Download GTU (Gujarat Technological University Ahmedabad) B.Tech/BE (Bachelor of Technology/ Bachelor of Engineering) 2020 Winter 6th Sem 2160902 Power Electronics II Previous Question Paper
Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE- SEMESTER?VI (NEW) EXAMINATION ? WINTER 2020
Subject Code:2160902 Date:27/01/2021
Subject Name:Power Electronics ? II
Time:02:00 PM TO 04:00 PM Total Marks: 56
Instructions:
1. Attempt any FOUR questions out of EIGHT questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
MARKS
Q.1 (a) Give classification of inverters. Draw circuit diagram of
03
1-phase half bridge center tapped inverter.
(b) Draw phase voltage and line voltage waveform for 1200
04
conduction of 3-phase H bridge inverter.
(c) Draw circuit diagram of 3-phase cycloconverter.
07
Comment on output harmonics in the cycloconverter.
Q.2 (a) Define modulation index. What is over modulation
03
region?
(b) Distinguish unipolar and bipolar PWM techniques.
04
(c) Explain working of line commutated inverters. Give
07
applications of line commutated inverters.
Q.3 (a) Give comparison of AC voltage controller with inverter.
03
(b) Determine output harmonics for the ratio fc/fm=15 in sine
04
PWM technique.
(c) Explain effect of non-sinusoidal wave on the performance
07
of rotating AC machine.
Q.4 (a) Compare space vector pulse width modulation (SVPWM)
03
technique with sine PWM (SPWM) technique.
(b) To eliminate 5th harmonic using selected harmonic
04
elimination technique, how many variables are to be
determined?
(c) Explain sine PWM technique with waveform. How output
07
voltage varies with modulation index?
Q.5 (a) Distinguish load commutated cycloconverter with line
03
commutated cycloconverter.
(b) Give the reason to keep voltage to frequency ratio constant
04
in induction motor drive. Suggest the converter that can be
used for such applications.
(c) Explain the basic principle of matrix converter. Compare
07
it with inverter and cycloconverter.
Q.6 (a) Explain basic principle of cycloconverter.
03
(b) Justify requirement of gating circuit. Mention its
04
components.
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(c) Explain the working of single phase full wave ac voltage
07
controller connected to R-L load. Derive its equation for the
average output voltages.
Q.7 (a) Draw torque speed characteristics of induction motor.
03
Define various region based on the slip value.
(b) Explain working principle of self-controlled synchronous
04
motor drive using cycloconverter.
(c) Explain soft starting of induction motor. Which converter
07
can be used for this purpose?
Q.8 (a) Explain rotor resistance control of induction motor.
03
Suggest the converter that can be used for this application.
(b) Explain working principle of self-controlled synchronous
04
motor drive using load commutated thyristor inverter.
(c) Explain static Kramer drive.
07
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This post was last modified on 04 March 2021