Electronically commutated motor and control system employing phase angle control of phase current
US7821217B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | May 22, 2007 |
| Grant date | Oct 26, 2010 |
| Priority date | — |
| Expiry date | Apr 29, 2028 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02P21/0089
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A power tool may include an electronically commutated motor such as, for example, a brushless DC permanent magnet motor with a rotor having internally mounted magnets and/or cavities filled with air or other non-magnetic materials. A control system may be used to control the motor in a manner that implements field weakening when the speed of the motor increases beyond its rated motor speed, or when the torque demands on the motor continue to increase after the maximum power output of the motor is reached. The field weakening may offset the growing back EMF and may enable a constant power and constant efficiency to be achieved by the motor over a wide speed range, rather than at just a single predetermined operating speed. Pulse width modulation control of the motor may be used up until the motor reaches its maximum power output.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.