Design Of NDI Low Power Self Powered Carbon Dioxide Sensor

At present,a lot of research has been done on non spectroscopic infrared(NDIR)gas detection at home and abroad,such as pyroelectric,thermopile and other sensors,but the conventional pyroelectric and thermopile detectors are not applicable in some scenarios.For example,when used in individual combat and outdoor sports,the conventional infrared gas sensor will increase the volume of the whole sensor due to its high power consumption,and the battery needs to be replaced frequently,resulting in inconvenience.Therefore,this paper designs a NDIR low-power self powered gas sensor.After a special low-power design,the sensor has developed a self powered system,which solves the problems of high power consumption and inconvenient carrying of conventional sensors.At the same time,the sensor has been tested in different temperature environments.The main research contents include the following aspects:1.The gas chamber with small volume and optical path can meet the requirements is designed.Its feasibility is verified by Trace Pro simulation,and the processing of gold-plated gas chamber is completed.In terms of hardware circuit,STM32 is selected as the core to design the light source driving circuit,signal conditioning circuit,power supply circuit and temperature and humidity acquisition circuit.The modulated light source is controlled by the single chip microcomputer.After passing through the signal conditioning circuit,the signal enters the single chip microcomputer for data acquisition,and completes the processing and welding of PCB.The flow of the whole software system is also introduced,and the important programs such as light source driver,A / D acquisition,internal clock configuration of the system are designed.2.The self power supply system supporting the whole sensor system is designed.Through the classical law of electromagnetic induction,the magnetic induction coil is cut by the magnet rod to generate electricity.The characteristics of various rectifier circuits are analyzed.The diode rectifier bridge is selected as the rectifier circuit,and then through the boost boost circuit to achieve stable DC power to supply power to the sensor system.3.The power consumption test platform is built,including the calibration of the gas sensor and the stability test of the system.In terms of data processing and analysis,through origin fitting analysis,the maximum fitting error is 0.16%,and the average power consumption of the sensor is 25.91 mw.At the same time,the calibration test within the temperature of 0-30 ℃ is completed,and the results are temperature compensated.The retest results show that when 5% standard gas is introduced,the maximum error is 2018 ppm.