一种热导式在线分析仪的温度控制方法

A Temperature Control Method on Thermal Conductivity Online Analyzer

介绍一种热导式在线分析仪,可实现混合气体中氩气含量的测量,由LCD显示测量结果,根据测量结果输出4～20mA电流,并能够根据标准气的不同设定相应的零值和满度值.电路设计包括数据采集电路、恒温控制电路、输出电路、键盘控制电路、稳压电源电路.作者着重介绍了其中的恒温控制电路,采用了一种用脉宽调制(PWM)进行控制的闭环结构.

The introduced product can measure the percentage of Argon(Ar) in the mixed gas. Its result can be displayed on LCD. The current of 4～20mA can be gotten according to the results. Zero values and full values can be set according to the different standard gases. The design of the circuit includes data collection circuit, constant temperature control circuit, 4～20mA current output circuit, keyboard control circuit, power supply circuit,etc. It is emphasized for the constant temperature control circuit, which adopts a kind of closed loop regulated by pulse width modulation(PWM).