【作者】 王青萍；

【导师】 姜胜林；

【作者基本信息】 华中科技大学 ， 软件工程， 2010， 硕士

【摘要】 随着无线传感网络技术和可携带器件的发展,电池供电成为其发展的瓶颈之一。为了获得无线生命周期的自主供电系统,利用周围环境的振动能转换为电能为电子器件供电成为亟待解决的问题。其中利用压电材料把振动能转换为电能越来越受到关注,成为微能量领域的研究热点。然而,目前存在的问题是,等效电路模型理论有待进一步完善;器件产生的输出电压较小,器件结构有待改进;收集电路及收集器件需进一步优化等。针对上述问题,本文首先研究了目前国内外压电振动能量收集的发展状况,就压电材料的类型、器件的结构、振动模式以及收集电路和器件进行了分析,比较了器件结构和收集电路各部分的优缺点,提出了压电振动能量收集器的研究内容。根据哈密顿变分原理,本文推导了压电单晶悬臂梁的振动方程,研究了其电特性,并在此基础上,对压电单晶悬臂梁产生的电能及负载功率作了定量研究。在上述理论基础上,通过ANSYS有限元分析软件对压电单晶悬臂梁进行了静力学和动力学分析。静力学方面主要研究了压电陶瓷和基板材料的尺寸对输出电压的影响,为器件结构的优化设计奠定了理论基础;动力学方面主要研究了压电悬臂梁的自然频率、振型以及谐响应,为后续的测试分析提供了有效指导。根据上述理论研究,本文建立了能量收集测试系统,就压电单晶片悬臂梁的尺寸结构对输出电压的影响进行了测试和仿真对比,结果取得了较一致的结论。由尺寸为50 mm×20 mm×0.5mm的基板和尺寸为10 mm×10 mm×0.4mm压电陶瓷片构成的压电能量产生器,在激振频率为34Hz ,加速度为1g (1g = 9.81m / s2),负载电阻为470KΩ时,能够产生峰峰值为11V的电压,收集34uW的能量。接着就电解电容器、超级电容器和可充电电池的存储特性进行了分析比较,然后对器件结构进行了改进,分别设计了压电双晶片和多片叠层结构,并进行了实验研究,由尺寸为50 mm×20 mm×0.5mm的基板和尺寸为10 mm×10 mm×0.4mm的压电双晶片并联连接构成的能量产生器,在激振频率为33Hz,加速度为1g ,负载电阻为470KΩ时,能够产生峰峰值为16.97V的电压,收集76.5uW的能量。这表明,双晶片比单晶片能较大地提高输出电压和功率。另外,实验表明,多片叠层结构则能较大的提高输出电流和能量,这为无线传感网点和可佩戴器件供电提供了应用的前景。最后,对全文工作进行了总结,并对下一步研究计划进行了展望,提出了新的研究思路。更多还原

【Abstract】 With the development of wireless sensor network technology and portable devices, the power supply via the battery becomes one of the bottlenecks. In order to achieve finite lifetime of self-powered systems, the desiderating thing is to provide electric energy for such devices and networks by utilizing the vibration energy from the ambient environment. Converting vibration energy into electric energy by piezoelectric materials attracts more and more attention and becomes the hot point in micropower field. However, the problems are that the modeling theory needs to be further investgated, the structures of the piezoelectric energy harvester are ought to be improved because of the small output voltage and optimizing the harvesting circuits and storage devices are much in demand.According to the above problems, this dissertation first investgated the development trend of the piezoelectric vibration energy harvesting at home and abroad, and then anylized the types of the piezoelectric materials, the structures of the devices, the vibration mode and harvesting circuits and strorage devices and compared the merits and shortcoming of the different parts of structures and harvesting circuits, finally, proposed the research content of piezoelectric vibration energy harvester.Based on Hamilton’s principle, this dissertation studied the vibration equations and electric traits of the piezoelectric unimorph cantilever, and then made a quantitative analysis on the output energy and load power of the piezoelectric unimorph cantilever.According the above study results, the static and dynamic analysis of the piezoelectric unimorph cantilever through ANSYS finite element software are presented. In static analysis, the geometric parameters of piezoelectric ceramic and substrate influcing the output voltage are investigated in detail which establishes a solid theory foundation for optimizing the devices, while in dynamic analysis the resonant frequencies and eigemodes of the piezoelectric unimorph cantilever and its harmonic analysis are also presented, which provides an efficient instruction for the after testing and analysis.This dissertation built a testing system for piezoelectric energy harvesting based on the above research, and tested and compared through simulation the size structure of piezoelectric unimorph catilever influcing the output voltage and achieved indentical results,the energy generator with a beam dimension about 50 mm×20 mm×0.5mm and the piezoelectric unimorph dimension about 10 mm×10 mm×0.4mm produced 11V pp, 34uW with the optimal resistive load of 470KΩfrom 1g (1g = 9.81m / s2) at its resonant frequency of 34Hz , and then made a comparison on conventional capacitor, supercapacitor and rechargeable battery. In addition, the structures of the devices were improved and the piezoelectric bimorph cantilever and muiltlayer structures were desighed, respectively. The energy generator with a beam dimension about 50 mm×20 mm×0.5mm and the piezoelectric bimorph in parallel dimension about 10 mm×10 mm×0.4mm produced 16.97V pp, 76.5uW with the optimal resistive load of 470KΩfrom 1g at its resonant frequency of 33Hz , this result showed that, compared with the piezoelectric unimorph cantilever, the piezoelectric bimorph cantilever could improve the output voltage and power, while the muiltilayer structures could increase the output current and energy. This provides an application prospect of power supply for wireless sensor networks and portable devices.In the end, the works of this dissertation are sunnarized briefly, and the next work is figured out, including the novel reseach ideas.更多还原