Resonance and Distance Insensitive Wireless Power. Transfer with Parity-Time Symmetric Duffing Resonators

In this paper, a concept of parity-time (PT) symmetry from quantum physics, which enables constantefficiency energy transfer between linear LC resonators within a definite range of transfer distance, is extended to WPT systems with Duffing resonators. By considering nonlinear resonance properties and introducing complex variables, the coupled-mode models of WPT systems with Duffing resonators are derived. Thereafter, transfer performance in the steady state is investigated in an explicit way according to coupled-mode theory (CMT) as well as the parameter conditions of an exact PT symmetric phase. In comparison with PT symmetry-based WPT systems with linear LC resonators, WPT systems with PT symmetric Duffing resonators exhibit combined features of distance and resonance detuning insensitivity. Finally, a system is designed to maintain constant transfer efficiency of 84% with a resonance detuning tolerance of nearly 5%, which is confirmed by simulation results.