Design And Optimization Of Axial Flux Permanent Magnet Motor For Electric Vehicles

As people pay more attention to energy and environmental issues,electric vehicles have become more and more widely used because of their environmental characteristics.As one of the core modules of electric vehicles,the future development direction of the drive system is high torque density,high efficiency,wide speed ratio and so on.Due to its structural characteristics,the axial-flux permanent magnet motor has the advantages of short axial length,high torque density and high efficiency.Yokeless And Segmented Armature motor(YASA)is a new type of axial-flux permanent magnet motor.Beside having advantages of the normal axial-flux permanent magnet motor,YASA motor also has the advantages of lower iron loss,shorter winding end and higher fill factor,which made it more suitable for the scenarios such as: electric vehicles,flywheel energy storage systems,and renewable energy systems and industrial equipment.In this paper,the Yokeless And Segmented Armature motor for electric vehicles is taken as the research object.The design process of YASA motor is introduced comprehensively.On this basis,the two indexes of torque density and torque fluctuation are optimized.Firstly,the different topology of axial-flux permanent magnet motor are described,and then structural characteristics of the YASA axial flux permanent magnet motor are introduced.According to the design parameters requirements and preset parameters for the electric vehicle drive motor,combined with the sizingl equations and design experience,the design parameters of the motor stator and rotor and permanent magnet materials,as well as the main dimensions of the parameters of the motor and the air gap length.Under different circumstances,the combination of the number of pole slot is analyzed to obtain a suitable pole slot fit.Secondly,after obtaining the electromagnetic program of the Yokeless And Segmented Armature axial-flux permanent magnet motor,this paper uses ANSYS Maxwell finite element software to carry out three-dimensional finite element analysis of the electromagnetic program,and obtains its key performance parameters to verify the rationality of design.Aiming at the key parameters of the motor,such as slot width,magnet pole-arc coefficient,permanent magnet thickness and magnet pole skew angle,the influence of their change on the performance parameters of the motor is studied.The loss of the rated load of the motor is simulated and the rated efficiency is obtained.Taking into account that as a driving motor of the electric vehicle,its operating conditions are more complicated,so that the efficiency of the motor at different speeds and output torque is calculated,and the efficiency MAP map is produced based on the calculation.Finally,a cultural differential evolution algorithm(CCDE)embedded in chaotic strategy is proposed,and multi-objective optimization design of the initial model of the motor is carried out by using support vector machine(SVM)and CCDE algorithm.The optimization process is divided into three parts.Firstly,the parameters affecting the torque density and torque ripple are analyzed.The practical application scenarios and electromagnetic mechanical characteristics of the motor are considered comprehensively,and the appropriate optimization variables and constraints are selected.Then the orthogonal test method is used to determine the parameter combination.Then the Finite Element simulation is carried out to get the sample space.The sample space is used as the training set to train the SVM,and then the SVM regression model of the optimization target is established.Finally,the chaotic cultural differential evolution algorithm is used to optimize the two targets.The Pareto optimal solution set is obtained,and one of the solutions is verified by finite element simulation.The results verify the accuracy and reliability of the SVM-CCDE algorithm model.