悬臂梁压电发电装置的实验研究

为了进行压电陶瓷材料发电性能测试与研究,研制了一套悬臂梁压电振子发电系统.设计了悬臂梁压电振子,并对压电振子进行了有限元分析和电导测试.在此基础上,设计了能量存储电路,并在低频下对悬臂梁压电振子发电性能进行了实验研究.研究结果表明,当悬臂梁压电振子处于谐振频率状态下振动时,输出电压和功率达到最大.输出电压随着负载的增大而增大,输出功率并不随着负载的增大而增大;压电振子存在-个最佳阻抗,当负载与最佳阻抗匹配时,此时压电振子的能量转化效率最高且输出功率最大.利用本实验系统进行压电发电实验测试,当负载为50 kΩ时,压电振子输出电压为7 V;当负载电阻为15 kΩ时,此时的输出功率最大可达到1.4 mW,产生的功率可以满足无线传感器等低耗能产品的供能需求.     

基于谐波平衡法的双稳态压电发电系统非线性振动特性研究

研究双稳态压电发电系统非线性振动特性。通过谐波平衡法计算获得系统幅频响应方程,分析不同非线性系数、阻抗参数与激励对系统幅值解影响,随激励频率、幅值的变化,双稳态压电发电系统幅值解存在跳跃、多解现象,调节非线性系数及阻抗参数可使不稳定区域范围最小;研究外加激励对功率影响,随非线性系数及阻抗参数的增加,输出功率先增加后减小,通过调节磁化强度与负载阻抗可使系统输出功率最大;通过实验所得频率电压响应曲线及电阻功率响应曲线,验证系统非线性分析结果。可为双稳态压电发电系统工程应用提供理论依据。     

基于Cymbal单元的压电复合智能材料设计

本文使用有限元法对Cymbal换能器单元的设计结构进行了仿真分析,并将换能器单元谐振频率与实际测量值进行了比较。将Cymbal换能器单元进行阵列,设计了一种新型的10kHz以下的低频薄板水声智能材料。对两块不同尺寸和结构的Cymbal压电复合智能材料的发射性能进行了测量与标定。并将用Cymbal压电复合智能材料作为主动吸声系统中的吸声材料,在脉冲声管中进行了管道声有源吸声控制实验。研究结果表明,Cymbal压电复合智能材料是一种高效的薄型低频宽带水声材料。     

夹心式复合变幅杆换能器频率方程的推导

应用复合变幅杆及夹心式换能器结构,研制了一种新型夹心式发射换能器。根据等效电路理论推导了这种夹心式复合变幅杆换能器的等效电路模型,得出了换能器频率方程。考虑黄铜电极片对压电振子的密度及等效纵波声速的影响,应用等效参数理论修正了频率方程。通过实验验证,误差由修正前的2.09%降低到修正后的0.64%。     

基于单片机控制的超声换能器频率跟踪

根据超声波压电换能器在谐振状态下工作电流最大的特点,针对因负载变化或扰动导致超声压电换能器工作频率偏离固有频率的问题,设计了由单片机组成的A/D转换器及其输入输出电路组成的共振频率单闭环跟踪系统.在软件的支持下,改变单片机输出给超声功率电源的PWM波的频率,使A/D转换采集到换能器的负载电流的分流值达到最大,从而保证了超声换能器工作在最佳谐振状态.该文对设计方案的硬件和软件部分作了较为详细的分析,并给出部分硬件原理图.设计方案应用在超声乳化装置上时,实测误差低于0.5%.     

激励环境下rainbow型压电换能器发电性能分析

为提高有限体积rainbow型压电换能器的能量收集能力,针对外力和外界位移两种激励环境,通过数值模拟分析了换能器输出电压与结构参数及材料特性的影响关系。结果表明,在外力激励环境中,随着宽度及初始曲率半径的增加,换能器的输出电压单调减小;随着长度和弹性模量比的增加,换能器的输出电压不断升高;随着厚度比的增加,换能器的输出电压将呈现-最大值。在外界位移激励环境中,随着厚度比、长度和弹性模量比的增加,换能器的输出电压不断降低;随着初始曲率半径的增加,换能器的输出电压不断升高;而宽度对换能器输出电压的影响可基本忽略。另外,不论在何种激励环境中,换能器内侧压电薄膜的输出电压都要大于外侧压电薄膜的输出电压。     

旋磁激励式圆形压电振子发电机

为满足旋转机构监测系统自供电需求,设计旋磁激励式圆形压电振子发电机,并着重研究磁铁尺寸、磁铁间距、压电振子厚度等对压电振子一次受激产生的最大输出电压及总能量的影响规律。结果表明,其它条件确定时,增加磁铁尺度或减小磁铁间距均可有效提高发电机输出电压及有效速带宽度。试验获得输出电压大于12 V的转速范围为100~2 850 r/min。压电振子厚度对输出电压及总发电量均有较大影响,低转速时采用薄压电振子、高转速时采用厚压电振子有助于提高发、供电能力。0.2 mm、0.4 mm、0.6 mm厚压电振子最佳转速分别为707.5 r/min、1 301.8 r/min、2 490.4r/min,0.2 mm厚压电振子一次受激产生的电能/功率分别为0.4 mm、0.6 mm压电振子的3.1/1.7倍、6.4/2.0倍。以输出5 V供电电压为例,912 r/min时0.4 mm厚压电振子输出电能为0.6 mm厚压电振子的5倍,1710 r/min时0.6 mm厚压电振子的输出电能为0.4 mm压电振子的1.7倍。     

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。     

道路用堆叠式压电俘能单元制备与应用性能

针对现有压电换能器用于道路工程存在技术缺陷,优选出适用于道路发电的堆叠式俘能单元结构并优化尺寸,制备8种路用堆叠式压电俘能单元,借助力学性能试验评估结构强度,开发出压电俘能单元测试夹具并搭建发电性能模拟测试系统,研究了压电俘能单元的发电性能,测试了发电路面小尺寸试件的能量输出效果。结果表明:制备的堆叠式压电俘能单元结构强度良好,能够满足发电路面施工及工作的使用要求;在试验研究范围内荷载大小、加载频率、压电陶瓷片厚度及堆叠层数均与压电俘能单元的发电性能正相关,单片厚度为1.0 mm的堆叠式压电俘能单元输出的最大开路电压可达37.8 V、最大功率可达183.2 m W;典型发电路面小尺寸试件能够实现11.06 m W的能量输出,具备了理想的应用前景。     

基于分段解析法的智能弹簧隔振系统基础激励响应分析

建立了基于智能弹簧的无阻尼消极隔振系统模型,将干摩擦引起的非光滑动力系统分段线性化,用接缝法求得系统响应的解析解,并对系统可能存在的粘滑振动响应过程进行了分析。通过数值分析,研究了一组结构参数下,系统在滑移起始频率附近的运动特性随工作频率的变化情况。结果表明,在系统的滑移区域,系统响应曲线有较大的畸变,且具有丰富的运动特性,包含单周期响应、多周期亚谐响应、超谐响应、拟周期响应以及混沌响应;在系统滑移区域外,系统维持粘滞状态,基本弹簧与主动弹簧刚性联接,系统运动状态为多周期与非周期运动;通过调整压电陶瓷作动器的控制电压,智能弹簧隔振系统可实现以刚度和阻尼的组合形式减小振动能量的传递。     

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。     

Effect of subgrade on piezoelectric energy harvesting under traffic loads

Piezoelectric energy harvesting in roads generated by traffic loads was theoretically and experimentally investigated, and an indoor model of a layered road for piezoelectric transformation was developed using the traffic load model groove. Elastic double-layer beams resting on the subgrade soil were used to consider piezoelectric energy harvesting under traffic loads. Based on the vibration differential equations of elastic double-layer beams, the electromechanical equation was obtained using the Fourier transform. The experimental results of the piezoelectric energy harvesting were close to the theoretical ones, which indicated that the proposed method was useful in predicting piezoelectric energy harvesting from roads under traffic loads. The results also show that the influence of the transducer position on the output voltage and power should be considered, and that the thickness of the concrete panel and the condition of the subgrade soil can affect the output voltage and output power of the piezoelectric transducer. Moreover, the electrical energy was proportional to the vibration frequency and the excitation load.     

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.     

球形永磁阵列振动能量收集器设计与优化

为实现多方向环境能量收集,设计球形电磁式振动能量采集器。基于二维Halbach阵列设计的球面Halbach永磁阵列,较传统永磁阵列能提高线圈中磁链变化梯度,从而提高结构输出性能;建立数学解析模型,据解析结果对模型各参数进行优化;对该模型进行有限元仿真分析及实验性能测试。结果表明,该模型能有效响应空间任意方向振动,进而转化为电能;外部激励为10 Hz、激励为水平方向、负载阻值50 Ω时,该球形振动能量采集器输出电能达最大,单个线圈中最大负载功率可达0.8 mW。     

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.     

Optimal design of cubic nonlinear energy harvester device for random vibrations

Linear energy harvesters have a narrow frequency bandwidth and hence operate efficiently only when the excitation frequency is very close to the fundamental frequency of the harvester. Consequently, small variations of the excitation frequency around the harvester’s fundamental frequency drop the energy output making the harvesting process inefficient. To extend the harvester’s bandwidth, some recent solutions call for using electromechanical devices with stiffness-type nonlinearities. This work deals with the optimisation of the performance of a single degree-of-freedom electromagnetic energy harvester whose mechanical behaviour has a Duffing-type nonlinearity, as for suspended masses, to reduce the size of energy harvesting devices without affecting their power output. The vibration input is assumed as a broadband Gaussian white noise base acceleration. It is analytically shown that the optimum load resistance of the device is different to that which is dictated by the principle of impedance matching.     

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.     

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.