Optimization Design Of Torque Function And Electromagnetic Vibration Of Built-in PMSM

Compared with motors of the same power level,the built-in permanent magnet synchronous motor has the advantages of small size and simple structure,which is favored by different industries and is widely used in transportation,medical equipment,aerospace and other fields.In recent years,with China’s strong support for new energy vehicles,the use of built-in permanent magnet synchronous motors has become more common.However,the existence of large cogging torque and torque ripple will make the electromagnetic vibration and electromagnetic noise problems of the built-in permanent magnet synchronous motor more prominent,which seriously affects the stability and service life of the motor.It’s very important to study the vibration and noise problem of motors in depth,especially in some applications with high requirements for motor vibration quality.In this dissertation,a built-in permanent magnet synchronous motor with 6 poles and 36 slots is the main research object,and its original transient magnetic field is simulated and analyzed.Combined with the design parameters of the prototype,the finite element model of the two-dimensional space of the motor is established,and the magnetic density under different working conditions of the motor is analyzed harmonically.According to Maxwell’s tensor law,the transient electromagnetic force density of the motor with spatial changes during load operation is solved.It is found that the motor has problems such as excessive torque ripple,and the target to be optimized is analyzed and extracted.Then,we further explore the distribution and change law of the radial electromagnetic force density of the motor obtained by the previous calculation method.The vibration-absorbing structure design of the arc offset of the stator tooth was adopted,and combined with the response surface method（RSM）proposed in this paper.The multi-objective optimization algorithm combined with RSM and Taguchi method takes the thickness of the permanent magnet,the width of the magnetic isolation bridge,the distance from the radial axis of the permanent magnet to the outer arc of the rotor as optimization variables.The optimization goal is to increase the average output torque and reduce the torque ripple.The target tracking is realized by layering the target features,and the space formed by the self-restraint of the influencing target change factor is used to achieve the accurate target value and complete the optimization process of the parameter variables.The calculated radial electromagnetic force is used as the load condition during the coupled analysis,and added to the stator teeth of the 3D finite element model of the motor.The electromagnetic vibration and noise harmonic response analysis of the motor before and after optimization are analyzed,and the influence on the vibration and noise order of the motor is judged.The vibration analysis results are mapped to the noise module as a load excitation source.An acoustic field model is established to compare the noise waterfall diagram at the multi-rotation speed of the motor before and after optimization.This thesis verifies that the proposed optimization scheme can achieve the effect of reducing vibration and noise.