Dual-purpose non-overlapped coil sets as foreign object and vehicle location detections for wireless stationary EV chargers

For commercialization of wireless stationary EV chargers, the foreign object detection (FOD) on a power supply coil and the location detection (LOD) of electric vehicles (EVs) are needed. In this paper, a dual-purpose non-overlapped coil sets as both FOD and LOD are newly proposed. Not only the existence of conductive object debris on a power supply coil but also the location of them are determined by an induced voltage difference of the coil sets. By measuring the induced voltage of the coil sets, displacements between a power supply coil and a pick-up coil can be also found to inform drivers of their EV alignments. Moreover, the proposed FOD and LOD methods make no contribution to any power losses. The proposed non-overlapped coil sets have been demonstrated by simulations and experiments for a prototype coil set. Throughout experiments, the induced voltage difference of a coil set shows 2.19 mV (ideally zero) without foreign objects while the induced voltage difference significantly increases by 78.2 mV, which is about 35 times of the value without objects, when eight conductive coins are located on a power supply coil. Also, it is found that the LOD can be achieved by measuring the variation of the induced voltages in coil sets when a pick-up coil moves on a power supply coil.