Dynamic inferred coupling estimation

1. A method for operating a wireless charging device, comprising:

transmitting a first pulse through a power transmitting coil in each of a plurality of charging circuits;

determining peak voltage at nodes in the plurality of charging circuits, each node coupling a power transmitting coil to a corresponding capacitor in one charging circuit in the plurality of charging circuits, the peak voltage at each node being responsive to the first pulse and indicative of a coupling coefficient between the corresponding power transmitting coil and a receiving coil in a chargeable device;

determining that a node having a minimum peak voltage responsive to the first pulse is associated with a first charging circuit in the plurality of charging circuits; and

providing a first charging current to the first charging circuit.

2. The method of claim 1 , wherein peak voltage at each node is representative of a leakage inductance of a corresponding charging circuit.

3. The method of claim 1 , further comprising:

detecting that voltage at the node in the first charging circuit exceeds a threshold voltage while providing the first charging current to the first charging circuit;

transmitting a second pulse through a power transmitting coil in one or more other charging circuits in the plurality of charging circuits;

determining that a minimum peak voltage responsive to the second pulse is associated with a second charging circuit in the plurality of charging circuits; and

providing a second charging current to the second charging circuit.

4. The method of claim 3 , further comprising:

discontinuing the first charging current when providing the second charging current to the second charging circuit.

5. The method of claim 3 , further comprising:

redirecting at least a portion of the first charging current to the second charging circuit as the second charging current.

6. The method of claim 1 , further comprising:

reducing the first charging current after detecting that voltage at the node in the first charging circuit exceeds a threshold voltage while providing the first charging current to the first charging circuit;

increasing the first charging current when a message requesting power increase is received from the chargeable device; and

discontinuing the first charging current when the message requesting power increase is not received from the chargeable device.

7. The method of claim 6 , further comprising:

decoding the message requesting power increase from an amplitude shift keyed signal received through the first charging circuit.

8. The method of claim 1 , further comprising:

determining that a chargeable device is located proximate to at least one power transmitting coil associated with the plurality of charging circuits, wherein the first pulse is transmitted responsive to determination of proximity of the chargeable device.

9. The method of claim 8 , further comprising:

detecting an increase in voltage at the node in the first charging circuit while providing the first charging current to the first charging circuit; and

determining that location of the chargeable device has changed when the voltage at the node in the first charging circuit exceeds a threshold voltage.

10. A charging device, comprising:

a plurality of charging circuits, each charging circuit including a power transmitting coil and a capacitor coupled at a node;

a driver circuit configurable to provide a charging current to one or more charging circuits in the plurality of charging circuits; and

a controller configured to:

cause a first pulse to be transmitted through a power transmitting coil in each of the plurality of charging circuits;

determine peak voltage at each of the nodes in the plurality of charging circuits, the peak voltage at each node being responsive to the first pulse and indicative of a coupling coefficient between the corresponding power transmitting coil and a receiving coil in a chargeable device;

determine that a node having a minimum peak voltage responsive to the first pulse is associated with a first charging circuit in the plurality of charging circuits; and

configure the driver circuit to provide a first charging current to the first charging circuit.

11. The charging device of claim 10 , wherein the controller is further configured to:

detect that voltage at the node in the first charging circuit exceeds a threshold voltage while providing the first charging current to the first charging circuit;

cause a second pulse to be transmitted through a power transmitting coil in one or more other charging circuits in the plurality of charging circuits;

determine that a minimum peak voltage responsive to the second pulse is associated with a second charging circuit in the plurality of charging circuits; and

configure the driver circuit to provide a second charging current to the second charging circuit.

12. The charging device of claim 11 , wherein the controller is further configured to:

configure the driver circuit to discontinue the first charging current when providing the second charging current to the second charging circuit.

13. The charging device of claim 11 , wherein the controller is further configured to:

configure the driver circuit to redirect at least a portion of the first charging current to the second charging circuit as the second charging current.

14. The charging device of claim 10 , wherein the controller is further configured to:

configure the driver circuit to reduce the first charging current after detecting that voltage at the node in the first charging circuit exceeds a threshold voltage while providing the first charging current to the first charging circuit;

configure the driver circuit to increase the first charging current when a message requesting power increase is received from the chargeable device; and

configure the driver circuit to discontinue the first charging current when the message requesting power increase is not received from the chargeable device.

15. The charging device of claim 14 , further comprising:

an amplitude shift keying demodulator configured to decode the message requesting power increase from a signal received through the first charging circuit.

16. The charging device of claim 10 , wherein the controller is further configured to:

determine that a chargeable device is located proximate to at least one power transmitting coil associated with the plurality of charging circuits, wherein the first pulse is transmitted responsive to determination of proximity of the chargeable device;

detect an increase in voltage at the node in the first charging circuit while providing the first charging current to the first charging circuit; and

determine that location of the chargeable device has changed when the voltage at the node in the first charging circuit exceeds a threshold voltage.

17. A processor-readable storage medium having instructions stored thereon which, when executed by at least one processor of a charging circuit, cause the charging circuit to:

transmit a first pulse through a power transmitting coil in each of a plurality of charging circuits;

determine peak voltage at nodes in the plurality of charging circuits, each node coupling a power transmitting coil to a corresponding capacitor in one charging circuit in the plurality of charging circuits, the peak voltage at each node being responsive to the first pulse and indicative of a coupling coefficient between the corresponding power transmitting coil and a receiving coil in a chargeable device;

determine that a node having a minimum peak voltage responsive to the first pulse is associated with a first charging circuit in the plurality of charging circuits; and

provide a first charging current to the first charging circuit.

18. The processor-readable storage medium of claim 17 , wherein the instructions cause the charging circuit to:

detect that voltage at the node in the first charging circuit exceeds a threshold voltage while providing the first charging current to the first charging circuit;

transmit a second pulse through a power transmitting coil in one or more other charging circuits in the plurality of charging circuits;

determine that a minimum peak voltage responsive to the second pulse is associated with a second charging circuit in the plurality of charging circuits; and

provide a second charging current to the second charging circuit.

19. The processor-readable storage medium of claim 18 , wherein the instructions cause the charging circuit to:

redirect at least a portion of the first charging current to the second charging circuit as the second charging current.

20. The processor-readable storage medium of claim 17 , wherein the instructions cause the charging circuit to:

reduce the first charging current after detecting that voltage at the node in the first charging circuit exceeds a threshold voltage while providing the first charging current to the first charging circuit;

increase the first charging current when a message requesting power increase is received from the chargeable device; and

discontinue the first charging current when the message requesting power increase is not received from the chargeable device.