单片机数控式直流恒流源设计(本人有可以仿真原理图，可加7932202

攀枝花学院本科毕业设计（论文）

基于单片机数控式直流恒流源设计

学生姓名：

学生学号： 200710501020 院（系 ）： 电气信息工程学院 年级专业： 2007级电子信息工程 指导教师：刘衍平 (助教/硕士)

二〇一一年六月

摘 要

摘 要

一般地，将输出恒定的电流源称为恒流源，“恒流源”这个术语，原则上是指这样一种稳定电源：它输出的电流与外部影响无关即和负载改变大小无关。实际上，大多数恒流源是用电子电路实现的，而且仅当外部条件在一定的范围内变化时才能保持输出电流基本不变。

本系统以直流电流源为核心，AT89S52单片机为主控制器，通过键盘来设置直流电源的输出电流，设置步进等级可达1mA，并可由LCD1602显示电流设定值和实际输出电流值。本系统由单片机程控设定数字信号，经过D/A转换器（TLC5615）输出模拟量，再经过运算放大器隔离放大，控制输出功率管的基极， 随着功率管基极电压的变化而输出不同的电流。单片机系统还兼顾对恒流源进行实时监控，输出电流经过电流/电压转换后，通过A/D转换芯片(TLC2543)，实时把模拟量转化为数据量，再经单片机分析处理，通过数字量形式的反馈环节，使电流更加稳定，这样构成稳定的压控电流源。实际测试结果表明，本系统能有效应用于需要高稳定度的小功率恒流源的领域。

关键字 数控直流恒流源，单片机，D/A转换器，A/D转换，电压/电流转换器

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攀枝花学院本科毕业设计(论文)

ABSTRACT

In this system the DC source is center and 89S52 version single chip microcomputer (SCM) is main controller, output current of DC power can be set by a keyboard which step level reaches 1mA, while the real output current and the set value can be displayed by LCD. In the system, the digitally programmable signal from SCM is converted to analog value by DAC (TLV5616), then the analog value which is isolated and amplified by operational amplifiers, is sent to the base electrode of power transistor, so an adjustable output current can be available with the base electrode voltage of power transistor. Using the keyboard to set the needed output current value, The SCM based on some specific algorithm to deal the certain settings for processing. Corresponding voltage output by the ADC output voltage-controlled current source circuit.On the other hand, The constant current source can be monitored by the SCM system real-timely, its work process is that output current is converted voltage, then its analog value is converted to digital value by ADC, finally the digital value as a feedback loop is processed by SCM so that output current is more stable, so a stable voltage-controlled constant current power is designed. The test results have showed that this system, compared with the traditional regulated current source, has easy to operate and features high output current stability.

Key words: Numerical control dc constant-current source，microcontroller，D/A

converter，A/D conversion

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目 录

目 录

摘 要 ........................................................................................................................................... I ABSTRACT ...................................................................................................................................... II

目 录 ............................................................................................................................................. I 1 绪 论 ......................................................................................................................................... 1 2 数控直流恒流源系统描述 ....................................................................................................... 2

2.1 系统简介 ................................................................................................................................. 2 2.2 系统总体设计 .......................................................................................................................... 3 2.3方案论证 ................................................................................................................................. 3 2.3.1 主控器 ........................................................................................................................... 3 2.3.2 供电电源 ........................................................................................................................ 3 2.3.3 恒流源 ........................................................................................................................... 4 2.3.4 DAC和ADC方案论证 ....................................................................................................... 5 2.3.5 键盘 ............................................................................................................................... 6 2.3.6 显示 ............................................................................................................................... 6

3 系统硬件设计 ........................................................................................................................... 8

3.1 主控电路设计 .......................................................................................................................... 8 3.2 供电电源设计 ......................................................................................................................... 9 3.2.1 主电源 ........................................................................................................................... 9 3.2.2 单片机电源（第二级电源） .......................................................................................... 10 3.2.3 电源参数计算[10] ........................................................................................................... 10 3.3 恒流源电路设计 ..................................................................................................................... 12 3.4 D/A转换电路设计 .................................................................................................................. 12 3.4.1 D/A和A/D转换器介绍[12] ............................................................................................ 12

[12]3.4.2 理论分析与参数计算 ................................................................................................. 16 3.4测电路设计 ............................................................................................................................ 16 3.4.1电流检测原理介绍[2] ...................................................................................................... 16

[2]3.4.2 采样电阻的计算 ....................................................................................................... 16 3.6 键盘电路设计 ........................................................................................................................ 17 3.7 显示电路设计 ........................................................................................................................ 18 3.7.1 LCD1602的介绍 ............................................................................................................ 18 3.8 PCB板的制作 ......................................................................................................................... 19

4 系统软件设计 ......................................................................................................................... 22

4.1 软件结构设计[8] ...................................................................................................................... 22 4.1.1 系统软件的结构 ........................................................................................................... 22 4.1.2 总体流程 .................................................................................................................... 23 4.2 指标测试和测试结果 ............................................................................................................... 24 4.3 程序设计.............................................................................................................................. 32

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