Time Varying Disturbance Observer Based on Sliding Mode Control for Active Magnetic Bearing System

This paper proposes a time varying disturbance observer for the active magnetic bearing system. The first derivative disturbance value was considered different to zero to show the effectiveness and originality of the proposed methodology. A novel disturbance observer form was constructed based on the basic nonlinear disturbance observer, which was combined with a proportional integral derivative sliding mode control for designing a control system. The disturbance estimation error was converged exponentially to the zero when the time goes to infinite. The output distance of the active magnetic bearing was closely converged to the desired trajectory. The Lyapunov law was used to analyses the convergent condition of the control system. Simulation results were used to prove the effectiveness of the proposed theory.