# Power Electronics 5th AM11 EE2301

B.E./B.Tech. DEGREE EXAMINATION, APRIL/MAY 2011
Fifth Semester
Electrical and Electronics Engineering
EE 2301 - POWER ELECTRONICS
(Common to Instrumentation and Control Engineering)
(Regulation 2008)

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PART A — (10 × 2 = 20 marks)

1. What are the parameters involved in switching loss of a power device?
2. What are the methods to turn-on the SCR?
3. Write any four performance parameters of a phase controlled rectifiers.
4. What is a dual converter?
5. What is the principle of current limit control for chopper?
6. What is meant by SMPS and mention its two advantages?
7. What are the PWM methods for voltage control within the inverters?
8. What are the merits and demerits of current source inverter?
9. What is a matrix converter?
10. List out the different types of cycloconverter.

PART B — (5 × 16 = 80 marks)

11. (a) Explain the switching characteristics of the IGBT with neat circuit diagram and waveforms. (16)
Or
(b) Write short notes on :
(i) Snubber circuit for BJT (8)
(ii) Commutation circuit of SCR. (8)

12. (a) Describe the effect of source inductance on the performance of a single phase full converter indicating clearly the conduction of various thyristors during one cycle. Derive the expression for its output voltage.(12+4)
Or
(b) Explain the principle of operation of single phase dual converter with neat power circuit diagram. (16)

13. (a) A step-up chopper has input voltage of 220 V and output voltage of 660 V. If the non-conducting time of thyristor chopper is 100 Âµ s, compute the pulse width of output voltage. Incase pulse width is halved for constant frequency operation, find the new output voltage.(16)
Or
(b) Explain the various modes of operation of Boost DC-DC converter with necessary waveforms. (16)

14. (a) Describe the operation of single phase auto sequential commutated current source inverter with power circuit and waveforms. (16)
Or
(b) Describe the operation of three phase voltage source inverter with 120° mode of operation. (16)

15. (a) Explain the working of multistage sequential control of AC voltage controller. (16)
Or
(b) Explain the principle of single phase to single phase step-down cycloconverter with power circuit and waveforms. (16)