摘要本文介绍了一种间接测温装置和控温装置的系统设计。此系统可以广泛被应用于家用电器,在此以豆浆机为例。

首先,利用安捷伦34970A数据采集控制主机,34370A热电偶套件以及Benchlink Data Logger 3配套软件获取液体中心与豆浆机杯体的温度数据。将温度数据输入Minitab进行DOE正交实验，从多个可能的误差影响因子中找到关键因子,从而得出液体中心温度与杯体温度的转移方程。然后利用NTC热敏电阻或DS18b20数字传感器与8051单片机构成系统达到测量温度与控制温度的目的。最后系统达到设计目标,测温范围为0℃～120℃；分辨力为0.1℃；精度在80℃时为 5℃。61409

毕业论文关键词  液体加热器  中心点温度  间接测量  关键因子  转移方程  DOE 

Title  indirectly measure and control the liquid temperature in the central area                                 

Abstract The essay describes a system which is able to measure and control the liquid temperature in the center area indirectly. The system can be widely used in the family appliance and actually this essay takes soybean milk maker for example.

First of all, I use Agilent 34970A data collection machine, 34370A thermocouple suite, software named Benchlink Data Logger 3 to acquire the temperature in liquid edge area and center area. And then send these data into Minitab, as we can see, Minitab can be used to design of experiment and processing data analysis .As a result, I can find the key factor from multiple impact factors and find out transfer equation between the liquid edge temperature and center liquid temperature. Finally it is possible to get the target, indirect measurement and control the liquid temperature in the central area, by the system which is composed of 8051 MCU and NTC thermal resistor or DS18b20 digital temperature sensor. At last the measurement range of the system should be 0℃～120℃. Besides, the system resolution is able to reach 0.1℃.What is also worth mentioning is that the system accuracy which is  5℃ when it is 80℃.

Keywords  liquid heater, temperature in the center area, indirect measurement, key factor, transfer equation, DOE

1 绪论 3

1.1 研究背景 3

1.1.1 课题意义 3

1.1.2 研究现状 4

1.1.3 研究目标 6

2 总体方案 6

3 系统各模块的方案论证与设计 7

3.1 电源模块的设计 7

3.2 温度采集电路的设计 8

3.2.1 系统量程和最优化设计温度区域 8

3.2.2 传感器的选型 9

3.2.3 温度采集电路的方案与原件参数 10

3.3 放大电路的设计 14

3.4 AD转换模块的设计 14

3.4.1 AD型号的选择 14

3.4.2 NTC热敏电阻与AD7705的线性插值 16

3.5 温度控制模块的设计 17

3.5.1 脉宽调制在温度控制中的应用 17

3.5.2 控制温度模块元件的选择 18

3.6 显示模块的设计 19

3.6.1 LCD液晶屏