This paper introduces the power loss model and efficiency analysis of the current-type active-clamped boost full-bridge isolated converter (BFBIC) used in the medium voltage photovoltaic DC boost system. SiC BFBIC is developed by using silicon carbide semiconductor devices. Silicon carbide has the advantages of high switching frequency and low loss, which can effectively reduce the volume of the converter and improve the overall efficiency. According to the ZVS modulation technology of BFBIC, the accurate loss model and calculation formula of SiC BFBIC are derived. Through simulation results and A 5kV/50kW experimental prototype, the power loss of each loss element at different loads at 50kHz switching frequency of full-bridge MOSFETs is analyzed, and the power loss distribution of each switching device under full load is also analyzed. The results show that the developed model can replicate the actual operating conditions of BFBIC and accurately calculate converter efficiency over a wide load range. The calculation results show that the theoretical efficiency of SiC BFBIC is 98.59%, which can significantly reduce the power loss and heating of the photovoltaic DC converter.

Boost full-bridge isolated converter(BFBIC),SiC MOSFET,power loss,efficiency test