Impact of Air Gaps into the Ferrite Core of Inductive Wireless Power Transfer Systems

Wireless Power Transfer has become a technology of great interest, as it enables static and dynamic charging of electric vehicles. However, the manufacturing of the system can lead to possible design solutions that could have a negative effect on the performance. The ferrite core above the coils could be composed of an array of tiles with one or more holes for fixing, resulting in air gaps within and between adjacent tiles, the latter due to irregularities in the edges of the tiles. The aim of this work is to quantify the effect of such manufacturing limitations on system performance, by means of proper simulation models. The results highlight that the fixing holes within the tiles do not significantly affect the operation and the performances of the WPT system. On the contrary, the air gaps between the tiles might have a significant effect on system performance, depending on their thickness and their length along the edges. However, a partial contact (30% of each side) between adjacent tiles is enough to not significantly alter the properties and the performance of the system.