A novel control scheme of magnetic lift and guidance

The electromagnetic suspension system, which is a kind of magnetic levitation, can be divided into two groups: separate lift and guidance system; and combined lift and guidance system. This paper considers the latter system, in which lift and guidance forces are generated by a pair of staggered magnets with the inverted U-shaped rail. Although the forementioned arrangement provides the lift and the guidance simultaneously, a separate control scheme over them is desirable. In this paper, a quasi-decoupled control method is presented which reduces the coupling between guidance and lift over a substantially wide range of lateral displacement. Simulation showed that the lift control has a small effect on the guidance but the guidance control has a considerable effect on the lift. Therefore a parallel complimentary controller on the lift controller is proposed to reduce the sensitivity for parameter variation and force disturbance. As a result, the lift system has robustness to parameter variation and force disturbance, while the guidance system is independently controllable with respect to the lift system. Hence it is possible to obtain adequate guidance force and to meet the ride quality standard related to the guidance of levitation vehicles.