Accurate Design of Deep Sub-Wavelength Metamaterials for Wireless Power Transfer Enhancement

Abstract

Deep sub-wavelength metamaterials for a wireless power transfer system (WPT) is still a challenge in design and optimization. We propose a large capacitor spiral metamaterial (LCSM) which involves inherent advantages of low operating frequencies and compact structures. The ratio of electromagnetic wavelength to the metamaterial scale can easily reach 1000 at the operation frequency of several megahertz. A hybrid search method, which combines a modified simulated annealing algorithm and a differential evolution algorithm, is applied to the accurate and automatic design of LCSM. The permeability of LCSM is evaluated by finite element analysis and then verified by experimental results. Finally, a small-size WPT system working at 6.78 MHz was constructed to evaluate LCSM. The results show that LCSM can enhance the transfer efficiency of the WPT system from 5.54% to 22.40% at a transmission distance of 15 cm.

Development and prospects of metamaterial in wireless power transfer

“…1. Accurate establish the system model and calculate the electrical parameters [87] The structure parameters of the metamaterial are optimized by the modified simulated annealing algorithm.…”

“…Korea Advanced Institute of Science and Technology [63,70] Kyung Hee University [49, 64-68, 77, 78, 93, 94, 98, 109] Huazhong University of Science and Technology [52,62,82,[117][118][119][120][121] Xidian University [48,101,103] Shanghai Jiao Tong University [45,51,67,87,100] Mitsubishi Electric Research Lab [8,37,98,99] Hong Kong Polytehnic University [114,115] Carnegie Mellon University [80] Duke University [40,80] Nevertheless, the above-mentioned metamaterials with the planar structure are not appropriate to the application of nonstreamlined devices, such as autonomous underwater vehicles, wearable devices. The flexible metamaterial will be a potential solution because of its robustness and low cost.…”

“…In [86], the efficiency improvement of the WPT system with the metamaterial is verified by the equivalent circuit. A hybrid search method for optimizing MHz metamaterial has been proposed in [87,88]. The modified simulated annealing algorithm is applied to optimize the high-sensitive parameters (the number of turns, outer length of the spiral, and thickness of substrate) of metamaterials.…”

A Review of Metamaterials in Wireless Power Transfer

“…Ref. [90,91] improved the metamaterial unit cell's equivalent capacitance and inductance by connecting the upper and lower metal spirals through The use of metamaterials in WPT systems must consider their volume, frequency, and loss. The most commonly used metamaterial structure is the metallic graphic structure based on Pendry's proposed LC resonant cell array, with split ring resonators (SRRs) and spiral resonators (SRs) as the most typical artificial structural units.…”

Broadband and precise reconfiguration of megahertz electromagnetic metamaterials for wireless power transfer

“…As the main technical indicators, the transmission distance and the transmission efficiency of a WPT system are strongly dependent on the position and the configuration of the transmitting (Tx) coil and the receiving (Rx) coil [7]. On the premise of ensuring sufficient distance between the two coils, one of the most commonly used methods is to insert an electromagnetic metamaterial [8,9] (EMM) slab between the two coils [10][11][12] (see figure 1(a)), utilizing the superlens effect of EMM to enhance the transmission efficiency.…”