Dynamic Analysis And Control Strategy Research Of Active Magnetic Bearing Rotor System

Active Magnetic Bearing(AMB)is a new type of high-performance bearing that uses electromagnetic force to provide bearing capacity.Because of its advantages of non-contact friction,no oil pollution,and long life,it is widely used in high-speed motors,ships,and aero engine turbo pump,various positioning systems,flywheel energy storage systems and other fields have broad application prospects.With the development of ferromagnetic materials and new switching device technology,the control performance of AMB will be further improved.This paper takes the eight-pole radial active magnetic bearing(ARMB)as the research object,and studies its system dynamics,suspension control strategy and parameter design.The main research work is as follows:This paper firstly summarizes and analyzes the research progress of AMB’s control strategy,and power amplifier,and analyzes its working principle according to the composition of the ARMB system;Based on the basic structural parameters of the 8-pole ARMB,a single degree of freedom magnetic bearing model is established,and the rotor dynamics model in the form of a single degree of freedom matrix is established.The mathematical model has been preliminarily verified to be correct through the joint comparison and simulation of MATLAB and Maxwell.Secondly,in order to avoid the problem of overshooting and hitting the wall in the magnetic bearing rotor,this paper focuses on analyzing the dynamics of the ARMB system,including theoretical dynamics analysis and measured dynamics analysis.By analyzing and comparing the curves of theoretical and measured motion related quantities,the reasons for the deviation between the two are analyzed,and the theoretical dynamic analysis is corrected,the optimal angle of the electromagnetic offset angle is deduced,and the correctness of the mathematical model is further verified.and practicability,which provides theoretical support for the subsequent control strategy.Then,according to the dynamic analysis of ARMB system,a control strategy to realize the stable suspension of the rotor is proposed.Firstly,taking the constraints of achieving stable suspension and avoiding overshoot as the starting point,two modes,the maximum control and the minimum control are proposed,which are derived from the previous theoretical dynamics analysis.The action point and time range under the two control modes are obtained.Secondly,the PWM modulation strategy is analyzed,and the maximum rate of change of the allowable current of the power amplifier is calculated;Finally,the optimal action point and action time are determined through the simulation analysis of the system.Finally,for the experimental verification,the relevant parameters of the magnetic bearing are designed,including the inner diameter of the stator,the duty cycle of the stator teeth,the number of coil turns,etc.as well as the system software and hardware.The hardware part includes the selection of the main control chip,the design of the power amplifier,and the displacement.The selection of sensors and current sensors,the software part includes the main process,sensor thread,algorithm control thread,etc.The experimental results show that the proposed control strategy can effectively avoid rotor overshoot and achieve good suspension performance.