Vibration Control Of An Active Magnetic Bearings-flexible Rotor System Based On Recursive Least Square Algorithm

Active magnetic bearings(AMBs)have gradually become the main support unit in high-speed rotating machinery because of its characteristics of no contact,no lubrication and no wear.This thesis mainly analyzes and studies the vibration control of an AMBs-flexible rotor system under unbalance excitation,harmonic excitation and base excitation.Firstly,the dynamic equation of the AMBs-flexible rotor system is obtained by finite element method.Combined with the mathematical models of the power amplifier and displacement sensor in the control system,the model of the AMBs-flexible rotor control system is established.Then,the modal analysis of the flexible rotor supported by AMBs with different equivalent stiffness is carried out,and the modal frequencies,modal shapes and critical speeds of the flexible rotor are given.Finally,in order to simplify the design process of the controller,the reduced-order model of the AMBs-flexible rotor system is obtained by the modal truncation method.Aiming at the vibration control of the AMBs-flexible rotor system under unbalance excitation,this thesis first introduces the adaptive filter based on recursive least square(RLS)algorithm,describes the iterative process of RLS algorithm,and analyzes the performance of the RLS adaptive filter on tracking and filtering sinusoidal signals with constant frequency and variable frequency.Then,based on the RLS adaptive filter,the RLS adaptive controller for synchronous vibration suppression is constructed.The controller extracts the synchronous signal in the vibration displacement of the rotor and outputs the compensation signal through the iterative process of RLS algorithm,so as to reduce the vibration displacement of the flexible rotor under unbalance excitation and make the rotor safe to pass through the first-order bending critical speed.Finally,the effectiveness of the controller is verified by simulation,even under a certain level of noise.Aiming at the vibration control of the AMBs-flexible rotor system under harmonic excitation,this thesis first introduces the composition of harmonic interference from the displacement sensor,and then connects several RLS adaptive filters in parallel to form the RLS adaptive controller for harmonic vibration suppression to filter out each frequency component in harmonic interference.Finally,the effectiveness of the RLS adaptive controller to suppress the harmonic vibration of the flexible rotor is verified by simulation.Aiming at the vibration control of the AMBs-flexible rotor system under base excitation,this thesis first introduces the source of base excitation.The influence of base excitation is considered during the system modeling,and the model of the AMBs-flexible rotor system under base excitation is established.Then,based on the RLS adaptive filter,the RLS adaptive controller for suppression of the rotor vibration due to base excitation is designed.According to the acceleration of the base and the relative displacement of the rotor to the bearings,the controller outputs the compensation signal through the iterative process to reduce the vibration displacement of the flexible rotor caused by the base excitation.Finally,the simulation results show the great performance of the RLS adaptive controller on the vibration suppression.Finally,the experimental platform of the AMBs-flexible rotor system is constructed and improved,and the vibration control experiments of the AMBs-flexible rotor system under unbalance excitation,harmonic excitation and base excitation are carried out to verify the effectiveness of the RLS adaptive controller.