Wireless power system with capacitive proximity sensing

• US 9,583,951 B2
• Filed: 10/05/2015
• Issued: 02/28/2017
• Est. Priority Date: 08/17/2012
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Von Novak, William Henry, Monat, Pavel, Kallal, Edward
• Primary Examiner(s): Deberadinis, Robert
• Application Number:
  US14/875,449
• Publication Number:
  US 20160028245A1
• Time in Patent Office: 512 Days
• Field of Search: 307/104
• US Class Current: 1/1
• CPC Class Codes: H02J 50/05 using capacitive coupling
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 50/40 using two or more transmitting or receiving devices H02J50/50 takes precedence
• CPC Class Codes: H02J 50/60 responsive to the presence of foreign objects, e.g. detection of living beings
• 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
• CPC Class Codes: H02J 7/00034 Charger exchanging data with an electronic device, i.e. telephone, whose internal battery is under charge
• CPC Class Codes: H04B 5/22 Capacitive coupling
• CPC Class Codes: H04B 5/79 for data transfer in combination with power transfer

Abstract

This disclosure provides systems, methods and apparatus for tuning a transmit coil for operation in a plurality of frequency bands. In one aspect, a method of wireless power transmission is provided. The method includes exciting a first part of a wireless power transmission system, via a wireless power transmitter. The method further includes detecting, in the presence of a non-charging object, a first change in a first parameter. The first parameter is indicative of a coupling between the non-charging object and the first part. The method further includes varying a characteristic of the wireless power transmission based on said first change.

Claims

1. A method of wireless power transmission comprising:

generating an electromagnetic field to wirelessly transfer power to a receive antenna, via a transmit antenna of a wireless power transmission system,

exciting a first non-transmitting part of the wireless power transmission system, which is coupled to the transmit antenna; and

detecting, in the presence of a non-charging object, a first change in a parameter indicative of a coupling between the non-charging object and the first non-transmitting part.

2. The method of claim 1, wherein the antenna excites the first non-transmitting part via capacitive coupling.

3. The method of claim 1, wherein the coupling between the non-charging object and the first non-transmitting part comprises capacitive coupling.

4. The method of claim 1, wherein the first non-transmitting part comprises a conducting plate.

5. The method of claim 1, wherein the non-charging object comprises at least one of:

a living object, and a parasitic receiver.

6. The method of claim 1, further comprising varying a characteristic of the wireless power transmission based on said change.

7. The method of claim 6, wherein the varied characteristic of the wireless power transmission comprises at least one of:

a transmit power, and a transmit frequency.

8. The method of claim 1, wherein said detecting the first change in the parameter indicative of the coupling between the non-charging object and the first non-transmitting part comprises:

in the absence of the non-charging object;

receiving a calibration input;

detecting an envelope of the calibration input; and

sampling the detected envelope of the calibration input; and

in the presence of the non-charging object;

receiving an input indicative of the coupling between the non-charging object and the first non-transmitting part;

detecting an envelope of input indicative of the coupling between the non-charging object and the first non-transmitting part; and

comparing the calibration input to the input indicative of the coupling between the non-charging object and the first non-transmitting part.

9. The method of claim 1, wherein said detecting the first change in the parameter indicative of the coupling between the non-charging object and the first non-transmitting part comprises:

receiving a reference input and an input indicative of the coupling between the non-charging object and the first non-transmitting part;

xoring the reference input with the input indicative of the coupling between the non-charging object and the first non-transmitting part;

integrating the xored inputs over alternate halves of a square wave cycle;

sampling the alternately integrated xored inputs at alternate halves of the square wave cycle; and

hysteretically comparing the alternately sampled, alternately integrated xored inputs.

10. The method of claim 1, further comprising:

exciting a second non-transmitting part of the wireless power transmission system, which is coupled to the transmit antenna;

detecting, in the presence of the non-charging object, a second change in a second parameter indicative of a coupling between the non-charging object and the second part; and

comparing said first and second changes to determine at least one of a location of said object, and an orientation of said object.

11. The method of claim 10, further comprising controlling a device input based on the determined location or orientation.

12. The method of claim 11, wherein the device input comprises at least one of:

a charging rate, a music control, a data synchronization, and a power control.

13. A system configured to provide wireless power transmission comprising:

a first non-transmitting part;

a transmit antenna configured to provide wireless power and to excite the first non-transmitting part coupled thereto; and

a circuit configured to detect, in the presence of a non-charging object, a first change in a parameter indicative of a coupling between the non-charging object and the first non-transmitting part.

14. The system of claim 13, wherein said circuit configured to detect the first change in the parameter indicative of the coupling between the non-charging object and the first non-transmitting part comprises:

an envelope detector configured to receive;

a calibration input, the absence of the non-charging object, and

an input indicative of the coupling between the non-charging object and the first non-transmitting part, in the presence of the non-charging object;

an envelope detector configured to;

detect an envelope of the calibration input, the absence of the non-charging object, and

detect an envelope of input indicative of the coupling between the non-charging object and the first non-transmitting part, in the presence of the non-charging object; and

a hysteretic comparator configured to compare the calibration input to the input indicative of the coupling between the non-charging object and the first non-transmitting part.

15. The system of claim 13, wherein said detecting the first change in the parameter indicative of the coupling between the non-charging object and the first non-transmitting part comprises:

a first inverter configured to receive a reference input;

a second inverter configured to receive an input indicative of the coupling between the non-charging object and the first non-transmitting part;

at least one xor gate configured to xor outputs of the first and second inverters;

a first and second integrator each configured to integrate an output of the at least one xor gate over alternate halves of a square wave cycle;

a first and second sample-and-hold circuit, each configured to sample an output of the first and second integrator, respectively, at alternate halves of the square wave cycle; and

a hysteretic comparator configured to compare outputs from the first and second sample-and-hold circuits.

16. The system of claim 13, further comprising:

exciting a second non-transmitting part of the wireless power transmission system, which is coupled to the transmit antenna;

detecting, in the presence of the non-charging object, a second change in a second parameter indicative of a coupling between the non-charging object and the second part; and

comparing said first and second changes to determine at least one of a location of said object, and an orientation of said object.

17. An apparatus for wireless power transmission comprising:

a first non-transmitting part;

means for transmitting wireless power and for exciting the first non-transmitting part coupled thereto; and

means for detecting a first change in a parameter indicative of a capacitive coupling between the non-charging object and the first non-transmitting part.

18. The apparatus of claim 17, wherein said means for detecting the first change in the parameter indicative of the coupling between the non-charging object and the first non-transmitting part comprises:

means for, in the absence of the non-charging object;

receiving a calibration input;

detecting an envelope of the calibration input; and

sampling the detected envelope of the calibration input; and

means for, in the presence of the non-charging object;

receiving an input indicative of the coupling between the non-charging object and the first non-transmitting part;

detecting an envelope of input indicative of the coupling between the non-charging object and the first non-transmitting part; and

comparing the calibration input to the input indicative of the coupling between the non-charging object and the first non-transmitting part.

19. The apparatus of claim 17, wherein said means for detecting the first change in the parameter indicative of the coupling between the non-charging object and the first non-transmitting part comprises:

means for receiving a reference input and an input indicative of the coupling between the non-charging object and the first non-transmitting part;

means for xoring the reference input with the input indicative of the coupling between the non-charging object and the first non-transmitting part;

means for integrating the xored inputs over alternate halves of a square wave cycle;

means for sampling the alternately integrated xored inputs at alternate halves of the square wave cycle; and

means for hysteretically comparing the alternately sampled, alternately integrated xored inputs.

20. The apparatus of claim 17, further comprising:

means for exciting a second non-transmitting part of the wireless power transmission system, which is coupled to the transmit antenna;

means for detecting, in the presence of the non-charging object, a second change in a second parameter indicative of a coupling between the non-charging object and the second part; and

means for comparing said first and second changes to determine at least one of a location of said object, and an orientation of said object.