Patent ID: 11921161
Assignee: MITSUBISHI ELECTRIC RESEARCH LABORATORIES, INC.
Field: Electrical machinery, apparatus, energy (Electrical engineering)
Classification: CPC G  H | IPC G  H

Claim 7:
8. A fault detection system for detecting broken bar faults of an induction motor during operations, comprising:
an interface configured to acquire signals via sensors connected to the induction motor, wherein one of the sensors is arranged to measure, in a time domain, signals of a stator current powering the induction motor with a fundamental frequency, wherein the induction motor is under a varying speed operation;
a memory to store computer-executable programs including a computer-implemented method of claim 1 and a fault detection program;
a processor configured to perform steps of:
converting the stator current to a complex space vector;
transforming the complex vector to a transformed stator current by referencing to synchronous reference frame;
performing Short time Fourier Transform (STFT) on the transformed stator current to get spectrogram matrix;
removing a DC component from the spectrogram matrix;
determining, in a frequency domain, sparse and smooth frequency components in the spectrogram matrix, wherein the determining includes performing a graph-based method by imposing a smoothness constraint and a sparsity constraint on the frequency component; and
detecting a fault in the induction motor if the frequency component includes a continuously changing frequency component and sparse fault frequency component-in the spectrogram matrix;
displaying a normal/fault status information of the induction motor on a display unit by transmitting a signal of the normal/fault status to a user interface connected to the display unit; and
interrupting supplying the stator current in response to detecting the fault.