Effect of Equivalent Constant and Output Power of Concentric Disk-Type Piezoelectric Transformer on Temperature

本文研究以壓電變壓器等效內電阻的觀點探討壓電變壓器在不同溫度下內部能量損失的變化，藉以了解壓電變壓器的輸出功率與溫度間的關係。本文將壓電變壓器的能量損失分為機械損失與介電損失，並成功的利用電路訊號量測方式將能量損失個別量測出來並與阻抗分析儀所量測的結果進行比較。 本文也針對自行研發的量測方式利用電力電子模擬軟體PSIM進行模擬與驗證，模擬結果得到，在量測壓電變壓器等效內電阻方面，其誤差均在1%附近；而在量測壓電變壓器介電損失電阻方面，其誤差在5%附近。表示利用本文所研發的量測技術確實能夠準確地量測壓電變壓器等效內電阻及介電損失電阻。 實驗結果顯示，影響壓電變壓器內部損失的主要因素為溫度與輸入電壓，且溫度與輸入電壓對壓電變壓器內部損失呈正相關特性，也就是說壓電變壓器內部損失會隨著溫度以及輸入電壓的增加而上升。此外，研究顯示在低輸入電壓時溫度為主要影響壓電變壓器內部損失的因素，但當輸入高電壓時，溫度造成壓電變壓器內部損失的變化便遠小於輸入電壓造成的變化，即輸入電壓成為影響壓電變壓器內部損失的主要因素。 本文利用量測得到的結果，說明壓電變壓器內部損失控制迴路，解釋壓電變壓器在升溫過程中內部所產生的變化。研究發現，當輸入功率使得壓電變壓器因為能量損失而溫度上升時，等效內電阻的增加與共振頻的改變會導致輸入電流的下降，促使壓電變壓器內部消耗功率降低，讓壓電變壓器的溫度達平衡。本文最後將壓電變壓器結合機械損失與介電損失探討壓電變壓器之輸出功率在不同溫度下的變化。This dissertation aims to discuss the energy losses in the piezoelectric transformer. The resistance of the equivalent circuit has been used to explore how the energy losses varies from the temperature. Losses in the piezoelectric transformer has been considered generally as two different mechanisms: dielectric and mechanical loss which we succeeded in measuring by oscilloscope. Meanwhile statistical data is adopted to compare with the experimental results by impedance Analyer. Due to the PSIM simulation software, we could simulate and verify the measure method of which the result was accurate at measuring the dielectric and mechanical loss. In addition, we found the temperature and input voltage were two major parameters to influence the energy losses in the piezoelectric transformer. When the temperature and input voltage increased, the energy losses raised accordingly. However, when we input low voltage, temperature became the major parameter to the energy losses in piezoelectric transformer. On the contrary, when we input high voltage, input voltage became the major parameter. Finally, we added the dielectric and mechanical loss to the piezoelectric transformer in order to analyze the piezoelectric transformer output power. In conclusion, the experimental results show that the energy losses control loop in the piezoelectric transformer. And result shows when the temperature increased, the output power decreased as well