APJ ABDUL KALAM TECHNOLOGICAL UNIVERSITY
SECOND SEMESTER M.TECH DEGREE EXAMINATION, MAY 2016

Electrical and Electronics Engineering

(Power Control and Drives)
01EE6502 Design Principles of Power Converters
Max. Marks: 60 Duration: 3 Hours

Answer any twofull questions from each part

Part A

1 Design an inductor for buck converter configuration with the following specifications:
Output voltage, Vo = 3.3V
Output current, 10 ಎ 54,
Switching frequency, fs = 20 kHz
Input voltage, 10\/+10%8
Diode voltage drop, IV
Operating flux density,
Window utilization factor, Ku=0.29
Current density, 15433 A/cm2 (9)

2. Design a heat sink with forced convection, for a three phase sinusoidal PWM inverter
delivering a load current of 175A (peak) at 0.8 pf. The dc bus voltage is 600V. Switching

frequency—2 kHz.

The datasheet parameters of the dual IGBT module are as follows:
Tjmax=125 °C, =50°C
IGBT saturation voltage drop ட 1754-1 .4V
Total Turn on and turn off switching energy per pulse =58 mJ Forward
voltage drop of the diode @175A — 1 .45\/
Diode peak recovery current =300A
Diode reverse recovery time 102nS per
Roje(Q)=0.085°C/W IGBT module per
Roje(D)=0.15°C/W ற 1/2 module
Contact thermal resistance Ro,.r 0.02 °C/W per 1/2 module with thermal grease
Cooling fan specifications:
Size 60mm X60mm
Airflow = 12.8CFM (9)