基于FPGA的高精度S型热电偶温度测量系统设计

Design of temperature measuring circuit of S-type thermocouple based on temperature sensor

针对传统的多通道S型热电偶测温系统测量精度低、各通道精度相差较大的问题,提出了一种以FPGA为核心的高精度S型热电偶测温系统。系统以FPGA为核心控制器,采用模块化设计,利用AD590温度传感器对S型热电偶进行冷端补偿。采用多通道采集、单通道调理的设计方法以改善由于元器件差异引起的各通道精度相差较大的情况。同时选用高精度ADC将采集的温度模拟信号转换为数字信号传输到上位机显示,上位机通过查表法准确定位温度值,提高测温精度。经过多次试验验证,该测温系统温度采集精度优于0.2%F.S.。目前该系统已经应用到工程实践中,为多通道S型热电偶测温系统设计提供了有效、可靠的手段。

Aiming at the problem that the traditional multi-channel S-type thermocouple temperature measurement system has low measurement accuracy and each channel is quite different,a high-precision S-type thermocouple temperature measurement system based on FPGA is proposed.The system uses FPGA as controller,with modular design,and uses AD590 to perform cold junction compensation for S-type thermocouples.A high-precision ADC is used to convert the collected temperature analog signal into a digital signal and transmit it to the upper computer for display and locates the temperature value through the look-up table method to improve the temperature measurement accuracy.After many tests,it is verified that the temperature acquisition accuracy of this temperature measurement circuit is better than 0.2%F.S.At present,the circuit design has been applied to engineering practice,which provides an effective and reliable means for the design of temperature measuring circuit of S-type thermocouple.