基于脉冲液流换能器的振动能量回收原理与实验研究

针对自供电磁流变阻尼调节系统的能量供给问题,提出基于脉冲液流换能器的振动能量回收方法,通过振动能-液流能-机械能-电能的变换,实现振动能量回收。建立了基于齿轮马达、飞轮和永磁发动机的脉冲液流换能器分析模型,利用Matlab软件对正弦振动下换能器的电压输出特性、功率转换特性和转换效率进行仿真。为验证理论分析的正确性,设计制作了基于脉冲液流换能器的振动能量回收装置,利用J95-I减振器测试台上对振动能量回收装置实验测试,比较了正弦激励条件下换能器的理论电压特性与实测电压特性、理论转换效率与实验转换效率。实验研究表明,脉冲液流换能器是能够实现振动能量的转换,在带30 负载情况下,效率可以达到 46.85%,平均输出功率可以达到37.4W。     

A flex-compressive-mode piezoelectric transducer for mechanical vibration/strain energy harvesting

A piezoelectric transducer for harvesting energy from ambient mechanical vibrations/strains under pressure condition was developed. The proposed transducer was made of two ring-type piezoelectric stacks, one pair of bow-shaped elastic plates, and one shaft that pre-compresses them. This transducer works in flex-compressive (F-C) mode, which is different from a conventional flex-tensional (F-T) one, to transfer a transversely applied force F into an amplified longitudinal force N pressing against the two piezo-stacks via the two bowshaped elastic plates, generating a large electric voltage output via piezoelectric effect. Our experimental results show that without an electric load, an F-C mode piezo-transducer could generate a maximum electric voltage output of up to 110 Vpp, and with an electric load of 40 κΩ, it a maximum power output of 14.6 mW under an acceleration excitation of 1 g peak-peak at the resonance frequency of 87 Hz.     

Consideration of impedance matching techniques for efficient piezoelectric energy harvesting

This study investigates multiple levels of impedance-matching methods for piezoelectric energy harvesting in order to enhance the conversion of mechanical to electrical energy. First, the transduction rate was improved by using a high piezoelectric voltage constant (g) ceramic material having a magnitude of g33 = 40 x 10(-3) V m/N. Second, a transducer structure, cymbal, was optimized and fabricated to match the mechanical impedance of vibration source to that of the piezoelectric transducer. The cymbal transducer was found to exhibit approximately 40 times higher effective strain coefficient than the piezoelectric ceramics. Third, the electrical impedance matching for the energy harvesting circuit was considered to allow the transfer of generated power to a storage media. It was found that, by using the 10-layer ceramics instead of the single layer, the output current can be increased by 10 times, and the output load can be reduced by 40 times. Furthermore, by using the multilayer ceramics the output power was found to increase by 100%. A direct current (DC)-DC buck converter was fabricated to transfer the accumulated electrical energy in a capacitor to a lower output load. The converter was optimized such that it required less than 5 mW for operation.     

Cymbal压电发电换能器有限元分析

通过建立Cymbal压电发电换能器的机电耦合有限元分析模型,计算分析了换能器结构参数对输出电压和谐振频率的影响以及外接负载对Cymbal换能器输出电压和输出功率的影响。研究表明,为了降低换能器的工作频率和提高换能器的输出电压,应增大换能器的空腔底部直径和减小换能器的空腔高度;在选择金属端冒和压电陶瓷厚度等参数时,应综合考虑换能器系统的刚度和外界振动源的频率特性和加速度特性;在任意一个频率点上,Cymbal换能器均存在一个最佳的外接负载,使得换能器的输出功率最大,而这个最佳的负载阻抗就等于Cymbal换能器在这个工作频率点上的输出阻抗。文中还提出并分析了基于外加预应力的多振子级联方式Cymbal压电发电换能器系统的结构。     

Double synchronized switch harvesting (DSSH): a new energy harvesting scheme for efficient energy extraction

This paper presents a new technique for optimized energy harvesting using piezoelectric microgenerators called double synchronized switch harvesting (DSSH). This technique consists of a nonlinear treatment of the output voltage of the piezoelectric element. It also integrates an intermediate switching stage that ensures an optimal harvested power whatever the load connected to the microgenerator. Theoretical developments are presented considering either constant vibration magnitude, constant driving force, or independent extraction. Then experimental measurements are carried out to validate the theoretical predictions. This technique exhibits a constant output power for a wide range of load connected to the microgenerator. In addition, the extracted power obtained using such a technique allows a gain up to 500% in terms of maximal power output compared with the standard energy harvesting method. It is also shown that such a technique allows a fine-tuning of the trade-off between vibration damping and energy harvesting.     

宽频压电振动能量采集器的力-电输出特性分析

压电振动能量采集器是一种新型的力(加速度)-电耦合转换输出器件,为了提高单自由度悬臂梁压电振动能量采集器的输出功率和工作频带,通过在单自由度悬臂梁压电振动能量采集器模型基础上增加一个弹性放大器的方法,构造形成了具有两自由度的宽频压电振动能量采集器。利用ANSYS有限元软件建立了宽频压电能量采集器的有限元力-电耦合模型,数值分析了模型中各参数(如质量比、阻尼比以及负载电阻等)对系统力特性(速度、加速度等)和电输出特性(电压、电流、输出功率等)的影响。研究结果表明：大的质量比和小的阻尼比能够提高压电悬臂梁能量采集器的输出功率并拓展其工作频带;短路谐振状态下的匹配电阻能够使能量采集器产生较大的输出电流,而开路谐振状态的匹配电阻能够使能量采集器产生较大的输出电压,优化后的短路谐振和开路谐振最大输出功率分别达到4386.5 mW/g2和4263.4 mW/g2。频带宽度达到10 Hz,且是SDOF系统的5倍。     

A new piezoelectric energy harvesting design concept: multimodal energy harvesting skin

This paper presents an advanced design concept for a piezoelectric energy harvesting (EH), referred to as multimodal EH skin. This EH design facilitates the use of multimodal vibration and enhances power harvesting efficiency. The multimodal EH skin is an extension of our previous work, EH skin, which was an innovative design paradigm for a piezoelectric energy harvester: a vibrating skin structure and an additional thin piezoelectric layer in one device. A computational (finite element) model of the multilayered assembly - the vibrating skin structure and piezoelectric layer - is constructed and the optimal topology and/or shape of the piezoelectric layer is found for maximum power generation from multiple vibration modes. A design rationale for the multimodal EH skin was proposed: designing a piezoelectric material distribution and external resistors. In the material design step, the piezoelectric material is segmented by inflection lines from multiple vibration modes of interests to minimize voltage cancellation. The inflection lines are detected using the voltage phase. In the external resistor design step, the resistor values are found for each segment to maximize power output. The presented design concept, which can be applied to any engineering system with multimodal harmonic-vibrating skins, was applied to two case studies: an aircraft skin and a power transformer panel. The excellent performance of multimodal EH skin was demonstrated, showing larger power generation than EH skin without segmentation or unimodal EH skin.     

三角形状压电振子压电特性分析与仿真

(压电振子的几何形状是影响其振动发电的重要因素之一。在相同压电材料体积下,三角形压电振子相比于矩形和梯形压电振子具有更大的发电能力。选用悬臂梁式三角形状压电振子作为研究对象,利用有限元分析软件ANSYS进行仿真研究。建立有限元模型;通过静力学和模态分析,研究压电振子的几何形状对其输出电压、固有频率的影响规律,然后在满足原来输出电压不下降的前提下对其进行尺寸优化,提高单位体积的发电能力。在相同边界条件和外力作用下,优化尺寸模型的体积是原来的0.94倍,输出电压是原来的1.03倍,取得了很好的优化效果。     

Modeling and analysis of dual-output piezoelectric transformer operating at the thickness-shear vibration mode.

In our previous study, the multioutput piezoelectric transformer operating at the thickness-shear vibration mode was proposed and experimentally investigated. By designing a new construction of support and lead wire connection, a power density of 52.7 W/cm3 and a total output power of 169.8 W were achieved at a temperature rise less than 20 degrees C. In this work, a theoretical model was developed for the dual-output piezoelectric transformer operating at the thickness-shear vibration mode. The equivalent circuit parameters of the piezoelectric transformer were derived. Based on this, the impedance characteristics, equivalent inductance, capacitance ratio, voltage gain, and efficiency of the piezoelectric transformer were calculated. The theoretical results were verified by experimental data. Furthermore, the effect of the transformer size on the voltage gain, efficiency, output power and power density, and the effect of the load of one output on the voltage gain of another output were analyzed. Some useful guidelines were achieved by these analyses.     

被动湍流控制圆柱驰振能量收集的等效电路研究

为更好的预测驰振压电能量收获机的性能,首先建立了等效电路仿真模型(ECM)并通过实验验证,最大误差不超过10%。采用该方法分析了被动湍流控制(PTC)下圆柱驰振压电能量收集的仿真模型,且该方法可将驰振能量转化系统的质量-弹簧-阻尼(M-C-K)控制方程中各参数用等效电路的电子元件来表示,从而可以分析过往仿真手段所不能解决的直流电路耦合问题。其次,从能量收集效率角度分析了交流-直流等效电路中临界风速(Ucr)随外接载荷的变化规律,及输出电压与功率随不同风速和外界载荷的变化规律。结果表明,交流电路中Ucr随载荷的增大先增大后减小,直流电路中Ucr随载荷的增大逐渐减小。当风速达到Ucr的最大值时,驰振在任一电阻下均会发生。U≥Ucr时,驰振出现锁定现象,输出电压和功率均随着风速的增大而增大。当风速过大时,增长率有减小趋势。输出电压均随着电阻的增大而增大,功率随电阻的增大先增大后减小。相比于交流电路,直流电路的最佳负载由1.1 MΩ提高到2.0 MΩ,同时功率峰值从0.08 mW降低到0.04 mW。     

基于拓扑优化的压电分流阻尼抑振实验研究

将结构拓扑优化引入压电分流振动抑制中,以压电元件的分布面积为设计变量,压电元件产生的电荷最大化为优化目标,对压电元件的拓扑进行了优化以获得最佳抑振效果。针对悬臂梁结构,得到了对不同的结构模态进行抑制时的压电元件最优拓扑构型。建立了带有压电分流阻尼系统的悬臂梁振动控制实验模型,将压电元件拓扑优化后的压电分流阻尼系统应用于悬臂梁多阶弯曲模态的振动响应抑制实验,并对比分析了带最优拓扑和非优拓扑压电元件的悬臂梁压电分流阻尼抑振效果。结果表明,对压电元件进行拓扑优化可以明显提高压电分流阻尼系统的抑振效果。     

Transmitting electric energy through a metal wall by acoustic waves using piezoelectric transducers

The feasibility of transmitting electric energy through a metal wall by propagating acoustic waves using piezoelectric transducers is examined by studying the efficiency of power transmission and its dependence upon the relevant system parameters for a simplified system consisting of an elastic plate sandwiched by two piezoelectric layers. One of these layers models the driving transducer for generating acoustic wave, and the other layer models the receiving transducer for converting the acoustic energy into electric energy to power a load circuit. The output voltage, the output power, and the efficiency of this system are expressed as explicit functions of the system parameters. A numerical example is included to illustrate the dependence of the system performance upon the physical and geometrical parameters.     

基于并联电感同步开关控制的振动能量回收方法研究

针对振动能量回收使用的并联电感同步开关(SSHI)控制方法研究中未考虑的控制损耗、储能负载和激励环境等问题,设计了一种基于电流监控、比较器、单片机和双向电子开关的低功耗回收控制电路。单片机通过比较器产生的中断信号控制双向开关适时闭合,成功实现了并联SSHI回收控制电路的功能。以储能装置为负载时,分析了整流电压、振子电容、激励幅值和频率对并联SSHI回收电路控制效果的影响,结果表明该方法在整流电压值较高、振子电容较大、激励频率较高、激励力较小时能够更有效地提高回收效率,为并联SSHI控制方法的应用奠定了一定的理论基础。     

Modeling and analysis of dual-output piezoelectric transformer operating at thickness-shear vibration mode

In our previous study, the multioutput piezoelectric transformer operating at the thickness-shear vibration mode was proposed and experimentally investigated. By designing a new construction of support and lead wire connection, a power density of 52.7 W/cm/sup 3/ and a total output power of 169.8 W were achieved at a temperature rise less than 20 /spl deg/C. In this work, a theoretical model was developed for the dual-output piezoelectric transformer operating at the thickness-shear vibration mode. The equivalent circuit parameters of the piezoelectric transformer were derived. Based on this, the impedance characteristics, equivalent inductance, capacitance ratio, voltage gain, and efficiency of the piezoelectric transformer were calculated. The theoretical results were verified by experimental data. Furthermore, the effect of the transformer size on the voltage gain, efficiency, output power and power density, and the effect of the load of one output on the voltage gain of another output were analyzed. Some useful guidelines were achieved by these analyses.     

Modeling and fabrication of a piezoelectric vibration‐induced micro power generator

Abstract

In this paper, theoretical and experimental study on a piezoelectric vibration‐induced micro power generator that can convert mechanical vibration energy into electrical energy is presented. The mechanical‐electrical energy conversion mechanism is a voltage between two capacitors, which belong to the mechanical and the piezoelectric equivalent circuits, respectively. To verify the theoretical analysis, two clusters of transducer structures are fabricated. Piezoelectric lead zirconate titanate (PZT) material is chosen to make the energy conversion transducer. The desired shape of the piezoelectric generator with its resonance frequency in accordance with the ambient vibration source is designed by finite element analysis (FEA).

Experimental results show that the maximum output voltages are generated at the first mode resonance frequencies of the structure. The overall conversion efficiency is measured to be 33%. The experimental results coincide with the theoretical analysis.     

An exact analysis of a rectangular plate piezoelectric generator

We study thickness-twist vibration of a finite, piezoelectric plate of polarized ceramics or 6-mm crystals driven by surface mechanical loads. An exact solution from the three-dimensional equations of piezoelectricity is obtained. The plate is properly electroded and connected to a circuit such that an electric output is generated. The structure analyzed represents a piezoelectric generator for converting mechanical energy to electrical energy. Analytical expressions for the output voltage, current, power, efficiency, and power density are given. The basic behaviors of the generator are shown by numerical results.     

基于双ZnO薄膜单元并联结构的微型压电振动能量采集器(英文)

报道了一种基于ZnO压电薄膜双单元结构的压电式微型振动能量采集器,其中的双压电元件是并联结构.采用射频磁控溅射技术制备ZnO压电薄膜,同时,该压电式振动能量采集器采用微加工技术制作.测试表明该器件的共振频率为1 300 Hz,基于ZnO薄膜双单元并联结构的压电式振动能量采集器比起具有同样尺寸的传统型压电振动能量采集器有更高的输出性能.在频率为1 300 Hz,加速度为10 m/s2的外界振动激励下,该压电式振动能量采集器在1 MΩ负载电阻上产生的电压为2.06 V;当负载电阻为0.6 MΩ时,输出功率最大为1.25μW.     

多方向压电振动能量收集装置及其优化设计

摘要：为实现对不同方向环境振动能量的收集,提出了一种新颖的多方向振动能量收集装置的设计结构,装置的换能部分采用了一种Rainbow型压电结构。为提高多方向振动能量收集装置收集能量的效果,以多方向振动能量收集装置输出的总电能为目标函数,综合考虑金属弹性基片的强度、装置振动的固有频率及装置的尺寸空间要求等多种因素,采用序列二次规划法对能量收集装置的结构参数进行了优化。该多方向振动能量收集装置经过优化后,在Y向激励时,其输出的总电能为37.146μJ,比优化前提高了30.82%,当沿装置体对角线方向激励时,结构装置输出的总电能为58.715μJ,比优化前提高了29.24%,装置的能量收集效果得到了明显提高。分析结果为多方向振动能量收集装置的设计、制造及应用提供了技术依据。     

Design and fabrication of a piezoelectric transducer for wind-power generator

This study investigates the feasibility of a high-performance ZnO piezoelectric transducer for wind-power generation applications. The piezoelectric transducer is constructed of a Cu/ZnO/ITO/PET structure. Closely examining the ITO/PET substrate by a nano indenter reveals a low Young's modulus of 6.62 Gpa for specific deflections. The ZnO piezoelectric film of 965 nm is deposited on ITO/PET substrate using a RF magnetron sputtering system at room temperature. A copper layer is attached to the ZnO/ITO/PET structure to construct piezoelectric transducers. Both scanning electron microscopy and X-ray diffraction indicate that, among the favorable characteristic of the ZnO piezoelectric film include a rigid surface structure and a high c-axis preferred orientation. According to cantilever vibration theory, a transducer with a cantilever length of 9.9 mm and vibration area of 1.5 cm² is designed for natural wind. An appropriate mass loading of 0.57 g on the cantilever is critical for increasing the vibration amplitude and promoting the generated power of a piezoelectric transducer. Finally, an open circuit voltage of 1.87 V for the ZnO piezoelectric transducer at a vibration frequency of 100 Hz is obtained by an oscilloscope. After rectifying and filtering, the output power of the generator exhibits an available benefit of 0.07 μW/cm² with the load resistance of 5 MΩ.     

Dynamic bending/torsion and output power of S-shaped piezoelectric energy harvesters

This paper studies the dynamic electromechanical response of S-shaped piezoelectric energy harvesters both numerically and experimentally. The resonant frequency and output voltage of the harvesters excited by bending/torsion vibration were analyzed by three dimensional finite element method. The resonant frequency and output voltage were also measured, and a comparison was made between analysis and experiment. The effects of waviness ratio, proof mass and load resistance on the dynamic electromechanical fields and output power were then discussed in detail.