Method and apparatus for detecting rotor position by use of magnetic field sensor pairs
US6288533A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 1, 1999 |
| Grant date | Sep 11, 2001 |
| Priority date | — |
| Expiry date | Apr 1, 2019 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01D5/145
- WIPO fieldPharmaceuticals
- WIPO sectorChemistry
Abstract
The rotation position of a rotor (2) rotatable around a rotation axis (1) is determined by mounting a magnetic source (2.1) on the rotor, by providing on a stator (3) at least three sensors (4, 5, 6, 7) for measuring the magnetic field of the magnetic source and being arranged in at least two pairs (4/5, 6/7), calculating the difference of quantities measured by the two sensors of each sensor pair, calculating the ratio of the difference values of two pairs and comparing the ratio with a predetermined function of said ratio versus the rotation position. This rotation position determination is very robust against offset and sensitivity variations common to all sensors (4, 5, 6, 7) and against external magnetic fields and can easily be made robust against mechanical tolerances between rotating and stationary parts also. In a preferred embodiment, there are four sensors (4, 5, 6, 7) arranged at the corners of a square perpendicular to and symmetrical relative to the rotation axis (1). The sensors (4, 5, 6, 7) are advantageously Hall sensors integrated together with readout and calculation electronics in one die.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.