【作者】 杨强；

【导师】 熊汉；

【作者基本信息】 重庆大学 ， 信息与通信工程， 2024， 硕士

【摘要】 远距离无线能量传输(Wireless Power Transfer,WPT)是电能输送过程中一种潜力巨大的能源供应方式。与传统的电能传输方法相比,WPT因其更高的灵活性和便捷性,将引发电能传输方式的根本性技术革命。在微波辐射式WPT系统中,微波能量接收(Microwave Power Reception,MPR)扮演着至关重要的角色,而一个高效可靠的MPR设备是实现系统最大化传输效率的关键。通过对国内外研究现状进行调查分析后发现,当前针对MPR技术的研究面临设计复杂性高、能量收集效率低及应用成本昂贵等挑战。鉴于这些挑战,本文探索了基于相位梯度超表面(Phase Gradient Metasurfaces,PGMs)对电磁波进行自由控制的新策略,对MPR技术进行了以下研究:(1)设计了一款中心频率在5.8 GHz的MPR复合PGMs阵列。该阵列通过余弦相位梯度指数调制,实现了对入射平面波的极化不敏感转换为中心聚焦的表面波,并通过全向天线将能量馈送至整流器,完成从射频到直流(Radio Frequency to Direct Current,RF-DC)的转换。仿真结果显示,阵列可在不同极化状态的平面波激发下有效地产生表面波,达到66.52%的能量收集效率。实验结果表明,该阵列可实现59.91%的能量接收效率和34.83%的RF-DC转换效率。此设计免除了对大量整流部件和复杂匹配网络的需求,提供了一种创新的MPR解决方案。(2)设计了三款用于MPR的复合反射相位梯度超表面(Reflectance PGMs,R-PGMs)阵列。基于R-PGMs可实现平面波完美转换为表面波的研究理论,设计了一种具备高转换效率的R-PGMs阵列,可将入射波高效转换为表面波。并采用三种不同的表面波汇聚阵列和能量收集天线,周向引导表面波收敛至能量收集天线端口,再馈入整流电路,完成RF-DC转换。在5.8 GHz工作频点,仿真表明,R-PGMs阵列可实现高达97.85%的平面波-表面波转化效率,复合阵列可实现最高76.67%的能量收集效率。实验测试获得73.68%的能量收集效率和49.28%的RF-DC转换效率。该方案微波能量转换效率高,应用成本低,具备工程化应用价值,并为MPR设计提供了另一种新的思路和方法。(3)设计了一款对入射波极化不敏感的复合R-PGMs阵列。阵列工作中心频点为5.8 GHz,由中心旋转对称的超表面单元以中心位置为原点对称排列构成,实现反射相位梯度周向性分布,可将入射平面波高效转换为表面波并汇聚于其中心区域。采用水平全向天线引出表面波能量至单一整流器,完成RF-DC转换。仿真结果表明,复合阵列在圆极化平面波入射下,不同极化角度保持表面波激发并向中心区域传播,具有74.89%的平面波-表面波转换效率。实验测试表明,所提阵列可实现62.23%的能量收集效率以及39.96%的RF-DC转换效率。本工作进一步提升了极化不敏感PGMs微波能量接收器件的工作效率,并为R-PGMs阵列实现入射波的极化不敏感性提供了一种新的设计思路。更多还原

【Abstract】 Wireless Power Transfer(WPT)is a high-potential energy supply option for the transmission of electrical energy over long distances.Compared to traditional methods of electric power transmission,WPT is poised to revolutionize the fundamental technology of electric power transmission due to its higher flexibility and convenience.Specifically,in microwave radiation-based WPT systems,the Microwave Power Reception(MPR)is introduced for maximizing the transmission efficiency of the system as the indispensable part.Currently,the research on MPR technology is confronting challenges such as design complexity,low energy harvesting efficiency,and expensive application costs based on the comprehensive investigation of literatures.In spite of these challenges,a new strategy for free control of electromagnetic waves based on Phase Gradient Metasurfaces(PGMs)is explored in this thesis,and the following studies on MPR technology are conducted:A study on an array of MPR composite PGMs with a center frequency of 5.8 GHz is presented in order to address the need for a large number of rectifier components and a complex matching network in conventional MPR devices.Concretely,the array is insensitive to incident plane wave polarization through cosine phase gradient-index modulation,which converts the incident plane wave into a centrally focused surface wave,and the surface wave energy is fed to the rectifier through an omnidirectional antenna,completing the energy conversion from Radio Frequency to Direct Current(RF-DC).Simulation results show that the array effectively generates surface waves under excitation by plane waves of different polarization states,achieving an energy collection efficiency of 66.52%.Experimental results indicate that the array can achieve an energy reception efficiency of 59.91%and an RF-DC conversion efficiency of 34.83%.Furthermore,this design provides an innovative solution for MPR.A study on three composite Reflectance Phase Gradient Metasurface(R-PGMs)arrays for MPR is proposed to further improve the energy harvesting efficiency.Specifically,based on the research theory that R-PGMs can realize the perfect conversion of plane waves into surface waves,an array of R-PGMs with high conversion efficiency is designed to efficiently convert incident waves into surface waves.Subsequently,three different surface wave convergence arrays and energy harvesting antennas are proposed,which can circumferentially direct the converted surface wave energy to converge to the antenna ports and feed into a rectifier circuit to complete the RF-DC conversion.At a working frequency of 5.8 GHz,simulations show that the R-PGMs array can achieve a plane wave-to-surface wave conversion efficiency of up to 97.85%,and the composite arrays can achieve a maximum energy collection efficiency of 76.67%.Experimental measurements of the composite arrays obtain up to 73.68%energy harvesting efficiency and 49.28%RF-DC conversion efficiency.The design scheme offers high efficiency of microwave energy conversion and low application cost,which has the value of engineering application,as well as provides another new idea and method for MPR design.A study on an array of MPR composite R-PGMs which is polarization insensitive to the incident wave is designed to solve the issue of polarization sensitivity of R-PGMs arrays to the incident wave.Details,the array operates at a center frequency of 5.8 GHz,consists of rotationally symmetric metasurface unit cells arranged symmetrically with the center position as the origin,realizes the circumferential distribution of the reflection phase gradient,which can efficiently convert the incident plane wave into surface wave and converge the energy in the center region.Subsequently,a horizontal omnidirectional antenna is used to extract the surface wave energy to a rectifier for RF-DC conversion.Simulation results show that under circularly polarized plane wave incidence,the composite array maintains surface wave excitation and propagation towards the central region at different polarization angles,achieving the plane wave to surface wave conversion efficiency of 74.89%.Experimental tests reveal that the array can achieve the energy collection efficiency of 62.23%and the RF-DC conversion efficiency of 39.96%.This work further enhances the efficiency of polarization-insensitive PGMs MPR devices,more importantly,provides a new design idea for R-PGMs arrays to realize the polarization insensitivity of the incident wave.更多还原