Non-Linear Inductor Models Comparison for Switched-Mode Power Supplies Applications

Purpose of the paper: to compare two analytical models of non-linear power inductor to be employed in an SMPS in the same test conditions. Methodology: the models are identified by an experimental setup. It exploits the same DC/DC converter board used for simulations. The computation time and accuracy are compared, on the same computer, retrieving the characteristic curve, calculating a current profile and performing a simulation of a boost converter employing the identified models. Research limits: (a) the absolute computation time evaluation could be performed by the algorithmic complexity function; in this paper we provided a the relative comparison between the two algorithms; (b) most manufacturers do not give enough information to identify the model valid up to the saturation region; as a consequence, a dedicated measurement system is required. Practical implications: the user can choose the model according to a trade-off between computation time and operation outside the rated current interval. Originality of the paper: it is the first time that the two models are compared in the same test conditions showing the pros and cons of each. Highlights: The use of non-linear power inductors, intended as devices exploited up to a current at which the inductance is halved, is of great interest in switched-mode power supplies (SMPSs). Indeed, it allows the use of lighter and cheaper inductors improving the power density. On the other hand, the analysis of SMPSs equipped with non-linear inductors requires appropriate modeling of the inductor reproducing the inductance versus current. This paper compares two main analytical models proposed in the literature: the former is based on a polynomial, and the latter exploits the arctangent function to reproduce the non-linearity of the inductance. Performance is compared by considering the effort of retrieving the model's parameters, evaluating a current profile by the characteristic equation of the inductor, and exploiting the two models to simulate a switched-mode power supply. Results are given both in terms of computation time and accuracy with reference to experimental values, highlighting the pros and cons of each model.