| Nowadays,the electric drive assembly has become the most critical part of new energy vehicles.High speed,high power density,and low vibration noise have gradually become its development direction.Compared to traditional powertrain systems,electric drive systems lack the masking effect of the engine,resulting in increasingly prominent electromagnetic noise from motors and order noise generated during gear meshing;At the same time,high-speed will make the natural frequencies of the entire system of the electric drive assembly become dense and local modes increase.Therefore,it is particularly important to analyze the dynamic response of the electric drive assembly under transient conditions,which has certain guiding significance for solving the vibration and noise problems of the electric drive assembly.In this paper,the two-in-one electric drive assembly is taken as the research object.Firstly,the motor part of the electric drive assembly is analyzed,and the winding equations are established to calculate the magnetomotive force on the stator side and the magnetomotive force on the rotor side.Considering the influence of stator slot,a relative permeability function is proposed.Finally,the radial magnetic flux density and electromagnetic torque are obtained by analytical methods.Based on the ANSYS Electronics Desktop simulation calculation platform,the magnetic flux density and magnetic force line distribution of the permanent magnet synchronous motor are calculated and solved.According to Maxwell’s stress tensor theory,the electromagnetic force distribution in space and time as well as the electromagnetic force distribution in frequency domain can be obtained.Finally,the magnetic flux density and torque obtained by the finite element method are compared with the results obtained by the analytical method,and the results obtained by the analytical method are in good agreement with those obtained by the finite element method,which proves the accuracy of the analytical method.Based on the theoretical basis of axial,radial,and tangential electromagnetic forces,the concept of unbalanced magnetic pull is introduced.The unbalanced magnetic pull is the resultant force of radial electromagnetic forces.The unbalanced magnetic pull is caused by the eccentricity of the rotor in the motor,and after static and dynamic eccentricity,new force waves are generated on both sides of the original force wave order.Based on the Maxwell Electronic Desktop simulation and analysis platform,the relationship between the magnitude of radial electromagnetic force and eccentricity,space,and time is obtained after analyzing the two eccentric methods.The gear transmission system of the two-in-one electric drive assembly is theoretically modeled using the lumped mass method,and the entire system is numerically solved using the Runge Kutta method.It is verified through experiments under two different operating conditions,steady state and transient.It can be seen that the theoretical model and the experimental results are basically consistent,indicating that the theoretical model has a high accuracy and can be used for the next step of the dynamic response analysis of the electric drive assembly.The radial electromagnetic force and motor torque excitation are applied to the gear transmission system,and the acceleration and sharp deceleration conditions of the electric drive assembly were simulated.The bearing force curves of each bearing in the electric drive assembly were analyzed in the time domain and frequency domain.The influence law of excitation on bearing force under two transient conditions and the influence of eccentricity on vibration under acceleration conditions are investigated. |
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