Wireless energy transmission coil device with adjustable inductance value

Abstract

The utility model provides a wireless energy transmission coil device with an adjustable inductance value, and relates to the technical field of wireless power transmission. Comprising a top-layer coil shell, a top-layer coil, a spherical switchable coil connector, a middle-layer coil, a wiring reed, a connecting shaft, a lower-layer shell and the like. Through position switching of the spherical switchable coil connector, the coil shell rotates to drive the wiring reed to slide, and the coil access length is changed to adjust the inductance value. The device can flexibly adjust the resonance state of the system, rapidly obtain the coil with the specific inductance value, solve the problem that the coil needs to be manufactured again to adjust the inductance in the prior art, improve the wireless power transmission efficiency, and is suitable for parameter adjustment and experiment scenes of the wireless power transmission system.

Description

Technical Field

[0001] The utility model relates to the technical field of wireless power transmission, in particular to a wireless energy transmission coil device with adjustable inductance value. Background Art

[0002] At present, when a wireless power transmission system performs energy transmission, it needs to work in a resonant state. If it is detuned, the energy transmission efficiency will decrease. In order to improve the transmission efficiency of the wireless power transmission system, the existing technologies mostly adopt the schemes of variable capacitors and variable resonant inductors, lacking a convenient means to directly change the inductance value of the wireless energy transmission coil. Currently, in the research and experiments on wireless energy transmission technology, to change the inductance value of the coil mainly depends on remaking the coil.

[0003] Therefore, a wireless energy transmission coil with variable inductance value is of great significance for the adjustment of system parameters, especially for the rapid and convenient adjustment of the inductance value in experiments. Summary of the Utility Model

[0004] Aiming at the deficiencies of the prior art, the utility model provides a wireless energy transmission coil device with adjustable inductance value.

[0005] A wireless energy transmission coil device with adjustable inductance value includes: a top coil housing, a top coil, a top coil metal outer ring, a spherical switchable coil connector, a middle coil metal outer ring, a middle coil housing, a middle coil, a wiring reed, a connecting shaft, and a lower housing;

[0006] A first annular groove and a first threaded groove are provided on the lower surface of the top coil housing. The top coil metal outer ring is embedded in the first annular groove, and the top coil is embedded in the first threaded groove. A first card slot is provided at the center of the lower surface of the top coil housing;

[0007] A second annular groove and a second threaded groove are provided on the upper surface of the middle coil housing. The middle coil metal outer ring is embedded in the second annular groove, and the middle coil is embedded in the second threaded groove. A second card slot and a first central hole are provided at the center of the upper surface of the middle coil housing. The connecting shaft is inserted into the first central hole from below the middle coil housing and contacts the spherical switchable coil connector.

[0008] The top coil metal outer ring is in contact with the middle coil metal outer ring. One end of a wire is connected to the middle coil metal outer ring, and the other end of the wire serves as a first wiring port. The lower surface of the middle coil is in contact with the wiring reed. One end of a first tap wire is connected to the wiring reed, and the other end of the first tap wire serves as a second wiring port. The bottom metal contact of the spherical switchable coil connector is in contact with the connecting shaft. One end of a second tap wire is connected to the connecting shaft, and the other end of the second tap wire serves as a third wiring port.

[0009] The upper surface of the lower housing is provided with a second central hole and a limiting groove. The second central hole is located at the center of the circle, and the limiting groove passes through the second central hole. The limiting groove is a radial groove and has the same length as the diameter of the lower housing.

[0010] The limiting groove is connected to the wiring spring piece, enabling the wiring spring piece to slide in the limiting groove towards or away from the center of the circle.

[0011] The first central hole of the middle coil housing and the second central hole of the lower housing are respectively connected to both ends of the connecting shaft, and the top coil housing rotates around the connecting shaft with respect to the lower housing.

[0012] The spherical switchable coil connector includes a sphere, 4 metal connectors, and 4 grooves; metal contacts are provided at the bottom of the sphere. The metal connectors are in the shape of a cuboid. The 4 metal connectors are connected inside the sphere and are connected to the bottom metal contacts. The 4 grooves are provided on the surface of the sphere.

[0013] Specifically, for the spherical switchable coil connector, taking the center point of the lower surface of the top coil housing as the origin, the direction from the origin to the inner connection of the top coil as the positive direction of the Y-axis, the direction obtained by rotating 90 degrees counterclockwise in the lower surface of the top coil housing perpendicular to the positive direction of the Y-axis as the positive direction of the X-axis, and the direction perpendicular to the lower surface of the top coil housing and upward as the positive direction of the Z-axis; the sphere satisfies x² + y² + z² = r²; the coordinates of the 4 grooves satisfy (y - k)² + (z - k)² < r1², (y + k)² + (z - k)² < r1², (x - k)² + (z - k)² < r1², (x + k)² + (z - k)² < r1², where: X, Y, and Z are coordinate axes, the center coordinates of the sphere are the origin (0, 0, 0), (x, y, z) is a point in the coordinate axes, r is the radius, k is a constant and k < r, r1 is the radius of the 4 grooves of the spherical switchable coil connector and r1 < r; the 4 metal connectors are the first cuboid to the fourth cuboid respectively; let W be the thickness of the cuboid, H be the width of the cuboid, and L be the length of the cuboid, and satisfy W < L = H, r² = L² + H²;

[0014] The vertex coordinates of the first cuboid: (W, 0, 0), (-W, 0, 0), (W, L, 0), (-W, L, 0), (W, 0, H), (-W, 0, H), (W, L, H), (-W, L, H);

[0015] The vertex coordinates of the second cuboid: (W, 0, 0), (-W, 0, 0), (W, -L, 0), (-W, -L, 0), (W, 0, H), (-W, 0, H), (W, -L, H), (-W, -L, H);

[0016] Vertex coordinates of the third cuboid: (0, W, 0), (0, -W, 0), (L, W, 0), (L, -W, 0), (0, W, -H), (0, -W, -H), (L, W, -H), (L, -W, -H);

[0017] Vertex coordinates of the fourth cuboid: (0, W, 0), (0, -W, 0), (-L, W, 0), (-L, -W, 0), (0, W, -H), (0, -W, -H), (-L, W, -H), (-L, -W, -H).

[0018] The spherical switchable coil connector is inserted into the first card slot from below the top - layer coil housing at two angles of position one or position two. The outer terminal of the top - layer coil is connected to the top - layer coil metal outer ring. When the spherical switchable coil connector is in position one, the inner terminal of the top - layer coil is connected to the first cuboid or the second cuboid. When the spherical switchable coil connector is in position two, the inner terminal of the top - layer coil is connected to the third cuboid or the fourth cuboid;

[0019] The spherical switchable coil connector is inserted into the second card slot from above the middle - layer coil housing at two angles of position one or position two. The outer terminal of the middle - layer coil is connected to the middle - layer coil metal outer ring. When the spherical switchable coil connector is in position two, the inner terminal of the middle - layer coil is connected to the first cuboid or the second cuboid. When the spherical switchable coil connector is in position one, the inner terminal of the middle - layer coil is connected to the third cuboid or the fourth cuboid;

[0020] The specific position one is: the center coordinates of the spherical switchable coil connector are the origin (0, 0, 0), and the line connecting the center points of the first cuboid and the second cuboid is parallel to the Y - axis. The specific position two is: the center coordinates of the spherical switchable coil connector are the origin (0, 0, 0), and the line connecting the centers of the first cuboid and the second cuboid is parallel to the X - axis.

[0021] The top - layer coil and the middle - layer coil are wound in a helix with Litz wire to form a planar spiral - wound coil. In the planar spiral - wound coil, the wire head near the center of the coil is the inner terminal, and the wire head near the edge of the coil is the outer terminal.

[0022] The beneficial effects produced by adopting the above technical solution are as follows:

[0023] The utility model provides a wireless energy - transfer coil device with adjustable inductance value, having the following beneficial effects:

[0024] Beneficial effect 1: The device of the present utility model can make the resonance state of magnetic coupling wireless power transmission adjustable. In wireless power transmission, the system operates most efficiently in the inductance-capacitance resonance state. However, due to factors such as parasitic parameters in the circuit, component tolerances, and coil offset, the system may become detuned. Therefore, resonance adjustment is required. The present utility model can change the inductance value of the coil itself and can flexibly adjust the coil inductance to make it resonate when the system is detuned.

[0025] Beneficial effect 2: The device of the present utility model provides a platform for quickly obtaining a wireless charging coil with a specific inductance value. In the experiment of wireless charging devices, the production of coils with specific inductance values is time-consuming and laborious, and as the theoretical parameters are corrected, the inductance values of the coils required for the experiment often change. With the present utility model, the coil with the required inductance value can be quickly obtained, saving the time of winding multiple coils. Description of the Drawings

[0026] Figure 1 It is a schematic structural view of the wireless energy transmission coil device in the embodiment of the present utility model from top to bottom perspective;

[0027] Figure 2 It is a schematic structural view of the wireless energy transmission coil device in the embodiment of the present utility model from bottom to top perspective;

[0028] Figure 3 It is a schematic structural view of the lower layer housing in the embodiment of the present utility model;

[0029] Among them, (a) - front view of the lower layer housing, (b) - top view of the lower layer housing, (c) - side view of the lower layer housing;

[0030] Figure 4 It is a schematic structural view of the spherical switchable coil connector in the embodiment of the present utility model;

[0031] Among them, (a) - top view, (b) - front view, (c) - perspective view;

[0032] In the figure, 1 - top coil housing, 2 - top coil, 3 - top coil metal outer ring, 4 - spherical switchable coil connector, 5 - middle coil metal outer ring, 6 - middle coil housing, 7 - middle coil, 8 - connection spring piece, 9 - connection shaft, 10 - lower layer housing. Detailed Embodiments

[0033] The following combines the drawings and embodiments to further describe in detail the specific embodiments of the present utility model. The following embodiments are used to illustrate the present utility model but are not used to limit the scope of the present utility model.

[0034] A wireless energy transmission coil device with adjustable inductance value, and its schematic structural views from top to bottom perspective and from bottom to top perspective are respectively asFigure 1 , Figure 2 As shown in the figure, it includes: a top coil housing 1, a top coil 2, a top coil metal outer ring 3, a spherical switchable coil connector 4, a middle coil metal outer ring 5, a middle coil housing 6, a middle coil 7, a connection spring piece 8, a connecting shaft 9, and a lower housing 10;

[0035] A first annular groove and a first threaded groove are provided on the lower surface of the top coil housing 1. The top coil metal outer ring 3 is embedded in the first annular groove, and the top coil 2 is embedded in the first threaded groove. A first card slot is provided at the center of the lower surface of the top coil housing 1;

[0036] A second annular groove and a second threaded groove are provided on the upper surface of the middle coil housing 6. The middle coil metal outer ring 5 is embedded in the second annular groove, and the middle coil 7 is embedded in the second threaded groove. A second card slot and a first central hole are provided at the center of the upper surface of the middle coil housing 6. The connecting shaft 9 is inserted into the first central hole from below the middle coil housing and contacts the spherical switchable coil connector 4.

[0037] The top coil metal outer ring 3 is in contact with the middle coil metal outer ring 5. One end of a wire is connected to the middle coil metal outer ring 5, and the other end of the wire serves as a first wiring port. The lower surface of the middle coil 7 is in contact with the connection spring piece 8. One end of a first tap wire is connected to the connection spring piece 8, and the other end of the first tap wire serves as a second wiring port. The bottom metal contact of the spherical switchable coil connector 4 is in contact with the connecting shaft 9. One end of a second tap wire is connected to the connecting shaft 9, and the other end of the second tap wire serves as a third wiring port.

[0038] As Figure 3 shown, the front view, top view, and side view of the lower housing are respectively as shown in Figure 3 figures (a), (b), and (c). A second central hole and a limiting groove are provided on the upper surface of the lower housing 10. The second central hole is located at the center of the circle. The limiting groove passes through the second central hole. The limiting groove is a radial groove and is as long as the diameter of the lower housing;

[0039] The limiting groove is connected to the connection spring piece, enabling the connection spring piece to slide in the limiting groove towards or away from the center of the circle.

[0040] The first central hole of the middle coil housing and the second central hole of the lower housing are respectively connected to both ends of the connecting shaft. The top coil housing rotates with the connecting shaft as the axis between the top coil housing and the lower housing.

[0041] The spherical switchable coil connector includes a sphere, 4 metal connectors, and 4 grooves. As Figure 4 shown, the top view, front view, and oblique view of the spherical switchable coil connector are respectively as shown in Figure 4As shown in (a), (b), and (c); a metal contact is provided at the bottom of the sphere. The metal connector is in the shape of a cuboid. Four metal connectors are connected inside the sphere and are connected to the bottom metal contact. Four grooves are provided on the surface of the sphere.

[0042] Specifically, for the spherical switchable coil connector, taking the center point of the lower surface of the top-layer coil housing as the origin, the direction from the origin to the inner connection of the top-layer coil as the positive direction of the Y-axis, the direction obtained by rotating 90 degrees counterclockwise in the plane of the lower surface of the top-layer coil housing and perpendicular to the positive direction of the Y-axis as the positive direction of the X-axis, and the direction perpendicular to the lower surface of the top-layer coil housing and upward as the positive direction of the Z-axis; the sphere satisfies x² + y² + z² = r²; the coordinates of the four grooves satisfy (y - k)² + (z - k)² < r1², (y + k)² + (z - k)² < r1², (x - k)² + (z - k)² < r1², (x + k)² + (z - k)² < r1², where: X, Y, Z are the coordinate axes, the center coordinate of the sphere is the origin (0, 0, 0), (x, y, z) is a point in the coordinate axes, r is the radius, k is a constant, and k < r, r1 is the radius of the four grooves of the spherical switchable coil connector and r1 < r; the four metal connectors are respectively the first cuboid to the fourth cuboid; let W be the thickness of the cuboid, H be the width of the cuboid, and L be the length of the cuboid, and satisfy W < L = H, r² = L² + H²;

[0043] Vertex coordinates of the first cuboid: (W, 0, 0), (-W, 0, 0), (W, L, 0), (-W, L, 0), (W, 0, H), (-W, 0, H), (W, L, H), (-W, L, H);

[0044] Vertex coordinates of the second cuboid: (W, 0, 0), (-W, 0, 0), (W, -L, 0), (-W, -L, 0), (W, 0, H), (-W, 0, H), (W, -L, H), (-W, -L, H);

[0045] Vertex coordinates of the third cuboid: (0, W, 0), (0, -W, 0), (L, W, 0), (L, -W, 0), (0, W, -H), (0, -W, -H), (L, W, -H), (L, -W, -H);

[0046] Vertex coordinates of the fourth cuboid: (0, W, 0), (0, -W, 0), (-L, W, 0), (-L, -W, 0), (0, W, -H), (0, -W, -H), (-L, W, -H), (-L, -W, -H).

[0047] The spherical switchable coil connector is inserted into the first card slot from below the top coil housing at two angles, namely position one or position two. The outer terminal of the top coil is connected to the outer metal ring of the top coil. When the spherical switchable coil connector is in position one, the inner terminal of the top coil is connected to the first cuboid or the second cuboid. When the spherical switchable coil connector is in position two, the inner terminal of the top coil is connected to the third cuboid or the fourth cuboid.

[0048] The spherical switchable coil connector is inserted into the second card slot from above the middle coil housing at two angles, namely position one or position two. The outer terminal of the middle coil is connected to the outer metal ring of the middle coil. When the spherical switchable coil connector is in position two, the inner terminal of the middle coil is connected to the first cuboid or the second cuboid. When the spherical switchable coil connector is in position one, the inner terminal of the middle coil is connected to the third cuboid or the fourth cuboid. The specific position one is that the center coordinates of the sphere of the spherical switchable coil connector are the origin (0, 0, 0), and the line connecting the center points of the first cuboid and the second cuboid is parallel to the Y-axis. The specific position two is that the center coordinates of the sphere of the spherical switchable coil connector are the origin (0, 0, 0), and the line connecting the centers of the first cuboid and the second cuboid is parallel to the X-axis.

[0049] The top coil and the middle coil are wound with Litz wire in a spiral manner to form a planar spiral-wound coil. In the planar spiral-wound coil, the wire end near the center of the coil is the inner terminal, and the wire end near the edge of the coil is the outer terminal.

[0050] In this embodiment, taking the example of obtaining a 5 μH planar coil. Adjust the LCR meter to the inductance measurement range, connect the probe to connection port 1 and connection port 2 of the wireless energy transfer coil device with adjustable inductance value, and set the spherical switchable coil connector to position 2. By rotating the top coil housing and the middle coil housing, the middle coil rotates accordingly; the wiring reed cannot rotate due to the limitation of the lower housing limit groove, but it will slide in two directions towards and away from the center of the circle as the planar coil rotates; since the position where the middle coil contacts the wiring reed changes during rotation, the length of the planar coil between the two connection terminals changes, thereby changing its inductance value. Read the inductance value indication on the LCR meter and stop when the indication is 5 μH after rotating to a certain position. If the top coil housing and the middle coil housing are rotated to the limit and still do not reach 5 μH, set the spherical switchable coil connector to position 1, connect the probe to connection port 3 and connection port 2 of the wireless energy transfer coil device with adjustable inductance value, and rotate the top coil housing and the middle coil housing again. The middle coil rotates accordingly; the wiring reed cannot rotate due to the limitation of the lower housing limit groove, but it will slide in two directions towards and away from the center of the circle as the planar coil rotates; since the position where the middle coil contacts the wiring reed changes during rotation, the length of the planar coil between the two connection terminals changes, thereby changing its inductance value. Read the inductance value indication on the LCR meter and stop when the indication is 5 μH after rotating to a certain position.

[0051] In this embodiment, taking the example of adjusting the resonance frequency of the LC series compensation wireless charging transmitter to f. Adjust the impedance analyzer to the range for measuring the impedance amplitude Z and phase θ. Connect connection port 2 of the wireless energy transfer coil device with adjustable inductance value to a capacitor to form a series structure, connect one probe to the other end of the capacitor, and connect the other probe to connection port 1 of the wireless energy transfer coil device. By rotating the top coil housing and the middle coil housing, the middle coil rotates accordingly; the wiring reed cannot rotate due to the limitation of the lower housing limit groove, but it will slide in two directions towards and away from the center of the circle as the planar coil rotates; since the position where the planar coil contacts the wiring reed changes during rotation, the length of the planar coil between the two connection terminals changes, thereby changing its inductance value. Observe on the impedance analyzer whether the impedance amplitude Z is a minimum value at the target frequency f. Stop when the impedance amplitude Z is a minimum value at the frequency f after rotating to a certain position.

[0052] The above description is only a preferred embodiment of the present disclosure and an explanation of the applied technical principles. Those skilled in the art should understand that the scope of the utility model involved in the embodiments of the present disclosure is not limited to the technical solutions formed by the specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the above utility model concept. For example, the technical solutions formed by mutually replacing the above features with the technical features (but not limited to) disclosed in the embodiments of the present disclosure that have similar functions.

Claims

1. A wireless energy transfer coil device with adjustable inductance value, characterized in that, It includes a top coil housing, a top coil, a top coil metal outer ring, a spherical switchable coil connector, a middle coil metal outer ring, a middle coil housing, a middle coil, a connection spring piece, a connection shaft, and a lower housing; The lower surface of the top coil housing is provided with a first annular groove and a first threaded groove. The top coil metal outer ring is embedded in the first annular groove, and the top coil is embedded in the first threaded groove. A first clamping groove is provided at the center of the lower surface of the top coil housing; The upper surface of the middle coil housing is provided with a second annular groove and a second threaded groove. The middle coil metal outer ring is embedded in the second annular groove, and the middle coil is embedded in the second threaded groove. A second clamping groove and a first central hole are provided at the center of the upper surface of the middle coil housing. The connection shaft is inserted into the first central hole from below the middle coil housing and contacts the spherical switchable coil connector; The upper surface of the lower housing is provided with a second central hole and a limiting groove. The second central hole is located at the center of the circle, and the limiting groove passes through the second central hole. The limiting groove is a radial groove and is as long as the diameter of the lower housing; The top coil metal outer ring is in contact with the middle coil metal outer ring. One end of a wire is connected to the middle coil metal outer ring, and the other end of the wire serves as a first wiring port. The lower surface of the middle coil is in contact with the connection spring piece. One end of a first tap wire is connected to the connection spring piece, and the other end of the first tap wire serves as a second wiring port. The bottom metal contact of the spherical switchable coil connector is in contact with the connection shaft. One end of a second tap wire is connected to the connection shaft, and the other end of the second tap wire serves as a third wiring port; The spherical switchable coil connector includes a sphere, 4 metal connectors, and 4 grooves; A metal contact is provided at the bottom of the sphere. The metal connectors are in a cuboid structure. The 4 metal connectors are connected inside the sphere and are connected to the bottom metal contact. The 4 grooves are provided on the surface of the sphere.

2. The wireless energy transfer coil device with adjustable inductance value according to claim 1, wherein The limiting groove is connected to the connection spring piece, enabling the connection spring piece to slide towards or away from the center of the circle in the limiting groove.

3. The wireless energy transfer coil device with adjustable inductance value according to claim 1, characterized in that, The first central hole of the middle coil housing and the second central hole of the lower housing are respectively connected to both ends of the connection shaft. The top coil housing rotates with the connection shaft as the axis between the top coil housing and the lower housing.

4. An adjustable inductance value wireless energy transmission coil device according to claim 1, characterized in that, Specifically, for the spherical switchable coil connector, taking the center point of the lower surface of the top-layer coil housing as the origin, the direction from the origin to the inner connection of the top-layer coil as the positive direction of the Y-axis, the direction obtained by rotating 90 degrees counterclockwise in the lower surface of the top-layer coil housing perpendicular to the positive direction of the Y-axis as the positive direction of the X-axis, and the direction perpendicular to the lower surface of the top-layer coil housing upward as the positive direction of the Z-axis; the sphere satisfies x² + y² + z² = r²; the coordinates of the 4 grooves satisfy (y - k)² + (z - k)² < r1², (y + k)² + (z - k)² < r1², (x - k)² + (z - k)² < r1², (x + k)² + (z - k)² < r1², where: X, Y, and Z are coordinate axes, the center coordinates of the sphere are the origin (0, 0, 0), (x, y, z) is a point in the coordinate axes, r is the radius, k is a constant, and k < r, r1 is the radius of the 4 grooves of the spherical switchable coil connector and r1 < r; the 4 metal connectors are the first cuboid to the fourth cuboid respectively; let W be the thickness of the cuboid, H be the width of the cuboid, and L be the length of the cuboid, and satisfy W < L = H, r² = L² + H²; Vertex coordinates of the first cuboid: (W, 0, 0), (-W, 0, 0), (W, L, 0), (-W, L, 0), (W, 0, H), (-W, 0, H), (W, L, H), (-W, L, H); Vertex coordinates of the second cuboid: (W, 0, 0), (-W, 0, 0), (W, -L, 0), (-W, -L, 0), (W, 0, H), (-W, 0, H), (W, -L, H), (-W, -L, H); Vertex coordinates of the third cuboid: (0, W, 0), (0, -W, 0), (L, W, 0), (L, -W, 0), (0, W, -H), (0, -W, -H), (L, W, -H), (L, -W, -H); Vertex coordinates of the fourth cuboid: (0, W, 0), (0, -W, 0), (-L, W, 0), (-L, -W, 0), (0, W, -H), (0, -W, -H), (-L, W, -H), (-L, -W, -H).

5. The wireless energy transfer coil device with adjustable inductance value according to claim 4, wherein The spherical switchable coil connector is inserted into the first card slot from below the top-layer coil housing at two angles of position one or position two, and the outer connection terminal of the top-layer coil is connected to the top-layer coil metal outer ring; when the spherical switchable coil connector is in position one, the inner connection terminal of the top-layer coil is connected to the first cuboid or the second cuboid, and when the spherical switchable coil connector is in position two, the inner connection terminal of the top-layer coil is connected to the third cuboid or the fourth cuboid; The spherical switchable coil connector is inserted into the second card slot from above the middle coil housing at two angles, namely position one or position two. The outer connection head of the middle coil is connected to the middle coil metal outer ring. When the spherical switchable coil connector is in position two, the inner connection head of the middle coil is connected to the first cuboid or the second cuboid. When the spherical switchable coil connector is in position one, the inner connection head of the middle coil is connected to the third cuboid or the fourth cuboid. Specifically, for position one: the center coordinates of the sphere of the spherical switchable coil connector are the origin (0, 0, 0), and the line connecting the center points of the first cuboid and the second cuboid is parallel to the Y-axis. Specifically, for position two: the center coordinates of the sphere of the spherical switchable coil connector are the origin (0, 0, 0), and the line connecting the centers of the first cuboid and the second cuboid is parallel to the X-axis. The top coil and the middle coil are wound with Litz wire in a spiral manner to form a planar spiral wound coil. In the planar spiral wound coil, the wire head near the center of the coil is the inner connection head, and the wire head near the edge of the coil is the outer connection head.

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