Rotation detector and direct-current motor
US8222776B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Aug 5, 2009 |
| Grant date | Jul 17, 2012 |
| Priority date | — |
| Expiry date | Aug 26, 2030 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02P2203/03
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A power supply unit superimposes alternating-current voltage on direct-current voltage and applies it to a motor. As a result, when the motor is rotated, a current containing an alternating-current component flows. Further, the motor includes a capacitor connected in parallel with one phase coil. Owing to this capacitor, the impedance of the motor circuit between brushes is varied according to the rotation of the motor. Variation in impedance appears as variation in the amplitude of the alternating-current component in motor current. A signal processing unit extracts an alternating-current component from the motor current detected by the current detection unit and generates a rotation pulse corresponding to variation in the amplitude. A rotation angle detection unit detects the rotation angle of the motor based on this rotation pulse.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.