Nonlinear Electromagnetic Force Model and Its Application to Magnetic Levitation Control System

The electromagnetic force in the magnetic levitation system is highly nonlinear, and the leakage flux brings in tremendous error to the conventional empirical formula, which makes the force feedback hard to use in a practical maglev controller. This paper aims to present a more precise but computational efficient force model for the estimation of the electromagnetic force during levitation. Different electromagnetic force models are presented for tests, and their parameters are determined by measured data and the least squares fit. Then the best model is selected. Experiments are carried out to validate the effect of the model on a levitation control test rig. Experimental results show that the estimated electromagnetic force agrees well with the actual force; the precision of the proposed nonlinear model is satisfactory and is easy to be used in a practical maglev controller. This work paves a way for a series of control algorithms that depends on electromagnetic force feedback, which is believed to behave more robustly in the presence of elastic track and track irregularities.