Open-switch fault diagnosis and fault-tolerant control for three-phase VSI-fed induction motor drive

This paper proposes a new fault-diagnosis method and fault-tolerance control (FTC) strategy applied to the field-oriented control (FOC) of induction motor drives. The proposed diagnosis method for open-switch faults (OSFs) relies solely on measured current behavior. The diagnostic variables are extracted from the average absolute values of the normalized phase currents. The simulation results show that the diagnosis method can detect the OSFs in less than 36% of the fundamental phase current period without additional sensors. A total of nine types of OSFs can be diagnosed accurately and quickly. In addition, the obtained results demonstrate the method's robustness against load-transient conditions. Compared with existing diagnosis methods, this technique relies on two diagnostic variables and an adaptive detection threshold. To improve the drive's reliability against OSF effects, a fault-tolerant control scheme is developed based on reconfiguring the voltage source inverter (VSI) topology. In this case, the faulty VSI phase is connected to the DC-link midpoint through bidirectional power switches. Most FTC systems reported in the literature require a change in the drive's control algorithm. Hence, this paper presents a low-cost FTC scheme without changing the FOC algorithm. Simulation results are carried out in MATLAB-Simulink to validate the effectiveness of the proposed fault diagnosis method and the FTC strategy.