Indirect Core Loss Measurement of Ferrite and Powder Cores under Rectangular AC Voltage and DC Bias

Abstract:
Accurate estimation of core losses is essential for optimizing switched-mode power supplies, which depend on precise measurement data. Existing techniques, however, often require extensive calibration and compensations, and face challenges with low-permeability materials or DC bias conditions. This work introduces an indirect method that provides high accuracy, supports DC-bias conditions, and minimizes the need for complex pre- or post-processing. The proposed method ensures core losses account for up to 98.8% of the measured DC power, achieving high precision, as confirmed by thermal imaging. For ferrite materials, the results align closely with the data published in the MagNet project under various conditions, including DC bias, showing an average deviation of less than 4.7%. In contrast, comparisons with datasheet values exhibit an average deviation of up to 15.6%. For iron powder materials, the discrepancies from datasheet values are more significant, with an average deviation of 57.2%. These findings emphasize the limitations of relying solely on datasheet values for core loss estimations, particularly for low-permeability materials.