Pushing to the Distance Boundary of Inductive Wireless Power Transfer

Wireless power transfer technology constantly involves tradeoffs among transfer distance, power and efficiency. Near-field WPT systems are ideal for high power and efficiency, while far-field WPT prevails at long distance. Pushing to longer distance of inductive wireless power transfer by increasing the coupler size will inevitably be impacted by electromagnetic radiation. This paper aims to push the boundary of near-field inductive WPT to a much longer distance by operating at a higher frequency but without incurring too much radiation effect. Both fundamental and physical coil design considerations are given according to analytical and finite element full-wave simulations, and a GaN-based power electronics system is presented. Preliminary experimental results achieved 300W output power over a 2-meter distance, with a DC-to-DC efficiency of 62%.