| With the development of the hub motor driven car,the hub motor integrated with the wheel needs higher power density and torque density,but it will bring about problems such as excessive power loss,causing the motor temperature to rise too high and the motor to overheat..Excessive motor temperature will not only damage the insulation of the motor winding,reduce the life of the motor,but also cause the permanent magnet to irreversibly demagnetize,seriously affecting the safe driving performance of the vehicle.Therefore,it is of great significance to correctly calculate and analyze the temperature field distribution of the hub motor drive system and design an efficient cooling structure to extend the service life of the hub motor and improve the performance of the vehicle.(1)After summarizing the research status of thermal performance analysis and heat dissipation structure of hub motor at home and abroad,this paper takes the prototype of 3.5kW outer rotor permanent magnet synchronous hub motor for light vehicle as the research object.Firstly,the electromagnetic finite element model of the hub motor was established by using Maxwell electromagnetic field simulation software.The simulated no-load characteristics and load characteristics were compared with the actual parameters of the prototype.The correctness of the electromagnetic field analysis model was verified.Prepare for electromagnetic loss analysis.(2)Eight working conditions of the classic wheel hub motor were selected,and the specific values and variation rules of the electromagnetic losses of the motor components were analyzed,which provided more accurate heat source data for the simulation analysis of the temperature field of the hub motor.(3)The ANSYS transient temperature field simulation module is used to analyze the temperature field characteristics of the hub motor under the rated air condition and the highest overload condition under natural air cooling conditions.In the case of ensuring the calculation accuracy,the complex structure of the stator slot winding,the insulation layer and the stator silicon steel sheet of the hub motor is equivalent and simplified,and the heat dissipation coefficient of the boundary conditions of each component is calculated.After solving the calculation,it is concluded that the cooling effect of the hub motor under natural air cooling conditions is not ideal,and the cooling method needs to be improved.Finally,the correctness of the simulation calculation method is verified by comparing the temperature rise test results with the simulation results.(4)The cooling structure of the Z-channel is designed for the hub motor.The heat-flow coupling simulation method is used to compare the cooling effect of the water channel under different water flow rates,and the optimal cooling design scheme is given.Finally,the simulation results show that the cooling effect of the designed cooling structure can meet the temperature rise requirements of the hub motor. |
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