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

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Subject Code: 2150903

GUJARAT TECHNOLOGICAL UNIVERSITY

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Instructions:

1. Attempt all questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.

1. (a) Explain DIAC with construction and characteristics. [03]
   

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   (b) Explain IGBT with construction and characteristics. [04]
   (c) Enlist various commutation circuit of SCR. Explain any one voltage commutation circuit. [07]
2. (a) What is snubber circuit? Explain working and application for same. [03]
   (b) Explain UJT relaxation oscillator. [04]
   (c) Explain working of series connected SCRs. [07]
   

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   OR
   (c) Explain working of parallel connected SCRs. [07]
3. (a) Explain duty cycle and chopper frequency. [03]
   (b) Explain harmonics in power electronic circuit and enlist harmonic sources. [04]
   (c) Explain cuk converter in detail. [07]
   

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   OR
   (c) What is pulse transformer and opto-coupler? [07]
4. (a) Explain significance of freewheeling diode in-controlled rectifiers. [03]
   (b) Draw necessary waveforms and explain working of single phase full controlled rectifier circuit with R-L load. [04]
   (c) What do you mean by continues conduction mode and discontinues conduction mode of operation in choppers. [07]

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5. (a) Explain jone’s chopper in short. [03]
   (b) Write brief note on buck-booest converter. [04]
   (c) OR Give difference between voltage and current commutated choppers. [07]
6. (a) Draw and explain RC triggering circuit for SCR. [03]
   (b) Explain 3 phase full wave rectifier with R load. [04]
   

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   (c) Explain basic-principles for speed control of DC motor. [07]
7. (a) Explain the principle of motoring control of separately exited DC motor with phase controlled converter. [03]
   (b) Explain single phase full converter drive feeding separately exited dc motor for continuous conduction mode. [04]
   (c) OR What is regenerative braking? Explain w.r.t. DC motor speed control. [07]
8. (b) Write short note on single phase dual converter. [04]
   

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   (c) Explain operation of four quadrant DC motor using chopper circuit. [07]

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