基于虚拟仪器的加热炉温控系统设计

摘要

本论文要做的课题是基于虚拟仪器的加热炉温控系统设计, 要求加热炉温度稳定在80℃, 允许有±1℃的误差。

本论文采用美国NI公司虚拟仪器开发软件LabVIEW8.5开发出一套低温电加热炉温度控制系统。系统具体设计方案如下: 由传感器测得的炉温信号经过变送环节送给数据采集卡, 采集卡对信号进行A/D转换后传输至虚拟仪器, 虚拟仪器中的PID算法对信号处理后产生控制信号, 再经过采集卡D/A转换后输出控制PWM波产生电路, 改变PWM波占空比, 产生的PWM波经过光耦MOC3041控制双向可控硅的通断, 以此改变加在电阻上的电压, 达到温控目的。

本论文首先按照上述设计方案设计了硬件电路, 接着进行系统软件的设计。经过简单的实验, 系统能够正常采集数据并显示。

关键词: 虚拟仪器, LabVIEW, 温控系统, 过零调功, PWM

Abstract

The task of this paper is to design a temperature control system based on virtual instrument of the furnace.And the requirements of the furnace temperature is stable at 80℃, allowed error of ± 1℃.

This paper adopted LabVIEW8.5, a software to develop the virtual instrument of NI company in America,developed a set of temperature control system of low-power electric heating. The system design are showed as follows: the temperature sensors send the signal of temperature change to the data acquisition card by transmitter, then the signal will be convert to digital signal and be send to the virtual instrument by the data acquisition card , and then the virtual instrument will output control signal after be processed by PID algorithm, and the control signal will be convert to analog signal by the data acquisition card and output to control PWM waves produce circuit to change the duty cycle of PWM waves, then the PWM waves will control the bidirectional thyristor through opticalcoupler MOC3041 to change the voltage in resistance so that the temperature will be changed.

This paper designed the hardware circuit in accordance with the above design scheme, followed by the design of the system software. After a simple experiment, the system can acquire and display the

III

datas normally.

Key words: virtual instrument, LabVIEW, temperature control system,zero-crossing power adjustment,PWM

摘要 ................................................................................................. I ABSTRACT (英文摘要) (Ⅱ)

目录 (Ⅲ)

第一章绪论 (1)

1.1课题的研究的目的和意义 (1)

1.2国内外发展状况 (1)

1.3本设计要做的工作 (3)

第二章虚拟仪器及LabVIEW简介 (4)

2.1虚拟仪器的基本概念 (4)

2.2虚拟仪器的特点及应用 (4)

2.3LabVIEW的含义 (5)

2.4LabVIEW的发展 (6)

2.5 LabVIEW的结构 (6)

2.6LabVIEW的优势 (6)

第三章系统总体方案及硬件电路设计 (7)

3.1系统总体方案 (7)

3.2硬件电路设计 (7)

3.2.1 传感器的选型 (7)

3.2.2 数据采集卡的选型 (9)

3.2.3 PWM波产生电路的设计 (11)

3.2.4 交流过零触发PWM脉宽调功原理 (12)

第四章温控系统软件设计 (14)

4.1登录系统设计 (14)

4.2数据采集及处理控制模块的设计 (17)

4.2.1 温度信号的采集 (17)

4.2.2 采集数据的处理 (19)

4.2.3 PID控制信号的产生 (22)

4.3数据存储模块 (24)

4.3.1 数据存入文本文件 (24)

4.3.2 数据存入TDMS文件 (25)

4.4 历史数据查看模块 (26)

4.4.1 文本文件查看方式 (26)

4.4.2 TDMS文件查看方式 (28)

4.5 打印模块 (39)

4.6 网络通信模块 (30)

4.6.1 DataSocket的数据传输 (31)

4.6.2 在Web上发布程序 (33)

4.7 加热炉温控系统的集成 (34)

总结 (37)

参考文献 (38)

致谢 (39)