带弹性放大器的双稳态压电振动能量采集器

针对带弹性放大器的双稳态压电振动能量采集器,利用Hamilton原理和Raleigh-Ritz方法建立了压电振动能量采集器的机电耦合分布参数模型.重点分析了激励频率Ω≥1时系统质量比、刚度比、磁铁对间距等参数对系统输出性能的影响.研制了压电振动能量采集器原理样机,搭建了实验测试平台,实验测试了压电振动能量采集器的输出性能.研究结果表明带弹性放大器的压电振动能量采集器是一个非线性双自由度系统,具有两个双稳态运动区域;在激励频率Ω≥1时压电振动能量采集器需要较大的激励能量才能进入大幅值周期振动状态.     

基于弹性支撑与放大的宽频压电振动能量采集器模型与实验研究

针对刚性支撑压电振动能量采集器工作频带窄、采集效率低等问题,提出了一种基于弹性支撑与放大的宽频压电振动能量采集器.利用有限元方法建立了宽频压电振动能量采集器的机电耦合模型,通过Ansys软件仿真分析了能量采集器结构参数对其频域输出特性的影响;根据力学和电学平衡方法建立了宽频压电振动能量采集器的集总参数机电耦合运动微分方程,利用4-5阶龙格库塔算法对方程进行了时域求解,仿真分析了能量采集器在不同结构参数下的振动位移、速度、输出电压和功率等性能.研制了弹性支撑和放大的宽频压电振动能量采集器原理样机,建立了样机系统实验平台,并对理论研究结果进行了实验验证,结果表明本文所提的宽频压电振动能量采集器具有工作频带宽、输出性能高等优点,适合为微电子器件进行供电.     

基于卡门涡街的水下振动能量采集器的设计与研究

针对传统的单自由度压电能量采集器工作带宽窄的现状,提出了在水下流激振动环境下的一种基于卡门涡街的二自由度宽频压电能量采集器来提高压电能量采集器的带宽,3 种二自由度压电能量采集器分别被设计、制造,并且测试了能量采集性能。结果表明,采用二自由度能量采集器比采用传统的单自由度能量采集器具有更好的采集效率,根据仿真和实验结果,H型压电能量采集器具有更好的振动能量采集效率。     

非线性压电振动能量采集器的振动特性与实验研究

为了提高线性压电振动能量采集器的输出特性,在线性压电振动能量采集器悬臂梁末端引入Duffing非线性磁力,构造了一种双稳态非线性压电振动能量采集器;综合考虑能量采集器的动态振型与轴向应变分布情况,建立了系统非线性机电耦合集总参数运动控制模型,并利用4阶、5阶Runge-Kutta算法对能量采集器的非线性振动特性进行了数值模拟;利用谐波平衡法计算获得了能量采集器的幅频响应方程,数值分析了激励频率、激励幅值以及磁铁间距等对系统非线性振动特性的影响,发现双稳态运动可以极大地提高能量采集器的频率响应范围和能量采集效率,并且能量采集器在低频、低幅值激励情况下可以产生大幅值周期运动;最后,通过实验对数值计算结果进行了验证.     

三稳态压电振动能量采集器的非对称势能阱产生机理及其动力学特性研究

为了揭示三稳态压电振动能量采集器非对称势能阱的产生机理及其对采集器动力学特性的影响机制,考虑采集器压电悬臂梁大扰度几何非线性和末端磁铁重力效应,利用能量法和Hamilton原理建立了三稳态压电振动能量采集器的非线性动力学模型.仿真研究了几何非线性和磁铁重力对系统静态解分岔、势能阱特性及其动力学响应特性的影响规律,结果表明几何非线性和磁铁重力使压电振动能量采集器产生附加的三阶和五阶非线性刚度及重力势能,导致非对称势能阱的产生.非对称势能阱不仅有利于提高三稳态压电振动能量采集器的有效工作频带和能量转换效率,还可以降低采集器对环境振动强度的要求使其在较低激励加速度下可以进入高能轨道运动.实验验证了理论仿真结果的正确性.     

悬臂梁式压电双晶片振动能量采集器的模型与实验研究

针对悬臂梁式双压电晶片振动能量采集器的质量效应问题,通过幅值修正方法建立了能量采集器的集总参数修正模型,利用阻抗分析和导纳圆法对模型参数进行了识别,得到了采集器在简谐基础激励作用下的机电耦合输出传递函数表达式;建立了悬臂梁压电振动能量采集器的实验系统,实验与仿真分析了悬臂梁末端质量、负载电阻等对能量采集器输出特性的影响,结果表明理论仿真结果与实验结果具有很好的吻合度,证明本文模型有利于提高压电振动能量采集器输出性能的分析预测精度。     

三稳态压电振动能量采集器的动力学建模、仿真与实验研究

为探究磁－机－压电耦合型三稳态压电能量采集器的非线性动力学行为,利用磁偶极子点荷方法计算得到了能量采集器末端受到的非线性磁力,基于欧拉－伯努利梁理论和拉格朗日方程建立了三稳态压电振动能量采集器的分布参数机电耦合动力学模型,仿真分析了系统参数(d、dg)对能量采集器的势能、磁力以及非线性动力学输出特性的影响,研制了磁－机－压电耦合型三稳态振动能量采集器原理样机,搭建了样机实验平台,实验验证了理论模型与仿真结果的正确性。研究结果表明:适当调整d后和dg可使压电振动能量采集器分别作单稳态、双稳态和三稳态运动,其中三稳态运动存在3个势能阱,势能阱的深度和宽度均小于双稳态压电振动能量采集器的势能阱深度和宽度,这有利于提升振动能量采集器的工作频带和采集输出效率。     

双稳态压电振动能量采集器的时-频域动力学特性及实验研究

为揭示双稳态压电振动能量采集器系统参数对其时－频域动力学特性的影响,利用等效磁荷法和拉格朗日方程及基尔霍夫电流定律分别建立了双稳态压电振动采集器的非线性磁力模型和系统分布参数动力学方程。基于谐波平衡法对双稳态压电悬臂梁振动能量采集器的动力学响应特性进行了解析,并分别从频域和时域角度仿真分析了系统参数对采集器动力 学响应特性的影响规律,实验验证了仿真结果的正确性。研究结果有利于对双稳态压电振动能量采集器的结构优化设计和综合性能的提高。     

折叠梁式振动能量采集器的设计

单自由度压电能量采集器因其结构特点,其有效工作频带范围较窄,难以在实际的无线传感器网络节点和可穿戴设备等领域应用。本文提出一种基于折叠梁结构的压电振动能量采集器,以提高采集器的工作带宽。首先,对折叠梁式振动能量采集器进行理论建模及有限元分析。其次,分析不同质量块的质量对所提出的能量采集器的影响。最后,对所提出的能量采集器进行实验研究。实验结果表明,在频域为0~ 100Hz,加速度为0.3g的条件下,“L”型振动能量采集器的工作带宽为1Hz,“Z”型振动能量采集器的工作带宽为3Hz,扩增为“L”型带宽的300%。其次,“Z”型振动能量采集器在0.2gn,0.25gn,0.30gn激励下的最佳匹配负载电阻分别为0.21ＭΩ,0.27ＭΩ 以及0.21ＭΩ,最大输出功率为509.122mW,921.926mW以及1331.230mW,初步验证了折叠梁式能量采集器的性能。本文所提出的折叠梁式能量采集器可以兼顾降低谐振频8.率和增加低频段的谐振阶数的需求,有效提高了能量采集效率,为待供能设备提供充足的电能。     

超声液体环境下压电式振动能量采集的研究

针对在液体环境下工作的器件不利于直接供能这一难题,制作了一种可在液体环境下工作的振动能量采集器,采用压电悬臂梁结构在液体环境中采集水中的超声能量,在32 kHz超声频率激励下,最高获得了5.04V的输出电压.通过改变超声波与悬臂梁的相对方向及液体盐分质量分数,发现能量采集器在超声液体环境下工作的发电效率随盐分质量分数的...     

A scrape-through piezoelectric MEMS energy harvester with frequency broadband and up-conversion behaviors

We propose a MEMS piezoelectric energy harvester with a wide operating frequency range by incorporating a high-frequency piezoelectric cantilever and a metal base as the top and bottom stoppers with a low-frequency piezoelectric cantilever. Frequency up-conversion of the piezoelectric energy harvester is realized when the low-frequency piezoelectric cantilever impacts and scrapes through the high-frequency piezoelectric cantilever. For an input acceleration of 0.6?g, with top and bottom stopper distances of 0.75 and 1.1?mm, respectively, the operating frequency ranges from 33 to 43?Hz. The output voltage and power up to 95?mV and 94 nW can be achieved. Experimental results indicate that the frequency up-conversion mechanism significantly improves the effective power.     

基于八悬臂梁-中心质量块结构MEMS压电振动能量采集器

高能量密度输出、低频范围响应、环境适应性强的自供电振动能量采集器已成为微能源技术领域的一个重要发展方向。提出一种d31型工作模式下MEMS压电式振动能量采集器,设计八悬臂梁-中心质量块结构代替传统的单悬臂梁结构,利用溶胶-凝胶（Sol-Gel）技术在每个悬臂梁上异质集成制备锆钛酸铅（Pb（Zr0.53Ti0.47）O3,PZT）压电功能厚膜层,通过MEMS工艺和引线键合技术完成器件础结构制造。输出性能测试结果表明,器件一阶谐振频率为41 Hz,3 gn加速度激励下输出电压峰峰值为264.00 mV;在器件两端加载3.00 MΩ负载时输出功率最大,为0.72 nW。     

Simulations,fabrication, and characterization of d31 mode piezoelectric vibration energy harvester

This paper presents the development work on d₃₁ mode piezoelectric vibration energy harvester. The device structure consists of a fixed-free type cantilever beam with a seismic mass attached at the free end of the beam. On top of the cantilever beam, a ZnO piezoelectric layer is sandwiched between two metal electrodes. The harvester is designed using an FEM tool CoventorWare. The simulations are carried out to estimate the resonance frequency, mises stress, optimal load resistance, and generated power. The optimized design is then implemented using a five mask SOI bulk micromachining process. The fabricated harvester is characterized for frequency response using Polytec MSA-500 Micro System Analyzer. The experimental resonance frequency is found to be 235.38 Hz. The harvester is also evaluated for generated open-circuit voltage when subjected to harmonic acceleration. The open-circuit peak-to-peak voltage for 0.1 g acceleration is found to be 306 mV.

     

微型之字形压电式能量收集器输出电压的建模和仿真

为了有效解决无线传感器网络节点的供电难题,提出之字形结构的微型压电式能量收集器。相比于传统的直悬臂梁,此结构等效加大了压电梁的长度,降低了系统的固有振动频率。建立了之字形压电梁的本构方程和受迫振动方程,推导得到其输出电压的频域表达式。基于之字形压电梁的结构,利用ANSYS软件对其进行了谐响应分析。仿真结果表明,压电梁的输出电压在各阶固有振动频率处存在极值,符合理论分析的结果;输出电压大小随压电梁长度增加而降低,随压电梁宽度增加而升高,但均为非线性关系;压电梁末端质量块的长度和厚度、基体层厚度减小时,会导致输出电压的增大。在论文中所提出的结构尺寸下,10根直梁构成的之字形结构压电梁,在其一阶固有振动频率处,输出电压可达10 V以上,符合无线传感器网络节点的实际供电需求,证明了之字形压电梁结构的有效性。     

窄带随机激励下三稳态压电俘能器的动力学特性与实验研究

本文研究了窄带随机激励下三稳态压电俘能器的动力学输出特性.首先,建立了非线性三稳态压电俘能器的分布参数型机电耦合运动方程,并基于多尺度法推导得到系统运动方程响应的解析解以及一阶、二阶稳态矩的表达式.其次,分析了磁铁间距、噪声强度和激励幅值等参数对系统稳态响应的影响.研究结果表明在一定参数范围内,随着噪声强度的增加,压电振动俘能器会经历阱内振动、阱间振动甚至大轨道周期运动,以表现出单稳态、双稳态和三稳态特性;改变磁铁水平间距和竖直间距构造三稳态压电俘能器,其振动幅值和采集电压相较于双稳态明显提高.最后,通过实验比较了压电俘能器在不同位形时的采集性能,结果表明了三稳态压电俘能器的优越性,为窄带随机激励下的非线性振动俘能器的设计提供一定的理论依据.     

Microenergy harvesting applications for outdoor power equipment

An energy harvesting system designed in this paper is of electromagnetic linear-motion inertial type that is capable of converting kinetic energy into useful electrical energy. The harvester consists of moving magnet–iron poles enclosed by cylindrical coils and an iron stator, and two stationary magnets are placed at both end sides acting as spring. The developed energy harvester is to be used for outdoor power equipment such as lawnmower and snow blower. Preliminary vibrational analysis is conducted on the lawnmower and snow blower to determine its working frequency and the optimal point of vibration. It was determined that the lawnmower resonated at a frequency of 15 Hz while the snow blower resonated at 21 Hz. Two methods are used to tune the energy harvesting system. The first is changing the stationary magnet thickness while keeping the magnet air gap constant and second is changing the air gap while keeping the stationary magnet thickness constant. We found that it is optimal to change the air gap rather than the magnet thickness to change the natural frequency of the device. The energy harvesting system is tuned to work on a lawnmower where the natural frequency is 15 Hz. Natural frequency of 15 Hz is obtained when the magnet thickness is 9.525 mm and a gap of 70.75 mm, where the maximum power dissipated is 29 mW.     

A design method for low-frequency rotational piezoelectric energy harvesting in micro applications

A rotational piezoelectric energy harvester is an electromechanical device that converts ambient mechanical rotation into electric power. The gravity-based method of using the gravity to excite the cantilever beam to deform in the vertical plane has received great attention. The harvester operates effectively at a narrow frequency band, which must be matched with the excitation frequency. For micro applications, low-frequency harvesters are often very difficult to design due to the specific limitations of the size and weight and the thickness of the piezoelectric material. Moreover, low-frequency harvesters require high precision in production and assembly, and small errors can cause large frequency error deviations. In response to this problem, this paper proposes a scheme for designing low-frequency rotational piezoelectric energy harvester, wherein the tuning is accomplished by changing the distance between the mass and the center of rotation. Furthermore, the paper establishes a theoretical model and presents a relationship for frequency adjustment. The experimental results achieved with a piezoelectric fiber composite fit the theoretical results well. The simulation and experimental results show that the resonance frequency of the harvester could be decreased by 63% when the distance between the mass and the center is five times the length of the harvester.

     

Fabrication and characterisation of bulk micromachined ZnO energy transducer with interdigitated electrodes

The proposed research work deals with the design, fabrication and characterisation of a ZnO cantilever energy transducer on Si(c) without the use of SOI wafers, thereby, reducing the cost of fabrication. The energy transducer is operated in the longitudinal mode through the interdigitated electrodes. This is for the first time, we have attempted to fabricate a cantilever transducer with interdigitated electrodes on Si(c) in our lab. The design frequency has been chosen in the range of 700–1000 Hz for a typical tire pressure monitoring system application in mind. The experimentally obtained frequency is 876.25 Hz and d₃₃ was calculated as 3.9 pC/N from the measurements. The experimental results are further validated by simulation and the feasibility of its application as energy harvester is demonstrated. The fabrication process is being optimised to fabricate devices with higher piezoelectric coefficients.     

双梁磁力压电振动能量采集器的实验和仿真

基于非线性技术改善能量采集器的能量采集效果作用,本文研究了非线性磁力耦合的双悬臂梁压电振动能量采集器,该采集器由两条不同的固有频率悬臂梁与永磁体组成.本文给出双梁磁力耦合压电能量采集器模型并建立了动力学方程式,通过实验测试获取相关参数与拟合磁力公式,数值仿真分析了双梁固有频率比1∶1.2与1∶1.5和永磁体初始间距40mm与30mm的4种结构能量采集器的电压输出性能与频率特征.根据数值分析设计实验:外激励加速度3m/s2作用下,双梁磁力结构能量采集器比单梁线性结构多一个电压共振峰;双梁固有频率比为1∶1.5比双梁固有频率比1∶1.2的电压响应带宽宽;初始磁距30mm共振峰值分别为(12Hz,39.4V)与(18Hz,13.4V)比初始磁距40mm两电压共振峰高且电压共振峰峰之间的电压输出比其他组合结构高.     

圆片级低真空封装的MEMS压电振动能量收集器结构设计

MEMS低真空封装技术能为MEMS器件的可动部分提供低阻尼环境,降低能量损耗,有效提高器件的能量转换效率,具有重要的研究意义和应用前景,是MEMS技术的研究热点和难点。为了进一步提高MEMS压电振动能量收集器的输出性能,提出了圆片级低真空封装的共质量块MEMS压电悬臂梁阵列振动能量收集器新结构,通过有限元分析方法对器件结构参数进行了优化设计,在优化结构参数下仿真器件输出性能：在610 Hz、2 gn加速度下,器件的输出电压为8.88 V,输出功率为1220μW,能满足实际应用需求;根据器件结构设计了加工工艺流程,对低真空封装结构的实现和封装工艺探索具有重要意义。