Research On Vehicle Interior Active Noise Control Technology Based On FXLMS Algorithm

Now,with the rising national automotive consumer automobile fuel economy performance and comfort of riding concern,improve vehicle NVH(Noise Vibration& Harshness)performance has become the main means of domestic and foreign automobile manufacturers competing to increase market share.In the car low-frequency noise components,the engine noise is usually dominated.Engine noise usually presents as a direct relationship with the engine speed of low-frequency characteristics of the car's acoustic environment caused a great negative impact.The traditional passive noise reduction measures for the low-frequency noise control memory is poor,such as sound insulation,sound absorption and other measures of passive noise reduction measures only in the noise of the high frequency section has a better protective effect.In this paper,the active noise control system of the filter-X minimum mean square(FXLMS)algorithm is simulated by using the feedforward noise active control system with engine speed signal as the input of low frequency noise,for turning second order noise in the vehicle,the test validation is completed as well.The main work is as follows:First,the interior noise and engine noise are analyzed,and among other results vehicle road excitation frequency noise outside the engine noise as a main component.The specific relationship between the frequency of the main peak in the vehicle noise and the engine speed was summarized.It provides a theoretical basis for the active noise control of the engine second order noise in the vehicle based on the method of synthesizing the engine speed signal as the reference signal of the control system.Secondly,the LMS algorithm and the FXLMS algorithm are studied theoretically.Based on the offline path model of FXLMS algorithm,the vehicle noise is simulated in MATLAB.The simulation and contrast study is carried out which aiming at the different filter length,the selection of convergence step and the control system of different speed signal input.The necessity of choosing the filter length and the convergence step is analyzed by the simulation results.It is proved that the method ofsynthesizing the reference input signal by the engine speed is feasible.Furthermore,noise active control system based on FXLMS algorithm is designed,single-channel and multi-channel feedforward noise active control system test model are built based on real vehicle.Respectively,experiment studies are carried out under different test conditions for single-channel and multi-channel noise control system.The experimental results show that the designed single-channel noise active control system has an average reduction of 8dB~ 10dB;The noise reduction that achieved is about 15 dB when applying multi-channel system in the car fixed speed cases at the front row of car.And the multi-channel system achieved an average of 6dB noise reduction in the front row in fast acceleration condition of the car.