Design And Research Of Direct Drive In-wheel Motor

Electric vehicles are the main direction of future automotive research and development,and have broad market prospects.The development of key technologies for electric vehicle drive systems has become a research focus.Electric vehicles driven by in-wheel motors are conducive to the lightweight,electrification,integration,high efficiency and rationalization of space arrangements of electric vehicles,and they have more advantages than other forms of electric vehicles.As the core component of the power output of electric vehicles,the in-wheel motor has high requirements for its structure and working performance,and the key to the motor is its electromagnetic characteristics.In addition,due to the special working environment of the in-wheel motor,temperature control and mechanical strength issues cannot be ignored either.Therefore,the electromagnetic structure design of the in-wheel motor and the analysis and research of the electromagnetic field,temperature field and mechanical structure strength have important practical significance.This paper takes the permanent magnet synchronous in-wheel motor of electric vehicle as the research object,and conducts design research on the in-wheel motor.The main research contents and conclusions are as follows:(1)First,according to the technical requirements of the designed in-wheel motor,the common in-wheel motor drive mode,magnetic circuit structure,permanent magnet performance and motor related parameters are analyzed and calculated.A prototype of a 6.8k W permanent magnet synchronous in-wheel motor with 48 slots,46 poles,six-phase double-layer short-pitch distributed stacked windings and selected neodymium iron boron N30 UH permanent magnet material was designed.(2)According to the basic parameters of the prototype,an electromagnetic field simulation model is established in ANSYS Motor-CAD software to simulate and analyze the internal electromagnetic field of the in-wheel motor.The results show that the internal magnetic field distribution of the in-wheel motor is uniform and reasonable,and there is no magnetic saturation.The overall design of the magnetic circuit of the in-wheel motor is reasonable.The electromagnetic torque fluctuates in a small range in the range of 144～146N ? m when the motor is running under load,which meets the requirements of in-wheel motor design.The results show that the electromagnetic design of the in-wheel motor is reasonable and meets the motor design requirements.(3)In order to ensure that the mechanical structure of the in-wheel motor can meet the mechanical strength requirements of actual working conditions during operation,the mechanical structure of the in-wheel motor is simulated.The simulation results show that when the in-wheel motor runs between the rated speed(460?8)4)9))and the design maximum speed(1150?8)4)9)),the maximum mechanical stress experienced by it is 4.31(6,which is much lower than the yield strength of silicon steel sheet of 370(6and neodymium.The iron-boron permanent magnet has a yield strength of 80(6,and the mechanical structure of the in-wheel motor is reasonably designed to meet the mechanical strength requirements and ensure the safe operation of the motor.(4)The temperature field of the in-wheel motor is simulated and analyzed.The temperature field finite element simulation model is established,and the heat source loss is coupled to the temperature field simulation model as an excitation,and the temperature field of the in-wheel motor is simulated and analyzed.The analysis result shows that in the internal temperature field of the motor,the maximum temperature of the winding reaches 113.2℃,the temperature of the permanent magnet is 63.6℃,and the maximum temperature is lower than its allowable maximum operating temperature.The material selection of the in-wheel motor is reasonable,meets the design requirements,and can meet the normal operation of the motor.(5)The prototype test was carried out on the prototype,and the test results showed that the prototype was reasonable in design and met the design requirements.