Research On The Ride Comfort Of The Suspended Configurations Of In-Wheel Motor Electric Vehicle

In recent years,with the increasingly serious problem of energy shortage and environmental pollution,the energy-saving and environmental protection of electric vehicle(EV)has become the focus of the global automobile industry.Among them,the in-wheel motor electric vehicle(IWM-EV)has received great attention because of its own advantages such as high utilization rate of interior space,high driving efficiency and intelligent control.However.due to the integration of in-wheel motor(IWM)and other components in the wheel,the unsprung mass of EV is too large,and the vertical performance indexes of the vehicle decreases near the peak of wheel resonance,which will deteriorate the ride comfort of the vehicle.In addition,the coupling excitation of motor vertical excitation and road excitation aggravates the body vibration,further worsens the vibration excitation,also has negative effect on vehicle ride comfort and safety.Therefore,the research on the influence of IWM suspended configuration on vehicle ride comfort and how to reduce the negative effect of vertical vibration under the dual excitations has become an inevitable key issue in the development of IWM-EV.In view of the above problems of the reduction of vehicle ride comfort due to adding IWM to EVs,this paper first comprehensively analyzed the influence of EV configurations on ride comfort.Then the feasibility of turning IWM into the dynamic vibration absorber(DVA)and influence factors were analyzed.The configuration models of motor stator suspended and motor overall suspended as the DVA were established.The optimization method of the suspended configurations was established to compare and analyze ride comfort of the two suspended schemes and the optimal configuration was obtained.The improvement degree of ride comfort of active and passive control of optimal configuration was compared.In addition,the multi-objective optimization algorithm was applied to optimize the optimal configuration,and the satisfied configuration and matching parameters were obtained.Finally,the optimization effect was analyzed.The main contents of this paper are as follows.(1)Analysis of EV suspended configuration schemes.Based on the analysis of existing EV wheel structures and common problems,the quarter vehicle models of traditional centralized motor driven EV and conventional IWM-EV were established respectively for ride comfort simulation and analysis.Then the DVA was added to analyze the improvement of ride comfort performance compared with the conventional EV.And the influence of the mass components of the DVA and the residual unsprung mass of the motor on the vehicle ride comfort was analyzed,then the optimal quality ranges of the two parts were obtained.According to the obtained quality influence law.the motor stator suspended configuration and the motor whole suspended configuration were built respectively,which provides the direction for the future ride comfort research of the suspended configuration scheme.(2)Ride comfort analysis and optimization comparison of suspended structures.Firstly,the adverse effect of motor vibration on vehicle ride comfort was analyzed.The ride comfort of the two IWM-EV suspended configurations compared and analyzed,and the optimal suspended configuration was obtained.Among them,the process of configuration optimization includes four parts:the influence analysis of dual excitations of road and motor,the analysis of the impact of speed on ride comfort,the influence analysis of relative displacement of motor stator and rotor,and the analysis of vibration path transfer rate.According to the results of the optimization comparison,the better suspended configuration was obtained,which provides the object for further study on the suspended configuration optimization.(3)Ride comfort performance analysis of active and passive control for the suspended configuration.First of all,the principal mode of different frequencies was analyzed and solved,and the different parts that play the main role in the first to fourth order principal mode were obtained.Then,according to the main connecting parts of vibration mass block,in order to reduce the negative effect of vibration,the active suspension with linear motor as actuator was used,and the performance indexes were compared between the skyhook control strategy and the optimal suspended structure with passive suspension.The ride comfort effect under active and passive control was compared.(4)Optimization of the suspended configuration.Firstly,the vibration response analysis of the parameters of the optimal suspended configuration system was carried out,and the key components that have the greatest impact on the ride comfort of the vehicle were obtained.Then,the influence of the structural parameters of the key components on the ride comfort indexes was analyzed.In order to avoid resonance,according to the range of parameters recommended in the influence law,the parameters of key components were optimized by the improved NSGA-II algorithm based on Pareto optimal solution,and the effectiveness of the optimization was proved by the simulation experiment.The research results provide a certain reference for improving the ride comfort of IWM-EV under dual excitations.