PROTECTION DEVICE AND METHOD FOR POWER TRANSMITTER

• US 20140071571A1
• Filed: 03/15/2013
• Published: 03/13/2014
• Est. Priority Date: 09/07/2012
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Tseng, Ryan, Kasturi, Sreenivas, Radovic, Milorad, Von Novak, William H. III, Kallal, Edward Kenneth III
• Granted Patent: US 9,391,442 B2
• Time in Patent Office: Days
• US Class Current: 361/91.1
• CPC Class Codes: H02H 3/20 responsive to excess voltage
• 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 50/80 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: H04B 1/0466 Fault detection or indication H04B1/0483 takes precedence
• CPC Class Codes: H04B 17/103 Reflected power, e.g. return loss
• CPC Class Codes: H04B 5/266 One coil at each side, e.g. with primary and secondary coils
• CPC Class Codes: H04B 5/79 for data transfer in combination with power transfer

Abstract

Aspects of a protection circuit and method are disclosed. A transmit circuit generates a power transmit signal for powering the transmit antenna to generate a wireless field sufficient for wirelessly charging a device. A detection circuit senses a strength of an electromagnetic field received by the transmit antenna and further configured to generate an sense signal indicating the strength of the electromagnetic field received by the transmit antenna. A power control circuit controls a switch based at least partly on the sense signal. The power control circuit can attenuate an electrical coupling between the transmit antenna and the transmit circuit such that the received electromagnetic field is inhibited from damaging the transmit antenna or the transmit circuit.

Claims

1. A wireless power transmission device, the device comprising:

a transmit antenna;

a transmit circuit configured to generate a power transmit signal for powering the transmit antenna to generate a wireless field sufficient for wirelessly charging a device;

a detection circuit configured to sense a strength of an electromagnetic field received by the transmit antenna and further configured to generate an sense signal indicating the strength of the electromagnetic field received by the transmit antenna; and

a power control circuit configured to control a switch, based at least partly on the sense signal, to attenuate an electrical coupling between the transmit antenna and the transmit circuit such that the received electromagnetic field is inhibited from damaging at least one of the transmit antenna or the transmit circuit through the electrical coupling.

2. The device of claim 1, wherein the detection circuit is configured to sense the strength of the electromagnetic field received by the transmit antenna by measuring an electrical characteristic generated by the transmit antenna.

3. The device of claim 1, wherein a power control circuit is configured to attenuate the electrical coupling by at least one of opening or closing the switch to electrically isolate the transmit antenna and the transmit circuit based at least partly on the sense signal.

4. The device of claim 1, wherein the power control circuit is configured to selectively control the switch to activate a connection between the transmit antenna and the transmit circuit, wherein the connection is configured to shunt current away from the transmit circuit when activated.

5. The device of claim 1, wherein the power control circuit is configured to control the switch to decouple a connection between the transmit antenna and the transmit circuit.

6. The device of claim 1, wherein the power control circuit is configured to prevent power transfer between the antenna and the transmit circuit based on the protection circuit being in an off-state.

7. The device of claim 1, wherein the power control circuit is configured to allow power transfer between the antenna and the circuit based on the antenna receiving power less than the threshold.

8. The device of claim 1, wherein the detection circuit is configured to cease sensing the power from the antenna based on the antenna receiving less power than the threshold.

9. The device of claim 1, wherein the power control circuit comprises a relay.

10. The device of claim 1, wherein the detection circuit comprises a sensing element, a rectifier, and a filter.

11. The device of claim 1, wherein the detection circuit is configured to provide the sense signal to a processor, wherein the power control circuit is configured to receive a control signal based on the indication signal from the processor, the power control circuit configured to control the switch based on the control signal.

12. The device of claim 1, wherein the detection circuit is configured to provide the sense signal to a processor for generating a control signal, wherein the power control circuit is configured to receive the control signal from the processor for selectively preventing or allowing the transmit circuit to transfer power to the transmit antenna.

13. A method of protecting a wireless power transmission device, the method comprising:

sensing a strength of an electromagnetic field received by a transmit antenna;

generating an indication signal indicating the strength of the electromagnetic field received by the transmit antenna; and

attenuating an electrical coupling between the transmit antenna and a transmit circuit based on the indication signal such that the received electromagnetic field is inhibited from damaging at least one of the transmit antenna or the transmit circuit through the electrical coupling.

14. The method of claim 13, wherein the sensing includes measuring an electrical characteristic generated by the transmit antenna to determine the strength of the received electromagnetic field.

15. The method of claim 13, wherein the attenuating the electrical coupling includes controlling a switch to activate an electrical pathway between the transmit antenna and the transmit circuit, wherein the electrical pathway is configured to shunt current away from the transmit circuit when activated.

16. The method of claim 13, wherein the attenuating the electrical coupling includes controlling a switch to decouple the electrical coupling between the transmit antenna and the transmit circuit.

17. A wireless power transmission apparatus, the apparatus comprising:

means for sensing a strength of an electromagnetic field received by a transmit antenna and for generating an indication signal indicating the strength of the electromagnetic field received by the transmit antenna; and

means for attenuating an electrical coupling between the transmit antenna and a transmit circuit based on the indication signal such that the received electromagnetic field is inhibited from damaging at least one of the transmit antenna or the transmit circuit through the electrical coupling.

18. The method of claim 17, wherein the means sensing is configured to sense an electrical characteristic generated by the transmit antenna to determine the strength of the received electromagnetic field.

19. The method of claim 17, wherein the means for attenuating is configured to control a switch to activate an electrical pathway between the transmit antenna and the transmit circuit, wherein the electrical pathway is configured to shunt current away from the transmit circuit when activated.

20. The method of claim 17, wherein the means attenuating is configured to control a switch to decouple the electrical coupling between the transmit antenna and the transmit circuit.