METHOD AND APPARATUS FOR ADAPTIVE TUNING OF WIRELESS POWER TRANSFER

• US 20090284220A1
• Filed: 11/06/2008
• Published: 11/19/2009
• Est. Priority Date: 05/13/2008
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Mohammadian, Alireza H., Ozaki, Ernest T., Toncich, Stanley S.
• Granted Patent: US 9,236,771 B2
• Time in Patent Office: Days
• US Class Current: 320/108
• CPC Class Codes: G06K 19/0701 at least one of the integrated circuit chips comprising an arrangement for power management
• CPC Class Codes: G06K 19/0715 the arrangement including means to regulate power transfer to the integrated circuit
• CPC Class Codes: G06K 19/0723 the record carrier comprising an arrangement for non-contact communication, e.g. wireless communication circuits on transponder cards, non-contact smart cards or RFIDs
• CPC Class Codes: G06K 7/0008 General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer
• CPC Class Codes: G06K 7/10178 including auxiliary means for focusing, repeating or boosting the electromagnetic interrogation field comparable booster antennas integrated on the record carrier itself G06K19/07794
• CPC Class Codes: H01F 38/14 Inductive couplings for wireless supply or distribution of electric power using inductive coupling H02J50/10
• CPC Class Codes: H01Q 1/2225 used in active tags, i.e. provided with its own power source or in passive tags, i.e. deriving power from RF signal
• CPC Class Codes: H01Q 1/38 formed by a conductive layer on an insulating support patch antennas H01Q9/0407; microstrip dipole antennas H01Q9/065; microstrip slot antennas H01Q13/106; transmission line microstrip antennas H01Q13/206; manufacturing reflecting surfaces using insulating material for supporting the reflecting surface H01Q15/142
• CPC Class Codes: H01Q 7/00 Loop antennas with a substantially uniform current distribution around the loop and having a directional radiation pattern in a plane perpendicular to the plane of the loop
• CPC Class Codes: H02J 50/005 Mechanical details of housing or structure aiming to accommodate the power transfer means, e.g. mechanical integration of coils, antennas or transducers into emitting or receiving devices
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 50/20 using microwaves or radio frequency waves
• CPC Class Codes: H02J 50/40 using two or more transmitting or receiving devices H02J50/50 takes precedence
• CPC Class Codes: H02J 50/50 using additional energy repeaters between transmitting devices and receiving devices
• CPC Class Codes: H02J 50/502 the energy repeater being integrated together with the emitter or the receiver
• 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 7/00034 Charger exchanging data with an electronic device, i.e. telephone, whose internal battery is under charge
• CPC Class Codes: H04B 5/48 Transceivers
• CPC Class Codes: H04B 5/72 : for local intradevice communication
• CPC Class Codes: H04B 5/79 : for data transfer in combination with power transfer

Abstract

Exemplary embodiments are directed to wireless power transfer. A transmit antenna generates an electromagnetic field at a resonant frequency of to create a coupling-mode region within a near field of the transmit antenna. A receive antenna receives the resonant frequency when it is within the coupling-mode region and resonates substantially near the resonant frequency. One, or both, of the transmit and receive antennas are tunable antennas that can be adaptively tuned. The adaptive tuning is accomplished by detecting a mismatch at the tunable antenna and generating a mismatch signal responsive to a voltage standing wave ratio at the tunable antenna. A resonance characteristic of the tunable antenna can be modified by adjusting a capacitance of a variable capacitor network connected to the tunable antenna.

Claims

1. A wireless power receiver, comprising:

a receive antenna for coupling with a transmit antenna through a near field radiation generated by the transmit antenna to generate an RF signal;

a voltage standing wave ratio detector operably coupled to the receive antenna to generate a mismatch signal indicating a degree of mismatch at the receive antenna;

a controller operably coupled to the mismatch signal to analyze the mismatch signal and generate control signals responsive thereto; and

a variable capacitor network operably coupled to the control signals and between the receive antenna and the RF signal, the variable capacitor network to modify a resonance characteristic of the receive antenna and the variable capacitor network by modifying a capacitance of the variable capacitor network responsive to the control signals.

2. The wireless power receiver of claim 1, wherein the variable capacitor network comprises a network selected from the group consisting of a T-network, an L-network, and a Pi-network.

3. The wireless power receiver of claim 1, wherein the variable capacitor network comprises a plurality of variable capacitors, each variable capacitor controlled by a control signal of the control signals, wherein a capacitance of each capacitor is adjusted responsive to its corresponding control signal.

4. The wireless power receiver of claim 3, wherein each variable capacitor of the plurality comprises a plurality of switched capacitors operably coupled in parallel, each switched capacitor comprising a switch and a capacitor operably coupled in series, wherein each switched capacitor is selectively included in the variable capacitor responsive to the control signal operatively coupled thereto.

5. The wireless power receiver of claim 3, wherein each variable capacitor of the plurality comprises at least one varactor operatively coupled to a corresponding control signal acting as a bias control for the at least one varactor, the at least one varactor selected from the group consisting of a reverse bias varactor diode and a MEMS variable capacitor.

6. A wireless power transmitter, comprising:

a transmit antenna for generating a near field radiation for coupling to a receive antenna;

a voltage standing wave ratio detector operably coupled to the transmit antenna to generate a mismatch signal indicating a degree of mismatch at the transmit antenna;

a controller operably coupled to the mismatch signal to analyze the mismatch signal and generate control signals responsive thereto; and

a variable capacitor network operably coupled to the control signals and between the transmit antenna and an RF signal, the variable capacitor network to modify a resonance characteristic of the transmit antenna and the variable capacitor network by modifying a capacitance of the variable capacitor network responsive to the control signals.

7. The wireless power transmitter of claim 6, wherein the variable capacitor network comprises a network selected from the group consisting of a T-network, an L-network, and a Pi-network.

8. The wireless power transmitter of claim 6, wherein the variable capacitor network comprises a plurality of variable capacitors, each variable capacitor controlled by a control signal of the control signals, wherein a capacitance of each capacitor is adjusted responsive to its corresponding control signal.

9. The wireless power transmitter of claim 8, wherein each variable capacitor of the plurality comprises a plurality of switched capacitors operably coupled in parallel, each switched capacitor comprising a switch and a capacitor operably coupled in series, wherein each switched capacitor is selectively included in the variable capacitor responsive to the control signal operatively coupled thereto.

10. The wireless power transmitter of claim 8, wherein each variable capacitor of the plurality comprises at least one varactor comprising a reverse bias diode operatively coupled to a corresponding control signal acting as a bias control for the at least one varactor.

11. A wireless power transmitter, comprising:

a transmit antenna for generating a near field radiation for coupling to a receive antenna;

an amplifier with a power signal for supplying power to the amplifier, the amplifier for applying an RF signal to the transmit antenna;

a load sensing circuit operably coupled to the amplifier and for detecting a change in current through the power signal, wherein the load sensing circuit generates a load indication signal responsive to the change in current;

a controller operably coupled to the load indication signal and to generate control signals responsive to the load indication signal; and

a variable capacitor network operably coupled to the control signals and between the transmit antenna and the RF signal, the variable capacitor network to modify a resonance characteristic of the transmit antenna and the variable capacitor network by modifying a capacitance of the variable capacitor network responsive to the load indication signal.

12. The wireless power transmitter of claim 11, wherein the variable capacitor network comprises a network selected from the group consisting of a T-network, an L-network, and a Pi-network.

13. The wireless power transmitter of claim 11, wherein the variable capacitor network comprises a plurality of variable capacitors, each variable capacitor controlled by a control signal of the control signals, wherein a capacitance of each capacitor is adjusted responsive to its corresponding control signal.

14. The wireless power transmitter of claim 13, wherein each variable capacitor of the plurality comprises a plurality of switched capacitors operably coupled in parallel, each switched capacitor comprising a switch and a capacitor operably coupled in series, wherein each switched capacitor is selectively included in the variable capacitor responsive to the control signal operatively coupled thereto.

15. The wireless power transmitter of claim 13, wherein each variable capacitor of the plurality comprises at least one varactor comprising a reverse bias diode operatively coupled to a corresponding control signal acting as a bias control for the at least one varactor.

16. A method, comprising:

generating an electromagnetic field at a resonant frequency of a transmit antenna to create a coupling-mode region within a near field of the transmit antenna;

disposing a receive antenna within the coupling-mode region, wherein the receive antenna resonates substantially near the resonant frequency; and

adaptively tuning a tunable antenna selected from the group consisting of the transmit antenna and the receive antenna by;

detecting a mismatch at the tunable antenna by generating a mismatch signal responsive to a voltage standing wave ratio at the tunable antenna; and

modifying a resonance characteristic of the tunable antenna by adjusting a capacitance of a variable capacitor network operably coupled to the tunable antenna.

17. The method of claim 16, wherein the transmit antenna comprises a first tunable antenna and the receive antenna comprises a second tunable antenna and the acts of detecting the mismatch and modifying the resonance characteristic are applied to the transmit antenna and the receive antenna.

18. The method of claim 16, wherein adjusting the capacitance of the variable capacitor network comprises selectively enabling a plurality of switched capacitors responsive to the mismatch signal, wherein the plurality of switched capacitors are operably coupled to form the variable capacitor network.

19. The method of claim 16, wherein adjusting the capacitance of the variable capacitor network comprises biasing a plurality of varactors responsive to the mismatch signal, wherein the plurality of varactors are operably coupled to form the variable capacitor network.

20. A wireless power transfer system, comprising:

means for generating an electromagnetic field at a resonant frequency of a transmit antenna to create a coupling-mode region within a near field of the transmit antenna;

means for receiving the resonant frequency within the coupling-mode region with a receive antenna, wherein the receive antenna resonates substantially near the resonant frequency; and

means for adaptively tuning a tunable antenna selected from the group consisting of the transmit antenna and the receive antenna using;

means for detecting a mismatch at the tunable antenna by generating a mismatch signal responsive to a voltage standing wave ratio at the tunable antenna; and

means for modifying a resonance characteristic of the tunable antenna by adjusting the capacitance of a variable capacitor network operably coupled to the tunable antenna.

21. The system of claim 20, wherein:

the transmit antenna comprises a first tunable antenna with the means for detecting the mismatch and the means for modifying the resonance characteristic; and

the receive antenna comprises a second tunable antenna with the means for detecting the mismatch and the means for modifying the resonance characteristic.

22. The system of claim 20, wherein the adjusting the capacitance of the variable capacitor network comprises selectively enabling a plurality of switched capacitors responsive to the mismatch signal, wherein the plurality of switched capacitors are operably coupled to form the variable capacitor network.

23. The system of claim 20, wherein adjusting the capacitance of the variable capacitor network comprises biasing a plurality of varactors responsive to the mismatch signal, wherein the plurality of varactors are operably coupled to form the variable capacitor network.