Improved Second-Order Repetitive Control with Parameter Optimization for Magnetically Suspended Rotor System

In magnetically suspended rotor (MSR) system supported by active magnetic bearings, the mass imbalance of the rotor and the sensor runout lead to multi-frequency vibration of the rotor system, which seriously affects the operation accuracy. In order to suppress the harmonic vibration in the MSR system, an improved second-order repetitive control (SORC) method based on parameter optimization is proposed. Firstly, the dynamic model of MSR system is established. The necessity of restraining the current stiffness force can be confirmed through the division and further analysis of the bearing force. Then, an improved SORC structure diagram is constructed, and the coupling relationship between control gain and weight factor is determined by system stability criterion. Next, for the rapidity, stability and steady-state accuracy in the convergence process, parameters are optimized separately. Then, stage integration can achieve a better balance of performance impacted by parameters. Finally, the simulation results show that the proposed scheme can effectively suppress the multi-frequency vibration of the MSR system.