Estimation of AC copper loss in electrical machine windings with consideration of end effects

AC copper losses can represent a significant proportion of the total loss in electrical machines under high frequency excitation. With the current trend being towards high speed machines for higher power density in, for example, automotive applications, a fast and accurate technique for estimating the AC loss in the early design stages is essential. This paper presents a method for estimating the AC loss in coils in the concentrated winding of an axial flux machine (AFM) using two-dimensional (2-D) finite element analysis (FEA). Effects in the dimension not modelled in the simulation, including the end region of the winding, are compensated for to increase the accuracy of the model. The results are calibrated and verified by detailed three-dimensional (3-D) FEA, and the significant simulation time improvement over conventional 3-D and hybrid approaches is demonstrated. The principles of the method may be readily applied to other machine types, including radial flux machines.