Four-quadrant zero-currenttransition converter-fed DC motor drives for electric propulsion

In this paper, a new four-quadrant (4Q) soft-switching converter for dc motor drives, namely the 4Q zero-current-transition (4Q-ZCT) converter, with the capabilities of 4Q power flow, and ZCT switching profile for dc motor drives is proposed. It has some definite advantages over their hard-switching counterparts and other soft-switch-ing converters. Both the turn-on and turn-off losses of main switches are significantly reduced, while the auxiliary switches can always operate with zero-current-switching (ZCS). It possesses the advantages of reduced switching stresses, minimum voltage and current stresses as well as minimum circulating energy during both the motoring and regenerating modes. It also offers simple circuit topology, minimum component count and low cost