Critical Speed And Unbalanced Response Analysis Of Vertical Magnetic Suspension Flywheel Rotor System

Magnetic suspension flywheel energy storage system is a mechanical device that performs inertial energy storage and energy release under the support of electromagnetic bearings.With the advantages of low energy consumption,low pollution,long service life and convenient maintenance,it has a great application prospects in energy storage.Because the operating speed of the high-speed magnetic levitation flywheel energy storage system is often above the first-order critical speed,and the air gap between the rotor system and the bearing is very small.The vibration cannot exceed the air gap value.Therefore,this paper takes the vertical magnetic suspension flywheel energy storage system as the research object,and analyzes the critical speed and unbalanced response of the rotor system.First,the dynamic model of the rotor system is established.Analyze the structural layout of the entire magnetic suspension flywheel rotor system.According to the support characteristics of the electromagnetic bearing,the calculation formula of the electromagnetic force of the electromagnetic bearing and the specific expressions of equivalent stiffness and equivalent damping are derived.And the equivalent stiffness and equivalent damping range are obtained.The differential equations of motion of the magnetic levitation rotor system were established,which laid the foundation for subsequent analysis.Second,calculating and analyzing the critical speed of the rotor system.The first two order critical speeds of the rotor system were calculated by rotor frequency equation,transfer matrix method,and finite element method.The calculated results are in good agreement,indicating the accuracy of the critical speed calculation results.The influence of interference amount on critical speed is also analyzed.Then the unbalanced response of the rotor system is analyzed.The reasons for the eccentricity and the vibration mechanism of the unbalanced response are explained first.Then the steady-state and transient unbalanced responses of the rotor system are analyzed.For the steady-state unbalanced response,the steady-state response of the rotor system at constant speed is analyzed,and the effect of the equivalent stiffness on the steady-state response is analyzed;For the transient unbalanced response during the speed increase and decrease,the effects of angular acceleration,equivalent stiffness,equivalent damping and eccentricity on the transient response of the system are analyzed.Finally,the 600 Wh flywheel energy storage system is used for lifting speed test.The calibration experiment of the eddy current sensor is carried out to obtain the working range and sensitivity of the eddy current sensor.Carry out static suspension debugging on the system to find the static stable position of the system.The system is tested for rising and falling speed,and the data in the whole process are obtained by using the data acquisition system,and the data processing is carried out to obtain the time domain diagram,frequency domain diagram and axis trajectory diagram of the system at the critical speed and stable operation time.From the frequency domain diagram,it can be obtained that the rotor system is greatly affected by unbalanced excitation.From the time domain diagram,it can be obtained that the rotor system has a large amplitude of vibration at critical speeds.From the axis trajectory diagram,it can be seen that the upper axis trajectory is crescent shaped and the rotor system has the problem of poor alignment.