Modeling Amorphous-Core Inductors up to Magnetic Saturation

In power supplies, inductors operating in partial magnetic saturation are increasingly exploited, to increase power density and efficiency. The design and simulation of converters exploiting nonlinear magnetic components require accurate models, able to predict their voltage/current characteristics and power losses under different operating conditions. In practical applications, inductors are subjected to either square-wave or sinusoidal voltages with different amplitude, frequency, and duty cycle. We focus on amorphous-core inductors, characterized by an extremely soft magnetic behavior and reduced magnetic losses, with a weak temperature dependence. We propose a novel behavioral circuit model with some temperature-dependent parameters, composed of two coupled nonlinear inductors and linear resistors; a capacitor is also included to account for parasitic capacitances occurring at higher frequencies for the winding. The model is tested on two amorphous-core inductors. Good accuracy is obtained in reproducing the inductor current (with different DC biases) and power loss, for sinusoidal, square, and triangular voltages with different amplitudes (also leading to magnetic saturation), frequencies (from 25 to 200 kHz), and temperatures (from 23 to 100 °C).