Design Of Constant Temperature And Humidity Generating System Under The Low Temperature

In order to obtain the temperature and humidity measurement and verification environment under the low temperature conditions,this paper has taken the dual-flow method as the principle of humidity generation under the low temperature and used fuzzy PID algorithm to complete the temperature and humidity control.On this basis,a constant temperature and humidity generating system under the low temperature has been designed.This paper has designed the overall scheme of the constant temperature and humidity generating system in the low temperature section.The system has mainly included dry air generation system,thermostat test box,dew-point hygrometer,gas flowmeter,hygrothermograph.On this basis,minimum system control board,power supply module,serial communication module,electric valve control module,temperature control module and other hardware circuits have been designed with the core of STM32F103RCT6 chip.According to the experimental data,this paper has uesd the step response method to establish relative humidity control model of the system.After studying the conventional PID algorithm and fuzzy algorithm,a fuzzy PID control algorithm for the constant temperature and.humidity generating system under the low temperature has been proposed.Compared with the traditional PID controller,the fuzzy PID controller has had less overshoot,short adjustment time and better control effect.in the constant temperature and humidity generating system by Simulink.By porting the embedded RTOS μC/OS-II on the STM32 side,the master program,serial communication task,temperature stabilization task,fuzzy PID temperature and humidity control task and so on have been designed.The upper computer software has been designed by C#language,which has realized serial communication,target temperature and humidity settings,data storage,temperature and humidity data display,humidity control curve,the drying-wetting gas flow curve real-time display and other functions.Finally,through system operation experiments,it has been verified that the system meet the design requirements.