| Car noise easily causes driver and passengers to be fret and fatigue,and affects the ride comfort.With the improvement of consumption level,the consumers have higher expectations on the ride comfort.At the same time,new regulations also puts forward more strict requirements on automotive noise control.The pursuit of excellent NVH performance has become the consensus of the domestic automotive industry.It is difficult to effectively suppress the low frequency noise in the vehicle by adopting the traditional noise reduction measures.In recent years,the highly anticipated application of active noise control technology in automobiles is expected to break this predicament.However,the current domestic research in this area is still mostly limited to the active control of single-channel noise,which can not meet the noise reduction requirements of multiple locations in the vehicle at the same time.Therefore,if we want to apply this technology to a car,we need to solve the problem of active noise reduction at multiple locations in the car first.In this paper,the causes of engine-related noise in automotive vehicles and the derivation of related algorithms are analyzed.Combining with the researches on active control technology of multi-channel noise in recent years and the existing research experiences of our group,a multi-channel active noise control scheme for synthesizing filter reference signals based on engine speed to eliminate engine order noise in vehicles is proposed.The hardware and software design of the control system is completed by using DSP as the master chip.Finally,the controller prototype is used for the hardware in the loop test and real vehicle test to verify the active noise reduction effect of the multi-channel control system.The article research conclusions are listed as follows:First of all,the control scheme of multi-channel active noise control system in the vehicle is determined.By comparing various algorithms,it is decided to use LMS algorithm and multi-channel Fx LMS algorithm to accomplish secondary path modeling and active noise reduction of multi-channel control system respectively.Secondly,the cause of the noise in the vehicle related to the engine is analyzed,and the method of extracting the frequency of the order noise is obtained according to its relationship with the speed.In order to effectively control multi-channel multi-frequency noise,a multi-channel multi-frequency notch filter is constructed by using a plurality of parallel notch filters.simultaneously,the multi-channel multi-frequency adaptive notch algorithm has been completed.Then,the modeling and simulation of secondary channel estimation and active control of multi-frequency noise of multi-channel system are completed by using Matlab/ Simulink,and good noise canceling effect is achieved.The effectiveness of multi-channel multi-frequency adaptive notch filtering algorithm and the feasibility has been verified.Then,using the DSP chip as the main control unit,the PCB circuit board was designed based on the completion of each module and the selection of electroacoustic devices,and the controller prototype was developed.The CCS development environment was used to compile and debug the control system software code.Finally,under the different loudspeaker and microphone layout schemes,the controller noise reduction test was completed by using programmed controller prototype.By comparing the test results under different deployment scenarios,the optimal deployment scheme was selected and the establishment of a multi-channel active noise control system in the vehicle was completed.Finally,using the built system to test in the actual vehicle.In the selected two vehicle operating conditions,the noise reduction of the control system for the peak frequency and the total sound pressure level reached 6.7 dB(A)~35.6 dB(A)and 4.3 dB(A)~9.8 dB(A)respectively,and the noise in the car is also effectively controlled under the acceleration condition. |
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