A Review on Hybrid Modular Multilevel Converters for Medium Voltage Applications

The medium-voltage dc (MVDC) distribution network is gaining interest due to the increasing demand for electrical vehicles, medium voltage motor drives, onboard electrical systems for electric ships, and distributed generations. The conventional two and three-level converters face challenges with high filter requirements and series connection of power switches. To overcome these challenges and improve the converter performance, the modular multilevel converter and its derived topologies are the best suitable choice. This paper discusses different major multilevel converters for medium voltage applications, which include modular multilevel converter (MMC), alternate arm converter (AAC), parallel hybrid converter (PHC), and modular embedded multilevel converter (MEMC). The comparative analysis of these converters based on their structure, device count, energy storage requirement, and semiconductor losses are performed in this paper. The working principle of the converters is validated using the simulation studies in MATLAB/Simulink environment.