Maximizing Received Energy in Magnetic Resonance Wireless Power Transfer Using Feedback

Abstract

This paper considers the effect of variation of load resistance, as a function of the amount of charged energy in battery, in magnetic wireless power transfer. We calculate load resistance as a function of time, and show that load resistance increases as the receiver acquires energy over time. Unlike the previous studies that considered the resonance frequency of transmitter and receiver as a fixed value, so that it remains unchanged once it has been set, it is shown that the resonance frequency changes as load resistance varies. To avoid performance degradation due to the unmatched resonance frequencies between transmitter and receiver, we employ feedback from the receiver. Considering the cost of feedback, there is a trade-off between the number of feedbacks that the receiver sends and the collected energy at the receiver. For a point-to-point system model, the optimal feedback interval that maximizes the received energy is found. The numerical results show that the proposed protocol collect more energy compared to the conventional magnetic wireless power transfer systems.