Basic Research On A Large-Load Magnetic Levitation Gravity Compensator With Permanent Magnet Array

The magnetic levitation gravity compensator(MLGC)with permanent magnet array uses the mutual electromagnetic force between the array permanent magnets to produce larger suspension force for the gravity compensation,and has lower stiffness.Due to the advantages of non-contact,non friction,good vacuum compatibility and less additional energy loss,MLGC is widely used in the field of high precision machining measurement for the vibration isolation,and has great potential in the field of microgravity environment simulation.In this paper,a large-load MLGC with permanent magnet array is designed.An improved analytical model based on the traditional surface magnetic charge model is proposed for modeling,and its size is optimized by genetic algorithm.The work of this paper is as follows:Firstly,a double horizontal air gap three-layer permanent magnet array face-to-face topology MLGC is proposed and its basic principle is described.By analyzing the error of the traditional surface magnetic charge model based on the assumption that the relative permeability is constant 1.0,an improved magnetic charge model based on the iterative calculation of the working point of the permanent magnet at different positions is proposed.The accuracy of the model is analyzed,and the MLGC is modeled using the model.Secondly,the performance index of the MLGC is defined,and the influence of each size of the MLGC,including air gap,pole distance,stator pole arc coefficient,mover pole arc coefficient,stator thickness and mover thickness,on the levitation force and stiffness performance of the MLGC is analyzed.The variation law is summarized,and the size optimization range of the MLGC and the optimization scheme are given.Thirdly,combined with the above analysis,the design principle of MLGC is clarified.The size of MLGC is optimized based on genetic algorithm,and the size of two topologies with better theoretical performance are obtained and compared.The mechanical structure of the MLGC is designed,and the strength is checked and analyzed.Finally,the prototype of two kinds of topology permanent magnet array MLGC is manufactured,the triaxial pressure test platform is built,and the levitation force characteristics are measured.The experimental results verify the effectiveness of the optimization scheme.Then,the error causes between the finite element model and the experimental data are analyzed from three aspects of measurement error,machining error and assembly error.