SANKALCHAND PATEL COLLEGE OF ENGINEERING

Department of Electrical Engineering

Subject: Power Electronics-I (150903)

Power Semiconductor Devices

1. Draw the internal diagram of an SCR (specifying the different layers and

their doping levels) and hence, explain the various operating modes of the

device. Also draw the static V- I characteristic of the SCR.

2. What do you understand by commutation of SCR? What are the

conditions required for successful commutation.

3. Write a short note on TRIAC and explain its characteristics.

4. Explain the various methods for turn-on of thyristors

5. Write short note on Diac with regard to their working and V-I

characteristics.

6. Describe turn on characteristics of SCR with proper waveforms.

7. Describe turn off characteristics of SCR with proper waveforms.

Choppers

1. Explain in brief various control strategies of a chopper.

2. Classify various chopper circuits based on principle of operation, circuit

configuration etc.

3. Draw the circuit configuration of step up chopper and explain its working

principle and also derive its output voltage equation in terms of duty cycle

and input voltage.

4. write short note on buck-boost converter

5. Describe the working of Morgan's chopper.

6. Explain circuit operation of Jones chopper.