Dynamics Characteristic Analysis Of Active Magnetic Suspension Flywheel Shaft Rotor

Compared with traditional battery energy storage system, flywheel energy storage system has many advantages as a new type of energy storage, such as higher energy storage density, higher specific power and power density, lower risk of overcharge or over-discharge,very long life cycle and environmental friendliness and broad application prospects. As the energy storage flywheel prototype design for the 600Wh research background, this research focused on dynamic characteristics of flywheel rotor. Its dynamic characteristics including critical speed of the flywheel rotor and steady-state response at operating speed. the quality of its dynamics will directly affect the rotating accuracy and stability of the flywheel rotor. Lay the foundation for the subsequent commissioning of flywheel energy storage system, it is necessary to study flywheel rotor dynamic characteristics.Firstly, this paper summarizes the research status at home and abroad about the flywheel energy storage technology and the rotor dynamics research methods. Secondly, the mathematical model and mechanic models have been established using traditional dynamics combined with the characteristics of AMB. Then, by considering the characteristics of AMB and adapting the traditional transfer matrix method to active magnetic suspension rotor system, a method is established for calculating and analyzing dynamics. Set upper and lower radial magnetic bearing different stiffness and analysis three cases support stiffness change on the distribution of flywheel rotor critical speeds, and the relationship between rotor critical speed and the magnetic bearing stiffness has been obtained.Using ANSYS WOEKBENCH finite element analysis flywheel rotor modal, comparing with the transfer matrix method and verify the accuracy of the analysis results. Calculate the flywheel rotor critical speed respectively in the elastic support conditions. In the finite element model of the elastic support, by assigning different value on the spring unit Body-Ground, the flywheel rotor critical speed can be obtained at any stiffness conditions. In engineering applications, the flywheel rotor running under different operating speed, by adjusting the magnetic bearing support stiffness, making flywheel rotor critical speed away from its working speed to avoid resonance.The results were used to verify the correctness of the dynamics model. Because of the external excitations in the actual operation, including mass imbalance, basic incentives. A digital filter designed by the data signal processing using time domain analysis and frequency domain analysis in-depth study, the unbalance response to external incentives were expected based on the flexible rotor model. Simulation analysis show that the variation of the mass unbalance response at the lower bearing, to provide reference for rotor balancing.