Impact of Leakage Flux on Permanent Magnet Synchronous Machines in Traction Drives Using 2D and 3D Finite Element Analysis Comparative Study

This paper examines the impact of 3D effects on torque accuracy in permanent magnet synchronous machines (PMSMs) for traction drives, focusing on various stator outer diameter-to-active-length ratios, saturation levels, and air gap lengths. While 2D finite element simulations are commonly used for design optimization, they can overestimate torque due to neglecting leakage flux, especially at high magnetic saturation. This study analyzes all major influencing factors, demonstrating that reducing the axial length amplifies the relative difference between 2D and 3D simulations, while increasing the axial length minimizes 3D effects. By investigating selected operating points at different saturation levels and air gap lengths, the research enables the extrapolation of 3D effects across different PMSM designs. These results underscore the necessity of 3D simulations in certain permanent magnet synchronous machine designs, particularly when scaling and at high saturation levels, offering an approach for efficiently predicting 3D effects.