Optimizing Wireless Power Transfer: Advanced Multi-Relay-Coil Design with Chebyshev Filter Theory

In current wireless power transfer (WPT) research, one of the focuses is to make the transmission efficiency independent of distance and misalignments or electrically independent of mutual inductances. This paper presents a systematic way of designing such multi-relay coil WPT systems by developing the filter equivalence theory. High filter orders then correspond to multi relay coils for better performances. Simulations and measurements of the prototypes show the proposed design method can achieve a stable transmission efficiency within a defined range of mutual inductance variations, making the WPT system robust against changes in transmission distances and misalignments of the relay coils.