Power Electronics

Power Semiconductor Devices Devices and Commutation Circuits Single Phase Half Controlled Converters Single Phase Fully Controllers Converters Three Phase Line Commutated Converters AC Voltage Controllers and Cyclo Converters Choppers Inverters Thyristors - Silicon Controlled Rectifiers (SCR's) - BJT - Power MOSFET - Power IGBT and their characteristics and other thyristors - Basic theory of operation of SCR - Static characteristics - Turn-on and turn-off methods - Dynamic characteristics of SCR - Turn-on the Turn-off times - Salient points. Two transistor analogy - SCR - UJT firing circuit - Series and parallel connections of SCR's - Snubber circuit details - Specifications and ratings of SCR's, BJT, IGBT - Numerical problems - Line commutations and forced commutation circuits. Phase control technique - Single phase Line commutated converters - Mid point and Bridge connections - Half controlled converters with Resistive, RL loads and RLE load - Derivation of average load voltage and current - Active and reactive power inputs to the converters without and with free wheeling diode - Numerical problems. Fully controlled converters, Mid point and Bridge connections with Resistive, RL loads and RLE load - Derivation of average load voltage and current - Line commutated inverters - Active and Reactive power inputs to the converters without and with free wheeling diode, Effect of source inductance - Derivation of load voltage and current - Numerical problems. Three phase converters - Three pulse and six pulse converters - Mid point and bridge connections, Average load voltage with R and RL loads - Effect of source inductance - Dual converters (both single phase and three phase) - Waveforms - Numerical problems. AC voltage controllers - Single phase two SCR's in anti parallel - With R and RL loads - Modes of operation of Triac - Triac with R and RL loads - Derivation of RMS load voltage, current and power factor. Waveforms - Firing circuits - Numerical problems - Cyclo converters - Single phase mid point cyclo converters with resistive and inductive load Bridge configuration of single phase cyclo converter - Waveforms. Choppers - Time ratio control and current limit control strategies - Step down choppers-Derivation of load voltage and currents with R, RL and RLE loads - Step up chopper - Load voltage expression. Morgan's chopper, Jones chopper and Oscillation chopper (Principle of operation only)- Waveforms-AC chopper, Problems. Inverters - Single phase inverter - Basic series inverter - Basic parallel capacitor inver ter-Bridge inverter-Waveforms- Simple forced commutation circuits for bridge inverters - McMurray and McMurray Bedford inverters-Voltage control techniques for inverters-Pulse width modulation techniques-Numerical problems.