Active Noise Control Method Based On EWT And Recursive Chebyshev Filter

The traditional passive noise control method has some disadvantages in dealing with low-frequency noise,such as large equipment volume and high cost.At present,the Active Noise Control(ANC)technology is mainly used to control the low frequency noise.However,there exists nonlinear disturbances in the primary path and secondary path in practice.Moreover,the noise exhibits non-stationary characteristics.Based on third-order Chebyshev filter and Empirical Wavelet Transform(EWT),this paper has in-depth study on control method of the non-stationary noise under the nonlinear path.The specific content and results are as follows:(1)To solve the problem of high-order nonlinear path,an ANC algorithm based on adaptive recursive third-order Chebyshev nonlinear(RTOCN)filter is proposed.In the method,the recursive structure is introduced and then an improved third-order Chebyshev nonlinear filter is derived.Based on RTOCN filter,the reference noise and feedback noise are extended respectively.Besides,the weight coefficients of RTOCN filter are updated by multi-channel FELMS algorithm.In conclusion,this method can eliminate the influence of high-order harmonics generated by nonlinear primary and secondary path on the noise reduction of ANC system.(2)In view of the high computational complexity of extended cross-terms in RTOCN filter,the diagonal structure is designed and presented by analyzing the delay characteristics of multi-channel extensions.Channel reduction strategy is introduced to select the main diagonal channels to optimize the number of extended cross-terms,and then a control algorithm based on channel-reduced diagonal RTOCN(CRD-RTOCN)is established.In addition,the computational complexity of the algorithm is investigated in detail.The simulation results show that compared with CEMD-SOCFXLMS,TOVFELMS,FSLMS and RFSLMS algorithms,the proposed algorithm has the highest noise reduction.(3)Aiming at the non-stationarity of the reference noise in nonlinear ANC control system,a control algorithm based on EWT and CRD-RTOCN is proposed.Combined with the analysis of nonstationary noise characteristics,the EWT technology is introduced to adaptively decompose the reference noise.Due to the orthogonal decomposition characteristic,the decomposed noise components become more stable and easier to control.Afterwards each noise component is extended by CRD-RTOCN to compensate for the potential high-order nonlinear distortion.Additionally,the computational complexity of the algorithm is discussed in detail.Simulations have been carried out to show that proposed algorithm outperforms TD-FXLMS,DWT-TD-FXLMS and CEMD-SOC-FXLMS algorithms to control non-stationary noise and compensate for nonlinear distortion.