Bidirectional soft-switching converter-fed dc motor drives

Two new soft-switching dc-dc converters, with the capabilities of bidirectional power flow, and soft-switching (either zero-voltage transition or zero-current transition) are developed for de motor drives. The proposed bidirectional zero-voltage-transition converter possesses the definite advantages that both main transistors and rectifiers can switch with zero-voltage switching (ZVS) and unity device stresses during motoring and regenerating modes of operation. While both the main and auxiliary switches of the bidirectional zero-current-transition converter can operate with zero-current switching (ZCS) and minimum voltage / current stress. These converters are particularly useful for de traction systems in which both motoring and regenerative braking are desired to have high efficiency.