Adaptive Sliding Mode Control for PMSM Drives with High-Order Disturbance Compensation

To enhance the dynamic response and robustness of permanent magnet synchronous motor (PMSM) speed regulation under load disturbances, this study proposes a composite control strategy that integrates a novel sliding mode control based on an adaptive reaching law (NSMC) with a high-order disturbance observer (HDOB). First, an adaptive reaching law is designed to accelerate the convergence process when the system state is far from the sliding surface, while an adaptive saturation function (ASF) is introduced to smooth switching actions and reduce chattering near the sliding surface. Subsequently, a high-order disturbance observer is developed to estimate the lumped disturbance and its variation in real time, with the estimated disturbance being fed forward to the output of the speed-loop controller to enhance disturbance rejection capability. The effectiveness of the proposed method is validated through simulations and real-time experiments on a Hall-sensor-based PMSM drive platform. Experimental results show that, at a reference speed of 600 r/min, the proposed NSMC reduces settling time by 43.1% compared with conventional sliding mode control, while virtually eliminating overshoot. Under sudden load application and removal, the proposed NSMC + HDOB reduces the maximum speed deviation by 38.3% and 57.2%, respectively, compared with SMC + HDOB. These results indicate that the proposed strategy achieves faster speed tracking, smaller speed fluctuations, and enhanced robustness against load disturbances, offering an effective solution for high-performance PMSM drive systems.