Modelling and stability analysis of the permanent magnetic bearing-rotor system under base excitation

Permanent magnetic bearings (PMBs) hold great potential for various applications such as artificial heart pumps, space equipment, and flywheels. This is due to their notable advantages, including the absence of mechanical contact, no friction, and no control system requirements. However, in many practical scenarios involving PMBs, the bearing installation base is often subject to external excitation, which can interfere with its stability. Currently, the impact of base excitation on the PMB-rotor system and methods for enhancing the stability of the PMB-rotor system under base excitation remain subjects of investigation. Hence, this study focuses on conducting stability analysis of the PMB-rotor system under the influence of base excitation. Firstly, the theoretical model of PMB based on the Halbach array is established, and then the system dynamics model of PMB-rotor under base excitation is established by using the second Lagrange equation. Finally, according to the established dynamic model, the effects of base excitation parameters, structural parameters, and external damping on the stability of the PMB-rotor system under base excitation are analysed through the root locus method. The research results presented in this study provide a theoretical reference for further engineering applications of PMBs.