Examination of the axial flux in stator cores with particular reference to turbogenerators

The distribution of axial flux in stator cores has been examined by numerical and experimental techniques. It has been found possible to consider separately the tooth region and the core back. In the tooth region, the axial flux is caused by the airgap fringing flux. In the core back, it is caused by the main core flux and the magnetomotive force of the winding overhang. The effect of slits in the teeth has been studied and also the effect of radial cooling ducts. The effect of butted joints between the core segments has also been considered. It has been found that axial flux is a very local phenomenon which cannot be eliminated, but which can be reduced by careful design of those regions where it is likely to be troublesome.