Design And Research Of Automatic Control System Of Air Conditioning Refrigeration Unit

Now the air conditioning is everywhere, it has penetrated into all aspects of our lives, for the control of the special environmental requirements even need to keep a constant temperature. In this paper, a unit of Tianjin central air-conditioning automatic control system for the background, for the single screw refrigeration system design of a higher degree of automation control system. The research mainly includes the overall design scheme of central air-conditioning control system, fuzzy PID control algorithm is applied to the design of hardware and software and monitoring system.With the advancement of modern science and technology development and social,people have more and more demands for the control of central air conditioning.Control of central air conditioning efficiency and energy consumption are we have been pursuing, although the traditional PID control has a good stability, but has become increasingly difficult to achieve the desired expectations. So we are on the traditional PID control method further improvement, we let the traditional PID control and fuzzy control algorithm integration, forming a fuzzy PID control algorithm, the simulation in the MATLAB environment, from the analysis on forming results can overcome large delay in the system, and can achieve good energy saving effect from the actual operation.Air-conditioning refrigeration unit into the intake, compression, exhaust three working process.The air conditioning system is mainly composed of a refrigerating compressor system, cooling water circulation system, cooling water circulation system, fan coil system and cooling tower work constitute the working process of refrigeration system.Through the analysis of the working principle of the air conditioning and refrigeration system, it summed up the characteristics and needs of actual need to implement the function of the control system which determines the control scheme of the system, control system flow chart shown, to achieve the appropriate level of control and monitoring software level control system hardware design.The control system of the SIEMENS S7-200 PLC as control core, using the SIEMENS KTP178 touch screen as the monitoring system, realizing the function of human-computer interaction.This paper describes the selection of hardware automation equipment, including the allocation of I / O points, power supply module, CPU selection, analog and digital modules.The software part completed the design of the communication between devices, part of the program and the monitor screen.This paper focuses on how the central air-conditioning control system using fuzzy PID control algorithm to make a detailed description, a thorough analysis of the formation process of fuzzy PID, and lists the fuzzy PID controller design process by controlling the temperature of the room to make the MATLAB simulation, while the traditional PID and fuzzy PID control to compare.Design of touch screen monitor screen so that the operator can operate simple and effective operation.The actual operation results show that the control effect of the fuzzy PID controller is much better than the traditional PID control effect.