非線性拉伸型壓電能量採集器之設計與分析

Design and Analysis of a Nonlinear Stretching-type Piezoelectric Energy Harvester

張皓林(Hao-Lin Chang)

指導教授 ： 蘇偉儁

國立臺灣大學/工學院/機械工程學研究所/碩士(2021年)

https://doi.org/10.6342/NTU202101186

摘要

傳統壓電懸臂梁能量採集器以彎矩方式拉伸壓電材料，有著形變量少、頻寬狹窄等問題，使得發電效率低落且不利於應用在頻率變動大的環境。因此為了有效採集能量，本研究建立一結合旋轉接頭之非線性壓電能量採集器，利用力放大機構使壓電材料在激振下產生均勻的軸向應變而提高輸出電壓，並藉由結構帶來的幾何非線性有效拓寬頻寬。本研究所提出的設計以剛體樑作為主體，剛體樑的其中一端為旋轉接頭，另一端則連接受預拉之PVDF壓電薄膜。研究中建立此系統之力學模型，分析此系統在垂直激振下的動態表現。由於此系統中壓電薄膜的剛性遠小於剛體樑，故在模型中忽略壓電薄膜的抗彎剛性，而僅考慮其抗拉剛性。除此之外，壓電薄膜的等校剛性、預拉力、加速度、長度比例與質量配置等參數，也會透過實驗結果與理論模型相互驗證，並探討個參數造成的影響。結果顯示，此壓電能量採集器在不同配置下都有一定採集能力，而其非線性硬化之特性也大幅提升頻寬。實驗中效果最佳的配置與傳統懸臂梁壓電能量採集器相比，峰值電壓可達到6.17倍而頻寬可達12.5倍，且在外接阻抗為3.42 MΩ時，最大輸出功率可達1.8 mW。

關鍵字

壓電能量採集器 ； 非線性硬化效應 ； 軸向拉伸 ； 力放大機構

並列摘要

The conventional piezoelectric cantilever energy harvester suffers from limited bandwidth and deformation of the piezoelectric layer. To overcome these disadvantages, a nonlinear stretching-type piezoelectric energy harvester is proposed in this study. The proposed design is composed of a rigid beam and an elastic beam which is covered with piezoelectric material. One end of the rigid beam is connected to a revolute joint, and the other end is connected to a re-stretched PVDF film. Due to the force amplification caused by the mechanism, PVDF can easily be stretched with even strain distribution and the output voltage can be significantly improved. The theoretical model is developed to analyze the dynamics of the proposed harvester under base excitations. In the model, the rotation of the rigid beam is considered as the only degree of freedom. Besides, the bending stiffness of the piezoelectric film is ignored and only the stretching stiffness is considered because the stiffness of the piezoelectric film is much smaller than that of the rigid beam. Furthermore, experimental study will be done to verify the theoretical model. Several parameters, including pre-stretching force, stiffness, acceleration, length ratio and mass, will be discussed in the verification. In the experimental results, the output voltage and the bandwidth of the proposed design outperforms these of the conventional cantilever design by 6.17 times and 12.5 times, respectively. The output power achieves 1.8 mW when connected to an optimal resistance of 3.42 MΩ.

並列關鍵字

Piezoelectric energy harvester ； Hardening effect ； Axial stretching ； Amplifying mechanism

參考文獻

Chandy, A. (2019). "A Review on Iot Based Medical Imaging Technology for Healthcare Applications." Journal of Innovative Image Processing, 1(01): 51-60.

Khan, M. A. and K. Salah (2018). "IoT security: Review, blockchain solutions, and open challenges." Future Generation Computer Systems, 82: 395-411.

Zantalis, F., et al. (2019). "A Review of Machine Learning and IoT in Smart Transportation." Future Internet, 11(4), 94.

Erturk, A. and D. J. Inman (2008). "A Distributed Parameter Electromechanical Model for Cantilevered Piezoelectric Energy Harvesters." Journal of Vibration and Acoustics, 130(4), 041002.

Erturk, A. and D. J. Inman (2009). "An experimentally validated bimorph cantilever model for piezoelectric energy harvesting from base excitations." Smart Materials and Structures, 18(2), 025009.