Wireless power transfer for low power devices

• US 9,425,642 B2
• Filed: 08/01/2014
• Issued: 08/23/2016
• Est. Priority Date: 02/12/2009
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Toncich, Stanley Slavko, Ozaki, Ernest T.
• Primary Examiner(s): Muralidar, Richard V
• Application Number:
  US14/450,083
• Publication Number:
  US 20140340036A1
• Time in Patent Office: 753 Days
• Field of Search: 320/108
• US Class Current: 1/1
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 50/20 using microwaves or radio frequency waves
• CPC Class Codes: H02J 50/90 involving detection or optimisation of position, e.g. alignment
• CPC Class Codes: H02J 7/00 Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries

Abstract

Exemplary embodiments are directed to wireless power transfer. A method of operating a wireless receiver may comprise receiving wireless power with a receive antenna and conveying power from the receive antenna to a chargeable element. The method may further include electrically isolating the receive antenna from the chargeable element upon detecting that the chargeable element is fully-charged.

Claims

1. A wireless power receiver, comprising:

a receiver circuit selectively coupled to a chargeable element and configured to receive wireless power from a transmit antenna of a wireless power transmitter at a level sufficient to charge the chargeable element; and

a switching device operably coupled between the receiver circuit and the chargeable element and configured to disconnect the receiver circuit from the chargeable element.

2. The wireless power receiver of claim:

1, wherein the switching device comprises a field effect transistor.

3. The wireless power receiver of claim 1, wherein the wireless power transmitter is configured to monitor an amount of current being drawn from the transmit antenna by the receiver circuit, determine if the amount of current being drawn by the receiver circuit is less than a threshold level, and discontinue wireless transmission of power in response to the amount of current being drawn by the receiver circuit being less than the threshold level.

4. The wireless power receiver of claim 1, further comprising a controller operably coupled to the switching device and configured to transmit one or more control signals to the switching device to control a configuration of the switching device.

5. The wireless power receiver of claim 1, further comprising a controller configured to determine a charging level status of the chargeable element and monitor the charging level status of the chargeable element.

6. The wireless power receiver of claim 1, further comprising a controller configured to determine that the chargeable element is in a substantially fully-charged state and electrically isolate the receiver circuit from the chargeable element.

7. The wireless power receiver of claim 1, further comprising a controller configured to transmit the one or more control signals to the switching device to establish a connection between the receiver circuit and the chargeable element, the connection configured to supply power from the receiver circuit to the chargeable element.

8. The wireless power receiver of claim 1, further comprising a sensor operably coupled between the receiver circuit and the chargeable element and configured to sense an amount of current being supplied to the chargeable element, or sense a voltage of a power signal being supplied to the chargeable element, or any combination thereof.

9. The wireless power receiver of claim 8, wherein the sensor is configured to transmit a status signal to the controller indicative of a parameter sensed by the sensor and the controller is configured to determine the charging level status of the chargeable element based on the parameter sensed by the sensor.

10. The wireless power receiver of claim 9, wherein the status signal is indicative of the amount of current being supplied to the chargeable element or the voltage of the power signal.

11. The wireless power receiver of claim 1, further comprising:

a receive antenna configured to receive the wireless power; and

a rectifier operably coupled between the receive antenna and the switching device.

12. A method for receiving wireless power, comprising:

receiving wireless power with a receiver circuit at a level sufficient to charge a chargeable element;

conveying power from the receive antenna to the chargeable element; and

disconnecting the receiver circuit from the chargeable element upon detecting that the chargeable element is in a substantially fully-charged state.

13. The method of claim 12, wherein disconnecting the receiver circuit from the chargeable element comprises electrically isolating the receiver circuit from the chargeable device.

14. The method of claim 12, wherein disconnecting the receiver circuit from the chargeable element comprises disconnecting a connection between the receiver circuit and the chargeable element using a switching device operably coupled between the receiver circuit and the chargeable element.

15. The method of claim 12, further comprising establishing a connection between the receiver circuit and the chargeable element upon detecting that the chargeable element is in a less than fully-charged state.

16. The method of claim 12, further comprising sensing at least one of an amount of current being supplied to the chargeable element from the conveyed power and a voltage of a power signal of the conveyed power.

17. The method of claim 12, further comprising transmitting a status signal to a controller indicative of a parameter sensed by a sensor operably coupled between the receiver circuit and the chargeable element.

18. The method of claim 12, further comprising transmitting one or more control signals from a controller to a switching device operably coupled between the receiver circuit and the chargeable element to electrically isolate the receiver circuit from the chargeable element.

19. A wireless power device, the device comprising:

means for receiving wireless power at a level sufficient to charge a chargeable element;

means for conveying power to the chargeable element; and

means for disconnecting the receiving means from the chargeable element upon detecting that the chargeable element is in a substantially fully-charged state.

20. The wireless power device of claim 19, further comprising means for sensing at least one of an amount of current being supplied to the chargeable element from the conveyed power and a voltage of a power signal of the conveyed power.

21. The wireless power device of claim 19, further comprising means for establishing a connection between the receiving means and the chargeable element upon detecting that the chargeable element is in a less than fully-charged state.