Semester : SEMESTER 1
Subject : Power Converter Circuits
Year : 2015
Term : DECEMBER
Branch : POWER CONTROL AND DRIVES
Scheme : 2015 Full Time
Course Code : 01 EE 6501
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PART-B (Module ॥॥ and IV)
4 a. With neat waveforms explain the working of fully controlled converter (5) for
RL toad with a=60°
0. Athree phase full converter is operated from a 30, 230۷, 60 Hz supply. The (4) load
is highly inductive and the average load current IS * | 150A with negligible ripple
content. If the delay angle js TK/3, determine the ratings of thyristor.
5 Explain the operation of Boost converter with neat circuit diagram and (5) relevant
waveforms. Derive the expressions for the average output voltage.
6 a. A buck converter has an input voltage, Vs=15 V. The required average (6) output
voltage Va= 15 V and the peak to peak output ripple voltage is 10 mV. The
switching frequency is 20 KHz. The peak to peak ripple current of inductor is
limited to 0.5 A. Determine i) the duty cycle ii) the filter inductance iii) the filter
capacitance iv) the critical values of Land C.
b. Explain the inversion mode of operation of rectifier with relevant (3) waveforms.
PART-C (Module V and VI)
7 a. The average output voltage ofa flyback circuit is 24 V at a resistive load of (8)
R=.8 Q. The duty ratio is 50 % and the switching frequency is 1KHz.the on stage
voltage drops of transistor and diode are 1.2 Vand 0.7 V respectively.
The turns ratio of transformer 15 a=Ns/Np=0.25, Determine
i) The efficiency ii) Average rms and peak
transistor currents.
0. Explain the working of a half bridge converter with relevant waveforms (4) 8 Explain
the operation of 3 phase inverter with 180° conduction with circuit (12) neat
diagram. Draw the thyristor currents, Phase voltage and Line voltage waveforms.
9 a. Explain the methods of harmonic elimination in PWM inverters (6) 0. Write short notes
on Push-pull 60-60 converter (6)