压电式变截面悬臂梁低频振动能量收集器的设计与优化

Design and Optimization of Piezoelectric Energy Harvester For Low⁃Frequency Vibration Based on Variable Cross⁃Section Cantilever

为了降低环境振动压电能量收集器(PVEH)的固有频率(ω_(n)),提高PVEH的输出性能,提出了一种压电式变截面悬臂梁低频振动能量收集器(VCL-PVEH)。基于压电方程建立了不同压电材料分布的VCL-PVEH数值模型,优化了压电材料分布位置。研制了PVCL-PVEH原理样机,搭建样机实验平台。结果表明:当压电材料靠近悬臂梁固支端时,器件输出电压(V)和功率(P)最大;随着压电材料与固支端距离(D)增大,器件ω_(n)降低。在相同压电材料面积下,三角形VCL-PVEH的ω_(n)最低(ω_(n)=25.7 Hz)、V最大(V=100 V)。实验和计算表明,随负载阻抗(R)增大,P先增大后减小,存在最优R为25000Ω,此时,P为240 mW,可直接点亮21只商用LED,满足低功耗农业物联网传感器供电的要求。

To reduceω_(n)and improve the output performance of the piezoelectric vibration energy harvester(PVEH),a variable cross⁃section piezoelectric low⁃frequency vibration energy harvester(VCL⁃PVEH)is proposed.The numerical model of VCL⁃PVEH with different shapes(rectangle,trapezoid and triangle)of piezoelectric materials is established based on piezoelectric equations by using finite element method(FEM)&MATLAB,and the distribution position of piezoelectric materials in PVEH is optimized.Meanwhile,the VCL⁃PVEH is prepared,and a piezoelectric energy collection platform is established for the verification of the proposed model.The results show that the maximum power(P)and voltage(V)are generated when the piezoelectric material is close to the fixed end of the cantilever;As D increases,ω_(n)decreases.Specifically,when the area of piezoelectric material is certain,ω_(n)is the lowest,the value of which is 25.7 Hz,and V is the largest,the value of which is 100 V;in addition,experiments and calculations show that P first increases and then decreases with the increase of load impedance(R).It is noteworthy that P reaches 240 mW when the optimal R is 25000Ω.This high power generated can light 21 commercial LEDs,and meet the power supply requirements of micro power agricultural internet of things(Ag⁃IoT).