Adaptive nonsingular terminal sliding mode controller for PMSM drive system using modified extended state observer

In this study, a novel adaptive nonsingular terminal sliding mode (ANTSM) control frame combined with a modified extended state observer (MESO) is presented to enhance the anti-interference performance of the permanent magnet synchronous motor (PMSM) system. In the face of time-varying disturbances with unknown upper bounds, traditional nonsingular terminal sliding mode (NTSM) controllers typically utilize the large control gain to counteract the total disturbance, which will cause unsatisfactory control performances. To address this tough issue, an ANTSM control technique was constructed for the PMSM system by tuning the control gain automatically without overestimation. On this basis, the MESO was adopted to estimate the unknown total disturbance, whose estimation was offset to the ANTSM control input. By applying finite-time techniques, the estimation error will finite-time converge to zero. The proposed MESO has a more rapid estimation speed than the traditional extended state observer (ESO). Finally, the validity of the ANTSM + ESO composite control algorithm is confirmed by comprehensive experiments.