Hardware-circuit-based diagnosis method for open-switch faults in inverters

The theory, design, implementation and experimental validation of a hardware-circuit-based diagnosis method for open-switch faults in voltage source inverters are discussed. Operating states of the inverter under both healthy and faulty conditions are analysed. The estimated voltages can be achieved as pre-fault voltages by means of the switching function model of the inverter under a normal condition. Then, the error voltages between the estimated ones and measured ones can be used to detect faults. To achieve reliable diagnosis, the design employs both the amplitude limit and the duration limit to filter the error voltages so as to eliminate effects of the deadtimes and the switching processes of power devices. The proposed method is validated by experiments.