Modular Multilevel Converter with Novel Octal-Switch Redundant Submodules to Ride Through Open-Circuit Faults

A modular multilevel converter (MMC) with octal-switch redundant submodules is proposed to ride through open-circuit faults from insulated gate bipolar transistors.Faults are detected using a residual analysis method, followed by prompt compensation for insufficient voltage.An active fault diagnosis method is subsequently applied to accurately identify the faulty switch location, bypass the affected submodule, and engage redundant modules to maintain converter output, thereby achieving ride-through operation for open-circuit faults.The proposed fault ride-through can quickly detect faults and identify the types without requiring additional sensors or complex mathematical models.This ensures the stable operation of the MMC with the proposed octal-switch redundant submodules.The proposed circuit and control are validated through simulations.