CLOVER LEAF AND BUTTERFLY COIL STRUCTURES FOR FLAT WIRELESS COUPLING PROFILES IN WIRELESS POWER TRANSFER APPLICATIONS
In one aspect, an apparatus for wirelessly transferring charging power is provided. The apparatus comprises a coil comprising a conductor defining a plurality of sides of the coil. For each of the plurality of sides of the coil, the conductor bows toward a center of the coil as the conductor extends from an outer portion of the respective side of the coil toward a middle portion of the respective side of the coil. A magnetic coupling factor between the coil and a receive coil is within a predetermined percentage of a maximum or minimum magnetic coupling factor between the coil and the receive coil for all offsets of a center of the receive coil, with respect to the center of the coil, that are within a perimeter defined by the conductor of the coil.
1 . An apparatus for wirelessly transferring charging power, the apparatus comprising:
a coil comprising a conductor defining a plurality of sides of the coil, wherein for each of the plurality of sides of the coil, the conductor bows toward a center of the coil as the conductor extends from an outer portion of the respective side of the coil toward a middle portion of the respective side of the coil.
2 . The apparatus of claim 1 , wherein at each corner of corresponding sides of the coil, the conductor is bent at an acute angle with respect to a direction of extension of each of the corresponding sides to form substantially rounded corners.
3 . The apparatus of claim 1 , wherein at each corner of corresponding sides of the coil, the conductor is bent at a substantially 90 degree angle with respect to a direction of extension of each of the corresponding sides.
4 . The apparatus of claim 1 , wherein the conductor of the coil forms a plurality of windings and for at least one winding on one side of the plurality of sides of the coil, the conductor extends in a substantially straight line along the entire side.
5 . The apparatus of claim 1 , wherein a magnetic coupling factor between the coil and another coil is within a predetermined percentage of a maximum or minimum magnetic coupling factor between the coil and the another coil for all offsets of a center of the another coil, with respect to the center of the coil, that are within a perimeter defined by the conductor of the coil.
6 . The apparatus of claim 1 , wherein for a given voltage applied across the coil, an amount of current circulating in the coil is within a predetermined percentage of a maximum or minimum amount of current circulating in the coil for all offsets of a center of another coil, with respect to the center of the coil, that are within a perimeter defined by the conductor of the coil.
7 . The apparatus of claim 1 , wherein the conductor of the coil forms a plurality of windings and wherein successive windings of the plurality of windings bow toward a center of the coil to an increasing extent from an outermost winding to an innermost winding.
8 . The apparatus of claim 1 , wherein the conductor of the coil forms a plurality of windings and wherein the conductor extends in a substantially straight line along an entirety of each of the plurality of sides for at least one of the plurality of windings.
9 . A method for wirelessly transferring charging power, the method comprising:
driving, with an alternating current, a coil comprising a conductor defining a plurality of sides of the coil, wherein for each of the plurality of sides of the coil, the conductor bows toward a center of the coil as the conductor extends from an outer portion of the respective side of the coil toward a middle portion of the respective side of the coil, and
wirelessly transferring charging power from the coil to another coil.
10 . The method of claim 9 , wherein the coil comprises a plurality of windings and for at least one winding on one side of the plurality of sides of the coil, the conductor extends in a substantially straight line along the entire side.
11 . The method of claim 9 , wherein a magnetic coupling factor between the coil and the another coil is within a predetermined percentage of a maximum or minimum magnetic coupling factor between the coil and the another coil for all offsets of a center of the another coil, with respect to the center of the coil, that are within a perimeter defined by the conductor of the coil.
12 . The method of claim 9 , wherein for a given voltage applied across the coil, an amount of current circulating in the coil is within a predetermined percentage of a maximum or minimum amount of current circulating in the coil for all offsets of a center of the another coil, with respect to the center of the coil, that are within a perimeter defined by the conductor of the coil.
13 . The method of claim 9 , wherein the conductor of the coil forms a plurality of windings and wherein successive windings of the plurality of windings bow toward a center of the coil to an increasing extent from an outermost winding to an innermost winding.
14 . The method of claim 9 , wherein the conductor of the coil forms a plurality of windings and wherein the conductor extends in a substantially straight line along an entirety of each of the plurality of sides for at least one of the plurality of windings.
15 . A method for fabricating an apparatus for wirelessly transferring charging power, the method comprising:
providing a ferrimagnetic structure, and
forming a coil by disposing a conductor defining a plurality of sides of the coil such that, for each of the plurality of sides, the conductor bows toward a center of the coil as the conductor extends from an outer portion of the respective side of the coil toward a middle portion of the respective side of the coil.
16 . The method of claim 15 , wherein the conductor is disposed such that, at each corner of corresponding sides, the conductor is bent at an acute angle with respect to a direction of extension of each of the corresponding sides to form substantially rounded corners.
17 . The method of claim 15 , wherein the conductor is disposed such that, at each corner of corresponding sides, the conductor is bent at a substantially 90 degree angle with respect to a direction of extension of each of the corresponding sides.
18 . The method of claim 15 , wherein for at least one side of the plurality of sides, the conductor is disposed to extend in a substantially straight line along the entire side.
19 . The method of claim 15 , wherein the coil is formed such that when driven with an alternating current, a magnetic coupling factor between the coil and another coil is within a predetermined percentage of a maximum or minimum magnetic coupling factor between the coil and the another coil for all offsets of a center of the another coil, with respect to the center of the coil, that are within a perimeter defined by the conductor of the coil.
20 . The method of claim 15 , wherein the coil is formed such that for a given voltage applied across the coil, an amount of current circulating in the coil is within a predetermined percentage of a maximum or minimum amount of current circulating in the coil for all offsets of a center of another coil, with respect to the center of the coil, that are within a perimeter defined by the conductor of the coil.
21 . The method of claim 15 , further comprising disposing the conductor such that the coil comprises a plurality of windings, wherein successive windings of the plurality of windings bow toward a center of the coil to an increasing extent from an outermost winding to an innermost winding.
22 . The method of claim 15 , further comprising disposing the conductor to form a plurality of windings, wherein the conductor extends in a substantially straight line along an entirety of each of the plurality of sides for at least one of the plurality of windings.
23 . An apparatus for wirelessly transferring charging power, the apparatus comprising:
means for wirelessly transmitting charging power comprising a conductor defining a plurality of sides of the means for wirelessly transmitting charging power, wherein for each of the plurality of sides, the conductor bows toward a center of the means for wirelessly transmitting charging power as the conductor extends from an outer portion of the respective side toward a middle portion of the respective side; and
means for driving the means for wirelessly transmitting charging power with an alternating current.
24 . The apparatus of claim 23 , wherein at each corner of corresponding sides, the conductor is bent at an acute angle with respect to a direction of extension of each of the corresponding sides to form substantially rounded corners.
25 . The apparatus of claim 23 , wherein at each corner of corresponding sides, the conductor is bent at a substantially 90 degree angle with respect to a direction of extension of each of the corresponding sides.
26 . The apparatus of claim 23 , wherein the conductor forms a plurality of windings and wherein for at least one side of the plurality of sides, the conductor extends in a substantially straight line along the entire side.
27 . The apparatus of claim 23 , wherein a magnetic coupling factor between the means for wirelessly transmitting charging power and another coil is within a predetermined percentage of a maximum or minimum magnetic coupling factor between the means for wirelessly transmitting charging power and the another coil for all offsets of a center of the another coil, with respect to the center of the means for wirelessly transmitting charging power, that are within a perimeter defined by the conductor.
28 . The apparatus of claim 23 , wherein for a given voltage applied across the means for wirelessly transmitting charging power, an amount of current circulating in the means for wirelessly transmitting charging power is within a predetermined percentage of a maximum amount or minimum of current circulating in the means for wirelessly transmitting charging power for all offsets of a center of another coil, with respect to the center of the means for wirelessly transmitting charging power, that are within a perimeter defined by the conductor.
29 . The apparatus of claim 23 , wherein the conductor forms a plurality of windings and wherein successive windings of the plurality of windings bow toward a center of the means for wirelessly transmitting charging power to an increasing extent from an outermost winding to an innermost winding.
30 . The apparatus of claim 23 , wherein the conductor forms a plurality of windings and wherein the conductor extends in a substantially straight line along an entirety of each of the plurality of sides for at least one of the plurality of windings.