归一化复域能量算子解调及其在转子碰摩故障诊断中的应用

Normalized Complex Teager Energy Operator Demodulation Method and Its Application to Rotor Rub-impact Fault Diagnosis

归一化希尔伯特变换(Normalized Hilbert transform,NHT)解调采用经验AM-FM分解实现信号的包络信号(即瞬时幅值)和纯调频信号的分离,再对纯调频信号进行希尔伯特变换提取瞬时频率。与直接希尔伯特变换解调比较,归一化希尔伯特变换的解调效果有较大提高。然而,研究发现,经验AM-FM分解得到的纯调频信号可能存在易导致负频率出现的骑波,并且由于归一化希尔伯特变换求取瞬时频率仍采用希尔伯特变换,则不可避免地在端点处产生振荡。针对归一化希尔伯特变换解调存在的问题,提出可以消除骑波的改进的经验AM-FM分解以及基于复域能量算子的纯调频信号的瞬时频率估计,并在此基础之上进一步提出一种新的信号解调方法——归一化复域能量算子(Normalized complex Teager energy operator,NCTEO)解调,采用改进的经验AM-FM分解提取单分量信号的瞬时幅值,再用基于复域能量算子的瞬时频率估计对纯调频信号进行解调提取瞬时频率。通过仿真试验以及转子早期碰摩故障诊断的应用实例验证了归一化复域能量算子解调的优越性和有效性。

Normalized Hilbert transform （NHT） demodulation method introduces an empirical AM-FM decomposition to a monocomponent signal, achieving a separation of the envelope signal （i.e., instantaneous amplitude） and the FM signal, then instantaneous frequency can be directly extracted through Hilbert transform to the FM signal. Compared with direct HT method, NHT method could gain a better demodulation performance. However, studies show that the FM signal results from empirical AM-FM decomposition may contain riding waves, which are prone to negative frequency. Moreover, since Hilbert transform is still used, oscillations will inevitably occur near endpoints of the obtained instantaneous frequency by NHT method. Aiming at the drawbacks of NHT method, an improved empirical AM-FM decomposition for eliminating riding waves and an instantaneous frequency estimate based on complex Teager energy operator （CTEO） for the FM signal are presented, respectively. Furthermore, a new signal demodulation method named normalized complex Teager energy operator （NCTEO） demodulation is proposed, in which the improved empirical AM-FM decomposition is applied to a monocomponent signal to extract instantaneous amplitude, and NCTEO method is applied to the resulting FM signal to extract instantaneous frequency. Simulated signals experiments and early rub-impact fault signals analysis of rotor system verify the excellence and effectiveness of NCTEO method.