Optimal Design of Highly Efficient and Highly Compact PCB Winding Inductors

In industrial power electronic systems, power density and costs are key design criteria. Therefore, very high switching frequencies are commonly used in order to minimize the volume of the inductive components. However, especially in high-current applications, the well-known skin and proximity effects as well as the fringing field around the air gaps of inductors, impede the design of these components, as they are usually all reducing the effective cross-sectional area of solid inductor windings. Consequently, litz wire windings would have to be used, which is often impossible, mainly due to cost reasons. This paper introduces a new, simple and efficient approach on how to integrate inductor windings directly into the PCB, by mitigating the high-frequency losses due to a relocation of the air gap. In this way, its fringing field can be used to partly compensate the parasitic magnetic fields causing the skin and proximity effects. Hence, very low production costs and high power densities can be achieved. In a first step, simple design guidelines are derived and verified by means of simulations. Finally, a possible hardware implementation of the proposed concept is presented.