Download PTU B.Tech 2020 March EE 6th Sem Power Electronics Question Paper

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Roll No. ‘ ‘ ‘ ‘ H ‘ ‘ ‘ H ‘ Total No. of Pages : 02

Total No. of Questions : 09

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B.Tech. (EE) PT (Sem.-6)

POWER ELECTRONICS

Subject Code : BTEE-504

M.Code : 72789

Time : 3 Hrs. Max. Marks : 60

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INSTRUCTIONS TO CANDIDATES :

1. SECTION-A is COMPULSORY consisting of TEN questions carrying TWO marks each.
2. SECTION-B contains FIVE questions carrying FIVE marks each and students have to attempt any FOUR questions.
3. SECTION-C contains THREE questions carrying TEN marks each and students have to attempt any TWO questions.

SECTION-A

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1. Answer briefly :
   1. Define latching and holding current of a thyristor.
   2. What do you understand by PIV rating of a thyristor?
   3. What is a snubber and why is it used?
   4. What is phase control in a thyristor?
   5. What is the purpose of a chopper?

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   6. What is feedback diode and where is it used?
   7. What is di/dt and dv/dt ratings of a thyristor?
   8. Why and where the zener diode is used for thyristors?
   9. Can a converter be used as an Inverter? If yes how and if no why?
   10. Differentiate between SUS and SCS.

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SECTION-B

2. Discuss the transient characteristics of a thyristor and explain various terms used in it.
3. Differentiate between line and load commutations of a thyristor.

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4. Explain the operation of a current commutated chopper with the help of its waveforms.
5. Explain the operation of a single-phase bridge inverter with the help of circuit diagram and associated waveforms.
6. Discuss the PWM control for reduction of harmonics in the inverter output voltage.

SECTION-C

7. Discuss the need of static and dynamic equalization for the series and parallel operation of thyristors? Also discuss various protection circuits used for thyristors.

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8. Draw the circuit diagram of a three-phase bridge converter and explain its operation with the help of various waveforms.
9. Write short note on any of two :
   1. Single phase bridge cyclo-converter.
   2. Modified Mc-Murray Half bridge Inverter.
   3. Classification of choppers.

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NOTE : Disclosure of Identity by writing Mobile No. or Making of passing request on any page of Answer Sheet will lead to UMC against the Student.

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