Purpose – The paper presents an application of the scaling theory in a description of energy losses in soft magnetic materials in order to improve an agreement between measurements and theoretical models. Design/methodology/approach – The scaling theory allows the description of energy losses by a generalized homogenous function, which depends on scaling exponents a, ß and amplitudes G⁽ⁿ⁾. The values of the scaling exponents and amplitudes were estimated on the basis of measurement data of total energy losses. Findings – The main findings of the paper are: the linear relationships between the scaling exponents a and ß, the data collapse of energy losses and the scaling laws for asymptotic exponents of energy losses derivatives. Research limitations/implications – The origin of the data collapse and the relationship between the scaling exponents will be the subject of further research with the aid of renormalization group method Practical implications – The paper could be useful both for device designers and researchers involve in computational electromagnetism. Particularly, the data collapse allows a comparison of energy loss values measured in laboratories on different samples and by different methods. Originality/value – The application of the scaling theory in a description of energy losses in soft magnetic materials improves an agreement between measurement and theoretical models.

The paper presents a study of the influence of magnetic hysteresis on macroscopic eddy current losses. Usually, this loss is calculated within many simplifying assumptions, of which the most striking is not only neglecting the hysteresis, but also the nonlinearity of the material. To check how such simplifications affect the results, the loss was calculated taking into account the hysteresis phenomenon for several materials. For this purpose, an algorithm for solving Maxwell’s equations with magnetic characteristics given as a family of measured hysteresis loops was constructed. A new method for conversion between H and B fields using the measured hysteresis loops was also proposed. The results of calculations for three materials show that the eddy current loss calculated with magnetic hysteresis taken into account are smaller than those calculated via the classical formula obtained for linear materials. For the tested materials, the differences reach up to around 30%, depending on frequency, magnetic flux density and thickness of electrical sheet. This may result, among others, in erroneous determination of the excess loss in Bertotti’s approach.

This paper presents a study of the empirical approach to the estimation of power losses in composite cores excited by harmonic flux density waveforms. Nowadays, magnetic cores operating in power electronic devices are excited by distorted (e.g., harmonic) flux density waveforms. Magnetic material properties are mostly determined for sinusoidal waveforms of the magnetic flux density. However, these properties can vary significantly in the case of harmonic excitations, which affects the devices’ efficiency. The effect of harmonic flux density waveform parameters (amplitude ratio and phase angle) on the level of power losses in soft magnetic composites is analyzed. A simple, empirical model of harmonic losses based on standardized measurements, i.e., carried out for sinusoidal flux density waveforms, is modified and validated. It is revealed that the empirical approach to estimating harmonic losses can be applied to magnetic composites with satisfactory modelling results.