Bidirectional soft-switching converter-fed DC motor drives

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