Three Dimensional Harmonic Field and Eddy Current Analysis for Rotor End Region of Turbine Generator

In this paper, we report eddy current loss distribution in retaining rings of a turbine generator rotor end region. Main causes of the eddy current are harmonic fluxes in a steady state. Although the calculation required full model in three dimensional analysis, we used two different models. One is to analyze eddy current loss due to the magneto-motive force harmonic flux and another is to analyze the loss due to the slot harmonic flux. This enabled us to acquire results in reasonable times. By the analysis, distributions of eddy current loss caused by each harmonic flux are well studied. In addition, we propose a harmonic flux distribution analysis method based on a Fourier series expansion. We were able to clarify the higher harmonic flux and eddy current loss distributions.