三稳压电梁随机振动特性与能量采集研究

Traditional battery has such shortages as limited life and often replacing, and hence how to supply continuous electrical power for micro-electronic devices has been paid more attention. At present, energy harvesting from circumstance and being transferred to electricity has become a research focus. Especially, energy harvesting from the ubiquitous ambient vibration has being a major highlight. Vibrational energy harvesting is a key self-solution to power a minitype electronic device. The proposal is based on the previous theoretic and technical research of vibrational energy harvesting of nonlinear bistable piezoelectronic cantilever beam, in order to extend to study the methodology and technology of vibrational energy harvesting of tri-stable piezoelectronic cantilever system. The project takes the tri-stable piezoelectronic cantilever beam as the study object, under different vibration condition, particularly the small vibrational intensity condition, the tri-stable vibrational energy harvesting with the elastic supporting outside magnets is proposed. In this proposal, the analysis and calculation model of magnetic force of the tri-stable piezoelectronic beam system will be investigated. The relationship among the tri-stable dynamics characteristic and the vibration response as well as energy converter will be explored, too. The influence of different stochastic excitations on the dynamical response of the tri-stable piezoelectronic beam and its energy acquisition is also to be analyzed. In addition, the mechanism of the geomagnetic field affecting on tri-stable piezoelectronic beam system is going to be exposed in the project, and the optimal tri-stable piezoelectronic beam system for vibrational energy harvesting will be designed. The goal of the proposal is to harvest more electrical-mechanical conversion energy by tri-stable piezoelectronic cantilever beam system.

传统电池存在寿命短、需要经常更换等缺陷，因此如何为微小型电子设备提供持续不间断的电力能源越来越受到关注。目前，从环境中采集能量并转换为电能已成为研究热点，而从普遍存在振动的环境中采集能量已成为一个主要的研究方向，环境振动能量的采集是为微小型电子设备提供电力的一种重要的自主解决方案。课题在前期非线性双稳压电梁的振动能量获取研究基础上，进一步深入扩展研究三稳压电梁的振动能量采集方法与技术。课题以三稳压电悬臂梁结构为研究对象，根据不同的振动环境，特别是低强度振动环境，提出弹性支撑外部磁铁的三稳压电梁振动能量采集思想，研究三稳压电梁系统的磁力分析方法与计算模型，探索三稳压电梁结构动力学特征与梁的响应及能量获取的关系，分析不同随机激励特征对三稳压电梁振动响应与能量转换的影响规律，揭示地磁场对三稳压电梁系统的作用机理，设计合理的三稳压电梁振动能量采集系统，实现三稳压电梁更多的机电能量转换。

为探索最少磁铁数目实现更多稳态数目的非线性梁结构的设计方法，解决多磁铁数目导致可调参数多、结构复杂、系统动力学分析繁琐等问题，课题提出了双磁铁实现双稳、三稳、四稳等多稳态悬臂梁的物理构型，并揭示了双磁铁多稳态梁的阱间跃迁响应和能量获取的机理。针对多稳态梁结构中常用的磁化电流、磁荷、磁偶极子等磁力分析模型的差异性，课题阐述了三者之间的关联机制，并给出了多稳态压电梁非线性磁力计算的宏微观尺度适用条件。为掌握弹性支撑和刚性支撑的三稳压电梁系统的动力学特征的异同，课题研究阐明了弹性和刚性支撑的三稳压电梁系统都各自存在一个最优磁铁间距，且这两个最优磁铁间距相差很小，可以认为在不同强度激励下，系统不需要调节结构参数和磁性能参数而实现有效的机电能量转换。针对一类具有中心频率的窄带随机激励，课题以双稳压电悬臂梁系统为研究对象，揭示了系统振动响应存在多峰值特征的机理及其能量获取的规律，为不同实际工况谱特征的非线性压电悬臂梁的应用提供了一定的实践指导。由磁铁构成的非线性多稳态梁结构始终处在地磁场的环境中，课题研究了地磁场对多稳态磁铁间相互作用的影响，得到了地磁场对多稳态梁的振动响应影响非常微小且可忽略不计的结论。为了检验非线性压电梁的能量获取效果，课题在低强度车载工况激励条件下，对三稳、双稳和线性压电梁进行了实际验证，以弹性三稳压电梁系统的机电能量转换电压均方值为基准，分别与刚性三稳压电梁、弹性双稳压电梁、线性压电梁、刚性双稳压电梁等系统的输出电压值进行对比，得到的输出比值分别是1.4倍、1.35倍、1.85倍、4.6倍以上。课题研究过程发现了单面双极性永磁铁这种特殊的物理现象，即对于一对尺寸相差很大的磁铁，同极不一定相斥，异极不总是相吸，课题通过对永磁铁负载线及退磁曲线上的工作点随外磁场变化的研究，揭示了外磁场变化会导致磁铁的工作点发生不可逆移动造成磁铁局部磁极极性翻转的机制。