Research On Electromagnetic Drive Modeling And Structure Design Of Large-Stroke Maglev Platform

The large-stroke maglev platform is a new-type multi-degree-of-freedom motion platform,and is a core component supporting the development of high-end manufacturing equipment such as IC manufacturing equipment and nano-precision machining tools.It directly achieves vertical suspension and horizontal large-stroke motion through Lorentz force between permanent magnet array and coil array.Compared with the traditional method of stacking multi-level one-dimensional motion to achieve high-dimensional motion,it can get higher dynamic response performance and motion accuracy.With the improving requirements of processing precision and production efficiency,the movement platform is more demanding on the thrust and its fluctuation characteristics.This dissertation focuses on permanent magnet array magnetic field modeling and harmonic characteristics analysis,coil electromagnetic force/torque modeling and force ripple analysis,new configurations of permanent magnet array and integrated design method of electromagnetic structure,which provide theoretical basis and technical support to develop a high-performance large-stroke maglev platform.Firstly,this dissertation analyzes the characteristics of permanent magnet array analytical modeling method,calculates the fringe magnetic field of the permanent magnet array using the equivalent magnetic charge method,establishes the magnetic field harmonic model of the permanent magnet array by the Fourier series method,and analyzes the influence of the array structural parameters on the amplitude of basic wave and the proportion of high-order harmonics,thus providing ideas about the optimal design of permanent magnet array.Based on the harmonic model of magnetic field and Lorentz force integration method,the simplified rectangle model of coil is used to derive the electromagnetic force and torque expressions of the coil.The effects of coil size and installation angle on horizontal thrust decoupling are analyzed,and an accurate analytical modelling method of coil fillet using polar coordinate system is discussed;the model of the force ripple caused by high-order harmonics of the magnetic field is established,and the ratio of the coil length and the magnetic pole pitch which can effectively suppress the force ripple is obtained.Aiming at the high magnetic flux density-low high-order harmonics requirement of the permanent magnet array for moving-coil maglev platform,a new permanent magnet array with different magnetization and magnet height is proposed,and its harmonic model of magnetic field is deduced and the parameters of the array are optimized,and its easy-to-manufacture characteristic is introduced.The theoretical and experimental results both show that this proposed structure can effectively increase the magnetic flux density and the coil thrust,and the suppression effect of high-order harmonics is better than the existing configurations.Aiming at the weight reduction requirement of the permanent magnet array for moving-magnet maglev platform,a new permanent magnet array with installation gaps and installation height differences is proposed.The magnetic field model is established,analyzed and optimized.The modal analysis of the lightweight mover board is conducted.The theoretical and experimental results show that its quality,vertical component of flux density,and high-order harmonics suppression effect have all been improved compared to the existing configurations.Finally,the DQ decomposition method and direct decoupling method for the decoupling control of the maglev platform are introduced,and the advantages and disadvantages of both methods are analyzed and compared.According to the structural characteristics of the three-phase windings of the DQ decomposition method and the structural requirements of suppressing the force ripple caused by high-order harmonics,the design criteria of the maglev platform electromagnetic structure are given.Based on the minimum of coil currents 2-norm,the direct current decoupling model for current distribution is obtained.The electromagnetic structural design criteria for the maglev platform which is suitable for the direct decoupling method are summarized.According to the derived design criteria,the design flow of the electromagnetic structure is summarized,methods for parameter optimization of coils are provided,and a design tool based on Matlab is developed.