Dynamic analysis of radial force density in brushless DC motor using 3-D equivalent magnetic circuit network method

The distribution of radial force density in brushless permanent magnet DC motors is not uniform in the axial direction. The analysis of radial force density has to consider the 3-D shape of teeth and overhang, because the radial force density causes vibration and acts on the surface of teeth inconsistently. For the analysis, a new 3-D equivalent magnetic circuit network method is used to account for the rotor movement without remeshing. The radial force density is calculated and analyzed by Maxwell stress tensors and discrete Fourier transforms (DFT) respectively. The results of the 3-D equivalent magnetic circuit method have been compared with the results of 3-D FEM.