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论文编号:WLX109 字数:12932,页数:21摘 要 发光二极管（Light Emitting Diode，LED）作为一种固体光源，因其节能、环保、结构牢固、寿命长、启动时间短、体积小、低压驱动等诸多特性，应用前景十分巨大，因此对LED驱动电路的研究有着重要的理论意义和应用价值。本课题针对线性稳压电源功耗大、体积大的不足，设计了一种体积小、效率高、性能稳定、价格便宜的脉冲宽度调制(Pulse Width Modulation，PWM) 开关电源，用以恒流驱动LED，并可通过外部电位器改变输出电流，以达到光强可调的目的。本论文首先说明了研究的动机、目的、意义及其背景，然后根据LED的电气特性、LED驱动器的特性及系统要求，选择降压(Buck)式DC/DC变换器拓扑结构，使用LM2575-ADJ作为系统核心控制芯片，设计了一种在15 V～30 V输入电压下输出电流可在8 mA～40 mA之间变化的开关电源，本文详细说明了具体的设计过程，硬件制作及调试方法，经测试分析证明该电源基本满足恒流驱动LED的设计要求。 关键词： 发光二极管 脉冲宽度调制 开关电源 恒流驱动 降压式DC/DC变换器 Abstract LED（Light Emitting Diode）is a solid light source , it has an enormous application prospect because of its advantages , such as energy conservation, environmental protection, firm structure, long life, short start-up time, small volume, low voltage supply. So research of LED Drive Circuit has crucial significance of theory and value of application. Due to the disadvantages of the Linear Regulated Power Supply which has high power consumption and large volume, a PWM(Pulse Width Modulation) switch power supply has been designed with the characteristics of small volume, high efficiency, steady performance, low cost, used to drive LED by constant current which can be adjusted by regulating external potentiometer, and the light intensity also changes. Firstly this paper introduces the motivation, the purpose, the significance and the background of the research, then selects Buck topology DC/DC converter based on the study of the electrical characteristics and the driver’s characteristics of LED and the system requirements, takes LM2575-ADJ as the core control chip of the system, it designs a switch power supply which can convert 15 V～30 V DC power supply into 8 mA～40 mA DC output current. In this paper, the design process, the hardware making and the debugging methods of the system are introduced in detail. It proves that the power supply basically satisfied the requirement of constant current driving LED through testing and analyzing.Keywords： LED PWM switch power supply constant current driving Buck DC-DC converter 目 录中文摘要i 英文摘要．．ii 目录iii 第1章 绪论．．1 1.1 研究的动机、目的及意义．．1 1.1.1 研究的动机与目的．1 1.1.2 研究的意义．1 1.2 研究背景1 1.2.1 LED照明现状．．1 1.2.2 LED驱动电源研究状况2 1.3 论文内容概述．．2第2章 LED光源及其驱动简介．3 2.1 LED发光原理及其I-V特性3 2.2 LED驱动电路．．3 2.2.1 LED驱动器的特性．3 2.2.2 DC/DC变换器及其拓扑结构．．3第3章 LED驱动电路设计．．6 3.1 LED驱动电路设计要求6 3.2 降压型DC/DC变换器集成电路芯片的选取．．6 3.2.1 芯片的初步选取6 3.2.2 三种芯片性能比较．7 3.2.3 驱动电路控制芯片LM2575介绍．．7 3.3 LED驱动电路原理图设计及其工作原理介绍8 3.3.1 LED驱动电路原理图设计．8 3.3.2 驱动电路外围元器件的选取．．9 3.3.3 LED驱动电路工作原理．．10第4章 LED驱动电路硬件制作、调试、测试与分析．．12 4.1 硬件制作与调试．．12 4.1.1 硬件制作．．12 4.1.2 电路调试．．12 4.2 电路性能测试与分析．12 4.2.1 稳流分析．．12 4.2.2 光强可调分析．13第5章 结束语．14致谢．．15参考文献．16 |
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