A wide input voltage range ZVS isolated bidirectional DC-DC converter for ultra-capacitor application in hybrid and electric vehicles

This paper presents a new wide input voltage range ZVS isolated bidirectional DC/DC converter for an ultra-capacitor module used as an auxiliary power supply in electric vehicles. Compared to the conventional bidirectional converters, this modified circuit minimizes device current stress over a wide input voltage range. A natural zero-voltage switching for the transformer-connected switches is achieved without additional device. Moreover, reverse-recovery process of the diode of the transformer-connected switch module is avoided. These two features promise high operation frequency of transformer to improve power density. These advantages make the new converter promising for high power density applications especially to overcome high device current stress problem. In this paper, firstly, a completed design consideration of the new topology is presented; secondly, an analysis of operation is provided; finally, a 9-21V/66V 500W prototype is built up and it successfully proved this converter's device current stresses minimization and high power density characteristics.