Naslov
Time-frequency representations of induction machine stator current

Autori
Lopac, Nikola ; Bulić, Neven

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Book of Abstracts – My First Conference 2018 / Jardas, Mladen ; Glujić, Darko ; Vukelić, Goran ; Čanađija, Marko ; Travaš, Vanja - Rijeka, 2018, 17-17

ISBN
978-953-165-128-8

Skup
2nd edition of annual conference for doctoral students of engineering and technology „MY FIRST CONFERENCE“

Mjesto i datum
Rijeka, Hrvatska, 27.09.2018

Vrsta sudjelovanja
Ostalo

Vrsta recenzije
Domaća recenzija

Ključne riječi
time-frequency distributions ; instantaneous frequency ; nonstationary signals ; induction machine ; analytic signal

Sažetak
Induction machines have a dominant role in industrial applications nowadays, due to their robustness, reliability, low cost and efficiency. Therefore, the monitoring of their conditions is required. The most cost effective approach might be the monitoring of the stator current, whose measurements are usually already incorporated into the control systems. During the transient states of the machine, stator current may be considered as a nonstationary signal, because its frequency content varies with time. Time-frequency distributions (TFDs) represent valuable tools for the analysis and processing of nonstationary signals. They provide a simultaneous representation in the both time and frequency domain. Therefore, TFDs are convenient to keep track of signal frequency variation with time. The function that provides signal frequency at each time instance is called the instantaneous frequency (IF). This study provides an analysis of TFDs, focusing on their possible application in the monitoring of the induction machine stator current frequency during the transient and steady state, in the case of the measured signal being heavily corrupted by noise. The nonstationary current signal was obtained by experimental measurements conducted during the acceleration of induction machine, with low signal-to-noise ratio. After signal preprocessing, six different TFDs were applied and examined. Finally, IF was estimated by the algorithm exploiting peak values of the computed TFDs. The spectrogram offered a good attenuation of interferences, but a poor resolution. The Wigner-Ville distribution was discarded as unsuitable for this application due to significant interferences. The smoothed- pseudo Wigner-Ville, the Choi-Williams and the Born- Jordan distributions gave satisfactory results, with the Zhao-Atlas-Marks distribution suggested as the most suitable choice for this application as it provided the best balance between time and frequency resolution and noise and interferences reduction. Considered distributions, except the Wigner-Ville’s, offered practically identical IF estimations, in accordance to the expected ones.

Izvorni jezik
Engleski

Znanstvena područja
Elektrotehnika, Računarstvo

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