基于低频环境振动驱动的微型压电式能量收集器的结构研究

发布时间：2018-05-01 15:13

本文选题：无线传感器网络 + 能量收集器　；参考：《浙江工业大学》2014年硕士论文

【摘要】：随着无线传感器网络的发展,其能源的持续供应成为亟需解决的问题。考虑到振动能在人们生产生活中广泛存在,例如机器运行、车辆行驶、地震甚至微弱的声音波动都可以提供振动能,因此科研人员已经研发了一些通过拾取振动能转换为电能为大量微型电子设备提供电能的能量收集器件。其中由压电材料制作的微型压电能量收集器因其无需外界电源、较高的机电耦合性能和功率密度大等特性而得到广泛应用。另一方面,利用压电材料发电提供能源还可缓解大量废旧电池所造成的环境污染。应用于无线传感器网络供电的压电式能量收集器,要求结构尺寸较小,往往采用MEMS(Micro-Electro-Mechanical System)工艺制作成微型压电式能量收集器。传统的微型直压电悬臂梁能量收集器,其固有振动频率通常达到上千赫兹,难以与环境中的低频振动源形成共振,导致输出功率一般只有微瓦量级,无法保证无线传感器网络节点正常工作所需的功率。鉴于此,本文进行了微型压电式能量收集器的结构设计和优化,以降低其固有频率并提高输出电压和功率。本文从理论分析和有限元仿真两个角度之字形压电悬臂梁的发电能力进行了研究,具体内容包括：(1)建立了之字形压电悬臂能量收集器的振动数学模型,从固有频率、输出电压幅值和功率两大方面对比几何参数对之字形悬臂梁发电性能研究；(2)采用有限元软件ANSYS建立之字形压电悬臂梁的有限元模型,并对其进行静力分析、模态分析和谐响应分析,获得之字形压电悬臂梁的固有频率、电压等随结构、尺寸的变化规律,为压电能量收集器的优化设计奠定基础。仿真结果表明,梁的厚度增加,其固有频率升高；质量块的长和厚的增加,组成之字形梁的单根梁长度和宽度的增加以及组成之字形结构的梁根数增加都会导致固有频率的降低。由10根直臂梁构成的之字形结构的一阶固有振动频率仅为142Hz,满足与低频环境振动的条件。通过谐响应分析,比较获得了输出电压及功率与结构尺寸、组成梁的数目、负载电阻值的关系。当由十根梁组成之字形梁时,其产生的电压可以达到10-20V范围；最佳负载电阻为200KΩ,此时输出功率能达到1.66mW,经整流与存储有望为间断性工作的微型传感器节点提供电能。
[Abstract]:With the development of wireless sensor networks (WSN), the sustainable energy supply becomes an urgent problem. Considering that vibration can be widespread in people's production and life, such as the movement of machines, driving of vehicles, earthquakes and even weak sound fluctuations, can provide vibration energy, As a result, researchers have developed energy collection devices that convert vibration energy into electricity for a large number of micro electronic devices. The miniature piezoelectric energy collector made of piezoelectric materials has been widely used because of its high electromechanical coupling performance and high power density without external power supply. On the other hand, the use of piezoelectric materials to provide energy can also alleviate the environmental pollution caused by a large number of waste batteries. Piezoelectric energy collector, which is used in wireless sensor network power supply, requires a small size of structure, and is often made into a miniature piezoelectric energy collector using MEMS(Micro-Electro-Mechanical system technology. The traditional miniature piezoelectric cantilever beam energy collector usually has a natural vibration frequency of thousands hertz, which is difficult to resonate with the low frequency vibration source in the environment, resulting in the output power generally of only the order of microwatt. Wireless sensor network nodes can not guarantee the normal operation of the required power. In view of this, the structure design and optimization of the miniature piezoelectric energy collector are carried out in order to reduce its natural frequency and increase the output voltage and power. In this paper, the generation capacity of zigzag piezoelectric cantilever beam from two angles of theoretical analysis and finite element simulation is studied. The specific contents include: 1) the vibration mathematical model of the zigzag piezoelectric cantilever energy collector is established from the natural frequency. Comparison of output Voltage amplitude and Power with geometric parameters; A finite element model of a zigzag cantilever beam is established by using finite element software ANSYS, and the static analysis is carried out on the model of the zigzag cantilever beam by means of the finite element software ANSYS, and the finite element model of the zigzag cantilever beam is established by the finite element software ANSYS. Modal analysis of harmonic response analysis, obtained zigzag piezoelectric cantilever beam natural frequency, voltage and other changes with the structure, the size of the law, for the piezoelectric energy collector for the optimization of the design of the foundation. The simulation results show that the thickness of beam increases and the natural frequency of beam increases, and the length and thickness of mass block increase. The increase of the length and width of a single beam and the increase of the number of beams in a zigzag structure will result in the decrease of natural frequency. The first order natural vibration frequency of the zigzag structure composed of 10 straight arm beams is only 142 Hz, which satisfies the condition of low frequency ambient vibration. By harmonic response analysis, the relationship between output voltage and power and structure size, the number of beams and the value of load resistance are obtained. When the zigzag beam is composed of ten beams, the voltage can reach 10-20V, the optimum load resistance is 200K 惟, and the output power can reach 1.66mW. The rectifier and memory are expected to provide electrical energy for the micro-sensor nodes which work intermittently.
【学位授予单位】：浙江工业大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TB535;TM619

【共引文献】