Structural Design And Dynamic Characteristics Of Soft Magnetic Composite Electromagnetic Thrust Bearing

In order to study the dynamic characteristics of the electromagnetic thrust bearing,based on the double objective optimization and electromagnetic field theory,the electromagnetic field and strength model of the electromagnetic thrust bearing is established by using the finite element method.Combined with the specific electromagnetic environment,the electric field and magnetic field analysis are carried out and a reasonable magnetic circuit is constructed.According to the dynamic response of the bearing under the actual working condition,the dynamic performance and strength standards of the bearing are taken as the key standards to judge the rationality of the bearing design.The main research contents are as follows:(1)Based on the analysis of the basic structure of the electromagnetic thrust bearing,a double objective optimization model is established to reduce the bearing mass and eddy current loss.The objective function is optimized to obtain the optimal structural parameters.The innovative "magnetic ring" structure design is introduced to balance the magnetic field balance and magnetic performance at the contact between the thrust disk and the stator,and balance the magnetic field variables at the contact more reasonably.(2)The electromagnetic field characteristics of the optimized structure are analyzed.The magnetic line of force,energy loss,air gap flux density and magnetic field strength on the surface of thrust disk are obtained at different frequencies.The results show that the energy loss of AMB increases parabola with the increase of frequency,and the distribution of magnetic field lines is the most intensive near the coil.At the same time,the air gap flux density around the coil and the magnetic field strength of the thrust disk reach the maximum.The magnetic circuit of the electromagnetic thrust bearing system is simulated by equivalent circuit,and the magnetic circuit characteristics of the bearing are analyzed by equivalent simplified element.The magnetic circuit is improved by using the conclusion and the material of the system.(3)Considering the influence of non-uniform magnetization of soft magnetic material magnetic ring and the edge effect of magnet on the bearing capacity,the bearing capacity model of non-uniform magnetization electromagnetic bearing is established,and the bearing capacity and stiffness under different magnetic gap and dynamic conditions are analyzed by finite element method.The results show that the electromagnetic thrust bearing made of soft magnetic material can withstand the strength of carbon steel bearing within the reasonable use range.(4)Based on the equivalent magnetoresistance model,the dynamic characteristics of the bearing are analyzed,including the dynamic current stiffness,displacement stiffness and electromagnetic force of eddy current effect.The results show that the magnetic bearing made of soft magnetic material not only reduces the eddy current loss,but also increases the dynamic bandwidth of electromagnetic force,which can provide more stable electromagnetic force,thus effectively improving the bearing performance.