Statistic-based spectral indicator for bearing fault detection in permanent-magnet synchronous machines using the stator current

Abstract

In this paper, an original method for bearing fault detection in high speed synchronous machines is presented. This method is based on the statistical process of Welch's periodogram of the stator currents in order to obtain stable and normalized fault indicators. The principle of the method is to statistically compare the current spectrum to a healthy reference so as to quantify the changes over the time. A statistic-based indicator is then constructed by monitoring specific harmonic family. The proposed method was tested on two experimental test campaigns for four different speeds and compared to a vibration indicator. The method was evaluated using a rigorous performance evaluation metric. A threshold evaluation was performed and shows that the proposed method is very tolerant to the machine speed. Thus, the use of a unique fault threshold whatever the speed can be considered. Results showed excellent agreement as compared with the vibration indicator, with an overall correlation of r ¼0.74 and only 4% of false alarms. Performance demonstrated by this novel method was superior to those of a classical energy-based indicator in terms of correlation with the vibration indicator and detection stability. Moreover, results also showed a better robustness of the proposed method since good performance can be obtained with the same detection threshold whatever the speed or the measure campaign whereas it needs to be redefined for each case with the classical indicator. This work shows the advantages of a statistic-based approach in order to increase the robustness of bearing fault detection in permanentmagnet synchronous machines.

The Decision making System for Condition Monitoring of Induction Motors Based on Vector Control Model

“…Comparatively, the threshold scheme proposed in this paper has shown to be reliable and has the ability to make decisions independent of environmental noise and motor operating points. Thus, for real time condition monitoring applications, the proposed threshold scheme in this paper is more suitable as compared to the method as reported in [53].…”

“…The threshold system as reported in [53] was designed based on the t-test table of standard deviations of the healthy and faulty motor. They consider the impact of speed variation on the decision making system.…”

“…Notably, the predetermined threshold designing techniques used in [36][37][38]53] needs to be updated according to the motor operating point (load) which is quite difficult in real time condition monitoring applications. However, the proposed threshold scheme in this paper adopt itself automatically according to the motor operating situations and thus, can perform reliable decisions on the presence of defects.…”

Research on damage mechanism of bearing current in high power motor

“…William Liu et al analyzed the EDM, wrinkling and its characterization methods caused by bearing current [7]. A. Picot think that high frequency current through the bearings lead to premature failure of the bearing, proposed the Welch cycle statistical method based on a stator current [8]. However, there are few studies on the damage mechanism, damage form and rule of bearing current, and for high-power motors such as wind turbines, bearing current damage has become the main form of mechanical damage, which needs to be studied deeply.…”

Evaluation of different monitoring parameters for synchronous machine fault diagnostics

“…[4][5][6][7][8][9][10][11][12]. Bearing faults though not quite common in large SMs are matter of importance [13] for high-speed machines. Demagnetization faults draw attention of research community those are found in permanent magnet synchronous machines (PMSM) [14].…”