Contactless power transfer systems using series and parallel resonant capacitors

A new contactless power transfer system using series and parallel resonant capacitors is described. If the primary series resonant capacitor and the secondary resonant capacitor are set proper values, the equivalent circuit of the transformer with these capacitors becomes very simple at the resonant frequency. Ignoring the winding resistance and the core loss, the equivalent circuit is the same as an ideal transformer. Therefore the circuit analysis is easy, and if the input voltage is constant, the output voltage is also constant regardless the output current. The paper describes the determination of the series and the parallel capacitor values, the derivation of the equivalent circuit and the test results which shows the usefulness of the new contactless power transfer system.