Speed sensorless fault-tolerant control of induction motor drives against current sensor fault

Current sensors are needed in conventional field-oriented control (FOC) in 3-phase induction motor (3-PIM) drives. Nevertheless, these sensors are exposed to different faults which reduce the reliability of drive systems. To solve this problem, a current sensor fault-tolerant control (FTC) for 3-PIM drives without speed measurement is proposed in this paper. In the proposed scheme, a sensorless FOC strategy based on open-loop speed estimator is utilized for normal condition. A third-difference operator performs the task of fault detection and isolation (FDI). After FDI, a sensorless FOC strategy based on extended Kalman filter (EKF) is used for the faulty condition. In this paper, the EKF is used for stator currents and speed estimation during post-fault operation. Such scheme is appropriate for sensorless 3-PIM drives to increase safety and reliability of the system, in the case of current sensor fault. The proposed FTC scheme is experimented for a 1HP 3-PIM drive system through a DSP/TMS320F28335. The experimental results show that the proposed FTC system can accurately and effectively control the 3-PIM during both healthy and faulty conditions.