Research On The Speed Control System Of Roughing Mill Main Drive

This paper conducts the research on iron and steel plate reversible rolling mill4200mm main drive of Baosteel. Iron and steel plate reversible rolling mill4200mm main drive of Baosteel is one of the most advanced iron and steel plate reversible mill to date nationwide, whose main motor is powerful AC synchronous low-speed motor. The control system utilizes two Siemens cocloconverter systems to control the upper and lower motors respectively. In modern times, Siemens applies vector control rationale to the control system of powerful AC synchronous low-speed motors; therefore AC motors keeps the advantages that DC motors do not have, such as large unit capability, small moment of inertia, simple and firm structure and little maintenance time. At the same time, the control performance and accuracy of the drive system improve dramatically, as good as DC driver system, if not outperform.As the process of reversing mill plate rolling are reciprocated, overshot over the general assembly would result in the decrease of the quality of the steel plate and have an impact on mill life and control accuracy. Therefore, the rolling mill requires the high speed performance. This study is to explore better control effect than the production site.First of all, the conception of AC motors field oriented vector control is introduced. From the perspective of AC motors theory, imitating torque control rationale of DC motors, AC motors are considered as DC motors by coordinate transformation control and then AC motors field oriented vector control theory is concluded.Secondly, on the basis of6-pulse cocloconverter system every procedure and their functions of the system are understood. The study extends to12-pulse cocloconverter system. What’s more, from cocloconverter adjustable speed analog control system to cocloconverter adjustable speed digital control system, the similarities and differences between analog system and digital system are also deeply understood.Furthermore, with the help of ibaAnalyzer software the variable curves and relevant data of important variables of the system are collected from the iron and steel plate reversible rolling mill4200mm main drive of Baosteel production site and analyses and studies these variable curves. Simulink Simulation is conducted in the mathematics model of synchronous motors and its whole system and based on the production site curve simulated veracity is verified combined with theoretical knowledge.Finally, MRAC built on Lyapunov theorem of stability is studied and researched to understand the originality, development and achievements of adaptive control. MRAC simulation research on cocloconverter adjustable speed system of synchronous motors is conducted. By comparing to traditional PID control, the merits and demerits are further understood.