Tunable Metamaterial Slab for Efficiency Improvement in Misaligned Wireless Power Transfer

Lee, Woosol; Yoon, Yong-Kyu

doi:10.1109/lmwc.2020.3015680

Cited by 32 publications

(13 citation statements)

References 12 publications

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“…Specifically, peripherical unit-cells will respond to the impinging radiation with a lower current than the central ones, leading to a reduction in power transfer efficiency and lower misalignment robustness for WPT systems 55 . In some recent publications, the ability to combine two different types of unit cells within a magnetic metasurface to accomplish field focusing or misalignment robustness in WPT applications has been demonstrated 38 , 39 . In addition, another manuscript proposed an eigenmode analysis to modulate the magnetic field distribution by geometrically modifying the structure and, thus, the self-resonance of the elements 52 .…”

Section: Introductionmentioning

confidence: 99%

“…Currently, various types of shapes and configurations of resonating spirals and other printed unit-cells have been studied to demonstrate metasurfaces' ability to enhance the mutual coupling between magnetic dipoles. Consequently, the inductive link power transfer efficiency, the working distance, and the misalignment robustness of WPT systems can be significantly improved 14,[34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49] . In 42,46,47,[50][51][52] , it was also proved how metasurfaces could be employed to lower E-field peaks, therefore, accomplishing high safety standards for the WPT system while guaranteeing an enhanced power transfer efficiency level with respect to a conventional driver-receiver system.Typically, the design and analysis of metamaterials and metasurfaces are based on the classical electromagnetic theory where the slab is considered infinite, and uniformly excited by a normal incident plane wave 31 .…”

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confidence: 99%

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Spatial filtering magnetic metasurface for misalignment robustness enhancement in wireless power transfer applications

Lazzoni

Brizi

Monorchio

2023

Sci Rep

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In this paper, we present the design of spatial filtering magnetic metasurfaces to overcome the efficiency decay arising in misaligned resonant inductive Wireless Power Transfer systems. At first, we describe the analytical framework for the control of currents flowing on a finite-size metasurface, avoiding classical truncation effects on the periphery and opportunely manipulating, at the same time, the spatial magnetic field distribution produced by the closely placed RF driving coil. In order to validate the theoretical approach, we conceive a numerical test case consisting of a WPT system operating at 12 MHz. By performing accurate full-wave simulations, we prove that inducing a uniform current in the metasurface results in a more robust WPT system in terms of misalignment with respect to conventional configurations, also including standard metasurfaces. Therefore, while the use of metasurfaces in WPT systems has been already demonstrated to be beneficial in terms of efficiency enhancement, we confirmed that a proper control of the metasurfaces field filtering response can be advantageous also for the misalignment issue. Notably, the free space wavelength at the operating frequency (12 MHz) is 25 m, whereas the proposed metasurface dimensions are only 0.0024λ × 0.0024λ. Despite the extremely reduced dimensions, the spatial magnetic field distribution produced by the closely placed RF driving coil can be nevertheless opportunely manipulated. Finally, experimental measurements conducted on fabricated prototypes validated the numerical results, demonstrating the effectiveness of the proposed approach. These achievements can be particularly helpful in WPT applications where the position of driving and receiving coils frequently changes, as in consumer devices and biomedical implants.

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Section: Introductionmentioning

confidence: 99%

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confidence: 99%

Spatial filtering magnetic metasurface for misalignment robustness enhancement in wireless power transfer applications

Lazzoni

Brizi

Monorchio

2023

Sci Rep

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“…Specifically, for the efficient utilization of space, modern commercial electronic devices change their form factors and are deformed, folded, and rolled, e.g., foldable, flipped phones, and rollable televisions, without degrading the performance of the electronic devices while promoting their portability. In this respect, previously demonstrated WPT systems utilizing MTMs have not been compliant with this trend, as their structures have been thick, huge, or rigid [ 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 ] for modern electronic devices. In our previous work [ 14 ], a rollable MTM screen for a high-efficiency WPT system was designed at 4.5 MHz, where only the MTM screen was rollable, while the source, Tx, Rx, and load coils were made of non-planar and non-rollable rigid structures.…”

Section: Introductionmentioning

confidence: 99%

High-Efficiency Wireless-Power-Transfer System Using Fully Rollable Tx/Rx Coils and Metasurface Screen

Lee

Yoon

2023

Sensors

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This work presents a high-efficiency reconfigurable wireless-power-transfer (WPT) system using fully rollable Tx/Rx coils and a metasurface (MS) screen working at 6.78 MHz, for the first time. The MS screens are placed between the Tx and Rx to magnify the power-transfer efficiency (PTE) of the WPT system. The proposed MS-based WPT can be rolled down or rolled up as required, which allows end-users to use the space more flexibly. In the measurement results, the PTE of the WPT is improved from 13.32% to 32.49% at a power-transfer distance (PTD) of 40 cm with one MS screen, 5.42% to 42.25% at a PTD of 50 cm with two MS screens, 1.78% to 49% at a PTD of 60 cm with three MS screens, 0.85% to 46.24% at a PTD of 70 cm with four MS screens. The measured PTE results indicate that the demonstrated MS screens are greatly effective for magnifying the PTE and the PTD of the WPT. In addition, the measured PTE results in the misaligned condition verify that the MS screens also help increase the PTE of the WPT even in the misalignment condition.

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“…At present, many researchers proposed MRCWPT systems to further enhance PTE and extend the distance of the system. A kind of method by adding relay resonators is proposed in 17 . It is obvious that the distance and PTE of the system are extended.…”

Section: Introductionmentioning

confidence: 99%

Wireless power transfer system with enhanced efficiency by using frequency reconfigurable metamaterial

Shan

Wang

Cao

et al. 2022

Sci Rep

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The wireless power transfer (WPT) system has been widely used in various fields such as household appliances, electric vehicle charging and sensor applications. A frequency reconfigurable magnetic resonant coupling wireless power transfer (MRCWPT) system with dynamically enhanced efficiency by using the frequency reconfigurable metamaterial is proposed in this paper. The reconfigurability is achieved by adjusting the capacitance value of the adjustable capacitor connected in the coil of the system. Finite element simulation results have shown that the frequency reconfigurable electromagnetic metamaterial can manipulate the direction of the electromagnetic field of the system due to its abnormal effective permeability. The ultra-thin frequency reconfigurable metamaterial is designed at different working frequencies of 14.1 MHz, 15 MHz, 16.2 MHz, 17.5 MHz, 19.3 MHz, 21.7 MHz and 25 MHz to enhance the magnetic field and power transfer efficiency (PTE) of the system. Frequency reconfigurable mechanism of the system with the frequency reconfigurable metamaterial is derived by the equivalent circuit theory. Finally, further measurement which verifies the simulation by reasonable agreement is carried out. PTE of the system by adding the metamaterial are 59%, 73%, 67%, 66%, 65%, 60% and 58% at different working frequencies. PTE of the system with and without the metamaterial is 72% and 49% at the distance of 120 mm and the frequency of 15 MHz, respectively.

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Tunable Metamaterial Slab for Efficiency Improvement in Misaligned Wireless Power Transfer

Cited by 32 publications

References 12 publications

Spatial filtering magnetic metasurface for misalignment robustness enhancement in wireless power transfer applications

Spatial filtering magnetic metasurface for misalignment robustness enhancement in wireless power transfer applications

High-Efficiency Wireless-Power-Transfer System Using Fully Rollable Tx/Rx Coils and Metasurface Screen

Wireless power transfer system with enhanced efficiency by using frequency reconfigurable metamaterial

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