Novel dual-sliding mode sensorless vector control strategy for permanent magnet synchronous motorized spindles

To solve the problems of overshoot, chattering, and slow response in the traditional sensorless control scheme based on sliding mode observer with PI controller, a novel dual-sliding mode sensorless vector control (NDSMSVC) strategy for permanent magnet synchronous motorized spindle (PMSMS) is proposed. Based on the PMSMS mathematical model, the terminal sliding mode controller and sliding mode observer models are successively established. To solve the singularity problem, the NTSM surface function is redefined. In designing the speed controller, the reaching law is incorporated, and the sigmoid (s) function is used to improve the discontinuities in control. ISMO integrated a phase-locked loop that extracts the rotor position and speed, which enhances the observation accuracy. The validation was carried out in the laboratory using a high-speed electric spindle (FL170-20-15). The experiments show that the proposed strategy is able to achieve the desired results and accurately track the rotor position and speed compared to the existing schemes.