POWER ELECTRONICS JNTU previous years question papers

POWER ELECTRONICS JNTU previous years question papers

 Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks

1. Explain in detail various voltage ratings and current ratings of a thyristor. [16]

2. Explain the operation of a singe phase half wave converter for R-load with neat circuit diagram and necessary waveforms. Also derive the output average voltage and current for a = 300. [12+4]

3. A three phase, six pulse fully controlled converter is connected to three phase ac supply of 440V and 50Hz and operates with a firing angle of p/5 radians. The load current is maintained constant at 5 Amps and load voltage is 440V. Calculate load resistance, source inductance and overlap angle. [4+6+6]

4. A single phase full wave ac voltage controller has a resistance load of
(a) 10 ohms and
(b) 5 ohms.
The input ac voltage is 230V, 50Hz. For a delay angle of 900, determine the rms load voltage, rms load current, rms thyristor current and input power factor for above two loads. [8+8]

5. Explain the operation of single phase bridge type cyclo converter when fed form 230V, 50Hz source and controlling power to resistive load with the help of neat circuit diagram and output voltage and current waveforms for a = 450 and a =1600 for f0 = 1/5 fs. [4+6+6]

6. Explain the operation of class -C commutation circuit and also give its application with neat circuit. [10+4+2]

7. Single phase half bridge inverter has a resistive load of R = 3 ohms and dc input voltage Edc = 50V. Calculate
(a) rms output voltage at fundamental frequency E1
(b) the output power
(c) average and peak current of each thyristor [6+4+6]

8. Calculate the output frequency of a series inverter circuit with following parameters,
L = 10mH, C = 0.1 µF, R = 400 ohms, toff = 0.2 msec. Also determine the attenuation factor.

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