Coil, power transmitting device, power receiving device, and power transmission system

Abstract

Provided is a coil or the like that can pass a large current even at high frequencies and can improve the efficiency of wireless power transmission. In a coil for contactless power transmission, two thin copper film wires that constitute the coil are parallel to the winding direction.

Description

[Technical Field]

[0001] The present invention belongs to the technical fields of coils, power transmitting devices, power receiving devices, and power transfer systems, and more specifically, to the technical fields of coils for contactless power transfer, and contactless power transmitting devices, power receiving devices, and power transfer systems using such coils. [Background technology]

[0002] In recent years, electric vehicles equipped with storage batteries, such as lithium-ion batteries, have become increasingly popular. Such electric vehicles use power stored in the storage batteries to drive their motors, necessitating efficient battery charging. Therefore, research has been conducted on so-called wireless power transmission, which uses a power receiving coil and a power transmitting coil spaced apart and facing each other, as a method for charging the storage batteries of electric vehicles without physically connecting them to a charging plug or the like. Wireless power transmission methods generally include electric field coupling, electromagnetic induction, and magnetic resonance. When these methods are compared in terms of, for example, operating frequency, horizontal and vertical positional freedom, and transmission efficiency, the electric field coupling method using a capacitor and the magnetic resonance method using a coil are considered promising wireless power transmission methods for charging the storage batteries of electric vehicles, and research and development into these methods is actively being conducted. Patent Document 1 listed below is an example of a prior art document disclosing such background technology. Patent Document 1 discloses a coil that transmits power by magnetic field resonance using a loop coil with one winding (1 turn) and an open coil with 5.5 windings (5.5 turns).

[0003] Meanwhile, the frequency of the power transmitted and received via wireless power transmission is predetermined for each device, for example, by law. For example, the frequency of power transmitted to an electric vehicle is set at 85 kHz. It is generally known that when a high-frequency current flows through a conductor, the current density is high on the surface of the conductor and decreases as it moves from the surface toward the center. Furthermore, as the current frequency increases, the current tends to concentrate on the surface, resulting in a higher AC resistance of the conductor. This phenomenon is known as the "skin effect of a conductor." [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-200045 Summary of the Invention [Problem to be solved by the invention]

[0005] On the other hand, the above-mentioned wireless power transmission (contactless power supply) for electric vehicles requires the transmission (i.e., flowing through the coil) of high-power power of at least 3.7 kilowatts while using a high-frequency (e.g., the above-mentioned 85 kilohertz) current. Therefore, if the resistance of the conductor (coil) increases due to the above-mentioned skin effect as a result of flowing such high-power power (current), Joule heat is generated, increasing loss in the coil and reducing the efficiency of wireless power transmission.

[0006] The present invention has been made in consideration of the above-mentioned problems, and one example of the object of the present invention is to provide a coil that can pass a large current even at high frequencies and can improve the efficiency of wireless power transmission, as well as a contactless power transmitting device, power receiving device, and power transmission system that use such a coil. [Means for solving the problem]

[0007] In order to solve the above problem, the invention described in claim 1 is: Used to charge storage batteries installed in electric vehicles In a coil for contactless power transmission, at least a portion of the windings constituting the coil and made of thin film conductors are composed of multiple parallel windings aligned in the radial direction of the coil and parallel to the winding direction of the windings, the parallel windings are structured such that two thin film conductors are stacked in a direction perpendicular to a plane including the windings of the windings and the two thin film conductors are connected in parallel to each other within one winding, the parallel windings are composed of an outer-inner parallel winding wound from the outer periphery side to the inner periphery side of the coil, and an inner-outer parallel winding wound from the inner periphery side to the outer periphery side of the coil in the same direction as the outer-inner parallel winding, and the parallel windings in one winding of the coil are composed of multiple straight sections and curved sections connecting the multiple straight sections.

[0008] According to the invention of claim 1, at least a part of the windings that make up the coil and are made of thin-film conductors is made up of a plurality of parallel windings that are aligned in the radial direction of the coil and parallel to the winding direction of the windings, so that the influence of the skin effect caused by the current flowing through the coil can be reduced, and the resistance value of the coil can be reduced. Also, since the parallel windings are structured such that two thin-film conductors are stacked in a direction perpendicular to the plane including the windings of the windings, and the two thin-film conductors are connected in parallel to each other within one winding, A coil for contactless power transmission used to charge a storage battery mounted on an electric vehicle, By laminating two layers of thin-film conductors and connecting them in parallel, the cross-sectional area of the windings that make up the coil can be increased, further reducing the resistance of the coil and further improving its efficiency. Furthermore, because the parallel windings are composed of outer-inner parallel windings and inner-outer parallel windings, improving the impedance characteristics of the coil also improves the efficiency of wireless power transmission. In order to solve the above problem, the invention described in claim 2 is the coil described in claim 1, in which the parallel windings that make up one of the windings are formed in the same layer. According to the invention described in claim 2, in addition to the effect of the invention described in claim 1, the parallel windings constituting one winding of the coil are formed in the same layer of the coil, so that the resistance value of the coil can be further reduced while simplifying the manufacturing process.

[0009] In order to solve the above problem, claims 3 The invention described in claim 1 or claim 2 In the coil described in , the at least one portion is configured by three of the parallel wound wires.

[0010] Claim 3 According to the invention described in claim 1 or claim 2 In addition to the effects of the invention described above, at least a portion of the windings constituting the coil is made up of three parallel windings, so that the resistance value of the coil can be effectively reduced.

[0011] In order to solve the above problem, claims 4 The invention described in claim 1 or claim 2 In the coil described in , the coil is configured by four of the parallel wound wires.

[0012] Claim 4 According to the invention described in claim 1 or claim 2 In addition to the effects of the invention described above, since the coil is made up of four parallel wound wires, the resistance value of the coil can be reduced more effectively.

[0013] In order to solve the above problem, claims 5 The invention described in claims 1 to 5 is 4 In the coil described in any one of the above, a switching portion is provided on the winding of the coil, where the positions of the parallel windings in a direction perpendicular to the winding direction are switched.

[0014] Claim 5 According to the invention described in claim 1 to claim 2, 4In addition to the effects of the invention described in any one of claims 1 to 5, the coil winding is provided with a switching section where the positions of the parallel windings in the direction perpendicular to the winding direction are switched, thereby further reducing the influence of the skin effect and reducing the resistance value of the coil.

[0019] In order to solve the above problem, claims 6 The invention described in claims 1 to 5 is 5 In the coil according to any one of claims 1 to 5, an intersection where the parallel windings intersect is provided at the innermost periphery of the coil.

[0020] Claim 6 According to the invention described in claim 1 to claim 2, 5 In addition to the effects of the invention described in any one of claims 1 to 5, an intersection where the parallel windings intersect is provided at the innermost periphery of the coil, which further improves the impedance characteristics of the coil and thereby further improves the efficiency of wireless power transmission.

[0021] In order to solve the above problem, claims 7 The invention described in claims 1 to 5 is 6 In the coil described in any one of the above, one of the windings is composed of two of the parallel windings, and in one of the windings, the width of the parallel winding on the inner side is wider than the width of the parallel winding on the outer side.

[0022] Claim 7 According to the invention described in claim 1 to claim 2, 6 In addition to the effects of the invention described in any one of claims 1 to 4, one winding is composed of two parallel windings, and in one winding, the width of the parallel winding on the inner side is wider than the width of the parallel winding on the outer side, so that the impedance characteristics of the coil are further improved, and the efficiency of wireless power transmission can also be further improved.

[0023] In order to solve the above problem, claims 8 The invention described in claim 7In the coil described above, the width of the winding wire is configured to be wider toward the inner periphery of the coil.

[0024] Claim 8 According to the invention described in claim 7 In addition to the effects of the invention described above, the width of the winding wire is wider toward the inner circumference of the coil, which further improves the impedance characteristics of the coil and thereby further improves the efficiency of wireless power transmission.

[0026] above In order to solve the above problem, the following claims are provided: 9 The invention described in claims 1 to 5 is 8 In the coil described in any one of the above, the frequency of the power transmitted by the coil is configured to be equal to or greater than 85 kilohertz and equal to or less than 1 megahertz. Claim 9 According to the invention described in claim 1 to claim 2, 8 In addition to the effect of the invention described in any one of the above, since the frequency of the power transmitted by the coil is 85 kilohertz or more and 1 megahertz or less, the resistance value of the coil in that frequency band can be further reduced.

[0027] In order to solve the above problem, the invention described in claim 11 provides a power transmission system that includes a power transmission device and a power receiving device spaced apart from the power transmission device, and that transmits power from the power transmission device to the power receiving device in a contactless manner, the power transmission device comprising: a power transmission coil that is the coil described in any one of claims 1 to 10, and that is arranged opposite the power receiving device; and an output means that outputs the power to be transmitted to the power transmission coil.

[0028] In order to solve the above problem, the invention described in claim 12 is a power receiving device included in a power transmission system that is composed of a power transmitting device and a power receiving device spaced apart from the power transmitting device and that transmits power from the power transmitting device to the power receiving device in a contactless manner, the power receiving device comprising: a power receiving coil that is the coil described in any one of claims 1 to 10, the power receiving coil being arranged opposite the power transmitting device; and an input means connected to the power receiving coil.

[0029] In order to solve the above problem, the invention described in claim 13 comprises a power transmission device described in claim 11, and a power receiving device that is arranged at a distance from the power transmission device and opposite the power transmission coil, and that receives power transmitted from the power transmission device.

[0030] In order to solve the above problem, the invention described in claim 14 comprises a power transmitting device and a power receiving device described in claim 12, which is located away from the power transmitting device and has the power receiving coil facing the power transmitting device, and receives power transmitted from the power transmitting device.

[0031] Claim 10 From the claim 13 According to the invention described in any one of claims 1 to 5, at least one of a power transmitting coil provided in a power transmitting device and a power receiving coil provided in a power receiving device that constitutes a power transmission system is 9 Since the coil is the one described in any one of the above, when the power transmitting coil or the power receiving coil is placed opposite to each other and a non-contact type power transmission is performed, the influence of the skin effect caused by the current flowing through the coil can be reduced, and the resistance value of the coil can be reduced. , two thin film conductors in a direction perpendicular to the plane containing the turns of the winding Lamination and two thin film conductors are connected in parallel to each other within one winding. Because it is considered a structure, By stacking two layers of thin film conductors and connecting them in parallel, By increasing the cross-sectional area of the windings that make up the coil, the resistance of the coil can be further reduced. Further improve its efficiency It is possible. Furthermore, since the parallel winding circuit is composed of an outer-inner parallel winding circuit and an inner-outer parallel winding circuit, the impedance characteristics of the coil can be improved, thereby improving the efficiency of wireless power transmission. [Effects of the Invention]

[0032] According to the present invention, at least a portion of the windings that constitute the coil and are made of thin-film conductors is made up of a plurality of parallel windings that are parallel to the winding direction of the windings.

[0033] Therefore, the influence of the skin effect caused by the current flowing through the coil can be reduced, and the resistance value of the coil can be reduced, so that the loss of the coil can be reduced and a large high-frequency current can be passed through, thereby improving the efficiency of the coil. Also, since the parallel winding has a structure in which two thin-film conductors are stacked in a direction perpendicular to the plane including the winding of the winding, and the two thin-film conductors are connected in parallel to each other within one winding, A coil for contactless power transmission used to charge a storage battery mounted on an electric vehicle, By laminating two layers of thin-film conductors and connecting them in parallel, the cross-sectional area of the windings that make up the coil can be increased, further reducing the resistance of the coil and further improving its efficiency. Furthermore, because the parallel windings are composed of outer-inner parallel windings and inner-outer parallel windings, improving the impedance characteristics of the coil also improves the efficiency of wireless power transmission. [Brief explanation of the drawings]

[0034] [Figure 1] 1 is a block diagram showing a schematic configuration of a power transmission system according to a first embodiment; [Figure 2] FIG. 2 is a plan view (i) showing the structure of the coil of the first embodiment. [Figure 3] FIG. 2B is a plan view showing the structure of the coil of the first embodiment. [Figure 4] FIG. 3(iii) is a plan view showing the structure of the coil of the first embodiment. [Figure 5] FIG. 4 is a plan view (iv) showing the structure of the coil of the first embodiment. [Figure 6] FIG. 10 is a plan view (v) showing the structure of the coil of the first embodiment. [Figure 7] FIG. 2 is a partial cross-sectional view showing the structure of the coil of the first embodiment. [Figure 8] FIG. 10 is a plan view illustrating the structure of a power transmission loop coil according to a second embodiment. [Figure 9]FIG. 10 is an enlarged perspective conceptual diagram showing the detailed structure of a power transmission loop coil according to a second embodiment. [Figure 10] FIG. 10 is a plan view illustrating the structure of a power transmission loop coil according to a third embodiment. [Figure 11] 10A and 10B are enlarged perspective conceptual diagrams showing the detailed structure of a power transmission loop coil of a third embodiment, where (a) is the enlarged perspective conceptual diagram (I) and (b) is the enlarged perspective conceptual diagram (II). [Figure 12] 4 is a diagram showing the relationship between resistance and frequency as an effect of the structures of the power transmitting loop coil and the power receiving loop coil of the first embodiment. FIG. [Figure 13] FIG. 10 is a diagram showing the relationship between S parameters and frequency as an effect of the structures of the power transmitting loop coil and the power receiving loop coil of the second embodiment. [Figure 14] FIG. 20 is a plan view showing the coil structure (I) of the twelfth modified form. [Figure 15] FIG. 20 is a plan view showing the coil structure (II) of the twelfth variant. [Figure 16] FIG. 20 is a plan view showing the coil structure (III) of the twelfth modified form. [Figure 17] FIG. 20 is a plan view showing a part of the coil structure (IV) of the twelfth variant. [Figure 18] FIG. 23 is a diagram showing the relationship between impedance and frequency as an effect of the structure of each coil of the twelfth modified embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0035] Next, embodiments of the present invention will be described with reference to the drawings. Each of the embodiments and modifications described below is an embodiment and modification in which the present invention is applied to a power transmission system that transmits power for charging a rechargeable battery mounted on an electric vehicle to the electric vehicle equipped with the rechargeable battery in a contactless manner using magnetic resonance.

[0036] Here, the magnetic field resonance type power transfer system of each embodiment and modified form includes a power transmission coil that transmits power, and a power receiving coil that is disposed facing (i.e., opposite) the power transmission coil and receives the power transmitted from the power transmission coil. The power transmission coil is configured by stacking a power transmission loop coil (described later) and a power transmission open coil (described later). The power receiving coil is configured by stacking a power receiving open coil (described later) and a power receiving loop coil (described later). Embodiments

[0037] (A) First embodiment First, a first embodiment of the present invention will be described with reference to FIGS.

[0038] (I) Overall configuration and operation of the power transmission system of the first embodiment First, the overall configuration and operation of the power transmission system of the first embodiment will be described with reference to Fig. 1. Fig. 1 is a block diagram showing the general configuration of the power transmission system of the first embodiment.

[0039] As shown in FIG. 1 , the power transmission system S of the first embodiment is configured to include a power receiving device R including a power receiving unit RV and the power receiving coil RC, and a power transmitting device T including a power transmitting unit TR and the power transmitting coil TC. In this case, the power receiving device R is mounted on the electric vehicle and connected to a storage battery (not shown) mounted on the electric vehicle. On the other hand, the power transmitting device T is installed on the ground at a position where the electric vehicle is moving or parked. When charging the storage battery, the electric vehicle is driven or parked so that the power receiving coil RC of the power receiving device R and the power transmitting coil TC of the power transmitting device T face each other. Note that when charging the storage battery using the power transmission system S of the first embodiment, power can be transmitted from the power transmitting device T to the power receiving device R mounted on the parked electric vehicle via the power transmitting coil TC of the power transmitting device T installed on the ground below the parked position. Alternatively, a configuration may be adopted in which power is continuously transmitted from a power receiving device R mounted on a moving electric vehicle to the power transmitting device T via power transmitting coils TC of a plurality of power transmitting devices T installed within a certain distance of the road on which the electric vehicle is traveling. In this case, the power transmitting unit TR corresponds to an example of the "output means" of the present invention, and the power receiving unit RV corresponds to an example of the "input means" of the present invention.

[0040] Meanwhile, the power transmitting coil TC includes a power transmitting loop coil TL and a power transmitting open coil TO. The power receiving coil RC includes a power receiving open coil RO and a power receiving loop coil RL. In this case, the power to be transmitted is input to the power transmitting loop coil TL from the power transmitting unit TR. The power transmitting open coil TO is stacked concentrically with the power transmitting loop coil TL and has both ends open. On the other hand, the power receiving open coil RO is disposed opposite the power transmitting open coil TO and has both ends open. The power receiving loop coil RL is stacked concentrically with the power receiving open coil RO and outputs the power received from the power transmitting coil TC to the power receiving unit RV via the power receiving open coil RO by magnetic field resonance. In this case, the power transmitting loop coil TL and the power receiving loop coil RL each correspond to an example of a "coil" in the present invention.

[0041] In the above configuration, the power transmitting unit TR of the power transmitting device T outputs power to be transmitted to the power receiving device R to the power transmitting coil TC while complying with laws and regulations, such as the Radio Act, in the country where the power transmission system S is used. The laws and regulations, for example, regulate leakage magnetic fields to be below a predetermined level, taking into account the effects on the human body. Furthermore, to enable interconnection between all power transmitting devices T and the power receiving devices R, they must ultimately use frequencies within a predetermined range. Therefore, the predetermined frequency range or frequency band must comply with the recommendations of international organizations, such as the ISO (International Organization for Standardization) or the IEC (International Electrotechnical Commission), as the laws and regulations. Furthermore, the international organizations also specify a lower limit of the transmission efficiency, taking into account a predetermined positional misalignment between the power transmitting coil TC and the power receiving coil RC. Therefore, the power transmission system S is also required to have high power transmission efficiency.

[0042] Meanwhile, the power receiving coil RC of the power receiving device R, which receives power from the power transmitting coil TC using the magnetic field resonance method, outputs the received power to the power receiving unit RV. As a result, the power receiving unit RV converts the output corresponding to the power (for example, the 85 kHz high-frequency power) into a DC (direct current) current using, for example, a power conversion unit (not shown), and outputs it to the storage battery of the electric vehicle. As a result, the storage battery is charged with the required amount of power.

[0043] (II) Configuration of the transmitting coil TC (receiving coil RC) Next, the configurations of the power transmitting coil TC and the power receiving coil RC of the first embodiment used in the power transfer system S of the first embodiment described above will be described with reference to FIGS. 2 to 7. The power transmitting coil TC and the power receiving coil RC of the first embodiment have essentially the same configuration. That is, the configurations of the power transmitting loop coil TL and the power receiving loop coil RL are essentially the same. The configurations of the power transmitting open coil TO and the power receiving open coil RO are also essentially the same. Furthermore, the positional relationship between the power transmitting loop coil TL and the power transmitting open coil TO within the power transmitting coil TC is essentially the same as the positional relationship between the power receiving loop coil RL and the power receiving open coil RO within the power receiving coil RC. Therefore, the following description will focus on the structure of the power transmitting coil TC. FIGS. 2 to 6 are plan views showing the structure of the power transmitting coil TC of the first embodiment, and FIG. 7 is a partial cross-sectional view showing the structure of the power transmitting coil TC of the first embodiment. FIGS. 2 to 6 are plan views of the power transmitting coil TC as viewed from the power transmitting unit TR side in the power transmitting device T.

[0044] As shown in a plan view in FIG. 2 , the power transmitting coil TC of the first embodiment is configured by stacking a power transmitting loop coil TL, which is composed of two parallel copper thin-film wires, e.g., copper thin-film wires TL11 and TL12 (described later), and a power transmitting open coil TO (not shown in FIG. 2 ), with an insulating film BF1 (described later in detail) between them, in the direction of the page in FIG. 2 . In this configuration, the copper thin-film wires TL11 and TL12 correspond to an example of a “parallel wound circuit” according to the present invention. The power transmitting open coil TO is configured by stacking two coils, CL1 and CL2 (described later), with an insulating film BF2 (described later in detail) between them, in the direction of the page in FIG. 2 . Note that in the first embodiment, the film BF1 is used to provide insulation between the power transmitting loop coil TL and the power transmitting open coil TO, and the film BF2 is used to provide insulation between the coils CL1 and CL2. However, other insulating materials, such as glass epoxy materials, can also be used. Furthermore, to efficiently dissipate heat generated by the power transmitting coil TC, a thin-film material with ceramic particles dispersed therein can also be used. Furthermore, the wires may be stacked with the necessary gaps provided by using an appropriate gap retaining material. Furthermore, the winding centers of the copper thin film wires TL11 and TL12 that make up the power transmission loop coil TL and the winding centers of the copper thin film wires described below that make up the coils CL1 and CL2 are set to be the same or approximately the same as each other.

[0045] As shown in Fig. 2, the power transmitting loop coil TL is composed of copper thin-film wire TL11 and copper thin-film wire TL12 wound parallel to each other within the same layer of the power transmitting coil TC, and has connection terminals O1 and O2 on one side of its outermost circumference to which the copper thin-film wires TL11 and TL12 are connected and which are also connected to the power transmitting unit TR. The power transmitting loop coil TL is composed of the copper thin-film wire TL11 and copper thin-film wire TL12 wound parallel to each other three times (three turns), and both ends of the copper thin-film wire TL11 and copper thin-film wire TL12 (the center of the right side in Fig. 2) are connected to the connection terminals O1 and O2. The copper thin-film wire TL11 and copper thin-film wire TL12 each have the same width and thickness over the entire circumference of the power transmitting loop coil TL. Furthermore, each of the copper thin film wires TL11 and TL12 has straight line sections on its upper, lower, left and right sides in Fig. 2, and these straight line sections are connected by curved lines. Furthermore, the copper thin film wires TL11 and TL12 cross each other at their intersections while being insulated from each other by a jumper wire or a laminated structure with an insulating layer sandwiched therebetween.

[0046] Next, the configuration of the coil CL1 that constitutes the power transmitting open coil TO, which is layered directly below the power transmitting loop coil TL via the film BF1, will be described with reference to Fig. 3. Fig. 3 is a plan view showing only the coil CL1.

[0047] As shown in FIG. 3 , the outermost portion of the coil CL1 constituting the power transmitting open coil TO is an open end T1. The coil CL1 is formed by, for example, spirally winding a copper thin-film wire ten and a half times (10.5 turns) in a counterclockwise direction starting from the open end T1 from the outermost portion to the innermost portion. A via V is connected to the innermost portion of the coil CL1 to electrically connect it to the coil CL2 stacked directly below it in the direction of the page in FIG. 3 . The copper thin-film wire constituting the coil CL1 has a uniform thickness around the entire circumference of the coil CL1. However, as shown in FIG. 3 , the width of the copper thin-film wire increases from the open end T1 at the outermost end of the coil CL1 to the portion of the innermost end where the via V is connected. The coil CL1 has parallel straight portions on its top, bottom, left, and right sides in FIG. 3 , and these straight portions are connected by curved portions that are approximately concentric arcs. The width of the copper thin film wire constituting the coil CL1 is constant in each straight section, but increases toward the innermost circumferential end of each curved section connecting them. In this case, it is sufficient that the width of the copper thin film wire constituting the coil CL1 increases from the outermost circumferential end to the innermost circumferential end of the entire coil CL1, and even if the width temporarily (partially) narrows from the outermost circumferential end to the innermost circumferential end, this does not affect the effect of power transmission using the power transmission system S of the first embodiment.

[0048] Next, the configuration of the coil CL2 laminated directly below the coil CL1 via the film BF2 will be described with reference to Fig. 4. Fig. 4 is a plan view showing only the coil CL2.

[0049] As shown in FIG. 4, the coil CL2, which constitutes the power transmitting open coil TO together with the coil CL1, has the via V connected to its innermost periphery for electrical connection with the coil CL1. In this case, the coils CL1 and CL2 are connected in series. The coil CL2 is formed by winding, for example, a thin copper wire spirally about two and a half turns (about 2.5 turns) clockwise (i.e., in the opposite direction to the coil CL1) starting from the via V from its innermost periphery to its outermost periphery. The outermost periphery is defined as an open end T2. The thin copper wire constituting the coil CL2 has the same thickness around the entire circumference of the coil CL2. However, as shown in FIG. 4, the width of the thin copper wire increases from the open end T2 at the outermost periphery of the coil CL2 to the part connected to the via V at the innermost periphery. Like coil CL1, this coil CL2 has parallel straight line segments on its top, bottom, left, and right sides in FIG. 4, and these straight line segments are connected by curved lines that are approximately concentric arcs. The width of the copper thin-film wire constituting coil CL2 is constant along each straight line segment, but increases toward the innermost periphery of each curved line segment connecting them. Similarly to the width of the copper thin-film wire constituting coil CL1, the width of the copper thin-film wire constituting coil CL2 as a whole only needs to increase from the outermost periphery to the innermost periphery, and may, for example, be temporarily (partially) narrowed from the outermost periphery to the innermost periphery.

[0050] Here, the copper thin film wires constituting the coils CL1 and CL2 are wound such that the positions of the copper thin film wires of the counterclockwise-wound coil CL1 and the clockwise-wound coil CL2 are approximately aligned when viewed from the center of the winding of each coil CL1 and CL2. The coils CL1 and CL2 are connected in series by vias V connected to their innermost peripheries. As a result, the coil CL2 is connected to the innermost periphery of the coil CL1 so that the winding direction is opposite to that of the coil CL1, and the coil CL2 is wound from the innermost periphery to the outermost periphery while maintaining the winding direction. With this structure, in the power transmitting open coil TO of the first embodiment, a current flows counterclockwise from the outermost periphery to the innermost periphery in the coil CL1, and the current flows in the opposite clockwise direction from the innermost periphery to the outermost periphery in the coil CL2.

[0051] Next, the positional relationship between the copper thin film wires constituting the power transmitting loop coil TL (i.e., the copper thin film wires TL11 and TL12) and the power transmitting open coil TO (i.e., the coils CL1 and CL2) will be described with reference to FIGS. 5 and 6. FIG. 5 is a plan view showing the overlapping state of the copper thin film wires TL11 and TL12 with the coil CL1, where the copper thin film wires TL11 and TL12 are indicated by solid lines and the coil CL1 of the power transmitting open coil TO, which is layered directly below them with a film BF1 (not shown in FIG. 5) interposed therebetween, is indicated by a dashed line. FIG. 6 is a plan view showing the overlapping state of the coil CL1 of the power transmitting open coil TO with the coil CL2, where the coil CL1 is indicated by a solid line and the coil CL2, which is layered directly below them with a film BF2 (not shown in FIG. 6) interposed therebetween, is indicated by a dashed line.

[0052] As shown by the dashed lines in Fig. 5, coil CL1 is wound from the outer periphery toward the inner periphery and is connected to coil CL2 at its innermost periphery by via V. The copper thin film wire is wound with each curved portion formed so that the position of the straight portion shifts toward the inner periphery by one-fourth of the pitch of the copper thin film wire winding (i.e., the radial distance in the winding between the center lines of adjacent copper thin film wires on each side; the same applies below) every quarter of the turn. On the other hand, as shown by the solid lines in Fig. 5, copper thin film wires TL11 and TL12 are stacked so as to be in approximately the same position as coil CL1, and connection terminals O1 and O2 are shaped to protrude outside the winding.

[0053] Next, as shown by the dashed line in Fig. 6, coil CL2 is wound from the inner periphery to the outer periphery and is connected to coil CL1 at its innermost periphery by via V. The copper thin film wire is wound with each curved section formed so that the position of the straight section shifts toward the outer periphery by one-fourth of the pitch of the winding of the copper thin film wire every quarter of the turn. Meanwhile, as shown by the solid line in Fig. 6, coil CL1 is stacked so that it is in approximately the same position as coil CL2, with open ends T1 and T2 formed on the outside of the winding and further connected to each other by vias V at their innermost peripheries so as to penetrate film BF2.

[0054] As shown in Figures 5 and 6 above, in the power transmission coil TC, in which the power transmission loop coil TL (copper thin film wires TL11 and TL12) and the coils CL1 and CL2 of the power transmission open coil TO are stacked, the copper thin film wires TL11 and TL12 and the copper thin film wires that make up the power transmission open coil TO (coils CL1 and CL2) are stacked so that they approximately overlap on each of the top, bottom, left, and right sides.

[0055] Next, the stacking state of the copper thin film wires TL11 and TL12 with the coils CL1 and CL2, and the connection state of the coils CL1 and CL2 will be explained using Figure 7, which is a cross-sectional view of the a-a' portion shown in Figures 5 and 6.

[0056] 2 to 6, the power transmission loop coil TL (copper thin-film wire TL11 and copper thin-film wire TL12) and coil CL1 are laminated with film BF1 (see FIG. 2) sandwiched between them, and further, coils CL1 and CL2 are laminated with film BF2 sandwiched between them, with coils CL1 and CL2 electrically connected by via V. From the position of this via V, the clockwise winding of coil CL2 is formed so that the winding direction is opposite to the counterclockwise winding of coil CL1.

[0057] (III) Manufacturing method of the transmitting coil TC and receiving coil RC Next, a method for manufacturing the power transmitting coil TC and the power receiving coil RC of the first embodiment will be described.

[0058] The manufacturing method can be basically the same as conventional methods, such as a first manufacturing method including the following steps (a)-1 to (a)-11, or a second manufacturing method including the following steps (b)-1 to (b)-12. (a) 1st manufacturing method (a)-1: Copper thin film is formed on both sides of film BF2 (a)-2: Apply resist to the copper thin film (both sides) formed in (a)-1 above. (a)-3: The resist applied in (a)-2 above is patterned on the copper thin film wires of the coils CL1 and CL2 on each side (at this time, the patterning is performed so that the width of the copper thin film wire constituting the coil CL1 (coil CL2) of the first embodiment increases from the open end T1 (open end T2) at the outermost edge of the coil CL1 (coil CL2) to the part at the innermost edge where the via V is connected, as described above). (a)-4: After the patterning in (a)-3 above, etching is performed to form copper thin film wires as coils CL1 and CL2. (a)-5: A via V is formed to connect the coil CL1 and the coil CL2 to form a power transmitting open coil TO. (a)-6: A thin copper film is formed on the entire surface of film BF1. (a)-7: Apply resist onto the copper thin film formed in (a)-6 above. (a)-8: The resist applied in (a)-7 above is patterned into copper thin film lines TL11 and TL12. (a)-9: After the patterning of (a)-8 above, etching is performed to form copper thin film wires TL11 and TL12 as the power transmission loop coil TL. (a)-10: The power transmission open coil TO of (a)-5 above and the power transmission loop coil TL of (a)-9 above are glued together to form the power transmission coil TC. (a)-11: Connect the connection terminal O1 and the connection terminal O2 to the power transmitting unit TR (in the case of the power transmitting device T) or the power receiving unit RV (in the case of the power receiving device R). (b) Second manufacturing method (b)-1: Copper thin film is formed on both sides of film BF2 (b)-2: Form a through hole using a laser or the like at a position corresponding to the via V that connects the coils CL1 and CL2. (b)-3: Copper plating is performed by electroless copper plating and electrolytic copper plating on the entire surface including the through hole to form the via V. (b)-4: Apply resist to the copper plating (both sides) formed in (b)-3 above. (b)-5: The resist applied in (b)-4 above is patterned onto the copper thin film wires of the coils CL1 and CL2 (at this time, the patterning is performed so that the width of the copper thin film wire constituting the coil CL1 (coil CL2) of the first embodiment becomes wider from the open end T1 (open end T2) at the outermost edge of the coil CL1 (coil CL2) to the part at the innermost edge where the via V is connected, as described above). (b)-6: After the patterning in (b)-5 above, etching is performed to form copper thin film wires as the coils CL1 and CL2 to form the power transmission open coil TO. (b)-7: A thin copper film is formed on the entire surface of film BF1. (b)-8: Apply resist onto the copper thin film formed in (b)-7 above. (b)-9: The resist applied in (b)-8 above is patterned into copper thin film lines TL11 and TL12. (b)-10: After the patterning of (b)-9, etching is performed to form copper thin film wires TL11 and TL12 as the power transmission loop coil TL. (b)-11: The power transmission open coil TO of (b)-6 and the power transmission loop coil TL of (b)-10 are bonded together to form the power transmission coil TC. (b)-12: Connect the connection terminal O1 and the connection terminal O2 to the power transmitting unit TR (in the case of the power transmitting device T) or the power receiving unit RV (in the case of the power receiving device R).

[0059] As described above, in power transmission using the power transmission system S of the first embodiment including the power transmitting coil TC and the power receiving coil RC of the first embodiment, the copper thin-film wires TL11 and TL12 constituting the power transmitting loop coil TL (or the power receiving loop coil RL) stacked concentrically around the power transmitting open coil TO (or the power receiving open coil RO) are parallel to the winding direction of the copper thin-film wires. This reduces the influence of the skin effect caused by the current flowing through the power transmitting loop coil TL (or the power receiving loop coil RL) and can reduce the resistance of the power transmitting loop coil TL (or the power receiving loop coil RL) and the power transmitting coil TC (or the power receiving coil RC). This reduces losses in the power transmitting loop coil TL (or the power receiving loop coil RL) and the power transmitting coil TC (or the power receiving coil RC) and allows a large high-frequency current to flow, thereby improving the efficiency of the power transmitting coil TC (or the power receiving coil RC).

[0060] Furthermore, since the copper thin film wire TL11 and the copper thin film wire TL12 that make up the power transmitting loop coil TL (or the power receiving loop coil RL) are formed within one layer of the power transmitting coil TC (or the power receiving coil RC), the manufacturing process for the power transmitting coil TC (or the power receiving coil RC) can be simplified while further reducing the resistance values of the power transmitting loop coil TL (or the power receiving loop coil RL) and the power transmitting coil TC (or the power receiving coil RC).

[0061] The effect of power transmission using the power transmission system S of the first embodiment including the power transmitting coil TC and the power receiving coil RC of the first embodiment will be described later as a first example using FIG. 12 and the like.

[0062] Furthermore, although the copper thin film wire TL11 and the copper thin film wire TL12 in the first embodiment are parallel, the copper thin film wire TL11 and the copper thin film wire TL12 may alternatively be configured to intersect at one or more points in the winding of the power transmission loop coil TL while maintaining insulation from each other, as in the second or third embodiment described below.

[0063] (B) Second embodiment Next, a second embodiment of the present invention will be described with reference to Fig. 8 and Fig. 9. Fig. 8 is a plan view showing the structure of a power transmission loop coil of the second embodiment, and Fig. 9 is an enlarged perspective conceptual view showing the detailed structure of the power transmission loop coil.

[0064] In the first embodiment described above, the power transmitting coil TC and the power receiving coil RC are configured with two parallel thin-film copper wires, TL11 and TL12. In contrast, in the second embodiment described below, the power transmitting coil and the power receiving loop coil are configured with three parallel thin-film copper wires that intersect with each other.

[0065] The configuration of the power transmitting coil of the second embodiment and the configuration of the power receiving coil of the second embodiment are basically the same. The configuration of the power receiving loop coil in the power receiving coil of the second embodiment is also the same as the configuration of the power transmitting loop coil in the power transmitting coil of the second embodiment. Furthermore, the configuration of the power transmitting open coil in the power transmitting coil of the second embodiment and the configuration of the power receiving open coil in the power receiving coil of the second embodiment are the same as the configuration of the power transmitting open coil TO and the configuration of the power receiving open coil RO in the first embodiment, respectively. Therefore, in the following explanation, only the configuration of the power transmitting loop coil of the second embodiment will be described. In this case, the same components as those in the power transmitting loop coil TL of the first embodiment are designated by the same component numbers, and detailed explanations will be omitted.

[0066] 8 and 9, the power transmitting loop coil TL2 of the second embodiment is made up of copper thin-film wires TL20 to TL22 formed in two adjacent layers of the power transmitting coil of the second embodiment. The power transmitting loop coil TL2 is made up of the copper thin-film wires TL20 to TL22 wound in parallel three times (three turns) in portions other than the curved portions C2 at the four corners and multiple intersections CG2 (described later), and both ends (the centers of the right sides in the case of FIG. 8) of the copper thin-film wires TL20 to TL22 are connected to connection terminals O1 and O2, which connect the copper thin-film wires TL20 to TL22 and are also connected to the power transmitting unit of the second embodiment.

[0067] Each of the copper thin-film wires TL20 to TL22 has the same width and thickness around the entire circumference of the power transmission loop coil TL2, except for each curved portion C2 and each intersection CG2. Furthermore, the copper thin-film wires TL20 to TL22 have straight portions at their upper, lower, left, and right sides in FIG. 8 , which are connected by a curved portion C2. In each straight portion, as shown in FIG. 9 , the copper thin-film wires TL20 to TL22 are formed within each of the adjacent two layers. Furthermore, at each curved portion C2, the copper thin-film wires TL20 to TL22 are connected to a uniform copper thin-film wire. Furthermore, each of the copper thin-film wires TL20 to TL22 is formed so that one of the copper thin-film wires TL20 to TL22 intersects with the other two at the intersection CG2 while maintaining mutual insulation. Each intersection CG2 causes one of the positions to be swapped with the other two positions in the radial direction of the power transmitting coil of the second embodiment. Each intersection CG2 corresponds to an example of a "swapped portion" in the present invention. The winding center of the copper thin-film wires TL20 to TL22 that form the power transmitting loop coil TL2 and the winding center of the copper thin-film wire that forms the power transmitting open coil of the second embodiment are the same or approximately the same.

[0068] On the other hand, at each intersection CG2 (for example, the intersection CG2 indicated by the dashed line in FIGS. 8 and 9), as shown in FIG. 9, for example, the copper thin-film wire TL22 is connected by the connection CN2 via a via (not shown) in a layer different from the other copper thin-film wires TL20 and TL21 connected by the connection CN2. This results in a configuration in which the copper thin-film wire TL22 intersects with the copper thin-film wire TL20 and TL21 in the radial direction of the power transmitting coil of the second embodiment while maintaining insulation between the copper thin-film wire TL22 and the copper thin-film wire TL21. As a result, in the power transmitting loop coil TL2, at each intersection CG2, one of the copper thin-film wires TL20 to TL22 intersects with the other two, as described above.

[0069] As described above, according to power transmission using the power transmission system of the second embodiment including the power transmission coil of the second embodiment including the power transmission loop coil TL2 and the power receiving coil of the second embodiment including the power receiving loop coil of the second embodiment having the same configuration as the power transmission loop coil TL2, in addition to the effects achieved by power transmission using the power transmission system S of the first embodiment described above, since the power transmission loop coil TL2 (or the power receiving loop coil of the second embodiment) is made of copper thin film wire TL20 to copper thin film wire TL22, the resistance values of the power transmission loop coil TL2 (or the power receiving loop coil of the second embodiment) and the power transmission coil of the second embodiment (or the power receiving coil of the second embodiment) can be effectively reduced.

[0070] Furthermore, since each intersection CG2 is provided on the power transmission loop coil TL2, the influence of the skin effect can be further reduced, thereby reducing the resistance value of the power transmission loop coil TL2 (or the power receiving loop coil of the second embodiment) and the power transmission coil of the second embodiment (or the power receiving coil of the second embodiment).

[0071] Furthermore, since the copper thin film wires TL20 to TL22 are respectively formed in different layers in the power transmission coil of the second embodiment (or the power receiving coil of the second embodiment), by increasing the cross-sectional area of the copper thin film wires constituting the power transmission loop coil TL2 (or the power receiving loop coil of the second embodiment), the resistance value of the power transmission loop coil TL2 (or the power receiving loop coil of the second embodiment) and the power transmission coil of the second embodiment (or the power receiving coil of the second embodiment) can be further reduced.

[0072] The effect of power transmission using the power transmission system of the second embodiment including the power transmitting coil of the second embodiment and the power receiving coil of the second embodiment will be described later as a second example using FIG. 13 and the like.

[0073] (C) Third embodiment Next, a third embodiment of the present invention will be described with reference to Fig. 10 and Fig. 11. Fig. 10 is a plan view showing the structure of a power transmission loop coil of the third embodiment, and Fig. 11 is an enlarged perspective conceptual view showing the detailed structure of the power transmission loop coil.

[0074] In the power transmitting coil TC and power receiving coil RC of the first embodiment described above, the power transmitting loop coil TL and power receiving loop coil RL are configured from two parallel copper thin-film wires TL11 and TL12. In the power transmitting coil and power receiving coil of the second embodiment described above, the power transmitting loop coil TL2 and power receiving loop coil of the second embodiment are configured from three partially parallel copper thin-film wires TL20 to TL22. In contrast, in the power transmitting coil and power receiving coil of the third embodiment described below, the power transmitting loop coil and power receiving loop coil are configured from four parallel copper thin-film wires that intersect with each other.

[0075] The configuration of the power transmitting coil of the third embodiment and the configuration of the power receiving coil of the third embodiment are basically the same. The configuration of the power receiving loop coil in the power receiving coil of the third embodiment is also the same as the configuration of the power transmitting loop coil in the power transmitting coil of the third embodiment. Furthermore, the configuration of the power transmitting open coil in the power transmitting coil of the third embodiment and the configuration of the power receiving open coil in the power receiving coil of the third embodiment are also the same as the configuration of the power transmitting open coil TO and the power receiving open coil RO of the first embodiment, respectively. Therefore, in the following explanation, only the configuration of the power transmitting loop coil of the third embodiment will be described. In this case, the same components as those in the power transmitting loop coil TL of the first embodiment will be assigned the same component numbers, and detailed explanations will be omitted.

[0076] 10 and 11 , the power transmitting loop coil TL3 of the third embodiment is composed of copper thin-film wires TL30 to TL33 formed in two adjacent layers of the power transmitting coil of the third embodiment. In FIG. 10 , for ease of understanding, the copper thin-film wire TL30 is shown hatched, the copper thin-film wire TL32 is shown cross-hatched, and the copper thin-film wires TL31 and TL33 are shown without hatching. The power transmitting loop coil TL3 is composed of the copper thin-film wires TL30 to TL33 wound in parallel three times (three turns) in a portion other than the curved portions C3 at the four corners and multiple intersections CG3 (described later). Both ends (the centers of the right sides in FIG. 10 ) of the copper thin-film wires TL30 to TL33 are connected to connection terminals O1 and O2, which connect the copper thin-film wires TL30 to TL33 and are also connected to the power transmitting unit of the third embodiment. For clarity in the drawing, only the positions of the curved portions C3 and the intersections CG3 are indicated by dashed lines in Fig. 10, and the specific configurations of the curved portions C3 and the intersections CG3 are shown as enlarged perspective conceptual diagrams in Fig. 11. Furthermore, for clarity in Fig. 10, the copper thin film wire TL30 is shown by a half-hatched pattern, the copper thin film wire TL32 is shown by a double-hatched pattern, and the copper thin film wires TL31 and TL33 are shown without hatching.

[0077] Each of the copper thin-film wires TL30 to TL33 has the same width and thickness around the entire circumference of the power transmission loop coil TL3, except for each curved portion C3 and each intersection CG3. Furthermore, the copper thin-film wires TL30 to TL33 have straight portions at their upper, lower, left, and right sides in FIG. 10 , which are connected by a curved portion C2. In each straight portion, as shown in FIG. 11 , the copper thin-film wires TL30 to TL33 are formed within each of the two adjacent layers. Furthermore, as shown in FIG. 11( b ), each of the copper thin-film wires TL30 to TL33 is formed such that, at each intersection CG3, the copper thin-film wire TL30 and the copper thin-film wire TL31 intersect while maintaining mutual insulation, and similarly, the copper thin-film wire TL32 and the copper thin-film wire TL33 intersect while maintaining mutual insulation. Due to each intersection CG3, in a pair of the copper thin-film wires TL30 and TL31, the positions of the copper thin-film wires TL30 and TL31 are interchanged in the radial direction of the power transmitting coil of the third embodiment. Similarly, in a pair of the copper thin-film wires TL32 and TL33, the positions of the copper thin-film wires TL32 and TL33 are interchanged in the radial direction of the power transmitting coil of the third embodiment.

[0078] 11(a) , the dashed-line ellipse including the curved portion C3 in the upper left corner of FIG. 10 is formed so that, at each curved portion C3, a pair of copper thin-film wires TL30 and TL31 and a pair of copper thin-film wires TL32 and TL33 intersect while maintaining mutual insulation. Due to each curved portion C3, the positions of the pair of copper thin-film wires TL30 and TL31 and the pair of copper thin-film wires TL32 and TL33 are interchanged in the radial direction of the power transmitting coil of the third embodiment. Furthermore, the winding center of the copper thin-film wires TL30 to TL33 that make up the power transmitting loop coil TL3 and the winding center of the copper thin-film wires that make up the power transmitting open coil of the third embodiment are aligned or substantially aligned with each other.

[0079] 11(b), at each intersection CG3, the copper thin-film wire TL30 and the copper thin-film wire TL32 are connected by the connection portion CN3, for example, via a via (not shown), in a layer different from the other copper thin-film wires TL31 and TL33 connected by the connection portion CN3. This results in a configuration in which the copper thin-film wire TL30 intersects with the copper thin-film wire TL31 in the radial direction of the power transmitting coil of the third embodiment while maintaining insulation from the copper thin-film wire TL31, and the copper thin-film wire TL32 intersects with the copper thin-film wire TL33 in the radial direction of the power transmitting coil of the third embodiment while maintaining insulation from the copper thin-film wire TL33. This results in the power transmitting loop coil TL3 being configured such that, at each intersection CG3, the copper thin-film wire TL30 intersects with the copper thin-film wire TL31, and the copper thin-film wire TL32 intersects with the copper thin-film wire TL33, as described above.

[0080] As described above, according to power transmission using the power transmission system of the third embodiment including the power transmission coil of the third embodiment including the power transmission loop coil TL3 and the power receiving coil of the third embodiment including the power receiving loop coil of the third embodiment having the same configuration as the power transmission loop coil TL3, in addition to the effects achieved by power transmission using the power transmission system S of the first embodiment described above, since the power transmission loop coil TL3 (or the power receiving loop coil of the third embodiment) is made of copper thin film wire TL30 to copper thin film wire TL33, the resistance values of the power transmission loop coil TL3 (or the power receiving loop coil of the third embodiment) and the power transmission coil of the third embodiment (or the power receiving coil of the third embodiment) can be effectively reduced.

[0081] Furthermore, since the transmitting loop coil TL3 is provided with each curved portion C3 and each intersection portion CG3, the influence of the skin effect can be further reduced, thereby reducing the resistance value of the transmitting loop coil TL3 (or the receiving loop coil of the third embodiment) and the transmitting coil of the third embodiment (or the receiving coil of the third embodiment).

[0082] Furthermore, since the copper thin film wires TL30 to TL33 are respectively formed in different layers in the power transmission coil of the third embodiment (or the power receiving coil of the third embodiment), by increasing the cross-sectional area of the copper thin film wires constituting the power transmission loop coil TL3 (or the power receiving loop coil of the third embodiment), the resistance value of the power transmission loop coil TL3 (or the power receiving loop coil of the third embodiment) and the power transmission coil of the third embodiment (or the power receiving coil of the third embodiment) can be further reduced. [Example]

[0083] (A) First Example Next, the effect of power transmission using the power transmission system S of the first embodiment including the power transmitting coil TC and the power receiving coil RC of the first embodiment will be described with reference to FIG. 12 , based on experimental results (simulation results; the same applies below) by the inventors of the present application. FIG. 12 is a diagram showing the relationship between resistance value and frequency as an effect of the coil structure of the first embodiment. In the following explanation, the simulation results of the effect of power transmission using the power transmission system S of the first embodiment will be described in comparison with the simulation results of the effect of power transmission using power transmission systems including power transmitting coils and power receiving coils of different configurations, including conventional examples.

[0084] The specifications of the experiment whose results are shown in Fig. 12 are as follows: In the following explanation, the specifications of the power transmitting coil are explained, but the specifications of the power receiving coil used in the experiment are the same.

[0085] (1) The specifications of the power transmission coil TC for which the experimental results are shown as examples (see ▲ and ● marks in Figure 12) Number of turns of copper thin film wire TL11 and copper thin film wire TL12: 3 (see Figure 2) The width of the copper thin film wire TL11 and copper thin film wire TL12 is 4 mm. Distance between copper thin film wire TL11 and copper thin film wire TL12 in one winding: 4 mm Number of turns of coil CL1: 10.5 (see Figures 3, 5, and 6) Number of turns of coil CL2: 2.5 (see Figures 4 and 6) The thickness of the copper thin film wires TL11 and TL12 and the coils CL1 and CL2: 0.2 mm In the embodiment shown by the ● mark in FIG. 12, a coil made of a copper thin film wire TL11 and a copper thin film wire TL12 is concentrically laminated in two layers. (2) The specifications of the power transmission coils whose experimental results are shown as comparative examples including the conventional example (see circles and squares in Figure 12) Except for the following points, the shape and other specifications are the same as the transmitting coil TC. The first conventional example of a power transmission loop coil is made up of a single copper thin film wire wound around a wire 8 mm wide (see circle in Figure 12). The second conventional example of a power transmission loop coil is made up of two concentric layers of a single 8 mm wide copper thin film wire wound around it (see the square in Figure 12). The structures of the receiving coils in the comparative example and each of the conventional examples are the same as those of the transmitting coils in the comparative example and each of the conventional examples.

[0086] As shown in Figure 12, firstly, in the low-frequency range below 1 kHz, the resistance of each coil is almost the same as the DC resistance, so compared to a single-layer transmission loop coil (see marks ▲ and ○ in Figure 12), a two-layer transmission loop coil (see marks ● in Figure 12) simply doubles the cross-sectional area of the copper thin film wire used as the transmission loop coil, and therefore its resistance value is halved. Furthermore, in both the single-layer and double-layer configurations, there is no difference in the resistance values between the first and second conventional examples with a width of 8 mm (see marks ○ and □ in Figure 12) and the case where two parallel-wound copper thin film wires, each 4 mm wide, are wound (see marks ● and ▲ in Figure 12).

[0087] On the other hand, as the frequency gradually increases, the resistance begins to increase due to the skin effect at frequencies around 10 kHz. However, comparing the first conventional example (see circle marks in FIG. 12 ) and the second conventional example (see square marks in FIG. 12 ) with a width of 8 mm, we see that the effect of the double layering is lost around 100 kHz, close to the 85 kHz frequency used in electric vehicle transmission. This is thought to be due to the skin effect and the proximity effect, which further increases the resistance of the double-layered copper thin film wire. In contrast, around 100 kHz, the resistance increase is within an acceptable range when two parallel-wound copper thin film wires, each 4 mm wide (see ● and ▲ marks in FIG. 12 ) are used. As is clear from FIG. 12 , the double-layered power transmission loop coil TL (copper thin film wire TL11 and copper thin film wire TL12) can further suppress the increase in resistance compared to the power transmission coil TC structure of the first embodiment (see ● marks in FIG. 12 ).

[0088] (B) Second Example Next, the effect of power transmission using the power transmission system of the second embodiment including the power transmitting coil and the power receiving coil of the second embodiment will be described with reference to FIG. 13 , based on the results of an experiment conducted by the inventors of the present application. FIG. 13 is a diagram showing the relationship between S parameters and frequency, which is an effect of the coil structure of the second embodiment. In the following explanation, the results of a simulation of the effect of power transmission using the power transmission system of the second embodiment will be described in comparison with the results of a simulation of the effect of power transmission using a power transmission system including a conventional power transmitting coil and a power receiving coil.

[0089] The specifications of the experiment whose results are shown in Fig. 13 are shown below. Note that in the following explanation, the specifications of the power transmitting coil are explained, but the specifications of the power receiving coil used in the experiment are the same.

[0090] (1) The specifications of the power transmission coil of the second embodiment, the experimental results of which are shown as the second example (see the solid line in FIG. 13 ), Number of turns of copper thin film wire TL30 to copper thin film wire TL32: 3 (see Figure 2) Width of copper thin film wire TL30 and copper thin film wire TL32: 3 mm each Number of turns of coil CL1: 10.5 (see Figures 3, 5, and 6) Number of turns of coil CL2: 2.5 (see Figures 4 and 6) The thickness of the copper thin film wires TL30 to TL32 and the coils CL1 and CL2: 0.2 mm (2) Specifications of the power transmission coil shown in the experimental results as a conventional example (see dashed line in Figure 13) The shape and other specifications are the same as those of the power transmission coil of the second embodiment, except for the following points: The transmission loop coil is made up of a single winding of a 10mm-wide thin copper wire. The structure of the conventional receiving coil is the same as that of the conventional transmitting coil. As a result, the total cross-sectional area of the copper thin-film wires TL20 to TL22 is smaller than the cross-sectional area of the copper thin-film wires that make up the conventional transmitting loop coil.

[0091] 13, the graph showing the real part of the S-parameter is sharper when the power transmitting loop coil TL2 is used than when the conventional power transmitting loop coil is used. This shows that the configuration of the copper thin-film wires TL20 to TL22 reduces power loss in the power transfer system of the second embodiment, which includes the power transmitting loop coil TL2 and the power receiving loop coil of the second embodiment. This shows that in a power transmission coil including a conventional power transmission loop coil and a power receiving coil including a conventional power receiving loop coil, the skin effect causes current density to concentrate at both ends of the copper thin film wire (both radial ends of the conventional power transmission coil and power receiving coil), whereas in the power transmission system of the second embodiment including the power transmission loop coil TL2 and the power receiving loop coil of the second embodiment, the positions of the copper thin film wire TL20 to the copper thin film wire TL22 can be swapped between the radial ends of the power transmission loop coil TL2 and the power receiving loop coil of the second embodiment and their centers, thereby suppressing an increase in the resistance value of the power transmission loop coil TL2 and the power receiving loop coil of the second embodiment, and the power transmission coil of the second embodiment and the power receiving coil of the second embodiment (or reducing the resistance value).

[0092] Next, modified embodiments of the present invention will be described. The configuration of the power transmission system of each of the above-described embodiments may be modified as shown in the following (A) to (K). The inventors of the present invention have confirmed that even when these modifications are made, the same effects as those of the above-described power transmission system can be achieved.

[0093] (A) First Variation First, as a first modified embodiment, in the power transmitting open coil TO (or the power receiving open coil RO) of the first embodiment, the coil CL1 and the coil CL2 are connected, and the power transmitting open coil TO (or the power receiving open coil RO) and the power transmitting loop coil TL (or the power receiving loop coil RL) are mutually insulated. However, other than this, either one or both of the coils CL1 and CL2 may be connected to the power transmitting loop coil TL (or the power receiving loop coil of the first embodiment). The configuration of this first modified embodiment is similar to that of the power transmitting loop coil TL2 of the second embodiment (or the power receiving loop coil of the second embodiment) or the power transmitting loop coil TL3 of the third embodiment (or the power receiving loop coil of the third embodiment).

[0094] (B) Second Variation Next, as a second modified embodiment, the copper thin-film wire TL11 and the copper thin-film wire TL12 constituting the power transmitting loop coil TL (or the power receiving loop coil RL) of the first embodiment may be formed in different layers of the power transmitting coil TC (or the power receiving coil RC). The configuration of this second modified embodiment is similar to that of the power transmitting loop coil TL2 of the second embodiment (or the power receiving loop coil of the second embodiment) or the power transmitting loop coil TL3 of the third embodiment (or the power receiving loop coil of the third embodiment).

[0095] (C) Third Variation Next, as a third variant, in the transmitting open coil TO (or receiving open coil RO) of each embodiment, the number of turns of the coil CL1 and the coil CL2 that make up each coil are ten and a half turns (10.5 turns) and two and a half turns (2.5 turns), respectively, but other than these, the number of turns of coil CL1 and coil CL2 may be different from those described above, or the number of turns of coil CL1 and the number of turns of coil CL2 may be the same.

[0096] (D) Fourth Variation Next, as a fourth variant, in the power transmitting open coil TO (or power receiving open coil RO) of each embodiment, for example, the power transmitting loop coil TL (or power receiving loop coil RL) and coil CL1 of the first embodiment are formed in different layers, but they may be formed in the same layer and the power transmitting loop coil TL (or power receiving loop coil RL) and coil CL1 may be wound concentrically.

[0097] (E) Fifth Transformation Next, as a fifth modified embodiment, the order of coil CL1 and coil CL2 of the first embodiment may be reversed when viewed from the side of the power transmitting loop coil TL (or the power receiving loop coil RL) of the first embodiment. The configuration of this fifth modified embodiment is similar to that of the power transmitting loop coil TL2 of the second embodiment (or the power receiving loop coil of the second embodiment) or the power transmitting loop coil TL3 of the third embodiment (or the power receiving loop coil of the third embodiment).

[0098] (F) Sixth Transformation Next, in a sixth modified embodiment, the positions of the power transmitting loop coil TL and the power transmitting open coil TO in the power transmitting coil TC of the first embodiment may be interchanged, and the positions of the power receiving loop coil RL and the power receiving open coil RO in the power receiving coil RC of the first embodiment may be interchanged. In this sixth modified embodiment, the power transmitting loop coil TL of the power transmitting coil and the power receiving loop coil RL of the power receiving coil are arranged opposite each other in the overall power transfer system of the sixth modified embodiment. Furthermore, the configuration of the sixth modified embodiment is similar to that of the power transmitting loop coil TL2 of the second embodiment (or the power receiving loop coil of the second embodiment) or the power transmitting loop coil TL3 of the third embodiment (or the power receiving loop coil of the third embodiment).

[0099] (G) Seventh Transformation Next, as a seventh variant, in each embodiment, the widths of coils CL1 and CL2 are configured to increase from the outer periphery to the inner periphery, but in addition to this, the widths of coils CL1 and CL2 may be the same over the entire circumference.

[0100] (H) Eighth Transformation Next, as an eighth modified embodiment, while the power transmitting open coil TO (or power receiving open coil RO) in each embodiment has a two-layer laminated structure of coil CL1 and coil CL2, the power transmitting open coil (or power receiving open coil) may be configured by laminating four coils. In this case, a copper thin film wire is wound counterclockwise around the first coil from its outermost portion to its innermost portion and connected to the second coil at the innermost portion. A copper thin film wire is wound clockwise around the second coil from its innermost portion connected to the first coil to its outermost portion and connected to the third coil at the outermost portion. Furthermore, a copper thin film wire is wound counterclockwise around the third coil from its outermost portion to its innermost portion and connected to the fourth coil at the innermost portion. A copper thin film wire is wound clockwise around the fourth coil from its innermost portion connected to the third coil to its outermost portion. It is also preferable that the outermost end of the first coil and the outermost end of the fourth coil are each configured as open ends.

[0101] (I) 9th transformation Next, as a ninth modified embodiment, in the power transmitting open coil TO (power receiving open coil RO) of each embodiment, the winding direction (counterclockwise) of the coil CL1 and the winding direction (clockwise) of the coil CL2 are opposite, but these may be the same. This also applies to the four-layer structure of the eighth modified embodiment.

[0102] (J) Tenth Transformation Next, as a tenth variant, in each of the above-described embodiments, the radial position of each winding of coil CL1 in the transmitting open coil TO (receiving open coil RO) is configured to match the radial position of each winding of coil CL2 (see Figures 3, 4, and 6), but this is not limited to this. Even if the radial positions of each winding are different, as long as coils CL1 and CL2 are stacked, it is possible to adjust the parasitic capacitance as desired, and an effect equivalent to that of the above-described power transmission system S can be achieved.

[0103] (K) 11th Transformation Next, as an eleventh modified embodiment, a capacitor may be further connected in series or parallel to the end of the power transmitting open coil TO or the power receiving open coil RO that is an open end in the first embodiment, or in parallel to the power transmitting loop coil TL or the power receiving loop coil RL, to adjust the parasitic capacitance of the power transmitting loop coil TL or the power receiving loop coil RL, or the power transmitting open coil TO or the power receiving open coil RO, thereby lowering the resonant frequency. In this case, when a capacitor is connected in series to the open end of either the power transmitting open coil TO or the power receiving open coil RO, the terminal of the capacitor that is not connected to either of the open ends may be set as the open end. Furthermore, the configuration of the eleventh modified embodiment is similar to that of the power transmitting coil of the second embodiment (or the power receiving coil of the second embodiment) or the power transmitting coil of the third embodiment (or the power receiving coil of the third embodiment).

[0104] (L) 12th Transformation Next, as a twelfth modified embodiment, the power transmitting coil TC (or the power receiving coil RC) of each embodiment may be configured without the power transmitting open coil TO (or the power receiving open coil RO) and with an increased number of turns in the power transmitting loop coil TL (or the power receiving loop coil RL). In this case, the number of turns in the power transmitting loop coil TL (or the power receiving loop coil RL) is preferably, for example, six turns. This configuration in which the number of turns in the power transmitting loop coil TL (or the power receiving loop coil RL) of each embodiment is six turns (six turns) and the power transmitting open coil TO (or the power receiving open coil RO) is omitted will be referred to as the "first pattern" below.

[0105] Furthermore, in the first pattern of this twelfth variant, the connection manner between the connection terminals O1 and O2 and the power transmitting loop coil TL (or power receiving loop coil RL) in each of the above-mentioned embodiments may be the same as the configuration in each embodiment, i.e., the configuration in which both ends of the power transmitting loop coil TL (or power receiving loop coil RL) are connected to the connection terminals O1 and O2, respectively, at the outermost periphery of the power transmitting loop coil TL (or power receiving loop coil RL). Alternatively, as in the power transmitting loop coil TL4 shown in Figure 14 (a power transmitting loop coil TL4 consisting of two parallel copper thin film wires TL40 and TL41), the winding of the power transmitting loop coil (or power receiving loop coil) may be in one direction from the outermost periphery to the innermost periphery, with the ends at the outermost periphery connected to, for example, the connection terminal O1, and the ends of the copper thin film wires TL40 and TL41 drawn from the innermost periphery to the outermost periphery by a layered structure with a jumper wire or an insulating layer sandwiched therebetween, may be connected to, for example, the connection terminal O2. This modified connection between both ends of the power transmitting loop coil (or the power receiving loop coil) and the connection terminal O1 and the connection terminal O2 is hereinafter referred to as a "second pattern."

[0106] Furthermore, in the twelfth modified embodiment, the number of windings of the power transmitting loop coil TL (or the power receiving loop coil RL) may be seven turns. In this case, as in the power transmitting loop coil TL5 shown in Fig. 15 , the copper thin-film wire TL50 and the copper thin-film wire TL51 may be wound in parallel three and a half turns (3.5 turns) from the outer periphery of the power transmitting loop coil TL5, and then three and a half turns (3.5 turns) from the innermost periphery, and each of the copper thin-film wire TL50 and the copper thin-film wire TL51 may have a two-layer structure with an insulating layer interposed therebetween (see the copper thin-film wire TL20 and the copper thin-film wire TL21 illustrated in Fig. 9 ). Furthermore, like the power transmission loop coil TL6 shown in FIG. 16 (a power transmission loop coil TL6 formed by two parallel copper thin film wires TL60 and TL61), the power transmission loop coil TL5 shown in FIG. 15 may have an intersection CX at its innermost periphery where the copper thin film wires TL60 and TL61 intersect, using a layered structure with a jumper wire or an insulating layer sandwiched therebetween.

[0107] Furthermore, in a twelfth variant in which the number of windings of the power transmitting loop coil TL (or the power receiving loop coil RL) is seven turns, the relationship between the parallel copper thin film wires in each winding may be configured so that the relationship between the widths of the copper thin film wires satisfies the following relationships (A) and (B), as in the power transmitting loop coil TL7 (power transmitting loop coil TL7 consisting of two parallel copper thin film wires), part of the structure of which (corresponding to part of the upper side in FIG. 15 or 16) is shown in FIG. 17.

[0108] (A) In one winding, the width of the innermost copper thin film wire TL71 is wider than the width of the outermost copper thin film wire TL70. That is, as shown in Fig. 17, starting from the outermost winding, the width of the copper thin film wire TL70-OT7 < the width of the copper thin film wire TL71-IN7, the width of the copper thin film wire TL70-OT6 < the width of the copper thin film wire TL71-IN6, the width of the copper thin film wire TL70-OT5 < the width of the copper thin film wire TL71-IN5, the width of the copper thin film wire TL70-OT4 < the width of the copper thin film wire TL71-IN4, the width of the copper thin film wire TL70-OT3 < the width of the copper thin film wire TL71-IN3, the width of the copper thin film wire TL70-OT2 < the width of the copper thin film wire TL71-IN2, and the width of the copper thin film wire TL70-OT1 < the width of the copper thin film wire TL71-IN1.

[0109] (B) In each winding, the sum of the widths of the copper thin-film wires TL70 and TL71 increases toward the inner periphery. That is, as shown in Fig. 17, (width of copper thin-film wire TL70-OT7 + width of copper thin-film wire TL71-IN7) < (width of copper thin-film wire TL70-OT6 + width of copper thin-film wire TL71-IN6) < (width of copper thin-film wire TL70-OT5 + width of copper thin-film wire TL71-IN5) < (width of copper thin-film wire TL70-OT4 + width of copper thin-film wire TL71-IN4) < (width of copper thin-film wire TL70-OT3 + width of copper thin-film wire TL71-IN3) < (width of copper thin-film wire TL70-OT2 + width of copper thin-film wire TL71-IN2) < (width of copper thin-film wire TL70-OT1 < width of copper thin-film wire TL71-IN1).

[0110] As a result of (A) and (B) above, the width of the copper thin film line TL70-OT7<the width of the copper thin film line TL70-OT6<the width of the copper thin film line TL70-OT5<the width of the copper thin film line TL70-OT4<the width of the copper thin film line TL70-OT3<the width of the copper thin film line TL70-OT2<the width of the copper thin film line TL70-OT1. Similarly, the width of the copper thin film line TL71-IN7<the width of the copper thin film line TL71-IN6<the width of the copper thin film line TL71-IN5<the width of the copper thin film line TL71-IN4<the width of the copper thin film line TL71-IN3<the width of the copper thin film line TL71-IN2<the width of the copper thin film line TL71-IN1.

[0111] Here, according to the results of experiments conducted by the inventors of the present application on the effect of transmitting power using a power transmitting coil (or a power receiving coil) consisting only of a power transmitting loop coil (or a power receiving loop coil) having the configuration of each of the first pattern and the second pattern (the power transmitting loop coil TL4 shown in Figure 14 (single layer structure for the copper thin film wire TL40 and the copper thin film wire TL41)), when the size of the power transmitting coil (or the power receiving coil) is 320 mm x 320 mm, the line width of each of the parallel copper thin film wires in the power transmitting loop coil (or the power receiving loop coil) of the first pattern or the second pattern is 4 mm, the spacing between the parallel copper thin film wires is 4 mm, the thickness of each copper thin film wire is 0.2 mm, and capacitors with a capacity of 300 nanofarads are connected in parallel to both ends of the power transmitting loop coil (or the power receiving loop coil), the transmission efficiency of the power transmission system was 86.8% for the first pattern and 87.5% for the second pattern. On the other hand, in a similar experiment using a power transmission loop coil formed by winding a single copper thin film wire in the first pattern as a comparative example, the transmission efficiency of the power transmission system was 78.9%.The above experimental results corresponding to the twelfth modified embodiment show that by configuring the power transmission loop coil (or power receiving loop coil) using multiple parallel copper thin film wires, the resistance value of the power transmission loop coil (or power receiving loop coil) as a whole can be reduced (i.e., loss due to Joule heat can be suppressed), and therefore a large high-frequency current can be passed through, resulting in highly efficient power transmission.

[0112] 18 shows the results of an experiment conducted by the inventors of the present application on the effects of power transmission using only a power transmitting coil (or a power receiving coil) with respect to each of the power transmitting loop coils TL4 shown in Fig. 14 to the power transmitting loop coil TL7 shown in Fig. 17 (however, each of the thin-film copper wires TL40, etc. constituting each of the power transmitting loop coils TL4, etc. has a double-layer structure). The specifications of the coils used in the experiment are as follows: Dimensions: 230mm x 154mm Width of the parallel copper thin film wires at the outermost periphery: 2.0 mm on the outside of the coil and 3.0 mm on the inside of the coil (5.0 mm in total for the parallel copper thin film wires) Width of the parallel copper thin film wires at the innermost periphery: 3.5 mm on the outside of the coil and 5.5 mm on the inside of the coil (total of 9.0 mm for the parallel copper thin film wires)

[0113] According to the experiment, the impedance of the power transmitting coil (or power receiving coil) is in the order of power transmitting loop coil TL4 > power transmitting loop coil TL5 > power transmitting loop coil TL6 > power transmitting loop coil TL7, and it was found that at the frequency of 85 kHz at which power transmitting loop coil TL4 and the like are used, power transmitting coil loop coil TL7 has the lowest resistance and therefore the best transmission efficiency.

[0114] 17, the widths of the copper thin-film wires TL70-OT7 to TL70-IN1 are as described above. This is because the magnetic field strength increases toward the center of the power transmitting loop coil TL7, and therefore more current flows through the copper thin-film wires TL70-IN1 and the like on the inside of the power transmitting loop coil TL7. Therefore, the widths of the copper thin-film wires TL70-OT7 to TL70-IN1 are made wider toward the center of the power transmitting loop coil TL7 as a whole, thereby reducing the resistance. Therefore, as long as this purpose is achieved, the widths of adjacent copper thin-film wires in the power transmitting loop coil TL7 may be the same in some of the windings of the power transmitting loop coil TL7. [Industrial Applicability]

[0115] As described above, the present invention can be used in the field of contactless power transmission, and particularly when applied to the field of power transmission for charging storage batteries installed in electric vehicles, it can produce particularly significant effects. [Explanation of symbols]

[0116] S Power Transmission System R Power receiving device T Power transmission equipment V-Via RV power receiving unit RC receiving coil TR power transmission section TC transmitting coil TL, TL2, TL3, TL4, TL5, TL6, TL7 Transmission Loop Coil TO power transmission open coil RO power receiving open coil RL receiving loop coil O1, O2 connection terminals C2, C3 curved section TL11, TL12, TL20, TL21, TL22, TL30, TL31, TL32, TL33, TL40, TL41, TL50, TL51, TL60, TL61, TL71-IN1, TL71-IN2, TL71-IN3, TL71-IN4, TL71-IN5, TL71-IN6, TL71-IN7, TL70-OT1, TL70-OT2, TL70-OT3, TL70-OT4, TL70-OT5, TL70-OT6, TL70-OT7 Thin Film Copper Wire BF1, BF2 film CL1, CL2 coils CG2, CG3 intersection

Claims

1. A coil for contactless power transmission used to charge a storage battery mounted on an electric vehicle, At least a portion of the windings that constitute the coil and are made of thin-film conductors is composed of a plurality of parallel windings that are arranged in a radial direction of the coil and parallel to the winding direction of the windings, the parallel winding has a structure in which two thin film conductors are stacked in a direction perpendicular to a plane including the winding of the winding, and the two thin film conductors are connected in parallel to each other within one of the windings, the parallel winding circuit is composed of an outer-inner parallel winding circuit wound from the outer circumferential side to the inner circumferential side of the coil, and an inner-outer parallel winding circuit wound from the inner circumferential side to the outer circumferential side of the coil in the same direction as the outer-inner parallel winding circuit, A coil characterized in that the parallel windings in one turn of the coil are composed of a plurality of straight sections and curved sections connecting the plurality of straight sections.

2. 2. The coil according to claim 1, A coil characterized in that the parallel windings constituting one of the windings are formed in the same layer.

3. The coil according to claim 1 or 2, A coil characterized in that at least a portion thereof is composed of three of the parallel windings.

4. The coil according to claim 1 or 2, A coil characterized in that the coil is composed of four of the parallel wound wires.

5. The coil according to any one of claims 1 to 4, A coil characterized in that an interchange portion is provided on the winding of the coil, where the positions of each of the parallel windings are interchanged in a direction perpendicular to the winding direction.

6. The coil according to any one of claims 1 to 5, A coil characterized in that an intersection where the parallel windings intersect is provided at the innermost periphery of the coil.

7. The coil according to any one of claims 1 to 6, One of the windings is made up of two of the parallel windings, A coil characterized in that, in one of the windings, the width of the parallel winding on the inner periphery side is wider than the width of the parallel winding on the outer periphery side.

8. The coil according to claim 7, A coil characterized in that the width of the winding wire is wider toward the inner periphery of the coil.

9. The coil according to any one of claims 1 to 8, A coil characterized in that the frequency of the power transmitted by said coil is equal to or greater than 85 kilohertz and equal to or less than 1 megahertz.

10. A power transmission system includes a power transmission device and a power receiving device that is remote from the power transmission device, and transmits power from the power transmission device to the power receiving device in a contactless manner. The power transmission coil according to claim 1 , wherein the power transmission coil is disposed opposite the power receiving device; an output means for outputting power to be transmitted to the power transmitting coil; A power transmitting device comprising:

11. A power receiving device included in a power transmission system that includes a power transmitting device and a power receiving device separated from the power transmitting device and transmits power from the power transmitting device to the power receiving device in a contactless manner, a power receiving coil that is the coil according to any one of claims 1 to 9 and that is disposed opposite the power transmitting device; an input means connected to the receiving coil; A power receiving device comprising:

12. The power transmitting device according to claim 10; a power receiving device disposed at a distance from the power transmitting device and facing the power transmitting coil, the power receiving device receiving the power transmitted from the power transmitting device; A non-contact power transmission system comprising:

13. a power transmission device; 12. The power receiving device according to claim 11, wherein the power receiving device is disposed at a distance from the power transmitting device and the power receiving coil faces the power transmitting device, and receives power transmitted from the power transmitting device; A non-contact power transmission system comprising:

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