A 6.6kW 500khz bidirectional isolated DC/DC converter based on GaN and SiC wide devices is developed for 800V EV charging system, which is simpler and more reliable than the multilevel topology method on the output side. Firstly, resonant DAB topology with fixed frequency and relatively small turn-off current is selected to optimize the turn ratio of the transformer through simulation method and heat dissipation design of the system. Secondly, according to the determined turn ratio and resonance parameters, a magnetic integrated high-frequency transformer is designed by the method of loose coupling. The magnetic field simulation and loss solution are carried out by Maxwell software. The overall size of the transformer is reduced by about 50% compared with the traditional 90khz design. Finally, based on the application of electric vehicle charging, the resonant DAB full-load output voltage range is designed from 550v to 870v, and an experimental platform of 500khz 6.6kw 800V is built by means of water-cooled heat dissipation to verify the feasibility of the design.
