Jawaharlal Nehru Technological University Hyderabad 2009-1st Sem M.Tech Electrical & Electronics Engineering Code no:A5402,ester Regular s,– ANALYSIS OF POWER ELECTRONIC CONVERTERS - Question

Here i am submitting M.Tech. I Semester Regular Examinations, March – 2009
ANALYSIS OF POWER ELECTRONIC CONVERTERS ques. paper in the provided beneath attachment.

Code No. A5402

JAWAHARLAL NEHRU TECHNOLOGY UNIVERSITY, HYDERABAD M.Tech. I Semester Regular Examinations, March - 2009 ANALYSIS OF POWER ELECTRONIC CONVERTERS (Common to Power Electronics & Electric Drives, Power Electronics, Electrical Power Engineering and Power Engineering & Energy Systems)

Time: 3 hours    Max. Marks.60

Answer any Five questions All questions carry equal marks

1.a) Explain about synchronous tap changers. Give the applications. b) The single-phase full wave controller supplies an RL load. The input rms voltage is Vs = 120 V, 60 Hz. The load is L = 6.5 mH and R = 2.5 Q. The delay angles of thyristors are equal a₁ = a₂ = ⁿ/₂. Determine:

i)    The conduction angle of thyristor T1 Si

ii)    The rms thyristor current IR

iii)    The input power factor.

2a) The three phase unidirectional controller supplies a Y-connected resistive load with R = 2.5 Q and the line-to-line input voltage is 208 V (rms), 60 Hz. If the desired output power is P0 = 12 KW. Calculate:

a)    the delay angle, a

b)    the rms output phase voltage V0, and

c)    the input PF

b) What are the advantages and disadvantages of ac voltage controllers?

3.a)    What is a cyclo converter? Explain the principle and operation of singlephase cyclo converter with neat diagram draw the waveforms.

b) What are the effects of load inductance on the performance of cyclo converters?

4.    a) What is pulse-width modulation control of converts and what are the

applications?

b) A single phase full converter is connected to RLE load. The source voltage is 230 V, 50 Hz. The average load current of 10 A is continuous over the working range. For R = 0.4 Q and L = 2 mH, compute firing angle delay for E = 120 V.

5.    For a 3 phase full converter, sketch the input voltage waveforms for Vab, Vac, Vbc etc and voltage variation across any one thyristor for one complete cycle for a firing angle delay of:

a)    60⁰ and

b)    120⁰

Code No. A5402

6.    a) How can the input current of the rectifier-fed boost converter be made

sinusoidal and in phase with the input voltage?

b) The buck regulator has an input voltage Vs=15 V. The required average out put voltage Va=5 V and the peak-to-peak out put ripple voltage is 10 mV. The switching frequency is 20 KHz. The peak-to-peak ripple current of inductor is limited to 0.5A. Determine:

i)    the duty cycle K,

ii)    the critical values of L and C.

7.    Explain the voltage control of single phase inverters with the help of waveforms.

8.a)    What are the techniques for harmonic reductions?

b) Explain about the back and boost inverter and give the advantages and applications.

Attachment: jawaharlal-nehru-technological-university-hyderabad-2009-m-tech-electrical--amp--electronics-engineering-47174-1.pdf

Earning:   Approval pending.