The Application Of Permanent Magnet Synchronous Motor Step-motion Control System In Valve Positioning

Valve is the most widely used actuator in the petroleum、chemicals、textiles、metallurgy and other control fields, and the most important accessory of the valve is the valve location device. Early valve control mainly adopts mechanical drive, but this method exist disadvantages such as low-response、 ineffective, What’s more, it needs effectively protect production safety and system reliability. Ordinary electrically operated valve location device adopts specified motor, but their mechanical structure is complex and need high price. Electrically operated valve location device which based on stepping motor, has high accuracy, but the efficiency is low, so it is hard to be applied in the high-power occasions. Electrically operated valve location device which achieved by employing PMSM stepping control method uses the AC drive ideology, has large torque、small inertia、positional accuracy characteristics, so it possess wide development potential.The basic principle of the PMSM stepping control system is on account of the AC stepping drive theory, this theory breaks the range of the continuation and the disperse, combines the increment control and the motion control, makes increment control apply high-capacity、high efficiency situations.This thesis first introduces the general development of several parts of the PMSM control system, then not only the mathematical model and structure of PMSM and AC step motion drive theory are all expounded, but also the basic theory of discrete control of PMSM, that is hysteretic current control method, is analyzed.Then the overall design and implementation of PMSM step-motion control system is presented. In order to obtain high operation speed, good real-time performance and high noise immunity the STC89C58RD+MCU with51core is selected as the core control component of the system. As for the software, C language is selected, and the software developing technology is Keil C.The C programming adopts modularized design idea to make the system having high generality and easy maintenance. In order to satisfy the requirement, relatively complete control circuit and peripheral circuit are also designed. Mainly includes V/F circuit, phase memory circuit.display circuit, voltage isolation circuit, and digital to analog converter etc. This thesis also designs the control program of the system and the flow diagrams are also given. After that the PMSM step-motion control system is applied into valve positioning and the results are analyzed.Finally, some existing problems in theoretical and practical application are pointed out, and the prospect of research work of next step is presented in the thesis.