Smooth Stabilizing Controllers for a 3-Pole Active Magnetic Bearing System

In this study, a class of smooth controllers is proposed for the stabilization of a 3-pole active magnetic bearing(AMB) system. The 3-pole AMB systemis strongly nonlinear and non-affine. Conventional controllers are non smooth and complicated, which is difficult for implementation and further study. The proposed smooth controllers are designed utilizing a linear transformation on the system inputs (coil currents). Asa result, simple smooth controllers, such as quadratic state feedback controller, can be obtained. The domain of attraction of theorigin under the smooth controller is estimated. The proposed smooth controller is verified through both numerical and experimental results.