FOM-rd Plane: An Effective Design and Analysis Methodology for Resonant Energy Link in Inductive Power Transfer

Resonant energy link plays a vital role in the performance of inductive wireless power transfer (IPT) system, whereas the effective design method has not been actively investigated from a perspective of power conversion circuit. This paper presents a new graphical design method based on FOM-r(d) plane which gives convenience as well as insight to circuit designers. The proposed FOM-rd plane can estimate the voltage gain and efficiency according to the variations of magnetic coupling coefficient and the load resistance. Furthermore, the gain bifurcation phenomenon which hampers soft-switching operation and complicates the output voltage control can be readily avoided from the operating region. An energy link for 200 W wireless power transfer system in series-series configuration has been designed and constructed by the proposed method, and its hardware test result verifies the usefulness of the proposed method.