The bifurcation characteristics of the active magnetic bearing-rotor system subjected to the external excitation were investigated analytically when it was operating at a speed far away from its natural frequencies. During operation of the system, some nonlinear factors may be prominent, for example, the nonlinearity of bearing force and current saturation. Nonlinear factors can lead to some complicated behaviors, which have negative effects on the operating performance and stability. To analyze the bifurcations happening at the speed far away from harmonic resonances, an approximate analytical method that can be applicable to the bifurcation analysis of the forced vibration system was proposed. By applying it to the active magnetic bearing-rotor system, multiple static equilibriums and periodic solutions were obtained, and then, the stability analysis was conducted based on Floquet theory. The validity and accuracy of the approximate analytical method were verified by the numerical integration method and generalized cell mapping digraph method. It was found that there was supercritical pitchfork bifurcation of static equilibrium in the active magnetic bearing-rotor system. The influences of external excitation and controller parameters on dynamical characteristics were discussed. Based on analysis results, controller parameters were also improved to prevent nonlinear behaviors and improve system performance.

主动磁轴承-转子系统在远离其固有频率的速度下运行时的分叉特性进行了分析研究。在系统运行期间，一些非线性因素可能会很突出，例如，承载力和电流饱和度的非线性。非线性因素会导致某些复杂的行为，从而对运行性能和稳定性产生负面影响。为了分析在远离谐波共振的速度下发生的分叉，提出了一种适用于强迫振动系统分叉分析的近似分析方法。将其应用于主动磁轴承-转子系统，可以获得多个静态平衡和周期解，然后，稳定性分析是基于Floquet理论进行的。通过数值积分法和广义单元映射图法验证了近似分析方法的有效性和准确性。研究发现，在主动磁轴承－转子系统中，存在超静态的动平衡分叉。讨论了外部激励和控制器参数对动力学特性的影响。根据分析结果，还改进了控制器参数，以防止非线性行为并改善系统性能。研究发现，在主动磁轴承－转子系统中，存在超静态的动平衡分叉。讨论了外部激励和控制器参数对动力学特性的影响。根据分析结果，还改进了控制器参数，以防止非线性行为并改善系统性能。研究发现，在主动磁轴承－转子系统中，存在超静态的动平衡分叉。讨论了外部激励和控制器参数对动力学特性的影响。根据分析结果，还改进了控制器参数，以防止非线性行为并改善系统性能。