Download GTU (Gujarat Technological University) BE/BTech (Bachelor of Engineering / Bachelor of Technology) 2018 Winter 6th Sem New 2161006 Power Electronics Devices And Circuits Previous Question Paper
1
Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER ?VI (NEW) EXAMINATION ? WINTER 2018
Subject Code:2161006 Date:27/11/2018
Subject Name:Power Electronics Devices and Circuits
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) Draw the symbol of following:
(a)Diac (b) MCT (c) GTO
03
(b) Describe what is Power Electronics with help of neat sketch of diagram?
Also list out application of Power Electronics.
04
(c) Explain construction and characteristics of following :
(a)SCR (b) IGBT
07
Q.2 (a) Discuss comparison of Power BJT and Power MOSFET. 03
(b) What are the requirements of gate triggering for SCR? List out different
gate triggering circuits of SCR.
04
(c) Discuss and derive UJT relaxation Oscillator for Triggering SCR with
help of neat sketch of waveforms and circuit diagram.
07
OR
(c) Describe the single phase full wave controlled rectifier using RL load
with help of proper waveforms and circuit diagram.
07
Q.3 (a) State types of Commutation in SCR. 03
(b) An SCR with latching current of 200 mA is connected in series with dc
voltage supply of 200V, resistance of 20 ? and inductance of 2 H.
Calculate the minimum gate pulse width to turn on SCR.
04
(c) Describe the three (3-?) phase full wave controlled rectifier using RL
load and freewheeling diode with help of proper waveforms and circuit
diagram.
07
OR
Q.3 (a) What is a chopper? What is the application of chopper? 03
(b) What is inverter? How do you classify the inverters? 04
(c) Discuss the classification of DC converters with the help of circuit
diagram and the quadrant of operation.
07
Q.4 (a) Give the difference between Voltage source Inverter and Current Source
Inverter.
03
(b) List out classification of voltage control techniques. Explain one of
them.
04
(c) Describe the auxiliary commutated inverters (McMurry inverter) with
circuit diagram and waveform.
07
OR
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1
Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER ?VI (NEW) EXAMINATION ? WINTER 2018
Subject Code:2161006 Date:27/11/2018
Subject Name:Power Electronics Devices and Circuits
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) Draw the symbol of following:
(a)Diac (b) MCT (c) GTO
03
(b) Describe what is Power Electronics with help of neat sketch of diagram?
Also list out application of Power Electronics.
04
(c) Explain construction and characteristics of following :
(a)SCR (b) IGBT
07
Q.2 (a) Discuss comparison of Power BJT and Power MOSFET. 03
(b) What are the requirements of gate triggering for SCR? List out different
gate triggering circuits of SCR.
04
(c) Discuss and derive UJT relaxation Oscillator for Triggering SCR with
help of neat sketch of waveforms and circuit diagram.
07
OR
(c) Describe the single phase full wave controlled rectifier using RL load
with help of proper waveforms and circuit diagram.
07
Q.3 (a) State types of Commutation in SCR. 03
(b) An SCR with latching current of 200 mA is connected in series with dc
voltage supply of 200V, resistance of 20 ? and inductance of 2 H.
Calculate the minimum gate pulse width to turn on SCR.
04
(c) Describe the three (3-?) phase full wave controlled rectifier using RL
load and freewheeling diode with help of proper waveforms and circuit
diagram.
07
OR
Q.3 (a) What is a chopper? What is the application of chopper? 03
(b) What is inverter? How do you classify the inverters? 04
(c) Discuss the classification of DC converters with the help of circuit
diagram and the quadrant of operation.
07
Q.4 (a) Give the difference between Voltage source Inverter and Current Source
Inverter.
03
(b) List out classification of voltage control techniques. Explain one of
them.
04
(c) Describe the auxiliary commutated inverters (McMurry inverter) with
circuit diagram and waveform.
07
OR
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2
Q.4 (a) Discuss following:
(a) Plugging (b) Regenerating Braking
03
(b) List out various PWM techniques. Explain one of them. 04
(c) What is the basic principle of cycloconvertes? Explain single phase to
single phase cycloconverter with help of relevant circuit diagrams.
07
Q.5 (a) Define UPS. What is need of UPS? 03
(b) Explain constant V/f speed control technique for induction motor. 04
(c) With help of block schematic describe the use of Phase lock Loop (PLL)
for speed control of DC motors.
07
OR
Q.5 (a) What is Commutation? Explain briefly the classification of commutation
techniques.
03
(b) Draw and briefly explain closed control of DC drives. 04
(c) What is SMPS? Give the classification of SMPS. Also List out
advantages and disadvantages of SMPS.
07
*************
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This post was last modified on 20 February 2020