Comprehensive Optimization Of Operation And Vibration Performance Of New Energy Vehicle Driven Motor

In recent years,the development of automobile industry is faced with the problems of energy shortage and environmental pollution,and the development of new energy vehicles is the only way to solve these.For new energy vehicles,the key of the drive system is the driven motor,which determines the performance of new energy vehicles directly.High power density,high output torque,high efficiency and low loss are the goals pursued by electrical engineers all the time,however,it comes with the problem of greater vibration and noise.There is always a contradiction between operation performance and vibration and noise,therefore,the performance of operation and vibration of a driven motor for new energy vehicles is comprehensively optimized in this paper.Firstly,the electromagnetic model of permanent magnet synchronous motor is established in2D by Maxwell,and the correctness of the model is verified by the test data.The operation performance and the radial electromagnetic force of the motor at the speed of 3000 r/min and the input current of 250A are calculated and analyzed.It is found that the amplitude of the radial electromagnetic force is mainly distributed at the frequency of 400Hz（8f₁）,800Hz（16f₁）,1200Hz（24f₁）,1600Hz（32f₁）and 2400Hz（48f₁）.Secondly,the three-dimensional finite element model of stator core of the motor is established,and its natural mode is calculated.The natural frequencies of the stator core of the first four modes are simulated and analyzed.The vibration modes are ellipse,triangle and quadrilateral,and the rationality of the model is verified by comparison.Further,the vibration response characteristics of the stator core of the motor is calculated by the magnetic solid coupling method of the motor.The results show that the stator core vibration displacement at the frequency of2400Hz in the X axis direction is the largest,and the vibration displacement in the X axis direction is the largest at the frequency of 1200Hz.Then,the influence of structural parameters,such as air gap length,thickness of permanent magnet,distance between magnetic isolation bridges and width of stator slot,the output torque,torque ripple and the amplitude of 1200Hz and 2400Hz radial electromagnetic force are studied by the two-dimensional finite element model.Furthermore,a BP neural network is established for the correlation between the structural parameters of the motor and its performance,radial electromagnetic force.The average relative error of the network prediction is less than 5%,which has a high prediction accuracy.Finally,under the framework of multi-objective particle swarm optimization algorithm,the operation and vibration performance of the permanent magnet synchronous motor are comprehensively optimized by taking the length of air gap,the thickness of permanent magnet,the spacing of magnetic separation bridge and the width of stator slot as optimization parameters,and the motor output torque,torque ripple,the amplitude of 1200Hz and 2400Hz radial electromagnetic force as optimization objectives.Compared with the original machine,the output torque of the optimized motor is increased by 4N.m,the torque ripple is reduced by 49%,the radial electromagnetic force amplitude of 1200Hz and 2400Hz are reduced by 35%and 64.3%.It can be seen that operation and vibration performance of the optimized motor have been significantly improved.In this paper,the influence of the motor structure parameters on the operation performance and vibration noise is studied.A method for comprehensive optimization of motor performance and vibration characteristics is proposed combining with the particle swarm optimization algorithm and BP neural network model.This method has important practical engineering significance.