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Title:
WIRELESS POWER TRANSFER DEVICE & METHOD
Document Type and Number:
WIPO Patent Application WO/2019/195882
Kind Code:
A1
Abstract:
A wireless power transfer device (1200) includes an array of transmitters (1201) and a controller (1202). The array of transmitters (1201, Fig 2a) includes transmitters which are each adapted to transmit power to a receiver device (1207). The controller (1202) operates in a searching mode, and, a charging mode. In the searching mode, the presence of a receiver device (1207) is detected, and, one or more transmitters (1201) is determined to be the optimal transmitter(s) based on electromagnetic coupling to the receiver device (1207). Conflict transmitter(s) are also determined, such that, in the charging mode, the optimal transmitter(s) is/are selectively energized whilst the conflict transmitter(s) are prevented from being energized.

Inventors:
MCMENAMIN, Thomas James (c/- Halfords IP, Level 7 1 Market Stree, Sydney New South Wales 2000, 2000, AU)
LIU, James (c/- Halfords IP, Level 7 1 Market Stree, Sydney New South Wales 2000, 2000, AU)
UPADHYA, Avinash (c/- Halfords IP, Level 7 1 Market Stree, Sydney New South Wales 2000, 2000, AU)
Application Number:
AU2019/050313
Publication Date:
October 17, 2019
Filing Date:
April 08, 2019
Export Citation:
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Assignee:
PIXELATED INDUCTION PTY LTD (c/- Halfords IP, Level 7 1 Market Stree, Sydney New South Wales 2000, 2000, AU)
International Classes:
H02J7/02; H01F38/14; H02J50/10
Foreign References:
US9118203B22015-08-25
US8169185B22012-05-01
Attorney, Agent or Firm:
COWLE, Anthony et al. (Level 7, 1 Market StreetSydney, New South Wales 2000, 2000, AU)
Download PDF:
Claims:
CLAIMS

1. A wireless power transfer device including:

a plurality of transmitters, each adapted to transmit power to a receiver device;

a controller, adapted to,

in a searching mode:

detect the presence of a receiver device proximal to one or more of said transmitters;

determine which of said transmitters is an optimal transmitter based on measures of electromagnetic coupling to said receiver device; and,

determine which of said transmitters adjacent to said optimal transmitter is a conflict transmitter device based on proximity to said optimal transmitter device; and, in a charging mode:

selectively energise said optimal transmitter(s) whilst preventing said conflict transmitter(s) from being simultaneously energised.

2. The wireless power transfer device as claimed in claim 1 , wherein said plurality of transmitters is an array of transmitters.

3. The wireless power transfer device as claimed in claims 1 or 2, wherein each of said plurality of transmitters includes a coil, chip, PCB printed inductor and/or other transmitter.

4. The wireless power transfer device claimed in any one of claims 1 to 3, wherein each of said transmitters substantially abuts or at least partially overlaps at least one other transmitter.

5. The wireless power transfer device as claimed in any one of claims 1 to 4, wherein, in use, each of said transmitters is adapted to emanate an electromagnetic field therefrom which at least partially overlaps the electromagnetic field from at least one other transmitter.

6. The wireless power transfer device as claimed in any one of claims 1 to 5, wherein said transfer device is adapted to simultaneously power a plurality of receiver devices.

7. The wireless power transfer device as claimed in any one of claims 1 to 6, wherein the device is adapted to be connected to a power source, including an external power supply or a power supply formed integrally in said device.

8. The wireless power transfer device as claimed in any one of claims 1 to 7, wherein said controller includes a multiplexer.

9. The wireless power transfer device as claimed in any one of claims 1 to 7, wherein, in said searching mode:

each of the transmitters is energised by being connected to a power source; if a receiver of a corresponding receiver device is within charging range of the corresponding transmitter, a corresponding measure of the electromagnetic coupling between the energised transmitter and the corresponding receiver is determined; and

one or more of the energised transmitters is selected on the basis of measures of electromagnetic coupling; and,

in said charging mode,

the selected transmitter(s) is/are connected to the power source, to transmit power to the corresponding power receiving device(s);

wherein, to avoid electromagnetic interference between energised transmitter coils, each transmitter is only energised if that transmitter coil is sufficiently distant from any other energised transmitter coil.

10. The wireless power transfer device as claimed in any one of claims 1 to 9, wherein, in said searching mode, each of the transmitters is energised selectively and/or sequentially.

11. The wireless power transfer device as claimed in any one of claims 1 to 10, wherein, in said searching mode, each transmitter is only energised if that transmitter is not adjacent to any other energised transmitter.

12. The wireless power transfer device as claimed in any one of claims 1 to 11 , wherein the device is adapted to be operatively connected to one or more similar power transfer devices.

13. The wireless power transfer device as claimed in claim 12, wherein, when operatively connected to any other similar power transfer device, said controller is adapted to operate across all connected devices as if a single device.

14. A wireless power transfer apparatus, including:

a plurality of power transmitter subsystems, each power transmitter subsystem including: a plurality of transmitters for transmitting electrical power to at least one receiver of a corresponding power receiving device; and

a controller for selectively and sequentially energising each of the transmitters by connecting it to a power source; wherein each power transmitter subsystem is configured to operate in at least two modes, including:

(a) a searching mode, in which the controller:

(i) selectively and sequentially energises each of at least a subset of the

transmitters of the power transmitter subsystem by connecting the corresponding transmitters to the power source;

(ii) if a corresponding receiver of a corresponding power receiving device is within charging range of the corresponding transmitter, determines a corresponding measure of the electromagnetic coupling between the energised transmitter and the corresponding receiver; and

(iii) selects one of the energised transmitters on the basis of the determined measures of electromagnetic coupling; and,

(b) a charging mode, in which the multiplexer connects the power source to the selected transmitter to transmit power to the corresponding power receiving device;

wherein, to avoid electromagnetic interference between energised transmitters, in the searching mode the multiplexer of each power transmitter subsystem only energises a corresponding transmitter if that transmitter is sufficiently distant from any energised transmitter of others of the power transmitter subsystems.

15. The wireless power transfer apparatus of claim 14, wherein, in the searching mode the multiplexer of each power transmitter subsystem only energises a corresponding transmitter if that transmitter is not adjacent to any energised transmitter of others of the power transmitter subsystems.

16. The wireless power transfer apparatus of claim 14 or 15, wherein each of the plurality of power transmitter subsystems has the same number of transmitters, and the corresponding transmitters are in the same arrangement in each of the power transmitter subsystems, wherein in each of the power transmitter subsystems, the energising of the corresponding transmitters in the search mode is synchronised with the energising of corresponding transmitters in the search mode in the other power transmitter subsystems by having an identical energising sequence.

17. The wireless power transfer apparatus of any one of claims 14 to 16, wherein if the multiplexer determines that a corresponding transmitter is insufficiently distant from an energised transmitter of any other of the power transmitter subsystems, the multiplexer delays the energising of that corresponding transmitter.

18. The wireless power transfer apparatus of any one of claims 14 to 17, wherein the multiplexer of each power transmitter subsystem is communicatively connected to at least one multiplexer of at least one corresponding other of the power transmitter subsystems.

19. The wireless power transfer apparatus of any one of claims 14 to 18, wherein the multiplexer includes:

a switching component for connecting the power source to one of the transmitters; and

a switching controller to control the switching component.

20. The wireless power transfer apparatus of any one of claims 14 to 19, wherein the charging ranges of the transmitters of each of the power transmitter subsystem at least partially overlap with the charging ranges of the transmitters of at least one other of the power transmitter subsystems.

21. The wireless power transfer apparatus of any claims 14 to 20, wherein each of the power transmitter subsystems is arranged adjacent to at least another one other of the power transmitter subsystems in a horizontal plane.

22. The wireless power transfer apparatus of any one of claims 14 to 21 , wherein at least a subset of the power transmitter subsystems are arranged in a row.

23. The wireless power transfer apparatus of any one of the claims 14 to 22, wherein at least a subset of the power transmitter subsystems are arranged in a two dimensional array.

24. The wireless power transfer apparatus of any one of claims 14 to 23, wherein more than one of the subsystems are configured to charge the same power receiving device simultaneously.

25. The wireless power transfer apparatus of any one of claims 14 to 24, wherein different subsets of the power transmitter subsystems are compliant or at least compatible with respective different wireless charging standards.

26. The wireless power transfer apparatus as claimed in any one of claims 14 to 25, wherein said power source includes an external power supply or a power supply formed integrally in said device.

27. The wireless power transfer apparatus as claimed in any one of claims 14 to 25, wherein each of said transmitters includes a coil, chip, PCB printed inductor and/or other transmitter.

28. The wireless power transfer apparatus/device as claimed in any one of claims 1 to 27, wherein said apparatus/device is embodied in the form of a modular unit which may be operatively connected to one or more similar modular unit.

29. The wireless power transfer apparatus/device as claimed in claim 28, wherein said modular units are adapted to be magnetically connected together.

30. A method for transferring power wirelessly, including:

(i) selectively and sequentially energising each of at least a subset of a plurality of transmitter coils of a power transmitter subsystem of a wireless power transfer apparatus by connecting the corresponding transmitter coil to a corresponding power supply of the corresponding power transmitter subsystem;

(ii) to avoid electromagnetic interference between energised transmitter coils, determining whether a corresponding transmitter coil is sufficiently distant from any energised transmitter coil of any other of the power transmitter subsystems of the wireless power transfer apparatus;

(iii) if the corresponding transmitter coil is sufficiently distant from all energised transmitter coils of others of the power transmitter subsystems of the wireless power transfer apparatus, determining whether a corresponding receiver coil of a corresponding power receiving device is within charging range of the corresponding transmitter coil;

(iv) if a corresponding receiver coil of a corresponding power receiving device is within the charging range of the corresponding transmitter coil, determining a corresponding measure of the electromagnetic coupling between the energised transmitter coil and the corresponding receiver coil;

(v) selecting one of the energised transmitter coils on the basis of the determined measures of electromagnetic coupling; and

(vi) connecting the power supply to the selected transmitter coil to transmit power to the corresponding power receiving device.

Description:
WIRELESS POWER TRANSFER DEVICE & METHOD

TECHNICAL FIELD OF THE INVENTION

[0001]The present invention relates to a wireless power transfer device and method. In particular, the present invention relates to a wireless power transfer apparatus and method that is capable of charging multiple electronic devices simultaneously.

BACKGROUND OF THE INVENTION

[0002] Any reference herein to known prior art does not, unless the contrary indication appears, constitute an admission that such prior art is commonly known by those skilled in the art to which the invention relates, at the priority date of this application.

[0003] Wireless power transfer (WPT), refers to the transmission of electrical energy from a power transmitting device to a power receiving device, in the form of electromagnetic waves travelling between electromagnetically coupled inductor coils; i.e., without wires or other electrically conductive connectors between the devices. Perhaps the most common form of wireless power transfer in use today is the wireless charging of battery powered portable electronic devices, in particular smartphones, but increasingly also smart watches, wearable health monitors, and the like.

[0004] The power transmitting device uses a power supply to drive a first induction coil (referred to in the art as a "primary coil") to generate an electromagnetic field, from which a second induction coil (referred to in the art as a "secondary coil") in the power receiving device receives electrical power in the form of an alternating electric current that supplies the electrical power to the power receiving device.

[0005] In order to achieve efficient power transmission, the primary coil and the secondary coil need to be aligned and in close proximity to each other. If they are misaligned, the secondary coil may not be able to receive much of the electromagnetic energy generated by the primary coil, and consequently the efficiency of power transfer may decrease. Accordingly, wireless charging systems generally require the portable device to be charged to be placed at a specific location on a planar charging surface of these systems.

[0006] In the context of wireless charging of portable electronic devices such as mobile smartphones as the power receiving device, it is generally desirable to allow essentially arbitrary placement of the or each power receiving device on a charging surface that is considerably larger than the (or each) power receiving device, a capability referred to herein as "free positioning". [0007] Free positioning can be achieved by providing multiple primary coils below the charging surface of a wireless charging apparatus so that at least one of these primary coils will have acceptable electromagnetic coupling to the secondary coil of a power receiving device placed on the charging surface.

[0008] Additionally, due to the increasing ubiquity of portable electronic devices, it is also generally desirable to allow simultaneous charging of multiple electronic devices on the charging surface of a wireless charger.

[0009] Unfortunately for consumers and manufacturers, there are multiple different specification for wireless charging of battery-powered portable electronic devices, including the Qi standard, and the PMA (Power Matters Alliance) standard. Whilst the Qi standard appears to be dominating the market, some companies, such as Apple, use their own specification. Accordingly, when buying a wireless charger, consumers need to be careful that the wireless charger supports the correct wireless charging standard for their device. If a consumer owns multiple wirelessly chargeable devices, then it is quite possible that those devices require different wireless charging standards, and thus the consumer may need to purchase multiple different types of wireless chargers.

[0010] The Qi Wireless Power Transfer System Power Class 0 Specification ("the Qi Specification") describes various reference designs to support free positioning. In particular, section 2.3.1 Power Transmitter design B1 describes a hypothetical wireless charger architecture in which an array of partly overlapping identical primary coils (in three mutually offset layers) allows free positioning, and a "multiplexer connects and/or disconnects the appropriate primary coils".

[0011] Sub-section 2.3.1.3 of the same document describes how a wireless charger might support the simultaneous charging of multiple power receiving devices by providing multiple power supplies and using the multiplexer to connect each of these power supplies to respective different primary coils (when power receiving devices are present at those primary coils) while "[ensuring] that it does not connect multiple inverters to any individual primary coil."

[0012] However, the inventors have determined that this hypothetical wireless charger architecture would be extremely difficult and impractical to implement in practice. Not only is the description not enabling, but also there are numerous technical challenges that make the design impractical. In particular, a multiplexer with the required amount of AC power handling and flexibility as described does not exist, and is impractical to design at least for reasons of space constraints, cost, and in particular electrical leakage through the greatly increased number of off-state paths. Although the Qi Specification claims that the described architecture is scalable, that is incorrect because these constraints would increase prohibitively as the number of primary coils is scaled upwards. In particular, when the same multiplexer is used to connect multiple inverters to multiple primary coils, the number of switching circuits required will increase quadratically, according to (2 x C x N), where C represents the number of coils and N represents the number of devices that can be charged simultaneously.

[0013] The number of coils and the number of coil devices each increases as the square of each linear dimension of a wireless charger (width by depth). This indicated that the required number of switching circuits would increase as the fourth power of these spatial dimensions of the charger. This would make the charger more difficult and prohibitively expensive to manufacture as the charging surface area is increased.

SUMMARY OF THE INVENTION

[0014] The present invention seeks to provide a power transfer device/apparatus which addresses or alleviates one or more shortcomings of the prior art, or, at least to provide a useful alternative.

[0015] According to one aspect, the present invention provides a wireless power transfer device including:

a plurality of transmitters, each adapted to transmit power to a receiver device; a controller, adapted to,

in a searching mode:

detect the presence of a receiver device proximal to one or more of said transmitters;

determine which of said transmitters is an optimal transmitter based on measures of electromagnetic coupling to said receiver device; and,

determine which of said transmitters adjacent to said optimal transmitter is a conflict transmitter device based on proximity to said optimal transmitter device; and,

in a charging mode:

selectively energise said optimal transmitter(s) whilst preventing said conflict transmitter(s) from being simultaneously energized.

[0016] Preferably, said plurality of transmitters is an array of transmitters.

[0017] Also preferably, each of said plurality of transmitters includes a coil, chip, PCB printed inductor and/or other transmitter.

[0018] Preferably, each of said transmitters substantially abuts or at least partially overlaps at least one other transmitter.

[0019] Also preferably, in use, each of said transmitters is adapted to emanate an electromagnetic field therefrom which would at least partially overlaps the electromagnetic field from at least one other transmitter.

[0020] Preferably, said transfer device is adapted to simultaneously power a plurality of receiver devices.

[0021] Preferably, the device is adapted to be connected to a power source, including an external power supply or a power supply formed integrally in said device.

[0022] Preferably, said controller includes a multiplexer.

[0023] Also preferably, in said searching mode: each of the transmitters is energised by being connected to a power

source;

if a receiver of a corresponding receiver device is within charging range of the corresponding transmitter, a corresponding measure of the electromagnetic coupling between the energised transmitter and the corresponding receiver is determined; and

one or more of the energised transmitters is selected on the basis of

measures of electromagnetic coupling; and,

in said charging mode,

the selected transmitter(s) is/are connected to the power source, to transmit power to the corresponding power receiving device(s);

wherein, to avoid electromagnetic interference between energised transmitter coils, each transmitter is only energised if that transmitter coil is sufficiently distant from any other energised transmitter coil.

[0024] Preferably, in said searching mode, each of the transmitters is energized selectively and/or sequentially.

[0025] Also preferably, in said searching mode, each transmitter is only energised if that transmitter is not adjacent to any other energised transmitter.

[0026] Preferably, the device is adapted to be operatively connected to one or more similar power transfer devices.

[0027] Preferably, when operatively connected to any other similar power transfer device, said controller is adapted to operate across all connected devices as if a single device.

[0028] According to an alternative aspect, the invention provides a wireless power transfer

apparatus, including:

a plurality of power transmitter subsystems, each power transmitter subsystem including:

a plurality of transmitters for transmitting electrical power to at least one receiver of a corresponding power receiving device; and

a multiplexer for selectively and sequentially energising each of the transmitters by connecting it to the power supply;

wherein each power transmitter subsystem is configured to operate in at least two modes, including:

a) a searching mode, in which the multiplexer:

(i) selectively and sequentially energises each of at least a subset of the transmitters of the power transmitter subsystem by connecting the corresponding transmitter to the power source;

(ii) if a corresponding receiver of a corresponding power receiving device is within charging range of the corresponding transmitter, determines a corresponding measure of the electromagnetic coupling between the energised transmitter and the corresponding receiver; and

(iii) selects one of the energised transmitters on the basis of the determined measures of electromagnetic coupling; b) and a charging mode, in which the multiplexer connects the power supply to the selected transmitter to transmit power to the corresponding power receiving device;

wherein, to avoid electromagnetic interference between energised transmitters, in the searching mode the multiplexer of each power transmitter subsystem only energises a corresponding transmitter if that transmitter is sufficiently distant from any energised transmitters of others of the power transmitter subsystems.

[0029] Preferably, in the searching mode the multiplexer of each power transmitter subsystem only energises a corresponding transmitter if that transmitter is not adjacent to any energised transmitter of others of the power transmitter subsystems.

[0030] Also preferably, each of the plurality of power transmitter subsystems has the same number of transmitters, and the corresponding transmitters are in the same arrangement in each of the power transmitter subsystems, wherein in each of the power transmitter subsystems, the energising of the corresponding transmitters in the search mode is synchronised with the energising of corresponding transmitters in the search mode in the other power transmitter subsystems by having an identical energising sequence.

[0031] Preferably, if the multiplexer determines that a corresponding transmitter is insufficiently distant from an energised transmitter of any other of the power transmitter subsystems, the multiplexer delays the energising of that corresponding transmitter.

[0032] Also preferably, the multiplexer of each power transmitter subsystem is communicatively connected to at least one multiplexer of at least one corresponding other of the power transmitter subsystems.

[0033] Preferably, the multiplexer includes:

a switching component for connecting the power source to one of the transmitters; and

a switching controller to control the switching component.

[0034] Preferably, the charging ranges of the transmitters of each of the power transmitter

subsystem at least partially overlap with the charging ranges of the transmitters of at least one other of the power transmitter subsystems.

[0035] Also preferably, each of the power transmitter subsystems is arranged adjacent to at least another one other of the power transmitter subsystems in a horizontal plane.

[0036] Preferably, at least a subset of the power transmitter subsystems are arranged in a row.

[0037] Also preferably, at least a subset of the power transmitter subsystems are arranged in a two dimensional array.

[0038] Also preferably, more than one of the subsystems are configured to charge the same power receiving device simultaneously. [0039] Also preferably, different subsets of the power transmitter subsystems are compliant or at least compatible with respective different wireless charging standards.

[0040] Preferably, said power source includes an external power supply or a power supply formed integrally in said device.

[0041] Preferably, each of said transmitters includes a coil, chip, PCB printed inductor and/or other transmitter.

[0042] Also preferably, said apparatus/device is embodied in the form of a modular unit which may be operatively connected to one or more similar modular unit.

[0043] Also preferably, said modular units are adapted to be magnetically connected together.

[0044] According to another aspect, the invention provides a method for transferring power

wirelessly, including:

(i) selectively and sequentially energising each of at least a subset of a plurality of transmitter coils of a power transmitter subsystem of a wireless power transfer apparatus by connecting the corresponding transmitter coil to a corresponding power supply of the corresponding power transmitter subsystem;

(ii) to avoid electromagnetic interference between energised transmitter coils, determining whether a corresponding transmitter coil is sufficiently distant from any energised transmitter coil of any other of the power transmitter subsystems of the wireless power transfer apparatus;

(iii) if the corresponding transmitter coil is sufficiently distant from all energised transmitter coils of others of the power transmitter subsystems of the wireless power transfer apparatus, determining whether a corresponding receiver coil of a corresponding power receiving device is within charging range of the corresponding transmitter coil;

(iv) if a corresponding receiver coil of a corresponding power receiving device is within the charging range of the corresponding transmitter coil, determining a corresponding measure of the electromagnetic coupling between the energised transmitter coil and the corresponding receiver coil;

(v) selecting one of the energised transmitter coils on the basis of the determined measures of electromagnetic coupling; and

(vi) connecting the power supply to the selected transmitter coil to transmit power to the corresponding power receiving device.

BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Some embodiments of the present invention are hereinafter described, by way of example only, with reference to the accompanying drawings, in which like reference numerals are used to refer to like components, and wherein:

[0046] Figure 1 is a schematic diagram of a wireless power transfer apparatus in accordance with some embodiments of the present invention;

[0047] Figures 2A to 2D are plan, perspective, and side views, respectively, of an embodiment of a charging coil array unit of a power transmitter subsystem of the wireless power transfer apparatus;

[0048] Figure 3A and Figure 3B are plan views showing four instances of the charging coil array unit of Figures 2A to 2D side by side: (3A) in a spaced apart arrangement, and (3B) abutting one another to form a four unit charging coil array of the wireless power transfer apparatus of Figure 1 ;

[0049] Figure 4 is a plan view of a sixteen unit charging coil array of a wireless power transfer apparatus according to another embodiment;

[0050] Figure 5 is a circuit schematic diagram of an exemplary power transmitter that is compatible with the Qi standard;

[0051] Figure 6 is a flowchart of a wireless power transfer process executed by a controller of each power transmitter subsystem;

[0052] Figures 7A - 7D are examples of coil interference tables for different coil array configurations;

[0053] Figure 8 is a block diagram of a wireless power transfer apparatus in accordance with some embodiments of the present invention;

[0054] Figure 9 is a schematic diagram of a wireless power transfer apparatus in accordance with some further embodiments of the present invention;

[0055] Figure 10 is a schematic plan view illustrating four possible locations of respective chargeable devices on a charging surface of a wireless power transfer apparatus according to some embodiments;

[0056] Figures 11A to 11 C are bottom, top isometric, and plan views, respectively, of a charging coil printed circuit board (PCB) in accordance with an embodiment of a wireless power transfer apparatus; Figures 11A and 11 B showing the attached charging coils and Figure 11 C showing the conductive PCB tracks that are used to independently provide power to each charging coil.

[0057] Figure 12 shows an embodiment of a power transfer device in accordance with the present invention, showing a power receiving device being charged thereby;

[0058] Figure 13 shows a plurality of the power transfer devices of Figure 12 interconnected together;

[0059] Figure 14 shows an exploded view of the power transfer device of Figure 12;

[0060] Figure 15 shows an isolated view of the PCB of the power transfer device of Figures 12 and 13.

DETAILED DESCRIPTION OF PREFERED EMBODIMENTS

[0061] Embodiments of the present invention include a wireless power transmitting apparatus and method that provide efficient simultaneous charging of multiple power receiving devices with free positioning.

[0062] According to at least some embodiments, the provided apparatus is scalable to arbitrary practical dimensions of the charging area and of the number of devices that can be charged simultaneously. Multiple different wireless charging standards can also be supported to operate simultaneously in a single wireless charging apparatus. For example, the required number of switching circuits scales with only the number of charging coils, and scales linearly.

[0063] According to at least some embodiments, a number of subsystems in the wireless power transmitting apparatus may be used to simultaneously charge the same power receiving device, e.g., a power receiving device that has a large footprint, such as a laptop computer, or a tablet computer.

[0064] Figure 1 is a block diagram of a wireless power transfer apparatus 100 in accordance with an embodiment of the present invention. [0065] The wireless power transfer apparatus 100 (which for the sake of brevity is also referred to hereinafter as the "apparatus 100") includes four power transmitter subsystems 110, 120, 130 and 140.

[0066] Each of these power transmitter subsystems 1 10, 120, 130, 140 includes a power supply 150, a multiplexer 160, and a plurality of wireless charging coils or "transmitter" coils 170. The architecture of the wireless power transmitting apparatus 100 is scalable. Thus, although the described embodiment shown in Figure 1 includes four subsystems 110, 120, 130, 140, each of which includes an array of 24 transmitter coils 170, other embodiments can have any practical number of subsystems (to provide simultaneous wireless charging of that same number of portable electronic devices) and any practical number of transmitter coils in each subsystem (to allow correspondingly arbitrary placement of those portable electronic devices relative to a charging surface of the apparatus).

[0067] In each subsystem, the power supply 150 generates and outputs an AC power signal that is sent to only one of the transmitter coils 170 of the subsystem at any given time by the multiplexer 160.

[0068] The multiplexer 160 includes a controller 180 and a switching component 190. The controller 180 executes a wireless power transfer process 600, as shown in Figure 6, that controls the operation of the switching component 190 to send a power signal to only one selected transmitter coil 170 at a time, while avoiding energising any transmitter coil 170 that would interfere with an energised transmitter coil of any of the other subsystems, as described below.

Operating modes

[0069] In order to select and connect the transmitter coil 170 with the best electromagnetic coupling to a receiver coil of a power receiving device to be charged, each subsystem polls each of its transmitter coils 170 in turn to detect the presence of a power receiving device within charging range, and to connect the power supply 150 to the transmitter coil that has the best electromagnetic coupling to the receiver coil.

[0070] To achieve this, each subsystem operates in one of at least two operating modes or states: a searching or scanning mode, and a charging mode.

[0071] In the searching mode, the subsystem searches (or "scans") its transmitter coils to determine whether a receiving coil of a power receiving device is located within charging range of any of its transmitter coils 170. This is performed by the multiplexer 160 connecting the power supply 150 to each of its transmitter coils 170 in a sequential manner, one transmitter coil 170 at a time. For each of the transmitter coils 170 within charging range of a receiver coil, a measure of the electromagnetic coupling between the transmitter coil and the receiver coil is determined. In various embodiments, the detection of receiving coils within range is made either by the power supply 150, or by the controller 180, as described below. In any case, this detection step allows the controller to determine, for each detected receiver coil, which of the transmitter coils 170 has the best electromagnetic coupling to the receiver coil, and will thus provide the most efficient charging of the corresponding power receiving device.

[0072] When a subsystem has detected the presence of a power receiving device, and has determined which of its transmitter coils 170 has the best electromagnetic coupling with the receiver coil of the power receiving device, the subsystem stops scanning its transmitter coils 170 and enters the charging mode or state, in which the multiplexer 160 connects the output AC signal from the corresponding power supply 150 to that selected transmitter coil 170 to charge the detected power receiving device. Provided that the power receiving device remains within charging range of that transmitter coil 170, the power supply remains connected to that transmitter coil.

[0073] The searching or scanning of the array of coils and selection of the coil in the best position can be implemented using any suitable detection method, including, for example, the methods described in Section 5.1.1 and/or 10.1 of The Qi Wireless Power Transfer System Power Class 0 Specification, Parts 1 and 2: Interface Definitions (Version 1.2.2).

Avoiding interference

[0074] The embodiment of the apparatus 100 shown in Figure 1 includes four subsystems 110, 120, 130 and 140. As each subsystem can charge a single power receiving device, the whole apparatus 100 is capable of charging up to four different power receiving devices simultaneously.

[0075] The subsystems 110, 120, 130 and 140 have respective different portions of the charging surface of the apparatus 100 (those portions also referred to herein as "charging areas" or "charging regions"). Thus a power receiving device is chargeable by a power transmitter subsystem when placed within that subsystem's corresponding charging area of the charging surface.

[0076] In order to allow free positioning of the power receiving devices, the charging area of each subsystem may abut or partially overlap with the charging area of another of the subsystems. [0077] For example, in the apparatus 100 shown in Figure 1 , the charging area of the subsystem 1 10 may abut or overlap with the charging area of the subsystem 120 on its right side. Similarly, the charging area of the subsystem 120 may abut or overlap with the charging area of the subsystem 110 on its left side, and abut or overlap with the charging area of the subsystem 130 on its right side. Similar abutting or overlapping relationships may also apply to the subsystems 130 and 140.

[0078] Because the subsystems perform searching and charging in parallel with one other, the simultaneous energising of primary coils belonging to two adjacent subsystems but within coupling range of one another can cause significant electromagnetic mutual interference. This interference can cause misdetection of power receiving devices if either or both of the coils is/are being searched, or a decrease in charging efficiency if either or both of the coils is charging a power receiving device.

[0079] In order to address this potential problem, embodiments of the present invention address this problem by avoiding the simultaneous energising of such coils.

[0080] To achieve this, in each of the subsystems of the apparatus 100, the controller 180 controls the operation of the switching component 190 to ensure that the switching component 190 only connects the power supply 150 to a primary coil 170 when that connection would not interfere with the searching or charging in an adjacent subsystem, or vice versa.

[0081] In some embodiments, this is at least partly achieved by having identical layouts of primary coils in the different subsystems, and synchronising the searches so that at least a threshold spatial separation or distance is maintained between the energised primary coils in the different subsystems at any instant, and in some embodiments to maximise the separation between energised coils when simultaneously searching in adjacent subsystems.

[0082] For example, in the described embodiment, each of the subsystems includes a corresponding coil array having the same number of coils and in the same arrangement as the other subsystems. Each coil in a coil array is associated with a unique identifier, e.g., a serial number, and simultaneous searches in multiple subsystems are synchronised by simultaneously scanning coils with the same identifier in each subsystem. For example, in a first time slot, each subsystem scans its own coil No. 1 ; in a second time slot, each subsystem scans its own coil No. 2; in a third time slot, each subsystem scans its own coil No. 3, and so on. Coil No. 1 in each subsystem is located in the same position relative to the corresponding coil array, and the same applies to the other coils with the same coil number. [0083] In order to ensure that coils located at the same relative position in each coil array are scanned at the same time, the controller 180 synchronises the multiple subsystems 110, 120, 130 and 140. In some embodiments, the subsystems 110, 120, 130 and 140 are connected to a common clock signal. However, in the described embodiment, the subsystems 110, 120, 130 and 140 are interconnected and communicate with each other (as shown in Figure 1) to relay their scanning timing to each other (which effectively becomes a clock signal). This allows the synchronisation of the searches in different subsystems without requiring additional hardware resource for generating the clock signal.

[0084] This allows the apparatus 100 to avoid - with minimal computational overhead - simultaneous searching of coils in two different subsystems in such a way that at least one of them would interfere with the other.

[0085] In addition to the above, the avoidance of interference is carried out by the controlling module controlling the connection of the switching module in an adaptive manner, such that searching of a primary coil is avoided if that search would interfere with the searching or charging of a primary coil in another subsystem.

[0086] For example, the controller can determine whether the distance between a coil in one subsystem and a coil being searched or charged in another subsystem (e.g. an adjacent subsystem) is below a predetermined threshold. If so, the controller can control the switching component 190 to delay or skip the scan of that primary coil 170. Given that the spatial arrangement of the primary coils in the apparatus is fixed during manufacture (i.e. , it is known or predetermined in advance), it is most straightforward to define a lookup table that indicates the electromagnetic interference of any given primary coil with any other primary coil of the apparatus.

[0087] For example, as shown in Figure 1 , in some embodiments the controller of each subsystem is in data communication with the controller(s) 180 of its adjacent subsystem(s). Signals sent from the controller 180 of one subsystem (referred to as the "first subsystem") to the controller 180 of an adjacent subsystem (referred to as the "second subsystem") indicate which of the primary coils in the first subsystem is being energised (I.e., searched or charged) at that time. Accordingly, in the second subsystem, the searching of a primary coil that is of insufficient distance from (or would otherwise interfere with) that primary coil of the first subsystem is avoided, e.g., delayed or skipped.

[0088] This allows the apparatus 100 to avoid the energising of any coil that would interfere with the searching or charging using another primary coil of another subsystem, without compromising the overall function of the apparatus 100.

[0089] This adaptive approach is particularly useful in the circumstances where synchronisation of the searches in different subsystems is not possible, e.g., when these subsystems are compliant with different wireless charging standards or have different arrangements of coil arrays.

Improving searching efficiency

[0090] In some embodiments, the dimensions of the primary coils 170 are much smaller than the dimensions of the power receiving devices.

[0091] Consequently, when a coil at or near the edge of one subsystem is charging a power receiving device, it is unlikely that the first few closest coil(s) at or near the corresponding edge of an adjacent subsystem would provide the best electromagnetic coupling to another power receiving device, because the distance between these two coils would be much smaller than the minimum possible distance between the receiver coils of two different power receiving devices on the charging surface of the apparatus 100 at the same time.

[0092] Accordingly, in some embodiments, each subsystem can simply avoid searching the primary coils 170 immediately adjacent to an adjacent subsystem if an adjacent subsystem is already charging a power receiving device (i.e., that subsystem is already in the charging mode) using a primary coil at or near the corresponding edge of that subsystem.

[0093] For example, in some embodiments a predetermined threshold distance is used to determine whether a primary coil 170 is too close to an adjacent subsystem that is charging a power receiving device. If the controller 180 of the multiplexer determines that the distance of a primary coil from an adjacent subsystem in a charging mode is below the threshold distance, the controller 180 controls the switching component to delay or skip the scanning of that primary coil 170.

[0094] This arrangement avoids searching primary coils 170 that are unlikely to provide optimal inductive coupling, and can thereby improve the search efficiency.

Improving charging efficiency

[0095] In some embodiments, multiple subsystems can be used to charge the same power receiving device, provided that they all provide a high level of electromagnetic coupling with the receiver coil of the power receiving device. This can be particularly advantageous when the power receiving device has a large footprint and covers multiple subsystems. The coupling between the charging apparatus and a larger power receiving device is improved if the power receiving device includes multiple secondary coils that can be aligned with coils in multiple subsystems. An improved charging speed can be achieved because multiple subsystems are simultaneously transmitting power to the same power receiving device.

[0096] The exemplary structure and operation of each component of the apparatus 100 will now be described in further detail.

The coil arrays

[0097] In the embodiment shown in Figure 1 , each subsystem includes a coil array formed by 24 charging coils 170.

[0098] Figures 2A - Fig. 2D illustrate the coil array of each subsystem. The coil array 200 includes 24 circular coils arranged in three layers, with eight coils in each of the layers. The 24 circular coils are formed in substantially same shape and size, each coil being partly overlapping with other coils and in a hexagonal close packed (hep) arrangement, as shown in plan view in Figure 2A.

[0099] An insufficient density of coils, or coils of too large a size, can cause dead spots across the charging surface of the apparatus, where power receiving devices will not be detected or will not charge.

[00100] The dimensions and other relevant parameters of the coils in the described embodiment are given in Table 1 below, however, different values may be used in other embodiments.

Table 1 : Examples of coil parameters

[00101] As the apparatus 100 includes four subsystems 110, 120, 130 and 140, four instances of the array shown in Figure 2A - 2D are used.

[00102] Figure 3A shows the four coil arrays of the four subsystems as they are arranged in the apparatus 100, each coil array having the same structure as the one shown in Figure 2A - Figure 2D. [00103] As shown in Figure 3B, in the apparatus 100, these four coil arrays are arranged in a one dimensional horizontal row, each coil array partially overlapping with the adjacent coil array(s) in the horizontal direction. As a result, the charging area of the apparatus 100 is approximately four times larger than the charging area of each single subsystem 110, 120, 130, 140.

[00104] Although in the above example, the apparatus 100 includes four subsystems 110, 120, 130, 140 and thus four coil arrays, it would be understood by a person skilled in the art that in other embodiments a wireless charging apparatus can include any practical number of coil arrays, and the coil arrays may be arranged in any suitable manner.

[00105] For example, the coil arrays of the subsystems can be arranged as a two-dimensional array.

Accordingly, in addition to its horizontally neighbouring subsystems, the controller 180 of each subsystem may further be in data communication with the controller 180 of its vertically and diagonally neighbouring subsystem(s).

[00106] Figure 4 illustrates coil arrays of an exemplary wireless power transfer apparatus according to another embodiment. As shown by the dashed lines, this wireless power transfer apparatus includes 16 subsystems and thus 16 coil arrays. These 16 coil arrays are arranged in a 4x4 array, each coil array having the same structure as the one shown in Figure 2A - Figure 2D.

[00107] For each subsystem, although only one example of the design of the coils are provided above, it would be understood by a person skilled in the art that any suitable design may be used for the coil. For example, each coil may be formed in any suitable shape, size and material. Further, each subsystem may include any suitable number of coils, and the coils may be arranged in any suitable manner.

[00108] The design and the arrangement of the coils and the power supply 150 of each subsystem can be selected to be compliant (or at least compatible) with a corresponding wireless charging standard, e.g., the Qi Standard or the PMA standard, and the coils of different subsystems can be compliant with respective different wireless charging standards. Alternatively, each subsystem can include multiple power supplies 150 supporting respective different wireless charging standards, and the controller selectively connects the power supply 150 that matches the type of power receiving device detected in the searching mode (e.g., Qi, PMA or Apple watch). In general, a coil array can be designed to support multiple standards, e.g., by selecting the parameters that are compatible multiple standards or that can be combined to achieve this. For example, one approach is to configure the coil array based on the standard that requires the highest coil inductance, and to connect multiple coils to a single power supply 150 in parallel (i.e. turn on multiple switches at once) to decrease the equivalent inductance to a level required by (or at least compatible with) the power supply of the other standard(s). If the receiver coil sizes in the plurality of standards are similar, taking this approach requires no substantial hardware modification to the above-described embodiments.

The power supply

[00109] The power supply 150 in each subsystem generates and outputs the AC power signal used to energise the coils in the searching mode of the subsystem, and in the charging mode of the subsystem.

[00110] The power supply 150 can be any suitable existing power supply for wireless charging, for example any known power supply compliant to existing wireless charging standards, such as Qi, AW4P, or MFI. Figure 5 illustrates a circuit schematic diagram of an exemplary power supply 150 that is compatible with the Qi standard.

[00111] In the described embodiments, the power supply 150 may, for example, be a COTS

('commercial off the shelf) wireless charging power transmitter supply.

The multiplexer

[00112] As described above, the multiplexer 160 of each subsystem includes a controller 180 and a switching component 190.

[00113] The controller 180 executes a wireless power transfer process 600, as shown in Figure 6, to control the operation of the switching component 190. In this way, each of the subsystems continually searches for the presence of a power receiving device within charging range, and, when detected, enters the charging mode to charge the power receiving device using the primary coil of the subsystems that provides the most efficient charging while reducing or avoiding interference between primary coils in different (typically adjacent) subsystems.

[00114] In the described embodiments, the controller 180 includes a microcontroller 180 chip and the wireless power transfer process 600 is implemented as a software program stored on nonvolatile storage associated with the controller 180 (e.g., as firmware).

[00115] In the described embodiment, the controller 180 is an ST Microelectronics STM8S103k6t6c microcontroller 180 (as described at http://www.st.com/en/microcontroller 180s/stm8sl03k3.html), which provides the advantage of low cost and a high GPIO/Cost ratio. [00116] Alternatively, in other embodiments any other suitable microcontroller 180 or equivalent electronic component(s) may be used as the controller 180.

[00117] Under control of the controller 180, the switching component 190 connects the output of the power supply to a selected one of the primary coils at any given time.

[00118] In the described embodiment, the switching component 190 switches power to each primary coil using a corresponding simple MOSFET-based AC switch known to those skilled in the art, which allows making and breaking connections at high power (~10A) and high frequency AC (~1 MHz). As each subsystem shown in Figure 1 includes 24 coils, 24 switches are used. For the entire apparatus 100 which includes four subsystems, 96 switches are used in total. However, in other embodiments each subsystem of the apparatus can be scaled to any practical number of primary coils 170 by including the same number of switches. Further, in other embodiments the switching component 190 may alternatively include other means to selectively provide power to the charging coils under control of the controller 180.

[00119] In the described embodiments, a printed circuit board (PCB) is used to provide both mechanical support for and electrical connections to the coils, the power supply and the multiplexer. The PCB defines the precise spatial arrangement of the coils and provides the electrical routing between the electronic components in a single manufacturing step, and thus allows manufacturing of the apparatus 100 in a low-cost manner. Figure 11 A to Figure 11 C illustrates an exemplary embodiment of the apparatus 100 based on a PCB.

Workflow

[00120] Figure 6 is a flow diagram of the wireless power transfer process 600 executed by the controller 180 of each subsystem.

[00121] In the described embodiment, each subsystem includes a coil array of 24 coils arranged as illustrated in Figure 2A - Figure 2D. This arrangement is identical for each subsystem, and the coil arrays tessellate to form a homogeneous array across four subsystems, as shown in Figure 3A and Figure 3B. The use of identical arrays ensures consistent charging performance across the apparatus 100.

[00122] In the described embodiment, each coil in a subsystem is associated with a unique identifier corresponding to its position, but that identifier is identical across subsystems. The unique identifier may be, e.g., a serial number. [00123] For example, in Figure 2A, the 24 coils are identified as Number 0 - Number 23. As illustrated in Figure 2A, coils Number 0 to Number 5 are located on the left edge of the coil array, and coils Number 18 to Number 23 are located on the right edge of the coil array.

[00124] The corresponding relationship between the unique identifier of a coil and its location in the coil array is stored, e.g., in an internal memory of the controller 180. It may be embedded into the controller 180 as data associated with, or as part of, the process executed by the controller 180.

[00125] Referring to Figure 6, at step 602, the controller 180 controls the switching component 190 to connect a coil Number X (where X is initialised to 0) to the power supply (also referred to in the art and herein as the "transmitter", abbreviated as "Tx"), preparing for the detection of the power receiving device. When connecting the coil Number X to the Tx, the switching component 190 also disconnects other coils from the Tx.

[00126] At step 604, the controller 180 determines whether coil Number X is near an edge of the subsystem. This determination is made based on the arrangement of the coils in the subsystem.

[00127] For example, for the coil array shown in Figure 2A, if X = 0, 1 , 2, 3, 4 or 5, the controller 180 determines that it is near the left edge. Alternatively, if X = 18, 19, 20, 21 , 22 or 23, the controller 180 determines that it is near the right edge.

[00128] In this example, as the four coil arrays of the four subsystems are arranged to form a row in the horizontal direction as shown in Figure 3B, only the left edge and/or right edge of the coil array of each subsystem can potentially interfere with the coils in an adjacent coil array.

[00129] However, in some other embodiments, the coil arrays of the subsystems can be arranged in a two-dimensional array, for example as shown in Figure 4. Accordingly, up to four edges of a subsystem can potentially interfere with the coils in its adjacent coil array(s) on the left, right, top, and/or bottom side, and the coils in a diagonally neighbouring coil array, and the controller 180 may determine accordingly that a coil is on the edge of the subsystem if the coil is located on any of the four edges of the coil array shown in Figure 2A.

[00130] Further, in some other embodiments, the coil array of each subsystem may include more than 24 coils, arranged in more than four columns as shown in Figure 2A. Accordingly, two or more columns of coils near the edge may potentially interfere with an adjacent subsystem, and therefore may be identified as a coil near an edge. [00131] Referring back to Figure 6, if the controller 180 determines that the coil Number X is located on the left edge of the subsystem (e.g., if the number of the coil is between 0 and 5), the controller 180 sends a signal to the controller 180 of the adjacent subsystem on its left side, notifying that adjacent subsystem of the number of the coil being connected (as shown in step 606). This may be performed by utilising a transceiver port or other type of output interface of the controller 180.

[00132] Similarly, if the controller 180 determines that the coil Number X is located on the right edge of the subsystem (e.g., if the number of the coil is between 18 and 23), the controller 180 sends a signal to the controller 180 of the adjacent subsystem on its right side, notifying that adjacent subsystem of the number of the coil being connected (as shown in step 608).

[00133] After step 606 or 608, or if at step 604 the controller 180 determines that the coil Number X is neither located on the left edge nor on the right edge, the controller 180 proceeds to step 610, in which the controller 180 detects whether a power receiving device is placed in a charging area of coil Number X.

[00134] In some embodiments, this detection is carried out by checking the Tx for a signal indicating the successful detection of a power receiving device.

[00135] For example, if the Tx is a transmitter compliant with the Qi standard, it generates a HIGH/LOW signal indicating whether a resonance shift is detected following a very short pulse (referred to in the art and herein as an "analog ping") output by the Tx.

[00136] According to the Qi standard (e.g. Section 10.1 of The Qi Wireless Power Transfer System Power Class 0 Specification, Parts 1 and 2: Interface Definitions), when detecting a power receiving device, the Tx outputs a short pulse to one of its primary coils at an operating frequency f 0 d, which corresponds to the (LC) resonance frequency of the coil and series capacitance, resulting in a coil current l 0 d which can be measured by the Tx. The measured value of the coil current lod indicates whether or not a power receiving device is present within the charging area (also referred to herein and in the art as the "active area") of the coil. The Tx can apply the pulses at regular intervals to different coils to which the multiplexer has connected in order to determine which coil is best aligned with the receiver coil of the power receiving device.

[00137] Alternatively, the transmitter may be compliant with a wireless charging standard other than Qi, and the signal may reflect the result of a similar detection following that wireless charging standard. [00138] In some embodiments, the Tx also performs a digital ping after the analog ping process, in which the Tx wakes up and communicates with the receiver coil of the power receiving device to better locate the power receiving device (as described in Section 5.1 and Annex B of The Qi Wireless Power Transfer System Power Class 0 Specification, Parts 1 and 2: Interface Definitions). The signal output from the Tx may accordingly indicate the result of a combination of the analog ping and the digital ping.

[00139] In some other embodiments, the detection of the power receiving device is carried out by the controller 180 itself performing an on-board measurement of the mutual inductance or capacitance of the coil Number X and the potential power receiving device. In some embodiments, the controller 180 is configured to generate a short pulse signal the same as or similar to the "analog ping" described above and in section 10. 1 of the Qi standard, and detect whether there is a resonance shift following the short pulse. For example, if the inductance or capacitance is higher than a corresponding predetermined value, the controller 180 deems that the power receiving device is detected. The measurement of the inductance or capacitance is performed using standard methods known to those skilled in the art.

[00140] In some embodiments, the inductance or capacitance measurement is used in combination with checking the signal from the Tx.

[00141] For example, the controller 180 can perform the inductance or capacitance measurement first and then determine whether to check the detection signal generated by the Tx, and only check the signal from the Tx if the inductance or capacitance measurement returns a positive result. That is, the inductance or capacitance measurement is used as an initial filter to reduce the number of coils that need to be checked using the signal from the Tx.

[00142] As the inductance or capacitance measurement can be performed at a higher speed than the detection performed by the Tx, this can improve the speed of the detection of the power receiving device.

[00143] In detecting the power receiving device, if the power receiving device is detected, the controller 180 can also determine whether the coil Number X provides better coupling to the receiver coil of the power receiving device than its adjacent coils in the same subsystem.

[00144] In some embodiments, the detection of the power receiving device and the determination of the coupling quality is performed in a single measurement, for example, by measuring the mutual inductance of coil Number X and the potential power receiving device. [00145] As an example, the controller 180 compares the measured inductance value to at least one of a predetermined minimum inductance value and a predetermined typical inductance value.

[00146] If the measured inductance is lower than the minimum inductance value, the controller 180 deems that no device is detected, and proceeds to step 612 of Figure 6 to increment the coil number X being processed.

[00147] Alternatively, if the measured inductance is higher than the typical inductance value, the controller 180 determines that a power receiving device is detected, and proceeds to step 616 of Figure 6 to cease the scanning and to enter the charging state at coil Number X.

[00148] Alternatively, if the measured inductance is between the minimum inductance value and the typical inductance value, the controller 180 checks whether the measured inductance of any adjacent coil is higher than the inductance of coil Number X. If so, the controller 180 deems that coil Number X is not providing the best coupling with the receiver coil of the power receiving device, in other words, coil NumberX is a suboptimal coil. In that case, the controller 180 stops scanning and enters the charging state using the adjacent coil that provides the highest inductance. Alternatively, if none of the adjacent coils reports a higher inductance value than coil Number X, the controller commences charging with coil Number X, because the poor coupling is likely caused by external factors, e.g., a thick phone case or a small receiver coil of the power receiving device.

[00149] Examples of the minimum inductance value and the typical inductance value are shown in Table 2.

Table 2: Examples of minimum inductance values

and typical inductance values

[00150] In some other embodiments, the coupling quality may be received from the Tx. For example, if the Tx is compliant with the Qi standard, the coupling quality may be determined based on the signal strength packet output by the Tx.

[00151] As a result of step 610, if the power receiving device is detected, the controller 180 ceases the scanning of the coils and enters the charging state at the current coil Number X at step 616, and charges the device at step 618. The controller 180 also regularly loops back to step 610 to determine whether the power receiving device can still be detected, and whether the current coil is still the coil that provides the optimal coupling quality. This allows the subsystem to react in a timely manner when the charging is completed or the power receiving device is removed or moved. The subsystem terminates the charging when the charging is completed or the device is removed. In the described embodiments, this is handled by the power supply 150. The subsystem can change the coil used for charging when the location of the power receiving device relative to the subsystem has changed.

[00152] On the other hand, if no power receiving device is detected, or the coil Number X is not providing the best coupling with the receiver coil of the power receiving device, the controller 180 may proceed to step 612 and increment the coil number X being processed.

[00153] Next, at step 614, the controller 180 determines whether scanning coil Number X after the increment of X would interfere with the scanning or charging in an adjacent subsystem.

[00154] Similar to the notification sent at step 606 and step 608 to an adjacent subsystem, the current subsystem also receives notification from its adjacent subsystem(s) indicating which coil(s) are currently being scanned or charged in the adjacent subsystem(s). This may be performed by receiving data using a transceiver port or other type of input port of the controller 180.

[00155] Upon obtaining the number of coil being scanned or charged in the adjacent subsystem(s), the controller 180 determines whether interference is likely to occur if coil Number X is to be scanned. This may be determined based on the arrangement of the coils in the subsystem.

[00156] For example, in the example shown in Figure 3B, the controller 180 of subsystem 1 10 may determine that the scanning of coil Number 20 of subsystem 110 would severely interfere with the scanning or charging of coil Number 2 or coil Number 3 of subsystem 120 on its right side, and may partially interfere with the scanning or charging of coil Number 1 or coil Number 4 of subsystem 120. This determination can be performed by looking up one or more coil interference tables that records the potential interference between coils of adjacent subsystems. Examples of coil interference tables are shown in Figure 7A - 7D.

[00157] For the example illustrated in Figure 3B, subsystems are adjacent with each other horizontally. Figure 7A shows the corresponding coil interference table indicating the potential interference between coils of subsystems that are horizontally adjacent to each other. [00158] For the example illustrated in Figure 4, subsystems may be adjacent with each other either in a horizontal, vertical or diagonal direction. Accordingly, in addition to Figure 7 A that shows the horizontal interference. Figure 7B shows the potential interference between coils of subsystems that are vertically adjacent with each other, and Figure 7C and Figure 7D show the potential interference between coils of diagonally neighbouring subsystems. In these cases, in addition to its horizontally neighbouring subsystems, the controller 180 of each subsystem may further be in data communication with the controller 180 of its vertically and diagonally neighbouring subsystem(s).

[00159] The coil interference table may be stored, e.g., in an internal memory of the controller 180. It may be installed into the controller 180 together with or as part of the software program to be executed by the controller 180. Utilisation of the coil interference table(s) may allow the operation of the controller 180 to easily adapt to different configuration of coil arrays. If the arrangement of the coils is changed, the determination of the controller 180 may be changed by simply replacing the coil interference table(s).

[00160] Upon determining that the scanning of coil Number X would interfere (either severely or partially) with the scanning or charging of coil(s) in one or more adjacent subsystems, the controller 180 can avoid scanning coil Number X, for example, by delaying or skipping the scanning of coil Number X. In that case, the controller 180 proceeds to step 612 of Figure 6 to increment the coil number being processed. In some embodiments, the controller 180 resumes the scan of coil Number X that has been delayed when the potential interference is resolved.

[00161] If the controller 180 has determined that there would be no interference, it then loops back to step 602 to scan the coil Number X.

[00162] Although not shown in Figure 6, the dimensions of the coils are typically much smaller than the dimensions of the power receiving devices.

[00163] As a result, when a coil in one subsystem is charging a power receiving device, it is unlikely that a nearby coil belonging to an adjacent subsystem would provide optimal inductive coupling for charging another power receiving device.

[00164] Accordingly, in addition to the determination of potential interference at step 614, the controller 180 also determines whether coil Number X is too close to an adjacent subsystem that is charging a power receiving device. If so, the controller 180 delays or skips the scanning of the coil Number X, and loops back to step 612 to increment the coil number being processed.

[00165] As described above, this logic allows the process to avoid searching coils that are unlikely to provide optimal inductive coupling, and thereby improve the searching efficiency of the subsystem.

General Structure of Exemplary Embodiments

[00166] The present invention will now be herein after described with reference to exemplary embodiments.

[00167] The wireless power transfer device, shown in Figures 12, 13, 14 and 15, and generally designated by the numeral 1200, includes a plurality of transmitters 1209 which formed on printed circuit board (PCB) 1201 in the form of an array of transmitters. The device 1200 further includes a controller which may be likewise embodied on a PCB 1202, as shown in Figure 14. The wireless power transfer device 1200 is in this embodiment, configured as a modular unit in ‘tile-like’ form, incorporating a top housing portion 1203, and, a bottom housing portion 1204.

[00168] The top housing portion 1203 and bottom housing portion 1204 are each adapted to be physically connected together to form the‘tile-like’ modular unit shown in Figure 12. The housing, formed by the top and bottom components 1203 and 1204, respectfully, therefore incorporate the printed coil array 1201 , and, the main control and power printed circuit board 1202.

[00169] Therebetween, a shielding may be incorporated as shown in Figure 14 at 1205, formed of ferrite or other material. As would be understood by persons skilled in the art, this shields electromagnetic radiation emanating from the main controller power printed circuit board 1202 from the printed coil array on the printed circuit board 1201. Shielding also serves to increase magnetic field density on the opposite side of the coil from that which is shielded.

[00170] A typical array of printed coils is shown in Figure 15. This example specifically illustrates an array of 53 printed coils, formed in 5 rows. The 1 st , 3 rd and 5 th rows each incorporate eleven printed coils, whilst the 2 nd and 4 th rows each incorporate ten printed coils. As would be understood by persons skilled in the art, the array may be formed of by any number of coils 1209 in both the vertical and horizontal directions.

[00171] Figure 12 also illustrates how the modular unit 1200 may be connected to a power source 1206. The power source 1206 may of course be alternatively formed integrally within the modular unit 1200. Figure 12 also shows the provision of a receiver device 1207, in this case, a smart phone, positioned on the wireless power transfer device 1200.

[00172] A plurality of the modular units 1200 may be operatively connected together as shown in Figure 13. Figure 13 shows seven modular units 1200 interconnected, to receiving power via a single power cable 1206. The interconnected modular units in Figure 13 show three receiver devices, in this case three smart phones, being charged by the composite modular wireless power transfer device 1210.

[00173] The modular units 1200 may be operatively connected to each other via connectors 1208 which are illustrated in Figure 12. Details of the connectors 1208 are also shown in exploded form in Figures 14 and 15. As illustrated in Figure 15, these may be provided along one or more sides of the modular unit 1200, and serve to electrically connect multiple modular units together.

[00174] As will be understood from the afore-mentioned description, each of the plurality of transmitters 1209 are each adapted to transmit power to a receiver device 1207.

[00175] In a first mode, or searching mode, the controller on PCB 1202 detects the presence of the receiver device 1207 proximal to one or more of the transmitters 1209. The controller then determines which of the transmitters is an ‘optimal’ transmitter based on measures of electromagnetic coupling to the receiver device 1207. One or more‘optimal’ transmitter may be selected. The controller then determines which of the transmitters 1209 adjacent to the ‘optimal’ transmitter is a‘conflict’ transmitter based on proximity to the‘optimal’ transmitter.

[00176] Then, in a charging mode, the controller selectively energises the‘optimal’ transmitters whilst preventing any‘conflict’ transmitters from being simultaneously energized. That is, one or more‘optimal’ transmitter may be energized, whilst any‘conflict’ transmitter(s), which may be proximal to the‘optimal transmitter(s) and which may cause interference with the‘optimal’ transmitter(s), are prevented from being energized.

[00177] As herein before described, the transmitters are preferably formed as an array of transmitters, as shown in Figure 15. Each of the plurality of the transmitters may be formed as a printed coil array, as shown in Figure 15, or alternatively, may be formed as a more traditional inductor coil or chip or any other transmitter device. Each of the transmitters may substantially abut or partially overlap at least one other transmitter.

[00178] In use, each transmitter emanates an electromagnetic field therefrom which would preferably at least partially overlap the electromagnetic field from at least one other transmitter in the array. As shown in Figure 13, the power transfer device is adapted to simultaneously power a plurality of receiver devices 1207. [00179] The power transfer device may be adapted to be connected to a power source 1206 including an external power supply, or a power supply formed intricately within the device.

[00180] The transfer device preferably incorporates a control which includes a multiplexer device. In the searching mode, each of the transmitters is energized by being connected to a power supply source. If a receiver of a corresponding receiver device is within charging range of the corresponding transmitter, a corresponding measure of the electromagnetic coupling between the energized transmitter and the corresponding receiver is determined. One or more of the energized transmitters is selected on the basis of measures of electromagnetic coupling such that, in the charging mode, the selected transmitter is/are connected to the power source to transmit power to the corresponding power receiving device.

[00181] To avoid electromagnetic interference between energized transmitter coils each transmitter is only energized if that transmitter coil is sufficiently distant from other energized transmitter coils.

[00182] The transmitters may be energized selectively and/or sequentially.

[00183] However, each transmitter is preferably only energized if that transmitter is not adjacent to any other energized transmitter.

[00184] As illustrated in Figure 13, the device is adapted to be operatively connected to one or more similar power transfer devices and, in that form, the controller is adapted to operate across all connecting devices as if it were a single device.

Applications and advantages

[00185] The apparatus 100 provides a continuous charging area that allows free-positioning of the power receiving device. It is also capable of charging multiple power receiving devices simultaneously. Moreover, it can effectively reduce the electromagnetic interference between adjacent subsystems.

[00186] By simply increasing the number of subsystems, embodiments of the apparatus can be easily scaled to any practical desired size. Further, as multiple subsystems can be combined in any suitable arrangement within a single apparatus, the charging area of the apparatus can be scaled to any suitable 2-dimensional area of essentially arbitrary shape.

[00187] As the power supply of each subsystem can be an existing standard-compliant (or at least compatible) transmitter, commercially available "off-the-shelf" wireless charging transmitters can be used in the apparatus, which can significantly reduce the cost of manufacturing such an apparatus.

[00188] Further, the above-described structure and operation of the apparatus is not limited to any particular wireless charging standard, but can be readily adapted to support any one or more of a variety of different inductive resonant wireless charging standards, by simply replacing the power supply and the coil array and making minor changes to the multiplexer that will be apparent to those skilled in the art.

[00189] In some embodiments, different subsystems in the apparatus are compliant with different wireless charging standards, e.g., by adopting different power supply and different coil arrays. Figure 8 shows an example of a wireless power transfer apparatus 800 that includes four subsystems: 810, 820, 830 and 840. As shown, the two subsystems 810 and 820 are compliant with a wireless charging standard A, while the two subsystems 830 and 840 are compliant with a wireless charging standard B.

[00190] In some embodiments, a single subsystem is compliant with multiple wireless charging standards by including multiple power supplies in that single subsystem. For example. Figure 9 shows an example of a wireless power transfer apparatus 900 that includes four subsystems: 910, 920, 930 and 940. As shown, each of the subsystems 910 and 920 are compliant with a single wireless charging standard A. Each of the other subsystems 930 and 940, on the other hand, is compliant with two different wireless charging standards: standard B and standard C. As shown in Figure 9, each of these other subsystems 930 and 940 includes two power supplies, compliant with standards B and C respectively, both connected to the multiplexer in their subsystem.

[00191] Further, two or more of the subsystems in the apparatus described herein can be used to simultaneously charge the same power receiving device. This requires the power receiving device to have multiple secondary coils and a relatively large footprint so that it can span multiple subsystems. Accordingly, the secondary coils of the power receiving device can be aligned with respective transmitting coils of the multiple subsystems. As multiple subsystems can simultaneously transmit power to the same power receiving device, a higher power output to the power receiving device can be achieved. This can be particularly advantageous for charging power receiving devices that have high power requirements, e.g., a laptop computer or a tablet computer.

[00192] Figure 10 is a schematic diagram showing the use of a wireless power transfer apparatus 1200 according to some embodiments. Each of the squares 1010 represents an individual subsystem, which includes both the clear section and the immediately adjacent shadowed sections 1020, representing overlap between adjacent subsystems. Each square 1010 is capable of detecting and powering a power receiving device. The apparatus 1000 includes 36 such squares 1010. Accordingly, the apparatus 1000 is capable of charging up to 36 devices simultaneously.

[00193] If a particular subsystem is either scanning a coil in an overlap area, or charging a device in an overlap area, other overlapping subsystems that share the same overlap area then adaptively avoid scanning any of their own coils that would have interference with that coil, ensuring no adverse interactions between the subsystems.

[00194] If a power receiving device is placed on the overlapping portion of two subsystems, and one of those subsystems is already charging another device, the unoccupied subsystem charges the newly placed device so that both devices can be charged simultaneously. Border regions where the corners of four subsystems overlap follow similar arrangements.

[00195] Further, in some embodiments, if one of the subsystems is powering a device, the other subsystems will adaptively avoid scanning coils in the immediately adjacent area if scanning those coils would otherwise interfere with the charging in that one subsystem.

[00196] In Figure 10, each of the rectangles 1030 represents a device that has been placed on the surface of the system and is being charged. The black circles within the rectangles 1030 represent the specific coils that are being used for charging the corresponding device. If any of those coils lies in an overlap area (1020), then the immediately adjacent coils will not be searched by neighboring subsystems (1010).

[00197] The large square 1040 represents a larger power receiving device, e.g., a laptop, that is being charged by multiple subsystems simultaneously to achieve a higher charging power. Preferably, the power receiving device may have multiple receiver coils that can be aligned with coils in multiple subsystems. No significant change to the apparatus needs to be made to the apparatus 1000 to deliver this functionality. As each subsystem has its own independent power supply, and the subsystems are spaced apart in the same horizontal plane (with the same surface area for cooling), the charging apparatus provides improved thermal performance compared to existing charging devices that can charge multiple power receiving devices. Further, compared to a prior art system using a single coil, the use of multiple subsystems as described herein allows the use of multiple smaller coils, which also reduces the generation of heat, and a higher level of coil alignment can be achieved regardless of the location of the receiving coil of the power receiving device.

[00198] The dotted squares 1050 represent subsystems that are compliant with a wireless charging standard that is different from the standard compliant by the other subsystems of the apparatus 1000. In this way, the same device 1000 is capable of charging devices compliant with multiple wireless charging standards.

[00199] Throughout this specification the wireless power transfer device/apparatus has been described as incorporating transmitter coils, etc. It should be appreciated by persons skilled in the art that the transmitters are able to be used with the present invention include any coil, chip or printed circuit board inductor or other like transmitter device. As such, these terms should be considered to be used interchangeably throughout the specification and claims.

[00200] The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that that prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavor to which this specification relates.

[00201] Many modifications will be apparent to those skilled in the art without departing from the scope of the present invention.