Hall Ticket No Question Paper Code: BPE208
INSTITUTE OF AERONAUTICAL ENGINEERING
(Autonomous)
M.Tech I Semester End Examinations (Regular) February, 2017
Regulation: IARE-R16
MULTI LEVEL INVERTERS
(Power Electronics and Electric 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. Explain the principle of operation of a single phase full bridge inverter circuit with the help of a
neat circuit diagram and necessary waveforms.
A single phase full bridge inverter is operated from a 48Vbattery and is supplying power to a
pure resistive load of 10
. Determine
i. The fundamental output voltage and first five harmonics
ii. RMS value by direct integration method,
iii. Output power
2. What is meant by Pulse Width Modulation. Explain any two modulation techniques for an
inverter circuit.
What is the function of a drive circuit. Explain about an Optocoupler isolated drive circuit
suitable for IGBT's and MOSFET.
UNIT II
3. Explain the concept of Multilevel Inverters.
Explain the effect of Multilevel operation on the harmonic content and switching stress.
4. Explain the principle of operation of SVPWM technique in linear modulation region.
What are the various topologies of Multilevel inverters. Explain the advantage of each type.

UNIT III
5. Explain the principle of operation of a cascaded Multilevel Inverter with a neat circuit diagram.

Consider the output phase voltage waveform for 6 (including 0-level) cascaded MLI, find the
generalized Fourier series of the phase voltage waveform obtained. 7M]
6. Distinguish between NPC and Cascaded H-bridge Multi level inverters.
Describe how high level inverters can be constructed employing capacitors and compare its cost
and reliability aspects.
Page 1 of 2
UNIT IV
7. Explain the principle of operation of a flying capacitor MLI.
Explain about a generalized MLI topology with self voltage balancing.
8. Explain the cascading of two level inverter concept.
Explain about a higher level inverter by using an open end induction machine with MLI on each
side.
UNIT V
9. Explain about the issues in capacitor voltage Balancing.
What are hybrid inverters. List the latest topologies available in MLI configurations.
10. Explain the principle of operation of a 12 sided polygon voltage space vector generation with
step by step procedure for generating space vectors.
What is meant by common mode voltage. Explain any method to eliminate such a voltage in an
induction motor drive.
Page 2 of 2