A permanent magnet spherical rotor design and three dimensional static magnetic analysis

Abstract

In this work, to be used in spherical motor a four pole spherical rotor is designed which is shaped as quarter-spherical-segment. The material used in this design is NdFeB permanent magnet. Rotor's 3D static magnetic analysis is calculated by using finite element method (FEM). Because of the high production cost of this designed rotor, it is dwelled upon different rotor designs that can supply the same magnetic efficiency. One, three and five parts cylindrical magnet spherical rotors are designed. The magnet parts in designed rotor are placed into half-spherical shaped Teflon as to build the four pole. Thus, a spherical structure is obtained. The 3D static magnetic analysis of the rotor models is done and the surface flux density values are compared with the quarter-spherical-segment shaped rotor. As the results of the analysis, the surface flux density value of the five permanent magnet spherical rotor is nearly equal to the quarter-spherical-segment shaped rotor. The surface flux values of all designed rotors, at surface level and 1 mm from the surface, are calculated numerically with the help of Mathematica® software. Thus, the results found by using FEM, and the application results, are supported by numerical results. NdFeB 35 permanent magnet is used in the design of the rotor. To find approximate values, the factory results are taken in to consideration. At first, the 3D models of the rotors are constructed and then the material is selected. The directions of the magnetic flux of the permanent magnets are selected appropriately. To decrease the failure percent to minimum level, a sensitive mesh is done to a rotor whose model is sketched and the material selection is determined. The magnetic flux density values are shown graphically by sketching contours on to the surface of the rotor. So, the magnetic flux density values, formed by different rotor structures, are expressed graphically and the rotor structures that will provide the same efficiency are selected. © 2007 Elsevier B.V. All rights reserved.