Design of 10 kV SiC MOSFET Power Module Based MW-level Modular Multilevel Converter Phase-leg

This paper presents the design of a megawatts (MW) level modular multilevel converter (MMC) phase-leg for 13.8 kV medium voltage (MV) grid based on Wolfspeed 10 kV SiC MOSFET XHV-9 half bridge module. Compared with the 10 kV SiC single die discrete device, the 10 kV SiC multi-die module has higher di/dt, higher dv/dt (for loss reduction), and more stringent protection requirement, posing new challenges on the MW-level MV power converter design based on this 10 kV SiC module. Detailed MMC submodule and system design to address these challenges are presented. A protection strategy for this 10 kV SiC MOSFET power module is proposed, which can detect the short circuit within 200 ns and effectively limit short circuit current to within 200 A for short circuit fault at 6 kV dc voltage. Hardware is built and experimental results of the MMC submodule test at 6 kV dc voltage, MMC phase-leg test at 12 kV dc voltage, and 8-level converter test up to 23 kV are demonstrated and verify the effectiveness of the presented design.