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。     

无线传感器网络的压电能量收集技术研究

针对压电能量收集装置在进行能量收集时具有固有频率高、能量收集效率低等问题,设计了一种变截面压电能量收集装置,并对压电振子进行了理论建模和有限元特性分析。根据分析结果,在相同的条件下,变截面悬臂梁的固有频率比等截面悬臂梁低。同时,变截面悬臂梁在截面厚度等于0. 4 mm时,电压输出最大,可达23. 77 V;变截面悬臂梁比等截面悬臂梁具有频带宽、输出电压高,并具有比等截面悬臂梁质量轻的优点。从而对环境中低频振动的能量进行收集时,为传感器的供电装置提供了理论的设计依据。     

磁场耦合双梁压电振动俘能器响应特性研究

环境振动能量收集有望解决微功耗无线传感器节点的供电问题。针对典型压电式振动俘能器多为线性谐振系统,工作频带窄,难以适配实际振源的问题,引入外加磁场,研究双梁—永磁体结构的能量收集器的振动特性,利用磁偶极子理论建立了磁力模型并引入动力学方程中,建立系统集中参数动力学模型,仿真分析了系统关键参数对响应的影响规律,最后搭建实验平台进行了验证。研究结果表明:双梁压电俘能器在耦合磁场作用下俘能效率相对无磁力时大幅提高,在磁间距为26 mm时俘能范围拓宽3倍,电压输出显著提高。     

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.     

MEMS压电阵列振动能量收集器

近年来,随着微能源的发展,微型压电振动能量收集器得到了广泛关注,但传统d31模式PZT薄膜微型压电振动能量收集器输出电压普遍较低,难以满足应用需求。为提高微型压电振动能量收集器的输出电压,论文提出了共质量块悬臂梁阵列压电振动能量收集器新结构,该结构包含压电悬臂梁单元组成的阵列和一个质量块,悬臂梁阵列共用质量块。采用有限元方法对该结构进行了优化设计,得到压电悬臂梁单元优化尺寸为3 mm×2.4 mm×0.05 mm,硅质量块优化尺寸为8 mm×12.4mm×0.5 mm。设计了MEMS压电阵列振动能量收集器加工工艺流程,加工出原理样件。在1 gn加速度,239.7 Hz谐振频率激励下,测试得到样件输出开路电压有效值为9.16 V;在最优化负载200 kΩ下,负载输出电压有效值为5.51 V,输出功率为151.8μW。     

采用复合磁电换能器的振动能量采集器研究

采用Teffenol-D/PZT/Terfenol-D复合磁电换能器,设计了一种新型振动能量采集器.采集器由悬臂梁、磁电换能器和永磁体三部分组成,环境振动引起换能器与永磁体相对运动,使得作用到换能器的磁场变化,变化的磁场引起Tedenol-D产生应变,应变传递到PZT得到电输出.采用等效磁荷理论分析了影响换能器与永磁体相对运动的磁场力;并用林滋泰德-庞加莱法分析了永磁体的非线性运动情况.实验结果表明,在振动激励频率为33 Hz,加速度为0.5 gn时,输出电压峰峰值45.1 V,输出功率112.1μW.     

压电驱动器的电致振动特性研究

旨在分析压电驱动器的电激励振动特性。以双晶压电悬臂梁为对象,基于能量法和热力学平衡方程推导了压电悬臂梁在电压激励下的强迫振动微分方程。利用自行搭建的电激励振动试验系统,测试了不同幅值交流电压激励下压电梁的谐响应和瞬态响应。通过试验验证了理论分析的合理性,讨论了激励电压和阻尼对谐响应和瞬态响应的影响。结果表明：压电悬臂梁的谐响应呈非线性,具有弹簧渐软特性;压电梁的共振频率随激励电压幅值的增大而减小,在6V、9V、12V交流电压激励下,压电梁的共振频率分别为55.6Hz、54.8Hz、54.4Hz;当激励电压频率等于压电梁的固有频率时,其横向振幅达到峰值;当激励电压频率逐渐远离压电梁的固有频率时,其振幅则迅速降低;激励电压频率接近共振频率时梁会发生“拍振”现象;阻尼对压电梁的共振抑振作用最为明显。     

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。     

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。     

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...     

Design and experimental study of broadband hybrid energy harvester with frequency-up conversion and nonlinear magnetic force

In this paper, a novel broadband hybrid piezoelectric and electromagnetic energy harvester using in the low frequency vibration environment is proposed, which combines nonlinear magnet force and frequency-up conversion mechanism simultaneously. Performances are studied by theoretical analysis and experimental test. Electromechanical governed equations of harvester are established, and analytical solutions of vibration response, output voltage and power are derived. Then, effects of nonlinear force, spacing between low frequency vibration beam and piezoelectric beam, load resistance and input excitation on harvester performances are investigated by experimental test. It can be concluded that the harvester can be used to work at the low-frequency environment efficiently, and the resonant frequency and harvesting bandwidth can be tuned by the nonlinear force between the magnets and the spacing between beams. Moreover, the larger the nonlinear magnetic force and the smaller the distance between two beams, the lower working frequency and the larger bandwidth. Compared with the corresponding linear apartment, output power and bandwidth of proposed harvester are improved 90% and 125% respectively.

     

抗磁悬浮能量采集器振动与输出特性分析

对抗磁悬浮振动能量采集器中悬浮永磁体的非线性振动特性进行了分析,并在此基础上分析了感应线圈结构参数对输出特性的影响.利用MATLAB软件的Simulink组件仿真分析采集器的非线性振动特性,利用有限元分析软件COMSOL对能量采集器的输出特性进行了仿真分析.通过改变线圈参数发现,在线圈体积一定时,输出功率变化很小,电压随着铜线直径减小增加很快,所以可以通过微细加工减小铜线直径的方法来提高线圈的输出电压.最终在线圈总体积约为6.4 mm3,铜线直径为0.02 mm,匝数为500匝时,得到的电压峰值达到约93.8 mV.     

一种宽频的磁式压电振动能量采集器

基于环境能量采集的压电振动能量采集器为无线传感器和微机电系统的长期供能提供了一种有效解决方案.目前研制的压电式振动能量采集器存在工作频率高,且频带窄的问题.给出了一种通过磁力的引入使其在低频下工作的、宽频的压电振动能量采集器,并搭建了测试系统对器件进行分析测试.在压电悬臂梁上放置永磁铁取代传统的质量块,同时在悬臂梁的上...     

A micro electromagnetic low level vibration energy harvester based on MEMS technology

This paper presents a micro electromagnetic energy harvester which can convert low level vibration energy to electrical power. It mainly consists of an electroplated copper planar spring, a permanent magnet and a copper planar coil with high aspect ratio. Mechanical simulation shows that the natural frequency of the magnet-spring system is 94.5 Hz. The resonant vibration amplitude of the magnet is 259.1 μm when the input vibration amplitude is 14 μm and the magnet-spring system is at resonance. Electromagnetic simulation shows that the linewidth and the turns of the coil influence the induced voltage greatly. The optimized electromagnetic vibration energy harvester can generate 0.7 μW of maximal output power with peak–peak voltage of 42.6 mV in an input vibration frequency of 94.5 Hz and input acceleration of 4.94 m/s² (this vibration is a kind of low level ambient vibration). A prototype (not optimized) has been fabricated using MEMS micromachining technology. The testing results show that the prototype can generate induced voltage (peak–peak) of 18 mV and output power of 0.61 μW for 14.9 m/s² external acceleration at its resonant frequency of 55 Hz (this vibration is not in a low ambient vibration level).     

Nonlinear behaviour of membrane type electromagnetic energy harvester under harmonic and random vibrations

In this paper, the fabrication and characterization of a vibration-based polydimethylsiloxane (PDMS) membrane type electromagnetic energy harvester (EMEH) is reported. The harvester is suitable for generating electric energy from low level sinusoidal and narrow band random vibrations. Under acceleration levels greater than 0.1 g the behaviour of the EMEH is nonlinear, exhibiting sharp jump and hysteresis phenomena during frequency sweeps. Under sinusoidal excitations (0.1–3 g), the device produces a maximum of 88.8 mV load voltage and 39.4 μW power. At a matching load impedance of 10.1 Ω and when excited at its resonant frequency of 108.4 Hz and 3 g base acceleration, it generates a power of 68.0 μW, which corresponds to a power density of 30.22 μW/cm³. The nonlinear behaviour of the EMEH is exploited to harvest energy under narrow band random excitations. At higher acceleration levels of narrow band (50–150 Hz) random excitations, the device exhibits a broadening of the load voltage spectrum in comparison to the response under relatively low acceleration levels of narrow band (5–150 Hz) random excitations. The results show that the nonlinear behaviour of the PDMS membrane can be utilized to enhance the bandwidth of the harvester under narrow band random excitations and provides a simple alternative to other bandwidth broadening methods such as beam prestress, resonance tuning, or stopper impacts.     

基于抗磁悬浮的气流能量采集器

研究了一种由外壳、提升磁体、上热解石墨板、线圈、永磁体转子和下热解石墨板构成的气流能量采集器,自由悬浮于两热解石墨板之间的永磁体转子可在外界气流的作用下转动,并在线圈中产生感应电压。采用有限元软件COMSOL Multiphysics 5.3和ANSYS Maxwell 16.0建立仿真模型,对能量采集器的悬浮特性、驱动特性和输出特性进行仿真分析通过实验验证,发现当喷嘴为83°时转子所受的气流驱动力矩最大;实验测试永磁体转子悬浮高度56.5 mm,与仿真高度57.5 mm误差仅为1.77%;能量采集器稳定工作的气流量范围为137 sccm^733 sccm,最大输出电压可达160 mV。     

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.     

Comparative study of conventional and magnetically coupled piezoelectric energy harvester to optimize output voltage and bandwidth

Energy harvesting has experienced significant attention from researchers globally. This is due to the quest to power remote sensors and portable devices with power requirements of tens to hundreds of μW. Hence, ambient vibration energy has the potential to provide such power demands. Thus, cantilever beams with piezoelectric materials have been utilized to transduce mechanical energy in vibrating bodies to electrical energy. However, the challenge is to develop energy harvesters that can harvest sufficient amount of energy needed to power wireless sensor nodes at wide frequency bandwidth. In this article, piezoelectric energy harvester (PEH) beams with coupled magnets are proposed to address this issue. With macro fiber composite as the piezoelectric transducer, mathematical models of different system configurations having magnetic couplings are derived based on the continuum based model. Simulations of the system dynamics are done using numerical integration technique in MATLAB software to study the influence of magnetic interactions in generating power and frequency bandwidth due to base excitations at low frequency range. Experimental results comparing conventional system and the proposed piezoelectric beam configurations with coupled magnets are also presented. Finally, the optimal beam separation distance between the magnetic oscillator and PEH is presented in this work.

     

Theoretical analysis and experimental study for nonlinear hybrid piezoelectric and electromagnetic energy harvester

A nonlinear hybrid piezoelectric (PE) and electromagnetic (EM) energy harvester is proposed, and its working model is established. Then the vibration response, output power, voltage and current of nonlinear hybrid energy harvester subjected to harmonic excitation are derived by the method of harmonic balance, and their normalized forms are obtained by the defined dimensionless parameters. Through numerical simulation and experimental test, the effects of nonlinear factor, load resistance, excitation frequency and the excitation acceleration on amplitude and electrical performances of hybrid energy harvester are studied, which shows that the numerical results are in agreement with that of experimental tests. Furthermore, it can be concluded that the bigger nonlinear factor, the lower resonant frequency; moreover, there is an optimal nonlinear factor that make the harvester output the maximum power. In addition, the output power of nonlinear hybrid energy harvester reaches the maximum at the optimal loads of PE and EM elements, which can be altered by the excitation acceleration. Meanwhile, the resonant frequency corresponding to the maximum power rises firstly and then falls with PE load enhancing, while it rises with EM load decreasing; furthermore, the frequency lowers with the acceleration increasing. Besides, the larger acceleration is, the bigger power output and the wider 3 dB bandwidth are. Compared with performances of linear hybrid energy harvester, the designed nonlinear energy harvester not only can reduce the resonant frequency and enlarger the bandwidth but also improve the output power.     

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.