The Use of a Modified Prony's Method to Detect the Airgap-Eccentricity Occurrence in Induction Motors

Induction motors airgap-eccentricity fault detection has attracted the interest of many researchers in the last decades. The discrete Fourier transform (DFT) has been widely used for that purpose. However, DFT can only give meaningful information for stationary signals. In addition, DFT requires a long acquisition time in order to get a high-frequency resolution. In this paper, an efficient time-domain technique based on a modified Prony's method for the airgap-eccentricity fault detection in induction motors is presented in order to overcome the DFT problems. Using this technique, the stator current and apparent power-as processed signals-are divided into short overlapped time windows and each one is analyzed by the least squares Prony's method. The proposed technique allows tracking the frequency and amplitude of the airgap-eccentricity fault characteristic component with a very high accuracy using only few data samples. A fault severity factor based on the amplitude of the estimated component is defined. The effectiveness and accuracy of the proposed method are verified through the presented simulation and experimental results.