The aim of an optimal design of electrical machines requires the accurate prediction of iron losses for various operating points. For this purpose different iron-loss models have been proposed which intent to describe the loss inducing effects. The most used iron-loss prediction formulas are either physically based, but nevertheless only valid for linear material behavior at low frequencies and low magnetic flux densities, or grounded on a pure mathematical description of the material behavior, that is not more than interpolated measurements. This paper presents a modified loss equation with semi-physically based parameters as well as a first try to explain the nonlinear loss component.Index Terms-High frequency iron losses, magnetic losses, measurement loss prediction, nonlinear material behavior, soft magnetic materials.

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This paper proposes a multi-scale energy-based material model for poly-crystalline materials. Describing the behaviour of polycrystalline materials at three spatial scales of dominating physical mechanisms allows accounting for the heterogeneity and multiaxiality of the material behaviour. The three spatial scales are the poly-crystalline, grain and domain scale. Together with appropriate scale transitions rules and models for local magnetic behaviour at each scale, the model is able to describe the magneto-elastic behaviour (magnetostriction and hysteresis) at the macroscale, although the data input is merely based on a set of physical constants. Introducing a new energy density function that describes the demagnetisation field, the anhysteretic multi-scale energy-based material model is extended to the hysteretic case. The hysteresis behaviour is included at the domain scale according to the micromagnetic domain theory while preserving a valid description for the magneto-elastic coupling. The model is verified using existing measurement data for different mechanical stress levels.

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