Performance Analysis and Design for Three-phase Y-Y Fixed-Frequency Bidirectional CLLC Resonant Converter with Synchronous PWM Modulation

The frequency modulation is usually employed in the three-phase Y - Y type CLLC isolated bidirectional DC/DC resonant converter (CLLC-IBDC). However, the magnetic components and control loop design are complex when the output voltage and load vary over a wide range. To address this problem, the operation characteristics of the three-phase Y - Y-type CLLC-IBDC based on fixed-frequency synchronous PWM modulation are studied in this paper, and a parametric design method is further proposed to achieve ZVS (Zero Voltage Switching) over the full input voltage range. Firstly, the voltage gain and soft switching of the converter are analyzed based on the equivalent model, and the design principles of the resonant network parameters are obtained. Then a resonant parameter design method is proposed to achieve ZVS over the full voltage range. Finally, a 1.5kW experimental prototype is developed, and the experimental results verified the correctness of the characteristic analysis and the validity of the design method.