Abstract
In this article, we propose the side-placed negative-permeability metamaterial (NPM) and zero-permeability metamaterial (ZPM) in the wireless power transfer (WPT) system to simultaneously enhance the level of efficiency and meet the electromagnetic field (EMF) safety regulations. A theoretical analysis, simulation, and experiment are conducted to verify the feasibility of the proposed system model. Based on the principle of magneto-inductive waves (MIWs) and the shielding theory, the transmission characteristics of the WPT system without and with two NPM slabs, two ZPM slabs, and the combination of NPM and ZPM slabs are analyzed. The results demonstrate that the ZPM slabs and the combination of NPM and ZPM slabs have a high efficiency improvement when the transfer distance is located under 40 cm and exceeds 40 cm, respectively. Both methods can control the EMF leakage. Moreover, the side-placed metamaterial exhibits tolerance to the misalignment of the coil. Finally, comparative studies on the ZPM slab and aluminum are carried out. The experimental and simulation results show that the ZPM slab performs better than aluminum.
Highlights
With the constant development of the electrification of society, consumer devices have become more popular, new requirements for charging methods have emerged
Through the simulation and experimental results, we show that the sideplaced zero-permeability metamaterial (ZPM) slabs and the combination of negative-permeability metamaterial (NPM) and ZPM slabs are excellent choices for increasing efficiency and
It is shown that the magnetic fields between the air and ZPM are almost prohibited, and the magnetic fields in the transport channel of the wireless power transfer (WPT) system are converging to the Rx coil
Summary
With the constant development of the electrification of society, consumer devices have become more popular, new requirements for charging methods have emerged. In reality, when WPT technology is applied to supply power to equipment, we need to consider a method of enhancing the efficiency while simultaneously meeting EMF safety requirements while not affecting the wireless transmission path. When the side-placed NPM slabs are vertical to the system, the ability to propagate magneto-inductive waves (MIWs) has been shown, resulting in the enhancement of the efficiency [23]-[27]. It is shown that the magnetic fields between the air and ZPM are almost prohibited, and the magnetic fields in the transport channel of the WPT system are converging to the Rx coil It is very useful for the side-placed ZPM slabs to enhance the efficiency, while maintaining the safety. Where k0 is the wavenumber in vacuum, k represents the wave number parallel to the metamaterial, and t is the thickness of the metamaterial
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