本文應用壓電材料之力電偶合效應，研發一自動調頻之外伸壓電樑能量擷取系統，其能回收最佳的振能大小。吾人首先建立自動調頻外伸壓電樑的模型，並加入力電耦合效應，利用外伸壓電樑之能量式，運用模態展開法將系統之能量式予以離散化，代入拉格朗日方程式（Lagrange equation）而求得系統的運動方程式。
文中研製一自動調頻之外伸壓電樑能量擷取系統，在穩態的狀況下，藉由自動控制調整外伸壓電樑滾珠夾持之位置，使得能量擷取系統的固有頻率能隨之改變。當外界施予能量擷取系統一激振外力時，系統能自動搜尋至一滾珠夾持位置，使系統與外在環境之頻率達成一致造成共振，提高壓電材料之電能輸出。當外界頻率改變時，能量擷取系統亦能藉由電壓的驟降，得知外界頻率已改變，進而啟動系統搜尋另一最佳振能回收之位置。此能量擷取系統經實驗測試，其電能確能達到最大，實為能量回收的可行機構。

Utilizing the characteristics of PZT which can generate electrical charge induced by strain, an adjustable overhung PZT beam system is developed for maximum power harvesting. In theoretical analysis, a beam of intermediate roller support is first established, in which the electro-mechanical coupling effect of the PZT energy is included. Assumed mode method is then employed to yield the Lagrange’s equation of motion.
A self-tuning overhung PZT beam power harvesting system is set up for experimental work. This system can automatically adjust the roller position to tune the beam natural frequency according to the external excitation
frequency to yield the maximum power harvesting. Once the output voltage decreases suddenly due to the external frequency change, the control system automatically search for the new position, and the experiments showed satisfactory results. The developed mechanism provides the engineers a valuable approach to energy harvesting.

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