壓電振動能量擷取器在標準介面與SSHI介面之分析

The Analysis of Piezo Vibration Energy Harvester in Standard Interface and SSHI Interface

莊政縉(Cheng-Chin Chuang)

指導教授 ： 舒貽忠

國立臺灣大學/工學院/應用力學研究所/碩士(2008年)

https://doi.org/10.6342/NTU.2008.02777

摘要

本論文主要著重壓電振動能量擷取之研究，利用壓電材料特有力電耦合特性，吸收外界振動能量轉化為電能，再透過能量擷取電路將其儲存。而物理模型之建立涵蓋了力學以及電學理論為基礎，且描述彼此之間相互轉換的特性。
在能量擷取電路上，區分兩種不同介面電路加以討論。一為傳統普及的標準電路，另一為SSHI的新式電路，並分別在兩種不同力電耦合係數材料下加以討論。在標準電路介面下，中力電耦合係數材料透過電致阻尼效應可發現輸出功率僅具有單一峰值，而強力電耦合係數材料則會有兩個最佳功率輸出。然而，不論是中或強力電耦合係數材料，在SSHI電路下均只有單一峰值。除此之外，在該電路下通過最佳功率點後，持續加大系統阻抗，則兩種不同力電耦合係數材料於頻率偏移之情況下，均會發生功率衰減趨緩的現象，但此效果在強力電耦合係數材料下則較差強人意。因此，考慮外界給予激振頻率偏移共振之前提下，為求輸出功率維持穩定的特質，使用SSHI電路會較標準電路合適，尤其在中力電耦合係數材料效果更加顯著。
實驗上，受到二極體耗能效應的限制，在標準電路下之短路共振點無法被實際應用，同樣，在SSHI電路亦會因此而受到影響，有鑑於此，本文乃透過實驗方式，觀察出加速度的增加對於克服此耗能效應有相關的幫助。最後，本文亦提供了壓電串並聯的方式以提高整體輸出功率。

關鍵字

壓電振動能量擷取 ； 壓電材料 ； 能量擷取電路

並列摘要

This thesis studies energy harvesting using piezoelectric elements as energy transducer materials. The ambient vibration energy is transmitted into electrical energy via electromechanical coupling. The harvested energy is further stored by choosing suitable energy harvesting circuits. Here we propose an appropriate physical model accounting for the effect of electronic interfaces on the harvested power output.
We analyze the behavior of energy harvesting system for two different electronic circuits. One is the standard interface and the other is the relatively new interface called SSHI (synchronized switch harvesting on inductor). In each circuit, two different magnitudes of electromechanical coupling piezoelectric materials are adopted and studied. In the case of standard interface, it is found that there is only a single peak for optimal power when the coupling effect is in the medium range. On the other hand, there is a pair of optimal power for the case of strongly coupled electromechanical system. Further, it is found that there is always a single peak of power in the case of SSHI system. In this case, the output power drops significantly when the applied frequency deviates from the resonance, in particular, in the case of strongly coupled materials. Therefore, the desired output power for the SSHI system is in the case of mid-range of electromechanical coupling.
The effect of diode loss is also studied here via experiment. This effect is significant when the applied frequency is close to the short circuit resonance in both cases of standard and SSHI interfaces. One approach to overcome it is to increase the magnitude of applied acceleration. Finally, the piezoelectric elements in series and parallel forms are proposed to enhance the output power.

並列關鍵字

piezoelectric vibration energy harvesting ； piezoelectric materials ； energy harvesting circuits

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