Technology for sensorless detection of reverse rotation and speed estimation for electric machines

A computer system comprising:

• at least one processor;
• and
• a computer readable storage medium accessible to the at least one processor, the computer readable storage medium having program instructions embodied therewith, the program instructions being executable by the at least one processor to cause the at least one processor to perform a method comprising:
• detecting by the computer system, for a recorded waveform of multi-phase electrical power indicia for supply conductors of the machine measured remotely from the machine, that a first time segment of the recorded waveform corresponds to an electrically energized state of the machine and that a second time segment of the recorded waveform corresponds to an electrically de-energized state of the machine, wherein since the second time segment of the recorded waveform is for the de-energized state, the second time segment is for times when the recorded waveform arises from power induced on the supply conductors for the machine by rotation of the machine;
• and
• determining by the computer system that the machine in the de-energized state has rotated in a direction reverse to the reference direction, wherein the determining that the machine in the de-energized state has rotated in a direction reverse to the reference direction includes the computer system comparing the first and second time segments of the recorded waveform.

A computer program product for determining rotation of a shaft of a de-energized electric machine without accessing the machine, the computer program product comprising a computer readable storage medium having program instructions embodied therewith, the program instructions executable by at least one processor of a computer system to cause the computer system to perform a method comprising:

• detecting by the computer system, for a recorded waveform of multi-phase electrical power indicia for supply conductors of the machine measured remotely from the machine, that a first time segment of the recorded waveform corresponds to an electrically energized state of the machine and that a second time segment of the recorded waveform corresponds to an electrically de-energized state of the machine, wherein since the second time segment of the recorded waveform is for the de-energized state, the second time segment is for times when the recorded waveform arises from power induced on the supply conductors for the machine by rotation of the machine;
• and
• determining by the computer system that the machine in the de-energized state has rotated in a direction reverse to the reference direction, wherein the determining that the machine in the de-energized state has rotated in a direction reverse to the reference direction includes the computer system comparing the first and second time segments of the recorded waveform.