The Study Of Dynamic Characteristics Of Resistance Temperature Detector

Thermal resistance is widely used in industrial production and daily life due to its high precision and good stability.However,due to the thermal resistance itself,there is a dynamic error when using it to measure dynamic temperatures.Therefore,it is very important to understand the dynamic characteristics of the RTD temperature sensor and to correct its dynamic error by using the time constant.The subject uses LabVIEW's cRIO controller's FPGA mode to perform temperature acquisition on platinum resistance under different temperature conditions.The temperature acquisition under step change and linear temperature change is the key of this research.The main research contents are as follows:(1)We have learned and studied different measurement methods of thermal resistance dynamic characteristics,especially the change of time constant under different step temperatures;understanding the existence principle of thermal error of thermal resistance,through the relevant formula,The calculation method of the time constant.(2)According to the selected thermal resistance,the relevant test system is designed based on LabVIEW software;the system adopts the FPGA mode of the cRIO controller,and uses the fixed-point characteristics of the FPGA mode to obtain extremely high data acquisition accuracy and ensure the accuracy of the thermal resistance temperature signal.Through the research of ARX regression model,the ARX dynamic error correction program is compiled to correct the dynamic error of the thermal resistance.(3)The functional modules of the system were simulated and debugged,and the thermal resistance dynamic test tests of different step temperatures were carried out in silicone oil,water and air using double-slot method,and data analysis was carried out,and the uncertainty was evaluated.Finally,a new dynamic correction method,SVM correction method,is proposed.Compared with ARX correction method and BP neural network correction method,it shows that the method has the advantages of no need to calculate time constant and good correction performance.