Calculation of AC Loss in a High-Speed Coreless Axial-Flux Machine Under No Load and Load Conditions Using a Hybrid Method

The winding eddy current loss can cause a dangerous temperature rise in an electric machine, especially in a coreless topology. The coreless axial-flux machine (AFM) is an unconventional machine configuration with many advantages, but its application is limited due to the winding eddy current loss. However, this problem has not yet been studied extensively in previous literature due to the relatively new topology. Furthermore, it is very difficult to analyze this loss accurately because it would usually require modeling each of the machine’s conductors, extending the designing and computation time significantly. This article is one of the few that utilize a hybrid method to calculate winding ac loss with both analytical method and simplified 3-D finite element analysis (FEA) of a coreless AFM, under both no load and load conditions. This method can reduce the computation time while giving relatively good accuracy, making the coreless axial-flux topology becomes more feasible. Losses at multiple sizes of conductors were calculated using this method and thermal analysis was performed with 3-D FEA to determine which conductor size will not cause the thermal problem. The analysis results of losses and temperature are then validated with test results.