The Research Of The Hopf Bifurcation And Control For The Rotor Speed's Sustained Oscillation Of The Induction Motor System

Sustained oscillation phenomenon of rotor speed is often experienced in an induction motor (IM) variable frequency adjustable speed system during some low frequency areas with light load or no load, and the appearance of sustained oscillation influences system's running quality and reliability.The simplified mathematical model of an IM drive system is first derived, making use of Matlab software and based on S function, Simulink model of the IM drive system is set up and simulation results indicate the existence of sustained oscillation phenomenon.Based on abovementioned research and introducing the bifurcation theory, Hopf bifurcation criterions of the nonlinear system with one variable parameter and two variable parameters changing are studied, and then two dimensional and three dimensional Hopf bifurcation sets are determined. Therefore, Hopf bifurcation essence of sustained oscillation is disclosed. By aid of accurately determining Hopf bifurcation points and showing Hopf bifurcation figures, the sustained oscillation's inherence essence is opened out that the equilibrium points lose stability and undergoes Hopf bifurcation for the IM drive system.At last, the time-delay feedback control method is introduced, and the Matlab/Simulink model of the IM system is set up with time-delay feedback controller. Simulation results indicate that the unstable equilibrium point can be stabilized by time-delay feedback control method and the presented method can effectively control the appearance of sustained oscillation.