Research on disturbance rejection PI control strategy of electric power steering system

In response to the phenomenon of torque fluctuations caused by the time-varying parameters of the motor in the electric power steering (EPS) system, this study takes the EPS system as the research object, improves the PID algorithm, and designs a disturbance rejection PI (DR-PI) controller based on the relative order of the controlled object. The DR-PI controller divides system disturbances into external disturbances and internal disturbances caused by the expected model mismatch. The disturbance estimator Q(s) is used to estimate the total disturbance of the system, thereby improving the system's anti-disturbance performance. The results of CarSim/Simulink show that, compared with the PI controller and the active disturbance rejection controller, the DR-PI controller improves the tracking accuracy of the assist current by 46.8-69.8%. It can effectively suppress sinusoidal disturbances and white noise disturbances. During active return control, the system responds accurately and quickly without overshooting. The proposed control strategy effectively reduces torque fluctuations of the assist motor, ensuring system control accuracy while improving the robustness of the system.