coil

Abstract

To provide a coil that has the coil size specified in the international standard of wireless power feeding to electric automobiles and that is resonated at a frequency specified in a standard.SOLUTION: A coil for power transmission or power reception for wireless power feeding has external connection terminals provided at both ends. The external connection terminals are not connected with a capacitor. At least three wound parts around each of which a conductor is wound a predetermined number of times are provided between the external connection terminals. One place in the plurality of wound parts is open, and the conductors can be separated at the open place. In transmitting or receiving power, the coil is resonated in a frequency band used to wirelessly feed power to a mobile body driven by using stored power as motive power.SELECTED DRAWING: Figure 2A

Description

[Technical Field]

[0001] The present invention relates to a coil. [Background technology]

[0002] In wireless power transmission, a capacitor's capacitance C is required to resonate with the coil's inductance L. It is known that achieving this resonance can achieve high efficiency and large power. However, using a capacitor is costly. Therefore, it is possible to use a self-resonant coil that uses open-type stray capacitance, commonly known as a capacitorless coil (see Non-Patent Document 1, etc.). [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] "Initial Study on Capacitor-less Power Transmission System Using 85kHz Self-Resonant Open-Type Coil for Wireless Power Transfer in Motion", Koichi Furusato, Takehiro Imura, Yoichi Hori, IEICE Technical Report: IEICE Technical Report 116(238), pp25-30, 2016-10-06 Summary of the Invention [Problem to be solved by the invention]

[0004] In order to resonate at the international standard of 85 kHz with a two-layer open coil, the coil size must be large to ensure stray capacitance and inductance. With a two-layer open coil, the coil size restrictions imposed by the international standard (SAE-J2954) that stipulates wireless power transfer to electric vehicles while parked mean that it is not possible to resonate at 85 kHz, the frequency specified for wireless power transfer to electric vehicles. In other words, in order to resonate at 85 kHz with a two-layer open coil, the coil size must be large, larger than the coil size required by the international standard.

[0005] The present invention has been made in consideration of the above points, and aims to provide a coil that has a coil size specified in the international standard for wireless power supply to electric vehicles and that resonates at a frequency specified in the standard. [Means for solving the problem]

[0006] The coil according to the first aspect of the present invention is a coil for transmitting or receiving power wirelessly, which has external connection terminals on both ends, which are not connected to a capacitor, and which has at least three winding sections between the external connection terminals, each with a conductor wound a predetermined number of times, one of the winding sections being open, and which is formed so that the conductor can be separated at the open section, and which resonates in a frequency band used when wirelessly supplying power to a mobile body that is driven by stored electricity when transmitting or receiving power.

[0007] A coil according to a second aspect of the present invention is a coil for transmitting or receiving power wirelessly, which has external connection terminals on both ends, the external connection terminals not connected to a capacitor, at least two winding sections in which a conductor is wound a predetermined number of times between the external connection terminals, one of the plurality of winding sections is open, and when transmitting or receiving power, the coil resonates in a frequency band used when wirelessly supplying power to a mobile body that is driven by stored power, and the at least two winding sections are formed in the same layer, with one of the conductors and the other conductor wound in opposite directions to each other.

[0008] A coil according to a third aspect of the present invention is the coil according to the first or second aspect, and has a size equal to or smaller than the size defined for wireless power supply to the moving object.

[0009] A coil according to a fourth aspect of the present invention is the coil according to any one of the first to third aspects, wherein the frequency band is a frequency band used when wirelessly supplying power to the moving object while it is stopped.

[0010] A coil according to a fifth aspect of the present invention is the coil according to the fourth aspect, wherein the frequency band is an 85 kHz band.

[0011] A coil according to a sixth aspect of the present invention is the coil according to any one of the first to fifth aspects, wherein the winding portions are stacked at predetermined intervals.

[0012] A coil according to a seventh aspect of the present invention is the coil according to any one of the first to sixth aspects, wherein the moving body is an electric vehicle.

[0013] A coil according to an eighth aspect of the present invention is a coil according to any one of the first to seventh aspects, and is a square coil. [Effects of the Invention]

[0014] According to the present invention, at least three winding sections are provided in which a conductor is wound a predetermined number of times, and one of the multiple winding sections is open, thereby making it possible to provide a coil that has a coil size specified in the international standard for wireless power supply to electric vehicles and that resonates at a frequency specified in the standard. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a diagram illustrating an example of an open-type coil. [Figure 2A] 1 is a diagram showing a coil according to an embodiment of the present invention; [Figure 2B] 1 is a diagram showing a coil according to an embodiment of the present invention; [Figure 3A] 10 is a modified example of the coil according to the embodiment of the present invention. [Figure 3B] 10 is a modified example of the coil according to the embodiment of the present invention. [Figure 4] 10 is a modified example of the coil according to the embodiment of the present invention. [Figure 5] 10 is a modified example of the coil according to the embodiment of the present invention. [Figure 6] 10 is a modified example of the coil according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0016] An example of an embodiment of the present disclosure will be described below with reference to the drawings. The same reference numerals are used throughout the drawings to designate identical or equivalent components and parts. The dimensional proportions of the drawings are exaggerated for illustrative purposes and may differ from the actual proportions.

[0017] First, an overview of the open-type coil will be described.

[0018] FIG. 1 is a diagram showing an example of an open-type coil. The coil 10 shown in FIG. 1 is composed of two conductors 12 and 22, and has an open-type structure in which the two conductors 12 and 22 are not connected. Furthermore, no capacitors are connected to external connection terminals 11 and 21 for supplying current from the outside to the conductors 12 and 22, respectively. An open-type coil is a coil that can self-resonate even without a capacitor connected due to its own stray capacitance. In other words, when a current flows through the coil 10 shown in FIG. 1, the coil 10 generates a magnetic field.

[0019] Conductor wire 12 is wound clockwise, starting from external connection terminal 11. On the other hand, conductor wire 22 is wound counterclockwise, starting from external connection terminal 21. In this way, in an open-type coil, the winding directions of each conductor wire are opposite. In the following explanation, a wound conductor wire is defined as one winding section. The coil shown in Figure 1 has two winding sections.

[0020] The conductors 12 and 22 of the coil 10 shown in Fig. 1 are each wound in a single layer. The winding pattern of the conductors 12 and 22 shown in Fig. 1 is a schematic illustration, and the winding pattern and number of windings can be changed depending on the desired frequency of resonance, etc.

[0021] To prevent the depletion of power stored in the batteries of electric vehicles, which are becoming increasingly common, wireless power transfer technology for charging the batteries of electric vehicles is being developed. In order to transfer power to electric vehicles wirelessly, the coils used for wireless power transfer must be made smaller.

[0022] However, as shown in Fig. 1, in an open-type coil 10 consisting of two windings of single-layer wound conductor wires 12 and 22, the size must be increased in order to resonate at 85 kHz, the frequency specified for wireless power supply to electric vehicles. However, the international standard (SAE-J2954) for wireless power supply to electric vehicles while parked imposes restrictions on the size of the coil. Specifically, SAE-J2954 imposes a restriction of 650 mm x 500 mm or less on the size of a coil that supplies wireless power while the vehicle is parked, as an example.

[0023] Therefore, in the embodiment of the present invention described below, in order to resonate particularly in the tens of kilohertz band and to keep the coil size below a predetermined size, a coil with three or more winding sections is shown, where the wound conductor is one winding section.

[0024] 2A and 2B are diagrams showing a coil according to an embodiment of the present invention. Coil 100 shown in Figures 2A and 2B is a coil used to supply power to a mobile object driven by stored electric power, particularly an electric vehicle.

[0025] 2A and 2B is made up of two conductors 110 and 120, and has an open-type structure in which the two conductors 110 and 120 are not connected. Furthermore, no capacitors are connected to external connection terminals 111 and 121 for supplying current from the outside to the conductors 110 and 120, respectively. In other words, the coil 100 is an open-type capacitorless coil. Furthermore, the coil 100 is formed so that the two conductors 110 and 120 can be separated at the open portion.

[0026] Conductor 110 has two winding portions 112A and 112B. That is, conductor 110 has a two-layer structure. Conductor 120 has two winding portions 122A and 122B. That is, conductor 120 has a two-layer structure. Therefore, coil 100 has a four-layer structure as a whole.

[0027] In FIG. 2B, the locations indicated by black dots on the conductors 110 and 120 are actually connected.

[0028] Conductive wire 110 is wound clockwise around external connection terminal 111 as a starting point. Specifically, in winding section 112A, conductor 110 is wound clockwise from the outside to the inside around external connection terminal 111 as a starting point, and in winding section 112B, conductor 110 is wound clockwise from the inside to the outside. On the other hand, conductor 120 is wound counterclockwise around external connection terminal 121 as a starting point. Specifically, in winding section 122A, conductor 120 is wound counterclockwise from the outside to the inside around external connection terminal 121 as a starting point, and in winding section 122B, conductor 120 is wound counterclockwise from the inside to the outside. In this way, in an open-type coil, the winding directions of the respective conductors are opposite to each other.

[0029] 2A and 2B, coil 100 according to this embodiment can resonate at a predetermined frequency band, particularly at a frequency in the 85 kHz band, which is a frequency specified for wireless power supply to electric vehicles. Furthermore, coil 100 according to this embodiment can be manufactured to a predetermined size, particularly a size equal to or smaller than the size specified for a coil that supplies wireless power while the vehicle is parked, by having the configuration shown in FIGS.

[0030] In Figures 2A and 2B, the conductors 110 and 120 are evenly wound, but the present invention is not limited to this example. The number of windings in the conductors 110 and 120 may be varied. Also, in Figures 2A and 2B, the conductors 110 and 120 each have two windings, but the present invention is not limited to this example. For example, the two conductors may have different numbers of windings. Specifically, the conductor 110 may have one winding, and the conductor 120 may have two windings.

[0031] 2A and 2B, the conductors 110 and 120 are wound in a square shape, but the present invention is not limited to this example. The conductors 110 and 120 may be wound in other shapes, for example, in a circular shape.

[0032] Furthermore, the winding portions of the conductor wires 110 and 120 may be formed so that they are in the same layer by being wound in opposite directions. FIG. 3 shows a modified example of a coil according to an embodiment of the present invention. FIG. 3 is a plan view of a coil 100 showing how the conductor wires 110 and 120 are wound in opposite directions to be in the same layer. When the conductor wires 110 and 120 are wound in opposite directions, it is necessary to cross the conductor wires 110 and 120 at some points. For example, by crossing the conductor wires 110 and 120 at crossing points 130A and 130B, the coil 100 can be fabricated so that the conductor wires 110 and 120 are wound in opposite directions to be in the same layer.

[0033] FIG. 4 shows a modified example of a coil according to an embodiment of the present invention. FIG. 4 shows a perspective view and a plan view of coil 200, illustrating how conductor wires 210, 220A, 220B, and 230 are wound in opposite directions to form the same layer. Note that conductor wires 210 and 220B are connected at a black dot, and conductor wire 220A and 230 are connected at a black dot. When conductor wires 210, 220A, 220B, and 230 are wound in opposite directions, it is necessary to cross conductor wires 210, 220A, 220B, and 230 in some places. By crossing the conductor wires as shown on the right side of FIG. 4, coil 200 can be fabricated so that conductor wires 210, 220A, 220B, and 230 are wound in opposite directions to form the same layer.

[0034] FIG. 5 shows a modified example of a coil according to an embodiment of the present invention. FIG. 5 shows a perspective view and a plan view of coil 300, illustrating how conductor wires 310, 320, 330, and 340 are wound in opposite directions to form the same layer. Note that conductor wires 310 and 320 are connected at black dots, and conductor wires 330 and 340 are connected at black dots. When conductor wires 310, 320, 330, and 340 are wound in opposite directions, it is necessary to cross conductor wires 310, 320, 330, and 340 in some places. By crossing the conductor wires as shown on the right side of FIG. 5, coil 300 can be fabricated so that conductor wires 310, 320, 330, and 340 are wound in opposite directions to form the same layer.

[0035] Fig. 6 shows a modified example of a coil according to an embodiment of the present invention. Fig. 6 shows a perspective view and a plan view of a coil formed by stacking coils 400A and 400B, which are fabricated to be in the same layer. Coils 400A and 400B are both fabricated to be in the same layer by winding two conductors in opposite directions, as shown in Fig. 3.

[0036] Coil 100 according to this embodiment and coils 200, 300, 400A, and 400B according to the modifications can be resonated at a frequency in the 85 kHz band, which is the frequency specified for wireless power supply to electric vehicles, and can be fabricated to a size equal to or smaller than the international standard for wireless power supply to electric vehicles, making them suitable for use in wireless power supply systems for electric vehicles. When coils 100, 200, 300, and 400 are applied to wireless power supply systems for electric vehicles, coils 100, 200, 300, and 400 are provided at the bottom of the electric vehicle and buried in the location where the electric vehicle is parked. [Explanation of symbols]

[0037] 100 coils 110, 120 conductor 111, 121 External connection terminals 112A, 112B, 122A, 122B winding section

Claims

1. A coil for transmitting or receiving power for wireless power supply, External connection terminals are provided on both ends, the external connection terminal is not connected to a capacitor, At least three winding portions are provided between the external connection terminals, each of which has a conductor wound a predetermined number of times; One of the plurality of winding portions is open, and the conductor is formed so as to be separated at the open portion; A coil that resonates in the frequency band used when wirelessly supplying power to a mobile object powered by stored electricity during transmission or reception.

2. A coil for transmitting or receiving power for wireless power supply, External connection terminals are provided on both ends, the external connection terminal is not connected to a capacitor, At least two winding portions are provided between the external connection terminals, each having a conductor wound a predetermined number of times; The plurality of winding portions intersect at an intersection portion, One of the plurality of winding portions is open, When transmitting or receiving electricity, the device resonates at the frequency band used when wirelessly supplying power to a mobile object powered by the stored power. At least two of the winding portions are formed in the same layer with one of the conductors and the other of the conductors wound in opposite directions.

3. 3. The coil according to claim 1, wherein the frequency band is an 85 kHz band.

4. The coil according to any one of claims 1 to 3, wherein the winding portions are stacked at predetermined intervals.

5. The coil according to any one of claims 1 to 4, wherein the moving body is an electric vehicle.

6. The coil according to any one of claims 1 to 5, which is a rectangular coil.

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