基于TL494恒流源的设计 - 图文

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基于TL494的恒流源设计

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电气工程及其自动化 *** 0990641** 指导老师：***

摘要

现代电子设备中使用的直流稳流电源有两大类：线性电源和开关电源。开关电源相对于线性电源具有效率、体积、重量等方面的优势，尤其是高频开关电源正变得更轻，更小，效率更高，也更可靠，这使得高频开关电源成为了应用最广泛的电源。开关恒流源是指通过对电流的采样以反映负载变化的情况，并调节变换器的脉宽（或占空比），相应地调整输出电压，保持输出电流不变。通常恒流源采样电路采集的是输出的电流信号，但实际上采集的是经过I／V转换后反应电流大小的电压信号。本文以TL494芯片作为PWM控制器，设计了一种采用半桥拓扑结构的恒流源。其相关参数为交流220V输入电压，5A输出电流，24V开路电压。重点介绍了该电源的设计思想，工作原理及特点。在此基础上，对主电路和控制电路的参数进行了计算和选取，并根据既有实验条件，设计了一块电源板，同时给出了实验波形。

关键词：TL494；半桥变换器；恒流源

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毕业设计（论文）说明书

Abstract

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DC Current Stabilized Power Supply used in the modern electronic equipment is divided into two categories:linear power supply and switch power supply.Compared with the linear power supply ,switching power supply have advantages of efficiency, volume, weight and so on,especially high frequency switching power supply is becoming lighter, smaller, more efficient and reliable, which makes the high frequency switching power supply become the most widely used power supply.Switching constant-current source can adjust pulse width and the output voltage by means of a current sampling of reflecting the change of load to keep the output current constant.Usually the constant-current source sampling circuit collects the output current signal.But in fact the acquisition is the voltage signal which can respect the current size through the I / V conversion .A design of the constant current source using a half-bridge topology withTL494 chip as PWM controller is introduced in this paper,of which the input voltage of AC 220V, output current of 5A, open circuit voltage voltage of 24V. It mainly introduces the designing idea of the power supply, the working principle and characteristics. Parameters of the main circuit and control circuit were calculated and selected on this basis.According to the existing experiment condition, a power board is designed while the experimental waveforms are given.

Keywords:TL494; half-bridge converter; constant current source

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目录

摘要 ....................................................................................................................................... 1 Abstract .................................................................................................................................. 2 第1章 绪言 ....................................................................................................................... 1

1.1 课题研究背景和意义 .......................................................................................... 5 1.2 开关电源的现状和趋势 ...................................................................................... 5 1.3 开关电源的分类 .................................................................................................. 6 1.4 恒流源的设计思想 .............................................................................................. 7 1.5 本文研究的主要内容 .......................................................................................... 8 1.6 本章小结 .............................................................................................................. 8 第2章 单元电路的设计 ................................................................................................... 8

2.1 主电路设计 .......................................................................................................... 8

2.1.1 硬开关DC/DC变换器的设计 ................................................................. 9 2.1.2 整流电路 ................................................................................................. 11 2.1.3 EMI滤波器的设计 ................................................................................. 12 2.2 控制电路的设计 ................................................................................................ 13

2.2.1 关于PWM控制芯片TL494的介绍 ..................................................... 13

2.2.2 TL494引脚的接线 .................................................................................. 16 2.3 隔离驱动电路的设计 ........................................................................................ 17

2.3.1 驱动芯片TLP250 ................................................................................... 17 2.3.2 MOSFET驱动电路 ................................................................................. 18 2.4 辅助电源的设计 ................................................................................................ 20 2.5 保护电路的设计 ................................................................................................ 21

2.5.1 防浪涌软启动电路 ................................................................................. 21 2.5.2 缓冲电路设计 ........ …… 此处隐藏：6047字，全部文档内容请下载后查看。喜欢就下载吧 ……