Fault detection, isolation and reconfiguration of three-phase AC drive with current sensor fault

This paper deals with an on-line fault detection and isolation method for three-phase AC drives. Small magnitude fault is considered as well as complete current sensor outage. A way to deal with intermittent fault is also provided. The method is based on hardware redundancy with additional current sensors. This approach allows the fault isolation to be performed on the whole speed range including zero speed. It is inherently insensitive to the drive parameter uncertainties and variations. Moreover, the monitoring is executed while the machine is driven with a closed-loop controller and the full dynamic performances are continuously available. A decision system based on the “CUSUM” algorithm is described, which manages the post-fault operation by taking advantage of the system redundancy.