Design And Application Of Power Regulation System Based On Profibus-DP Bus

Electric power regulator is the core of various kinds of electric heating equipmentcontrol system. It effects on the independence of the temperature control system. It plays animportant role in the credibility of the temperature control system. But now traditionalelectric power regulator which are widely used in many factories in China can’t carry outfield bus communication. Low precision and complicated connection are also traditionalelectric power regulator’s innate defects. Traditional electric power regulator’s capabilitycan’t meet modern industry production needs. With the development of field bustechnology and intelligent control technology, the electric power regulator is developedvery fast. Field bus and intellectualization are general trend of the electric power regulatordevelopment. Because of that, the development of the intelligent electric power regulatorbased on the PROFIBUS-DP field bus technology is valuable.This paper first presents the overall design scheme on the basis of study and analysisfor the working methods, circuit structure and requirement of power regulation system.Based on this, this system’s hardware and software are reasonably designed.In this system,PLC is the master station and each thyristor regulator is the slave station. The mastercontroller of each slave station is single chip computer. Each slave station has DP buscommunication interface.In the hardware part, the STC12C5A60S2microcontroller as the main control unitachieves data processing, data storage and display, and other functions. In addition, it isalso designed a few peripheral circuit. It especially focus on the study and design of thePROFIBUS-DP communication interface circuit by using SPC3as the interface chip.In the software part, it describes the design of algorithm of the duty ratio and soft startfunction, and it also designs the program of DP communication on the basis of study andanalysis for the master station PLC’s communication settings.Finally, the electric power regulator system’s functions were tested in the laboratoryroom and factory. The result of experiment indicated that the electric power regulator couldaccurately control the load current and communicated well with the master station PLC. Ina word, this system’s functions realized the requirement of the original design.