Power Electronics

Unit 1

Power Semiconductor Switches: Controllable switch waveforms and power loss in clamped inductive switching circuit - Desirable characteristics in a switch - Temperature rise and use of heat-sinks. Structure, operation, steady state and switching characteristics, turning on and off, gate drive, rating and protection for power MOSFETs, IGBTs and Thyristors, Phase controlled converters: Single phase and three phase converters in CCM - Performance parameters – DCM operation - Inverter mode of operation -- Effect of source inductance - Gate triggering circuits - Single phase dual converter. Non-sinusoidal analysis.

Unit 2

Single phase AC switching controllers with R and R-L loads - Thyristor controlled inductor - Three phase applications of switching control. Choppers: Applications. Step-down chopper with R load with L filter - Transient and steady state operations - Average and ripple load currents- Back emf loads - CCM and DCM - Input filter. Step-up chopper: Analysis, with CCM – Effect of frequency on DCM/CCM - Two Quadrant chopper with static changeover. High power factor front end converter.

Unit 3

Inverters: Applications – Half bridge inverter – Full bridge inverter with square wave and single pulse width modulated operations – Sine PWM scheme: Single phase full bridge with unipolar voltage switching, performance parameters, AC and DC side currents - Sinusoidal pulse width modulation for three phase inverters, Expressions for phase to neutral voltages – Current regulated modulation - Rectifier mode of operation of inverters - AC side filters - Schemes to generate triangular carrier and sinusoidal reference - Introduction to Space vector pulse width modulation – Multilevel inverter and UPS.