This paper analyses a method for measuring the magnetization curves of ferrite and nanocrystalline materials and determining the loss of the ferromagnetic material used in inductor and transformer cores. Analogue and digital methods for determining B(H) characteristics and the corresponding measurement setup are described. Limitations of the analogue method are highlighted, and example magnetization characteristics obtained using both methods over a wide range of flux density amplitude and frequency changes are shown and discussed. Using the magnetization curves measured using both methods, the dependence of the loss of the tested cores on the frequency and amplitude of flux density was determined. It was demonstrated that the classical analogue hysteresis method produces distorted B(H) waveforms and significantly overestimated values of loss for the tested materials compared to the manufacturer’s data. An analysis was also conducted of the suitability of the classical Steinmetz model for modelling the dependence of the loss of the considered materials on the frequency and amplitude of magnetic flux density. It was demonstrated that the coefficients in this formula should be dependent on the above-mentioned quantities to achieve satisfactory accuracy between the model and the manufacturer’s data. Using a digital method for measuring the hysteresis loop of a ferromagnetic core and measuring its temperature using an optical method, the thermal resistance values of the tested cores were determined. Using the digital measurement method and the modified Steinmetz formula, a significant improvement in the accuracy of determining the losses of ferrite and nanocrystalline cores was achieved.
Górecki et al. (Wed,) studied this question.