Wireless power transfer system

Abstract

A charging unit for wireless power transfer is described herein. The charging unit includes at least one coil for inductive power transfer, a sensor coil array having a sensing field for sensing the presence of at least one foreign object, and a controller. The controller is configured to move the sensor coil array and / or the sensing field so that the sensing field can scan a sensing area, and is configured to detect the presence of at least one foreign object in the sensing area based on the sensing array output. The sensor coil array and / or the sensing field is movable so that the sensing field can be: a) positioned in the sensing area so that the sensing field does not overlap with the at least one foreign object, and b) positioned in the sensing area so that the sensing field overlaps with the at least one foreign object.

Description

Technical Field

[0001] The present invention relates to a wireless power transfer system (charging or real-time power system) and a device for detecting a foreign object thereon. Background Art

[0002] FIG1 shows a prior art wireless power transfer charging system 10 for charging an electric vehicle 11. The charging system includes a central charging unit 12 having a power source 9 and a controller 8 for controlling the supply of power to the electric vehicle 11, and also includes a wireless charging unit 13 that inductively transfers power 15 to the electric vehicle 11. The central charging unit 12 is electrically coupled 16 to the wireless charging unit 13. The wireless charging unit 13 may take the form of a wireless charging pad 40 that includes one or more inductive coils 14 for transferring power to the electric vehicle 11.

[0003] In operation, the central charging unit 12 induces alternating current into the induction coil 14, which produces a varying electromagnetic field / flux in and around the induction coil 14. The electric vehicle has a receiver 17 that receives the power inductively transmitted from the wireless charging unit 13. The receiver 17 is electrically coupled to a rechargeable battery 18. If the receiver 17 of the electric vehicle 11 is near the wireless charging pad 13, the varying electromagnetic field / flux induces alternating current in the induction coil of the receiver 17, resulting in a wireless transmission of power 15 to the electric vehicle 11.

[0004] If a foreign object is also located in the vicinity of the wireless charging pad 13, the changing electromagnetic field will induce eddy currents in the foreign object. If the resistance of the foreign object is low, then the foreign object will begin to heat up, and continued exposure to the electromagnetic flux increases the risk of the foreign object becoming a heating and / or fire hazard. Summary of the invention

[0005] It is an object of the present invention to provide object sensing in wireless power transfer.

[0006] The present embodiment provides a foreign object detection system for the wireless power transfer charging system 10 so that remedial action can be taken if a foreign object is on or sufficiently close to the wireless charging pad 13. For example, the wireless charging pad 13 can be powered off and / or shut down to prevent the foreign object from becoming a safety hazard.

[0007] In one aspect, the invention may be said to include a charging unit for wireless power transfer, the charging unit comprising: at least one coil for inductive power transfer, an array of sensor coils having a sensing field for sensing the presence of at least one foreign object, and

[0008] a controller configured to: move the sensor coil array and / or the sensing field so that the sensing field can scan a sensing area, and detect the presence of at least one foreign object in the sensing area based on the sensing array output, wherein the sensor coil array and / or the sensing field is movable so that the sensing field can:

[0009] a) positioned in the sensing region such that the sensing field does not overlap with the at least one foreign object, and b) positioned in the sensing region such that the sensing field overlaps with the at least one foreign object.

[0010] Optionally, the charging unit is used to wirelessly charge the electric vehicle by inductive power transfer.

[0011] Optionally, the charging unit further comprises an arm, wherein the sensor coil array is arranged on the arm, and the controller is capable of controlling the arm to move so as to position the sensing field in the sensing area.

[0012] Optionally, the arm is configured as a rotatable arm and the controller is capable of rotating the arm to position the sensing field.

[0013] Optionally, the arm is a slidable arm and the controller is capable of sliding the arm to position the sensing area.

[0014] Optionally, the charging unit has an operating area, and the sensing area overlaps the operating area.

[0015] Optionally, the sensor coil array and / or the sensing field is smaller than the operating area.

[0016] Optionally, the charging unit further comprises one or more additional sensor arrays for sensing the presence of the at least one foreign object.

[0017] Optionally, each additional sensor array is arranged on a respective additional arm.

[0018] Optionally, the charging unit comprises electromagnetic shielding material for shielding the sensor coil array from electromagnetic interference.

[0019] Optionally, the charging unit is used to wirelessly charge one or more of the following:

[0020] Electrical system

[0021] ·Battery

[0022] Scooter

[0023] Electric bicycle

[0024] ·robot

[0025] Other electronic devices

[0026] In another aspect, the present invention may be said to include a charging unit for wirelessly charging an electric vehicle via inductive power transfer, the charging unit comprising: at least one coil for inductive power transfer, a sensor coil array having a sensing field for sensing the presence of a foreign object, and a controller configured to: move the sensor coil array and / or the sensing field so that the sensing field can scan a sensing area and detect the presence of a foreign object in the sensing area based on the sensing array output, wherein the sensor coil array and / or the sensing field are movable so that the sensing field can: a) be positioned in the sensing area so that the sensing field does not overlap with the foreign object, and b) be positioned in the sensing area so that the sensing field overlaps with the foreign object.

[0027] In another aspect, the invention may be said to include a sensing unit of a charging unit for wireless power transfer, the charging unit comprising: a sensor coil array having a sensing field for sensing the presence of at least one foreign object, and a controller or in communication with a controller, the controller being configured to: move the sensor coil array and / or the sensing field so that the sensing field can scan a sensing area, and detect the presence of at least one foreign object in the sensing area based on the sensing array output, wherein the sensor coil array and / or the sensing field is movable so that the sensing field can:

[0028] a) positioned in the sensing region such that the sensing field does not overlap with the at least one foreign object, and positioned in the sensing region such that the sensing field overlaps with the at least one foreign object.

[0029] Optionally, the charging unit is used to wirelessly charge the electric vehicle by inductive power transfer.

[0030] Optionally, the charging unit further comprises one or more sensor arrays for sensing the presence of the at least one foreign object.

[0031] Optionally, the charging unit is used to wirelessly charge one or more of the following:

[0032] Electrical system

[0033] ·Battery

[0034] Scooter

[0035] Electric bicycle

[0036] ·robot

[0037] Other electronic devices

[0038] In another aspect, the invention may be said to comprise a wireless power transfer system comprising a charging unit and / or a sensing unit according to any of the preceding aspects of the invention.

[0039] On the other hand, the present invention can be said to include a power system for wireless power transmission for charging and / or real-time power supply of a system or device, comprising: at least one coil for inductive power transmission, a sensor coil array having a sensing field for sensing the presence of at least one foreign object, and a controller, the controller being configured to: move the sensor coil array and / or the sensing field so that the sensing field can scan a sensing area; and detect the presence of the at least one foreign object in the sensing area based on the sensing array output, wherein the sensor coil array and / or the sensing field is movable so that the sensing field can: a) be positioned in the sensing area so that the sensing field does not overlap with the at least one foreign object, and b) be positioned in the sensing area so that the sensing field overlaps with the at least one foreign object.

[0040] The term "comprising" as used in the present specification and claims means "consisting at least in part of..." When interpreting each expression containing the term "comprising" in the present specification and claims, features other than the term or those preceded by the term may also exist. Related terms such as "comprise" and "comprises" are to be interpreted in the same manner.

[0041] Numerical ranges disclosed herein (e.g., 1 to 10) also include reference to all rational numbers within that range (e.g., 1, 1.1, 2, 3, 3.9, 4, 5, 6, 6.5, 7, 8, 9, and 10) as well as any range of rational numbers within that range (e.g., 2 to 8, 1.5 to 5.5, and 3.1 to 4.7).

[0042] The present invention may also be broadly described as including the parts, elements and features referred to or indicated in the specification of the present application, either individually or collectively, and any or all combinations of any two or more of said parts, elements or features, and where specific integers are referred to herein, these specific integers have known equivalents in the art to which the present invention relates, and these known equivalents are deemed to be incorporated herein as if individually set forth. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Preferred embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0044] FIG. 1 is an overview of a prior art wireless power transfer charging system.

[0045] Figure 2is a general overview of a wireless power transfer charging system according to the described embodiments.

[0046] Figure 3 is a block diagram overview of a wireless charging unit according to the embodiment.

[0047] Figure 4 is a block diagram overview of a sensing unit according to the embodiment.

[0048] Figure 5 is a plan view of an embodiment of a sensing unit.

[0049] Figure 6 is a line diagram showing an example of how one embodiment of a sensing unit senses and detects a foreign object.

[0050] Figure 7 is a plan view of another embodiment of a sensing unit.

[0051] Figure 8 is a line diagram showing an example of how another embodiment of a sensing unit senses and detects a foreign object.

[0052] Fig. 9 is a plan view of another embodiment of a sensing unit.

[0053] Fig.10 is a plan view of another embodiment of a sensing unit.

[0054] FIG. 11 is a plan view of a foreign object detection system of the prior art.

[0055] FIG. 12 is a line graph showing why it is difficult to detect a foreign object using a foreign object detection system of the related art. DETAILED DESCRIPTION

[0056] Overview of the Described Embodiments

[0057] Figure 2 A wireless power transfer charging system 10 for charging an electric vehicle 11 is shown, the wireless power transfer charging system being configured to enable detection of foreign objects in an operating area of ​​a wireless charging unit 13 .

[0058] The wireless power transfer charging system 10 comprises a central charging unit 12 for controlling the supply of power to an electric vehicle 11, and further comprises a wireless charging unit 13 for inductively transferring power 15 to the electric vehicle 11. The charging unit 13 is electrically coupled 16 to the central charging unit 12. The wireless charging unit 13 may take the form of a wireless charging pad comprising one or more inductive coils 14 for transferring power 15 to the electric vehicles 17, 18.

[0059] In operation, the central charging unit 12 induces alternating current into the induction coil 14, which generates a varying electromagnetic field / flux in and around the induction coil 14. The electric vehicle 11 has a receiver 17 that receives the power inductively transmitted 15 from the wireless charging unit 13. The receiver 17 is electrically coupled to a rechargeable battery 18. If the receiver 17 of the electric vehicle 11 is in the vicinity of the wireless charging pad 13, the varying electromagnetic field / flux induces alternating current in the induction coil of the receiver 17, resulting in a wireless transmission of power 15 to the electric vehicle 13. A foreign object sensing unit 20 is provided to detect any foreign objects in the operating area of ​​the charging unit 13.

[0060] In summary, the described embodiments provide a sensing unit 20, a wireless power transfer charging unit 13 having a sensing unit 20, and / or a wireless power transfer charging system 10 having a charging unit 13, whereby the sensing unit 20 can sense and detect dangerous foreign objects (on or near the charging unit) that may be present as previously stated.

[0061] The embodiments disclosed herein are described in terms of sensing and detecting a single foreign object as opposed to two or more foreign objects. This is to provide a simplified explanation of how foreign objects are detected and sensed by the embodiments described herein. Those skilled in the art will appreciate that the described embodiments are capable of sensing and detecting a single foreign object, and are also capable of sensing and detecting two or more foreign objects. This is because the techniques used to sense and detect a single foreign object can also be used to detect two or more foreign objects.

[0062] The embodiments of the wireless power transmission charging system 10, the sensing unit 20, and the wireless power charging unit 13 described herein are all described in the context of wirelessly charging an electric vehicle 11. However, those skilled in the art will appreciate that the described embodiments may also be applicable to systems that power an electrical system in real time or that charge a battery. Furthermore, the described embodiments may be applicable to charging scooters, electric bicycles, robots, and other similar electronic devices.

[0063] Various embodiments of a wireless charging unit 13 that can sense foreign objects are described. In general, see Figure 3 , an embodiment provides a sensing coil array 34 that can scan a sensing area 31 and a controller 32 that can detect a foreign object 33 in the sensing area 31. Upon detection, appropriate action can be taken to prevent the hazard, such as shutting down the wireless charging unit 13. Typically, the sensing coil array will be in the housing of the charging unit 13.

[0064] The controller 32 is capable of detecting foreign objects 33. In addition, the controller 32 can be used to operate any actuators for moving the sensing array 34, and the controller 32 can be used to power the sensing coil array 34 (including the sensing coils themselves). The controller 32 can refer to one or more controllers that can be placed anywhere in the wireless charging unit 13.

[0065] refer to Figure 4 , various general features of the wireless charging unit 13 and the sensing unit 20 are shown in general diagrammatic form. The various geometric areas are shown for illustration purposes only and may not correspond to actual geometric areas of the charging unit according to the described embodiments.

[0066] The charging unit 13 takes the form of a charging pad 40 having a housing that covers an area. In this case, the pad 40 and housing are circular, but they can take other shapes, such as square, rectangular or other shapes. The charging pad 40 includes a wireless power transmission charging coil ("power coil") 14 - in this case one, although the actual number will depend on the charging unit 13. The coil 14 has an operating area 41, which is the area where the electromagnetic field of these power coils 14 can operate to provide power transmission 15 to the electric vehicle 11. Foreign objects 42 that fall within the operating area 41 are at risk of creating an overheating hazard because they receive power for the vehicle 11. Therefore, embodiments herein are intended to detect such foreign objects 42 within the operating area 41. The geometry of the operating area 41 may completely overlap or not completely overlap with the geometry of the charging pad area 40. Depending on the range of the wireless power transmission 15, the operating area 41 may overlap, partially overlap, be larger or smaller than the charging pad area 40. Typically, the operating area 41 and the charging pad area 40 will be closely aligned. The term "overlapping" with respect to the operating area 41 and the charging pad 40 will mean that the operating area 41 at least partially coincides with the charging pad 40 (regardless of whether it is larger or smaller), and may completely coincide with the charging pad 40 (i.e., the same size and substantially completely aligned), or it may even be larger than the charging pad 40. The term "covering" means that the area is at least aligned with or even larger than another area.

[0067] The charging unit 13 has a sensing unit (generally depicted as 43). The sensing unit 43 may be integrated with the charging unit 13 or a separate device, and may be retrofittable or incorporated at the time of manufacture. The sensing unit 43 includes a sensor arm 44 and a sensor coil array 45 arranged on the sensor arm 44. The sensor coil array 45 is shown as a single array of multiple sensing coils, such as 45a, but this is merely exemplary, and other geometries and numbers of sensing coils are possible. The sensor coil array 45 has an electromagnetic sensing field ("sensing field") 46, which is a geometric area over which the sensor coil array 45 can operate / sense foreign objects 42 to a suitable measurement level.

[0068] The sensor coil array 45 (and therefore the sensing field 46) is smaller than the operating area 41, the advantageous reasons of which will be explained later. As a result, the sensing field 46 does not cover / overlap and cannot sense foreign objects 42 over the entire operating area (when stationary). Therefore, the sensing unit 46 has a controller 32 and an actuator 47, which under the control of the controller 32 can operate the sensor coil array 45 so that the sensing field 46 can scan a larger area. This can be by moving the sensor arm 44 and / or the sensor coil array 45 so that the sensing field 46 scans a larger area. The area scanned by the sensing field 46 is the sensing area 48. The sensing area 48 is the area where the foreign object sensing unit 20 can sense and detect foreign objects 42. Preferably, the sensing area 48 is at least the same size as the operating area 41 of the charging unit 13 and completely covers the operating area. The sensing area area 48 can be larger than the operating area area 41. However, it may not be absolutely necessary for the sensing area 48 to be the same size as or larger than the operating area 41, and a sensing area 48 that covers only a portion of the operating area 41 may still be useful. Even if the sensing area 48 does not completely overlap with the operating area 41, for example it overlaps but does not completely cover it, some benefit may still be obtained. However, any operating area 41 that is not scanned is in danger of hiding foreign objects 42 that will not be detected and may pose a heating hazard. The term "overlap" with respect to the operating area 41 and the sensing area 48 will mean that the sensing area 48 at least partially overlaps with the operating area 41 (whether it is larger or smaller), and may completely overlap with the operating area 41 (i.e., the same size and substantially completely aligned) or it may even be larger than the operating area 41. The term "covering" means that the area in question is at least aligned with or even larger than another area. As Figure 4As shown, sensing area 48 is slightly larger than operating area 41. Sensing field 46 may not conform to the geometry of sensor arm 44. Typically, it may be larger than sensor arm 44, although this is not required, and it may have other relationships to sensor arm 44, such as conforming to sensor arm 44, partially or completely overlapping sensor arm 44, and / or being smaller than sensor arm 44.

[0069] like Figure 4 As shown, the arm 44 can be moved by the actuator 47 so that the sensing coil array 45 rotates to scan (sweep out) the sensing area 48. In this case, the arm 44 is rotated to sweep out a circular sensing area 48. It can be seen that the actual area swept by the arm 44 (the arm movement area 49) is smaller than the sensing area 48 because the sensing field 46 is slightly longer than the arm 44, so it sweeps a larger radius. Having a rotating sensor arm 44 is only one option for moving the sensing field 46, and other options are possible, thereby creating different shape sensing areas 48, some of which will be described below.

[0070] The geometry of the sensing field 46 and sensing region 48 is arranged relative to the operating region 41 such that there is at least one position of the sensing field 46 such that the sensing field 46 does not overlap with a foreign object 42 in the operating region 41 (which means that it does not partially or completely coincide with it), and there is at least one position of the sensing region such that it does not overlap with a foreign object 42 in the operating region 41 (which means that it at least partially or completely coincides with it). In practice, there are typically multiple positions of both, but the sensing field 46, sensing region 48 can and can move in a variety of different geometries and movements as long as there is at least one position of each.

[0071] The shielding helps to attenuate the electromagnetic field emitted from the power coil 14, so as to mitigate electromagnetic interference with the signals induced in the sense coils 45a of the sense array 45. The arm of this embodiment can incorporate more shielding material because the sense rod 44 occupies less area relative to the sensing area 48.

[0072] It should be understood that Figure 4 The boundaries of the areas shown involving electromagnetic fields may not be the actual shapes of these areas. These shapes are shown for exemplary purposes only. It should also be understood that the boundaries of the areas shown will not actually be "hard" boundaries, that is, the electromagnetic fields depicted will not necessarily become zero immediately outside the boundaries. Instead, the electromagnetic fields decay as a function of the distance from the source of the field. The boundaries of the depicted areas are merely indicative and show where the effective fields can be considered to have ended. Those skilled in the art will understand this and the boundaries should not be viewed as limiting in such a way that they limit the scope of the invention in a manner contrary to the concepts described herein.

[0073] The embodiments described herein have the following advantages over prior art sensing arrays.

[0074] The sensor coil array 45 does not need to be the same size as the operating area 41 to effectively detect foreign objects 42 in the operating area. Instead, a smaller sensor coil array 45 can be used. A small footprint of the sensor coil array 45 can be used. This saves on the cost of the coils and the accompanying control and sensing electronics.

[0075] The coils of the prior art sensing array are preferably shielded so that the field of the wireless power transmission coil 14 does not interfere with the sensing coil 45. However, if the coil array of the prior art is of considerable size, there is a large shielding area, which will prevent or attenuate the power transferred to the vehicle 11. In contrast, the smaller sensor coil arrays 45 of the embodiments described herein require a smaller shielding area, so they do not shield all or most of the power coils 14, and therefore do not attenuate the power transfer to a large extent. Because the sensor coil array 45 requires a smaller shielding area, a higher level (e.g., thickness) of shielding around the sensor coil array 45 can be provided without hindering the operation of the wireless power transmission coil 14. The additional shielding reduces electromagnetic interference from the wireless power transmission coil 14, which improves the quality of the signal sensed by the sensor coil array 45. This improves the accuracy and / or precision of the sensor coil array 15 measurements. In addition, the additional shielding thickness allows the controller 32 to be placed closer to the sensor coil array 45. Placing the controller 32 physically closer to the sensor coil array 45 also improves the accuracy and / or precision of the sensor coil array 45 measurements.

[0076] When using a sensor coil array to detect a foreign object 42, having a reference helps distinguish whether the foreign object 42 is present or not. For example, as shown in FIG11, with a prior art sensor coil array 15 covering most or all of the operating area, it is possible that the foreign object 42 is always sensed to some extent. Therefore, it is difficult to determine the difference from when the object 42 is present to when it is not present, see, for example, FIG12. In contrast, the present embodiment has a situation where the size of the sensing field 46 is such that the object 42 is only sensed sometimes and not other times, so the two readings can distinguish whether the object 42 is there or not.

[0077] Specific exemplary embodiments will now be described. These are not limiting and are provided by way of example only. A person skilled in the art may envision various other embodiments that still satisfy aspects of the present invention.

[0078] Specific embodiments according to the present invention will now be discussed.

[0079] 1. First Embodiment

[0080] Now refer to Figure 5 and 6 The first embodiment is discussed.

[0081] form Figure 2 The charging unit 13 which is part of the system may be Figure 5 and Figure 6 As shown. The various features of this embodiment will be renumbered relative to the previous figures, but they still relate to the same aspects specified by the context. The charging unit 13 of this embodiment includes a circular pad 50, which includes a housing and at least one wireless power transfer coil 57. The charging unit 13 has a rotatable sensor arm ("rotatable arm") 54 that is arranged above the pad 50 on a rotatable actuator (such as a motor). Preferably, the rotatable arm is in the charging unit housing, although this is not required. The rotatable actuator is controlled to rotate via a controller (such as Figure 3 32) to rotate, the controller is arranged in the charging unit 13 or arranged elsewhere in the system. The sensor coil array 55 is arranged on the rotatable arm 54. The size of the arm is suitable for carrying the sensor coil array 55. The sensor coil 55 can be any suitable coil used in the art. The rotatable arm 54 and / or the sensor coil 55 can be shielded to reduce interference from the charging coil 14.

[0082] The following areas are also shown:

[0083] A circular charging pad housing 50 .

[0084] A circular operating area 51 is the area over which the wireless power transfer coil 14 can transfer power. This is typically a similar area to the charging pad 50, ie they overlap.

[0085] • A rotatable arm 54 with a sensor coil 55 covering an elongated rectangular area.

[0086] • The sensing field 53, which is the area where the sensor coils 55 can sense the object 52 when the rotatable arm 54 / sensor coil array 55 is in a particular position.

[0087] The circular sensing area 58 is the area that the sensing field 53 is scanned or swept through by the rotatable movement of the arm 54 .

[0088] The area covered by the sensor coil array 55 and the rotatable arm 54 and the sensing field 53 is a small portion of the entire operating area 51, which is advantageous for the reasons described above. In particular, the sensing field 53 and the sensing area geometry 58 are arranged relative to the operating area 51 so that there is at least one position of the sensing field 53 such that it does not overlap with a foreign object 52 in the operating area (e.g., see position A, position C, and position D), and at least one position of the sensing field 53 such that it overlaps with a foreign object 52 in the operating area (see position B). In practice, there are many such positions for each. There is a vertical gap between the rotatable arm 54 and the charging unit pad 50 so that when the arm 54 rotates, it will pass over any foreign object 52 on the pad 50 or otherwise pass in the operating area 51.

[0089] In use, the rotatable arm 54 is rotated by the actuator under the control of the controller 32, so that the sensor coil array 55 scans / sweeps out the circular arm movement area 59, and the sensing field 53 scans / sweeps out the sensing area 58, thereby allowing the sensor coil array 55 to sense any foreign objects 52 located in the sensing area 58 / operating area 51. Four positions of the rotatable arm 54 are shown (positions A, B, C and D), but it should be understood that the arm 54 will rotate through a continuous range of different positions. It can be seen that as the arm 54 rotates, for most of the positions, the sensing field 53 does not cover the foreign object 52, but for a small portion of the scan (for a smaller range of positions), the arm 54 covers (and therefore the sensing field 53 covers) the foreign object 52.

[0090] When the rotating arm 54 / sensor coil array 55 is positioned so that the sensing field 53 does not overlap with any foreign object 52 (e.g., does not cover or is too far away to sense), the sensor coil array 55 will not sense the object 52. See, for example, positions A and C. The controller 32 receives a substantially zero signal 60 from the sensor coil array (see Figure 6 ) or an output of a signal indicating the absence of an object. Once the sensor coil array 55 is in one of the positions (e.g., position B) where the sensing field 53 overlaps (e.g., covers or is close to sensing) with the foreign object 52, the controller 32 receives the output as a positive signal 61a, b (see Figure 6 ), the controller detects the foreign object 52 from the positive signals 61a, b. The controller 32 can use the relative output from when the sensing field 53 does not sense or overlaps the object 52 to when it overlaps / senses the object 52 to help distinguish between these two events.

[0091] For example, at position A, the sensing rod 54 is oriented in a "north-south" direction, and the foreign object 52 does not overlap with (and is too far from) the sensing field 53. The foreign object 52 is too far from the sensing field 53 to induce an electrical signal into any of the sensing coils 55 located along the arm 54. Since no electrical signal is induced in any of the sensing coils 55, the controller 32 receives a ("low") zero reading 60 from the sensor coil array 55. The rotatable arm 54 begins to rotate clockwise toward position B. At position B, the arm 54 is oriented in a "northeast-southwest" direction. At this position, the sensor coil array 55 overlaps with the foreign object 52. Since an electrical signal is induced in at least one of the sensing coils 55, the controller 32 receives a ("high") non-zero reading 61. The arm 54 continues to rotate clockwise toward position C. At position C, the sensor coil array 55 is oriented in a "west-east" direction. At this position, the foreign object 52 is too far from the sensor coil array 55 to induce an electrical signal into any of the sensing coils 55 located along the rotatable arm 54. Since no electrical signal is induced in any of the sensing coils 55, the controller 32 receives a ("low") zero reading 60 from the sensor coil array 55. The arm 54 continues to rotate clockwise toward position D. At position D, the sensing rod 54 is oriented in a "northwest-southeast" direction. At this position, the foreign object 52 is too far from the sensor coil array 55 / sensing field 53 to induce an electrical signal into any of the sensing coils 55 located along the rotatable rod 54. Since no electrical signal is induced in any of the sensing coils 55, the controller receives a ("low") zero reading 60 from the sensor coil array. The arm 54 continues to rotate clockwise toward position A and can continue to rotate clockwise.

[0092] By rotating the sensing rod 54 from position A to position D and position A again, the controller 32 receives a ("low") zero reading 60 and a ("high") non-zero reading 61. The controller is able to reference the ("high") non-zero reading 61 against the ("low") zero 60 reading to correctly determine that a foreign object 52 is present within the sensing area 58. The controller 32 then de-energizes the inductive coil 57 of the charging pad to prevent inductive heating of the foreign object 52. The foreign object 52 is then no longer an inductive heating hazard.

[0093] Once detection occurs, the controller 32 may communicate with the central charging unit 12 to take appropriate action, such as shutting down power transfer.

[0094] Those skilled in the art will appreciate that, instead of continuously moving the rod 54 in a continuous clockwise direction, the rod 54 may rotate in other ways. For example, the rotatable rod 54 may move in alternating "stop" and "start" movements. In another example, the rotatable rod 54 may rotate in a counterclockwise direction. In another example, the rotatable rod 54 may move alternately between a clockwise direction and a counterclockwise direction.

[0095] The disclosed embodiments suggest sensing and detecting different voltage signals (i.e., non-zero readings when a foreign object is present, and zero readings when a foreign object is not present) to determine whether a foreign object 52 is present in the sensing region 53. Those skilled in the art will appreciate that the controller 32 may be configured to alternatively measure different parameters to determine whether a foreign object 52 is present in the sensing region 53. That is, instead of using relative voltage levels, the controller may alternatively measure, for example, frequency, phase shift, or some other parameter.

[0096] 2. Second Embodiment

[0097] Now refer to Figure 7 and Figure 8 The second embodiment is discussed.

[0098] form Figure 2 The charging unit 13 which is part of the system may be Figure 7 and Figure 8 As shown. The various features of this embodiment will be renumbered relative to the previous figures, but they still relate to the same aspects specified by the context. The charging unit 13 of this embodiment includes a rectangular pad 70, which includes a housing and at least one power coil 77 (three coils in this case). The charging unit 13 has a slidable sensor arm ("slidable arm") 74, which is arranged above the pad 70 on a sliding actuator (e.g., a linear motor). Preferably, the slidable arm is in the charging unit housing, although this is not required. The actuator is controlled to slide the arm 74 by a controller 32, which is arranged in the charging unit 13 or elsewhere in the system. A sensor coil array 75 is arranged on the slidable arm 74. The arm 74 is rectangular and spans a width slightly less than the width of the sensing area 78. These sensing coils 75 are connected to the control electronics. The size of the arm 74 is suitable for carrying the sensor coil array 75. The sensor coil 75 can be any suitable coil used in the art. The slidable arm 74 and / or the sensor coil 75 may be shielded to reduce interference from the charging coil 77 .

[0099] The following areas are also shown:

[0100] A rectangular charging pad 70 housing.

[0101] An operating area 71, which is the area over which the wireless power transfer coil can transfer power. This is typically of similar area to the charging pad 70. This may actually be a quasi-elliptical, or some other shape that reflects the total electromagnetic field of the power coil 77. Regardless, the operating area 71 will most likely be of similar size and cover or extend beyond the rectangular pad area 70. That is, preferably the sensing area 78 coincides with the operating area 71. However, even if there is no complete overlap, some useful gain may be obtained.

[0102] • A slidable arm 74 with a sensor coil 75 covering an elongated rectangular area.

[0103] • The sensor field 73, which is the area where the sensor coils 77 can sense the object 72 when the rotatable arm 74 / sensor coil array 75 is in a particular position.

[0104] The generally rectangular sensing area 78 is the area that the sensing field 73 scans or sweeps through by the sliding movement of the arm 74 .

[0105] The area covered by the sensor coil array 75 and the slidable arm 74 and the sensing field 73 is a small portion of the entire operating area 71, which is advantageous for the reasons discussed above. Specifically, the sensing field 73 and the sensing area geometry 78 are arranged relative to the operating area 71 so that there is at least one position of the sensing area 73 such that it does not overlap with a foreign object 72 in the operating area 71 (see positions A and C), and at least one position of the sensing field 73 such that it overlaps with a foreign object 72 in the operating area 71 (see position B). In practice, there are many such positions for each. There is a gap between the slidable arm 74 and the charging unit pad 70 so that when the arm 74 moves, it will pass over any foreign object 72 on the pad 70 or otherwise pass in the operating area 71.

[0106] In use, the arm 74 is manipulated by an actuator that can move the rod across the sensing area, such as position A through position B to position C. The actuator can be any suitable mechanism, such as an electromagnetic track. The actuator is controlled by the controller 32 in the charging unit, in the controller unit 32, or elsewhere in the system. The slidable rod 74 is moved laterally by the actuator under the control of the controller 32, so that the sensor coil array 75 scans / sweeps through the rectangular movement area 79 and the sensing field 73 scans / sweeps out the quasi-rectangular sensing area 78, thereby allowing the sensor coil array 55 to sense any foreign objects 72 located in the sensing area 78 / operating area 71. The three positions of the slidable arm 74 are shown as A, B, C, but it should be understood that the arm 74 will move through a continuous range of different positions. It can be seen that as the arm 74 moves, for most positions, the sensing field 73 does not cover the foreign object 72, but for a small portion of the scan (for a smaller range of positions), the arm 74 covers (and therefore the sensing field 73 covers) the foreign object 72.

[0107] The arm 74 moves laterally from one end of the sensing area 78 to the opposite end, allowing the area and sensing field 73 to scan the sensing area 78 to sense any foreign objects 72 located in the operating area 71. When the arm 74 / sensor coil array 75 is positioned so that the sensor field 73 does not overlap with the foreign object 72 (e.g., does not cover or is too far away to be sensed), the sensor coil array 75 will not sense the object 72. See, for example, positions A and C. The controller 32 receives a substantially zero signal 80 from the sensor coil array 75 (see Figure 8 ) or an output indicating the absence of an object. Once the sensor coil array 75 is in one of the positions (e.g., position B) where the sensing field 73 overlaps (e.g., covers or is close to sensing) with the foreign object 72, the controller 32 receives an output from the sensor coil array 75 as a positive signal 81, from which the controller 32 detects the foreign object 72. The controller 32 can use the relative output from when the sensing field 73 does not sense or overlaps the object 72 to when it overlaps / senses the object 72 to help distinguish between these two events.

[0108] For example, see Figure 7 and Figure 8, at position A, the arm 74 is at the edge of the sensing area 78, and the foreign object 72 is too far from the arm 74 to induce an electrical signal into any of the sensing coils 75 located along the arm 74. Since no electrical signal is induced in any of the sensing coils 75, the controller 32 receives a ("low") zero reading 80 from the arm. The arm 74 begins to move further to the right toward position B. At position B, the sensing rod 74 is located in the middle of the sensing area 78. At this position, the sensing rod 74 overlaps the foreign object 72, and the foreign object 72 is close enough to induce an electrical signal into at least one of the sensing coils 75 located along the arm 74. Since an electrical signal is induced in at least one of the sensing coils 75, the controller 32 receives a ("high") 81 non-zero reading. The arm 74 continues to move further to the right toward position C. In position C, the arm 74 is at the edge of the sensing area 78, and similar to position A, the foreign object 72 is too far from the arm 74 / sensing field 73, and therefore the controller 32 receives a ("low") 80 zero reading from the arm 74. Starting from position C, the direction of travel of the sensing rod 74 can be reversed, so that the sensing rod 74 begins to return to position A.

[0109] By moving the sensing rod 74 from position A to position C, the controller 32 receives a ("low") 80 zero reading and a ("high") 81 non-zero reading. The controller is able to reference the ("high") non-zero reading 81 against the ("low") zero reading 80 to correctly determine that a foreign object 72 is present within the sensing area 78. The controller 32 then de-energizes the inductive coil 77 of the charging pad to prevent inductive heating of the foreign object 72. The foreign object 72 is then no longer an inductive heating hazard.

[0110] Once detection occurs, the controller 32 can communicate with the system controller to take appropriate action, such as shutting down power transmission. Those skilled in the art will appreciate that, as an alternative to continuously moving the rod 74 in a continuous motion, the rod 74 can rotate in other ways. For example, the slidable rod 74 can move in alternating "stop" and "start" movements.

[0111] The disclosed embodiments suggest sensing and detecting different voltage signals (i.e., non-zero readings when a foreign object is present, and zero readings when a foreign object is not present) to determine whether a foreign object 72 is present in the sensing region 73. Those skilled in the art will appreciate that the controller 32 may be configured to alternatively measure different parameters to determine whether a foreign object 72 is present in the sensing region 73. That is, instead of using relative voltage levels, the controller may alternatively measure, for example, frequency, phase shift, or some other parameter.

[0112] 3. Changes

[0113] It should be understood that for the above-described embodiments, there may be many variations. For example, a single coil array is not required for the sensor coil array - there may be two, three or even more coil arrays, each array comprising one or more coil columns. In addition, each coil array may be arranged on its own arm - that is, some embodiments may have multiple sensing arms, each with its own coil array. Each sensing arm may move independently or together. In addition, the number of coils may be any suitable number. The consideration for the number of coils is of course sensitivity, and it is also a compromise between this consideration and the minimum size of the optimized sensor coil array (and therefore the arm) so that the cost can be maintained at a desired level, i.e., shielding can be maintained at a desired level, and the array may also always be placed at a position where it does not detect a foreign object and at another position where it does not detect a foreign object, so that a reference between two readings can improve detection.

[0114] Reference Fig. 9 , in a slidable arm 94 arrangement where the operating area 91 and the sensing area 98 are rectangular, typically the largest dimension of the sensor coil array 95 will produce a sensing field 93 having an area slightly less than half the area of ​​the sensing area 98, so that at least non-sensing and sensing locations of foreign objects can exist. In practice, it is desirable to have a sensor coil array 95 that produces a sensing field 93 that is much smaller than this. For example, the area of ​​the sensing field 93 may be less than 50% of the area of ​​the sensing area 98, or less than 40% of the area of ​​the sensing area 98, or less than 30% of the area of ​​the sensing area 98, or less than 25% of the area of ​​the sensing area 98, or less than 10% of the area of ​​the sensing area 98.

[0115] refer to Fig.10 , in a rotating arm arrangement 104 where the operating area 101 and the sensing area are circular, the sensor coil array 104 can theoretically be a significant portion of the entire circle to produce a sensing field 103, which is a significant portion of the entire circle with a small area where the sensing field 103 does not appear. This means that when rotation of the sensor coil array 105 occurs, there are still small areas in the sensing area 108 where no sensing occurs. However, in practice, it is more desirable to have a sensor coil array 105 that produces a sensing field 103 that is much smaller than this, more similar to what is described in the above embodiments.

[0116] The above embodiments relate to charging units. Wireless power transmission can also be used for real-time powering of systems and / or devices without or in addition to charging. The above embodiments can also be used with such systems.

[0117] 4. Shielding

[0118] As described above, shielding helps to attenuate the electromagnetic flux emitted from the sensing coils 14, 57, 77, thereby mitigating electromagnetic interference with the signals induced in the sensing coils of the sensing array 45, 55, 75. The sensing rods 44, 54, 74 according to the disclosed embodiments can incorporate more shielding material than the sensing array because the sensing rods 44, 54, 74 occupy a smaller area relative to the scanning area 48, 58, 78.

[0119] 5. Advantages

[0120] The disclosed embodiments may have one or more of the following advantages:

[0121] The sensing rods 44, 54, 74 are small relative to the size of the sensing area 48, 58, 78 that they need to scan. The sensing rods 44, 54, 74 are movable to scan the entire sensing area 48, 58, 78. The combination of the size of the rods 44, 54, 74 (relative to the size of the sensing area 48, 58, 78) and the means for moving the sensing rods 44, 54, 74 ensures that the wireless charging pad 40, 50, 70 is able to detect the presence of a foreign object 42, 52, 72 regardless of the size of the foreign object 42, 52, 72, the location of the foreign object 42, 52, 72 within the sensing area 48, 58, 78, or whether the foreign object 42, 52, 72 is stationary.

[0122] The small area of ​​the sensing rod 44, 54, 74 limits the amount of coil material and / or limits the number of sensing coils 45, 55, 75 that can be placed. Therefore, fewer supporting electronic components are required, resulting in simpler electronic circuits to manufacture and repair. Therefore, the cost of manufacturing and maintenance is cheaper.

[0123] The sensing rod 44, 54, 74 may have more shielding than is possible with a sensing array that covers a majority of the sensing area 48, 58, 78 of the wireless charging pad 40, 50, 70. The additional shielding that the sensing rod 44, 54, 74 may have means that the sensing coils 45, 55, 75 get less interference from the electromagnetic flux generated by the induction coils 14, 57, 77, while still ensuring that there is a sufficient rate of adequate wireless power transfer from the wireless charging pad 40, 50, 70 to the electric vehicle 11. Because the sensor coil array 45, 55, 75 requires a smaller shielding area, a higher level (e.g., thickness) of shielding around the sensor coil array 45, 55, 75 may be provided without hindering the operation of the wireless power transfer coils 14, 57, 77. The additional shielding reduces electromagnetic interference from the wireless power transfer coils 14, 57, 77, which improves the quality of the signal sensed by the sensor coil array 45, 55, 75. This improves the accuracy and / or precision of the measurements of the sensor coil array 45, 55, 75. Furthermore, the additional shielding thickness allows the controller 32 to be placed closer to the sensor coil array 45, 55, 75. Placing the controller 32 physically closer to the sensor coil array 45, 55, 75 also improves the accuracy and / or precision of the sensor coil array 45, 55, 75 measurements.

[0124] As shown in Figures 11 and 12, prior art arrangements typically include an array of sensing coils (referred to herein as a "sensing array") located below a charging surface (referred to herein as a "sensing area") of a wireless charging mat. The sensing coil array typically spans the entirety (or at least a large portion) of the charging mat area. The large size of the sensing array relative to the size of the wireless charging mat is problematic for several reasons:

[0125] ·First, the prior art arrangement using sensor coils to sense foreign objects can only detect foreign objects if the sensed measurement indicating the presence of the foreign object ("high" and / or "non-zero") can be referenced to a weaker or essentially non-existent ("low" and / or "zero") measurement indicating the absence of the foreign object. Prior to operation, the prior art is calibrated so that the system can distinguish between "high" and "low" measurements and / or distinguish between "non-zero" and "zero" measurements. If a stationary foreign object is located on the pad during start-up, the prior art arrangement will not be able to detect the foreign object. This is because the sensing array is too large so that it always senses the presence of a foreign object; and because there are always no "low" and / or "zero" measurements, the "high" and / or "non-zero" measurements are "misinterpreted" as uncertain measurements. Fig. 9 and Fig.10 In the example shown, the foreign object is positioned so that a portion of the sensing array always "overlaps" the foreign object.

[0126] Second, the wireless charging mat covers a relatively large surface area that needs to be scanned for foreign objects. Prior art arrangements require a large number of sensing coils so that the entire charging mat can be scanned for foreign objects. This means that a large amount of coil material is required. Furthermore, in order to detect small foreign objects (which may be at least as small as a hairpin or paper clip, for example), the sensing coils need to be placed very close together to achieve high-resolution sensing. This arrangement of the sensing coils exacerbates the problem of the large amount of coil material required to manufacture the wireless charging mat.

[0127] · Third, the sensing array has a shielding material to attenuate the electromagnetic flux emitted from the sensing coils so as to mitigate electromagnetic interference with the signals induced in the sensing coils of the sensing array. The shielding material should still be sufficiently magnetically "porous" so that the electromagnetic flux emitted from these sensing coils can still pass through so that there is still sufficient wireless transmission power. Returning to the example with reference to FIG. 11 , the size of the sensing array is large relative to the top surface of the sensing array, which limits the upper limit of how much shielding material can be applied to the sensing array. Excessive shielding will limit the rate of wireless power transfer from the wireless charging pad to the electric vehicle.

Claims

1. A unit for wireless power transmission charging, comprising: at least one coil for inductive power transfer, a sensor coil array having a sensing field for sensing the presence of at least one foreign object; an arm on which the sensor coil array is arranged, wherein the arm comprises an electromagnetic shielding material configured to shield the sensor coil array from an electromagnetic field emanating from the at least one coil, and A controller configured to: moving the arm to position the sensing field in a sensing area and moving the sensor coil array and / or the sensing field so that the sensing field scans the sensing area, and detecting the presence of the at least one foreign object in the sensing region based on outputs from the sensor coil array, Wherein, the controller is configured to move the sensor coil array and / or the sensing field such that the sensing field: a) being positioned in the sensing region such that the sensing field does not overlap with the at least one foreign object, and b) being positioned in the sensing region such that the sensing field overlaps the at least one foreign object. 2 . The unit of claim 1 , wherein the arm is a rotatable arm and the controller is configured to rotate the arm to position the sensing field.

3. The unit of claim 1, wherein the arm is configured as a slidable arm and the controller is configured to slide the arm to position the sensing field.

4. The unit of any one of claims 1-3, wherein the unit has an operating area and the sensing area overlaps the operating area.

5. The unit according to any one of claims 1-3, wherein the sensor coil array and / or sensing field is smaller than the operating area of ​​the unit.

6. The unit of any one of claims 1-3, further comprising one or more additional sensor arrays for sensing the presence of the at least one foreign object.

7. A unit according to claim 6, wherein each additional sensor array is arranged on a respective additional arm.

8. A unit according to any one of claims 1 to 3, wherein: The unit is used to wirelessly charge one or more of the following: • Electric vehicles, • Electrical system, •Battery, • Scooters, •robot, •Other electronic devices.

9. A unit according to any one of claims 1 to 3, wherein: The unit is used for wireless charging of electric bicycles.

10. A unit for real-time wireless transmission of power to a system or device, comprising: at least one coil for inductive power transfer, a sensor coil array having a sensing field for sensing the presence of at least one foreign object; an arm on which the sensor coil array is arranged, wherein the arm comprises an electromagnetic shielding material configured to shield the sensor coil array from an electromagnetic field emanating from the at least one coil, and A controller configured to: moving the arm to position the sensing field in a sensing area and moving the sensor coil array and / or the sensing field so that the sensing field scans the sensing area, and detecting the presence of the at least one foreign object in the sensing region based on outputs from the sensor coil array, Wherein, the controller is configured to move the sensor coil array and / or the sensing field such that the sensing field: a) being positioned in the sensing region such that the sensing field does not overlap with the at least one foreign object, and b) being positioned in the sensing region such that the sensing field overlaps the at least one foreign object.

11. The unit of claim 10, wherein the arm is a rotatable arm and the controller is configured to rotate the arm to position the sensing field.

12. The unit of claim 10, wherein the arm is configured as a slidable arm and the controller is configured to slide the arm to position the sensing field.

13. A unit according to any one of claims 10-12, wherein the unit has an operating area and the sensing area overlaps the operating area.

14. A unit according to any of claims 10-12, wherein the sensor coil array and / or sensing field is smaller than an operating area of ​​the unit.

15. The unit of any of claims 10-12, further comprising one or more additional sensor arrays for sensing the presence of the at least one foreign object.

16. A unit according to claim 15, wherein each additional sensor array is arranged on a respective additional arm.

17. A unit according to any one of claims 10 to 12, wherein: The unit is used to wirelessly charge one or more of the following: • Electric vehicles, • Electrical system, •Battery, • Scooters, •robot, •Other electronic devices.

18. A unit according to any one of claims 10 to 12, wherein: The unit is used for wireless charging of electric bicycles.

19. A unit for wirelessly charging an electric vehicle by inductive power transfer, comprising: at least one coil for inductive power transfer, a sensor coil array having a sensing field for sensing the presence of a foreign object; an arm on which the sensor coil array is arranged, wherein the arm comprises an electromagnetic shielding material configured to shield the sensor coil array from an electromagnetic field emanating from the at least one coil, and A controller configured to: moving the arm to position the sensing field in a sensing area and moving the sensor coil array and / or the sensing field so that the sensing field scans the sensing area, and detecting the presence of the foreign object in the sensing area based on outputs from the sensor coil array, Wherein the controller is configured to move the sensor coil array and / or the sensing field such that the sensing field: a) positioned in the sensing area so that the sensing field does not overlap with foreign objects, and b) being positioned in the sensing region such that the sensing field overlaps the foreign object.

20. The unit of claim 19, further comprising one or more sensor arrays for sensing the presence of the foreign object.

21. A sensing unit for a unit for wireless power transmission charging, the sensing unit comprising: a sensor coil array having a sensing field for sensing the presence of at least one foreign object; an arm on which the sensor coil array is arranged, wherein the arm comprises an electromagnetic shielding material configured to shield the sensor coil array from an electromagnetic field emitted from at least one coil of the sensing unit, the at least one coil being used for inductive power transfer, and A controller or communicating with a controller, the controller being configured to: moving the arm to position the sensing field in a sensing area and moving the sensor coil array and / or the sensing field so that the sensing field scans the sensing area, and detecting the presence of the at least one foreign object in the sensing region based on outputs from the sensor coil array, Wherein the controller is configured to move the sensor coil array and / or the sensing field such that the sensing field: a) being positioned in the sensing region such that the sensing field does not overlap with the at least one foreign object, and b) being positioned in the sensing region such that the sensing field overlaps the at least one foreign object.

22. The sensing unit of claim 21, further comprising one or more sensor arrays for sensing the presence of the at least one foreign object.

23. The sensing unit according to claim 21, wherein: The sensing unit is used to wirelessly charge one or more of the following: • Electric vehicles, • Electrical system, •Battery, • Scooters, •robot, •Other electronic devices.

24. The sensing unit according to claim 21, wherein The sensing unit is used for wirelessly charging the electric bicycle.

25. A sensing unit for real-time wireless transmission of power to a unit of a system or device, the sensing unit comprising: a sensor coil array having a sensing field for sensing the presence of at least one foreign object; an arm on which the sensor coil array is arranged, wherein the arm comprises an electromagnetic shielding material configured to shield the sensor coil array from an electromagnetic field emitted from at least one coil of the sensing unit, the at least one coil being used for inductive power transfer, and A controller or communicating with a controller, the controller being configured to: moving the arm to position the sensing field in a sensing area and moving the sensor coil array and / or the sensing field so that the sensing field scans the sensing area, and detecting the presence of the at least one foreign object in the sensing region based on outputs from the sensor coil array, Wherein the controller is configured to move the sensor coil array and / or the sensing field such that the sensing field: a) being positioned in the sensing region such that the sensing field does not overlap with the at least one foreign object, and b) being positioned in the sensing region such that the sensing field overlaps the at least one foreign object.

26. The sensing unit of claim 25, further comprising one or more sensor arrays for sensing the presence of the at least one foreign object.

27. The sensing unit according to claim 25, wherein: The sensing unit is used to wirelessly charge one or more of the following: • Electric vehicles, • Electrical system, •Battery, • Scooters, •robot, •Other electronic devices.

28. The sensing unit according to claim 25, wherein: The sensing unit is used for wirelessly charging the electric bicycle.

29. A wireless power transmission system comprising the unit according to claim 1 and / or the sensing unit according to claim 21.

30. The wireless power transmission system according to claim 29, wherein: The unit is used to wirelessly charge one or more of the following: • Electric vehicles, • Electrical system, •Battery, • Scooters, •robot, •Other electronic devices.

31. The wireless power transmission system of claim 29, wherein: The unit is used for wireless charging of electric bicycles.

32. The wireless power transmission system of claim 29, wherein: The sensing unit is used to wirelessly charge one or more of the following: • Electric vehicles, • Electrical system, •Battery, • Scooters, •robot, •Other electronic devices.

33. The wireless power transmission system of claim 29, wherein: The sensing unit is used for wirelessly charging the electric bicycle.

34. A power system for wireless power transmission for charging a system or device, comprising: at least one coil for inductive power transfer, a sensor coil array having a sensing field for sensing the presence of at least one foreign object; an arm on which the sensor coil array is arranged, wherein the arm comprises an electromagnetic shielding material configured to shield the sensor coil array from an electromagnetic field emanating from the at least one coil, and A controller configured to: moving the arm to position the sensing field in a sensing area and moving the sensor coil array and / or the sensing field so that the sensing field scans the sensing area, and detecting the presence of the at least one foreign object in the sensing region based on outputs from the sensor coil array, Wherein the controller is configured to move the sensor coil array and / or the sensing field such that the sensing field: a) being positioned in the sensing region such that the sensing field does not overlap with the at least one foreign object, and b) being positioned in the sensing region such that the sensing field overlaps the at least one foreign object.

35. A power system for wireless power transmission for real-time powering of a system or device, comprising: at least one coil for inductive power transfer, a sensor coil array having a sensing field for sensing the presence of at least one foreign object; an arm on which the sensor coil array is arranged, wherein the arm comprises an electromagnetic shielding material configured to shield the sensor coil array from an electromagnetic field emanating from the at least one coil, and A controller configured to: moving the arm to position the sensing field in a sensing area and moving the sensor coil array and / or the sensing field so that the sensing field scans the sensing area, and detecting the presence of the at least one foreign object in the sensing region based on outputs from the sensor coil array, Wherein the controller is configured to move the sensor coil array and / or the sensing field such that the sensing field: a) being positioned in the sensing region such that the sensing field does not overlap with the at least one foreign object, and b) being positioned in the sensing region such that the sensing field overlaps the at least one foreign object.

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