Power Electronics and Drives - May 2015

MU Instrumentation Engineering (Semester 6)

Total marks: --
Total time: -- INSTRUCTIONS
(1) Assume appropriate data and state your reasons
(2) Marks are given to the right of every question
(3) Draw neat diagrams wherever necessary

Solve any four:

1 (b) Explain UJT with basic construction. 5 marks

1 (c) Write a short note on brushless DC motor. 5 marks

1 (d) Write a protection scheme for over voltage for SCR. 5 marks

1 (e) Compare series and parallel inverter. 5 marks

2 (a) List out various triggering methods of SCR. Explain RC triggering of SCR with diagram. 5 marks

2 (b) What is communication SCR? Explain class C type of commutation with neat waveforms. 5 marks

3 (a) Explain asymmetric semi-converter along with waveforms for α=45°. 5 marks

3 (b) Explain fan regulator with disc-TRIAC scheme. 5 marks

4 (a) Draw and explain H-Bridge inverter, with neat waveform, using IGBT. 5 marks

4 (b) Explain series inverter. Write down its merits and demerits. 5 marks

5 (a) Explain Buck converter. Derive the expression for selection of inductor. 5 marks

5 (b) Explain working principle of induction heating. Give example and write down its merits and demerits. 5 marks

6 Design an AC power control for firing angle of 90° to supply ac voltage to a resistive load of 10Ω from 230v, 50H_z mains supply. Use SCR-UJT circuit. No temp. Compensation resistor is required. (Use UJT 2N 2646). 5 marks