DC Bias Impact on Magnetic Core Losses at High Frequency

This paper aims to provide more insight into core losses at high frequency (MHz range) with superimposed DC bias in ferrite. Inductive cancellation method is employed to reduce measurement sensitivity to phase errors. The tested MnZn ferrite has a nominal relative permeability (μr of 1500 (core A) and 800 (core B), which was tested at frequency from 500 kHz to 3 MHz. The DC bias appears to create a shift in the Steinmetz parameters, in particular the ki and β are affected the most. Higher BDC creates higher losses gain and higher fsw makes the relative losses increase lower. This is a new finding. Furthermore, the Steinmetz Premagnetization Graph (SPG) with iGSE method ise used to create a core losses prediction model. A maximum error of 25% were found. The measurement data and the built model will be published online for use by other magnetics designer.