Numerical Analysis Of Hysteresis Characteristic Of Permanent Magnetic Materials In High Magnetic Field

With the rapid improvement of the characteristics of permanent magnetic material, it is a kind of trend to use permanent magnetic material making permanent magnetic mechanism with high magnetic field strength. There is a kind of special permanent magnetic mechanism—magic ring which is made up of permanent magnet segments with different magnetization direction. A magnetic flux density level several times as much as the remanence B_r of permanent magnet material can be achieved, if we design the size of the magic ring properly. The assembling process of magic ring is very complex. In the process of assembling the permanent magnetic structure, there exists a magnetization pattern in which the direction of local magnetic field varies arbitrarily due to the interaction of the magnet segments, and the demagnetization or saturation might occur at certain positions of the segments. The assembly process refers to rotational magnetization and vector hysteresis problem. There is a very little information available on the arbitrary two-dimensional magnetization case to permanent magnetic materials.The hysteresis characteristic of isotropic permanent magnetic materials under arbitrary applied field is numerically analyzed in this paper. As a result of the complexity of the assembly process of magic ring, the permanent magnet segments are constrained to move according to predetermined mode. The paper analyzes numerically the assembly process of permanent magic ring combining Preisach hysteresis model with FEM, and applies hysteresis loop including minor loop to the numerical computation. The program is designed on the basis of FEM program using FORTRAN language. It is supposed that the normal component of the applied field has no effect on magnetization in the paper. Under this hypothesis hysteresis process with rotational magnetization is simulated.The paper analyzes the assembling process of magic ring which uses NdFeB and AlNiCo permanent magnetic materials with the new method presented. Also, the paper analyzes the assembling process of enhanced magic ring configuration proposed by our group. Compared with the traditional simplified method such as current sheet model, the new computation method has obtained the results with much more higher accuracy to simulate the actual properties of permanent magnetic material in high magnetic field.