Improved Park's Vector Method and its Application in Planetary Gearbox Fault Diagnosis

Motor current signature analysis is a commonly used fault diagnosis method of drive system parts. However, for some complex mechanical parts such as planetary gearbox, motor current signal is complicated, characteristic frequencies are hard to extract, and weak fault is difficult to identify. Thus, in this paper, an Im proved Park's vector method based on three-phase current signal analysis is proposed. The analytic signal is constructed by conducting Park transform. The instantaneous amplitude and the instantaneous frequency, which contain modulated characteristic frequencies, can be calculated according to the analytic signal. Fault characteristic frequencies are extracted by the spectral analysis of the instantaneous amplitude and the instantaneous frequency, and automatic fault diagnosis of the gearbox is accomplished by the spectral indexes. The simulation result shows that, compared with traditional planetary gearbox signal analysis method, our method has better effect on characteristic frequency extracting of a three-phase current signal. The experiment result shows that our method functioning well on small cracks fault diagnosis of the planetary gearbox.