Research On Air-borne Noise Transfer Path Analysis Methods

With the popularity of electric vehicles,the focus of automotive NVH(Noise、Vibratio、Harshness)work has shifted from oil-fueled vehicles to electric vehicles.With the replacement of the engine by the electric motor,the vehicle vibration noise problem,which used to be dominated by structural-borne noise,has shifted to airborne noise.High-frequency airborne noise is also increasingly becoming a common concern for customers and automakers.(1)A transfer path analysis model containing only two airbornes were developed using two reverberation chambers and an anechoic chamber.The analysis were performed using Conventional Transfer Path Analysis(CTPA)method and Operational Transfer Path Analysis(OTPA)method.The results show that both the CTPA method and the OTPA method can calculate the contribution of the two airbornes,and the accuracy of the calculation results of the CTPA method is better.(2)The transfer path analysis model without considering intermediate points,the transfer path analysis model with nine intermediate points and the transfer path analysis model with sixteen intermediate points are proposed for the road noise problem of a electric vehicle,and the significance of establishing the model considering intermediate points is explained.Experiments were designed to study the model with nine intermediate points and the model with sixteen intermediate points,and the Frequency Response Functions were tested in the Semi-Anechoic Chamber,and the working condition data was tested in the Vehicle SemiAnechoic Room With 4×4 NVH Chassis Dyno.The CTPA method and OTPA method were used to analyze 60km/h,90km/h and 120km/h,respectively.The results show that the contribution of road noise to the target points in the vehicle can be calculated more accurately according to the proposed intermediate point transfer path analysis model.(3)Optimization measures are proposed for the poor accuracy of the OTPA method for the study of high-frequency airborne noise of electric vehicle road noise.Independent Component Analysis(ICA)was introduced to calculate the working condition data tested by the OTPA method to eliminate some of the effects of crosstalk to improve the accuracy of the OTPA method calculation.