Analytic Expression of Magnetic Field Distribution of Rectangular Permanent Magnets
-
摘要: 从分子环流模型出发,利用毕奥-萨伐尔定理,对于仅在一个方向均匀完全充磁的矩形永磁块体,导出了其外部空间磁场分布的解析表达式．该解析式能精确描述一块至多块按极性相反并列放置时矩形永磁体外部空间的磁场分布．针对单块永磁体,还分析了磁场分布与永磁体几何尺寸之间的依赖关系,以及磁场大小随外部空间点离开永磁体表面距离之间的关系;定量分析了横向磁场的强度均匀度和分布均匀度随永磁体几何尺寸和离开永磁体表面距离的变化规律．Abstract: From the molecular current viewpoint, an analytic expression exactly describing magnetic field distribution of rectangular permanent magnets magnetized sufficiently in one direction was derived from the Biot-Savart's law. This expression is useful not only for the case of one rectangular permanent magnet bulk, but also for that of several rectangular permanent magnet bulks. By using this expression, the relations between magnetic field distribution and the size of rectangular permanent magnets as well as the magnitude of magnetic field and the distance from the point in the space to the top (or bottom) surface of rectangular permanent magnets were discussed in detail. All the calculating results are consistent with experimental ones. For transverse magnetic field which is a main magnetic field of rectangular permanent magnets, in order to describe its distribution, two quantities, one is the uniformity in magnitude and the other is the uniformity in distribution of magnetic field, were defined. Furthermore, the relations between them and the geometric size of the magnet as well as the distance from the surface of permanent magnets were investigated by these formulas. The numerical results show that the geometric size and the distance have a visible influence on the uniformity in magnitude and the uniformity in distribution of the magnetic field.
-
Key words:
- permanent magnet /
- magnetic field distribution /
- analytic expression
-
[1] Moon F C.Superconducting Levitation[M].New York:John Wiley & Sons, Inc,1994. [2] 王家素,王素玉.超导技术应用[M]. 成都: 成都科技大学出版社,1995. [3] 张永,徐善纲. 高温超导磁悬浮模型车[J].低温与超导,1998,26(4):35—39. [4] Enokizono M,Matsumura K， Mohri F. Magnetic field of anisotropic permanent magnet problems by finite element method[J].IEEE Transaction on Magnetics,1997,33(2):1612—1615. doi: 10.1109/20.582576 [5] Harrold W J. Calculation of equipotentials and flux lines in axially symmetrical permanent magnet assemblies by computer[J].IEEE Transaction on Magnetics,1972,8(1):23—29. doi: 10.1109/TMAG.1972.1067275 [6] 孙雨施.关于永磁的计算模型[J]. 电子学报,1982,(5):86—89. [7] 李景天,郑勤红,宋一得,等.用边界元法计算永磁体磁场[J]. 电工电能新技术,1998,(1):7—9. [8] Campbell P,Chari M V K,Angeio J D. Three-dimension finite element solution of permanent magnet machines[J].IEEE Transaction on Magnetics,1981,17(6):2997—2999. doi: 10.1109/TMAG.1981.1061560 [9] 林德华,蔡从中,董万春. 方型永磁体表面磁感应强度分布的研究[J].工科物理,1999,9(2):5—9. [10] CHEN In-gann,LIU Jian-xiong,Weintein Roy,et al.Characterization of YBa2Cu3O7,including critical current density,by trapped magnetic field[J].Journal Appllied Physics,1992,72(3):1013—1020. doi: 10.1063/1.351826 -
计量
- 文章访问数: 4397
- HTML全文浏览量: 204
- PDF下载量: 2786
- 被引次数: 0
下载:
渝公网安备50010802005915号