Research On Active Noise Control In Vehicle Based On Engine Excitation

With the increasing concern of consumers for automobile economy and ride comfort,improving cab noise environment has become the main means for domestic and foreign automobile manufacturers to compete to increase market share.The traditional noise control technology is mainly passive control,including sound insulation,muffling and sound absorption.It has better effect in dealing with medium and high frequency noise,but it has poor effect in controlling low frequency noise caused by vehicle body vibration and radiation under road or engine excitation.Compared with the passive control technology,the active control technology can effectively reduce the low-frequency noise of the car room.In this paper,the simulation analysis and active noise control of a domestic vehicle from engine-driven interior noise are studied,which has clear engineering significance and application background.Firstly,the interior noise and engine noise are analyzed theoretically.It is concluded that engine noise is the main component of interior noise except road noise.There is a specific relationship between the main frequency of interior noise and engine speed.It provides a theoretical basis for collecting the data of vibration and noise generated by engine excitation of a domestic vehicle,and using LMS Virtual LAB to carry out acoustic simulation analysis.Secondly,aiming at the problem that traditional FXLMS algorithms rely more on secondary channel mathematical model,this paper uses synchronous disturbance random approximation(SPSA)algorithm and improves it.The FXLMS algorithm is compared with the improved algorithm through Matlab simulation experiments.The experimental results show that the improved algorithm estimates the control variables directly,so the control sequence can be obtained directly,which reduces the computational complexity and improves the response speed of the system.The improved algorithm has the advantages of fast convergence speed and high operation efficiency.It effectively solves the problems of high dimension,slow convergence and complex structure of the traditional algorithm.The computational speed and storage space requirements of the controller are greatly reduced,which is of great significance in engineering.Finally,a multi-channel active noise control system laboratory test platform is built by using high-speed digital processor as controller,primary and secondary loudspeakers,DCregulated power supply,power amplifier,microphone and other devices.Experiments on active control of single-frequency noise and multi-frequency noise in vehicle target frequency region are carried out respectively.The experimental results show that the maximum 9.6dB(A)noise reduction is achieved in the control of single-frequency noise and the maximum 11.2dB(A)noise reduction is achieved in the control of multi-frequency noise.The experimental analysis verifies the design of active noise by comparing the time-domain and frequency-domain diagrams.The control system can achieve stable noise control.