System and method for contact free transfer of power

• US 20070145830A1
• Filed: 12/27/2005
• Published: 06/28/2007
• Est. Priority Date: 12/27/2005
• Status: Active Grant

• Current Assignee: Power Science Inc.
• Original Assignee: Mobilewise
• Inventors: Lee, Yeechun, Su, Victor
• Granted Patent: US 7,521,890 B2
• Time in Patent Office: Days
• US Class Current: 307/135
• CPC Class Codes: G01V 3/104 using several coupled or uncoupled coils G01V3/101 takes precedence
• 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 50/402 the two or more transmitting or the two or more receiving devices being integrated in the same unit, e.g. power mats with several coils or antennas with several sub-antennas
• CPC Class Codes: H02J 50/70 involving the reduction of electric, magnetic or electromagnetic leakage fields
• CPC Class Codes: H02J 7/00308 Overvoltage protection

Abstract

A system and method is provided for the inductive transfer of electric power between a substantially flat primary surface and a multitude of secondary devices in such a way that the power transfer is localized to the vicinities of individual device coils. The contact free power transfer does not require precise physical alignment between the primary surface and the secondary device and can allow the secondary device or devices to be placed anywhere and in arbitrary orientation with respect to the primary surface. Such power transfer is realized without the need of complex high frequency power switching network to turn the individual primary coils on or off and is completely scalable to almost arbitrary size. The local anti-resonance architecture of the primary device will block primary current from flowing when no secondary device or devices are in proximity to the local RF power network. The presence of a tuned secondary device detunes the local anti-resonance on the primary surface; thereby enable the RF power to be transferred from the local primary coils to the secondary device. The uniformity of the inductive coupling between the active primary surface and the secondary devices is improved with a novel multi-pole driving technique which produces an apparent traveling wave pattern across the primary surface.

Claims

1. A system comprising:

i) a first unit with a substantially flat top surface, having an array of substantially identical local conducting substructures containing at least one conducting wire to generate an inductive magnetic field and attendant electric field when radio frequency currents of a fixed frequency flow therein, said local conducting substructures to share a plurality of common conductors which deliver the radio frequency power to the individual local substructure, wherein, placement of a secondary unit within proximity to the primary unit causes radio frequency power to flow from the first device to the secondary unit, the

2. The system of claim 1, wherein the secondary unit comprises a conducting structure to generate a radio frequency when placed in proximity to a conducting local substructure of said primary unit via a closed circuit formed.

3. The system of claim 2 wherein;

said local conducting substructure of the first unit includes at least a capacitor in parallel connection with the conducting wire.

4. The system of claim 3 wherein;

said local conducting substructure of the first unit is a parallel LC resonance substructure with a resonance frequency that is substantially the same as said fixed radio frequency of the first unit, such that when no secondary unit is placed in its proximity, an impedance across the parallel LC connection of the local conducting substructure is to reduce the radio frequency current.

5. The system of claim 4 wherein;

said secondary unit includes at least one capacitor in connection with said conducting structure.

6. The system of claim 5 wherein;

said capacitor is to be in LC resonance with said conducting structure of the secondary unit at the fixed radio frequency of the first unit.

7. The system of claim 6 wherein;

, an inductive coupling between the secondary unit and a local conducting substructure of the first unit is to causes the local conducting substructure to detune, to cause an impedance across a parallel LC connection of local conducting substructure to drop, to allow the radio frequency current to flow through said local conducting substructure.

8. The system of claim 1 wherein;

said array of local conducting substructures are arranged in a substantially periodic manner.

9. The system of claim 8 wherein;

said substantially periodic array of local conducting substructures are to be driven by a plurality of radio frequency (RF) drivers such that each RF driver has a fixed phase relationship with respect to a separate RF driver.

10. The system of claim 9 wherein;

said phase relationships are integer multiples of a fixed phase to form a circular array of equally spaced phases that cover 3600.

11. The system of claim 10 wherein;

when said substantially periodic array of local conducting substructures is to be driven by said plurality of phased drivers to create a traveling wave pattern across the top surface of the first unit.

12. The system of claim 10 wherein;

said plurality of phases includes four phases that are 00, 900, 1800, and 2700.

13. The system of claim 10 wherein;

Said plurality of phases includes six phases that are 00, 600, 1200, 1800, 2400, and 3000.

14. The system of claim 6 wherein;

said substantially periodic array of local conducting substructures are to be driven by a plurality of radio frequency drivers such that each RF driver is to have a random phase relationship with respect to another driver.

15. The system of claim 14 wherein;

when said substantially periodic array of local conducting substructures is to be driven by said plurality of phased drivers, said array is to create a randomly traveling wave pattern across the top surface of the first unit.

16. The system of claim 7 wherein;

said secondary unit comprises at least one electronically adjustable capacitor module.

17. The system of claim 16 wherein;

said electronically adjustable capacitor module comprises a bank of parallel capacitors switched by transistors.

18. The system of claim 17 wherein;

said transistors are MOSFETs.

19. The system of claim 16 wherein;

said secondary unit includes a controller to adjust a capacitance in response to variation of magnetic coupling between said secondary unit and the first unit.

20. The system of claim 19 wherein;

said controller of the secondary unit is to monitor an output voltage of the secondary unit and adjust the capacitance to bring the output voltage to a predefined reference voltage regardless of a variation of the output current.

21. A method comprising:

with conducting rails;

supplying radio frequency voltages across conducting rails, said conducting rails interconnect an array of conducting substructures of a first unit;

to

producing a contact free transfer of radio frequency power from the first unit to a secondary unit in response to the secondary unit being within a predetermined proximity of the first unit, the secondary unit comprising a conducting structure

22. The method of claim 21 wherein the conducting structure includes a variable capacitor module in connection said conducting structure.

23. The method of claim 22 wherein the array of conducting substructures further comprise a capacitive components to create radio frequency impedance for said conducting substructures when no secondary units are in the predetermined proximity.

24. The method of claim 23 wherein supplying radio frequency voltages across said conducting rails further comprises supplying radio frequency voltages having a plurality of phases generating a traveling wave radio frequency magnetic field pattern across a top surface of the first unit.

25. The method of claim 24 further comprising:

adjusting said variable capacitor module to increase a radio frequency voltage across said conducting structure of the secondary unit.

26. The method of claim 24 further comprising:

adjusting said variable capacitor module to stabilize a radio frequency voltage across said elongated conducting structure of the secondary unit relative to a predefined reference voltage.

27. The methods of claim 25, wherein adjusting said variable capacitor module further comprises monitoring the output voltage of said conducting structure.

28. The method of claim 27 wherein adjusting said variable capacitor module further comprises using a feedback control process.

29. The method of claim 28 wherein using a feedback control process further comprises providing the controller with a process that utilize a PID control process.