August
T05/TES102/EE/20150821
2015
Power Electronics -2
Instructions:
MARKS-80
Time: 3 Hrs
1. All questions are compulsory.
2. “Long Answer type Question (LAQ)” is a supply type
question of 15 marks which required a typical answer of about
60-80 lines in bout 32-40 minutes.
3. “Sort Answer type Question (SAQ)” is a supply type question
of 5 marks which required a typical answer of about 15-20 lines
in bout 08-10 minutes.
4. Figures to the right indicate marks allotted to the questions.
5. Assume suitable data if necessary
6. Use a nonprogrammable type of scientific calculator is
allowed
Marks
SECTION-A
Q.1 A) Draw a neat diagram parallel inverter employing feedback
diode.
08
B) Explain the working of inverter with help of voltage and current
waveform. What care should be taken to avoid commutation
failure?
OR
Q.1 Explain MC Marry Bedford Commutated Half-Bridge Inverter with
diagram. Mention Merits and Demerits.
07
Q.2 A) Compare between PWM control and Variable frequency control
5
B) Explain Step Down chopper. Explain Analysis of Step Down
Chopper.
OR
Q.2 Design the Jones Chopper for optimum frequency consideration to
meet the following specifications Where Source voltage Edc=200V,
Load current, Io=50A, Tq=200µs.solution must based on
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(i)
(ii)
(iii)
(iv)
(v)
Selection of commutating capacitor C.
(ii)Selection of inductance L1.
Selection of SCR T1(main SCR).(iv)Selection of
auxiliary SCT T2
Selection of diode D1.
SCR dynamic characteristics with Main SCR T1 &
Main SCR T2.
15
15
Q.3 A step down (type A) chopper feeds a resistive load of 10 ohm from
100 V dc supply. Calculate the duty cycle required so that the
average power dissipation in the load is 100W.
5
Q.4 What is Capacitance? A load commutated chopper, fed from a 230
V dc. Source has a constant load current of 50 A. For a duty cycle
of 0.4 and a chopping frequency of 2kHz, calculate
(a) The value of commutating capacitance.
(b) Average output voltage.
(c) Circuit turn-off time for one SCR pair
(d) Total communication interval.
5
SECTION-B
Q.5 A) What do understand by Power-Electronics? Mention the
application area of power electronics. What do you know about
thyristor family?
B) Explain the working of a simple diode with V-I characteristics.
10
5
OR
Q.5 Explain SUS (Silicon Unilateral Switch) with diagram. Explain V-I
characteristics of SUS. Mention Application and disadvantage for
SUS?
15
Q.6 How the Thyristor are mounting in circuit? How the Thyristor help
in electronic world? What is the precaution need to take while
dealing with Thyristor?
15
OR
Q.6 What is Power Transistor? Mention the points
(A) Symbol and Application and Merits of BJT.
(B) Symbol and Application and Merits of MOSFET.
(C) Symbol and Application and Merits of IGBT?
15
Q.7 Explain the Dynamic characteristic during Turn-off in detail with
wave form?
5
Q.8 Explain different state of TRAIC operation? Mention the
disadvantage of TRIAC.
Computer Generated Random Question Paper dated: 17-07-2015 12:37:56
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