A Concentration Detection Method of Infrared Carbon Dioxide Sensor Based on Zero-drift Estimation

Abstract

The invention discloses a method for detecting the concentration of an infrared carbon dioxide sensor based on zero drift estimation, comprising the following steps: S1: collecting the output voltage value U 1 and chamber temperature T 1 ;S2: Initialize the minimum value of carbon dioxide concentration C min , the corresponding voltage value U min and chamber temperature T min ; S3: Get the corrected theoretical voltage value U 0 , to calibrate the model to get the estimated concentration value C 0 and the uncorrected concentration value C 1 ; S4: Judgment C 0 Compared with the numerical value of 400ppm; S5: compare C 1 with C min S6: Judging the value of the number of seconds t and 86400; S7: Reversely obtain the output voltage value U of the calibration model 0 , initialize the minimum value of carbon dioxide concentration C min , the corresponding voltage value U min and chamber temperature T min ; S8: repeat the above step S3 to step S7 until power off. In the present invention, the concentration detection method can estimate the zero drift of the infrared carbon dioxide sensor, thereby correcting the specific value of the estimated carbon dioxide concentration, which can improve the accuracy of the estimated carbon dioxide concentration of the sensor.

Description

technical field [0001] The invention relates to the technical field of carbon dioxide concentration detection, in particular to a concentration detection method of an infrared carbon dioxide sensor based on zero drift estimation. Background technique [0002] Various fields such as industrial production and environmental monitoring need to detect the concentration of CO2 gas. There are many kinds of detection methods for CO2 gas concentration. Among them, non-dispersive infrared (NDIR) detection technology is widely used. This technology uses the strong absorption principle of CO2 gas molecules to a specific infrared spectrum. For the quantitative analysis of CO2 gas, the Lambert-Beer absorption law is I=I 0 exp(-KCL), where I is the output light intensity, I 0 is the input light intensity, C is the concentration, and K is the CO 2 The absorption coefficient of the gas, L is the effective length of the interaction between the gas and the light source. [0003] Since the ...

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Problems solved by technology

[0003] Since the gas absorption characteristics, that is, the value of parameter K is easily affected by temperature, and temperature changes will cause changes in gas concentration, carbon dioxide molecular activity, light source stability, etc., it is directly estimated based on the output voltage of the pyroelectric detector. 2 The gas concentration often causes the accuracy of the measurement results to be low and does not have the value of being put into use. At this time, it is necessary to use an algorithm to correct the temperature compensation of the measurement results so that the equipment can be put into use. According to the output voltage value of the sensor and the temperature value in the cavity With the known actual concentration value, we can establish a calibration model with temperature compensation. Although the calibration has been carried out, as time goes by, the attenuation of the light source and the aging of the photosensitive element will cause the model to drift to a certain extent , if the model with a long time interval is still used at this time, the estimated concentration value will be very different, that is, the actual concentration value corresponding to the same set of voltage values ​​and chamber temperature has changed. In order to put a The carbon dioxide sensor can still maintain a certain accuracy on a long time scale