| In recent years,with the development trend of automobile electricization and intelligence,the number of new energy vehicles has increased rapidly.Electric vehicles have become the most technologically mature and market share of new energy vehicles.Hub motor drive has received widespread attention as an electric vehicle drive,and some car companies have invested a lot of money in hub motor research and development.Because this method has the advantages of fewer intermediate drive parts,high transmission efficiency,small space occupation,convenient use of wire control technology and the development of autonomous driving function,but the hub motor installation and its special working environment,making the motor vibration noise problem more prominent.Mainly manifested in the road surface excitation will cause hub motor eccentricity,eccentricity will not only aggravate vibration but also produce unbalanced magnetic pull to make eccentric problems more serious.The vibration of the hub motor will shorten the life of the motor itself due to fatigue and other problems,and will also make the comfort of the whole vehicle worse.Therefore,this paper studies the vibration characteristics of permanent magnet synchronous hub motors under the condition of road surface excitation.First of all,the system dynamics model of the hub motor as a three-part composition of a torator,bearing and rotor is established,and the initial eccentricity of the wheel motor during different operating conditions is calculated by simulation of the built model.After verifying the accuracy of the road model,the eccentricity of the hub motor in different driving speeds,different levels of road and different load quality on tires is explored.Among them,the vehicle travel speed and road level will have a greater impact on the eccentricity of the hub motor,and the wheel load on the eccentricity of the fixed rotor is less influential.Secondly,the two-dimensional finite element model of the hub motor is established,and the twodimensional finite element model is verified by calculating the empty magnetic cloud map,tooth slot torque,load magnetic chain,etc.of the hub motor,and using this model to calculate the magnetic dense cloud map of the rotor air gap magnetic field of the hub motor under different eccentric distance conditions,as well as the vertical electromagnetic force of the stator and rotor,i.e.the unbalanced magnetic pull force.Wherein eccentricity causes the gyration to be subjected to the sine fluctuation of the vertical unbalanced magnetic pull and the magnetic field at the same frequency,and the rotor is affected by the vertical unbalanced magnetic pull main part is the constant force with zero frequency.Then,considering the coupling relationship between electromagnetic field and dynamic system,further analysis of the unbalanced magnetic pull will often have an impact on the eccentric distance of the hub motor,the hub motor several typical three iterations of the calculation of the operating conditions,and finally found that the eccentric distance of the hub motor will gradually tend to stabilize the value,the unbalanced magnetic pull will gradually stabilize with the eccentric distance.Finally,the electromagnetic force wave corresponding to the eccentric distance of eccentricity reaching a stable state is taken as the source of excitation,and the motivation source obtained by the road surface incentive is not considered.It is concluded that the spatial order of the excitation source will increase after considering road incentive,but the frequency component of the incentive source will not change.Finally,the first 6-order mode of hub motor twin and rotor is calculated,the radial vibration type of the tyrone is mainly the deformation of the syringe tooth,and the radial second-to fourth-order mode vibration type of the rotor is the ellipse,triangle and quadrection vibration shape.The vibration response characteristics of the hub motor in the absence of eccentricity and road excitation eccentricity are analyzed,and the results show that the vibration displacement at some point on the rotor is the largest vibration displacement in the X and Z axis directions at 320 Hz,and the vibration displacement value in the Y-axis direction at 1920 Hz is the largest.At the same time,the vibration amplitude is large at 640 Hz,960Hz and1920 Hz.The vibration displacement of a certain point of the pronamuary is mainly at 320 Hz,and the point on the tyrannut has a peak at 2560 Hz in the direction of the X axis.The reasons for the large vibration magnitude caused by different frequency components are analyzed. |
