Operation of Medium‐Voltage Modular Multilevel Converter With Hybrid Si and SiC Half‐Bridge Sub‐Modules

ABSTRACT The medium‐voltage (MV) modular multilevel converter (MMC) with hybrid Si and SiC sub‐modules (SMs) is investigated in this paper to reduce switching losses. Unlike existing hybrid MMCs with full‐bridge SMs, stable operation is achieved by adopting only half‐bridge SiC SMs, thereby preserving the modularity of the MMC. The main contribution lies in the proper distribution of the switching actions, which comprehensively coordinates three objectives: reducing total switching loss; ensuring the capacitor voltage balance among the SMs, and limiting the capacitor voltage ripple of Si SMs. The effectiveness of the proposed distribution has been verified by both simulation and experimental results.