Reconfiguration of Carrier-Based Modulation Strategy for Fault Tolerant Multilevel Inverters

This paper focuses on the fault-tolerance potential of multilevel inverters with redundant switching states such as the cascaded multilevel inverters and capacitor self-voltage balancing inverters. The failure situations of the multilevel inverters are classified into two types according to the relationship between output voltage levels and switching states. The gate signals can be reconfigured according to the failure modes when some of the power devices fail. The reconfiguration 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. Balanced line-to-line voltage will be achieved with the proposed method when device failure occurs. Furthermore, the circuit structures can be the same as the general ones and the voltage stress of the devices does not increase. Simulation and experimental results are included in the paper to verify the proposed method.