一个大值电容并联一个负载电阻。在直流电机的控制应用中，电压降代表反电动势的直流电机。转换行为产生一个脉动电流。一个滤波电容是这个脉动电流平和并且提供直流的电压负荷。
Rotating electric machines take many forms and are known by many names –DC ,synchronous ,permanent-magnet ,induction ,hysteresis,etc.Although these machines appear to be quite dissimilar and require a variety of analytical techniques ,the physical principles governing their behavior are quite similar ,and in fact these machines can often be explained from the same physical picture.An induction machine ,in spite of many fundamental differences ,works on exactly the same principle ;one can identify flux distributions associated with the rotor and stator ,which rotor in synchronism and which are separated by some torque-producing angular displacement. 旋转电机采取多种形式,我们知道它的很多名字，像-DC、同步、永磁、归纳、滞环等。虽然这些机器似乎相当不同,需要各种分析技术，但指导他们行为的物理原则是非常相似的,事实上这些机器会经常被解释来自相同的物理图像。异步机,尽管许多基本的不同,但在相同的原理上工作室一致的;人们知道磁场分布与转子和定子有关，就是磁场与转子同步，并被产生的一些转力矩分离一定的角位移。
The commonest form of AC motor is the polyphase induction motor .as its name suggest ,the current in the rotor is derived from an external supply ,as in the DC motor ,but is induced by a moving magnetic field in the air-gap between the rotor and the stator .Excitation of the stator winding by a three-phase current causes a rotating magnetic field ,as each of the electro-magnets in turn reaches its maximum strength .And this rotating magnetic field between the stator and the rotor induces a voltage in the rotor conductors . 最常见的形式的交流电机是多相感应电动机,就像它的名字一样，转子内的电流来自外部的供应,而在直流电机中,电流是由转子和定子之间的气隙磁场所感应产生.定子绕组的激励来自一个三相电流引起由一个旋转磁场,每个electro-magnets反过来达到最优强度。这个定、转子之间旋转磁场在转子上产生一个电压。