Distribution Law Of Magnetic Field In Permanent Magnet And Its Application In Sensor

Because the performance of the permanent magnetic materials is strong and stable, it were widely used in the manufacture of magnetic levitation, highway track navigation, magnetic therapy and other systems of permanent magnetic sensing mechanism. Research on the accurate laws of magnetic field strength is of significant importance in the design and development of permanent magnetic sensing mechanism. Currently, cuboid, cylindrical and spherical permanent magnets were used most commonly. The research of cuboid permanent magnets is sufficient while the study on the magnetic field distribution of cylindrical and spherical permanent magnet is relatively sparse, thus restricting its accurate use in the above fields. Therefore, this paper has carried out a series of theoretical study, simulation and testing research on the magnetic field distribution of cylindrical and spherical permanent magnets and other shapes of permanent magnetic actuators that can be described.Based on the theory of Maxwell, the equivalent current model of axial-magnetized cylindrical and spherical permanent magnet was established. And the method of the equivalent current model for permanent magnet magnetic fields whose shapes are available described in mathematical language were summed up. According to the law of Ampere molecular circulation and the law of Biot-Savart, the equivalent current model of the cylindrical permanent magnetic field was established. It can describe the main impact factors of the magnetic field strength of cylindrical permanent magnet accurately. The equivalent current model of axial-magnetized spherical permanent magnet was established by summing up the applicable rules of permanent magnets with regular shape, which can be described in mathematical language. According to the equivalent current model, the magnetic field intensity vector space of cylindrical and spherical permanent magnet was disintegrated respectively. The changing rules of magnetic field intensity along the radial and axial direction were acquired.By using the finite element software of COMSOL, the simulation analysis of the cylindrical and spherical magnetic field was completed. What’s more, the method of simulation, analysis, and verify the magnetic field based on COMSOL software were summarized. According to the finite element method and the equivalent magnetic charge theory, the electromagnetic field simulation module of COMSOL software was used to finish the simulation analysis of cylindrical and spherical of permanent magnetic field. By contrasting the simulation results of COMSOL and the equivalent current mathematical model, it can be concluded that the establishment of the mathematical models have certain rationality and accuracy. It also proved that the equivalent magnetic charge model and the equivalent current model is the mathematical model is of the same physical nature but with different form.The distribution rule of axial-magnetized magnetic field intensity on center axis was applied on the magnetic resistance sensor which was put up in view of the complex structure and the poor accuracy of existing magnetic resistance displacement detector. The magnetic field detection module was designed optimally on theory and experience. It theoretically showed that the new scheme can realize the displacement measurement by testing the magnetic field strength, simplifying the structure of the measuring system, improving the accuracy of measurement.To sum up, the equivalent current model of permanent magnetic field for cylindrical and spherical permanent magnets established in this paper provided a basic method of magnetic signatures study for the permanent magnetic mechanism to reference and theoretical basis for its application in engineering.