基于虚拟仪器和USB技术的热电偶测温系统设计

Design of Thermocouple Temperature Measurement System Based on Virtual Instruments and USB Technology

针对传统热电偶测温中的若干问题,设计了基于虚拟仪器和USB技术的测温系统;热电偶和AD590测量热端和冷端温度,USB采集卡实现信号的转换和传输;上位机软件利用LabVIEW编制,实现数字滤波、非线性和冷端补偿、生成统计直方图等功能;在0～200℃范围进行了实验,系统非线性误差为0.8%,对于同一温度点,顺测和回测的最大误差为0.6℃;这表明系统能够实现高精度实时补偿、重复性较好、结构简单、界面良好,可以满足工业测试的需要。

In view of some problems of the traditional temperature measurement for thermocouple, the virtual measurement system was designed based on Virtual Instruments and USB technology. The signal of the hot-junction and the cold junction temperature was gained by thermocouple and AD590, using USB data acquisition card for signal conversion and transmission. Host Computer software was programmed on LabVIEW, achieving functions such as digital filtering, nonlinear compensation, cold-junction compensation, generating temperature histogram. Experimentally in the range of 0-200℃, nonlinear error is 0. 8%, for the same points, the maximum error of order and return measurement is 0.6℃ o This shows that the system can achieve high precision real time compensation, reproducible, simple structure, good interface to meet the needs of industrial testing.