Sensor Fault Tolerant Control of Induction Motors

In this paper we propose a multiobserver switching control strategy for fault tolerant control of induction motors. The strategy combines three current sensors and associated observers that estimate the rotor flux. The estimates provided by the observers are compared at each sampling time by a switching mechanism which selects the sensors–observer pair with the smallest error between the estimated flux magnitude and a desired flux reference. The selected estimates are used by a field oriented controller to implement the control law. Pre-checkable conditions are derived that guarantee fault tolerance under an abrupt fault of a current sensor. Simulation results under realistic conditions illustrate the effectiveness of the scheme.