| 摘要 |
A method of operating a three phase sensorless brushless motor including a stator including three phase windings and a rotor carrying at least one permanent magnet, the method including switching power to the phase windings of the stator in synchronisation with the rotor position, by applying voltage strokes to the windings, to generate a rotating magnetic flux which interacts with the rotor flux generated by the rotor magnet, to rotate the rotor, the method including applying a plurality of voltage strokes to each of the windings for each rotation of the rotor, sensing a position of the rotor by detecting back emf voltage transitions in a third only of the windings in periods in which voltage strokes are not applied to the third winding, and estimating when the rotor is expected to have rotated though a predetermined angle to a position at which a voltage stoke is next to be applied to the or another winding, and applying the voltage stroke at the estimated time.
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