应用自适应带宽信号的BS-EMD混叠消除

A study on the method for eliminating mode mixing in B-spline empirical mode decomposition based on adaptive bandwidth constrained signal

经验模态分解(Empirical Mode Decomposition,EMD)存在的模态混叠现象严重影响了其应用效果,成为制约其在工程中推广应用的一个重要难题。在总结引起模态混叠的主要原因及分析模态混叠产生机理的基础上,借鉴高频谐波加入法(High Frequency Harmonic Added EMD,HFHA-EMD)原理并对高频谐波信号的构造进行改进,提出了一种应用自适应带宽信号的B样条EMD(B-Spline EMD,BS-EMD)模态混叠消除方法。该方法利用EMD的二进带通滤波特性和总是先分离高频分量的特点,根据被分析信号的BS-EMD得到的第一个IMF分量确定带宽限制频率和带宽限制幅值,从而构造出自适应带宽限制信号。通过在原始信号中添加自适应带宽限制信号来改变EMD带通滤波器的中心频率,再进行BS-EMD分解消除模态混叠。与EMD、BS-EMD进行对比分析,验证了该方法的优越性。与HFHA-EMD的对比仿真分析表明,两种方法都可以有效消除模态混叠现象,但是该方法在构造自适应带宽限制信号上更加明确可行,也更具自适应性。对含复杂异常事件的实际转子故障信号分析也验证了该方法在工程应用中的有效性和可行性。

Mode mixing is an inevitable problem in empirical mode decomposition(EMD)which significantly impacts its engineering application.The main reasons of causing mode mixing were summarized and the mechanism of mode mixing was analyzed.Inspired by high frequency harmonic added EMD(HFHA-EMD),an improved method for eliminating mode mixing in B-spline Empirical Mode Decomposition(BS-EMD)based on adaptive bandwidth constrained signal was proposed.According to the first IMF obtained by BS-EMD of the analyzed signal,the frequency and amplitude of the bandwidth constrained signal were determined.Thus,the adaptive bandwidth constrained signal was constructed.The central frequency of the EMD band pass filter was changed by adding the adaptive bandwidth constrained signal to the original signal.And then BS-EMD was performed to eliminate the mode mixing.Compared with EMD and BS-EMD,the effectiveness and feasibility of the proposed method was verified.Compared with HFHA-EMD,simulation results show that both two methods can avoid mode mixing correctly,but the proposed method was more explicit and feasible to construct the adaptive bandwidth constrained signal,and more adaptive.An actual fault rotor signal with complex abnormal events was also analyzed,and the effectiveness and feasibility in engineering were verified.