Current Sensor Fault Diagnosis and Fault-Tolerant Control for Encoderless PMSM Drives Based on Dual Sliding-Mode Observers

In this paper, a new fault diagnosis and fault-tolerant control scheme against current sensor based on dual sliding-mode observers (SMOs) is proposed for encoderless permanent magnet synchronous machine (PMSM) drives. The current sensor fault is diagnosed logically according to the residual of the measured current and the reference one, compared with the preset threshold. Immediately after the fault diagnosis, one SMO is utilized to restructure the fault current, and another SMO is utilized to estimate the rotor position/speed using the restructured current. Therefore, the stable operation for PMSM drive in single phase current encoderless mode can be guaranteed using the proposed dual SMOs based scheme. The experimental results carried out on a 1.0-kW PMSM drive verified the effectiveness of the proposed scheme.