Design For The Intelligent Air Conditioner Control System Based On RS485 Communication Protocols

Along with the developments of the society and the economy, the energy consumption of HVAC (heating, ventilating and air conditioning) system is increasing, which will further intensify the contradiction of the supply and demand of the energy. The sustainable development of the society demands the energy conservation and the intelligent control. Specifically, the HVAC system can automatically keep the working condition of high energy efficiency ratio according to the intelligent control.In this paper, the design of an intelligent control system of HVAC is introduced based on RS485 communication protocols. Using the RS485 communication protocols platform developed by Emerson Technology Corporation for HVAC, the inside subsystem composed of the thermostat subsystem, the indoor unit subsystem and the outdoor unit subsystem, can communicate with each other to follow the dynamic load for energy conservation. Unlike the traditional running mode of the HVAC, the new system has several features such as the following behaviors, the trend predication, and the dynamic regulation and so on. These features can insure both the comfort and the energy conservation. Besides, the system includes many protection functions as following: overvoltage, overcurrent, earthing, short-circuit, overload, instantaneous power-off and principal units self -protection. The optimal working condition can be achieved by monitoring the whole system.The high-resolution TFT liquid crystal screen is used for the man-machine interface of the designed system. The interface is easy to operate and manage. Through the interface, users will get much more information of the system's working condition. Users also can edit the running table by their own life habits and favorites and the system will run according to edited program. The accurate messages of the system faults from the interface are provided for Engineering and maintenance personnel to remove the failures in time. So the interface is helpful to decrease the maintenance time and improve the quality.In addition, a USB interface is provided for the software configuration and update.After full certification tests, the control system can meet all requirements of design functions, and passed the ESD, EFT and EMC reliability standard test, and certified approval as well.