7/31/2019 Ee 09 l 10smpc Model Qpaper

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EE 09 L 10: Switched Mode Power Converters

MODEL QUESTION PAPER

Time: 3 hours Maximum Marks: 70

Part A

(Answer all questions: 5 x 2 marks = 10 marks)

1) Draw the block diagram of typical dc-dc converter system

2) Write shortly the effect of square wave pulse switching in dc-ac converter

3) What is meant by ZVS and ZCS

4) List the various classification of Resonant converters

5) Obtain the input-output voltage and current relation as a function of duty ratio for a

Buck-Boost dc-dc converter in continuous conduction mode

PART B(Answer any four questions: 4 x 5 marks = 20 marks)

6) With the help of Suitable waveforms, derive the equation for output ripple voltage for

switched mode Buck converter

7) Explain the Tolerance band control of Current regulated modulation technique adopted

in inverters

8) Explain the programmed harmonic elimination-switching concept in DC to ACconverters

9) Explain the advantages of Resonant converters over corresponding normal converters

10) Explain the role of Static Transfer Switch in UPS operation

11) Explain the working of Cuk converter

Seventh Semester B. Tech. Degree Examination

Electrical and Electronics Engineering

7/31/2019 Ee 09 l 10smpc Model Qpaper

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PART C

(Answer section (i) or section (ii) of each question: 4 x 10 marks = 40 marks)

12) (i) In a step-up converter, the duty ration is adjusted to regulate the output voltageVo at 48 V. The Input voltage varies in a wide range from 12 to 36 V.The maximum

power output is 120 W. For stability reasons, it is required that the converter always

operates in a discontinuous current conduction mode. The switching frequency is 50

kHz. Assuming ideal components and regulating Capacitor very large, calculate the

maximum value of inductance that can be used.

OR

(ii) With the help of relevant derivations and waveforms, analyse the discontinuous

mode of operation with constant output voltage of a dc-dc Buck converter. Also get theboundary condition between continuous and discontinuous conduction for dc-dc Buck

converter

13) (i) With relevant circuit and waveforms explain the effect of blanking signal on

output voltages in PWM inverters. Also compute the change in output voltage due to

above signal

OR

(ii) With a neat circuit diagram and suitable waveforms, explain the Bi-polar

voltage switching adopted for single-phase switched mode inverter.

14) (i) Using suitable waveforms, explain the working of Series Loaded resonant dc-dc

converter in discontinuous conduction mode for switching frequency (s) less than half

the resonant frequency (o)

OR

(ii) Derive the inductor current and capacitor voltage equation of Series resonantconverter circuit with a capacitor parallel Load

15) (i) Explain the working of double ended forward converter with electrical isolation

OR

(ii) Explain the working of Fly back converter and obtain its voltage, current and

flux waveforms