Study of Piezoelectric Transformer Fed Rectifiers for LED Lighting Module

• Main Authors: Yi-Ying Lai, 賴羿穎
• Other Authors: 李世光
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/11958921929916106259

碩士 === 國立臺灣大學 === 應用力學研究所 === 100 === 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.