Diversified Diagnosis Strategy for PMSM Inter-Turn Short-Circuit Fault via Novel Sliding Mode Observer

Traditional sliding mode observers (SMOs) are no longer able to meet the high standard requirements for interturn short-circuit (ITSC) fault diagnosis in permanent magnet synchronous motors (PMSM). The first reason is the system jitter problem caused by traditional SMO control functions. The second reason is the amplitude attenuation and phase delay problems caused by low-pass filters. A diversified diagnosis strategy based on the novel SMO for PMSM ITSC fault detection, localization, and severity estimation is proposed to address the above issues. First, the system jitter is minimized by introducing a nonlinear saturation function. Second, a diagnostic method based on second-order generalized integrator (SOGI) SMO is designed. This method can realize the undistorted extraction of back electromotive force signal. Importantly, SOGI can phase shift the filtered signal. The coupled signal used for fault severity estimation is easier to obtain. Finally, the effectiveness of the method is verified under experimental working conditions of system steady-state, dynamic, and load disturbances. The experiment shows that the proposed method can complete current calculation within 0.1 s and fault diagnosis within 1 s.