A High Efficiency and Low Shutdown Current Bidirectional DC-DC CLLLC Resonant Converter

This paper proposes a detailed design method to build a bidirectional CLLLC resonant converter for an on-board charger (OBC). The proposed CLLLC resonant converter can realize the ZVS of the switching transistor and the ZCS of the rectifier, benefiting from its high efficiency and high power density, and can thus realize a wide output voltage range. Furthermore, the bidirectional energy transformation makes the CLLLC topology suitable for use in OBC dc-dc converters. The design method proposed in this paper is used to systematically expound the relationship between the parameters and the characteristics of the CLLLC converter. In addition, the resonance parameters are optimized according to the key indicators of shutdown current and efficiency. A prototype with a forward operation at 6.6 kW and a reverse operation at 3.3 kW is built according to the proposed design method and its characteristics are verified.