High-Efficiency Bidirectional CLLC Converter With Wide Voltage Gain and Reduced Losses for On-Board Charger Applications

This paper introduces a new bidirectional DC-DC converter topology featuring a CLLC resonant network designed to offer high efficiency and wide voltage range. The key innovation lies in the incorporation of a third winding on the secondary side of the transformer, combined with a two-switch half-bridge configuration. This innovative topology significantly reduces losses and stress on switches compared to traditional CLLC converters while preserving their desirable attributes, including soft switching and flexibility in power conversion. A comprehensive analysis of the operational principles in both directions of power flow is presented, highlighting the unique advantages of the proposed design. Detailed discussions on the structural features, efficiency, and voltage gain characteristics are provided, alongside a thorough parameter design process aimed at optimizing performance. Moreover, a comparative study with conventional CLLC converters is conducted, using a 1kW prototype to validate the proposed converter's superior efficiency and broad voltage gain range, thereby demonstrating its clear advantages over existing solutions.