Study on the Dynamic Stability of Repu1sive Magnetic Levitation Systems : Optimal Control of Active Secondary Suspension

Abstract

Repulsive magnetic levitation systems for vehicle suspensions are statically stable but dynamically of zero or low damping characteristics. In paticular, it is reported that electrodynamic suspensions have negative damping in some operating conditions. In this paper, an active suspension is applied to the secondary suspension of the zero-damping magnetic levitation system in order to improve the dynamic stability of both the car body and truck. The active suspension with a pneumatic actuator is designed by optimal regulator theory. The kinetic energy and the potential energy of both the car body and truck are evaluated according to an evaluation criterion. The two-degrees-of-freedom suspension model of this MAGLEV system is analyzed theoretically and compared with the experimental results. The theoretical analysis and experimental results show that the dynamic stability is much improved by the active secondary suspension.