Increasing Power Transfer Capability of Wireless Battery Charger Under Misalignment Conditions

An i nductive power transfer system usually implies the existence of coils that are coupled without the presence of a magnetic core. As a result of the lack of a magnetic core in the system, the reactive power necessary for the operation of the system is significant. One of the ways of compensating for the system’s need for reactive power is by placing a third winding with an accompanying resonant circuit. This paper describes how the construction and position of the third winding influence the power transfer capability of the system and how they can be used to reduce the influence of the potential misalignment between the primary and secondary coils. A system is built and tested with a power transfer of up to 8 kW over an air gap of 40 mm. In the worst case of misalignment, an increase of 130 % in the power transfer capability is achieved.