Analysis And Research On Temperature Field And Heat Dissipation Of Electric Vehicle In- Wheel Motor

Facing the severe challenges of global energy crisis and environmental change,in recent years,electric vehicle has become the hotspot of the development of automobile industry in the world.In-wheel motor as the core component of electric vehicle,its performance is very important,which directly affects the comprehensive performance of electric vehicle driven by in-wheel motor.Electric vehicles driven by in-wheel motor usually use high-power permanent magnet motors,which are installed in enclosed narrow space,the large amount of heat generated cannot be released in time,excessive temperature will lead to demagnetization of inwheel motor,reduce their reliability and safety,and even affect the performance of the whole vehicle.Thus,It is necessary to analyze the temperature field of in-wheel motor,and take appropriate cooling and heat dissipation measures.This paper is supported by National Fund(51565011)and Jiangxi Jieqing Project(20171BCB23059).Firstly,the force analysis of the electric vehicle is carried out,and the resistance of the electric vehicle in the course of driving is analyzed.Three dynamic indexes of electric vehicle are analyzed and calculated,and two driving modes of in-wheel motor are compared and analyzed.According to the parameters and performance indexes of electric vehicle,the performance requirements of in-wheel motor are analyzed,and the basic parameters such as torque,power and speed of in-wheel motor are calculated.Secondly,the electromagnetic field finite element model of in-wheel motor is established by Ansoft Maxwell software,the electromagnetic transient field of in-wheel motor is simulated under no-load and load conditions respectively,the magnetic line distribution,flux density distribution and cogging torque under two different conditions are obtained.Taking several loss theoretical calculation formulas as the starting point,the mechanism of stator core loss and other losses of in-wheel motor is analyzed and studied,and the simulation results are given respectively,the simulation clouds and curves of several losses of the motor are obtained.The results show that iron loss and copper loss account for the largest proportion.Thirdly,the heat dissipation coefficients of the main components of the in-wheel motor are calculated,and the temperature field model of the in-wheel motor is established.Based on the known heat loss values of the main components of in-wheel motor,the coupling simulation calculation of the in-wheel motor under rated power and rated speed,rated power and peak speed was carried out by ANSYS WB,the temperature distribution cloud of the main components of the motor was obtained.The results show that the winding temperature field is the highest.Finally,the advantages and disadvantages of the two cooling modes are compared and analyzed.Water cooling is chosen as the cooling mode of the motor.According to the structural design requirements of the water cooling channel of the motor,the cooling structure is determined.The CFD software is used to analyze the fluid field of the coolant in the channel,the loss value obtained by Maxwell simulation and the heat dissipation coefficient curve obtained by CFD simulation are imported into the transient field thermal analysis module,the temperature field of in-wheel motor is analyzed by ANSYS WB,and the temperature field distribution before and after cooling is obtained.The results show the rationality of the heat dissipation structure.