扭轉式壓電發電機之理論和實驗驗證

Abstract

再生能源是將環境中的能量轉換成可用的能源。許多人研究如何把環境中的能量轉換成可利用之能源。本研究利用壓電材料的特性，探討利用自然頻率讓壓電試片扭轉變形的可行性，用自行設計的實驗機構，量測壓電片的扭轉角和扭轉速度對於產生的電壓和電流之影響，且驗證壓電發電機之理論。並設計一個發電機構，能利用日常生活中的扭力成為輸入，輸出成電能。本研究利用實驗找到壓電試片三明治結構的扭轉剛度，代入推導之理論公式值與分析的理論值驗證壓電試片共振頻率。 壓電樑受扭轉實驗中，發現當扭轉的角度越大，導致壓電樑的變形量提高，致使產生的電壓與電流有上升的趨勢，符合壓電發電理論的正壓電效應，電極強度與應力成正比，因為應力集中於壓電樑的固定端，故整片壓電樑產生最大的電壓在固定端。較快的扭轉頻率，能使產生的電流稍微提升，主要是因為扭轉頻率更接近共振頻率的緣故。

Renewable energy is the energy that is converted from environmental energy and does not harm the environment. More and more people are studying how to transform ambient energy into useful energy. Ambient energy coming from environment includes, for instance, solar energy, geothermal energy, wind energy, and vibration energy. This study designs a power generation mechanism. The mechanism uses torque as the input, and the output is electrical energy. This study uses piezoelectric material characteristics-natural frequency to make piezoelectric sheets torsional vibrate. Piezoelectric sheets torsional angle and torsional velocity are found to affect voltage and current. The power generation mechanism was validated by using experimental results. This study obtains in experiments sandwich structure’s torsional stiffness, which is used to derive theoretical results. Theoretical results and simulation results are consistent. In the piezoelectric beam experiment, deformation was larger when torsion angule became bigger. The twist angle rose so that the resulting voltage and current were on the rise. This result confirms a direct piezoelectric effect. The maximum voltage amount happened at the fixed end because stress was concentrated at the fixed end. Consequently, This study proved that generation amount is proportional to the torsional frequency because higher torsional frequency is closer to the natural frequency.