An Interleaved Soft-Switching Bidirectional Converter for EV Application

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This article presents an interleaved unbalanced capacitor voltage bidirectional soft-switching dc–dc converter to achieve a wide soft-switching range and high-power density for electric vehicles applications. In the proposed circuit, an auxiliary circuit comprising back-to-back switches and small auxiliary inductors are connected to the mid-node of switch leg to facilitate soft-switching. By properly designing the auxiliary loop, the converter achieves zero voltage switching and zero current switching conditions for the semiconductor switches across the entire load range. This technique effectively mitigates issues related to highdv/dt, diode reverse recovery, and switching losses in bidirectional dc–dc converters. Furthermore, an interphase transformer is integrated into the power loop, elevating the equivalent frequency of voltage/current ripples and minimizing power loop current ripples with a compact magnetic component, which improves power density. Finally, a 200 kHz, 5 kW prototype has been built and tested in the lab. The experimental power density (7.31 kW/kg or 18.21 kW/L) and efficiency (98.7% at full power load) achieved by the prototype confirm its viability in critical electric vehicle applications.