Radial Vibration Analysis Of Vertical Rigid Flywheel Rotor System

The flywheel energy storage system is a mechanical device for storing and releasing energy by a high-speed rotating rotor.In order to maximize the energy storage efficiency,a magnetic suspension bearing is used as a supporting bearing,which puts higher requirements on the dynamic precision of the rotor system.In this paper,the vertical magnetic suspension flywheel energy storage system is taken as the research object,and the vibration response of the rotor under various transient speeds is analyzed.Firstly,the linear dynamic model of the magnetic suspension flywheel rotor system is established.This paper analyzes the radial vibration characteristics of the vertical rigid flywheel rotor from three aspects: the free vibration response,the unstable vibration response of the shifting,and the vibration response considering the basic coupling.Establishing a mathematical model of a rigid rotor system and a rotor-base coupling system: According to Newton’s second law and gyroscopic moment basic theory,the radial four-degree-of-freedom motion differential equation of the vertical rigid flywheel rotor under transient speed is established;A four-degree-of-freedom mathematical model of a rigid flywheel rotor-base coupling system is established based on the Lagrangian energy method.Then based on the established linear dynamic model,the radial vibration characteristics of the rigid flywheel rotor are analyzed by numerical integration method.The rotating state of the rotor is divided into two situations: uniform speed and variable speed.When the rotor rotates at a constant speed,the free vibration response is analyzed,and the rigid rotor Campbell diagram is obtained.When the rotor rotates at a variable speed,it is in the transition phase of the non-stationary motion.And the effects of the angular acceleration in the uniform shifting state and the motor driving power in the variable acceleration state on the rotor vibration amplitude are analyzed.In addition,the two-order natural frequency of the flywheel rotor and stator under the coupled system is calculated by the dynamic model of the rotor-base coupling system.The effects of the flywheel speed and the radial support stiffness of the mounting bracket on the vibration response of the rotor and stator are analyzed.Finally,the 600 Wh magnetic suspension flywheel energy storage system test platform is installed,debugged and data collected,and the obtained test data is filtered to analyze the vibration characteristics of the actual rotor motion,and to verify the accuracy of the simulation results.By adjusting the motor speed,the vibration time domain diagram,frequency domain diagram and axial trajectory diagram of the upper and lower ends of the rotor at different speeds are obtained.It is seen from the frequency domain diagram that the unbalanced excitation is more obvious during the rotation of the rotor,and the time domain diagram shows that the rotor has a large amplitude at the critical speed.The axial trajectory shows that the rotor vibration interval does not exceed the air gap value of 0.3 mm,and the vibration trajectory has centering,which is consistent with the previous simulation results.In addition,the specific method of suppressing rotor vibration in the test platform is also analyzed.