【作者】 王宁；

【导师】 朱永；

【作者基本信息】 重庆大学 ， 仪器科学与技术， 2011， 博士

【摘要】 无线传感器网络是新一代的传感器网络,由部署在监测区域内大量的低成本微型传感器节点组成,通过无线通信方式形成的一种多跳自组织网络。无线传感器网络是21世纪高技术领域的四大支柱产业之一,具有可快速部署、可自组织、隐蔽性强和高容错性等优点,在军事、环境监测、医疗护理、工业等领域有着广泛的应用,其应用和发展将会给人类生活和生产的各个领域带来深远的影响。但是能源问题影响了无线传感器网络的性能和生存时间,是限制无线传感器网络应用和发展的关键问题。因此解决无线传感器网络的能源问题,延长其生存时间具有重要的经济和社会价值。研究人员提出的能量管理策略在一定程度上延长了无线传感器网络的生存时间,但是没能从根本上解决能源问题。随着自供能技术的提出,无线传感器网络的生存时间得到提高,但是对于一些没有环境能或是环境能很弱的场合,自供能技术的应用受到了限制,为此本文提出了无线传感器网络激光主动供能的方法。该方法利用激光进行远距离传能,在工作地点将集中的光能转换为分散的具有一定均匀性的空间光场,同时给多个无线传感器节点供能。该方法能够使无线传感器网络工作在大型地下油库和煤矿等没有环境能的高危场所,扩展了无线传感器网络的应用范围。本论文分析了无线传感器网络激光主动供能的光学模型,讨论了其特性;分析了硅太阳能电池的光电模型,在此基础上提出了利用纳米孔阵列薄膜提高太阳能电池性能的方法,并建立了纳米孔阵列增强型太阳能电池的光学模型;设计了基于激光主动供能的微功耗能量采集系统;在实验上验证了激光主动供能的可行性,验证了纳米孔阵列薄膜对太阳能电池性能的提高,验证了所设计的能量采集系统的原理和性能,具体内容包括:1)利用大气物理学中大气的吸收模型,分析计算了不同波长激光在大气中的传输特性,计算结果表明可见光激光和近红外激光在大气中的传输损耗较少,其中1064nm激光在进行远距离传输时能量损失最小。2)提出了两类将单点激光转换为空间光场的方法:激光激励荧光片法和激光-漫反射体法。分析了这两类方法的光学特性,计算了不同方法的效率和光场均匀性。其中激光激励荧光片的光场均匀性较好,但效率比较低;激光-漫反射体方法的效率较高,但光场均匀性较差。设计了两种能够提高激光利用率的光学结构,并对这两种光学结构进行了分析比较。3)由于激光主动供能得到的空间光场的光照度比较弱,因此本文分析了不同硅太阳能电池的弱光响应特性,并根据不同的激光波长选用不同的硅太阳能电池。同时设计了激光主动供能网络,该网络提高了激光主动供能的供能面积。4)太阳能电池的性能对整个供能系统的性能有着重要的影响,本文在分析太阳能电池光电模型的基础上提出利用纳米孔阵列薄膜作为太阳能电池增透膜来提高太阳能电池的转换效率。并利用严格耦合波理论分析了纳米孔阵列薄膜的光学特性,建立了纳米孔阵列增强型太阳能电池的光学模型,优化了纳米孔阵列薄膜的光学结构。纳米孔阵列薄膜的最优结构参数为:周期a=500nm,填充率f=0.2,厚度t=110nm。5)分析了商用太阳能电池无线节点的结构,在此基础上设计了基于激光主动供能的能量采集系统和无线传感节点。利用电压反馈法追踪太阳能电池的最佳工作点,提高了太阳能电池的充电效率,同时设计了低功耗的控制电路,实现了能量采集系统的高效低功耗。6)搭建了激光激励荧光片供能系统并测试了该系统的性能;搭建了激光-漫反射体供能系统并测试了该系统的性能。验证了所提出的激光主动供能系统的原理和可行性。7)利用微纳加工方法,在Φ200μm Si探测器的增透膜上制作了不同周期的纳米孔阵列,并搭建了相应的测试系统,实验结果表明:阵列周期为500nm时,器件的性能提高最为明显:短路电流在400nm-1100nm波段提高约为6%,在400nm-600nm波段提高约为15%;开路电压提高约为2%,纳米孔阵列薄膜能够很好的提高光伏器件的转换效率。8)加工调试了所设计的能量采集电路,测试了其性能,该电路能够在激光主动供能光照条件下(50-100μW/cm~2)很好的工作。加工了基于该能量采集电路的无线传感节点,在实际应用中,该节点能够进行准确的测量。更多还原

【Abstract】 As a new generation sensor network, wireless sensor network is a sort of multi-hop and self-organizing network, consisted of many low-cost micro sensor nodes displaced within the detection area, in the form of wireless communication. Wireless sensor network is one of the four high-tech fundamental industries with merits such as fast distribution, self-organization, strong hidden and high fault tolerance, and is widely utilized in domains of military, environment detection, medical nursery, industry and so on. The development and application of wireless sensor network will provide profound effects for fields of human life and production. However, energy issue, which affects wireless sensor network’s function and longevity, is the key problem that restrains the development and application of wireless sensor network. Therefore, it deserves significant economic and social value to solve the energy issue of wireless sensor network and lengthen its longevity.Researchers proposed a series of energy management strategies which just lengthened wireless sensor network’s longevity to a certain extent but didn’t radically settle down the energy problem. The longevity of wireless sensor network has been lengthened after self-power supply technology was proposed. However, in situations of no environment energy or low environment energy, the application of self-power supply technology is limited. On base of that, the dissertation proposed the method of wireless sensor network active laser energy supply. This method makes full use of laser to transmit energy wirelessly, by transforming the focused light energy into dispersed and well-distributed space light field in working sites to supply energy to multi-node wireless sensor. This method enables wireless sensor network to perform in high-risk places with no environment energy such as large-scale underground oil depots and coal mines, which extends the application domain of wireless sensor network. In this dissertation, the optical model of wireless sensor network laser active-power supply is established and its features are analyzed; the Si solar cell’s opto-electronic model is analyzed, on base of which the method of utilizing nano-hole array film to improve solar cell’s function is proposed and the optical model is set up; the micro energy depletion collecting system on base of laser’s active power supply is designed; in the experiment the feasibility of laser’s active power supply is tested and verified and the improvement of nano hole array film on solar energy battery’s function is also tested and verified, and the principle and performance of the designed energy collecting system is also tested and verified. The specific details include:1) Set up the physics model of laser transmission in the atmosphere according to Atmospheric Physics, analytically calculate the transmission performance of laser with different wavelength; the calculations indicate the transmission losses of visible laser and near-infrared laser in the atmosphere are less, and the transmission power loss of 1064nm laser is the least in far-distance transmission.2) Brought up forward two methods of transforming single-point laser into space light field: laser excitation phosphor and laser - diffuse reflector. Analyzed the optical properties of the two methods and calculated their efficiency and light field uniformity. Among the two methods, laser excitation phosphor is better in light field uniformity, but lower in efficiency; laser-whiteboard method is higher in efficiency but worse in light field uniformity. Designed and analytically compared two optical structures which can improve laser utilization.3) For the illumination intensity of the space light field from laser active-power supply was weak, the article mainly analyzed different Si solar cell’s low light response property and chose various Si solar cells in accordance with various laser wavelengths. Thus, the laser active power supply network, which enlarged the acreage of power supply, was designed.4) Since solar cell’s property is of criminal importance in the whole power supply system, the dissertation put forward taking nano-hole array film as solar cell’s antireflection coating to improve solar cell’s transmission efficiency on base of analysis of solar cell’s optical model. In addition, the dissertation analyzed the optical property of nano-hole array film in principle of Rigorous Coupled-wave theory, established the optical model of nano-hole array transparent film solar cell and optimized the optical structure of nano-hole array film. The optimized structure parameters of nano-hole array film are: period a=500nm, filling fraction f=0.2, thickness t=110nm.5) The dissertation analyzed commercial solar cell wireless nodes’structure, on base of which the power harvesting system and wireless nodes of laser active-power supply are designed. The voltage feedback method of tracking solar cell’s optimized working point enhanced solar cell’s charge efficiency. Meanwhile, the low power loss control circuit was designed, which realized high efficiency and low power loss in the power harvesting system.6) Two power supply systems were set up and their properties were tested, i.e. laser excitation phosphor power supply system and laser-whiteboard power supply system.7) In micro-nano processing method, various periods’nano-hole arrays were fabricated on the transparent film ofΦ200μm Si detector and the corresponding testing system was set up. The results suggested that devices’property was improved obviously in 500nm period; the improvement was about 6% when short circuit electric current was in 400nm-1100nm wavelength and about 15% in the 400nm-600nm wavelength; the open circuit voltage’s improvement was about 2%; the nano-hole array film could well enhance Photovoltaic devices’transmission efficiency.8) The designed power harvesting electric circuit was processed and debugged and its property was tested; it proved that the circuit could work well in condition of laser active-power supply illumination (50-100μW/cm2). Wireless nodes based on this power harvesting circuit was processed and practically measured with perfect results.更多还原