研究生专业外语三单元.pptVIP

Chapter 3 Power Electronic Technology ;Section 1 Semiconductor Switches;semiconductor n. 半导体 power electronic n. 电力电子 loss n. 损耗，损失 winding n. ①绕组，线圈 ②一圈，一转 transformer n 变压器，变换器，变量器 dielectric n. 介质，电介质，绝缘材料；a. 绝缘的，介电的，介质的，不导电的 ;eddy n. 涡流，旋涡； a. 涡流的，涡旋的；v. 涡流，起旋涡 hysteresis n. 磁滞，滞后，迟滞 on-state a. 通态的，接通的，开态 off-state a. 关态的，断开的，断态的 microamp n. 微安 milliamp n. 毫安 ;waveform n. 波形 zero-voltage 电压过零的 zero-current 电流过零的 ;[1]The switching losses are significant and can be managed. They can be further divided into three components: (a) the on-state losses, (b) the off-state losses and ③the losses in the transition states.;[2]The practical switching devices have limited capabilities of rate of voltage transition and the rate of current steering. These nonabrupt transition ratesgive rise to power losses in the switching devices. We will examine these switching losses in two cases separately: the inductive and capacitive loads.;[3]The switching power losses increase linearly with the switching frequency like in the resistive case but about six times more. The upper bound on the switching frequency is also about half. ;[4]The capacitor is assumed to be large so that the voltage through it in steady state is nearly constant Uo. Assume that initially the switch is on, hence, the current through the switch is IS. The capacitor voltage is Uo, the voltage across the switch is zero and the diode V1 is reverse biased. .;Exercises ; 电力电子器件Power Electronic Device;全控型器件： GTR 晶体管 (Giant Transistor) IGBT 绝缘栅双极晶体管 (Insulated-Gate Bipolar Transistor) Power MOSFET 电力场效应晶体管 (Metal Oxide Semiconductor Field Effect Transistor) GTO 门极可关断晶闸管 (Gate-Turn-Off Thyristor) 不可控器件： Power Diode (Semiconductor Rectifier);Transition of Part of Speech;Transition of Part of Speech;Transition of Part of Speech;Transition of Part of Speech;Transition of Part of Speech;Transition of Part of Speech;Transition of Part of Speech;Transition of