Apparatus and method for determining shaft speed of a motor
US6449567B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Oct 27, 1998 |
| Grant date | Sep 10, 2002 |
| Priority date | — |
| Expiry date | Oct 27, 2018 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01R31/343
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Briefly stated the motor speed monitor includes a method of determining a shaft speed of a motor by using an electrical signature of the motor. The method includes: (a) sensing an electrical current supplied to the motor to generate a current sensor output signal for at least one electrical phase of the motor; (b) demodulating the current sensor output signal for a predetermined time interval to obtain an instantaneous amplitude of the electrical current signal; (c) generating a frequency spectrum of the instantaneous current amplitude; (d) finding at least one spectral peak of the instantaneous current amplitude frequency spectrum within a predetermined shaft frequency sideband range; (e) estimating a shaft frequency from the at least one spectral peak and converting the shaft frequency to shaft speed.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.