An improved model-free approach for PMSM drive with multi-parameter mismatch and external disturbances

Abstract

Permanent magnet synchronous motor (PMSM) drive system is widely used in various industrial fields. However, parameter mismatches and multiple load torque disturbances inevitably reduce the tracking accuracy of the system. This paper presents a model-free finite-time sliding-mode robust control approach with a hybrid cascaded extended state observer (HCESO) for a PMSM drive system. An ultra-local model of the system speed loop is first constructed. Then, a model-free finite-time sliding-mode controller (MFFTSMC) is designed. Moreover, a HCESO is developed to decompose the lumped disturbance into main and residual components without requiring complex computations, then estimates them separately using observers with distinct characteristics. Compared to the existing single-observer disturbance rejection architectures, this design preserves algorithmic simplicity while reducing the estimation burden on individual observers. By estimating and compensating for residual disturbances, it significantly enhances the accuracy of lumped disturbance estimation. This improves the system’s robustness and control accuracy under severe operating conditions. The closed-loop stability is rigorously proven in the uniformly ultimately bounded stability (UUBS) sense through Lyapunov analysis. Finally, simulation and experiment verify the validity of the method by in comparison with other methods under multiple external disturbances and composite parameter mismatches.