This paper proposes a fault-tolerant control scheme for a modular multilevel converter (MMC) in medium-voltage motor drives. The redundant submodules (SMs) are implemented in each converter arm to bring advantages during healthy and fault-tolerant operations. During the healthy operation, redundant SMs are controlled to function as a normal half-bridge SM, which helps reduce the SM capacitor voltages, improving the system's reliability and loss reduction. During the fault-tolerant operation, the failure SMs are only bypassed in one converter arm, and the other arm’s SMs keep functioning
thus, it utilizes redundant SMs for future failure SMs. The injected scheme is also performed to ensure low voltage ripples on the SM capacitors during the low-speed operation. The feasibility of the proposed control scheme has been verified by simulation results for the 4160-V/1-MW MMC-fed induction motor drive system.