電荷抵消效應對兩段式壓電片懸臂樑的能量擷取影響

The Effect of Charge Cancellation on Harvesting Energy from a Cantilever Beam with Two Segmented Piezoelectrics

陳柔妤(Rou-Yu Chen)

指導教授 ： 舒貽忠

國立臺灣大學/工學院/應用力學研究所/碩士(2021年)

https://doi.org/10.6342/NTU202103616

摘要

本論文研究旨在探討電荷抵銷效應對高模態時壓電能量擷取的影響。首先，懸臂樑受到振動產生應變，高模態會改變彎曲應變的分佈，產生的反曲點稱之為應變節點，其發生於第二模態以上的高模態，第一模態不會產生應變節點。若將壓電層直接分佈於應變節點上，系統之等效力電耦合係數的值會變小，導致輸出功率降低。為了驗證電荷抵銷效應，使用不同長度比例之兩段式壓電片懸臂樑的模型，進行研究。理論推導使用懸臂樑之分佈參數法，模擬驗證使用有限元素模擬軟體COMSOL Multiphysics。為避免電荷抵銷，將兩段式壓電片懸臂樑搭配電路正接與反接，實驗結果與預期結果相符，在第一模態時，電路反接的輸出功率趨近於0，而在第二模態，若兩段式壓電片分佈比例接近應變節點的位置，或是與應變節點相符時，電路反接的輸出功率會明顯增加，反之，若兩段式壓電片的分佈比例偏離應變節點，則電路反接提升輸出功率的效果會下降。

關鍵字

電荷抵銷 ； 高模態激振 ； 壓電能量擷取 ； 電路反接 ； 分段式壓電層 ； 應變節點

並列摘要

The thesis investigates the effect of charge cancellation on the capability of piezoelectric energy harvesting under excitation at higher resonant modes. First, the strain node is defined such that the dynamic strain distribution changes sign in the direction of beam length, as often seen in the higher resonant modes other than the fundamental mode. A consequence of it is the magnitude of effective piezoelectric constant decreases for the piezoelectric layers paved across the strain node, causing the power reduction. To examine this effect, a cantilever beam with two segmented piezoelectric layers of different lengths is prepared. The theoretical estimation of power output is derived based on the parametric distribution method of the cantilever beam and is validated by COMSOL simulation. Both normal and reversed electric connections for avoiding charge cancellations are compared. The experimental observations are found to be consistent with the predictions. They show the harvested power output almost vanishes if the electric connection is reversed and the beam is excited at the fundamental mode. On the other hand, it is increased significantly for the reverse electric connection when the segmented boundary is located at around the strain node and the device is excited at the second resonant mode. But such an enhanced effect will be decreased if the segmented boundary deviates from the location of the strain node.

並列關鍵字

Charge Cancellation ； Higher Resonant Mode Excitation ； Piezoelectric Energy Harvesting ； Reverse Electric Connection ； Segmented Piezoelectric Layers ； Strain Node

參考文獻

[1] Y. Chiu and V. F. G. Tseng. A Capacitive Vibration-to-Electricity Energy Converter with Integrated Mechanical Switches. Journal of Micromechanics and Microengineering, 18: 104004. 2008.

[2] L. Tang and Y. Yang. A Nonlinear Piezoelectric Energy Harvester With Magnetic Oscillator. Applied Physics Letters, 101: 094102, 2012.

[3] P. Basset, D. Galayko, F. Cottone, R. Guillemet, E. Blokhina, F. Marty and T. Bourouina. Electrostatic Vibration Energy Harvester with Combined Effect of Electrical Nonlinearities and Mechanical Impact. Journal of Micromechanics and Microengineering, 24: 035001, 2014.

[4] A. Abdelkefi and N. Barsallo. Nonlinear Analysis and Power Improvement of Broadband Low-Frequency Piezomagnetoelastic Energy Harvesters. Nonlinear Dynamics, 83:41-56, 2016.

[5] C. K. Thein, F. M. Foong and Y. C. Shu. Spring Amplification and Dynamic Friction Modelling of a 2DOF/2SDOF System in an Electromagnetic Vibration Energy Harvester-Experiment, Simulation, and Analytical Analysis. Mechanical Systems and Signal Processing, 132: 232-252, 2019.