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.

In this paper, the method for calculating losses in magnetic cores operating in a DC/DC power converter is experimentally verified for selected samples. The chosen method of calculating magnetic losses based on loss measurements under sinusoidal excitation is described, and the measurement process is discussed. The results of power loss measurements with a direct current bias for three different magnetic core materials, e.g., ferrite, nickel–iron–molybdenum alloy powder, and nanocrystalline, are presented. A quantitative determination of the deviations for the tested method is proposed, including the frequency dependence of the deviation distribution.

The paper presents an experimental verification of a method for computing losses in a magnetic core operating in a DC-DC converter with a variable duty cycle, based on losses measured under sinusoidal excitation conditions. The core operating conditions that influence the losses and the method for their measurement are presented. The measurement setup was designed for this research, its basic features are discussed in the paper. The results obtained from the analysis were compared with core loss measurements obtained from the Brockhaus MPG-200 system. The theoretical foundation for core loss calculations and the measurement error analysis are also presented. The discussion of the results takes into account additional factors, such as the effect of working temperature on loss level.