A Novel AC/AC Modular Multilevel Converter for Medium Voltage Variable Frequency Vector Controlled Induction Motor Drives

Modular Multi-level Converter (MMC) is becoming one of the suitable choices for medium voltage drives application due to modularity, scalability, higher efficiency, low THD, etc. However, at the low-frequency operation, it suffers from high capacitor voltage ripple and circulating current. In this paper, a hybrid sub-module based novel MMC topology is proposed to overcome the aforementioned limitations of medium voltage drives. Also, it reduces the passive component count and reduces the overall size of the system of similar converter ratings. The control, operation, and design of the proposed converter is explained in detail in this paper. Simulation is carried out in MATLAB/Simulink with the ratings of a standard medium voltage drive to validate the concept. The results show satisfactory performance.