Application-Oriented Characterization and Analysis of Core Materials Under Medium-Frequency Condition

Abstract

In medium-frequency applications, magnetic components generally operate in high-temperature conditions caused by higher power loss and more difficult heat dissipation, which results in changes in their electromagnetic characteristics. In this paper, the application-oriented characterization of the typical core materials, Mn-Zn ferrite and Fe-based nanocrystalline alloy, is comprehensively studied. The magnetic parameters under sinusoidal (5 kHz-50 kHz) and square (10 kHz) excitation from 20°C to 125°C is analyzed detailedly. Combined with the micromagnetic theory, the influence factors of electromagnetic parameters such as permeability and power factor angle are investigated. The loss variation of ferrite with temperature, flux density and frequency is explained by using the energy loss ratio. The proportion of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">P</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">h</sub> and Pdy in total loss with temperature and frequency is compared, and the loss fluctuation of nanocrystalline alloys and ferrite is analyzed. Moreover, the reasonable range of frequency that needs to consider temperature effect in practical applications is suggested. The difference between the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">B-H</i> loop bias under asymmetrical square excitation and DC bias conditions is compared and illuminated. The effectiveness and limitation of typical Steinmetz Equations considering the temperature and duty cycle effect are analyzed, and the suggestion of loss calculation is given combined with the material characteristics.