【作者】 薛欢；

【导师】 胡元太；

【作者基本信息】 华中科技大学 ， 固体力学， 2008， 博士

【摘要】 无线供能是现代传感技术向微型化和集成电路化发展所需突破的“瓶颈”问题之一。在已有的几类无线供能技术中,压电俘能最具有发展前途,这是因为压电材料天然的力电耦合效应,可以实现力学量与电学量之间相互转换,并且其在转换过程中的电能损耗极小。本论文针对压电俘能技术这个多学科交叉问题,开展了大量的压电俘能/储能系统的非线性耦合作用及关键动力学行为研究,从整体角度对压电俘能器进行了全局优化,取得一系列创新性成果,具体体现在:1.跨越结构分析与电路设计等多个学科建立了关于压电俘能/储能系统的非线性耦合作用模型,重点研究了压电结构在非线性电路开、闭路交替作用下的动力学性能,揭示了多时间尺度之间的相互作用规律以及电路影响压电结构动力特性的作用机制,从而实现了压电俘能器的整体分析和全局优化。2.揭示了外载型式和环境温度对压电俘能器性能的影响机制,提出了频率控制与温度补偿策略,使得压电俘能器具备环境适应能力。尤其是为了让俘能器能从多频环境振动中更有效地提取能量,我们提出了具有变频功能的压电俘能结构,分析结果显示:这种压电结构从易变环境振动中所提取的能量可以达到没有变频功能压电结构所获能量的数倍之多。另外,我们还通过增设温度补偿层消除了压电俘能器由温度变化所引起的频率漂移,计算结果表明通过适当设计器件层与补偿层的厚度比就可以消除频率漂移,从而保证了俘能结构的温度稳定性。3.研究了在共振状态下工作的压电俘能器非线性特征,揭示了输出电流和功率密度在共振附近的多值与跳跃本质,确定了外载与外负载等对压电俘能器非线性性态的影响规律。4.研究了压电结构表面电极对器件整体性能的影响机理,提出了两种新颖的电极优化设计方案,明显降低了电极边缘的应力和电场集中现象,从而大大提高了压电俘能器安全可靠性。本文突破了多个在压电俘能技术综合分析和实际应用中的重点难点问题,开创性地提出了多种性能远超传统俘能器件的新型压电俘能器模型,得到了一系列适用于不同俘能器模型的优化方法和结论。这些成果不仅对压电俘能器整体性能的提升具有重要的指导意义,同时开展这样的研究还可以进一步地促进学科的交叉与渗透。更多还原

【Abstract】 The wireless power supply technology for the development of micromation and integration of new generation sensor technology is bottleneck that needs to break though. Among all kinds of energy harvesters, the piezoelectric energy is the most promised one because the piezoelectric materials are natural candidates for converting mechanical energy into electric energy with low loss in the energy converting process. This paper puts up a mount of study on the nonlinear dynamic behaviors and relative integrated optimization on the piezoelectric energy harvesting/storing system, obtains a lot of innovative results. Specific contents are as follows:(1) This paper establishes a novel intermittent nonlinear coupling model of piezoelectric energy harvesting/storage system spaning structure analysis and electrics circuit design fields. The dynamics performance of the harvesting structure under the turning of the open and close circuit conditions is calfully analysed. The multi-time scale interaction mechanisms and the mechanism of how the circuit influence the dynamic characteristic of harvesting structure is analysed, the integral analysis and optimization of piezoelectric energy harvester is then realized.(2) The machanism of how the load mode and temperature influence the performances of piezoelectric harvester is studied, and an appropriate frequency adjusting and temperature compensating strategy to enhance the environmental adaptability of piezoelectric energy harvester is developed, which gives the energy harvester better adapbility on enenvironment influence. In order to strength the interaction between the energy hatvester and the environment with varying frequency, two novel approaches for designing piezoelectric harvesters with adjustable and broad operating frequency-band are presented. Numerical results show that the harvesting efficiency of these devices is several times higher than the harvesters without frequency adjusting function. On the other side, temperature-induce d frequency shift in a thickness mode bulk piezoelectric device with a layer of another material for temperature compensation is analysed. It is shown that with a proper design of the compensation layer the temperature sensitivity can be reduced or made zero.(3) The nonlinear behavior distinction of piezoelectric energy harvester near resonance is studied, multi-valuedness and jump phenomena at resonance region of the output power are found, the influence of the driving force and circuit load to the nonlinear region which gives an important guidance of device design are analyzed.(4) The machanism of how the electrode on the surface of piezoelectric structure influce its integral performance is studied. Two noval methods for the electrode optimization are developed, the stress concentration effect near the edge of an electrode has been reduced, and the reliability of the piezoelectric harvester is enhanced a lot.This paper breakthroughs several key and/or difficult problems in the analysis and design of piezoelectric energy harvesting device, develops a variety of new type of piezoelectric energy harvesters with much better performance than the traditional one. Several research blanks of the international community in this field are filled, a series of valuable methods and conclusions suit to different harvesting model are obtained. These achievements have instructional significance to enhance the integral performance of the piezoelectric energy harvester. By conducting this kind of study, the cross and penetration of sentific subjects can be further promoted.更多还原