Automatically-aligning magnetic field system
A wireless power transfer system includes a wireless power transfer device. The wireless power transfer device includes a first transmitting coil oriented along a first axis; a second transmitting coil on the first transmitting coil and oriented along a second axis different from the first axis; and a nonmagnetic material magnetically decoupling the first transmitting coil from the second transmitting coil in an area of overlap between the first and second transmitting coils.
1. A wireless power transfer system comprising a wireless power transfer device, the wireless power transfer device comprising:
a coil assembly, comprising:
a first transmitting coil oriented along a first axis,
a second transmitting coil above the first transmitting coil in an area of overlap between the first and second transmitting coils, and oriented along a second axis different from the first axis, and
a nonmagnetic material magnetically decoupling the first transmitting coil from the second transmitting coil in the area of overlap between the first and second transmitting coils; and
an electronics assembly, comprising at least one electronic component.
2. The wireless power transfer system of claim 1 , wherein the wireless power transfer device comprises a cable electrically coupled between the electronics assembly and the coil assembly.
3. The wireless power transfer system of claim 2 , wherein the at least one electronic component comprises:
a driver configured to provide a first current to the first transmitting coil and a second current to the second transmitting coil, and
a controller configured to control the first and second currents provided by the driver.
4. The wireless power transfer system of claim 3 , wherein the cable comprises:
a first twisted pair of internal wires to provide the first current from the driver to the first transmitting coil; and
a second twisted pair of internal wires to provide the second current from the driver to the second transmitting coil.
5. The wireless power transfer system of claim 3 , wherein the cable comprises one or more internal wires configured to provide information about current in the first transmitting coil and/or current in the second transmitting coil from the coil assembly to the electronics assembly.
6. The wireless power transfer system of claim 3 , wherein the at least one electronic component comprises a receiver configured to wirelessly receive data and to transmit the data to the controller.
7. The wireless power transfer system of claim 3 , wherein the at least one electronic component comprises power modulation electronics configured to provide power to the driver.
8. The wireless power transfer system of claim 2 , wherein the electronics assembly comprises a battery.
9. The wireless power transfer system of claim 2 , wherein a length of the cable is equal to or greater than a length of the first transmitting coil along the first axis.
10. The wireless power transfer system of claim 1 , wherein the electronics assembly and the coil assembly are in a same container and are spaced apart from each other in the container by at least 0.25 times a length of the first transmitting coil along the first axis,
wherein the at least one electronic component comprises a driver configured to provide a first current to the first transmitting coil and a second current to the second transmitting coil.
11. The wireless power transfer system of claim 2 , wherein the coil assembly comprises:
a first LC resonant circuit corresponding to the first transmitting coil and a second LC resonant circuit corresponding to the second transmitting coil.
12. The wireless power transfer system of claim 2 , comprising an electronic device comprising a receiver coil.
13. A wireless power transfer system comprising a wireless power transfer device, the wireless power transfer device comprising:
a first transmitting coil oriented along a first axis;
a second transmitting coil on the first transmitting coil and oriented along a second axis different from the first axis;
a nonmagnetic material magnetically decoupling the first transmitting coil from the second transmitting coil in an area of overlap between the first and second transmitting coils; and
at least one electronic component in a magnetic field shallow zone angularly positioned in a plan view between a portion of the first transmitting coil extending in the plan view from the area of overlap and a portion of the second transmitting coil extending in the plan view from the area of overlap,
wherein the magnetic field shallow zone comprises a region where, when the first and second transmitting coils are driven with in-phase AC currents of a same magnitude, a magnetic field generated by the first and second transmitting coils at any point in the region is substantially less in magnitude than the magnetic field at an end of the first transmitting coil.
14. The wireless power transfer system of claim 13 , wherein the first and second axes are perpendicular to each other in the plan view and four magnetic field shallow zones including the magnetic field shallow zone are positioned in the plan view in four quadrants defined by the first and second transmitting coils, and
wherein a plurality of electronic components are in the four magnetic field shallow zones.
15. The wireless power transfer system of claim 13 , wherein the at least one electronic component comprises at least one selected from among a capacitor, a transistor, a resistor, an inductor, a diode, a transducer, a transformer, and a current sensor.
16. The wireless power transfer system of claim 13 , wherein a ratio of a first magnitude of the magnetic field at any point in the region to a second magnitude of the magnetic field at the end of the first transmitting coil is less than 0.2.
17. The wireless power transfer system of claim 13 , wherein the region has:
a planar shape in the plan view of a 90 degree sector of a circle having a radius equal to or less than a distance on the first axis between a first point corresponding to the end of the first transmitting coil and a second point corresponding to an edge of the area of overlap proximal to the end of the first transmitting coil; and
a thickness in a thickness direction perpendicular to the plan view that is uniform over the planar shape and less than an average thickness of the first transmitting coil, and
wherein the region is centered in the thickness direction on a plane that is parallel to the plan view and equidistant between the first and second transmitting coils in the thickness direction.
18. The wireless power transfer system of claim 13 , wherein the magnetic field shallow zone comprises a portion of a low-angle magnetic field plane parallel to the plan view that is equidistant between the first and second transmitting coils in a thickness direction perpendicular to the low-angle magnetic field plane.
19. The wireless power transfer system of claim 13 , wherein the magnetic field shallow zone comprises a portion of a low-angle magnetic field plane parallel to the plan view and between the first and second transmitting coils where, when the first and second transmitting coils are driven with AC current, an angle between a magnetic field generated by the first and second transmitting coils to the low-angle magnetic field plane is less than 15 degrees.
20. The wireless power transfer system of claim 19 , wherein an electronic component of the at least one electronic component is in the low-angle magnetic field plane.
21. The wireless power transfer system of claim 13 , comprising an LC resonant circuit corresponding to the first transmitting coil and comprising a first capacitor in the magnetic field shallow zone.
22. The wireless power transfer system of claim 21 , comprising a second LC resonant circuit corresponding to the second transmitting coil and comprising a second capacitor in the magnetic field shallow zone.
23. The wireless power transfer system of claim 13 , comprising an electronic device comprising a receiver coil.
24. A wireless power transfer system comprising a wireless power transfer device, the wireless power transfer device comprising:
a first transmitting coil oriented along a first axis;
a second transmitting coil above the first transmitting coil in an area of overlap between the first and second transmitting coils, and oriented along a second axis different from the first axis;
a nonmagnetic material magnetically decoupling the first transmitting coil from the second transmitting coil in the area of overlap between the first and second transmitting coils;
a first LC resonant circuit corresponding to the first transmitting coil; and
a second LC resonant circuit corresponding to the second transmitting coil.
25. The wireless power transfer system of claim 24 , wherein the first transmitting coil comprises a first rod and a first wire wound around the first rod, and the second transmitting coil comprises a second rod and a second wire wound around the second rod, and
wherein the first LC resonant circuit comprises the first wire and a first capacitor coupled in parallel with the first wire, and the second LC resonant circuit comprises the second wire and a second capacitor coupled in parallel with the second wire.
26. The wireless power transfer system of claim 25 , wherein the first LC resonant circuit further comprises a third capacitor coupled in series with the first capacitor and first wire, and the second LC resonant circuit further comprises a fourth capacitor coupled in series with the second capacitor and second wire.
27. The wireless power transfer system of claim 24 , wherein the wireless power transfer device comprises:
a coil assembly comprising the first transmitting coil, the second transmitting coil, the nonmagnetic material, the first LC resonant circuit, and the second LC resonant circuit; and
an electronics assembly comprising a driver to provide a first current to the first LC resonant circuit and a second current to the second LC resonant circuit, and
wherein the electronics assembly is spaced apart from the coil assembly.
28. The wireless power transfer system of claim 24 , comprising an electronic device comprising a receiver coil.