Research and Discussion on Thermal Model Equivalent Methods of the Random Winding

Accurate thermal modeling of windings is critical for predicting motor temperature distributions when using the computational fluid dynamics (CFD) method. To solve this problem, the concentrated and anisotropic equivalent methods of random winding was systematically analyzed, and a layered equivalent strategy that simplifies the random winding into a multilayer concentric structure of copper and insulation was proposed. Then, a single-tooth random winding model was established by full model, concentrated, layered and anisotropic equivalent methods, and the steady-state and transient temperature field were carried out. The temperature experiment of single-tooth winding samples shows that all models show high accuracy in temperature calculation, exhibiting a maximum relative error below 2.9%. Furthermore, a comprehensive comparison of modeling dimensions, meshing, computational time, and result accuracy was conducted, summarizing the advantages and limitations of each method. The results indicate that the efficiency of the three equivalent methods is significantly improved compared with the full model. The maximum mesh elements shall not exceed 16% of the full model, with computational time reduced by over 75%. The results of this paper also clarify the applicable boundaries of various methods, providing a basis for the selection of motor thermal design.