[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, ΔB=0.1T, J=3A/mm2, Dmax=0.45, ɳ =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