Wireless power system with power control

1. A wireless power transmitting device configured to transmit wireless power to a wireless power receiving device, comprising:

wireless power transmitting circuitry configured to transmit an amount of the wireless power to the wireless power receiving device; and

control circuitry configured to:

gather measurements of wireless power transmitting device operating parameters in the wireless power transmitting circuitry;

estimate in real time a wireless power receiving device operating parameter of the wireless power receiving device using the gathered measurements; and

adjust the amount of wireless power being transmitted using the estimate.

2. The wireless power transmitting device of claim 1 wherein the wireless power receiving device comprises wireless power receiving circuitry with a coil and a rectifier coupled to the coil and wherein the wireless power receiving device operating parameter comprises a rectifier current associated with the rectifier.

3. The wireless power transmitting device of claim 2 wherein the control circuitry is configured to estimate the rectifier current in real time based at least partly on an inductance value for the coil.

4. The wireless power transmitting device of claim 3 wherein the control circuitry is configured to receive the inductance value from the wireless power receiving device over an in-band communications link between the wireless power receiving device and the wireless power transmitting device.

5. The wireless power transmitting device of claim 4 wherein the control circuitry is configured to estimate the rectifier current in real time based at least partly on a capacitance value for a capacitor coupled in series with the coil in the wireless power receiving device.

6. The wireless power transmitting device of claim 1 wherein the wireless power receiving device has a rectifier that draws a rectifier current during wireless power transfer, wherein the control circuitry is configured to estimate the rectifier current in real time based at least partly on:

a first capacitance value for a first capacitor coupled in series with a wireless power transmitting coil in the wireless power transmitting circuitry; and

a second capacitance value for a second capacitor coupled in series with a wireless power receiving coil coupled to the rectifier.

7. The wireless power transmitting device of claim 1 wherein the control circuitry is configured to adjust the amount of wireless power by adjusting an inverter in the wireless power transmitting circuitry.

8. The wireless power transmitting device of claim 1 wherein the control circuitry is configured to adjust the amount of power based on received wireless power adjustment commands from the wireless power receiving device.

9. The wireless power transmitting device of claim 1 wherein the wireless power transmitting circuitry includes a wireless power transmitting coil, wherein the wireless power transmitting device operating parameters comprise a wireless power transmitting coil current for the wireless power transmitting coil and a wireless power transmitting coil voltage for the wireless power transmitting coil, wherein the wireless power receiving device operating parameter comprises rectifier current for a rectifier in the wireless power receiving device, and wherein the control circuitry is configured to:

estimate the rectifier current based on the wireless power transmitting coil voltage and the wireless power transmitting coil current; and

adjust the amount of power being transmitted using the estimate of the rectifier current.

10. The wireless power transmitting device of claim 1 wherein the wireless power transmitting circuitry includes a wireless power transmitting coil that draws a wireless power transmitting coil current and operates at a wireless power transmitting coil voltage, wherein when a load transient occurs in the wireless power receiving device, the load transient affects the wireless power transmitting coil current and the wireless power transmitting coil voltage, wherein the wireless power transmitting device operating parameters comprise the wireless power transmitting coil voltage and the wireless power transmitting coil current, and wherein the control circuitry is configured to monitor the wireless power receiving device operating parameter for changes due to the load transient by estimating the wireless power receiving device operating parameter based on the wireless power transmitting coil current and the wireless power transmitting coil voltage.

11. The wireless power transmitting device of claim 1 wherein the wireless power receiving device comprises wireless power receiving circuitry and wherein the wireless power receiving circuitry comprises:

a wireless power receiving device coil with a wireless power receiving device coil inductance;

a capacitor having a capacitance; and

a rectifier with a rectifier current,

wherein the wireless power receiving device operating parameter comprises the rectifier current, and

wherein the control circuitry is configured to estimate the rectifier current based on the wireless power transmitting device operating parameters and the capacitance, the inductance, and the rectifier current.

12. A wireless power transmitting device configured to transmit wireless power to a wireless power receiving device, comprising:

wireless power transmitting circuitry having an inverter coupled to a wireless power transmitting coil, wherein the wireless power transmitting circuitry is configured to transmit an amount of the wireless power to the wireless power receiving device; and

control circuitry configured to detect when a load transient has occurred in the wireless power receiving device from measurements of a wireless power transmitting coil voltage and a wireless power transmitting coil current at the wireless power transmitting coil.

13. The wireless power transmitting device of claim 12 wherein the control circuitry is configured to detect when the load transient has occurred by estimating an operating parameter in the wireless power receiving device using the wireless power transmitting coil voltage and the wireless power transmitting coil current.

14. The wireless power transmitting device of claim 13 wherein the operating parameter comprises a rectifier current of a rectifier in the wireless power receiving device.

15. The wireless power transmitting device of claim 14 wherein the control circuitry is configured to adjust the amount of wireless power being transmitted to the wireless power receiving device with the wireless power transmitting circuitry based on an inductance of the wireless power transmitting coil and an inductance of a wireless power receiving device coil in the wireless power receiving device.

16. A wireless power transmitting device configured to transmit wireless power to a wireless power receiving device, comprising:

wireless power transmitting circuitry having an inverter coupled to a wireless power transmitting coil, wherein the wireless power transmitting circuitry is configured to transmit an amount of the wireless power to the wireless power receiving device; and

control circuitry configured to:

measure a wireless power transmitting coil voltage of the wireless power transmitting coil;

measure a wireless power transmitting coil current of the wireless power transmitting coil;

estimate a current flowing in the wireless power receiving device using the measured wireless power transmitting coil voltage and the wireless power transmitting coil current; and

adjust the amount of wireless power being transmitted based on the estimation of the current.

17. The wireless power transmitting device of claim 16 wherein the wireless power receiving device comprises a wireless power receiving coil and a rectifier coupled to the wireless power receiving coil and wherein the current comprises a rectifier current flowing through the rectifier.

18. The wireless power transmitting device of claim 16 wherein the control circuitry is configured to estimate the current flowing in the wireless power receiving device based on a capacitance in the wireless power receiving device and an inductance of the wireless power transmitting coil.

19. The wireless power transmitting device of claim 16 wherein the control circuitry is configured to estimate the current flowing in the wireless power receiving device based on:

an inductance value of the wireless power transmitting coil;

an inductance value of a wireless power receiving coil in the wireless power receiving device; and

a mutual inductance between the wireless power transmitting coil and the wireless power receiving coil.

20. The wireless power transmitting device of claim 19 wherein the mutual inductance is calculated using a coupling coefficient value and wherein the control circuitry is configured to periodically update the coupling coefficient value.