Analysis and Design of a Novel Hybrid Modular Multilevel Converter With Time-Sharing Alternative Arm Converter

In this article, we propose a time-sharing principle-based modular multilevel converter (TS-MMC) for medium- to high-voltage power transmission applications, which is designed with a lightweight running feature. The TS-MMC consists of cascaded switch stacks (CSSs) and alternative arm converters (AACs), integrating the merits of both the modular multilevel converter and the two-level voltage-source converter. In TS-MMC, the AACs shape the required multilevel arm waveforms, and the CSSs arrange the AACs operating at different intervals for producing the desirable output waveforms. By applying a "time-sharing" principle for the AACs, a dramatic reduction of the submodule number is achieved. Additionally, the TS-MMC does not require any arm inductors, whereas only three inductors are equipped in ac side. Moreover, featured by the specific structure, the dc fault blocking capability of the TS-MMC is also enabled. Furthermore, to explore the performance of the TS-MMC, mathematical model and control strategy of the TS-MMC are provided. Finally, the simulation and experimental results are carried out to verify the feasibility of the TS-MMC.