Download GTU (Gujarat Technological University) BE/BTech (Bachelor of Engineering / Bachelor of Technology) 2018 Winter 6th Sem New 2160902 Power Electronics ? Ii Previous Question Paper
1
Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER ?VI (NEW) EXAMINATION ? WINTER 2018
Subject Code:2160902 Date:27/11/2018
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.
Q.1 (a) What is an inverter? List a few industrial applications of inverters. 03
(b) Describe about PWM control in inverters. 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 180
o
conduction of SRCs with star connected load.
07
Q.2 (a) What are the control strategies for the regulation of output voltage in ac
voltage controllers?
03
(b) Explain the concept of ON-OFF or integral cycle control. 04
(c) Discuss the principle of phase control in single-phase full-wave ac voltage
controller with RL load. Illustrate your answer with relevant circuit diagram
and waveforms. Derive expression for rms output voltage.
07
OR
(c) With neat circuit diagram and waveforms explain 3-? ac voltage controller
with Y connected load.
07
Q.3 (a) Draw the circuit diagram and waveforms for current source inverter and give
the applications of current source inverter.
03
(b) A single phase full bridge inverter is connected to a dc source of Vs. Resolve
the output voltage wave shape into Fourier series.
04
(c) Explain the operation of a single phase parallel commutated inverter without
freewheeling diode, with the help of voltage and current waveforms.
07
OR
Q.3 (a) Define: (1). Harmonic factor, (2). Total Distortion Factor and
(3). Distortion Factor.
03
(b) Compare voltage source inverter and current source inverter in brief. 04
(c) What is space vector modulation? Explain the working principle of
SVM(Space Vector Modulation).
07
Q.4 (a) List the speed control methods for synchronous motor. 03
(b) Enlist advantages and disadvantages of cycloconverter. 04
(c) Draw and explain the operation of three phase cycloconverter with relevant
waveforms.
07
OR
Q.4 (a) Draw and Discuss briefly self-controlled synchronous motor drive. 03
(b) Explain operation of single phase to three phase cycloconverter. 04
(c) Derive an emf equation for the line-commutated phase-controlled
cycloconverters.
07
Q.5 (a) Draw the equivalent circuit of an induction motor referred to stator side. 03
(b) Explain the speed-torque characteristic of an induction motor. 04
(c) Draw and explain cyclocnverter based induction motor drive. 07
OR
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1
Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER ?VI (NEW) EXAMINATION ? WINTER 2018
Subject Code:2160902 Date:27/11/2018
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.
Q.1 (a) What is an inverter? List a few industrial applications of inverters. 03
(b) Describe about PWM control in inverters. 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 180
o
conduction of SRCs with star connected load.
07
Q.2 (a) What are the control strategies for the regulation of output voltage in ac
voltage controllers?
03
(b) Explain the concept of ON-OFF or integral cycle control. 04
(c) Discuss the principle of phase control in single-phase full-wave ac voltage
controller with RL load. Illustrate your answer with relevant circuit diagram
and waveforms. Derive expression for rms output voltage.
07
OR
(c) With neat circuit diagram and waveforms explain 3-? ac voltage controller
with Y connected load.
07
Q.3 (a) Draw the circuit diagram and waveforms for current source inverter and give
the applications of current source inverter.
03
(b) A single phase full bridge inverter is connected to a dc source of Vs. Resolve
the output voltage wave shape into Fourier series.
04
(c) Explain the operation of a single phase parallel commutated inverter without
freewheeling diode, with the help of voltage and current waveforms.
07
OR
Q.3 (a) Define: (1). Harmonic factor, (2). Total Distortion Factor and
(3). Distortion Factor.
03
(b) Compare voltage source inverter and current source inverter in brief. 04
(c) What is space vector modulation? Explain the working principle of
SVM(Space Vector Modulation).
07
Q.4 (a) List the speed control methods for synchronous motor. 03
(b) Enlist advantages and disadvantages of cycloconverter. 04
(c) Draw and explain the operation of three phase cycloconverter with relevant
waveforms.
07
OR
Q.4 (a) Draw and Discuss briefly self-controlled synchronous motor drive. 03
(b) Explain operation of single phase to three phase cycloconverter. 04
(c) Derive an emf equation for the line-commutated phase-controlled
cycloconverters.
07
Q.5 (a) Draw the equivalent circuit of an induction motor referred to stator side. 03
(b) Explain the speed-torque characteristic of an induction motor. 04
(c) Draw and explain cyclocnverter based induction motor drive. 07
OR
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Q.5 (a) Discuss effect of harmonics on machine performance. 03
(b) Explain in brief the different speed control methods for induction motor. 04
(c) Discuss closed loop V/f technique used for induction motor drive. 07
*************
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This post was last modified on 20 February 2020