Download PTU B-Tech EEE 2020 Dec 6th Sem 72789 Power Electronics Question Paper

Download PTU (I.K.Gujral Punjab Technical University (IKGPTU)) B-Tech (Bachelor of Technology) (EEE)- Electrical And Electronics Engineering 2020 December 6th Sem 72789 Power Electronics Previous Question Paper

Roll No.
Total No. of Pages : 02
Total No. of Questions : 18
B.Tech. (E E) PT (Sem.?6)
POWER ELECTRONICS
Subject Code : BTEE-504
M.Code : 72789
Time : 3 Hrs. Max. Marks : 60
INST RUCT IONS T O CANDIDAT ES :
1 .
SECT ION-A is COMPULSORY cons is ting of TEN questions carrying TWO marks
each.
2 .
SECT ION-B c ontains F IVE questions c arrying FIVE marks eac h and s tud ents
have to atte mpt any FOUR q ues tions.
3 .
SECT ION-C contains THREE questions carrying T EN marks e ach and s tudents
have to atte mpt any T WO questio ns.
SECTION-A
Answer briefly :
1.
Draw the Symbol and characteristics of TRIAC.
2.
Explain the need of snubber circuit.
3.
Differentiate between forced and natural commutation.
4.
Compare voltage and current source inverters.
5.
Explain the importance of phase angle control.
6.
Which of the DC choppers is more commonly employed and why?
7.
Explain the operating principle of an Inverter.
8.
List the advantages and disadvantages of cyclo converters.
9.
What do you mean by harmonics? Explain.
10.
Differentiate between AC link chopper and DC chopper.
1 | M-72789
(S2)-534

---

SECTION-B
11.
Define string efficiency for two series/parallel connected SCRs. Show that the string
efficiency for two series connected SCRs is usually less than one.
12.
A step up chopper has input voltage of 220 V and output voltage of 660V. If the
conducting time of the chopper is 100 micro second, compute the pulse width of the
output voltage. In case output voltage pulse width is halved for constant frequency
operation, find the average value of the new output voltage.
13.
Explain the operating principle of single phase to single-phase step down cyclo converter.
14.
Discuss, with the relevant waveforms, Class B type of commutation employed for
thyristor circuits.
15.
Discuss the various voltage control methods in single phase inverters in detail.
SECTION-C
16.
Explain the static VI characteristics of a thyristor. List various triggering methods of the
thyristor and explain gate triggering and dv/dt triggering.
17.
a) What is the purpose of a chopper? Discuss in detail the basic principle of operation of
choppers.
b) Why is Dual converter required? Explain the working of an ideal dual converter.
18.
Discuss :
a) Line Commutation
b) Series inverter
NOTE : Disclosure of Identity by writing Mobile No. or Making of passing request on any
page of Answer Sheet will lead to UMC against the Student.
2 | M-72789
(S2)-534

---