Wideband Improvement by Switch Design Used in Mixed Parallel-Series Connection of Piezoelectric Energy Harvesters

本研究之主要目的為探討混合串並聯壓電振動子之能量擷取系統，藉由振動子各種不同的串並聯組合各自擁有不同頻率響應的效應，設計一套可以因應不同之振動頻率而切換不同之串並聯組合之壓電能量擷取系統，相對於傳統之陣列式壓電擷取系統，此能自動切換組合之智慧系統擁有更優秀的功率輸出與寬頻效果。 本論文透過PSpice 的電路模擬軟體與數值模擬，交叉地驗證此理論架構之精確性。並藉由數值模擬，尋找出能夠良好搭配此混合串並聯振動子系統的振動子特性，並設計一套準則，其準則可以以最有效的串並聯組合達到頻寬增幅的效果，另外也提出了一個阻抗固定化的設計，其設計對於此系統在實務上的使用有了重大的突破。 最後藉由LabVIEW 系統開發輔助，並搭配開關的電路設計，完成此混合串並聯壓電振動子之能量擷取系統，此系統能夠藉由本身振動子的特性準確地偵測到真實外界振動之頻率，並自動切換至此時最高效率之串並聯型態作能量擷取。此能量擷取系統，透過外界振動頻率為依據來切換振動子之串並聯型態，以產生較佳的功率輸出，故筆者設計了兩套判斷頻率區間之準則，最佳切換模式擁有最佳之切換時機判斷，不過計算上複雜；簡易切換模式，以一套快速的方法估算頻率區間，其效果也不亞於最佳切換模式，在使用上較為方便且符合實際應用之情況。 在實驗及模擬的結果顯示，透過較為快速且方便的阻抗固定設計與頻率區間之簡易切換模式下，強力電耦合強度振動子系統下功率增幅以及頻寬增幅皆有大幅地成長，至於中弱力電耦合強度振動子系統在輸出功率有略為衰減，不過在頻寬增幅上仍然有很優異的表現。由實驗結果顯示，以四根振動子系統，此混合串並聯壓電振動子能量擷取系統擁有比傳統陣列式擷取系統多了約四倍之頻寬*效果。The thesis is to study the mixed parallel-series connection of piezoelectric energy harvesters. Using the different connection of oscillators have different frequency response, so that to design energy harvesting system which can automatically switch connection of oscillators. With respect the traditional single connection of oscillators system, this smart switching system have more power boosting and broadband improvement. The proposed analytic estimates are validated numerically by PSpice circuit simulation. By numerical simulation to set up a design rule at this switching system. The design rule can effectively increase broadband improvement. There is also proposed fixed-load design. The fixed-load design for the practicality of the energy harvesters has a big breakthrough. Finally, though LabVIEW system development and design of the switching circuit to finish a mixed parallel-series energy harvesting system. This system can accurately measure the external vibration frequency and automatically switches to the optimal configuration. According to this system is based on the measurement of external vibration frequency to switch configuration of oscillators so author designed two different switching modes. The optimal switching mode has the best output power, but it calculation is more complicated. Another simple switching mode has a more convenient method to estimate the frequency interval. And its output effect no less than the optimal switching mode. The results appear in the experiment and simulation. Strong coupling harvesting system has a higher power boosting and broadband improvement in fixed-load design and simple switching mode; Medium coupling harvesting system, although there is no good power boosting but can has a good improvement of broadband. In case of four oscillators system, the smart switching harvesters has more than traditional array harvesters four times a broadband improvement in experimental results