Method and apparatus for brushless DC motor speed control
US4876491A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 26, 1988 |
| Grant date | Oct 24, 1989 |
| Priority date | — |
| Expiry date | Feb 26, 2008 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02P6/185
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
Control and synchronization of a polyphase, brushless DC motor (used for a hard-disk system) during initial start-up of the motor, is effected by monitoring rotor position using a high-frequency commutation: A short current pulse is applied to each power phase of the motor, and motor current conducted in response thereto, is measured to determine therefrom positional information of the rotor. From such positional information the identity of the appropriate motor phase to which is applied a torque-producing current is determined. Cycles of high-frequency commutation and application of torque-producing are performed, until the rotational speed of the rotor has attained a predetermined RPM. Motor speed is controled in synchronized, increasing fashion by continued monitoring of the motor current and back-EMF, until a desired rotational RPM is attained, whereupon torque-producing current is sequentially applied to each motor phase in synchronization with the rotor position by deriving positional information from the disk.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.