Design And Torque Optimization Of Built-in Permanent Magnet Synchronous Hub Motor

IPMSM is widely used in traction locomotives and other industrial sector,because of its highly active and highly torque density.But the cogging effect is obvious,which leads to the cogging torque is too large,resulting in a larger torque ripple,mechanical oscillations and swishing in operation,which affect the manipulate of the system performance.Therefore,the research on cogging torque and torque ripple of IPMSM is emphasized.The main tasks to be completed are as follows:(1)Based on the permanent magnet synchronous motor(PMSM)for traction locomotive,this thesis describes the relationship between the dynamic performance of locomotive and the performance index of motor.According to the performance index of motor,a 30 k W IPMSM for locomotive driving is designed.Then,the mathematical model between the cogging torque and the parameters of stator and rotor is solved by energy method,which gives a theoretical foundation for cogging torque optimization.(2)Be directed against the problem of high cogging torque and torque ripple of traditional IPMSM,an asymmetric V-type pole offset rotor structure is proposed.In view of the winding function theory and equivalent magnetic circuit method,the expressions of stator and rotor magnetomotive force are derived respectively.Combined with Lorentz force law,the analytical model of torque ripple is obtained;three kinds of pole offset modes are compared.Finally,the torque ripple,and air gap flux density high-order harmonics of symmetrical v-pole,asymmetric v-pole and asymmetric v-pole are simulated and compared.(3)A much-target and much parameter majorization way combining parameter stratification and RSM is proposed.Taking cogging torque and torque pulsation as the optimization targets,five influencing parameters,such as pole embrace,stator slot width,permanent magnet land,axial length of rotor and magnetic pole interval magnetic bridge,are selected.Through parameter sensitivity analysis,the optimization alternating quantities are layered and affecting the high specific gravity were screened out.The torque of 30 k W asymmetric v-pole offset IPMSM is taken as the optimization objective.Layer by layer analysis based on integrated response surface method and parametric scansion.MMAS is used to solve the RSM equation,and the optimal parameters under the minimum cogging torque are defined.The electromagnetic performance and efficiency of the optimized motor are certificated by the finite element simulation experiment.