EEE 405: Power Electronics Supplementary Examination

Supplementary sitting of the power electronics unit. Defines power electronics, the snubber circuit in a thyristor connection, the commutation circuit and the regulated power supply, then the firing circuit of a thyristor, the three reasons a freewheeling diode is needed in a bridge converter, ripple factor and its importance, the physical significance of voltage regulation, and the transistor against the silicon controlled rectifier as a switch. Works a full-wave rectifier on a centre-tapped transformer whose diodes carry fifteen ohms of forward resistance into a one and a half kilo-ohm load from a 141 sine omega t secondary: average load current, ripple factor, direct-current output power, alternating-current input power and rectifier efficiency. Closes on the inverter, cycloconverter and step-down chopper with their industrial applications, the two methods of turning on an SCR, harmonic content at input and output, computer simulation of a power converter system, the chopper waveform used to control the speed of a direct-current drive, current source and voltage source inverters, the conventional on-line uninterruptible power supply, the boost converter, and a single-phase full-wave semiconverter charging a 24 volt battery through a 5 ohm limit resistor at a firing angle of forty-five degrees.