Comparison between an analytic method and a numerical calculation to determine the end winding inductances of a turbo generator

The paper at hand introduces a comparison between an analytic method and a numerical calculation for the determination of turbo generator end winding inductances under steady-state conditions. The analytical inductance calculation is carried out using Neumann´s formula where the coils in the end winding with finite cross section are modeled by straight serially connected filaments. Field affecting components as lamination stack, pressure plate, flux trap and air gap can approximately be considered by adopting the method of images and virtual air gap conductors. The calculation results are compared with those computed by a 3D finite element program, where both methods consider the eddy currents in the end face. For the turbo generator under investigation the results of the two methods show good accordance regarding the different approaches in modeling and calculating.