Research Of PID Control For Active Magnetic Bearing

Magnetic bearing system is a complex mechatronic system, which involves many disciplines, including mechanical engineering, mechanics, electrical engineering, electronics, control engineering, computer science, and rotor dynamics. Compared with the traditional contact bearings, magnetic bearings have many advantages, because of its no mechanical contact, and therefore there is no friction and wear, no friction and heat, no need of lubrication and can work in high temperature environment, can achieve a high speed and have a long life, this series of advantages make magnetic bearing has a broad application prospects. using magnetic bearings in various rotating machinery to replace the traditional mechanical bearings can be significantly improved overall performance.In addition to civilian industry, the magnetic bearing also play an important role in the military and space technology, such as ultra-low temperature pump, high-temperature gas turbines in the new generation fighters, micro machining, space gyro, flywheel energy storage, missile launchers, etc. Therefore do research on the magnetic bearing have great significance.The direction of this paper is the research of the control of magnetic bearings, in allusion to the structure and framework of the magnetic bearing system and its working principle, the basic theory of electromagnetic fields according to Maxwell, at the beginging, conducted a stress analysis of rotor bearing, derived electromagnetic force and get its expression, based on this,a mathematical model of single degree freedom is got. According to the model of the magnetic bearing rotor obtained kinetic equation, and then derived the transfer function, using classical control theory-PID control method in the MATLAB environment to simulate can get the result how the system parameters affect the control perform, the initial establishment of the model was feasible in the linear process, after getting a good control situation, taking into account the non-linear factors, and non-linear factors'affection on various aspects of magnetic bearings'dynamic properties were also discussed, including the maximum capacity of the bearings, etc. In this paper we do not discuss the hardware design of the control system, but the conclusions have some reference value to the actual controller design,the parameter tuning and debugging.