Field Modeling for Plate-Core Inductor With Significant Fringing Using Equal-Flux Contours

An inductor with winding sandwiched between two core plates is analyzed to model the nonuniform distribution of magnetic field. The winding is placed near the edge of the core to maximize the energy within the limited footprint such that the amount of energy stored outside the core volume is not negligible. The proportional-reluctance, equal-flux model is developed to build the contours with equal amount of flux by governing the reluctance of the flux path. The shapes of the flux lines are modeled by different functions that are guided by the finite-element simulation. The field calculated from the flux lines enables calculation of inductance, winding loss, and core loss. The inductance is used as a figure of merit to evaluate the modeling accuracy. Prototypes made of flexible circuit for inductors with different layouts are measured to verify the model. The measured inductances agree with the modeled result by less than 13% error.