Wireless power feeding coil unit

Abstract

To suppress heat generation of a coil in a wireless power supply coil unit.SOLUTION: A wireless power feeding coil unit includes a planar coil in which a conductive wire is wound in a spiral shape, and the planar coil has an inner portion in which the number of turns is N (N is an integer of 2 or more), the number of inner turns is M (M is an integer of 1 or more and less than N), and the planar shape is a substantially circular spiral shape, and an outer portion in which the number of outer turns is (N-M), and the planar shape is a rounded polygonal spiral shape in which corners of a polygon are rounded in an arc shape.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a wireless power supply coil unit. [Background technology]

[0002] In recent years, coil units having coils for wireless power supply used in electric vehicles have been developed (see, for example, Patent Documents 1 to 3). Patent Document 1 discloses a spiral planar coil with a substantially square planar shape. Patent Documents 2 and 3 disclose planar coils in which a pair of conducting wires are wound. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-61517 [Patent Document 2] Patent No. 7038677 [Patent Document 3] Japanese Patent Publication No. 2022-22950 Summary of the Invention [Problem to be solved by the invention]

[0004] As described in Patent Documents 1 to 3, wireless power transfer uses a coil in which a conducting wire is wound in a spiral shape. However, because the conducting wire has electrical resistance, some of the applied electrical energy is lost and converted into heat. A rise in the coil temperature leads to an increase in the coil's electrical resistance, which may result in a decrease in power transfer efficiency. Therefore, there is a need for a technology to suppress heat generation in the coil in a wireless power transfer coil unit. [Means for solving the problem]

[0005] The present disclosure can be realized in the following forms. (1) According to one embodiment of the present disclosure, there is provided a wireless power supply coil unit including a planar coil in which a conducting wire is wound in a spiral shape, the planar coil having N turns (N is an integer equal to or greater than 2), including an inner portion having an inner M turns (M is an integer equal to or greater than 1 and less than N) and a substantially circular spiral shape in plan view, and an outer portion having an outer (NM) turns and a rounded polygonal spiral shape in plan view with rounded corners.

[0006] The temperature of the inside of the spiral of a planar coil tends to rise. With this type of wireless power transfer coil unit, the planar shape of the inner part of the planar coil is approximately circular, and the direction of current flow changes gradually, which prevents current from concentrating in one area inside the planar coil and reduces heat generation.

[0007] (2) In the wireless power supply coil unit of the above embodiment, the thickness of the conductor in the inner portion may be thicker than the thickness of the conductor in the outer portion. In a spiral planar coil, current tends to be biased toward both sides of the conductor in the inner portion. Therefore, by increasing the thickness of the conductor in the inner portion, the cross-sectional area increases and the current density can be reduced. As a result, current resistance can be reduced, energy loss can be reduced, and temperature rise in the planar coil can be further suppressed.

[0008] (3) In the wireless power supply coil unit of the above aspect, the number of turns in the outer portion may be equal to or greater than the number of turns in the inner portion. This allows the area occupied by the coil to be increased, thereby suppressing a decrease in inductance.

[0009] (4) In the wireless power supply coil unit of the above aspect, when the minimum value of the distance between the conductors of the innermost turn of the outer portion and the outermost turn of the inner portion is x, the maximum value of the distance between the conductors may be less than 35x. In this way, it is possible to suppress gaps between adjacent conductors of the conductors constituting the planar coil, and to suppress an increase in electrical resistance and a decrease in inductance.

[0010] (5) In the wireless power supply coil unit of the above embodiment, the cross-sectional shape of the conductor may be rectangular, and the aspect ratio of the width to the thickness of the cross-section of the conductor may be 1.4<α / β<5.4, where α is the aspect ratio of the conductor in the outer portion and β is the aspect ratio of the conductor in the inner portion. In this way, the conductor in the outer portion is flatter than the conductor in the inner portion. By increasing the height of the conductor in the inner portion, where the current density difference is relatively large, and reducing the current density difference, heat generation in the coil can be further suppressed.

[0011] (6) The wireless power supply coil unit of the above configuration may further include a magnetic portion made of a magnetic composite material having a resin material and soft magnetic particles contained in the resin material, the magnetic portion covering the planar coil, and the magnetic composite material filling the spaces between adjacent conductors of the planar coil. In this way, the proximity effect between adjacent conductors is suppressed, and the amount of heat generated can be reduced.

[0012] (7) The coil unit for wireless power transfer of the above configuration may further include a magnetic member laminated on the planar coil covering the magnetic portion and made of a magnetic material having a higher complex relative permeability than the magnetic composite material, and a shielding member laminated on the magnetic member on the opposite side of the planar coil from the planar coil and made of a conductive metal. In this way, it is possible to provide a coil unit for wireless power transfer that suppresses leakage flux and achieves highly efficient wireless power transfer.

[0013] (8) In the wireless power supply coil unit of the above embodiment, when the real term of the complex relative magnetic permeability of the magnetic part at a frequency of 85 kHz is A and the real term of the complex relative magnetic permeability of the magnetic member at a frequency of 85 kHz is B,

[0014] ​(9) In the wireless power supply coil unit of the above aspect, the conductor wires of the planar coil may be a pair of first and second conductor wires arranged in parallel, which can further reduce heat generation.

[0015] (10) In the wireless power supply coil unit of the above aspect, the cross-sectional shape of the conductor wire may be rectangular, and the planar coil may have a first imaginary plane formed imaginarily by adjacent spirally wound conductor wires and a second imaginary plane behind the first imaginary plane, the first imaginary plane being planar, and the second imaginary plane having a portion corresponding to the inner portion protruding from a portion corresponding to the outer portion. This can facilitate magnetic coupling between the two planar coils when two wireless power supply coil units are arranged opposite each other. It can also suppress a decrease in inductance and an increase in electrical resistance.

[0016] The present disclosure can be realized in various forms other than those described above, such as a method for manufacturing a wireless power supply coil, a wireless power supply method using a wireless power supply coil, a vehicle using a wireless power supply coil, or a moving body using a wireless power supply coil. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a diagram conceptually illustrating a planar configuration of an example of a wireless power supply coil unit. FIG. [Figure 2] 1 is a diagram conceptually illustrating a cross-sectional configuration of a wireless power supply coil unit. FIG. [Figure 3] FIG. 1 is a diagram conceptually illustrating an example of a conventional planar coil. [Figure 4] FIG. 2 is a diagram conceptually illustrating the configuration of an example of a planar coil according to the first embodiment. [Figure 5] FIG. 2 is an enlarged view of a portion of the planar coil. [Figure 6] 10A and 10B are diagrams illustrating an example of the relationship between the minimum and maximum values ​​of the distance between conductors. [Figure 7] FIG. 10 is a diagram schematically illustrating the configuration of another example of a planar coil. [Figure 8] FIG. 2 is an enlarged view of a portion of the planar coil. [Figure 9] 10A and 10B are diagrams illustrating an example of the relationship between the minimum and maximum values ​​of the distance between conductors. [Figure 10] 10 is a diagram conceptually showing the positional relationship in the Z-axis direction between the inner conductor and the outer conductor. FIG. [Figure 11] FIG. 1 is a diagram showing a schematic configuration of a magnetic composite material. [Figure 12] 3 is an enlarged conceptual view showing a cross-sectional configuration of a wireless power supply coil unit. FIG. [Figure 13] 10A and 10B are diagrams conceptually illustrating the configuration of a wireless power supply coil unit according to a second embodiment. [Figure 14] FIG. 10 is a diagram conceptually showing the configuration of a planar coil according to a third embodiment. [Figure 15] FIG. 10 is a diagram schematically illustrating a configuration of a wireless power supply system according to a fourth embodiment. [Figure 16] FIG. 2 is a diagram schematically illustrating the arrangement of two wireless power supply coil units. [Figure 17] FIG. 10 is a diagram showing design items and evaluation results of planar coil samples S1 to S9. [Figure 18] FIG. 10 is a diagram showing other design items of samples S1 to S9. [Figure 19] FIG. 10 is a diagram showing the evaluation results of samples S11 to S16 of the coil unit for wireless power supply. DETAILED DESCRIPTION OF THE INVENTION

[0018] First Embodiment A1. Magnetic coil schematic: FIG. 1 is a diagram conceptually illustrating a planar configuration of an example of a wireless power supply coil unit 41 according to a first embodiment of the present disclosure. In the drawing, mutually orthogonal X, Y, and Z axes are shown to identify directions. For convenience, the positive Z-axis direction is referred to as the upward direction, and the negative Z-axis direction is referred to as the downward direction. As illustrated, the wireless power supply coil unit 41 includes a planar coil 10 and a magnetic portion 20 made of a magnetic composite material 22 and covering the planar coil 10. The planar coil 10 includes a conductor 10L wound in a spiral shape. Connection portions 13 and 14 are provided at both ends of the spiral of the planar coil 10 for electrically connecting the planar coil 10 to an external device. The planar coil 10 is made of a metal such as copper or aluminum, and the magnetic composite material 22 includes a resin material 24 and soft magnetic particles 26 (described in detail below).

[0019] FIG. 2 is a conceptual diagram showing the cross-sectional configuration of wireless power supply coil unit 41. FIG. 2 shows a cross section taken along line AA in FIG. 1. Planar coil 10 has a first imaginary plane SC1 formed imaginarily by adjacent spirally wound conductor wires 10L, and a second imaginary plane SC2 on the back side of first imaginary plane SC1. Using a planar coil (also called a plate-shaped coil) can contribute to weight reduction, thickness reduction, high efficiency power transmission, and reduction of AC resistance of the coil. Magnetic part 20 covers planar coil 10 and has a first surface S1 covering first imaginary plane SC1 of planar coil 10 and a second surface S2 covering second imaginary plane SC2 of planar coil 10.

[0020] A2. Conventional planar coil: Before describing the planar coil 10 of the first embodiment in detail, the configuration of a conventional planar coil 10P and the results of a simulation analysis of the current density when an AC current is passed through the conventional planar coil will be described. The simulation is an electromagnetic field analysis using CAE (Computer Aided Engineering).

[0021] FIG. 3 is a conceptual diagram illustrating an example of a conventional planar coil 10P. FIG. 3 illustrates half of the planar coil 10P. The planar coil 10P is formed by spirally winding a conductor wire 10PL, and its planar shape is a rounded square spiral. In FIG. 3, the current density at the area surrounded by the dashed line is displayed on the cross section of the conductor wire 10PL. The current density is classified into five types: highest, high, slightly high, slightly low, and low, and is shown in FIG. 3 with different hatching. The hatching according to the current density is as follows: Highest: Right-sloping diagonal hatching High: Double diagonal hatching with upward slope Slightly high: Right-sloping diagonal hatching Slightly low: crosshatching Low: Dot hatching

[0022] As shown in the figure, at the bent portion of the conductor 10PL and inside the planar coil 10P, the current is biased to both sides of the conductor 10PL, and the current density is particularly highest on the inside. This portion has the highest current density in the planar coil 10P (FIG. 3(A)).

[0023] In the conductor 10PL where the conductor 10PL is linear and located near the center of the adjacent conductors 10PL, current flows relatively throughout the entire conductor 10PL (FIG. 3(B)). In the conductor 10PL where the conductor 10PL is linear and located on the inner side of the adjacent conductors 10PL, current is biased to both side surfaces of the conductor 10PL, with the current density being particularly high on the inner side (FIG. 3(C)). In the conductor 10PL where the conductor 10PL is linear and located on the outer side of the adjacent conductors 10PL, current is biased to both side surfaces of the conductor 10PL, with the current density being particularly high on the outer side (FIG. 3(D)).

[0024] When a current flows through a planar coil, a large amount of heat is generated, which leads to an increase in the electrical resistance of the planar coil, resulting in a decrease in power supply efficiency. Furthermore, for example, when a planar coil for wireless power supply is placed under the floor of a vehicle, if the planar coil generates heat, a heat dissipation mechanism must be installed, and there is a risk of deterioration or malfunction of surrounding devices due to the heat. Therefore, there is a need to suppress the heat generated by the planar coil.

[0025] The inventors of the present application conducted an actual test simulating a wireless power supply coil unit having the above-described planar coil 10P, placing it on a vehicle and on the ground, and investigated the temperature change using a thermal camera. When current was applied to the ground-side coil and electromotive force was generated in the vehicle-side coil, it was confirmed that the coil was heated to such an extent that its shape was clearly visible. In particular, it was confirmed that the temperature rise was large inside the coil.

[0026] In order to reduce energy loss in the planar coil, the inventors of the present application conducted a simulation to investigate the behavior of the current flowing through the planar coil, and obtained the results shown in Figure 3. Therefore, they investigated a configuration with the goal of passing a current with a uniform current density through the conductors that make up the planar coil.

[0027] A3. Planar coil configuration: Fig. 4 is a diagram conceptually illustrating an example of the configuration of the planar coil 10 of this embodiment. In Fig. 4, the upper part illustrates the planar configuration of the planar coil 10, and the lower part illustrates the cross-sectional configuration. As described above, the planar coil 10 is formed by winding the conducting wire 10L in a spiral shape.

[0028] The planar coil 10 has an inner portion 11 with N turns (N is an integer equal to or greater than 2) and an inner M turns (M is an integer equal to or greater than 1 and less than N) that have a roughly circular spiral shape in plan view, and an outer portion 12 with an outer (NM) turns that have a rounded polygonal spiral shape in plan view with rounded corners. The roughly circular shape includes a regular circle, an ellipse, an oval, and an oval. The polygonal shape includes various polygons such as a triangle, a quadrangle (square, rectangle, parallelogram, rhombus), a pentagon, and a hexagon.

[0029] In the example shown in FIG. 4, N=5 and M=2, the number of turns in the inner portion 11 is 2, and the number of turns in the outer portion 12 is 3. That is, the number of turns in the outer portion 12 is equal to or greater than the number of turns in the inner portion 11. The planar shape of the inner portion 11 is a perfect circular spiral, and the planar shape of the outer portion 12 is a perfect circular spiral with rounded corners. The perfect circular spiral is a spiral shape known as "Archimedes' spiral." The number of turns is not limited to the example shown in FIG. 4, as long as it is 2 or greater. The number of turns in the inner portion 11 and the outer portion 12 are not limited to the example shown in FIG. 4, and the number of turns in the inner portion 11 may be equal to or greater than the number of turns in the outer portion 12.

[0030] As described above, the temperature of the inside of the spiral of the conventional planar coil 10P was prone to rise. This is thought to be because the planar shape of the inside of the planar coil 10P was also a spiral with rounded square corners, and the current flow direction changed suddenly where the conductor 10PL bent, making it easier for the current to be biased in the conductor 10PL and for the current to pass through the inside. In contrast, the planar shape of the inner portion 11 of the planar coil 10 of the present embodiment is approximately circular, and the current flow direction changes gradually. This prevents the current from concentrating in one area in the inner portion of the planar coil, thereby suppressing heat generation.

[0031] In the planar coil 10 of this embodiment, the outer portion 12 has a spiral shape with rounded square planar shapes. When the location of the wireless power supply coil unit 41 is square, by making the outer portion 12 a rounded square, the area occupied by the coil can be increased and the inductance can be improved compared to a spiral shape with a circular planar shape. In other words, by making the planar shapes of the inner portion 11 and the outer portion 12 different, the planar shapes of the planar coil 10 of this embodiment can suppress heat generation in the planar coil and suppress a decrease in inductance.

[0032] The conductor 10L of this embodiment is formed by connecting an inner conductor 11L forming the inner portion 11 and an outer conductor 12L forming the outer portion 12. As shown in FIG. 4, the thickness t1 of the inner conductor 11L of the inner portion 11 is greater than the thickness t2 of the outer conductor 12L of the outer portion 12. In a spiral planar coil, current tends to flow unevenly toward both sides of the conductor in the inner portion. In the example shown in FIG. 4, the inner conductor 11L of the inner portion 11 is thicker and has a larger cross-sectional area than the outer conductor 12L of the outer portion 12. This reduces the current density compared to when the inner portion 11 has the same thickness as the outer conductor 12L. As a result, the current resistance in the inner portion 11 is reduced, reducing energy loss and further suppressing temperature rise in the planar coil. Furthermore, reducing the thickness of the outer conductor 12L of the outer portion 12 reduces the skin effect and suppresses heat generation in the planar coil. In other embodiments, the thickness t1 of the inner conductor 11L of the inner portion 11 may be equal to or smaller than the thickness t2 of the outer conductor 12L of the outer portion 12.

[0033] The cross-sectional shape of the conductor 10L is rectangular. The outer conductor 12L of the outer portion 12 preferably has a width w2 of 8 mm to 16 mm and a thickness t2 of 0.6 mm to 0.8 mm. The inner conductor 11L of the inner portion 11 preferably has a width w1 of 8 mm to 16 mm and a thickness t1 of 1.2 mm to 1.6 mm. The aspect ratio of the width to the cross-sectional thickness of the conductor 10L is defined as the aspect ratio of the outer conductor 12L of the outer portion 12, α, and β, respectively. The relationship α / β is preferably 1.4<α / β<5.4. In this manner, the outer conductor 12L of the outer portion 12 is flatter than the inner conductor 11L of the inner portion 11. By increasing the height of the inner conductor 11L in the inner portion 11 where the current density difference is relatively large, and thereby reducing the current density difference, heat generation in the planar coil 10 can be further suppressed. In other embodiments, α / β may be 1.4 or 5.4 or α / β. Furthermore, in other embodiments, the cross-sectional shape of the conductor 10L does not have to be rectangular and may be, for example, circular.

[0034] FIG. 5 is an enlarged view of a portion of the planar coil 10. FIG. 5 illustrates the positional relationship between the innermost turn 12I of the outer portion 12 and the outermost turn 11O of the inner portion 11 in part A of FIG. 4. When the minimum inter-wire distance between the innermost turn 12I of the outer portion 12 and the outermost turn 11O of the inner portion 11 is defined as x, the maximum inter-wire distance is defined as kx. The inter-wire distance is the distance between the point where a line passing through the center of the inner portion 11 intersects with the outside of the turn 11O and the point where it intersects with the inside of the turn 12I. The maximum inter-wire distance is the distance between the point where a line passing through the center of the inner portion 11 and a corner of the square of the outer portion 12 (a virtual corner with the corners assumed to be unrounded) intersects with the outside of the turn 11O and the point where it intersects with the inside of the turn 12I. k is preferably less than 35.

[0035] In planar coil 10, inner portion 11 has a planar shape of a perfect circle spiral, and outer portion 12 has a planar shape of a rounded square spiral, so that the distance between the rounded corners of turn 12I of outer portion 12 and turn 11O of inner portion 11 is large. If this distance is large, the number of gaps where no conductor wire exists increases, reducing the self-inductance of wireless power supply coil unit 41. In contrast, if k is set to less than 35, the magnetic portion 20 is reduced, and the reduction in self-inductance can be suppressed.

[0036] Fig. 6 is a diagram showing an example of the relationship between the minimum and maximum inter-conductor distances. In the sample shown in Fig. 5, the planar shape of the inner portion 11 is a spiral with a perfect circle, and the planar shape of the outer portion 12 is a spiral with rounded squares. In all of Samples 1 to 4, the above k was less than 35.

[0037] Fig. 7 is a diagram schematically illustrating the configuration of another example of a planar coil. Planar coil 10A differs from planar coil 10A shown in Fig. 4 in its planar shape. In planar coil 10A, inner portion 11 has an elliptical spiral shape in plan view, and outer portion 12 has a rounded rectangular spiral shape in plan view.

[0038] FIG. 8 is an enlarged view of a portion of the planar coil 10A. FIG. 8 illustrates the positional relationship between the innermost turn 12I of the outer portion 12 and the outermost turn 11O of the inner portion 11 in part B of FIG. 7. When the minimum inter-wire distance between the innermost turn 12I of the outer portion 12 and the outermost turn 11O of the inner portion 11 is defined as x, the maximum inter-wire distance is defined as kx. The inter-wire distance is the distance between the point where a line passing through the center of the inner portion 11 intersects with the outside of the turn 11O and the point where it intersects with the inside of the turn 12I. The maximum inter-wire distance is the distance between the point where a line passing through the center of the inner portion 11 and a corner (a virtual corner assuming the corner is not rounded) of the rectangle of the outer portion 12 intersects with the outside of the turn 11O and the point where it intersects with the inside of the turn 12I. k is preferably less than 35. This configuration can suppress a decrease in self-inductance, as in the example shown in FIG. 4.

[0039] Fig. 9 is a diagram showing an example of the relationship between the minimum and maximum inter-conductor distances. In the sample shown in Fig. 9, the planar shape of the inner portion 11 is an elliptical spiral, and the planar shape of the outer portion 12 is a rounded rectangular spiral. In all of Samples 5 to 8, the value of k was less than 35. In other embodiments, k may be 35 or greater.

[0040] Fig. 10 is a diagram conceptually showing the positional relationship in the Z-axis direction between the inner conductor 11L and the outer conductor 12L. Fig. 10 shows an enlarged portion of the wireless power supply coil unit 41. Fig. 10(A) shows the wireless power supply coil unit 41 of this embodiment, and Fig. 10(B) shows a wireless power supply coil unit 41P of a comparative example. In Fig. 10, the flow of magnetic field lines is shown by arrows.

[0041] The cross-sectional shape of the conductor 10L of this embodiment is rectangular, and the planar coil 10 has a first imaginary plane SC1 imaginarily formed by adjacent spirally wound conductors 10L, and a second imaginary plane SC2 behind the first imaginary plane SC1, where the first imaginary plane SC1 is planar, and the second imaginary plane SC2 has a portion corresponding to the inner portion 11 protruding from a portion corresponding to the outer portion 12 (FIG. 10(A)). The cross-sectional shape of the conductor 10L of the comparative example is also rectangular, but both the first imaginary plane SC1 and the second imaginary plane SC2 are uneven (FIG. 10(B)).

[0042] In the wireless power supply coil unit 41 of this embodiment, the first imaginary plane SC1 of the planar coil 10 is planar, suppressing disturbance of magnetic field lines, thereby suppressing a decrease in inductance and an increase in electrical resistance. Furthermore, when two wireless power supply coil units 41 are arranged so that the first imaginary planes SC1 face each other, magnetic coupling between the planar coils 10 is easily achieved. Therefore, it is preferable to arrange the inner conductor 11L and the outer conductor 12L as shown in FIG. 10(A). On the other hand, in the wireless power supply coil unit 41P of the comparative example, the first imaginary plane SC1 and the second imaginary plane SC2 are uneven, which may cause the magnetic field lines flowing through the magnetic portion 20 to detour, resulting in a decrease in inductance and an increase in electrical resistance. In other embodiments, the inner conductor 11L and the outer conductor 12L may be arranged as in the wireless power supply coil unit 41P.

[0043] The planar coil 10 can be fabricated by cutting a metal plate into a coil shape. When the thicknesses of the inner portion 11 and the outer portion 12 of the planar coil 10 are different, the inner conductor 11L and the outer conductor 12L are cut out of metal plates of different thicknesses into coil shapes of the appropriate shape and then joined by welding. Joining may also be achieved by known methods other than welding, such as solid-state welding using ultrasound. Since the planar coil 10 will be used as a coil, a joining method that provides low electrical resistance at the joint is preferred, and a method that directly joins metal is preferred over joining using a resin adhesive.

[0044] A4.Magnetic part configuration: As shown in FIG. 2, the magnetic portion 20 is made of a magnetic composite material 22 and covers the planar coil 10. 11 is a diagram showing a schematic configuration of a magnetic composite material 22. The magnetic composite material 22 includes a resin material 24 and soft magnetic particles 26 contained in the resin material 24.

[0045] The resin material 24 preferably has vibration absorption properties by itself, and examples thereof include elastomers such as natural rubber, butyl rubber, nitrile rubber, silicone rubber, polyurethane, and fluorine-based rubber. Among these, silicone rubber is particularly preferred due to its ease of mixing with soft magnetic particles 26 (filler) and its high heat resistance, weather resistance, and adhesive properties. When silicone rubber is used as the resin material 24, the molecular weight between crosslinking points of the silicone rubber is preferably 20,000 or more in order to optimize the elongation and rubber hardness of the magnetic composite material 22. Using an elastomer as the resin material 24 can improve flexibility compared to using polycarbonate, polypropylene, epoxy resin, or phenolic resin. Furthermore, it can improve heat resistance and weather resistance compared to urethane. Resin materials other than elastomers may also be used as the resin material 24. For example, using polycarbonate or polypropylene can result in a magnetic composite material 22 with excellent shape stability, using urethane can result in a magnetic composite material 22 with excellent vibration absorption ability, and using epoxy resin or phenolic resin can result in a magnetic composite material 22 with excellent adhesiveness.

[0046] The soft magnetic particles 26 are preferably practical as a magnetic material in a frequency range of, for example, 50 to 100 kHz. This allows the magnetic composite material 22 to be suitably used in wireless power supply devices, as described below. The frequency range of 50 to 100 kHz is a frequency range in which high power transmission efficiency can be achieved in wireless power supply. From the perspective of applying the magnetic composite material 22 to a wireless power supply device, it is desirable that the soft magnetic particles 26 function well as a magnetic material, particularly in the 85 kHz band, which is the resonance frequency of magnetic field coupling type wireless power supply. The soft magnetic particles 26 can include, for example, at least one of a soft magnetic metal and a soft magnetic ferrite. The inclusion of such soft magnetic particles 26 allows the magnetic composite material 22 to function as a good magnetic material.

[0047] Examples of soft magnetic metals constituting the soft magnetic particles 26 include Fe-Si alloys, Fe-Si-Cr alloys, sendust (Fe-Si-Al alloys), and permalloy (Fe-Ni alloys). Examples of ferrites constituting the soft magnetic particles 26 include Ni-Zn ferrite (nickel zinc ferrite) and Mn-Zn ferrite (manganese zinc ferrite). Among these soft magnetic materials, Ni-Zn ferrite and Mn-Zn ferrite are particularly preferred because they have a large real part μ' of the complex relative permeability in the frequency range of 50 kHz to 100 kHz. The larger the real part μ' of the complex relative permeability, the greater the degree to which magnetic flux can be confined.

[0048] Furthermore, the shape of the powder particles that are the soft magnetic particles 26 is not particularly limited, but is preferably close to spherical in terms of enhancing the vibration absorption properties of the entire magnetic composite material 22. Specifically, the aspect ratio (major axis / minor axis) of the powder particles of the soft magnetic particles 26 is preferably, for example, 5 or less, and more preferably 3 or less. Here, the "major axis" refers to the maximum value of the distance between two parallel lines when an image of a powder particle of the soft magnetic particles 26 projected in the vertical direction is sandwiched between the two lines, and the "minor axis" refers to the minimum value of the distance between the two lines.

[0049] Although there are no particular limitations on the average particle size of the soft magnetic particles 26, it is preferably 50 μm or less. This makes it possible to suppress eddy currents caused by changes in the magnetic field and the resulting heat generation. Furthermore, it is preferable that the average particle size of the soft magnetic particles 26 be 2 μm or more. If the average particle size is smaller than this, the surface area of ​​the soft magnetic particles increases relative to the volume when blended with the resin, causing the viscosity to increase and making it impossible to blend.

[0050] Fig. 12 is a conceptual enlarged view of the cross-sectional configuration of the wireless power supply coil unit 41. Fig. 12 shows an enlarged view of the X portion in Fig. 2. As shown in the figure, in the wireless power supply coil unit 41, a magnetic composite material 22 is filled between adjacent conductor wires 10L. If the magnetic composite material 22 is not filled between adjacent conductor wires 10L and air is trapped between them, the state of the magnetic field may change and the magnetic field may leak. However, in this configuration, the magnetic field leakage can be suppressed, and a decrease in power transmission efficiency can be suppressed.

[0051] A5. Manufacturing method for wireless power supply coil unit: The wireless power supply coil unit 41 of this embodiment can be manufactured by, for example, the following method. (Step P2) A soft magnetic powder made of metal and a thermosetting resin are mixed to prepare a paste-like magnetic composite material. (Step P4) A resin material that does not contain magnetic powder is prepared. (Step P6) A resin material that does not contain magnetic powder is thinly spread. (Step P8) A magnetic composite material is spread on top of the spread resin material. (Step P10) The planar coil 10 is placed on the magnetic composite material. (Step P12) A magnetic composite material is applied between adjacent conductive wires 10L of the planar coil 10, filling the gaps between the adjacent conductive wires 10L so that no air bubbles remain. (Step P14) A magnetic composite material is further applied to the planar coil 10 to a predetermined thickness. (Step P16) A resin material that does not contain magnetic powder is further thinly applied on the above. (Step P18) The product produced in step P16 is heated and cured to complete the wireless power supply coil unit 41 covered with the magnetic composite material.

[0052] According to this method for manufacturing a magnetic coil, the wireless power supply coil unit 41 of this embodiment can be easily manufactured. However, the wireless power supply coil unit 41 may also be manufactured by other manufacturing methods. For example, a magnetic composite material may be placed in a predetermined container, the planar coil 10 may be immersed in the magnetic composite material, and the material may be hardened by heating.

[0053] As described above, in the wireless power supply coil unit 41 of this embodiment, the planar shape of the inner portion 11 of the planar coil 10 is approximately circular, and the current flow direction changes gradually. This prevents current from concentrating in one area in the inner portion of the planar coil, thereby suppressing heat generation. In the planar coil 10, the outer portion 12 has a spiral shape with rounded polygonal corners in planar shape. When the wireless power supply coil unit 41 is arranged in a polygonal shape, making the outer portion 12 spiral with rounded polygonal corners increases the area occupied by the coil and improves inductance compared to a spiral shape with a circular planar shape. In other words, by making the planar shapes of the inner portion 11 and the outer portion 12 different, the planar shape of the planar coil 10 of this embodiment can suppress heat generation in the planar coil and suppress a decrease in inductance.

[0054] Second Embodiment 13 is a conceptual diagram showing the configuration of a wireless power supply coil unit 41B of the second embodiment. In addition to the configuration of the wireless power supply coil unit 41 of the first embodiment, the wireless power supply coil unit 41B of the second embodiment includes a magnetic member 32 and a shielding member 34. In the following description, the same components as those of the planar coil 10 are denoted by the same reference numerals, and the preceding description will be referred to.

[0055] The magnetic member 32 is made of a magnetic material having a higher complex relative permeability than the magnetic composite material 22, and is laminated on the planar coil 10. The magnetic member 32 may be, for example, a ferrite tile.

[0056] The shielding member 34 is made of a conductive metal and is laminated on the opposite side of the magnetic member 32 from the planar coil 10. For example, aluminum can be used as the metal constituting the shielding member 34. The magnetic member 32 and the planar coil 10, and the magnetic member 32 and the shielding member 34, do not need to be in close contact with each other, and there may be a gap between at least one of the magnetic member 32 and the planar coil 10 and the magnetic member 32 and the shielding member 34. The gap may be filled with, for example, a resin plate, a resin pillar, or the like.

[0057] When the real term of the complex relative permeability of the magnetic part 20 at a frequency of 85 kHz is A and the real term of the complex relative permeability of the magnetic member 32 at a frequency of 85 kHz is B, the value of B / A is not particularly limited, but is preferably 75

[0058] According to the wireless power supply coil unit 41B of this embodiment, it is possible to provide a coil unit for wireless power supply that suppresses leakage magnetic flux and achieves highly efficient wireless power supply.

[0059] Third Embodiment ​FIG. 14 is a conceptual diagram illustrating the configuration of a planar coil 10C according to a third embodiment. The conductor wires 10LC of the planar coil 10C are a pair of first conductor wire 15 and second conductor wire 16 arranged in parallel. This configuration further reduces heat generation. In FIG. 14, the first conductor wire 15 and the second conductor wire 16 are distinguishably hatched. The first conductor wire 15 is hatched with an upward slope to the right, and the second conductor wire 16 is hatched with a downward slope to the right.

[0060] <Fourth embodiment> Fig. 15 is a diagram schematically illustrating the configuration of a wireless power feeding system 70 according to the fourth embodiment. The wireless power feeding system 70 shown in Fig. 15 is a system that feeds power wirelessly by electromagnetic induction, and includes a wireless power feeding device 40 on the power receiving side and a wireless power feeding device 50 on the power transmitting side.

[0061] The wireless power supply device 40 includes a wireless power supply coil unit 41B of the second embodiment, a circuit board 44, and a load 46. The wireless power supply coil unit 41B includes a planar coil 10 as a secondary coil on the power receiving side, a magnetic part 20 that covers the planar coil 10, a magnetic member 32, and a shielding member 34.

[0062] In the example shown in FIG. 15 , the planar coil 10 is covered by the magnetic portion 20 and is disposed on the back side of the magnetic member 32, and the portion hidden by the magnetic member 32 is indicated by a dashed line. The circuit board 44 is electrically connected to the planar coil 10 and is provided to supply power generated in the planar coil 10 to a load 46. FIG. 15 shows, as an example, a state in which the wireless power transfer device 40 is mounted on a vehicle (electric vehicle) 60. The vehicle 60 includes the wireless power transfer device 40 and a power storage device that stores power for driving the vehicle 60. The power storage device corresponds to the load 46 in FIG. 15 , and power generated in the planar coil 10 is supplied to the power storage device via the circuit board 44. The circuit board 44 includes a converter that converts the voltage when power is supplied from the planar coil 10 to the power storage device into a voltage suitable for charging the power storage device. In the vehicle 60, the load 46 is a power storage device. However, the load 46 may further include a drive motor of the vehicle, so that the wireless power supply device 40 can directly supply power to the drive motor.

[0063] The wireless power supply device 40 of this embodiment includes the planar coil 10 of the first embodiment, and can suppress heat generation from the planar coil 10 during wireless power supply, thereby suppressing energy loss. Also, adverse effects on devices arranged around the wireless power supply coil unit 41 can be suppressed.

[0064] The wireless power supply device 50 includes a wireless power supply coil unit 51, a circuit board 54, and a power supply device 56. The wireless power supply coil unit 51 includes a planar coil 52 as a primary coil on the power transmission side, a magnetic section 20 covering the planar coil 52, a magnetic member 32, and a shielding member 34. The magnetic member 32 and the shielding member 34 are disposed on the back side of the magnetic section 20 (the lower side of the drawing). In the example shown in FIG. 15, the planar coil 52 is hidden by the magnetic section 20 and is therefore represented by a dashed line. In the wireless power supply device 50, the circuit board 54 is electrically connected to the planar coil 52 and is provided to supply AC power to the planar coil 52. For example, when the power receiving side wireless power supply device 40 is mounted on a vehicle 60 as shown in FIG. 15, the wireless power supply device 50 may be installed at a specific location (e.g., a road) provided for power supply so as to be able to supply power to the vehicle 60 parked at the specific location. The circuit board 54 includes a converter and an inverter that converts the voltage used when power is supplied from the power supply device 56 to the planar coil 52 into a voltage suitable for power supply operation using the planar coil 52. The configuration of the wireless power supply coil unit 51 is similar to that of the wireless power supply coil unit 41B.

[0065] Fig. 16 is a diagram schematically illustrating the arrangement of the wireless power supply coil unit 41B and the wireless power supply coil unit 51. Fig. 16 illustrates a cross section perpendicular to the plane direction of the wireless power supply coil unit 41B and the wireless power supply coil unit 51. As illustrated, the wireless power supply coil unit 41B and the wireless power supply coil unit 51 are arranged facing each other, and a magnetic member 32 and a shielding member 34 are layered in this order on the outside of the wireless power supply coil unit 41B and the wireless power supply coil unit 51, respectively.

[0066] As shown in the figure, in wireless power supply coil unit 41B, inner conductor 11L protrudes toward the side that does not face wireless power supply coil unit 51. In wireless power supply coil unit 51, inner conductor 11L protrudes toward the side that does not face wireless power supply coil unit 41B. This makes it easier to create magnetic coupling between planar coil 10 of wireless power supply coil unit 41B and planar coil 52 of wireless power supply coil unit 51.

[0067] The wireless power supply coil unit 41 of the above-described embodiment may be used for purposes other than wireless power supply devices for electric vehicles, such as wireless power supply devices provided in aircraft, satellites, smartphones, tablet terminals, small home appliances, etc. [Example]

[0068] The present disclosure will be explained more specifically with reference to examples. FIG. 17 shows the design items and evaluation results for planar coil samples S1 to S9, and FIG. 18 shows other design items for samples S1 to S9. The evaluation was performed using electromagnetic field simulation software Eddyjω and VOLT. The analysis determined the electrical resistance of the planar coil during operation. The loss in the coil can be calculated using the following formula from the coil's electrical resistance and the current value flowing through it. Loss P=I 2 R Since the loss is heat generated in the coil, if we assume that the current value is constant, the amount of heat generated by the coil can be compared by comparing the electrical resistance of the coil.

[0069] As mentioned above, the "conductor spacing ratio k" in Figure 17 is the maximum value of the conductor spacing relative to the minimum value of the conductor spacing between the innermost turn in the outer portion and the outermost turn in the inner portion. The "aspect ratio ratio α / β" is the ratio α / β, where the aspect ratio is the width (mm) to the thickness (mm) of the conductor cross section, α is the aspect ratio of the conductor in the outer portion, and β is the aspect ratio of the conductor in the inner portion. The electrical resistance value (mΩ) is the value obtained by the above simulation. The "coil size" in Figure 18 is the length or diameter of one side of the outermost circumference. The "conductor spacing x" is the minimum value of the conductor spacing between the innermost turn in the outer portion and the outermost turn in the inner portion.

[0070] Samples S1 to S7 all have an inner portion whose planar shape is a perfect circle and a spiral outer portion whose planar shape is a rounded square, and are examples of the planar coil of the above embodiment. Sample S8 has a rounded square spiral planar shape, and sample S9 has a perfect circle and a spiral planar shape. In other words, samples S8 and S9 are comparative examples. Samples S1 to S9 all have 9 turns, with the number of turns in the inner portion and the outer portion differing in part.

[0071] All of the planar coil samples S1 to S7 satisfy the following requirement [1]. [1] The planar coil has N turns (N is an integer equal to or greater than 2), an inner portion having an inner M turns (M is an integer equal to or greater than 1 and less than N) and a planar shape that is a roughly circular spiral, and an outer portion having an outer (NM) turns and a planar shape that is a rounded polygonal spiral with the corners of the polygon rounded into an arc.

[0072] It was confirmed that all of samples S1 to S7 had reduced electrical resistance values ​​compared to samples S8 and S9, which did not satisfy the above requirement [1]. As described above, reduced electrical resistance can reduce the amount of heat generated by the coil. It was confirmed that satisfying the above requirement [1] can reduce the amount of heat generated by the planar coil.

[0073] Both samples S1 and S3 have 2 turns in the inner portion and 7 turns in the outer portion. Comparing these two samples, sample S3 also satisfies the following requirement [2], while sample S1 does not. The electrical resistance of sample S3 was reduced compared to sample S1 (Figure 17). [2] The thickness of the inner conductor is greater than the thickness of the outer conductor.

[0074] Both samples S5 and S7 have 5 turns in the inner portion and 4 turns in the outer portion. Comparing these two samples, sample S5 also satisfies the above requirement [2], while sample S7 does not. The electrical resistance of sample S5 was lower than that of sample S7 (Figure 17).

[0075] From the above results, it was confirmed that by satisfying the above requirement [2], the heat generation amount of the planar coil can be further reduced.

[0076] Samples S1 and S7 have the same thickness of 0.8 mm for the inner and outer conductors. Comparing these two samples, sample S1 satisfies the above requirement [1] as well as the following requirement [3]. On the other hand, S7 does not satisfy the following requirement [3]. [3] The number of turns on the outer side is equal to or greater than the number of turns on the inner side. Sample S1 had a reduced electrical resistance compared to sample S7 (FIG. 17).

[0077] From the above results, it was confirmed that by satisfying the above requirement [3], the heat generation amount of the planar coil can be further reduced.

[0078] Samples S1 to S5 satisfy the above requirement [1] as well as the following requirement [4]. On the other hand, samples S6 and S7 do not satisfy the following requirement [4]. [4] When the minimum distance between the innermost turn of the outer part and the outermost turn of the inner part is x, the maximum distance between the wires is less than 35x.

[0079] Comparing samples S2, S4, and S6, which have four turns on the inner side and five turns on the outer side, it was confirmed that samples S2 and S4, which have a conductor spacing ratio of less than 35, have lower electrical resistance than sample S6 (Figure 17). Samples S2 and S4 have narrower conductor spacing than sample S6, which also improves self-inductance. Comparing samples S5 and S7, which have five turns on the inner side and four turns on the outer side, it was also confirmed that sample S5, which has a conductor spacing ratio of less than 35, has lower electrical resistance than sample S7 (Figure 17). Furthermore, when comparing sample S1 and sample S7, both of which have coil thicknesses of 0.8 mm on both the inner and outer sides, it was confirmed that sample S1, which has a wire spacing ratio of less than 35, has a lower electrical resistance value than sample S7 (Figure 17).

[0080] From the above results, it was confirmed that the decrease in inductance can be suppressed by satisfying the above requirement [4].

[0081] Samples S1 to S6 satisfy the above requirement [1] as well as the following requirement [5]. On the other hand, S7 does not satisfy the following requirement [5]. [5] If the aspect ratio of the width to the thickness of the cross section of the conductor is the aspect ratio, the aspect ratio of the outer conductor is α, and the aspect ratio of the inner conductor is β, then 1.4<α / β<5.4. Samples S1 to S6 had reduced electrical resistance compared to sample S7 (FIG. 17).

[0082] From the above results, it was confirmed that by satisfying the above requirement [5], the heat generation amount of the planar coil can be further reduced.

[0083] Fig. 19 is a diagram showing the evaluation results of samples S11 to S16 of wireless power supply coil units. Samples S11 to S15 include the above-mentioned sample S3 as a planar coil, and further include the planar coil covered with a magnetic part and a magnetic member laminated thereon. Sample S16 includes the above-mentioned sample S3 as a planar coil, but does not include a magnetic part or magnetic member. In Fig. 19, the real term of the complex relative magnetic permeability of the magnetic part at a frequency of 85 kHz is denoted as A, and the real term of the complex relative magnetic permeability of the magnetic member at a frequency of 85 kHz is denoted as B.

[0084] Sample S15 further satisfies the following requirement [6]: On the other hand, sample S16 does not satisfy the following requirement [6]: In other words, sample S15 is obtained by adding a magnetic portion to sample S16. [6] A magnetic composite material having a resin material and soft magnetic particles contained in the resin material, having a magnetic part that covers a planar coil, and the magnetic composite material is filled between adjacent conductors of the planar coil. Sample S15 had a lower electrical resistance and an improved self-inductance compared to sample S16. That is, it was confirmed that satisfying the above requirement [6] resulted in a lower electrical resistance and an improved self-inductance.

[0085] Sample S14 is obtained by laminating a magnetic member made of a magnetic material having a higher complex relative permeability than the magnetic composite material on sample S16. It was confirmed that sample S14 had a lower electrical resistance and an improved self-inductance compared to sample S16.

[0086] Samples S11 to S13 satisfy the above requirement [6] and further include a magnetic member. Samples S11 and S12 further satisfy the following requirement [7]. [7] If the real term of the complex relative permeability of the magnetic part at a frequency of 85 kHz is A and the real term of the complex relative permeability of the magnetic material at a frequency of 85 kHz is B, then 75 is.

[0087] ​ Compared to sample S13, samples S11 and S12 had similar electrical resistance but improved self-inductance. In other words, it was confirmed that satisfying the above requirement [7] makes it possible to reduce electrical resistance and improve self-inductance. The self-inductance is preferably between 40 μH and 50 μH. This range is within the range specified by the standard. Samples S11 and S12 satisfy the standard for self-inductance.

[0088] <Modification of this embodiment> The present invention is not limited to the above-described embodiment, and can be embodied in various forms without departing from the spirit of the invention. For example, the following modifications are also possible.

[0089] In the second embodiment, the wireless power supply coil unit 41B includes the shielding member 34, but the shielding member 34 may not be included.

[0090] The present disclosure is not limited to the above-described embodiments, and can be realized in various configurations without departing from the spirit thereof. For example, the technical features in the embodiments corresponding to the technical features in each aspect described in the Summary of the Invention section can be appropriately replaced or combined to solve some or all of the above-described problems or achieve some or all of the above-described effects. Furthermore, if a technical feature is not described as essential in this specification, it can be appropriately deleted.

[0091] The present disclosure can also be realized as the following application examples. [Application example 1] A wireless power supply coil unit, A planar coil is provided in which a conducting wire is wound in a spiral shape, The planar coil is The number of turns is N (N is an integer greater than or equal to 2), an inner portion having M turns (M is an integer of 1 or more and less than N) and a plane shape of a substantially circular spiral; An outer (NM) turn, the planar shape of which is a spiral of a rounded polygon with rounded corners; characterized in that it has Wireless power supply coil unit. [Application example 2] The wireless power supply coil unit according to Application Example 1, The thickness of the conductor in the inner portion is greater than the thickness of the conductor in the outer portion. Wireless power supply coil unit. [Application example 3] The wireless power supply coil unit according to Application Example 1 or Application Example 2, The number of turns in the outer portion is equal to or greater than the number of turns in the inner portion. Wireless power supply coil unit. [Application example 4] The wireless power supply coil unit according to any one of Application Examples 1 to 3, When the minimum value of the distance between the innermost turn of the outer portion and the outermost turn of the inner portion is x, the maximum value of the distance between the conductors is less than 35x. Wireless power supply coil unit. [Application example 5] The wireless power supply coil unit according to any one of Application Examples 1 to 4, The cross-sectional shape of the conductor is rectangular, and the width of the cross-section of the conductor relative to the thickness is defined as an aspect ratio, When the aspect ratio of the conductor wire in the outer portion is α and the aspect ratio of the conductor wire in the inner portion is β, 1.4<α / β<5.4 characterized in that Wireless power supply coil unit. [Application Example 6] The wireless power supply coil unit according to any one of Application Examples 1 to 5, moreover, a magnetic portion made of a magnetic composite material having a resin material and soft magnetic particles contained in the resin material, the magnetic portion covering the planar coil; the magnetic composite material is filled between adjacent conductor wires of the planar coil. Wireless power supply coil unit. [Application Example 7] The wireless power supply coil unit according to any one of Application Examples 1 to 6, moreover, a magnetic member laminated on a planar coil covering the magnetic portion, the magnetic member being made of a magnetic material having a complex relative permeability higher than that of the magnetic composite material; a shielding member made of a conductive metal and laminated on the magnetic member on the opposite side of the planar coil; characterized in that it comprises Wireless power supply coil unit. [Application Example 8] The wireless power supply coil unit according to any one of Application Examples 1 to 7, The real term of the complex relative permeability of the magnetic part at a frequency of 85 kHz is defined as A, If the real term of the complex relative permeability of the magnetic member at a frequency of 85 kHz is B, then 75 characterized in that Wireless power supply coil unit. [Application Example 9] The wireless power supply coil unit according to any one of Application Examples 1 to 8, The conductor wires of the planar coil are a pair of first and second conductor wires arranged in parallel. Wireless power supply coil unit. [Application Example 10] The wireless power supply coil unit according to any one of Application Examples 1 to 9, The cross-sectional shape of the conductor is rectangular, The planar coil is a first imaginary plane formed virtually by adjacent spirally wound conductors; a second imaginary surface on the rear side of the first imaginary surface; and the first imaginary surface is planar; ​The second imaginary surface is characterized in that a portion corresponding to the inner portion protrudes more than a portion corresponding to the outer portion. Wireless power supply coil unit. [Explanation of symbols]

[0092] 10, 10A, 10C, 10P...flat coil 10L, 10LC, 10PL…Conductor 11...Inner part 11L…Inner conductor 11O, 12I...Turn 12...Outer part 12L…Outer conductor 13...Connection 15...1st conductor 16…Second conductor 20...Magnetic part 22...Magnetic composite material 24...Resin material 26…Soft magnetic particles 32...Magnetic member 34...Shielding member 40...Wireless power supply device 41, 41B, 41P...Wireless power supply coil unit 44...Circuit board 46...Load 50...Wireless power supply device 51...Wireless power supply coil unit 52...Planar coil 54...Circuit board 56…Power supply device 60...Vehicle 70...Wireless power supply system S1...Side 1 S2...Side 2 SC1: First virtual surface SC2: Second virtual surface

Claims

1. A wireless power supply coil unit, A planar coil is provided in which a conducting wire is wound in a spiral shape, The planar coil is The number of turns is N (N is an integer of 2 or more), an inner portion having an inner M-turn (M is an integer of 1 or more and less than N) and a substantially circular spiral shape in plan view; An outer (N-M) turn, the planar shape of which is a spiral of a rounded polygon with rounded corners; characterized in that it has Wireless power supply coil unit.

2. The wireless power supply coil unit according to claim 1, The thickness of the conductor in the inner portion is greater than the thickness of the conductor in the outer portion. Wireless power supply coil unit.

3. The wireless power supply coil unit according to claim 1, The number of turns in the outer portion is equal to or greater than the number of turns in the inner portion. Wireless power supply coil unit.

4. The wireless power supply coil unit according to claim 1, When the minimum value of the distance between the conductors of the innermost turn of the outer portion and the outermost turn of the inner portion is x, the maximum value of the distance between the conductors is less than 35x. Wireless power supply coil unit.

5. The wireless power supply coil unit according to claim 1, The cross-sectional shape of the conductor is rectangular, and the width of the cross-section of the conductor relative to the thickness is defined as an aspect ratio, When the aspect ratio of the conductor wire in the outer portion is α and the aspect ratio of the conductor wire in the inner portion is β, １．４＜α／β＜５．４ characterized in that Wireless power supply coil unit.

6. The wireless power supply coil unit according to claim 1, moreover, a magnetic portion made of a magnetic composite material having a resin material and soft magnetic particles contained in the resin material, the magnetic portion covering the planar coil; the magnetic composite material is filled between adjacent conductor wires of the planar coil. Wireless power supply coil unit.

7. The wireless power supply coil unit according to claim 6, moreover, a magnetic member laminated on a planar coil covering the magnetic portion, the magnetic member being made of a magnetic material having a complex relative permeability higher than that of the magnetic composite material; a shielding member made of a conductive metal and laminated on the magnetic member on the opposite side of the planar coil; characterized in that it comprises Wireless power supply coil unit.

8. The wireless power supply coil unit according to claim 7, The real term of the complex relative permeability of the magnetic part at a frequency of 85 kHz is defined as A, If the real term of the complex relative permeability of the magnetic member at a frequency of 85 kHz is B, then 75<B / A<370 characterized in that Wireless power supply coil unit.

9. The wireless power supply coil unit according to any one of claims 1 to 8, The conductor wires of the planar coil are a pair of first and second conductor wires arranged in parallel. Wireless power supply coil unit.

10. The wireless power supply coil unit according to claim 2, The cross-sectional shape of the conductor is rectangular, The planar coil is a first imaginary surface formed imaginarily by adjacent spirally wound conductors; a second imaginary surface on the rear side of the first imaginary surface; and the first imaginary surface is planar; The second imaginary surface is characterized in that a portion corresponding to the inner portion protrudes more than a portion corresponding to the outer portion. Wireless power supply coil unit.

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