单磁耦合式压电振动俘能器的建模与试验

Modeling and Tests for Magnetically Coupled Piezoelectric Vibration Energy Harvesters Using a Single Magnet

为实现高可靠性及宽频带振动能量的回收,提出了一种单磁耦合式压电振动俘能器。建立了俘能器的动力学方程,采用COMSOL仿真分析了磁铁水平耦合距离d、竖直耦合距离h及耦合角α对势能的影响;设计制作了样机,并进行了试验测试。试验结果表明,俘能器的势能曲线随水平耦合距离d减小由单势阱变为双势阱,且存在较佳的磁铁水平耦合距离(d=11 mm),使双势阱的阱深适中、俘能器的固有频率减小、有效频带变宽;竖直耦合距离h增大对有效频带的影响较小,h≤2 mm时,相较于无磁耦合(NMC)降低了固有频率;仅改变耦合角α时,存在最佳参数组合(d=14 mm、h=6 mm、α=67.5°)使俘能器获得较低的固有频率(16 Hz)和较宽的有效带宽(19.6 Hz),较无磁耦合时的有效带宽拓宽了6 Hz,进而提高了俘能器的发电性能。

In order to achieve high reliability and broadband vibration energy recovery,a magnetically coupled piezoelectric vibration energy harvester using a single magnet was proposed.The kinetic equation of the energy harvesters was established.The effects of magnet horizontal coupling distance d,vertical coupling distance h and coupling angleαon potential energy were simulated and analyzed using COMSOL.A prototype was designed and made to test the output characteristics.The testing results show that the potential energy curve of the energy harvesters changes from single potential well to double potential well as d decreases,at the same time there is a better condition where d is as 11 mm,which may make the depth of the double potential well moderate and then reduce the natural frequency of the energy harvesters and broaden the effective frequency band.The increase of h has little effect on the effective frequency band.When h≤2 mm,the natural frequency is reduced compared to non-magnetic coupling(NMC).When only changingα,there is an optimal combination of parameters(d=14 mm,h=6 mm,α=67.5°)to enable the energy harvesters to obtain a lower natural frequency(16 Hz)and a wider effective bandwidth(23.6 Hz),which is as 6 Hz wider than that of NMC,then the power generation performance of the energy harvesters is improved.