One-transmitter Multiple-receiver Wireless Power Transfer System Using an Exceptional Point of Degeneracy
Robust transfer efficiency against the various operating conditions in a wireless power transfer system remains a fundamentally important challenge. This challenge becomes even more critical when transferring power to groups of inductively coupled receivers. We propose a method for efficient wireless power transfer to multiple receivers exploiting the concept of exceptional points of degeneracy (EPD) in a self-oscillating system. In previous studies based on PT symmetry, a receiver's operation has been divided into two strong and weak coupling regimes, and the power transfer efficiency is constant in the strong coupling regime when varying the coupling factor. Here, the concept of strong and weak coupling and constant power efficiency is extended to a system of multiple receivers that do not follow PT symmetry. The transmitter has saturable nonlinear gain and the EPD is analyzed when the system oscillates after reaching saturation. We show that the important feature to have a roughly constant power efficiency, independently of the positions of the receivers, is the existence of an EPD that separates the weak and strong regimes. Our proposed method demonstrates a system with less sensitivity to the coupling change than a conventional system without EPD when the receivers and their couplings to the transmitter are not necessarily identical.