Abstract:In this paper, the equal effective non-linear mathematical model of the brushless DC motor system is studied, the Hopf bifurcation behavior of system is investigated, and the washout filter is adopted to control the Hopf bifurcation behavior of the system. Then, the Hopf bifurcation normal form of the controlled system is obtained using the direct normal form method. According to the normal form coefficient, the selection criteria of the parameter and its effect on the periodic solution′s amplitude and Hopf bifurcation type of system are discussed. Theories and simulation results show that without the controller, the subcritical Hopf bifurcation occurs and unstable limit cycles appear, which leads to chaos. However, with the controller, supercritical Hopf bifurcation occurs, and the cycles of the original system become stable when the real part of coefficient of normal form is less than zero. Thus, the chaotic behavior of the system is controlled, and the stability of the motor′s running performance is ensured.