Design And Analysis Of A New Type Of Axial Flux Motor With Integrated Hub Direct Drive

With the development of industrial intelligence,automatic guided vehicle(AGV)continues to grow in China.As the in-wheel motor of robot joint and wheel drive module,it adopts a direct-drive integrated design,with compact structure,high torque density and reliability.This thesis designs and optimizes an integrated hub direct drive axial flux motor(IHDD-AFM),which plays an important role in promoting the development and application of integrated hub motor.First of all,this thesis investigates the domestic and foreign research progress of in-wheel motors for AGV.Different driving methods are compared and analyzed to determine the design route of high torque density scheme.According to the actual installation environment of joints and wheels of AGV robot,the size limits and performance goals of the IHDD-AFM are set.The motor type and its corresponding topological structure are selected according to the target,and a complete initial design of the motor is obtained through main magnetic circuit analysis,of stator and rotor materials selection,basic dimensions calculation,winding forms selection,and pole-slot fit design.Secondly,based on the initial design scheme,a 3D finite element electromagnetic simulation model for the IHDD-AFM is established,and the performance parameters of the motor under noload and load conditions are obtained to determine the improvement direction of the initial design scheme.Further,by adopting optimization methods such as Halbach permanent magnet array,optimizing pole-slot fit,updating air gap length,and selecting high-performance materials,the design scheme of the IHDD-AFM is improved in many aspects,so that the output torque of the motor is increased by 11.2%.Then,choosing the maximum output torque and minimum torque ripple as the optimization goals,the size parameters of the initial design scheme of the IHDD-AFM are optimized by multiobjective.After comprehensive optimization,the final design scheme of the IHDD-AFM is obtained and 3D finite element simulation analysis is carried out.According to the analysis results,the performance of the designed motor reaches the design goal,and achieves a high torque density level of 55.2Nm/L and 6.5Nm/kg.Finally,in view of the temperature rise problem of the axial flux permanent magnet synchronous motor under high torque density,the final IHDD-AFM design scheme is checked for temperature rise based on the temperature field analysis with Ansys Workbench software.The highest temperature of the motor is 106.22°C at the end of the winding,which is within the normal temperature range;the maximum temperature of the permanent magnet reaches 72.2°C,which can effectively avoid the risk of high temperature demagnetization.In summary,this thesis comprehensively improves the torque density of the designed IHDDAFM and effectively reduces its torque ripple through multi-objective optimization,which has great reference significance for the direct drive integration of in-wheel direct drive motor and the development of AGV power system.