Improved Backstepping Control with Nonlinear Disturbance Observer for the Speed Control of Permanent Magnet Synchronous Motor

This paper investigates the speed regulation problem of permanent magnet synchronous motor (PMSM) drive based on backstepping control and nonlinear disturbance observer. By introducing the backstepping control, the single-loop controller is designed instead of the traditional cascade structure, in which, speed and current controller are combined together by recursive design. However, the standard backstepping control method cannot achieve a satisfying behavior in the presence of the disturbance and parameter uncertainties. Unlike the existing adaptive backstepping control method, a nonlinear disturbance observer is designed to estimate the lump disturbance, which includes the matched and mismatched disturbance in the system. Through disturbance estimation and feed-forward compensation, the robustness of the controller is improved effectively. The stability of the system is also proved. Finally, simulation and experiment are implemented with real-time interface (RTI) based on dSPACE. Compared with PI control method, the proposed composite backstepping controller has fast transient response and strong robustness for all disturbance in various conditions.