Design And Torque Performance Optimization Analysis Of Flat-wire Permanent Magnet Synchronous Motors For Electric Vehicles

Electric vehicle drive motors are developing towards high torque density,small size and low noise,and the penetration rate of flat wire winding type permanent magnet synchronous motors is also increasing rapidly in major automotive companies,and becoming a popular and trendy development of electric vehicle drive motors.The flatwire permanent magnet synchronous motor also has good noise,vibration and harshness(Noise,Vibration,Harshness,NVH),and NVH is closely related to torque ripple,for the flat wire motor torque ripple suppression is an urgent issue to deal with.Firstly,this paper designs a flat wire permanent magnet synchronous motor for electric vehicles with rated speed of 6000 rpm and power of 50 k W,designs the main dimensions and pole slot fits of the motor according to the performance index,determines different layers and dimensions of the flat wire motor by comparing AC copper consumption,and determines the rotor V-shaped structure by the change of straight shaft inductance and convex pole ratio under different operating currents,and determines the electromagnetic performance of the designed motor by finite element analysis.The electromagnetic performance of the proposed motor is analyzed by finite elements to determine its reasonableness.Secondly,according to the mechanism of torque ripple,weakening measures are proposed and optimized from the stator side and rotor side,the stator side is firstly optimized by optimizing the width and height of stator slot and analyzing the slotting of stator teeth;the rotor side is optimized by segmenting the wrong pole to determine the best wrong pole angle under different rotor segments;meanwhile,the pole arc coefficient of rotor,the angle of V-shaped permanent magnet,the slotting of rotor surface and the use of uneven air gap are compared and analyzed.After optimization,the motor torque can be increased by 1N?m and the torque ripple can be reduced by 4%,which verifies the optimization effect of each scheme on the torque performance.Finally,the multi-parameter variable optimization of the torque ripple and torque performance of the flat wire permanent magnet synchronous motor is based on the response surface method.To reduce the torque ripple and improve the torque performance as the optimization target;set the sensitivity level according to the degree of influence of each parameter on the stator side and rotor side on the torque ripple and torque performance of the motor;considering the large difference in sensitivity of different parameters to the optimization target,carry out the hierarchical optimization on the basis of response surface.The simulation results shows that the torque and torque ripple meet the constraint conditions,and the layered optimization further increases torque by nearly 1.1N?m and reduces torque pulsation by 1.2%.Moreover,the motor efficiency map,external characteristic curve and no-load counter-electromotive force are greatly improved,which verifies the effectiveness of the hierarchical optimization of the response surface and further improves the motor performance.