APJ ABDUL KALAM TECHNOLOGICAL UNIVERSITY
FIRST SEMESTER M.TECH DEGREE EXAMINATION. DECEMBER 201

5
ELECTRICAL & ELECTRONICS ENGINEERING
Stream: CONTROL SYSTEMS & ELECTRICAL MACHINES
OIEE6303 - Power Electronic Circuits
Time: 3 hours Max marks: 60

Answer any two full questions from each part.

PART-A (Module | and II)

1 a. Explain the turn-on and turn-off process in a GTO with the help of appropriate (5)
voltage and current waveforms.

.A single phase ac voltage controller is connected to a load of र = 100. Input (4) voltage is
230%, 50112. Firing angle delay is 309. Determine the rms value of 3 harmonic output
voltage

2 3. Discuss the power loss in a diode during the reverse recovery transients.

b Explain with relevant diagrams and waveforms the working of a 2 — stage (5) sequence
control of |- phase voltage controller with RL load.

3 a.Draw the power circuit diagram of a three phase fully controlled bridge rectifier (5) with
RLE load and explain the inverter operation with voltage waveform.

b Explain the conduction and switching losses in a IGBT.

PART-B (Module and IV)

4 a.Explain the operation of a Buck converter with circuit diagram and relevant (5)

waveforms.

0 With circuit diagram and relevant waveforms explain the operation of flyback (4)
converter. Derive the expression for average output voltage.

5 93. The data for a CLK converter are as follows;
VI = 160 V and frequency 25 kHz. For a duty cycle of 25%,

a Determine VCa and |/0;

(b) The peak forward voltage the switch has to block,