PMSM non-singular fast terminal sliding mode control with disturbance compensation

A non-singular fast terminal sliding mode control (NFTSMC) strategy is proposed for a permanent magnet synchronous motor control system susceptible to load disturbance. First, an NFTSM surface with fast convergence during the finite time is designed to circumvent the singular point in the TSM surface. Then, a novel reaching law (NRL) is presented to resolve the inconsistency between the system chattering and convergence rate in the traditional reaching law (TRL). Meanwhile, a non-singular fast terminal sliding mode disturbance observer (NFTSMDO) is developed to estimate the disturbance value and compensate the speed controller, further enhancing the system's anti-disturbance performance. Finally, the experiments are conducted jointly with MATLAB/Simulink and the dSPACE platform; accordingly, the experimental results indicate that when the system adds load disturbances, the PI overshoot is 38.7 rpm and the adjustment time is the longest. In addition, when the NFTSMC-TRL and NFTSMC-NRL-NFTSMDO overshoots are 37.4 and 22.1 rpm, respectively, the adjustment time is the shortest and the overall anti-disturbance is the best. Compared to SMDO, NFTSMDO improves the observer's response speed and estimation accuracy while suppressing sliding-mode chattering. It can be inferred that the control strategy proposed in this study can effectively suppress the chattering of the sliding mode control system and improve the anti-disturbance ability of the control system.