HIGH-ASPECT RATIO HOMOPOLAR MAGNETIC ACTUATOR
First Claim
1. An electromagnetic actuator comprising:
- a body having a rotational axis;
at least three radial magnetic pole assemblies, each circumferentially arranged around the rotational axis, separated from the body by radial gaps, and distributed along the rotational axis at fixed distances from each other, each radial magnetic pole assembly comprising;
a plurality of radial poles adjacent and spaced apart from a lateral facing surface of the body and configured to communicate magnetic flux with the lateral facing surface of the body, andthe plurality of radial poles of the respective radial magnetic pole assembly and the body magnetically coupled and defining a radial magnetic control circuit;
an excitation coil around each of the plurality of radial poles configured to produce control magnetic flux in the radial magnetic control circuits; and
a plurality of magnetic elements distributed with alternating polarities along the rotational axis, each of the magnetic elements residing between adjacent radial magnetic pole assemblies and configured to produce bias magnetic fluxes flowing radially within each adjacent radial magnetic pole assembly and axially in the body between adjacent radial magnetic pole assemblies.
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Accused Products
Abstract
A homopolar magnetic actuator is configured to exert controllable radial forces on a body adapted to rotate around an axis. The actuator comprises at least three radial magnetic pole assemblies distributed at some distances from each other along the axis, each including a plurality of poles adjacent to an actuator target on the body. Permanent magnets are used to induce bias magnetic fluxes in the assemblies with polarities alternating from assembly to assembly but remaining the same around the rotational axis. Having several small bias fluxes distributed between several pole assemblies instead of a large single bias flux facilitates designing an actuator with a high aspect ratio. A control coil around each pole can induce a control magnetic flux in the poles. These control fluxes affect magnetic flux distribution around the actuator target, resulting in magnetic forces exerted on the target.
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Citations
20 Claims
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1. An electromagnetic actuator comprising:
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a body having a rotational axis; at least three radial magnetic pole assemblies, each circumferentially arranged around the rotational axis, separated from the body by radial gaps, and distributed along the rotational axis at fixed distances from each other, each radial magnetic pole assembly comprising; a plurality of radial poles adjacent and spaced apart from a lateral facing surface of the body and configured to communicate magnetic flux with the lateral facing surface of the body, and the plurality of radial poles of the respective radial magnetic pole assembly and the body magnetically coupled and defining a radial magnetic control circuit; an excitation coil around each of the plurality of radial poles configured to produce control magnetic flux in the radial magnetic control circuits; and a plurality of magnetic elements distributed with alternating polarities along the rotational axis, each of the magnetic elements residing between adjacent radial magnetic pole assemblies and configured to produce bias magnetic fluxes flowing radially within each adjacent radial magnetic pole assembly and axially in the body between adjacent radial magnetic pole assemblies. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method for exerting a radial force on a body, the body configured to rotate about a rotational axis, the method comprising:
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communicating a first bias magnetic flux between a first radial pole assembly, the body, and a second radial pole assembly, the first and second radial pole assemblies spaced apart from one another along the rotational axis, the first and second radial pole assemblies each circumferentially arranged around the rotational axis, and the first and second radial pole assemblies separated from the body by an air gap, the first bias magnetic flux propagating through the body in a direction parallel to the rotational axis; communicating a second bias magnetic flux between the second radial pole assembly, the body, and a third radial pole assembly, the second and third radial pole assemblies spaced apart from one another along the rotational axis, the second and third radial pole assemblies each circumferentially arranged around the rotational axis, and the second and third radial pole assemblies separated from the body by an air gap, the second radial bias magnetic flux propagating through the body in a direction parallel to the rotational axis and opposite from the first bias magnetic flux; communicating a first radial control magnetic flux between the first radial pole assembly and the body, the first radial control magnetic flux propagating between a first radial pole of the first pole assembly, the body, and a second pole of the first pole assembly, the first radial control magnetic flux propagating in a radial direction orthogonal to the rotational axis; communicating a second radial control magnetic flux between the second radial pole assembly and the body, the second radial control magnetic flux propagating between a first radial pole of the second pole assembly, the body, and a second pole of the second pole assembly, the second radial control magnetic flux propagating in a radial direction orthogonal to the rotational axis opposite from the first radial control magnetic flux; and communicating a third radial control magnetic flux between the third radial pole assembly and the body, the third radial control magnetic flux propagating between a first radial pole of the third pole assembly, the body, and a second pole of the third pole assembly, the third radial control magnetic flux propagating in a radial direction orthogonal to the rotational axis opposite from the second radial control magnetic flux. - View Dependent Claims (13, 14)
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15. A system comprising:
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a body having a rotational axis configured to move relative to a base; an electromagnetic actuator sub-assembly coupled to the base comprising; three radial magnetic pole assemblies, each circumferentially arranged around the rotational axis, separated from the body by radial gaps, and distributed along the rotational axis at fixed distances from each other, each radial magnetic pole assembly comprising; a plurality of radial poles adjacent and spaced apart from a lateral facing surface of the body and configured to communicate magnetic flux with the lateral facing surface of the body, and the plurality of radial poles of the respective radial magnetic pole assembly and the body magnetically coupled and defining a radial magnetic control circuit, a control coil around each of the plurality of radial poles configured to produce control magnetic flux in the radial magnetic control circuits, and a plurality of magnetic elements distributed with alternating polarities along the rotational axis, each of the magnetic elements residing between adjacent radial magnetic pole assemblies and configured to produce bias magnetic fluxes flowing radially within each adjacent radial magnetic pole assembly and axially in the body between adjacent radial magnetic pole assemblies; one or more position sensors configured to sense a position of the body; and at least one control electronics package configured to control the magnetic flux in the radial magnetic control circuits. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification