Universal electric motor speed sensing by using Fourier transform method
US4527101A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 23, 1983 |
| Grant date | Jul 2, 1985 |
| Priority date | — |
| Expiry date | Nov 23, 2003 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S388/904
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An indirect speed sensor for an electric motor, such as an electric motor of the universal type, provides for a resistive element in series with the motor windings so that current pertubations that occur as a consequence of armature rotation are manifested as speed-dependent voltage signals across the resistive element. The voltage signals are amplified and filtered to remove frequency components above and below the expected signal spectrum and then provided to an analog-to-digital converter that converts the filtered analog signal to digital values that are stored in a memory. A stored-program controlled microprocessor analyzes the stored digital information by performing a fast Fourier transform to provide an equivalent amplitude spectrum. The maximum amplitude spectral component is then identified to determine the speed of the motor.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.