A control method for improvement of reliability in fault tolerant NPC inverter system

In this paper, a simple method for fault tolerance is proposed for improvement of reliability when the NPC inverter fault occurs in the switching device. The fault of switching device is detected by checking the change of a leg-voltage in NPC inverter. This method has some advantage of fast detection ability and a simple realization for fault detection, compared with conventional methods. Also, reconfiguration is performed by two phases control method which used to supply the balancing three phases voltage to the load continuously. This proposed method help the system minimize the harmful affection to the load caused by a delay of fault detection. The proposed method has been verified by simulation and experiment.