**[Total Time: 3 Hours]****[Total Marks: 80 M]Note:(1) Question No. 1 is compulsory.(2) Answer any three from the remaining five questions.(3) Assume suitable data if necessary and justify the same**.

1.(a) What is a dc-dc voltage regulator? Give a comparison between linear power supply and switched mode power supply. **[5M]**

(b) Explain the difference between ZVS and ZCS resonant dc to dc converter with neat circuit diagrams. **[5M]**

(c) What is the need for multilevel inverter? What are its applications? **[5M]**

(d) Discuss any two current control methods in dc to dc converter. **[5M]**

2.(a) Draw the diagram of a Boost converter. Find the expression for control to output transfer function of an Ideal Boost converter in CCM using state space averaging technique and small signal analysis.** [20M]**

3.With a neat diagram of a Flyback dc to dc converter, design a transformer for the following specifications: input voltage(Vd)=24V, Vo=5V Po=30W, fs=40kHz, L1=1mH. Assume Kw=0.4, Î”B=0.1T, J=3A/mm^{2}, Dmax=0.45, É³ =80%, VD=1.5. Assume any other data if needed and state the same. **[20M]**

4.(a) With neat diagrams explain Push Pull dc to dc converter and derive the voltage ratio** [10M]**

(b) With a neat block diagram write short notes on DC Link voltage control loop and the design of compensator in current mode control of grid connected inverter. **[10M]**

5.(a) Explain phase shifted and level shifted PWM technique used in Multilevel inverters **[10M]**

(b) A BUCK- Converter has an input voltage of Edc=14V. The required average output voltage is Eo=6V and the peak to peak output ripple voltage is 15mV. The switching frequency is 30kHz. If the peak to peak ripple current of inductor is limited to 0.6 A. Determine: (a) the duty cycle, (b) the filter inductance L, and (c) the filter capacitor C.** [10M]**

6.(a) Draw the steady state characteristics of Series Loaded Resonant dc to dc converter and explain its features. **[10M]**

(b) Explain any one of the following **[10M]**

(i) Thermal management and EMI issues in converters.

(ii) Solar PV power conditioning unit.

(iii) Modelling of Grid connected inverter with LC filter

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