基于负磁导率电磁材料的WPT效率提升研究

Study of efficiency improvement for wireless power transfer based on negative permeability metamaterials

为提高无线电能传输(wireless power transfer, WPT)系统的传输效率,提出一种由六边形双层螺旋线圈阵列构成的蜂巢结构的负磁导率人工电磁材料(negative permeability metamaterials, NPM).通过对NPM基本单元的参数优化,将其负磁导率工作频率调节至6.78 MHz.仿真表明了该NPM的磁场再聚焦及增强特性,实验测得NPM在6.2～6.7 MHz频段处其磁导率为负.搭建了一个两线圈结构的WPT系统,验证了该NPM的传输效率提升性能及在WPT系统中的结构、位置特性.结果表明:两层结构的NPM在WPT系统的中间位置具有最优的效率提升效果,可将传输距离为30 cm的WPT系统的传输效率从1%提升到12.5%.

In order to enhance the transmission efficiency of wireless power transfer （WPT）, a negative permeability metamaterials （NPM） with a structure of honeycomb composed by units of hexagon-shaped spirals copper is proposed in this paper. The unit parameters of the NPM are optimized, to make sure the negative permeability at 6.78 MHz. The S-parameters of the designed NPM are measured by a network analyzer and the permeability is extracted. It shows that the honeycomb NPM have a negative permeability at 6.2-6.7 MHz. A two-coil WPT is setup and the transmission efficiency of WPT embedded with NPM at the different position and with different structure are investigated. The measured results show that the 2-slab honeycomb NPM have a good performance compared with the 1 - slab NPM, and the efficiency can be increased up to 12.5% at a distance of 30 cm.