Temperature characteristics of core losses for HfO2 doped manganese-zinc ferrites

Core losses in manganese-zinc (MnZn) ferrites is an important factor governing the performances of power conversion devices such as power converters and switching mode power supplies. With the development trend of miniaturization, lightweight, and high frequency for power supply, it is worth emphasizing that the temperature characteristics of ferrite cores are closely related to energy transfer efficiency and reliability of power conversion devices and components. Herein, the effect of high valence ion additive HfO₂ on the microstructure and electromagnetic performances of MnZn ferrites was systematically discussed, as well as physical mechanism of temperature dependence of core losses. The variation of hysteresis loss has been correlated with the hysteresis loop area (B-H), and the effect of the ratio of square of average grain size to resistivity D²/ρ on eddy current loss has been taken into consideration. Remarkably, eddy current loss does not monotonically decrease with the increase of HfO₂ content via enhancing resistivity ρ, as well with the variation of average grain size D. The state-of-the-art MnZn ferrites with excellent temperature characteristics of core losses exhibits great potential in power conversion devices operating in a wide temperature range.