摘  要
基于半导体制冷技术，针对航天、军事、医疗、生物制品、车载等特殊有限工作空间的独特需求，本文研究设计了体积小、成本低、性能高、结构合理紧凑、功耗低且节能环保的微型半导体温控箱箱体，并对恒温箱的温度及变化速率等各种参数能够实时精确控制。为高性能生物制剂、功能材料、疫苗储藏等的实验室制备方法以及性能研究提供技术支撑。
本文硬件选用TEC-19906半导体制冷片，驱动器选用恒流源电路，控制系统选用Cortex-M3内核微控制器，控制器通过PID算法控制恒流源输出电流驱动半导体制冷片产生热量，实现恒温箱体内的自动控温。由于内箱与空气不断地热量交换，在半导体制冷片恒温箱体中，它的温度不完全是均匀分布的，离源端的位置越近其温差越低，反之温差越高。因此需要对箱体内部的空气进行能量互换，通过对含能量不同的空气进行遣散可以达到箱体内温度温差减小。尽可能地使箱体内温度分布均匀。半导体恒温箱的控制使用空气强行互换能量的方式，提高了箱体内空气之间的能量互换率，由此在箱体内的环境产生一块温度恒定的领域，此领域内温度匀和没有差别，且能快捷地响应控制系统的温度改变。此系统具有布局不复杂、控制精度高、可靠性好、性能稳定等益处，具有辽阔的应用舞台。
关键词：TEC-19906半导体；PID算法；Cortex-M3；恒温箱
Abstract
Based on semiconductor refrigeration technology, for the unique needs of special limited working spaces such as aerospace, military, medical, biological products, and vehicle, this paper has designed a small semiconductor with small size, low cost, high performance, reasonnable and compact structure, low power consumption, and energy saving and environmental protection. The temperature control box body can accurately control the temperature and change rate of the constant temperature box in real time. It provides technical support for laboratory preparation methods and performance research of high-performance biological agents, functional materials, and vaccine storage
In this paper, the TEC-19906 semiconductor cooling chip is used for the hardware, the constant current source circuit is used for the driver, and the Cortex-M3 core microcontroller is used for the control system. The controller controls the constant-current source output current through the PID algorithm to drive the semiconductor cooling chip to generate heat, thereby realizing the body of the calorstat. Automatic temperature control. Due to the constant heat exchange between the inner box and the air, its temperature is not completely evenly distributed in the constant temperature box of the semiconductor refrigeration sheet. The closer to the source end, the lower the temperature difference, and vice versa. Therefore, it is necessary to perform air convection on the cabinet to make the temperature distribution in the cabinet as uniform as possible. By dispersing the hot and cold air, the temperature difference in the cabinet can be reduced. The semiconductor constant temperature box adopts forced air convection to increase the heat exchange rate between the air in the storage room, thus forming a constant temperature control area in a three-dimensional space area at a certain distance from the storage room, the temperature distribution in the area is uniform and no difference, And can quickly respond to the temperature switching of the semiconductor chip. The system has the advantages of simple structure, high control accuracy, good reliability and stable performance, and has a wide range of application prospects.
Keywords: TEC-19906 semiconductor; Cortex-M3; PID algorithm; calorstat
目    录
引言 1
1  系统整体框架 2
1.1系统设计要求 2
1.2系统设计思路 2
1.3 驱动器方案介绍 3
1.3.1 PWM脉冲宽度调制原理介绍 3
1.3.2 PID自动控制算法介绍 3
1.3.3 Buck降压斩波电路介绍 5
1.3.4电流采样原理介绍 6
1.4 温度传感器介绍 8
1.5 本章小结 9
2  硬件设计 10
2.1 电源电路设计 10
2.1.1开关电源的工作特点 10
2.1.2系统电源电路 10
2.2 中央控制器电路 12
2.3 恒流源电路设计 13
2.3.1 PWM输出电路 14
2.3.2电流采样电路 15
2.3.3 Buck同步降压恒流源电路 16
2.4 传感器电路设计 17
2.4.1温度检测电路 17
2.5 按键输入电路设计 17
2.6 显示电路设计 18
2.7 本章小结 18
3  程序设计 19
3.1 整体程序设计框架 19
3.2 电流环程序设计 20
3.2.1 PWM输出程序设计 20
3.2.2 AD采样程序设计 21
3.2.3 PID电流环闭环程序设计 23
3.3 温度环程序设计 26
3.3.1 DS18B20温度传感器工作过程 26
3.3.2温度采集程序设计 27
3.3.3串级PID温度环闭环程序设计 28
3.4 OLED显示程序设计 31
3.4.1 OLED显示原理 31
3.4.2 OLED显示程序设计 32
3.5 按键输入程序设计 33
3.6 本章小结 35
4  结论 36
谢  辞 37
参考文献 38
附  录 39