WIRELESS POWER TRANSFER VIA MAGNETIC RESONANT COUPLING

Abstract

Small electronic devices such as smartphones and tablets are increasingly rooted in everyday life. To eliminate cable mess and make it easy to stay connected with always-charged electronic devices, magnetically coupled resonant wireless power transfer (MCR-WPT), which can power electronic devices wirelessly at midrange distances, is the most practical solution. A long-standing goal has been to transfer power wirelessly over a large area with a compact and easy-to-implement receiver that can be used for electronic and medical devices. However, existing technology falls short of this goal. MCR-WPT systems are bulky and highly sensitive to axial and lateral misalignment, and MCR-WPT systems are limited to the size of the transmitter. Furthermore, simply exciting an MCR-WPT array system cannot address the issue due to transfer efficiency fluctuations over the covered area. The transfer efficiency of the system drops dramatically when the receiver is not perfectly aligned with the transmitter resonator and is limited to the size of the transmitter. This thesis explores several novel topologies and models of non-planar and planar transmitter, receivers for an MCR-WPT system. The proposed MCR-WPT can achieve higher transfer efficiency compared to previous works of comparable size and transmission distance. Two novel techniques are proposed to increase the quality factor of resonators, and various planar WPT systems are studied regarding size constraints. The second contribution of this thesis is to overcome the problem of misalignment between the transmitter and receiver resonators. To address this issue, a planar MCR-WPT array system consisting of two to nine transmitting array resonators using a novel feeding structure is proposed. The aim is to have a simple and easy-to-implement structure with a transfer efficiency that is less sensitive to axial- and lateral-misalignment. The proposed MCR-WPT system consists of five subsystems (an amplifier, MCR-WPT, a rectifier, a DC-to-DC converter, and a load) which are applied to verify the performance of the proposed WPT systems. It is shown that the proposed systems are more desirable and feasible to implement inside walls and under desks to charge small electronic devices anywhere inside its confines.