Wireless Power Transfer Based on Microwaves and Time Reversal for Indoor Environments

Abstract

Resorting to power accurate delivery for wireless power transfer (WPT) based on microwaves, a theory and method based on time reversal (TR) for WPT in 3D indoor environments are presented in this paper. Conventional WPT methods have the limitations of requiring that the elements on power source array (PSA) must have the same structure and regular arrangement. Unlike those conventional methods, the PSA used in this paper can be constructed by any omnidirectional antenna elements with any structure and any arrangement, whose principles are based on the auto-match of antenna radiation and environment adaptability of TR. Moreover, compared with those conventional methods, which perform complex multi-objective optimizations of beam pattern cost-functions at each frequency for getting excitation of PSA, the proposed algorithm can obtain PSA's excitation over a wide frequency range only by a single run of TR and Fourier transform operations. In addition, by weighting the time reversed charging request signal from powered devices, the interference caused by different observing elevation angles and amplitude difference among each channel can be suppressed effectively. At last, multi-powered devices placed arbitrarily can be charged simultaneously, and get similar power from PSA without power unfairness by our proposed algorithm. INDEX TERMS 3D indoor environment, auto-match of antenna radiation and channel, microwave, time reversal, wireless power transfer.

Asynchronous Focusing Time Reversal Wireless Power Transfer for Multi-Users With Equal Received Power Assignment

“…If one wants to assign equal received power to the desired users and achieve the maximum transfer efficiency, only the phases of the focusing signals received by the selected users need to be optimized with the following equations. (20) For equal received power allocation, only phases ( 1, 2, , ) i iM   are the optimal variables and the amplitudes of selected users are set to 1, while others are set to 0. This means that the optimal transfer efficiency can not be achieved if only the amplitude is processed.…”

“…Another advantage of TR-WPT is that multi-users can be wirelessly powered at the same time [20]. The basic idea for multi-user power transfer is to generate a number of time-reversal single-point focusing fields within the power transfer area.…”

Transient Electric Field Shaping With the Linear Combination of Configuration Field Method for Enhanced Spatial Control of Microwave Plasmas

“…The spatial and temporal focusing properties of TR were demonstrated for microwave applications by Lerosey et al [19]. They have since been applied for wireless communications [20], [21], source localization [22], and wireless power transfer [23], [24]. In a TR experiment, the field radiated by a source is first recorded using an array of antennas known as the time reversal mirror (TRM) [25].…”

Compact Microwave Rectifier with Wide Input Power Dynamic Range Based on Integrated Impedance Compression Network

“…Microwave power transmission (MPT) is a promising technique to prolong life cycle of battery in electronic devices [1], [2]. Researches on MPT technology are carried out for different applications, such as bio-medical equipment [3], sensors for Internet-of-Things [3] and power transmission by solar satellite [5].…”