铂电阻高精度温度测量系统设计

为了满足工业生产对温度测量的高精度要求,研制了一种恒流源微电流驱动四线制铂电阻Pt100的高精度温度测量系统.分析了引起系统测量误差的原因,给出了减少误差的方法;阐述了恒流源、仪用放大、抗混叠滤波、采样保持、A/D采样等主要电路的设计原理和参数选择准则;说明了测量系统的标定方法.该系统采用四线制铂电阻Pt100作为温度传感器,由恒流源微电流驱动产生电压,可以完全去除铂电阻自身的引线电阻、有效减少自热效应;通过仪用放大电路、抗混叠滤波电路和采集保持电路可以有效滤除采集信号中的干扰信号,降低外界干扰对测量系统的影响,增强测量系统稳定性、可靠性和准确性.测试结果表明,该系统性能稳定可靠,标定后测量误差小于±0.03℃.

Design of platinum resistance high-precision temperature measurement system

Aiming at meeting the precision requirement of temperature measurement in industrial process,a high-precision temperature measurement system based on four-wired platinum resistance Pt100,driven by a constant current,was proposed.The measurement errors and the methods to reduce the errors were analyzed; the designed circuits of constant current source,instrumentation amplifier,anti-aliasing filter sampling holder and A/D sampling,and the principle of parameters selection were presented; the calibration method of the measurement system was accounted.As four-wired platinum resistance Pt100 used as the temperature sensor,driven by a constant micro-current to generate measure voltage,the effect of lead resistance was completely eliminated and self-heating was efficiently decreased.After acquisition signal through instrumentation amplifier,anti-aliasing filter and sampling holder,interfering signals were effectively filtered out,interference of the measurement system was reduced,the stability,reliability and accuracy of measurement system were enhanced.The results indicate that,the system is stable and reliable,and the temperature measurement error is less than ±0.03 ℃ after calibration.