Torque Calculation Method of a Permanent Magnet Spherical Motor

This paper presents the torque calculation method of a permanent magnet spherical motor. To calculate using the finite element method (FEM), three-dimensional (3D) FEM must be used. However, since the method requires excessive time and memory, an easier torque calculation method is hereby presented. In the proposed method, it is very important to obtain the approximation function of the torque profile curve. We present the approximation method of the torque profile curve and show that the torque calculation result can approximate the torque obtained by 3-D FEM.This work was supported by the National Research Laboratory (NRL) through a grant (Contract Number R0A-2008-000-20048-0) provided by the Ministry of Education, Science, and Technology (MEST)