Performance analysis and optimization of a permanent-magnet starter motor with auxiliary poles by FEM

Due to its special structure, the distribution of magnetic fields in a permanent-magnet starter motor with auxiliary poles becomes complex and more affected by the relative position between the stator and rotor than that in an ordinary permanent-magnet starter motor. A twodimensional finite-element method (FEM), with the effects of relative position and commutation taken into account, is proposed to improve the accuracy of performance analysis. Optimization of the magnetic pole was performed by the proposed FEM. The experimental results showed good agreement with the calculated results, and the cost of the magnetic pole was greatly reduced, while the performances were improved.