Research On Temperature And Humidity Control System Of Pharmaceutical Factory Variable Air Volume Air-condition

Medicines are the product that related to human health and life, which has an extremely strict technical requirements and production conditions. The quality of drugs does not only have a close relationship with formulations, but also the production environment has become a crucial factor. The quality of production environment air is ensured by the system of air condition. To control the temperature and humidity at a constant value as stated is the main target for air purification system.In this thesis, give a brief introduction of the basic knowledge of pharmaceutical cleanroom and basic principles about VAV system based on the background of a pharmaceutical temperature and humidity controlled air purification system at first. Secondly, through the mechanism modeling method, using some approximations and assumptions, by study of variable air volume air conditioning system temperature and humidity control to determine the amount of steam flow control valve and the cold water valve as temperature and humidity control system’s control variables and the cleanroom’s temperature and humidity as controlled variables and get a two inputs and two outputs multivariable mathematical model control systems. Then, according to the mathematical model of the temperature and humidity object’s coupling characteristic, design a method called feed-forward which is easy to implement in engineering to decouple the link between temperature and humidity. On this basis, considered the original system for temperature and humidity controlled object’s complex mathematical models, it is difficult to establish a precise mathematical model, and the parameters identification become difficult, coupled with the limitations of traditional PID used to multivariable control system, this thesis is based on decoupling fuzzy PID controller for VAV systems to improve temperature and humidity control performance. Through using features of fuzzy control’s flexible and strongly adaptive, coupled with traditional PID’s high accuracy performance to get optimal PID control parameters to improve system robustness performance and to increase the controllability of temperature and humidity control system and to ensure air quality of pharmaceutical companies.Finally, the simulation results based on fuzzy PID of temperature and humidity control system through Simulink under the circumstance of set-point tracking, anti-interference and objects mismatch compared with traditional PID control system and decoupling control system show that the decoupling fuzzy PID control system designed in this thesis greatly reduce the overshoot, coupled with better track performance, anti-interference and good robustness when the object model parameters of control system mismatch.