Analysis and design of LLC converter based on SiC MOSFET

With the advantage of achieving zero voltage switching for a wide input voltage range, the LLC resonant converter has become increasingly popular for use in high power density and high-efficiency power converter applications. To improve the power density, the frequency can be pushed to several hundred kHz especially if advanced power devices such as the SiC MOSFET are used. In this paper, based on the operational principle of full bridge LLC resonant converter, the loss model of the power switch is described. Also, for comparing with Si MOSFET and SiC MOSFET, their static characteristics are analyzed. Then in order to meet the requirements of high driving voltage and fast driving speed of SiC MOSFET, and take into account the influence of crosstalk of LLC resonant converter, the driving circuit of SiC MOSFET is designed. Finally, to verify the correctness of the theoretical analysis, an experimental prototype operating at 260 kHz, rated at 800V input voltage, and 500W output power is built.