A new resonant active clamping technique for bi-directional converters in HEVs

In this paper a resonant active clamp circuit is presented, addressing the efficient optimization of a bidirectional DCDC converter for hybrid electric vehicles applications. The converter structure is based on a combination of two dc/dc topologies connected through a high frequency transformer, a full-bridge stage modulated in phase shift for step-down operations and a current-source push-pull stage used as step-up. For such a converter, a resonant clamp circuit based on bipolar transistors and self-commuted driver circuitry has been developed and connected on the low voltage side. Detailed operation principles, theoretical analysis as well as design considerations are provided. In order to verify the validity and performance of this solution, a complete prototype of the converter has been built reaching a conversion efficiency of about 95%.