New electromagnetic lift control method for magnetic levitation systems and magnetic bearings

The classical approach to gap control in active magnetic bearings-including those in magnetic levitation (maglev) systems-is proportional-integral-derivative (pid) based current correction. This paper explores a new method that simplifies control electronics, based on repeatedly solving the governing system equations in approximations that are valid for the next 20 to 40 ms. The method simplifies the magnetic forces by using a Taylor approximation, one that can be evaluated rapidly by using multivariate splines. The simplified equations of motion are solved by the method of Frobenius. These simplified solutions are inverted to predict the voltage necessary to achieve a desired gap change in a specified time increment. Variations from this target position allow for an update on inertia and mass of the levitated object.