Apparatus, system, and method for detecting a foreign object in an inductive wireless power transfer system based on input power

• US 9,553,485 B2
• Filed: 03/30/2012
• Issued: 01/24/2017
• Est. Priority Date: 10/13/2011
• Status: Active Grant

• Current Assignee: Integrated Device Technology Incorporated (Renesas Electronics Corporation)
• Original Assignee: Integrated Device Technology Incorporated (Renesas Electronics Corporation)
• Inventors: Singh, Manjit, Bastami, Siamak
• Primary Examiner(s): Fureman, Jared
• Assistant Examiner(s): Perez Borroto, Alfonso
• Application Number:
  US13/436,309
• Publication Number:
  US 20130257168A1
• Time in Patent Office: 1,761 Days
• Field of Search: 307/104, 320/107
• US Class Current: 1/1
• CPC Class Codes: G01V 3/12 operating with electromagnetic waves operating with millimetre waves G01V8/005
• CPC Class Codes: H01F 38/14 Inductive couplings for wireless supply or distribution of electric power using inductive coupling H02J50/10
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 50/60 responsive to the presence of foreign objects, e.g. detection of living beings
• CPC Class Codes: H02J 50/80 involving the exchange of data, concerning supply or distribution of electric power, between transmitting devices and receiving devices
• CPC Class Codes: H02J 50/90 involving detection or optimisation of position, e.g. alignment

Abstract

An inductive wireless power transfer system comprises a transmitter configured to generate an electromagnetic field to a coupling region for providing energy transfer to a wireless power receiving apparatus. The transmitter includes control logic configured to determine a power component of the transmitter, and determine a presence of a foreign object within the coupling region in response to a comparison of the power component and a desired threshold for the power component. Related inductive methods for detecting a foreign object in an inductive wireless power transfer coupling region of an inductive wireless power transfer system and operating a sleep mode of a wireless power transmitter are disclosed.

Claims

1. An inductive wireless power transfer device, comprising:

a transmitter configured to generate an electromagnetic field to a coupling region for providing energy transfer to a wireless power receiving apparatus, wherein the transmitter includes control logic configured to;

determine a first input power of the transmitter from a ping generated during a sleep mode;

determine a presence of a foreign object within the coupling region in response to a comparison of the first input power to a first desired threshold;

reduce a frequency of the ping in response to determining the presence of the foreign object; and

transmit the ping at the reduced frequency.

2. The inductive wireless power transfer device of claim 1, wherein the first input power is one of a power value and a current value.

3. The inductive wireless power transfer device of claim 1, wherein the sleep mode is a non-continuous wireless power transfer state.

4. The inductive wireless power transfer device of claim 1, wherein the first input power is determined while there are no wireless power receiving devices within the coupling region.

5. The inductive wireless power transfer device of claim 1, wherein the first desired threshold is a value above an expected power value when no foreign object is present in the coupling region.

6. The inductive wireless power transfer device of claim 1, further comprising a wireless power charging device that includes the transmitter and the control logic.

7. The inductive wireless power transfer device of claim 1, further comprising an integrated circuit chip that includes the transmitter and the control logic.

8. The inductive wireless power transfer device of claim 1, wherein the transmitter further includes a power sense element configured to sense the first input power for the transmitter and transmit the first input power to the control logic.

9. The inductive wireless power transfer device of claim 8, wherein the power sense element is coupled to a transmit coil of the transmitter, the power sense element configured to measure a second input power for the transmit coil.

10. The inductive wireless power transfer device of claim 9, wherein the power sense element is coupled to an input power source of the transmitter and is configured to measure a voltage and current of the input power source of the transmitter.

11. The inductive wireless power transfer device of claim 1, wherein the control logic is further configured to:

when the first input power does not exceed the first desired threshold, exit the sleep mode to begin wireless power transfer during an active mode;

compare a second input power to a second desired threshold for the transmitter during the active mode; and

in response to the comparison, determine a presence of a foreign object within the coupling region when the second input power exceeds the second desired threshold during the active mode.

12. The inductive wireless power transfer device of claim 11, wherein the control logic is further configured to compare the first input power to a third threshold for the transmitter during the sleep mode and compare the second input power to a fourth threshold for the transmitter during the active mode.

13. The inductive wireless power transfer device of claim 12, wherein the control logic is further configured to:

disable the ping generated until the foreign object has been removed in response to a determination that the first input power exceeds the third threshold for the transmitter during the sleep mode; and

disable wireless power transfer until the foreign object has been removed in response to a determination that the second input power exceeds the fourth threshold for the transmitter during the active mode.

14. A method for detecting a foreign object in a coupling region of an inductive wireless power transfer device, the method comprising:

determining a first input power drawn by a wireless power transmitter during a ping generated during a sleep mode;

determining a presence of a foreign object within a coupling region of the wireless power transmitter based on a comparison of the first input power and a first desired threshold; and

reducing a frequency of the ping in response to determining the presence of the foreign object; and

transmit the ping at the reduced frequency.

15. The method of claim 14, wherein determining the first input power occurs when a wireless power receiver is determined to not be present in the coupling region.

16. The method of claim 14, wherein determining the presence of the foreign object comprises comparing the determined first input power with a plurality of desired thresholds.

17. The method of claim 14, further comprising reducing a pinging frequency of the wireless power transmitter during the sleep mode of the wireless power transmitter.

18. The method of claim 14, further comprising notifying a user in response to the determination of the presence of the foreign object.

19. The method of claim 14, further comprising:

comparing the first input power to a second threshold for the wireless power transmitter during the sleep mode;

when the first input power does not exceed the first desired threshold, exiting the sleep mode to begin wireless power transfer during an active mode;

comparing a second input power to a third desired threshold for the wireless power transmitter during the active mode;

in response to the comparison, determining a presence of a foreign object within the coupling region when the second input power exceeds the third desired threshold during the active mode; and

comparing the second input power to a fourth threshold for the wireless power transmitter during the active mode.

20. The method of claim 19, further comprising:

disabling the ping generated until the foreign object has been removed in response to a determination that the first input power exceeds the second threshold for the wireless power transmitter during the sleep mode; and

disabling wireless power transfer until the foreign object has been removed in response to a determination that the second input power exceeds the fourth threshold for the wireless power transmitter during the active mode.

21. A method of operating a sleep mode of a wireless power transmitter, the method comprising:

monitoring a first input power of a ping of a wireless power transmitter during a sleep mode;

comparing the first input power to a first desired threshold for the wireless power transmitter;

determining a presence of a foreign object in a coupling region of the wireless power transmitter responsive to the first input power exceeding the first desired threshold for the wireless power transmitter during the sleep mode;

reducing a frequency of the ping in response to determining the presence of the foreign object; and

transmit the ping at the reduced frequency.

22. The method of claim 21, further comprising waiting for a response period to receive a response from a wireless power receiver prior to determining the presence of the foreign object.

23. The method of claim 22, further comprising exiting the sleep mode responsive to receiving the response from the wireless power receiver during the response period.

24. The method of claim 21, further comprising adjusting time intervals between subsequent pings in response to determining the presence of a foreign object in the coupling region.

25. The method of claim 21, wherein monitoring the first input power occurs independently of a determination that a wireless power receiver is present in the coupling region.