【作者】 彭敏强；

【导师】 刘少强；

【作者基本信息】 中南大学 ， 交通信息工程及控制， 2011， 硕士

【摘要】 无线传感器网络节点通常采用电池供电,而有限的电池能量制约了无线传感器网络生命周期。随着低功耗集成电路技术与电源管理技术的进步,可通过采集环境能量为传感器节点或其他便携式电子装置补给能量,从而延长它们的工作或生命周期,避免电池的频繁更换。利用压电效应原理采集环境中的振动能是环境能量采集技术中的一种主要方式,但振动能量采集、电能转移和存储的效率偏低以及谐振响应带宽较窄是影响压电式振动能量采集技术实用化的关键因素。面向无线传感器网络应用,本文针对微小型压电式振动能量采集技术展开研究。以悬臂梁结构的压电式振动能量采集装置为研究对象,根据压电效应原理,建立了压电振子振动能量转换的理论模型,以最大输出功率为目标,采用遗传算法,对不同外部环境振动激励下压电振子的材料选择与结构参数进行了优化分析；建立了悬臂梁压电振子的有限元模型,进行了有限元仿真分析；针对悬臂梁结构的单自由度压电振子谐振响应带宽过窄的问题,设计了一种由两个梯形悬臂梁结构压电振子和连接弹簧构成的二自由度压电振子,并对其结构参数进行了优化设计；最后根据压电振子工作时的输出电能特点,设计了一种具有同步电荷转移功能、输出电压阈值可调且自身功率消耗低的功率调理电路,并利用Pspice电路仿真软件对该电路进行了仿真与优化分析。仿真结果表明本文设计的压电式振动能量采集装置具有较宽的谐振响应带宽,易于与环境振源频率匹配,同时能高效地实现振动能采集、转移和存储。更多还原

【Abstract】 Wireless sensor network (WSN) nodes are generally powered by batteries, and limited energy of battery is the key factor to influence the lifetime of WSN nodes. With the development of low-power integration circuit technology and power management technology, it is possible for using the energy scavenged directly from the ambient energy source to power this kind of device. Power supply by scavenging energy from environment can avoid changing batteries frequently and lengthen the lifetime of WSN. Harvesting vibration energy from environment is one of the fundamental modes for ambient energy harvesting technology. Increasing the bandwidth of resonance frequency and the efficiency of energy conversion and storage is very important for harvesting vibration energy from environment based on piezoelectric principle.In order to apply the energy harvesting to WSN, the mathematical expression of power output is deduced in this thesis, based on analyze of the static and dynamic model and the electrical equivalent model of the miniature-piezoelectric vibration energy generator. The selection of materials under different vibration condition and the effects of the structure parameters on performance are investigated based on the limitation of geometrical dimensions and admissible stress, the structural optimization design is developed with power output as the optimization objectives based on genetic algorithm. the finite element analysis tool is used to simulate the piezoelectric vibrator. In order to widen the frequency bandwidth of piezoelectric vibrator of generator, a two-degrees-of-freedom piezoelectric vibrator is designed, which can effectively increase the band of resonance frequency comparing with a single piezoelectric vibrator, and the parameters optimal method of the two-degrees-of-freedom piezoelectric vibrator is presented. Finally, according to the characteristic of the high output voltage of piezoelectric generator and the small eclectic current, the power conditioning circuit of piezoelectric transducer with low power consumption is designed which the output voltage can be regulated, and Pspiceis tool is used to simulate the power conditiong circuit, and the applicability of circuit is analyzed on basis of the simulation results.The simulation results demonstrate that the two-degrees-of-freedom piezoelectric vibrator can effectively increase the bandwidth of resonance frequency, and the higher conversion efficiency is obtained by the power conditioning circuit of piezoelectric transducer.更多还原