| Nowadays,the empire of electric vehicles is vast.The performance of permanent magnet materials is enhanced,and the application of permanent magnet motors is heating up,and related studies are emerging in an endless stream.With the rapid maturity of control technology and the emergence of high-performance permanent magnet materials,permanent magnet motor combined with the drive control system is widely used in the industry of new energy vehicles.Hence,the research on the analysis and optimization of electromagnetic vibration and noise of drive motor is nonnegligible in the new energy vehicle industry.In this paper,a 12-pole,48-slot electric vehicle is studied by using permanent magnet synchronous motor under the current drive of three-phase sine waves.The research content is mainly divided into the following parts:First,the generation of air-gap magnetic field and electromagnetic exciting force in automotive driving motor is analyzed and the discriminant method to identify the excitation source which produces the main vibration noise is indicated.Moreover,the low order mode of stator core,which is the core vibrating component in the motor is presented.The mechanism of production of the cogging torque and the ways of reducing cogging torque is explained in detail.Furthermore,this paper introduces the relationship between the vibration and noise generated by the electromagnetic excitation of the motor,with the relational expression of the sound intensity and the amplitude derived.Second,by using the Maxwell simulation,the oscillogram of air gap flux density and the electromagnetic density in the motor is drawn.Moreover,their radial components and tangential components are solved out by combining theory with formula derivation.Through the Fourier expansion,the distribution of the air gap flux density in each order is obtained.Through the spectrum analysis,the harmonic component of the electromagnetic exciting force on each section of the frequency is obtained.The simulation analysis of the motor stator core and the surrounding motor sheath is carried out to explore the existence of a resonance phenomenon.The electromagnetic analysis,harmonic response analysis and noise sound pressure analysis are carried out in the electromagnetism,vibration and noise in the coupled system of multi-physics field respectively,in which the comprehensive performance the research object is studied.Third,the distribution of electromagnetic vibration and noise generated by the driving motor after reducing the cog torque is analyzed.By changing the pole-arc coefficient and poles of different thicknesses,the fluctuation of the cogging torque is analyzed.Furthermore,the electromagnetic characteristics of the air gap flux density and the electromagnetic force density of the driving motor are obtained again through Fourier expansion and spectrum analysis respectively.The results show that the electromagnetic vibration and noise of the permanent magnet drive motor are greatly improved after the corresponding measures are taken to reduce the cogging torque by comparing with the harmonic frequency and amplitude difference before the cogging torque is reduced.Finally,under the premise of satisfying the driving performance conditions of permanent magnet synchronous motor drive,for the optimization objective of the sound pressure level of the noise field,poles of different thicknesses,the stator slot width and arc coefficient are applied and the optimization of the structural parameters in motor is carried out.The Kriging approximate model and multi-islands genetic algorithms are chosen as the research methods for target optimization.Based on the parameters after optimization,coupling simulation of the multi-physics field is carried out.The optimization result is compared with the radiation noise characteristics of the motor before optimization.Hence,the result verifies the accuracy and reliability of the construction of the approximate model and also ensures the feasibility of the optimization scheme. |
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