Low-speed sensorless brushless motor control in a power tool
US11750124B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jun 22, 2022 |
| Grant date | Sep 5, 2023 |
| Priority date | — |
| Expiry date | Jun 22, 2042 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02P2209/07
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A control unit for a brushless DC motor of a power tool having a rotor and a stator is provided. The control unit detects an initial position of the rotor, commutates the motor beginning at the initial position of the rotor using a low-speed motor commutation scheme until an output speed of the rotor exceeds a speed threshold, and commutates the motor based on a back-electromotive force (back-EMF) voltage of the motor after the output speed of the rotor exceeds the speed threshold. In the low-speed commutation scheme, the control unit applies a first set of voltage pulses to a present sector and a second set of voltage pulses to a next sector, and detects a transition of the rotor from the present sector to the next sector based on motor current measurements associated with the first set of voltage pulses and the second set of voltage pulses.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.