Advantages of Active Magnetic Bearings (AMB) technology continue to motivate research in this field for more than thirty years. Among these advantages are: (i) contactless actuation, which prevents mechanical wear and a need of lubrication; (ii) the ability to modify actively (by means of feedback control) such system features as stiffness and damping. Although the main application area of AMB is rotor machinery, this technology also was shown to be worthwhile in precise positioning related applications. In particular, due to relatively large stroke and non-contaminating operation, magnetically levitated positioning systems can provide an excellent alternative to other solutions, such as piezoelectric actuators and air bearings.
This study presents a novel approach for accurate modeling of AMB actuator. This approach is based on the precise real-time evaluation of the AMB core permeability value, which is assumed to be constant in a common AMB model. The improved AMB model can be used either for more efficient implementation of the well-known feedback-linearization control technique, or for obtaining more reliable results in simulations of AMB positioning systems oriented controllers. The model developed within this study was validated experimentally, using a real single-degree-of-freedom AMB plant. The experimental results demonstrate that utilization of the developed model for the implementation of feedback linearization control technique considerably improves the performance of the AMB system levitated part position tracking.
