Experimental validation of a variable-permeance G-C magnetic model for a SEPIC converter

This paper validates a nonlinear magnetic modeling approach based on a variable-permeance gyrator–capacitor (G–C) representation for the design of SEPIC (Single-Ended Primary-Inductor Converter) converters operating with highly uneven current stress profiles. In many practical applications, the converter runs predominantly at a nominal current level, while short-duration peaks can exceed the nominal value by more than a factor of two. An optimal design can therefore target the required inductance around nominal operation and allow a controlled inductance roll-off as peak current is approached. To assess the predictive capability of the G–C model in this context, a wide-input SEPIC converter is analysed at worst-case minimum input voltage and across multiple load points near the high-current region. Simulated inductor current waveforms, output-voltage ripple, and a large-signal load-step response are directly compared against oscilloscope measurements from a hardware prototype. The results show that the model reproduces the trend of saturation onset and provides actionable insight through the simulated magnetic flux density B, supporting inductor selection and design-margin decisions while reducing reliance on repeated prototyping.