高精度多参考阻值比率测温系统

High-precision multi-reference ratiometric temperature measurement system

单参考阻值比率测温系统是一种目前常用的高精度测温方法,可以有效削弱恒流源长期漂移、放大器增益漂移、热电势等因素对测量结果所造成的影响,但测量性能会随着测量阻值远离参考电阻阻值而变差。为了解决该问题,本文首先分析了基于恒流源的铂电阻、参考电阻比率测温方法,引入非线性因子,理论分析了测量性能会随着测量阻值远离参考电阻阻值而变差的原因,并由此提出了多参考阻值比率测温方法,进行了硬件系统的设计。对多参考阻值比率测温系统进行了长期稳定性、分辨能力、不同环境温度所造成非线性标定劣化的等效实验,验证了本文理论推导部分的正确性。实验结果表明,在-38.8~64.6℃的温度测量范围内,高精度多参考阻值比率测温系统的测量稳定性优于0.0025℃/5 day,测量分辨能力优于0.00125℃,在5~45℃环境温度下的测量稳定性优于0.004℃。基本满足长期、环境温度变化较大的温度测量应用需求。

The single-reference resistance ratio temperature measurement system is a commonly used method for high-precision temperature measurement,which can effectively weaken the effect of constant current source long-term drift,amplifier gain drift,thermoelectric potential,and other factors on the measurement results.However,the performance worsens when the value of the measured resistance is far away from the reference resistance.To solve this problem,we analyze the platinum resistance and a single-reference resistance ratio temperature measurement method based on a constant current source,introduce a nonlinear factor,and analyze why the measurement performance will deteriorate as the value of the measured resistance moves far away from the reference resistance.Moreover,based on this,a multi-reference resistance ratio temperature measurement method is proposed and the hardware system is designed.The multi-reference resistance ratio temperature measurement system was tested by performing equivalent experiments to determine the long-term stability,resolution ability,and nonlinear calibration degradation caused by different ambient temperatures,which verifies the correctness of the theoretical derivation part of this study.The experimental results showed that,in the temperature measurement range of approximately-38.8~64.6℃,the measurement stability of the high-precision multi-reference resistance ratio temperature measurement system is better than 0.0025℃/5 d,the measurement resolution is better than 0.00125℃,and the measurement stability at an ambient temperature range of 5 to 45℃is better than 0.004℃.It basically meets the long-term temperature measurement application requirements with large environmental temperature changes.