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

Abstract

To provide a coil or the like capable of improving efficiency as wireless power transmission even when a high frequency current is used.SOLUTION: In a power receiving coil RC or a power transmission coil TC for non-contact power transmission, a winding line TL constituting the transmission coil TC or the power receiving coil RC is composed of a thin film conductor TL1 and a thin film conductor TL2 parallel to the winding direction of the winding line TL, and is configured such that the sum of an interval SPL in the direction perpendicular to the winding direction of the thin film conductor TL1 and the thin film conductor TL2 and an interval SPT in the vertical direction of the adjacent winding line TL is longer than at least a threshold length corresponding to the frequency of power transmission.SELECTED DRAWING: Figure 2

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 are becoming more widespread. In such electric vehicles, the motor is driven by the power stored in the storage battery to move, so efficient charging of the storage battery is required. Therefore, as a method for charging the storage battery mounted on the electric vehicle without physically connecting a charging plug or the like to the electric vehicle, so-called wireless power transmission using a receiving coil and a transmitting coil that are separated and opposed to each other has been studied. Wireless power transmission methods generally include an electric field coupling method, an electromagnetic induction method, and a magnetic field resonance method. When these methods are compared from the viewpoints of, for example, the frequency of the power transmitted and received, the degree of freedom in the horizontal and vertical directions, and the transmission efficiency, the electric field coupling method using a capacitor or the magnetic field resonance method using a coil is considered to be promising as a wireless power transmission method for charging the storage battery mounted on the electric vehicle, and research and development into these methods is also being actively conducted. For example, the following Patent Document 1 can be given as a prior art document disclosing such background technology. This Patent Document 1 discloses a coil that transmits power by a magnetic field resonance method using a loop coil with one winding (1 turn) and an open coil with 5.5 windings (5.5 turns).

[0003] On the other hand, the frequency of the power transmitted and received by the wireless power transmission is predetermined for each device by law, and in the case of the power transmission to the electric vehicle, it is set to a high frequency of 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 from the surface toward the center. In addition, the higher the frequency of the current, the more the current is concentrated on the surface, and as a result, the AC resistance of the conductor increases. This phenomenon is known as the so-called "skin effect of the conductor." In the following description, the AC resistance of a conductor when a high-frequency current flows through the conductor is simply called "impedance." [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2011-200045 A 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-output 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-output power (current), the loss in the coil increases due to the generation of Joule heat, resulting in a problem of reduced efficiency as wireless power transmission.

[0006] In addition, as with the skin effect, another electrical phenomenon that reduces the efficiency of wireless power transmission is the so-called "conductor proximity effect," which occurs when conductors are wound in a coil close to each other. Therefore, measures must be taken to prevent the increase in resistance caused by this proximity effect.

[0007] The present invention has been made in consideration of the above problems and demands, and one example of the object of the present invention is to provide a coil that can improve the efficiency of wireless power transmission even when using a high-frequency current such as 85 kHz, and a non-contact power transmitting device, power receiving device, and power transfer system that use such a coil. [Means for solving the problem]

[0008] In order to solve the above problem, the invention described in claim 1 provides a coil for contactless power transmission, in which the windings constituting the coil are composed of a plurality of parallel windings, each of which is made of a thin-film conductor and parallel to the winding direction of the windings, and the sum of the spacing between the parallel windings constituting one of the windings in a direction perpendicular to the winding direction and the spacing between adjacent windings in the perpendicular direction is configured to be longer than at least a threshold length corresponding to the frequency of power transmission by the coil.

[0009] According to the invention described in claim 1, when the winding is formed of a plurality of parallel windings made of thin-film conductors parallel to the winding direction, the sum of the interval in the direction perpendicular to the winding direction between the parallel windings making up one winding and the interval in the perpendicular direction between adjacent windings is longer than at least the length corresponding to the frequency of power transmission. Therefore, it is possible to reduce the impedance of the coil due to the so-called skin effect or proximity effect caused by forming the parallel windings from thin-film conductors to reduce weight and cost, and it is possible to achieve both weight reduction and cost reduction, improved transmission efficiency, and prevention of an increase in operating temperature.

[0010] In order to solve the above problem, the invention described in claim 2 comprises: A coil for contactless power transmission, wherein a winding constituting the coil is made up of a plurality of parallel windings, each of which is parallel to a winding direction of the winding and made of a thin-film conductor, and the sum of the spacing in a direction perpendicular to the winding direction of the parallel windings constituting one of the windings and the spacing in the perpendicular direction of adjacent windings is longer than at least a threshold length corresponding to a frequency of power transmission by the coil, One of the windings is made up of two of the parallel windings, and in one of the windings, the width of the parallel winding on the inner side of the coil is wider than the width of the parallel winding on the outer side of the coil.

[0011] According to the invention described in claim 2, When the winding is made up of a plurality of parallel windings made of thin-film conductors parallel to the winding direction, the sum of the spacing in the direction perpendicular to the winding direction between the parallel windings making up one winding and the spacing in the perpendicular direction between adjacent windings is longer than at least the length corresponding to the frequency of power transmission. This makes it possible to reduce the impedance of the coil due to the so-called skin effect or proximity effect caused by forming the parallel windings from thin-film conductors to reduce weight and cost, and thus makes it possible to achieve both weight reduction and cost reduction, improved transmission efficiency, and prevention of increases in operating temperature. First winding circuit but It is composed of two parallel windings, and in one winding, the width of the parallel winding on the inner circumference side of the coil is wider than the width of the parallel winding on the outer circumference side of the coil. So By reducing the impedance of the coil, it is possible to achieve both weight reduction and cost reduction, improved transmission efficiency, and prevention of an increase in operating temperature.

[0012] In order to solve the above problem, the invention described in claim 3 is a coil described in claim 1 or claim 2, in which the winding circuit is composed of an outer-inner winding circuit composed of the parallel winding circuit wound from the outer periphery side to the inner periphery side of the coil, and an inner-outer winding circuit composed of the parallel winding circuit wound from the inner periphery side to the outer periphery side.

[0013] According to the invention recited in claim 3, in addition to the effects of the invention recited in claim 1 or claim 2, since the winding wire is composed of an outer-inner winding wire and an inner-outer winding wire, the impedance of the coil can be further reduced.

[0014] In order to solve the above problems, the invention recited in claim 4 provides the coil recited in any one of claims 1 to 3, in which the winding wire has a laminated structure.

[0015] According to the invention described in claim 4, in addition to the effect of the invention described in any one of claims 1 to 3, since the winding wire has a laminated structure, the impedance of the coil can be further reduced by increasing the cross-sectional area of ​​the winding wire constituting the coil.

[0016] In order to solve the above problem, the invention described in claim 5 is a coil described in any one of claims 1 to 4, wherein the threshold length in the perpendicular direction in the turns of the winding is 4.5 millimeters when the frequency is 85 kilohertz.

[0017] According to the invention described in claim 5, in addition to the effect of any one of the inventions described in claims 1 to 4, when the frequency of power transmission is 85 kHz, the sum of the spacing in a direction perpendicular to the winding direction of the parallel windings constituting one winding and the spacing in the perpendicular direction between adjacent windings is longer than the threshold length of 4.5 mm, so that the structure of the windings can be optimized and the impedance of the coil can be further reduced.

[0018] In order to solve the above problem, the invention described in claim 6 is the coil described in claim 5, wherein the spacing between adjacent windings in the perpendicular direction is 2 millimeters or more.

[0019] According to the invention recited in claim 6, in addition to the effect of the invention recited in claim 5, the distance between adjacent windings in a direction perpendicular to their winding direction is 2 millimeters or more, so that the structure of the windings can be optimized and the impedance of the coil can be further reduced.

[0020] In order to solve the above problem, the invention described in claim 7 is a power transmission system including a power transmission device and a power receiving device spaced apart from the power transmission device, and which transmits power from the power transmission device to the power receiving device in a non-contact manner, the power transmission device comprising a power transmission coil which is the coil described in any one of claims 1 to 6 and which is arranged opposite the power receiving device, and an output means which outputs the power to be transmitted to the power transmission coil.

[0021] In order to solve the above problem, the invention described in claim 8 relates to 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 transmits power from the power transmitting device to the power receiving device in a non-contact manner, the power receiving device comprising a power receiving coil that is the coil described in any one of claims 1 to 6 and is arranged opposite the power transmitting device, and an input means connected to the power receiving coil.

[0022] In order to solve the above problem, the invention described in claim 9 comprises a power transmission device described in claim 7, and a power receiving device arranged away from the power transmission device and facing the power transmission coil, the power receiving device receiving power transmitted from the power transmission device.

[0023] In order to solve the above problem, the invention described in claim 10 comprises a power transmitting device and a power receiving device described in claim 8, which is positioned 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.

[0024] According to the invention described in any one of claims 7 to 10, at least one of the power transmitting coil provided in the power transmitting device or the power receiving coil provided in the power receiving device that constitutes the power transmission system is a coil described in any one of claims 1 to 6. Therefore, when the power transmitting coil or the power receiving coil is placed opposite each other to perform non-contact power transmission, the impedance of the coil due to the skin effect or the proximity effect can be reduced, and it is possible to achieve both weight reduction and cost reduction, improved transmission efficiency, and prevention of an increase in operating temperature. Effect of the Invention

[0025] According to the present invention, when a winding is formed by a plurality of parallel windings made of thin film conductors parallel to the winding direction, the sum of the spacing in a direction perpendicular to the winding direction between the parallel windings constituting one winding and the spacing in the perpendicular direction between adjacent windings is longer than at least a length corresponding to the frequency of power transmission.

[0026] Therefore, it is possible to reduce the impedance of the coil due to the so-called skin effect or proximity effect, which is caused by forming the parallel windings from a thin film conductor in order to reduce weight and cost, and it is possible to achieve both weight and cost reduction, improved transmission efficiency, and prevention of an increase in operating temperature. [Brief description of the drawings]

[0027] [Figure 1] 1 is a block diagram showing a schematic configuration of a power transmission system according to an embodiment; [Diagram 2] FIG. 2 is a plan view illustrating a structure of a power transmission coil according to an embodiment. [Diagram 3] 11 is a diagram showing the relationship between impedance and frequency as an effect of the structures of the power transmitting coil and the power receiving coil of the embodiment. FIG. [Figure 4] 1 is a diagram showing the relationship between the structure of a power transmitting coil and a power receiving coil of an embodiment and impedance as an effect of the structure. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] Next, embodiments for carrying out the present invention will be described with reference to Figures 1 to 4. The embodiments and modifications described below are embodiments and modifications in which the present invention is applied to a power transmission system that transmits power for charging a storage battery mounted on an electric vehicle to the electric vehicle equipped with the storage battery in a non-contact manner by a magnetic field resonance method.

[0029] Here, the power transmission system using the magnetic field resonance method in the embodiment and modified form includes a power transmission coil described below that transmits power, and a power receiving coil described below that is positioned facing (i.e., opposite) the power transmission coil at a distance and receives the power transmitted from the power transmission coil.

[0030] (I) Overall configuration and operation of the power transmission system of the embodiment First, the overall configuration and operation of a power transmission system according to an embodiment will be described with reference to Fig. 1. Fig. 1 is a block diagram showing a schematic configuration of the power transmission system according to the embodiment.

[0031] As shown in FIG. 1, the power transmission system S of the embodiment is configured with 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. At this time, the power receiving device R is mounted on the electric vehicle and is 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 moves or stops. When the storage battery is charged, the electric vehicle is driven or stopped 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 the storage battery is charged by the power transmission system S of the embodiment, it can be configured to transmit power from the power transmitting device T to the power receiving device R mounted on the stopped electric vehicle via the power transmitting coil TC of the power transmitting device T installed on the ground below the stopping position. Alternatively, power may be continuously transmitted from a power transmitting device T to a power receiving device R mounted on a moving electric vehicle via power transmitting coils TC of a plurality of power transmitting devices T installed in a section of a certain distance on the road on which the electric vehicle is moving. 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.

[0032] Meanwhile, the power to be transmitted is input to the power transmitting coil TC from the power transmitting unit TR. The power receiving coil RC outputs the power received from the power transmitting coil TC to the power receiving unit RV by the magnetic resonance method. In this case, the power transmitting coil TC and the power receiving coil RC each correspond to an example of the "coil" of the present invention.

[0033] In the above configuration, the power transmission unit TR of the power transmission device T outputs power to be transmitted to the power receiving device R to the power transmission coil TC while complying with laws and regulations such as the Radio Act in the country in which the power transmission system S is used. At this time, the laws and regulations regulate the leakage magnetic field to be below a predetermined level, for example, taking into account the effect on the human body. In addition, in order to enable interconnection between all the power transmission devices T and the power receiving devices R, it is necessary for both of them to use a predetermined range of frequencies, and therefore the predetermined range of frequencies or frequency bands must follow the recommendations of international organizations such as ISO (International Organization for Standardization) or IEC (International Electrotechnical Commission) as the laws and regulations. In addition, the lower limit of the transmission efficiency taking into account a predetermined positional deviation between the power transmission coil TC and the power receiving coil RC is also specified by the international organizations or the laws and regulations, so that the power transmission system S is also required to have high power transmission efficiency.

[0034] Meanwhile, the power receiving coil RC of the power receiving device R that receives power from the power transmitting coil TC by 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 high-frequency power of 85 kHz) into a DC (direct current) current by, 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.

[0035] (II) Configuration of the transmitting coil TC (receiving coil RC) Next, the configuration of the power transmitting coil TC and the power receiving coil RC of the embodiment used in the power transfer system S of the above-mentioned embodiment will be described with reference to FIG. 2. The power transmitting coil TC and the power receiving coil RC of the embodiment basically have the same configuration. Therefore, in the following explanation, the structure of the power transmitting coil TC will be described. FIG. 2 is a plan view showing the structure of the power transmitting coil TC of the embodiment, and is a plan view of the power transmitting coil TC as viewed from the power transmitting unit TR side in the power transmitting device T (see FIG. 1).

[0036] As shown in a plan view in FIG. 2, the power transmission coil TC of the embodiment is configured by laminating a winding line TL, which is formed by winding two parallel wires, for example, copper thin film wire TL1 and copper thin film wire TL2, on an insulating film BF (described in detail later). In this configuration, each of the copper thin film wire TL1 and the copper thin film wire TL2 corresponds to an example of a "parallel winding line" of the present invention. Here, in the embodiment, the film BF is used for laminating the power transmission coil TC, but other insulating materials such as glass epoxy materials can also be used. In addition, in order to efficiently dissipate heat generated by the power transmission coil TC, a thin film material in which ceramic particles are dispersed, for example, can also be used. Furthermore, the centers of winding of the copper thin film wire TL1 and the copper thin film wire TL2 constituting the winding line TL are the same or approximately the same in each winding.

[0037] As shown in Fig. 2, the power transmission coil TC is formed by winding a winding line TL made of a copper thin film wire TL1 and a copper thin film wire TL2 wound in parallel to each other in the same layer, and has a connection terminal O1 and a connection terminal O2 on one side of the outermost circumference for connecting the copper thin film wire TL1 and the copper thin film wire TL2 and connecting the winding line TL to the power transmission unit TR. The power transmission coil TC is formed by winding a winding line TL made of parallel copper thin film wires TL1 and TL2 six times (6 turns), and both ends (the center of the right side in Fig. 2) of each of the copper thin film wires TL1 and TL2 (i.e., the winding line TL) serve as the connection terminals O1 and O2. Note that each of the copper thin film wires TL1 and TL2 in the example shown in Fig. 2 has the same width and thickness over the entire circumference of the winding line TL. Further, the winding circuit TL has straight portions at its upper side, lower side, left side, and right side in Fig. 2, and the straight portions are connected by curved portions having a substantially concentric arc shape. The copper thin-film wire TL1 and the copper thin-film wire TL2 cross each other at their intersections while being insulated from each other by a laminated structure (see Fig. 2) with an insulating layer sandwiched therebetween, or a method using a jumper wire, or the like. As will be described later, in the power transmitting coil TC or the power receiving coil RC of the embodiment, the width W1 and the width W2 of the copper thin-film wire TL1 and the copper thin-film wire TL2 shown in Fig. 2, the interval SPL between the copper thin-film wire TL1 and the copper thin-film wire TL2 in one turn of the winding circuit TL, and the interval SPT between adjacent winding circuits TL are optimized so as to reduce the impedance of the power transmitting coil TC or the power receiving coil RC when the width W1 and the width W2 of the copper thin-film wire TL1 and the interval SPL and the interval SPT are variously changed.

[0038] (III) Manufacturing method of the transmitting coil TC and the receiving coil RC Next, a method for manufacturing the power transmitting coil TC and the power receiving coil RC according to the embodiment will be outlined.

[0039] The manufacturing method may be a typical printed circuit board manufacturing process, i.e., a manufacturing method including the following steps (1) to (5). In this case, the material used in the manufacturing process may be, for example, a copper-clad laminate in which copper is pre-laminated on both sides of a glass epoxy board. In the following description, the copper-clad laminate is simply referred to as "CCL (Copper Clad Laminate)". (1) A hole is drilled at the location where the copper on both sides of the CCL is to be joined (connected), and copper is laminated in the order of electroless plating → electrolytic plating to electrically connect the copper on both sides (forming the so-called through hole). (2) Apply resist to one side of the copper thin film formed in (1) above. (3) The resist applied in (2) above is patterned into the copper thin film wire TL1 and the copper thin film wire TL2 (including the connection terminal O1 and the connection terminal O2). (4) After the patterning in (3) above, an etching process is performed to form the copper thin film wire TL1 and the copper thin film wire TL2 as the winding circuit TL. (5) 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). EXAMPLES

[0040] Next, in the power transmitting coil TC or the power receiving coil RC of the embodiment based on the configuration shown in Fig. 2, the width W1 and the width W2 and the interval SPL and the interval SPT are changed to various values ​​to measure the impedance (simulation results) will be described with reference to Fig. 3 and Fig. 4. Fig. 3 is a diagram showing the relationship between impedance and frequency as an effect of the structure of the power transmitting coil TC or the power receiving coil RC of the embodiment, and Fig. 4 is a diagram showing the relationship between the structure of the power transmitting coil TC or the power receiving coil RC and the impedance as an effect thereof.

[0041] In this case, Fig. 3 shows the relationship between the frequency of power transmission and the value obtained by multiplying the sum of the widths W1 and W2 by impedance when the widths W1 and W2 and the intervals SPL and SPT are changed to various values ​​in a power transmitting coil TC or a power receiving coil RC having a size (see Fig. 2) of 280 mm length by 280 mm width and a pitch PT (see Fig. 2) of 16 mm (six turns (6 turns) for the winding line TL) in a direction perpendicular to the winding direction of the winding line TL. In the following description, the sum of the widths W1 and W2 is simply referred to as "width (W1+W2)". For example, the continuous triangle marks in Fig. 3 show the relationship between the frequency and the value obtained by multiplying the width (W1+W2) by impedance in a power transmitting coil TC or a power receiving coil RC having both the widths W1 and W2 of 6 mm and both the intervals SPL and SPT of 2 mm. For example, successive * marks indicate the relationship between the frequency and the value obtained by multiplying the width (W1+W2) by the impedance in a power transmitting coil TC or a power receiving coil RC in which the width W1 is 7 mm, the width W2 is 3 mm, and the intervals SPL and SPT are both 3 mm. In this case, the legend in Fig. 3 indicates each structure in the format of "(▲ mark, etc.) (value of width W2 (inner circumference side))_(value of interval SPL)_(value of width W1 (outer circumference side))_(value of interval SPT)". Also, "12_4" indicated by successive "-" marks indicates a structure in which the winding wire is a solid wire with a width of 12 mm, and the interval between the winding wires is 4 mm.

[0042] On the other hand, Figure 4 shows the relationship between the sum of the above-mentioned spacing SPL and the above-mentioned spacing SPT (horizontal axis in Figure 4) and the value obtained by multiplying the width (W1 + W2) by the impedance (vertical axis in Figure 4) for each structure of the transmitting coil TC shown in Figure 3.

[0043] As described above, in the power transmitting coil TC or the power receiving coil RC of the embodiment, power transmission is performed at a transmission frequency of 85 kHz. In this case, when transmitting, for example, 10 kilowatts of power, it is assumed that a current of about 40 to 50 Arms (Ampere root mean square) flows through the power transmitting coil TC or the power receiving coil RC. Under this condition, if the impedance is 0.05 ohms when the transmission frequency is 85 kHz, the loss rate in the power transmitting coil TC or the power receiving coil RC is 0.8% to 1.25%. In addition, considering the transmission efficiency in the power transmitting coil TC or the power receiving coil RC, it is preferable that the loss is suppressed to the above value or less. Furthermore, from the viewpoint of reducing the weight of the power transmitting coil TC or the power receiving coil RC itself and effectively using copper material, it is preferable that the product of the impedance and the width (W1+W2) is 0.5 ohms-millimeters or less under the above-mentioned conditions regarding losses, etc. Based on the experimental results shown in Figures 3 and 4, the product of width (W1+W2) and impedance for a transmission frequency of 85 kHz is summarized for each structure of the transmitting coil TC as shown in Table 1 below. Note that in Table 1, structures where the product of impedance and width (W1+W2) of the transmitting coil TC etc. is 0.5 ohm-mm or more are indicated by hatching. [Table 1]

[0044] From the results shown in Figures 3 and 4 and Table 1 above, it can be seen that the following seven structures (i) to (vii) are suitable for the transmitting coil TC and receiving coil RC of the embodiment (i.e., when the power transmission frequency is 85 kHz, the product of impedance and width (W1 + W2) is less than 0.5 ohm-millimeters). (i) Width W2: 4 mm, Spacing SPL: 4 mm, Width W1: 4 mm, Spacing SPT: 4 mm (ii) Width W2: 6 mm, spacing SPL: 3 mm, width W1: 4 mm, spacing SPT: 3 mm (iii) Width W2: 3 mm, spacing SPL: 3 mm, width W1: 3 mm, spacing SPT: 7 mm (iv) Width W2: 8 mm, spacing SPL: 3 mm, width W1: 2 mm, spacing SPT: 3 mm (v) Width W2: 9 mm, Spacing SPL: 3 mm, Width W1: 1 mm, Spacing SPT: 3 mm (vi) Width W2: 9.5 mm, spacing SPL: 3 mm, width W1: 0.5 mm, spacing SPT: 3 mm (vii) Width W2: 8 mm, spacing SPL: 3 mm, width W1: 3 mm, spacing SPT: 2 mm

[0045] As described above, when the transmission frequency becomes large (high), the skin effect and the proximity effect are the causes of the increase in impedance. Focusing on the proximity effect, when the relationship between the sum of the spacing SPL and spacing SPT and the product of the width (W1+W2) and impedance is checked in FIG. 4, it is found that the product of the width (W1+W2) and impedance rises sharply when the sum of the spacing SPL and spacing SPT is less than about 4.5 millimeters. From this, it is found that at this transmission frequency (85 kilohertz), it is preferable to set the sum of the spacing SPL and spacing SPT to 4.5 millimeters or less. In the embodiment, the pitch PT is unified to 16 millimeters, but since it is estimated that the impedance varies mainly due to the proximity effect depending on the spacing SPL and spacing SPT, it is considered that the same effect can be obtained even if the pitch PT is changed.

[0046] On the other hand, when the sum of the intervals SPL and SPT is 4.5 mm, if the pitch PT is too narrow, the width W1 of the copper thin-film wire TL1 or the width W2 of the copper thin-film wire TL2 sufficient to pass the required current cannot be obtained, so in order to ensure the required widths W1 and W2 in more than half of the number of turns, the pitch PT needs to be 9 mm or more. Also, looking closely at the relationship between the intervals SPL and SPT in Table 1 and the like, it is desirable to set the interval SPT to be the same as the interval SPL or greater. In other words, from the viewpoint of the sum of the intervals SPL and SPT, as exemplified in FIG. 4, if the sum is greater than 4.5 mm, the structure of the transmitting coil TC and the receiving coil RC of the embodiment is appropriate.

[0047] As described above, in the power transmission using the power transmission system S of the embodiment including the power transmitting coil TC and the power receiving coil RC of the embodiment, when the winding circuit TL is formed by the copper thin film wire TL1 and the copper thin film wire TL2 parallel to the winding direction, the sum of the interval SPL in the direction perpendicular to the winding direction between the copper thin film wire TL1 and the copper thin film wire TL2 constituting one winding circuit TL and the interval SPT in the perpendicular direction between the adjacent winding circuits TL is longer than 4.5 mm corresponding to the power transmission frequency of 85 kHz. Therefore, it is possible to reduce the impedance of the power transmitting coil TC or the power receiving coil RC due to the so-called skin effect or proximity effect caused by forming the winding circuit TL by the parallel copper thin film wire TL1 and the copper thin film wire TL2 for weight and cost reduction, and it is possible to simultaneously achieve weight and cost reduction of the power transmission system S, improvement of the transmission efficiency, and prevention of an increase in the operating temperature.

[0048] Here, one winding TL is formed of a copper thin-film wire TL1 and a copper thin-film wire TL2, and in one winding TL, the width W2 of the copper thin-film wire TL2 on the inner circumference side of the power transmitting coil TC or the power receiving coil RC may be formed wider than the width W1 of the copper thin-film wire TL1 on the outer circumference side of the power transmitting coil TC or the power receiving coil RC (in the cases of "6_3_4_3", "7_3_3_3", "8_3_2_3", "9_3_1_3", "9.5_3_0.5_3", and "8_3_3_2" in FIG. 3). Even in this case, the impedance of the power transmitting coil TC or the power receiving coil RC can be reduced, so that it is possible to more easily achieve weight reduction and cost reduction, improved transmission efficiency, and prevention of an increase in operating temperature.

[0049] In addition, since the winding TL is composed of a winding wound from the outside to the inside and a winding wound from the inside to the outside, the impedance of the power transmitting coil TC or the power receiving coil RC can be further reduced.

[0050] Furthermore, when the power transmission frequency is 85 kilohertz, the sum of the above-mentioned intervals SPL and SPT is greater than 4.5 millimeters, so that the structure of the winding line TL can be optimized to further reduce the impedance of the transmitting coil TC or the receiving coil RC.

[0051] Furthermore, when the spacing SPT is 2 millimeters or more (the cases of "6_3_4_3", "7_3_3_3", "8_3_2_3", "9_3_1_3", "9.5_3_0.5_3" and "8_3_3_2" in Figure 3), the structure of the winding line TL can be optimized to further reduce the impedance of the transmitting coil TC or the receiving coil RC.

[0052] In the above-described embodiment, the winding line TL in the power transmitting coil TC or the power receiving coil RC has a single-layer structure, but in addition to this, two or more winding lines TL having similar structures may be laminated in two or more layers so that they are at the same position when viewed from one side with an insulating layer such as a film BF sandwiched therebetween, and each connection terminal O1 and connection terminal O2 may be connected to the power transmitting section TR (in the case of the power transmitting device T) or the power receiving section RV (in the case of the power receiving device R). In this case, since the winding line TL has a laminated structure, the impedance of the power transmitting coil TC or the power receiving coil RC can be further reduced by increasing the cross-sectional area of ​​the winding line TL constituting the power transmitting coil TC or the power receiving coil RC.

[0053] In the power transmitting coil TC or power receiving coil RC of the above-mentioned embodiment, the winding TL is made of the copper thin film wire TL1 and the copper thin film wire TL2, but one winding may be made of three or more copper thin film wires, and the spacing between the windings and the spacing between the windings may be optimized for the frequency of power transmission. In this case, since the winding is made of three or more copper thin film wires, the cross-sectional area of ​​the winding constituting the power transmitting coil or the power receiving coil can be further increased, thereby further reducing the impedance of the power transmitting coil or the power receiving coil. Modified form

[0054] Next, modified forms of the present invention will be described. The configuration of the power transmission system of each of the above-mentioned embodiments may be modified as shown in the following (A) to (D). Even if each of the modifications is added, the present invention can achieve the same effects as the above-mentioned power transmission system.

[0055] (A) First Variation First, as a first modified embodiment, in the power transmitting coil CL or the power receiving coil RC of the embodiment, the width W1 and the width W2 are the same around the entire circumference of the winding TL, but these widths may be increased from the outer circumference to the inner circumference of the power transmitting coil TC or the power receiving coil RC. In this case, the sum of the widths of the two thin copper wires constituting the winding also increases toward the inner circumference of the power transmitting coil TC or the power receiving coil RC.

[0056] (B) Second Variation Next, as a second modified embodiment, when the power transmitting coil TC or the power receiving coil RC is configured with two or more layers of windings TL in the above-mentioned embodiment, the radial positions of the power transmitting coil TC or the power receiving coil RC of each turn of the two or more layers of windings TL may be the same between the two or more layers of windings TL as in the embodiment, or may be different. In any of these cases, as long as the two or more layers of windings TL are stacked, the same effect as the above-mentioned power transmission system S can be achieved.

[0057] (C) Third Variation Next, as a third variant, in the above embodiment, the connection mode between the connection terminals O1 and O2 and the transmitting coil TC (or the receiving coil RC) may be the same as that of the embodiment, i.e., the two ends of the winding line TL are connected at their outermost portions to the connection terminals O1 and O2, respectively. Alternatively, the winding line may be wound in one direction (e.g., counterclockwise) from the outermost portion to the innermost portion, with the end at the outermost portion connected to, for example, the connection terminal O1, and the end of the winding line drawn from the innermost portion to the outermost portion by a laminated structure with an insulating layer sandwiched therebetween (see FIG. 2) or a jumper wire or the like may be connected to, for example, the connection terminal O2.

[0058] (D) Fourth Variation Finally, as a fourth variant, in the power transmission system S, the case where the transmitting coil TC and the receiving coil RC have the same structure has been described, but in addition to this, only one of the transmitting coil or the receiving coil that constitutes the power transmission system may have the same structure as the transmitting coil TC or the receiving coil RC of the embodiment. [Industrial Applicability]

[0059] 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]

[0060] S Power Transmission System R Power receiving device T Power transmission equipment RV power receiving unit RC receiving coil TR Power Transmission Unit TC Transmitting Coil TL Winding Line TL1, TL2 copper thin film wire O1, O2 connection terminals BF Film

Claims

1. In a coil for contactless power transmission, The windings constituting the coil are made up of a plurality of parallel windings each made of a thin film conductor and arranged in parallel to the winding direction of the winding, A coil characterized in that the sum of the spacing between the parallel windings constituting one of the windings in a direction perpendicular to the winding direction and the spacing between adjacent windings in the perpendicular direction is longer than at least a threshold length corresponding to the frequency of power transmission by the coil.

2. A coil for contactless power transmission, The windings constituting the coil are made up of a plurality of parallel windings each made of a thin film conductor and arranged in parallel to the winding direction of the winding, The sum of the spacing between the parallel windings constituting one of the windings in a direction perpendicular to the winding direction and the spacing between adjacent windings in the perpendicular direction is longer than at least a threshold length corresponding to a frequency of power transmission by the coil, 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 windings on the inner side of the coil is wider than the width of the parallel windings on the outer side of the coil.

3. The coil according to claim 1 or 2, The coil is characterized in that the winding circuit is composed of an outer-inner winding circuit constituted by the parallel winding circuit wound from the outer periphery side to the inner periphery side of the coil, and an inner-outer winding circuit constituted by the parallel winding circuit wound from the inner periphery side to the outer periphery side.

4. The coil according to any one of claims 1 to 3, A coil characterized in that the winding has a laminated structure.

5. The coil according to any one of claims 1 to 4, If the frequency is 85 kilohertz, 4. A coil comprising: a coil having a winding having a thickness of 100 nm and a thickness of 150 nm;

6. The coil according to claim 5, 11. A coil comprising: a coil winding having a perpendicular spacing of 2 millimeters or more between adjacent windings.

7. A power transmission system includes a power transmission device and a power receiving device separated from the power transmission device, and transmits power from the power transmission device to the power receiving device in a non-contact manner.

7. The coil according to claim 1 , wherein the coil is a power transmission coil arranged to face the power receiving device; an output means for outputting power to be transmitted to the power transmitting coil; A power transmitting device comprising:

8. A power transmission system includes a power transmission device and a power receiving device that is separated from the power transmission device, and the power receiving device transmits power from the power transmission device to the power receiving device in a non-contact manner.

7. The coil according to claim 1, wherein the power receiving coil is disposed opposite the power transmitting device; An input means connected to the receiving coil; A power receiving device comprising:

9. The power transmitting device according to claim 7 ; 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:

10. A power transmission device; 9. The power receiving device according to claim 8, wherein the power receiving coil is disposed opposite the power transmitting device and away from the power transmitting device, and the power receiving device receives power transmitted from the power transmitting device; A non-contact power transmission system comprising:

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