Wireless energy transfer using coupled antennas

Patent metadata

Field	Value
Publication number	US-9634730-B2
Application number	US-77516807-A
Country	US
Kind code	B2
Filing date	Jul 9, 2007
Priority date	Jul 9, 2007
Publication date	Apr 25, 2017
Grant date	Apr 25, 2017

Abstract

A power transmission system produces a magnetic field at a source that is wirelessly coupled to a receiver. Both the source and receiver are capacitively coupled LC circuits, driven at or near resonance.

First claim

What is claimed is:

1. A method of transmitting power via a wireless field, comprising:
driving a multidirectional antenna of a transmitter with a driving signal at a frequency within a range of a resonant frequency of the antenna to produce a magnetic field in more than one direction, the magnetic field configured to wirelessly transfer power to a receiver for charging a load coupled to the receiver, the receiver having a receive loop, the antenna located at a minimum distance from the receive loop of the receiver and having a higher Q factor than the receiver, the minimum distance defining a distance at or above which detuning of the antenna by the receiver is reduced, the antenna including at least a resonant component including a wire loop in series with a capacitor, and an inductive component including an inductive loop; and
preventing the antenna from being located at less than the minimum distance from the receiver.

2. A method as in claim 1 , further comprising receiving power via the magnetic field with a receiving antenna, the receiving antenna including a second resonant component, generating electrical power from the receiving antenna, and coupling the electrical power to a load.

3. A method as in claim 1 , wherein the minimum distance is between 2 and 12 inches.

4. A method as in claim 1 , further comprising setting the resonant frequency to a value of approximately 13.56 MHz.

5. A method as in claim 1 , wherein the antenna has a Q value of at least 1400.

6. A method as in claim 1 , wherein the capacitor is capable of withstanding at least 1000 V.

7. A method as in claim 1 , wherein driving the antenna comprises driving the antenna with a signal generator and adjusting a resistance of the antenna based on the impedance of the signal generator at resonance to maximize the amount of power transferred from the antenna to the receiver.

8. A method as in claim 1 , wherein the antenna has a substantially round outer form factor.

9. A method as in claim 1 , wherein the antenna has a substantially rectangular outer form factor.

10. A method as in claim 1 , wherein the inductive component is configure to receive a driving signal and is physically separated from the resonant component.

11. A method as in claim 1 , wherein the inductive component and the resonant component have different outer form factors.

12. A method as in claim 1 , wherein the inductive component and the resonant component have substantially the same outer form factors.

13. A method as in claim 1 , wherein the capacitor is a variable capacitor.

14. The method of claim 1 , wherein the antenna has a Q value of approximately 700.

15. The method of claim 1 , wherein the antenna has a Q value of approximately 450.

16. The method of claim 1 , wherein the antenna has a Q value of approximately 100.

17. The method of claim 1 , wherein the antenna is located at a maximum distance from the receiver, wherein at a second distance greater than the maximum distance a power received by the receiver falls below a usable range.

18. A method of transferring power via a wireless field, comprising:
generating a magnetic field in more than one direction using a resonant transmitter having a multidirectional antenna;
receiving power via the magnetic field with a resonant receiver, the resonant receiver located at a minimum distance from the resonant transmitter and having a lower Q factor than the resonant transmitter, the minimum distance defining a distance at or above which detuning of the resonant transmitter and resonant receiver are reduced, each of the resonant transmitter and the resonant receiver having a resonant component including a wire loop in series with a capacitor, and an inductive component including an inductive loop;
converting power received by the resonant receiver to electrical power for charging a load coupled to the receiver; and
preventing at least one of the resonant transmitter or the resonant receiver from being located at less than the minimum distance from the other of the resonant transmitter and resonant receiver.

19. An apparatus for transmitting power via a wireless field comprising:
a multidirectional antenna having a usable range at a resonant frequency; and
a power source coupled to the antenna, the power source configured to drive the antenna using a driving signal at a frequency within a range of the resonant frequency to generate a magnetic field in more than one direction, the magnetic field configured to wirelessly transfer power to a receiver for charging a load coupled to the receiver, the receiver having a receive loop, the antenna including at least a resonant component including a wire loop in series with a capacitor, and an inductive component including an inductive loop, the antenna positioned at or further than a minimum distance from the receive loop of the receiver and having a higher Q factor than the receiver, the minimum distance equal to a distance at or above which detuning of the antenna by the receiver is reduced.

20. An apparatus as in claim 19 , wherein the receiver includes a rectifier configured to output electrical power to the load coupled to the receiver.

21. An apparatus as in claim 19 , wherein the minimum distance is between 2 and 12 inches.

22. An apparatus as in claim 19 , wherein the resonant frequency is set to a value of approximately 13.56 MHz.

23. An apparatus as in claim 19 , wherein the antenna has a Q value of at least 1400.

24. An apparatus as in claim 19 , wherein the capacitor is capable of withstanding at least 1000 V.

25. An apparatus as in claim 19 , wherein the power source includes a signal generator configured to generate the driving signal, the signal generator having an impedance based on a resistance of the antenna at resonance to maximize the amount of power transferred from the antenna to the receiver.

26. An apparatus as in claim 19 , wherein the antenna has a substantially round outer form factor.

27. An apparatus as in claim 19 , wherein the antenna has a substantially rectangular outer form factor.

28. An apparatus as in claim 19 , wherein the inductive component is connected to the power source and is configured to receive the driving signal, and wherein the resonant component is physically separated from the inductive component.

29. An apparatus as in claim 19 , wherein the inductive component and the resonant component have different outer form factors.

30. An apparatus as in claim 19 , wherein the inductive component and the resonant component have substantially the same outer form factors.

31. A system as in claim 19 , wherein the capacitor is a variable capacitor.

32. The apparatus of claim 19 , wherein the antenna has a Q value of approximately 700.

33. The apparatus of claim 19 , wherein the antenna has a Q value of approximately 450.

34. The apparatus of claim 19 , wherein the antenna has a Q value of approximately 100.

35. The apparatus of claim 19 , wherein the antenna is prevented from being located at greater than a maximum distance from the receiver, wherein at a second distance greater than the maximum distance a power received by the receiver falls below the usable range.

36. A system of transferring energy wirelessly, comprising:
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Assignees

• Cook Nigel P
• Meier Paul
• Sieber Lukas
• Secall Marc
• Widmer Hanspeter
• Qualcomm Inc

Inventors

• Cook Nigel P
• Meier Paul
• Sieber Lukas
• Secall Marc
• Widmer Hanspeter

Classifications

• H02J50/05

  using capacitive coupling · CPC title

• H02J50/12 Primary

  of the resonant type · CPC title

• H02J5/005

  Electricity · mapped topic

• H04B5/0081

  Electricity · mapped topic

• H04B5/0037 Primary

  Electricity · mapped topic