Research On The H_∞ Control System In The Radial-Axial Magnetic Bearing Biased With Permanent Magnets

The Magnetic Bearing(MB), widely used in high speed rotation field, has the advantage over conventional mechanical bearing in many aspects, such as no mechanical contact between the rotor and the bearing, no lubrication, no pollution, long-life span and so forth. The most important direction of the development of the Magnetic Bearing system is integration technology, which can simplify the control strategy, reduce the size of the system, improve rotor dynamics performances, and reduce cost. The MB with suspended ability between radial direction and axial direction has especially been emphasized. The design of MB's control system is focused on the design of robust control system.This paper describes the study of an original radial-axial MB biased with permanent magnet, including its operation principle, mathematic model, the design of the structure, and so on. A method of design and checkout of the MB is put forward. The method of H , control has been applied to the design of the MB controller in order to improve the robust stabilization of the MB control system. In addition, the comparison between H control and traditional PID control has substantiated that H control method has better disturbance attenuation and robust stabilization. Furthermore, a digital control system for this kind of MB is established and its reliability and stabilization is verified by computer simulation of the whole digital control system.