Core losses in nanocrystalline soft magnetic materials under square voltage waveforms

The study of losses in nanocrystalline alloys under square voltage waveforms - often used in power electronics - is the aim of the presented numerical model and experiments. The model predicts the losses based on the theory of one-dimensional homogeneous transmission lines. The experiments are carried out by a specially designed high-current high-frequency platform in a full bridge configuration with phase shift. The losses of three toroidal Vitroperm 500F cores with different sizes are measured and calculated by the model under square voltage waveforms at variable duty ratios (5-50% with a 5% step) and constant peak induction. The measured and calculated losses correspond well. They decrease with increasing duty ratio. For applications with extreme duty ratio, the losses are higher than predicted by the classical loss theory. Finally, the losses of Vitroperm are compared with the losses in ferrites. (C) 2007 Elsevier B.V. All rights reserved.