A highly efficient Si/SiC based Hybrid Modular Multilevel H-bridge Converter for MV application

Modular multilevel converter (MMC) is gaining more and more attention for medium voltage applications due to its perks of being modular and scalable structure, lower dv/dt stress, and better harmonic performance. The single-phase MV applications such as traction converters generally consist of two-phase H-bridge MMC which results in larger energy storage requirements and higher switch count. To address this challenge, this article presents a hybrid modular multilevel H-bridge converter (HMMHC) topology best suitable for single-phase medium voltage (MV) systems. The proposed converter topology is developed by combining the three-level stack and chain links (CLs) which results in multilevel voltage at the output terminal. Further to enhance the converter efficiency with the high switching frequency, the proposed topology utilizes a combination of silicon (Si) IGBTs in the three-level stack and silicon carbide (SiC) MOSFETs in the CLs. The detailed operation of the HMMHC is discussed and verified using simulation study. Further, a detailed compassion is carried out between the proposed and existing converter based on the energy storage requirement, device count and overall losses. At last, the efficacy of the proposed converter is verified by developing a scale down prototype.