Elevating Performance of Magnetically Coupled WPT Systems Through Compact Metamaterial Integration

Abstract

This work presents a compact metamaterial (MTM)-integrated near-field wireless power transfer (WPT) system with enhanced performance. The WPT is designed by magnetically coupling two slotted ground plane-based resonators oscillating at 433 MHz. The WPT performance elevation is achieved through a proposed systematic design approach encompassing two key stages. In the first stage, the plus-shaped fractal slot-based resonators are analyzed, revealing that successive iterations expand the magnetic field ($\mathbf {B}$) area and consequently extend the power transfer distance ($d$). In the second stage, MTM with dimensions of$30 \times 30$mm$^{2}$is integrated into the WPT system. The size of MTM does not exceed the area of the resonator, ensuring that the overall volume remains compact. The MTM is arranged in a configuration of$3 \times 3$unit cells, with the latter being designed using octagonal spirals and exhibiting a permeability of$-1$at 433 MHz. The MTM is carefully positioned between the coupled resonators in order to effectively mitigate the$\mathbf {B}$leakage and increase coupling. As a result, the power transfer efficiency ($\eta$) and$d$are both improved, achieving$\eta$of 81% at$d=39$mm. Experimental validation and benchmarking against state-of-the-art systems show a FoM reaching 1. The WPT performance was evaluated in practical application scenarios, considering the effects of misalignment and the presence of nearby objects. Overall, the obtained results confirm the effectiveness of the proposed systematic design approach, marking a significant advancement in WPT technology.

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