Three-Dimensional Eddy-Current Analysis in Steel Laminations of Electrical Machines as a Contribution for Improved Iron Loss Modeling

A finite-element method to compute the 3-D eddy-current distribution in steel laminations of electrical machines is presented and applied to the loss estimation of an induction machine. Two different eddy-current formulations, the A-V and A-T formulations, are investigated. The 3-D model is excited by boundary conditions derived from a 2-D field solution. The obtained eddy-current losses serve as a validation basis for those from two simplified iron loss models. The first one is the traditional model based on the statistical loss theory. The second one is the so-called hybrid model, which is based on the evaluation of magnetization curves. Both models are found to produce reasonable results for low-frequency losses. The hybrid model is particularly suitable for the estimation of high-order harmonic losses. The results from the models are compared to measured no-load iron loss data.