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

The effects of skewing on the loss behavior of a megawatt rated slip-ring induction machine are studied. The iron loss evaluation is performed by postprocessing the field solution obtained from a multi-slice finite element model. A novel method to compute the three-dimensional eddy current distribution in the steel sheets is employed for the eddy current analysis. The iron loss models are validated against no-load iron loss measurements. Simulation results under load show that skewing leads to a highly non-uniform iron loss distribution along the machine length. The sum of the iron and copper losses increases slightly compared to a machine with straight rotor bars.