Analysis And Control Of Multi-parameter Coupling Dynamics For High-speed Flywheel Rotor System

Active magnetic bearing(AMB)is a new non-contact supporting device and it has the advantage of zero-friction,no lubrication and being strong suitable for surrounding.Besides,it is available for AMB to control its output force by controlling its current.Flywheel is an energy storing device by transforming electric energy to mechanical energy,which requires low friction loss.AMB-flywheel system is really perfect for energy storing.This paper mainly analyzed the multi-parameter coupling dynamics for an AMB-flywheel systemThis paper set up a four-degree-freedom model for AMB-flywheel system and the influence from the integrative motor/generator and axial bearings is considered.Unified kinetic equations are built by combining flywheel rotor coordinate,drive motor coordinate and axial bearing coordinate.The disturbing force from the integrative motor/generator and axial bearings is regarded as acting on the rotor mass center.As for unbalanced magnetic force(UMP)from motor/generator,an analytical method was proposed to obtained the final expression,which considered separately the ideal flux distribution and distortion factors(including cogging effect,rotor eccentricity,et al.).Then,the influence of UMP to rotor vibrations,control current and control force was analyzed.It is verified by simulation results that harmonic components less than 10 order existed in the flywheel system.In order to study the influence of fundamental component of UMP to the performance of AMB-flywheel system,a simplification method for UMP was proposed and the influence of UMP to the system could be regarded as the change of displacement stiffness in unified kinetic equations.Then,the relation between the UMP and the critical speed and the vibration amplitude of rotor was studied and it was validated by simulation results.As for radial disturbing force from axial thrust bearings,an analytical method based on equivalent magnetic charge wass proposed to calculate the force expression and the result was verified by finite element results.It was indicated that the influence of radial force could be also regarded as the change of displacement stiffness in unified kinetic equations.In order to suppress the harmonic components and fundamental component of rotor vibrations and control current in AMB,a repetitive controller was introduced and the design procedure based on classical control theory was given.The effectiveness of repetitive controller was validated by simulation results.At last,the AMB-flywheel experiment platform based on dSPACE control system is introduced.The influence of UMP’s fundamental component and harmonic components was validated and the effectiveness of repetitive controller for suppressing the vibrations was validated by experiment results.