Minimum loss design of a 100 kHz inductor with foil windings

In high current, high frequency inductors and transformers foil windings are competitive with other types like litz wire if they are properly designed. Here, a minimum loss design of a 100 kHz inductor with foil windings using a multi air gap approach is presented. In the design process, finite element eddy current computations have been used extensively. A prototype has been constructed and tested. The inductor is designed for use in a 20 kVA dual active bridge inverter. The required inductance is 5 μH. In the final design, a multi air gap solution with 16 air gaps is used, keeping the winding losses as low as 35 W at 75 A rated current. The additional losses rising from the fringe field near the air gaps is only 7 W at rated current