Temperature Field Simulation And Heat Dissipation Design Of Outer Rotor In-wheel Motor For Electric Vehicle

Electric vehicles have enjoyed great popularity by the characteristics of little pollution to environment and low energy consumption.Because of the characteristics of simple structure,high power factor and high transmission efficiency,in-wheel driven electric vehicle has received a lot of attention.With the increasing demand of highefficiency and high power driving system,solving the problem of motor temperature rise will be the key to improve the performance of driving system.In order to ensure the stable and efficient operation of the electric vehicle,the precise calculation of the temperature field of the motor is indispensable to the design of the driving motor.In this paper,the electromagnetic-heat-fluid-solid coupling analysis is mainly focused on the electromotor of the outer rotor permanent magnet synchronous in-wheel motor of electric vehicle.The main work contents include the following aspects:First of all,according to the theory of heat transfer and fluid mechanics,this paper analyzes the forms of heat transfer among the parts of in-wheel motor.Then on the basis of the structure characteristics of the in-wheel motor,simplify the model,calculate the thermal conductivity coefficient of each part and the heat transfer coefficient between the parts.Secondly,using the principle of the motor,create in-wheel model of motor in finite element software,simulate the electromagnetic field of in-wheel motor in rated condition,lines of magnetic force and magnetic induction intensity distribution cloud associated with motor loss is obtained.On this basis,Based on the finite element and empirical formula,the loss of each part of the motor is obtained,and obtain loss density contours of each main part by using the finite element simulation,providing the heat source for the motor temperature field simulation.Thirdly,a model is established for the simulation of two-dimensional temperature field,and the magneto-thermal coupling simulation of the in-wheel motor is carried out using ANSYS Workbench to obtain the initial temperature appreciation of the motor.Based on the theory of fluid heat transfer,the solution equation of fluid-solid coupling temperature field of in-wheel motor is established.Then the wheel motor cooling structure is analyzed,and compare the effects of different cooling structures on the temperature rise of the motor,determine the optimal cooling.On the structure of the selected cooling channel,analyze the effect of different cooling water velocity on the temperature rise of the in-wheel motor.Finally,the cooling structure of the outer rotor in-wheel motor is determined,and the temperature rise curve of the cooling structure is obtained by simulation,which proves the rationality of the structure.