一种恒流源驱动的高精度温度测量系统设计

为提高温度测量精度,利用REF200提供的0.4mA恒定电流驱动串联的四线制温度传感器PT1000和精密电阻,在传感器和精密电阻两端分别提取电压信号并对其进行调理,通过高精度AD7712对所得到的电压信号进行放大和A/D转换,设计了一种高精度温度测量系统。为了减小高精度温度测量中铂电阻非线性所引起的误差,在上位机中对数字信号进行了最小二乘法算法处理。测试结果表明,该系统稳定可靠,其随机误差和系统误差均小于0.1℃,实现了高精度温度测量。

Design of a high-precision temperature measurement system driven by constant current source

In order to improve the precision of temperature measurement, a high precision temperature measuring system is designed in this paper. REF200 which can provide 0.4mA constant current is applied to drive four wires temperature sensor of PT1000 and precise resistance. The voltage at both sides of PT1000 and precise resistance is extracted respectively and then conditioning the circuit. The voltage is amplified and A/D converted by high precision AD7712. The digital signal is processed by least square method on upper computer to reduce the error which is caused by nonlinear property of PT1000. The test result shows that the system is stable and reliable. And the random error and system error of system is both less than 0.1 ℃. It means that this design realizes the high precise temperature measurement.