A Soft-Switching Bidirectional DC–DC Converter for the Battery Super-Capacitor Hybrid Energy Storage System

For the battery super-capacitor hybrid energy storage system (BSHESS) applied to the electric vehicle (EV) or the hybrid electric vehicle (HEV), the bidirectional dc-dc converter (BDC) is the key component to control the energy flow between the battery and the super-capacitor. To reduce the internal energy loss of the BSHESS, the efficient BDC with soft-switching characteristics is the best choice. In this paper, through analyzing several existing soft-switching BDCs, a new coupled inductor based soft-switching BDC is proposed. This BDC has a simple structure with no auxiliary switch and can provide soft-switching conditions for both switches without additional control signals. In order to prove the feasibility of the proposed BDC, experimental results, which have been obtained from an experimental prototype, are presented. Experimental results show that soft-switching conditions of both switches of the proposed BDC are achieved.