Overcurrent Protection and Unmatched Disturbance Rejection under Non-Cascade Structure for PMSM

Abstract

A non-cascade structure with a simple parameter adjustment method and satisfying dynamic performance is investigated so as to address the problem of the complicated structure of a typical cascade control system of permanent magnet synchronous motor (PMSM) system. However, the current cannot work within a limited value under this structure, which poses a risk to circuit safety. To this end, a fast non-singular sliding mode (FNTSM) speed-control strategy is proposed to solve the inadequate resilience of the PI controller. Then, a nonlinear term is developed to address the q-axis current overrun. Furthermore, a sliding-mode disturbance observer (SMDO) is proposed to compensate for the current fluctuation caused by the unmatched load torque disturbances. Finally, stability analysis is conducted for the proposed composite strategy, and the hardware-in-the-loop experiments verify that it achieves satisfying speed-tracking performance and ensures overcurrent protection under unmatched disturbances.

Keywords

• permanent magnet synchronous motor
• unmatched disturbance
• drive-current constraint
• fast non-singular terminal sliding mode
• sliding-mode disturbance observer