A New Two-level Hybrid Modular Multilevel Converter

This article proposes a single-phase two-level hybrid modular multilevel converter (2L-HMMC) by combining the traditional two-level structure with the modular multilevel converter (MMC) to simplify control and reduce active devices. The 2L-HMMC structure is simple and only requires two power frequency switches and two sub-modules to achieve nine-level output voltage. 2L-HMMC inherits the advantages of MMC, such as modularity, scalability, common DC bus, and high efficiency. Meanwhile, compared to conventional hybrid modular multilevel topologies, such as NPC-MMC, it reduces two switches and one DC capacitor. Therefore, the proposed topology not only eliminates the midpoint problem but also reduces the overall volume of the inverter and improves power density. This article provides a detailed introduction and investigation of the structure and operation principles of the proposed topology, and a simulation model is built in order to verify the performance of the proposed topology.