Digital techniques for faults diagnostic and protection of IPM motors

The paper presents a comparative analysis of digital faults diagnostic techniques for interior permanent magnet (IPM) synchronous motors. In IPM motors, permanent magnets are embedded inside rotor core. Therefore, the IPM motors show critical properties such as demagnetization and flux distortion during a fault. The invasive and non-invasive type faults diagnostic techniques are implemented for IPM motors. The non-invasive techniques, which include digital algorithms, are found effective and better than invasive techniques. In this work, fast Fourier transform (FFT), short-time Fourier transform (STFT), and wavelet packet transform (WPT) algorithms are implemented for diagnostic and protection of IPM motors. The FFT, STFT, and WPT algorithms are applied on stator currents of an IPM motor for single phasing, line to ground (L-G), and ine to line (L-L) faults of an IPM motor are investigated. The WPT based diagnostic algorithm performed better than FFT and STFT algorithms.