應用於旋轉環境之非線性壓電能量採集器

Abstract

本論文主要研究用於旋轉環境壓之壓電能量採集器。不同於以往傳統壓電能量採集器共振頻率固定以及頻寬的受限，此能量採集器可因安裝旋轉半徑不同，及不同配置來改變系統發電頻率以及頻寬。本論文提出三種配置模型，分別為朝外型、角度偏移型以及朝內型，討論不同配置模型下的特性，並希望透過非線性外力作用來達到拓展頻寬之效果。實驗使用兩種非線性外力作用，其中碰撞非線性利用懸臂樑末端質量塊激振時，對擋板碰撞所造成的非線性脈衝力來改變系統剛性。但因碰撞容易產生摩擦力影響系統，進而降低發電效率，因此本論文又另外導入磁力非線性至能量採集器中，希望透過非接觸力來避免摩擦力。 本論文之理論推導將以古典樑理論與壓電本構方程式為基礎，首先推出三種配置方式不同的線性理論模型，並使用數值方法解出發電電壓，透過實驗來驗證此線性理論模型。而非線性模型一樣使用數值方法解得，再用實驗驗證之。此實驗結果顯示，磁力非線性可在盡量不減少總發電量的前提下有效拓展頻寬，進而達到寬頻之效果，這也是本研究的核心目的。

This thesis studies the piezoelectric energy harvester for rotating environment. Different from a conventional piezoelectric energy harvester, whose resonant frequency is fixed and the bandwidth is limited, the resonant frequency and the bandwidth of the proposed energy harvester can be adjusted by changing the rotational radius and installation orientation. This study investigates three different orientations, which are outward, tilted, and inward orientations. The characteristics in this three models are discussed and expected to achieve a broad bandwidth through nonlinear forces. The first nonlinearity is induced by impact, which is caused by the collision between the tip mass of cantilever and the mechanical stopper to change the rigidity of the system. However, the results show that the efficiency of power generation is reduced because of the friction appears when the collision occurs. Therefore, the magnetic force is introduced to the design of the harvester and is expected to avoid friction. The theoretical model of the piezoelectric energy harvester is derived based on the classical beam theory and piezoelectric constitutive equations. Three linear model with different orientations are developed, and solved numerically to estimate the power generation. The numerical results are verified through experiments. The nonlinear models are verified through experiment results as well. The experimental results show that the magnetic nonlinearity can effectively expand the bandwidth without reducing the total power generation, which is the core purpose of this thesis.