Electronically commutated motor
US4169990A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 1, 1977 |
| Grant date | Oct 2, 1979 |
| Priority date | — |
| Expiry date | Jun 1, 1997 |
Classification
- Technology area (CPC F)Mechanical Engineering; Lighting; Heating
- CPC primaryF25B2600/021
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A brushless DC motor is constructed with photosensitive device for detecting rotor shaft position. Arcuate permanent magnets on the rotor provide a DC flux field while distributed stationary armature windings, each spanning a fixed number of slots in the armature assembly, provide mutually perpendicular magnetic fields. A logic circuit comprising NOR gates and transistor switches and drivers activated in response to signals from the shaft position sensors are utilized to control current switching in the armature windings of the motor. A light interrupting shutter mounted to the rotor cooperates with the light sensitive devices which are mounted to a supporting bracket fixed to the stationary armature assembly in a manner to selectively preset advancement of commutation of the armature windings. Variations on permanent magnet rotor construction and novel applications of a brushless DC motor are also disclosed as is a novel approach for dispensing with the mechanism for detecting the shaft position. In this last respect a commutating circuit is disclosed for a brushless DC motor, including a detecting circuit responsive to the electromotive force (emf) of the brushless DC motor to pr…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.