Method to identify rotor slot harmonics in a motor current spectrum

A computer-implemented method to identify rotor slot harmonics in a motor current spectrum of an AC induction motor, comprising:

• receiving current data from the AC induction motor operated at two different load values;
• obtaining a motor current frequency spectrum comprising a first motor current spectrum corresponding to a first load value and a second motor current spectrum corresponding to a second load value;
• detecting a number of peak current values for a frequency range of the motor current frequency spectrum;
• and
• comparing the detected number of peak current values for the frequency range from the first motor current spectrum to the second motor current spectrum by:
• determining a pair of consecutive peak current values from the detected number of peak current values, the pair of consecutive peak current values include a first peak current value for the first load value and a second peak current value for the second load value;
• calculating a difference between the first peak current value and the second peak current value;
• comparing the difference to a threshold value;
• and
• in response to the difference being greater than zero and less than the threshold value, identifying the pair of consecutive peak current values as rotor slot harmonics.