A practical core loss calculation method of filter inductors in PWM inverters based on the modified Steinmetz equation

In this paper, a practical core loss calculation method based on the modified Steinmetz equation is proposed. It calculates the low-frequency losses and the high-frequency losses separately. By utilizing the curves of permeability versus DC bias provided by core vendors instead of plenty tests, the paper establishes a relation between the DC bias and the core losses. A novel model of minor loops is proposed to calculate the high-frequency losses based on the simulation results and Steinmetz parameters of cores. The low-frequency loss is analyzed in depth from the hysteresis curves in the B-H plane. The calculated results are verified by measuring the core losses of the filter inductor in a three-level NPC inverter. The proposed model can be derived without any test. Meanwhile, the detailed low-frequency loss calculation is presented. Moreover, the influence of DC bias is also taken into consideration to improve the accuracy. The proposed method is practical and accurate to predict the core losses.