- 學位論文
壓電變壓器應用於發光二極體照明模組整流電路之研究
Study of Piezoelectric Transformer Fed Rectifiers for LED Lighting Module
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摘要
本論文研究內容主要為比較不同種類後端整流電路，對壓電變壓器應用於發光二極體照明模組時的影響，共比較三種整流電路：全波整流、倍流整流及使用發光二極體自身構成之全波整流。壓電變壓器是以壓電材料製成的變壓器，相較於傳統變壓器，壓電變壓器擁有許多好處，例如：體積小、能量密度高及無電磁輻射干擾。發光二極體的優點為體積小、消耗能量較少及較高的效率。然而，壓電變壓器後端之負載阻抗影響其輸出之電壓範圍及效率甚大，因此以往使用壓電變壓器時需要根據負載特性對壓電變壓器輸出端之尺寸和電極做特別設計，來獲得較高的效率。一般而言，壓電變壓器適合高負載阻抗，而發光二極體阻抗較低，並不適合做為壓電變壓器的負載。因此，發光二極體和壓電變壓器輸出的連結方式與其阻抗變換為一設計重點，亦為本論文主要討論之方向。壓電變壓器輸出為交流電壓，須將交流電整流成直流後再驅動發光二極體。一般最常使用之整流電路為全波整流電路，若使用倍流整流電路，可以使壓電變壓器匹配阻抗的範圍變大，因此應用在非壓電變壓器之匹配阻抗下，仍然可以達到高效率的規範要求。另一方面，使用發光二極體自身構成之全波整流則可免除選用電感的問題。本文將詳細比較三種整流方式的特性和效率。最後，本論文以單層圓盤型壓電變壓器為例，應用三種不同整流電路驅動發光二極體照明模組，其總功率最大可達25瓦，由模擬及實驗結果得知，在負載為發光二極體時，使用倍流整流電路可達到較高的輸出電壓及電流，且可操作之頻率範圍較寬。
並列摘要
The main purpose of this thesis is to compare three different topologies of LED drivers by using a piezoelectric transformer. There are several advantages in LEDs lighting applications, which include low profile, low power consumption, and high efficacy, etc. However, most LED drivers are based on the magnetic components, which may sacrifice the low profile advantage associated with LED lighting. On the other hand, the merits of the piezoelectric transformer are thin profile, high power density and no electromagnetic interference radiation when compared to electromagnetic transformers. Therefore, piezoelectric transformers are suitable to drive LEDs on this account. Since the output voltage of the piezoelectric transformer is highly related to the load impedance, the methods of designing the interface between the piezoelectric transformer and the LEDs are thus the key design parameters. Specifically, different interface methods lead to different temperature rise and vastly different efficiency. In this thesis, three methods are discussed in detail. They are LED self-rectifier circuit, full-wave rectifier and current doubler. Theoretical analysis of these three various topologies will be given first. Then, the theoretical prediction will be verified by the circuit simulator PSIM. Finally, the characteristics among these three driving methods will be summarized and compared. From the simulation and experimental results, utilizing the current doubler is much more suitable when the load is LED lighting module. By utilizing the current doubler rectifier, the output voltage, output current and efficiency is the highest when compared to the other two methods.
參考文獻
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