CN115800565A - Foreign matter detection device and foreign matter detection method - Google Patents

Abstract

The present application relates to a foreign matter detection device and a foreign matter detection method, including: the first detection unit is arranged in the coupling range of the transmitting coil and used for generating a first induction signal set according to the excitation magnetic field provided by the transmitting coil, and the first induction signal set comprises a plurality of pairs of first induction signals and a pair of second induction signals; the control module is connected with the first detection unit and used for judging whether foreign matters exist in the coupling range of the transmitting coil according to the first induction electric signal set; the first detection unit comprises a first detection coil group and a second detection coil group, a first central line of the second detection coil group is coincided with a second central line of the emission coil, the first detection coil group is symmetrical relative to the first central line, the first detection coil group is used for generating a plurality of pairs of first induction signals, and the second detection coil group is used for generating a pair of second induction signals so as to make up a magnetic field detection blind area of the first detection coil group and improve detection sensitivity and reliability.

Description

Foreign matter detection device and foreign matter detection method

technical field

The present application relates to the technical field of wireless charging, in particular to a foreign object detection device and a foreign object detection method.

Background technique

With the continuous consumption of fossil energy and the aggravation of environmental pollution, the new energy automobile industry has received strong support and is in a stage of rapid development. Wireless charging of electric vehicles has the advantages of safety, convenience and automation, and has become a hot spot in the research and development of charging technology. However, due to the strong alternating magnetic field between the primary coil and the secondary coil during wireless charging, if there is a metal foreign object on the surface of the primary coil on the ground side, the metal foreign object will generate an induced eddy current and form a large power In addition, the temperature of the foreign matter will rise, and it will cause a fire in severe cases. However, there are many foreign matter detection devices in the market for wireless charging systems that cannot be detected, which can easily cause safety hazards.

Contents of the invention

Based on this, it is necessary to provide a foreign object detection device and a foreign object detection method to solve the problem of multiple detection blind spots in the foreign object detection device in the prior art.

In order to achieve the above purpose, the present application provides a foreign object detection device, including:

The first detection unit is arranged within the coupling range of the transmitting coil and is parallel to the transmitting coil, the first detecting unit is used to generate a first induction electrical signal set according to the excitation magnetic field provided by the transmitting coil, and the The first induction electrical signal set includes multiple pairs of first induction signals and a pair of second induction signals;

A control module, connected to the first detection unit, for judging whether there is a foreign object within the coupling range of the transmitting coil according to the first induction electrical signal set;

Wherein, 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, and the first detection coil group Symmetrical with respect to the first neutral 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 Describe the blind area of the magnetic field detection of the first detection coil group.

In one of the embodiments, the first detection coil group includes multiple pairs of first coils, each pair of first coils is symmetrical with respect to the first midline, and the multiple pairs located on the same side of the first midline The first coils are evenly spaced;

Wherein, each of the first coils is respectively used to output corresponding first induction signals.

In one of the embodiments, the second detection coil group is symmetrically distributed about the center.

In one of the embodiments, the second detection coil group is divided into a symmetrical area and a central area, and the symmetrical area is center-symmetrically distributed with respect to the center of the central area;

Wherein, the number of the symmetrical areas is multiple pairs, and in the same symmetrical area, the area enclosed by the second detection coil group located on the left side of the first central line and the first central line is equal to the The area enclosed by the second detection coil group on the right side of the first midline and the first midline.

In one of the embodiments, the second detection coil group located in the first symmetrical area has a multi-turn coil structure, the first symmetrical area is the outermost symmetrical area in the first direction, and the first direction is along the midline direction of the transmitting coil.

In one of the embodiments, the number of the symmetrical regions is two pairs;

The second detection coil group located in the second symmetrical area 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 the second direction;

Wherein, the second direction is perpendicular to the first direction, and the second symmetrical area is a symmetrical area between the first symmetrical area and the central area.

In one of the embodiments, the second detection coil group includes a pair of second coils, and each of the second coils is respectively used to output the corresponding second induction signals.

In one of the embodiments, the foreign object detection device further includes:

A second detection unit, the center of the second detection unit is staggered from the center of the first detection unit, and the second detection unit is used to generate a second induced electrical signal to compensate for the magnetic field of the first detection unit Detection of blind spots;

Wherein, the control module is further connected with the second detection unit, and is used for judging whether there is a foreign object within the coupling range of the transmitting coil according to the first induction electrical signal set and the second induction electrical signal.

In one of the embodiments, the second detection unit includes a rectangular coil.

In one of the embodiments, the control module includes:

A signal receiving unit, connected to the first detection unit and the second detection unit, respectively, for obtaining each of the first induction signals, each of the second induction signals and the second induction electrical signal;

A signal processing unit, connected to the signal receiving unit, configured to, according to the amplitude of each of the first induction signals, the amplitude of each of the second induction signals, the amplitude of the second induction electrical signal, the first The preset threshold and the second preset threshold determine whether there is a foreign object within the coupling range of the transmitting coil.

In one of the embodiments, the signal processing unit is configured to, when the amplitude difference of each pair of the first sensing signals is less than or equal to the first preset threshold, the two second sensing signals When the difference in amplitude is less than or equal to the first preset threshold, and the amplitude of the second induced electrical signal is less than or equal to the second preset threshold, it is determined that there is no foreign object within the coupling range of the transmitting coil; and /or

When the difference between the amplitudes of any pair of the first sensing signals is greater than the first preset threshold, or the difference between the amplitudes of two second sensing signals is greater than the second preset threshold, or the When the amplitude of the second induction 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.

The present application provides a foreign matter detection method, which is applied to the foreign matter detection device as described above, and the method includes:

When the receiving coil is not within the coupling range of the transmitting coil, the drive control module acquires the first induction electrical signal set;

When the control module judges that there is no foreign object within the coupling range of the transmitting coil according to the first induction electrical signal set, it issues a driving-in command; the driving-in command is used to instruct the car to be charged to drive in, so that all The receiving coil of the car to be charged is within the coupling range of the transmitting coil.

In one of the embodiments, when the foreign object detection device includes a second detection unit, before acquiring the first induction electrical signal set, the method further includes:

The drive control module acquires the second induction electrical signal;

When the control module determines that there is a foreign object within the coupling range of the transmitting coil according to the first induction electrical signal set or the second induction electrical signal, it controls the transmitting coil to stop transmitting signals.

The above-mentioned foreign object detection device can detect the intrusion of foreign objects in the whole area except the center of the transmitting coil by setting the first detection unit, wherein the second detection coil group of the first detection unit is used to eliminate the detection blind area of the first detection coil group, On the basis of solving the detection blind spot in the metal foreign object detection device of the wireless charging system during operation, the detection sensitivity can be improved without affecting the performance of the wireless charging system itself.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application or the conventional technology, the following will briefly introduce the accompanying drawings that need to be used in the description of the embodiments or the traditional technology. Obviously, the accompanying drawings in the following description are only the present invention For some embodiments of the application, those skilled in the art can also obtain other drawings based on these drawings without creative work.

Fig. 1 is one of the structural schematic diagrams of a foreign object detection device provided in an embodiment;

Fig. 2 is a schematic structural diagram of a first detection unit provided in an embodiment;

Fig. 3 is one of the structural schematic diagrams of the second detection coil group provided in an embodiment;

Fig. 4 is a schematic structural diagram of a second detection coil group located in the first symmetrical area provided in an embodiment;

Fig. 5 is the second structural schematic diagram of the second detection coil group provided in an embodiment;

Fig. 6 is a schematic structural diagram of a second detection unit provided in an embodiment;

Fig. 7 is a schematic structural diagram of the combination of the first detection unit and the second detection unit provided in an embodiment;

Fig. 8 is the second structural schematic diagram of the foreign object detection device provided in an embodiment;

Fig. 9 is the third schematic diagram of the structure of the foreign object detection device provided in an embodiment;

Fig. 10 is one of the schematic flow charts of the foreign object detection method provided in an embodiment;

Fig. 11 is the second schematic flow diagram of the foreign object detection method provided in an embodiment.

Explanation of reference signs:

The first detection unit: 10; the control module: 20; the second detection unit: 30; the first detection coil group: 101; the second detection coil group: 102; the signal receiving unit: 201; the signal processing unit: 202.

Detailed ways

In order to facilitate the understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. Embodiments of the application are given in the drawings. However, the present application can be embodied in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of this application more thorough and comprehensive.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this application belongs. The terms used herein in the specification of the application are only for the purpose of describing specific embodiments, and are not intended to limit the application.

When used herein, the singular forms "a", "an" and "the/the" may also include the plural forms unless the context clearly dictates otherwise. It should also be understood that the terms "comprising/comprising" or "having" etc. specify the presence of stated features, integers, steps, operations, components, parts or combinations thereof, but do not exclude the presence or addition of one or more The possibility of other features, integers, steps, operations, components, parts or combinations thereof. Meanwhile, in this specification, the term "and/or" includes any and all combinations of the related listed items.

When the traditional wired charging method is applied to electrical equipment such as electric vehicles, mobile robots, and drones, there will be many problems. For example, when using plugs and wires for physical contact charging, frequent plugging and unplugging will easily cause mechanical wear and pull. arc phenomenon, and the charging scene is in an open-air environment, it will not be able to cope with severe weather and environments such as rain and snow. Therefore, wireless power transmission technology transmits electric energy in a wireless form without physical electrical contact through wires, and solves the problems existing in the above-mentioned wired charging method with the characteristics of safety, reliability and high efficiency.

Although wireless charging has unique advantages that traditional power supply methods do not have, there are still some problems that restrict its wide application. Among them, foreign object detection is an important link that affects the development of wireless charging. Specifically, wireless charging technology generally adopts the form of strong coupling between the transmitting coil and the receiving coil. There is a strong alternating magnetic field in the energy transmission area between the two. If metal foreign objects are mixed into this area, there will be internal circulation in the metal foreign objects. , Due to the eddy current effect, the surface temperature rises sharply. At this time, it will not only affect the transmission efficiency of electric energy, but if it encounters flammable materials such as plastic and paper, it will cause a fire and cause a safety accident. There is a great safety hazard. Therefore, it is very necessary to perform foreign object detection on the wireless charging system to ensure the efficient and safe operation of the wireless charging system.

Furthermore, one of the main commercialization schemes of wireless charging coils is to use DD-type coils, which are composed of two rectangular coils with parallel circuits and magnetic circuits in series, which overcomes the low efficiency of traditional circular coils and flux tube coils. It has disadvantages such as poor coupling coefficient and poor anti-horizontal offset characteristics, but also has the advantages of high flux path, unipolar magnetic field, low loss and low leakage. However, there are very few foreign object detection devices on the market that are specially designed for wireless charging systems based on DD coils, and studies have found that when the existing foreign object detection devices for wireless charging systems based on rectangular or circular coils are applied to wireless charging systems based on DD coils When charging the system, there will be many areas where foreign objects cannot be inspected, which can easily cause safety hazards.

Therefore, the present application provides a foreign object detection device to solve the above problems, please refer to FIG. 1 , the foreign object detection device includes: a first detection unit 10 and a control module 20 .

This embodiment takes the application of the foreign matter detection device in an electric vehicle as an example for explanation. Specifically, the wireless system of the electric vehicle includes a transmitting end and a receiving end. The transmitting end includes a transmitting coil and a transmitting end control circuit. The receiving end includes a receiving coil and a receiving end. terminal control circuit. Among them, the transmitting coil is buried on the ground and has a planar design. The receiving coil is installed on the chassis of the car and is parallel to the ground. The alternating current is converted into high-frequency alternating current. After the high-frequency alternating current is compensated, the high-frequency alternating current is converted into magnetic energy by the primary transmitting coil, and a high-frequency magnetic field is generated between the primary and secondary coils. The secondary receiving coil induces the high-frequency magnetic field and converts the high-frequency magnetic field into High-frequency alternating current is converted to direct current by the control circuit at the receiving end for charging electric vehicles, thereby realizing non-contact transmission of electric energy.

The first detection unit 10 in the foreign matter detection device is arranged 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 induction electrical signal set according to the excitation magnetic field provided by the transmitting coil. A sensing electrical signal set includes multiple pairs of first sensing signals and a pair of second sensing signals.

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 signal includes an induced voltage signal and an induced current signal. Optionally, the first detection unit 10 of this embodiment By collecting the first induced voltage signal set in the entire area of the transmitting coil, that is, multiple pairs of first induced voltage signals and a pair of second induced voltage signals are collected, and the first induced voltage signal set is used as a judgment for the presence or absence of foreign objects. according to.

Further, the first detection unit 10 includes a first detection coil group 101 and a second detection coil group 102, the first center line of the second detection coil group 102 coincides with the second center line of the transmitting coil, and the first detection coil group 101 is relatively The first center line is symmetrical, 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 make up for the magnetic field detection blind area of the first detection coil group 101 . The control module 20 is connected with the first detection unit 10, and is used for judging whether there is a foreign object within the coupling range of the transmitting coil according to the first induction electrical signal set.

Based on the fact that the first detection coil group 101 has an axisymmetric structure on the surface of the transmitting coil, and there is no foreign matter in the coupling range of the transmitting coil, the amplitude of a pair of first induction signals generated at symmetrical positions in the first detection coil group 101 is The value difference should be 0 or within a preset range, and when a foreign object invades, because the foreign object affects the distribution of the magnetic field, and then causes the amplitude difference of at least one pair of first induction signals to change, the control module 20 passes Whether there is a foreign object can be determined by detecting the amplitude difference of each pair of first induction signals of the first detection coil group 101 .

However, when the foreign matter is located on the central axis of the transmitting coil, that is, when it is symmetrical about the second center line, the foreign matter fails to break the voltage balance of the first detection coil group 101, and the difference between the amplitudes of each pair of first induction signals does not change, and the first detection The coil assembly 101 cannot identify whether there is a foreign object intruding. At this time, each pair of first induction signals cannot be used as a criterion for the presence or absence of a foreign object, so that the first detection unit 10 has a central axis detection blind zone. Therefore, by adding the second detection coil group 102 in the first detection unit 10 to reduce the detection blind zone area, wherein, the control module 20 can detect whether the amplitude difference of a pair of second induction signals of the second detection coil group 102 is 0 or within the preset range, if it is not 0 or exceeds the preset range, it is judged that there is a foreign object in the coupling range of the transmitting coil, so as to realize the global foreign object detection of the transmitting coil.

In the above example, by setting the first detection unit 10, it is possible to detect the intrusion of foreign matter in the entire area except the center of the transmitting coil, wherein the second detection coil group 102 of the first detection unit 10 is used to eliminate the first detection coil group 101 The detection blind area fills the technical gap. On the basis of solving the detection blind area of the metal foreign object detection device in the wireless charging system during operation, the detection sensitivity and accuracy can be improved, and the structure is simple, the reliability is strong, and the wireless charging system is not affected. its own performance.

In one embodiment, as shown in FIG. 2 , which is a schematic structural diagram of the first detection unit 10 provided in one embodiment, the first detection coil group 101 includes multiple pairs of first coils, and each pair of first coils is relatively The first midline is symmetrical, and the plurality of first coils located on the same side of the first midline are arranged at regular intervals, wherein each of the first coils is used to output corresponding first induction signals.

It can be understood that in this embodiment, the first center line is recorded as the Y-axis direction, and the direction perpendicular to the first center line is the X-axis direction, and the first detection coil group 101 includes a plurality of first coils laid in an array along the X-axis direction, and A pair of first coils symmetrical to the Y-axis direction is formed, respectively denoted as a ₁ and b ₁ , a ₂ and b ₂ , a ₃ and b ₃ , ..., a _n-1 and b _n-1 , and there are (n -1) A pair of first coils that are bilaterally symmetrical about the Y axis, and each pair includes the same number of coil units. Wherein, the shape of the first coil can be circular, rectangular or other polygons, etc., because the rectangular coils can be closely arranged due to geometric features, which can effectively reduce the area ratio of the detection blind zone, so the preferred shape of the first coil in this application is rectangle.

Further, the first detection coil group 101 uses two first coils placed symmetrically to form a balanced coil to detect foreign objects. In this embodiment, a pair of first coils a ₁ and b ₁ are taken as an example for explanation. Due to the symmetry of the magnetic field of the transmitting coil, when no foreign matter invades the wireless charging system, the amplitude of the first induction signal output by the first coil a ₁ and b ₁ is the same, that is, under ideal conditions, the two first coils a ₁ and b The difference in the amplitude of the first induction signal between ₁ is 0. If a foreign object invades the range of the first coil a ₁ , the foreign object will affect the magnetic flux passing through a ₁ , resulting in the amplitude of the first induction signal output by a ₁ changes, but the amplitude of the first induction signal output by b ₁ does not change, at this time the difference between the amplitude of the first induction signal of the first coil a ₁ and b ₁ is no longer 0, so by comparing the first coil a ₁ and b ₁ respectively output the first induction signal to judge whether there is foreign matter intrusion. Similarly, when there is a change in the amplitude difference of the first induction signals of a certain pair of first coils, it can be determined that there is a foreign object within the coupling range of the transmitting coil.

In one embodiment, the second detection coil groups 102 are symmetrically distributed about the center. Please continue to refer to FIG. 2 , the second detection coil group 102 has a center-symmetric structure, which can effectively eliminate other central axis detection blind spots except the center point caused by the axis-symmetric structure of the first detection coil group 101 .

In one embodiment, the second detection coil group 102 includes a pair of second coils, and each of the second coils is respectively used to output the corresponding second induction signals.

Specifically, the second coil whose input end is located on the left side of the Y-axis direction is marked as a _n , and the second coil whose input end is located on the right side of the Y-axis direction is marked as b _n . When there is no foreign object, the amplitude difference of the second induction signal correspondingly output by the two second coils a _n and b _n should be 0 or within the preset range. The difference between the amplitudes of the second induction signals output by the two second coils a _{n and} b _n will change. Therefore, the control module detects the amplitudes of the second induction signals output by the above two second coils an and b _n The difference between the values can be used to determine whether foreign matter has invaded the central axis area.

In one embodiment, the second detection coil group 102 is divided into a symmetrical area and a central area, and the symmetrical area is symmetrically distributed about the center of the central area; wherein, the number of symmetrical areas is multiple pairs, and in the same symmetrical area, the first The area enclosed by the second detection coil group 102 on the left side of the centerline and the first centerline is equal to the area enclosed by the second detection coil group 102 on the right side of the first centerline and the first centerline.

Divide the symmetrical area and the central area in the direction of the Y axis. The number of symmetrical areas can be multiple pairs. In order to further improve the foreign object detection sensitivity of the second detection coil group 102, the structure of the coil units in the central area and the symmetrical area can be specially modulated. , this embodiment does not limit the coil structure of each region. Specifically as shown in Figure 3 (Figure 3 takes the C area as the central area, and uses two pairs of symmetrical areas A and B as an example to illustrate), two B areas that are symmetrical to the C area in the Y-axis direction form a pair of symmetrical areas, Similarly, two A areas form another pair of symmetrical areas, and the shape of the coils of the same pair of symmetrical areas is arranged in the same way. The area enclosed by a pair of symmetrical areas A or B on the left side of the Y axis is the same as that enclosed on the right side of the Y axis. The same area, in order to realize that in the state of no foreign matter, the amplitudes of the second induction signals respectively output by the two second coils a _n and b _n are consistent, that is, the difference between the amplitudes of the second induction signals is kept at 0 or at within the preset range.

In one embodiment, as shown in FIG. 4 , the second detection coil group located in the first symmetrical area has a multi-turn coil structure, the first symmetrical area is the outermost symmetrical area in the first direction, and the first direction is along the midline of the transmitting coil.

It can be understood that since the magnetic induction in the edge region of the transmitting coil is relatively weak, in order to prevent the outermost part of the second detection coil group in the first direction (Y-axis direction) from becoming a blind spot for foreign object detection, the outermost part of the second detection coil group in the Y-axis direction The symmetrical area is configured as a multi-turn coil structure, which can enhance the foreign matter detection sensitivity of the first symmetrical area. In addition, the coils in the above-mentioned first symmetrical area are not symmetrical with respect to the Y axis, and the left-right asymmetrical structure can prevent the positive and negative magnetic fluxes passing through the first symmetrical area from canceling each other, and further prevent the occurrence of no voltage reading.

In one embodiment, as shown in Figure 5, the number of symmetrical areas is two pairs, the second detection coil group located in the second symmetrical area has a serpentine structure extending along the first direction; the second detection coil group located in the central area The group has a serpentine structure extending along the second direction; wherein, the second direction is perpendicular to the first direction, and the second symmetrical area is a symmetrical area between the first symmetrical area and the central area.

Furthermore, when the second detection coil group is provided with two pairs of symmetrical areas, one pair is the first symmetrical area A located on the outermost side, and the other pair is the second symmetrical area located between the first symmetrical area A and the central area C. Zone B, wherein, in order to enhance the detection sensitivity of the second detection coil group, the structures of the central zone C and the second symmetrical zone B are specially modulated. Specifically, the central area C has a plurality of C-shaped coil structures alternately arranged along the X-axis direction (second direction), and the second symmetrical area B has a plurality of C-shaped coil structures alternately arranged along the Y-axis direction (first direction). (Figure 5 shows that the central area C has four alternately arranged C-shaped coil structures, and the second symmetrical area B has three alternately arranged C-shaped coil structures as an example), and the single C-shaped coil in the second symmetrical area B The size of the structure is different from the single C-shaped coil structure of the central area C, thereby enhancing the foreign matter detection sensitivity of the central area C and the second symmetrical area B.

In one embodiment, with reference to FIG. 6 and FIG. 7 (FIG. 7 is illustrated by taking the first detection unit 10 containing seven pairs of first coils as an example), the foreign object detection device further includes a second detection unit 30, and the second detection unit 30 The center of the center is staggered with the center of the first detection unit 10, and the second detection unit 30 is used to generate the second induced electrical signal to make up for the blind area of the magnetic field detection of the first detection unit 10; wherein, as shown in FIG. 8 , the control module 20 It is also connected to the second detection unit 30 for judging whether there is a foreign object within the coupling range of the transmitting coil according to the first induction electrical signal set and the second induction electrical signal.

Specifically, since the second detection coil group 102 has a center-symmetrical structure, the first detection unit 10 has a detection blind area at the center point, so the second detection unit 30 is arranged on one side of the center position of the first detection unit 10, thereby eliminating The central point detects the blind area. Compared with the technology of using two layers of large-sized detection coils arranged in a staggered manner, the technology provided by this application uses a first detection unit 10 and a small-sized second detection unit 30 close to the center position. , not only can greatly reduce the area ratio of the detection blind zone, but also reduce the cost and improve the detection sensitivity. It should be noted that the second detection unit 30 can be arranged on the side of the first detection unit 10 away from the transmitting coil, and can also be arranged on the side of the first detection unit 10 close to the transmitting coil, that is, the second detection unit 30 and The stacking order of the first detection unit 10 can be interchanged, and this application does not limit the order.

Further, FIG. 8 illustrates 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 output signal of the second detection unit 30. The second induction electrical signal, and judge whether there is a foreign matter intrusion according to the above signal.

In one embodiment, the second detection unit 30 includes a rectangular coil. It can be understood that the second detection unit 30 having a rectangular structure has a larger blind area detection area under the same size as structures of other shapes.

In one embodiment, as shown in FIG. 9 , the control module 20 includes a signal receiving unit 201 and a signal processing unit 202. The signal receiving unit 201 is respectively connected to the first detection unit 10 and the second detection unit 30 for obtaining the The first sensing signal, each of the second sensing signals and the second sensing electric signal; the signal processing unit 202 is connected to the signal receiving unit 201, and is used to The magnitude of the second induction signal, the magnitude of the second induction electrical signal, the first preset threshold and the second preset threshold determine whether there is a foreign object within the coupling range of the transmitting coil.

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 first induction signal output by each second coil. The second induction signal, meanwhile, the signal receiving unit 201 is also connected to the rectangular coil in the second detection unit 30 to receive the second induction electrical signal output by the rectangular coil.

Further, the signal receiving unit 201 transmits the obtained above-mentioned signals 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 induction electrical signal output by the second detection unit 30 with the second preset threshold, and if the former exceeds the latter, it is determined that there is a foreign object intrusion into the wireless charging system at this time, otherwise the detection continues ; The signal processing unit 202 makes a difference between the amplitudes of the two first induction signals output by a pair of first coils in the first detection unit 10, and compares the obtained difference with the first preset threshold, if the former exceeds the latter Otherwise, it is judged that there is a foreign object intrusion into the wireless charging system at this time, otherwise, continue to detect other pairs of first coils until the difference between the amplitudes of the first induction signals output by each pair of first coils does not exceed the first preset threshold. In the case where it is determined that there is no foreign object based on the detection by the second detection unit 30 , it can be determined that there is no foreign object intrusion into the wireless charging system.

In one embodiment, the signal processing unit 201 is configured to: when the amplitude difference of each pair of first sensing signals is less than or equal to the first preset threshold, the difference of the amplitudes of the two second sensing signals is less than or equal to the first preset threshold. threshold, and when the amplitude of the second induction electrical signal is less than or equal to the second preset threshold, it is determined that there is no foreign matter within the coupling range of the transmitting coil.

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

为第一线圈或第二线圈a_i输出后在信号处理单元202中得到的感应信号幅值，

为第一线圈或第二线圈b_i输出后在信号处理单元202中得到的感应信号幅值。Among them, ΔU _i is the absolute value of the amplitude difference of the induction signal of the i-th pair,

is the amplitude of the induction signal obtained in the signal processing unit 202 after the output of the first coil or the second coil a _i ,

is the amplitude of the induction signal obtained in the signal processing unit 202 after output from the first coil or the second coil _bi .

When the amplitude difference of the induction signals 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 induction electrical signal output by the second detection unit 30 is within the second preset threshold When it is within the range, it means that there is no foreign matter intrusion into the transmitting coil.

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

When the amplitude difference of the induction 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 induction electrical signal output by the second detection unit 30 exceeds the second preset threshold range, it indicates that foreign matter has invaded the transmitting coil.

In one embodiment, the signal processing unit 202 includes a sequentially connected sampling resistor, a low-pass filter, an operational amplifier, and a central processing unit. Each of the first induction signal, each of the second induction signal and the second induction electrical signal received by the signal processing unit 202 is first sent to the sampling resistor, and the resistance value of the sampling resistor is very large, generally above 100kΩ, because The signal processing unit 202 analyzes the fundamental wave signal, so each of the signals after the sampling resistor needs to pass through the next-stage low-pass filter to filter the high-order harmonics, and then pass through the first-stage operational amplifier to analyze each The signals are amplified to improve the judgment accuracy of the signal processing unit 202, and finally each of the signals is input to the central processing unit for calculation and analysis to judge whether there is a foreign object or not.

The present application also provides a foreign matter detection method, which is applied to the foreign matter detection device as described above, and the method includes steps S300 and S400, specifically as follows:

Step S300: When the receiving coil is not within the coupling range of the transmitting coil, the drive control module acquires a first induction electrical signal set.

When the electric vehicle is about to drive into the charging station, the foreign object detection of the wireless charging system needs to be carried out before charging. At this time, the system will automatically place the first preset threshold and the second preset threshold prepared in advance in the signal processing module. And perform no-load foreign object detection. The signal receiving unit in the control module obtains 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.

Step S400: When the control module judges that there is no foreign object within the coupling range of the transmitting coil according to the first induction electric signal set, issue a drive-in command; the drive-in command is used to instruct the vehicle to be charged to drive in, so that the receiving coil of the vehicle to be charged Within the coupling range of the transmitting coil.

The signal processing unit in the control module compares the threshold difference of the first induction signal output by each pair of first coils with the first preset threshold, and also compares the threshold difference of the second induction signal output by a pair of second coils Compared with the first preset threshold, if the above-mentioned difference does not exceed the first preset threshold, then there is no foreign object in the coupling range of the transmitting coil, then a drive-in instruction is issued, and the electric vehicle drives into the charging station for normal charging, and During the charging process, the conventional foreign object detection under the rated load is continued to prevent the intrusion of foreign objects during the charging process; if a certain pair of difference exceeds the first preset threshold, there is a foreign object in the coupling range of the transmitting coil, and this When it is necessary to stop the work of the transmitting coil, and send an alarm signal to prompt that foreign objects need to be cleaned at this time. After the foreign matter is cleaned up, the content of step S300 is recirculated.

In one embodiment, when the foreign object detection device includes the second detection unit, step S300 further includes the following steps before acquiring the first induction electrical signal set:

Step S100: The drive control module acquires the second electrical induction signal.

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

Step S200: When the control module determines that there is a foreign object within the coupling range of the transmitting coil according to the first induction electrical signal set or the second induction electrical signal, control the transmitting coil to stop transmitting signals.

The signal processing unit compares the amplitude of the second induced electrical signal with the second preset threshold, and if the former does not exceed the latter, enter step S300 and step S400; if the former exceeds the latter, the coupling range of the transmitting coil There is a foreign object in the internal memory. At this time, the transmitting coil needs to be stopped, and an alarm signal is sent to indicate that the foreign object needs to be cleaned at this time. After the foreign matter is cleaned up, recycle to step S300 and step S400.

In one embodiment, as shown in FIG. 11 , a schematic flow chart of a method for foreign object detection is provided, wherein the method includes steps S10 , S20 , S30 , S40 , S50 and S60 .

Step S10: Before the electric vehicle drives in, the wireless system is initialized, and the first preset threshold and the second preset threshold are placed in the signal processing module for no-load detection.

Step S20: The signal receiving unit acquires the second induction electrical signal output by the second detection unit, and transmits it to the signal processing unit.

Step S30: the signal processing unit judges whether the amplitude of the second induction electrical signal is greater than a second preset threshold, and if so, the transmitting coil stops working, and sends out an alarm signal to prompt cleaning of foreign objects.

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.

Step S50: The signal processing unit judges whether the difference between the threshold values of the first induction signals output by each pair of first coils and the threshold difference between the second induction signals output by a pair of second coils are both smaller than the first preset threshold, if not, Then the transmitting coil stops working, and an alarm signal is sent to prompt to clean up the foreign matter.

Step S60: Send out a driving-in instruction, and the electric vehicle drives into the charging station for normal charging.

It should be noted that during the charging process, the conventional foreign object detection under rated load will continue to be carried out to prevent the intrusion of foreign objects during the charging process.

It should be understood that although the various steps in the flowcharts of FIG. 10 and FIG. 11 are shown sequentially as indicated by the arrows, these steps are not necessarily executed sequentially in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order restriction on the execution of these steps, and these steps can be executed in other orders. Moreover, at least some of the steps in FIG. 10 and FIG. 11 may include multiple steps or stages, and these steps or stages are not necessarily executed at the same time, but may be executed at different moments, and the steps or stages The order of execution is not necessarily performed sequentially, but may be performed alternately or alternately with other steps or at least a part of steps or stages in other steps.

In the description of this specification, descriptions with reference to the terms "some embodiments", "other embodiments", "ideal embodiments" and the like mean that specific features, structures, materials, or characteristics described in connection with the embodiments or examples are included in this specification. In at least one embodiment or example of the application. In this specification, schematic descriptions of the above terms do not necessarily refer to the same embodiment or example.

The technical features of the above-mentioned embodiments can be combined arbitrarily. For the sake of concise description, all possible combinations of the technical features of the above-mentioned embodiments are not described. However, as long as there is no contradiction in the combination of these technical features, they should be It is considered to be within the range described in this specification.

The above-mentioned embodiments only express several implementation modes of the present application, and the description thereof is relatively specific and detailed, but should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the scope of protection of the patent application should be based on the appended claims.

Claims (13)

1. A foreign matter detection device, characterized by comprising:

the first detection unit is arranged in the coupling range of the transmitting coil and is parallel to the transmitting coil, and the first detection unit is used for generating a first induction signal set according to an excitation magnetic field provided by the transmitting coil, wherein the first induction signal set comprises a plurality of pairs of first induction signals and a pair of second induction signals;

the control module is connected with the first detection unit and used for judging whether foreign matters exist in the coupling range of the transmitting coil according to the first induction electric signal set;

the first detection unit comprises a first detection coil group and a second detection coil group, a first central line of the second detection coil group is superposed with a second central line of the emission coil, the first detection coil group is symmetrical relative to the first central line, the first detection coil group is used for generating a plurality of pairs of first induction signals, and the second detection coil group is used for generating a pair of second induction signals so as to make up a magnetic field detection blind area of the first detection coil group.

2. The foreign object detection device according to claim 1, wherein the first detection coil group includes a plurality of pairs of first coils, each pair of the first coils being symmetrical with respect to the first center line, the plurality of first coils located on the same side of the first center line being arranged at regular intervals;

wherein, each first coil is used for outputting each corresponding first induction signal respectively.

3. The foreign matter detection device according to claim 1, wherein the second detection coil groups are distributed in central symmetry.

4. The foreign object detection device according to claim 3, wherein the second detection coil group is divided into a symmetrical region and a central region, the symmetrical region being distributed in central symmetry with respect to the center of the central region;

the number of the symmetrical areas is multiple pairs, and in the same symmetrical area, the area enclosed by the second detection coil group positioned on the left side of the first central line and the first central line is equal to the area enclosed by the second detection coil group positioned on the right side of the first central line and the first central line.

5. The foreign object detection device according to claim 4, wherein the second detection coil group located in a first symmetric region, which is the symmetric region located outermost in a first direction along a center line direction of the transmission coil, has a multi-turn coil structure.

6. The foreign object detection device according to claim 5, wherein the number of the symmetric regions is two pairs;

the second detection coil group positioned 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 in a second direction;

wherein the second direction is perpendicular to the first direction, and the second symmetric region is a symmetric region between the first symmetric region and the central region.

7. The foreign object detection apparatus according to any one of claims 3 to 6, wherein the second detection coil group includes a pair of second coils, each of the second coils being configured to output a corresponding one of the second induction signals.

8. The foreign object detection device according to any one of claims 1 to 6, characterized by further comprising:

the center of the second detection unit is staggered with the center of the first detection unit, and the second detection unit is used for generating a second induction electric signal so as to make up a magnetic field detection blind area of the first detection unit;

the control module is further connected with the second detection unit and used for judging whether foreign matters exist in the coupling range of the transmitting coil according to the first induction electric signal set and the second induction electric signal.

9. The foreign object detection device according to claim 8, wherein the second detection unit includes a rectangular coil.

10. The foreign object detection apparatus according to claim 1, wherein the control module includes:

a signal receiving unit, connected to the first detecting unit and the second detecting unit, respectively, for obtaining each of the first inductive signals, each of the second inductive signals, and the second inductive electrical signal, respectively;

and the signal processing unit is connected with the signal receiving unit and used for judging whether foreign matters exist in the coupling range of the transmitting coil according to the amplitude of each first induction signal, the amplitude of each second induction signal, a first preset threshold and a second preset threshold.

11. The foreign object detection device according to claim 10, wherein the signal processing unit is configured to determine that no foreign object exists in the coupling range of the transmitting coil when the difference between the amplitudes of the pairs of the first induced signals is smaller than or equal to the first preset threshold, the difference between the amplitudes of the two second induced signals is smaller than or equal to the first preset threshold, and the amplitude of the second induced signal is smaller than or equal to the second preset threshold; and/or

And when the difference between the amplitudes of any pair of the first induction signals is greater than the first preset threshold, or the difference between the amplitudes of two second induction signals is greater than the second preset threshold, or the amplitude of the second induction signal is greater than the second preset threshold, judging that a foreign matter exists in the coupling range of the transmitting coil.

12. A foreign matter detection method applied to the foreign matter detection apparatus according to any one of claims 1 to 11, the method comprising:

when the receiving coil is not in the coupling range of the transmitting coil, the driving control module acquires a first induction electric signal set;

when the control module judges that no foreign matter exists in the coupling range of the transmitting coil according to the first induction electric signal set, a driving-in instruction is sent out; the driving-in instruction is used for indicating a vehicle to be charged to drive in so as to enable a receiving coil of the vehicle to be charged to be in a coupling range of a transmitting coil.

13. The foreign object detection method according to claim 12, wherein when the foreign object detection apparatus includes the second detection unit, before the acquiring the first induced electrical signal set, the method further includes:

the driving control module acquires a second induction electric signal;

and when the control module judges that foreign matters exist in the coupling range of the transmitting coil according to the first induction electric signal set or the second induction electric signal, the transmitting coil is controlled to stop transmitting signals.

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