Wireless Power Transfer Based on Metamaterials

Near-field-based wireless power transfer (WPT) technology is promising for many applications from consumer electronics to industrial automation. By utilizing resonant coupling, the power transfer can be made more flexible than conventional inductive WPT. However, the range is still limited. In this chapter, we report research work on near-field wireless power transfer (WPT) based on metamaterials-related ideas, aiming to extend the range and improve the flexibility of a WPT system. In the first part, we show that with a thin slab of metamaterial, the near-field coupling between two resonant coils can be enhanced; the power transfer efficiency between coils can also be greatly improved by the metamaterial. The principle of enhanced coupling with metamaterials will be discussed; the design process of metamaterial slabs for WPT will be introduced; experimental results on WPT efficiency improvement with metamaterials will also be presented. In the second part, inspired by metamaterials theory, we study the mutual coupling of an array of coupled resonators, and their application for WPT. We show that the range of WPT can be greatly extended with an array of coupled resonators. More importantly, the technology enables wireless power delivery to both static and mobile devices. The principle of this technology will be explained; analytical and numerical models will be introduced to estimate the performance of a WPT system based on an array of coupled resonators; methods for WPT optimization will be discussed and experimental results will be presented.