LED並聯結構達成電流平衡之研究

STUDY OF LED CURRENT BALANCE FOR PARALLEL STRING CONFIGURATION

葉重麟(Chung-lin Yeh)

指導教授 ： 呂虹慶

大同大學/電機資訊學院/電機工程學系所/碩士(2012年)

摘要

本篇論文提出一個簡單的發光二極體(LED)電流平衡方法，並藉由連接一被動元件以達到兩個發光二極體串之間的電流平衡與電流共享的目的。由於近年來，發光二極體被廣泛應用在照明、螢幕背光、路燈與車載燈具等等，然而單一的發光二極體串不足以提供所需的亮度，因此，逐漸採用多組串聯發光二極體串的方法。使用多組串聯發光二極體串時一個重要的問題就是兩串聯的電流會有不平衡的現象，此現象會導致明亮的不均勻。因此，這裡研究的方法就是降低因為不同的發光二極體順向電壓造成的各發光二極體串的電流不平均現象。所提出的被動元件的電流平衡方式有著降低零件使用、降低電路複雜度、節省材料成本與降低工作溫度的特點。最後，利用模擬與實驗結果來證明此方式的可行性。

關鍵字

電流平衡 ； 發光二極體照明 ； 發光二極體背光 ； 路燈

並列摘要

In this thesis, a simply current balance method of the light emitting diodes (LEDs) string via the connection of passive components is proposed to achieve current balance and current sharing between two serial LEDs strings. In recent years, the researches of LED are proposed due to the wide applications of LED in the lightings, backlight of monitor, street lights, vehicle lamps, and so on. However, a single LEDs string does not enough to provide illumination, and therefore, the multiple LEDs strings are developed. The most important issue by using the multiple LEDs strings is the unbalanced current of each LEDs string. It causes the uneven brightness as the unbalance of every LEDs string serial current occurs. Therefore, the passive component current balance method is proposed to improve the phenomenon of the unbalanced current of each LEDs string which is caused by the different forward voltages of LEDs. The advantages of the proposed method include fewer components, low complexity, cost saving, and easy to be implemented. Finally, the simulations and experimental results verify the effectiveness of the proposed method.

並列關鍵字

Current balance ； LED lighting ； Backlight ； Street light

參考文獻

[1] O. A. Ogungbenro and M. C. Ndinechi, “Design, construction and testing of multipurpose energy saving LEDs and its implications on energy crisis in Nigeria,” in Proc. 3rd IEEE Int. Conf. Adaptive Science Techn. (ICAST), Abuja, Nigeria, Nov. 24–26, 2011, pp. 226–230.

[6] Y. C. Chiang, Design and implementation of power converters for LED desk lamp with dimmer. Master Thesis, Department of Electrical Engineering, National Yunlin University of Science and Technology, Taiwan, 2009.

[8] J. Bao, C. Hu, and W. Bao, ” Design of a high-efficiency quasi-resonant LED street-lamp power supply,” in Proc. IEEE Int. Conf. Automation Logistics (ICAL), Chongqing, China, Aug. 15–16, 2011, pp. 483–487.

[10] E. C. Kang, D. Kwon, J. E. Yeon, D. S. Kim, and W. Oh, “A new low voltage detecting method for multi-string LED BLU circuit,” in Proc. 13th European Conf. Power Electron. Appl., Barcelona, Spain, Sept. 8–10, 2009, pp. 1–6.

[11] H. J. Chiu and S. J. Cheng, “LED backlight driving system for large-scale LCD panels,” IEEE Trans. Ind. Electron., vol. 54, no. 5, pp. 2751–2760, Oct. 2007.