弧形永磁体外部磁场的均匀性分析

Uniformity analysis of external magnetic field of curved permanent magnet

在精密测量和航空航天领域,类磁栅位移传感器对永磁体产生磁场的均匀性有很高的要求,但常见的永磁体磁场均匀性较差,从而影响液压缸位移的高精确、高可靠测量。因此,本文设计了一种具有独特结构的弧形永磁体,首先基于分子电流假说和比奥-萨法尔定律,推导弧形永磁体在空间任一点产生磁感应强度的表达式;其次利用Maxwell电磁场分析软件对永磁体的结构尺寸进行优化,确定弧形永磁体的基本尺寸;最后搭建实验平台测量永磁体对应位置处的磁感应强度,通过对比实测数据和Maxwell仿真数据,结果表明:仿真与实验结果基本吻合,弧形永磁体能够产生较为均匀的磁场,磁场均匀区域的相对误差最大不超过3%;在类磁栅位移传感器的实际应用中,敏感元件在弧形永磁体均匀磁场内测试得到一致性较好的简谐信号,为传感器后续细分处理保证信号质量,从而提升传感器的测试精度,进一步证明了弧形永磁体产生均匀磁场的实际意义。

In the field of precision measurement and aerospace,the magnetic-grating-like displacement sensor has high requirements on the uniformity of magnetic field generated by permanent magnet.While the magnetic field uniformity of common rectangular permanent magnet is poor,which affects the high precision and reliable measurement of hydraulic cylinder displacement.Therefore,this paper designed a curved permanent magnet with a unique structure.First based on the molecular current hypothesis and the Biot-Savart Law,to derive the expression of the magnetic induction intensity of a curved permanent magnet at any point in space;then,the structure size of the permanent magnet was optimized using the Maxwell electromagnetic field analysis software,to determine the basic size of the curved permanent magnet;finally,the experimental platform is built to measure the magnetic induction intensity at the corresponding position of the permanent magnet.By comparing the measured data and Maxwell simulation data,the results show that the simulation is basically consistent with the experimental results.The curved permanent magnet can produce a uniform magnetic field,and the relative error of the uniform field does not exceed 3%.In the practical application of the Magnetic-grating-like displacement sensor,the sensitive element tests the uniform magnetic field,ensuring the signal quality for the subsequent subdivision of the sensor,thus improving the test accuracy of the sensor,which further proves the practical significance of the arc permanent magnet.