Torque Performance Optimization for PMSM Drives in Flux-Weakening Region With Sliding-Mode-Based Disturbance Observer

Parameter mismatch and external disturbances in permanent magnet synchronous motor (PMSM) significantly impact current and torque performance, particularly in flux weakening region. Such disturbances not only alter the regulation capability of flux-weakening current but also exacerbate torque ripple and torque error, ultimately compromising control system stability. To address these issues, a torque performance optimization (TPO) scheme in flux-weakening region using sliding-mode-based disturbance observer is proposed in this article. First, a novel prediction model considering both parameter mismatch and external disturbances is developed. The collective effects of these disturbances in the model are converted into voltage coefficients. Besides, a sliding-mode-based gradient descent disturbance observer (SMB-GDDO) is implemented to determine the voltage coefficients varying with disturbances. Next, a sliding-mode-based current controller (SMB-CC) is employed to further mitigate the effects of voltage coefficient disturbances. Then, building upon the newly developed model, a collaborative framework integrating SMB-GDDO and SMB-CC is constructed to estimate and compensate for various system disturbances. Finally, the proposed scheme is validated by simulation and experimental results, showing its ability to mitigate torque ripple and torque error while optimizing overall torque performance in flux-weakening region.