温度传感器S型热电偶测温电路设计

Design of temperature measuring circuit of S-type thermocouple based on temperature sensor

针对航天领域环境温度测量宽量程、高精度的需求,提出一种基于温度传感器进行冷端补偿的S型热电偶测量电路,该电路由S型热电偶温度传感器信号调理电路和采样量化电路两部分组成。利用温度传感器AD590的输出电流产生补偿电动势,以补偿S型热电偶冷端温度,实现其测点绝对温度的测量;通过S型热电偶输出电动势与测量温度在分段线性拟合和全量程线性拟合两种算法下的线性度比较,S型热电偶测量时的非线性误差采用分段线性拟合校正算法。对测量电路进行多次试验,结果表明,该设计可实现的温度测量范围为0~1600℃,全温度范围测量准确度±0.2%。电路经工程应用验证,测量结果符合环境变化情况。

Aiming at the wide range and high precision requirements of ambient temperature measurement in aerospace industry,an S-type thermocouple measurement circuit using temperature sensor for cold junction compensation is proposed,which includes an S-type thermocouple temperature sensor signal conditioning circuit and a sampling quantization circuit.In order to compensate the temperature of the S-type thermocouple cold junction,the output current of the temperature sensor AD590 was used to generate a compensation electromotive force,which achieved the measurement of the absolute temperature about its measuring point;through comparing the linearity of the S-type thermocouple output electromotive force and the measured temperature under piecewise linear fit and full-scale linear fit algorithm,the nonlinear error of S-type thermocouple measurement adopted a piecewise linear fitting correction algorithm.After performing multiple tests on the measurement circuit,the results show that the design could achieve a temperature measurement range from 0℃to 1600℃and the measurement accuracy of the full temperature range is±0.2%.The circuit has been verified by engineering application and the measurement results are in line with environmental changes.