Research On Noise Of Electric Vehicle Drive Motor Under Multiple Working Conditions

As the power source of the electric vehicle,the driving motor has a large vibration and noise during operation,which affects the ride comfort.The radial electromagnetic force generated by the electromagnetic field of the motor is the main cause of vibration and noise.At present,the research on the electromagnetic vibration noise caused by the electromagnetic force inside the permanent magnet synchronous motor needs to be strengthened.Based on the permanent magnet synchronous motor of urban electric bus,this paper studies the vibration and noise of the motor and proposes measures to reduce the vibration and noise of the motor.The main research contents of this paper are summarized as followings:Firstly,the operating characteristics of the drive motor and the theory of vibration and noise are analyzed.Based on the drive motor of electric bus,the working performance of permanent magnet synchronous motor is studied.According to the operating conditions of the passenger car,the working conditions studied in this paper,namely starting,acceleration and deceleration conditions,were selected.Combined with the theory of electromagnetic field,the vibration and noise theory of the motor is studied.Thirdly,the modal analysis of the motor structure was carried out.For the structure of the motor and the structural model of the whole machine,the finite element modal analysis is performed by ANSYS simulation software to obtain the mode shape of each structure and the corresponding modal frequency.Secondly,for the permanent magnet synchronous motor,the radial electromagnetic force of the electric passenger car under the starting,acceleration and deceleration conditions is simulated and analyzed.Starting from the air gap magnetic field of the motor,the radial electromagnetic force per unit area of the inner surface of the stator tooth is obtained according to Maxwell's equation,and the radial electromagnetic force harmonic is obtained by Fourier transform.The finite element electromagnetic simulation is used to start and accelerate.The radial electromagnetic force of the deceleration condition.Finally,the harmonic response analysis is used to calculate the vibration displacement and vibration speed of the motor,and noise reduction measures are proposed.The electromagnetic noise sound pressure level is calculated by the vibration speed and compared with the vibration displacement calculation result.The influence of the frequency amplitude of the natural frequency of the motor structure and the radial electromagnetic force density distribution on the vibration and noise of the motor is analyzed.Through the vibration and displacement simulation analysis of the motor,the vibration displacement increases with the increase of the motor speed under the starting and acceleration conditions,and the radial electromagnetic force in the acceleration condition has more impact on the motor vibration,and the noise is also formed Larger.Under deceleration conditions,the overall vibration displacement is less than the acceleration condition,and the vibration displacement is decreasing.Based on the study of electromagnetic vibration and noise,the peak frequency of electromagnetic force is not in the same frequency range as the system structure frequency by changing the input current frequency or improving the structure frequency of the motor controller,thus effectively reducing the electromagnetic noise.