Design Of Low Humidity Dew Point Meter Based On STM32

Dew point temperature is an important parameter to characterize air humidity,the physical quantity that reflects the degree of dryness and humidity of the air,which impacts on us everywhere,so the high-precision detection of dew point is particularly important.Based on the principle of the chilled mirror dew point meter,this paper studies the temperature control method and designs a low humidity dew point meter based on STM32.The working principle and process of the dew point meter designed in this paper is to set a light intensity first,and to reduce the temperature at full speed.When light intensity reaches the set value,the rough dew point is obtained.Controlling the temperature until the surface of mirror is in the critical state of condensation and non-condensation,the temperature value measured by the temperature sensor inside the mirror is the dew point temperature of the gas.This paper introduces the structural and hardware design of the system,including laser module,refrigeration module,temperature measurement module,light measurement module,display module and other hardware electric circuit otherwise air chamber,optical path structure,heat sink and other structures,and program software for each module of the system.In this paper,the temperature control method of dew point meter is also studied,and several control methods are proposed.The control method of each method is compared and the light temperature control method based on BP neural network PID is selected.It is characterized by two PID controllers.The light intensity and temperature are controlled separately,and the light intensity controller adds temperature adjustment parameters to improve the sensitivity.The temperature controller adds the BP neural network algorithm,and adjusts the parameters of the controller through the self-learning and weighting coefficient adjustment of the neural network algorithm.Self-tuning,realizing rapid response to temperature control,matching with the light intensity controller,finally making the dew point meter have high precision,good stability and fast response.The experimental results show that the repetition of the dew point instrument designed in this paper is ±0.06℃,the accuracy is ±0.3℃ and the measuring range is-50℃~+25℃,which meets the requirements of low humidity dew point detection and can be used for measurement in industrial fields.