Power Semiconductor Devices and Commutation Circuits: Thyristors – Silicon Controlled Rectifiers (SCR’s), BJT, power MOSFET, power IGBT,GTO and their characteristics. Basic operation of SCR, Static characteristics, turn on and turn off methods, Dynamic characteristics of SCR, two transistor analogy, Protection and ratings of SCR’s, series and parallel connections of SCR’s, snubber circuit, line commutation and forced commutation circuits.
Single Phase Controlled Converters: Phase control technique, single phase line commutated converters, half wave rectifier, midpoint and bridge connections, half controlled converters and fully controlled converters with R, RL loads and RLE load, without and with freewheeling diode. Derivation of average load voltage and current, performance parameters, effect of source inductance.
Three Phase Line Commutated Converters: Three pulse and six pulse conversion, average load voltage with R and RL loads, effect of source inductance, dual converters (single phase and three phase). AC Voltage Controllers: AC voltage controllers, single phase two SCR’s in anti parallel with R and RL loads, Triac with R and RL loads, derivation of RMS load voltage, current and input power factor.
Cyclo Converters: Single phase midpoint cyclo-converters with resistive and inductive load (principle of operation only), bridge configuration of single phase cyclo-converter, principle of operation and waveforms. Choppers: Time ratio control and current limit control strategies, step down chopper, step up chopper and step up/down chopper, derivation of load voltage expression. Morgan’s chopper and Jone’s chopper.
Inverters: Basic series inverter, basic parallel inverter, single phase bridge inverter, waveforms, Three phase inverters (120 and 180 operation), voltage control techniques for inverters-pulse width modulation techniques.