JP2020078130A - Power transmission coil, power reception coil, and wireless power feeding system - Google Patents

Abstract

To provide a wireless power feeding system capable of controlling capacity generated in a power transmission coil or a power reception coil.SOLUTION: A wireless power feeding system has two power receiving coils 1A, B and a single power transmitting coil 2. The power transmitting coil 2 is a coil that is wound multiple times in a z-axis direction, and constituted of two working portions 20A, B for each winding, and a connecting portion 21 for connecting the working portion 20A and the working portion 20B. The connecting portion 21 is a portion for connecting the working portion 20A and the working portion 20B, being two linear wires 21a and 21b extending in an x-axis direction. The connecting portion 21 is provided with a control portion 22 for fixing the two wires 21a and 21b so as not to change an interval therebetween.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a wireless power feeding system that wirelessly transmits power by a magnetic field resonance method.

  In recent years, wireless power feeding technology for transmitting power in a contactless manner has been extensively studied and developed. Various wireless power feeding methods have been proposed, such as an electromagnetic induction method and a magnetic field resonance method. Among them, the magnetic field resonance method is drawing attention. The magnetic field resonance method has a high degree of freedom in the relative arrangement of the power transmitting coil and the power receiving coil, and it is possible to arrange a plurality of power receiving coils within the influence range of the power transmitting coil.

  Patent Literature 1 describes a magnetic field resonance type wireless power feeding system, and describes that a power transmission coil is provided with a region in which coil conductors are closely spaced and a region in which coil conductors are sparse. Further, it is described that the parasitic capacitance generated in the coil is determined by the distance between the coil conductors and the potential difference between the coil conductors. Then, it is described that the region connecting the power transmission coil and the external circuit is made a region in which the spacing between the coil conductors is sparse, thereby avoiding the influence of parasitic capacitance.

International Publication No. 2017/169708

  In the power transmission device used in the magnetic field resonance type wireless power feeding system, the resonance frequency is set by the inductance L of the power transmission coil and the capacitance C of the capacitor, and the resonance frequency is similarly set in the power reception device. In the high frequency band, the inductance L is large and the capacitance C is small, so strictness is required to adjust the capacitance C of the capacitor.

  However, depending on the shape and arrangement of the power transmitting coil and the power receiving coil, parasitic capacitance may occur in the coil, causing a shift in the inductance L, which may cause a reduction in power transmission efficiency.

  Therefore, an object of the present invention is to make it possible to control the capacitance generated in a power transmission coil or a power reception coil in a magnetic field resonance type wireless power feeding system.

The present invention relates to a power transmission coil made of a wire for transmitting electric power in a contactless manner by a magnetic field resonance method, in which two wire rods are close to each other at a distance of 1/10 or less of a diameter of the power transmission coil.
A control unit configured to control a distance between the two wire rods in the proximity unit to a predetermined distance, the power transmission coil.

  Further, the present invention provides a power receiving coil made of a wire rod that receives electric power in a contactless manner by a magnetic field resonance method, in which the two wire rods are close to each other at a distance of 1/10 or less of a diameter of the power receiving coil, and the proximity portion. And a control unit that controls the distance between the two wire rods in the unit to a predetermined distance.

  In the present invention, the control unit may fix the distance between the two wire rods to a predetermined distance. It is possible to prevent the parasitic capacitance of the power transmitting coil or the power receiving coil from fluctuating, and even if the shape or arrangement of the power transmitting coil or the power receiving coil is deviated, it is possible to suppress the fluctuation of the inductance of the coil and to improve the power transmission efficiency. Can be suppressed.

  Further, in the present invention, the control unit may change the interval between the two wire rods. The parasitic capacitance of the power transmitting coil or the power receiving coil can be adjusted, and even if the shape of the power transmitting coil or the power receiving coil is displaced or the inductance of the coil fluctuates, the inductance can be adjusted. Alternatively, the shift of the resonance frequency of the power receiving side circuit can be corrected. As a result, it is possible to intentionally change the power transmission efficiency or the power reception efficiency.

  According to the present invention, the parasitic capacitance of the power transmission coil or the power reception coil can be adjusted.

1 is a diagram showing a configuration of a wireless power feeding system according to a first embodiment. FIG. 3 is a diagram showing shapes and arrangements of power receiving coils 1A and 1B and a power transmitting coil 2 in the wireless power feeding system of the first embodiment. The figure which showed the shape and arrangement | positioning of the power receiving coil 1A, 1B and the power transmission coil 2 in the wireless power supply system of Example 2. The figure which showed the structure of the control part 202. The figure which showed the modification of the control part 202. The figure which showed the modification of the control part 202.

  Hereinafter, specific examples of the present invention will be described with reference to the drawings, but the present invention is not limited to the examples.

  FIG. 1 is a diagram illustrating the configuration of the wireless power feeding system according to the first embodiment. As illustrated in FIG. 1, the wireless power feeding system according to the first exemplary embodiment includes two power receiving coils 1A and 1B, one power transmitting coil 2, an AC power source 3 connected to the power transmitting coil 2, a circuit 4, and a power receiving coil 1A. 1B and circuits 5A and 5B respectively connected thereto.

(Configuration of wireless power supply system)
The wireless power feeding system according to the first embodiment is a system that transmits power from one power transmitting coil 2 to two power receiving coils 1A and 1B in a non-contact manner by a magnetic field resonance method. The output of the transmitted power is, for example, 10 W or less.

  The AC power supply 3 is a power supply that supplies an AC current to the power transmission coil 2. The frequency is, for example, 500 kHz to 15 MHz. The circuit 4 is a circuit for setting the resonance frequency on the power transmission side, and is set to have a predetermined frequency depending on the capacitance of the capacitor and the inductance of the inductor. The circuits 5A and 5B are circuits for matching the resonance frequency on the power receiving side with the resonance frequency on the power transmitting side, and are set to have a predetermined frequency depending on the capacitance of the capacitor and the inductance of the inductor. A load (not shown) is connected to the circuits 5A and 5B. If the load is a device driven by DC, the received power is converted to DC and supplied to the load. The load is, for example, a light emitting element.

  The power receiving coils 1A and 1B and the power transmitting coil 2 are made of wire. The wire may be any conductive material, for example, a litz wire or a single copper wire. Further, the pattern is not limited to the wire material, and may be configured by pattern printing on a printed circuit board such as an FPC.

  Next, the shapes and arrangements of the power receiving coils 1A and 1B and the power transmitting coil 2 will be described with reference to FIG. FIG. 2 shows the shape of one coil, and is a view seen from a direction perpendicular to a plane formed by one coil of the power transmission coil 2. For convenience of explanation, a coordinate system is defined as shown in FIG.

(Structure of power receiving coils 1A, 1B)
First, the power receiving coils 1A and 1B will be described. As shown in FIG. 2, the power receiving coils 1A and 1B are arranged at a predetermined interval in the x-axis direction. The interval is arbitrary as long as the interference between the power receiving coil 1A and the power receiving coil 1B is sufficiently reduced. Further, the power receiving coils 1A and 1B have the same axial direction in the z-axis direction, and the planes formed by the power receiving coils 1A and 1B and the plane formed by the power transmitting coil 2 are arranged on the same plane.

The power receiving coils 1A and 1B are circular coils formed by winding a wire rod in a circular shape. The axial direction is the z-axis direction. Cylindrical ferrite cores 10A and 10B are inserted in the central portions of the power receiving coils 1A and 1B, respectively. The power receiving coils 1A and 1B have a cross-sectional area of 12 mm ² , the number of turns is 4.5, and the length of the coil in the axial direction (the length in the z-axis direction) is 6.5 mm. The ferrite cores 10A and 10B have a diameter of 8 mm and a length of 7 mm.

  The cross-sectional area and the number of turns of the power receiving coils 1A and 1B are not limited to the values shown in the first embodiment, and are set according to the power received, the power receiving efficiency, and the like. For example, when the transmitted power is 10 W or less, the width (coil diameter) of the power receiving coils 1A and 1B in the x-axis direction and the y-axis direction is 3 to 200 mm, and the length of the coil in the axial direction (length in the z-axis direction). Is preferably 1 to 20 mm. The power receiving efficiency can be improved and the received power difference can be further reduced.

  Further, the shape of the power receiving coils 1A and 1B is not limited to the circular shape, but may be a square shape, a rectangular shape, or the like. Further, the power receiving coil 1A and the power receiving coil 1B may have different shapes. However, it is preferable to have the same shape from the viewpoint of facilitating the control of the received power difference between the power receiving coil 1A and the power receiving coil 1B.

Further, the power receiving coils 1A and 1B do not necessarily require a core material, and may be air-core coils. However, when the cross-sectional area of the power receiving coils 1A and 1B is 20 mm ² or less, it is preferable to use a ferrite core from the viewpoint of improving power receiving efficiency.

  Further, the plane formed by the power receiving coils 1A and 1B does not necessarily have to be the same plane as the plane formed by the power transmitting coil 2, and as long as the power from the power transmitting coil 2 can be received, the plane formed by the power transmitting coil 2 is It may be parallel and different planes, or it may be angled planes. Further, the plane formed by the power receiving coil 1A and the plane formed by the power receiving coil 1B may be different planes that are parallel to each other or may form an angle.

  The winding directions of the power receiving coils 1A and 1B may be left-handed or right-handed, and the winding directions may be changed between the power-receiving coil 1A and the power-receiving coil 1B.

(Structure of power transmission coil 2)
Next, the power transmission coil 2 will be described. The power transmission coil 2 is a wire rod wound a plurality of times so that the axial direction is the z-axis direction, and for each winding, as shown in FIG. 2, two action parts 20A and 20B and an action part 20A And a connecting portion 21 that connects the portion 20B, and has a gourd-shaped or spectacle-shaped shape as a whole. Each of the action portions 20A, 20B and the coupling portion 21 is shown by enclosing it in a dotted line in FIG. The number of turns of the power transmission coil 2 is appropriately set according to the transmitted power, the power transmission efficiency, etc., and is, for example, 1 to 3 turns. The winding direction may be left-handed or right-handed.

  The action unit 20A is a part mainly contributing to power transmission to the power receiving coil 1A, and the action unit 20B is a part mainly contributing to power transmission to the power receiving coil 1B. The action portions 20A and 20B are portions of a wire material having a rectangular cross section and are arranged at intervals in the x-axis direction. The surface formed by the action portion 20A and the surface formed by the action portion 20B are the same surface. Further, the action parts 20A and 20B are arranged with their sides aligned in the x-axis direction and the y-axis direction. Further, the power receiving coil 1A is arranged at the center of the acting portion 20A, and the power receiving coil 1B is arranged at the center of the acting portion 20B. The width of the acting portions 20A and 20B in the x-axis direction is 140 mm, and the width in the y-axis direction is 90 mm.

  In this way, the action parts 20A and 20B are arranged so as to surround the four sides of the power receiving coils 1A and 1B. That is, the sides of the action portions 20A and 20B are located at equal distances in the + x direction, the −x direction, the + y direction, and the −y direction with respect to the center of the power receiving coils 1A and 1B. Therefore, the distribution of the magnetic field strength generated from each side of the action parts 20A and 20B becomes uniform, and the difference in the power received by the power receiving coils 1A and 1B also becomes small.

  In order to further reduce the difference in power received by the power receiving coils 1A and 1B, the difference between the longest distance and the shortest distance from the center of the power receiving coils 1A and 1B to the action portions 20A and 20B is the action portions 20A and 20B. The diameter is preferably 8 times or less (the diameter of the circumscribed circle of the action portions 20A and 20B).

  Moreover, the cross-sectional areas of the power receiving coils 1A and 1B are set to ½ or less of the cross-sectional areas of the action portions 20A and 20B. By setting the cross-sectional area of the power receiving coils 1A and 1B or the cross-sectional area of the acting portions 20A and 20B in this manner, the difference in received power from the acting portions 20A and 20B can be suppressed. More preferably, it is 1/50 or less of the cross-sectional area of the action portions 20A and 20B.

  In the first embodiment, the plane patterns of the action portions 20A and 20B are rectangular. However, any shape may be used as long as it surrounds the power receiving coils 1A and 1B on all sides, and the plane pattern of the action portion 20A and the action portion 20B may be any shape. The shape and the size may be different depending on the plane pattern. For example, the plane pattern of the action parts 20A and 20B is a square, a rectangle, a rhombus, a circle, a semicircle, an ellipse, a polygon, or the like. When the power transmission coil 2 is wound around the housing to be mounted, it may have a shape that matches the shape of the housing.

  Further, in the first embodiment, the surface formed by the acting portion 20A and the surface formed by the acting portion 20B are the same plane, but different surfaces may be used as long as they are within a range in which power can be transmitted to the power receiving coils 1A and 1B, and the angles may be different. May be formed.

  Further, the power receiving coils 1A and 1B do not necessarily have to be at the centers of the action portions 20A and 20B, but the vicinity of the centers is preferable from the viewpoint of suppressing the difference in the received power.

  The connecting portion 21 is a portion that connects the acting portion 20A and the acting portion 20B, and is two linear wires 21a and 21b extending in the x-axis direction. On the side where the action portion 20A and the action portion 20B face each other, one of the corner portions of the action portion 20A and the corner portion of the action portion 20B which faces the action portion 20A are connected by a connecting portion 21. Here, the connecting portion is optional as long as the wire members do not branch and are connected so that the action portions 20A, 20B and the connecting portion 21 as a whole are connected in one stroke. One of the two straight lines of the connecting portion 21 (the wire rod 21b) is continuous with one side of the action portions 20A and 20B to form one straight line.

  The connecting portion 21 is provided with a control portion 22 that fixes the two wire rods 21 a and 21 b forming the connecting portion 21 so that the distance between them does not change from a predetermined distance. The control unit 22 is a rectangular spacer whose short side is equal to the interval between the two wire rods and whose long side is equal to the length of the connecting unit 21 (width in the x-axis direction). The control unit 22 may be any member that does not affect the characteristics of the power transmission coil 2 (a non-conductive material having a low dielectric constant). For example, a foamable resin can be used. When the power transmission coil 2 has two or more turns, the connecting portion 12 for each turn may be collectively fixed by one spacer.

  Since the power transmission coil 2 in the wireless power feeding system according to the first embodiment is made of a wire material, the coil inductance changes due to deformation or dislocation of the power transmission coil 2. In particular, in the connecting portion 21 of the power transmission coil 2, the two wires 21a and 21b are close to each other, and parasitic capacitance is generated in the power transmitting coil 2 by the connecting portion 21, which greatly affects the inductance of the coil. Therefore, in the power transmission coil 2 of the first embodiment, the control unit 22 fixes the distance between the two wire rods 21a and 21b forming the coupling unit 21 so that the parasitic capacitance does not change. This suppresses the fluctuation of the inductance of the coil and prevents the power transmission efficiency from decreasing.

  The control unit 22 may fix the distance between the two wires to a predetermined distance by a method other than the spacer. For example, the housing around which the wire is wound may be provided with a groove or a projection, and the wire may be fitted therein to fix the wire. Further, it may be fixed to the housing with an adhesive or an adhesive tape, or the two wires 21a and 21b may be fixed to each other with an adhesive tape or an adhesive. If the wire material is covered with an insulating material, the distance between the two wire materials 21a and 21b may be fixed to zero. When the interval is 0, the two wires 21a and 21b may be twisted in a double spiral shape.

  The distance between the two wires 21a and 21b of the connecting portion 21 may be any distance as long as it is sufficiently smaller than the diameter of the power transmission coil 2 (the diameter of the inscribed circle of the entire power transmission coil 2). It may be 1/10 or less of the diameter. In Example 1, it is preferable to fix it to 0 to 15 mm.

  The shape and size of the power transmission coil 2 as a whole are not particularly limited, but when the transmitted power is 10 W or less, the width (diameter of the coil) in the x-axis direction and the y-axis direction is 10 to 400 mm, and the length in the axial direction of the coil. The length (length in the z-axis direction) is preferably 1 to 100 mm. The power receiving efficiency can be improved and the received power difference can be further reduced. Further, in this case, the shapes and sizes of the action parts 20A and 20B and the connecting part 21 are arbitrary as long as they fall within the above size as a whole.

  Further, in the first embodiment, the two wires connected to the circuit 4 are drawn out from the acting portion 20A, but the drawing position may be arbitrary and may be drawn out from the connecting portion 21.

  As described above, in the wireless power feeding system according to the first embodiment, the connection portion 21 of the power transmission coil 2 is provided with the control portion 22 that fixes the interval between the two wire rods 21a and 21b of the connection portion 21, and the control portion 22 transmits the power. The parasitic capacitance of the coil 2 is prevented from changing. Therefore, even if the shape or the arrangement of the power transmission coil 2 is deviated, the variation of the inductance of the coil is suppressed, and the reduction of the power transmission efficiency is suppressed.

  FIG. 3 is a diagram showing shapes and arrangements of the power receiving coils 1A and 1B and the power transmitting coil 2 in the wireless power feeding system of the second embodiment. In the wireless power feeding system of the second embodiment, as shown in FIG. 3, the control unit 22 provided in the coupling unit 21 of the power transmission coil 2 is replaced with the control unit 202 described below. Other configurations are similar to those of the first embodiment.

  The control unit 202 is a device that changes the distance between the two wires that form the connecting unit 21. The control unit 202 may be any member as long as it does not affect the characteristics of the power transmission coil 2. As shown in FIG. 4, the control unit 202 has two protrusions 203A and 203B and a gear 204.

  The protrusions 203A and 203B have an elongated rectangular shape. One end of the protrusion 203A is fixed to one of the two wire rods (21a) that form the connecting portion 21, and the other end of the protrusion 203A projects toward the other wire rod (21b). Further, one end of the protrusion 203B is fixed to the wire 21b, and the other end of the protrusion 203B protrudes to the wire 21a side. In addition, the protrusions 203A and 203B are arranged with a constant interval. Further, saw teeth 205 are provided on opposite sides of the protrusions 203A and 203B.

  The gear 204 is arranged in a space portion where the projection 203A and the projection 203B face each other, and is arranged so that the teeth of the gear 204 and the teeth of the projections 203A and 203B mesh with each other.

  In the control unit 202, when the gear 204 is rotated, the protrusions 203A and 203B meshing with the gear 204 move in a direction in which they separate from each other or in a direction in which they approach each other. Along with this, the wire rods 21a and 21b to which the protrusions 203A and 203B are connected are also pulled in a direction away from each other or in a direction toward each other. As a result, the distance between the wire rods 21a and 21b can be controlled.

  The control unit 202 is not limited to the above mechanism, and may be any mechanism as long as it can change the distance between the two wire rods 21a and 21b. Further, it is not necessary to change the interval over the entire area of the two wires 21a and 21b, and it is sufficient if the interval is variable only in a part.

  For example, a link mechanism may be provided as shown in FIG. The link mechanism is one in which three rod-shaped bodies 210A, 210B, and 210C are rotatably connected in series at their ends. One end of the rod-shaped body 210A is rotatably connected to the wire 21a, and the other end of the rod-shaped body 210A is rotatably connected to one end of the rod-shaped body 210B. Further, one end of the rod-shaped body 210C is rotatably connected to the wire 21b, and the other end of the rod-shaped body 210C is rotatably connected to the other end of the rod-shaped body 210B.

  A rotating shaft 211 is connected to the center of the rod-shaped body 210B. By rotating the rotary shaft 211, the link mechanism is operated and the distance between the wire rods 21a and 21b can be controlled.

Alternatively, as shown in FIG. 6A, the conical screws 220A and 220B may be provided. The conical screws 220A and 220B are conical rotating bodies, and are arranged such that the axis of the cone is perpendicular to the plane formed by the wire rods 21a and 21b. Further, by rotating the conical screws 220A, 220B, the conical screws 220A, 220B can be moved in the axial direction thereof. The conical screw 220A is in contact with the wire 21a on the side opposite to the side where the wire 21a and the wire 21b face each other, and the conical screw 220B is in contact with the wire 21b on the side opposite to the side where the wire 21a and the wire 21b face each other.

  As shown in FIGS. 6B and 6C, when the conical screws 220A and 220B are rotated, the diameter of the cross section of the conical screws 220A and 220B in the plane formed by the wire rods 21a and 21b is changed, and when the diameter is increased, The wire rods 21a and 21b in contact with the screws 220A and 220B are pulled by the conical screws 220A and 220B toward the opposite sides. In this way, the distance between the wire rods 21a and 21b can be controlled.

  As described above, in the wireless power feeding system according to the second embodiment, the connecting portion 21 of the power transmitting coil 2 is provided with the control portion 202 that makes the distance between the two wires of the connecting portion 21 variable. The parasitic capacitance of is adjustable. Therefore, even if the shape or disposition of the power transmission coil 2 is changed and the inductance of the coil is changed, the inductance can be adjusted and the shift of the resonance frequency of the power transmission side circuit can be corrected. As a result, it is possible to intentionally change the power transmission efficiency.

(Modification)
In the first and second embodiments, the control unit that fixes and changes the parasitic capacitance is provided at the connecting portion 21 of the two action units 20A and 20B of the power transmission coil 2, but the power transmission coil 2 has two wire rods. It is arbitrary as long as it has a close proximity part and a control part is provided at the close proximity part. Here, the proximity portion is a region in which the two wires are sufficiently close to each other, and is a region in which the diameter is 1/10 or less of the diameter of the power transmission coil. It is also not necessary for the two wires to be parallel. When a plurality of adjacent parts are provided, a control part may be provided for each.

  In the first and second embodiments, the control unit is provided on the power transmission coil 2 side to fix or adjust the parasitic capacitance due to the proximity unit (coupling unit 21), but the same applies to the power receiving coils 1A and 1B side. A configuration may be provided to fix and adjust the parasitic capacitance of the power receiving coils 1A and 1B. Of course, the parasitic capacitance may be fixed and adjusted for both the power transmitting coil 2 and the power receiving coils 1A and 1B.

  The wireless power feeding system of the present invention can be used for wireless power feeding to various electric devices.

1A, 1B: power receiving coil 2: power transmitting coil 3: AC power supply 4, 5A, 5B: circuit 20A, 20B: action part 21: connecting part 22, 202: control part

Claims (9)

In a power transmission coil made of a wire that transmits electric power in a non-contact manner by the magnetic field resonance method,
A proximity part in which the two wires are close to a distance of 1/10 or less of the diameter of the power transmission coil;
A control unit that controls the distance between the two wire rods in the proximity unit to a predetermined distance;
A power transmission coil having:   The power transmission coil according to claim 1, wherein the control unit fixes the distance between the two wires to a predetermined distance.   The power transmission coil according to claim 1, wherein the control unit changes a distance between the two wire rods. In a power receiving coil made of a wire that receives power in a non-contact manner from the magnetic resonance method,
A proximity portion in which the two wires are close to a distance of 1/10 or less of the diameter of the power receiving coil;
A control unit that controls the distance between the two wire rods in the proximity unit to a predetermined distance;
A power-receiving coil having:   The power receiving coil according to claim 4, wherein the control unit fixes the distance between the two wires to a predetermined distance.   The power transmission coil according to claim 4, wherein the control unit changes a distance between the two wire rods. The power transmission coil according to any one of claims 1 to 3, which transmits power in a contactless manner by a magnetic field resonance method,
A power receiving coil that receives power from the power transmitting coil in a non-contact manner,
A wireless power feeding system comprising: A power transmission coil that transmits electric power in a contactless manner by a magnetic field resonance method;
The power receiving coil according to any one of claims 4 to 6, which receives power from the power transmitting coil in a non-contact manner.
A wireless power feeding system comprising: The power transmission coil according to any one of claims 1 to 3, which transmits power in a contactless manner by a magnetic field resonance method,
The power receiving coil according to any one of claims 4 to 6, which receives power from the power transmitting coil in a non-contact manner.
A wireless power feeding system comprising:

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