Method and apparatus for determining electric motor speed using vibration and flux
US6087796A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 16, 1998 |
| Grant date | Jul 11, 2000 |
| Priority date | — |
| Expiry date | Jun 16, 2018 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01P3/487
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A programmable apparatus is used to determine the running speed of an ac induction motor based on vibration and flux measurements. A first analysis is performed on at least one of the vibration and flux signals according to a first criterion to determine candidate speeds and whether speed will be determined based on the first analysis or whether a second analysis is required. A second analysis is selectively performed if required by the first analysis. In the first analysis, vibration signals (for example) are transformed to the frequency domain, such as by Fast Fourier Transform, and vibration amplitude peaks contained in the resulting spectrum are analyzed to identify candidate peaks. If only one candidate peak is identified, the frequency at which the candidate peak occurs is used to determine motor running speed. If two or more candidate peaks are identified and the motor is a two-pole motor, the candidate peak having the maximum amplitude is used to determine running speed. If two or more candidate peaks are identified and the motor has more than two poles, a second analysis is performed by producing a flux spectrum. Peaks at various frequencies within the flux spectrum are co…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.