Download GTU BE/B.Tech 2019 Winter 6th Sem New 2161006 Power Electronics Devices And Circuits Question Paper

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GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER- VI (New) EXAMINATION - WINTER 2019

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Subject Code: 2161006 Date: 09/12/2019
Subject Name: Power Electronics Devices and Circuits
Time: 02:30 PM TO 05:00 PM Total Marks: 70

Instructions:

1. Attempt all questions.

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2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.

Q.1 (a) Draw only the symbols of the following: 03

1. DIAC
2. UJT

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3. SCR

(b) Explain the switching characteristics of SCR. 04
(c) Discuss the advantages and limitations of IGBT. 07

Q.2 (a) Write the advantages of LASCR. 03
(b) How SCR can be turned off using natural commutation method? 04

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(c) Explain the UJT as relaxation oscillator with appropriate diagrams. 07

OR

(c) Discuss the protection circuits of SCR under transient conditions. 07

Q.3 (a) Why a freewheeling diode is connected in inductive loaded circuit? 03
(b) Draw the circuit diagram of three phase half wave controlled 04 rectifier with R load.

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(c) Explain the construction, operation and characteristics of GTO. 07

OR

Q.3 (a) Write the applications of dc-dc converters. 03
(b) Explain the operation of type A chopper. 04
(c) Explain the single phase full wave controlled rectifier with RL load 07 with proper waveforms.

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Q.4 (a) What are the performance measures of inverters? 03
(b) Explain the basic principle of operation of cycloconverter. 04
(c) Explain different control strategies for chopper operation. 07

OR

Q.4 (a) Explain step up dc-dc converter with circuit diagram. 03

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(b) Draw only circuit diagram of three phase to single phase 04 cycloconverter.

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Q.5 (a) Draw the block diagram of microcontroller based control of DC 03 drives.
(b) Explain the concept of sinusoidal pulse width modulation. 04
(c) Draw and explain the circuit of battery charger. 07

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OR

Q.5 (a) Explain basic principle of dielectric heating. 03
(b) Differentiate between online and offline UPS systems. 04
(c) Compare various speed control techniques for AC motor drives. 07

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