T.E. (E & TC Engineering) Power device and circuit previous year question paper

 T.E. (E & TC Engineering)

T.E. (E & TC Engineering)

POWER device AND CIRCUIT 

(Semester-II) 

Q1) 

a) with wavefrom techniques in inverter? Explain Multiple PWM technique waveforms. 

b) Give the classification of inverters?Draw Three Phase voltage source inverter for balanced star R load? [5]

c) Explain working of single phase full bridge inverter for R load with inputs & output waveforms. Derive an expression for rms o/p voltage. 

 OR

Q2) a) Draw a three phase inverter for balanced star R load? Explain its operation of 120° mode with gate signals & output waveforms.[12]

Q3) a) Explain with neat diagram the operation of 4 quadrant with de motor as a load. in

[8]

b) Explain operation of step up chopper with circuit diagram and derive an expression for its o/p voltage: Vo=- Vs (1-D) where D is duty cycle.[6]

c) A step down DC chopper has a resistive load of R = 15 2 and input

voltage Ede=200V. The chopper frequency is IKHz. If the duty cycle 141

is 50%, determine

i) Average output voltage ii) rms output voltage

OR

Q4) 

a) A step up chopper is used to deliver load voltage is 660V from 220V DC source. If the blocking period of thyristor is 500μs, compute the turn on time. [4]

b) What are various types of choppers? Explain chopper with circuit diagram.(8)

c) Explain with block schematic working of SMPS.  [6]

Q5) 

a) What are different over voltage protection techniques in electronics? Explain any one in detail.(6)

b) Explain ZCS resonant converter with circuit & waveforms.(4)

c) For a thyristor, Maximum junction temperature is 110°C. The therm resistances are 0.16, 0.08°C/W. For heat sink temparature 60°C. calculate total average power loss in thryistor-sink combination.

  OR

Q6) 

a) What is EMI? Explain various sources & minimizing techniques of EMI. (7)

 b) Compare resonant converters ZVS with ZCS.(4)

C) Draw & explain single phase full wave ac load with following waveforms: [5] 

c) Explain with neat diagram working of snubber circuit used in power devices.[5]

Q7)

 a) Explain with neat diagram BLDC drive.

b) Explain operation of On-line & off-line UPS with block schematic [12]

OR

Q8) 

a) Explain with neat diagram variable voltage type three phase induction motor drive.[5]

b) Explain with diagram architecture of EVs battery charger. (8)

i) Gate signals for both SCRS

ii) Output rms voltage & current

iii) Voltage waveform across first SCR