Download GTU B.Tech 2020 Winter 7th Sem 171002 Power Electronics Question Paper

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GUJARAT TECHNOLOGICAL UNIVERSITY
BE- SEMESTER-VII (OLD) EXAMINATION — WINTER 2020

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Instructions:

1. Attempt any FOUR questions out of EIGHT questions.

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

1. (a) Explain the principle of operation of SCR with (i) Device structure (ii) Characteristics. [07]
   (b) Explain the construction and characteristics of IGBT. [07]
2. (a) What is the need of commutation in SCR circuits? Explain the class-B commutation in detail. [07]
   

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   (b) Draw and explain the structure of power MOSFET. Also explain principle of operation and I-V characteristics of power MOSFET [07]
3. (a) What are the various thyristor ratings? [07]
   (b) What is GTO ? Draw and Explain GTO structures . Also explain GTO Turn off mechanism with desired equation and figures. [07]
4. (a) Discuss the two transistor model of a Thyristor. Derive an expression for the anode current and henceforth discuss the turn ON mechanism of a Thyristor. [07]
   (b) Explain series and parallel operations of thyristor? [07]

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5. (a) What is chopper? Describe the working of Type C chopper. [07]
   (b) Explain R and RC firing circuit of SCR. [07]
6. (a) Explain principle of operation of step-down DC chopper. [07]
   (b) Write short note on three phase inverter. [07]
7. (a) Write short note on RF heating: [07]
   

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   (b) Write short note on Uninterruptible Power Supply. [07]
8. (a) Explain the circuit diagram and working of single phase semi converter with freewheeling diode: [07]
   (b) Write short notes on dielectric heating and induction heating [07]