Research On NVH Of Powertrain System Under Multi-source Excitation

The powertrain system consisting of a motor and a reducer is the core component of an electric vehicle.The performance of the NVH(Noise,Vibration,Harshness)determines the comfort of the vehicle to a large extent.Based on the current research on NVH of electric vehicle power system,most of them are based on motor and reducer.The NVH problem of powertrain system is based on internal excitation analysis,system coupling modeling,dynamic simulation and experiment.The research is carried out to provide a design solution for the analysis and optimization of the electric vehicle powertrain system NVH.Firstly,the electromagnetic excitation and mechanical excitation that cause the vibration and noise of the powertrain system are analyzed.For the motor part,the distribution form of the radial electromagnetic force of the permanent magnet synchronous motor under the action of three-phase sinusoidal alternating current is derived.At the same time,using electromagnetic finite element simulation and spectrum analysis,the order distribution of radial electromagnetic force under no-load and rated load conditions is obtained.The simulation results show that the main radial electromagnetic force harmonic order of 8-poles 48-slots permanent magnet synchronous motor is Multiple times of 8;for the source of the noise of the reducer,the main factors causing the vibration and noise of the gear during the transmission process are explained.Secondly,the coupling model between the shell of the powertrain system and the stator core is established.The contrast modal analysis is carried out for the influence of the motor shell and the reducer housing on the system mode.The simulation results show that the natural frequency of the system is improved on the condition of the same stator core radial mode shape and considering the motor casing and the reducer casing;the other natural frequency of the system is different when the same order mode is used.decline.On the basis of the powertrain coupling system model,and considering electromagnetic excitation and mechanical excitation,the model of powertrain system under multi-source excitation is established.The vibration and noise caused by electromagnetic excitation and the vibration caused by gear mesh excitation are analyzed.The simulation results show that the vibration and noise of the powertrain system are affected by electromagnetic excitation and mechanical excitation.Then,based on the powertrain coupling system model,a parameterized optimization strategy for the stator slot width selection by multi-source excitation dynamics simulation results are proposed for the electromagnetic scheme.The number of connecting bolts and the damping between the motor and the reducer are increased to optimize the vibration and noise of the system.Finally,the NVH characteristics of the prototype were tested using LMS Test.Lab.The test results show that the noise is larger when the reducer housing is considered under the same electromagnetic excitation and environment;the spectrogram of the experimental results agrees with the simulation results.By comparing the experimental results with the simulation results,the necessity of coupled modeling of the powertrain system and the feasibility of the modeling method in the paper can be seen.