Research On Rotor Optimization Of Permanent Magnet Synchronous Motor To Suppress Electromagnetic Vibration And Noise

With the improvement of consumption level,people’s requirements for car comfort are increasing gradually.Good vibration and noise performance has become an indispensable indicator for a high-quality car.Compared with the traditional fuel engine drive,the vibration noise level of the electric drive car is lower,but its electromagnetic noise has poor sound quality,often manifested as high-frequency howling,which is easy to cause people’s discomfort.Therefore the calculation and optimization of electromagnetic vibration and noise is of great theoretical and engineering value in the motor design stage.The electromagnetic vibration noise is mainly derived from the radial electromagnetic force generated by the stator and rotor magnetic field.To suppress the electromagnetic vibration noise,the radial electromagnetic force needs to be weakened,especially the low-order radial electromagnetic force,which plays a major role in electromagnetic vibration.In this paper,the rotor magnetic circuit of an interior permanent magnet synchronous motor for vehicles is optimized to improve the performance of electromagnetic vibration and noise by suppressing electromagnetic force on the basis of ensuring the electromagnetic performance.Firstly,starting with the mechanism of radial electromagnetic force generation,the spatial harmonic order and frequency distribution of radial electromagnetic force waves,as well as the characteristics of harmonic magnetic fields that generate these force wave components,are qualitatively deduced and analyzed.Then,the electromagnetic field finite element method is used to quantitatively calculate and analyze the magnetic field and radial electromagnetic force of an 8-pole 48-slot permanent magnet synchronous motor.The theoretical analysis and simulation results show that,the main components of low-order radial electromagnetic force wave are mainly generated by the characteristic order magnetic density harmonics: the 3rd,5th,7th,and 9th harmonics and the first and second order tooth harmonics.This points out the direction for the optimization of rotor to weaken the electromagnetic force and suppress the vibration and noise.Subsequently,in this paper,based on the new parametric modeling definition method,the optimization goal,optimization parameters,optimization sequence are determined,the internal penalty function method is introduced and magnetic steel structures are optimized.The results show that the electromagnetic performance of the prototype after optimization is improved,the characteristic order magnetic density harmonics and 0,8th-order low-order electromagnetic forces are significantly suppressed.Finally,a three-dimensional calculation model of the structural field is built to compare the vibration and noise conditions of the prototype before and after optimization,on the basis of the modal calculation.The results show that,under rated operating conditions,the vibration and noise response values are significantly reduced after optimization,under the condition of multi-speed operation.The results prove that the optimization of the rotor structure has a significant effect on suppressing the electromagnetic vibration noise of the motor.The theoretical analysis and optimization methods in this paper are of theoretical value and engineering significance for the optimization of the rotor structure to suppress the electromagnetic force and improve the performance of vibration and noise.It can be used for reference for other types of motors to suppress electromagnetic vibration and noise.