Design Methodology of SiC MOSFET Based Bidirectional CLLC Resonant Converter for Wide Battery Voltage Range

The CLLC resonant converter has gained much attention in DC microgrid due to its bidirectional power transfer capability and high power density. When interlinking the DC-link bus and energy storage battery in DC microgrid, the CLLC converter needs to possess wide voltage regulation ability in forward mode (FM) and backward mode (BM) due to the wide battery voltage range. To solve this issue, this paper presents a simple and effective design methodology of bidirectional CLLC resonant converter based on the first harmonic approximation (FHA) model. Considering the voltage gain and zero-voltages-witching (ZVS) region, the design procedures are discussed in detail. Finally, a 10-kW SiC MOSFET based prototype converter was designed and built. Experiment results verify the theoretical expectations and the maximum power conversion efficiency is 97.2%.