PMSM Sensor Fault Diagnosis Method Based on Second-Order Sliding-Mode Observer

The position sensor in the permanent-magnet synchronism motor (PMSM) servo system is prone to failure, and even causes the servo system to collapse in severe cases. Therefore, a fault diagnosis method based on the second-order super torsion sliding-mode observer is proposed. A second-order super torsion sliding-mode observer is designed to estimate the position and speed, and the saturation function is used to improve the observer to improve the effect of chattering suppression, and then the Lyapunov function is constructed to prove its stability. The fault is detected by the residual error of position and speed, combined with the time analysis method for secondary detection, to reduce the false detection caused by the fixed threshold. Based on the results of simulation experiments, this method can accurately detect faults and determine the type of fault.