Backscattering technique for real-time monitoring of the received power in wireless power transmission systems

摘要

A wireless power transmission system with a dynamic, real-time feedback for impedance matching is presented. The AC signal at the receiver node is rectified, the resulting DC signal is passed to a voltage controlled oscillator which drives a high-frequency analog switch. When in the ON state, the switch shorts the terminals of the receiver coil, dramatically changing the impedance seen by the transmitter coil. This change is detected on the transmitter side as the backscattered signal. Variation on the frequency of the backscattered signal can then be used to affect changes in the power source amplitude or the transmission side matching network to optimize the transmission power efficiency. The proposed feedback system is implemented with planar spiral coils on PCBs, and the effect of distance variation between the coils and as a consequence, DC voltage variation on the rectifier output is measured using voltage signal spectrum in the transmitter node at 1 MHz. (c) 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:2980-2983, 2016