Asymptotic Homogenization Method to Estimate Equivalent Thermal Conductivity of Electrical Machine Windings

Accurate and rapid prediction of temperature distribution in electrical machine windings is essential for thermal management. This paper proposes the asymptotic homogenization method as a numerical approach to estimate the equivalent thermal conductivity (ETC) of windings. A dual-scale coordinate system is adopted to analyze conductor-insulator composite, with the heat transfer problem separated into coupled macroscopic homogeneous and microscopic periodic perturbation fields. The global ETC of the winding is subsequently derived from the representative unit cell of a single wire. Crucially, the ETC is computed from the distribution and characteristic scales of physical parameters, so it is applicable to wires with arbitrary cross-sections and filling arrangements. Numerical simulations validate the accuracy of the method against randomly distributed winding models. Experiments on the prototype further confirm that the temperature distribution can be precisely predicted by the developed homogenized model, while computational efficiency is significantly improved.