The effect of different air-gap positions on the winding losses of modern planar ferrite cores in switch mode power supplies

The development of power supply technology has always been associated with the need for further miniaturization. One aspect of this trend is a design based on mathematical and physical principles and the implementation of magnetic components. The use of planar inductors and transformers offers the best preconditions for realizing this objective as they allow the windings to be integrated directly in the circuit board. Even when only a single series of planar cores is used, exactly identical winding configurations may have different air-gap positions. Different winding losses then result as a function of this position. The following paper presents a procedure for determining the effect of the air-gap position on the winding losses in planar inductors and its practical applicability on the basis of real examples.