Enhanced Repetitive Control with Phase Compensation Based ADRC for Harmonic Suppression in Magnetically Suspended Rotor Under Strong Gyroscopic Effects

Magnetically suspended rotor (MSR) systems have gained widespread industrial adoption owing to their frictionless operation and exceptional reliability. However, harmonic current generated by unbalanced mass and sensor runout threatens the system stability. Repetitive control (RC) effectively suppresses harmonic current, but its parameter design relies on an accurate decoupling model of the system. The decoupling model for the MSR system is often simplified to a second-order linear system. Such a simplification, however, necessitates explicit consideration of system uncertainties caused by unmodeled nonlinearities during the RC design process. Especially under strong gyroscopic effects, the parameter uncertainty is further increased. In this article, an active disturbance rejection controller (ADRC) based on phase compensation (PC) is used to suppress coupling disturbances and improve the control performance of harmonic suppression. Firstly, the dynamic model of the MSR system is established, and both internal and external disturbances are thoroughly analyzed. Then, the RC-PCADRC scheme is designed, integrating the complementary strengths of RC and ADRC, with a particular emphasis on PC to improve stability margins. A comprehensive stability analysis is conducted, along with parameter optimization guidelines. Finally, the effectiveness and superiority of the proposed scheme are validated through both simulations and experiments.