Research On Electromagnetic Optimization Design And Cooling System Of Axial Flux Permanent Magnet Motor

Axial flux permanent magnet motor（AFPMM）has the advantages of high power density,high efficiency and short axial length.It has been widely concerned in new energy vehicles,wind power generation,electric aircraft and other applications.But in the meantime,owing to the structural features of AFPMM,there are still many problems to be solved in engineering,such as electromagnetic performance analysis method,optimization design method and effective heat dissipation of motor.Based on the problems of AFPMM,this paper will study it from the following aspects:Firstly,the subdomain method is used to establish the magnetic field analytical model of AFPMM,and the axial motor with three-dimensional structure is equivalent to the motor with two-dimensional structure at its average radius.The Maxwell equations are solved according to the boundary conditions of each sub domain,and then the air gap flux density of the motor is obtained.After obtaining the air gap flux density distribution of the motor,the electromagnetic properties such as no-load back EMF,electromagnetic torque and loss of the motor are analyzed and calculated.The accuracy of the deduced analytical model is verified by establishing a finite element model for simulation calculation and an experiment on an existing 7k W amorphous alloy axial motor.Secondly,the analytical model combined with the genetic algorithm is used to optimize the design of AFPMM.The motor power density and efficiency are selected as the optimization objectives.The outer diameter of motor stator core,the ratio of inner and outer diameter,the number of turns in series per phase of winding,current density,air gap length,stator core length and permanent magnet thickness are taken as the optimization variables,and the value range of motor optimization variables is determined.At the same time,the constraints are set.The optimal design of the motor is realized by multi-objective genetic algorithm.After obtaining the optimization results of the motor,the three-dimensional finite element simulation calculation is used to analyze it and compared with the original data of the motor,so as to verify the effectiveness of the analytical model combined with the optimization algorithm to realize the optimal design of the motor.Finally,the cooling system of the motor is studied.The temperature field and fluid field of the AFPMM with a channel on its outer surface and an integrated cooling fin structure on its inner surface were simulated to obtain the temperature distribution and fluid flow of each component of the motor.A new type of cooling system is obtained by improvement.Based on computational fluid dynamics method,the influence of water inlet and outlet position,inlet water velocity and number of spoilers on the heat dissipation of the motor is studied,which provides a basis for improving the heat dissipation capacity of the axial motor.