Multi-Physical Field Characteristic Analysis And Optimization Design Of Hub Drive System

In recent years,people's awareness of environmental protection has been further enhanced,new energy vehicles have attracted the attention of all parties.As the core technology of new energy vehicles,in-wheel motor(IWM)has been paid more attention by various automobile companies.The advantages of IWM are high power density and high torque density,which have been widely studied and applied in the field of motors.As the key component of the hub drive vehicle,the structure and performance of the hub drive system directly affect the driving/braking performance of each drive wheel and the driving performance of the vehicle.At the same time,because of the large torque required at low speed,the design of the hub drive system is mostly from the point of view of satisfying the power of the whole vehicle,due to the limitation of space and operating environment,the heating of hub drive system is more serious,and the temperature will inevitably affect the characteristics of electromagnetic field and flow field of IWM,in order to accurately analyze the multi-field characteristics of hub driven system,a motor model which is more suitable for actual operation needs to be established.Firstly,this paper takes 15 KW inner rotor permanent magnet synchronous motor as the research object,the electromagnetic field,temperature field and flow field of IWM are analyzed by finite element method,the electromagnetic torque and the loss of each component of the motor,the maximum temperature of each component and the flow velocity and pressure of the flow field are obtained,through the formula calculation and the existing results,compared with the simulation results to verify the correctness of the model.Secondly,three-dimensional modeling of electromagnetic-temperature field,temperature-flow field and electromagnetic-flow field of IWM is carried out,The coupling simulation analysis of electromagnetic-temperature field,temperature-flow field and electromagnetic-flow field is carried out by using finite element simulation software,the electromagnetic torque,loss,maximum temperature,flow velocity and pressure of IWM are obtained,the two field coupling analysis is proved to be accurate by comparing the two field simulation results with the single field simulation results,at the same time,the coupling factors between the two fields are obtained,and the strong coupling factors and the weak coupling factors between the two fields are clarified.Then,based on the local two-field analysis,considering the strong coupling factors and neglecting the weak coupling factors,the three-field coupling analysis model of hub motor with suitable complexity is established,and then the electromagnetic field,temperature field and flow field characteristics of IWM are analyzed under certain driving conditions by using the established multi-field coupling model.Finally,based on the three-field coupling model under rated working conditions,the optimization analysis of IWM is carried out,with the stator slot of IWM and the size of stator and rotor core as the optimization variable,the objective of optimization is to maximize the electromagnetic torque and minimize the maximum temperature and mass of the IWM.By establishing multiple regression equation and particle swarm optimization,the optimal design of IWM is carried out.