A model for the NVH analysis of electric vehicles based on electromechanical coupling vibration

With the rapid development of electric vehicle industry, the noise, vibration, and harshness (NVH) problem of electric vehicles is drawing more attention. In order to address this problem, experiments are conducted in this research on a test rig of electric drive system, and the results show that there are four evident frequencies on the sound spectrum. In order to investigate this phenomenon, a model of an electric drive system consisting of a transmission and motor system is developed. The torsional vibration acquired with this model also has four dominant frequencies, which are quite close to frequencies of experimental measurement. Further analysis based on this model shows that these four dominant frequencies are due to the fundamental, doubled, tripled frequency of gear meshing, and the 6th order current harmonics of the d-axis current, respectively. The results of the model analysis are quite close to experimental measurements, and the difference is less than 3%, indicating that this model can be applied to predict the NVH of electric vehicles. It seems that the vibration is affected not only by the mechanical parts but also by the current harmonics, and the model can be applied to analyse the mechanism of the NVH phenomena of electric vehicles.