【作者】 胡洪平；

【导师】 胡元太；

【作者基本信息】 华中科技大学 ， 固体力学， 2006， 博士

【摘要】 新一代传感技术的发展较大程度上依赖于改进微电子器件的无线供能技术,即直接从环境中提取能量。能从环境中俘获能量的装置称为俘能器(energy harvester)。在几种已见的俘能器(静电、电磁、压电等)中,压电俘能器从环境振动或噪声中提取能量的性能最好。考虑到以往的压电俘能器研究要么集中于对压电结构的优化而将电路端简化成阻抗或者系统阻尼,要么集中于电路优化而将压电端简化成电流源,这样处理明显忽略了压电端与电路端的耦合作用,得不到性能优良的俘能器,因此,本论文跨越压电结构分析与电路设计这两个学科,建立起了可用于压电俘能器整体优化和设计的非线性耦合作用模型,将压电俘能结构与储能电路有效地连接在一起,从而通过对多时间尺度的相互作用的研究来开展压电俘能器的整体优化。具体表现以下几个方面:(1)从三维压电理论的基本方程出发,建立了对微电子器件设计和分析非常有用的梁、板、壳型压电结构的动力学方程。(2)建立了压电双晶片梁型俘能结构与RLC储能电路间的耦合分析模型,用多时间尺度方法研究了俘能过程与储能过程的非线性耦合作用规律,并分析了俘能器的重要结构参数和电路参数对其性能的影响机理。在此基础上,对压电俘能器性能进行了整体优化。(3)提出了一种可以从低频振动环境中有效提取能量的螺旋状压电俘能器模型,并利用传递矩阵方法建立了这类俘能结构的耦合计算模型,分析讨论了各系统参数对俘能器性能的影响。压电结构从环境中俘获的能量不经过储存而直接供给微电子器件工作。这种型式的俘能器一般比较适用于从较高振动水平的环境中俘能,即所俘获的能量不需要累积就能有效保证微电子器件的不间断工作。(4)更进一步建立了一种低频、性能好、服务期长、易微型化的自适应压电俘能器模型。其两个重要特征是:一是通过调节电路参数占空比,可以有效保证在变幅振动中工作的压电俘能结构性能最优;二是在压电端引入SSHI,可进一步延长整流器的导通时间,可从环境振动中提取更多能量。将压电结构与储能电路耦合成一个整体,建立了俘能过程与储能过程的耦合作用模型。运用多时间尺度方法对俘能-储能过程进行了综合计算,并根据计算结果对螺旋状压电俘能器进行了整体优化设计。这种类型的俘能器具备良好的俘能性能,并将俘获的能量有效地储存。因其俘能和储能的高效性,具有更广泛的适用范围为微电子器件无线供能,其中包括振动水平相对较低的工作环境。本文建立了三种低频俘能器模型,运用多时间尺度方法,对俘能器的俘能端和电路端之间耦合进行了计算和分析,得到了一系列适用于不同俘能器模型的优化方法和结论。这些成果对压电俘能器俘能结构和储能电路的优化设计,提高俘能器性能具有重要的指导意义。为俘能器的研究提供了行之有效的分析方法,为其它类型俘能器的研究提供了范例。更多还原

【Abstract】 The developments of new generation sensor technology rely significantly on the improvement of wireless power supply technology in microelectronic devices. In fact, energy to supply microelectronic devices can be scavenged directly from latent power source of environment. The device which picks up energy from environment is called“energy harvester”. The piezoelectric energy harvester has the best performance among common energy harvesters (electrostatic energy harvesters, electromagnetic energy harvesters and piezoelectric energy harvesters etc.). Considering the previous research about piezoelectric energy harvesters concentrate on the piezoelectric structure’s optimization, however the electric circuit’s side is simplified to impedance or system damping; or concentrate on the electric circuit’s optimization and the piezoelectric side is simplified to current source, treating like these neglect the coupling action between piezoelectric side and electric circuit side, so the high performance harvester can not be obtained.Specific contents as follows:(1) From three-dimension piezoelectric fundamental equation, we set up dynamic equations of piezoelectric structure with beam, plate and shell. It is useful to design and analyses on microelectronic device.(2) This paper builds up coupling action model of bimorph beam-type harvester and RLC power storage circuit. We study the nonlinear coupling law between harvesting process and store process by means of multiple time scale method, and analyze on mechanism of important structure parameters and circuit parameters of harvester on its performance. Base on this, we optimize on performance of whole energy harvester.(3) We propose a kind of low frequency piezoelectric energy harvester structure using spiral-shaped bimorph, and build a coupling counting model for the energy harvester by using transfer matrix method. Analyze and discuss the affection of harvester system parameters on its performance. Piezoelectric structure picks up energy to power microelectronics directly and no need to storage. This type of harvester suits to scavenge energy from ambient with high vibration level. This means that energy is no need to accumulate and enough to ensure microelectronic device keeps working effectively.(4) This paper brings forward to set up a self-adaptive energy harvester mode with lower working frequency, better performance and longer service life time. It has two important characteristic: firstly, through modulating duty cycle of circuit parameter, piezoelectric structure can be optimized even under situation of varied vibration amplitude; secondly, introduction of SSHI into piezoelectric part further elongates the close time of the rectifier, and can pick up much more energy from vibration environment. The piezoelectric structure and storage circuit are coupled into a whole, and set up a coupling action model between harvesting process and storing process. Comprehensive calculates on harvesting-storing coupling process by means of multiple time scale. According to the results, integral optimum design on the harvester. This kind of harvester has a good performance, and stores the harvesting energy effectively, even under the low level environmental vibration. This kind of harvester has a wide-rang to supply energy to microelectronic device.This paper has set up three types of low frequency harvester models. By utilizing multiple times scale method, we calculates and analyzes the coupling between the piezoelectric end and circuit end, and obtains a series of methods and conclusions which respectively suits to different kind of harvester model. These achievements have instructional significance to optimum design on harvesting structure and storage circuit, and performance of the harvester. At the same time, it has given an effective analytic method and provided examples to study on harvester.更多还原