University of Mumbai 2007-6th Sem B.E Electrical and Electronics Engineering Power Electronics - Question Paper
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Con/5530-07. (REVISED COURSE) CD-6523
N.B. : (1) Question No. 1 is compulsory. MtiUltfoh
(2) Atterrpt any four questions from remainings questions.
(3) Assume suitable data wherever necessary.
1. (a) Explain the following ratings of SCR 10
(i) I21 rating
(ii) di/dt rating
(iii) Holding and latching current
(iv) Peak inverse voltage
(v) dv/dt rating.
(b) (i) Compare properties of power BJT, MOSFET and IGBT from application 5 point of view.
(ii) Explain protection methods used for over current, overvoltage, dv/dt and 5 di/ct.
2. (a) xDraw a three phase full bridge inverter using SCR and its waveform for 120 10
conduction and 180 conduction. Explain operation in brief.
(b) Describe different commutation techniques used in case of SCR. 10
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3. (a) Draw and explain circuit diagram for synchronized UJT triggering with associated 10
waveforms. Also explain necessity for synchronization.
(b) Explain with the help of neat diagram, construction and operating principle 10 of JGBT.
4. (a) Sketch lV characteristics of typical TRIAC. Explain its four quadrant operation 10
and compare it with SCR,
(b) What are different methods to reduce harmonics in 3> inverter ? Explain briefly. 10
5. (a) Draw circuit diagram of single phase A.C. regulator for R-L load using phase 10
control. Give waveform of input, output voltage and currents.
(b) Derive the expressions for RMS value of output voltage and current for the 10 above circuit.
6. (a) Draw circuit diagram of multiple pufse PWM single phase inverter and explain 10 its working with suitable waveforms. Give advantages of PWM Technique.
(b) Explain basic operation of SCR with suitable circuit diagram. Also write difference 10 between SCR and BJT.
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| Earning: Approval pending. |
