Study On Control System Of Ground Source Central Air-conditioning

Ground source central air-conditioning because of its zero emissions, high thermal efficiency, low prices and other advantages, becomes a strong proponent central air-conditioning in many current countries of the world. On the basis of cooling-heating needs, to reduce energy consumption of central air-conditioning is one of the most popular topics of control system.In this paper, based on a large number of literature search and analysis, Introduces the status quo for the current Ground source central air-conditioning control system, and geothermal-depth analysis of central air-conditioning control system structure and the type of information network and its applications in the real limitations and shortcomings. And establishes a fuzzy PID control model basing on power line carrier technology. The control model breaks the existing system of independent forms and exchanges information through power transmission lines and achieves intelligent control between units and fan.According to the control model, the subject detailed design a set of intelligent ground source central air-conditioning control system, which mainly composed of the unit control system and the end of fan control system. In order to achieve the exchange of information between units control system and fan control system, a network is established in the two subsystems through the power line carrier technology. The units control system in accordance with the collected information of fans, calculates the number of work units as well as the state of the work ,the state of fan, by smart fuzzy algorithm, in order to intelligent achieve variable flow, variable speed control.In order to test the proposed control model performance, this article is designed adjustable parameters MATLAB Simulink-based PID controller in MATLAB Simulink environment, and establishes the control block diagram of the simulation to each part of central air-conditioning. And runs simulation to the design, the result verifies the Fuzzy PID controller is stability and robustness.Based on the above design, this paper gives the main control system software and hardware reference design. Hardware design mainly includes detection circuit to supply-water and backwater temperature, the PWM drive circuit, frequency control circuit of circulating pump, overvoltage protection circuits to compressor, fan air volume control circuit, keyboard and display interface circuit and the interface circuit between power line carrier chip and MCU. Software Design mainly includes the principles and methods to realize the control of machine set, communications on power line, fuzzy calculating, keyboard and display, and developed a protocols for communication on power line, and gives the process flowchart to each procedure.