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APJ ABDUL KALAM TECHNOLOGICAL UNIVERSITY
FIRST SEMESTER M. TECH DEGREE EXAMINATION, DECEMBER 2018
Electrical and Electronics Engineering
Stream(s): Control Systems &Electrical Mach ines

01 EE6303 Power Electronics Circuits

Answer any twofull questions from each part
Limit answers to the required points.

Max. Marks: 60 Duration: 3 hours
PART A

1. a. Explain the dynamic characteristics of MOSFET with the help of Voltage and (3)

current waveforms
b. What are the characteristic features of an ideal switch (3)
c. Describe different configurations of switches using selniconductor devices (3)

2. a. Explain the analysis of a single phase ac voltage controller with RL load (5)
b. Explain the conduction and switching losses in MOSFET (4)
3. 2. Explain the static and dynamic characterisiics of था IGBT (6)

b. The off state voltage is V and on state current is I, the switching frequency is f, (3)
Obtain the expression for the average switching power loss, Instantaneous peak power
loss in the switch. Assume the switch is ideal

PART B

4. ೩ Explain the boost converter and obtain the condition for continuous inductor (6) current
and capacitor voltage

b. A boost converter has an input voltage of 5V,the average output voltage is 15V (3)
and the average load current is O,5A.The switching frequency is 25kHz.If L=150gH
and C=220gF,Determine the duty cycle, critical values of Land C

5. a. Describe the working of a fly back converter with neat circuit diagram and wave (5)

forms.
b. Distinguish between isolated DC-DC converters. (4)

6. a. In a Cuk converter operating at 50kHz, L1=L2=1mH and Cl=5gF.The output (3)
capacitor is sufficiently large to yield an essentially constant output voltage. Input voltage
is TOV and output VO is regulated to be constant at 5V.It is supplyingSW to a load.
Assume ideal components and constant voltage across CI, Calculate the percentage error
in voltage.