RESONATOR OPTIMIZATIONS FOR WIRELESS ENERGY TRANSFER
Described herein are improved configurations for a high-Q resonator for wireless power transfer that includes a magnetic material having a length along an axis, and a first conductor wrapped around the magnetic material to form a plurality of loops around the axis, the plurality of loops having a span over the magnetic material, wherein the length is a largest dimension of the magnetic material that is parallel to a dipole moment created by the plurality of loops, and the span of the plurality of loops is about one half of the length.
1 . A resonator for wireless power transfer comprising:
a magnetic material having a length along an axis; and
a first conductor wrapped around the magnetic material to form a plurality of loops around the axis, the plurality of loops having a span over the magnetic material, wherein the length is a largest dimension of the magnetic material that is parallel to a dipole moment created by the plurality of loops, and the span of the plurality of loops is about one half of the length.
2 . The resonator of claim 1 , further comprising one or more capacitors coupled to the first conductor.
3 . The resonator of claim 2 , wherein a resonant frequency of the resonator is tuned by the one or more capacitors.
4 . The resonator of claim 3 , wherein the first conductor is connected to an oscillating voltage source at a frequency substantially equal to the resonant frequency.
5 . The resonator of claim 1 , wherein the first conductor includes a Litz wire.
6 . The resonator of claim 1 , wherein the resonator has a quality factor Q>100.
7 . The resonator of claim 1 , wherein the magnetic material is at least partially hollow.
8 . The resonator of claim 7 , further comprising power and control circuitry coupled to the first conductor.
9 . The resonator of claim 8 , wherein the power and control circuitry is at least partially enclosed in the magnetic material.
10 . The resonator of claim 9 , wherein the power and control circuitry is substantially completely enclosed in the magnetic material.
11 . The resonator of claim 1 , further comprising a sheet of conductor material acting as a shield wherein a plane of the sheet is parallel to the axis of the magnetic material.
12 . The resonator of claim 11 , wherein the sheet is separated by less than three centimeters from the magnetic material.
13 . The resonator of claim 12 , wherein a largest dimension of the sheet is greater than a largest dimension of the magnetic material.
14 . The resonator of claim 13 , wherein the sheet is shaped to have at least one flap that bends toward the resonator.
15 . The resonator of claim 14 , wherein the at least one flap extends completely around a perimeter of the sheet.
16 . The resonator of claim 11 , wherein the sheet includes copper.
17 . The resonator of claim 1 , further comprising a second conductor wrapped around the magnetic material to form a second plurality of loops having a second dipole moment that is substantially coaxial to a second axis along a width of the magnetic material, the second axis being substantially orthogonal to the axis, and the second plurality of loops having a second span over the magnetic material wherein the second span is about one half of the width.
18 . A resonator for wireless power transfer comprising:
a magnetic material;
a conductor wrapped around the magnetic material to form a plurality of loops; and
a sheet of conductive material separated from the magnetic material, the sheet having a flap at one or more edges of the sheet that extends toward the magnetic material;
wherein the sheet includes one or more dimensions greater than one or more dimensions of the magnetic material.
19 . The resonator of claim 18 , wherein the sheet includes copper.
20 . The resonator of claim 18 , wherein the sheet is separated from the magnetic material by less than three centimeters.
21 . The resonator of claim 18 , wherein the sheet includes one or more flaps on all of the one or more edges.
22 . The resonator of claim 18 , wherein the flaps extends less than four centimeters toward the magnetic material.
23 . The resonator of claim 18 , wherein the resonator has a quality factor Q>100.
24 . A resonator for wireless power transfer comprising:
a magnetic material having a length along an axis; and
at least one conductor wrapped around the magnetic material to form a plurality of loops around the axis, the plurality of loops having a span over the magnetic material;
wherein the length is a largest dimension of the magnetic material, the length is parallel to a dipole moment created by the at least one conductor, and the span is greater than twenty percent of the length and less than eighty percent of the length.
25 . The resonator of claim 24 , further comprising one or more capacitors coupled to the at least one conductor.
26 . The resonator of claim 24 , wherein the resonator has a quality factor Q>100.