Reconfiguration of carrier-based modulation strategy for fault tolerant multilevel inverters

This paper focuses on the fault-tolerance of the multilevel inverters with the redundant switching states. The failure situations of the multilevel inverters are classified into two kinds of them according to relationship between the output voltage level and the switching states. When some of the power devices fail, the gate signals are reconfigured according to the failure types. The method is discussed for phase disposition PWM strategy (PDPWM) and phase shifted PWM strategy (PSPWM) in the paper and it can be extended for other carrier-based PWM strategies easily. The normal line-to-line voltage will be achieved with the proposed method when device failure occurs. At the same time, the circuit structures are the same as the generally used ones and the voltage stress of the devices does not increase. The simulation and experimental results are included in the paper to verify the proposed method.