Wireless power transmission system and power transmission coil

Abstract

To provide a wireless power transmission system which reduces introduction cost and reduces a leakage magnetic field without reducing the mechanical strength of a coil.SOLUTION: A wireless power transmission system comprises: at least two power transmission coils each including a coil, around which a conductor wire is wound and in which power is transmitted by generating a magnetic field, and a lead wire which causes a current to flow to the conductor wire; and a power transmission device which transmits power to the lead wires. The power transmission coils are disposed in a predetermined direction in such a manner that the coils have a predetermined interval therebetween, and the lead wire has such a shape that encloses the peripheries of the coil connected thereto and one or more other coils disposed adjacently.SELECTED DRAWING: Figure 5

Description

Technical Field

[0004] , , , , , , , , , ,

[0005] ,

[0003]

[0001] The present disclosure relates to a wireless power transmission system and a power transmission coil.

Background Art

[0002] [[ID=I1]] Techniques related to wireless power supply during driving, which wirelessly transmits power to an electric vehicle in motion, have been proposed. In wireless power supply during driving, a leakage magnetic field is generated. From the perspective of human protection or the safety of peripheral devices, regulatory values for the leakage magnetic field are defined by the Radio Law, CISPR (International Special Committee on Radio Interference), etc., and the practical application of wireless power supply during driving is not possible unless it is below the regulatory value. Therefore, techniques for reducing the leakage magnetic field have been disclosed.

[0003] Non-Patent Document 1 discloses a technique for suppressing the leakage magnetic field from the main power transmission coil by newly installing a cancellation coil with respect to the main power transmission coil. The technique of Non-Patent Document 1 can bring a high cancellation effect of the leakage magnetic field by installing a cancellation coil with respect to the main power transmission coil. <|

[0004] Non-Patent Document 2 discloses a technique of winding a shielding coil around a coil that performs power transmission. The technique of Non-Patent Document 2 cancels the leakage magnetic field by winding a shielding coil around the coil.

Prior Art Documents

Non-Patent Documents

[0005]

Non-Patent Document 1

[0006] However, as with conventional technology, if cancellation coils are newly embedded in addition to the coils used for power transmission to reduce leakage magnetic fields, or if complex shielding is mounted on the coils, it leads to a significant increase in initial investment costs and a decrease in the mechanical strength of the coils due to the increase in coil thickness.

[0007] This disclosure has been made in view of the above points, and aims to provide a wireless power transmission system and power transmission coil that reduce implementation costs and reduce leakage magnetic fields from coils without reducing the mechanical strength of the coils, compared to conventional technology. [Means for solving the problem]

[0008] A wireless power transmission system according to a first aspect of the present disclosure comprises at least two power transmission coils, each having a conductor wound around it for transmitting power by generating a magnetic field, and a lead wire for carrying current through the conductor; and a power transmission device for transmitting power to each of the lead wires, wherein each of the power transmission coils is arranged along a predetermined direction such that each of the coils is spaced apart, and the lead wires are shaped to surround the connected coil and at least one other coil that is adjacent to it.

[0009] A wireless power transmission system according to a second aspect of this disclosure is a wireless power transmission system according to a first aspect, wherein the coil has the conductor wound in a rectangular shape.

[0010] A wireless power transmission system according to a third aspect of this disclosure is a wireless power transmission system according to a first aspect, wherein the coil has a plurality of configurations in which the conductor is wound in a rectangular shape.

[0011] A wireless power transmission system according to a fourth aspect of this disclosure is a wireless power transmission system according to a first aspect, wherein the coil has the conductor wound in a circular shape.

[0012] A wireless power transmission system according to a fifth aspect of this disclosure is a wireless power transmission system according to a first aspect, wherein the distance between the lead wire and the coil is such that the leakage magnetic field measured at a predetermined distance from the coil when the coil generates a magnetic field is less than or equal to a predetermined threshold.

[0013] A wireless power transmission system according to a sixth aspect of this disclosure is a wireless power transmission system according to a first aspect, wherein each coil transmits power to an electrically driven mobile body using a magnetic field generated by power transmission from the power transmission device.

[0014] A wireless power transmission system according to a seventh aspect of this disclosure is a wireless power transmission system according to a sixth aspect, wherein each of the coils of each power transmission coil is arranged at a predetermined interval along the direction of travel of the moving body.

[0015] The wireless power transmission system according to the eighth aspect of this disclosure is a wireless power transmission system according to the sixth or seventh aspect, wherein the mobile body is an electric vehicle powered by electricity.

[0016] A wireless power transmission system according to the ninth aspect of this disclosure is a wireless power transmission system according to the sixth or seventh aspect, wherein each of the transmission coils is embedded in the road.

[0017] A wireless power transmission system according to a tenth aspect of the present disclosure is a wireless power transmission system according to a sixth or seventh aspect, further comprising a moving object detection unit that detects the approach of a moving object when the power transmission device is transmitting power to one of the power transmission coils and another power transmission coil generates a current in response to a magnetic field generated from the lead wire.

[0018] A wireless power transmission system according to the 11th aspect of this disclosure is a wireless power transmission system according to the 10th aspect, wherein the power transmission device switches to transmitting power to the power transmission coil using the current generated by another power transmission coil.

[0019] A wireless power transmission system according to a twelfth aspect of this disclosure is a wireless power transmission system according to a first aspect, further comprising a phase shift circuit that shifts the phase of the current flowing through the lead wire from the phase of the current flowing through the coil.

[0020] A power transmission coil according to a thirteenth aspect of the present disclosure comprises a coil around which a conductor is wound to transmit power by generating a magnetic field, and a lead wire for carrying current through the conductor, wherein the lead wire has a shape that surrounds the coil and at least one other coil arranged in a predetermined direction at a predetermined interval. [Effects of the Invention]

[0021] According to this disclosure, it is possible to provide a wireless power transmission system and a power transmission coil that reduce installation costs and leakage magnetic fields without reducing the mechanical strength of the coil, compared to conventional technologies.

Brief Description of the Drawings

[0022] [Figure 1] It is a diagram showing a schematic configuration of a power transmission coil according to an embodiment of the present disclosure. [Figure 2A] It is a diagram schematically showing a plane of the power transmission coil. [Figure 2B] It is a diagram schematically showing a plane of the power transmission coil. [Figure 3] It is a plan view showing a state where a plurality of power transmission coils are arranged. [Figure 4] It is a graph showing the effect of reducing the leakage magnetic field by the power transmission coil according to the embodiment. [Figure 5] It is a graph showing the effect of reducing the leakage magnetic field by the power transmission coil according to the embodiment. [Figure 6] It is a diagram showing a configuration example of a wireless power transmission system according to the embodiment. [Figure 7] It is a diagram showing a configuration example of a wireless power transmission system according to the embodiment. [Figure 8] It is a diagram showing a configuration example of a wireless power transmission system according to the embodiment. [Figure 9] It is a diagram showing a configuration example of a wireless power transmission system according to the embodiment. [Figure 10] It is a diagram showing a configuration example of a wireless power transmission system according to the embodiment. [Figure 11] It is a diagram showing a state where a phase shift circuit is sandwiched between the coil and the lead wire of the power transmission coil.

Modes for Carrying Out the Invention

[0023] Hereinafter, an example of an embodiment of the present disclosure will be described with reference to the drawings. In each drawing, the same or equivalent components and parts are given the same reference numerals. Also, the dimensional ratios in the drawings are exaggerated for the convenience of explanation and may be different from the actual ratios.

[0024] Figure 1 is a diagram showing a schematic configuration of a power transmission coil according to an embodiment of the present disclosure. The power transmission coil 10 according to this embodiment includes a coil 11 around which a conductor is wound to transmit power by generating a magnetic field, and a lead wire 12 that carries current from a power supply device (not shown) through the conductor. The coil 11 transmits power to a power receiving coil 20 mounted on a vehicle (not shown) by electromagnetic induction in a non-contact manner.

[0025] As shown in Figure 1, the power transmission coil 10 according to this embodiment has a shape such that the lead wires 12 can surround portions of the coils 11 of multiple power transmission coils 10. In this embodiment, the shape of the coil 11 of the power transmission coil 10 according to this embodiment is such that the conductor is wound in a rectangular shape, but this disclosure is not limited to this example. For example, multiple coils 11 with conductors wound in a rectangular shape may be formed for one power transmission coil 10. The shape of the coil 11 may be rectangular or circular. If it is formed in a circular shape, the shape of the coil 11 may be a perfect circle or an ellipse.

[0026] Figures 2A and 2B are schematic diagrams showing the plan view of the power transmission coil 10. The power transmission coils 10 shown in Figures 2A and 2B have different winding directions for the coil 11. In Figures 2A and 2B, the direction of the current flowing through the coil 11 and the direction of the current flowing through the lead wire 12 are indicated by arrows. As shown in Figures 2A and 2B, the direction of the current flowing through the coil 11 and the direction of the current flowing through the lead wire 12 are opposite.

[0027] When transmitting power from the transmitting coil 10 to the receiving coil 20 in a non-contact manner, a sinusoidal alternating current flows through the coil 11 in a constant direction. This sinusoidal current generates a magnetic field in its surroundings, but by reversing the direction of the current, this magnetic field can be canceled out.

[0028] As shown in Figures 2A and 2B, the direction of the current flowing through coil 11 and the direction of the current flowing through lead wire 12 are opposite. This allows the leakage magnetic field generated by the current flowing through coil 11 to be attenuated by the magnetic field generated by the current flowing through lead wire 12. The leakage magnetic field is a value measured at point A, for example, at a predetermined distance in the X-axis direction from the center of coil 11, as shown in Figure 1. The leakage magnetic field at point A must be below a predetermined regulatory value. The predetermined distance is, for example, 10 meters.

[0029] Therefore, it is desirable that the distance between the coil 11 and the lead wire 12 be such that when the coil 11 generates a magnetic field, the leakage magnetic field measured at a predetermined distance from the coil 11 (for example, point A in Figure 1) is below a predetermined threshold.

[0030] Furthermore, since the power transmission coil 10 has a shape such that the lead wires 12 can surround the coil 11 portions of multiple power transmission coils 10, by arranging other power transmission coils 10 so that the coil 11 portions are contained within the area surrounded by the lead wires 12, it is possible to enhance the leakage magnetic field attenuation effect. In addition, from the viewpoint of enabling vehicle detection, the lead wires 12 of the power transmission coil 10 are structured to surround the coil 11 portions of other power transmission coils 10, but this disclosure is not limited to this example. Even without surrounding the coil 11 portions of other power transmission coils 10, a magnetic field cancellation effect can be generated by making the lead wires 12 longer.

[0031] Figure 3 is a plan view showing the arrangement of multiple power transmission coils 10. Figure 3 also shows a vehicle 100 receiving power from the power transmission coils 10. Each power transmission coil 10 shown in Figure 3 is assumed to have current flowing in the direction shown in Figure 2. In the example in Figure 3, the lead wires 12 are shaped to surround the coil 11 portions of the three power transmission coils 10. In the case of large vehicles, power may be supplied from multiple power transmission coils 10, and even when multiple consecutive power transmission coils 10 are transmitting power, the effect of reducing the leakage magnetic field can be maintained. In the example in Figure 3, the leakage magnetic field from the coil 11 can be attenuated by a maximum of three lead wires 12.

[0032] Figure 4 is a graph showing the effect of reducing leakage magnetic field by the power transmission coil 10 according to this embodiment. The graph in Figure 4 shows the leakage magnetic field from the power transmission coil 10, along with the non-contact power transmission efficiency of the power transmission coil 10. The left vertical axis of the graph in Figure 4 is the value of the non-contact power transmission efficiency, and the right vertical axis is the value of the magnetic field strength measured at a predetermined distance in the X-axis direction from the power transmission coil 10 (point A in Figure 1). The horizontal axis is the number of coils 11 surrounded by the lead wire 12. Note that the graph in Figure 4 is compared using the same power receiving coil and receiving the same power. In other words, the received power is unified.

[0033] As shown in the graph in Figure 4, the strength of the magnetic field measured at a predetermined distance in the X-axis direction from the power transmission coil 10 (point A in Figure 1) decreases as the number of coils 11 surrounded by the lead wire 12 increases. Therefore, by installing the lead wire 12 of the power transmission coil 10 to surround the coils 11 of other power transmission coils 10, the leakage magnetic field generated from the power transmission coil 10 can be reduced.

[0034] Figure 5 is a graph showing the effect of reducing the leakage magnetic field by the power transmission coil 10 according to this embodiment. The graph shown in Figure 5 plots the relationship between the shortest distance between the coil 11 and the lead wire 12, the non-contact power transmission efficiency of the power transmission coil 10, and the leakage magnetic field caused by the power transmission coil 10.

[0035] As shown in the graph in Figure 5, the relationship between the shortest distance between the coil 11 and the lead wire 12 and the leakage magnetic field due to the power transmission coil 10 is lowest at a certain distance, and the leakage magnetic field due to the power transmission coil 10 increases as the shortest distance increases. Therefore, the shortest distance between the coil 11 and the lead wire 12 can be determined such that the leakage magnetic field due to the power transmission coil 10 is below the regulated value of the magnetic field strength, while satisfying the constraints of the mechanical strength of the coil 10 and the wiring of the lead wire 12.

[0036] Furthermore, since there is no need to newly bury cancellation coils or mount complex shielding on the coil as in conventional technology, the power transmission coil 10 can reduce leakage magnetic fields without lowering the introduction cost and reducing the mechanical strength of the coil.

[0037] Next, we will explain a specific example of the configuration of a wireless power transmission system using the power transmission coil 10.

[0038] Figure 6 shows an example configuration of a wireless power transmission system according to an embodiment of the present disclosure. Figure 6 shows a wireless power transmission system comprising a plurality of power transmission coils 10 embedded in a road 1, a resonant circuit 30 provided one for each power transmission coil 10, and an inverter 40 that converts a direct current supplied from a DC power source (not shown) through a power transmission line 50 into an alternating current and supplies it to the power transmission coils 10. The inverter 40 is an example of a power transmission device according to the present disclosure.

[0039] In this embodiment, the resonant circuit 30 is composed of an LCC circuit comprising one coil and two capacitors, but the configuration of the resonant circuit 30 is not limited to this example in this disclosure. In the example of Figure 6, the lead wire 12 of one power transmission coil 10 is arranged to surround the coils 11 of the other two power transmission coils 10.

[0040] In the example shown in Figure 6, one inverter 40 is connected to three power transmission coils 10. The inverter 40 supplies current to each of the three power transmission coils 10 simultaneously or separately, generating a magnetic field from the power transmission coils 10, which then wirelessly transmits power to an electric vehicle traveling on road 1.

[0041] As shown in Figure 6, when the power transmission coils 10 and inverter 40 are connected, power consumption increases if current is always supplied to all power transmission coils 10. Since electric vehicles are not always located above all power transmission coils 10, it is desirable to avoid supplying current to power transmission coils 10 that do not require wireless power transmission.

[0042] Therefore, the wireless power transmission system according to this embodiment further includes a mobile object detection unit 60. The mobile object detection unit 60 can be implemented, for example, as a computer with a communication function with the inverter 40. The mobile object detection unit 60 detects when an electric vehicle powered by electricity approaches as a mobile object. The inverter 40 controls the switching of the power transmission coil 10 that supplies current according to the detection result of the mobile object detection unit 50.

[0043] This section describes a method for detecting a moving object using a wireless power transmission system according to this embodiment. For example, consider a case where three power transmission coils 10 are arranged as shown in Figure 3, and the moving object travels from right to left in the figure. For the sake of explanation, the power transmission coils 10 shown in Figure 3 will be described as the first power transmission coil, the second power transmission coil, and the third power transmission coil, in order from right to left. That is, in the example in Figure 3, the first power transmission coil, the second power transmission coil, and the third power transmission coil are arranged from right to left along the direction of travel of the vehicle.

[0044] When current flows through the first transmission coil, the magnetic field generated by the current flowing through the lead wires of the first transmission coil passes through the coils of the second and third transmission coils. When the magnetic field passes through the coils, a current is generated by electromagnetic induction. In other words, the inverter 40 detects the current generated by each coil of the second and third transmission coils, which indicates that the moving object is in close proximity to the second and third transmission coils.

[0045] When the inverter 40 detects the current generated by each power transmission coil 10 through electromagnetic induction, it notifies the mobile object detection unit 60 which power transmission coil 10 generated the current through electromagnetic induction. In response to the notification from the inverter 40, the mobile object detection unit 60 determines which power transmission coil 10 should receive current from the DC power supply and notifies each inverter 40 of the decision.

[0046] By having the inverter 40 and the moving object detection unit 60 perform the operations described above, the wireless power transmission system according to this embodiment can detect the proximity of a moving object without providing any separate sensors. Alternatively, a power semiconductor such as a MOSFET may be placed between the resonant circuit 30 and the inverter 40 to automatically switch between energization and isolation by switching the power semiconductor in response to the detection of induced electromotive force. By switching the power semiconductor to automatically switch between energization and isolation, the switching of the power transmission coil 10 that transmits power can be performed automatically using only the properties of electricity, without external control.

[0047] In the example shown in Figure 6, one inverter 40 is connected to three transmission coils 10, and one inverter 40 supplies current to the three transmission coils 10, but the disclosure is not limited to this example. Another example of a wireless power transmission system using transmission coils 10 is shown.

[0048] Figure 7 shows an example configuration of a wireless power transmission system according to an embodiment of the present disclosure. In the example in Figure 7, the lead wire 12 of one power transmission coil 10 is arranged to surround the coils 11 of the other two power transmission coils 10.

[0049] In the example shown in Figure 7, one inverter 40 is connected to one power transmission coil 10. The inverter 40 supplies current to the power transmission coil 10, which generates a magnetic field from the power transmission coil 10, enabling wireless power transmission to an electric vehicle traveling on road 1.

[0050] Figure 8 shows an example configuration of a wireless power transmission system according to an embodiment of the present disclosure. In the example in Figure 8, the lead wires 12 of one power transmission coil 10 are arranged to surround the coil 11 of another power transmission coil 10.

[0051] In the example shown in Figure 8, one inverter 40 is connected to three power transmission coils 10. The inverter 40 supplies current to the three power transmission coils 10, generating a magnetic field from the coils 10, which then wirelessly transmits power to an electric vehicle traveling on road 1.

[0052] Figure 9 shows an example configuration of a wireless power transmission system according to an embodiment of the present disclosure. In the example of Figure 9, the lead wires 12 of one power transmission coil 10 are arranged to surround the coil 11 of another power transmission coil 10.

[0053] In the example shown in Figure 9, one inverter 40 is connected to one power transmission coil 10. The inverter 40 supplies current to the power transmission coil 10, which generates a magnetic field from the power transmission coil 10, enabling wireless power transmission to an electric vehicle traveling on road 1.

[0054] As described above, several patterns have been given to illustrate the configuration examples of the wireless power transmission system according to the embodiment of this disclosure. However, the arrangement patterns of the power transmission coils 10 are not limited to these examples. As long as the lead wires 12 of one power transmission coil 10 are arranged to surround the coil 11 of another power transmission coil 10, the wireless power transmission system according to the embodiment of this disclosure can adopt various arrangement patterns of the power transmission coils 10. As mentioned above, even without surrounding the coil 11 of another power transmission coil 10, a magnetic field cancellation effect can be produced by making the lead wires 12 long.

[0055] Furthermore, in order to embed the power transmission coil 10 in the road 1, a trench will need to be formed in the road 1. Figure 10 is a diagram showing an example configuration of a wireless power transmission system according to the present disclosure, and in addition to the configuration example shown in Figure 6, it illustrates the location of the trench 2 dug in the road 1 for embedding the power transmission coil 10 in the road 1. Of course, it goes without saying that the location and shape of the trench 2 can be arbitrary.

[0056] Since the current flowing through coil 11 of the transmission coil 10 and the current flowing through lead wire 12 are the same, they cancel out the leakage magnetic field generated by coil 11 of the transmission coil 10. However, by inserting a phase shift circuit between coil 11 and lead wire 12, the phase of the current flowing through coil 11 and the phase of the current flowing through lead wire 12 are slightly shifted, but the phase of the current flowing through coil 11 approaches the phase of the current flowing through the receiving coil of the mobile unit. As the phase of the current in the transmission coil approaches the phase of the current in the receiving coil, it leads to cancellation that takes into account the magnetic field strength from both the transmission and receiving sides.

[0057] Figure 11 shows a phase shift circuit 13 inserted between the coil 11 and the lead wire 12 of the power transmission coil 10, which shifts the phase of the current flowing through the lead wire 12 from the phase of the current flowing through the coil 11. The phase shift circuit 13 consists of, for example, a capacitor and a capacitor, and can be configured in any way to shift the phase of the current flowing through the lead wire 12. By inserting the phase shift circuit 13 between the coil 11 and the lead wire 12, the power transmission coil 10 can perform cancellation considering the magnetic field strength from both the transmitting and receiving sides.

[0058] As described above, the power transmission coil 10 and the wireless power transmission system equipped with the power transmission coil 10 according to the embodiments of this disclosure can reduce leakage magnetic fields without requiring additional equipment or systems. The power transmission coil 10 according to the embodiments of this disclosure can adjust the effect of reducing leakage magnetic fields by adjusting the length of the lead wires 12.

[0059] Wireless power transmission using a wireless power transmission system controls power at a power supply facility installed along the roadside and supplies power by extending AC wiring that carries alternating current to a coil buried in the center of the road. Generally, AC wiring is highly dangerous from the standpoint of the risk of electric shock and the generation of magnetic fields, and it is undesirable to extend it over long distances. The wireless power transmission system according to the embodiment of this disclosure makes effective use of AC wiring and does not require additional elements to reduce leakage magnetic fields.

[0060] Furthermore, the power transmission coil 10 according to the embodiment of this disclosure can suppress not only distant leakage magnetic fields but also nearby magnetic fields, and is effective against harmonics emitted from the power transmission coil 10. In addition, a wireless power transmission system equipped with the power transmission coil 10 according to the embodiment of this disclosure can also be applied to vehicle detection.

[0061] While embodiments of the present disclosure have been described in detail above with reference to the attached drawings, the technical scope of the present disclosure is not limited to these examples. It is clear that a person with ordinary skill in the art of the present disclosure may conceive of various modifications or alterations within the scope of the technical idea set forth in the claims, and these modifications or alterations are also understood to fall within the technical scope of the present disclosure.

[0062] Furthermore, the effects described in the above embodiments are descriptive or illustrative, and are not limited to those described in the above embodiments. In other words, the technology relating to this disclosure may produce other effects that would be obvious to a person of ordinary skill in the art of this disclosure from the descriptions in the above embodiments, in addition to or in lieu of the effects described in the above embodiments. [Explanation of Symbols]

[0063] 1 road 2 grooves 10 Power transmission coil 11 coils 12 Lead wires 20 Power receiving coil 30 Resonant circuit 40 Inverters 50 Power transmission lines 60 Moving object detection unit

Claims

1. A coil is formed by winding a wire to transmit power by generating a magnetic field, A lead wire for conducting current through the aforementioned conductor, At least two power transmission coils comprising, A power transmission device that transmits power to each of the aforementioned lead wires, Equipped with, Each of the power transmission coils is arranged along a predetermined direction such that each coil has a predetermined interval between them. A wireless power transmission system in which the lead wires have a shape that surrounds the coil to which they are connected and at least one other coil that is located adjacent to it.

2. The wireless power transmission system according to claim 1, wherein the coil has the conductor wound in a rectangular shape.

3. The wireless power transmission system according to claim 1, wherein the coil has a plurality of configurations in which the conductor is wound in a rectangular shape.

4. The wireless power transmission system according to claim 1, wherein the coil has the conductor wound in a circular shape.

5. The wireless power transmission system according to claim 1, wherein the distance between the lead wire and the coil is such that the leakage magnetic field measured at a predetermined distance from the coil when the coil generates a magnetic field is below a predetermined threshold.

6. The wireless power transmission system according to claim 1, wherein each coil transmits power to an electrically driven mobile body using a magnetic field generated by power transmission from the power transmission device.

7. The wireless power transmission system according to claim 6, wherein each of the power transmission coils is arranged at a predetermined interval along the direction of travel of the moving body.

8. The wireless power transmission system according to claim 6 or 7, wherein the mobile body is an electric vehicle driven by electricity.

9. Each of the aforementioned power transmission coils is embedded in the road, the wireless power transmission system according to claim 6 or claim 7.

10. The wireless power transmission system according to claim 6 or 7, further comprising a moving object detection unit that detects the approach of a moving object when the power transmission device is transmitting power to one of the power transmission coils, and another power transmission coil generates a current in response to a magnetic field generated from the lead wire.

11. The wireless power transmission system according to claim 10, wherein the power transmission device switches to transmitting power to the other power transmission coil based on the current generated by the other power transmission coil.

12. The wireless power transmission system according to claim 1, further comprising a phase shift circuit that shifts the phase of the current flowing through the lead wire from the phase of the current flowing through the coil.

13. A coil is formed by winding a wire to transmit power by generating a magnetic field, A lead wire for conducting current through the aforementioned conductor, Equipped with, The lead wires are shaped to surround the coil and at least one other coil arranged in a predetermined direction at a predetermined interval, thereby forming a power transmission coil.

Images