MnZn功率铁氧体高频功耗特性分析

采用氧化物陶瓷工艺制备了2～4MHz频段高频开关电源用MnZn功率铁氧体,通过对铁氧体断面显微结构、密度和磁特性的测试,研究了Fe2O3含量对MnZn功率铁氧体功率损耗特性的影响。结果表明,随着Fe2O3含量的增加,晶粒尺寸逐渐减小,常温下3MHz、10mT高频损耗(Pcv)先增大后减小,Fe2O3含量从58mol%增加到59 mol%时,损耗下降非常明显,而在100℃时,铁氧体的剩余损耗逐渐降低,导致总损耗随着Fe2O3含量的增加而减小。随着频率的升高,剩余损耗(Pr)占总损耗的比重逐渐增加,成为损耗的主要部分,而磁滞损耗(Ph)占总损耗的比重逐渐降低,涡流损耗(Pe)所占比重变化不明显。

Analysis of high frequency power loss of MnZn power ferrite

MnZn power ferrites used for 2-4MHz high frequency switch power supply were prepared by conventional oxide ceramic process.The influence of Fe2O3 content on the core losses of MnZn power ferrites was investigated by means of characterizing the fracture surface micrograph,density and magnetic properties.The results indicated that the average grain size decreases,while the core losses(Pcv) of MnZn power ferrites increase first and decrease subsequently with increasing Fe2O3 content at 3MHz,10mT and room temperature,and especially from 58mol% to 59mol% of Fe2O3 content,the core losses decrease obviously.At high temperature of 100℃,the core losses of MnZn power ferrites gradually decrease with increasing Fe2O3 content.The ratio of residual loss(Pr) and hysteresis loss(Ph) to the total core loss gradually increases and decreases,respectively,and Pr gradually becomes the main part of the core losses,while the ratio of eddy current loss(Pe) to the total core losses changes little with the increase of frequency.