A Nonlinear Inductance Model Able to Reproduce Thermal Transient in SMPS Simulations

More compact Switched-Mode Power Supplies (SMPSs) satisfying the overall design specifications can be obtained by exploiting ferrite core inductors working in partial saturation. In this case, the inductance is no longer a constant parameter, since it exhibits a sharp drop as the inductor current increases. A behavioral model has been recently proposed, which provides the inductance at steady state. In this paper, a generalization of this model is presented, in order to capture the inductance behavior also during the thermal transient. The model inputs are the the inductor current and the SMPS load current, both measurable quantities. The model fitting to experimental measurements relies on accurate SMPS simulations performed with the envelope analysis method, particularly suitable for fast-slow systems. The simulations are also used to validate the model reliability, through comparisons with the experimental results on a boost converter.