旋轉敲擊式壓電發電機之阻抗匹配轉換器之設計與實現

Abstract

本論文為設計一個旋轉敲擊模式的壓電發電機，並結合阻抗匹配轉換器來達到輸出功率的最佳化，旋轉敲擊模式的概念是利用轉動的機構帶動齒輪敲擊懸臂樑式壓電片來發電 ， 例如 ： 腳踏車，電風扇．．．等，本研究使用步進馬達來取代轉動的機構，步進馬達的控制器有數種操作模式，操作方便。壓電材料的最佳輸出功率與負載有很大的關係，阻抗匹配轉換器可視為一個等效負載，因此透過調整轉換器的阻抗值可以達成輸出功率的最佳化，阻抗匹配轉換器為升降壓型轉換器，升降壓型轉換器為直流對直流轉換器的一種，轉換器在設計上必須操作於不連續導通模式才能有阻抗匹配的功能，本文設計了一個低功率的脈波寬度調整 (pulse-width modulation，PWM ) 產生器，此電路可以改變脈寬的責任周期來達到不同操作模式下的阻抗匹配。 本文設計了兩種實驗範例來驗證阻抗匹配轉換器的功能，實驗顯示脈寬調變產生電路耗電量極低，改變脈寬的責任周期的確可改變等效負載的阻抗值，轉換器可產生16.18K~39.2K廣泛的阻抗匹配，轉換器效率在600(pulses per second)pps和400pps操作模式下都有77.9%以上， 等效負載輸出功率的效率 600pps 和 400pps操作模式下都有75.3% 以上，壓電發電機在操作模式600pps下輸出功率可達391uW， 應用方面可以儲存於2.4V充電電池中或LED閃爍燈。

The thesis presents a piezoelectric generator operated in rotating tapping mode and combined with impedance matching converter to achieve optimal power output. The concept of rotating tapping mode is the use of rotating bodies let gear to tap cantilever-type piezoelectric film to generate power. Such as:bicycle,electric fan ...and so on.The thesis used stepper motor to replace the rotation of the body. The stepper motor controller has several operating mode , and it’s convenient to operate . The optimal power output of piezoelectric materials has a great relationship with the load. Impedance matching converters can be regarded as an equivalent load and by adjusting the impedance of the converter can achieve optimal power output . Impedance converter is a buck-boost converter and it’s one kind of the DC/DC converter. In order to have impedance matching function , the converter must operate in discontinuous conduction mode. The thesis design of a low-power ( pulse width modulation, PWM) generator. This circuit can modulate the width of the duty cycle to achieve impedance matching in different operation modes.

The thesis design two experimental examples to verify the impedance matching function of the converter. Experimental result shows the power consumption of pulse width modulation circuit is extremely low. Changes in pulse duty cycle can indeed change the equivalent load impedance. The converter can produce 16.18 K ~ 39.2K wide range of impedance matching . The efficiency of converter in 600(pulses per second)pps and 400pps operating mode has more than 77.9%. The output power efficiency of equivalent load in 600 pps and 400 pps operating mode has more than 75.3%. The output power of piezoelectric generator in 600pps is 391μW, applications can be stored in 2.4V rechargeable battery or LED flashing lights.