双磁耦合式压电振动俘能器的性能分析与试验

Design,Characterization and Testing of Magnetically Coupled Piezoelectric Vibration Energy Harvester Using Double Magnets

为满足远程监测系统的自供电需求,针对现有压电振动俘能器存在的问题,提出一种双磁耦合式压电振动俘能器,通过将压电振子对称安装于辅助悬臂梁两侧构成组合换能器,使压电片在俘能过程中主要受压应力。经建模仿真,获得了定磁铁间距与水平耦合间距对系统势能的影响规律,以及不同激励条件下的系统动力学响应特性。为验证俘能器原理的可行性与仿真结果的正确性,制作了样机并测试了不同条件下俘能器的输出特性。结果表明:激励频率对俘能器输出波形影响较大;选取适当的定磁铁间距和水平耦合间距(11 mm≤d≤12 mm,10 mm≤l≤16 mm),可有效降低俘能器固有频率、拓宽频带且幅频特性曲线较为平坦,进而提高了俘能器的环境适应性和可靠性;激励频率为12 Hz、16 Hz及20 Hz时,试验所获得的最大输出功率分别为1.27 mW、2.88 mW及5.31 mW,其所对应的最佳匹配电阻约为70 kΩ。

In view of some drawbacks of many existing piezoelectric vibrator energy harvesters,a magnetically coupled piezoelectric vibration energy harvester using double magnets is proposed to meet the demands of self-powered remote monitoring systems in this paper.This harvester was characterized by the combined transducer,where two piezoelectric vibrators were symmetrically fixed on each side of the additional elastic beam and thus the vibrators were mainly subjected to the unidirectional compressive stress.To figure out the effect of the involved structural parameters on the harvester’s performance,the simulation was firstly conducted based on the theoretical modelling.The results indicated that the vertical distance between two fixed magnets as well as the horizontal distance between the fixed magnet and movable magnet brought a significant impact on the potential energy of the system.Also,the dynamic response characteristics of the harvester under different excitation situations were obtained.Then,a harvester prototype was fabricated and its output characteristics was tested to verify the feasibility of the energy harvester and the correctness of the simulation results.The experimental results showed that the excitation frequency had a great influence on the output voltage waveform of the energy harvester.Meanwhile,with an appropriate vertical and horizontal distance(11≤d≤12 mm,10≤l≤16 mm),not only the natural frequency of the energy harvester could be significantly reduced and the working bandwidth could be broadened,but also a relatively flat voltage-frequency curve could be obtained in a quite wide frequency range.Thus,the environmental adaptability and reliability of the energy harvester was further improved.Besides,the maximum output powers of 1.27 mW,2.88 mW and 5.31 mW were achieved with an optimal load resistance of 70 kΩat the excitation frequency of 12 Hz,16 Hz and 20 Hz,respectively.