Research On Vibration Analysis And Vibration Suppression Method Of An Electric Vehicle Electric Drive Assembly

The vibration and noise of the electric drive assembly is an important part of the NVH performance of electric vehicles,and with the development of the electric drive assembly towards the direction of deep integration,high speed and lightweight,the NVH performance of the electric drive assembly has brought more severe challenges.Therefore,the research on the vibration mechanism of the electric drive assembly,the establishment of vibration analysis model and the research on vibration characteristics under multiple working conditions have become the key issues to improve the NVH performance of the electric drive assembly.Focusing on the above key issues,this paper takes the electric drive of an electric vehicle as the research object and uses the vibration and noise analysis process: excitation source-propagation way-acceptor to carry out the theoretical,simulation and experimental systematic research on the vibration response mechanism and vibration suppression method of the electric drive assembly.The main research contents are as follows:1.Complete the theoretical analysis of electromagnetic force based on Maxwell’s tensor method.The electromagnetic model of permanent magnet synchronous motor was built,and the electromagnetic calculation was carried out under specific working conditions.After post-processing,the variation curve of the radial electromagnetic force with time,the frequency spectrum of the electromagnetic force,the variation curve of the radial electromagnetic force with space and the spatial modulus law were obtained.The preprocessing preparation of the cored torque was completed,and the cored torque results were obtained.Combined with the theory,the effectiveness of the electromagnetic model was judged.2.The rigid-flexible coupling dynamics model of the electric drive assembly was built,and the change curve of the gear transmission error in the reducer was obtained,and the influence of the transmission error curve on the gear noise was judged.Then the transmission error is used as the excitation to calculate the dynamic forces of the six bearing seats on the reducer housing,and the spectrum analysis of the dynamic forces of the six bearings is completed.3.Established the modal analysis model of the electric drive assembly system,and completed the inherent modal calculation of the electric drive assembly under the unconstrained state;Free modal experiments were carried out to verify the validity of the finite element model of the electric drive assembly.Based on the verified finite element model,the inherent mode of the electric drive assembly system under the actual constraint state was calculated.Combined with the electromagnetic force frequency,the resonance risk of the electric drive assembly was determined.Finally,the modal strain energy theory is used to find the weak local stiffness,which provides guidance for the subsequent structural optimization.4.The vibration model of the electric drive assembly under the electromagnetic-mechanical-structural coupling is built,and the harmonic response calculation of the vibration acceleration of the electric drive assembly is completed.It is found that the main contribution component of the electric drive assembly is the motor shell.Based on the national standard of acoustic vibration experiment,the experiment outline was formulated to complete the acoustic vibration experiment of electric vehicle.It was determined that the electric drive assembly mainly had electromagnetic noise and resonance noise.The vibration spectrum diagram of the motor shell surface was used to verify the effectiveness of the vibration model of the electric drive assembly.5.For the resonance noise,the structure is optimized based on the modal strain energy theory.After optimization,the modal strain energy is no longer concentrated,the vibration sensitivity is weakened,and the resonance risk is reduced.Aiming at the electromagnetic noise,the method of rotor opening auxiliary grooves was adopted to optimize the DOE of electromagnetic noise,so as to find the optimal combination of rotor auxiliary grooves factors to reduce the change of cog torque and output torque.The optimized electromagnetic scheme and structural optimization scheme were brought into the vibration response model of the electric drive assembly.The vibration acceleration spectrum diagram of observation points showed that the optimization effect was obvious.The rotor grooving had little influence on the motor performance through the efficiency test,which ensured the effectiveness of the optimization scheme.