Improved active disturbance rejection control for AMB flywheel system based on inverse system

Active magnetic bearing (AMB) has been widely applied for flywheel system due to the excellent characteristics at high speed. However, limited by processing technology, rotor eccentricity will bring unbalanced vibration which will endanger the whole system. Vibration suppression is an important and unavoidable topic for the further development of AMB. In this paper, sliding mode active disturbance rejection control (SMADRC) strategy based on inverse system decoupling is proposed. Firstly, coupling phenomenon between four degrees of freedom (DOF) in radial direction of the system is analyzed, and a decoupling controller based on the inverse system method is designed. Then, considering the unbalanced force caused by rotor eccentricity, dynamic model of AMB flywheel system under high speed operation is established. Later, conventional nonlinear feedback control law is replaced by sliding mode control and external disturbance will be suppressed by SMADRC. Lastly, tracking performance of extended state observer (ESO) is analyzed, and stability of the system is realized by adjusting control parameters in SMADRC. Simulation results show that the inverse system control (ISC) can realize complete decoupling of radial four DOF and ESO has excellent tracking performance. Compared with conventional control strategy, SMADRC-ISC has better dynamic performance and can effectively suppress the unbalanced vibration caused by rotor eccentricity, which amplitude is reduced by 40.9% compared with PID-ISC.