Design And Research Of Permanent Magnet Synchronous Motor With Hairpin Winding For Electric Vehicle

The energy crisis and environmental pollution have severely challenged the traditional fuel automobile industry,and new energy electric vehicles have been attracted widely attention due to their energy-saving and high-efficiency characteristics.As the core component of electric vehicle,high-performance drive motor has always been the focus of new energy vehicle research.With its many advantages,permanent magnet synchronous motors have been widely used in electric vehicles.However,the traditional permanent magnet synchronous motor with copper wire winding has been difficult to meet the higher requirements of new energy vehicles for higher peak power density level of the driving motor.The hairpin winding provides a new way to further improve the power density of the motor.At present,the permanent magnet synchronous motor with hairpin winding is gradually becoming a research focus of the drive motor for new energy electric vehicles.According to the characteristics and design indicators of the permanent magnet synchronous motor with hairpin winding,the stator slot type,winding layer number and rotor magnetic pole structure of motor were confirmed.The specific parameters were determined based on finite element method.The initial electromagnetic design of a three-phase 12-pole 72 slot permanent magnet synchronous motor with hairpin winding was completed.The rationality of the preliminary design was proved by the simulation analysis of magnetic field distribution,cogging torque,no-load back potential,air gap flux density and output torque.Taking the preliminarily design of the motor as the research object,the cogging torque and torque ripple were studied.The influences of linear and V-type step-skewed pole modes on the cogging torque and torque ripple were analyzed,and determined the optimal design of rotor with two step-skewed pole.In order to improve the sinusoidal of motor air gap magnetic field,and to reduce the torque ripple and improve the output torque were considered as optimization objectives.Taguchi algorithm was used to optimize the rotor auxiliary groove.In order to verify the effectiveness of the optimal design of the motor,the output performance of the motor and the mechanical strength of the rotor were checked.In order to calculate the electromagnetic vibration and noise level of the motor,the spatial order and frequency order of the radial electromagnetic force which have great influence on the electromagnetic vibration and noise of the motor were analyzed,and the correctness of theoretical analysis was verified by the finite element simulation results.The finite element method was used to calculate the modal and natural frequencies of the system composed of the stator core,the stator core,the windings and the casing,and the possibility of the motor resonance was analyzed.Through the coupling of electromagnetic,mechanical and noise fields,based on harmonic response analysis method,the vibration of the outer surface of the motor shell and the noise distribution in the air domain near the motor were calculated.The results show that the motor has low electromagnetic vibration and noise level,which can meet the design requirements.