A modulation reconfiguration based fault-tolerant control scheme for modular multilevel converters

A modulation reconfiguration based fault-tolerant method is proposed for the modular multilevel converter (MMC) system. A practical method to reconfigure the reference sine wave is proposed from the point of view that the output line-to-line voltages should be guaranteed to be well regulated and not vary. Voltage balancing for sub-module capacitors is achieved while using carrier rotation algorithm based multicarrier pulse width modulation. Experimental results obtained from the laboratory system verified the validity and reliability of the proposed fault-tolerant control algorithm in the MMC application.