Minimizing winding losses in foil windings using field shaping techniques

High frequency foil windings offer a good solution to realize high power/high frequency magnetic components. The surface area available for cooling is quite large thus improving the thermal capacity of these windings and allowing higher current densities. However, at high frequencies, additional losses are incurred within foil windings due to the eddy currents induced by skin, proximity, fringing and other AC effects. In addition, the winding structure greatly affects the distribution of losses within the windings. This paper presents a technique to reduce high frequency AC losses in foil windings. By shaping and controlling the field distribution in a given foil design, the current distribution can be improved which results in an improvement in the winding losses