Development Of Embedded Intelligent Controller For Refrigerating Machine

While people enjoy better living conditions, energy consumption is rising annually. The energy consumption of air-condition refrigeration industry which is closely related to people counts for a big proportion. The core of refrigerating system of central air-condition is refrigerator, which occupies 40 percents of total electricity consumption of central air-condition. Thus, the development of a new type energy saving refrigerator has a better market value.In this thesis, an intelligent control algorithm of refrigerator overheat, which is the combination of PID control and fuzzy control method, is proposed based on analysis of working principle of refrigeration system. It regards large-scale water-cooled refrigeration machines as the research objective and central air-conditioning (HVAC) system experimental platform of SUT as the actual test objective. That is to say, the refrigerating machine superheat is controlled efficiently and steadily by PID controller, in which the parameters are determined by fuzzy strategy according to the different load. An embedded controller is developed based on this control strategy and an embedded system development platform containing Samsung's S3C2410 central processing unit based on ARM920T core.Based on embedded LINUX and QT/embedded development platform, this thesis establishes cross compiler environment of refrigeration machines embedded controller software development, analyses in detail the cutting and compiling of Linux kernel, establishes the root file system and compiling routine, and completes programming of the overall flow of refrigeration machines controller. On the basis of it, subprogram of control algorithm, temperature sampling filter and stepper motor drive and the design of graphical user interface (GUI) are fulfilled. Through realizing embedded software development and control strategy, the intelligent controller of refrigeration machine has many characteristics, such as optimizing control of overheat, touch setting of the overheat, real time display of the overheat, alarming and monitoring the state of electronic expansion valve. In order to validate the practical application validity of the controller, the central air-conditioning (HVAC) system of SUT is used as the experimental objective. The experiment results shows that intelligent PID control strategy responses process smoothly compared with the PID of tradition, and the biggest fluctuation of superheat is less than 4℃, and the controller realizes the energy-saving of the system.