Research on torque analytical model of permanent-magnet spherical motor based on torque map by Lorentz force method

Abstract

The magnetic field and torque of permanent-magnetic spherical motor (PMSpM) are difficult to analyze due to the complicated structure, and therefore are often analyzed by the finite-element method (FEM) or Lorentz force method, with large amount of calculation and time consumption. This paper first establishes a three-dimensional (3-D) magnetic field analytical model of a spherical motor with permanent magnets (PMs) by the equivalent surface current method. Secondly, through the Lorentz force spatial integration of energized stator coil, a torque analytical model is established. Thirdly, in order to avoid repeated integration operation, a torque interpolation model based on torque Map is established. Both magnetic field and torque analytical models are verified by comparing with FEM and the experiment respectively. It is shown that the method proposed not only ensures the modeling accuracy but also significantly speeds up the analysis.