以實驗探討壓電轉子在兩種不同型態下之能量擷取研究

Abstract

本研究為探討實驗上兩種不同安裝方式的壓電懸臂樑，在旋轉環境中所展現的獵能效果。而其中的壓電振子模型分別為壓電懸臂樑安裝自由端朝離圓心模型(朝外模型)，以及壓電懸臂樑安裝自由端朝向圓心模型(朝內模型)。理論方面基本上為使用Hamiltonian principle 配合著distributed parameter method，來得出兩種不同安裝型態下的解析解。在此研究中有許多成果，首先在朝外模型會因離心力作用方向與壓電懸臂樑伸長方向相同而使其勁度上升。最終使得壓電振子的共振頻調變斜率為正斜率，擁有能使共振頻與外界轉速一致的潛力。另一方面，朝內模型會因離心力作用方向與壓電懸臂樑壓縮方向相同而使勁度下降，因此能夠提高壓電振子的功率輸出，但取而代之的是失去了寬頻的能力。而本研究的除了將執行實驗來與理論比較外，也探討了在實驗上改變附加質量塊(Mt)或改變壓電懸臂樑固定端到旋轉圓心距離(r0)，其對實驗輸出結果的影響。最終發現增加附加質量塊(Mt)將會提升壓電振子的功率輸出。以及，隨著懸臂樑固定端到旋轉圓心距離(r0)增加，能夠提升功率輸出的頻寬。

The thesis presents an experimental investigation of two cantilever configurations for harvesting energy from rotational motion. A piezoelectric cantilever beam is mounted radially on a rotating body with either an outward or inward configuration. A unified approach based on the Hamiltonian principle and the distributed parameter method is employed to analyze these two different cases. There are several observations. First, the centrifugal force in the outward configuration of a rotatory harvester beam effectively stiffens the beam. As a result, the slope of resonance against driving frequency is positive, showing the potential of tracking and matching the driving frequency. On the other hand, the inward configuration leads to the softening of stiffness, giving rise to the enhancement of power at the cost of the loss of tuning ability. Both theoretical predictions are observed in the proposed experiment. Finally, the effect of tip mass and the distance between the fixed end and the center on the harvesting capability are studied for performance evaluation. It is found power increases as the increase of the tip mass. In addition, the overall bandwidth is enlarged for increasing the distance of the fixed end to the center of radius.