热电偶时间常数激光测试系统中激光加热研究

Study on laser heating of laser test system for thermocouple time constant

为了在热电偶时间常数测试中提供可靠的阶跃温度信号,优化反馈控制效果,进一步缩短阶跃温升信号的上升延时间,确保热电偶时间常数测量的准确性,采用中温黑体炉对高速辐射测温模块进行了静态温度-电压标定,使用激光器对被校热电偶进行加热,获取单次脉宽调制波(PWM)脉宽时间与温度之间的关系式;理论分析了红外辐射测温模块电压与黑体温度、PWM波脉宽时间与温度之间非线性关系的原因,对进一步优化控制效果、建立系统数学模型提供了实验验证。结果表明,红外辐射测温模块输出电压与黑体温度呈4次方关系;单次PWM波脉宽时间与温度呈3次方关系。该实验结果可为控制器反馈控制调节PWM波脉宽时间(占空比)提供理论依据。

In order to provide the reliable step temperature signal in thermocouple time constant test,optimize the feedback control effect,further shorten the rising delay time of step temperature-rising signal and ensure the accuracy of thermocouple time constant measurement,the static temperature-voltage calibration was carried out for the high-speed radiation temperature measurement module by using medium-temperature blackbody furnace.The relationship between pulse width and temperature of single pulse width modulation(PWM)was obtained by heating the thermocouple with a laser.The nonlinear relationship between the voltage of infrared radiation thermometer module and the blackbody temperature,pulse width of PWM wave and temperature was analyzed theoretically.Experimental verification was provided for the further optimization of control effect and the establishment of system mathematical model.The results show that output voltage of infrared radiation thermometer module is quadratic to blackbody temperature and pulse width of single PWM wave is cubic to temperature.The experimental results can provide a theoretical basis for the controller to adjust PWM pulse width(duty cycle)by feedback control.