Study On Dynamic Characteristics And Control Of Magnetic Bearing

Magnetic Bearing (MB) is one of typical mechatronic products and a new type high performance bearing piece, MB development is the important change in the supporting fields, it has a far-reaching meaning and extensive application prospect, and its practical value is inestimable. MB has the properties of no friction, no fray, dispense with lubricate, lasting life, all extrude excellence above which can't be seen in traditional roll bearing and sliding bearing. With the technology of MB is known and mastered gradually, MB will be applied to these fields far and wide: aviation and space flight, vacuum technology, machine-tool and tail-wagging engine, energy source and traffic , and so on. MB is one of the advanced technology, and the research come down to Electro-magnetic, Control Theory, Mechanics, Rotor Dynamics and Computer Science, and so on. The most important field of MB research is the research of the Controller of the MB. The performance of the controller affects the dynamic performance of the MB system and the circumgyrateticon precision of the rotor, which is very important to the application of the MB.Firstly, equations of axle bearing- stiffness rotor system and axle bearing-flexibility rotator have been deduced out on the foundation of traditional rotor dynamics. Secondly, the basic principle of the differential drive control system of the MB has explained in the thesis, the electric magnetic force of the system is simplified and analyzed. On the basis of the analysis and calculation formulas of stiffness and dampness of one-degree-of-freedom, calculation formulas stiffness and dampness of five-degree-of-freedom is given. Thirdly, the mathematical model and mechanic models have been established using traditional dynamics combined with the characteristics of MB. then, by considering the characteristics of MB and adapting the traditional Riccati transfer matrix method to magnetic suspension rotor system, a method is established for calculating and analyzing dynamics. Finally, in term with PD and PID control methods, the simulation of the two control effects is compared by adopting Matlab. At the same time, dynamic control response curve pictures of the system have been given , and the dynamic characteristics effects from PID controller parameter have been analyzedSome main conclusions are formed through researching in this thesis: the dynamic characteristic coefficient can be described by eight equivalent stiffness and dampness coefficients, the stiffness and dampness coefficients relate with not only parameters of magnetic bearing itself but those of controller. The simulation results indicated that the control target is fairly good to be carried out by choosing the appropriate proportion, accumulate and differential modulus of PID controller.