Wireless power transfer metering

1. A system for measuring wireless power transfer between a transmitter and a receiver, the system comprising:

a sensor circuit comprising a a plurality of sensors, each sensor of the plurality of sensors being configured and positioned relative to the transmitter and the receiver to generate sensor data indicative of transfer power propagating from the transmitter to the receiver in connection with the wireless power transfer; and

a processor coupled to the sensor circuit and configured to determine a power measurement of the transfer power based on the sensor data.

2. The system of claim 1 , wherein each sensor of the plurality of sensors is positioned between the transmitter and the receiver.

3. The system of claim 1 , wherein the processor is configured to determine the power measurement using pair-wise products of the plurality of sensors.

4. The system of claim 1 , wherein each sensor of the plurality of sensors includes a respective capacitive sense plate such that the transfer power propagates via an electric field.

5. The system of claim 1 , wherein each sensor of the plurality of sensors comprises a sense coil.

6. The system of claim 1 , wherein the transfer power propagates via a magnetic field.

7. The system of claim 1 , wherein the processor is further configured to determine a misalignment of the transmitter or the receiver, and to correct an estimate of the power measurement based on the misalignment.

8. The system of claim 1 , wherein the power measurement is indicative of real power.

9. The system of claim 1 , wherein the processor is configured to determine the power measurement via frequency domain computations.

10. The system of claim 1 , wherein the processor is configured to determine the power measurement via binning in the frequency domain.

11. The system of claim 1 , wherein the processor is configured to determine the power measurement via time domain computations.

12. The system of claim 1 , wherein the sensor circuit is configured such that the sensor data disaggregates inefficiencies of the transmitter and inefficiencies of the receiver.

13. The system of claim 1 , wherein the sensor circuit is configured such that the sensor data excludes losses from the transmitter and losses from the receiver.

14. The system of claim 1 , wherein:

the transfer power involves a field generated by the transmitter and a field generated by the receiver; and

the sensor circuit is configured such that the plurality of sensors resolve the field generated by the transmitter and the field generated by the receiver.

15. A method of measuring wireless power transfer between a transmitter and a receiver, the method comprising:

capturing field data with a plurality of sensors, each sensor of the plurality of sensors being configured and positioned relative to the transmitter and the receiver such that the field data is indicative of transfer power propagating from the transmitter to the receiver in connection with the wireless power transfer; and

determining a power measurement of the transfer power based on the field data.

16. The method of claim 15 , further comprising positioning each sensor of the plurality of sensors between the transmitter and the receiver.

17. The method of claim 15 , wherein determining the power measurement comprises determining a misalignment of the transmitter or the receiver.

18. The method of claim 17 , wherein determining the power measurement further comprises correcting the power measurement based on the misalignment.

19. The method of claim 15 , wherein determining the power measurement comprises binning in the frequency domain.

20. The method of claim 15 , wherein capturing the field data with the plurality of sensors disaggregates inefficiencies of the transmitter and inefficiencies of the receiver.

21. The method of claim 15 , wherein capturing the field data with the plurality of sensors excludes losses from the transmitter and losses from the receiver.

22. The method of claim 15 , wherein:

the transfer power involves a field generated by the transmitter and a field generated by the receiver; and

capturing the field data with the plurality of sensors resolves the field generated by the transmitter and the field generated by the receiver.

23. A method of calibrating a wireless power transfer measurement device, the method comprising:

positioning a test receiver relative to a transmitter and the wireless power transfer measurement device;

capturing field data for a load impedance with the wireless power transfer measurement device;

determining a power measurement based on the field data; and

determining a plurality of calibration factors for the wireless power transfer measurement device based on the power measurement.

24. The method of claim 23 , wherein capturing the field data comprises varying a load impedance of the test receiver.

25. The method of claim 23 , wherein capturing the field data comprises varying a load resistance of the test receiver.

26. The method of claim 23 , wherein determining the plurality of calibration factors comprises performing an optimization to minimize measurement error.

27. The method of claim 23 , wherein determining the plurality of calibration factors comprises performing a least squares approximation.

28. The method of claim 23 , wherein capturing the field data comprises positioning multiple sense coils relative to the transmitter and the wireless power transfer measurement device.

29. The method of claim 28 , wherein capturing the field data comprises approximating a misalignment over multiple positions of the multiple sense coils.

30. The method of claim 28 , wherein determining the power measurement comprises using pair-wise products of the multiple sense coils.