Brushless DC drive motor with external rotor for use in disc drives and like devices
DCFirst Claim
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1. A brushless DC drive motor of the type having a total number of phases divisible by three, comprising, in combination,a stator;
- a permanent-magnet rotor mounted on said stator for rotation relative thereto about a rotation axis, said rotor having a total of four rotor poles of which two are of a first magnetic polarity and the other two of an opposite magnetic polarity, the rotor poles of first polarity alternating circumferentially with the rotor poles of second polarity;
a stator winding mounted on said stator and consisting of three pairs of non-overlapping stator coils; and
rotor-position-dependent control means connected to the three pairs of non-overlapping stator coils for controlling energization of said three pairs of non-overlapping stator coils in dependence upon angular position of the rotor, and including rotor-position-detecting means located stationary with respect to said stator and operative for detecting the angular position of the rotor,wherein each pair of stator coils consists of two coils which are located diametrically opposite to each other and which are so wound and electrically connected that both are energized substantially simultaneously with identical magnetic polarity.
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Abstract
A brushless DC drive motor with an external rotor has three pole shoes on a substantially ring-shaped stator for each two poles on the rotor. The stator winding is commutated by a three-phase commutation network in such a fashion that first, second and third networks in the stator winding are cyclically connected to an external DC source in accordance with rotor position. Each of the networks comprises at least one stator coil wrapped around a neck of a single corresponding one of the pole shoes.
45 Citations
28 Claims
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1. A brushless DC drive motor of the type having a total number of phases divisible by three, comprising, in combination,
a stator; -
a permanent-magnet rotor mounted on said stator for rotation relative thereto about a rotation axis, said rotor having a total of four rotor poles of which two are of a first magnetic polarity and the other two of an opposite magnetic polarity, the rotor poles of first polarity alternating circumferentially with the rotor poles of second polarity; a stator winding mounted on said stator and consisting of three pairs of non-overlapping stator coils; and rotor-position-dependent control means connected to the three pairs of non-overlapping stator coils for controlling energization of said three pairs of non-overlapping stator coils in dependence upon angular position of the rotor, and including rotor-position-detecting means located stationary with respect to said stator and operative for detecting the angular position of the rotor, wherein each pair of stator coils consists of two coils which are located diametrically opposite to each other and which are so wound and electrically connected that both are energized substantially simultaneously with identical magnetic polarity. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27)
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28. A brushless DC motor of the type having a total number of phases divisible by three, comprising, in combination,
a stator; -
a permanent-magnet rotor mounted on said stator for rotation relative thereto about a rotation axis, said rotor having an even integer, nrp, of rotor poles of which nrp /2 are of a first magnetic polarity and the other nrp /2 of an opposite magnetic polarity, the rotor poles of first polarity alternating circumferentially with the rotor poles of second polarity; a stator winding mounted on said stator and an even integer, nsc, of non-overlapping stator coils disposed in pairs, wherein the number of non-overlapping stator coils, nsc, is an even integer multiple of three and the ratio nsc /nrp equals 3/2; and rotor-position-dependent control means connected to the pairs of non-overlapping stator coils for controlling energization of said pairs of non-overlapping stator coils in dependence upon angular position of the rotor, and including rotor-position-detecting means located stationary with respect to said stator and operative for detecting the angular position of the rotor, wherein each pair of stator coils consists of two coils which are located diametrically opposite to each other and which are so wound and electrically connected that both are energized substantially simultaneously with identical magnetic polarity.
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Specification