SYSTEMS AND METHODS OF WIRELESS POWER TRANSFER WITH INTERFERENCE DETECTION

• US 20120077537A1
• Filed: 02/22/2011
• Published: 03/29/2012
• Est. Priority Date: 09/23/2010
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Muratov, Vladimir Alexander, Oettinger, Eric Gregory
• Granted Patent: US 9,294,153 B2
• Time in Patent Office: Days
• US Class Current: 455/522
• 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 50/70 involving the reduction of electric, magnetic or electromagnetic leakage fields
• CPC Class Codes: H04B 5/24 Inductive coupling
• CPC Class Codes: H04B 5/266 One coil at each side, e.g. with primary and secondary coils
• CPC Class Codes: H04B 5/73 for taking measurements, e.g. using sensing coils
• CPC Class Codes: H04B 5/79 for data transfer in combination with power transfer

Abstract

Performance of wireless charging systems may be significantly degraded when parasitic metal objects come in close proximity to the transmitting coil. Some of the transmitted energy may be coupled by these metal objects and wasted as heat. This may create a danger as the metal objects may get hot enough to create a fire hazard, to cause plastic parts deformation, or operator skin burns when touched.

Systems and methods of wireless power transfer system with interference detection disclosed herein detects possible excessive energy transfer associated with parasitic metal objects placed in close proximity with system coils by comparing power received on the receiving side of the system with the power consumed on the primary side considering known losses in the system. If the result of such comparison shows that power consumed on the primary side substantially exceeds power received on the secondary side, the system may terminate operation.

Claims

1. A system comprising:

a secondary side controller configured to monitor a sensed power and to produce a feedback signal comprising parameters relative to the sensed power; and

a modulation module configured to modulate a representation of the feedback signal, the modulation transmitted to a primary side controller, the primary side controller configured to inhibit charging based on the parameters as applied to a power loss equation.

2. The system of claim 1, wherein the parameters comprise at least one of a constant relative to the sensed secondary power and quiescent dissipation on the secondary side.

3. The system of claim 1, further comprising a sense resistor and an amplifier for sensing a secondary side current to be monitored by the secondary side controller.

4. The system of claim 1, wherein the modulation module transmits at least one of an amplitude modulated, pulse width modulated, frequency modulated, phase shift keyed, infrared, and radio frequency signal.

5. The system of claim 1, further comprising the primary side controller, configured to

demodulate the modulation from the modulation module;

compare the demodulated representation of the feedback signal with a primary power, and prohibit charging if efficiency of secondary power versus primary power is less than a predetermined level.

6. The system of claim 5, wherein the predetermined level is user configurable.

7. The system of claim 5, wherein the primary controller controls a resonant converter.

8. The system of claim 5, wherein the predetermined level comprises a level under which indicates presence of a parasitic metal element.

9. A method, comprising:

sensing a power on a secondary side of an inductive coupling;

generating a representation comprising parameters relative to the sensed power;

modulating the representation of the sensed power; and

transmitting the modulated representation of the sensed power to a primary side of the inductive coupling, the primary side configured to inhibit power transfer based on the parameters as applied to a power loss equation.

10. The method of claim 9, wherein the parameters comprise at least one of a constant relative to the sensed secondary power and quiescent dissipation on the secondary side.

11. The method of claim 9, wherein the modulating comprises at least one of amplitude modulating, frequency modulating, phase shift keying, pulse width modulating, infrared signaling, and radio frequency signaling.

12. The method of claim 9, wherein the modulated representation is used by the primary side to determine the presence of a parasitic metallic element.

13. The method of claim 9, further comprising:

receiving the modulated representation on the primary side; and

demodulating the modulated representation of the sensed power.

14. The method of claim 13, further comprising:

comparing the demodulated representation of the sensed power to a primary side power to determine a transmission efficiency; and

determining the presence of a parasitic metallic element based on the transmission efficiency.

15. The method of claim 14, further comprising inhibiting primary power transmission if the determining of the presence of the parasitic metallic element is positive.

16. A method, comprising:

receiving a representation comprising parameters relative to sensed power from a secondary side of an inductive coupling;

applying the parameters to a power loss equation to determine efficiency of power transfer from primary to secondary; and

determining the presence of a parasitic metallic element based on the efficiency.

17. The method of claim 16, wherein the parameters comprise at least one of a constant relative to the sensed secondary power and quiescent dissipation on the secondary side.

18. The method of claim 16, further comprising inhibiting primary power transmission if the determining of the presence of the parasitic metallic element is positive.

19. The method of claim 16, further comprising:

sensing power on the secondary side;

generating a representation of the sensed power;

modulating the representation; and

transmitting the modulated representation to the primary side.

20. The method of claim 19, wherein the modulating comprises at least one of amplitude modulating, frequency modulating, phase shift keying, pulse width modulating, infrared signaling and radio frequency signaling.

21. A system comprising:

a primary side controller configured to;

control power transmitted across an inductive coupling;

receive a representation comprising parameters relative to secondary sensed power; and

determine if a parasitic metallic element is present by applying the parameters to a power loss equation to determine an efficiency of secondary sensed power versus primary power.

22. The system of claim 21, wherein the parameters comprise at least one of a constant relative to the sensed secondary power and quiescent dissipation on the secondary side.

23. The system of claim 21, wherein the primary side controller is further configured to inhibit the transmission of power across the inductive coupling if the parasitic metallic element is present.

24. The system of claim 21, wherein the representation of the secondary sensed power is modulated on the secondary side.

25. The system of claim 24, wherein the representation of the secondary sensed current is modulated by at least one of amplitude modulation, pulse width modulation, frequency modulation, phase shift keying, infrared signaling, and radio frequency signaling.

26. The system of claim 24, wherein the primary side controller is further configured to demodulate the modulated representation of the secondary sensed power.