Download GTU (Gujarat Technological University) BE/BTech (Bachelor of Engineering / Bachelor of Technology) 2019 Winter 6th Sem New 2160902 Power Electronics ? Ii Previous Question Paper
Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER ? VI (New) EXAMINATION ? WINTER 2019
Subject Code: 2160902 Date: 09/12/2019
Subject Name: Power Electronics ? II
Time: 02:30 PM TO 05:00 PM Total Marks: 70
Instructions:
1. Attempt all questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
MARKS
Q.1 (a) Define total harmonic distortion. What is the importance
of THD while designing an inverter?
03
(b) Write important features of sinusoidal pulse width
modulation used in PWM inverters.
04
(c) Mention disadvantages of harmonics produced by an
inverter. What are the different methods to reduce
harmonic content? Explain any one harmonics reduction
technique in detail.
07
Q.2 (a) Compare VSI and CSI. 03
(b) Write advantages and disadvantages of PWM technique
to generate gate pulse.
04
(c) Discuss the principle of working of a three-phase bridge
inverter with an appropriate circuit diagram. Draw gate
signal, phase voltage and line voltage waveforms for
120? conduction of SCRs with star connected resistive
load.
07
OR
(c) A full bridge inverter is operated from a dc supply of 280V
and in unipolar PWM mode. Determine (1) Fundamental
output voltage at M=0.8 and (2) First five dominant
harmonic order if Mf = 24.
07
Q.3 (a) Derive only expression of RMS output voltage of single
phase full wave AC regulators with R-load.
03
(b) Explain integral cycle control and phase control method. 04
(c) A single phase AC regulator with R-L load has input
voltage 230V, 50 Hz. R=4? and ?L=3?. Calculate the
control range of firing angle, maximum power and power
factor.
07
OR
Q.3 (a) Write application of Cycloconverters. 03
(b) Write advantages of AC voltage regulators using either
Triac or Thyristors. Mention at least one limitation of it.
04
(c) Write importance of sequence control in AC regulators.
Explain two stage sequence control AC regulators with
circuit diagram and waveforms.
07
Q.4 (a) Compare Cycloconverter with DC link converter. 03
(b) Write shortly Load-commutated cycloconverter. 04
(c) Describe single phase Cycloconverter with centre-tapped
transformer configuration with neat circuit diagram and
plot input and output voltage waveform for R-load and
frequency of 16.66 Hz.
07
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1
Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER ? VI (New) EXAMINATION ? WINTER 2019
Subject Code: 2160902 Date: 09/12/2019
Subject Name: Power Electronics ? II
Time: 02:30 PM TO 05:00 PM Total Marks: 70
Instructions:
1. Attempt all questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
MARKS
Q.1 (a) Define total harmonic distortion. What is the importance
of THD while designing an inverter?
03
(b) Write important features of sinusoidal pulse width
modulation used in PWM inverters.
04
(c) Mention disadvantages of harmonics produced by an
inverter. What are the different methods to reduce
harmonic content? Explain any one harmonics reduction
technique in detail.
07
Q.2 (a) Compare VSI and CSI. 03
(b) Write advantages and disadvantages of PWM technique
to generate gate pulse.
04
(c) Discuss the principle of working of a three-phase bridge
inverter with an appropriate circuit diagram. Draw gate
signal, phase voltage and line voltage waveforms for
120? conduction of SCRs with star connected resistive
load.
07
OR
(c) A full bridge inverter is operated from a dc supply of 280V
and in unipolar PWM mode. Determine (1) Fundamental
output voltage at M=0.8 and (2) First five dominant
harmonic order if Mf = 24.
07
Q.3 (a) Derive only expression of RMS output voltage of single
phase full wave AC regulators with R-load.
03
(b) Explain integral cycle control and phase control method. 04
(c) A single phase AC regulator with R-L load has input
voltage 230V, 50 Hz. R=4? and ?L=3?. Calculate the
control range of firing angle, maximum power and power
factor.
07
OR
Q.3 (a) Write application of Cycloconverters. 03
(b) Write advantages of AC voltage regulators using either
Triac or Thyristors. Mention at least one limitation of it.
04
(c) Write importance of sequence control in AC regulators.
Explain two stage sequence control AC regulators with
circuit diagram and waveforms.
07
Q.4 (a) Compare Cycloconverter with DC link converter. 03
(b) Write shortly Load-commutated cycloconverter. 04
(c) Describe single phase Cycloconverter with centre-tapped
transformer configuration with neat circuit diagram and
plot input and output voltage waveform for R-load and
frequency of 16.66 Hz.
07
2
OR
Q.4 (a) Explain briefly slip-power recovery scheme. 03
(b) Explain effect of non-sinusoidal waveform on
performance of AC machine.
04
(c) Write short technical note on matrix converter. 07
Q.5 (a) Compare AC drives and DC drives. 03
(b) Explain rotor resistance control of induction motor drives. 04
(c) Explain the method of controlling induction motors using
Cycloconverters.
07
OR
Q.5 (a) Why voltage to frequency ratio kept constant in
Induction Motor Drives.
03
(b) Briefly explain self controlled synchronous motor drive
using electronic commutator.
04
(c) List out types of synchronous motors. Explain Motoring
and Regeneration region of Cylindrical rotor synchronous
motor by plotting torque vs. ?
07
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This post was last modified on 20 February 2020