介绍一种基于数字PID控制算法的热电偶时间常数测试系统,提出了以PDI-4型红外探测器输出作为反馈信号控制半导体激光器功率输出以实现在热电偶测温端处形成阶跃温升的测试方法.该系统由半导体激光器,反馈控制模块,椭球面反射镜,红外探测模块,热电偶及信号采集显示模块构成.在温度20℃,湿度59％,标准大气压的环境下,以上升时间,超调量作为控制器性能参数测试KQXL-18U-6型热电偶,测得其在上升时间0.8 s,超调量2％,阶跃温升1020℃的温度信号激励下的时间常数为0.34 s.%A system for time constant testing of thermocouple based on digital PID control algorithm was introduced .The idea of using the output signal of PDI-4 infrared detector to be the feedback signal to control the output power of semiconductor laser to generate step change of temperature on the surface of Thermocouple was proposed .The system is made up of semiconductor la-ser, feedback control module, ellipsoidal reflecting mirror, infrared detector, thermocouple and data acquisition and display module.Under the condition of temperature at 20 ℃,humidity at 59％and normal atmospheric pressure , the KQXL-18U-6 thermocouple was tested with rise time and overshoot as the performance parameters of the PID controller .The result shows that with the incentive of 1020 ℃step temperature of rise time 0.8 s,overshoot 2％,the time constant of KQXL-18U-6 thermocouple is 0.34 s.
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