基于能量捕获和混合储能的微观网络能量最优分配算法

随着纳米技术和无线网络技术的快速发展,单个节点(设备)的微小尺寸和有限能量严重地限制了微观无线网络的应用。因此,在传统宏观网络节点储能结构单一和能量捕获技术不稳定的基础上,利用超级电容的快速充放电特性,提出了一种基于超级电容和电池的混合储能结构。在此混合储能结构的基础上,根据点对点的双工信道模型和能量传输损耗特性,建立了面向能量捕获的网络吞吐量模型和节点能量分配解析模型,并提出了相应的能量最优分配算法,实现了节点吞吐量的最大化。该算法根据节点捕获能量的时域分布,优化分配超级电容与电池的能量值;同时,采用最优传输功率与传输时间进行数据传输。实验结果表明,所提混合储能结构和能量分配算法能有效地提高节点的吞吐量。     

基于非理想电池模型能量收集无线传感器网络的链路调度

近年来,为了解决传感器节点能量受限问题,能量收集无线传感器网络成为了研究热点。针对传感器节点中电池存在容量有限、充放电损耗和能量泄漏等不足,提出了非理想电池模型的收集 使用 存储能量存储结构。综合路由、链路调度和能量分配3个方面建立数学模型,通过求解混合整数线性方程的方法得到最短帧长,从而提升网络吞吐量。仿真实验表明,充放电效率从0.6提高至0.9,帧长最多可减少48%;能量泄漏速率从0.04降低至0.01,帧长最多可减少33%;而扩大电池容量对帧长基本无影响。对比收集 存储 使用能量存储结构,帧长最多可减少11%,从而验证了利用所提方法,可以提高充放电效率,降低能量泄漏速率,大幅度提升网络吞吐量。     

Design and realization of an ultra‐low power sensing RF energy harvesting module with its RF and DC sub‐components

Herein, design, development, and analysis of ultra‐low power sensing energy harvesting modules and their subcomponents for ISM band applications have been studied with a holistic approach in an effort to achieve a feasible and high efficient RF energy harvesting performance. The complete harvester system designed and developed here consists of a zero‐bias RF energy rectifying antenna (rectenna), DC boost converters and energy storage super‐capacitors. Compared with the counterpart energy sources, the surrounding or transmitted wireless energy has low intensity which requires designs with high efficiency. To achieve a successful harvester performance, rectifier circuits with high sensitivity Schottky diodes and proper impedance matching circuits are designed. Dedicated RF signals at various levels from nanowatts to miliwatts are applied at the input of the rectenna and the measured input power versus the scavenged DC output voltage are tabulated. Furthermore, by connecting the rectifier to a high gain antenna and using a RF signal transmitter, the wireless RF power harvesting performance at 2.4 GHz was tested up to 5 m. The performance of the rectenna is analyzed for both low‐power detection and efficiencies. Impedance matching network is implemented to reduce the reflected input RF power, DC to DC converters are evaluated for their compatibility to the rectifiers, and super‐capacitor behaviors are investigated for their charging and storage capabilities. The measured results indicate that a wide operating power range with an ultra‐low power sensing and conversion performance have been achieved by optimizing the efficiency of the Schottky rectifier as low as ?50 dBm. The system can be used for battery free applications or expanding battery life for ultra‐low power electronics, such as; RFID, LoRa, Bluetooth, ZigBee, and low power remote sensor systems.