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提出了一种基于移频技术的短时傅里叶变换阶比分析算法.该算法利用傅里叶变换在频域的卷积性质,对原始信号在时域乘以e-j2πfit使fi的频谱能量搬迁到零频处,按一定的频率间隔改变fi就可以在零频处得到其他频率的频谱能量,以此来提高短时傅里叶变换在时频分析中的频率分辨率.然后在时频面上进行局部阈值降噪,同时跟踪转速的变化,最终应用到变速机械的阶比分析中.与短时傅里叶变换分析结果对比表明,本文方法可以更加准确地跟踪到实际的转速.实际降速过程中轴承信号利用本文方法进行阶比分析,成功提取到轴承的故障特征频率.
This paper proposes a frequency-dependent short-time Fourier transform order analysis algorithm which uses the convolution property of the Fourier transform in the frequency domain to multiply the original signal in the time domain by e-j2πfit to make the spectrum of fi When the energy is moved to the zero frequency, the frequency energy of other frequencies can be obtained at zero frequency by changing fi at a certain frequency interval to improve the frequency resolution of the short-time Fourier transform in the time-frequency analysis. The local threshold noise reduction and the change of speed are tracked at the same time, and finally applied to the order analysis of variable speed machinery.The comparison with the result of short time Fourier transform shows that this method can track the actual speed more accurately. In the process of actual deceleration, bearing signal is analyzed by order method of this paper, and the fault characteristic frequency of bearing is successfully extracted.