论文编号:WLX106  字数:11632,页数:22

摘    要
 LED作为一种固体光源，因其具有光效高、寿命长、稳定性好等诸多优良的特性，应用前景十分广阔。本课题针对当今LED驱动电源功耗大、体积大的不足，利用LM2575 DC/DC降压芯片设计了一种体积小、效率高、性能稳定、价格便宜的PWM驱动电源，用以恒流驱动大功率（1W）白光LED，并可通过调节外部电位器改变输出电流，实现大功率LED光强可调的目的。从测试数据可以看出该驱动电源效率可达85%；输入电压在11V到38V之间变化时，LED驱动电流及其发光强度保持恒定，实现恒流驱动的目的；当改变外围电位器阻值使总阻值在0.6Ω到3Ω之间改变时，LED的驱动电流在350mA到70mA之间变化，调节LED发光强度，达到光强可调的目的。因该驱动电源设计参数符合电动车的要求，可将该驱动电源应用在如今仍使用电珠照明的电动车上，用LED取代电珠照明以提高电动车用电效率。
关键词：大功率LED  恒流驱动  可调光  DC/DC转换器

Abstract
 As a solid light source, LED has an enormous application prospect because of its advantages, such as high efficiency, long life, stability and so on. Due to the disadvantages of the current Power Supply which has high power consumption and large volume, a PWM power supply based on LM2575 DC/DC step-down chip has been designed with the characteristics of small volume, high efficiency, steady performance, low cost. It is used to drive powerful (1W) white LED by constant current which can be adjusted by regulating external potentiometer, and the light intensity is also changeable. According to the test data, we can learn that the efficiency of the power supply can reach to 85%, and when the input voltage is changed from 11V to 38V, the LED’s drive current and luminous intensity keep constant to achieve the purpose of constant current drive. When the total resistance is changed from 0.6Ω to 3Ω by adjusting the external potentiometer, the LED’s drive current varied from 350mA to 70mA and the luminous intensity is changeable. Because the designed parameters of this power supply meet the requirements of electric motor car, the device can be applied to the electric motor car which still use lamp bulb to light. Using LED instead of lamp bulb to light, the power efficiency of electric motor car will be improved.
Keywords: Powerful LED; Constant current driver; Adjustable intensity; 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  研究动机和目的 1
1.2  研究背景及意义 1
1.2.1  研究背景 1
1.2.2  研究的意义 2
1.3  论文内容概述 2
第2章  LED简介 3
2.1  LED基本特性 3
2.1.1  LED发光原理 3
2.1.2  LED的特性曲线 3
2.2  白光LED特性 4
2.2.1  白光LED特性概述 4
2.2.2  白光LED光学特性 4
第3章  大功率LED驱动电源硬件制作 5
3.1  驱动电源参数设定 5
3.2  驱动芯片的选择 5
3.2.1  驱动芯片的分类 5
3.2.2  驱动芯片的选取 6
3.3  两种芯片设计的驱动电源比较 6
3.3.1  LM3402驱动电源设计 6
3.3.2  LM2575驱动电源设计 8
3.3.3  高效LM2575驱动电源设计 9
第4章  驱动电源性能测试与分析 11
4.1  测试仪器 11
4.2  恒流性能测试 11
4.3  可调光性能测试 12
4.3.1  光通量可调分析 12
4.3.2  LED驱动电流与光通量的关系 12
4.4  LED串联个数与电源效率关系 13
第5章  结束语 14
致  谢 15
参考文献 16
附录  测试数据表 17

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