测控论文编号:CK095   论文字数:24333,页数:52

目 录
摘要………………………………………………………………………………………….. II
Abstract……………………………………………………………………………………..Ⅲ
目录……………………………………………………………………………………….. ……Ⅳ
1绪论…………………………………………………………………………………1
1.1恒流源的应用…………………………………………………………………………1
 1.2恒流源的发展…………………………………………………………………………3
     1.3国内外现状……………………………………………………………………………4
1.4论文的研究内容………………………………………………………………………4
   2数控恒流源的设计理论和总体方案…………………………………………6
2.1  系统总体方案…………………………………………………………………….…6
2.2  系统性能指标…………………………………………………………………….…6
2.3  恒流源基本设计原理与实现方法…………………………………………….……7
     3统硬件设计……………………………………………………………….……9
 3.1  单片机功能介绍……………………………………………………………………9
 3.2  电源模块设计………………………………………………………………..……15
 3.3  A/D模块设计………………………………………………………………..……15
  3.4  D/A模块设计…………………………………………………………..…………20
      3.5  键盘接口电路设计………………………………………………….……….……22
      3.6  显示接口电路设计…………………………………………………….….………24
      3.7  计算机接口电路设计………………………………………………….…….……27
 3.8  原理图………………………………………………………………….….………28
 3.9  印制板的制作………………………………………………………….…….……29
 3.10 电路板………………………………………………………………..……………32
4系统的软件设计…………………………………………………………...……33
 4.1  控制算法………………………………………………………………..…………33
 4.2  软件流程………………………………………………………………..…………35
             4.3  上位机程序……………………………………………………………38
5统功能调试、测试与分析………………………………...……………….39
 5.1  测试仪器  39
 5.2  测试数据及结果分析  39
6总结……………………………………………………………………….……...42
参考文献……………………………………………………………………..…………….43
致谢………………………………………………………………………….……………...45
附录1 PCB图…………………………………………………….……………………….46
附录2 总电路图…………………………………………………………………………47

摘  要
 目前电源技术已逐步发展成为一门多学科互相渗透的综合性技术学科，它对现代通讯、电子仪器、计算机、工业自动化、电力工程、国防及某些高新技术提供高质量、高效率、高可靠性的电源起着关键作用。
 本文设计了一种基于单片机控制的高精度数控直流恒流源。该恒流源以AT89C52 为控制核心，采用了高共模抑制比低温漂的运算放大器OP07 和达林顿管TIP137 构成恒流源的主体，配以高精度采样电阻及12 位D/A 芯片AD5320、16 位A/D 芯片AD7715，完成了单片机对输出电流的实时检测和实时控制。人机接口采用4×4 键盘及LED 数码管显示器，控制界面直观、简洁，具有良好的人机交互性能。还具有串口通讯能力，实现了远程控制功能。
 本文在软件设计上采用增量式PID 控制算法，即数字控制器的输出只是控制量的增量。增量式控制虽然只是算法上作了一点改进，却带来了如下的优点：一是算式中不需要累加，控制增量的确定仅与最近三次的采样值有关，容易通过加权处理获得比较好的控制效果；其次是计算机每次只输出控制增量，即对应执行机构位置的变化量，故机器发生故障时影响范围小、不会严重影响生产过程。
 文章最后对该恒流源的主要性能参数进行了测定，测试结果表明：该系统已基本达到预期的设计目标，具有精度高、性能可靠、体积小、电路简单的特点，可以应用于需要高稳定度的小功率恒流源领域。

关键词：单片机；数控；恒流源；ID算法

Abstract
 At present, the technique of power supply is becoming a comprehensive technique imbued with multiplex techniques and playing a crucial role in providing the power supply with highq- uality and high efficiency to the following fields:telecommunication, technical instruments, co - mputer, industrial automatic control, electric power engineering, national defence as well as some high-technology industry.
 In the paper we designed a DC constant-current power controlled based on SCM. The system adopt AT89C52 as hard core and the main circuit of constant-current source consist of darlington device TIP137 and operational amplifier OP07 which has high CMRR(Common Mode Rejection Ratio) and low temperature shift. Moreover, we adopt 12 bit D/A chip AD5320 and 16 bit A/D chip AD7715 to realize a real-time test and control to the current output controlled based on SCM. The display interface with 4× 4 keyboard technique and LED enables operator to read the screen more intuitively.Next,the equipment can be long-distance controled by the RS232.
 This paper adopt incremental PID control algorithm in software design，namely the output
of digital controller is just the increment of controlled variable. Incremental control is a little im- provement at algorithm. However, it has some advantage as follows: first, accumulating is not
needed in equation, the decision of increment is just involved in last three sampling values and it
can obtain good controlled effect with weighted processing. Next, the computer output only co- ntrolled increment every time, namely the variable value of position corresponding operator. So the range of influence is small and it will not affect the production process when the machine get out of order.
 In the end, the paper measured the primary parameter of the constant-current source. And it
confirmed that the system has reached the anticipated objective. This system armed comprehend- sive functionalities in the following aspects: power suit, high credibility, simple circuit design. It can be used flexibly in the domain which in a demand of high-stable constant-current source with small power.
 
Keywords：MCU；igital-control；onstant-current source,；ID control arithmetic