Analysis And Control Of Vibration And Noise Of Electric Powertrain

With the continuous development of the automobile industry,the problems of vibration and noise of automobile parts have received extensive attention from researchers.The electric powertrain is the core component of the entire electric vehicle,and its vibration and noise performance is closely related to the NVH performance of the electric vehicle.Compared with traditional fuel vehicles,electric vehicles lack the masking effect of the engine,and the noise of the electric powertrain becomes the main noise source.Therefore,how to analyze and control the vibration and noise of the electric powertrain has become a key factor to improve the NVH performance of electric vehicles.In this paper,a certain "three-in-one" electric powertrain is always the research object,and its vibration and noise characteristics are analyzed and measures are taken to control it.The main research work of this paper is as follows:On the basis of considering the superposition effect of the stator core,the finite element model of the "three-in-one" electric powertrain structure is established based on the Hypermesh software,and the restraint modal analysis under the simulated actual mounting state is carried out,and the controller is compared and analyzed.The modal difference between the housing and the motor-reducer integration.Based on the structural parameters of the drive motor,a finite element simulation model of the drive motor’s electromagnetic field was established through Maxwell software.The output torque fluctuation,magnetic density cloud map and magnetic field line distribution of the motor were obtained,and the frequency characteristics of the air gap magnetic density were analyzed.The spatial and frequency characteristics of the electromagnetic force of the motor are analyzed by Fourier transform,and the concentrated electromagnetic force on the stator tooth surface is extracted.The AVL EXCITE POWER UNIT software is used to build a multi-body dynamics model of the electric powertrain.The excitation is applied as the torque ripple obtained by the motor simulation,and the excitation amplitude at each bearing of the reducer is calculated.Based on the hybrid FE-SEA method,the vibration and noise analysis model of the electric powertrain is established in the VA One software.The electromagnetic force of the motor and the bearing force of the gear shaft system of the reducer are used as excitation signals to solve the forced vibration response characteristics of the electric powertrain.The semi-infinite fluid analyzes the radiated noise of the electric powertrain.The electric power train is placed in a semi-anechoic room for noise testing,and the noise characteristics of the electric powertrain are obtained by using the method of order analysis for transient working conditions.The radiated noise simulation results and the experimental results are compared and analyzed.The error range of the sound pressure level curves of the two is small and the change trend is consistent,thus verifying the accuracy of the simulation model.Based on the power input method,the noise contribution of the electric powertrain components is analyzed,and the components with a larger contribution are found,and the noise is controlled from the transmission path by the method of pasting damping materials.Based on the moving asymptote algorithm,the sound pressure level amplitude is optimized with the thickness of the damping layer and the thickness of the constrained layer of the constrained damping structure as design variables.Aiming at the noise reduction plan of the reducer,the gear micro-modification method is adopted to reduce the gear meshing excitation,which ultimately reduces the radiated noise of the electric drive assembly to a certain extent.