On-Load Parameter Estimation of Inductors in DC-DC Buck Converters

This paper presents the design, fabrication and testing of an EE-shaped ferrite core based inductor in a lab-developed synchronous buck converter prototype at 30 W @ 200 kHz. The main aim is to propose an accurate analytical method to calculate the AC resistance of the inductor winding at different frequencies and segregate core and copper losses. The flux linkage associated with the coil is estimated to calculate the operating flux density. A study has been conducted to decide the approximation required for the harmonic expansion of the inductor current waveform. The results are further validated through on-load experiments. The on-load inductance has also been calculated from the experimental flux linkage vs current curve. The effect of temperature has been taken into account during the analysis. Excellent agreement between the experimental and analytical/ simulated results uphold the accuracy of the analysis and precision of the experiments.