Controlled Magnetic Levitation System Based On H_ ¡Þ Control Theory

Magnetic suspension has been paid more and more attention because of its many merits such as no mechanical contact, no wear, low power loss, no need of lubrication and long service life, etc. The performance of magnetic suspension is determined mainly by its control system. Therefore,so it has great significance to study control methed of suspension system. It is difficult for a magnetic suspension system with traditional method to solve the problem of the uncertainties caused by the parameter variety and disturbance. Robust control theory can design a controller whose structure and parameters is 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 H robust control theory to magnetic suspension system.In this paper single freedom degree mathematics model on the basis of current and voltage controlled magnetic suspension are set up respectively and four freedom degrees mathematics is built. Based on H control theory about mixed sensitivity, a Hoo controller is designed and the magnetic suspension system based on H controller is stable and robust . The performance of PID and H controller are compared and evaluated. The robustness, stability and disturbance suppression are verified.By using mixed assembly and C language, the program is written and applied to the TMS320VC33 DSP control system of magnetic system. The results of simulations and experiments show that the system based on Hoo controller can work stably and have good starting characteristics, strong robustness, and satisfying disturbance suppression effect.At last, the paper presents an application of Hcontrol design to a single freedom magnetic suspension system . The design is evaluated by experiment. The experiment results show that Hoo control can levitate the suspension system stably and is very robust.