Papers by Keyword: Magnetic Bearing System

Abstract: In order to eliminate the chattering phenomena caused by conventional sliding mode control (SMC) method in magnetic bearing system control, this paper proposes a variable rate reaching law approach based sliding mode controller to achieve higher system stability and robustness. In this control law, system states’ normal numbers are brought in to automatic adjust the gain of the switching control part of SMC. The controller output amplitude of chattering can be progressively damped, and the system will converge to zero asymptotically. The system stability is proved by Laypunov theory, and the prerequisite of control law parameters design is deduced out. Simulation results show that the proposed SMC control method has effectiveness in dynamic suspension position tracking performance and obtaining system robustness.

Abstract: Stabilization of a plant in case of uncertainty parameters and unmodeled dynamics are the main problems considered in this paper. A robust control of motion of a rigid shaft that is supported by magnetic bearings was used as an example. The dynamics of the active magnetic suspension system is characterized by instability and uncertainty. The uncertainty is modeled as an additive and multiplicative. Robust controller H∞ was designed for the defined plant with the uncertainty models. The robust controller assures high quality of control despite the uncertainty models. Robust control of vibrations of a rigid rotor is confirmed by experimental studies. A digital signal processor is used to execute the control algorithm in real time.

Abstract: Analysis of robustness of active magnetic bearing system is carried out in the paper. All of the most important acceptable levels of robustness are established. Rigid body model of a rotor is used for controller design, stability and analysis of robustness. Advanced tools for robust control are applied. The μ-synthesis is used to design a μ robust controller to stabilize the shaft that is supported magnetically. The influence of robust control on the sensitivity of plant with an uncertainty dynamics is shown. The influence of dynamic uncertainty on the robustness level of closed-loop system is considered. Small gain theorem and robustness theorem for an active magnetic bearing are investigated. Finally, the experimental results confirm the analytical investigations of the robust control of vibrations.