轴向磁化永磁微电机的磁场分析及定子线圈制作工艺

Magnetic Field Analysis and Stator Fabrication of Axial-magnetized Permanent Magnet Micromotor

为研究尺寸效应对轴向磁化永磁电机性能的影响,采用有限元方法对这种双转子电机的磁场进行了仿真计算,得出了轴向磁化永磁电机转子的气隙磁密波形分布。分析了转子外形尺寸、充磁极数、磁体厚度和气隙长度对气隙磁密的影响,即随着气隙长度的增加,充磁极数多的转子产生的气隙磁密幅值的减小幅度大于充磁极数少的;随着磁体厚度的增加,气隙磁密为一上升曲线,当磁体厚度达到某一点时,气隙磁密幅值基本为一常数;减小转子直径时,随着磁体厚度的降低,平均半径处气隙磁密幅值的减小幅度越来越不明显,但为不使气隙磁密波形变形严重,永磁转子径向长度需至少大于1.5 mm.对高深宽比微结构的制作工艺进行了研究,最终采用深刻蚀成型电铸工艺制作出了直径10 mm微电机在硅片上的平面定子线圈。并将直径20 mm电机的一系列转矩计算结果和实验测得结果进行了比较,计算值和实测值基本一致。分析方法和结果可对该类电机微小型化过程中的设计起指导作用。

In order to study the impact on its performance of the size effect in designing axial-magnetized permanent magnet micromotor,the finite element method was adopted to simulate the magnetic field of this kind of dual rotor motor,and the flux density wave form in the airgap was distributed.Different influences on the flux density were analyzed,which were the external dimensions,pole numbers and magnet thicknesses of the rotor and the airgap was distances.With the increasing of the airgap distance,the flux density under more poles reduces more quickly than under fewer poles.With the increasing of the magnet thickness,the flux density is a rising curve,and after the magnet thickness gets to a certain point,it is almost a constant.While reducing the diameter of the rotor,the decreasing of the flux density is slower and slower with the reducing of the magnet thickness.Meanwhile,the radial length of the rotor should be larger than 1.5 mm in order to avoid the seriously distorted waveform.The fabrication of high-aspect-ratio microstructure is studied.And the stator on silicon substrate is fabricated by deep-etching molding electroforming techniques.The results of magnetic field analysis and experiments can guide the design of the microminiaturization of the motor.