Novel robust nonlinear control of magnetic bearing system based on extended state observer

In this paper, a novel robust nonlinear control scheme is proposed for a basic current-controlled active magnetic bearing (AMB) that is non-affine in the control input. First, a dynamic model approximation technique is developed to facilitate the controller design. Then, since the control characteristics of the AMB are highly nonlinear and time-varying with external disturbance, the robust nonlinear control system with an extended state observer is proposed to improve the control performance and increase the robustness of the AMB control system. Finally, The proposed approach is applied to a flywheel which is supported by four current-controlled active magnetic bearings. Simulation results are included to show the effect of the proposed new control design techniques.