毕业设计（论文）-基于单片机的数控直流恒流源的设计.doc

基于单片机的数控直流恒流源的设计
摘要
恒流源,是一种能够向负载提供恒定电流的电源。恒流源的应用范围非常广泛,并且在许多情况下是必不可少的。它既可以为各种放大电路提供偏流以稳定其静态工作点,又可以作为其有源负载,以提高放大倍数。并且在差动放大电路、脉冲产生电路中得到了广泛应用。
本文设计了一种基于单片机控制的数控直流恒流源。该恒流源以AT89S52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TIP122构成恒流源的主体,配以高精度采样电阻及12位D/A芯片MAX532、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。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。
该系统已基本达到预期的设计目标,具有功能强、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的领域。
关键词:恒流源;PID控制算法;数字控制;单片机
The Design Of Dc Constant-Current Source
Controlled Based On SCM
Abstract
The constant current, is one kind can provide the constant current to the load the power source. Therefore the constant current application scope is widespread, and in many situations is essential. It both may provide the bias for each kind of amplifying circuit by to stabilize its static operating point, and may take its active load, enhances the enlargement factor. And in the differential motion amplifying circuit, the pulse produced in the electric circuit to obtain the widespread application.
In the paper we designed a DC constant-current power controlled based on SCM. The system adopt AT89S52 as hard core and the main circuit of constant-current source consist of darlington device TIP122 and operational amplifier OP07 which has high mon Mode Rejection Ratio) and low temperature shift. Moreover, we adopt 12 bit D/A chip MAX532 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. 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 improvement 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 obt