EE2301 POWER ELECTRONICS ANNA UNIVERSITY NOV/DEC 2011 , ANNA UNIVERSITY QUESTION PAPER for EEE,ICE DPT ...

EE2301 POWER ELECTRONICS ANNA UNIVERSITY NOV/DEC 2011 , ANNA UNIVERSITY QUESTION PAPER for EEE,ICE DPT ... 

B.E./B.Tech. DEGREE EXAMINATION, NOVEMBER/DECEMBER 2011.

Fifth Semester

Electrical and Electronics Engineering

EE 2301 — POWER ELECTRONICS

(Common to Instrumentation and Control Engineering)

(Regulation 2008)

Time : Three hours Maximum : 100 marks

Answer ALL questions.

PART A — (10 × 2 = 20 marks)

1. State the condition to be satisfied for the load commutation in SCR.

2. Define ‘Turn off time’ of SCR.

3. Give any two differences between single phase full converter and semi converter?

4. What is meant by line commutated inverter?

5. What are the advantages of SMPS over phase controlled rectifiers?

6. Give the uses of resonant switching.

7. What is meant by current source inverter?

8. Why is the series inverter called so?

9. What are the applications of cyclo converter?

10. What is Integral cycle control?

PART B — (5 × 16 = 80 marks)

11. (a) Describe the current commutation technique to turn off the SCR with neat sketch and waveforms. (16)

Or

(b) With neat sketch explain the turn on and turn off characteristic of SCR. (16)

12. (a) Explain the working of a three phase full converter with ‘R’ load for the firing angles of 60°, 90° and 150°. (16)

Or

(b) (i) Explain the operation of a single phase full bridge converter with RL load for continuous and discontinuous load currents. (10)

(ii) A single phase full bridge converter is connected to ‘R’ load. The source voltage is of 230 V, 50 Hz. The average load current is of 10 A. For R = 20 _ find the firing angle. (6)

13. (a) Explain the working of Buck–Boost converter with sketch and waveforms and also drive the expression for SI . (16)

Or

(b) With a neat sketch and output voltage waveforms, explain the working of full bridge SMPS. (16)

14. (a) With a neat sketch and output voltage waveforms, explain the working of three phase bridge inverter in 180 degree mode of operation. (16)

Or

(b) Discuss the different modes of operation of series resonant inverter with unidirectional switch with neat circuit diagram and waveforms. (16)

15. (a) Discuss the working of 2 stage sequence control of AC voltage controller. (16)

Or

(b) Discuss the working of a 3 phase to single phase cyclo-converter with neat voltage and current waveforms. (16)