MORE IN Power Electronics
MU Electrical Engineering (Semester 5)
Power Electronics
December 2014
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

Each question carry five marks:
1(a) List the advantages and disadvantages of current source inverter over Voltage source inverter
5 M
1(b) Once SCR is triggered, gate losses its control. Why?
5 M
1(c) What is a DC-DC converter? List few application of it.
5 M
1(d) What problem is caused by sharp single pluse triggering in a single phase AC voltage controllers when the load is inductive? How can this be solved?
5 M

2(a) Explain the concept of space vector modulation.
5 M
2(b) Compare the properties of power BJT, power MOSFET and IGBT.
5 M
2(c) Explain with relevant circuit diagram and waveforms the working of a single phase bidirectional phase control type AC voltage controllers connected to R load and obtain a relationship between the r.m.s. output voltage and the r.m.s. input voltage.
10 M

3(a) Draw a neat circuit and explain the working of full wave fully controlled 6-pulse 3 ϕ bridge circuit with resistive load. Draw the corresponding input and output voltage waveforms when the firing angle α=90°.
10 M
3(b) A single phase full wave fully controlled bridge rectifier is operated with an R-L load. Calculate average D.C. output voltage, input power factor, displacement factor and Total Harmonic distortion, if a 50 Hz. Sinusoidal voltage of 220 V. Peak is applied.
10 M

4(a) Explain with a neat circuit diagram and relevant waveforms, the working of a boost regulator and derive the expression for output voltage, filter capacitance and filter inductance.
10 M
4(b) Explain dynamic characteristics of SCR with wave forms.
10 M

5(a) Explain with relevant wave forms any one method to control the magnitude _ frequency of the output voltage of the single phase inverter.
10 M
5(b) Explain with circuit diagram and waveforms, three phase bridge inverter _ conduction mode.
10 M

6(a) Basic working principle of Matrix converter.
5 M
6(b) Any two commutation circuits of SCR.
5 M
6(c) Comparison of fully controlled and half controlled full wave rectifier with R-L load.
5 M
6(d) Snubber circuit of SCR
5 M

More question papers from Power Electronics