Predicting Core Losses Under the DC Bias Based on the Separation Model

Magnetic components in switched-mode power converters usually work under the rectangular voltage excitations with a dc premagnetization; the nonlinear changing characteristics of core losses in the magnetic components are hard to predict. In this paper, the method for predicting core losses in power inductors is introduced. A simplified hysteresis loss model is proposed to explain the well-known empirical characteristics of the hysteresis loss. If the working conditions of the dc bias and flux density are the same, hysteresis losses will keep constant independent with the exciting voltage waveforms, and the values of eddy-current losses will also have the constant mathematics relationships between nonsinusoidal voltage excitations and sinusoidal voltage excitations. The proposed method is very practical since it only takes core loss data under the sinusoidal voltage excitations as inputs rather than relies on any material parameters. Core losses under the different duty cycles and premagnetization levels have been tested; the experimental results verify the correctness of the proposed model.