Research On The Force And Torque Between Permanent Magnets

Magnetic machines working depend on the interaction force of the magnetic field, they have the characteristics of non-contact power transmission, and so they can be applied to the fields of mechanical, aerospace, chemical and pharmaceutical, etc. In recent years, with the continuous improvement of the energy product of the high-performance rare earth material, it has laid the foundation for improving the working-performance and expanding the application field of the magnetic machines.It is mainly using the magnetic equivalent circuit method to calculate the magnetic field, while using the numerical method to the theoretical analysis. For the equivalent magnetic circuit method, the data preparation process is simple and with a small amount of calculation, the disadvantage is that the inaccurate calculation of the air-gap in the magnetic field. The solution of the numerical calculation method is accurate, but the solving program is complex and the calculation is time-consuming.For permanent magnetic machines, the common shapes of the permanent magnets are always cuboidal and sleeve-shaped(including cylindrical and tile-shaped). This dissertation studies the method of calculating magnetic force and torque using the equivalent magnetic charge theory and the Coulomb’s law, and verifies the model of magnetic force and torque through experiments.In this dissertation, the following works have been accomplished:1.According to the equivalent magnetic charge theory, using the magnetic energy method, this dissertation studies the calculation method of the magnetic fore and torque between two cuboidal magnets. These studies taking into account the error between the actual magnet shape, size and mechanical structures, and the states of the two magnets which including parallel and inclined to each other. The influence of the magnetization on the magnetic force and torque is studied too.2.According to the equivalent magnetic charge theory, using the Coulomb’s law, this dissertation studies the calculation method of the magnetic force and torque when one magnetic sleeve was placed in another one. The magnetic force and torque models are derived based on the states of the two magnetic sleeves are coaxial, eccentric, and inclined each other. The model of magnetic force is verified by measuring the axial force between two coaxial alignment magnetic sleeves.3. Through the numerical calculation of the verified mathematical model, this dissertation analyzes the influence of the space attitude parameters, the geometry size, and the air-gap of the two sleeves on the magnetic force and torque. The results obtained has a predictive value for the force and torque variation which caused by the dimensional tolerances, magnetic structure, and geometric tolerances.4. The calculation models of magnetic force and torque are studied and derived when one sleeve was placed out another one with their axes perpendicular to each other, then some numerical analysis are implemented.5. The magnetic driver of a reciprocating motion, which is consist of two coaxial alignment permanent magnetic sleeves(which were made of rare earth permanent magnet material, Nd-Fe-B), was designed and built up. Through the dynamic measurement of the axial force and axial relative displacement between the two sleeves, the performance of the axial force between the two coaxial sleeves was analyzed, and the numerical calculation of the mathematical model and the experimental results was compared and analyzed.The innovation work in this dissertation:1. This dissertation established general mathematical models of magnetic force and torque between two magnetic sleeves based on the equivalent magnetic charge theory and the Coulomb’s law. The setting and modifying of the parameters are convenient by programming, and it’s suitable for analysis and optimal design of the magnetic field.2. By setting the parameters of the geometry size and the relative position, the derived models of the magnetic force and torque can be extended the calculation models of magnetic force and torque between two cylinders or a cylinder and a sleeve.3. The study method of the magnetic force and torque between two magnetic sleeves of any relative position and attitude, has the same applies to calculate the force and torque between two cuboidal magnets.