Screw-type Air Compressor Control System

Since air compressor has many advantages in supplying pneumatic power and now nationprovides policy support for air compressor industry, the use of air compressor equipment isgradually increasing in recent years. In air compressor industry, screw-type air compressor occupiesa significant market share owing to its high reliability. However, it is noted the use of aircompressor equipment has certain risk and relevant safety accidents has been reported at home andabroad, for example, phase error, current overload, phase lack， supplies over time and so on.Therefore, it is necessary to design a reliable screw-type air compressor control system.Firstly, this essay lists several safety accidents of using air compressor and analyses thecorresponding reasons, and also makes a comprehensive comparison of domestic and foreignresearch status for air compressor’s control system. Then, it proposes RS-485bus basedcommunication network after the analysis of air compressor’s working conditions, which integratesmore than one air compressor into a whole and controls them in one system. In this way, theefficiency and safety can be enhanced greatly. As to the basic requirement of bus communication,various measures are put forward to improve the success rate and reliability of bus. Based on theanalysis of Modbus treaty and working pattern, it seems reasonable data package and CRC datachecking can speed data transmission, improve data integrity and data transportation efficiency.Secondly, it presents the overall circuit design with PIC24HJ128GP506as the core. Theoverall circuit design is consistent with the functional requirement of screw-type air compressor andis based on many relevant literature and cases. In the software, it was programmed in State modewhich makes the maintenance easy and structure clearly. Also, inverse time protection was add toprotect the machine and linear regression was add to correct the data. Besides, in order to realize theoverseas sale of equipment, the system menu is designed with bilingual model (Chinese andEnglish), which is quite helpful in satisfying the user’s requirements in Europe and America.Thirdly, it introduces MFC based graphical user interface. This GUI is designed with industrialcomputer as hardware platform and it is the result of combing Windows and Visual Studio2008.Host software is designed not only to meet the functional requirements, but also to take fullconsideration of the user experience, friendly interface and data transmission efficiency.Finally, this essay summarizes the general situation of the screw-type air compressor, the resultshows that the system meet the demand well. Also the essay analyzes the features and shortcomings of its current design, and puts forward its future development trend combined latest science andtechnology.