Iron Loss Analysis of High-Speed AFPM Motor With Ultra-Thin Silicon Steel Considering Bending Stress

In this paper, an iron loss model considering multiphysics fields is proposed and applied in a high-speed axial flux permanent magnet motor (HSAFPM). The investigated HSAFPMs are fabricated using winding cores of conventional silicon steel (CSS) with a thickness of 0.27 mm and ultra-thin silicon steel (UTSS) with a thickness of 0.05 mm, respectively. The wound technique makes axial flux motors easier to manufacture, but induces bending stresses. Therefore, the core loss of the motor is affected by the interaction of high frequency electromagnetic field, temperature and bending stress. The article analyses the difference of bending stress induced by silicon steel sheets with different thicknesses, and according to the operating conditions of the motor, the magnetic properties of silicon steel under the bending stress-temperature-electromagnetic multiphysics field coupling conditions are analyzed, and an iron loss model considering multiphysics fields is proposed. The validity of the proposed model is verified by experiments on silicon steel sheets with multiphysics fields, and the accuracy is improved compared with existing models. Finally, two motors with different core material thicknesses are fabricated and the proposed iron loss model is verified in the motor using the finite element method for more accurate calculation of motor iron loss.