SELECTABLE COIL ARRAY

• US 20100259217A1
• Filed: 04/08/2010
• Published: 10/14/2010
• Est. Priority Date: 04/08/2009
• Status: Active Grant

• Current Assignee: Philips IP Ventures B.V. (Koninklijke Philips N.V.)
• Original Assignee: Access Business Group International LLC (Alticor Incorporated)
• Inventors: Moes, Benjamin C., Baarman, David W., Moore, Colin J., Stoner, William T. JR., Mollema, Scott A., Taylor, Joshua B.
• Granted Patent: US 9,231,411 B2
• Time in Patent Office: Days
• US Class Current: 320/108
• 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 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 7/0013 acting upon several batteries simultaneously or sequentially H02J7/1423 takes precedence
• CPC Class Codes: H02J 7/0036 using connection detecting circuits H02J7/0034 takes precedence
• CPC Class Codes: H02J 7/0044 specially adapted for holding portable devices containing batteries H02J7/0045 takes precedence
• CPC Class Codes: H02J 7/00714 in response to battery charging or discharging current

Abstract

An inductive wireless power system using an array of coils with the ability to dynamically select which coils are energized. The coil array can determine the position of and provide power to one or more portable electronic devices positioned on the charging surface. The coils in the array may be connected with series resonant capacitors so that regardless of the number of coils selected, the resonance point is generally maintained. The coil array can provide spatial freedom, decrease power delivered to parasitic loads, and increase power transfer efficiency to the portable electronic devices.

Claims

1. A coil array system comprising:

a driver circuit for generating an AC signal;

a plurality of overlapping coils arranged in a plurality of layers to form a selectable coil array associated with a charging surface for placing a secondary device, wherein said selectable coil array includes a plurality of switches operable to selectively electrically connect a subset of said plurality of coils to said driver circuit in order to generate a magnetic field in said subset of said plurality of coils;

a position detection circuit for obtaining position information regarding a secondary coil of said secondary device placed on said charging surface; and

a controller programmed to operate said selectable coil array as a function of said position information in order to position said magnetic field relative to said position of said secondary device on said charging surface, wherein the number of coils selectively electrically connected to said driver in said selectable coil array depends at least in part on said secondary device position information.

2. The coil array system of claim 1 wherein each of said plurality of coils is electrically connected with a series resonant capacitor, wherein said resonant point is maintained independent of the number of coils selectively electrically connected in parallel to said driver in said selectable coil array.

3. The coil array system of claim 1 wherein the position detection circuit includes at least one of said controller, a primary current detector, primary voltage detector, input current detector, input voltage detector, secondary current detector, secondary voltage detector, primary and secondary communication system, or any combination thereof.

4. The coil array system of claim 1 wherein the number of coils selectively electrically connected to the driver circuit in said coil array is a function of the power requirements of said secondary device.

5. The coil array system of claim 1 wherein said controller is programmed to obtain said position information of said secondary device by pinging a plurality of said coils, measuring a response to said ping of each of said pinged coils, and comparing said measurements to determine said position information of said secondary coil of said secondary device with respect to said position of said coils in said coil array.

6. The coil array system of claim 1 wherein said controller is programmed to obtain said position information of said secondary device by pinging a plurality of said coils, for each pinged coil receiving position information from said secondary device, and comparing said position information to determine said position of said secondary coil of said secondary device with respect to said position of said pinged coils in said array.

7. The coil array system of claim 1 wherein said controller is programmed to operate said selectable coil array as a function of said position information in order to position said peak of said magnetic field relative to said position of said secondary device on said charging surface.

8. A selectable coil array comprising:

a plurality of overlapping coils arranged in a plurality of layers to form a selectable coil array associated with a charging surface for placing a secondary device, wherein each of said plurality of coils is electrically connected in series with a resonant capacitor, wherein said selectable coil array includes a plurality of switches operable to selectively electrically connect a subset of said plurality of coils in parallel to an AC input in order to generate a magnetic field in said subset of said plurality of coils;

wherein resonance point of said plurality of coils is maintained independent of the number of coils electrically connected in parallel in said coil array.

9. The coil array of claim 8 wherein one side of said selectable coil array is shielded.

10. The coil array of claim 8 wherein said value of each of said series resonant capacitor is selected as a function of the distance between the coil and said shielding in order to maintain the same resonant point for each of said coils in said array.

11. The coil array claim 8 wherein the number of coils selectively electrically connected to the AC input in said coil array is a function of the power requirements of a secondary device to be powered or charged.

12. The coil array of claim 8 wherein each of said plurality of coils are physically similar and the center of each coil is located one radius from the center of each other coil in the array.

13. A method for wirelessly powering a secondary device on a charging surface of a selectable coil array, the method comprising:

determining whether a secondary device is present;

obtaining power requirement information about the secondary device;

obtaining coil information about the secondary coil of the secondary device;

determining the position of the secondary device on said charging surface;

determining a subset of coils to select of the selectable coil array to provide power to the secondary coil of the secondary device as a function of at least said power requirement information, said coil information, and said position of said secondary coil on said charging surface;

energizing the selected subset of coils of the selectable coil array to provide wireless power to said secondary coil of said secondary device.

14. The method of claim 13 wherein said determining the position of the secondary device includes:

pinging a plurality of coils in the selectable coil array;

obtaining position information as a function of said pinging;

analyzing the position information to determine the position of the secondary coil of the secondary device with respect to the position of the pinged coils in the array.

15. The method of claim 13 wherein said determining the position of the secondary device includes:

individually pinging a plurality of coils in the coil array;

obtaining a measurement of the power received in the secondary coil of the secondary device in response to each individual ping, wherein said measurement varies based on the distance between the pinged coil in the array and the secondary;

analyzing the measurements using triangulation to determine the position of the secondary coil of the secondary device.

16. The method of claim 13 wherein said determining the position of the secondary device includes:

simultaneously pinging a plurality of coils associated with an area of the coil array;

in response to determining that the secondary coil of the secondary device is within range of the area, dividing the plurality of coils associated with an area of the coil array into a plurality of areas each associated with one or more coils in the array;

individually pinging the coils associated with each of the plurality of areas to determine if the device is present in that area.

17. The method of claim 13 wherein the power requirement information and the coil information is included within a device classification.

18. The method of claim 13 wherein each of said plurality of coils is electrically connected with a series resonant capacitor, wherein a resonance point is maintained independent of the number of coils selectively electrically connected in parallel in said selectable coil array.

19. The method of claim 13 wherein said obtaining position information as a function of pinging includes detecting changes in reflected impedance in the coil array indicative of the amount of power received by the secondary coil or receiving position information transmitted by the secondary device.

20. The method of claim 13 wherein said determining a subset of coils to select of the selectable coil array to provide power to the secondary coil of the secondary device as a function of the position of the secondary coil of the secondary device on the charging surface includes selecting the subset of coils of the selectable coil array to generate a peak magnetic field at the location of the secondary coil of the secondary device.

21. The method of claim 13 including determining whether a parasitic load is present on the charging surface and determining the subset of coils to select of the selectable coil array to provide power to the secondary coil of the secondary device as a function of said parasitic load.