Research On Active Noise Control System In Vehicle Based On Broad-Narrow Hybrid Control Algorithm

The low-frequency noise caused by the power system and road excitation in the vehicle has become one of the NVH(Noise,Vibration & Harshness)problems with the highest perception rate for passengers.It has received widespread attention from vehicle companies and research institutes.Active noise control has been verified to become a core technology in the NVH field.Interior noise has typical broad-narrow hybrid characteristics.Classical vehicle active noise control algorithms usually only focus on individual control of narrowband noise or broadband noise,and rarely consider the cooperative control of the broad-narrow hybrid noise.Therefore,in order to achieve effective suppression of broadband and narrowband noise at the same time,this paper focuses on research the vehicle ANC(Active Noise Control)technology based on the broad-narrow hybrid control algorithm.Based on the performance evaluation of the existing ANC algorithms,this paper proposes an improved broad-narrow hybrid control algorithm.The proposed algorithm includes the signal separation subsystem with acoustic feedback cancellation,the narrowband ANC subsystem configured with the notch delay LMS algorithm,and the broadband ANC subsystem configured with the clipped normalized FxLMS algorithm.Among them,the acoustic feedback cancellation technology is introduced in the signal separation subsystem,which can effectively eliminate the feedback sound collected by the reference microphone.The notch delay LMS algorithm is adopted as the narrowband ANC algorithm,in which the convolution operation between the secondary path coefficients and the reference signals is canceled,which greatly reduces the computational complexity of the algorithm.Simultaneously,the clipped normalized FxLMS(Th-NFxLMS)algorithm is developed and extended,which can guarantee the stability of the system under impulsive noise with high sound power.In order to verify the comprehensive performance of the proposed algorithm,a broad-narrow hybrid active noise control simulation model based on MATLAB/Simulink platform is established in this paper.The effectiveness of the proposed hybrid algorithm is verified through the simulation assess of the simulated broad-narrow hybrid noise and the acquisition noise from a real vehicle.Secondly,to solve the problem of acoustic path identification in ANC,this paper introduced a self-developed ANC application software based on MATLAB/GUI platform for the identification and analysis of the secondary channel and acoustic feedback channel.This software employed amplitude mean square coherence analysis(MSC)and power spectrum Density calibration method(PSD)for accurate analysis of estimated path coefficient,which can more intuitively reflect the identification accuracy under different frequency components.Finally,based on the developed ANC hardware system,an offline active noise reduction test for the collected interior noise was performed in the laboratory scenario.The test results showed that the proposed ANC system can reduce the engine second-order and fourth-order noise effectively.Besides,broadband random noise has a significant decrease in performance.In particular,the engine order noise is reduced by up to 16.6 dB after active noise reduction,the linear total sound pressure level is improved by 6.0-9.9 dB,and the A-weighted total sound pressure level is improved by 3.0-7.1 dB(A).Besides,to better verify the performance of the ANC system in the active control of real vehicle noise,this article carried out an active control experiment in the real vehicle under the 2100 r/min neutral steady condition,and the 70 km/h uniform driving conditions.The results showed that the reduction effect of engine order noise is obvious,the amount of noise reduction is 9.6-14.1 dB.At the same time,the total sound pressure level of the target noise in the vehicle has improved slightly,among which the linear total sound pressure level has been reduced by up to 4.3 dB,The A-weighted total sound pressure level is reduced by up to 2.1 dB(A).In summary,the broad-narrow hybrid active noise algorithm proposed in this paper has a certain control effect on interior noise and can be regarded as an available reference for active control of vehicles.