Calculation, simulation and production of PCB integrated inductors with focus on fringing effect

Abstract:
Inductors in modern power electronics are heavy and large in every dimension and usually they act as thermal hotspots. Planar inductors have the advantage to reduce the thickness and overall cost. A further volume reduction can be achieved, if ferrite materials as well as the windings are integrated (embedded) into the PCB. An evaluation of such method showed, that calculation is complex in terms of fringing field at the air gap(s) located inside the magnetic material. Functional demonstrators have been produced to evaluate the fringing behavior. Measured inductance values are compared to calculation and simulation. It turned out, that calculation for one air gap fits, but in case of multiple air gaps the calculation result did not meet the measurement. Therefore, a FEM simulation is necessary to predict the properties of planar inductors with multiple air gaps.