Study On Robost Controller For Hybrid Maglev Suspension System

As a new-style and non-contact vehicle on land, maglev train has been used successfully in practice. Because of the shortcomings such as limited suspension gap and magnetic pollution in EMS(Electro Magnetic System) or EDS(Electro Dynamic System) systems, hybrid suspension systems came into research. In this paper, some problems are tackled in the research of hybrid EMS system with hybrid electromagnets made of high temperature superconductor coil and normal conductor coil.Due to the inherent nonlinearities and open-loop instability of the electromagnetic suspension systems, control of their stability must be accomplished through controller. linear control theories have provided much of the benchmark design procedures for numerous full-scale vehicles in large test facilities. However, due to constraints of linearization, the resulting time and frequency-domain controllers have restricted capability to cope with significant changes in the suspended load or large variations in the guideway profile. Though the hybrid EMS system mentioned in this paper has great advantage in saving power and increasing air gap, the control method over it is getting much more difficult and complicated accordingly. For the hybrid EMS system the paper attempts to use nonlinear control strategy to enhance the anti-jamming ability of the system. Based on dissipative theory, robust control theories for nonlinear systems can be used to design a controller whose structure and parameters are unchanged when the controlled system is under the worst conditions and can make the closed loop system maintain the performance with uncertainties. Therefore, the paper put stress on the application of robust nonlinear control theories to hybrid EMS system with hybrid electromagnets made of high temperature superconductor coil and normal conductor coil.A nonlinear H_∞ controller is designed for the hybrid EMS system presentedin this paper. The mathematical model and the basic structure of the hybrid single electromagnet levitation system are discussed firstly. Then the nonlinear characteristics is analyzed, and based on nonlinear system control theory a nonlinear Hoc controller is designed. The simulation shows the controller is feasible. After that, the four-quadrant chopper and an implementation of the maglev vehicle controller based on DSP are presented. The hardware architecture and software flow diagrams are introduced in detail. The experiment results show the system proposed is stable and robust.