Download GTU BE/B.Tech 2019 Winter 7th Sem Old 171002 Power Electronics Question Paper

Download GTU (Gujarat Technological University) BE/BTech (Bachelor of Engineering / Bachelor of Technology) 2019 Winter 7th Sem Old 171002 Power Electronics Previous Question Paper

Seat No.: ________ Enrolment No.___________

GUJARAT TECHNOLOGICAL UNIVERSITY

BE - SEMESTER ?VII (Old) EXAMINATION ? WINTER 2019
Subject Code: 171002 Date: 26/11/2019

Subject Name: Power Electronics
Time: 10:30 AM TO 01:00 PM Total Marks: 70

Instructions:
1. Attempt allquestions.
2. Make suitable assumptions wherevernecessary.
3. Figures to the right indicate fullmarks.

Q.1 (a) Explain the Thyristor dynamic characteristic.

07
(b) Explain R and RC trigger circuits for SCR with suitable waveform. 07
Q.2 (a) Discuss the two transistor model of a Thyristor and also derive the expression
for the anode current.
07

(b) Explain the operation of GTO with relevant diagram. 07

OR

(b) Explain the series parallel operation of thyristor. 07
Q.3 (a) What is chopper? Describe the working of Type A chopper. 07
(b) What is commutation? Explain with relevant waveforms class B commutation. 07

OR

Q.3 (a) Describe the construction and working of IGBT. Also enumerate the advantages
of IGBT over BJT and MOSFET
07
(b) Explain Single phase Full (Bridge) controlled rectifier with resistive load in
detail.
07
Q.4 (a) Describe the working of single phase half Bridge inverter. What is its main
drawback? Explain how this drawback is overcome?
07

(b) Describe the operation of three-phase inverter with 180-Degree conduction 07

OR

Q.4 (a) Describe the operation of single phase half wave controlled rectifier using SCR
for RL load and RL load with freewheeling diode.
07
(b) What is the principle of operation of step-up chopper? Explain with wave form. 07
Q.5 (a) What are the causes of overvoltage and overcurrent? Describe the method used
for overvoltage protection of SCR.
07
(b) Describe Switched mode power supply with necessary diagrams in detail 07

OR

Q.5 (a) What is forced commutation? With help of circuit diagram and necessary
waveform.Explain the auxiliary (Class D) commutation.
07
(b) List out turn on and turn off methods for thyristor. 07
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