Research On Fault Self-diagnosis System For Environmental Control Of Fruits And Vegetables Controlled Atmosphere Preservation

At present,the controlled atmosphere preservation technology on fresh fruits is the most promising one in China.It can inhibit the respiration of fruits and vegetables and extend the preservation time of fruits and vegetables to a large extent;in recent years,colleges and universities and scientific research institutions at home and abroad have been carrying out in-depth researches and discussions on the controlled atmosphere preservation technology.And many controlled atmosphere preservation equipment for practical production are designed,and the equipment is an integration of Refrigeration system,ventilation system,nitrogen enrichment system and humidification system,etc.,which can comprehensively control and adjust the temperature,the humidity and content of the carbon dioxide,nitrogen,oxygen of the humidity and other environmental factors of the preservation box.In this paper,the hardware and software of fault self-diagnosis system based on stm 32 intelligent controlled atmosphere preservation box are researched,and the hardware and software of fault self-diagnosis system are further designed.The main research is as follows:(1)Researches and discussions on various control principles and failures of the systems of the platform are carried out based on the platform of the original controlled atmosphere preservation box.The influence of the systems on the controlled atmosphere preservation box is analyzed.(2)The expert system knowledge base for the actuator device current parameters is determined by means of the processing and analysis on the collection and data of actuator current factors.Various actuators that accomplish environmental factor adjustment in the controlled atmosphere preservation box are researched,including the relationship between the fault current and phenomena of the Electric ball valve,liquid nitrogen tank discharge solenoid valve,booster solenoid valve,condenser fan,ultrasonic atomization head,DC fan and other actuators,and acquisition experiments of solenoid valve,fan,electric ball valve,humidifier oscillator current factor are carried out and actuator current characteristics in various working conditions are analyzed to determine the current threshold for each operating condition,providing basis for the design of fault self-diagnosis control strategies.(3)Hardware design for the fault self-diagnosis system of controlled atmosphere preservation box is based on stm 32 control system.The design of the fault self-diagnosis hardware system is based on the stm32 atmosphere preservation control system;two-pole power supply scheme is the main design in order to avoid the over charing and impairment of fault current on the control system if the working current of acquisition actuators go wrong.Current conversion,filtering,isolation and other processing are conducted during current acquisition.(4)Based on the current acquisition experiment and fault analysis.The design of each actuator fault self diagnosis system.The control strategy and software implementation of the subroutine The integrated control strategy of fault self diagnosis system is designed,and the comprehensive fault self diagnosis verification test is carried out...