Research on the Efficiency of Silicon Carbide Three‐Phase AC/DC Converter Under the Influence of Miller Effect

ABSTRACT SiC MOSFETs are widely used in AC/DC converters of electric vehicle. The Miller effect is an important cause of switching losses in SiC MOSFETs. This article focuses on all‐silicon carbide three‐phase voltage source rectifier (VSR) AC/DC converter. A series of studies have been conducted on the mechanism of SiC MOSFET losses and the causes of losses in the SiC three‐phase VSR. Based on a detailed analysis of the switching process of SiC MOSFETs, a high‐frequency switching model affected by Miller effect and device parasitic parameters is established. According to the model, the influence of various parameter changes on the Miller platform and switching losses under different driving modes is further discussed. A dual‐pulse test platform is built to verify the correctness of the model and the rationality of the analysis. On this basis, a steady‐state loss model of a three‐phase VSR under space vector pulse width modulation (SVPWM) is established. Finally, a prototype of a three‐phase VSR is designed and a test platform is built to experimentally verify the model. The output efficiency of the converter during closed‐loop steady‐state operation under multiple parameter changes is tested, and the experimental results are analyzed to provide suggestions for high‐frequency SiC MOSFET drive design.