蒲公英状压电振动能量收集装置宽频带设计

研究了蒲公英状压电振动能量收集装置的宽频带设计,以解决环境振源振动频率多变的问题。建立了蒲公英状压电振动能量收集装置谐振频率的理论模型并进行了数值模拟,结果表明,该能量收集装置的谐振频率并不是可以任意拓展的。为验证理论分析的正确性,进行了蒲公英状压电振动能量收集装置的频率响应实验,得到的实验结果与理论分析基本吻合,说明了本文理论分析的可靠性。最后对宽频带的蒲公英状压电振动能量收集装置进行了发电性能测试实验,结果表明,通过对蒲公英状压电振动能量收集装置的宽频带设计,其在20～34Hz有较大的功率输出,且最大输出功率达到了约2.3mW。本文的设计有效地拓宽了该装置的谐振频率范围,易于实现与环境振源的匹配而获得较高的能量收集能力。     

圆弧螺旋型压电能量收集器的有限元模型研究

为了分析圆弧螺旋型压电能量收集器的振动特性和输出特性,本文提出了一种有限元模型,可以在简化模型的同时改善结果的精度。对近似前后的圆弧型压电能量收集器进行了建模、仿真和测试,得到了圆弧螺旋型能量收集器的谐振频率、输出电压与输出功率。将圆弧型悬臂梁进行有限元分割成6～16个矩形结构悬臂梁,并对不同程度的有限元近似下圆弧螺旋能量收集器的谐振频率与输出性能进行分析,结果表明在有限元个数大于等于10时,谐振频率与输出性能相对误差较小。加工制备了2π圆弧螺旋型压电振动能量收集并进行了性能测试。测试结果表明螺旋能量收集器谐振频率为158 Hz,采取10边型有限元模型的理论谐振频率为153 Hz,相对误差为3.5%;最大输出功率的测试结果为53.5μW,最大输出功率的理论结果为55.2μW,相对误差为3.18%,理论结果与测试结果较为符合。     

宽频压电振动能量采集器的实验研究

为改善线性单频谐振式压电振动能量采集器的输出性能,研制了双自由度宽频压电振动能量采集器样机模型,搭建了样机实验测试平台,研究了系统刚度比和负载电阻等参数对能量采集器输出性能的影响。通过调节系统刚度比,不仅可以拓宽压电振动能量采集器的工作率带,还提高了压电振动能量采集器的输出电压和输出功率。结果表明:在基础振动加速度为40m/s~2和负载电阻为471kΩ条件下,双自由度宽频压电能量采集器的工作频带是单频系统的7倍,最大输出功率是单频系统的4.5倍。     

两端固支式双晶片压电梁建模及发电特性分析

压电梁能将机械振动转换为电能,有效解决了轨道车辆走行部件安全监测传感器的供电问题。为获取其发电特性,根据小弯曲变形理论建立压电梁的弯矩方程,按照一维压电片应力和电位移方程建立压电梁机电转换数学模型。采用Nelder-Mead单纯形算法实现结构参数优化并分析了压电梁材料、结构参数和振动频率对发电效能的影响规律,通过仿真及实验验证了理论模型的正确性。结果表明：双晶片梁的发电效能随弹性模量比增加而减小;低弹性模量的金属基底构成的压电梁,输出能量较高且共振频率低;压电梁存在最佳厚度比使其发电效能最大,铍铜的最佳厚度比为0.213,锰白铜为0.261。实测值与理论值相比,输出有效电压最大偏差为0.13 V,相对偏差小于2.8%;输出功率最大偏差为0.024 mW,相对偏差小于2.9%。     

多频响应的压电振动能量采集器的性能分析与测试

为了提升压电悬臂梁采集振动能量的能力,研究了一种具有多频振动响应的振动能量采集器。在压电悬臂梁与振动激励源之间增加一个附加梁,压电悬臂梁和附加梁的末端分别安装一个质量块,压电悬臂梁和附加梁垂直连接。附加梁的末端质量被设计为远大于压电梁的末端质量,而压电梁的一阶谐振频率在附加梁的前两阶谐振频率之间。采用该设计,压电悬臂梁的振动响应是多个谐振频带的叠加。通过建立机电解析模型,描述了所提出的振动能量采集器的振动响应和发电特性,同时制作了一个振动能量采集器样机进行试验,结果表明,与传统的悬臂梁振动能量采集器相比,所提出的振动能量采集器可以在更宽的频带范围内采集更多的振动能量。     

高性能多方向双圆弧形压电能量收集系统

为了解决传统压电能量收集系统通频带窄、功率密度低的问题,本文采用线性多模态共振法,提出一种双圆弧悬臂梁内 外反向拼接的压电能量收集系统。 两根梁上各覆盖一个压电层,压电层之间串联连接。 建立二自由度系统集总参数模型和机 电耦合模型来分析频率响应和输出性能。 对比压电层弧度不同的压电能量收集系统的输出性能,根据测试结果,当弧度为 0. 5π 时输出性能最佳。 设置激励加速度为 0. 1 g,一阶模态下,谐振频率为 82. 19 Hz,开路电压为 49. 65 V,最大输出功率为 3. 74 mW;二阶模态下,谐振频率为 119. 14 Hz,开路电压为 44. 74 V,最大输出功率为 3. 54 mW。 测试结果表明,该结构可有效 拓宽通频带宽度至 52 Hz,且功率密度高。 该压电能量收集系统结构简单易于制备,工作频带宽,可在频率波动大的环境下供 电,同时体积小、功率密度大,能在多方向激励下高效率收集能量,可应用于可穿戴设备、低功率设备等多个领域。     

复合型悬臂梁压电振子振动模型及发电试验研究

单悬臂梁压电振子俘获环境中振动能时,对环境振动频率敏感且频带有限,在谐振频率与环境振动频率不匹配的情况下,会导致压电振子俘能效率低下。基于此,设计复合型悬臂梁压电振子并建立其振动模型,采用激光测振仪对复合型悬臂梁压电振子进行扫频测试。研究结果表明,复合型悬臂梁压电振子谐振频率范围为56～72Hz,与理论分析结果基本吻合,试验验证了理论模型的正确性。相比于单悬臂梁压电振子,复合型悬臂梁压电振子有效地拓宽了其谐振频带,易于实现与环境振动源振动频率匹配以提高压电发电效率。在此基础上,进行复合型悬臂梁压电发电装置的发电能力测试,在负载为820?,工作频率为60Hz时最大输出功率达到4.9mW,产生的能量能够满足网络传感器等低耗能微电子产品的供能需求。     

间接激励式压电风力俘能器

为提高环境监测自供电系统的可靠性及风速适应性,提出一种间接激励式压电风力俘能器,通过圆柱型壳体与风场耦合作用产生的涡激振动间接激励壳体内的压电梁振动发电,具有可靠性高、动态特性调节范围宽等优点。介绍了其结构及原理,并进行了理论和试验研究。结果表明:壳体质量、压电梁质量对风力俘能器输出性能都有较大影响;当俘能器总质量确定时,试验范围内通过增加压电梁质量,减小壳体质量可以有效提高压电俘能器的输出性能;此外,不同风速下存在最佳负载使输出功率最大,且本文试验范围内输出功率及最佳负载均随风速增加而增大,风速为28m/s、电阻600kΩ时所获得的最大输出功率为0.4mW。因此,应根据实际风速范围确定合理的压电梁质量/壳体质量以提高俘能器输出能力。     

复合式电磁悬挂系统馈能特性分析

为有效回收车辆悬挂振动能量,对馈能影响因素及相互间的关系进行分析。建立复合式电磁悬挂系统(composite electrical-magnetic suspension system,简称CESS)动力学及馈能电路模型,采用功率流的方法分析悬挂系统的能量输入、输出及耗散关系。在考虑传递效率的条件下,分析电阻比、激励频率及振幅对馈能效率与馈能功率的影响。讨论了减振指标及馈能性能之间的关系,通过台架试验分析了外接电阻与悬挂相对运动速度对馈能性能的影响。结果表明:采用功率流的方法可有效分析悬挂能量流动关系,馈能效率和馈能功率受电阻比、激励频率及振幅等因素影响;悬挂系统不能同时满足最大馈能效率和最大馈能功率,悬挂系统减振及馈能性能存在一定的相互制约关系。     

基于神经网络的压电能量收集器性能预估模型

设计了一款双稳态聚偏氟乙烯（polyvinylidene fluoride,简称PVDF）梁压电振动能量收集器,并介绍了该款收集器结构特点和工作原理。为了解决传统理论模型预测与能量收集器实际输出性能的偏差,利用人工神经网络对其结构参数、激励频率和收集电能之间的非线性关系进行建模。基于误差反向传播训练的多层前馈网络建立了双稳态PVDF梁压电能量收集器的人工神经网络模型。以质量块质量、PVDF压电梁的压缩距离以及外激振力频率作为输入变量,收集器输出电压均方根（root mean square,简称RMS）值作为输出变量,采集了不同条件下压电能量收集器的实验数据。通过将仿真预测结果与实验结果对比,验证了所设计的人工神经网络能有效地预测压电能量收集器的输出特性,且无需复杂的收集器理论建模。     

Vibration control efficiency of piezoelectric shunt damping system

The piezoelectric shunt damping technique based on the direct piezoelectric effect has been known as a simple, low-lost, lightweight, and easy to implement method for passive damping control of structural vibration. In this technique, a piezoelectric material is used to transform mechanical energy to electrical energy. When applying the piezoelectric shunt damping technique to passively control structural vibration, the piezoelectric materials must be bonded on or embedded in host structure where large strain is induced during vibration, thus to ensure vibrational mechanical energy to be transformed into electrical energy as much as possible. In this paper, the concept of vibration control efficiency of a piezoelectric shunt damping system is proposed and studied theoretically and experimentally. In the study, PZT patches are used as energy converter, and the vibration control efficiency is expressed by the vibration reduction rate per area of the PZT patches. Emphasis is laid on the effect of the generalized electromechanical coupling coefficient K₃₁ on the vibration control efficiency. Four PZT patches with different sizes are bonded on the geometrical central area of four similar clamped aluminum plates, respectively, and vibration control experiments are conducted for these plates using the R-L shunt circuit. The results indicate that the bigger the coupling coefficient K₃₁, the larger the rate of vibration reduction, and hence, the higher the vibration control efficiency. It also shows that the vibration responses of the first mode of the plates bonded with different PZT patches can be reduced by about 30.5%，48.58%，85.47%, and 89.91%, respectively. It comes to a conclusion that the vibration control efficiency of the piezoelectric shunt damping system decreases with the increase of the area of the PZT patch, whereas the vibration reduction of the plate increases with the area of the PZT patch. Therefore, it is necessary to make topology optimization for the PZT patch in the vibration control utilizing the piezoelectric shunt damping technique.     

Vibration control efficiency of piezoelectric shunt damping system

The piezoelectric shunt damping technique based on the direct piezoelectric effect has been known as a simple, low-lost, lightweight, and easy to implement method for passive damping control of structural vibration. In this technique, a piezoelectric material is used to transform mechanical energy to electrical energy. When applying the piezoelectric shunt damping technique to passively control structural vibration, the piezoelectric materials must be bonded on or embedded in host structure where large strain is induced during vibration, thus to ensure vibrational mechanical energy to be transformed into electrical energy as much as possible. In this paper, the concept of vibration control efficiency of a piezoelectric shunt damping system is proposed and studied theoretically and experimentally. In the study, PZT patches are used as energy converter, and the vibration control efficiency is expressed by the vibration reduction rate per area of the PZT patches. Emphasis is laid on the effect of the generalized electromechanical coupling coefficient K ₃₁ on the vibration control efficiency. Four PZT patches with different sizes are bonded on the geometrical central area of four similar clamped aluminum plates, respectively, and vibration control experiments are conducted for these plates using the R-L shunt circuit. The results indicate that the bigger the coupling coefficient K ₃₁, the larger the rate of vibration reduction, and hence, the higher the vibration control efficiency. It also shows that the vibration responses of the first mode of the plates bonded with different PZT patches can be reduced by about 30.5%, 48.58%, 85.47%, and 89.91%, respectively. It comes to a conclusion that the vibration control efficiency of the piezoelectric shunt damping system decreases with the increase of the area of the PZT patch, whereas the vibration reduction of the plate increases with the area of the PZT patch. Therefore, it is necessary to make topology optimization for the PZT patch in the vibration control utilizing the piezoelectric shunt damping technique.     

Performance analysis of piezoelectric bimorph generator

In this paper, the theoretical model and simulation of the performance of a piezoelectric (PZT) bimorph generator is introduced. The generator consists of two piezoelectric plates bonded on a substrate metal plate. For an effective electromechanical coupling coefficient (EECC) and the generated energy, the analytical formulae are established with the thickness ratio and the Young’s modulus ratio as variables. After giving correlative material parameters, the EECC and generated energy can be computed. The results show that there is a optimal thickness ratio for a piezoelectric bimorph generator to achieve the maximum EECC and electrical energy. The EECC and generated energy decrease with an increase of the Young’s modulus ratio. In addition, the influence of mechanical source on electrical energy generation and power output is also considered.     

Performance analysis of piezoelectric bimorph generator

In this paper, the theoretical model and simulation of the performance of a piezoelectric (PZT) bimorph generator is introduced. The generator consists of two piezoelectric plates bonded on a substrate metal plate. For an effective electromechanical coupling coefficient (EECC) and the generated energy, the analytical formulae are established with the thickness ratio and the Young’s modulus ratio as variables. After giving correlative material parameters, the EECC and generated energy can be computed. The results show that there is a optimal thickness ratio for a piezoelectric bimorph generator to achieve the maximum EECC and electrical energy. The EECC and generated energy decrease with an increase of the Young’s modulus ratio. In addition, the influence of mechanical source on electrical energy generation and power output is also considered.     

宽频压电振动能量采集器的分布参数模型与实验

为解决无线传感网络节点自供电问题,提出了一种带有弹性支撑与放大的宽频压电振动能量采集器。利用Hamilton原理和Raleigh-Ritz方法,并考虑悬臂梁末端质量块的影响,建立了压电能量采集器的分布参数机电耦合模型;数值分析了能量采集器质量比、刚度比和阻尼比等参数对系统振动特性、输出特性的影响;研制了实验原理样机,搭建了实验测试平台,验证了数学模型的正确性。研究结果表明,分布参数模型比集总参数模型具有更高的预测精度。     

Passive vibration damping enhancement of piezoelectric shunt damping system using optimization approach

Piezoelectric materials can be used for structural damping because of their ability to efficiently transform mechanical energy to electrical energy and vice versa. The electrical energy may be dissipated through a connected load resistance. In this paper, a new optimization technique for the optimal piezoelectric shunt damping system is investigated in order to search for the optimal shunt electrical components of the shunt damping circuit connected to the piezoelectric patch on a vibrating structure for the structural vibration suppression of several modes. The vibration suppression optimization technique is based on the idea of using the piezoelectric shunt damping system, the integrated p-version finite element method (p-version FEM), and the particle swarm optimization algorithm (PSOA). The optimal shunt electrical components for the piezoelectric shunt damping system are then determined by wholly minimizing the objective function, which is defined as the sum of the average vibration velocity over a frequency range of interest. Moreover, the optimization technique is performed by also taking into account the inherent mechanical damping of the controlled structure with the piezoelectric patch. To numerically evaluate the multiple-mode damping capability by the optimal shunting damper, an integrated p-version FEM for the beam with the shunt damping system is modeled and developed by MATLAB. Finally, the structural damping performance of the optimal shunt damping system is demonstrated numerically and experimentally with respect to the beam. The simulated result shows a good agreement with that of the experimental result. This paper was recommended for publication in revised form by Associate Editor Eung-Soo Shin Jin-Young Jeon received his Ph.D. degree in Mechanical and Aerospace Engineering from Tokyo Institute of Technology in 2005. Dr. Jeon is currently a senior engineer at Digital Printing Division, Digital Media & Communications Business at Samsung Electronics Co., Ltd., Korea. His research interests are the areas of structural-acoustic optimization, sound quality, motion quality, and vibration control.     

磁铁间距对双稳态压电悬臂梁俘能器输出特性的影响研究

建立了双稳态压电悬臂梁俘能器的机电耦合动力学方程,基于磁偶极子模型进行了 2 个磁铁间磁力的计算,根据静态平衡点分析得到了系统发生双稳态运动时的磁铁间距范围。数值仿真分析了环境激励源振动频率发生变化时磁铁间距变化对系统平均输出功率的影响规律,设计制作了磁铁间距可调的双稳态压电悬臂梁俘能装置,并进行了环境激励频率变化条件下的压电悬臂梁振动能量捕获实验。实验结果与仿真分析具有较好的一致性,为提高双稳态压电悬臂梁俘能器的发电性能提供了一种有效途径。     

Characteristic of torsional vibration of mill main drive excited by electromechanical coupling

In the study of electromechanical coupling vibration of mill main drive system, the influence of electrical system on the mechanical transmission is considered generally, however the research for the mechanism of electromechanical interaction is lacked. In order to research the electromechanical coupling resonance of main drive system on the F3 mill in a plant, the cycloconverter and synchronous motor are modeled and simulated by the MTLAB/SIMULINK firstly, simulation result show that the current harmonic of the cycloconverter can lead to the pulsating torque of motor output. Then the natural characteristics of the mechanical drive system are calculated by ANSYS, the result show that the modal frequency contains the component which is close to the coupling vibration frequency of 42Hz. According to the simulation result of the mechanical and electrical system, the closed loop feedback model including the two systems are built, and the mechanism analysis of electromechanical coupling presents that there is the interaction between the current harmonic of electrical system and the speed of the mechanical drive system. At last, by building and computing the equivalent nonlinear dynamics model of the mechanical drive system, the dynamic characteristics of system changing with the stiffness, damping coefficient and the electromagnetic torque are obtained. Such electromechanical interaction process is suggested to consider in research of mill vibration, which can induce strong coupling vibration behavior in the rolling mill drive system.     

压电分流阻尼控制悬臂梁振动的参数优化分析

采用阻抗分析技术,根据压电材料的机电耦合特性和RLC电路的电学阻抗特性,详细推导了RLC串联压电分流阻尼系统的机械阻抗特性,研究了作单模态振动的悬臂梁在粘贴压电片后形成的压电悬臂梁系统的位移传递函数特性。借助于调谐质量阻尼减振理论,进行了压电分流阻尼系统的参数优化分析,并通过算例验证了参数优化前后压电分流阻尼系统对悬臂梁振动的被动控制效果。