Levitation control for a double-sided bearingless linear motor based on feedback linearization

Abstract

This paper deals with levitation control for a double-sided bearingless linear-motor system. Analytical design rules for a state-feedback gain and a state observer are derived. To decouple the production of forces in thrust- and normal-force directions, feedback-linearizing control based on the magnetic model is proposed. The proposed control design is tested in an experimental system consisting of four individually supplied linear-motor units in a double-sided configuration. The results from time-domain simulations and experimental tests suggest that the proposed control design can successfully provide smooth transition to contactless operation and retain the stable levitation during the movement in the thrust-force direction.