高功率白光LED驅動器設計

Design of High Power White Light LED Driver

張湘傑(JHANG-SIANG JIE)

指導教授 ： 范憶華

中原大學/工學院/機械工程研究所/碩士(2009年)

https://doi.org/10.6840/cycu200901620

摘要

本篇論文主要是在研究適合高功率白光LED 的驅動電路，根據 LED 的特性決定採用定電流的驅動方案，在陣列結構方面考慮到每 顆LED 的電流匹配度，將LED 全部串聯為一列。由於當返馳式轉換 器操作在DCM 時不需要額外的輸入電流控制電路，本身就為一個主 動式功因校正電路。為了兼顧成本與高功因，本論文的LED 驅動架 構都以返馳式轉換器為主體操作在不連續模式(DCM)下，而驅動方法 研討了兩種相異的定電流法，一、電壓控制電流源，二、定電流脈寬 調變。在電壓控制電流源的部份，為了節省成本與降低損耗以恆定功 率的方式得到一穩地的輸出電壓，輸出的部份則透過運算放大器與 MOSFET 得到一可調的定電流輸出。定電流脈寬的部分，電路的主 體為一單級的反馳式PFC 電路，不同於一般轉換器固定的輸出電壓， 電路中的反馳式電路將輸出電流視為一個要控制的參數，利用PWM 電路來控制轉換器的開關，達到LED 數變動下也能有穩定的電流輸 出，回授控制的部份根據頻域與時域分析的結果來設計出最佳的PI 控制器，得到一LED 數可變的驅動器。最後透過電路模擬軟體，來 分析設計出來兩種定電流方法的輸出結果。

關鍵字

發光二極體 ； 反馳式轉換器

並列摘要

This paper mainly presents the driver design for high-luminance
LED lamp. When the flyback converter working in discontinuous
conduction mode (DCM) without additional input current control circuit,
it act as an active power factor correction circuit (PFC).
In order to give consideration to circuit cost and high power factor,
the flyback converter is used as the active power factor corrector in this
thesis. We present two different methods for constant current output, one
is the voltage controlled current source, the other is called switch mode
constant current control.
First method using the constant-power-drive to get a stable output
voltage, with this we can obtain the constant current without feedback
circuit. Even the slight variety in the output voltage will influence the
output current greatly. So we continue using the second method to obtain
the constant current and compare the results in the simulation. The other
method is called switch mode constant current control, the main circuit of
the switch mode is a single-stage PFC circuit. Unlike convention
converters use output voltage as a control parameter, the switch mode
constant current control is using the output current as a feedback to get
constant current output. With the PWM controlled converter switch, we
can obtain the constant current output in the variety numbers of the LEDs.
With the part of the feedback control, we design the PI controller by the
analysis of the frequency and time domain.
After analyzing the principle of the two methods, we design the
circuit and using the IsSpice to simulate the two different circuits. From
the simulation result, we can find that the result is conform with the
purpose.

並列關鍵字

LED driver ； flyback

參考文獻

文，國立中山大學電機工程學系，July 2007。

[2] 周楷勳,“高功率切換式LED 背光源電源電路設計與分析”,碩

ON BIOMEDICAL ENGINEERING， VOL. 52, NO. 1, JANUARY

[5] Jeong Whan Lee, Tong In Oh, Sang Min Paek, Jae Sang Lee,

and Eung Je Woo “Precision Constant Current Source for Electrical