Foreign matter detection device and foreign matter detection method

Abstract

The application relates to a foreign matter detection device and a foreign matter detection method, which comprise a first detection unit, a plurality of first coils, each first coil is used for outputting a corresponding first induced electric signal according to an excitation magnetic field provided by a transmitting coil, each first coil is arranged in a coupling range of the transmitting coil and is parallel to the transmitting coil, each first coil is symmetrical to a first middle line of the transmitting coil, and each first coil is arranged in an array along a direction of the first middle line, the direction of the first middle line is perpendicular to a magnetic field direction of the transmitting coil, and a control module is connected with the first detection unit, the control module is used for judging whether foreign matter exists in the coupling range of the transmitting coil according to each first induced electric signal. The foreign matter is judged based on the first induced electric signal generated by a single first coil, and the foreign matter detection sensitivity and reliability can be effectively improved.

Description

Technical Field

[0001] This application relates to the field of wireless charging technology, and in particular to a foreign object detection device and a foreign object detection method. Background Technology

[0002] To conserve energy and reduce environmental pollution, electric vehicles have been vigorously promoted worldwide, leading to rapid growth in the global electric vehicle market in recent years. Limited battery capacity is a major factor contributing to range anxiety among car owners. To alleviate this problem, vigorously promoting the construction of charging infrastructure has become crucial for the vigorous development of the electric vehicle industry. Against this backdrop, wireless charging for electric vehicles, as an important supporting technology, has made significant progress in both technological research and commercial development. However, in the operation of magnetically coupled wireless charging systems, a high-frequency, high-intensity alternating magnetic field exists between the transmitting and receiving coils. When a metallic foreign object enters this area, it not only weakens the magnetic field coupling and reduces system efficiency but also causes a severe and rapid surface temperature rise due to eddy current effects, thus posing a fire hazard. Therefore, foreign object detection during wireless charging is essential.

[0003] However, current foreign object detection technologies suffer from low sensitivity and a tendency to generate false alarms. Summary of the Invention

[0004] Therefore, it is necessary to provide a foreign object detection device and method to address the problems of low sensitivity and false alarms in existing foreign object detection devices.

[0005] To achieve the above objectives, this application provides a foreign object detection device, comprising:

[0006] The first detection unit includes a plurality of first coils. Each first coil is used to output a corresponding first induced electrical signal according to the excitation magnetic field provided by the transmitting coil. Each first coil is located within the coupling range of the transmitting coil and is parallel to the transmitting coil. Each first coil is symmetrical with respect to the first center line of the transmitting coil and is arranged in an array along the direction of the first center line. The direction of the first center line is perpendicular to the magnetic field direction of the transmitting coil.

[0007] A control module is connected to the first detection unit. The control module is used to determine whether there are foreign objects within the coupling range of the transmitting coil based on each of the first induced electrical signals.

[0008] In one embodiment, the foreign object detection device further includes:

[0009] The second detection unit is located within the coupling range of the transmitting coil. The second detection unit includes a second coil, which is used to generate a second induced electrical signal.

[0010] Wherein, the magnetic flux in the region enclosed by the second coil and the second center line in the first part is equal to the magnetic flux in the region enclosed by the second coil and the second center line in the second part, and the two parts of the second coil are respectively located on both sides of the second center line of the second coil;

[0011] The control module is also used to determine whether there are foreign objects within the coupling range of the transmitting coil based on each of the first induced electrical signal and the second induced electrical signal.

[0012] In one embodiment, the second centerline coincides with the first centerline of the transmitting coil, and the second coil includes a plurality of rectangular regions, each of which is alternately arranged on both sides of the first centerline along the first centerline.

[0013] The area enclosed by the rectangular region on one side of the first center line and the first center line is equal to the area enclosed by the rectangular region on the other side of the first center line and the first center line.

[0014] In one embodiment, the second detection unit further includes:

[0015] A third coil surrounds the edge of the transmitting coil, and the orthographic projection of the third coil partially overlaps with that of the transmitting coil. The third coil is used to generate a third induced electrical signal to compensate for the magnetic field detection blind zone of the first detection unit.

[0016] The control module is used to determine whether there are foreign objects within the coupling range of the transmitting coil based on the first induced electrical signal, the second induced electrical signal, and the third induced electrical signal.

[0017] In one embodiment, the edge of the transmitting coil is rectangular, and two first symmetrical regions and two second symmetrical regions are alternately arranged along the four sides of the rectangle, with the two first symmetrical regions being symmetrical about the first centerline;

[0018] In the same first symmetrical region, the magnetic flux in the region enclosed by a portion of the third coil and the third center line is equal to the magnetic flux in the region enclosed by the other portion of the third coil and the third center line. The two portions of the third coil are located on both sides of the third center line, and the third center line is parallel to the first center line.

[0019] In the same second symmetrical region, the magnetic flux in the region enclosed by a portion of the third coil and the fourth center line is equal to the magnetic flux in the region enclosed by the other portion of the third coil and the fourth center line. The two portions of the third coil are located on both sides of the fourth center line, which is perpendicular to the first center line.

[0020] In one embodiment, the control module includes:

[0021] A signal receiving unit is connected to the first detection unit and the second detection unit respectively, and is used to acquire each of the first induced electrical signal, the second induced electrical signal and the third induced electrical signal respectively;

[0022] A signal processing unit, connected to the signal receiving unit, is used to determine whether there are foreign objects within the coupling range of the transmitting coil based on the amplitude of each of the first induced electrical signal, the amplitude of the second induced electrical signal, the amplitude of the third induced electrical signal, a first preset threshold, a second preset threshold, and a third preset threshold.

[0023] In one embodiment, the signal processing unit is used to add the amplitudes of the first induced electrical signals output by any two adjacent first coils according to a preset ratio to generate a processed value, and compare the processed value with the first preset threshold.

[0024] In one embodiment, the signal processing unit is further configured to determine that there are no foreign objects within the coupling range of the transmitting coil when all of the processed values ​​are less than or equal to the first preset threshold, the amplitude of the second induced electrical signal is less than or equal to the second preset threshold, and the amplitude of the third induced electrical signal is less than or equal to the third preset threshold; and / or

[0025] When any of the processed values ​​is greater than the first preset threshold, or the amplitude of the second induced electrical signal is greater than the second preset threshold, or the amplitude of the third induced electrical signal is greater than the third preset threshold, it is determined that there is a foreign object within the coupling range of the transmitting coil.

[0026] This application also provides a foreign object detection method, applied to the foreign object detection device described above, the method comprising:

[0027] When the receiving coil is not within the coupling range of the transmitting coil, the drive control module acquires multiple first induced electrical signals;

[0028] When the control module determines that there are no foreign objects within the coupling range of the transmitting coil based on each of the first induced electrical signals, it issues an entry command; the entry command is used to instruct the vehicle to be charged to enter so that the receiving coil of the vehicle to be charged is within the coupling range of the transmitting coil.

[0029] In one embodiment, the method further includes:

[0030] The control module is driven to acquire the second and third induced electrical signals;

[0031] When the control module determines that there is a foreign object within the coupling range of the transmitting coil based on each of the first induced electrical signals or any two adjacent first induced electrical signals, the second induced electrical signals, or the third induced electrical signals, it controls the transmitting coil to stop transmitting signals.

[0032] In the aforementioned foreign object detection device, the structure of each first coil in the first detection unit extends along the magnetic field direction of the transmitting coil. When there is no foreign object within the range of a single first coil, the magnetic flux of the first coil on both sides of the first center line of the transmitting coil is the same. However, when there is a foreign object, the magnetic flux of the first coil on both sides of the first center line of the transmitting coil is different, and the first induced electrical signal generated by the first coil changes accordingly. Therefore, the control module can determine whether there is a foreign object within the coupling range of the transmitting coil by using the first induced electrical signal output by each first coil. Compared with the foreign object detection method that uses the voltage difference between the balanced coil pairs as the criterion, the above method of judging foreign objects based on the first induced electrical signal generated by a single first coil can effectively improve the sensitivity and reliability of foreign object detection. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of this application or the conventional technology, the drawings used in the description of the embodiments or the conventional technology will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 This is one of the structural schematic diagrams of a foreign object detection device provided in one embodiment;

[0035] Figure 2 This is a schematic diagram of the structure of the first detection unit provided in one embodiment;

[0036] Figure 3 This is a second schematic diagram of the foreign object detection device provided in one embodiment;

[0037] Figure 4 This is a schematic diagram of the structure of the first detection unit and the second coil combined in one embodiment;

[0038] Figure 5 This is a schematic diagram of the structure of the third coil provided in one embodiment;

[0039] Figure 6 This is a third schematic diagram of the foreign object detection device provided in one embodiment;

[0040] Figure 7 This is one of the flowcharts illustrating a foreign object detection method provided in one embodiment;

[0041] Figure 8 This is a second schematic flowchart of a foreign object detection method provided in one embodiment.

[0042] Explanation of reference numerals in the attached figures:

[0043] First detection unit: 10; Control module: 20; Second detection unit: 30; First coil: 101; Signal receiving unit: 201; Signal processing unit: 202; Second coil: 301; Third coil: 302. Detailed Implementation

[0044] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings, which illustrate embodiments of the present application. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of this application will be more thorough and complete.

[0045] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0046] Spatial relation terms such as “below,” “under,” “below,” “under,” “above,” “above,” etc., are used herein to describe the relationship between one element or feature shown in the figure and other elements or features. It should be understood that, in addition to the orientation shown in the figure, spatial relation terms also include different orientations of the device in use and operation. For example, if the device in the figure is flipped, the element or feature described as “below,” “under,” or “below” will be oriented “above” the other element or feature. Therefore, the exemplary terms “below” and “under” can include both above and below orientations. Furthermore, the device may also include other orientations (e.g., rotated 90 degrees or other orientations), and the spatial descriptive terms used herein will be interpreted accordingly.

[0047] When used herein, the singular forms of “a,” “an,” and “the” may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising / including” or “having,” etc., specify the presence of the stated features, wholes, steps, operations, components, parts, or combinations thereof, but do not preclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof. Meanwhile, in this specification, the term “and / or” includes any and all combinations of the associated listed items.

[0048] Charging methods for electrical devices such as electric vehicles, mobile robots, and drones mainly include: wired charging (also known as conductive charging) and wireless charging (also known as contactless charging). Wired charging offers higher charging power, higher efficiency, and better technological maturity, but the power extraction process is inflexible, requiring repeated plugging and unplugging of the charging plug, which can cause wear and tear, leading to safety hazards such as electrical leakage. Furthermore, in rainy or snowy weather, charging devices require moisture protection; otherwise, outdoor charging under adverse weather conditions is impossible. Additionally, the land utilization rate of charging stations is relatively low, resulting in high construction costs. In contrast, wireless charging offers better information and intelligence, reduces labor costs, and is safe and reliable, effectively addressing the problems associated with wired charging. Therefore, wireless charging has become the main development direction for electric vehicle charging.

[0049] However, during the operation of a magnetically coupled wireless charging system, a high-frequency, high-intensity alternating magnetic field exists between the transmitting and receiving coils. When a metallic foreign object enters this area, it not only weakens the magnetic field coupling and reduces the charging system's efficiency, but also causes a severe and rapid surface temperature rise due to eddy current effects, thus posing a fire hazard. Therefore, to ensure the efficient and safe operation of wireless charging systems, foreign object detection technology is receiving increasing attention.

[0050] Furthermore, the coupling coil (including the transmitting coil and the receiving coil) is the core component of a magnetic field-coupled wireless charging system. Common coil topologies include circular, rectangular, and DD-type. Among them, the DD-type coil consists of two rectangular coils with parallel circuits and series magnetic circuits. Compared with circular and rectangular coils, the DD-type coil has a larger coupling coefficient and stronger resistance to horizontal offset. Therefore, the DD-type coil has become one of the mainstream commercial choices for automotive charging coils.

[0051] However, most foreign object detection technologies currently on the market only support wireless charging systems with simple coil topologies, such as circular and rectangular ones. Foreign object detection devices specifically designed for DD-type coil wireless charging systems are extremely rare. Furthermore, foreign object detection devices based on circular or rectangular coils lack portability. Moreover, foreign object detection methods for circular and rectangular coils often rely on the voltage difference between two coils physically connected at symmetrical positions (voltage difference method). When this method is applied to DD-type coils, it suffers from a series of problems, including low detection sensitivity and a high susceptibility to false alarms.

[0052] Therefore, to solve the above problems, this application provides a foreign object detection device. Please refer to [link to relevant documentation]. Figure 1 The foreign object detection device includes a first detection unit 10 and a control module 20.

[0053] The wireless charging system for electric vehicles includes a transmitter and a receiver. The transmitter includes a transmitting coil and a transmitter control circuit, while the receiver includes a receiving coil and a receiver control circuit. The transmitting coil is buried in the ground and has a planar design. The receiving coil is mounted on the vehicle chassis and parallel to the ground. When an electric vehicle drives in, causing the receiving coil to align with or slightly offset from the transmitting coil, the transmitter control circuit converts the mains frequency AC power into high-frequency AC power. After compensation, the high-frequency AC power is converted into magnetic energy by the primary transmitting coil, generating a high-frequency magnetic field between the primary and secondary coils. There is no direct electrical connection between the primary transmitting coil and the secondary receiving coil. The secondary receiving coil senses the high-frequency magnetic field and converts it back into high-frequency AC power, which is then converted into direct current by the receiver control circuit for charging the electric vehicle, thus achieving contactless charging.

[0054] The first detection unit 10 in the foreign object detection device is located within the coupling range of the transmitting coil. The first detection unit 10 includes a plurality of first coils 101. Each first coil 101 is used to output a corresponding first induced electrical signal according to the excitation magnetic field provided by the transmitting coil. Each first coil 101 is located within the coupling range of the transmitting coil and is parallel to the transmitting coil. Each first coil 101 is symmetrical with respect to the first center line of the transmitting coil and is arranged in an array along the direction of the first center line. The direction of the first center line is perpendicular to the direction of the magnetic field of the transmitting coil. The control module 20 is used to determine whether there is a foreign object within the coupling range of the transmitting coil according to each first induced electrical signal.

[0055] Specifically, the transmitting coil can be a DD-type coil, and the first detection unit 10 is laid on the entire surface of the transmitting coil, located between the transmitting coil and the receiving coil, and coupled to both the transmitting coil and the receiving coil. The induced electrical signal includes an induced voltage signal and an induced current signal. Optionally, in this embodiment, the first detection unit 10 collects a first induced voltage signal over the entire area of ​​the transmitting coil and uses multiple first induced voltage signals as criteria for determining the presence or absence of foreign objects.

[0056] Furthermore, the traditional detection method involves distributing each first coil along a direction orthogonal to the magnetic field direction of the transmitting coil, and combining two first coils symmetrical about the first centerline of the transmitting coil as a pair of detection coils. The presence of foreign objects is determined by measuring the change in the induced voltage difference across the two detection coils. However, the method of symmetrically placing two detection coils to form a balanced coil is limited by the power magnetic field characteristics, which will affect the accuracy of foreign object detection and easily lead to misjudgment.

[0057] Based on this, this application proposes that each first coil 101 extend along the magnetic field direction of the transmitting coil, instead of extending in a direction orthogonal to the magnetic field direction as described above. When there are no foreign objects within the range of a single first coil 101, the magnetic flux distributed on both sides of the first centerline of the transmitting coil is the same, so the amplitude of the first induced electrical signal it generates should be 0 or within a preset range. However, when there are foreign objects, the voltage balance of the first coil 101 is broken, and the first induced electrical signal it generates changes. Therefore, the control module 20 is connected to the first detection unit 10, that is, the control module 20 is connected to each first coil 101 to receive the first induced electrical signal output by each first coil 101. The control module 20 detects whether the amplitude of the corresponding first induced electrical signal generated by each first coil 101 is 0 or within a preset range. If so, it determines that there are no foreign objects intruding within the coupling range of the transmitting coil; otherwise, it determines that there are foreign objects within the coupling range of the transmitting coil.

[0058] In the above example, the structure of each first coil 101 of the first detection unit 10 extends along the magnetic field direction of the transmitting coil. When there is no foreign object within the range of a single first coil 101, the magnetic flux of the first coil 101 on both sides of the first center line of the transmitting coil is the same. However, when there is a foreign object, the magnetic flux of the first coil 101 on both sides of the first center line of the transmitting coil is different. The first induced electrical signal generated by the first coil 101 changes as a result. Therefore, the control module 20 can determine whether there is a foreign object within the coupling range of the transmitting coil by the first induced electrical signal output by each first coil 101. Compared with the foreign object detection method based on the voltage difference of the balanced coil pair, the above method of foreign object judgment based on the first induced electrical signal generated by a single first coil 101 can effectively improve the sensitivity and reliability of foreign object detection.

[0059] In one embodiment, such as Figure 2 As shown, Figure 2 A schematic diagram of the structure of the first detection unit 10 is shown, wherein each of the first coils 101 has a multi-turn coil structure. Specifically, the direction of the first centerline of the transmitting coil is denoted as the y-axis direction, and the direction parallel to the magnetic field direction is denoted as the x-axis direction. n first coils 101 with multi-turn coil structures are evenly arranged from top to bottom along the y-axis direction. Each first coil 101 is symmetrical about the y-axis, and each first coil is denoted as a1, a2, ..., a1 from top to bottom. n Furthermore, the shape of the first coil 101 can be circular, rectangular, or other polygonal. However, since rectangular coils can be arranged closely due to their geometric features, this application preferably uses a rectangular shape for the first coil 101 and adopts a multi-turn coil structure to further enhance the sensitivity of foreign object detection.

[0060] In one embodiment, in conjunction with reference Figure 3and Figure 4 , Figure 3 Another structural schematic diagram of the foreign object detection device is shown. Figure 4 The diagram shows the structure of the first detection unit 10 combined with the second coil 301. The foreign object detection device provided in this application also includes a second detection unit 30, which is located within the coupling range of the transmitting coil. The second detection unit 30 includes a second coil 301, which is used to generate a second induced electrical signal. The magnetic flux within the area enclosed by the first portion of the second coil 301 and the second center line is equal to the magnetic flux within the area enclosed by the second portion of the second coil 301 and the second center line. The two portions of the second coil are located on opposite sides of the second center line of the second coil 301. The control module 20 is further used to determine whether a foreign object exists within the coupling range of the transmitting coil based on each of the first and second induced electrical signals.

[0061] It is understandable that, based on the geometric characteristics of the array arrangement of the first coil 101, when a foreign object invades the double-D junction (central axis region) of the DD-type transmitting coil, since the magnetic field direction is generally parallel, the magnetic field lines lack the ability to pass through this region, and therefore lack the ability to change the induced electrical signal. Although in actual practice, the first induced electrical signal generated in the central axis detection region will still change, the final output first induced electrical signal does not change much, which is not significantly different from the case when no foreign object has invaded. Therefore, it is impossible to detect that the foreign object is present at this time, resulting in a central axis detection blind zone for the first detection unit 10. Based on this, a second detection unit 30 is set within the coupling range of the transmitting coil to eliminate the central axis detection blind zone generated by the first detection unit 10. It should be noted that the second detection unit 30 can be set on the side of the first detection unit 10 away from the transmitting coil, or it can be set on the side of the first detection unit 10 closer to the transmitting coil. That is, the stacking order of the second detection unit 30 and the first detection unit 10 can be interchanged, and this application does not limit the order.

[0062] Furthermore, the second coil 301 is located in the central axis region of the first detection unit, and the structural design of the second coil 301 needs to ensure that, in the absence of foreign objects, the amplitude of the second induced electrical signal it generates is 0 or within a preset range. To achieve this, it is necessary to ensure that the magnetic flux enclosed by the second coil 301 on the left side of the y-axis and the second center line is equal to the magnetic flux enclosed by the second center line on the right side of the y-axis. The second center line is located in... Figure 3 This is shown as coinciding with the y-axis direction.

[0063] The control module 20 can determine whether there are foreign objects in the coupling range of the transmitting coil except for the central axis area through the first induced electrical signals, and can determine whether there are foreign objects in the central axis area of ​​the transmitting coil through the second induced electrical signals. This can effectively eliminate the central axis detection blind zone, thereby realizing full detection of the transmitting coil and avoiding further expansion of the detection blind zone.

[0064] In one embodiment, reference continues Figure 4 The second centerline coincides with the first centerline of the transmitting coil. The second coil 301 includes multiple rectangular regions, each of which is arranged alternately on both sides of the first centerline. The area enclosed by the rectangular region on one side of the first centerline and the first centerline is equal to the area enclosed by the rectangular region on the other side of the first centerline and the first centerline.

[0065] Specifically, the first centerline of the transmitting coil and the second centerline of the second coil 301 coincide, and are denoted as the y-axis direction. The second coil 301 is distributed from top to bottom along the y-axis. In this embodiment, the rectangular areas of the second coil 301 are alternately arranged from top to bottom on the left and right sides of the y-axis to ensure that when a foreign object is in the central axis region of the transmitting coil, it falls into at least one of the rectangular areas. At the same time, it is necessary to ensure that the area enclosed by the rectangular areas on the left side of the y-axis and the y-axis is equal to the area enclosed by the rectangular areas on the right side of the y-axis and the y-axis, so that the amplitude of the second induced electrical signal generated by the second coil 301 in the absence of foreign objects is 0 or within a preset range.

[0066] Furthermore, this embodiment uses the second coil 301 comprising three rectangular regions as an example for explanation. The two rectangular regions located to the left of the y-axis are of the same size, and the size of a single rectangular region on the left is smaller than that on the right. These rectangular regions are arranged continuously and alternately. When a foreign object invades the central axis region, the magnetic flux density of the second coil 301 changes, thereby causing a change in the output second induced electrical signal. This effectively eliminates the central axis detection blind zone present in the first detection unit 10. Moreover, when a foreign object invades the center (origin), only the larger rectangular region experiences a change in magnetic flux density, while the other two rectangular regions are almost unaffected, effectively eliminating the central blind zone as well. Therefore, the second coil 301 can eliminate the detection blind zones of the central axis and center point of the first detection unit 10, achieving a significant reduction in the area ratio of the foreign object detection blind zone with a simple structural design.

[0067] In one embodiment, such as Figure 5 As shown, Figure 5A schematic diagram of the structure of the third coil 302 is shown. The second detection unit also includes the third coil 302, which surrounds the edge of the transmitting coil and the orthographic projection of the third coil 302 partially overlaps with the transmitting coil. The third coil 302 is used to generate a third induced electrical signal to compensate for the magnetic field detection blind zone of the first detection unit. The control module is used to determine whether there is a foreign object within the coupling range of the transmitting coil based on the first induced electrical signal, the second induced electrical signal and the third induced electrical signal.

[0068] It is understandable that the edge region of the transmitting coil (at the four edges) not only has a weak magnetic induction intensity, but also, when a foreign object intrudes into this area, because the magnetic field direction is generally parallel, the magnetic field lines lack the ability to pass through this region. Therefore, relying solely on the first detection coil is insufficient to detect the metallic foreign object intruding into the edge region, resulting in a blind spot in edge detection. Therefore, designing a third coil 302 based on the first detection unit can effectively eliminate several undetectable areas at the edge of the transmitting coil. It should be noted that the stacking order of the first detection unit, the second coil, and the third coil 302 can be interchanged; this application does not restrict this order.

[0069] Furthermore, the orthographic projection of the third coil 302 should be distributed along the four edges of the first detection unit, and the polarities of the third coil 302 connection should be mutually canceling (left-right and top-bottom canceling). The control module acquires the first induced electrical signal output by each first coil, the second induced electrical signal output by the second coil, and the third induced electrical signal output by the third coil 302. The first induced electrical signal can be used to determine whether there are foreign objects within the coupling range of the transmitting coil, excluding the central axis region. The second induced electrical signal can be used to determine whether there are foreign objects within the central axis region of the transmitting coil. The third induced electrical signal can be used to determine whether there are foreign objects in the edge region of the transmitting coil, thereby achieving full-area foreign object detection of the transmitting coil.

[0070] In one embodiment, the edge of the transmitting coil is rectangular, and two first symmetrical regions and two second symmetrical regions are alternately arranged along the four sides of the rectangle. The two first symmetrical regions are symmetrical about a first center line. In the same first symmetrical region, the magnetic flux in the region enclosed by a portion of the third coil 302 and the third center line is equal to the magnetic flux in the region enclosed by the other portion of the third coil 302 and the third center line. The two portions of the third coil 302 are located on both sides of the third center line, and the third center line is parallel to the first center line. In the same second symmetrical region, the magnetic flux in the region enclosed by a portion of the third coil 302 and the fourth center line is equal to the magnetic flux in the region enclosed by the other portion of the third coil 302 and the fourth center line. The two portions of the third coil 302 are located on both sides of the fourth center line, and the fourth center line is perpendicular to the first center line.

[0071] It is understandable that the structural design of the third coil 302 needs to ensure that, in the absence of foreign objects, the amplitude of the third induced electrical signal it generates is 0 or within a preset range. To achieve this, it is necessary to ensure that the magnetic flux on one side of any symmetrical region is equal to the magnetic flux on the other side. Furthermore, each symmetrical region may include multiple rectangular regions, to... Figure 5 Taking the rightmost first symmetrical region, comprising three rectangular regions, as an example, the rectangular regions are alternately arranged on both sides of the third center line (parallel to the y-axis) to ensure that when a foreign object is within this first symmetrical region, it falls into at least one of the rectangular regions. This changes the magnetic flux density of the third coil 302, causing a change in the output third induced electrical signal, thereby effectively eliminating the edge detection blind zone present in the first detection unit. Furthermore, the second symmetrical region has the same structure as the first symmetrical region, but different dimensions. This embodiment uses... Figure 5 Taking the uppermost second symmetry region, comprising three rectangular regions, as an example, each rectangular region is alternately arranged along the fourth center line (perpendicular to the y-axis) on both sides of the fourth center line. This ensures that when a foreign object is within this second symmetry region, it falls into at least one of the rectangular regions, thereby changing the magnetic flux density of the third coil 302 and causing a change in the output third induced electrical signal. It should be noted that the topology of the two first symmetry regions and the two second symmetry regions can be the same as that of the second coil.

[0072] In one embodiment, such as Figure 6 As shown, Figure 6 A schematic diagram of another foreign object detection device is shown. The control module 20 includes a signal receiving unit 201 and a signal processing unit 202. The signal receiving unit 201 is connected to the first detection unit 10 and the second detection unit 30, respectively. The signal receiving unit 201 is used to acquire each of the first induced electrical signal, the second induced electrical signal and the third induced electrical signal. The signal processing unit 202 is connected to the signal receiving unit 201 and is used to determine whether there is a foreign object within the coupling range of the transmitting coil based on the amplitude of each of the first induced electrical signal, the amplitude of the second induced electrical signal, the amplitude of the third induced electrical signal, a first preset threshold, a second preset threshold and a third preset threshold.

[0073] Specifically, the signal receiving unit 201 is connected to each of the first coils in the first detection unit 10 and receives the first induced electrical signal output by each of the first coils. At the same time, the signal receiving unit 201 is also connected to the second coil 301 and the third coil 302 in the second detection unit 30 and receives the second induced electrical signal output by the second coil 301 and the third induced electrical signal output by the third coil 302.

[0074] Further, the signal receiving unit 201 transmits the acquired signal to the subsequent signal processing unit 202 for calculation, analysis, and output of a decision. The signal processing unit 202 compares the amplitude of the second induced electrical signal output by the second coil 301 with a second preset threshold, and the amplitude of the third induced electrical signal output by the third coil 302 with a third preset threshold. If the former does not exceed the latter, the detection continues; otherwise, it is determined that there is foreign object intrusion in the wireless charging system. The signal processing unit 202 continues to compare each of the first induced electrical signals output by the first detection unit 10 with the first preset threshold. If any first induced electrical signal exceeds the first preset threshold, and the second induced electrical signal output by the second detection unit 30 is less than the second preset threshold and the third induced electrical signal is less than the third preset threshold, it can be determined that there is no foreign object intrusion in the wireless charging system.

[0075] However, when a foreign object is located between any two adjacent first coils, a uniform magnetic field region appears at the location of the foreign object, meaning the amplitude of the first induced electrical signal exhibits a high-low-high-low distribution. For example, if only half of the foreign object penetrates one of the first coils, even if the voltage balance is disrupted, the amplitude of the first induced electrical signal output by that first coil is close to the first preset threshold, easily leading to misjudgment and missed detection. To address this problem, although another layer of first detection units can be interleaved on the surface of the first detection unit 10, if only half of the foreign object's area falls within the original first detection unit, then the entire area of ​​the foreign object will fall within the newly superimposed first detection unit, thus solving the misjudgment problem, using two layers of physical coils increases the design difficulty and cost of the PCB detection coil. Based on this, this application proposes a virtual double-layer coil method to solve the misjudgment situation caused by a single-layer first detection unit.

[0076] In one embodiment, the signal processing unit 202 is used to add the amplitudes of the first induced electrical signals output by any two adjacent first coils according to a preset ratio to generate a processed value, and compare the processed value with a first preset threshold.

[0077] It is understandable that the signal processing unit 202 can construct an effect where foreign objects always fall within one of the first coils by flexibly combining the first induced electrical signals generated by adjacent first coils and adding them in a certain proportion. This results in a detection effect very close to that produced by the superposition of two first detection units. Therefore, the aforementioned virtual double-layer coil method achieves a detection effect comparable to that of a double-layer physical coil without adding an additional physical coil, through clever information processing. Without sacrificing cost-effectiveness, it greatly improves the sensitivity and reliability of foreign object detection and significantly reduces the probability of false positives.

[0078] Furthermore, the signal processing unit 202 obtains a processing value generated by any two adjacent first coils based on formula (1), while the entire first detection unit 10 will generate multiple processing values.

[0079] V 处 =α1V1+α2V2---(1)

[0080] Among them, V 处 For the processing value, V1 and V2 are the amplitudes of the first induced electrical signals generated by the two adjacent first coils, respectively. The setting of the two coefficients α1 and α2 should ensure that the processing value obtained by equation (1) is at least three times the first preset threshold.

[0081] In one embodiment, the signal processing unit 202 is further configured to determine that there are no foreign objects within the coupling range of the transmitting coil when each of the processed values ​​is less than or equal to a first preset threshold, the amplitude of the second induced electrical signal is less than or equal to a second preset threshold, and the amplitude of the third induced electrical signal is less than or equal to a third preset threshold.

[0082] When the corresponding processing values ​​generated by the sum of the adjacent first coils according to the preset ratio are all within the first preset threshold range, and the amplitude of the second induced electrical signal output by the second coil is within the second preset threshold range, and the amplitude of the third induced electrical signal output by the third coil is within the third preset threshold range, it indicates that there is no foreign object intrusion into the transmitting coil.

[0083] In one embodiment, when any processed value is greater than a first preset threshold, or the amplitude of the second induced electrical signal is greater than a second preset threshold, or the amplitude of the third induced electrical signal is greater than a third preset threshold, it is determined that there is a foreign object within the coupling range of the transmitting coil.

[0084] If the processing value formed by any two adjacent first coils exceeds the range of the first preset threshold, it indicates that there is a foreign object between the adjacent first coils. This indicates that a foreign object has entered the transmitting coil. Alternatively, if the amplitude of the second induced electrical signal output by the second coil or the amplitude of the third induced electrical signal output by the third coil exceeds the corresponding preset threshold, it indicates that a foreign object has entered the coil.

[0085] In one embodiment, the signal processing unit 202 includes a sampling resistor, a low-pass filter, an operational amplifier, and a central processing unit connected in sequence. The first, second, and third induced electrical signals received by the signal processing unit 202 are first sent to the sampling resistor, whose resistance is generally above 100kΩ. Since the signal processing unit 202 analyzes the fundamental signal, each signal after passing through the sampling resistor needs to be passed through a next-stage low-pass filter to filter out higher harmonics. Then, it passes through an operational amplifier to amplify each signal, improving the accuracy of the signal processing unit 202's judgment. Finally, each signal is input to the central processing unit for processing and analysis to determine whether a foreign object has intruded.

[0086] This application also provides a foreign object detection method, applied to the foreign object detection device described above, such as... Figure 7 As shown, the method includes steps S100 and S200, as detailed below:

[0087] Step S100: When the receiving coil is not within the coupling range of the transmitting coil, the drive control module acquires multiple first induced electrical signals.

[0088] When an electric vehicle approaches the wireless charging device, the foreign object detection circuit of the wireless charging system is automatically connected. Simultaneously, the system automatically sets pre-defined first, second, and third preset thresholds in the signal processing unit. When the electric vehicle is about to enter the charging position and is within a distance where the on-board receiver will not interfere with the electromagnetic parameters of the transmitter, the wireless charging transmitting coil circuit is automatically connected. The transmitting coil can be supplied with a small current (e.g., 1A) below its rated value for no-load detection. The signal receiving unit in the control module acquires the first induced electrical signals output from each first coil within the first detection unit and transmits them to the signal processing unit.

[0089] Step S200: When the control module determines that there are no foreign objects within the coupling range of the transmitting coil based on each of the first induced electrical signals, it issues an entry command; the entry command is used to instruct the vehicle to be charged to enter so that the receiving coil of the vehicle to be charged is within the coupling range of the transmitting coil.

[0090] The signal processing unit in the control module compares the amplitude of each first induced electrical signal with a first preset threshold, and adds the amplitudes of the first induced electrical signals output by each adjacent first coil according to a preset ratio. Multiple processed values ​​are obtained in the first detection unit, and each processed value is compared with the first preset threshold. If the amplitude of each first induced electrical signal does not exceed the first preset threshold, and the processed value does not exceed the first preset threshold, it is determined that there are no foreign objects within the coupling range of the transmitting coil. An entry command is then issued, and the electric vehicle drives into the charging station for normal charging. During charging, routine foreign object detection under rated load continues to prevent foreign object intrusion. If the amplitude of any first induced electrical signal exceeds the first preset threshold, or if any processed value exceeds the first preset threshold, it indicates that there are foreign objects within the coupling range of the transmitting coil. In this case, the transmitting coil needs to be stopped, and an alarm signal is issued to indicate that the foreign object needs to be removed. After the foreign object is removed, step S100 is repeated.

[0091] In one embodiment, the foreign object detection method further includes steps S300 and S400, as follows:

[0092] Step S300: The drive control module acquires the second and third induced electrical signals.

[0093] When the foreign object detection device also includes a second detection unit, the signal receiving unit of the control module will also acquire the second induced electrical signal output by the second coil and the third induced electrical signal output by the third coil, and transmit them to the signal processing unit.

[0094] Step S400: When the control module determines that there is a foreign object within the coupling range of the transmitting coil based on each of the first induced electrical signals or any two adjacent first induced electrical signals, the second induced electrical signals, or the third induced electrical signals, it controls the transmitting coil to stop transmitting signals.

[0095] The signal processing unit compares the amplitude of the second induced electrical signal with a second preset threshold and the amplitude of the third induced electrical signal with a third preset threshold. If the former does not exceed the latter, the process proceeds to step S100; otherwise, it indicates the presence of foreign objects within the coupling range of the transmitting coil. In this case, the transmitting coil needs to be stopped, and an alarm signal is issued to indicate that the foreign objects need to be removed. After the foreign objects are removed, the process repeats to step S100.

[0096] In one embodiment, such as Figure 8 The diagram shows a flowchart of a foreign object detection method, wherein the method includes steps S10, S20, S30, S40, S50 and S60.

[0097] Step S10: Before the electric vehicle enters, the wireless system is initialized, and the first preset threshold, the second preset threshold and the third preset threshold are placed in the signal processing unit for no-load detection.

[0098] Step S20: The signal receiving unit acquires the second induced electrical signal and the third induced electrical signal output by the second detection unit and transmits them to the signal processing unit.

[0099] Step S30: The signal processing unit determines whether the amplitude of the second induced electrical signal is greater than the second preset threshold and whether the amplitude of the third induced electrical signal is greater than the third preset threshold. If so, the transmitting coil stops working and issues an alarm signal to prompt the removal of foreign objects.

[0100] Step S40: The signal receiving unit acquires the first induced electrical signal output by each first coil in the first detection unit and transmits it to the signal processing unit.

[0101] Step S50: The signal processing unit adds the amplitudes of the first induced electrical signals output by each adjacent first coil according to a preset ratio, and obtains multiple processed values ​​in the first detection unit. It then determines whether each processed value and the amplitude of each first induced electrical signal are less than or equal to a first preset threshold. If not, the transmitting coil stops working and issues an alarm signal to prompt the removal of foreign objects.

[0102] Step S60: Issue a driving command, and the electric vehicle drives into the charging station for normal charging.

[0103] It should be noted that during the charging process, routine foreign object detection under rated load will continue to be performed to prevent foreign objects from entering during the charging process.

[0104] It should be understood that, although Figure 7 and Figure 8 The steps in the flowchart are shown sequentially as indicated by the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order in which these steps are executed, and they can be performed in other orders. Figure 7 and Figure 8 At least some of the steps in the process may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but may be executed at different times. The execution order of these steps or stages is not necessarily sequential, but may be executed in turn or alternately with other steps or at least some of the steps or stages in other steps.

[0105] In the description of this specification, the references to terms such as "some embodiments," "other embodiments," "ideal embodiments," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example that are included in at least one embodiment or example of this application. In this specification, the illustrative descriptions of the above terms do not necessarily refer to the same embodiments or examples.

[0106] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features of the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0107] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A foreign object detection device, characterized in that, include: The first detection unit includes a plurality of first coils. Each first coil is used to output a corresponding first induced electrical signal according to the excitation magnetic field provided by the transmitting coil. Each first coil is located within the coupling range of the transmitting coil and is parallel to the transmitting coil. Each first coil is symmetrical with respect to the first center line of the transmitting coil and is arranged in an array along the direction of the first center line. The direction of the first center line is perpendicular to the magnetic field direction of the transmitting coil. The control module is connected to the first detection unit; The foreign object detection device also includes: The second detection unit is located within the coupling range of the transmitting coil. The second detection unit includes a second coil, which is used to generate a second induced electrical signal. The second coil is located in the central axis region of the first detection unit, and the amplitude of the second induced electrical signal generated by the second coil in the absence of foreign objects is 0 or within a preset range. Wherein, the magnetic flux within the region enclosed by the second coil and the second center line in the first part is equal to the magnetic flux within the region enclosed by the second coil and the second center line in the second part, and the two parts of the second coil are respectively located on both sides of the second center line of the second coil; the second center line coincides with the first center line of the transmitting coil; The second coil includes multiple rectangular regions, each of which is alternately arranged on both sides of the first center line along the first center line; The area enclosed by the rectangular area on one side of the first center line and the first center line is equal to the area enclosed by the rectangular area on the other side of the first center line and the first center line. The second detection unit further includes: A third coil surrounds the edge of the transmitting coil, and the orthographic projection of the third coil partially overlaps with that of the transmitting coil. The third coil is used to generate a third induced electrical signal to compensate for the magnetic field detection blind zone of the first detection unit. The control module is used to determine whether there are foreign objects within the coupling range of the transmitting coil based on the first induced electrical signal, the second induced electrical signal, and the third induced electrical signal. The edge of the transmitting coil is rectangular, and a first symmetry region, a second symmetry region, a first symmetry region, and a second symmetry region are arranged sequentially along the four sides of the rectangle. The two first symmetry regions are symmetrical about the first center line, and the two second symmetry regions are symmetrical about the fourth center line. In the same first symmetrical region, the magnetic flux in the region enclosed by a portion of the third coil and the third center line is equal to the magnetic flux in the region enclosed by the other portion of the third coil and the third center line. The two portions of the third coil are located on both sides of the third center line, and the third center line is parallel to the first center line. In the same second symmetrical region, the magnetic flux in the region enclosed by a portion of the third coil and the fourth center line is equal to the magnetic flux in the region enclosed by the other portion of the third coil and the fourth center line. The two portions of the third coil are located on both sides of the fourth center line, which is perpendicular to the first center line.

2. The foreign object detection device according to claim 1, characterized in that, The transmitting coil is a DD type coil.

3. The foreign object detection device according to claim 1, characterized in that, The control module includes: A signal receiving unit is connected to the first detection unit and the second detection unit respectively, and is used to acquire each of the first induced electrical signal, the second induced electrical signal and the third induced electrical signal respectively; A signal processing unit, connected to the signal receiving unit, is used to determine whether there are foreign objects within the coupling range of the transmitting coil based on the amplitude of each of the first induced electrical signal, the amplitude of the second induced electrical signal, the amplitude of the third induced electrical signal, a first preset threshold, a second preset threshold, and a third preset threshold.

4. The foreign object detection device according to claim 3, characterized in that, The signal processing unit is used to add the amplitudes of the first induced electrical signals output by any two adjacent first coils according to a preset ratio to generate a processed value, and compare the processed value with the first preset threshold.

5. The foreign object detection device according to claim 4, characterized in that, The signal processing unit is further configured to determine that there are no foreign objects within the coupling range of the transmitting coil when all the processed values ​​are less than or equal to the first preset threshold, the amplitude of the second induced electrical signal is less than or equal to the second preset threshold, and the amplitude of the third induced electrical signal is less than or equal to the third preset threshold; and / or When any of the processed values ​​is greater than the first preset threshold, or the amplitude of the second induced electrical signal is greater than the second preset threshold, or the amplitude of the third induced electrical signal is greater than the third preset threshold, it is determined that there is a foreign object within the coupling range of the transmitting coil.

6. A method for detecting foreign objects, characterized in that, The method, applied to the foreign object detection device as described in any one of claims 1 to 5, comprises: When the receiving coil is not within the coupling range of the transmitting coil, the drive control module acquires multiple first induced electrical signals; When the control module determines that there are no foreign objects within the coupling range of the transmitting coil based on each of the first induced electrical signals, it issues an entry command; the entry command is used to instruct the vehicle to be charged to enter so that the receiving coil of the vehicle to be charged is within the coupling range of the transmitting coil.

7. The foreign object detection method according to claim 6, characterized in that, The method further includes: The control module is driven to acquire the second and third induced electrical signals; When the control module determines that there is a foreign object within the coupling range of the transmitting coil based on each of the first induced electrical signals or any two adjacent first induced electrical signals, the second induced electrical signals, or the third induced electrical signals, it controls the transmitting coil to stop transmitting signals.

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