电力电子习题2013Quiz03.ppt

Trillion Q Zheng (郑琼林) BEIJING JIAOTONG UNIVERSITY 1896 * * * * * * * * * * * * Quiz 03 A single phase rectifier as shown in the Fig 01 with the following parameters: vs=220sin?t at 50Hz, Ls=1mH, Rs=1m?, Cd=1000uF, Rload=20 ?, diodes with 600V/ 20A.(2 point) (1) What measures can be added to the Fig 01 to suppress inrush current for protecting diodes at the start of the rectifier? Please. (2) Sketch waveforms of vs and the corresponding is. Fig 01 ? Answer (1) Add a current limit resistor R with a shunt contactor (switch). (1 point) Answer 1： Resistor limits inrush current (冲击电流)at startup Resistor switched out during operation Answer (2) Refer to Fig 5-23 on page 98. (1 point) Answer 1： Quiz 03 1. A single phase rectifier as shown in the Fig 01 with the following parameters: vs=220sin?t at 50Hz, Ls=1mH, Rs=1m?, Cd=1000uF, Rload=20 ?, diodes with 600V/ 20A. Fig 01 ? 估算启动限流电阻 估计最大启动冲击电流 Quiz 03 2. In the single phase rectifier of Fig 02, the input voltage has a square waveform amplitude of 200V at 50Hz, Assume Ls =3mH and Id=10A.(3 point) (1) get analytical expressions for μ and Vd in terms of Vs, Ls, ?, Id and ?.(2) Why is u independent of ? here? (3) Obtain is and vd waveforms and calculate the commutation interval and Vd for the following values of the delay angle ?: 45? and 120?. Fig 02 Answer Answer 2：分析 vs vd is 45° 120° vd is (1) (0.5+0.5 point) Answer Answer 2： vs vd is 45° 120° vd is (2) (1 point) μ is independent of ? here because the commutation voltage is the same. (3) vd waveforms (0.5 point) Answer Answer 2： While ?= 45?, Vd=94V; while ?= 120?, Vd=-72.7V (0.5 point) Quiz 03 3. Consider a three phase, half controlled rectifier shown in Fig 03. Calculate the triggering ? for which Vd =0.5Vd0. Assume Ls=0.(3 point) (1) Draw vd waveform and identify the devices that conduct during various intervals. (2) Obtain the DPF in the input line current and compare results with a full-bridge rectifier operating at Vd =0.5Vd0. (3) If Df in the Fig 03 is broken,