Foreign matter detection device and foreign matter detection method

Abstract

This application relates to a foreign object detection device and a foreign object detection method, comprising: a first detection unit parallel to a transmitting coil, disposed within the coupling range of the transmitting coil, for generating a first induced electrical signal set based on the excitation magnetic field provided by the transmitting coil, the first induced electrical signal set including multiple pairs of first induced signals and a pair of second induced signals; a control module connected to the first detection unit, for determining whether a foreign object exists within the coupling range of the transmitting coil based on the first induced electrical signal set; the first detection unit includes a first detection coil group and a second detection coil group, the first centerline of the second detection coil group coincides with the second centerline of the transmitting coil, the first detection coil group is symmetrical about the first centerline, the first detection coil group is used to generate multiple pairs of first induced signals, and the second detection coil group is used to generate a pair of second induced signals to compensate for the magnetic field detection blind zone of the first detection coil group and improve detection sensitivity and reliability.

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] With the continuous depletion of fossil fuels and the increasing severity of environmental pollution, the new energy vehicle industry has received strong support and is in a stage of rapid development. Wireless charging for electric vehicles has advantages such as safety, convenience, and automation, and has become a hot topic in charging technology research and development. However, during the wireless charging process, there is a strong alternating magnetic field between the primary and secondary coils. If there are metallic foreign objects on the surface of the primary coil on the ground side, these foreign objects will induce eddy currents, resulting in significant power loss and causing the temperature of the foreign objects to rise, which may even lead to a fire in severe cases. However, current foreign object detection devices for wireless charging systems have many areas where foreign objects cannot be detected, which can easily cause safety hazards. Summary of the Invention

[0003] Therefore, it is necessary to provide a foreign object detection device and method to address the problem of multiple detection blind spots in existing foreign object detection devices.

[0004] To achieve the above objectives, this application provides a foreign object detection device, comprising:

[0005] The first detection unit is located within the coupling range of the transmitting coil and is parallel to the transmitting coil. The first detection unit is used to generate a first set of induced electrical signals based on the excitation magnetic field provided by the transmitting coil. The first set of induced electrical signals includes multiple pairs of first induced signals and a pair of second induced signals.

[0006] A control module, connected to the first detection unit, is used to determine whether there are foreign objects within the coupling range of the transmitting coil based on the first set of induced electrical signals.

[0007] The first detection unit includes a first detection coil group and a second detection coil group. The first center line of the second detection coil group coincides with the second center line of the transmitting coil. The first detection coil group is symmetrical with respect to the first center line. The first detection coil group is used to generate multiple pairs of the first induction signals, and the second detection coil group is used to generate a pair of the second induction signals to compensate for the magnetic field detection blind zone of the first detection coil group.

[0008] In one embodiment, the first detection coil group includes multiple pairs of first coils, each pair of first coils being symmetrical with respect to the first center line, and the multiple first coils located on the same side of the first center line being evenly spaced.

[0009] Each of the first coils is used to output the corresponding first induction signal.

[0010] In one embodiment, the second detection coil group is centrally symmetrically distributed.

[0011] In one embodiment, the second detection coil group is divided into a symmetrical region and a central region, wherein the symmetrical region is centrally symmetrical about the center of the central region;

[0012] The number of symmetrical regions is multiple pairs. In the same symmetrical region, the area enclosed by the second detection coil group located to the left of the first center line and the first center line is equal to the area enclosed by the second detection coil group located to the right of the first center line and the first center line.

[0013] In one embodiment, the second detection coil group located in the first symmetry region has a multi-turn coil structure, the first symmetry region being the outermost symmetry region in a first direction, the first direction being along the centerline direction of the transmitting coil.

[0014] In one embodiment, the number of symmetrical regions is two pairs;

[0015] The second detection coil group located in the second symmetrical region has a serpentine structure extending along the first direction;

[0016] The second detection coil group located in the central area has a serpentine structure extending along a second direction;

[0017] Wherein, the second direction is perpendicular to the first direction, and the second symmetrical region is the symmetrical region between the first symmetrical region and the central region.

[0018] In one embodiment, the second detection coil group includes a pair of second coils, each of which is used to output a corresponding second sensing signal.

[0019] In one embodiment, the foreign object detection device further includes:

[0020] The second detection unit has its center offset from the center of the first detection unit. The second detection unit is used to generate a second induced electrical signal to compensate for the magnetic field detection blind zone of the first detection unit.

[0021] The control module is also connected to the second detection unit and is used to determine whether there are foreign objects within the coupling range of the transmitting coil based on the first set of induced electrical signals and the second set of induced electrical signals.

[0022] In one embodiment, the second detection unit includes a rectangular coil.

[0023] In one embodiment, the control module includes:

[0024] 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 sensing signals, each of the second sensing signals and the second sensing electrical signals respectively;

[0025] 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 sensing signals, the amplitude of each of the second sensing signals, the amplitude of the second sensing electrical signal, a first preset threshold, and a second preset threshold.

[0026] In one embodiment, the signal processing unit is configured to determine that there are no foreign objects within the coupling range of the transmitting coil when the amplitude difference between each pair of the first sensing signals is less than or equal to the first preset threshold, the amplitude difference between two second sensing signals is less than or equal to the first preset threshold, and the amplitude of the second sensing electrical signal is less than or equal to the second preset threshold; and / or

[0027] When the difference in amplitude of any pair of the first sensing signals is greater than the first preset threshold, or the difference in amplitude of two second sensing signals is greater than the second preset threshold, or the amplitude of the second sensing electrical signal is greater than the second preset threshold, it is determined that there is a foreign object within the coupling range of the transmitting coil.

[0028] This application provides a foreign object detection method, applied to the foreign object detection device described above, the method comprising:

[0029] When the receiving coil is not within the coupling range of the transmitting coil, the drive control module acquires the first set of induced electrical signals;

[0030] When the control module determines that there are no foreign objects within the coupling range of the transmitting coil based on the first set of 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.

[0031] In one embodiment, when the foreign object detection device includes a second detection unit, before acquiring the first set of induced electrical signals, the method further includes:

[0032] The drive control module acquires the second induced electrical signal;

[0033] When the control module determines that there is a foreign object within the coupling range of the transmitting coil based on the first set of induced electrical signals or the second set of induced electrical signals, it controls the transmitting coil to stop transmitting signals.

[0034] The aforementioned foreign object detection device, by setting a first detection unit, can detect foreign object intrusion in the entire area except for the center of the transmitting coil. The second detection coil group of the first detection unit is used to eliminate the detection blind zone of the first detection coil group. In addition to solving the detection blind zone that occurs in the metal foreign object detection device of the wireless charging system during operation, it can improve the detection sensitivity without affecting the performance of the wireless charging system itself. Attached Figure Description

[0035] 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.

[0036] Figure 1 This is one of the schematic diagrams of a foreign object detection device provided in one embodiment;

[0037] Figure 2 This is a schematic diagram of the structure of the first detection unit provided in one embodiment;

[0038] Figure 3 This is one of the structural schematic diagrams of the second detection coil group provided in one embodiment;

[0039] Figure 4 This is a schematic diagram of the structure of the second detection coil group located in the first symmetry region according to one embodiment;

[0040] Figure 5 This is a second schematic diagram of the structure of the second detection coil group provided in one embodiment;

[0041] Figure 6 This is a schematic diagram of the structure of the second detection unit provided in one embodiment;

[0042] Figure 7 This is a schematic diagram of the structure of the first detection unit and the second detection unit combined in one embodiment;

[0043] Figure 8 This is a second schematic diagram of the foreign object detection device provided in one embodiment;

[0044] Figure 9 This is the third schematic diagram of the foreign object detection device provided in one embodiment;

[0045] Figure 10 This is one of the flowcharts illustrating a foreign object detection method provided in one embodiment;

[0046] Figure 11 This is a second schematic flowchart of a foreign object detection method provided in one embodiment.

[0047] Explanation of reference numerals in the attached figures:

[0048] First detection unit: 10; Control module: 20; Second detection unit: 30; First detection coil group: 101; Second detection coil group: 102; Signal receiving unit: 201; Signal processing unit: 202. Detailed Implementation

[0049] 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 thorough and complete.

[0050] 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.

[0051] 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.

[0052] Traditional wired charging methods present numerous problems when used in electrical devices such as electric vehicles, mobile robots, and drones. For example, physical contact charging via plugs and wires can cause mechanical wear and arcing due to frequent plugging and unplugging. Furthermore, charging in open-air environments is unsuitable for harsh weather conditions such as rain and snow. Therefore, wireless power transfer technology, by eliminating the need for physical electrical contact via wires, transmits electrical energy wirelessly, offering a safe, reliable, and highly efficient solution to these problems associated with wired charging.

[0053] While wireless charging offers unique advantages over traditional power supply methods, several issues hinder its widespread adoption. Foreign object detection (FOD) is a critical factor affecting its development. Specifically, wireless charging typically employs strong coupling between transmitting and receiving coils. A strong alternating magnetic field exists in the energy transmission region between these coils. If a metallic foreign object enters this region, internal currents will circulate within it. Due to the eddy current effect, its surface temperature will rise rapidly. This not only affects energy transmission efficiency but, if it encounters flammable materials such as plastics or paper, can ignite a fire, posing a significant safety hazard. Therefore, FOD detection is essential for wireless charging systems to ensure their efficient and safe operation.

[0054] Furthermore, one of the main commercial solutions for wireless charging coils currently is the use of DD-type coils, which consist of two rectangular coils with parallel circuits and series magnetic circuits. This overcomes the shortcomings of traditional circular coils and fluxtube coils, such as low coupling coefficients and poor resistance to horizontal offset, while also possessing advantages such as high magnetic flux path, unipolar magnetic field, low loss, and low leakage. However, foreign object detection devices specifically designed for DD-type coil-based wireless charging systems are extremely rare on the market. Moreover, research has found that when existing foreign object detection devices for rectangular or circular coil-based wireless charging systems are applied to DD-type coil-based systems, multiple areas where foreign objects cannot be detected exist, which can easily lead to safety hazards.

[0055] Therefore, this application provides a foreign object detection device to solve the above problems. Please refer to [link / reference]. Figure 1 The foreign object detection device includes a first detection unit 10 and a control module 20.

[0056] This embodiment uses the application of a foreign object detection device in an electric vehicle as an example for explanation. Specifically, the wireless system of the electric vehicle includes a transmitter and a receiver. The transmitter includes a transmitting coil and a transmitter control circuit, and 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 is parallel to the ground. When the electric vehicle drives in, causing the receiving coil to align with or slightly offset from the transmitting coil, the transmitter control circuit converts the power frequency AC to high frequency AC. After compensation, the high frequency AC is converted into magnetic energy by the primary transmitting coil, generating a high frequency magnetic field between the primary and secondary coils. The secondary receiving coil induces the high frequency magnetic field and converts it back into high frequency AC. The receiver control circuit then converts this back into DC for charging the electric vehicle, thereby achieving contactless power transmission.

[0057] The first detection unit 10 in the foreign object detection device is located within the coupling range of the transmitting coil and is parallel to the transmitting coil. The first detection unit 10 is used to generate a first set of induced electrical signals according to the excitation magnetic field provided by the transmitting coil. The first set of induced electrical signals includes multiple pairs of first induced signals and a pair of second induced signals.

[0058] Specifically, the first detection unit 10 covers the entire surface of the transmitting coil to generate a first set of induced electrical signals, wherein the induced electrical signals include induced voltage signals and induced current signals. Optionally, in this embodiment, the first detection unit 10 collects a first set of induced voltage signals over the entire area of ​​the transmitting coil, that is, it collects multiple pairs of first induced voltage signals and a pair of second induced voltage signals, and uses the first set of induced voltage signals as a criterion for the presence or absence of foreign objects.

[0059] Furthermore, the first detection unit 10 includes a first detection coil group 101 and a second detection coil group 102. The first centerline of the second detection coil group 102 coincides with the second centerline of the transmitting coil. The first detection coil group 101 is symmetrical with respect to the first centerline. The first detection coil group 101 is used to generate multiple pairs of first induction signals, and the second detection coil group 102 is used to generate a pair of second induction signals to compensate for the magnetic field detection blind zone of the first detection coil group 101. The control module 20 is connected to the first detection unit 10 and is used to determine whether there are foreign objects within the coupling range of the transmitting coil based on the first set of induction electrical signals.

[0060] Since the first detection coil group 101 has an axisymmetric structure on the surface of the transmitting coil, when there are no foreign objects in the coupling range of the transmitting coil, the difference in amplitude of a pair of first induction signals generated at symmetrical positions in the first detection coil group 101 should be 0 or within a preset range. However, when a foreign object intrudes, the foreign object affects the distribution of the magnetic field, which in turn causes the difference in amplitude of at least a pair of first induction signals to change. Therefore, the control module 20 can determine whether there is a foreign object by detecting the difference in amplitude of each pair of first induction signals in the first detection coil group 101.

[0061] However, when the foreign object is located on the central axis of the transmitting coil, i.e., symmetrical about the second centerline, the foreign object fails to disrupt the voltage balance of the first detection coil group 101, and the difference in amplitude between each pair of first sensing signals remains unchanged. Therefore, the first detection coil group 101 cannot identify whether a foreign object has intruded. In this case, the pairs of first sensing signals cannot be used as criteria for determining the presence or absence of a foreign object, resulting in a central axis detection blind zone in the first detection unit 10. Therefore, by adding a second detection coil group 102 to the first detection unit 10 to reduce the detection blind zone area, the control module 20 can detect whether the difference in amplitude between a pair of second sensing signals of the second detection coil group 102 is 0 or within a preset range. If it is not 0 or exceeds the preset range, it is determined that a foreign object exists within the coupling range of the transmitting coil, thereby achieving full-area foreign object detection of the transmitting coil.

[0062] In the above example, by setting the first detection unit 10, the intrusion of foreign objects in the entire area except for the center of the transmitting coil can be detected. The second detection coil group 102 of the first detection unit 10 is used to eliminate the detection blind zone of the first detection coil group 101, filling a technical gap. On the basis of solving the detection blind zone that occurs in the operation of the metal foreign object detection device of the wireless charging system, it can improve the detection sensitivity and accuracy, and has a simple structure, high reliability, and does not affect the performance of the wireless charging system itself.

[0063] In one embodiment, such as Figure 2 As shown, Figure 2 The diagram below shows the structure of the first detection unit 10 provided in one embodiment. The first detection coil group 101 includes multiple pairs of first coils. Each pair of first coils is symmetrical with respect to the first center line. Multiple first coils located on the same side of the first center line are evenly spaced. Each first coil is used to output the corresponding first sensing signal.

[0064] It can be understood that in this embodiment, the first centerline is denoted as the Y-axis direction, and the direction perpendicular to the first centerline is denoted as the X-axis direction. The first detection coil group 101 includes multiple first coils arrayed along the X-axis direction, and the first coils symmetrical with respect to the Y-axis direction form a pair, respectively denoted as a1 and b1, a2 and b2, a3 and b3, ..., a n-1 With b n-1 There are (n-1) pairs of first coils that are symmetrical about the Y-axis, and each pair contains the same number of coil units. The shape of the first coil can be circular, rectangular, or other polygonal. Since rectangular coils can be arranged closely due to their geometric features, which can effectively reduce the area ratio of the detection blind zone, the shape of the first coil is preferably rectangular in this application.

[0065] Furthermore, the first detection coil group 101 uses two first coils symmetrically placed to form a balanced coil to detect foreign objects. This embodiment uses a pair of first coils a1 and b1 as an example for explanation. Due to the symmetry of the magnetic field of the transmitting coil, when no foreign object intrudes into the wireless charging system, the amplitude of the first induction signal output by the first coils a1 and b1 is the same. That is, under ideal conditions, the difference in amplitude of the first induction signal between the two first coils a1 and b1 is 0. If a foreign object intrudes into the range of the first coil a1, the foreign object will affect the magnetic flux passing through a1, causing the amplitude of the first induction signal output by a1 to change, but the amplitude of the first induction signal output by b1 does not change. At this time, the difference in amplitude of the first induction signal of the first coils a1 and b1 is no longer 0. Therefore, the presence of foreign object intrusion is determined by comparing the first induction signals output by the first coils a1 and b1 respectively. Similarly, when the difference in amplitude of the first induction signal of a certain pair of first coils changes, it can be determined that there is a foreign object within the coupling range of the transmitting coil.

[0066] In one embodiment, the second detection coil group 102 is centrally symmetrically distributed. Please refer to [reference needed]. Figure 2 The second detection coil group 102 has a centrally symmetrical structure, which can effectively eliminate the central axis detection blind zone other than the center point caused by the first detection coil group 101 using an axisymmetric structure.

[0067] In one embodiment, the second detection coil group 102 includes a pair of second coils, each of which is used to output a corresponding second sensing signal.

[0068] Specifically, the second coil, whose input terminal is located on the left side in the Y-axis direction, is denoted as a. n The second coil, whose input terminal is located on the right side of the Y-axis, is denoted as b. n When there are no foreign objects, the two second coils a n b n The amplitude difference of the corresponding output second induction signal should be 0 or within a preset range. When a foreign object enters the central axis area of ​​the transmitting coil, the two second coils a n b n The difference in amplitude of the corresponding output second sensing signal will change; therefore, the control module detects the difference between the two second coils a. n b n The difference in amplitude of the output second sensing signal can be used to determine whether a foreign object has invaded the central axis region.

[0069] In one embodiment, the second detection coil group 102 is divided into a symmetrical region and a central region, and the symmetrical regions are centrally symmetrical about the center of the central region; wherein, there are multiple pairs of symmetrical regions, and in the same symmetrical region, the area enclosed by the second detection coil group 102 located to the left of the first center line and the first center line is equal to the area enclosed by the second detection coil group 102 located to the right of the first center line and the first center line.

[0070] The Y-axis direction is divided into a symmetrical region and a central region. There can be multiple pairs of symmetrical regions. To further improve the foreign object detection sensitivity of the second detection coil group 102, the structure of the coil units in the central region and the symmetrical region can be specially modulated. This embodiment does not limit the coil structure of each region. Specifically, as follows... Figure 3 As shown ( Figure 3 Taking region C as the central region and illustrating with two pairs of symmetrical regions A and B as examples, two regions B symmetrical about region C in the Y-axis direction form a pair of symmetrical regions. Similarly, two regions A form another pair of symmetrical regions. Furthermore, the coils within the same pair of symmetrical regions have the same shape arrangement. The area enclosed by a pair of symmetrical regions A or B on the left side of the Y-axis is the same as the area enclosed on the right side of the Y-axis, ensuring that, in the absence of foreign objects, the two second coils a... n b n The amplitudes of the output second sensing signals are kept consistent, that is, the difference between the amplitudes of the second sensing signals is kept to be 0 or within a preset range.

[0071] In one embodiment, such as Figure 4 As shown, the second detection coil group located in the first symmetry region has a multi-turn coil structure. The first symmetry region is the outermost symmetry region in the first direction, which is along the centerline of the transmitting coil.

[0072] It is understandable that, due to the weak magnetic induction intensity in the edge region of the transmitting coil, to prevent the outermost part of the second detection coil group in the first direction (Y-axis direction) from becoming a foreign object detection blind zone, the first symmetrical region in the Y-axis direction is designed as a multi-turn coil structure. This structure can enhance the foreign object detection sensitivity of the first symmetrical region. In addition, the coil in the aforementioned first symmetrical region is not symmetrical about the Y-axis. This asymmetrical structure can prevent the positive and negative magnetic fluxes passing through the first symmetrical region from canceling each other out, and further prevent the occurrence of no voltage reading.

[0073] In one embodiment, such as Figure 5 As shown, there are two pairs of symmetrical regions. The second detection coil group located in the second symmetrical region has a serpentine structure extending along the first direction; the second detection coil group located in the central region has a serpentine structure extending along the second direction; wherein, the second direction is perpendicular to the first direction, and the second symmetrical region is the symmetrical region between the first symmetrical region and the central region.

[0074] Furthermore, when the second detection coil group is configured with two pairs of symmetrical regions, one pair is the outermost first symmetrical region A, and the other pair is the second symmetrical region B located between the first symmetrical region A and the central region C. To enhance the detection sensitivity of the second detection coil group, the structures of the central region C and the second symmetrical region B are specially modulated. Specifically, the central region C has multiple C-shaped coil structures arranged alternately along the X-axis direction (second direction), and the second symmetrical region B has multiple C-shaped coil structures arranged alternately along the Y-axis direction (first direction). Figure 5 (Taking the central region C as an example with four alternating C-type coil structures and the second symmetrical region B with three alternating C-type coil structures as an example), and the size of a single C-type coil structure in the second symmetrical region B is different from that of a single C-type coil structure in the central region C, thereby enhancing the foreign object detection sensitivity of the central region C and the second symmetrical region B.

[0075] In one embodiment, in conjunction with reference Figure 6 and Figure 7 ( Figure 7 (Taking the first detection unit 10 containing seven pairs of first coils as an example for illustration), the foreign object detection device also includes a second detection unit 30. The center of the second detection unit 30 is offset from the center of the first detection unit 10. The second detection unit 30 is used to generate a second induced electrical signal to compensate for the magnetic field detection blind zone of the first detection unit 10; wherein, as... Figure 8 As shown, the control module 20 is also connected to the second detection unit 30, and is used to determine whether there are foreign objects within the coupling range of the transmitting coil based on the first set of induced electrical signals and the second set of induced electrical signals.

[0076] Specifically, because the second detection coil group 102 has a centrally symmetrical structure, the first detection unit 10 has a detection blind zone at the center point. Therefore, a second detection unit 30 is set on one side of the center position of the first detection unit 10 to eliminate the center point detection blind zone. Compared with the technology of using two layers of large-sized detection coils arranged in an alternating manner, the technology provided in this application, which uses one first detection unit 10 and one small-sized second detection unit 30 close to the center position, can not only greatly reduce the area ratio of the detection blind zone, but also reduce costs and improve detection sensitivity. 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 close 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 restrict this order.

[0077] Furthermore, Figure 8Taking seven pairs of first coils as an example, the control module 20 acquires the first induction signal output by each first coil, the second induction signal output by each second coil, and the second induction electrical signal output by the second detection unit 30, and determines whether there is foreign object intrusion based on the above signals.

[0078] In one embodiment, the second detection unit 30 includes a rectangular coil. It is understood that the rectangular second detection unit 30, for the same size, has a larger blind zone detection area than structures of other shapes.

[0079] In one embodiment, such as Figure 9 As 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, and is used to acquire each of the first sensing signals, each of the second sensing signals and the second sensing electrical signal. The signal processing unit 202 is connected to the signal receiving unit 201 and 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 sensing signals, the amplitude of each of the second sensing signals, the amplitude of the second sensing electrical signal, a first preset threshold and a second preset threshold.

[0080] Specifically, the signal receiving unit 201 is connected to each first coil and each second coil in the first detection unit 10, and receives the first induction signal output by each first coil and the second induction signal output by each second coil. At the same time, the signal receiving unit 201 is also connected to the rectangular coil in the second detection unit 30, and receives the second induction electrical signal output by the rectangular coil.

[0081] 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 detection unit 30 with a second preset threshold. If the former exceeds the latter, it is determined that there is foreign object intrusion in the wireless charging system; otherwise, the detection continues. The signal processing unit 202 subtracts the amplitudes of the two first induced signals output by a pair of first coils in the first detection unit 10 and compares the resulting difference with the first preset threshold. If the former exceeds the latter, it is determined that there is foreign object intrusion in the wireless charging system; otherwise, it continues to detect other pairs of first coils until the difference in amplitude of the first induced signals output by each pair of first coils does not exceed the first preset threshold. If the detection based on the second detection unit 30 indicates that there is no foreign object intrusion, it can be determined that there is no foreign object intrusion in the wireless charging system.

[0082] In one embodiment, the signal processing unit 202 is used to determine that there are no foreign objects within the coupling range of the transmitting coil when the difference in amplitude of each pair of first sensing signals is less than or equal to a first preset threshold, the difference in amplitude of two second sensing signals is less than or equal to the first preset threshold, and the amplitude of the second sensing electrical signal is less than or equal to a second preset threshold.

[0083] It can be understood that the signal processing unit 202 obtains the difference in amplitude between the amplitude of each pair of first sensing signals and the amplitude of a pair of second sensing signals output by the first detection unit 10 based on formula (1).

[0084] - - -(1)

[0085] in, Let be the absolute value of the amplitude difference between the i-th pair of induced signals. For the first coil or the second coil The amplitude of the induced signal obtained in the signal processing unit 202 after output. For the first coil or the second coil The amplitude of the induced signal is obtained in the signal processing unit 202 after output.

[0086] When the amplitude difference of the induced signal output by each pair of coils in the first detection unit 10 is within the first preset threshold range, and the amplitude of the second induced electrical signal output by the second detection unit 30 is within the second preset threshold range, it indicates that no foreign object has entered the transmitting coil.

[0087] In one embodiment, when the difference in amplitude of any pair of first sensing signals is greater than a first preset threshold, or the difference in amplitude of two second sensing signals is greater than a second preset threshold, or the amplitude of a second sensing electrical signal is greater than a second preset threshold, it is determined that there is a foreign object within the coupling range of the transmitting coil.

[0088] If the amplitude difference of the induced signal output by at least one pair of coils in the first detection unit 10 exceeds the first preset threshold range, or the amplitude of the second induced electrical signal output by the second detection unit 30 exceeds the second preset threshold range, it indicates that a foreign object has entered the transmitting coil.

[0089] 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 induced signal, the second induced signal, and the second induced electrical signal received by the signal processing unit 202 are first sent to the sampling resistor, which has a very high resistance, typically 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 exists.

[0090] This application also provides a foreign object detection method, applied to the foreign object detection device described above, the method comprising steps S300 and S400, as follows:

[0091] Step S300: When the receiving coil is not within the coupling range of the transmitting coil, the drive control module acquires the first set of induced electrical signals.

[0092] When an electric vehicle is about to enter the charging station, foreign object detection of the wireless charging system is required before charging. At this time, the system will automatically place the pre-prepared first and second preset thresholds in the signal processing module and perform no-load foreign object detection. The signal receiving unit in the control module acquires the first induction signal output by each first coil and the second induction signal output by each second coil in the first detection unit and transmits them to the signal processing unit.

[0093] Step S400: When the control module determines that there are no foreign objects within the coupling range of the transmitting coil based on the first set of 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.

[0094] The signal processing unit in the control module compares the difference between the threshold values ​​of the first induction signals output by each pair of first coils with a first preset threshold, and also compares the difference between the threshold values ​​of the second induction signals output by each pair of second coils with the first preset threshold. If the differences do not exceed the first preset threshold, there are no foreign objects within the coupling range of the transmitting coil, and an entry command is issued, allowing the electric vehicle to drive into the charging station for normal charging. During charging, routine foreign object detection under rated load continues to prevent foreign object intrusion. If any difference exceeds the first preset threshold, there are foreign objects within the coupling range of the transmitting coil. In this case, the transmitting coil must 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 S300 is repeated.

[0095] In one embodiment, when the foreign object detection device includes a second detection unit, the following steps are included before step S300 acquires the first set of induced electrical signals:

[0096] Step S100: The drive control module acquires the second induced electrical signal.

[0097] When the foreign object detection device includes a second detection unit, the signal receiving unit of the control module will also acquire the second induced electrical signal output by the rectangular coil of the second detection unit and transmit it to the signal processing unit.

[0098] Step S200: When the control module determines that there is a foreign object within the coupling range of the transmitting coil based on the first set of induced electrical signals or the second set of induced electrical signals, it controls the transmitting coil to stop transmitting signals.

[0099] The signal processing unit compares the amplitude of the second induced electrical signal with a second preset threshold. If the former does not exceed the latter, the process proceeds to steps S300 and S400. If the former exceeds the latter, there is a foreign object 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, the process repeats steps S300 and S400.

[0100] In one embodiment, such as Figure 11 As shown, a flowchart of a foreign object detection method is provided, wherein the method includes steps S10, S20, S30, S40, S50 and S60.

[0101] Step S10: Before the electric vehicle enters, the wireless system is initialized, and the first preset threshold and the second preset threshold are set in the signal processing module to perform no-load detection.

[0102] Step S20: The signal receiving unit acquires the second induced electrical signal output by the second detection unit and transmits it to the signal processing unit.

[0103] Step S30: The signal processing unit determines whether the amplitude of the second induced electrical signal is greater than the second preset threshold. If so, the transmitting coil stops working and issues an alarm signal to prompt the removal of foreign objects.

[0104] Step S40: The signal receiving unit acquires the first induction signal output by each first coil and the second induction signal output by each second coil in the first detection unit, and transmits them to the signal processing unit.

[0105] Step S50: The signal processing unit determines whether the threshold difference of the first induction signal output by each pair of first coils and the threshold difference of the second induction signal output by each pair of second coils are both less than the first preset threshold. If not, the transmitting coil stops working and issues an alarm signal to prompt the removal of foreign objects.

[0106] Step S60: Issue a driving command, and the electric vehicle drives into the charging station for normal charging.

[0107] 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.

[0108] It should be understood that, although Figure 10 and Figure 11 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 10 and Figure 11 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.

[0109] 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.

[0110] 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.

[0111] 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 is located within the coupling range of the transmitting coil, covering the entire surface of the transmitting coil and parallel to the transmitting coil. The first detection unit is used to generate a first set of induced electrical signals based on the excitation magnetic field provided by the transmitting coil. The first set of induced electrical signals includes multiple pairs of first induced signals and a pair of second induced signals. A control module, connected to the first detection unit, is used to determine whether there are foreign objects within the coupling range of the transmitting coil based on the first set of induced electrical signals. The first detection unit includes a first detection coil group and a second detection coil group. The first center line of the second detection coil group coincides with the second center line of the transmitting coil. The first detection coil group is symmetrical with respect to the first center line. The first detection coil group is used to generate multiple pairs of the first induction signals, and the second detection coil group is used to generate a pair of the second induction signals to compensate for the magnetic field detection blind zone of the first detection coil group.

2. The foreign object detection device according to claim 1, characterized in that, The first detection coil group includes multiple pairs of first coils, each pair of first coils being symmetrical with respect to the first center line, and multiple first coils located on the same side of the first center line being evenly spaced. Each of the first coils is used to output the corresponding first induction signal.

3. The foreign object detection device according to claim 1, characterized in that, The second detection coil group is centrally symmetrically distributed.

4. The foreign object detection device according to claim 3, characterized in that, The second detection coil group is divided into a symmetrical region and a central region, wherein the symmetrical region is centrally symmetrical about the center of the central region; The number of symmetrical regions is multiple pairs. In the same symmetrical region, the area enclosed by the second detection coil group located to the left of the first center line and the first center line is equal to the area enclosed by the second detection coil group located to the right of the first center line and the first center line.

5. The foreign object detection device according to claim 4, characterized in that, The second detection coil group located in the first symmetry region has a multi-turn coil structure. The first symmetry region is the outermost symmetry region in a first direction, which is along the centerline of the transmitting coil.

6. The foreign object detection device according to claim 5, characterized in that, The number of symmetrical regions is two pairs; The second detection coil group located in the second symmetrical region has a serpentine structure extending along the first direction; The second detection coil group located in the central area has a serpentine structure extending along a second direction; Wherein, the second direction is perpendicular to the first direction, and the second symmetrical region is the symmetrical region between the first symmetrical region and the central region.

7. The foreign object detection device according to any one of claims 3 to 6, characterized in that, The second detection coil group includes a pair of second coils, each of which is used to output a corresponding second sensing signal.

8. The foreign object detection device according to any one of claims 1 to 6, characterized in that, Also includes: The second detection unit has its center offset from the center of the first detection unit. The second detection unit is used to generate a second induced electrical signal to compensate for the magnetic field detection blind zone of the first detection unit. The control module is also connected to the second detection unit and is used to determine whether there are foreign objects within the coupling range of the transmitting coil based on the first set of induced electrical signals and the second set of induced electrical signals.

9. The foreign object detection device according to claim 8, characterized in that, The second detection unit includes a rectangular coil.

10. The foreign object detection device according to claim 8, 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 sensing signals, each of the second sensing signals and the second sensing electrical signals 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 sensing signals, the amplitude of each of the second sensing signals, the amplitude of the second sensing electrical signal, a first preset threshold, and a second preset threshold.

11. The foreign object detection device according to claim 10, characterized in that, The signal processing unit is configured to determine that there are no foreign objects within the coupling range of the transmitting coil when the amplitude difference between each pair of the first sensing signals is less than or equal to the first preset threshold, the amplitude difference between two second sensing signals is less than or equal to the first preset threshold, and the amplitude of the second sensing electrical signal is less than or equal to the second preset threshold; and / or When the difference in amplitude of any pair of the first sensing signals is greater than the first preset threshold, or the difference in amplitude of two second sensing signals is greater than the second preset threshold, or the amplitude of the second sensing electrical signal is greater than the second preset threshold, it is determined that there is a foreign object within the coupling range of the transmitting coil.

12. 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 11, comprises: When the receiving coil is not within the coupling range of the transmitting coil, the drive control module acquires the first set of induced electrical signals; When the control module determines that there are no foreign objects within the coupling range of the transmitting coil based on the first set of 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.

13. The foreign object detection method according to claim 12, characterized in that, When the foreign object detection device includes a second detection unit, before acquiring the first set of induced electrical signals, the method further includes: The drive control module acquires the second induced electrical signal; When the control module determines that there is a foreign object within the coupling range of the transmitting coil based on the first set of induced electrical signals or the second set of induced electrical signals, it controls the transmitting coil to stop transmitting signals.

Images