Research For The Speed Control System Of Plate Mill Main Drive

DC motor once occupied a dominant position in the electric drive field for an extended period of time because of its good speed adjusting performance. But the commutator and brush in DC motor restrict its development in the aspect of large capacity of single machine, the ability of high overload, low moment of inertia and maintenance simplification, so DC motor can not meet the production machinery high performance and maximization requirements already. With the rapid development of power electronics, microelectronics technology and modern control theory, the trend that AC drive takes place of DC drive is emerging rapidly in the electric drive field of high power. AC drive is divided into synchronous motor drive and induction motor drive. Synchronous motor drive has higher power factor, smaller capacity of inverter, higher efficiency, and lower moment of inertia compared to induction motor drive, so synchronous motor drive has obvious advantages in the electric drive field of high power.This paper unfolds the work combining with the maintenance project of plate mill main drive in Baosteel Group.4200mm plate mill of Baosteel is domestic advanced reversible mill. The process of rolling plate is reciprocating, excessive overshot will decrease the quality of plate, impact mill life and control accuracy, so the rolling process has high requirement of main drive speed adjusting performance. This paper researches on the speed control system of plate mill main drive, the aim is to make the field engineers have deeper understanding of the speed control system in theory, the research results of this paper have some guiding significance and practical reference value on the process of commissioning and maintenance.First of all, this paper analyzes the decoupling process of AC synchronous motor vector control; deuces mathematical model of AC synchronous motor based on air gap flux-oriented control; studies the structure of AC synchronous motor based on field-oriented control system. On these bases, this paper establishes the mathematical model of speed control system combined with the technical data of4200mm plate mill in Baosteel Group.Secondly, this paper throughly learns the thesis of fuzzy control and genetic algorithm then combines them to form fuzzy genetic algorithm. The aim is to inhibit the early maturity of genetic algorithm.Finally, this paper applies genetic algorithm and fuzzy genetic algorithm to optimize PID parameters of speed control system of plate mill main drive, designs genetic algorithm PID controller and fuzzy genetic algorithm PID controller. The experimental results show that fuzzy genetic algorithm inhibits the early maturity of genetic algorithm well and gets better optimization effect in regard to the speed control system of plate mill main drive.