基于PLZT薄膜多场耦合机理的光-热-振动复合能量采集研究

Energy harvesting from the environment can provide long-term energy supply for wireless sensor nodes and solve the power bottleneck problem of wireless sensor network. To solve the problem of the low output power, discontinuity and instability power supply of single energy harvesting and the complex energy transferring element, miniaturization and integration problem of hybrid energy harvesting, a hybrid energy harvester from multiple sources including light, thermal fluctuations and vibration is proposed, by which the multi-types energy can be harvested by a single material/structure. In consideration of the multi-field coupling relationship of PLZT film stimulated by multisource energy, the constitutive equations of multi-field coupling of light, thermal, electric and elastic are modeled on the basis of thermodynamics theory. According to the configuration of the hybrid energy harvester, the governing equation of coupled light-thermal-electrical-mechanical is established, on basis of which the mathematical model of power output is derived and verified by experiment. And then the correlative mechanism between the hybrid energy conversion efficiency and the structure parameter, load resistor is researched. The structure parameter of harvester is optimized with the finite element. At last, the hybrid energy harvester is manufactured, and the performance of output power is measured by experiments. Thus the load capacity and stability of energy supply are evaluated comprehensively, by which the feasibility and effectiveness of the above theory are proved. This study will help improving the theory of hybrid energy conversion and promoting the application of PLZT film in energy harvesting and wireless self-powered system.

采集环境中能量为无线传感器节点提供持续的能源供应，可从根本上解决无线传感网络的供能瓶颈。针对目前单一能量采集输出功率低、供能不稳定以及复合能量采集换能结构复杂、不易微型化和集成化的问题，本项目基于PLZT多场耦合机理提出一种光-热-振动复合能量采集方法，利用单一材料/结构实现不同形式能量的复合采集。通过对多场耦合关系分析，构建PLZT光-热-电-力多场耦合本构方程，揭示多源能量输入下PLZT的多场耦合机理与复合能量转换规律；结合构型建立复合能量采集器的光热机电耦合控制方程，导出复合能量输出数学模型并进行实验验证和修正，探究复合能量转换效率与负载、结构参数的关联机制，利用有限元方法对器件的结构参数进行优化设计；通过性能测试实验全面评价复合能量采集器的负载能力和供能稳定性，并验证上述原理的可行性和有效性。本项目的开展可完善PLZT的复合能量转化理论，推动PLZT在微能源采集和自供能领域的应用。

作为无线传感网络的核心，大量布置的无线传感器节点的寿命受到能量供应限制，采集环境中能量为无线传感器节点供能，能够从根本上解决无线传感网络的供能瓶颈，但现有能量采集器件由于环境影响导致供能不稳定、不连续。本课题提出了基于PLZT铁电材料的复合能量采集器件，能利用单一材料/结构同时对光能、热能和振动能进行采集，提高了供能稳定性和能量采集密度。本课题取得了以下几方面成果：建立了PLZT铁电的光-热-电-力多物理场耦合模型，并推导了PLZT铁电悬臂梁的多场耦合的有限元动力学方程，通过有限元求解探究了PLZT铁电多物理场耦合规律；构建了不考虑温升的反常光生伏特电压输出模型，并进行了参数辨识和实验验证；分析了PLZT铁电悬臂梁的能量输出规律，通过理论计算和仿真模拟，对结构尺寸和负载等参数进行优化；创新性提出阵列式宽频和螺旋式低频两种复合能量采集器结构，通过有限元仿真对关键参数进行了优化，有效提高了能量输出功率密度，阵列式复合能量采集器可实现50~300Hz宽频范围内的能量采集，螺旋式结构可实现50HZ的低频能量采集；提出了合适的能量采集电路，搭建了复合能量采集器件测试表征系统，测试了不同激励下复合能量采集器输出电压和功率，进行了不同环境载荷下PLZT铁电复合能量采集器充放电试验，并对复合能量采集器进行了阻抗匹配实验。本项目的研究为基于PLZT铁电材料的复合能量采集系统的设计提供理论基础，可以进一步拓展铁电材料在自供能无线传感器网络等领域应用。