A Load Adaptive Control Strategy for Electromagnetic Levitation Systems

The traditional control strategies for electromagnetic levitation systems (EMLS) are the voltage or current control strategies based on linearization models at the equilibrium, but their effectiveness and efficiency of response are not satisfactory especially when load varies strongly. As a large amount of overshoot occurs, the adjustment time is intolerable long. A load adaptive control strategy based on a mass observer, which is able to apply the signals of current and air gap between electromagnets and tracks to predict the mass of load, is proposed in this paper. The mass can modify the Proportion Integration Differentiation (PID) parameters associated with the changed operating point. Via the comparison between simulation and experimental results, it is verified that the load adaptive control strategy performs more accurately and efficiently than traditional PID control strategies and fuzzy PID control.