An electric vehicle charging system with 'universal' inductive interface

This paper describes the design of an inductive interface for an electric vehicle (EV) charging system based on a coaxial winding power transformer. The inductive interface is a separable transformer providing a means to 'plug-in' an EV without the need for metal-to-metal contact of exposed conductors. The proposed design is 'universal' in that dimensions can be selected which will accommodate more than an order of magnitude range of power ratings without imposing significant performance degradation. Interface geometry standardization and the configuration of the core and windings are shown to have important effects on the demands on the user, the EV infrastructure, the distribution of stationary and mobile weight, and the power electronic converter requirements. Design methodology for the proposed approach is summarized and experimental results of a laboratory prototype are presented to verify the design theory.>