C E1154 Pages: 2

Reg No.:_ Name:
APJ ABDUL KALAM TECHNOLOGICAL UNIVERSITY
V SEMESTER B.TECH DEGREE EXAMINATION(S), MAY 2019
Course Code: EE305
Course Name: POWER ELECTRONICS

Max. Marks: 100 Duration: 3 Hours
Graph sheet may be supplied on demand

PARTA
Answer all questions, each carries5 marks. Marks
1. Draw static characteristics of SCR, and based on that explain different modes of (5)
operation of SCR.
2. With the help of circuit diagram and waveform explain the operation of UJT (5)
triggering circuit for one thyristor.
3. Draw the circuit and derive the expression for output voltage of a single phase (5)
bridge converter.
4. Differentiate between voltage source inverter and current source inverter. (5)

With the help of waveform explain sinusoidal pulse width modulation used in (5)
single phase inverter.

6. Derive the equation for power factor for a single phase ac voltage controller (5)
feeding a resistive load.
7. Explain the necessity of filter in chopper circuit. (5)
8. Describe the working of type B chopper. (5)
PART ‏تا‎

Answer any twofull questions, each carries10 marks.

9 a) Explain with figures the switching characteristics of SCR during turn on and turn (5)
off.

b) With help of detailed structure explain the operation of MOSFET. (5)

10 a) With the help of circuit diagram and waveform explain the operation of RC (5)
triggering circuits for one SCR and also draw the voltage across the SCR.

b) Differentiate between features of UJT firing circuit, RC triggering circuit and R (5)
triggering circuit.
11 a) Mention the important ratings of the thyristors along with their significance. (5)
b) A battery is charged through a single phase half wave controlled converter. The (5)
supply voltage is 230 V, 50 Hz and battery emf is constant at 160 V. Find the

value of average charging current for firing angle of 30 degrees. Internal
resistance of battery is 2 Q.

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