Sigrid JACOBS
Global R&D, ArcelorMittal
Jan RENS
Global R&D Gent, ArcelorMittal

Abstract

The JMAG software provides advanced features for the accurate calculation of iron losses. For hysteresis losses, the Play Model has been integrated, allowing the hysteresis behaviour to be calculated in the time-domain, based on a mathematical description that is derived from measured hysteresis loops. Further, eddy current loss modules are included where the skin effect at higher frequencies, that leads to a local redistribution of flux density and currents withing the lamination, is taken into account. This is implemented by coupling the main 2D or 3D FE model with an additional 1-dimensional model at every node of the mesh in the depth of the lamination.
However, regarding excess losses, an equivalent module has not been developed within the JMAG software, leaving the total iron loss calculation somewhat incomplete.
In the presentation, a comparison will be made between the JMAG loss calculation modules and the more traditional statistical loss models as developed by Bertotti. The comparison will be based on different wave form measurements, using an Epstein frame, for a number of iron core materials for a range of frequencies and polarisations. This allows the predictions of elementary material models in JMAG to be compared with the outcome of the statistical model, and pinpoint the validity limits of the statistical model. Further, the approach will indicate the importance of excess losses for the investigated materials.