Power Semiconductor DevicesThyristors - 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.Devices and Commutation CircuitsTwo 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.Single Phase Half Controlled ConvertersPhase 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.Single Phase Fully Controllers ConvertersFully 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 Line Commutated ConvertersThree 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 and Cyclo Converters 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 (Principle of operation only) - Bridge configuration of single phase cyclo converter (Principle of operation only) - Waveforms.ChoppersChoppers - 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.InvertersInverters - Single phase inverter - Basic series inverter - Basic parallel capacitor inverter-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.Draw the circuit diagram and explain the operation of step down chopper with the help of waveforms. Unsolved Examples 1. In a DC chopper the average load current is 30 A. The chopping frequency is 250 Hz and supply voltage is 110 volts .

Title | : | Power Electronics |

Author | : | J.S.Chitode |

Publisher | : | Technical Publications - 2009-01-01 |

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