Model-free sliding mode control for PMSM based on adaptive super-twisting reaching law.

Permanent Magnet Synchronous Motors (PMSMs) are core actuators in electric drive systems for their high-power density and precision, but their control performance and robustness degrade severely under disturbances, abrupt load changes and parameter perturbations. Conventional Sliding Mode Control (SMC) has strong robustness but suffers from inherent high-frequency chattering and poor fixed-gain adaptability, failing to meet stringent high-precision electric demands. To address these issues, this paper proposes a novel model-free sliding mode control strategy (MFITISMC–ADSTA–TISMO) integrating improved terminal integral sliding mode, adaptive super-twisting reaching law and improved Terminal Sliding Mode Observer (TISMO) for high-precision PMSM control. The core contributions are: 1). A novel PMSM ultra-local model incorporating state gains and lumped unknown disturbances is constructed, eliminating accurate motor model dependence and fundamentally eradicating model mismatch errors. 2). An improved terminal integral sliding mode surface with continuous smooth nonlinear functions is designed, which, combined with the adaptive super-twisting reaching law, ensures finite-time state convergence and mechanism-level chattering suppression. 3). An improved terminal sliding mode observer is developed to accurately estimate and compensate for total system disturbances in real time, significantly enhancing disturbance rejection under complex conditions. Experimental results demonstrate that the proposed strategy outperforms traditional methods in dynamic response, steady-state accuracy, multi-condition disturbance rejection and parameter robustness, validating its engineering value in high-performance electric drive control.