宽频压电振动能量采集器的力-电输出特性分析

压电振动能量采集器是一种新型的力(加速度)-电耦合转换输出器件,为了提高单自由度悬臂梁压电振动能量采集器的输出功率和工作频带,通过在单自由度悬臂梁压电振动能量采集器模型基础上增加一个弹性放大器的方法,构造形成了具有两自由度的宽频压电振动能量采集器。利用ANSYS有限元软件建立了宽频压电能量采集器的有限元力-电耦合模型,数值分析了模型中各参数(如质量比、阻尼比以及负载电阻等)对系统力特性(速度、加速度等)和电输出特性(电压、电流、输出功率等)的影响。研究结果表明：大的质量比和小的阻尼比能够提高压电悬臂梁能量采集器的输出功率并拓展其工作频带；短路谐振状态下的匹配电阻能够使能量采集器产生较大的输出电流,而开路谐振状态的匹配电阻能够使能量采集器产生较大的输出电压,优化后的短路谐振和开路谐振最大输出功率分别达到4386.5 mW/g2和4263.4 mW/g2。频带宽度达到10 Hz,且是SDOF系统的5倍。

Force-electrical characteristic analysis of a broadband piezoelectric vibration energy harvester

Piezoelectric vibration energy harvester is a new force (acceleration) - electrically coupled converter output device. In order to improve the output power and broad the operating frequency band of a single degree of freedom (SDOF) piezoelectric vibration energy harvester (PVEH), a two degrees of freedom (TDOF) broadband piezoelectric vibration energy harvester consisting of a SDOF PVEH and a spring amplifiers is proposed in this article. The finite element force-electrical coupled model is established by ANSYS software, and the effects of the model parameters (such as the mass ratio, the damping ratio, and load resistance, etc.) on the system vibration characteristics and electrical output characteristics are studied in detail. The results have shown that a larger mass ratio and a smaller damping ratio can both improve the piezoelectric cantilever energy harvester output power and broad its working frequency band, and a suitable matching resistor under short-circuit resonant condition can make TDOF produce larger output current, while one under open-circuit resonant condition can produce larger output voltage. After optimization, maximum power output of short-circuit resonance and open-circuit resonance reached 4386.5 mW/g2 and 4263.4 mW/g2, respectively. Band width of TDOF also reached 10 Hz,which was five times the size of SDOF.