Numerical Approach to Determining Windings' Thermal Conductivity

This study concerns the characterization of windings' thermal conductivity, which is of primordial importance for thermal management of a high power density electrical machine. Indeed, such machines exhibit high heat dissipation in the windings' area. A precise knowledge of this conductivity value is therefore important for good thermal predictions. Unfortunately, the heterogeneity of the windings and the heat production repartition make it difficult to calculate easily winding's equivalent conductivity. The influence of four thermal and geometrical parameters on the windings' equivalent thermal conductivity is numerically studied on a Finite Element Analysis software, allowing determining precisely this characteristic. The impregnation's thermal conductivity, the conductors' number, the fill factor and the configuration of the copper wires inside the slot are investigated. The equivalent thermal conductivity, principally controlled by the impregnation thermal conductivity, the slot fill factor and the conductors' disposition, is expressed in terms of the first two parameters in its worst-case configuration.