부산대학교 도서관

Previously, experimental results have been presented showing that Mn-Zn ferrite core losses rise significantly with dc bias levels due to an increase in magnetostrictive vibration. In addition, it has been shown that the presence of a high level of remanent flux density, ${\rm B}_{\rm r}$, left within a core after the removal of a dc bias can significantly increase core losses and, therefore, influence the hysteresis loop shape. In this paper it is shown that this loss mechanism is rate-independent in nature; furthermore, it is proposed to originate from regions of irregular stress that are dependent on the magnetostrictive vibration of a core. Accordingly, it is also proposed that certain parameters of the Jiles-Atherton (J-A) model must be modified, in order to allow influence of ${\rm B}_{\rm r}$ on hysteresis loops to be shown. These modifications are consistent with the real physical effects experienced by a ferrite core in the presence of a high level of ${\rm B}_{\rm r}$.