Wireless power transmission
Techniques for modifying the electrical current distribution of transmit coil of a wireless power transmitting unit are described. An example power transmitting unit includes a transmit coil configured to generate a magnetic field to wirelessly power a device within an active wireless charging area. The power transmitting unit can also include a power source to transmit an alternating electrical current to an input terminal of the transmit coil and a plurality of reactive elements placed in series with the transmit coil. In some examples, the plurality of reactive elements attach to the transmit coil at least a quarter of a turn from the input terminal. The power transmitting unit can also include a controller to modify a reactance value of the reactive elements to adjust a current distribution of the transmit coil in response to detecting a characteristic of a power receiving unit.
1. A power transmitting unit, comprising:
a transmit coil configured to generate a magnetic field to wirelessly power a device within an active wireless charging area;
a power source to transmit an alternating electrical current (A/C) to an input terminal of the transmit coil;
a plurality of reactive elements placed in series with the transmit coil, wherein the plurality of reactive elements attach to the transmit coil at least a quarter of a turn from the input terminal; and
a controller to modify a reactance value of the reactive elements to adjust a current distribution of the transmit coil in response to detecting a characteristic of a power receiving unit, wherein the characteristic of the power receiving unit comprises a metal backing and modifying the reactance value comprises opening or closing a number of the reactive elements proximate a center of the transmit coil to adjust the current distribution, the controller to further establish a wireless communication with the power receiving unit, the wireless communication comprising data indicating a size of the device to be wirelessly powered and a wireless charging capability of the device.
2. The power transmitting unit of claim 1 , wherein the input terminal attaches to the center of the transmit coil.
3. The power transmitting unit of claim 2 , wherein the plurality of reactive elements attach to the transmit coil at an edge of the transmit coil.
4. The power transmitting unit of claim 1 , wherein the input terminal of the transmit coil attaches to an outer edge of the transmit coil.
5. The power transmitting unit of claim 4 , wherein the plurality of reactive elements of the transmit coil attach to the center of the transmit coil.
6. The power transmitting unit of claim 1 , wherein the plurality of reactive elements comprise a plurality of fixed capacitors, inductors, tunable inductors, or tunable capacitors.
7. The power transmitting unit of claim 1 , wherein the plurality of reactive elements connect to the transmit coil at a plurality of symmetric locations.
8. The power transmitting unit of claim 1 , wherein the characteristic of the power receiving unit comprises a size of the power receiving unit, or a coupling distance between the power transmitting unit and the power receiving unit.
9. A method of manufacturing a power transmitting unit, comprising:
forming a transmit coil configured to generate a magnetic field to wirelessly power a device within an active wireless charging area;
conductively coupling a power source to transmit an alternating electrical current to an input terminal of the transmit coil;
conductively coupling a plurality of reactive elements placed in series with the transmit coil, wherein the plurality of reactive elements attach to the transmit coil at least a quarter of a turn from the input terminal; and
conductively coupling a controller to the transmit coil to modify a reactance value of the reactive elements to adjust a current distribution of the transmit coil in response to detecting a characteristic of a power receiving unit, wherein the characteristic of the power receiving unit comprises a metal backing and modifying the reactance value comprises opening or closing a number of the reactive elements proximate a center of the transmit coil to adjust the current distribution, the controller to further establish a wireless communication with the power receiving unit, the wireless communication comprising data indicating a size of the device to be wirelessly powered and a wireless charging capability of the device.
10. The method of claim 9 , wherein the input terminal attaches to the center of the transmit coil.
11. The method of claim 10 , wherein the plurality of reactive elements of the transmit coil attach to an edge of the transmit coil.
12. The method of claim 9 , wherein the input terminal of the transmit coil attaches to an outer edge of the transmit coil.
13. The method of claim 12 , wherein the plurality of reactive elements of the transmit coil attach to the center of the transmit coil.
14. The method of claim 9 , wherein the plurality of reactive elements comprise fixed capacitors, inductors, tunable inductors, or tunable capacitors.
15. The method of claim 9 , wherein the plurality of reactive elements connect to the transmit coil at a plurality of symmetric locations.
16. The method of claim 9 , wherein the characteristic of the power receiving unit comprises a size of the power receiving unit, or a coupling distance between the power transmitting unit and the power receiving unit.
17. A wireless charger, comprising:
a transmit coil configured to generate a magnetic field to wirelessly power a device within an active wireless charging area;
a power source to transmit an alternating electrical current to an input terminal of the transmit coil;
a plurality of reactive elements placed in series with the transmit coil, wherein the plurality of reactive elements attach to the transmit coil at least a quarter of a turn from the input terminal; and
a controller to modify a reactance value of the plurality of reactive elements to adjust a current distribution of the transmit coil in response to detecting a characteristic of a power receiving unit with a metal backing, the characteristic comprising a size of the power receiving unit, or a coupling distance between the power transmitting unit and the power receiving unit, wherein modifying the reactance value comprises opening or closing a number of the reactive elements proximate a center of the transmit coil to adjust the current distribution, the controller to further establish a wireless communication with the power receiving unit, the wireless communication comprising data indicating a size of the device to be wirelessly powered and a wireless charging capability of the device.
18. The wireless charger of claim 17 , wherein the input terminal attaches to the center of the transmit coil.
19. The wireless charger of claim 18 , wherein the plurality of reactive elements attach to an edge of the transmit coil.
20. The wireless charger of claim 17 , wherein the input terminal of the transmit coil attaches to an outer edge of the transmit coil.
21. The wireless charger of claim 20 , wherein the plurality of reactive elements attach to the center of the transmit coil.