Design of an efficient contactless energy transfer system for battery charger

Based on mutual inductance model, this paper proposed three system design factors, i.e., coupling coefficient k, energy receive circuit´s quality Qs, and the self inductance ratio of primary and secondary coil n, which highly simplified the model of contactless energy transfer system(CETS). It is meanful to express the important characteristic parameters (transfer efficiency, voltage stress on compensation capacitors, voltage gain of CETS, ect.) as functions of the three factors, for it enables us to select operating frequency, turn ratio of coils and compensation capacitors much more easily than traditional design methods. Experimental results of a 48V/20AH battery charger system validated the design theory.