基于AD8227的热电偶动态冷端补偿通用设计  

General Design of Thermocouple Cold Junction Dynamic Compensation Based on AD8227

作　　者：皇迎港 任勇峰[1] 张凯华[1] HUANG Yinggang;REN Yongfeng;ZHANG Kaihua(State Key Laboratory of Electronic Measurement Technology,North University of China,Taiyuan Shanxi 030051,China)

机构地区：[1]中北大学电子测试技术国家重点实验室,山西太原030051

出　　处：《电子器件》2023年第3期673-677,共5页Chinese Journal of Electron Devices

摘　　要：在航空航天领域中,明确航天器壳体自身的温度分布特征,可以为优化结构和监测设备是否正常运转提供参考依据,热电偶作为航天领域经典的测温元件,其应用十分广泛,但传统的热电偶在冷端补偿电路设计时,会将冷端的温度固定为某一环境温度,以此展开补偿设计,这在高精度测量时,会引入误差。针对此问题,本文采用AD8227和AD590设计了一种新型通用的两级测温电路,来实现对不同热电偶信号的调理和动态冷端补偿,并在输入端设计了RFI射频滤波,使得热电偶传感器信号中频率高于1.011 kHz的差模电压和频率高于21.231 kHz的共模电压被滤除,提升了测量精度,设计完成后,对K型热电偶在冷端处于-40℃~60℃且热端在-30℃~1 200℃区间进行多次测试验证,测量误差优于±2℃。In the aerospace field, clarifying the temperature distribution characteristics of the spacecraft shell itself can provide a reference for optimizing the structure and monitoring whether the equipment is operating normally. Thermocouples are classic temperature measurement elements in the aerospace field, and its application is very extensive. In the traditional cold junction compensation circuit design, the cold junction temperature will be fixed to a certain ambient temperature, as a result, when carrying out compensation design in high-precision measurement, error will be introduced. In view of this problem, the AD8227 and AD590 are used to design a new general purpose two-stage temperature measurement circuit to achieve the conditioning and dynamic cold junction compensation of different thermocouple signals, and RFI RF filtering is designed at the input end, so that the differential mode voltage higher than 1.011 kHz in the thermocouple sensor signal and the common mode voltage with a frequency higher than 21.231 kHz are filtered out, which improves the measurement accuracy. After the design is completed, the K-type thermocouple with the cold end in the range of-40 ℃~60 ℃ and the hot end in the range of-30 ℃~1 200 ℃ is tested and verified for many times, and the measurement error is better than ±2 ℃.

关 键 词：AD8227 热电偶 冷端补偿 RFI射频滤波 AD590 

分 类 号：TP212.1[自动化与计算机技术—检测技术与自动化装置]