B.E./B.Tech. DEGREE EXAMINATION, NOV/DEC 2008
Electronics and Electronics Engineering
EE 332 – POWER ELECTRONICS
(Common to Fourth Semester Mechatronics Engineering)
Time : Three Hours Maximum: 100 marks
Answer all questions
PART A – (10x2=20marks)
1. Why is turn on time of devices less than turn off time?
2. Mention the advantages of GTo.
3. Why is the power factroe of semi converters better than the full converters?
4. What is the inversion mode of the converter?
5. State the limitations of the voltage commutated choppers.
6. Mention few applications of DC choppers.
7. What are the advantages of current source inverter over voltage source inverter?
8. What is PWM control?
9. List the merits and demerits of on – off control.
10. What are the applications of cycloconverters?
PART B – (5x16=80)
11.(a) With neat sketch explain the constructional details and working of an enhancement type power MOSFET with characteristics. (16)
(b) Explain the constructional details of IGBT with equivalent circuit and discuss its characteristics. (16)
12.(a) Draw the circuit diagram of three phase full converter with inductive load and explain its operation with relevant waveform. Derive its average output voltage. (16)
(b) (i) Discuss the effect of source inductance in a controlled rectifier. (8)
(ii) With aid of circuit diagram explain the operation of UJT firing circuit.(8)
13.(a) Draw the circuit diagram of load commutated chopper and explain its operation with relevant waveforms at various stages. (16)
(b) Explain the operation of current commutated chopper with circuit diagram and relevant waveforms at various stages. (16)
14. (a) Explain the working of series inverter with the help of circuit diagram and relevant waveforms. (16)
(b) Draw the circuit diagram of current source inverter and explain its operation with relevant waveforms. (16)
15. (a) Explain the operation of single phase half wave phase controller and single phase full wave phase controller with circuit diagrams and waveforms.(16)
(b) Draw the circuit diagram of three phase to single phase cycloconverter and explain its operation with waveforms. (16)