Anisotropy of Losses in Non-Oriented Iron Silicon Sheets: Influence on Electrical Machine Applications

Non-oriented iron silicon alloys are not perfectly isotropic, and one wonders how this structural anisotropy, mainly related to the lamination direction, can affect loss measurements if the relative orientation of the induction is not considered. Moreover, since the induction direction changes from one tooth pitch to another in electrical machines, one wonders how to estimate actual losses in the machine considering this anisotropy effect. In the first part, we present a characterization of a 0.35 mm-thick iron silicon sheet performed by means of a 2-D single-sheet tester designed to realize measurement in a continuum of induction directions with regard to the rolling directions in a wide range of frequencies and peak inductions. Based on the statistical theory of losses, loss separation is carried out, and the parameter V-0 is properly analyzed as a function of the induction direction. In the second part, the experimental identification of hysteresis losses and the V-0 parameter are used to estimate losses in a high-speed electrical machine considering the material anisotropy effect.