Nonlinear behavior mechanism and modeling method of wound SMD inductor

Abstract In the actual use process, the characteristics of the wire‐wound power inductor will change. On the one hand, the DC bias will fluctuate because the working current of the wire‐wound power inductor is not constant; on the other hand, there is a variable magnetic field, which, according to the principle of electromagnetic, affects structural size, core permeability, and flux density, both of which affect the amount of inductance. As a result, this research examines the wire‐wound SMD inductor's nonlinear behavior and modeling approach. Under the condition of zero bias at normal temperature, the static model is determined by simulating Y parameters and comparing its main performance parameters. The influence factors of temperature and DC bias are studied. The nonlinear model circuit is written in Verilog‐A format, and the inductor‐current curve is fitted by polynomial. The dynamic model is verified by ADS and compared with the test data. SWPA series power inductor measurement data from Sunlord is used to verify the validation of the model proposed in this paper. The Y parameter and performance index under zero DC bias at room temperature, inductance characteristics under different currents and inductance characteristics under different temperatures were compared respectively. From the comparison results, it can be concluded that, The fitting accuracy of the model is good in the frequency range of 100 KHz ~ 100 MHz, DC bias range of 0 ~ 0.28 A, and different temperatures (−40, 25, 125°C).