SiC-MOSFETs Characterization and Optimal Parameter Selection for Frequency Doubling LLC Resonant Converter

Data center power distribution is increasingly transitioning toward high-voltage DC, placing new demands on server rack power supply design to deliver high efficiency and high power density. The Frequency Doubling (FD) LLC resonant converter is a suitable topology for adapting to increased DC input voltage while maintaining similar device voltage stress, particularly where high step-down ratio and galvanic isolation are required. To enhance the efficiency and address asymmetrical stress of devices in the FD LLC converter, this paper proposes a method for selecting primary-stage semiconductor devices and determining tank parameters and needed dead time to achieve zero voltage switching across the full operating range. Using a flexible resonant double pulse test setup, the performance of different devices is characterized through LTspice simulations and validated experimentally. The results demonstrate that combining devices with different on-resistance values can enhance efficiency and suppress uneven loss while preserving the effective output capacitance to guarantee ZVS under all operating conditions.