Global bifurcations for a rotor-active magnetic bearings system

In this paper, the global bifurcation for a rotor-active magnetic bearings (AMB) system with the time-varying stiffness is investigated through discussing the zeros of the Melnikov function. Some critical conditions of chaos occurring are given. According to the results, the case that the order of Melnikov function is more than or equal to 2 is more general than other case (no zero or simple zero). In other word, homoclinic tangency may occur in several resonance relations.