Design of a contactless battery charger for cellular phone

In this paper, the design of a contactless charger for the lithium-ion batt ery of a cellular phone is presented. In this charger, the primary core of the transformer is in the charger unit and the secondary core is in the tel ephone. The gap (3 mm) between them is the thickness of the two plastic cas es. The transformer core design for the maximum coupling coefficient with t he size constraint on the secondary side is presented. Analysis of the prim ary-side series resonant converter with the loosely coupled transformer is performed, and the design optimization is presented. For the battery-chargi ng control, a simple control circuit is presented and its performance is ve rified from the experimental results.