Rerkratn Apinai, Prombut Supatsorn, Kamsri Thawatchai, Riewruja Vanchai, Petchmaneelumka Wandee
School of Engineering, King Mongkut's Institute of Technology Ladkrabang, Bangkok 10520, Thailand.
Thai Microeletronics Center (TMEC), Chachoengsao 24000, Thailand.
Sensors (Basel). 2022 May 31;22(11):4176. doi: 10.3390/s22114176.
A procedure for the precise determination and compensation of the lead-wire resistance of a resistance transducer is presented. The proposed technique is suitable for a two-wire resistance transducer, especially the resistance temperature detector (RTD). The proposed procedure provides a technique to compensate for the lead-wire resistance using a three-level pulse signal to excite the RTD via the long lead wire. In addition, the variation in the lead-wire resistance disturbed by the change in the ambient temperature can also be compensated by using the proposed technique. The determination of the lead-wire resistance from the proposed procedure requires a simple computation method performed by a digital signal processing unit. Therefore, the calculation of the RTD resistance and the lead-wire resistance can be achieved without the requirement of a high-speed digital signal processing unit. The proposed procedure is implemented on two platforms to confirm its effectiveness: the LabVIEW computer program and the microcontroller board. Experimental results show that the RTD resistance was accurately acquired, where the measured temperature varied from 0 °C to 300 °C and the lead-wire resistance varied from 0.2 Ω to 20 Ω, corresponding to the length of the 26 American wire gauge (AWG) lead wire from 1.5 m to 150 m. The average power dissipation to the RTD was very low and the self-heating of the RTD was minimized. The measurement error of the RTD resistance observed for pt100 was within ±0.98 Ω or ±0.27 °C when the lead wire of 30 m was placed in an environment with the ambient temperature varying from 30 °C to 70 °C. It is evident that the proposed procedure provided a performance that agreed with the theoretical expectation.
本文提出了一种精确测定和补偿电阻式传感器引线电阻的方法。所提出的技术适用于两线制电阻式传感器，尤其是电阻温度探测器（RTD）。该方法提供了一种利用三电平脉冲信号通过长引线激励RTD来补偿引线电阻的技术。此外，利用该方法还可以补偿因环境温度变化而受到干扰的引线电阻变化。根据所提出的方法确定引线电阻需要由数字信号处理单元执行的简单计算方法。因此，无需高速数字信号处理单元即可实现RTD电阻和引线电阻的计算。所提出的方法在两个平台上实现以确认其有效性：LabVIEW计算机程序和微控制器板。实验结果表明，在测量温度从0°C到300°C且引线电阻从0.2Ω到20Ω变化的情况下，能够准确获取RTD电阻，这对应于26号美国线规（AWG）引线长度从1.5 m到150 m的情况。RTD的平均功耗非常低，并且RTD的自热被最小化。当30 m长的引线置于环境温度从30°C到70°C变化的环境中时，对于pt100观察到的RTD电阻测量误差在±0.98Ω或±0.27°C以内。显然，所提出的方法提供了与理论预期相符的性能。
