Synchronous Vibration and Low-Frequency Nonlinear Disturbance Suppression Based on QR-ADRC in Active Magnetic Bearing System

In the magnetic bearing-fluid mechanical loads, surge is a common nonlinear low-frequency vibration under abnormal working conditions. Magnetic bearing motors can also experience same frequency vibration during rotation due to rotor imbalance. These vibrations can cause problems such as noise, collision, and even instability. Active Disturbance Rejection Control (ADRC) can be applied to the suspension control of magnetic levitation systems due to its robustness advantage. This article proposes an active disturbance rejection strategy for magnetic bearings based on quasi-resonant extended state observer (QR-ESO), which can simultaneously suppress both same frequency and low-frequency disturbances of magnetic bearings. Traditional ESO cannot effectively observe the sinusoidal disturbance of rotational frequency caused by rotor unbalance centrifugal force. Therefore, QR-ESO was applied to ADRC for interference estimation, and its sinusoidal disturbance estimation characteristics were analyzed. This study was tested on a 5-axis AMB test bench rotating in 3300 rpm. Centrifugal force disturbances are caused by rotation, and low-frequency currents are injected to simulate large nonlinear disturbances. Compared to traditional PID controllers, the same frequency vibration was attenuated by 26 dB, and the low-frequency vibration was attenuated by 15 dB, demonstrating the effectiveness of the proposed vibration reduction strategy.