Download GTU BE/B.Tech 2019 Winter 5th Sem New 2150903 Power Electronics ? I Question Paper

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

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Instructions:

1. Attempt all questions.

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

MARKS

1. (a) In brief discuss pulse transformer and opto-coupler. 03
   (b) Discuss about the two-transistor analogy of thyristor. 04
   

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   (c) Explain series operation of SCR, also derive the expression for static 07
   equalizing resistor.
2. (a) Draw the detail structure and symbol of IGBT. 03
   (b) Draw and explain the static V-I characteristic of SCR. 04
   (c) Explain the programmable UJT as an oscillator for SCR triggering. 07
   

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   OR
   (c) Draw and explain the triggering circuits for series connected SCRs. 07
3. (a) List the applications of AC-DC Converters. 03
   (b) Discuss about the effect of source and load inductance for ac to dc 04
   converter.
   

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   (c) Write a note on single phase semi controlled asymmetrical 07
   converter.
   OR
   (a) Draw circuit diagram and waveform for single phase full wave 03
   rectifier with bridge configuration.
   

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   (b) Derive the equation of output voltage for single phase full- wave 04
   controlled rectifier with RL load:
   (c) Explain full wave fully controlled converter in rectification and 07
   inversion mode.
4. (a) List the application of DC coppers. 03
   

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   (b) Explain the basic principle of DC Chopper. 04
   (c) Explain voltage commutated DC Chopper with necessary waveform 07
   and circuit diagram.
   OR
   (a) Derive an expression of output voltage for boost chopper. 03
   

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   (b) Explain the voltage control methods for DC Chopper. 04
   (c) Explain the principle of Buck-Boost converter in continuous mode 07
   of operation.
5. (a) List the speed control methods for DC motor. 03
   (b) Draw the circuit diagram and waveform for single phase fully 04
   

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   controlled rectifier with RLE load.
   (c) Explain three phase fully controlled converter based dc drive. 07
   OR
   (a) What is regenerative braking. 03
   (b) Briefly discuss about the dual converter. 04
   

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   (c) Explain four quadrant dc-dc converter for DC motor drive. 07

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