EP4732311A1 - A coupler for an hfac system - Google Patents

Abstract

A coupler for coupling an HFAC power supply bus to an electrical device to be powered is disclosed herein. The coupler comprises: a two-part core joinable at an interface to provide a magnetic yoke for inductive coupling of windings carried by the core with an HFAC power supply bus, wherein parts of the core are pivotable to slide relative to each other along the interface, to open the core to admit the HFAC power supply bus and to close the core to complete the magnetic yoke.

Description

A coupler for an HFAC system Field of Invention The present invention relates to couplers for HFAC systems, and more specifically, to a coupler for coupling an HFAC power supply bus to an electrical device to be powered. Background Conventional electrical mains distribution systems and the grid as we know it usually supply electricity at 90-264V AC and the frequency 47-63 Hz, depending on the jurisdiction. Electrical products are either hard wired with connectors or junction boxes using a variety of mains power connection plugs and sockets or other permanently fixed connection systems. Standard mains voltage is known to be potentially hazardous to work on due to the frequency of 47–63Hz and all connections to an installation, with the exception of simply plugging in appliances with traditional mains plugs, require the expertise of qualified and agency-approved electricians. Furthermore, AC Power presents a danger of electrocution which is exacerbated in wet conditions or when there are exposed or damaged cabling or connections. When providing power in outside environments, for example, communal play areas, gardens, swimming pools, around ponds, parks and elsewhere, additional safety procedures must be legally followed, for example, the use of IP6x waterproof junction boxes, armoured cables and resin filled connector blocks. Not only can this be notoriously difficult and time-consuming, but such equipment must be professionally installed by qualified electricians and carries a potential electrical shock risk to the installer and the consumer, and a fire risk to property in the event of a fault or damage. Increasing the frequency of the AC supply above 10kHz into the high frequency alternating current (HFAC) domain provides a safe alternative to traditional potentially dangerous AC power distribution, providing a system whereby appliances may be connected inductively. This takes the improved safety aspect of HFAC one step further as the power/load circuit is inductively coupled to a HFAC power supply. High frequencies, typically in excess of 10kHz are used so that efficient inductive power transfer can take place. As electrical devices and components are inductively powered, installation is quicker and simpler and furthermore does not carry the same risks of electrocution in any condition, even in wet environments. Such systems allow for a plurality of electrical devices to be spaced apart along a power supply bus, improving ease of installation and safety. Summary Aspects of the disclosure are set out in the independent claims and optional features are set out in the dependent claims. Aspects of the disclosure may be provided in conjunction with each other and features of one aspect may be applied to other aspects. Embodiments of the disclosure may permit couplings between the devices and the bus to be repeatedly opened and closed whist reducing or avoiding mechanical damage to the coupler (which provides coupling between the electrical device and the bus). This may improve the longevity of the coupler while still allowing the devices to be installed and/or moved easily. The present application aims to solve this problem, among others. An aspect of the disclosure provides a coupler for coupling an HFAC power supply bus to an electrical device to be powered, the coupler comprising: a two-part core joinable at an interface to provide a magnetic yoke for inductive coupling of windings carried by the core with an HFAC power supply bus, wherein parts of the core are pivotable to slide relative to each other along the interface, to open the core to admit the HFAC power supply bus and to close the core to complete the magnetic yoke. Additionally, the coupler may further comprise a first magnetic element slidable with a first part of the core and arranged to cooperate with a corresponding magnetic element associated with a second part of the core to secure the core closed. The attraction between the two elements may help to keep the parts of the core aligned when the coupler is closed. Additionally, the coupler may further comprise a second magnetic element slidable with the first part of the core and arranged to cooperate with a further corresponding magnetic element associated with the second part of the core to secure the core closed. The attraction between the two elements may further help to keep the parts of the core aligned when the coupler is closed. Additionally, the first magnetic element and second magnetic element may be disposed adjacent opposite edges of the first part of the core. This positioning may further help to keep the parts of the core aligned when the coupler is closed. Additionally, the coupler may further comprise a first protector to protect the first magnetic element during closing. This may reduce the risk of damage to the first magnetic element. Additionally, the first magnetic element may be recessed with respect to the protector. Additionally, the protector may cover the first magnetic element. Additionally, the protector may comprise a magnetic material such as steel. Additionally, the protector may comprise a steel plate. Additionally, the coupler may further comprise a second protector to protect the second magnetic element during closing, wherein the first protector and the second protector are disposed adjacent opposite edges of the core. This may reduce the risk of damage to the second magnetic element. Additionally, a surface of the first protector may be flush with the interface to allow an opposing part of the core to slide across the first protector during closing. This may help to reduce the risk of the core catching any part of the protector. Additionally, a surface of the second protector may be flush with the interface to allow an opposing part of the core to slide across the second protector during closing. This may help to reduce the risk of the core catching any part of the protector. Additionally, at least one edge of the interface may be bounded by a housing part. This may keep the components of the coupler, such as the core parts and the magnetic elements, in the correct positions with respect to each other. Additionally, the housing part may have a sliding surface configured to allow an opposing part of the core to slide across the sliding surface and an adjacent part of the core. This may enable the coupler to open and close smoothly without the risk of components catching other components. Additionally, the sliding surface may be flush with an interface surface of the adjacent part of the core. This may further help the coupler to open and close smoothly without the risk of components catching other components. Additionally, the sliding surface may comprise a surface of the protector. Additionally, the housing part may comprise a pivot coupling configured to pivotably couple the parts of the core. This may enable the coupler to open and close. Additionally, the pivot coupling may be configured to enable 360 degree rotation of the parts of the core about the pivot coupling relative to each other. This may enable the coupler to be fully opened, providing easy access to any internal components. Additionally, the housing part may comprise electrical connections for connecting a first of the windings to the HFAC power supply bus and a second of the windings to the electrical device. This may enable the inductive link to be provided between the bus and the device. Additionally, the parts of the core may be positioned substantially towards the centre of the housing part. This may provide maximum protection of the core. Additionally, a sliding motion of the parts of the core relative to one another may provide a wiping or cleaning effect of the parts of the core. This may help to keep the core free of foreign substances, thus ensuring that the coupler can close properly and the coupler can function efficiently in the desired manner. Additionally, the first magnetic element may comprise a first magnet, the first magnet being substantially oval-shaped. Additionally, the second magnetic element may comprise a second magnet, the second magnet being substantially oval-shaped. Additionally, the first magnetic element may comprise a first pair of magnets. Additionally, the second magnetic element may comprise a second pair of magnets. Brief Description of Drawings Embodiments of the disclosure will now be described, by way of example only, with reference to the accompanying drawings. Figure 1A shows a top view of a first portion of a coupler. Figure 1B shows a cross-sectional view of a first portion of a coupler. Figure 2A shows a top view of a second portion of a coupler. Figure 2B shows a cross-sectional view of a second portion of a coupler. Figure 2C shows a cross-sectional view of a second portion of a coupler. Figure 3A shows a top view of a coupler in an open position. Figure 3B shows a side view of a coupler in an open position. Figure 4A shows a side view of a coupler in a closed position. Figure 4B shows a cross-sectional view of a coupler in a closed position. Figure 4C shows a cross-sectional view of a coupler in a closed position. In the drawings like reference numerals are used to indicate like elements. Specific Description Figures 1A-B show a first portion 100 of a coupler. Specifically, Figure 1A shows a top view of the first portion 100 and Figure 1B shows a cross-sectional side view of the first portion 100. Figure 1A shows a line A-B transposed on top of the first portion 100 of the coupler. The line A-B bisects the first portion 100 of the coupler. Figure 1B shows the cross-sectional side view of the first portion 100 of the coupler along this line A-B. A coupler is a device configured to provide an inductive link between a power bus and a device to be powered, so that power taken from the bus may be used to drive the device. A coupler can be fixed to a bus in a way that closing the coupler completes a magnetic circuit (e.g., around a magnetic yoke) which provides an efficient inductive link between the bus and a winding carried by that yoke. The same action of closing the magnetic circuit may also mechanically fix the coupler to the bus. The first portion 100 of the coupler will now be described with reference to both Figures 1A and 1B. The first portion 100 of the coupler may comprise a first core part 101. The first core part 101 may be a first part of a two-part core, with the second part belonging to another portion of the coupler, as will be discussed with reference to Figures 2A-C. The first core part 101 may comprise a magnetic material such as ferrite or steel. The first core part 101 may be a solid core, or may comprise a series of laminated sheets. The first core part 101 may be a cube or a cuboid, and may have a substantially square or rectangular cross section. The first core part 101 may also comprise a pair of grooves 113 in an upper surface 102 of the first core part 101. The pair of grooves 113 may be substantially parallel to one another and may extend from a first side of the first core part 101 to a second, opposing side of the first core part 101. The pair of grooves 113 may have a substantially rectangular cross-section and so may each have a flat base. The upper surface 102 of the first core part 101 may be substantially level and flat, except for the pair of grooves 113. A first of the pair of grooves 113 may be positioned on one side of the centre of the first core part 101, and a second of the pair of grooves 113 may be positioned on an opposing side of the centre of the first core part 101, such that a cross-sectional top view of the first core part 101 is substantially symmetrical. The first portion 100 of the coupler may further comprise a housing 103. The housing 103 may comprise any suitable material and may house the first core part 101, along with other components that will be described later. The housing 103 may be substantially cylindrical, with a circular shape when viewed from above. The housing 103 may comprise an upper surface 104. The upper surface 104 may comprise a number of recesses and channels, as will be described, but apart from these recesses and channels, the upper surface 104 is substantially flat. The housing 103 may comprise a primary recess 114 within which the first core part 101 may be positioned. The primary recess 114 may define a volume that substantially matches the dimensions of the first core part 101, such that the upper surface 102 of the first core part 101 is level and flush with the upper surface 104 of the housing 103. The primary recess 114 may extend downwards from the upper surface 104 of the housing 103. The first side of the first core part 101 may therefore correspond to a first side of the primary recess 114 and the second side of the first core part 101 may correspond to a second side of the primary recess 114. The primary recess 114 may be positioned substantially towards the centre of the housing 103, such that the first core part 101 is also positioned substantially towards the centre of the housing 103. The housing 103 may also comprise a secondary recess extending downwards from the upper surface 104 of the housing 103. The secondary recess may be substantially oval-shaped, or may be substantially obround-shaped. It should be appreciated that any other shape is possible. The secondary recess may have a width profile that is constant along its entire depth, as shown in Figure 1B. Alternatively, the secondary recess may comprise an upper and a lower section, with the upper section being closer to the upper surface 104 of the housing 103 than the lower section. The lower section may represent the majority of the secondary recess and may be narrower than the upper section. In this way, the upper section and the lower section may have the same shape, but with different dimensions. The secondary recess may be positioned on a third side of the first core part 101. The first portion 100 of the coupler may further comprise a first magnetic element 105. The first magnetic element 105 may comprise a magnetic material and may be positioned within the secondary recess. The first magnetic element 105 may comprise a first magnet, which may be substantially oval-shaped, or may be obround-shaped. The shape of the first magnet may substantially match the shape of the secondary recess, although the width and length of the first magnet may be slightly smaller than those of the secondary recess. Alternatively, the first magnetic element 105 may comprise a first pair of magnets. The first pair of magnets may comprise two substantially identical magnets, each located at opposite ends of the secondary recess. For example, the first pair of magnets may comprise a pair of circular magnets. A height of the first magnetic element 105 may be smaller than a depth of the secondary recess. The first magnetic element 105 may therefore extend upwards from a base of the lower section of the secondary recess, but a top surface of the first magnetic element 105 is below the upper surface 104 of the housing 103. The first portion 100 of the coupler may further comprise a first protector 108. The first protector 108 may be positioned within the secondary recess directly above the first magnetic element 105. When viewed from above, the first protector 108 may have substantially the same shape as the secondary recess, so that it may wholly cover the volume defined by the secondary recess and in doing so cover the first magnetic element 105. The first protector 108 may sit directly on top of the first magnetic element 105 such that it is in contact with the first magnetic element 105. Alternatively, if the height of the first magnetic element 105 is smaller than the depth of the lower section of the secondary recess, the first magnetic element 105 may be recessed with respect to the first protector 108. The first protector 108 may comprise a magnetic material, such as steel. For example, the first protector 108 may comprise a steel plate, or a stainless steel plate. The first protector 108 may comprise a top surface that is substantially flat, and a side surface that protrudes downwards from an outer edge of the top surface and extends around a perimeter of the first protector 108. The side surface may therefore define a volume in which the first magnetic element 105 may be positioned. In this way, the first protector 108 may have a varying thickness. For example, the first protector 108 may be thicker at its edges than towards its centre, due to the side surface, such that a cross-sectional profile of the first protector 108 is of a substantially flat-bottomed U-shape. The thickness of the side surface may be chosen so that it substantially fills the gap that remains when the first magnetic element 105 is disposed within the secondary recess. Alternatively, the first protector 108 may comprise only a top surface and not a side surface. In such an embodiment, the first protector 108 may have a uniform thickness. Such an arrangement may be appropriate if the width profile of the first magnetic element 105 is substantially equal to the width profile of the secondary recess. The thickness of the first protector 108 may be chosen so that when the first protector 108 is positioned above the first magnetic element 105, the top surface of the first protector 108 is level and flush with the upper surface 104 of the housing 103 and the upper surface 102 of the first core part 101. Specifically, the side surface of the first protector 108 may protrude downwards to the base of the secondary recess, such that a height of the first protector 108 is substantially equal to the depth of the secondary recess. The housing 103 may also comprise a tertiary recess extending downwards from the upper surface 104 of the housing 103. The tertiary recess may be substantially oval-shaped, or may be substantially obround-shaped. It should be appreciated that any other shape is possible. Preferably, the shape of the tertiary recess matches the shape of the secondary recess. The tertiary recess may have a width profile that is constant along its entire depth, as shown in Figure 1B. Alternatively, the tertiary recess may comprise an upper and a lower section, with the upper section being closer to the upper surface 104 of the housing 103 than the lower section. The lower section may represent the majority of the tertiary recess and may be narrower than the upper section. In this way, the upper section and the lower section may have the same shape, but with different dimensions. The tertiary recess may be positioned on a fourth side of the first core part 101 opposite the third side, such that the secondary recess and the tertiary recess are on opposing sides of the first core part 101. For example, with reference to the line A-B, the secondary recess may be positioned closer to A along the line, whereas the tertiary recess may be positioned closer to B along the line. The first portion 100 of the coupler may further comprise a second magnetic element 106. The second magnetic element 106 may comprise a magnetic material and may be positioned within the tertiary recess. Due to their respective positions within the secondary and tertiary recesses, the first magnetic element 105 and the second magnetic element 106 may be disposed adjacent opposite edges of the first core part 101. The second magnetic element 106 may comprise a second magnet, which may be substantially oval-shaped, or may be obround-shaped. The shape of the second magnet may substantially match the shape of the tertiary recess, although the width and length of the second magnet may be slightly smaller than those of the tertiary recess. Alternatively, the second magnetic element 106 may comprise a second pair of magnets. The second pair of magnets may comprise two substantially identical magnets, each located at opposite ends of the tertiary recess. For example, the second pair of magnets may comprise a pair of circular magnets. A height of the second magnetic element 106 may be smaller than a depth of the tertiary recess. The second magnetic element 106 may therefore extend upwards from a base of the lower section of the tertiary recess, but a top surface of the second magnetic element 106 is below the upper surface 104 of the housing 103. The first portion 100 of the coupler may further comprise a second protector 109. The second protector 109 may be positioned within the tertiary recess directly above the second magnetic element 106. Due to their respective positions within the secondary and tertiary recesses, the first protector 108 and the second protector 109 may be disposed adjacent opposite edges of the first core part 101. When viewed from above, the second protector 109 may have substantially the same shape as the tertiary recess, so that it may wholly cover the volume defined by the tertiary recess and in doing so cover the second magnetic element 106. The second protector 109 may sit directly on top of the second magnetic element 106 such that it is in contact with the second magnetic element 106. Alternatively, if the height of the second magnetic element 106 is smaller than the depth of the lower section of the tertiary recess, the second magnetic element 106 may be recessed with respect to the second protector 109. The second protector 109 may comprise a magnetic material, such as steel. For example, the second protector 109 may comprise a steel plate, or a stainless steel plate. The second protector 109 may comprise a top surface that is substantially flat, and a side surface that protrudes downwards from an outer edge of the top surface and extends around a perimeter of the second protector 109. The side surface may therefore define a volume in which the second magnetic element 106 may be positioned. In this way, the second protector 109 may have a varying thickness. For example, the second protector 109 may be thicker at its edges than towards its centre, due to the side surface, such that a cross-sectional profile of the second protector 109 is of a substantially flat-bottomed U-shape. The thickness of the side surface may be chosen so that it substantially fills the gap that remains when the second magnetic element 106 is disposed within the tertiary recess. Alternatively, the second protector 109 may comprise only a top surface and not a side surface. In such an embodiment, the second protector 109 may have a uniform thickness. Such an arrangement may be appropriate if the width profile of the second magnetic element 106 is substantially equal to the width profile of the tertiary recess. The thickness of the second protector 109 may be chosen so that when the second protector 109 is positioned above the second magnetic element 106, the top surface of the second protector 109 is level and flush with the upper surface 104 of the housing 103 and the upper surface 102 of the first core part 101. Specifically, the side surface of the second protector 109 may protrude downwards to the base of the tertiary recess, such that a height of the second protector 109 is substantially equal to the depth of the tertiary recess. Collectively, the upper surface 104 of the housing 103, the upper surface 102 of the first core part 101, the top surface of the first protector 108 and the top surface of the second protector 109 may define a first sliding surface, along which a second portion of the coupler may slide – this will be described in greater detail with reference to Figures 2A-C, 3A-B and 4A-C. The housing 103 may further comprise a first pivot part 107 positioned on the upper surface 104 of the housing 103. The first pivot part 107 may be a part of a pivot coupling. Depending on the pivot coupling, the first pivot part 107 may be a protrusion extending upwards from the upper surface 104 of the housing 103, or may be a recess extending downwards from the upper surface 104 of the housing 103. The first pivot part 107 may be positioned towards an outer edge of the upper surface 104, such that it is closer to the outer edge than to the centre of the upper surface 104. The first pivot part 107 may be positioned away from the primary, secondary and tertiary recesses and away from any other components of the first portion 100 of the coupler. The housing 103 may further comprise a pair of winding recesses extending downwards from the upper surface 104 of the housing 103. The pair of winding recesses may comprise a first winding recess 115 positioned by the first side of the primary recess 114 and a second winding recess 116 positioned by the second side of the primary recess 114. A depth of the pair of winding recesses may be smaller than a depth of the primary recess 114, or may be substantially equal to the depth of the primary recess 114, or may be greater than a depth of the primary recess 114. The depth of the pair of winding recesses may be substantially equal to the depth of the pair of grooves 113 in the first core part 101. Each winding recess may comprise a flat base. Alternatively, the pair of winding recesses may both extend downwards through an entire depth of the housing 103, such that they define apertures extending through the first portion 100. In this way, the volume defined by the winding recesses may be accessed from both the top and the bottom of the first portion 100 of the coupler. This may be beneficial when the first portion 100 has been joined to a second portion (as will be described with reference to Figures 3A-B and 4A-C), as it will provide some access even when the coupler is joined. The first portion 100 of the coupler may further comprise a winding 110. The winding 110 may be positioned within the pair of grooves 113 of the first core part 101 and within the pair of winding recesses of the housing 103. Specifically, the winding 110 may be positioned on the bases of the pair of grooves 113 of the first core part 101 and on the bases of the pair of winding recesses. The winding 110 may be substantially rectangular-shaped, but with the centre cut out, such that the winding 110 defines a rectangular loop of material. A first side of the loop may extend along the length of a first of the pair of grooves 113 and a second side of the loop may extend along a length of the second of the pair of grooves 113, with the remaining two sides joining the first and second sides in the pair of winding recesses of the housing 104. The winding 110 may comprise a first winding and a second winding. The first winding may be positioned towards the first side of the first core part 101 (e.g. in the first winding recess 115) and the second winding may be positioned towards the second side of the first core part 101 (e.g. in the second winding recess 116). Alternatively, the first winding may be positioned towards the second side of the first core part 101 (e.g. in the second winding recess 116) and the second winding may be positioned towards the first side of the first core part 101 (e.g. in the first winding recess 115). The winding 110 may be substantially flat, with a thickness that is smaller than the depth of the pair of grooves 113 and the depth of the pair of winding recesses. The housing 103 may further comprise a first pair of channels 111 extending downwards from the upper surface 104 of the housing 103. The first pair of channels 111 may be substantially parallel to one another and may extend from the first winding recess 115 to an outer edge of the housing 103. The first pair of channels 111 may have a substantially U-shaped cross section and may have a depth that is smaller than a depth of the first winding recess 115. The housing 103 may also comprise a second pair of channels 112 extending downwards from the upper surface 104 of the housing 103. The second pair of channels 112 may be substantially parallel to one another and may extend from the second winding recess 116 to an outer edge of the housing 103. The second pair of channels 112 may have a substantially U-shaped cross section and may have a depth that is smaller than a depth of the second winding recess 116. The first pair of channels 111 may be substantially parallel to and directly aligned with the second pair of channels 112. The depth of the first pair of channels 111 may be substantially equal to the depth of the second pair of channels 112. Furthermore, the first pair of channels 111 and the second pair of channels 112 may be directly aligned with the pair of grooves 113 of the first core part 101. In this way, there may be a direct line of sight along a first of the first pair of channels 111, through the first winding recess 115, along a first of the pair of grooves 113, through the second winding recess 116 and along a first of the second pair of channels 112. Similarly, there may be a direct line of sight along a second of the first pair of channels 111, through the first winding recess 115, along a second of the pair of grooves 113, through the second winding recess 116 and along a second of the second pair of channels 112. The points at which the first pair of channels 111 meets the outer edge of the housing 103 may be radially opposite the points at which the second pair of channels 112 meets the outer edge of the housing 103. The housing 103 may further comprise electrical connections for connecting the winding 110 to suitable electrical components or devices. For example, the housing may comprise electrical connections for connecting the first winding to a high frequency alternating current (HFAC) power supply bus and for connecting the second winding to an electrical device to be powered. Connection to an HFAC supply may be preferable because it provides a safe alternative to traditional, dangerous low frequency AC voltage power distribution, providing a system whereby appliances may be connected to the HFAC power supply bus, taking the improved safety aspect one step further as the power/load circuit is inductively coupled to the HFAC power supply. High frequencies, typically in excess of 20kHz are used so that efficient inductive power transfer may take place. Installation may also be quicker and simpler and furthermore does not carry the same risks of electrocution or fires caused by arcing connectors in any condition, especially wet environments. The electrical connections may be positioned within the first pair of channels 111 and the second pair of channels 112 and may extend into the first winding recess 115 to connect with the first winding and into the second winding recess 116 to connect with the second winding. The first core part 101 may be configured to function as part of a core for a transformer. When an alternating current is passed through the first winding, a varying magnetic flux may be produced in the core, which then induces a varying electromotive force across the second winding. The first core part 101 helps to provide a low reluctance closed ferromagnetic path for the magnetic flux, which helps reduce any losses due to flux leakage. Furthermore, the first core part 101 may be configured to provide mechanical support to the winding 110. The housing 103 may be configured to hold the first core part 101 in place, as well as to hold other components of the coupler. The housing 103 therefore also serves the function of enabling all the components of the first portion 100 of the coupler to move as one, thus making it easier to align with another portion of the coupler. The housing 103 may also help to dissipate heat from the first core part 101, the temperature of which may become high during use of the coupler. The first magnetic element 105 may be configured to cooperate with a corresponding magnetic element associated with another portion of the coupler comprising another part of the core to secure the core closed. Specifically, the first magnetic element 105 may be attracted to the corresponding magnetic element and this attraction may be used to hold the coupler closed such that the parts of the core are aligned. The second magnetic element 106 may be configured to cooperate with a further corresponding magnetic element associated with the other portion of the coupler comprising the other part of the core to secure the core closed. Specifically, the second magnetic element 106 may be attracted to the further corresponding magnetic element and this attraction may be used to hold the coupler closed such that the parts of the core are aligned. The first protector 108 may be configured to cover the first magnetic element 105 and to protect the first magnetic element 105 during closing of the coupler. The first magnetic element 105 is important for holding the coupler together and so protecting the first magnetic element 105 from any damage is necessary. The second protector 109 may be configured to cover the second magnetic element 106 and to protect the second magnetic element 106 during closing of the coupler. The second magnetic element 106 is important for holding the coupler together and so protecting the second magnetic element 106 from any damage is necessary. The first pivot part 107 may be configured to interact with a pivot part of another portion of the coupler in order to create a pivot coupling. This pivot coupling may then enable the portions of the coupler to be pivotably slidable with respect to one another, thus allowing the coupler to be opened and closed. The winding 110 may be configured to enable inductive coupling through the coupler between a power supply and a device. For example, the winding 110 may be part of a transformer configured to enable inductive coupling between an HFAC power supply bus and an electrical device to be powered. The first winding may be a primary winding configured to receive an alternating current from the HFAC power supply bus and induce an alternating current in the second winding, which may then form part of a load circuit comprising the electrical device to be powered. The channels 111 and 112 may be configured to hold electrical connections for connecting the winding 110 to the HFAC power supply bus and to the electrical device. The grooves 113 may be configured to hold the winding 110 within the first core part 101, thus enabling the core to function in the desired manner. Figures 2A-C show a second portion 200 of a coupler. Specifically, Figure 2A shows a top view of the second portion 100. Figure 2B shows a cross-sectional side view of a first embodiment of the second portion 200, whereas Figure 2C shows a cross-sectional side view of a second embodiment of the second portion 200. Figure 2A shows a line X-Y transposed on top of the second portion 200 of the coupler. The line X-Y bisects the second portion 200 of the coupler. Figures 2B and 2C show the cross-sectional side view of the second portion 200 of the coupler along this line X-Y. The second portion 200 of the coupler will now be described with reference to Figures 2A, 2B and 2C. The second portion 200 of the coupler may comprise a second core part 201. The second core part 201 may be a second part of a two- part core, with the first part belonging to another portion of the coupler. For example, the first part of the two-part core may be the first core part 101, as has been discussed with reference to Figures 1A-B. The second core part 201 may comprise a magnetic material such as ferrite or steel. The second core part 201 may be a solid core, or may comprise a series of laminated sheets. The material of the second core part 201 matches the material of the first core part 101 of the first portion 100 of the coupler. The second core part 201 may be a cube or a cuboid, and may have a substantially square or rectangular cross section when viewed from above. The second core part 201 may have a cross-section that is substantially equal to the cross-section of the first core part 201. Specifically, a length of the second core part 201 is equal to a length of the first core part 101 and a width of the second core part 201 is equal to a width of the first core part 101. A height of the second core part 201 may be equal to a height of the first core part 101, or may be greater or smaller than the height of the first core part 101. The second portion 200 of the coupler may further comprise a housing 203. The housing 203 may comprise any suitable material and may house the second core part 201, along with other components that will be described later. The housing 203 may be substantially cylindrical, with a circular shape when viewed from above. The housing 203 may comprise an upper surface 204. The upper surface 204 may comprise a number of recesses and channels, as will be described, but apart from these recesses and channels, the upper surface 204 is substantially flat. The housing 203 may comprise a primary recess 214 within which the second core part 201 may be positioned. The primary recess 214 may define a volume that substantially matches the dimensions of the second core part 201, such that the upper surface 202 of the second core part 201 is level and flush with the upper surface 204 of the housing 203. The primary recess 214 may extend downwards from the upper surface 204 of the housing 203. A first side of the second core part 201 may therefore correspond to a first side of the primary recess 214 and a second side of the second core part 201 may correspond to a second side of the primary recess 214. The primary recess 214 may be positioned substantially towards the centre of the housing 203, such that the second core part 201 is also positioned substantially towards the centre of the housing 203. The housing 203 may also comprise a secondary recess extending downwards from the upper surface 204 of the housing 203. The secondary recess may be substantially oval-shaped, or may be substantially obround-shaped. It should be appreciated that any other shape is possible. The secondary recess may have a width profile that is constant along its entire depth, as shown in Figures 2B-C. Alternatively, the secondary recess may comprise an upper and a lower section, with the upper section being closer to the upper surface 204 of the housing 203 than the lower section. The lower section may represent the majority of the secondary recess and may be narrower than the upper section. In this way, the upper section and the lower section may have the same shape, but with different dimensions. The secondary recess may be positioned on a third side of the second core part 201. The second portion 200 of the coupler may further comprise a first magnetic element 205. The first magnetic element 205 may comprise a magnetic material and may be positioned within the secondary recess. The first magnetic element 205 of the second portion 200 of the coupler may correspond to the first magnetic element 105 of the first portion 100 of the coupler, as described with reference to Figures 1A-B. In this way, the first magnetic element 205 of the second portion 200 of the coupler may be considered a corresponding magnetic element with respect to the first magnetic element 105 of the first portion 100 of the coupler. The first magnetic element 205 may comprise a first magnet, which may be substantially oval-shaped, or may be obround-shaped. The shape of the first magnet may substantially match the shape of the secondary recess. The width and length of the first magnetic element 205 may be substantially equal to the width and length of the secondary recess, as shown in Figure 2B. Alternatively, the width and length of the first magnetic element 205 may be slightly smaller than those of the secondary recess, as shown in Figure 2C, in which it can be seen that there may be a gap surrounding the sides of the first magnetic element 205. Alternatively, the first magnetic element 205 may comprise a first pair of magnets. The first pair of magnets may comprise two substantially identical magnets, each located at opposite ends of the secondary recess. For example, the first pair of magnets may comprise a pair of circular magnets. A height of the first magnetic element 205 may be smaller than a depth of the secondary recess. The first magnetic element 205 may therefore extend upwards from a base of the lower section of the secondary recess, but a top surface of the first magnetic element 205 may be below the upper surface 204 of the housing 203, as shown in Figure 2C. Alternatively, as shown in the embodiment of Figure 2B, the height of the first magnetic element 205 may be equal to a depth of the secondary recess, such that a top surface of the first magnetic element 205 is level and flush with the upper surface 204 of the housing 203. The second portion 200 of the coupler may further comprise a first protector 208. The embodiment of Figure 2C shows such a protector, whereas the embodiment of Figure 2B does not. The first protector 208 may be positioned within the secondary recess directly above the second magnetic element 105. It should be appreciated that although Figure 2C shows the first protector 208 as being below the first magnetic element 205, this figure is upside down to aid understanding with regard to Figures 3A-B and 4A-C so the bottom of Figure 2C (and indeed Figure 2B) may be interpreted as representing the top of the second portion 200 of the coupler. When viewed from above, the first protector 208 may have substantially the same shape as the secondary recess, so that it may wholly cover the volume defined by the secondary recess and in doing so cover the first magnetic element 205. The first protector 208 may sit directly on top of the first magnetic element 205 such that it is in contact with the first magnetic element 205. Alternatively, if the height of the first magnetic element 205 is smaller than the depth of the lower section of the secondary recess, the first magnetic element 205 may be recessed with respect to the first protector 208. The first protector 208 may comprise a magnetic material, such as steel. For example, the first protector 208 may comprise a steel plate, or a stainless steel plate. The first protector 208 may comprise a top surface that is substantially flat, and a side surface that protrudes downwards from an outer edge of the top surface and extends around a perimeter of the first protector 208. The side surface may therefore define a volume in which the first magnetic element 205 may be positioned. In this way, the first protector 208 may have a varying thickness. For example, the first protector 208 may be thicker at its edges than towards its centre, due to the side surface, such that a cross-sectional profile of the first protector 208 is of a substantially flat-bottomed U-shape. The thickness of the side surface may be chosen so that it substantially fills the gap that remains when the first magnetic element 205 is disposed within the secondary recess. Alternatively, the first protector 208 may comprise only a top surface and not a side surface. In such an embodiment, the first protector 208 may have a uniform thickness. Such an arrangement may be appropriate if the width profile of the first magnetic element 205 is substantially equal to the width profile of the secondary recess. The thickness of the first protector 208 may be chosen so that when the first protector 208 is positioned above the first magnetic element 205, the top surface of the first protector 208 is level and flush with the upper surface 204 of the housing 203 and the upper surface 202 of the second core part 201. Specifically, the side surface of the first protector 208 may protrude downwards to the base of the secondary recess, such that a height of the first protector 208 is substantially equal to the depth of the secondary recess. The housing 203 may also comprise a tertiary recess extending downwards from the upper surface 204 of the housing 203. The tertiary recess may be substantially oval-shaped, or may be substantially obround-shaped. It should be appreciated that any other shape is possible. Preferably, the shape of the tertiary recess matches the shape of the secondary recess. The tertiary recess may have a width profile that is constant along its entire depth, as shown in Figures 2B-C. Alternatively, the tertiary recess may comprise an upper and a lower section, with the upper section being closer to the upper surface 204 of the housing 203 than the lower section. The lower section may represent the majority of the tertiary recess and may be narrower than the upper section. In this way, the upper section and the lower section may have the same shape, but with different dimensions. The tertiary recess may be positioned on a fourth side of the second core part 201 opposite the third side, such that the secondary recess and the tertiary recess are on opposing sides of the second core part 201. For example, with reference to the line X-Y, the secondary recess may be positioned closer to X along the line, whereas the tertiary recess may be positioned closer to Y along the line. The second portion 200 of the coupler may further comprise a second magnetic element 206. The second magnetic element 206 may comprise a magnetic material and may be positioned within the tertiary recess. Due to their respective positions within the secondary and tertiary recesses, the first magnetic element 205 and the second magnetic element 206 may be disposed adjacent opposite edges of the second core part 201. The second magnetic element 206 may comprise a second magnet, which may be substantially oval-shaped, or may be obround-shaped. The shape of the second magnet may substantially match the shape of the tertiary recess. The width and length of the second magnetic element 206 may be substantially equal to the width and length of the tertiary recess, as shown in Figure 2B. Alternatively, the width and length of the second magnetic element 206 may be slightly smaller than those of the tertiary recess, as shown in Figure 2C, in which it can be seen that there may be a gap surrounding the sides of the second magnetic element 206. Alternatively, the second magnetic element 206 may comprise a second pair of magnets. The second pair of magnets may comprise two substantially identical magnets, each located at opposite ends of the tertiary recess. For example, the second pair of magnets may comprise a pair of circular magnets. A height of the second magnetic element 206 may be smaller than a depth of the tertiary recess. The second magnetic element 206 may therefore extend upwards from a base of the lower section of the tertiary recess, but a top surface of the second magnetic element 206 may be below the upper surface 204 of the housing 203, as shown in Figure 2C. Alternatively, as shown in the embodiment of Figure 2B, the height of the second magnetic element 206 may be equal to a depth of the tertiary recess, such that a top surface of the second magnetic element 206 is level and flush with the upper surface 204 of the housing 203. The second portion 200 of the coupler may further comprise a second protector 209. The second protector 209 may be positioned within the tertiary recess directly above the second magnetic element 206. Due to their respective positions within the secondary and tertiary recesses, the first protector 208 and the second protector 209 may be disposed adjacent opposite edges of the second core part 201. When viewed from above, the second protector 209 may have substantially the same shape as the tertiary recess, so that it may wholly cover the volume defined by the tertiary recess and in doing so cover the second magnetic element 206. The second protector 209 may sit directly on top of the second magnetic element 206 such that it is in contact with the second magnetic element 206. Alternatively, if the height of the second magnetic element 206 is smaller than the depth of the lower section of the tertiary recess, the second magnetic element 206 may be recessed with respect to the second protector 209. The second protector 209 may comprise a magnetic material, such as steel. For example, the second protector 209 may comprise a steel plate, or a stainless steel plate. The second protector 209 may comprise a top surface that is substantially flat, and a side surface that protrudes downwards from an outer edge of the top surface and extends around a perimeter of the second protector 209. The side surface may therefore define a volume in which the second magnetic element 206 may be positioned. In this way, the second protector 209 may have a varying thickness. For example, the second protector 209 may be thicker at its edges than towards its centre, due to the side surface, such that a cross-sectional profile of the second protector 209 is of a substantially flat-bottomed U-shape. The thickness of the side surface may be chosen so that it substantially fills the gap that remains when the second magnetic element 206 is disposed within the tertiary recess. Alternatively, the second protector 209 may comprise only a top surface and not a side surface. In such an embodiment, the second protector 209 may have a uniform thickness. Such an arrangement may be appropriate if the width profile of the second magnetic element 206 is substantially equal to the width profile of the secondary recess. The thickness of the second protector 209 may be chosen so that when the second protector 209 is positioned above the second magnetic element 206, the top surface of the second protector 209 is level and flush with the upper surface 204 of the housing 203 and the upper surface 202 of the second core part 201. Specifically, the side surface of the second protector 209 may protrude downwards to the base of the secondary recess, such that a height of the second protector 209 is substantially equal to the depth of the tertiary recess. Collectively, the upper surface 204 of the housing 203, the upper surface 202 of the first core part 201, the top surface of the first protector 208 and the top surface of the second protector 209 may define a second sliding surface, along which a first portion of the coupler may slide (i.e. the first portion 100 from Figures 1A-B) – this will be described in greater detail with reference to Figures 3A-B and 4A-C. It should be appreciated that in the embodiment of Figure 2B, the upper surface 204 of the housing 203, the upper surface 202 of the first core part 201, the top surface of the first magnetic element 205 and the top surface of the second magnetic element 206 may collectively define the second sliding surface, since this embodiment does not comprise protectors. The housing 203 may further comprise a second pivot part 207 positioned on the upper surface 204 of the housing 203. The second pivot part 207 may be a part of a pivot coupling. Depending on the pivot coupling, the first pivot part 207 may be a protrusion extending upwards from the upper surface 204 of the housing 203, or may be a recess extending downwards from the upper surface 204 of the housing 203. The first pivot part 107 of the first portion 100 of the coupler must complement the second pivot part 207 of the second portion 200 of the coupler. For example, if the first pivot part 107 is a recess, the second pivot part 207 is a protrusion, and if the first pivot part 107 is a protrusion, the second pivot part 207 is a recess. The second pivot part 207 may be positioned towards an outer edge of the upper surface 204, such that it is closer to the outer edge than to the centre of the upper surface 204. The second pivot part 207 may be positioned away from the primary, secondary and tertiary recesses and away from any other components of the second portion 200 of the coupler. The position of the second pivot part 207 with respect to the housing 203 directly corresponds to the position of the first pivot part 107 with respect to the housing 103. The second core part 201 may be configured to function as part of a core for a transformer. When an alternating current is passed through the first winding in the first portion 100 of the coupler, a varying magnetic flux may be produced in the core, which then induces a varying electromotive force across the second winding. The second core part 201 helps to provide a low reluctance closed ferromagnetic path for the magnetic flux, which helps reduce any losses due to flux leakage. The housing 203 may be configured to hold the second core part 201 in place, as well as to hold other components of the coupler. The housing 203 therefore also serves the function of enabling all the components of the second portion 200 of the coupler to move as one, thus making it easier to align with another portion of the coupler (e.g. the first portion 100). The housing 203 may also help to dissipate heat from the first core part 201, since the temperature of the core may become high during use of the coupler. The first magnetic element 205 may be configured to cooperate with a corresponding magnetic element associated with another portion of the coupler comprising another part of the core to secure the core closed. For example, the first magnetic element 205 may be configured to cooperate with the first magnetic element 105 of the first portion 100 of the coupler. Specifically, the first magnetic element 205 may be attracted to the corresponding magnetic element and this attraction may be used to hold the coupler closed such that the parts of the core are aligned. The second magnetic element 206 may be configured to cooperate with a further corresponding magnetic element associated with the other portion of the coupler comprising the other part of the core to secure the core closed. For example, the second magnetic element 206 may be configured to cooperate with the second magnetic element 106 of the first portion 100 of the coupler. Specifically, the second magnetic element 206 may be attracted to the further corresponding magnetic element and this attraction may be used to hold the coupler closed such that the parts of the core are aligned. The first protector 208 may be configured to cover the first magnetic element 205 and to protect the first magnetic element 205 during closing of the coupler. The first magnetic element 205 is important for holding the coupler together and so protecting the first magnetic element 205 from any damage is necessary. The second protector 209 may be configured to cover the second magnetic element 206 and to protect the second magnetic element 206 during closing of the coupler. The second magnetic element 206 is important for holding the coupler together and so protecting the second magnetic element 206 from any damage is necessary. The second pivot part 207 may be configured to interact with a pivot part of another portion of the coupler (e.g. the first pivot part 107 of the first portion 100 of the coupler) in order to create a pivot coupling. This pivot coupling may then enable the portions of the coupler to be pivotably slidable with respect to one another, thus allowing the coupler to be opened and closed. Figures 3A-B show a coupler 300 in an open position. Specifically, Figure 3A shows a top view of the coupler 300 in an open position, whereas Figure 3B shows a side view of the coupler 300 in an open position. The coupler 300 comprises a first portion 100 and a second portion 200. The first portion 100 may be the first portion 100 from Figures 1A-B and so comprises the components and features already described with reference to these figures. The second portion 200 may be the second portion 200 from Figures 2A-C and so comprises the components and features already described with reference to these figures. The coupler 300 is formed by joining the first portion 100 and the second portion 200 by a pivot coupling. The two portions are arranged such that their upper surfaces face one another. Specifically, with respect to a central longitudinal axis of the coupler 300, the upper surface 104 of the housing 103 of the first portion 100 may face upwards along the axis, whereas the upper surface 204 of the housing 203 of the second portion 200 may face downwards along the axis. The housing 103 and the housing 203 can collectively provide a housing for the coupler as a whole. Similarly, the first core part 101 and the second core part 201 can collectively provide a two- part core of the coupler 300. The first pivot part 107 and the second pivot part 207 can collectively provide the pivot coupling of the coupler 300. The first portion 100 of the coupler 300 and the second portion 200 of the coupler 300 may be pivotable to slide relative to each other about the pivot coupling. Specifically, the pivot coupling is configured to enable rotation, such as 360° rotation, of the first portion 100 and the second portion 200 about the pivot coupling relative to each other. Such rotation causes the sliding surfaces of the first and second portions to move parallel to each other – e.g., each to slide along the opposing sliding surface. In this way, the first magnetic element 105 may be slidable with the first core part 101, since both components are held within the housing 103. The second magnetic element 106 may also be slidable with the first core part 101 and indeed with the first magnetic element 105 for the same reason. The open position may be defined as any position in which the first portion 100 and the second portion 200 are not aligned vertically with respect to the longitudinal axis. Specifically, the open position may be any position in which the first core part 101 is not aligned with the second core part 201, in which the first magnetic element 105 is not aligned with the first magnetic element 205, and in which the second magnetic element 106 is not aligned with the second magnetic element 206. When in the open position, the coupler 300 cannot be used to couple an HFAC power supply bus to an electrical device to be powered, since core alignment is necessary for such a procedure. In the open position, components of the coupler 300 may be accessed where necessary. For example, opening the coupler 300 may comprise opening the core in order to admit the HFAC power supply bus. A closed position may be defined as the position in which the first portion 100 and the second portion 200 are aligned vertically with respect to the longitudinal axis. Specifically, the closed position may be the position in which the first core part 101 is aligned with the second core part 201, in which the first magnetic element 105 is aligned with the first magnetic element 205, and in which the second magnetic element 106 is aligned with the second magnetic element 206. Further details of the closed position will be described with reference to Figures 4A-C. Since the pivot coupling is positioned towards the outer edge of the coupler 300, the coupler 300 may be opened so as to expose the majority of the upper surface 104 of the housing 103 and the upper surface 204 of the housing 203, and to fully expose the upper surface 102 of the first core part 101 and the upper surface 202 of the second core part 201. Moving the first portion 100 and second portion 200 with respect to one another may involve pivotably sliding the portions about the pivot coupling. Closing the coupler 300 may involve pivotably sliding the first portion 100 and the second portion 200 with respect to one another such that the two portions are aligned. This sliding involves swinging one of the portions in a circular manner with respect to the other portion and results in the upper surfaces of each portion sliding against each other. Specifically, the first sliding surface may slide against the second sliding surface. By forming the coupler 300 in the manner described above, an interface may be created between the first portion 100 and the second portion 200. The two-part core is therefore joinable at this interface and may provide a magnetic yoke for inductive coupling of the windings carried by the core with the HFAC power supply bus. This interface may grow or shrink as the first portion 100 and the second portion 200 are moved with respect to each other, since the overlapping area between the two portions grows or shrinks with this movement. At any point, however, at least one edge of the interface is bounded by a housing part (e.g. a part of housing 103 and/or housing 203). The parts of the core may therefore be pivotable to slide relative to each other along the interface. Closing the core may complete the magnetic yoke whereas opening the core may expose the components of the coupler 300 and enable components such as the HFAC power supply bus to be admitted. As described earlier, the first sliding surface may comprise the upper surface 102 of the first core part 101, the upper surface 104 of the housing 103, the top surface of the first protector 108 and the top surface of the second protector 109. In the embodiment of Figure 4B, the second sliding surface may comprise the upper surface 202 of the second core part 201, the upper surface 204 of the housing 203, the top surface of the first magnetic element 205 and the top surface of the second magnetic element 206. In the embodiment of Figure 4C, the second sliding surface may comprise the upper surface 202 of the second core part 201, the upper surface 204 of the housing 203, the top surface of the first protector 208 and the top surface of the second protector 209. In each embodiment, the first sliding surface is flush with the interface to allow the second core part 201 to slide across the first sliding surface, and the second sliding surface is flush with the interface to allow the first core part 101 to slide across the second sliding surface. More specifically, the arrangement of the coupler 300 enables a part of the core to slide across a sliding surface and an adjacent part of the core (e.g. the first core part 101 may slide across the second sliding surface, which includes the adjacent second core part 201). The sliding motion of the portions of the coupler 300 with respect to one another may provide a wiping or cleaning effect. More specifically, the sliding motion of the parts of the core relative to one another may provide such an effect. If either part of the core, or indeed any part of the first or second sliding surfaces is exposed for a period of time, dirt or other foreign substances may build up on these exposed surfaces (i.e. upper surface 102 and upper surface 202). This may affect the connection between the two parts of the core, which may have an adverse effect on the operation of the coupler 300. A further benefit of this pivotably sliding motion is that it avoids slamming of the magnetic elements. In a conventional hinged coupler, the attraction between the respective magnetic elements can cause the coupler to slam shut with significant force, which can cause damage to the magnetic elements and indeed to the core. The arrangement described keeps the vertical separation between the two portions of the coupler 300 constant, meaning that no slamming is possible. Since the two sliding surfaces are in contact, the sliding motion of the surfaces with respect to one another may wipe away any dirt or foreign surfaces. This helps to keep the sliding surfaces clean and helps to ensure effective operation of the coupler 300. Figures 4A-C show the coupler 300 in a closed position. Specifically, Figure 4A shows a side view of the coupler 300. Figure 4B shows a cross-sectional side view of a first embodiment of the coupler 300, whereas Figure 4C shows a cross-sectional side view of a second embodiment of the coupler 300. The first embodiment of the coupler 300, as shown in Figure 4B, comprises the first portion 100 and the second portion 200 from Figure 2B. The second embodiment of the coupler 300, as shown in Figure 4C, comprises the first portion 100 and the second portion 200 from Figure 2C. As described above, the closed position may be defined as the position in which the first portion 100 and the second portion 200 are aligned vertically with respect to the longitudinal axis. Specifically, the closed position may be the position in which the first core part 101 is aligned with the second core part 201, in which the first magnetic element 105 is aligned with the first magnetic element 205, and in which the second magnetic element 106 is aligned with the second magnetic element 206. In this position, the two parts of the core are joined to form the two-part core, meaning that the coupler can function in the intended manner. The first magnetic element 105 of the first portion 100 attracts the corresponding first magnetic element 205 of the second portion 200, and the second magnet element 106 of the first portion 100 attracts the corresponding second magnetic element 206 of the second portion 200. This attraction holds the two portions together and keeps the two parts of the core aligned. As the coupler 300 is brought close to this closed position, the coupler 300 may snap closed as the strength of the attraction increases. A force must be applied to overcome this attraction and reopen the coupler 300. A method of assembling and using the coupler 300 will now be described. The method starts with the two portions of the coupler 300 being separated. In this first step, the first portion 100 is not yet connected to an HFAC power supply bus or to an electrical device. The next step involves admitting the HFAC power supply bus to the first portion 100 of the coupler 300. The HFAC power supply bus may be connected to the electrical connections in the pair of channels 111 (or in the channels 112, if the winding 110 is arranged such that the first winding is in the first winding recess 115). Simultaneously, the first portion 100 may be connected to the electrical device to be powered. The electrical device may be connected to the electrical connections in the pair of channels 112 (or in the channels 111, if the winding 110 is arranged such that the first winding is in the first winding recess 115). Despite these connections, no inductive link is created, since the coupler 300 is not assembled and in the closed position. The next step involves joining the first portion 100 and the second portion 200 to form the coupler. The first portion 100 and the second portion 200 may be joined by coupling the first pivot part 107 to the second pivot part 207 to form the pivot coupling. At this stage, the coupler 300 may be in the open position. As described, this means that the respective components of the first portion 100 and the second portion 200 are not aligned, meaning that the components of the coupler 300 may be accessed and/or admitted. It should be appreciated that the step of joining the first portion 100 and the second portion 200 may take place prior to admitting the HFAC power supply bus and the electrical device to be powered. As has been described, these components can be admitted when the coupler 300 is in the open position. The next step involves closing the coupler 300. More specifically, this comprises pivotably sliding the two portions of the coupler 300 with respect to each other towards the closed position, in which the two core parts are aligned. As described earlier, this closing motion may simultaneously clean the core. As the coupler 300 nears the closed position, the attraction between the respective first magnetic elements of the first and second portions and the attraction between the respective second magnetic elements of the first and second portions may cause the coupler 300 to snap shut. At this point, the first core part 101 is aligned with the second core part 201 and the core may therefore function as part of a transformer, thus allowing the electrical device to be powered by the HFAC power supply bus. In this way, the mechanical link (i.e. the magnetic yoke) between the two coupler portions and the inductive link between HFAC power supply bus and the electrical device to be powered are created together at the same time. A further step may involve powering the electrical device by the HFAC power supply bus through the inductive link provided by the coupler 300 in the closed position. Powering of the electrical device can then be paused by opening the coupler 300, which involves sliding the two portions with respect to one another so as to move the coupler 300 from the closed position to an open position. Any feature of any one of the examples disclosed herein may be combined with any selected features of any of the other examples described herein. For example, features of methods may be implemented in suitably configured hardware, and the configuration of the specific hardware described herein may be employed in methods implemented using other hardware. It will be appreciated from the discussion above that the embodiments shown in the Figures are merely exemplary, and include features which may be generalised, removed or replaced as described herein and as set out in the claims. With reference to the drawings in general, it will be appreciated that schematic functional block diagrams are used to indicate functionality of systems and apparatus described herein. It will be appreciated however that the functionality need not be divided in this way, and should not be taken to imply any particular structure of hardware other than that described and claimed below. The function of one or more of the elements shown in the drawings may be further subdivided, and/or distributed throughout apparatus of the disclosure. In some embodiments the function of one or more elements shown in the drawings may be integrated into a single functional unit. The above embodiments are to be understood as illustrative examples. Further embodiments are envisaged. It is to be understood that any feature described in relation to any one embodiment may be used alone, or in combination with other features described, and may also be used in combination with one or more features of any other of the embodiments, or any combination of any other of the embodiments. Furthermore, equivalents and modifications not described above may also be employed without departing from the scope of the invention, which is defined in the accompanying ^claims.

Claims

Claims 1. A coupler for coupling an HFAC power supply bus to an electrical device to be powered, the coupler comprising: a two-part core joinable at an interface to provide a magnetic yoke for inductive coupling of windings carried by the core with an HFAC power supply bus, wherein the parts of the core are pivotable to slide relative to each other along the interface, to open the core to admit the HFAC power supply bus and to close the core to complete the magnetic yoke.

2. The coupler of claim 1 wherein at least one edge of the interface is bounded by a housing part, the housing part comprising a pivot coupling configured to pivotably couple the parts of the core so that the parts of the core are pivotable to slide relative to each other along the interface

3. The coupler of claim 1 or 2 comprising a first magnetic element slidable with a first part of the core and arranged to cooperate with a corresponding magnetic element associated with a second part of the core to secure the core closed.

4. The coupler of claim 3, further comprising a second magnetic element slidable with the first part of the core and arranged to cooperate with a further corresponding magnetic element associated with the second part of the core to secure the core closed. , for example wherein the first magnetic element and second magnetic element are disposed adjacent opposite edges of the first part of the core.

5. The coupler of any of claims 2 to 4, further comprising a first protector to protect the first magnetic element during closing.

6. The coupler of claim 5, wherein the first magnetic element is recessed with respect to the protector.

7. The coupler of claim 6, wherein the protector covers the first magnetic element.

8. The coupler of claims 6 or 7, wherein the protector comprises a magnetic material such as steel.

9. The coupler of claim 8, wherein the protector comprises a steel plate.

10. The coupler of any of claims 4 to 9 as dependent upon claim 5, further comprising a second protector to protect the second magnetic element during closing, wherein the first protector and the second protector are disposed adjacent opposite edges of the core.

11. The coupler of any of claims 5 to 10 as dependent on claim 5, wherein a surface of the first protector is flush with the interface to allow an opposing part of the core to slide across the first protector during closing.

12. The coupler of claim 11 as dependent on claim 10, wherein a surface of the second protector is flush with the interface to allow an opposing part of the core to slide across the second protector during closing.

13. The coupler of any preceding claim, wherein at least one edge of the interface is bounded by a housing part.

14. The coupler of claim 13, wherein the housing part has a sliding surface configured to allow an opposing part of the core to slide across the sliding surface and an adjacent part of the core.

15. The coupler of claim 14, wherein the sliding surface is flush with an interface surface of the adjacent part of the core.

16. The coupler of claim 15 as dependent on claim 5, wherein the sliding surface comprises a surface of the protector.

17. The coupler of any of claims 13 to 16, wherein the housing part comprises a pivot coupling configured to pivotably couple the parts of the core.

18. The coupler of claim 17, wherein the pivot coupling is configured to enable 360 degree rotation of the parts of the core about the pivot coupling relative to each other.

19. The coupler of any of claims 13 to 18, wherein the housing part comprises electrical connections for connecting a first of the windings to the HFAC power supply bus and a second of the windings to the electrical device.

20. The coupler of any of claims 13 to 19, wherein the parts of the core are positioned substantially towards the centre of the housing part.

21. The coupler of any preceding claim, wherein a sliding motion of the parts of the core relative to one another provides a wiping or cleaning effect of the parts of the core.

22. The coupler of any of claims 2 to 21, wherein the first magnetic element comprises a first magnet, the first magnet being substantially oval-shaped.

23. The coupler of any of claims 3 to 22 as dependent on claim 3, wherein the second magnetic element comprises a second magnet, the second magnet being substantially oval-shaped.

24. The coupler of any of claims 2 to 21, wherein the first magnetic element comprises a first pair of magnets.

25. The coupler of any of claims 3 to 22 as dependent on claim 3, wherein the second magnetic element comprises a second pair of magnets.