This study provides the first detailed exploration of core losses in MnZn and NiZn ferrite cores under DC bias with sine wave excitation, spanning frequency ranges from 100 kHz to 10 MHz. Contrary to traditional models that predict an increase in core loss with the addition of a DC component, our observations indicate a non-monotonic behavior characterized by distinctive turning points. These turning points vary with operating frequency, peak flux density, and material type, highlighting the complexity and variability in core loss. This discovery not only challenges the prevailing core loss models but also lays the groundwork for optimizing the design of magnetic components through more accurate predictions of loss across various conditions. The capacitive cancellation method was employed to reduce the errors caused by phase discrepancies, ensuring the reliability of our measurements. MnZn cores were used for measurements in the kHz range, while NiZn cores were utilized in the MHz range, each showing consistent trends within their respective frequency domains.
