Improved efficiency of inductive power transfer in misalignment conditions with multi coil design

Abstract

In charging process of electric vehicle, a misalignment between the transmitter (Tx) and receiver (Rx) coupling structure decreases the efficiency of the wireless power transfer. In inductive power transfer system, misalignment reduces the effective coupling between the Tx and Rx coils. In this work, based on previous multiple coil structures, a new multi coil design in proposed to increase the efficiency of the power transfer. Here, a multi coil structure with two rectangular and four spiral coils is designed with the overall dimension of the coil structure 26.5 cm x 36.5 cm. The measurement shows, that for coil distance below 10.3 cm and a lateral misalignment of maximal 10 cm (27.4%), the efficiency of the designed multi coil structure is better compared to previous coil structures. However for larger coil distance or larger misalignment, the efficiency of the new coil structure deteriorates significantly.