AN SiC‐based soft‐switching and self‐power supply MMC for MVDC

Abstract Here, a novel modular multilevel converter (MMC) and its associated control scheme are proposed for medium‐voltage direct‐current (MVDC) distribution systems. The voltage gain and power can achieve wide‐range expansion by expanding sub‐modules. The voltage, current, and power are shared among all sub‐modules. In addition, all semiconductor devices implement soft switching under low voltage stress and current stress by introducing an auxiliary cell in each sub‐module. By reasonably distributing the energy collected in the soft switching process, the converter realizes the self‐power supply for the drive control circuit of the high‐potential semiconductor switches, wherein the sub‐modules are turned on step by step. The structure of the converter is described and its working principle and control strategy are analyzed in detail. Finally, a 1.8 kW experimental prototype based on SiC devices is provided to achieve an efficiency of 97.3%.