Power pad design and optimization for contactless electric vehicle battery charging system

Inductive power transfer is a near-field technology for the transmission of electric energy via oscillating magnetic fields by inductive coupling between coils. The main issues related to this technology are the large air gap between coils and the lack of any ferromagnetic core, resulting in a weak coupling between transmitter and receiver coils and large leakage flux. Loosely coupled inductive power transfer systems have to be carefully designed to deliver power with high efficiency over relatively large air gaps, also having good tolerance to distance and misalignment. In the field of electric vehicles, contactless battery charging is a challenging solution to overcome mechanical hassles with charging cables and the long charging times. This paper deals with the optimized design of circular magnetic power pads for the contactless charging of electric vehicles. The paper investigates, by means of simulations through finite element software, how design parameters influence on the coupling and the power transmission.