Methods and systems for multi-phase coil control
Certain aspects of the present disclosure provide methods and apparatus for multi-phase coil control in power transfer systems. One example power transfer device generally includes a plurality of coils configured to generate at least one charging field, the plurality of coils comprising a first coil and a second coil, and a controller configured to identify that a coupling factor between the first coil and a third coil, which is external to the power transfer device, is at or below a threshold, and to adjust, based on the identification, one or more parameters associated with a current applied to the first coil to transfer power from the first coil to the second coil.
1. A power transfer device for wireless charging, comprising:
a plurality of coils configured to generate at least one charging field, the plurality of coils comprising a first coil and a second coil; and
a controller configured to:
identify that a coupling factor between the first coil and a third coil, which is external to the power transfer device, is at or below a predetermined threshold; and
adjust, based on the identification, one or more parameters associated with a current applied to the first coil to transfer power from the first coil to the second coil.
2. The power transfer device of claim 1 , wherein the one or more parameters comprise at least one of a magnitude of the current applied to the first coil or a phase of the current applied to the first coil.
3. The power transfer device of claim 2 , wherein the controller is configured to select the phase and the magnitude of the current to reduce a signal induced in the second coil from a field generated by the third coil.
4. The power transfer device of claim 2 , further comprising a power converter coupled to the second coil, and wherein the controller is configured to select the phase and the magnitude of the current to reduce an additional current supplied by the power converter to the second coil.
5. The power transfer device of claim 1 , wherein the controller is configured to adjust one or more additional parameters associated with an additional current applied to the second coil.
6. The power transfer device of claim 5 , wherein the one or more additional parameters comprise at least one of a magnitude of the additional current applied to the second coil or a phase of the additional current applied to the second coil.
7. The power transfer device of claim 6 , wherein the controller is configured to select the phase and the magnitude of the additional current to reduce a signal induced in the second coil from a field generated by the third coil.
8. The power transfer device of claim 1 , wherein the controller is configured to:
identify that an additional coupling factor between the first coil and the second coil is at or above an additional predetermined threshold, and
adjust the one or more parameters based on the identification of the additional coupling factor being at or above the additional predetermined threshold.
9. The power transfer device of claim 1 , wherein the first coil is configured for operation with a different phase than the second coil.
10. The power transfer device of claim 1 , wherein the predetermined threshold represents a value that enables the controller to determine whether mutual coupling between the first coil and the third coil is sufficient to transfer power between the first coil and the third coil.
11. A method of wireless power transfer, comprising:
identifying that a coupling factor between a first coil and a third coil, which is external to a power transfer device comprising the first coil, is at or below a predetermined threshold;
adjusting, based on the identification, one or more parameters associated with a first current applied to the first coil to transfer power from the first coil to a second coil; and
applying the first current with the one or more parameters to the first coil and a second current to the second coil to generate at least one charging field that transfers power from the second coil to the third coil.
12. The method of claim 11 , wherein the one or more parameters comprise at least one of a magnitude of the first current applied to the first coil or a phase of the first current applied to the first coil.
13. The method of claim 12 , wherein adjusting the one or more parameters comprises selecting the phase and the magnitude of the first current to reduce a signal induced in the second coil from a field generated by the third coil.
14. The method of claim 12 , wherein adjusting the one or more parameters comprises selecting the phase and the magnitude of the first current to reduce the second current supplied by a power converter to the second coil.
15. The method of claim 11 , further comprising:
adjusting one or more additional parameters associated with the second current applied to the second coil, wherein applying the second current comprises applying the second current with the additional one or more parameters to the second coil.
16. The method of claim 15 , wherein the one or more additional parameters comprise at least one of a magnitude of the second current applied to the second coil or a phase of the second current applied to the second coil.
17. The method of claim 16 , wherein adjusting the one or more additional parameters comprises selecting the phase and the magnitude of the second current to reduce a signal induced in the second coil from a field generated by the third coil.
18. The method of claim 11 , further comprising:
identifying that an additional coupling factor between the first coil and the second coil is at or above an additional predetermined threshold, wherein adjusting the one or more parameters comprises adjusting the one or more parameters based on the identification of the additional coupling factor being at or above the additional predetermined threshold.
19. The method of claim 11 , wherein the first current has a different phase than the second current.
20. The method of claim 11 , wherein the predetermined threshold comprises a value that enables a determination of whether the first coil and the third coil have sufficient mutual coupling to transfer power between the first coil and the third coil.
21. An apparatus for wirelessly transferring power, comprising:
means for identifying that a coupling factor between a first coil and a third coil is at or below a predetermined threshold, the apparatus comprising the first coil, the third coil being external to the apparatus;
means for adjusting, based on the identification, one or more parameters associated with a first current applied to the first coil to enable power to be transferred from the first coil to a second coil of the apparatus; and
means for applying the first current with the one or more adjusted parameters to the first coil and a second current to the second coil to generate a first charging field that transfers power from the first coil to the second coil and a second charging field that transfers power from the second coil to the third coil.
22. The apparatus of claim 21 , wherein the one or more parameters comprise at least one of a magnitude of the current applied to the first coil or a phase of the current applied to the first coil.
23. The apparatus of claim 21 , wherein the predetermine threshold represents a value usable to determine whether the first coil and the third coil have sufficient mutual coupling for transferring power between the first coil and the third coil.