A magnetically enhanced wireless power transfer system for compensation of misalignment in mobile charging platforms

Misalignment in wirelessly charged electric vehicles is unavoidable as perfect alignment of the pickup coil on the electric vehicle with respect to transmitter is quite difficult. Notably, even a small coil misalignment leads to significant reduction of the effective coupling. Due to which this problem is of quite significance for maintaining high efficiency over the complete misalignment range. This paper presents a two auxiliary coil solution for compensating misalignment in lateral and longitudinal directions. Two auxiliary coils are mounted on the receiver; both auxiliary coils are mounted perpendicular to each other. Auxiliary coil mounted on lateral direction compensates the drop in flux due to lateral misalignment and auxiliary coil mounted in longitudinal direction compensates for drop in flux due to longitudinal misalignment. Output of both auxiliary coils is then connected to the respective rectifier and the outputs of rectifiers are connected in parallel through inductors. Total addition of current due to auxiliary coils and receiver coil is provided to the load. To verify the proposed concept, simulation is performed in ANSYS Maxwell and PLECS. Further, an experimental prototype of a 250W system is developed and experimental results are provided to verify the effectiveness of the concept.