Title:
BRUSHLESS DC MOTORS
Document Type and Number:
WIPO Patent Application WO1996022629
Kind Code:
A3
Abstract:
A brushless DC motor comprises a rotor (20) and a stator (22) having confronting surfaces. Permanent magnets (M) are provided at one of the confronting surfaces, the magnets being equally angularly spaced around an axis (A-A) of rotation of the rotor such that each magnet occupies part of a respective pole arc (PA) of a first circle (C1) centred on the axis (A-A), the pole arcs each subtending a common pole angle ( alpha ) to the axis. Teeth (Tm) are provided at the other of the confronting surfaces, the teeth being angularly spaced from one another around the axis (A-A) such that each tooth occupies part of a respective tooth arc (TA) of a second circle (C2) centred on the axis, the tooth arcs each subtending a common tooth angle ( beta ) to the axis. Windings (40) are wound around the teeth (Tm) whereby energisation of the windings with electrical currents at respective phases will produce a torque that will rotate the rotor (20). The tooth angle ( beta ) is substantially equal to the pole angle ( alpha ). The teeth (Tm) are arranged in an even number of sets, each set comprising at least one tooth (Tm). A respective further tooth (Ta) is disposed between each such set, each further tooth not having a winding thereon and each further tooth occupying part of a respective further arc of the second circle (C2), the further arcs each subtending to the axis (A-A) a common angle ( gamma ) substantially equal to twice the above-mentioned pole angle ( alpha ) divided by the number of phases.
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Inventors:
WERSON MICHAEL JOHN (GB)
Application Number:
PCT/GB1996/000114
Publication Date:
September 12, 1996
Filing Date:
January 19, 1996
Export Citation:
Assignee:
NORCROFT DYNAMICS LTD (GB)
WERSON MICHAEL JOHN (GB)
WERSON MICHAEL JOHN (GB)
International Classes:
H02K21/12; H02K29/00; H02K21/22; H02K29/03; H02K3/28; (IPC1-7): H02K29/03; H02K29/00
Foreign References:
| DE3546226A1 | 1986-07-03 | |||
| EP0433479A1 | 1991-06-26 | |||
| EP0160868A2 | 1985-11-13 |
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