Research On The Speed Control System Of Mill Main Drive And Gennetic Algorithm PID Control

With the development of technology electronic power-electronics and computer control, the use of AC motors makes the total cost less than before, although the expense of the AC speed-regulating transducer is a little high. Especially, the vector control is applied to the speed-regulating field, which makes the performance of AC adjustable speed system is as good as DC system. So, the trend that the AC drive takes place of DC drive is emerging rapidly in the drive field of regulating speed.The cocloconverter-fed field-oriented vector control is playing a very important role in the field that is strict with regulating speed demand, such as the heavy steel plate mill,its good control system not only assures high capicity technology index and the production quality, but also cuts down the whole cost.This paper takes iron and steel plate reversible mill4200mm main drive of Baosteel. As the process of reversing mill plate rolling process of rolling back and forth, overshot over the general assembly would increase the quality of the steel plate, impact mill life and control accuracy, the rolling mill requirets the high speed performance. This study is to seek better control effect than the production site.First of all, based on the introduction of the vector control elementary priciple, this paper expands on the composition of the field-oriented vector control system of mill4200mm main drive, and abstracts the mathematical models according to the physical relationships between correlative variables.Secondly, in order to analyze the dynamic characteristic of the speed control system, after referring to a lot of relevant information, this paper proposes an analysis method of torque and flux to the decoupling of two variables with two single-variable linear systems to control, the speed and the flux linkage control are discoupled into two independent, sigle-variable and linear system, and than it builds the double closed loops of the adjustable speed system with the current inner closed loop. Finally, this paper makes simulation research on the speed control system respectively based on the conventional PID control algorithm and the binary-coding GA PID control algorithm using MATLAB. From the compare of the simulation curves, this article draws conclusions that the GA PID parameters turning method has higher dynamic performance indexes and does not depend on the object’s precise mathematical model and has stronger robustness than the conventional PID method, which makes the speed control system has better control effect, the study of this paper has some practical significance.