Effect of grain size and magnetic texture on iron-loss components in NO electrical steel at different frequencies

Abstract

The magnetic properties of non-grain-oriented (NO) electrical steels are a direct product of their inherent material properties in combination with induced changes due to material processing and external operational conditions such as magnetization and frequency. Chemical composition, grain size and texture are elementary intrinsic factors which determine the magnetic properties. Focus of this study is to improve the understanding of grain size and texture as important factors that affect different loss-components. A strong focus is placed on the frequency dependence and concurrent loss component distribution over application relevant frequency ranges of electrical machines. Due to its impact on the eddy current losses as well as the hysteresis components, the final thickness is additional subject of this study. A total of seven materials are produced on an experimental production line from one alloy. By different production and processing steps, different grain structures, textures and final thickness are achieved. The changes in the materials are attributed to the process variations and magnetically characterized. A loss separation procedure as well as loss modeling is performed and discussed. This work is part of a research field which aims to improve parametric models with low additional computational effort for the numerical simulation of electrical machines. The goal is to improve the accuracy of models with a deeper understanding of the material science.