Direct in-situ Measurement of Magnetic Core Loss under Rectangular Voltage Excitation in Power Electronic Circuits

Timing skew between measurement channels can introduce a significant error in direct power loss measurements when both the voltage and current waveforms incorporate AC components. This unknown timing skew hinders the application of the two-winding method for magnetic core loss measurement, introducing challenges when attempting to verify the performance of components under desired operating conditions. This paper presents a novel approach for direct in-situ core loss measurement of an inductor under rectangular voltage excitation, eliminating the measurement error caused by the unknown timing skew in the two-winding method. Mathematical models are built to analyze the effect of timing skew on the direct measured core loss. An additional capacitor will be utilized to introduce a special geometric feature to the mathematical model, which aids the determination of the actual timing skew and the real magnetic core loss. Theoretical analysis is verified in simulation and experiment with a conventional DC-DC step-down buck converter.