阻尼對於放大式壓電能量汲取器之影響評估

Evaluation of Damping Effect on Magnified Piezoelectric Energy Harvester

林文主(Wen-Chu Lin) ； 羅正忠(Jeng-Jong Ro)

《中華民國振動與噪音工程學會論文集》 2014 (2014/06) Pp. 123-129

摘要

本研究目的是探討放大式壓電能量汲取器的阻尼效果。在這項研究中，Lagrange能量方程式被用來推導含阻尼放大式壓電能量汲取器的運動方程式，然後使用Laplace轉換得到輸出電壓／輸入振動的轉換函數。利用數值模擬分析法評估三種不同的壓電能量汲取器的能量轉換效率，包括傳統式的壓電能量汲取器、無阻尼放大式壓電能量汲取器和含阻尼放大式壓電能量汲取器。數值分析結果得到放大機構和柱狀結構的質量比（μ）、壓電柱狀結構的阻尼比（ξ）、放大機構的阻尼比（ξ_m）與汲能電路中的負載電阻（RL）等四個參數值對能量的轉換效率有顯著的影響。數值分析結果同時也顯示若考慮放大機構的阻尼比則會造成系統能量轉換效率有顯著的下降，而且下降百分率隨著放大機構的阻尼比上升而增加。因此由本研究結果得知放大機構阻尼比不應被忽視，否則壓電能量汲取系統的效率將會被高估。

關鍵字

壓電材料 ； 壓電能量汲取器 ； 放大式壓電能量汲取器

並列摘要

Energy harvesting is the process by which energy is derived from external sources (e.g. solar power, thermal energy, wind energy and kinetic energy), captured, and stored for small, wireless autonomous devices, like those used in wearable electronics and wireless sensor networks. Piezoelectric vibration energy harvesters convert mechanical vibrational energy into alternating electrical energy (AC). This AC is then electronically converted to DC, which can be used to drive a multitude of wireless applications or recharge a battery. The objective of this research is to investigate the damping effect on a magnified piezoelectric energy harvester. In this study, the Lagrange's energy equations are utilized to formulate the equations of motion of magnified piezoelectric energy harvester with damping. The Laplace transform of the equations of motion is derived to generate the transfer functions of output voltage to base input excitation. The performance of three types of devices; classical piezoelectric energy harvester, magnified piezoelectric energy harvester without damping and magnified piezoelectric energy harvester with damping are compared with numerical simulation. The numerical results have shown that four parameters such as the mass ratio of the mass of piezoelectric rod divided by the mass of magnified mechanism, the damping ratio of piezoelectrc rod, the damping ratio of magnified mechanism and the resistance of harvesting circuit play an important role in energy conversion efficiency. The results have also revealed the significant reduction of energy conversion efficiency if the damping in magnified mechanism is taken into consideration. The percentage of reduction in magnified harvesting system rises with the increase of damping ratio in magnified mechanism. The research concludes that the damping in magnified mechanism should not be neglected; otherwise the efficiency of energy harvesting system will be over-estimated.

並列關鍵字

Piezoelectric ； piezoelectric harvester