CN107306054B - Wireless power transmission device and structure of metal foreign body detection coil thereof - Google Patents

Abstract

A wireless power transmission device and a structure of a metal foreign body detection coil thereof, wherein the wireless power transmission device comprises a transmitting antenna to radiate an electromagnetic wave, and a plurality of metal foreign body detection coils to sense the electromagnetic wave and generate a plurality of signals to be tested accordingly, wherein each of the metal foreign body detection coils is composed of three coil units connected in series, and the three coil units are arranged at intervals, wherein the distribution area of the transmitting antenna covers the plurality of metal foreign body detection coils; the present invention comprises a controller to determine whether a metal foreign body has entered the electromagnetic wave range of the transmitting antenna according to a reference voltage signal and the plurality of signals to be tested corresponding to the plurality of metal foreign body detection coils, so as to stop the generation of the electromagnetic wave when a metal foreign body is detected, thereby preventing the electromagnetic wave from heating the metal foreign body.

Description

Structure of Wireless Power Transmission Device and Metal Foreign Object Detection Coil

technical field

The invention relates to a wireless power transmission device and a coil structure thereof, in particular to a wireless power transmission device with a metal foreign body detection function and a structure of a metal foreign body detection coil.

Background technique

The existing wireless power transmission device mainly includes an AC/DC converter, a DC/AC converter and a transmitting antenna which are connected in sequence. The input end of the AC/DC converter can be used to receive the AC power provided by the commercial power, the AC/DC converter converts the AC power to the DC power, the DC/AC converter is used for receiving the DC power, and converts the AC power to the DC power. The DC power is converted into an AC output power, and the DC/AC converter radiates electromagnetic waves from the AC output power through the transmitting antenna. In this way, a receiving device with a wireless charging function senses the electromagnetic waves of the transmitting antenna, and the receiving device can convert the electromagnetic waves into a charging power source for charging, thereby achieving a non-wired wireless charging operation.

When a metal foreign object enters the range of the electromagnetic wave generated by the wireless power transmission device, the metal foreign object generates high temperature under the action of the electromagnetic field, and there is a fear of causing danger. Therefore, the existing wireless power transmission device can have a metal foreign object detection function, and its metal foreign object detection technology is to directly measure the parameters of the electromagnetic wave generated by the transmitting antenna, such as power, efficiency, S-parameter and quality factor and other parameters. The change of the parameters is used to judge whether there is any metal foreign matter entering the range of the electromagnetic wave generated by the wireless power transmission device.

However, the measurement results of these parameters will be affected by the electromagnetic wave transmission distance, especially when the size of the metal foreign object is smaller than the size of the transmitting antenna, it is difficult to accurately determine the electromagnetic wave generated by the metal foreign object entering the wireless power transmission device. within the range.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to provide a wireless power transmission device and a structure of a metal foreign object detection coil to effectively detect metal foreign objects.

In order to achieve the above object, the present invention provides a wireless power transmission device, comprising:

an AC/DC converter, an input end of which is used to receive an AC power source, and convert the AC power source into a DC power source;

A DC/AC converter, an input terminal of which is electrically connected to an output terminal of the AC/DC converter, and the DC power is converted into an AC output power; the DC/AC converter includes a compensation capacitor for electrical connection a transmitting antenna, through which the AC output power radiates an electromagnetic wave to the outside;

A plurality of metal foreign object detection coils are distributed and arranged on an insulating substrate to sense the electromagnetic wave and generate a plurality of signals to be measured correspondingly. Each of the metal foreign object detection coils is composed of three coil units connected in series, and the three coil units are arranged at intervals , wherein the transmitting antenna distribution area covers the plurality of metal foreign object detection coils;

a reference voltage generating circuit, an input terminal of which is electrically connected to the compensation capacitor of the DC/AC converter to receive its terminal voltage, and generates a reference voltage signal according to the terminal voltage of the compensation capacitor;

a plurality of feedback detection circuits, respectively electrically connected to the plurality of metal foreign object detection coils, each of the feedback detection circuits receives a signal to be tested generated by the corresponding metal foreign object detection coil; and

a controller electrically connected to the reference voltage generating circuit and the plurality of feedback detection circuits to receive the reference voltage signal and the plurality of under-test signals corresponding to the plurality of metal foreign object detection coils, and to receive the reference voltage signal according to the reference voltage signal It is judged with the plurality of signals to be tested whether there is any metal foreign matter entering the electromagnetic wave range radiated by the transmitting antenna.

In order to better achieve the above purpose, the present invention also provides a structure of a metal foreign body detection coil, the metal foreign body detection coil is composed of three coil units formed on an insulating substrate connected in series, and the three coil units are spaced apart from each other. arrangement.

The technical effect of the present invention is:

The structure of the metal foreign body detection coil of the present invention is composed of three coil units connected in series, and the three coil units are arranged at intervals, so that the structure of the metal foreign body detection coil of the present invention can have a uniform magnetic field induction capability in a space to be measured . In addition, compared with the prior art, the present invention measures the parameters of the transmitting antenna of the wireless power transmission device because the distribution area of the transmitting antenna covers the plurality of metal foreign object detection coils, that is, the size of each metal foreign object detection coil is smaller than that of the transmitting antenna, and the Each metal foreign object detection coil has its own detection area, so it can effectively detect metal foreign objects smaller than the size of the transmitting antenna. When a metal foreign object is detected, the controller immediately stops generating electromagnetic waves from the transmitting antenna to avoid the metal foreign object. Foreign body heating.

The present invention is described in detail below with reference to the accompanying drawings and specific embodiments, but is not intended to limit the present invention.

Description of drawings

Fig. 1 is the circuit block diagram of the wireless power transmission device of the present invention;

2 is a perspective exploded schematic view of the housing, the transmitting antenna provided on the first insulating substrate, and the metal foreign object detection coil provided on the second insulating substrate of the present invention;

3 is a partial circuit block diagram of the wireless power transmission device of the present invention;

4 is a circuit block diagram of a reference voltage generating circuit, a controller and a feedback detection circuit of the present invention;

5 is a schematic plan view of an embodiment of the foreign object detection coil structure of the present invention;

Fig. 6 is the A-A sectional schematic diagram of Fig. 5;

FIG. 7 is a partial plan view of another embodiment of the foreign object detection coil structure of the present invention;

Fig. 8 is the B-B sectional schematic diagram of Fig. 7;

FIG. 9 is a schematic plan view of still another embodiment of the foreign object detection coil structure of the present invention;

FIG. 10 is a schematic plan view of still another embodiment of the foreign object detection coil structure of the present invention;

FIG. 11 is a schematic plan view of the foreign object detection coil shown in FIG. 10 arranged in a polygonal structure;

FIG. 12 is a flow chart of metal foreign matter judgment of the controller of the present invention.

Detailed ways

Below in conjunction with accompanying drawing, structure principle and working principle of the present invention are described in detail:

Please refer to FIGS. 1 to 3 , the wireless power transmission device 10 of the present invention includes an AC/DC converter 11 , a DC/AC converter 12 , a transmitting antenna 13 , a plurality of metal foreign object detection coils 14 , and a reference voltage generating circuit 15. A plurality of feedback detection circuits 16 and a controller 17.

Please refer to FIG. 1 and FIG. 3 , the input end of the AC/DC converter 11 is for receiving an AC power supply, for example, the AC power supply can be AC power provided by commercial power, and the AC/DC converter 11 converts the AC power supply for DC power. The input end of the DC/AC converter 12 is electrically connected to the output end of the AC/DC converter 11 to receive the DC power and convert the DC power into an AC output power. The output end of the DC/AC converter 12 is electrically connected to the transmitting antenna 13 , so that the AC output power can radiate electromagnetic waves to the outside through the transmitting antenna 13 .

Please refer to FIG. 2 , the transmitting antenna 13 can be disposed on the surface of a first insulating substrate 30 , the plurality of metal foreign object detection coils 14 are arranged in an array and are distributed on the surface of a second insulating substrate 31 , wherein the second The insulating substrate 31 is disposed on the transmitting antenna 13, so that the plurality of metal foreign object detection coils 14 are located above the transmitting antenna 13, and the distribution area of the transmitting antenna 13 covers the plurality of metal foreign object detection coils 14, the plurality of metal foreign object detection coils 14. The coil 14 and the transmitting antenna 13 are isolated by the second insulating substrate 31 . The second insulating substrate 31 is covered with a casing 32 , and the plurality of metal foreign object detection coils 14 are covered by the casing 32 to avoid exposure. The electromagnetic waves emitted by the transmitting antenna 13 can penetrate the second insulating substrate 31 and the casing 32 .

A receiving device 20 can be placed on the outer side of the casing 32 , and the receiving device 20 refers to the device to be charged. As shown in FIG. 1 , the receiving device 20 includes a receiving antenna 21 , a rectifier 22 , a communication module 23 and a control The rectifier 24 , when the receiving antenna 21 senses the electromagnetic wave emitted by the transmitting antenna 13 , it generates an inductive power source, and the rectifier 22 converts the inductive power source into a DC charging power source. Correspondingly, when the transmitting antenna 13 radiates electromagnetic waves to the outside, because the metal foreign body detection coils 14 are also located within the radiation range of the electromagnetic waves, the metal foreign body detection coils 14 can also sense the electromagnetic waves and correspondingly generate a to-be-detected signal. Signal Vsensor.

The structure of the metal foreign body detection coil 14 of the present invention is composed of three coil units connected in series, and the three coil units are arranged at intervals, whereby the structure of the metal foreign body detection coil 14 of the present invention can have a uniform magnetic field in a space to be measured Induction capability, the space to be measured is the magnetic field induction area of the three coil units.

Please refer to FIG. 5 , in the first embodiment of the metal foreign object detection coil 14 , the three coil units are a first coil unit 141 , a second coil unit 142 and a third coil unit 143 respectively. Taking the first coil unit 141 as an example, it includes a central line segment 400 , a first line segment 401 , a second line segment 402 , a third line segment 403 , a fourth line segment 411 , a fifth line segment 412 , and a sixth line segment 413 , a plurality of connecting lines 42 and a plurality of bridge lines 43 .

The central line segment 400 is formed on a surface of the second insulating substrate 31 and has a U-shaped structure including two ends. The first to third line segments 401 to 403 are formed on the surface of the second insulating substrate 31 and from the inside The outsides are sequentially distributed on one side of the central line segment 400 , that is, the first line segment 401 is closest to the central line segment 400 , and the fourth to sixth line segments 411 to 413 are formed on the surface of the second insulating substrate 31 and are formed by The inner and outer segments are sequentially distributed on the other side of the central line segment 400 relative to the first to third line segments 401 to 403 , that is, the fourth line segment 411 is closest to the central line segment 400 . One end of the third line segment 403 is a current output (or input) end, the other end is electrically connected to one end of the fifth line segment 412 via a bridge wire 43 , and the other end of the fifth line segment 412 is electrically connected via a connecting line 42 One end of the first line segment 401 is connected, and the other end of the first line segment 401 is electrically connected to one end of the central line segment 400 via a bridge wire 43 ; the other end of the central line segment 400 is electrically connected to the fourth line via a connecting line 42 One end of the line segment 411 , the other end of the fourth line segment 411 is electrically connected to one end of the second line segment 402 via a bridge line 43 , and the other end of the second line segment 402 is electrically connected to the sixth line segment 413 via a connecting line 42 one end, the other end of the sixth line segment 413 is electrically connected to the second coil unit 142 via a bridge wire 43 , and the structures of the second coil unit 142 and the third coil unit 143 can be deduced by analogy; please refer to the drawings 6. The connecting wire 42 is formed on the surface of the second insulating substrate 31, an insulating layer 44 is provided on the surface of the connecting wire 42, and the bridging wire 43 is formed on the insulating layer 44, so that the bridging wire 43 and the connecting wire 42 are connected to each other. The insulating layer 44 is separated to prevent the connection wire 42 from being in direct contact with the bridge wire 43 and short-circuiting. Therefore, the central line segment 400 , the first to third line segments 401 to 403 and the fourth to sixth line segments 411 to 413 are connected in series via the plurality of connecting lines 42 and bridge lines 43 to form a wound coil structure .

Please refer to FIG. 7 and FIG. 8 , in another embodiment, the second insulating substrate 31 can be a double-sided printed circuit board including a top surface and a bottom surface, the central line segment 400 , the first to third line segments 401 to 403 , the fourth to sixth line segments 411 to 413 and the plurality of connection lines 42 are formed on the top surface of the second insulating substrate 31 , and the bridge lines 45 are formed on the bottom surface of the second insulating substrate 31 , The plurality of bridging lines 45 are connected between corresponding two line segments through via holes 46 penetrating the second insulating substrate 31 .

Please refer to FIG. 9 , in the second embodiment of the metal foreign object detection coil 14 ′, the three coil units are a first coil unit 141 ′, a second coil unit 142 ′ and a third coil unit 143 respectively '. The second coil unit 142' is wound by a single line segment 472 into an isosceles triangle coil structure and has opposite first hypotenuse and second hypotenuse portions, and opposite ends of the second coil unit 142' respectively form a an inner end and an outer end; the first coil unit 141 ′ is wound into a right-angled triangle coil structure by a single line segment 471 and includes a hypotenuse portion, the hypotenuse portion is located at the first bevel of the second coil unit 142 ′ The outside of the edge portion is parallel to the first hypotenuse portion, and opposite ends of the first coil unit 141 ′ respectively form an inner end and an outer end. The third coil unit 143' is wound by a single wire segment 473 into a right-angled triangle coil structure and includes a hypotenuse portion located outside the second hypotenuse portion of the second coil unit 142' and parallel to the first hypotenuse portion. Two hypotenuses, opposite ends of the third coil unit 143' respectively form an inner end and an outer end; as shown in FIG. 9, the plurality of coil units 141', 142', 143' are separated by Arranged and the overall rectangular structure. The internal terminal of the first coil unit 141 ′ is connected to the external terminal of the second coil unit 142 ′ via a first connecting wire 474 , and the internal terminal of the second coil unit 142 ′ is connected via a second connecting wire 475 The internal terminal of the third coil unit 143', the external terminal of the first coil unit 141' is a current input (or output) terminal, and the external terminal of the third coil unit 143' is a current output (or input) terminal. As described in the first embodiment, the plurality of connection lines 474, 475 can be formed above the plurality of single line segments 471, 472, 473, and the plurality of connection lines 474, 475 and the plurality of single line segments 471, 472, An insulating layer (not shown) is provided between 473; alternatively, the plurality of single line segments 471, 472, 473 can be formed on the top surface of a double-sided printed circuit board, and the plurality of connecting lines 474, 475 can be formed on On the bottom surface of the double-sided printed circuit board, the plurality of single line segments 471 , 472 , 473 and the plurality of connecting lines 474 , 475 can be connected in series through vias penetrating the double-sided printed circuit board.

Please refer to FIG. 10 , in the third embodiment of the metal foreign object detection coil 14 ″, the three coil units are a first coil unit 141 ″, a second coil unit 142 ″ and a third coil unit 143 respectively ". The second coil unit 142" is wound by a single wire segment 482 into an isosceles triangle coil structure and has opposite first and second hypotenuse portions. The opposite ends of the second coil unit 142" respectively form a An inner end and an outer end; the first coil unit 141" is wound into a right-angled triangle coil structure by a single line segment 481 and includes a hypotenuse portion, the hypotenuse portion is located at the first bevel of the second coil unit 142" On the outside of the edge and parallel to the first hypotenuse, opposite ends of the first coil unit 141" respectively form an inner end and an outer end. The third coil unit 143" is wound at a right angle by a single line segment 483. The triangular coil structure includes a hypotenuse portion, and the hypotenuse portion is located outside the second hypotenuse portion of the second coil unit 142" and is parallel to the second hypotenuse portion. The opposite two sides of the third coil unit 143". As shown in Figure 10, the plurality of coil units 141", 142", 143" are arranged at intervals to form a fan-shaped structure as a whole. The first coil unit 141" The internal terminal is connected to the internal terminal of the third coil unit 143" via a first connecting wire 484, and the external terminal of the first coil unit 141" is connected to the external terminal of the second coil unit 142" via a second connecting wire 485. Internal terminal, the external terminal of the second coil unit 142" is a current input (or output) terminal, and the external terminal of the third coil unit 143" is a current output (or input) terminal. As in the first implementation For example, the plurality of connection lines 484, 485 can be formed above the plurality of single line segments 481, 482, 483, and the plurality of connection lines 484, 485 and the plurality of single line segments 481, 482, 483 are provided There is an insulating layer (not shown in the figure); alternatively, the plurality of single line segments 481, 482, 483 can be formed on the top surface of a double-sided printed circuit board, and the plurality of connecting lines 484, 485 can be formed on the double-sided printed circuit board On the bottom surface of the circuit board, the plurality of single line segments 481 , 482 , 483 and the plurality of connection lines 484 , 485 can be connected in series through vias penetrating the double-sided printed circuit board.

Referring to FIG. 11 , four metal foreign object detection coils 14 ″ as shown in FIG. 9 may be disposed on the second insulating substrate, so that the four metal foreign object detection coils 14 ″ have an octagonal structure as a whole.

Based on the aforementioned metal foreign object detection coil 14 , when the transmitting antenna 13 radiates electromagnetic waves, each of the metal foreign object detection coils 14 is also located within the range of the electromagnetic wave, so each of the metal foreign object detection coils 14 can sense the electromagnetic wave and generate a corresponding The signal to be tested Vsensor.

Please refer to FIG. 1 and FIG. 3 , the DC/AC converter 12 includes a plurality of compensation capacitors Cp connected in series, the compensation capacitors Cp are electrically connected to the transmitting antenna 13 , and the input end of the reference voltage generating circuit 15 is electrically connected to the DC Two ends of any compensation capacitor Cp of the /AC converter 12 receive its terminal voltage. Please refer to FIG. 4 . The reference voltage generating circuit 15 includes a differential amplifier 151 , a full-wave rectifier 152 and For the DC filter 153 , the input end of the differential amplifier 151 is the input end of the reference voltage generating circuit 15 , and the output end of the DC filter 153 is the output end of the reference voltage generating circuit 15 . Therefore, the reference voltage generating circuit 15 performs differential amplification, full-wave rectification and DC filtering on the terminal voltage of the compensation capacitor Cp to generate a reference voltage signal Vref.

Input ends of the plurality of feedback detection circuits 16 are respectively electrically connected to the plurality of metal foreign object detection coils 14 to form a one-to-one connection structure. FIG. 1 and FIG. 3 only show a feedback detection circuit 16 and a metal foreign object detection The coil 14 is described as an example. Referring to FIG. 4 , each of the feedback detection circuits 16 includes a low-pass filter 161 , a differential amplifier 162 , a rectifier 163 and a DC filter 164 , which are serially connected in series. The input of the low-pass filter 161 is The terminal is the input terminal of the feedback detection circuit 16 , the output terminal of the DC filter 164 is the output terminal of the feedback detection circuit 16 , and each feedback detection circuit 16 generates its corresponding metal foreign object detection coil 14 The measured signal Vsensor is subjected to low-pass filtering, differential amplification, rectification and DC filtering.

The controller 17 has a plurality of signal input terminals, and the plurality of signal input terminals are respectively electrically connected to the output terminals of the reference voltage generation circuit 15 and the output terminals of the feedback detection circuits 16 to receive the reference voltage signal Vref and a plurality of signals to be tested Vseneor corresponding to the plurality of metal foreign object detection coils.

Please refer to FIG. 1 and FIG. 12 . Before use, the user can check whether there is metal foreign matter between the wireless power transmission device 10 and the receiving device 20 . If there is metal foreign matter, remove the metal foreign matter. If there is no metal foreign matter, the controller 17 of the wireless power transmission device 10 can execute a charging mode to control its transmitting antenna 13 to radiate electromagnetic waves. The foreign object detection coil 14 can sense the electromagnetic wave and generate a signal to be detected correspondingly. Thereby, the controller 17 receives the reference voltage signal Vref and the plurality of under-test signals Vseneor in an initial state (ie, a state without foreign metal objects), and according to the reference voltage signal Vref and the plurality of under-test signals Vsensor Calculate a gain value Gain corresponding to each of the metal foreign object detection coils 14, wherein the gain value Gain is the ratio of the reference voltage signal Vref and the signal to be measured Vsensor (ie: Gain=Vref/Vsensor), and then according to the multiple The gain value Gain of each metal foreign object detection coil 14 creates a gain table (step S101 ), and the gain table can be stored in the controller 17 ; in other words, each metal foreign object detection coil has a corresponding gain value Gain.

After the gain table is established, while the wireless power transmission device 10 is in the charging mode, the controller 17 also continues to receive the detection signals Vsensor of the plurality of metal foreign object detection coils 14 , and generates the generated metal foreign object detection coils 14 . The real-time detection signal Vsensor is multiplied by the corresponding gain value to obtain a real-time monitoring signal Vm (step S102), and the difference between the reference voltage signal Vref and the real-time monitoring signal Vm corresponding to any metal foreign object detection coil 14 (ie: |Vref-Vm|) is greater than or equal to a threshold value Vth (step S103).

When a metal foreign object enters the area between the wireless power transmission device 10 and the receiving device 20 , the metal foreign object will affect the electromagnetic field generated by the transmitting antenna 13 , and will also affect the real-time monitoring signal corresponding to each metal foreign object detection coil 14 . VM. Therefore, when the difference between the real-time monitoring signal Vm and the reference voltage signal Vref is greater than the threshold value Vth, the controller 17 determines that a metal foreign object has entered the area between the wireless power transmission device 10 and the receiving device 20, and further shuts down In order to stop the charging mode, the electromagnetic field can effectively avoid the high temperature caused by the effect of the electromagnetic field on the metal foreign body. Please refer to FIG. 1 , the controller 17 can be electrically connected to a communication module 18 to establish a connection with the communication module 23 of the receiving device 20 , when the controller 17 of the wireless power transmission device 10 determines that there is a metal foreign object, it can send out The control command to stop charging is given to the communication module 23 of the receiving device 20, and the controller 24 of the receiving device 20 can stop charging according to the control command.

Of course, the present invention can also have other various embodiments, without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding Changes and deformations should belong to the protection scope of the appended claims of the present invention.

Claims (10)

1. A wireless power transmission device, characterized in that, comprising: an AC/DC converter, an input end of which is used to receive an AC power source, and convert the AC power source into a DC power source; A DC/AC converter, an input terminal of which is electrically connected to an output terminal of the AC/DC converter, and the DC power is converted into an AC output power; the DC/AC converter includes a compensation capacitor for electrical connection a transmitting antenna, through which the AC output power radiates an electromagnetic wave to the outside; A plurality of metal foreign object detection coils are distributed and arranged on an insulating substrate to sense the electromagnetic wave and generate a plurality of signals to be measured correspondingly. Each of the metal foreign object detection coils is composed of three coil units connected in series, and the three coil units are arranged at intervals , wherein the transmitting antenna distribution area covers the plurality of metal foreign object detection coils; a reference voltage generating circuit, an input terminal of which is electrically connected to the compensation capacitor of the DC/AC converter to receive its terminal voltage, and generates a reference voltage signal according to the terminal voltage of the compensation capacitor; a plurality of feedback detection circuits, respectively electrically connected to the plurality of metal foreign object detection coils, each of the feedback detection circuits receives a signal to be tested generated by the corresponding metal foreign object detection coil; and a controller electrically connected to the reference voltage generating circuit and the plurality of feedback detection circuits to receive the reference voltage signal and the plurality of under-test signals corresponding to the plurality of metal foreign object detection coils, and to receive the reference voltage signal according to the reference voltage signal It is judged with the plurality of signals to be tested whether there is any metal foreign matter entering the electromagnetic wave range radiated by the transmitting antenna. 2 . The wireless power transmission device of claim 1 , wherein the plurality of metal foreign object detection coil arrays are arranged on the insulating substrate, and each coil unit of each of the metal foreign object detection coils includes a plurality of metal foreign object detection coils formed on the insulating substrate. 3 . A central line segment, a first line segment, a second line segment, a third line segment, a fourth line segment, a fifth line segment, and a sixth line segment of a surface of ; The central line segment has a U-shaped structure and includes two ends. The first line segment, the second line segment and the third line segment are sequentially distributed on one side of the central line segment from the inside to the outside. The fifth line segment and the sixth line segment are sequentially distributed from the inside to the outside on the other side of the central line segment relative to the first line segment to the third line segment; The third line segment is electrically connected to one end of the fifth line segment via a bridge line, the other end of the fifth line segment is electrically connected to one end of the first line segment via a connecting line, and the other end of the first line segment is electrically connected via a connecting line The bridge line is electrically connected to one end of the central line segment, the other end of the center line segment is electrically connected to one end of the fourth line segment via a connecting line, and the other end of the fourth line segment is electrically connected to the second line segment via a bridge line. one end, the other end of the second line segment is electrically connected to one end of the sixth line segment through a connecting line; The central line segment and the first line segment to the sixth line segment form a wound coil structure. 3 . The wireless power transmission device of claim 1 , wherein the plurality of metal foreign object detection coil arrays are arranged on the insulating substrate, and the three coil units of each of the metal foreign object detection coils are respectively a first coil unit. 4 . , a second coil unit and a third coil unit; The second coil unit is wound by a single line segment into an isosceles triangle coil structure and has opposite first hypotenuse portions and second hypotenuse portions, and opposite ends of the second coil unit respectively form an inscribed end and a external terminal; The first coil unit is wound by a single line segment into a right-angled triangle coil structure and includes a hypotenuse portion, the hypotenuse portion is located outside the first hypotenuse portion of the second coil unit and is parallel to the first hypotenuse portion, The opposite ends of the first coil unit respectively form an inner end and an outer end; The third coil unit is wound by a single line segment into a right-angled triangle coil structure and includes a hypotenuse portion, the hypotenuse portion is located outside the second hypotenuse portion of the second coil unit and is parallel to the second hypotenuse portion, The opposite ends of the third coil unit respectively form an inner end and an outer end; The internal terminal of the first coil unit is connected to the external terminal of the second coil unit via a first connecting wire, and the internal terminal of the second coil unit is connected to the internal terminal of the third coil unit via a second connecting wire ; The first coil unit, the second coil unit and the third coil unit are arranged at intervals to form a rectangular structure as a whole. 4 . The wireless power transmission device of claim 1 , wherein the three coil units of each of the metal foreign object detection coils are respectively a first coil unit, a second coil unit and a third coil unit; 4 . The second coil unit is wound by a single line segment into an isosceles triangle coil structure and has opposite first hypotenuse portions and second hypotenuse portions, and opposite ends of the second coil unit respectively form an inscribed end and a external terminal; The first coil unit is wound by a single line segment into a right-angled triangle coil structure and includes a hypotenuse portion, the hypotenuse portion is located outside the first hypotenuse portion of the second coil unit and is parallel to the first hypotenuse portion, The opposite ends of the first coil unit respectively form an inner end and an outer end; The third coil unit is wound by a single line segment into a right-angled triangle coil structure and includes a hypotenuse portion, the hypotenuse portion is located outside the second hypotenuse portion of the second coil unit and is parallel to the second hypotenuse portion, The opposite ends of the third coil unit respectively form an inner end and an outer end; The internal terminal of the first coil unit is connected to the internal terminal of the third coil unit via a first connecting wire, and the external terminal of the first coil unit is connected to the internal terminal of the second coil unit via a second connecting wire end; The first coil unit, the second coil unit and the third coil unit are arranged at intervals to form a fan-shaped structure as a whole. 5 . The wireless power transmission device of claim 4 , wherein the insulating substrate is provided with four of the metal foreign object detection coils, so that the four metal foreign object detection coils have an octagonal structure as a whole. 6 . 6 . The wireless power transmission device of claim 1 , wherein the controller receives the reference voltage signal and the plurality of signals to be measured in an initial state when judging whether there is a metal foreign object. 7 . , and calculate a gain value corresponding to each of the metal foreign object detection coils according to the reference voltage signal and the plurality of signals to be measured, wherein the gain value is the ratio of the reference voltage signal to the signal to be measured, and then according to the multiple The gain value of each metal foreign object detection coil establishes a gain table, and the gain table is stored in the controller; After the gain table is established, the controller continuously receives the detection signals of the plurality of metal foreign object detection coils, and multiplies the real-time detection signals generated by each of the metal foreign object detection coils by the corresponding gain value to obtain a real-time monitoring signal, When it is determined that the difference between the reference voltage signal and the real-time monitoring signal corresponding to any metal foreign object detection coil is greater than or equal to a threshold value, it is determined that there is a metal foreign object, and further shutdown is performed. 7. A structure of a metal foreign body detection coil, characterized in that the metal foreign body detection coil is composed of three coil units formed on an insulating substrate connected in series to induce electromagnetic waves and correspondingly generate a plurality of signals to be measured, and the three coil units are connected in series. The coil units are arranged at intervals. 8 . The structure of the metal foreign object detection coil as claimed in claim 7 , wherein each of the coil units comprises a central line segment, a first line segment, a second line segment, a The third line segment, a fourth line segment, a fifth line segment, and a sixth line segment; The central line segment has a U-shaped structure and includes two ends. The first line segment, the second line segment and the third line segment are sequentially distributed on one side of the central line segment from the inside to the outside. The fifth line segment and the sixth line segment are sequentially distributed from the inside to the outside on the other side of the central line segment relative to the first line segment to the third line segment; The third line segment is electrically connected to one end of the fifth line segment via a bridge line, the other end of the fifth line segment is electrically connected to one end of the first line segment via a connecting line, and the other end of the first line segment is electrically connected via a connecting line The bridge line is electrically connected to one end of the central line segment, the other end of the center line segment is electrically connected to one end of the fourth line segment via a connecting line, and the other end of the fourth line segment is electrically connected to the second line segment via a bridge line. one end, the other end of the second line segment is electrically connected to one end of the sixth line segment through a connecting line; The central line segment and the first line segment to the sixth line segment form a wound coil structure. 9 . The structure of the metal foreign object detection coil according to claim 7 , wherein the three coil units are respectively a first coil unit, a second coil unit and a third coil unit; 9 . The second coil unit is wound by a single line segment into an isosceles triangle coil structure and has opposite first hypotenuse portions and second hypotenuse portions, and opposite ends of the second coil unit respectively form an inscribed end and a external terminal; The first coil unit is wound by a single line segment into a right-angled triangle coil structure and includes a hypotenuse portion, the hypotenuse portion is located outside the first hypotenuse portion of the second coil unit and is parallel to the first hypotenuse portion, The opposite ends of the first coil unit respectively form an inner end and an outer end; The third coil unit is wound by a single line segment into a right-angled triangle coil structure and includes a hypotenuse portion, the hypotenuse portion is located outside the second hypotenuse portion of the second coil unit and is parallel to the second hypotenuse portion, The opposite ends of the third coil unit respectively form an inner end and an outer end; The internal terminal of the first coil unit is connected to the external terminal of the second coil unit via a first connecting wire, and the internal terminal of the second coil unit is connected to the internal terminal of the third coil unit via a second connecting wire ; The first coil unit, the second coil unit and the third coil unit are arranged at intervals to form a rectangular structure as a whole. 10 . The structure of the metal foreign object detection coil according to claim 7 , wherein the three coil units are respectively a first coil unit, a second coil unit and a third coil unit; 10 . The second coil unit is wound by a single line segment into an isosceles triangle coil structure and has opposite first hypotenuse portions and second hypotenuse portions, and opposite ends of the second coil unit respectively form an inscribed end and a external terminal; The first coil unit is wound by a single line segment into a right-angled triangle coil structure and includes a hypotenuse portion, the hypotenuse portion is located outside the first hypotenuse portion of the second coil unit and is parallel to the first hypotenuse portion, The opposite ends of the first coil unit respectively form an inner end and an outer end; The third coil unit is wound by a single line segment into a right-angled triangle coil structure and includes a hypotenuse portion, the hypotenuse portion is located outside the second hypotenuse portion of the second coil unit and is parallel to the second hypotenuse portion, The opposite ends of the third coil unit respectively form an inner end and an outer end; The internal terminal of the first coil unit is connected to the internal terminal of the third coil unit via a first connecting wire, and the external terminal of the first coil unit is connected to the internal terminal of the second coil unit via a second connecting wire end; The first coil unit, the second coil unit and the third coil unit are arranged at intervals to form a fan-shaped structure as a whole.

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