Download GTU (Gujarat Technological University Ahmedabad) B.Tech/BE (Bachelor of Technology/ Bachelor of Engineering) 2020 Winter 6th Sem 2161006 Power Electronics Devices And Circuits Previous Question Paper
Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE- SEMESTER?VI (NEW) EXAMINATION ? WINTER 2020
Subject Code:2161006 Date:27/01/2021
Subject Name:Power Electronics Devices and Circuits
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) Why Germanium is not used in fabrication of thyristors.
03
(b) Sketch static I-V characteristics of a thyristor. Label the various
04
voltages, current and the operating modes on this sketch.
(c) Draw and explain two transistor analogy of SCR, and derive
07
I I
I
equation for anode current
2 g
CB 1
O
CBO2
I
.
a
1
1
2
Q.2 (a) Explain working principle of phase controlled rectifiers.
03
(b) Explain one quadrant converter.
04
(c) Explain working of single-phase half-wave circuit with RL, and
07
RL with freewheeling diode type load with necessary waveforms.
Q.3 (a) What do you mean by chopper? List out its applications.
03
(b) What is time ratio control in chopper? Explain the use of TRC for
04
controlling the output of chopper.
(c) List out types of chopper circuits and explain any one of them in
07
detail.
Q.4 (a) List a few industrial applications of inverter.
03
(b) Draw the voltage waveforms for 120 degree mode six-step 3-
04
phase voltage source inverter.
(c) Explain the working principle of a single-phase half-bridge
07
inverter with the help of the circuit and waveforms for both
resistive and inductive loads.
Q.5 (a) List out the applications of Cycloconverter.
03
(b) Draw the schematic diagram of three-phase to single-phase
04
Cycloconverter and basic circuit configuration with IG reactor.
(c) Draw the circuit diagram and explain the working principle of
07
Mid-point type single-phase to single-phase Cycloconverter.
Q.6 (a) Discuss braking modes operation in DC Drives.
03
(b) Discuss the concept of electric drives with neat and clean block
04
diagram.
(c) Describe single-phase half-wave converter feeding a separately
07
excited DC motor. Illustrate your answer with waveforms and
appropriate expressions.
1
Q.7 (a) List out advantages of AC drives.
03
(b) List out different speed control techniques used for three-phase
04
induction motors.
(c) With necessary diagram and characteristics discuss Stator Voltage
07
Control of IM.
Q.8 (a) Differentiate between offline and online UPS.
03
(b) Explain working principle of dielectric heating.
04
(c) Draw the block diagram of SMPS and explain it briefly.
07
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This post was last modified on 04 March 2021