Abstract
Whine noise from the electric powertrain system of electric vehicles, including electromagnetic noise and gear-meshing noise, significantly affects vehicle comfort and has been getting growing concern. In order to identify and avoid whine problems as early as possible in the powertrain development process, this paper presents a vibration and noise simulation methodology for the electric powertrain system of vehicles under speed-varying operating conditions. The electromagnetic forces on the stator teeth of the motor and the bearing forces on the gearbox for several constant-speed operating conditions are obtained first by electromagnetic field simulation and multi-body dynamic simulation, respectively. Order forces for the speed-varying operating condition are generated by interpolation between the obtained forces, before they are applied on the mechanical model whose natural modes have been calibrated in advance by tested modes. The whine noise radiated from the powertrain is then obtained based on acoustic boundary element analysis. The simulated bearing forces indicate that the overlooking of the motor torque ripple does not result in significant loss in simulation accuracy of electromagnetic noise. The simulation results and tested data show good consistency, with the relative frequency deviation of local peaks being less than 8% and the error of the average sound pressure level (SPL) being mostly below 10 dB (A).
Highlights
Whine noise from the electric powertrain system of electric vehicles, including electromagnetic noise and gear-meshing noise, significantly affects vehicle comfort and has been getting growing concern
In order to identify and avoid whine problems as early as possible in the powertrain development process, this paper presents a vibration and noise simulation methodology for the electric powertrain system of vehicles under speed-varying operating conditions. e electromagnetic forces on the stator teeth of the motor and the bearing forces on the gearbox for several constant-speed operating conditions are obtained first by electromagnetic field simulation and multi-body dynamic simulation, respectively
Order forces for the speed-varying operating condition are generated by interpolation between the obtained forces, before they are applied on the mechanical model whose natural modes have been calibrated in advance by tested modes. e whine noise radiated from the powertrain is obtained based on acoustic boundary element analysis. e simulated bearing forces indicate that the overlooking of the motor torque ripple does not result in significant loss in simulation accuracy of electromagnetic noise. e simulation results and tested data show good consistency, with the relative frequency deviation of local peaks being less than 8% and the error of the average sound pressure level (SPL) being mostly below 10 dB (A)
Summary
When the electric vehicle is speeding up or decelerating, harmonic excitation forces with order characteristics in the electric drive system excite the powertrain housing to vibrate and radiate noise into the air. ere are two main types of harmonic excitation forces responsible for whine noise, i.e., electromagnetic excitation loads and gear-meshing forces. When the electric vehicle is speeding up or decelerating, harmonic excitation forces with order characteristics in the electric drive system excite the powertrain housing to vibrate and radiate noise into the air. E former acts on the stator structure directly, while the latter acts on the rotor shaft which transmits the pulsating harmonic load to the powertrain housing through the bearings of the drive system [11]. E time-domain forces on the bearings under the constant-speed conditions are obtained through multi-body dynamic simulation. E normal vibration velocity of the powertrain housing is obtained by using FE analysis by applying the order forces onto the structural model. The modeling accuracy of the structural modes determines the accuracy of the multi-body dynamic simulation, which means it will affect the computed results of the bearing forces. Acoustic FEM analysis Figure 1: Process of vibration and sound analysis
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