Coil assembly

Abstract

To suppress more the unevenness of a current between flat coils in a coil assembly.SOLUTION: A coil assembly 100 includes a plurality of coil layers S1 to S4 laminated in a lamination direction and each having a plurality of plane coils 1 to 8 connected in parallel to one another wound in the plane direction X-Y perpendicular to the lamination direction. The coil layers form a plurality of coil parts a to d each formed of at least one plane coil and connected in parallel to one another. The coil layers include first-pitch coil layers S1, S2, and second-pitch coil layers S3, S4 of which pitches among element lines adjacent to one another are different from each other. The pitch p1 of the first-pitch coil layers is larger than pitches p2 and p3 of the second-pitch coil layers.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a coil assembly comprising a plurality of planar coils. [Background technology]

[0002] Conventionally, coil assemblies having multiple coil layers each having a planar coil have been used. When such a coil assembly is used together with a magnetic body such as a magnetic sheet, the self-inductance of each planar coil differs due to the difference in distance from the magnetic body. As a result, in a configuration in which multiple coil parts each composed of one or multiple planar coils connected in series are connected in parallel, there may be a difference in impedance between each coil part. When such an impedance difference occurs, there is a problem that current concentration occurs in some coil parts, which increases loss. Therefore, a technology has been proposed to suppress the difference in impedance between each coil part by making the line length of the planar coil longer in coil layers that are farther away from the magnetic body (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-186303 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the coil assembly described above, the mutual inductance between the coil parts affects the impedance of each coil part. However, the above technology for adjusting the line length of the planar coil according to the distance from the magnetic body does not take the mutual inductance between the coil parts into consideration, and there is still a risk of the above-mentioned difference in impedance between the coil parts occurring.

[0005] Such a problem is not limited to a configuration in which a magnetic material is used together with a coil assembly, but may also occur in a configuration in which a magnetic material is not used. For example, it may also occur in a coil assembly having a configuration in which planar coils included in different coil layers are connected in series to form one coil section, and such coil sections are connected in parallel. Specifically, for example, in a coil assembly in which the first to fourth layers are stacked in this order, when a coil section consisting of a planar coil in the first coil layer and a planar coil in the fourth coil layer is compared with a coil section consisting of a planar coil in the second coil layer and a planar coil in the third coil layer, the former coil section has a larger distance between the planar coils than the latter coil section, resulting in a smaller mutual inductance, and the above problem may occur. For this reason, a technology capable of further suppressing the current bias between the coil sections is desired. [Means for solving the problem]

[0006] As one embodiment of the present disclosure, a coil assembly (100-108) is provided. The coil assembly includes a plurality of coil layers (S1-S4, S11-S12, S21-S24, S31-S34, S41-S44, S51-S56, S61-S64, S71-S74) stacked in a stacking direction, each of which has a plurality of planar coils (1-8, 1,2,5,6, 1-12, 1a-4a, 5-8, 1-8) wound in a planar direction (XY) intersecting the stacking direction (Z) and connected in parallel to each other. The plurality of coil layers constitute a plurality of coil sections (a-d, a-f) each of which is composed of at least one of the planar coils and connected in parallel to each other. The coil layers include first pitch coil layers (S1, S2, S11, S21, S22, S31, S32, S41, S42, S51, S52, S53, S54, S61, S62, S72, S73) and second pitch coil layers (S3, S4, S12, S23, S24, S33, S34, S43, S44, S53, S54, S55, S56, S63, S64, S71, S74) having different pitches between adjacent wires. The pitch (p1) of the first pitch coil layer is larger than the pitch (p2, p3) of the second pitch coil layer.

[0007] According to the coil assembly of the above embodiment, the multiple coil layers include a first pitch coil layer and a second pitch coil layer in which the pitch between adjacent wires is different from each other, and the pitch of the first pitch coil layer is larger than that of the second pitch coil layer, so that in a configuration in which a magnetic body is used together with the coil assembly and the second coil layer is disposed farther from the magnetic body than the first coil layer, it is possible to suppress the occurrence of a difference in impedance between the coil parts and suppress the occurrence of a current bias between the coil parts. Also, for example, in a configuration in which the multiple coil layers include a first coil layer, a second coil layer, a third coil layer, and a fourth coil layer stacked in this order, and which has a coil part consisting of a planar coil of the first coil layer and a planar coil of the fourth coil layer and a coil part consisting of a planar coil of the second coil layer and a planar coil of the third coil layer, and the first and fourth coil layers are sandwiched between the second coil layer and the third coil layer, it is possible to suppress the difference in mutual inductance between the coil parts and suppress the occurrence of a difference in impedance between the coil parts. [Brief description of the drawings]

[0008] [Figure 1] 1 is an exploded plan view showing a schematic configuration of a coil assembly according to an embodiment of the present disclosure; [Diagram 2] 1 is a block diagram showing a schematic configuration of a contactless power supply system to which a coil assembly according to a first embodiment is applied. [Diagram 3] FIG. 2 is an explanatory diagram showing an equivalent circuit of the coil assembly according to the first embodiment. [Figure 4] FIG. 2 is a partial cross-sectional view of the coil assembly according to the first embodiment. [Diagram 5] 4 is an explanatory diagram for explaining impedance of each coil portion in the coil assembly of the first embodiment. FIG. [Figure 6] FIG. 2 is a partial cross-sectional view of the coil assemblies of Examples 1-1 to 1-3. [Figure 7] FIG. 2 is a partial cross-sectional view of a coil assembly of Comparative Example 1. [Figure 8]FIG. 13 is an explanatory diagram showing the results of numerical analysis of various parameters relating to impedance of the coil assemblies of Examples 1-1 to 1-3 and Comparative Example 1. [Figure 9] FIG. 11 is a partial cross-sectional view of a coil assembly according to a second embodiment. [Figure 10] FIG. 11 is an explanatory diagram showing an equivalent circuit of a coil assembly according to a second embodiment. [Figure 11] FIG. 11 is a partial cross-sectional view of a coil assembly according to a third embodiment. [Figure 12] FIG. 11 is a partial cross-sectional view of a coil assembly according to a fourth embodiment. [Figure 13] FIG. 13 is a partial cross-sectional view of a coil assembly according to a fifth embodiment. [Figure 14] FIG. 13 is a partial cross-sectional view of a coil assembly according to a sixth embodiment. [Figure 15] FIG. 13 is a partial cross-sectional view of a coil assembly according to a seventh embodiment. [Figure 16] FIG. 13 is an explanatory diagram showing an equivalent circuit of a coil assembly according to the seventh embodiment. [Figure 17] FIG. 13 is a partial cross-sectional view of a coil assembly according to an eighth embodiment. [Figure 18] FIG. 13 is a partial cross-sectional view of a coil assembly according to a ninth embodiment. [Figure 19] FIG. 13 is an explanatory diagram showing an equivalent circuit of a coil assembly according to the ninth embodiment. [Figure 20] FIG. 11 is a partial cross-sectional view of a coil assembly according to a second embodiment. [Figure 21] FIG. 11 is a partial cross-sectional view of a coil assembly of Comparative Example 2. [Figure 22] FIG. 13 is an explanatory diagram showing the results of numerical analysis of various parameters relating to impedance of the coil assemblies of Example 2 and Comparative Example 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] A. First embodiment: A1. Overall configuration: The coil assembly 100 shown in Fig. 1 and Fig. 2 includes a first coil layer S1, a second coil layer S2, a third coil layer S3, and a fourth coil layer S4 shown in Fig. 1. The coil assembly 100 as a whole forms a coil (inductor). In this embodiment, the coil assembly 100 is used in a contactless power supply system 500 shown in Fig. 2. A detailed configuration of the coil assembly 100 will be described later. The contactless power supply system 500 is a system for supplying power supplied from a power supply device 300 to a load device 300A electrically connected to the power receiving device 200A by contactlessly transmitting power from a power transmitting device 200 to the power receiving device 200A.

[0010] As shown in FIG. 2, the contactless power supply system 500 includes a resonant circuit 150 including a coil assembly 100, a power transmitting device 200 including the resonant circuit 150, a power transmitting output circuit 210, a power receiving side coil assembly 100A, a resonant circuit 150A including the power receiving side coil assembly 100A, a power receiving device 200A including the resonant circuit 150A, and a rectifier circuit 210A.

[0011] The resonant circuit 150 has a configuration in which an inductor formed by the coil assembly 100 and a capacitor (not shown) are connected in series. The power transmitting device 200 includes the resonant circuit 150, and uses power supplied from the power transmitting output circuit 210 to supply power to the power receiving device 200A in a non-contact manner.

[0012] The power transmission output circuit 210 includes an inverter circuit and a filter circuit (not shown), converts the DC power supplied from the power supply device 300 into AC power of a predetermined operating frequency, and also removes noise components from the AC power before supplying it to the power transmitting device 200.

[0013] The coil assembly 100 includes a magnetic body 110. The magnetic body 110 is a thin plate-like member made of a magnetic material, and is made of ferrite in this embodiment. As shown in FIG. 2, the magnetic body 110 is disposed on the opposite side of the coil assembly 100 from the side facing the power receiving coil assembly 100A. The magnetic body 110 directs the interlinkage magnetic flux generated in the coil assembly 100 more efficiently toward the power receiving coil assembly 100A, and increases the magnetic flux penetrating the power receiving coil assembly 100A. Other detailed configurations of the coil assembly 100 will be described later.

[0014] The power receiving side coil assembly 100A is an inductor constituting a part of the resonant circuit 150A included in the power receiving device 200A. The configuration of the power receiving side coil assembly 100A is the same as that of the coil assembly 100 described in detail later. The power receiving side coil assembly 100A includes a power receiving side magnetic body 110A, similar to the coil assembly 100. The power receiving side magnetic body 110A has a configuration similar to that of the magnetic body 110 described above. The power receiving device 200A includes a resonant circuit 150A in which an inductor formed by the power receiving side coil assembly 100A and a capacitor (not shown) are connected in series. While power is being supplied to the power transmitting device 200, the resonant circuit 150 in the power transmitting device 200 is in a resonant state at a predetermined operating frequency, and a magnetic flux linkage is generated. The interlinking magnetic flux passes through the power receiving coil assembly 100A of the power receiving device 200A, and the magnetic flux generates an induced electromotive force in the power receiving device 200A, transmitting and receiving power. The rectifier circuit 210A includes a bridge circuit and a smoothing capacitor (not shown), and converts the AC power output from the power receiving device 200A into DC power and supplies it to the load device 300A.

[0015] The contactless power supply system 500 having the above-mentioned configuration may be used, for example, by disposing the power transmission output circuit 210 and the power transmitting device 200 underground or on the ground surface, and mounting the power receiving device 200A, the rectifier circuit 210A, and the load device 300A on a moving body such as an electric vehicle, to supply power to the moving body. In such a configuration, the load device 300A corresponds to a battery or a motor mounted on the moving body.

[0016] A2. Detailed configuration of coil assembly 100: In the coil assembly 100, the four coil layers S1 to S4 shown in FIG. 1 are stacked along the Z axis. Specifically, the first coil layer S1, the second coil layer S2, the third coil layer S3, and the fourth coil layer S4 are stacked in the +Z direction in this order. Note that FIG. 1 shows an X axis, a Y axis, and a Z axis that are orthogonal to each other, and these XYZ axes correspond to the XYZ axes in other drawings. The direction from the power transmitting device 200 to the power receiving device 200A shown in FIG. 2 corresponds to the +Z direction. Note that the magnetic body 110 is omitted in FIG. 1.

[0017] Each of the coil layers S1 to S4 includes a plurality of planar coils made of wire wound in the XY plane. In this embodiment, the wire is made of copper foil. The number of planar coils included in each of the coil layers S1 to S4 is "2". Each of the coil layers S1 to S4 has a configuration in which an insulator such as prepreg is sandwiched between coil patterns of planar coils made of copper foil. The planar coil located on the outermost side (front surface side) of the coil assembly 100 may be covered with, for example, solder resist.

[0018] The first coil layer S1 includes a first planar coil 1 and a second planar coil 2. The second coil layer S2 includes a third planar coil 3 and a fourth planar coil 4. The third coil layer S3 includes a fifth planar coil 5 and a sixth planar coil 6. The fourth coil layer S4 includes a seventh planar coil 7 and an eighth planar coil 8. Each of the planar coils 1 to 8 has two turns. The number of turns of each of the planar coils 1 to 8 is not limited to two and may be any number.

[0019] Coil assembly 100 has four through-hole vias v1, v2, v3, and v4 formed through each of coil layers S1-S4. Second planar coil 2 and third planar coil 3 each have one end connected to through-hole via v1. Sixth planar coil 6 and seventh planar coil 7 each have one end connected to through-hole via v2. First planar coil 1 and fourth planar coil 4 each have one end connected to through-hole via v3. Fifth planar coil 5 and eighth planar coil 8 each have one end connected to through-hole via v4.

[0020] The first coil layer S1 has a connection terminal t1 at its center. The second coil layer S2 has a connection terminal t2 at its center. The third coil layer S3 has a connection terminal t3 at its center. The fourth coil layer S4 has a connection terminal t4 at its center. The other end of the first planar coil 1 and the other end of the second planar coil 2 are connected to the connection terminal t1. The other end of the third planar coil 3 and the other end of the fourth planar coil 4 are connected to the connection terminal t2. The other end of the fifth planar coil 5 and the other end of the sixth planar coil 6 are connected to the connection terminal t3. The other end of the seventh planar coil 7 and the other end of the eighth planar coil 8 are connected to the connection terminal t4. The connection terminal t1 and the connection terminal t3 are electrically connected to each other by vias (not shown). The connection terminal t2 and the connection terminal t4 are electrically connected to each other by vias (not shown). The connection terminal portion t1 and the connection terminal portion t4 are exposed on the −Z direction end face and the +Z direction end face of the coil assembly 100, and are connected to the power transmitting device 200 via a capacitor not shown.

[0021] As shown in FIG. 3, the first planar coil 1 and the fourth planar coil 4 are connected in series to form the coil section a. Similarly, the second planar coil 2 and the third planar coil 3 are connected in series to form the coil section b, the fifth planar coil 5 and the eighth planar coil 8 are connected in series to form the coil section c, and the sixth planar coil 6 and the seventh planar coil 7 are connected in series to form the coil section d. These four coil sections a to d are connected in parallel with each other. Hereinafter, the current flowing through the coil section a is referred to as the current Ia. Similarly, the current flowing through the coil section b is referred to as Ib, the current flowing through the coil section c is referred to as Ic, and the current flowing through the coil section d is referred to as Id, respectively. In this way, by connecting the four coil sections a to d in parallel, each wire can be made thinner, and the generation of eddy currents can be suppressed to improve the power transmission efficiency. Note that the magnetic body 110 is omitted in FIG. 3.

[0022] 4, the third coil layer S3 and the fourth coil layer S4 are disposed farther away from the magnetic body 110 than the first coil layer S1 and the second coil layer S2. In the first coil layer S1, a pitch p1 (hereinafter referred to as a "first pitch p1") between adjacent wires in a direction along the XY plane (hereinafter referred to as a "planar direction"), i.e., between the wires of the first planar coil 1 and the wires of the second planar coil 2, is equal to a pitch p1 between adjacent wires in the planar direction in the second coil layer S2, i.e., between the wires of the third planar coil 3 and the wires of the fourth planar coil 4. In addition, the pitch p2 (hereinafter referred to as "second pitch p2") between adjacent wires in the third coil layer S3 in the planar direction, i.e., between the wires of the fifth planar coil 5 and the wires of the sixth planar coil 6, is equal to the pitch p2 between adjacent wires in the planar direction, i.e., between the wires of the seventh planar coil 7 and the wires of the eighth planar coil 8, in the fourth coil layer S4. In this embodiment, the "pitch between wires" refers to the planar distance between the center of the width of a wire and the center of the width of an adjacent wire. Note that the center positions Ct1 of the wound wire groups in each of the coil layers S1 to S4 are aligned with each other. Note that FIG. 4 shows a cross section taken along line IV-IV in FIG. 1.

[0023] In this embodiment, the first coil layer S1 and the second coil layer S2 correspond to the "first pitch coil layer" of the present disclosure, and the third coil layer S3 and the fourth coil layer S4 correspond to the "second pitch coil layer" of the present disclosure.

[0024] In this embodiment, the pitch of the first coil layer, i.e., the first pitch p1, is larger than the pitch of the second coil layer, i.e., the second pitch p2. The reason for this configuration will be described with reference to FIGS.

[0025] The equivalent circuit shown in Fig. 3 is expressed by formulas 1-a, 1-b, 1-c, and 1-d shown in the top row of Fig. 5. In each of formulas 1-a to 1-d, V is the terminal voltage of the coil parts a to d, Ra to Rd are the resistance of each of the coil parts a to d, La to Ld are the self-inductance of each of the coil parts a to d, Mxy (x = a to d, y = a to d) are the mutual inductance between the coil parts x and y, and ω is the angular frequency. Note that Ia to Id are the currents flowing through each of the coil parts a to d, as described above.

[0026] In the four coil parts a to d connected in parallel, when there is no bias in the current, Ia=Ib=Ic=Id. Therefore, formulas 1-a to 1-d can be transformed into formulas 2-a to 2-d in the second row. Here, by replacing the "sum of self-inductance and mutual inductance" in formulas 2-a to 2-d with Sa, Sb, Sc, and Sd (hereinafter referred to as "inductance parameters") as in formulas 3-a to 3-d in the third row, formulas 4-a to 4-d in the fourth row are obtained. In the four coil parts a to d, in an ideal state where there is no bias in the current, the left sides of formulas 4-a to 4-d are all equal to "V / Ia". In this way, in order to achieve a state where there is no bias in the current, it is sufficient that Ra=Rb=Rc=Rd is satisfied for the resistance and Sa=Sb=Sc=Sd is satisfied for the inductance parameters.

[0027] In this embodiment, the resistances Ra to Rd are the same in the coil parts a to d, and the line lengths of the coil parts a to d are equal to each other. Specifically, as shown in Fig. 1, a first planar coil 1 wound radially outward in the first coil layer S1 and a fourth planar coil 4 wound radially inward in the second coil layer S2 are connected in series, and a second planar coil 2 wound radially inward in the first coil layer S1 and a third planar coil 3 wound radially outward in the second coil layer S2 are connected in series, thereby making the line lengths of the wires in the coil parts a and b equal. Similarly, fifth planar coil 5 wound radially outward in third coil layer S3 and eighth planar coil 8 wound radially inward in fourth coil layer S4 are connected in series, while sixth planar coil 6 wound radially inward in third coil layer S3 and seventh planar coil 7 wound radially outward in fourth coil layer S4 are connected in series, thereby making the line lengths of the wires in coil section c and coil section d equal. Furthermore, since the centers of coils a to d coincide at center position Ct1, the line lengths of coil sections a, b and coil sections c, d can be made substantially equal.

[0028] In this embodiment, among the inductance parameters Sa to Sd, the self-inductances La to Ld are made uniform by using wires of the same thickness in each of the coil parts a to d and winding the wires with the same number of turns. However, the self-inductance of the coil parts farther from the magnetic body 110 is smaller than that of the coil parts closer to the magnetic body 110. Therefore, differences may occur in the self-inductances La to Ld. Therefore, in this embodiment, the above-mentioned pitch difference is used to cause differences in the mutual inductances Mxy (x=a to d, y=a to d), and such differences cancel the above-mentioned differences in the self-inductances La to Ld. Specifically, the first pitch p1 in the first planar coil 1 and the second planar coil 2, which are closer to the magnetic body 110, is made larger than the second pitch p2 in the third planar coil 3 and the fourth planar coil 4, which are farther from the magnetic body 110, thereby reducing the mutual inductance Mab and canceling the large self-inductance. In other words, in the two coil parts a and b having larger self-inductances La and Lb compared to the self-inductances Lc and Ld, the pitch between adjacent strands is made larger to reduce the mutual inductance Mab and suppress the difference in inductance parameters Sa to Sd. This suppresses the occurrence of impedance differences in the coil parts a to d, and suppresses the decrease in loss due to current concentration in a specific coil part.

[0029] In the coil assembly 100 of this embodiment, the first pitch p1 and the second pitch p2 are adjusted so that the inductance parameters Sa to Sd, i.e., the sums of the self-inductance and the mutual inductance, are equal to each other. Note that "the sums of the self-inductance and the mutual inductance are equal to each other" has a broader meaning including not only the case where the sums are exactly equal, but also the case where the relationship between the sums of the self-inductance and the mutual inductance can reduce the difference in the inductance parameters between the coil sections a to d, as compared to a configuration in which the first pitch p1 and the second pitch p2 are equal to each other.

[0030] A3. Working Example: As an example of the coil assembly 100 of the first embodiment, a coil assembly 100x shown in Fig. 6 was numerically analyzed, and a coil assembly 900x of Comparative Example 1 shown in Fig. 7 was also numerically analyzed. Then, as shown in Fig. 8, mutual inductance Mab and inductance parameters Sa to Sd of these coil assemblies 100x and 900x were numerically analyzed to confirm their effects.

[0031] In the coil assembly 100x shown in FIG. 6, the number of turns of the wire in each of the coil layers S1 to S4 is 6. In each of the coil layers S1 to S4, the central positions Ct10 of the wire groups wound are aligned with each other. As shown in FIG. 8, the coil assemblies 100x of three examples 1-1, 1-2, and 1-3, which have different first pitches p1, were evaluated by numerical analysis. In each of the examples 1-1 to 1-3, the distance from the central axis Cu1 (the axis extending parallel to the Z axis from the central position when viewed in the Z axis direction) of each of the coil layers S1 to S4 to the central position Ct10 was 20 mm (millimeters). The wire had a thickness of 70 μm (micrometers) and a width of 0.5 mm. The magnetic body 110 had a thickness of 1 mm. The aluminum shield 112x had a thickness of 1 mm. The second pitch p2 was 1 mm in each case. As shown in FIG. 8, the first pitch p1 was 1.06 mm in Example 1-1, 1.12 mm in Example 1-2, and 1.18 mm in Example 1-3. On the other hand, in the coil assembly 900x of Comparative Example 1, the size of the first pitch p1 was 1.00 mm, which was the same as the second pitch p2, and the coil assembly 900x of Comparative Example 1 was different from the coil assembly 100x of Examples 1-1 to 1-3 in that the other configurations were the same. A current of 1 A was applied to the coil assembly 100x at a frequency of 85 kHz. The magnetic body 110 was made of ferrite. The planar coil, the magnetic body 110, and the aluminum shield 112x constituting each of the coil layers S1 to S4 were circular in plan view.

[0032] As shown in Fig. 8, by increasing the magnitude of the first pitch p1, the mutual inductance Mab becomes smaller. Therefore, the inductance parameters Sa and Sb can be made smaller, and the difference between the inductance parameters Sa to Sd can be suppressed. As a result, the difference between the currents Ia to Id becomes smaller, and in each of Examples 1-1 to 1-3, the AC resistance R of the coil assembly is suppressed to be lower than that of Comparative Example 1.

[0033] According to the coil assembly 100 of the first embodiment described above, the pitch in the first pitch coil layer, i.e., the first pitch p1 between adjacent wires in the planar direction in the coil parts a and b, is larger than the pitch in the second pitch coil layer, i.e., the second pitch p2 between adjacent wires in the planar direction in the coil parts c and d, so that the difference in self-inductance between the coil parts a and b and the coil parts c and d caused by the difference in distance from the magnetic body 110 can be at least partially cancelled, and the difference in impedance between the coil parts a to d can be suppressed, thereby suppressing the current bias between the coil parts a to d. Specifically, the coil parts a and b are arranged closer to the magnetic body 110 than the coil parts c and d, so that the self-inductance in the coil parts a and b is larger than the self-inductance of the coil parts c and d. However, since the first pitch p1 between adjacent wires in the planar direction in the coil portions a and b is larger than the second pitch p2 between adjacent wires in the planar direction in the coil portions c and d, the mutual inductance in the coil portions a and b is smaller than the mutual inductance in a configuration in which the pitch of the coil portions a and b is equal to the second pitch p2. This makes it possible to suppress the occurrence of differences in impedance among the coil portions a to d.

[0034] In addition, in each of the coil sections a to d, the planar coil wound radially inward and the planar coil wound radially outward are connected in series, thereby suppressing differences in the wire line lengths between the coil sections and suppressing differences in impedance between the coil sections.

[0035] Furthermore, the pitch (second pitch p2) between adjacent wires in the farthest coil layer S4, which is the farthest from the magnetic body 110 among the multiple coil layers S1 to S4, and the coil layer S3 connected in series to the farthest coil layer S4 is smaller than the pitch (first pitch p1) between adjacent wires in the other coil layers S1, S2, so that the mutual inductance of coil sections c, d, which are the farthest from the magnetic body 110 and have the smallest self-inductance among the multiple coil sections a to d, can be made larger than the mutual inductance in a configuration in which the pitch between adjacent wires in coil sections c, d is equal to the first pitch p1. This makes it possible to suppress differences in impedance between the coil sections a to d.

[0036] Furthermore, since the sums of the self-inductances and the mutual inductances are equal among the coil portions a to d, it is possible to suppress the occurrence of differences in impedance among the coil portions a to d.

[0037] B. Second embodiment: A coil assembly 101 of the second embodiment shown in FIG. 9 differs from the coil assembly 100 of the first embodiment in that it has two coil layers, but the other configurations are similar. In the coil assembly 101, the same components as those in the coil assembly 100 are given the same reference numerals, and detailed descriptions thereof will be omitted. Note that FIG. 9 shows a cross section at a position similar to the cross section IV-IV in FIG. 1. The coil assembly 101 includes a first coil layer S11 and a second coil layer S12 stacked on top of each other. The configurations of the first coil layer S11 and the second coil layer S12 are similar to the configurations of the first coil layer S1 and the second coil layer S2 of the first embodiment.

[0038] The first coil layer S11, which is closest to the magnetic body 110, has a first planar coil 1 and a second planar coil 2 formed therein, similar to the first coil layer S1 of the first embodiment. The second coil layer S22, which is farthest from the magnetic body 110, has a fifth planar coil 5 and a sixth planar coil 6 formed therein, similar to the third coil layer S3 of the first embodiment. As shown in FIG. 10, the first planar coil 1, the second planar coil 2, the fifth planar coil 5, and the sixth planar coil 6 are connected in parallel to one another. Note that the center positions Ct2 of the wire groups in each of the coil layers S1 and S2 coincide with one another.

[0039] In the coil assembly 101 of the second embodiment, as in the coil assembly 100 of the first embodiment, the pitch (first pitch) p1 between adjacent wires in the planar direction in the first coil layer S11 is larger than the pitch (second pitch) p2 between adjacent wires in the planar direction in the second coil layer S12.

[0040] The coil assembly 101 of the second embodiment described above has the same effects as the coil assembly 100 of the first embodiment. In the second embodiment, the first coil layer S11 corresponds to the first pitch coil layer of the present disclosure, and the second coil layer S12 corresponds to the second pitch coil layer of the present disclosure.

[0041] C. Third embodiment: The coil assembly 102 of the third embodiment shown in FIG. 11 includes a first coil layer S21, a second coil layer S22, a third coil layer 23, and a fourth coil layer 24 stacked on top of each other. The configurations of the first coil layer S21 to the fourth coil layer S24 are the same as those of the first coil layer S1 to the fourth coil layer S4 of the first embodiment. However, the coil assembly 102 differs from the coil assembly 100 of the first embodiment in that each of the coil layers S21 to S24 includes three planar coils, but the other configurations are the same. In the coil assembly 101, the same components as those in the coil assembly 100 are denoted by the same reference numerals, and detailed descriptions thereof will be omitted. Note that FIG. 11 shows a cross section at the same position as the IV-IV cross section in FIG. 1. In each coil layer, the center positions Ct3 of the strands of wires are aligned with each other.

[0042] In the coil assembly 102, the first coil layer S21 includes three planar coils 1 to 3. The second coil layer S22 includes three planar coils 4 to 6. The third coil layer S23 includes three planar coils 7 to 9. The fourth coil layer S24 includes three planar coils 10 to 12. Planar coils with the same hatching are connected in series to each other.

[0043] In the coil assembly 102 of the second embodiment, as in the coil assembly 100 of the first embodiment, the pitch (first pitch) p1 between adjacent wires in the planar direction in the two coil layers S21, S22 closer to the magnetic body 110 is larger than the pitch (second pitch) p2 between adjacent wires in the planar direction in the two coil layers S23, S24 farther away.

[0044] The coil assembly 102 of the third embodiment described above has the same effects as the coil assembly 100 of the first embodiment. In the third embodiment, the first coil layer S21 and the second coil layer S22 correspond to the first pitch coil layer of the present disclosure, and the third coil layer S23 and the fourth coil layer S24 correspond to the second pitch coil layer of the present disclosure.

[0045] D. Fourth embodiment: A coil assembly 103 of the fourth embodiment shown in Fig. 12 differs from the coil assembly 102 of the third embodiment shown in Fig. 11 in that the pitch between the wires in the planar direction is not constant in each of the coil layers S21 to S24. In the coil assembly 103, the same components as those in the coil assembly 102 are given the same reference numerals, and detailed descriptions thereof will be omitted. Note that Fig. 12 shows a cross section at a position similar to the IV-IV cross section in Fig. 1.

[0046] As shown in FIG. 12, the pitch between the wires in the planar direction between the first turn located on the radially outer side and the second turn located on the radially inner side is different from the pitch between the wires in the planar direction within the same turn. Specifically, in the first coil layer S21 and the second coil layer S22, the pitch p11 between the wires between the first turn and the second turn is larger than the first pitch p1. Similarly, in the third coil layer S23 and the fourth coil layer S24, the pitch p21 between the wires between the first turn and the second turn is larger than the second pitch p2. However, the pitch p11 is larger than the pitch p21. In this embodiment, the pitch p21 is larger than the pitch p1. However, the average value of the first pitch p1 and the pitch p11 is larger than the average value of the second pitch p2 and the pitch p21. Note that the magnitude relationship between the pitches is not limited to the above-mentioned magnitude relationship, provided that the average value of the first pitch p1 and the pitch p11 is larger than the average value of the second pitch p2 and the pitch p21. 12, the pitch between the wires in each layer is uniform between the turns, but the pitch between the wires in each layer may be different between the turns, assuming the above conditions. For example, in first coil layer S1, the pitch between first planar coil 1 and second planar coil 2 in the first turn may be different from the pitch between first planar coil 1 and second planar coil 2 in the second turn.

[0047] The coil assembly 103 of the fourth embodiment described above provides the same effects as the coil assembly 102 of the third embodiment.

[0048] E. Fifth embodiment: The coil assembly 104 of the fifth embodiment shown in FIG. 13 includes a first coil layer S31, a second coil layer S32, a third coil layer S33, and a fourth coil layer S34 stacked on top of each other. The configurations of the first coil layer S31 to the fourth coil layer S34 are the same as those of the first coil layer S1 to the fourth coil layer S4 of the first embodiment. The coil assembly 104 is different from the coil assembly 100 of the first embodiment in that the width of the wire of the first coil layer S31 and the second coil layer S32 is larger than the width of the wire of the first coil layer S1 and the second coil layer S2. In the coil assembly 104, the same components as those of the coil assembly 100 are denoted by the same reference numerals, and detailed description thereof will be omitted. Note that FIG. 13 shows a cross section at a position similar to the IV-IV cross section in FIG. 1.

[0049] The width d1 of the first planar coil 1a and the second planar coil 2a in the first coil layer S31 is equal to the width d1 of the third planar coil 3a and the fourth planar coil 4a in the second coil layer S32. These widths d1 are larger than the widths d2 of the planar coils 5 to 8 in the third coil layer S33 and the fourth coil layer S34. With this configuration, the distance between the strands in the planar direction (the length of the gap between the strands) in the first coil layer S31 and the second coil layer S32 is smaller than the distance between the strands in the third coil layer S33 and the fourth coil layer S34. However, even in the fifth embodiment, the pitch (first pitch) p1 between adjacent strands in the planar direction in the first coil layer S31 and the second coil layer S32 is larger than the pitch (second pitch) p2 between adjacent strands in the planar direction in the third coil layer S33 and the fourth coil layer S34. In addition, the distance between the wires in the planar direction (the length of the gap between the wires) in the first coil layer S31 and the second coil layer S32 may be configured to be equal to the distance between the wires in the third coil layer S33 and the fourth coil layer S34.

[0050] The coil assembly 104 of the fifth embodiment described above has the same effects as the coil assembly 100 of the first embodiment. In the fifth embodiment, the first coil layer S31 and the second coil layer S32 correspond to the first pitch coil layer of the present disclosure, and the third coil layer S33 and the fourth coil layer S34 correspond to the second pitch coil layer of the present disclosure.

[0051] F. Sixth embodiment: The coil assembly 105 of the sixth embodiment shown in FIG. 14 includes a first coil layer S41, a second coil layer S42, a third coil layer 43, and a fourth coil layer 44 stacked on top of each other. The configurations of the first coil layer S41 to the fourth coil layer S44 are the same as those of the first coil layer S1 to the fourth coil layer S4 of the first embodiment. However, the coil assembly 105 differs from the coil assembly 100 of the first embodiment in that the number of turns of each planar coil is "3". In the coil assembly 105, the same components as those of the coil assembly 100 are denoted by the same reference numerals, and detailed description thereof will be omitted. Note that FIG. 14 shows a cross section at a position similar to the IV-IV cross section in FIG. Note that the center positions Ct5 of the strand groups in each of the coil layers S41 to S44 are the same as each other.

[0052] The coil assembly 105 of the sixth embodiment described above has the same effects as the coil assembly 100 of the first embodiment. In the sixth embodiment, the first coil layer S41 and the second coil layer S42 correspond to the first pitch coil layer of the present disclosure, and the third coil layer S43 and the fourth coil layer S44 correspond to the second pitch coil layer of the present disclosure.

[0053] G. Seventh embodiment: A coil assembly 106 of the seventh embodiment shown in Figs. 15 and 16 includes a first coil layer S51, a second coil layer S52, a third coil layer S53, a fourth coil layer S54, a fifth coil layer S55, and a sixth coil layer S56, which are stacked on top of each other. The coil assembly 106 differs from the coil assembly 100 of the first embodiment in that it includes six coil layers. In the coil assembly 106, the same components as those in the coil assembly 100 are denoted by the same reference numerals, and detailed descriptions thereof will be omitted. Note that Fig. 15 shows a cross section at a position similar to the IV-IV cross section in Fig. 1. In each coil layer, the center positions Ct6 of the strands of wire coincide with each other.

[0054] The configurations of the first coil layer S51 to the fourth coil layer S54 are similar to those of the first coil layer S1 to the fourth coil layer S4 of the first embodiment. The fifth coil layer S55 includes a ninth planar coil 9 and a tenth planar coil 10. The sixth coil layer S56 includes an eleventh planar coil 11 and a twelfth planar coil 12. As shown in FIG. 16, the ninth planar coil 9 and the twelfth planar coil 12 are connected in series to each other to form a coil section e. Similarly, the tenth planar coil 10 and the eleventh planar coil 11 are connected in series to each other to form a coil section f. These two coil sections e and f are connected in parallel to the other coil sections a to d.

[0055] As shown in FIG. 15, in the fifth coil layer S55 and the sixth coil layer S56, the pitch p3 between adjacent wires in the planar direction (hereinafter referred to as the "third pitch p3") is equal to each other and smaller than the second pitch p2.

[0056] The coil assembly 106 of the seventh embodiment described above has the same effects as the coil assembly 100 of the first embodiment. In the seventh embodiment, the first coil layer S51 and the second coil layer S52 of the four coil layers S51 to S54 correspond to the first pitch coil layer of the present disclosure, and the third coil layer S53 and the fourth coil layer S54 correspond to the second pitch coil layer of the present disclosure. In addition, in the four coil layers S53 to S56, the third coil layer S53 and the fourth coil layer S54 correspond to the first pitch coil layer of the present disclosure, and the fifth coil layer S55 and the sixth coil layer S56 correspond to the second pitch coil layer of the present disclosure. Furthermore, of the four coil layers S51, S52, S55, and S56, the first coil layer S51 and the second coil layer S52 correspond to the first pitch coil layer of the present disclosure, and the fifth coil layer S55 and the sixth coil layer S56 correspond to the second pitch coil layer of the present disclosure.

[0057] H. Eighth embodiment: The coil assembly 107 of the eighth embodiment shown in FIG. 17 includes a first coil layer S61, a second coil layer S62, a third coil layer 63, and a fourth coil layer 64 stacked on top of each other. The configurations of the first coil layer S61 to the fourth coil layer S64 are the same as those of the first coil layer S1 to the fourth coil layer S4 of the first embodiment. However, the coil assembly 107 differs from the coil assembly 100 of the first embodiment in that the central positions of the strands are different in the two coil layers S61, S62 and the two coil layers S63, S64, but the other configurations are the same. In the coil assembly 107, the same components as those in the coil assembly 100 are denoted by the same reference numerals, and detailed description thereof will be omitted. Note that FIG. 17 shows a cross section at a position similar to the IV-IV cross section in FIG. 1.

[0058] Compared with a central position Ct21 of the wire group in the two coil layers S61, S62, a central position Ct22 of the wire group in the two coil layers S63, S64 is located farther from the central axis Cu3 of each coil layer.

[0059] The coil assembly 107 of the eighth embodiment described above has the same effects as the coil assembly 100 of the first embodiment. In the eighth embodiment, the first coil layer S61 and the second coil layer S62 correspond to the first pitch coil layer of the present disclosure, and the third coil layer S63 and the fourth coil layer S64 correspond to the second pitch coil layer of the present disclosure.

[0060] I. Ninth embodiment: I1. Equipment configuration: The coil assembly 108 of the ninth embodiment shown in Figs. 18 and 19 includes a first coil layer S71, a second coil layer S72, a third coil layer 73, and a fourth coil layer 74 stacked on top of each other. The configurations of the first coil layer S71 to the fourth coil layer S74 are the same as those of the first coil layer S1 to the fourth coil layer S4 of the first embodiment. The coil assembly 108 differs from the coil assembly 100 of the first embodiment in the connection configuration of each coil portion 1 to 8, but the other configurations are the same. In the coil assembly 108, the same components as those of the coil assembly 100 are denoted by the same reference numerals, and detailed description thereof will be omitted. Note that Fig. 18 shows a cross section at a position similar to the IV-IV cross section in Fig. 1.

[0061] 19, in the ninth embodiment, first planar coil 1 and eighth planar coil 8 are connected in series to form coil portion a. Second planar coil 2 and seventh planar coil 7 are connected in series to form coil portion b. Third planar coil 3 and sixth planar coil 6 are connected in series to form coil portion c. Planar coil 4 and fifth planar coil 5 are connected in series to form coil portion d.

[0062] 18, in the ninth embodiment, the pitch between the wires in the first coil layer S71 and the fourth coil layer S74 in the planar direction is a second pitch p2, and the pitch between the wires in the second coil layer S72 and the third coil layer S73 in the planar direction is a first pitch p1.

[0063] In the coil assembly 108 of the ninth embodiment, the coil parts c and d are disposed between the coil parts a and b, so that the distance between the planar coils in the coil parts c and d is smaller than the distance between the planar coils in the coil parts a and b. Therefore, the mutual inductance Mcd can be larger than the mutual inductance Mab. However, as described above, the second pitch p2 between the wires in the first coil layer S71 and the fourth coil layer S74 in the planar direction (the pitch between the wires in the coil parts a and b) is smaller than the first pitch p1 between the wires in the second coil layer S72 and the third coil layer S73 in the planar direction (the pitch between the wires in the coil parts c and d), so that the mutual inductance Mab can be larger than the mutual inductance in a configuration in which the pitch between the wires in the first coil layer S71 and the fourth coil layer 74 is equal to the first pitch p1. Therefore, overall, the difference between the mutual inductances Mab and Mcd can be suppressed, and the difference between the inductance parameters Sa to Sd can be suppressed.

[0064] I2. Working Example: As an example of the coil assembly 108 of the ninth embodiment, a coil assembly 108x shown in Fig. 20 was numerically analyzed, and a coil assembly 901x of Comparative Example 2 shown in Fig. 21 was numerically analyzed. Then, as shown in Fig. 22, mutual inductance, inductance parameters, etc. of these coil assemblies 108x and 901x were numerically analyzed to confirm their effects.

[0065] In the coil assembly 108x of Example 2 shown in FIG. 20, the number of turns of the wire in each of the coil layers S71 to S74 was 6. In each of the coil layers S71 to S74, the central positions Ct11 of the wound wire group were made to coincide with each other. As shown in FIG. 22, in the coil assembly 108x, the first pitch p1 was 1.035 mm. The second pitch p2 was 1.00 mm. In Example 2, the distance from the central axis (axis extending parallel to the Z axis from the central position when viewed in the Z axis direction) Cu4 of each of the coil layers S71 to S74 to the central position Ct11, as well as the thickness and width of the wire, are the same as those of the above-mentioned Examples 1-1 to 1-3, so the description will be omitted. On the other hand, the coil assembly 901x of Comparative Example 2 differs from the coil assembly 108x of Example 2 in that the size of the first pitch p1 is 1.00 mm, which is the same as the second pitch p2, but the other configurations are the same. A current of 1 A was applied to the coil assembly 108x at a frequency of 85 kHz. The magnetic body 110 was made of ferrite. The planar coils constituting each of the coil layers S71 to S74, the magnetic body 110, and the aluminum shield 112x were circular in plan view.

[0066] 22, by making the first pitch p1 in the second coil layer S72 and the third coil layer S73 larger than that in Comparative Example 2, the mutual inductance Mcd in Example 2 could be reduced. This made it possible to reduce the inductance parameters Sc and Sd in Example 2, thereby suppressing the difference between the inductance parameters Sa to Sd. Therefore, in Example 2, the difference between the currents Ia to Id was suppressed compared to Comparative Example 2, and the AC resistance R of the coil assembly was suppressed lower than that in Comparative Example 2.

[0067] The coil assembly 108 of the ninth embodiment described above has the same effects as the coil assembly 100 of the first embodiment. In the ninth embodiment, the first coil layer S71 and the fourth coil layer S74 correspond to the second pitch coil layer in this disclosure. Also, the second coil layer S72 and the third coil layer S73 correspond to the first pitch coil layer in this disclosure.

[0068] J. Other Embodiments: (J1) In the coil assembly 108 of the ninth embodiment, the magnetic body 110 may be omitted. Even in such a configuration, the difference in mutual inductance caused by the difference between the distance between the first coil layer S71 and the fourth coil layer S74 and the distance between the second coil layer S72 and the third coil layer S73 can be at least partially cancelled by the difference in mutual inductance caused by the second pitch p2 in the first coil layer S71 and the fourth coil layer S74 being smaller than the first pitch p1 in the second coil layer S72 and the third coil layer S73. Therefore, even in such a configuration, the same effect as the coil assembly 108 of the ninth embodiment is achieved.

[0069] (J2) In the eighth embodiment, the central positions Ct21 of the wire groups in the first coil layer S61 and the second coil layer S62 coincide with each other. Similarly, the central positions Ct22 of the wire groups in the third coil layer S63 and the fourth coil layer S64 coincide with each other. However, the present disclosure is not limited to this. At least some of the coil layers S61 to S64 may have a configuration in which the central positions of the wire groups are different from those of the other coil layers. Even with such a configuration, the same effects as those of the coil assembly 107 of the eighth embodiment are achieved.

[0070] (J3) The coil assemblies 100 to 108 in each embodiment are merely examples and may be modified in various ways. For example, the planar shape (shape when viewed in the Z-axis direction) of each coil layer S1 to S4, S11 to S12, S21 to S24, S31 to S34, S41 to S44, S51 to S56, S61 to S64, and S71 to S74 may not be rectangular as in each embodiment, and may be, for example, a circle, an ellipse, or a rectangle with rounded corners. The number of coil layers is not limited to 2, 4, or 6, and may be any number of multiple layers. For example, in the first embodiment, the pitches between adjacent wires in the first coil layer S1 and the second coil layer S2 may not be equal to each other. Similarly, the pitches between adjacent wires in the third coil layer S3 and the fourth coil layer S4 may not be equal to each other. In each embodiment, the most distant coil layer farthest from the magnetic body 110 is the second pitch coil layer, but the most distant coil layer may be the first pitch coil layer. Even in such a configuration, by configuring at least one second pitch coil layer to be farther from the magnetic body 110 than at least one first pitch coil layer, it is possible to suppress the difference in impedance between each coil portion, compared to a configuration in which all second pitch coil layers are closer to the magnetic body 110 than all first pitch coil layers.

[0071] The present disclosure is not limited to each embodiment, and can be realized in various configurations without departing from the spirit of the present disclosure. For example, the technical features in the embodiments corresponding to the technical features in the form described in the Summary of the Invention column can be appropriately replaced or combined in order to solve some or all of the above-mentioned problems or to achieve some or all of the above-mentioned effects. Furthermore, if the technical feature is not described as essential in this specification, it can be appropriately deleted. The features of this disclosure are set forth below. [Form 1] A coil assembly (100 to 108), The coil layer includes a plurality of coil layers (S1 to S4, S11 to S12, S21 to S24, S31 to S34, S41 to S44, S51 to S56, S61 to S64, S71 to S74) stacked in a stacking direction, each of which has a plurality of planar coils (1 to 8, 1, 2, 5, 6, 1 to 12, 1a to 4a, 5 to 8) wound in a planar direction (XY) intersecting the stacking direction (Z) and connected in parallel to each other, The plurality of coil layers each include a plurality of coil sections (a to d, a to f) each of which is formed by at least one of the planar coils and which are connected in parallel to each other; The plurality of coil layers include first pitch coil layers (S1, S2, S11, S21, S22, S31, S32, S41, S42, S51, S52, S53, S54, S61, S62, S72, S73) and second pitch coil layers (S3, S4, S12, S23, S24, S33, S34, S43, S44, S53, S54, S55, S56, S63, S64, S71, S74) having different pitches between adjacent wires, The pitch (p1) of the first pitch coil layer is larger than the pitch (p2, p3) of the second pitch coil layer. Coil assembly. [Form 2] In the coil assembly according to the first aspect, Each of the coil portions is configured by connecting the planar coils of two or more of the coil layers in series, A coil assembly, wherein the two or more planar coils constituting each of the coil portions include the planar coil wound radially inward in one of the coil layers and the planar coil wound radially outward in another of the coil layers. [Form 3] A coil assembly according to aspect 1 or 2, Further comprising a magnetic body (110), the plurality of coil layers include one or more of the first pitch coil layers and one or more of the second pitch coil layers; the plurality of coil layers are stacked on the magnetic body, A coil assembly, wherein the plurality of planar coils of at least one of the one or more second pitch coil layers are positioned farther from the magnetic body than the plurality of planar coils of at least one of the first pitch coil layers. [Form 4] In the coil assembly according to aspect 3, A coil assembly, wherein among the plurality of coil layers, at least the farthest coil layer (S4), which is the coil layer farthest from the magnetic body, is the second pitch coil layer, and at least a portion of the other coil layers other than the farthest coil layer are the first pitch coil layer. [Form 5] In the coil assembly according to aspect 4, A coil assembly, wherein, among the plurality of coil layers, the coil layer (S3) connected in series to the most distant coil layer and the most distant coil layer are the second pitch coil layer, and the other coil layers are all the first pitch coil layer. [Form 6] In the coil assembly according to any one of aspects 1 to 5, A coil assembly, wherein the sums of the self-inductances and the mutual inductances of the coil portions are equal to each other. [Explanation of symbols]

[0072] 100-108... Coil assembly, S1, S2, S11, S21, S22, S31, S32, S41, S42, S51, S52, S53, S54, S61, S62, S72, S73... First pitch coil layer, S3, S4, S12, S23, S24, S33, S34, S43, S44, S53, S54, S55, S56, S63, S64, S71, S74... Second pitch coil layer, 1-8, 1, 2, 5, 6, 1-12, 1a-4a, 5-8... Planar coil, p1... First pitch, p2... Second pitch, 110... Magnetic body

Claims

1. A coil assembly (100-108), comprising: A plurality of coil layers (S1-S4, S11-S12, S21-S24, S31-S34, S41-S44, S51-S56, S61-S64, S71-S74) laminated in a lamination direction, each having a plurality of planar coils (1-8, 1, 2, 5, 6, 1-12, 1a-4a, 5-8) wound in a plane direction (X-Y) intersecting the lamination direction (Z) and connected in parallel to each other, The plurality of coil layers are a plurality of coil portions (a-d, a-f) each constituted by at least one of the planar coils and connected in parallel to each other, The plurality of coil layers include a first pitch coil layer (S1, S2, S11, S21, S22, S31, S32, S41, S42, S51, S52, S53, S54, S61, S62, S72, S73) and a second pitch coil layer (S3, S4, S12, S23, S24, S33, S34, S43, S44, S53, S54, S55, S56, S63, S64, S71, S74) in which the pitches between adjacent strands are different from each other, The pitch (p1) of the first pitch coil layer is larger than the pitches (p2, p3) of the second pitch coil layer, In each of the coil layers, around a central portion where no strand is arranged, a group of strands are wound side by side with each other, In each of the coil layers, the central positions (Ct1) in the arrangement direction of the group of strands coincide with each other, Coil assembly.

2. The coil assembly according to claim 1, wherein Each of the coil portions is constituted by connecting in series the planar coils respectively included in two or more of the coil layers, Two or more of the planar coils constituting each of the coil portions include a planar coil wound radially inward in one of the coil layers and a planar coil wound radially outward in another of the coil layers. Coil assembly.

3. The coil assembly according to claim 1, further comprising: A magnetic body (110), The plurality of coil layers include one or more of the first pitch coil layers and one or more of the second pitch coil layers, The plurality of coil layers are laminated on the magnetic body. A coil assembly in which at least one of the plurality of planar coils of at least one of the second pitch coil layers having a pitch of 1 or more is arranged farther from the magnetic body than the plurality of planar coils of at least one of the first pitch coil layers having a pitch of 1 or more.

4. In the coil assembly according to claim 3, Among the plurality of coil layers, the most distant coil layer, which is the coil layer farthest from the magnetic body, is the second pitch coil layer, and at least a part of the other coil layers excluding the most distant coil layer is the first pitch coil layer. Coil assembly.

5. In the coil assembly according to claim 4, Among the plurality of coil layers, the coil layer connected in series to the most distant coil layer and the most distant coil layer are the second pitch coil layers, and the other coil layers are all the first pitch coil layers. Coil assembly.

6. In the coil assembly according to any one of claims 1 to 5, A coil assembly in which the sum of the self-inductance and the mutual inductance between the coil portions is equal to each other.

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