TRANSFORMERS AS EQUIVALENT-CIRCUITS FOR SWITCHES - GENERAL PROOFS AND D-Q TRANSFORMATION-BASED ANALYSES

The equivalent circuits for the switches in dc-dc, dc-ac, ac-dc, and ac-ac converters are proved to be time-varying transformers. This result is used in the analyses of dc-dc converters, an eighth-order current source rectifier-inverter, and a buck-boost inverter with fruitful physical insight. The circuit D-Q transformation is proposed for the analyses of the ac converters such as inverters, rectifiers, and cycloconverters which include the time-varying transformers. New power circuit elements, the gyrators appear in the D-Q transformed inductors and capacitors of the ac converters. Few equational manipulations are required to determine the steady-state operating points and the small signal gains of the converters. The analysis result for the rectifier-inverter shows that the circuit has self-short-circuit protection capability and strong immunity in the parasitic inductor resistance. © 1990 IEEE