Analysis of magnetic flux in stator end windings of large turbine generators using Fourier expansion

The magnetic flux density in the stator end windings of alternators is analyzed using the finite-element method (FEM) using a Fourier expansion scheme. For the analysis of the field in the winding, the fundamental component is not sufficient, because the higher harmonics of the field are relatively large near/in the windings. Therefore, the fundamental, 5th and 7th harmonics components are solved. The circumferential component is examined in comparison with the angular distribution of winding current. It is shown that the quasi-3-D FEM used here gives accurate and detailed results, because it is possible to use finer elements than in the case of a fully 3-D FEM. On the basis of this analysis, it is also made clear that the circumferential component can be estimated by a few simple equations