Based On PIC16F877 Development Of Soft Start Contorller

AC motor plays an important role in the national product.The motor current can be 4-7 times without any device if we use the rated voltage direct starts.This will influence the motor, the voltage and other equipments.With the concept of soft start coming intobeing, we can see several ways control start: the current limit, voltage slope sart. AC motor control device of soft start is replacing the traditional starting way with the development of electronic technology.This thesis puts forward an ideal design on the flameproof and safe AC motor sort start . The author forms the thesis based on the background of cooperation with Jiyuan kolding Electric Co.Ltd. In this program, we developed the"QJR-400 mine–flameproof and safe AC motor soft start device". This technology has passed the examination by National Examination center. The key point of thesis is to design the core control device in AC motor sort start device, it is sort start controller.In chapterⅠ,the thesis describes the status and developing trend of the sort start motor technology, it puts forward the basic function of sort start controller and some problems solved in design process.In chapterⅡ, the thesis analys the starting process of AC induction motor, at the same time, it analyses protection principle on the operation of the motor shorled circuit a commom fanlt of the set. It also provides a the oretical basis for the design of sorf start controller by using double-loop PID with a double-speed controlling the soft start motor process.In chapterⅢ,it analyses the hardware design ideas of soft start controller,introducing the whole design of hardware and module design.it also introduces the design about the hardware of MUC control system,A/D converter module, the data storage,the LED module, communication interface design, three-phase synchronous signal acquisition and accompanying triggered thyristor circuit design, signal acquisition and current-current protection, the hardware protection circuit design and input-output interface circuit design, and gives the corresponding circuit design.In chapterⅣ,it analyses the software design ideas of soft start controller. It gives the methods of exchanges sampling. Accofding to the current signal sampling and algo rith analysis. The thesis puts forwards the whole design of soft ang makes sure the software structure diagram.It gives the relative design idea ang software block siagram on the initialization, A/D conversion, key settings, voltage synchronous signal detection.Liquid crystal display, fault handling, anti-jamming measures.In chapterⅤ, the thesis gets conclusion of the relative data and the method of examination on the protection performance and the performance of starting.The soft start device's performance is very stable,which core is soft start controller. Its action is reliable the process of starting is stable and smoth,lower price,display clearly, installation is convenient, maion tenance is very simple . it's better than traditional start in practicability and reliability.