高精度三线制热电阻检测方法研究
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摘要
介绍了一种恒压分压法精密测量三线制热电阻阻值的方法,使用精密放大器OPA334与24位分辨率Σ-Δ型A/D转换器AD7714Y设计了简洁的输入检测电路。检测过程补偿了导线电阻影响、接触热电势影响及放大器输入漏电流等误差因素。介绍了测量电路自身基准参数的数字校准方法。对于Pt100热电阻,检测分辨率达到0.001Ω,在0~400℃范围内,热电阻测量的绝对误差小于0.01Ω。该测量方法具有精度高、量程宽、成本低及低功耗等特点,能够广泛应用于各类高精度测温仪表。
An accurate method with constant voltage detection for precision measurement of three-wire thermal resistance is presented.In addition,a compact input detection circuit is designed using OPA334 and 24 bit Σ-Δ style A/D 7 714 converter.Lead resistance,contact thermo-electric voltage and leakage current in amplifier input are all ccompensated very well in the whole detection process.Digital calibration method for reference variables in detection circuit is presented.For Pt100 thermal resistance,the detection resolution is up to 0.001 Ω;the absolute error for the thermal resistance measurement is less than 0.01 Ω in the temperature range of 0~400(C.The proposed method features high precision,wide measurement range,low cost and lowpower,which can be widely used in all high precision temperature measurement and control instruments.
An accurate method with constant voltage detection for precision measurement of three-wire thermal resistance is presented.In addition,a compact input detection circuit is designed using OPA334 and 24 bit Σ-Δ style A/D 7 714 converter.Lead resistance,contact thermo-electric voltage and leakage current in amplifier input are all ccompensated very well in the whole detection process.Digital calibration method for reference variables in detection circuit is presented.For Pt100 thermal resistance,the detection resolution is up to 0.001 Ω;the absolute error for the thermal resistance measurement is less than 0.01 Ω in the temperature range of 0~400(C.The proposed method features high precision,wide measurement range,low cost and lowpower,which can be widely used in all high precision temperature measurement and control instruments.
引文
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[2]周华,徐华,朱均.低功耗仪表设计初探[J].仪器仪表学报,2005,26(4):374-377.ZHOUH,XUH,ZHUJ.Study on lowpower instrumentdesign[J].Chinese Journal of Scientific Instrument,2005,26(4):374-377.
[3]徐力,张桂玲.∑-Δ型24位模数转换器AD7714在智能变送器中的应用[J].仪表技术与传感器,2003,(2):35-36.XU L,ZHANG G L.Application of∑-Δ24 bits A/Dconvertion in the smart transmitter[J].Instrument Tech-nique and Sensor,2003,(2):35-36.
[4]田广军,曹英惠.热电偶的幂函数模型[J].传感技术学报,1998,11(3):36-41.TIAN G J,CAO Y H.Power-modle pyroelectric propertyof thermo-couples[J].Journal of Transduction Technolo-gy,1998,11(3):36-41.
[5]王勇,王晓东.高精度铂电阻测温非线性校正方法[J].测控技术,2004,23(7):75-76.WANG Y,YANG X D.Non-linear calibration method ofthe high precision Pt-resistance in measuring temperature[J].Measurement&Control Technology,2004,23(7):75-76.
[6]陈文华,余水宝,张艳艳.高精度宽量程电阻测量方法研究[J].仪器仪表学报,2005,26(8):452-453.CHEN W H,YU SH B,ZHANG Y Y.A study of amethod with high precision and wide-range for resistancemeasurement[J].Chinese Journal of Scientific Instru-ment,2005,26(8):452-453.
[7]林海波.仪表的智能校准技术及方法[J].自动化仪表,2006,27(12):37-39.LIN H B.The intelligent calibration techniques andmethods of instrument[J].Process Automation Instru-mentation,2006,27(12):37-39.
[8]何正淼,宋克柱,汤家骏,等.24位ADC在地震数据采集中的应用[J].数据采集与处理,2005,20(2):244-248.HE ZHM,SONG K ZH,TANG J J,et al.Applicationof 24 bit ADC in a data acquiring system for seismic sur-vey[J].Journal of Data Acquisition&Processing,2005,20(2):244-248.
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