Impedance-matched wireless power transfer systems using an arbitrary number of coils with flexible coil positioning

This letter presents a new analytic design method for impedance-matched wireless power transfer (WPT) systems using an arbitrary number of coils. For deriving the impedance matching condition, we have used an equivalent circuit of the WPT system. It allows us to avoid solving voltage-current equations for the actual circuit. For verifying the proposed design method, an impedance-matched WPT system with one repeater coil has been designed and fabricated. This letter also shows that the distances between the coils can be varied maintaining the impedance-matching performance, and the distances can be determined analytically using the presented design method. Application of the presented design method can be found in designing WPT systems that require flexible coil positioning.