Magnetic Field Analysis And Optimal Design Of Surface Mounted Permanent Magnet Synchronous Wheel Motor

The in-wheel motor directly drives the smart rail vehicle,simplifying the mechanical transmission structure,making the vehicle more efficient in space,facilitating the adoption of multiple new energy technologies.Therefore,it is very important to develop in-wheel motors with high electromagnetic performance and high reliability.The improvement of motor performance needs to be achieved by optimizing the motor structure.It mainly studies the PMSM’s structure design,electromagnetic magnetic field calculation,and multi-physics coupling analysis:(1)According to the structure and operating performance requirements of the autonomous rail rapid transit developed by CRRC,the SPMSM with a rated power of 30 k W,a rated speed of 1187 rpm,and a rated torque of 241N·m is preliminarily designed using the magnetic circuit method.In the finite element software,the stator yoke and permanent magnets of SPMSM are simulated and optimized.The optimal parameters of the inner rotor SPMSM are obtained,and its no-load performance and load performance are analyzed.(2)Aiming at the problems of large electromagnetic torque fluctuation and permanent magnet eddy current loss in SPMSM with high power density,the Halbach partial segmented structure is proposed.The permanent magnet adoptes the Halbach magnetization method.Each magnetic pole is divided into three segments,and the main magnetic pole adopts a partial segment structure.The boundary magnetic pole and the main magnetic pole have different widths and thicknesses.It is expanded into two types,namely,Hat-,T-Halbach partial segmented PMSM.The solution domain is divided into four regions: slot body,notch,air gap,and permanent magnet.The subdomain model method is used to derive the analytical expressions of the no-load and load air gap magnetic field distribution,cogging torque and electromagnetic torque of SPMSM under two-dimensional polar coordinates.The analytical expression of the moment and the analytical solution is compared with the finite element simulation result,and the correctness of the analytical method is verified.(3)A 10-pole,12-slot Halbach partial segmented PMSM finite element simulation model is established in Maxwell.The permanent magnet structure of the Halbach partial segmented PMSM is simulated and optimized in an electromagnetic field.The comparison and analysis of the electromagnetic performance of the optimized PMSM with Hat-,T-Halbach partial segmented structure and related structures was carried out to verify the superiority of the performance of the Halbach partial segmented PMSM.(4)In order to verify the optimization effect of Hat-and T-Halbach partially segmented PMSM,the steady-state temperature distribution,permanent magnet equivalent stress and total deformation of Hat-and T-Halbach partial segmented PMSM are simulated in the temperature field and stress field.According to the simulation results of electromagnetic field,temperature field and stress field,the advantages and suitable applications of Hat-and T-Halbach partial segmented PMSM are obtained.