DEVICE DETECTION THROUGH DYNAMIC IMPEDANCE CHANGE MEASUREMENT

• US 20150233987A1
• Filed: 09/15/2014
• Published: 08/20/2015
• Est. Priority Date: 02/14/2014
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Von Novak, William Henry III, Wheeland, Cody Burton
• Granted Patent: US 9,995,777 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01R 27/08 Measuring resistance by measuring both voltage and current
• CPC Class Codes: G01R 31/40 Testing power supplies testing photovoltaic devices H02S50/10
• 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
• 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

Abstract

This disclosure provides systems, methods, and apparatuses for detecting placement of a wireless power receiver in a charging region of a wireless power transmitter. For example, the apparatus may include a transmit circuit comprising a transmit coil and be configured to wirelessly transmit power via a wireless filed applied to the charging region to a receive coil of the receiver. The apparatus may also include a detection circuit configured to detect a characteristic waveform resulting from the field that is applied to the charging region or changed between the transmit and receive coils, in response to the receiver being placed in the charging region.

Claims

1. A device for detecting placement of a wireless power receiver in a charging region of a wireless power transmitter, comprising:

a transmit circuit comprising a transmit coil and configured to wirelessly transmit power via a wireless field applied to the charging region to a receive coil of the receiver; and

a detection circuit configured to detect a characteristic waveform resulting from the field that is applied to the charging region or changed between the transmit and receive coils, in response to the receiver being placed in the charging region.

2. The device of claim 1, wherein the characteristic waveform is associated with a charging of a capacitor of the receiver during initial application of the field, and is based at least in part on a change in impedance presented to the transmit circuit of the transmitter in response to the receiver being placed in the charging region.

3. The device of claim 1, wherein the characteristic waveform is indicative of an impedance change pattern associated with a charging of a capacitor of the receiver during initial application of the field.

4. The device of claim 1, wherein the characteristic waveform comprises a transient spike in a transmitter current.

5. The device of claim 4, wherein the transmitter current comprises a DC current into a power amplifier (PA) of the transmitter.

6. The device of claim 1, wherein the characteristic waveform comprises a transient spike or oscillation in a transmitter voltage.

7. The device of claim 6, wherein the transmitter voltage comprises a DC voltage supplied to a power amplifier (PA) of the transmitter.

8. The device of claim 1, wherein the characteristic waveform comprises a transient spike in resistance as calculated based on a transmitter voltage and a transmitter current.

9. The device of claim 8, wherein the transmitter voltage comprises an AC voltage and the transmitter current comprises an AC current.

10. The device of claim 9, wherein the AC voltage and the AC current are measured at substantially a same point in an AC path.

11. The device of claim 9, wherein the AC current is measured at a first point in an AC path, the AC current having a known relation to, in at least one of amplitude or phase, a corresponding AC current measured at a second point in the AC path where the AC voltage is measured.

12. The device of claim 8, wherein the transmitter voltage comprises a DC voltage and the transmitter current comprises a DC current.

13. The device of claim 12, wherein the DC voltage and the DC current are measured at substantially a same point in a DC path.

14. The device of claim 12, wherein the DC current is measured at a first point in a DC path, the DC current having a known relation in value to a corresponding DC current measured at a second point where the DC voltage is measured.

15. The device of claim 1, wherein the detection circuit is further configured to switch the transmitter from a power-save mode to a higher power mode, in response to the receiver being in the charging region.

16. The device of claim 1, wherein the detection circuit is further configured to detect the change in impedance presented to the transmitter, in response to a valid receiver being placed in the charging region, the valid receiver comprising receiver circuitry with a rectifier and a capacitor in connected states, the capacitor configured to charge during initial application of the field.

17. A method for detecting placement of a wireless power receiver in a charging region of a wireless power transmitter, comprising:

transmitting power via a wireless field applied to the charging region to a receive coil of the receiver via a transmit coil of a transmit circuit; and

detecting a characteristic waveform resulting from the field that is applied to the charging region or changed between the transmit and receive coils, in response to the receiver being placed in the charging region.

18. The method of claim 17, wherein detecting the characteristic waveform comprises recognizing an impedance change pattern associated with a charging of a capacitor of the receiver during initial application of the field.

19. The method of claim 17, wherein:

the characteristic waveform comprises a transient spike in resistance as calculated based on a transmitter voltage and a transmitter current.

20. The method of claim 19, wherein the transmitter voltage comprises an AC voltage and the transmitter current comprises an AC current, and detecting the characteristic waveform comprises measuring the AC voltage and the AC current at substantially a same point in an AC path.

21. The method of claim 19, wherein detecting the characteristic waveform comprises measuring the AC current at a first point in an AC path, the AC current having a known relation to, in at least one of amplitude or phase, a corresponding AC current measured at a second point in the AC path where the AC voltage is measured.

22. The method of claim 17, wherein:

the characteristic waveform comprises a transient spike in resistance as calculated based on a transmitter voltage and a transmitter current.

23. The method of claim 22, wherein the transmitter voltage comprises a DC voltage and the transmitter current comprises a DC current, and detecting the characteristic waveform comprises measuring the DC current at a first point in a DC path, the DC current having a known relation in value to a corresponding DC current measured at a second point where the DC voltage is measured.

24. The method of claim 17, further comprising switching the transmitter from a power-save mode to a higher power mode, in response to the receiver being in the charging region.

25. An apparatus for detecting placement of a wireless power receiver in a charging region, comprising:

means for transmitting power via a wireless field applied to the charging region to a receive coil of the receiver; and

means for detecting a characteristic waveform resulting from the field that is applied to the charging region or changed between the means for transmitting and the receive coil, in response to the receiver being placed in the charging region.

26. The apparatus of claim 25, wherein the means for detecting the characteristic waveform comprises means for recognizing an impedance change pattern associated with a charging of a capacitor of the receiver during initial application of the field.

27. The apparatus of claim 25, wherein:

the characteristic waveform comprises a transient spike in resistance as calculated based on a transmitter voltage and a transmitter current; and

the transmitter voltage comprises an AC voltage and the transmitter current comprises an AC current.

28. The apparatus of claim 27, wherein the means for detecting the characteristic waveform comprises means for measuring the AC voltage and the AC current at substantially a same point in an AC path.

29. The apparatus of claim 27, wherein the means for detecting the characteristic waveform comprises means for measuring the AC current at a first point in an AC path, the AC current having a known relation to, in at least one of amplitude or phase, a corresponding AC current measured at a second point in the AC path where the AC voltage is measured.

30. A non-transitory computer readable medium comprising code that, when executed, causes an apparatus to:

transmit power via a wireless field applied to a charging region to a receive coil of a receiver via a transmit coil of a transmit circuit; and

detecting a characteristic waveform resulting from the field that is applied to the charging region or changed between the transmit and receive coils, in response to the receiver being placed in the charging region.