Wireless power transfer apparatus

Abstract

There is disclosed a wireless power transfer apparatus (10, 100, 200, 2500) including at least one non-planar flux coupling structure (12, 112, 212, 213). The non-planar flux coupling structure may include a first set of coil portions (14, 114, 214, 2014, 3014) spaced along a first axis (A, A1, A2), and a second set of coil portions (16, 116, 216, 2016, 3016) spaced along a second axis (B, B1, B2). The first and second sets of coil portions may be at least partially disposed in or on a curved or non-planar surface (18, 118, 218). The first axis and second axis may be tilted at opposite angles (α, β, α1, β1).

Description

[0001] WIRELESS POWER TRANSFER APPARATUS

[0002] CROSS-REFERENCE TO RELATED APPLICATION

[0003] This application claims priority from United Kingdom patent application number 2310844.2 filed on 14 July 2024, which is incorporated by reference herein.

[0004] FIELD

[0005] This disclosure relates to an electromagnetic structure and a wireless power transfer apparatus for generating and receiving magnetic flux.

[0006] BACKGROUND

[0007] Inductive wireless power transfer (IWPT) systems include transmitter and receiver coils through which flux coupling is achieved. Power is transferred from the transmitter coil, in which electricity generates magnetic flux, to the receiver coil in which electricity is induced by means of magnetic flux coupling.

[0008] In the case of planar flux couplers, the transmitter and receiver coils are disposed in a flat plane, which may be suitable in applications where the objects to which they are applied are likewise planar, such as a handheld device and a charging pad on which the device is placed.

[0009] Non-planar flux couplers come in various configurations, including solenoid coils, semi-cylindrical coils, hemi-cylindrical coils, circumferential coils, double helix conductors and concentric tilted double helix dipole arrangements. Existing arrangements may not, however, be ideal for all applications. For example, the only one of these that can couple with flux perpendicular to the axis of the coil is the double helix coil. However, this comes at the cost of utilising large amounts of space and copper. Most of these coils are also not tightly coupled, and most of these couplers have higher magnetic field strength inside the cylindrical body which means that the space cannot house electronic devices. The existing couplers are also bulky in size and configuration, and they often make use of excessive copper or other conductive materials.

[0010] Another problem with double helix conductors is that they experience a flux cancellation when used as a receiver due to their symmetry. This can cause losses in efficiency. A need exists for a wireless power transfer apparatus having a coupler that can effectively utilise magnetic materials (e.g., ferrite) as well as conductive materials (e.g., copper), has a relatively small footprint but with a satisfactory coupling coefficient.

[0011] The preceding discussion of the background is intended only to facilitate an understanding of the present disclosure. It should be appreciated that the discussion is not an acknowledgment or admission that any of the material referred to was part of the common general knowledge in the art as at the priority date of the application.

[0012] SUMMARY

[0013] In accordance with an aspect of the present disclosure there is provided a wireless power transfer apparatus including at least one non-planar flux coupling structure, wherein the non-planar flux coupling structure includes a first set of coil portions spaced along a first axis, and a second set of coil portions spaced along a second axis, wherein the first and second sets of coil portions are at least partially disposed in or on a curved or non-planar surface, and wherein the first axis and second axis are tilted at opposite angles.

[0014] The curved or non-planar surface may extend along a longitudinal axis thereof. The first axis and the second axis may be tilted relative to the longitudinal axis of the curved or non-planar surface. The first set of coil portions and second set of coil portions may be formed by folding or bending the single coil along a line which divides the single coil into two portions.

[0015] The curved or non-planar surface may have a fixed cross-sectional profile along a longitudinal axis thereof.

[0016] The first set of coil portions may at least partially overlap the second set of coil portions.

[0017] The curved or non-planar surface may be a portion of a cylindrical surface.

[0018] The first and second sets of coil portions may be arcuate.

[0019] The first axis and the second axis may be tilted relative to the longitudinal axis of the curved or non-planar surface.

[0020] The angle of tilt of the first axis may be equal to the angle of tilt of the second axis. The angle of tilt of each of the first and second axes may be about 45 degrees.

[0021] The non-planar flux coupling structure may be a flux receiver. The apparatus may include a flux transmitter.

[0022] The flux transmitter may be a planar flux transmitter, or it may be a non-planar flux transmitter.

[0023] The curved or non-planar surface may have a tapering cross-sectional profile along a longitudinal axis thereof.

[0024] The curved or non-planar surface may have a fixed cross-sectional profile that extends along a circumferential path.

[0025] The first set of coil portions may be part of a first coil. The second set of coil portions may be part of a second coil.

[0026] The first coil may include a set of coil portions disposed in or on a flat surface. The second coil may include a set of coil portions disposed in or on a flat surface.

[0027] The coil portions of the first coil disposed in or on the flat surface may overlap the coil portions of the second coil disposed in or on the flat surface.

[0028] The first set of coil portions and second set of coil portions may be part of a single coil.

[0029] The first set of coil portions and second set of coil portions may be formed by folding or bending the single coil along a line which divides the single coil into two portions.

[0030] The apparatus may include a magnetic structure positioned inside or outside one of the first and second coil portions to facilitate inductive coupling by the apparatus.

[0031] The magnetic structure may be made from ferrite or aluminium, or a combination of these.

[0032] The magnetic structure may include one or more strips positioned along the curved or non-planar surface.

[0033] Embodiments of the technology will now be described, by way of example only, with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In the drawings:

[0035] Figure 1 is a schematic three-dimensional view of an exemplary embodiment of a wireless power transfer apparatus having a non-planar coupling structure that may be used as a flux receiver;

[0036] Figure 2 is a top view of the wireless power transfer apparatus of Figure 1 ;

[0037] Figure 3 is a schematic three-dimensional view of an exemplary embodiment of a flat wireless power transfer apparatus that has a planar coupling structure that may be used as a flux transmitter, e.g., in conjunction with the flux receiver of Figure 1 ;

[0038] Figure 4 is a schematic three-dimensional view of another exemplary embodiment of a wireless power transfer apparatus having a non-planar coupling structure that may be used as a flux transmitter, e.g., in conjunction with the flux receiver of Figure 1 ;

[0039] Figure 5 is a schematic side view of the wireless power transfer apparatus of Figure 1 ;

[0040] Figure 6 is a schematic side view of the wireless power transfer apparatus of Figure 1 , illustrating exemplary magnetic field strength near the apparatus as vectors;

[0041] Figure 7 is a schematic end view of the wireless power transfer apparatus of Figure 1 , illustrating exemplary magnetic field strength near the apparatus as vectors;

[0042] Figure 8 is a schematic three-dimensional view of another exemplary embodiment of a wireless power transfer apparatus having a non-planar coupling structure that may be used as a flux receiver;

[0043] Figure 9 is a top view of the wireless power transfer apparatus of Figure 8;

[0044] Figure 10 is a schematic side view of the wireless power transfer apparatus of Figure

[0045] 8;

[0046] Figure 11 is a schematic side view of the wireless power transfer apparatus of Figure 8, illustrating exemplary magnetic field strength near the apparatus as vectors;

[0047] Figure 12 is a schematic end view of the wireless power transfer apparatus of Figure 8, illustrating exemplary magnetic field strength near the apparatus as vectors; Figure 13 is a schematic three-dimensional view of another exemplary embodiment of a wireless power transfer apparatus having a plurality of non-planar coupling structures that can be used as a flux transmitter and as a flux receiver;

[0048] Figure 14 is a schematic side view of the apparatus of Figure 13;

[0049] Figure 15 is a schematic end view of the apparatus of Figure 13;

[0050] Figures 16-18 are schematic three-dimensional views of further exemplary embodiments of wireless power transfer apparatuses similar to that of Figure 8, but with a ferrite core, ferrite sheets, and an inner ferrite structure, respectively;

[0051] Figure 19 is a schematic three-dimensional view of another exemplary embodiment of the wireless power transfer apparatus with an outer ferrite structure;

[0052] Figure 20 is a schematic three-dimensional view of another exemplary embodiment of a wireless power transfer apparatus that has a quadrilateral shape with an angled rim, that may be implemented as a flux transmitter;

[0053] Figure 21 is a side view of the apparatus of Figure 20;

[0054] Figure 22 is an end view of the apparatus of Figure 20;

[0055] Figures 23-24 are schematic illustrations of an exemplary application of the wireless power transfer apparatus in an electric scooter;

[0056] Figure 25 is a front or end view of another exemplary embodiment of a wireless power transfer apparatus or electromagnetic structure with inner and outer coil portions that are radially spaced with a gap between them so as to accommodate a core structure therebetween;

[0057] Figure 26 is a side view of the apparatus of Figure 25;

[0058] Figure 27 is a top view of the apparatus of Figure 25;

[0059] Figure 28 is a bottom view of the apparatus of Figure 25; and

[0060] Figures 29-32 are schematic illustrations of an exemplary application of the electromagnetic structure of Figure 25 in conjunction with a vessel to be heated, such as a water heater application.

[0061] DETAILED DESCRIPTION WITH REFERENCE TO THE DRAWINGS

[0062] Non-planar coil designs are proposed which have a compact profile, efficient use of copper and ferrite material, have a high coupling coefficient and take advantage of ferrite to shape the flux. The present disclosure may find many applications in different products or services. These range from using one or more coils or coil structures in biomedical devices, electric bikes, autonomous underwater vehicles and potentially electric vehicles. The coil structures may be applied to any non-planar or curved geometry to enable wireless power transfer. This may alleviate the drawbacks of using traditional planar coils, e.g., in applications with non-planar surfaces. Bespoke charging solutions for existing products may be provided and products may be built specifically around the proposed coil designs. The present disclosure may enable a coupler with a relatively small footprint or size while providing a satisfactory coupling coefficient for non-planar applications.

[0063] Wireless power transfer apparatuses are disclosed. It will be appreciated that a wireless power transfer apparatus may refer to a flux receiver or a flux transmitter or a combination of both. The wireless power transfer apparatus may also be termed a coupler, which may include a flux transmitter and / or a flux receiver. Each of the flux transmitter and the flux receiver may have a plurality of windings or loops or coil portions. These may also be termed coupling structure(s) or coil structure(s). The coil structures or coupling structures may be made from conductive material, such as, but not limited to copper. In embodiments of the present disclosure, sets of coil portions and their individual windings may be arranged so as to be evenly spaced, or they may be spaced regularly. However, embodiments are possible in which the sets of coil portions and each of their windings are spaced irregularly or in a predefined formation. The coil portions may be at least partially arcuate, curved, or non-planar.

[0064] The present disclosure extends to a wireless power transfer device that includes at least first and second coil portions, with the first coil portion extending toward a first direction, and the second coil portion extending toward a second direction which is different from the first direction. The first coil portion may also be termed a first series of half-loops, and the second coil portion may be termed a second series of half-loops. In the various embodiments of the present disclosure, coil structure(s) may be provided on top of or underneath or generally adjacent to magnetic material such as ferrite or aluminium structures. Alternatively, the coil structures may be embedded inside the magnetic material. Embodiments of the present disclosure may provide an increased coupling coefficient (or a decrease in a percentage of flux losses that occur between a flux transmitting coil and a flux receiving coil). Having a higher coupling coefficient provides increased efficiency by which wireless power can be transferred in use.

[0065] The present disclosure extends to an electromagnetic structure which has one or more coil portions or coil structures. The electromagnetic structure may be used for any one or more of: wireless power transfer; induction applications in general; induction heating; electromagnetic actuation, e.g., as a solenoid or solenoid inductor; or as a transformer.

[0066] Figures 1 -2 and 5-7 show a first exemplary embodiment of a wireless power transfer apparatus (10). Figures 3-4 show exemplary embodiments of further wireless power transfer devices, in this case flux transmitters, that may be used with, or that may form part of the wireless power transfer apparatus (10). For example, the apparatus of Figure 1 may be used as a flux receiver, and the apparatus of either Figure 3 or Figure 4 may be used as a flux transmitter, i.e., when it is electromagnetically coupled with the flux receiver of Figure 1. Figures 8-12 show an alternative exemplary embodiment of a wireless power transfer apparatus (100), which may also be used as a flux receiver, for example. Figures 13-15 show yet another alternative embodiment of a wireless power transfer apparatus (200). In this embodiment the wireless power transfer apparatus may include both a flux transmitter and a flux receiver. Figures 16-22 show yet further exemplary embodiments of wireless power transfer apparatuses (300, 400, 500, 600, 700). Figures 23-24 shows an exemplary practical implementation of a wireless power transfer apparatus and system in accordance with aspects of the present disclosure. Throughout the Figures, similar features may be designated by similar reference numerals.

[0067] In Figures 1 , 2 and 5 there is shown an exemplary embodiment of a wireless power transfer apparatus (10) according to aspects of the present disclosure. The wireless power transfer apparatus (10) may include at least one non-planar flux coupling structure (12). In the present embodiment, the non-planar flux coupling structure (12) includes a first set of coil portions (14) spaced along a first axis (A), and a second set of coil portions (16) spaced along a second axis

[0068] (B) (see Figure 5). In the exemplary embodiment, the first and second sets of coil portions (14, 16) are at least partially disposed in or on a curved or non-planar surface (18). The curved or non- planar surface (18) can be seen in the three-dimensional view of Figure 1 , and it is also diagrammatically illustrated by broken lines in the end view of Figure 7.

[0069] In the present embodiment, the first axis (A) and second axis (B) are tilted at opposite angles (designated a, and p respectively in Figure 5). In other words, the first set of coil portions (14) may be spaced along, or in a general direction of, the first axis (A), while the second set of coil portions (16) may be spaced along, or in a general direction of, the second axis (B). The first and second axes (A, B) may be tilted relative to one another, at opposite angles. In the exemplary embodiment, the first set of coil portions (14) are tilted at a first angle (a) from a longitudinal axis

[0070] (C) of the apparatus (10); whereas the second set of coil portions (16) are tilted at a second angle (P) from the longitudinal axis (C) of the apparatus (10). In the present embodiment, and in the other embodiments of the present disclosure, the coil portions may be made from an electrically conductive material, such as copper or another metal. However, many other types of conductive materials may be used.

[0071] Referring again to Figures 1 , 2 and 5-7, the first set of coil portions (14) may be part of a first coil and the second set of coil portions (16) may be part of a second coil. The first set of coil portions (14), and the second set of coil portions (16) may each have a plurality of windings or turns that form the coil. In embodiments of the present disclosure, the first and second sets of coil portions (14, 16) may be connected in series, however embodiments may be possible in which the coil portions are separate; or embodiments may be possible in which the first and second sets of coil portions are connected in parallel. The present embodiment (10) may have two layers of concentric hemi-circles tilted at opposite angles and shifted until the inner and out layer align along an axis of both coils.

[0072] Referring to Figure 7, in the exemplary embodiment, the curved or non-planar surface (18) may have a fixed cross-sectional profile along a longitudinal axis thereof. The longitudinal axis (C) of the apparatus (10) may also be a longitudinal axis of the curved or non-planar surface (18) in which, or along which, the first and second sets of coil portions (14, 16) may extend. The curved or non-planar surface may be an imaginary surface or three-dimensional surface that may define the shape of the first and second sets of coil portions (14, 16). The exemplary fixed cross-sectional profile of the curved or non-planar surface (18) may be shaped as a segment, e.g., a segment of a circle, or a segment of an oval or other shape. It will be appreciated that many other shapes of the curved or non-planar surface may be possible. In the present embodiment, the first axis (A) and the second axis (B) may be tilted relative to the longitudinal axis (C) of the curved or non- planar surface (18). It will be appreciated that the longitudinal axis (C) may be a central axis, but it may also simply extend lengthwise, e.g., not necessarily aligned with a centre of the shape of the cross-sectional profile of the non-planar surface (18). The height of the segment-shaped curved or non-planar surface (18) may be optimised. For example, a height of half a circle may be advantageous and it may provide a higher coupling coefficient.

[0073] In the schematic end view of the wireless power transfer apparatus (10) shown in Figure 7, exemplary magnetic field strength(s) near the apparatus are illustrated as vectors or vector arrows.

[0074] As is perhaps more evident in Figure 1 , the curved or non-planar surface (18) may, at least partially, be a portion of a cylindrical surface. The first set of coil portions (14) may have a curved part (14.1 ), as well as a straight or transverse part (14.2). The second set of coil portions (16) may have a curved part (16.1 ), as well as a straight or transverse part (16.2). In the present embodiment, the first and second sets of coil portions (14, 16) may at least partially overlap. In particular, the straight or transverse parts (14.2, 16.2) of the first and second sets of coil portions (14, 16) may at least partially overlap. The first coil may include a set of coil portions (14.2) disposed in or on a flat surface. This may also be termed the straight or transverse part (14.2) of the first coil. The second coil may include a set of coil portions (16.2) disposed in or on a flat surface. This may also be termed the straight or transverse part (16.2) of the second coil, or a flat face of the second coil which may be substantially parallel to a longitudinal axis (C) of the coil.

[0075] The coil portions (14.2) of the first coil disposed in or on the flat surface may overlap the coil portions (16.2) of the second coil disposed in or on the flat surface. However, embodiments may also be possible, and it may even be preferable in some cases, to implement first and second coil portions that do not overlap one another. The first set of coil portions (14) and the second set of coil portions (16) may be part of a single coil (e.g., connected in series), or they may be separate coils.

[0076] The first and second sets of coil portions (14, 16) may be generally arcuate, or at least the curved parts (14.1 , 16.1 ) thereof may be arcuate. Presently, these curved parts (14.1 , 16.1 ) have a semicircular cross-sectional shape, but they may also be defined by other shapes such as semi- cylindrical, semi-ovoid, semi-oval, etc.

[0077] In embodiments of the present disclosure, the angle of tilt (a) of the first axis (A) may be equal to the angle of tilt (P) of the second axis (B). However, these angles need not be equal, and embodiments are envisaged in which the first angle (a) is greater than the second angle (P), or embodiments in which the first angle (a) is smaller than the second angle (P). The angle of tilt of each of the first and second axes may be about 45 degrees. It is envisaged that an angle of about 45 degrees for the first and second angles (a, P) may result in maximum perpendicular flux by the apparatus (10). However, this angle can be varied to alter the component of perpendicular flux. Other angles such as 50 degrees or 30 degrees or any angle from 25 degrees to 60 degrees may be used.

[0078] In the present embodiment (10), the first set of coil portions (14), or at least the curved part (14.1 ) thereof, may extend in a first direction (e.g., along axis (A)); and the second set of coil portions (16), or at least the curved part (16.1 ) thereof may extend in a second direction (e.g., along axis (B)), away from the first direction. In the present embodiment (10), the coil’s windings, or loops of the first set of coil portions (14) may be slanted or tilted relative to the second set of coil portions (16) by an angle (©). The angle (©) may, for example, be 90 degrees, but many other configurations or arrangements are possible.

[0079] It will further be appreciated that the wireless power transfer apparatus (10) of Figures 1 , 2 and 5-7 may be used as a flux receiver. However, with the present embodiment and other embodiments of the present disclosure, the apparatus may be used as, or may include, either a flux receiver or a flux transmitter (or both) depending on practical considerations. In other words, any of the coil structures may be used either as a flux transmitter or as a flux receiver.

[0080] In a presently envisaged embodiment, the non-planar flux coupling structure (12) may be a flux receiver. The wireless power transfer apparatus (10) may further include a flux transmitter (15), e.g., as shown in Figure 3. In other words, the apparatus (10) may include both a flux receiver (12) and a flux transmitter (15). The flux transmitter (15) and the flux receiver (12) may be arranged to couple electromagnetically, so as to transfer wireless power. The wireless power transfer apparatus (15) (in this case a flux transmitter) of Figure 3 has planar coupling structure that may be used in conjunction with the flux receiver (12) of Figure 1 , e.g., with the flux receiver (12) positioned on top of or in close proximity with the flux transmitter (15). In use, coil portions (17) of the flux transmitter may be energized electrically, and cause magnetic flux to be generated and transferred to the flux receiver (12) which may receive said flux thereat. The flux transmitter (15) may include a magnetic structure (22) which will be described in more detail below.

[0081] The flux transmitter may be a planar flux transmitter or a non-planar flux transmitter. In the embodiment of Figure 3, a planar flux transmitter is implemented, e.g., in conjunction with the flux receiver apparatus of Figure 1. An alternative embodiment is shown in Figure 4, in which a wireless power transfer apparatus (50) has a non-planar coupling structure. The non-planar coupling structure may have first and second angled coil portions (52, 54), as well as a central coil portion (56). The apparatus (50) of Figure 4 may, for example, be used as a flux transmitter, and the angled coil portions (52, 54) may be shaped to accommodate the first and second sets of coil portions (14, 16) of the wireless power transfer apparatus (10) of Figure 1 (in this case acting as a flux receiver). This may have the advantage of better coupling, because the angled coil portions (52, 54) may be positioned closer to the curved parts (14.1 , 16.1 ) by way of them being angled. This may, e.g., cause more perpendicular flux and better wireless power transfer in general.

[0082] In the present embodiment of the wireless power transfer apparatus (10) of Figure 1 and 7, the curved or non-planar surface (18) has fixed cross-sectional profile that extends along the longitudinal axis (C) shown in Figure 5. However, it is also envisaged that an embodiment may be possible in which the curved or non-planar surface may have a tapering cross-sectional profile along a longitudinal axis thereof. In other words, one or both of the first and second sets of coil portions may be tapered along the longitudinal axis, e.g., arranged to fit into a cone-shaped or frustum-shaped flux transmitter (or flux receiver, as the case may be).

[0083] A further alternative embodiment is also envisaged in which the curved or non-planar surface extends along a circumferential or curved path. In other words, instead of along the longitudinal axis (C), the curved or non-planar surface may have a fixed cross-sectional profile that extends along a circumferential path, e.g., so that the first and / or second sets of coil portions are shaped as part of a toroid. Le., the coil portions may extend near a periphery of a toroidal shape, and the toroidal shape may extend along a curved path.

[0084] Referring to Figure 5, the wireless power transfer apparatus (10) may further include one or more magnetic structures (20, 22) positioned inside or outside one of the first and second coil portions to facilitate inductive coupling by the apparatus. Ferrite may be used as magnetic structure, or aluminium, or a combination of both, or other magnetic materials. A layer of aluminium may be provided on or under a layer of ferrite to form the magnetic structure (20, or 22 as the case may be). In an example embodiment, a first magnetic structure (20) may be provided inwardly of the coil structures or coil portions, e.g., adjacent to the flat portions (14.2, 16.2), and a second magnetic structure (22) may be provided outwardly of the coil portions. In a presently envisaged embodiment, the second magnetic structure (22) may be provided by the flux transmitter (15), and coil portions (17) of the flux transmitter (designated diagrammatically by broken lines in Figure 5) may be located inwardly of the magnetic structure (22). The magnetic structure may also be termed a shielding structure. The magnetic structure may be made from ferrite or aluminium, or a combination of these.

[0085] It will be appreciated that the flux transmitter (50) of Figure 4 may also be used instead of the flat one of Figure 3. The flux transmitter (50) of Figure 4 may also have a magnetic structure (23) or shielding structure, presently positioned outside the coil structure of the flux transmitter. The magnetic material (20, 22, 23 - as the case may be) may also shape the flux, and / or it may increase the inductance of one or more of the coil structures near the magnetic material. The flux shaping may result in less leakage flux (which is safer when the device is used near humans, or e.g., in electric scooter applications). Implementing the flux transmitter (50) of Figure 4 (an area of the coil may be about 288 cm2) in conjunction with a flux receiver such as that of Figure 1 , may result in a coupling coefficient of at least 0.6, or of 0.79 at an exemplary air gap of 5 mm when implementing magnetic material or shielding structures (e.g., as shown in Figures 4-5). It will be appreciated that the coupling coefficient may vary as the coil area and air gap parameters are varied. The conditions under which the coupling coefficient is measured may also affect it.

[0086] Another exemplary embodiment of a wireless power transfer apparatus (100) is shown in Figures 8-12. In some respects, this embodiment (100) may be similar to the other embodiments of the present disclosure and in other respects it may differ, as will become apparent from what follows. It will, nonetheless, be appreciated that any of the embodiments described may include one or more features of the other embodiments, and vice versa. Turning to Figure 8, there is shown an exemplary embodiment of a wireless power transfer apparatus (100) according to aspects of the present disclosure. The wireless power transfer apparatus (100) may include at least one non-planar flux coupling structure (112). In the present embodiment, the non-planar flux coupling structure (1 12) includes a first set of coil portions (1 14) spaced along a first axis (A1 ), and a second set of coil portions (1 16) spaced along a second axis (B1 ) (see Figure 10). In the exemplary embodiment, the first and second sets of coil portions (1 14, 1 16) are at least partially disposed in or on a curved or non-planar surface (1 18). The curved or non-planar surface (1 18) can be seen in the three-dimensional view of Figure 8, and it is also diagrammatically illustrated by broken lines in the end view of Figure 12.

[0087] In the present embodiment, the first axis (A1 ) and second axis (B1 ) are tilted at opposite angles (designated a1 , and pi respectively in Figure 10). In other words, the first set of coil portions (114) may be spaced along, or in a general direction of, the first axis (A1 ); while the second set of coil portions (1 16) may be spaced along, or in a general direction of, the second axis (B1 ). The first and second axes (A1 , B1 ) may be tilted or angled relative to one another, at opposite angles. In the exemplary embodiment, the first set of coil portions (114) are tilted at a first angle (a1) from a longitudinal axis (C1 ) of the apparatus (100); whereas the second set of coil portions (16) are tilted at a second angle (pi) from the longitudinal axis (C1) of the apparatus (100). Having larger tilt angles may be advantageous, since larger tilt angles may cause more perpendicular flux.

[0088] The first set of coil portions (114) and the second set of coil portions (116) may be part of a single coil. The first set of coil portions (1 14) and the second set of coil portions (116) may, for example, be formed by folding or bending the single coil along a line (e.g., along or towards axis (C1 )) which divides the single coil into two portions. These two coil portions or the two sets of coil portions (114, 1 16) may be equal in size and / or equal in a number of coil windings. However, embodiments may also be possible in which the first and second sets of coil portions each have a different number of windings or turns. The axis (C1 ) may be an axis of symmetry, e.g., an axis of symmetry of the coil when it is un-bent. The coil may be bent through this imaginary axis of symmetry to form the coil structure depicted in Figure 8. However, the axis (C1 ) need not be an axis of symmetry. It will also be understood that the coil structure of the apparatus (100) may take up less three-dimensional space than known coil structures.

[0089] In the present embodiment (100), the coil may be inwardly bent from an initially circular, oval, or other geometric shape, so that the first set of coil portions (114) of the coil extends in a first direction, and so that the second set of coil portions (1 16) of the coil extends in a second direction, away from the first direction. In the present embodiment (100), the coil’s windings, or loops may be bent at an angle (©1 ) which may for example be 90 degrees. However, many other folding or bending angles may be possible. In the present embodiment, one or more face(s) of the coil structure may be bent inward by an angle (e.g., 45 degrees relative to the longitudinal axis (C1 )). However, other angles such as 50 degrees or 30 degrees, or any angle from 25 degrees to 60 degrees, or any angle from 0 degrees to 90 degrees may be used. The coil face(s) may be shaped so as to be perpendicular (i.e., radially perpendicular) to the longitudinal axis of the coil. The present embodiment (100) may include a bent circular winding axially spaced to form a semi- cylindrical shape as shown in Figure 8. Ferrite can optionally be placed around an outer curve of the coil (which may be a flux transmitter) and within the hollow of the coil structure (e.g., when implemented as a flux receiver).

[0090] Referring to Figure 10, the wireless power transfer apparatus (100) may further include one or more magnetic structures positioned inside or outside one of the first and second coil portions to facilitate inductive coupling by the apparatus. Ferrite may be used as magnetic structure, or aluminium, or a combination of both; or other magnetic materials can be used. A layer of aluminium (e.g., a layer of 1 mm thick) may be provided on or under a layer of ferrite to form a magnetic structure. Other thicknesses of the aluminium layer, or varying thicknesses of the ferrite structure(s) may also be possible. In an example embodiment, a magnetic structure (122) may be provided outwardly of the coil portions. In a presently envisaged embodiment, the magnetic structure (122) may be provided by a flux transmitter (similar to one of the flux transmitters of Figures 3 or 4), and coil portions (117) of the flux transmitter (designated diagrammatically by broken lines in Figure 5) may be located inwardly of the magnetic structure (122). The magnetic structure may also be termed a flux guider or shielding structure. Magnetic materials may be arranged to guide the flux and / or also to shield it. On the other hand, aluminium or any conductive material may be arranged to only shield the magnetic flux. It will be appreciated that any of the other embodiments of the present disclosure may be used as a flux transmitter (e.g., including but not limited to the embodiments of Figures 17-18) in conjunction with the flux receiver (100) of Figure 8.

[0091] Further features of the embodiment (100) of Figures 8-12 may be similar to those of the embodiment of Figures 1 , 2 and 5-7. However, it will be appreciated that the flux which may be generated in the coil portions (1 14, 116) may be different, amongst other things due to the different shape of the first and second sets of coil portions (114, 116) compared to those of the other embodiment (10). This is evident from Figures 11 -12 which illustrate exemplary magnetic field strength near the apparatus (100) of the present embodiment as vectors. This difference in flux may, at least partially be attributed to the absence of the flat parts (14.2, 16.2) from the present embodiment (100), as well as due to the first and second coil portions (114, 1 16) being part of a single coil which has been bent.

[0092] Referring to Figure 12, in the exemplary embodiment (100), the curved or non-planar surface (118) may have a fixed cross-sectional profile along a longitudinal axis thereof. The longitudinal axis (C1 ) of the apparatus (100) may also be a longitudinal axis of the curved or non-planar surface (118) in which, or along which, the first and second sets of coil portions (1 14, 1 16) may extend. The curved or non-planar surface may be an imaginary surface or three-dimensional surface that may define the shape of the first and second sets of coil portions (1 14, 116). The exemplary fixed cross-sectional profile of the curved or non-planar surface (118) may be shaped as a part of a segment, e.g., part of a segment of a circle, or part of a segment of an oval or other shape. In particular, the cross-sectional profile of the curved or non-planar surface (1 18) may be shaped as a chord, or it may be arcuate. It will be appreciated that many other shapes of the curved or non-planar surface may be possible (e.g., a portion of a triangle, oval, circle, rectangle, square, etc.). In the present embodiment (100), the first axis (A1 ) and the second axis (B1) may be tilted relative to the longitudinal axis (C1 ) of the curved or non-planar surface (1 18). It will be appreciated that the longitudinal axis (C1 ) may be a central axis, but it may also simply extend lengthwise, e.g., not necessarily aligned with a centre of the shape of the cross-sectional profile of the non-planar surface (1 18).

[0093] In the present embodiment the faces of the coil structures or coil portions (1 14, 1 16) are arcuate. However, it will be understood that other shapes are also possible, such as partially triangular, angular, part of a hexagon, or any other geometric shape which is non-planar. The coil structure of Figure 8 may also be used as a flux transmitter or as a flux receiver, in conjunction with a flat; or with a curved or non-planar flux receiver or transmitter.

[0094] In the schematic end view of the wireless power transfer apparatus (100) shown in Figure 12, exemplary magnetic field strengths near the apparatus are illustrated as vectors or vector arrows. A leakage field may be minimised by the present embodiment. By increasing the tilting of the first and second coil portions (1 14, 1 16), a larger portion of the central part of the coil structure of the apparatus (100) may be exposed to perpendicular flux vectors (e.g., that are perpendicular to a face of the coil structure). This may increase efficiency of wireless power transfer. In other words, by increasing the tilt angle, or by providing the coil portions at tilted angles, a larger portion of the central part of the coil structure of the apparatus (100) may be exposed to perpendicular flux vectors, thereby increasing efficiency of wireless power transfer.

[0095] It will be appreciated that various embodiments of the present disclosure are possible in which the wireless power transfer apparatus (100) may be used as a flux receiver, i.e., arranged to receive magnetic flux. However, the wireless power transfer apparatus (100) may also be used as a flux transmitter, i.e., arranged to transmit magnetic flux when energised by electrical energy.

[0096] It will further be appreciated that the embodiment (100) of Figures 8-12 may include one or more further features of the embodiment (10) described with reference to Figures 1 -2 and 5-7, and vice versa.

[0097] In Figures 13-15 is shown yet another exemplary embodiment of a wireless power transfer apparatus (200). It will be appreciated that the embodiment (200) of Figures 13-15 may include one or more features of the other embodiments of the present disclosure, and vice versa. In present embodiment (200), the wireless power transfer apparatus (200) may include a flux transmitter (270) and a flux receiver (280). The flux transmitter (270) and the flux receiver may be complementarily shaped, so that they may fit inside one another. One of the flux transmitter and flux receiver may be shaped slightly larger than the other, to facilitate fitment and coupling between the transmitter and receiver coils. A close fit between the transmitter and receiver coils may facilitate or improve wireless power transfer between the flux transmitter (270) and the flux receiver (280), e.g., by virtue of the capturing of additional perpendicular flux that may occur between the transmitter (270) and the receiver (280).

[0098] In the present embodiment, each of the flux transmitter (270) and the flux receiver (280) may be similar to the wireless power transfer apparatus (100) described above with reference to Figure 8, and all of its features will not be repeated here for the sake of brevity. In other words, the wireless power transfer apparatus (200) may include two complementarily shaped coils (212, 213), which may also be termed an outer coil and an inner coil. The first and second coils (212, 213) may each include at least one non-planar flux coupling structure. In the present embodiment, each non-planar flux coupling structure (212, 213) of each of the coils may include a first set of coil portions (2014, 3014) spaced along a first axis (A2), and a second set of coil portions (2016, 3016) spaced along a second axis (B2). In the exemplary embodiment, the first and second coils (212, 213) with their respective sets of coil portions (2014, 2016, 3014, 3016) may be at least partially disposed in or on a curved or non-planar surface (218) which can be seen more clearly in Figure 15. The wireless power transfer apparatus may act as a coupler or an inductive coupler, and it may include the flux transmitter (212) and the flux receiver (213). The flux receiver (213) may be positioned radially inwardly of the flux transmitter (212). However, the positions of the flux transmitter and flux receiver may also be reversed, with the flux transmitter radially inwardly, and the flux receiver positioned radially outwardly. The apparatus (200) may have a plurality of non- planar coupling structures that can be used as a flux transmitter and as a flux receiver. A curved coil may provide better wireless power transfer (i.e., it may provide a better coupling coefficient) when coupled with another curved coil. E.g., the first and second coil structures (212, 213) may exhibit a better coupling coefficient than if one of the coils were flat. It may provide an advantage in coupling coefficient by implementing complimentarily shaped transmitting and receiving coils (e.g., both curved). Another advantage is envisaged by the flux transmitting coil (270) “gripping” or securing the flux receiving coil (280). This may inhibit misalignment (i.e., it may facilitate a better coupling coefficient). The flux transmitting coil (212) can also be made larger than the flux receiving coil (213) to inhibit misalignment during wireless power transfer. Leakage field may be minimised by the present disclosure, due to the close interface between the curved or non-planar surfaces of the first and second coil structures (212, 213). Implementing the flux transmitter (212) of Figure 13 in conjunction with the flux receiver (213) of Figure 13, may result in a coupling coefficient of at least 0.9 or even as high as 0.985. By bringing the flux transmitting coil (212) into registration with the flux receiving coil (213), an increased coupling coefficient may be achieved.

[0099] Figures 16-18 show exemplary embodiments (300, 400, 500) of flux receivers with coil structures that may at least partially correspond to those of Figure 8. Different magnetic structures (301 , 401 , 402, 501 ) are implemented. The magnetic structures may be ferrite structure(s), and they may be arranged to improve a coupling coefficient between the coil structure and another coil structure with which it is coupled. The magnetic structure(s) may be made from ferrite or aluminium, or a combination of these. In the exemplary embodiment (300) of Figure 16, a (preferably solid) ferrite core (301 ) is positioned radially inwardly of the coil structure or inwardly of the coupling structure. In the exemplary embodiment (400) of Figure 17, a plurality of ferrite sheets (401 ) are arranged inwardly of the coil structure, and the ferrite sheets or strips (401 ) may extend lengthwise, e.g., along a major axis of the coil structure. The magnetic structure may hence include one or more strips positioned along the curved or non-planar surface. In the exemplary embodiment (500) of Figure 18, a ferrite structure or sleeve (501 ) is positioned radially inwardly of the coil structure or inwardly of the coupling structure. The flux receivers (300, 400, 500) of Figures 16-18 may alternatively be implemented as flux transmitters.

[0100] In Figure 19 is shown an exemplary embodiment (600) of a flux transmitter with coil structures that may at least partially correspond to those of Figure 8. In the present embodiment (600), an outer ferrite shielding structure (601 ) is positioned radially outwardly of the coil structure. It is envisaged that the flux receiver (500) of Figure 18 may be used with (i.e., be coupled with) the flux transmitter (600) of Figure 19 to form a substantially enclosed coupler or a substantially enclosed wireless power transfer apparatus. Another embodiment which is envisaged is an embodiment in which the one or more coils can be embedded in a housing or guider body; or the coils can be provided or formed on the housing.

[0101] The flux transmitter coil structures (e.g., 300, 400, 500), and the flux receiver coil structures (e.g., 600) may be shaped so as to trade off material usage for improved misalignment performance. For example, a transmitter coil which is larger than the receiver coil can result in a better misalignment performance. Moreover, mechanical guiders can also be utilised to minimise misalignments. E.g., the flux receiver coil (500) and its housing or structure (501 ) may act as a guide to be received by the flux receiver’s housing (601).

[0102] It will be appreciated that ferrite may be used in the various embodiments of the present disclosure as a material to facilitate a coupling coefficient of the apparatus, but other magnetic materials may also be used in addition to, or instead of ferrite.

[0103] Figures 20-22 show another exemplary embodiment (700) of a wireless power transfer apparatus that can be implemented e.g., as a flux transmitter coil structure. In the present embodiment, the wireless power transfer apparatus (700) may have a quadrilateral shape with an angled rim (701 ). The present embodiment may be used to couple with any one of the other embodiments of the present disclosure.

[0104] Figures 27-28 shows an exemplary implementation of a wireless power transfer apparatus (800) in accordance with aspects of the present disclosure. One or more coil structures may be implemented. For example, a first coil structure (801 ) that may correspond to that of Figure 8 may be implemented in a vehicle, e.g., an electric scooter. The coil structure (801 ) may for example be embedded inside a vertical pole or inside a frame or chassis of the scooter, and it may act as a flux receiver, e.g., to charge a battery of the electric scooter by inductive charging. A corresponding coil structure (802) may be provided at a charging station to act as a flux transmitter. The flux transmitter may have a similar coil structure to that of Figure 8. One or more magnetic materials or shielding materials such as ferrite structures may also be implanted as described in the present disclosure, to facilitate or improve coupling. This may also provide the advantage of easier storage while charging, since the scooter can be folded up (e.g., vertically) next to the pole of the charging station. An exemplary interface between the receiver and transmitter coil structures (801 , 802) is shown in the diagrammatic enlarged portion in Figure 23.

[0105] Figures 25-28 show another example (2500) of the technology. The present version may be similar to that of Figure 8, and it also includes a first set of coil portions (2514) and a second set of coil portions (2516) (see the top and bottom views in Figures 27-28). It may also include at least one non-planar flux coupling structure, and the first and second sets of coil portions are at least partially disposed in or on a curved or non-planar surface. However, in the present version, the first and second sets of coil portions (2514, 2516) are spaced radially. In other words, as can be seen from the front view in Figure 25, there is a gap (2590, see Figs. 25 and 27) between an outer set of coil portions (2514, i.e., the first set of coil portions) and an inner set of coil portions (2516, i.e., the second set of coil portions). This gap (2590) or spaced relationship may enable a core or central structure (2501 ) to be located between the inner and outer coil portions.

[0106] A ferrite core (2501 ) may for example be used, but it will be appreciated that core structures of other materials (preferably with ferromagnetic properties) may also be used. The material may preferably be a metallic material with desirable electromagnetic properties. The spacing of the inner and outer coil structures or the spacing between the inner and outer (i.e., first and second) coil portions may facilitate inductance or inductive properties of the device (2500). The coil portions may be wrapped around the core structure (e.g., made from ferromagnetic material).

[0107] As with the embodiment of Figure 8, in the present embodiment (2500), the coil portions (2514, 2516) may be bent or folded back (see Figures 26-27). In other words, the coil with its coil portions (2514, 2516) may be formed by folding the coil along a line which divides the single coil into two portions. I.e., effectively the coil may be folded back onto itself, in a radially inward direction. The gap between the inner and outer coil portions may be provided when forming the coil structure by the aforementioned bending or folding process, so as to leave space for the ferrite core (2501 ) or other core structure which may facilitate magnetic properties and / or aid flux properties. Presently the core (2501 ) may be curved and / or semi-cylindrical. However, other shapes may also be possible.

[0108] In an exemplary implementation, the device (2500) may be used in conjunction with a vessel (2550) or container. The vessel or container may e.g., contain a fluid which is to be heated by induction heating. The fluid may e.g., be water, or another fluid that requires heating. The vessel may, e.g., be a water tank of a water heating application, or it may even be a cup of coffee or another beverage that requires heating. It will be appreciated that various vessels with fluid (water, gas, etc.) may be used in conjunction with the wireless power transfer apparatus (2500). As before, it will also be appreciated that one or more features of the present embodiment may be used in conjunction with selected features from one or more of the other embodiments of the present disclosure.

[0109] It will be appreciated that many other applications may be possible, for example underwater vehicles, electric vehicles or cars, drones and many others. It is further envisaged that another application of the coil structure(s) may be to use an exemplary coil structure for inductive heating of water boilers or water heaters. This may also be termed wireless power transfer, seeing as the inductive heating may transfer electric energy to the fluid such as water to be heated. In such an embodiment, a first coil structure (e.g., similar to that of Figure 8) may be provided around or adjacent to a vessel or container that has fluid such as water therein. The coil may then be energized by electrical energy, and this may transfer power as heat (wirelessly) to the water or other fluid inside the container or vessel. The container or vessel may be rounded, or it may have a cylindrical shape, so as to easily interface with the curved or non-planar surface of the coil structure.

[0110] Embodiments of the present disclosure may provide advantages over known double helix couplers, and over conventional planar couplers. For example, the coupling structures of the present disclosure may require less material usage, while also providing a better coupling coefficient, and alleviating leakage flux. Embodiments of the present disclosure may further provide the advantage of reducing flux cancellation which is prevalent with known apparatuses. In other words, flux cancellation of the receiving coil structure may be reduced by the present disclosure (e.g., when receiving flux from a flux transmitting coil). This may increase the coupling efficiency between the flux transmitting and flux receiving coil structures. The present disclosure may implement asymmetrical coil structures (e.g., that occupy only a portion or segment of a cross sectional shape such as a circle or oval). This may alleviate the drawback of known couplers with symmetrical shapes, such as double helix structures that suffer from flux leakage problems.

[0111] Embodiments of the present disclosure may also provide increased perpendicular flux transfer between the transmitting coil and the receiving coil. This may be particularly evident when implementing a curved or non-planar transmitter coil in conjunction with a curved or non-planar receiver coil because the coil structures can interface more directly than with previously known apparatuses. Leakage field may also be minimised by embodiments of the present disclosure. The present disclosure may provide the advantage of decreasing a distance between the transmitter coil structure and the receiver coil structure, which may increase coupling efficiency.

[0112] The shape of the coil designs of the present disclosure may produces a field profile which enables high coupling as it reduces flux cancellation when used as a receiver coil in wireless power transfer applications. The coil shapes of the present disclosure may also enable the efficient use of ferrite or magnetic material. The coil designs of the present disclosure may also have improved utilisation of space in non-planar applications as they may not need to be wound around a non- planar object. The coil design may also efficiently use copper wire without sacrificing coupling coefficient when compared to traditional flux couplers. Leakage field shielding offered by the present disclosure may enable housing sensitive electronic devices near the apparatus, and / or using the apparatus in or near living humans or animals, especially in an interior space where the coil is fitted.

[0113] The foregoing description has been presented for the purpose of illustration; it is not intended to be exhaustive or to limit the technology to the precise forms disclosed. Persons skilled in the relevant art can appreciate that many modifications and variations are possible in light of the above disclosure.

[0114] The language used in the specification has been principally selected for readability and instructional purposes, and it may not have been selected to delineate or circumscribe the inventive subject matter. It is therefore intended that the scope of the present disclosure be limited not by this detailed description, but rather by any claims that issue on an application based hereon. Accordingly, the present disclosure is intended to be illustrative, but not limiting, of the scope of any accompanying claims.

[0115] Finally, throughout the specification and any accompanying claims, unless the context requires otherwise, the word ‘comprise’ or variations such as ‘comprises’ or ‘comprising’ will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

Claims

CLAIMS:

1. A wireless power transfer apparatus including at least one non-planar flux coupling structure, wherein the non-planar flux coupling structure includes a first set of coil portions spaced along a first axis, and a second set of coil portions spaced along a second axis, wherein the first and second sets of coil portions are at least partially disposed in or on a curved or non-planar surface, wherein the first axis and second axis are tilted at opposite angles, wherein the curved or non-planar surface extends along a longitudinal axis thereof, wherein the first axis and the second axis are tilted relative to the longitudinal axis of the curved or non-planar surface, and wherein the first set of coil portions and second set of coil portions are formed by folding the single coil along a line which divides the single coil into two portions.

2. The wireless power transfer apparatus as claimed in claim 1 , wherein the curved or non- planar surface has a fixed cross-sectional profile along the longitudinal axis thereof.

3. The wireless power transfer apparatus as claimed in claim 1 , wherein the first set of coil portions at least partially overlap the second set of coil portions.

4. The wireless power transfer apparatus as claimed in claim 2 or claim 3, wherein the curved or non-planar surface is a portion of a cylindrical surface.

5. The wireless power transfer apparatus as claimed in any one of the preceding claims, wherein the first and second sets of coil portions are arcuate.

6. The wireless power transfer apparatus as claimed in any one of claims 1 to 5, wherein the angle of tilt of the first axis is equal to the angle of tilt of the second axis.

7. The wireless power transfer apparatus as claimed in claim 6, wherein the angle of tilt of each of the first and second axes are about 45 degrees.

8. The wireless power transfer apparatus as claimed in any one of claims 1 to 7, wherein the non-planar flux coupling structure is a flux receiver and wherein the apparatus includes a flux transmitter.

9. The wireless power transfer apparatus as claimed in claim 8, wherein the flux transmitter is a planar flux transmitter or a non-planar flux transmitter.

10. The wireless power transfer apparatus as claimed in claim 1 , wherein the curved or non- planar surface has a tapering cross-sectional profile along a longitudinal axis thereof.1 1 . The wireless power transfer apparatus as claimed in claim 1 , wherein the curved or non- planar surface has a fixed cross-sectional profile that extends along a circumferential path.

12. The wireless power transfer apparatus as claimed in any one of claims 1 to 11 , wherein the first set of coil portions are part of a first coil and the second set of coil portions are part of a second coil.

13. The wireless power transfer apparatus as claimed in claim 12, wherein the first coil includes a set of coil portions disposed in or on a flat surface and the second coil includes a set of coil portions disposed in or on a flat surface.

14. The wireless power transfer apparatus as claimed in claim 13, wherein the coil portions of the first coil disposed in or on the flat surface overlap the coil portions of the second coil disposed in or on the flat surface.

15. The wireless power transfer apparatus as claimed in any one of claims 1 to 11 , wherein the first set of coil portions and second set of coil portions are part of a single coil.

16. The wireless power transfer apparatus as claimed in any one of the preceding claims, wherein the apparatus includes a magnetic structure positioned inside or outside one of the first and second coil portions to facilitate inductive coupling by the apparatus.

17. The wireless power transfer apparatus as claimed in claim 16, wherein the magnetic structure is made from ferrite or aluminium, or a combination of these.

18. The wireless power transfer apparatus as claimed in claim 16 or claim 17, wherein the magnetic structure comprises one or more strips positioned along the curved or non- planar surface.

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