Power Loss Investigation of Si-SiC Hybrid Switches in a Modular Multilevel Converter System

Abstract To reduce the power loss in a modular multilevel converter (MMC), hybrid switches with different combinations of Si-IGBT, SiC-MOSFET, Si-FRD and SiC-SBD in parallel or anti-parallel are comparatively investigated. By comparing the power losses in MMC submodule (SM) bridge arm switching devices, one bridge arm of a SM is replaced with a different switch configuration, while the other remains in the conventional Si-IGBT and FRD configuration. Itot − Esw and I - V curves are obtained for four switch configurations through SIMETRIX, and brought to SIMULINK simulation over longer time scales to account for the variable switch operating condition. Along with the simulation and experimental results, the loss differences under different switch configurations are verified, obtaining the optimal switch configuration at last, which is instructive for the selection of MMC SM in the future.