An ultra-compact transformer for a 100 W to 120 kW inductive coupler for electric vehicle battery charging

A new generation of electric vehicles is being developed. A key problem to be solved is that of charging the batteries. One means of charging uses inductive coupling. The inductive coupling approach is essentially a transformer with a removable primary winding connected to a charging unit via a cable. The secondary and the core of the transformer are on the vehicle. This paper presents an inductive coupler which has been demonstrated delivering from 100 W to 120 kW continuously at a frequency of 75 to 120 kHz. The transformer is very compact (<100 in/sup 3/). The primary purpose of this paper is a discussion of the power transformer. In addition the paper briefly addresses how the design of a magnetic device, which is usually a strictly technical exercise between engineers, is impacted when it is directly accessible to consumers in a mass market.