Analysis of AC Loss in High-Speed Switched Reluctance Motor for Electric Vehicle Considering Winding Axial Transposition

The 3-D finite element method (FEM) has been widely used for accurate analysis of winding loss with winding axial transposition angle considered. However, its application is limited due to long computation time and complex modeling processes. To address these problems, this article proposed a 2-D equivalent permeability modeling method (EMM). First, according to the proposed method, the 3-D winding model with axial transposition angle could be equivalent to several segmented 2-D models. Through equivalent axial length coefficients, 2-D models with different axial lengths could be solved in one project. Using appropriate segment and equivalent coefficients, to a great extent, the inherent error of the 2-D model could be reduced. Second, with equivalent permeability and conductivity, current density distribution and winding ac loss could be calculated. To verify the correctness and robustness of the proposed method, the study was conducted in the five-parallel-strand model. Single-tooth models with concentrated windings were built to verify the evaluated winding loss. In addition, a 20-kW 12/8 high-speed switched reluctance motor was manufactured, and the temperature rise was tested to verify the effect of winding loss on the temperature rise. Through the comparison of experiments and FEM, the EMM is verified to be with high accuracy and computational efficiency to analyze the ac loss and current distribution.