宽频激励下双稳态压电振动发电机供电能力分析

为了探讨双稳态压电振动发电机在宽频激励下的供电能力问题,建立了宽频激励下双稳态压电振动发电机系统的动力学模型,仿真了双稳态压电振动发电机系统的输出响应特性和不同运动状态的输出电压特性,研究了双稳态压电振动发电机系统运行在高能量轨道上的激励条件,据此优化双稳态压电振动发电机结构参数,并对传感器网络节点的用电需求和双稳态压电振动发电机的供电能力进行分析。仿真和实验结果表明:双稳态压电振动发电机在宽频激励下,其输出平均功率为3.8 m W,能够满足实际振动环境下无线传感器网络节点的用电需求。     

微型振动式压电发电机的设计与特性分析

为了设计出与应用场合相匹配的微型振动式压电发电机,采用模态分析和谐响应分析方法对压电双晶片发电机的振动特性进行了研究,并分析了压电晶片的长度、宽度、厚度、质量块质量等参数对压电发电机固有频率的影响.在此基础上,基于压电发电机的等效电路模型对发电机的发电特性进行了研究,并分析了压电发电机的上述结构参数对输出电压和功率的影...     

悬臂梁压电发电机输出特性及其影响因素分析

为研究悬臂梁压电发电机的输出特性及其影响因素,设计搭建了悬臂梁物理实验模型。通过空载、负载和短路实验测试了振动频率、振动位移和负载大小对其输出电压的影响,对比了不同尺寸压电陶瓷的发电能力,为压电式发电技术的发展和改进提供详细的数据基础和实验依据。研究表明:当振动频率接近压电振子的谐振频率时,发电机有较高电压输出,而随着振动位移的增大,输出电压会线性增加,二者相比,振动位移对输出电压的影响更显著。发电机直接带负载的能力较弱,当外界负载与发电机内阻匹配时才能保持稳定的电压输出。对于不同尺寸的压电陶瓷来说,其长宽比越接近1,发电能力越强。     

专利快讯

专利名称:带质量块的微型振动式风力发电机专利申请号:CN201010233045.5公开号:CN101908836A申请日:2010.07.22公开日:2010.12.08申请人:重庆大学本发明提出的带质量块的微型振动式风力发电机是由衬底、振动梁/膜和由该振动梁/膜支承的质量块构成,其中振动梁/膜和质量块构成了发电机的振动部分,该振动梁/膜含有压电层,     

电磁式振动发电机的机电特性分析与实验研究

设计了一种电磁式振动发电机结构,利用质量-弹簧-阻尼模型对振动发电机结构进行了数学建模,分析了电磁式振动发电机进行了机电特性,并仿真计算了正弦振动位移激励下线圈的输出电动势。结果表明,在模型基础上,发电机的输出感应电动势与输入位移激励具有相同的变化规律,说明机械能较好地传递到了电能。对设计并制作的样机进行了实验研究,发电机在振动频率10 Hz,振幅10 mm的正弦位移激励作用下,同一侧单组线圈、双组串联线圈的输出电动势峰峰值和有效值分别为3.437 V、7.684 V和0.710 V、1.988 V,实验表明,实验数值和仿真数值近似而且波形规律相同。     

基于压电纤维复合材料的洋流能发电装置发电性能分析

设计了一种基于压电纤维复合材料(MFC)的洋流能发电装置,并分析了其发电性能。以悬臂梁结构为分析对象,对影响发电性能的因素进行了分析,研究了基底材料的类型和厚度、频率、位移激励幅值、单晶和双晶结构对发电性能的影响规律。基于上述分析结论,设计了一种洋流能发电装置。分析了该发电装置的发电性能。分析结果表明,该发电装置在转子转速为500 r/min的工作条件下,最大输出功率为9.31 W,能满足功率要求。     

振动发电机的系统建模与频率特性分析

采用两自由度振动模型对振动发电机进行描述,由于非线性磁力的影响,该模型表明电磁式振动发电机是非线性非自治系统。基于该模型,对正弦振动激励下的系统响应进行仿真分析,结果表明,动子与定子的相对位移响应出现了明显的倍频现象,而输出电动势的频率分布更加复杂,不但有对应激励频率的主振动解和亚谐振动解,而且还有对应固有频率的亚谐振动解和超谐振动解,表明系统具有较强的非线性,且随着输入振动能量增大,系统的非线性特征更加明显。在10Hz正弦振动激励下的测试发现,输出电动势的幅频特性在10Hz、20Hz和30Hz处出现峰值,表明输出电动势出现了明显的倍频信号,实验结果与仿真结果的频率特性一致。     

基于振动特征的智能电缆防外破监测技术研究

电力电缆是城市输配电系统的重要组成成分,其运行状态关系着城市供电的可靠性。近年来,因施工、偷盗、改造引起的电缆外力破坏问题长期威胁电缆运行安全,但由于电缆分布广、运行环境复杂,目前缺乏有效的监测和预警方法,传统的在线监测系统因其改造成本和维护难度较大,且难以在城市电缆系统中实现主动预警。本文首先基于压电传感器研制了无线分布式的电缆外力扰动智能传感器,并对其数据处理、低功耗电源管理、取能单元以及物联网通讯方法进行了分析;通过典型外力激励下电缆振动试验,获得了电缆振动信号的时域特征和时频域特征,并提取了可用于外力扰动识别的特征参量,为建立基于物联网的分布式电缆防外破智能预警系统鉴定基础。     

永磁振动发电机的输出功率分析及实验研究

针对多线圈的振动发电机,分析了其不同模块的不同联接方式对输出功率的影响,以及能够输出的最大功率。通过软件仿真分析了在正弦激励下,线圈串联和混联的输出电动势与最大输出功率,并在频率8 Hz、振幅8 mm的正弦激励下对样机进行了实验。对比实验与仿真结果,其数值近似,波形变化规律相同,根据该研究,可以合理选择振动发电机的联接方式,来提高振动发电机的机电转换效率。     

压电陶瓷剪切模式用于超声波电动机的研究

介绍了已经采用d15逆压电效应的切变型压电陶瓷元件,如激励扭转振动的压电陶瓷环和筒以及激励行波的压电陶瓷盘等,分析了其在行波型、驻波型等超声波电动机中的应用方式和驱动机理。提出了一种新的切变型弯曲振动的压电陶瓷柱元件,并应用于弯曲摇头型超声波电动机中,有助于满足发展大应变、微型化超声波电动机的需求。     

Design and Properties of Piezoelectric Vibrator with Generating Function by FEM Analysis

Bimorph type piezoelectric vibrator with generating function is designed using Finite Element Method (FEM) and fabricated. Design of piezoelectric vibrator by FEM is focused at its length and the weight of added mass. Also, the vibration and charging properties of the fabricated piezoelectric vibrator are investigated. As the FEM analysis results, when the piezoelectric vibrator is the length of 18 mm and the additive weight of 0.3 g, its resonance frequency decrease to 150 Hz. Also, when input voltage of 20 V is applied, output voltage is 10.285 V in generating element. As the properties of piezoelectric vibrator fabricated, when input voltage is 20 V_rms, the acceleration of piezoelectric vibrator and output voltage are about 1.1 G and 10.18 V_rms, respectively. When gold capacitor of 0.0066 [F] is used as the load, the output voltage is about 3 [VDC] after 3600 [sec] driving time.     

悬臂梁式PVDF压电风能发电装置的优化设计

为了能够提高单一PVDF压电悬臂梁发电装置的输出特性,提出了改变其悬臂梁刚度的设计。建立了悬臂梁式PVDF压电风能发电装置参数化有限元模型,以风能发电装置输出电压最大化为目标,分别利用序列二次规划算法和自适应模拟退火算法进行了优化设计。基于优化设计的结果,制作了压电风能发电装置样机,并进行了实验,结果表明,当风速在4~14 m/s范围内,优化后的输出电压值均高于优化前以及单一PVDF结构,同时优化后的最大输出功率为优化前最大输出功率的4倍。     

Enhanced piezoelectric energy harvester performance using magnetic force and thermal energy

One possible approach of improving the performance of energy harvesters is to use energy harvester with an external magnetic force to create a nonlinear coupling system. In this work, we report experimental results of a single piezoelectric cantilever beam (PCB) with tip mass or conventional piezoelectric energy harvester (CPEH), and the effect of applying an external magnetic force. The output voltage and power at optimal resistance was 7.62 V and 0.62 mW, respectively, at the resonance frequency of approximately 11 Hz of a CPEH. Also, the output voltage and average power at optimal resistance was 8.56 V and 0.44 mW, respectively, at resonance frequency of 7 Hz of a PCB with fixed opposing magnet. Furthermore, the output voltage and average power at optimal resistance was 13.31 V and 1.77 mW, respectively, at resonance frequency of 11 Hz of a PCB with opposing magnet attached at a second cantilever. In addition, comparison between the experimental results of all different configurations showed a reasonable enhancement of performance of energy harvester when an external magnetic force added over the main PCB. Finally, the performance of a multisource energy harvester with magnetic, thermal and mechanical sources is also presented in this study. In this case, it is demonstrated that increase in output voltage with temperature gradient under effect of magnetic force; the results of 2^nd and 3^rd model showed 44% and 99% enhancement of its original output voltage value at 1.2 °C and 2.7 °C temperature difference, respectively.     

Electrical Signal of Piezoelectric Buzzer by Impact Testing

Abstract

The aim of this paper was to study the electrical signal produced by the commercial piezoelectric buzzer by impact testing. The experiment varied external resistor, sphere weight, incident angle of sphere weight, impact position, the depth of the embedded piezoelectric buzzer in concrete and the impact surface of the embedded piezoelectric buzzer in concrete. As a result, we found that the suitable external resistor is 500?ohm which was related with resonant resistance of piezoelectric buzzer. The electrical signal increased as a result of the increased impact force on piezoelectric buzzer. The impact force will increase as the sphere weight falls at the middle of the piezoelectric buzzer. It is expected to explain electrical signal of piezoelectric buzzer by quantitative evaluation which is the key to understand physical mechanism to embedded piezoelectric materials in the structural health monitoring application.     

Could Mexico’s capacity market design lead to gaming by generators?

The recently reformed, Mexican power sector incorporates a market for capacity, which is balanced administratively after each delivery year. Both supply and demand are determined ex post, based on generator availability and demand, respectively, during 100 critical hours. We analyze the potential incentive for generation companies to withhold supply from the capacity market by withholding generator availability during operations. We compare Mexico’s capacity market to other global markets considering this potential market power incentive and introduce possible adjustments to Mexico’s market structure.     

基础激励下水电机组轴系统的非线性动力分析

以水轮发电机组轴系统和基础耦合动力系统为研究对象,提出了带有基础随机外激励的水电机组轴系统的动力学模型。考虑机组的转子不平衡、转轮密封力等非线性作用,建立了该系统的非线性动力学微分方程。应用相应的数值仿真方法,结合轴心轨迹图、Poincaré映射图和分岔图等,研究了不同频率、不同强度和不同谱宽下的基础随机不确定性激励对主轴系统横向振动的影响。结果表明,基础激励频率的改变及强度和谱宽的变化将影响机组轴系统的运行稳定性,导致主轴系统出现多周期运动和混沌运动等复杂的非线性振动现象。研究进一步揭示了水轮发电机组轴系统的一些复杂非线性动力特性的内在机理和影响规律。     

MODELING AND SIMULATION OF PIEZOELECTRIC MEMS ENERGY HARVESTING DEVICE

ABSTRACT

Piezoelectric MEMS power generator is used to harvest energy from the ambient vibrations in the environment. This paper proposes a structure design of MEMS power generator for low-frequency applications, which is based on bulk MEMS technology and (110) Si wafer. The structure consists of a silicon cantilever with a piezoelectric layer attached. The cantilever is modeled as an Euler-Bernoulli beam with a lumped mass beneath the tip of the cantilever, and then analytical modeling and simulations are carried out using MATLAB. Simulation results show that a tradeoff between the geometric parameters and the proof mass should be made for a high output power of the device. To increase the output power, the length of piezoelectric layer can be optimized, which is not necessarily equal to that of cantilever. Simulation results point out ways to perform the optimization of MEMS power generator. The analytical modeling and simulations are also helpful for the design of macro-scale power generator.     

气隙偏心下永磁风力发电机定子电磁振动特性分析

永磁风力发电机定转子偏心会造成发电机气隙分布不均匀而产生磁场不平衡,使发电机振动加剧,严重时甚至引发转子扫膛,使发电机损坏失效。以某兆瓦级永磁风力发电机为研究对象,理论分析了气隙偏心对发电机气隙磁密和径向电磁力的影响,对于不同气隙偏心量下的风力发电机瞬态电磁场开展有限元分析,获得气隙磁密和径向电磁力分布特性变化规律,进而开展径向电磁力作用下定子谐响应分析,以掌握气隙偏心引起的定子振动响应特性。结果表明：随着气隙偏心量的增加,气隙最小处气隙磁密幅值增大,径向电磁力新增边带分量;发电机定子振动响应中工作频率的倍频幅值也随之增大,其中二阶径向模态响应幅值最大。所得结果可为发电机气隙监测方法研究提供一定的理论依据。