Hall Ticket No Question Paper Code: BPE005
INSTITUTE OF AERONAUTICAL ENGINEERING
(Autonomous)
M.Tech II Semester End Examinations (Supplementary) January, 2018
Regulation: IARE-R16
DC TO AC CONVERTERS
(Power Electronics and Electrical Drives)
Time: 3 Hours Max Marks: 70
Answer ONE Question from each Unit
All Questions Carry Equal Marks
All parts of the question must be answered in one place only
UNIT I
1. What are the commonly used modulation techniques for controlling the voltage of single phase
inverter? Explain principle of operation of any one of them.
Discuss the effect of over-modulation on the performance of sinusoidal PWM controlled three
phase inverters.
2. How is staircase modulation different from stepped modulation? Explain briefly.
With relevant diagrams, discuss the operation of a boost inverter.
UNIT II
3. Briefly explain the different types of zero current switching resonant converters.
Discuss the operation of quasi-resonant inverters.
4. Write short notes on resonance dc link inverters.
A series resonance inverter with series load delivers a load power of 1kW at resonance. The load
resistance is10ohm. The resonant frequency is 20kHz. Determine
i. the dc input voltage,
ii. the quality factor, if it is required to reduce the load power to 250W by frequency control so
that u=0.8,
iii. the inductance value, and
iv. the capacitance value.
UNIT III
5. Explain how a multilevel converter can be used for reactive power compensation.
List the general features of multilevel converters.
6. Explain how multilevel converters connected back-to-back can be used to connect two asynchronous
systems.
Compare the different configurations of different multilevel converters.
UNIT IV
Page 1 of 2
7. Discuss the operation of forward converters. Also mention the use of reset winding in forward
converters.
Write short notes on bidirectional power supplies.
8. The average output voltage of the push-pull converter with a resistive load of 0.8Ω is 24V. The
on-state voltage drop of the transistors and diodes in the circuit is 1.2V and 0.7V respectively.
The turns ratio of the push-pull transformer is 0.25 (i.e. Ns/Np). Find, the average input current,
average transistor current, peak transistor current and rms transistor current.
Explain the operation of a flyback converter with neat diagrams.
UNIT V
9. With relevance to ac power supply control circuits, write short notes on voltage mode control
and current mode control.
What are the different types of power line disturbances? Briefly explain about them.
10. Write short notes on the effect of power line disturbances on sensitive equipment.
Draw the generalized block diagram of an uninterruptible power supply and explain the function
of each block.