ECE – 404 POWER ELECTRONICS

Rectifying Devices: The diode, the thyristor - thyristor gating requirements, requirements of firing circuits, typical firing circuits, controls features of firing circuits. The triac, Gate turn-off thyristor, the power transistor, power MOSFET, Insulated gate bipolar transistor, other devices, Ratings, Losses and cooling, Device comparisons.

Rectifying Circuit: Commutating diode, single phase half wave, Bi-phase half-wave, Single phase bridge - uncontrolled, fully controlled, half controlled, Three phase bridge, Twelve phase circuit, Transformer rating.

Converter Operation: Overlap, Power factor, Inversion, Regulation, Equations for P-Pulse converter, Power factor control via PWM converters.

D.C. Line Commutation: Parallel capacitance, Resonant turn-off, coupled pulse, commutation by another load carrying thyristor.

Frequency Conversion: Cycloconverter - Principle, blocked group operation, circulating current mode, control, Envelope cycloconverter, single phase center tapped inverter, single phase bridge inverter, three phase bridge inverter, constant voltage source inverter, inverter reverse power flow, constant current source inverter.

Some Applications: Contactor, Heating, Voltage Regulation, Voltage multipliers, stand by inverter, parallel connections, series connections, Electrochemical, HVDC transmission, switched mode power supplies, Resonant Converters.

Harmonics: Harmonic analysis, Load aspects, supply aspects, Filters-Rectifier output smoothing, Inverter output filtering, A.C. line filters, radio interference suppression, Active filters, Electromagnetic compatibility.

Protection: Current, Voltage, Gate turn off thyristor and MOSFET, Reduction of switching losses using snubbers.

TEXTBOOKS:

Power Electronics by C.W. Landau, Mc Graw Hill.

REFERENCE

1. An introduction to thyristors and their applications by M. Ramamurthy

2. Power Semi-Conductor circuits - S.B. Dewan and A. Stranghen

3. Thyristorised power controller - S.K. Dubey et-al.

4. Power Electronics: Mohan, Undeland, Robbins: Wiley

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