Sliding Mode Variable Structure Control of Active Magnetic Bearings Using Boundary Layer Approach

Abstract

To solve the chattering problem caused by the general sliding mode control in the active magnetic bearing control, a boundary layer approach is used in the controller design in this paper. The dynamic model of the active magnetic bearing is built firstly, and then a saturation function is employed to substitute for the sign function in the controller based on the Lyapunov theory to approximately realize infinite gain with finite gain. Finally, the performance of the controller is simulated, and compared with the general sliding mode control. The results show that the disadvantage of chattering can be effectively reduced by using the boundary layer approach, the rotor-s quick adjusting and steady levitation are achieved, and the controller has high tracking precision and good robustness.