Optimal Low-Switching Frequency Pulsewidth Modulation of Dual Modular Multilevel Converter for Medium-Voltage Open-end Stator Winding Induction Motor Drive

The first dual multilevel converter (MLC) topology for medium-voltage (MV) open-end stator winding induction motor (OESW-IM) drives was proposed in 1990s. Till now, MLC topologies to generate three-level, five-level, seven-level, and nine-level voltage waveforms for OESW-IM drives have been proposed. This paper proposes a new topology for OESW-IM drives based on modular multilevel converter (MMC) topology. The control requirements of the proposed topology are as follows: balancing floating capacitor voltages, removal of common-mode current components in stator current, and low-switching frequency operation with nearly sinusoidal machine stator currents. In this paper, synchronous optimal pulsewidth modulation (SOP) has been improved to satisfy the control requirements of the proposed topology. The proposed method has been validated using a low power experimental setup of dual three-level MMC.