Analysis On Vibration Characteristics Of Electric Drive System Of Pure Electric Vehicle

With the rapid development of the automobile industry,the contradiction between it and the increasingly scarce petroleum resources becomes increasingly prominent,which has become an important bottleneck restricting its sustainable development.Therefore,it is of great practical significance to change the structure of automobile energy consumption and develop electric vehicles.The system composed of permanent magnet synchronous motor and gear transmission device is the key part of pure electric vehicle,and its performance directly affects the driving quality of new energy vehicles.In order to improve the system efficiency,the electric drive system develops towards the direction of structural integration,which intensifies the influence of electromechanical coupling on the system transmission stability of pure electric vehicle.In this paper,considering the motor rotor installation error,time-varying mesh stiffness,mesh damping and lateral clearance,on the basis of permanent magnet synchronous motor and gear integrated electromechanical coupling vibration caused by the complications caused by all kinds of key technical problems on modeling,the electromechanical coupling dynamic model was established,analyses the effects of various parameters on the system dynamic response.The main contents of the paper are as follows:Considering the air gap eccentricity of permanent magnet synchronous motor,Fourier expansion calculation of air gap permeability was carried out,and the first three values were taken to establish the unbalanced magnetic pull model of permanent magnet synchronous motor.A single tooth cantilever beam model of helical gear system was established.The helical teeth of the helical gear pair are pieced together by several spur teeth along the direction of tooth width.The tooth width and meshing stiffness of each slice are calculated by energy method.The finite element node method was used to model the electric drive system.The whole electric drive system was divided into three types of units,and the complete electric drive system dynamics model was obtained by integrating each system unit module.Finally,the inherent characteristics and modes of vibration of the system are analyzed,and the critical speed of the system is calculated and analyzed considering the effect of high speed gyroscope.Considering the electro-mechanical coupling,the electromagnetic stiffness of the electric drive system makes the rotor system of the motor produce negative stiffness effect.Aiming at the unbalanced magnetic pull caused by rotor eccentricity,an analytical model of the unbalanced magnetic pull was established to obtain the electromechanical coupling model of the vibration of the rotor system.The vibration mechanism and response law of the electric drive system under electromechanical coupling were studied by modeling and analyzing the gear-to-rotor transmission system considering electromagnetic parameters.Finally,the change of time domain and spectrum is analyzed under variable speed.Taking pure electric vehicle BMW I3 as the object,the electromechanical coupling test bench was built,and the unbalanced magnetic tension test was carried out on the test bench,and the actual test results and results were analyzed.