Backstepping control of a bearingless induction motor based on a linear extended state observer

To improve the suspension performance and disturbance rejection ability of a bearingless induction motor (BL-IM), a backstepping control (BC) based on the linear extended state observer (LESO) strategy is proposed. Firstly, the vector control method is combined with two backstepping controllers introduced in the control system. Then, the LESO is applied to estimate the total disturbances composed of uncertainties and unknown external interference in the system, which simplifies the bandwidth parameters according to the pole-placement method. The BC law is continuously updated to reduce the impact of the total disturbances. Additionally, the stability and convergence of the BL-IM are proven based on the Lyapunov theory. Finally, the proposed strategy is compared with the PID control as well as robust backstepping control (RBC) through simulation analysis and experimental verification. The results indicate that the proposed backstepping control method in this paper can both achieve good disturbance rejection performance and fast speed response, and well levitation ability of the BL-IM.