Bistable Piezoelectric Flutter Energy Harvesting with Uncertainty

The analytical formulation of piezoelectric flutter energy harvesting using a bistable material,while considering uncertainties in the model is presented in this paper.Bistable laminates provide the advantage of large deflection due to the nonlinear snap-through characteristics when exposed to external loading,and can therefore provide a suitable base for piezoelectric material in energy harvesting applications.A piezoelectric material that is bounded on the surface of bistable laminates,subjected to external loading,generates large strains and hence relatively higher electrical output energy,in comparison with the case where piezoelectric material is bonded on a regular surface,with analogous loading conditions.Although information regarding the external loading,material characteristics of the bistable laminate and the piezoelectric material,boundary conditions,and overall electrical circuit efficiency can be defined for analytical purposes,the exact model of the system is not readily accessible.The unavoidable uncertainties in the material,loading,and efficiency of a complex system call for a probabilistic approach.Hence,this paper provides a formulation that considers uncertainty bounds in obtaining a realistic model.Optimal Uncertainty Quantification(OUQ) is used in this paper,which takes into account uncertainty measures with optimal bounds and incomplete information about the system,as a well-defined optimization problem according to maximum probabilities,subjected to the imposed constraints.The OUQ allows the inspection of the solution for a span of uncertain input parameters,as a reliable and realistic model.

Harvesting base vibration energy by a piezoelectric inverted beam with pendulum

We proposed a two-degrees-of-freedom inverted piezoelectric beam with pendulum to promote the performance of vibration energy harvesting. This configuration is composed of an inverted elastic beam and a pendulum attached to its free end. The electromechanical equations governing the nonlinear system were derived. The harmonic balance method(HBM)is applied to solve the equation and the results prove that there exists a 1:3 super-harmonic resonance. The simulation results show that owing to the particular nonlinearity, there appears a special bending effect in the amplitude-frequency response, i.e., bending right for the first natural frequency and left for the second natural frequency, which is beneficial for harvesting vibration energy. The HBM results are verified by the entity simulations. Furthermore, over a relatively wide range of power spectral density, it could reach a dense jumping and give a dense high pulse voltage.

Integration of a nonlinear energy sink and a piezoelectric energy harvester

A mechanical-piezoelectric system is explored to reduce vibration and to harvest energy. The system consists of a piezoelectric device and a nonlinear energy sink （NES）, which is a nonlinear oscillator without linear stiffness. The NES-piezoelectric sys- tem is attached to a 2-degree-of-freedom primary system subjected to a shock load. This mechanical-piezoelectric system is investigated based on the concepts of the percentages of energy transition and energy transition measure. The strong target energy transfer occurs for some certain transient excitation amplitude and NES nonlinear stiffness. The plots of wavelet transforms are used to indicate that the nonlinear beats initiate energy transitions between the NES-piezoelectric system and the primary system in the tran- sient vibration, and a 1：1 transient resonance capture occurs between two subsystems. The investigation demonstrates that the integrated NES-piezoelectric mechanism can re- duce vibration and harvest some vibration energy.

Double Peak Derived from Piezoelectric Coefficient Nonlinearity and Proposal for Self-Powered Systems

With the development of wireless sensor network(WSN)applications in intelligent monitoring,additional support for the low power consumption wireless nodes can be provided by piezoceramics that harvest vibrational energy.First,we describe the effects of stimulation variations on piezoceramics and the energy harvesting circuit set-up.Two types of piezoceramics were stimulated at different frequencies and amplitudes to obtain the power output characteristics.Then,the energy harvesting circuit was studied and coupled with the piezoceramics.A double peak phenomenon was found in energy harvesting using a hard piezoceramic which gave a direct proof that the nonlinearity of the piezo constant should be considered in application.Finally,energy storage and output were studied and analyzed.Electronic components for the WSN were recommended according to the output power and the application.The results will give an instruction for piezoceramic energy harvesting under various stress amplitudes on its implementation.

An energy harvester combining a piezoelectric cantilever and a single degree of freedom elastic system

This paper presents a type of vibration energy harvester combining a piezoelectric cantilever and a single degree of freedom (SDOF) elastic system. The main function of the additional SDOF elastic system is to magnify vibration displacement of the piezoelectric cantilever to improve the power output. A mathematical model of the energy harvester is developed based on Hamilton's principle and Rayleigh-Ritz method. Furthermore, the effects of the structural parameters of the SDOF elastic system on the electromechanical outputs of the energy harvester are analyzed numerically. The accuracy of the output performance in the numerical solution is identified from the finite element method (FEM). A good agreement is found between the numerical results and FEM results. The results show that the power output can be increased and the frequency bandwidth can be improved when the SDOF elastic system has a larger lumped mass and a smaller damping ratio. The numerical results also indicate that a matching load resistance under the short circuit resonance condition can obtain a higher current output, and so is more suitable for application to the piezoelectric energy harvester.

变截面压电悬臂梁能量采集器在高斯白噪声激励下的稳态统计特性研究

环境振动是一种非周期、随机的宽频激励,研究振动能量采集器在环境振动下的能量采集特性具有重要意义。本文采用改进随机平均法,求解了变截面压电梁在高斯白噪声激励下的等效振幅、位移、速度的稳态概率密度函数,位移与速度的联合概率密度函数以及稳态均方输出电压,随后研究了变截面压电梁的能量采集效能。结果表明:负载电阻一定时,截面系数β>0时的变截面压电梁相比β=0时的等截面压电梁有更好的稳态均方输出电压;截面系数β>0时,随着电阻电容乘积的倒数的增加,变截面压电梁的均方电压均呈现逐渐减小的趋势,当电阻电容乘积的倒数值一定时,β值越大,均方电压也越高;随着噪声强度的增加,变截面压电梁的均方电压均呈现逐渐增大的趋势,当噪声强度一定时,β值越大,均方电压也越高。本文研究结果可为变截面压电悬臂梁能量采集系统的设计及应用提供理论依据。

基于压电能量收集技术的自供电系统设计

为了降低对传统电池的依赖,同时收集和利用汽车发动机的振动能量,设计了一种二自由度压电能量收集器和基于压电能量收集技术的自供电系统。系统主要由压电能量收集器、电源管理模块和加速度传感器组成。对压电能量收集器进行了建模、仿真和测试,得到了压电能量收集器的谐振频率和输出电压,测试结果表明该压电能量收集器前两阶谐振频率分别为105.5和124.6 Hz,并且在95~128 Hz频率范围内输出电压均在2.7 V以上,频率带宽为33 Hz。测试系统的整体功能,测试结果表明电源管理模块LTC3588-1输出3.34 V的直流电压,加速度传感器ADXL335能够正常工作。实验验证了压电能量收集技术在汽车电子领域中的潜力和可行性,为汽车电子设备提供可持续的自供电解决方案。

A variable step-down conversion ratio switched capacitor DC-DC converter for energy harvesting systems working in intermittent mode

Energy harvesting systems stimulate the development of power management for low power consumption applications. Improving the converter efficiency of power management circuits has become a significant issue in energy harvesting system design. This paper presents a variable step-down conversion ratio switched capacitor （SC） DC-DC converter to advance the converter efficiency of charge on the stored capacitor in a wireless monitoring system of orthopedic implants. The converter is designed to work at 1 MHz switching frequency and achieves 15 to 2 V conversion. Measurement results show that the converter efficiency can reach 42% including all circuit power consumption, which is much higher than previous work.

轨下压电叠堆俘能器安装对车轨系统动力性能的影响

压电俘能技术已经在轨道交通领域受到广泛关注,但目前主要侧重于压电俘能器的结构设计。俘能器的安装会在轨道结构中附加新的装置,可能会对车轨系统动力性能产生一定影响,甚至会威胁行车安全。然而,俘能器的安装对车轨系统动力性能的影响鲜有报道。以轨下压电叠堆俘能器为研究对象,建立了车辆-轨道-俘能器耦合系统的动力分析模型,构建了安装单个或多个俘能器下钢轨和道床的垂向振动方程,采用MATLAB软件编写了新型预测-校正积分法程序,给出了理论解答。通过与已有文献的结果对比,验证了程序的正确性。进一步,探究了采用单个和多个安装方式时俘能器的等效刚度对车轨系统动力性能(钢轨位移、钢轨加速度、扣件力和车体加速度)的影响,并评估了等效刚度与列车舒适度的关系。结果表明:当俘能器等效刚度在0~60×10^(6)N/m变化时,随着俘能器等效刚度的增加,两种安装方式的最大钢轨位移减小,钢轨加速度减少,车体加速度几乎保持不变,扣件力减小,列车行驶的舒适度呈现微小变化;当俘能器的等效刚度在0~2×10^(6)N/m选取时,俘能器的安装对车轨系统动力性能影响很小。研究成果为轨下压电叠堆俘能器的设计与安装提供了理论指导。

基于架空输电导线振动的压电俘能系统研究

针对架空输电导线振动能量收集与输电线路传感器节点的供能问题,利用压电悬臂梁结构,设计了一种压电俘能系统。基于架空导线微风振动理论,搭建模拟架空导线振动的实验平台。通过实验研究,分析压电俘能装置结构对系统固有频率的影响,以及不同激励频率、不同激励加速度与不同负载条件下压电俘能系统的输出电能特性。实验结果表明:压电俘能系统处在共振频率下,激励加速度达到10 m/s~2时,存在最优负载使输出电压有效值达到16.27 V,输出功率达到5.29 mW,为解决输电线路传感器节点的供能问题提供一种新思路。

具有时滞反馈控制的双稳态压电-电磁式俘能器的随机动力学

本文研究了色噪声激励下具有时滞反馈控制的双稳态压电-电磁混合式俘能器的动力学特性.首先,建立了非线性双稳态压电-电磁俘能器的集中参数型机电耦合运动方程,并基于能量包线随机平均法推导得到系统稳态概率密度函数和平均输出功率表达式,通过蒙特卡洛数值方法验证了理论解的正确性.其次,分析了时滞和反馈增益系数对系统输出功率的影响.研究结果表明:在一定参数范围内,随着位移时滞与速度时滞的增加,输出功率出现周期性变化,并在特定的时滞与反馈增益组合下达到最大值;调节反馈增益系数可以改变输出功率的相位和大小.说明通过合理地设置时滞反馈控制可以提高俘能器的采集功率,为随机激励下非线性振动俘能器的设计和优化提供一定的理论依据.

分段悬臂梁压电振动能量采集器及其理论建模研究进展

压电振动能量采集器在无线传感器、嵌入式医疗设备、微电子机械系统(MEMS)、物联网(IoT)器件等低功率设备的供电中有广泛的应用前景,其中分段悬臂梁采集器因具有低频宽带、微尺寸和多方向采集等潜在优点而成为研究热点。评述了分段悬臂梁压电能量采集器及其理论建模的最新研究进展,介绍了压电能量采集原理及典型结构,梳理了各种分段悬臂直梁和角梁采集器的类型和结构特点,比较分析了其输出电压、输出功率和工作频率等性能,讨论了采集器的现有建模和求解方法的优缺点和难点,指出了应用面临的供应挑战。最后,总结了该能量采集技术目前存在的问题,并展望了其未来发展方向。

Simultaneous energy harvesting and tribological property improvement

In this study,piezoelectric elements were added to a reciprocating friction test bench to harvest friction‐induced vibration energy.Parameters such as vibration acceleration,noise,and voltage signals of the system were measured and analyzed.The results show that the piezoelectric elements can not only collect vibration energy but also suppress friction‐induced vibration noise(FIVN).Additionally,the wear of the friction interface was examined via optical microscopy(OM),scanning electron microscopy(SEM),and white‐light interferometry(WLI).The results show that the surface wear state improved because of the reduction of FIVN.In order to analyze the experimental results in detail and explain them reasonably,the experimental phenomena were simulated numerically.Moreover,a simplified two‐degree‐of‐freedom numerical model including the original system and the piezoelectric system was established to qualitatively describe the effects,dynamics,and tribological behaviors of the added piezoelectric elements to the original system.

基于组合非线性的多稳态宽带能量采集不同势阱结构的设计与比较

为提高低频和宽带下能量采集器的功率密度,提出一种新型多稳态宽带能量采集装置。该采集器通过悬臂梁-止档接触与磁弹性相结合的非线性方法得到多种稳态类型。采集器的全局振幅受到接触的限制,但阱间运动提高了采集效率。本文确定多稳态的形成机制和不同磁体结构的相关参数区域;建立采集器的机电耦合模型来描述其动态特性;为探讨势阱结构对多稳态能量采集的影响,建立具有4种典型势阱结构的能量采集器,并通过实验验证其等效非线性恢复力;采用数值方法研究和实验验证了这4种结构在不同激励水平下的动态特性。结果表明,当外部激励超过临界强度时,深度不均匀的多势阱和较浅的外势阱比均匀深度的多势阱更适合所提出的系统。此外,通过提高采集器效率和限制末端质量的全局振幅,本文提出的多稳态系统实现了比传统系统高6.3倍的功率密度。

微压电式振动能量采集器的研究进展

给出了微压电式振动能量采集器的基本工作原理和物理模型。按照压电单元结构类型的不同,将其分为单一的直线型悬臂梁、直线型悬臂梁阵列、L型悬臂梁和圆形压电膜,分别讨论了各种类型的微压电振动能量采集器的优缺点。详细介绍了国内外各研究小组研制的微压电式振动能量采集器的结构参数、性能及其应用现状,分析针对目前研究中存在的问题,指出如果能在分析建模、压电结构及压电材料优化方面取得实质性进展,微压电振动能量采集器作为新型供能设备在MEMS系统和低功耗无线传感网络中的应用将会具有更加诱人的前景。

MEMS压电-磁电复合式振动能量采集器

具有高能量输出密度的自我供电振动能量采集技术有着迫切的应用需求,是智能化MEMS器件系统发展的重要方向。研究了一种可将外界环境振动能转化为电能的MEMS压电-磁电复合振动能量采集器,其综合了压电发电和磁电发电的优势,为新型MEMS供电研究提供了新思路。利用溶胶-凝胶工艺完成锆钛酸铅(PZT)压电功能薄膜的制备,采用MEMS加工技术完成器件四悬臂梁-中心质量块基础结构的设计和制作,结合集成封装技术实现微结构与永磁铁的微组装。测试结果表明:在一阶谐振频率247 Hz,10 g加速度激励的振动状态下,器件压电部分压电敏感单元与磁电部分电感线圈的单位体积最大有效输出电压分别为2.066×107和5.002×106 mV/cm3。

高效压电能量回收系统的优化设计(英文)

提出了一种新型的压电能量回收器件,通过一个开关功率变换器的辅助,系统的能量转换效率可提高400%。该功率变换器原型为Buck-Boost变压器,本项研究通过低功耗的控制电路对其进行了优化。利用Pspice软件对整个系统电路进行了建模和仿真,仿真结果显示,优化后的能量回收器件输出功率提高了3.4倍。

微型振动能量收集器的研究现状及发展趋势

综述了最近几年国内外微型振动能量收集器的研究状况,重点介绍了被广泛应用的压电式振动能量收集器和电磁式振动能量收集器,简要阐明微型振动能量收集器实现大规模商业化产品的可能性。根据微型振动能量收集器的工作方式和结构特点对其进行了分类,并且分别列举出了各种类型能量收集器的突出研究成果,详细介绍了各种类型振动能量收集器的基本工作原理和工作性能,对比各种结构的优缺点,总结各类微型振动能量收集器的适用范围和存在的问题。最后,分别从能量收集器的结构尺寸、材料性能和能量收集电路三个方面对微型振动能量收集器的发展趋势进行了展望。

磁耦合式双稳态宽频压电俘能器的设计和俘能特性

为了同时提高振动能量俘获系统的效率和实用性,俘能器主结构的振动特性与环境振动特性的匹配度显得尤为重要.非线性系统复杂的动力学行为为设计高效的俘能器奠定了基础,但结构一旦被设计、生成出来,其工作频率往往是固定的,无法根据环境中的振动而发生相应的改变.本文利用可移动铰支座和非线性磁力设计了一种具有双稳态特性的宽频压电俘能器,通过拓宽压电俘能器的工作频带,来匹配环境中较宽的振动频率.为了保证系统低频宽带的俘能效果,详细分析了结构的长度比、磁间距、负载阻抗、外激励频率和幅值等对系统线性刚度、非线性刚度以及动力学行为的影响,并进行了实验验证.首先将系统简化为欧拉-伯努力梁,利用拉格朗日方程建立系统的非线性动力学方程,并利用谐波平衡法进行求解.针对理论分析给出的不同外激励频率下的最优长度比,搭建了实验平台进行验证.理论和实验的结果表明:非线性磁力的引入使系统呈现负刚度特性,使俘能器能够在单稳态和双稳态之间的变换,实现低频俘能效果;通过调节可移动铰支座的位置,改变系统的长细比,能够实现从0到16 Hz的宽频俘能效果.