Research On Electromagnetic Design And Control Strategy Of Radial Magnetic Bearing

Compared with mechanical bearings,magnetic suspension bearings have the advantages of no mechanical contact with the rotor,and can support the ultra-high-speed rotation of the rotor.However,it is difficult to select parameters in the design of magnetic bearings,and requires high control accuracy.At the same time,in order to ensure its efficiency,it is necessary to reduce losses as much as possible.Meanwhile,the current analysis and comparison of the electromagnetic characteristics of the two magnetic pole arrangements of different pole magnetic bearings are based on the same number of magnetic poles.Therefore,the different pole radial magnetic bearings are taken by this dissertation as the research object and the maximum electromagnetic force as the optimization goal.Under the constraint of the same number of magnetic circuits,the parameter selection and electromagnetic characteristics of two different pole radial magnetic bearings with different magnetic pole arrangements are studied.A detailed introduction of the advantages and the development process of magnetic bearings are given by this dissertation.The research works of domestic and foreign scholars in this field of recent years are summarized,meanwhile the working principles and classifications of radial magnetic bearings are expounded.The relationship between the electromagnetic force of the radial magnetic bearing of different poles and the stator structure parameters is studied,and the analytical model is established by the analytical method,and the model is verified by the finite element method.The law between the number of magnetic poles and the electromagnetic force of the two magnetic suspension bearings with the different magnetic pole arrangements is revealed.And on this basis,the design method of the magnetic suspension bearing is optimized.In order to analyze the difference between the two magnetic pole arrangements of radial magnetic bearings,by respectively establishing a two-dimensional finite element model to analyzed the electromagnetic characteristics of the two magnetic pole arrangements of radial magnetic bearings.Under the restriction of the same number of magnetic paths to analyze the phenomenons of magnetic field distribution,eddy current loss and electromagnetic force of the two magnetic pole arrangements of the radial magnetic bearing.Based on the analyses for the different pole radial magnetic bearings of the two kinds of magnetic pole arrangement to give their respective applicable occasions.Combined with the analysis results of the electromagnetic characteristics of the magnetic bearing,the mathematical model of the magnetic bearing is established,and the PD/PID controller is designed,which is verified by simulation calculation.Aiming at the problem of the nonlinearity and strong coupling of the magnetic bearing model,a nonlinear T-S fuzzy model of the magnetic bearing model is established,and a state-space feedback controller is designed for it.By the comparison with the two linear control strategies verifies that the method has better performance,and also has good dynamic and static performance and good robustness.The research contents of this article can provide certain reference value for parameter selection and control strategy design when designing and optimizing different pole radial magnetic bearings.