Hall Ticket No Question Paper Code: BPE002
INSTITUTE OF AERONAUTICAL ENGINEERING
(Autonomous)
M.Tech I Semester End Examinations (Regular) February, 2017
Regulation: IARE-R16
AC TO DC CONVERTERS
(Power Electronics and Electrical Drives
Time: 3 Hours Max Marks: 70
Answer ONE Question from each Unit
All Questions Carry Equal Marks
All parts of the question must be answered in one place only
UNIT I
1. Explain the V-I characteristics of thyristor circuit.
The capacitance of reverse biased junction J2 in a thyristor is Cj2=20pf and can be assumed
to be independent of offset voltage. The limiting value of the charging current to turn on the
thyristor is 16mA. Determine the critical value of dv/dt.
2. Discuss the process of commutation and explain the different commutation techniques used for
the thyristors along with circuit diagram and waveforms.
Describe the basic structure of MOS controlled thyristor and give its equivalent circuit.
UNIT II
3. Explain the operation of three phase full converters.
Write a short note on shunt capacitor compensation.
4. A three phase full converter is operated from a three phase star connected 208V,60HZ supply and the
load resistance is R=10
. If it is required to obtain an average output voltage of 50% of the maximum
possible output voltage, calculate
i. the delay angle
ii. the RMS and output currents.
iii. the average and RMS thyristor currents.
iv. the rectification efficiency
v. TUF
vi. input PF
UNIT III
5. Explain the operation of AC voltage controller with resistive, inductive and EMF loads along
with neat circuit diagram, input and output waveforms.
Discuss about the application of single phase AC voltage controller and compare the advantages
and disadvantages of single phase AC voltage controller
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6. A single phase unidirectional AC voltage controller is connected with a load of R=20
with an
input voltage of 230V, 50 HZ. If the firing angle of thyristor is 900. Determine,
i. RMS value of output voltage
ii. Power delivered to load.
Explain the operation of cyclo-inverters in detail.
UNIT IV
7. Explain the operation of single phase half wave converter drives.
Write a short notes on,
i. 3-phase half wave converter drives.
ii. 3-phase full converter drives.
8. Explain the operation of single phase series converter with neat diagrams.
Derive the expressions for performance factors of single phase fully converted bridge converter.
i. Input displacement factor
ii. Input power factor
iii. Voltage ripple factor.
UNIT V
9. Explain about the step down DC to DC convertes with resistive and inductive loads with neat
circuit diagrams and waveforms.
Explain the working of current commutated chopper with the aid of diagram waveforms.
10. Discuss the operation following power electronics converters along with circuit and waveforms.
i. BUCK and BOOST regulators.
ii. CUK regulators and multi output boost. converters.
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