自动化专业英语考试整理版

翻译

P.1

The voltage across a pure inductor is defined by Faraday’law,which states that the voltage across the inductor is proportional to the rate of change with time of the current through the inductor.thus we have U=Ldi/dt.

纯电感电压由法拉第定律定义，法拉第定律指出：电感两端的电压正比于流过电感的电流随时间的变化率。因此可得到：U=Ldi/dt 式中di/dt = 电流变化率，安培/秒；L = 感应系数，享利。

P.3

A three-phase electric circuit is energized by three alternating emfs of the same frequency and differing in time phase by 120 electrical degrees .

三相电压的产生三相电路可由三个频率相同在时间相位上相差120°电角度的电动势供电。

P.9

One problem with electronic devices corresponding to the generalized amplifiers is that the gains,AU or AI ,depend upon internal properties of two-port system( ).This makes design difficult since these parameters usually vary from device to device ,as well as temperature .

运算放大器像广义放大器这样的电子器件存在的一个问题就是它们的增益AU或AI取决于双端口系统(m、b、RI、Ro等)的内部特性。器件之间参数的分散性和温度漂移给设计工作增加了难度。

P.31

However, the disadvantage is that they generate harmonics in the utility system creating a power quality problem for other consumers.Besides thyristor converters constitute a low lagging power factor load on tha utility system.

但是，它们的缺点是在电力系统中产生谐波，对其他用户产生供电质量问题。此外，晶闸管变换器给电力系统提供了一个滞后的低功率因数负载。

P.32

Inverter is a device which receives DC voltage at one side and converts it to AC voltage on the other side

逆变器是从一侧接受直流电压，在另一侧将其转换成交流电压的装置。.

Inverter can be classified voltage-fed inverter and current-fed inverter.

逆变器可分成电压源型和电流源型两种。

P.36

The permanent-magnet motor has several advantages over convertional types of DC motors.One advantage is reduced operational cost.The speed characteristics of the permanent-magnet motor are similar to those of the shunt-wound DC motor.The direction fo rotation of a permanent-magnet moror can be reversed by reversing the twopower lines.

永磁电机相对于常规直流电机有几个优点。优点之一是减少了运行损耗。永磁电机的转速特性类似于并励式直流电机的转速特性。永磁电

机的旋转方向可通过将电源线反接来实现

P40

A signal proportional to the motor speed is obtained from the speed sensor.The speed sensor output is filtered to remove the AC ripple and compared with the speed reference. The speed error is processed through a speed controller.The output of the speed controller UC adjusts the rectifier firing angle A to make the actual speed close to the reference speed.

正比于电机速度的信号可从速度传感器获得。速度传感器的输出滤除交流波，并与速度参考值比较，速度误差被速度控制器处理，速度控制器的输出uc调整整流器的触发角α，以使实际的速度接近于参考速度。

P.45

In a wound-rotor machine,the rotor wingding si similar to that of the stator,but in a cage machine ,the rotor has a squirrel cage-like structure with shorted end rings.

对绕线式转子电机而言，转子绕组与定子绕组类似，但鼠笼式电机的转子具有鼠笼状结构，并且有两个短路环。

With the system transfer funcion known, the Routh-Hurwitz criterion will Tell us whether or not a system is stable .If it is stable ,the steady-state accuracy can be determined for various types of inputs.

如果已知系统的传递函数，劳斯-胡尔维茨判据会告诉我们系统是否