Design And Optimization Of Axial Flux In-Wheel Motor For Electric Vehicles

The in-wheel motor has strict requirements on the axial size,overall structure and weight of the selected motor.The traditional hub motor mainly uses radial flux permanent magnet(RFPM),but through the research on the axial flux permanent magnet(AFPM)motor,it is found that Compared with AFPM motor,it has advantages in power density,torque density and axial dimension,and is more suitable for hub motor.In this paper,an axial flux permanent magnet in wheel(AFPM)motor is designed to meet the requirements of the size and performance of the hub motor drive.Firstly,this paper matches the dynamic performance of in-wheel motor.By comparing the various magnetic circuit topologies of AFPM motor,it is considered that the axial flux internal rotor(AFIR)magnetic circuit structure is more suitable for AFPMW motor,and the basic electromagnetic design scheme is given.ANSYS Maxwell finite element analysis(FEA)software is used to check the electromagnetic scheme of the motor.Secondly,in view of the influence of torque ripple on the smooth operation of the hub motor,this paper takes cogging torque and ripple torque as two objectives to optimize the torque ripple.The optimization methods include changing the pole arc coefficient,bevel slot and bevel pole.According to the simulation results of the optimized cogging torque and ripple torque and the comparison of the motor process requirements,it is concluded that changing the pole arc coefficient is the more effective and practical method to restrain the torque ripple of the afpmw motor,and the best pole arc coefficient value of the motor is obtained.Moreover,in order to improve the efficiency of the motor,this paper starts with the loss calculation of the AFPMW motor,this paper uses Maxwell simulation to analyze the loss of the motor,and obtains the following conclusions: the effects of saturation degree of stator on stator core loss of motor;the effects of different materials of rotor support on eddy current loss;the effects of the segment form and the number of segments on the eddy current loss of permanent magnet.Among them,scholars pay less attention to the influence of rotor support materials on the eddy current loss,which is one of the important research contents of this paper.The research shows that different rotor support materials and different rotor support materials have a great influence on the eddy current loss of rotor.In this paper,the influence of four different rotor support materials on eddy current loss suppression is studied,and the results are indirectly verified by temperature rise test of stator and rotor.Finally,according to the optimized design scheme of the motor,the principle prototype is manufactured,and the torque and power of the prototype are tested by the dynamometer,as well as the temperature rise of the stator and rotor with four different materials of rotor support.Then,the motor is loaded and tested.The comprehensive road test results show that the motor performance is good and meets the requirements of the vehicle dynamic performance,and verifies the rationality of the AFPMW motor design scheme.