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对热电偶的冷端温度补偿方法进行了研究。为直观说明传统补偿电桥法存在的不足,文中选取了两种有代表性的热电偶,对其冷端补偿误差逐点计算,给出了补偿误差表;作为对比,推荐了一种双桥结构的冷端补偿方案。改进的冷端补偿器由主、副两个补偿电桥串联组成,主电桥按传统方法设计,副电桥设计在主电桥的完全补偿点平衡,通过调节副电桥限流电阻改变副电桥的输出,使改进后的补偿器在冷端温度变化范围的输入输出特性与所配热电偶的特性曲线尽量接近。分析计算表明,这种结构的补偿器补偿误差明显减少,使测温准确度显著提高。
The thermocouple cold junction temperature compensation method was studied. In order to intuitively illustrate the shortcomings of the traditional compensation bridge method, two representative thermocouples were selected in this paper, and the compensation error table was given on the basis of their cold junction compensation error. As a comparison, a double bridge Structure of the cold junction compensation program. The improved cold junction compensator is composed of main and auxiliary compensation bridge in series. The main bridge is designed according to the traditional method. The secondary bridge design is balanced at the complete compensation point of the main bridge. By adjusting the current limiting resistance of the secondary bridge, Bridge output, so that the improved compensator in the cold junction temperature range of the input and output characteristics with the thermocouple characteristic curve as close as possible. The analysis and calculation show that the compensator compensation error of this structure is obviously reduced, and the accuracy of temperature measurement is significantly improved.