| Today,in 21st century,resource shortage and environmental pollution are two major challenges for human survival and development.Traditional vehicles consume a lot of resources,and at the same time,the emissions also cause pollution to the atmospheric environment.Electric vehicles are powered by electricity,which are economical,clean and pollution-free.Although the current technology is not mature,electric vehicles still have broad prospects for development.Electric drive system is the core and vitality of electric vehicle.The driving motor,which provides power is the key of the electric drive system of electric vehicle.In recent years,with the discovery and application of rare-earth permanent magnet materials,permanent magnet motor is developing with each passing day.The electric drive system with permanent magnet synchronous motor as the core is more and more applied to electric vehicles.However,Electric vehicle during driving has high requirement on the noise performance of the driving motor,so the research on vibration and noise of permanent magnet synchronous motor for electric vehicle is of great significance.As an effective measure to weaken the electromagnetic vibration and noise,rotor step skewing is widely adopted in the design of motors.Therefore,in this paper,the vibration and noise characteristics of permanent magnet synchronous motor considering rotor step skewing are analyzed,and the influence of rotor step skewing on the radial electromagnetic force,vibration and noise of the motor is summarized.The vibration and noise generated by the radial electromagnetic force of the motor is the main source of the vibration and noise of the motor.In this paper,firstly,the analytical expressions of radial electromagnetic force of permanent magnet synchronous motor considering rotor step skewing are derived by Maxwell stress equation.The influence of rotor step skewing on the radial electromagnetic force of permanent magnet synchronous motor is analyzed and summarized.And taking a permanent magnet synchronous motor for electric vehicle as an example,combined with electromagnetic finite element analysis software,the radial electromagnetic force on the stator tooth surface of the motor is calculated by Fourier decomposition and spectrum analysis method,and the correctness of the analytical expression is verified.Secondly,the modal analysis of the motor is carried out,and the natural frequencies and modal shapes of the motor are obtained,and the possibility of structural resonance of the motor is preliminarily evaluated.Then,the electromagnetic vibration and noise simulation analysis of the motor is carried out based on multi-physical field joint simulation platform,and the influence of rotor step skewing on the vibration and noise of the motor is summarized.Rotor step skewing suppress the vibration and noise of the motor,at the same time,the electromagnetic performance of the motor is reduced.Electromagnetic simulations with different skewed angles have been carried out,and the torque curves of different motors are obtained.Considering the influence on the noise and electromagnetic performance,the optimal design of skewed angle is given in this paper.Finally,the prototype is made and the noise experiment is carried out.By comparing the measured noise result of the prototype with the simulation result,the accuracy of the finite element simulation calculation is verified,and the correctness of the analysis is further proved.This study provides guidance for the design of low vibration and noise permanent magnet drive motors for electric vehicles. |
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