Study On Bifurcation Control And Vibration Performance Of Rolling Mill’s Main Drive Electromechanical Coupling System Driven By DC Motor

The main drive system as a core part of rolling mill plays an irreplaceable role in the process of production. The frequent phenomena of torsional vibration in main drive system will seriously affected the product quality and production, sometimes even has a damage of rolling equipment and shut down the production line, Therefore, a study on instability mechanism of main drive system and the control strategy is of great practical significance. Rolling mill main drive system is composed of electric drive control system and mechanical drive system, the stability of the system is determined jointly by this two parts. Considering the unsaturated magnetic circuit and the coupling effect of electrical parameters and mechanical parameters, the nonlinear torsional vibration model of the main drive system is established in this paper. This paper study the nonlinear characteristic of rolling mill form establish, analysis and control of the system model three aspects, and analysis the torsional vibration mechanism and control strategy in detail by using theoretical analysis and numerical simulation, which promotes the development of nonlinear theory research and engineering application.Firstly, considering unsaturated magnetic circuit and the coupling effect of electrical parameters and mechanical parameters, the nonlinear torsional vibration model of the main drive system is established in this paper. The dynamical equation of electromechanical coupling vibration in rolling mill drive system is deduced by using the dissipation Lagrange equation.Secondly, the system equilibrium point and characteristic roots were analyzed. Choosing the torsional rigidity of rotating shaft as a bifurcation parameter and the necessary and sufficient conditions of Hopf bifurcation are given. The bifurcation characteristics of the system is investigated and the Washout filter is adopted to control the Hopf bifurcation, then the effect of the controller parameters were analyzed by using the Direct Normal Form method.Thirdly, the equivalent low-dimensional bifurcation equation is obtained by reducing the system dimensionality using the method of Lyapunov-Schmidt reduction and the bifurcation characteristic is analyzed using the singularity theory. Choosing the torsional rigidity of rotating shaft and excitation amplitude as the bifurcation parameters. The numerical method is employed to analyse the influences of different torsional rigidity and external disturbance excitation on chaotic motion by bifurcation diagram, maximum Lyapunov, phase trajectory and Poincare map.