KR102204236B1 - Magnetic pad, prepration method thereof and wireless charging device comprising same - Google Patents

Abstract

The magnetic pad according to the embodiment may increase a transmission rate of an electromagnetic signal generated from the conductive wire by a guide member provided between conductive wires wound in a flat coil shape. Accordingly, the wireless charging device including the magnetic pad may be usefully used in an electric vehicle that requires a large amount of power transmission between a transmitter and a receiver.

Description

Magnetic pad, a manufacturing method thereof, and a wireless charging device including the same TECHNICAL FIELD [MAGNETIC PAD, PREPRATION METHOD THEREOF AND WIRELESS CHARGING DEVICE COMPRISING SAME}

The embodiment relates to a magnetic pad, a method of manufacturing the same, and a wireless charging device including the same. More specifically, the embodiment relates to a magnetic pad having high magnetic properties that can be used in an electric vehicle (EV), a method of manufacturing the same, and a wireless charging device including the same.

Today, the field of information and communication is developing at a very fast pace, and various technologies in which electricity, electronics, communication, semiconductors, etc. are comprehensively combined are continuously being developed. In addition, as electronic devices become more mobile, researches on wireless communication and wireless power transmission technologies are being actively conducted in the communication field. In particular, research on a method of wirelessly transmitting power to electronic devices and the like is actively being conducted.

The wireless power transmission is performed wirelessly through space using an electromagnetic field resonance structure such as inductive coupling, capacitive coupling, or an antenna without physical contact between a transmitter supplying power and a receiver receiving power. Is to transmit. The wireless power transmission is suitable for portable communication devices, electric vehicles, etc. that require a large-capacity battery, and since the contact point is not exposed, there is little risk of a short circuit, and a wired-type charging failure phenomenon can be prevented.

Meanwhile, as interest in electric vehicles has increased rapidly in recent years, interest in establishing a charging infrastructure is increasing. Various charging methods such as battery replacement, rapid charging device, and wireless charging device have already appeared, including charging electric vehicles using household chargers, and new charging business business models have also begun to appear (see Korean Patent Laid-Open No. 2011-0042403). In addition, in Europe, electric vehicles and charging stations in test operation have begun to stand out, and in Japan, electric vehicles and charging stations are being piloted, led by automobile manufacturers and power companies.

Korean Patent Application Publication No. 2011-0042403

The wireless charging system is composed of a transmitter 10 and a receiver 20 with reference to FIG. 4, and each of them includes a magnetic pad in which a conductive coil and a magnetic material are combined. Accordingly, the charging efficiency of the wireless charging system may be determined according to magnetic characteristics of magnetic pads provided in the transmitter and the receiver.

Conventionally, in order to increase the magnetic properties of a magnetic pad, a thick magnetic material or a method of increasing the number of windings of a conductive coil has been used. However, such a conventional method has a problem of increasing the manufacturing cost by using a large amount of magnetic material and a conductive coil, and the magnetic properties of the magnetic pad have not been sufficiently increased.

Therefore, through the following implementation examples, it is intended to provide a magnetic pad having improved magnetic properties effectively without thickening a magnetic material or increasing the number of windings of a coil, a method of manufacturing the same, and a wireless charging device including the same.

According to one embodiment, a conductive wire wound in a flat coil shape; And a guide member disposed between the conductive wires, the guide member having magnetism, and a magnetic pad is provided.

According to another embodiment, there is provided a method of manufacturing a magnetic pad comprising the step of winding a conductive wire together with a guide member in a planar coil shape, wherein the guide member has magnetism.

According to another embodiment, a wireless charging device including the magnetic pad is provided.

The magnetic pad according to the embodiment may increase a transmission rate of an electromagnetic signal by focusing a magnetic field generated from the conductive wire by means of a guide member provided between conductive wires wound in a planar coil shape.

In particular, the magnetic pad is manufactured by a simple method of winding a conductive wire together with a guide member in the form of a flat coil without thickening the magnetic material or increasing the number of windings of the coil, thereby exhibiting high magnetic properties.

Accordingly, the wireless charging device including the magnetic pad may be usefully used in an electric vehicle that requires a large amount of power transmission between a transmitter and a receiver.

1A is a plan view illustrating a magnetic pad according to an embodiment.
1B is a cross-sectional view of the magnetic pad of FIG. 1A taken along line A-A'.
FIG. 2 is an enlarged view of part B in the cross-sectional view of FIG. 1B.
3 illustrates a method of manufacturing a magnetic pad according to an embodiment.
4 shows a transmitter and a receiver of a conventional wireless charging device.

In the description of the following embodiments, in the case where each sheet, layer, film, etc. is described as being formed in "on" or "under" of each sheet, layer, film, etc., "upper ( "on)" and "under" include both "directly" or "indirectly" formed through other elements.

In addition, standards for the top/bottom of each component will be described based on the drawings. The size of each component in the drawings may be exaggerated for the sake of explanation, and does not mean a size that is actually applied.

In addition, all numerical ranges representing physical property values, dimensions, and the like of the constituents described in the present specification are to be understood as being modified by the term "about" in all cases unless otherwise specified.

[Magnetic pad]

1A and 1B, a magnetic pad 100 according to an exemplary embodiment includes a conductive wire 110 wound in a flat coil shape; And a guide member 120 disposed between the conductive wires, and the guide member 120 has magnetism.

In addition, the magnetic pad 100 may further include a base substrate 130.

Hereinafter, each component of the magnetic pad will be described in detail.

Conductive wire

The conductive wire includes a conductive material. For example, the conductive wire may include a conductive metal. Specifically, the conductive wire may include at least one metal selected from the group consisting of copper, nickel, gold, silver, zinc, and tin.

In addition, the conductive wire may have an insulating sheath. For example, the insulating outer shell may include an insulating polymer resin. Specifically, the insulating outer shell may include polyvinyl chloride (PVC) resin, polyethylene (PE) resin, Teflon resin, silicone resin, polyurethane resin, and the like.

2, the diameter (d) of the conductive wire 110 may be, for example, 1 mm to 10 mm, specifically 1 mm to 7 mm, 1 mm to 5 mm, 3 mm to 7 mm, Or 5 mm to 10 mm.

The conductive wire is wound in the form of a flat coil. Specifically, the planar coil may be a planar spiral coil. In this case, the planar shape of the planar coil may be an oval, a polygon, or a polygon with rounded corners, but is not particularly limited.

The outer diameter of the flat coil may be 5 cm to 100 cm, 10 cm to 50 cm, 10 cm to 30 cm, 20 cm to 80 cm, or 50 cm to 100 cm. As a specific example, the planar coil may have an outer diameter of 10 cm to 50 cm.

In addition, the inner diameter of the flat coil may be 0.5 cm to 30 cm, 1 cm to 20 cm, or 2 cm to 15 cm.

The number of windings of the flat coil may be 5 to 50 times, 10 to 30 times, 5 to 30 times, 15 to 50 times, or 20 to 50 times. As a specific example, the planar coil may be formed by winding the conductive wire 10 to 30 times.

In addition, the spacing between the conductive wires in the planar coil shape may be 0.1 cm to 1 cm, 0.1 cm to 0.5 cm, or 0.5 cm to 1 cm.

When it is within the above-described preferred dimensions and specifications, it may be suitable for a field requiring large-capacity power transmission such as an electric vehicle.

Guide member

A guide member is disposed between the conductive wires in the planar coil. Specifically, the guide member may form a wall between the conductive wires in the planar coil. Since the guide member has magnetism, it is possible to increase the inductance of the planar coil by focusing the magnetic field generated from the conductive wire and improve the coupling coefficient with the counter coil.

2, the width (w) of the guide member 120 may be, for example, 1 mm to 30 mm, specifically 1 mm to 20 mm, 1 mm to 10 mm, 1 mm to 5 mm, 3 mm to 7 mm, or may be 5 mm to 10 mm

In addition, the thickness (t) of the guide member 120 may be, for example, 0.01 mm to 4 mm, 0.01 mm to 2.5 mm, 0.05 mm to 2 mm, or 0.05 mm to 1 mm.

As a specific example, the guide member may have a width of 1 mm to 10 mm and a thickness of 0.05 mm to 2 mm.

The width of the guide member may be equal to or greater than the diameter of the conductive wire.

2, the difference between the width (w) of the guide member and the diameter (d) of the conductive wire may be 0 mm to 5 mm, or 1 mm to 5 mm.

The guide member is magnetic and is not particularly limited to the material thereof. For example, the guide member may include a ferritic material, an Fe-based nanocrystal material, and an Fe-based amorphous material.

As an example, the guide member may be a flexible magnetic sheet, and accordingly, physical properties such as magnetism may not be deteriorated even when wound in a flat coil shape.

The flexible magnetic sheet may be erected between conductive wires in the planar coil to form a wall.

Flexible magnetic sheet

Specifically, the flexible magnetic sheet may be a non-sintered cured sheet having flexibility. That is, the flexible magnetic sheet may include a binder resin and magnetic particles dispersed in the binder resin.

Magnetic particles included in the flexible magnetic sheet may include oxide magnetic particles such as ferrite (Ni-Zn-based, Mg-Zn-based, Mn-Zn-based ferrite, etc.); Metallic magnetic particles such as permalloy, sanddust, Fe-Si-Cr alloy and Fe-Si-nanocrystal; Or it may be a mixture of these particles. For example, the magnetic particles may be sandblast particles having an Fe-Si-Al alloy composition.

As a specific example, the magnetic particles may have a composition represented by Formula 1 below.

[Formula 1]

Fe _1-abc Si _a X _b Y _c

In the above formula, X is Al, Cr, Ni, Cu, or a combination thereof; Y is Mn, B, Co, Mo, or a combination thereof; 0.01 ≤ a ≤ 0.2, 0.01 ≤ b ≤ 0.1, and 0 ≤ c ≤ 0.05.

The magnetic particles may have a particle diameter of about 3 nm to about 1 mm. More specifically, the particle diameter of the magnetic particles may be about 1 µm to 300 µm, about 1 µm to 50 µm, or about 1 µm to 10 µm.

The magnetic particles may have a shape such as a spherical shape, a flake shape, and a rod shape. Preferably, the magnetic particles may have a flake shape, and accordingly, the aspect ratio (ratio of the long diameter to the short diameter) of the particles is large, so that the magnetic properties can be more effectively exhibited. Specifically, the aspect ratio of the magnetic particles may be 1.1:1 to 50:1, 1.1:1 to 10:1, or 2:1 to 5:1.

Particularly, the magnetic particles in the flake shape may be evenly aligned by thermal pressure performed during manufacture of the antenna element.

As a result, referring to FIG. 2, the angle (a) between the long axis of the magnetic particle 121 and the plane direction of the planar coil is 60° to 120°, 70° to 110°, 75° to 105°, or It may be 80˚ to 100˚ (in FIG. 2, assuming that the plane direction of the planar coil and the plane direction of the base substrate are the same, it is expressed as the angle between the long axis of the magnetic particles and the plane direction of the base substrate). In addition, an average angle between the long axis of the magnetic particles and the plane direction of the planar coil may be 75° to 105°, 80° to 100°, or 85° to 95°. Here, the average angle means an average value of angles measured for a plurality of arbitrary magnetic particles.

As a specific example, the magnetic particles may have an aspect ratio of 1.1:1 to 50:1, and in this case, an average angle between a long axis of the magnetic particles and a plane direction of the planar coil may be 75° to 105°.

When within the preferred range, the long axis of the magnetic particles 121 is aligned substantially perpendicular to the surface direction of the magnetic pad, so that the electromagnetic signal 300 generated from the conductive wire 110 wound in the form of a flat coil is transmitted to the magnetic field. It can be transmitted more effectively to the terminal facing the pad.

A curable resin may be used as the binder resin included in the flexible magnetic sheet. Specifically, the binder resin may include a photocurable resin, a thermosetting resin and/or a high heat-resistant thermoplastic resin, and preferably a thermosetting resin.

As a resin capable of being cured in this way to exhibit adhesiveness, it includes at least one functional group or moiety capable of curing by heat such as a glycidyl group, an isocyanate group, a hydroxy group, a carboxyl group or an amide group; Or one or more functional groups or moieties that can be cured by active energy such as an epoxide group, a cyclic ether group, a sulfide group, an acetal group or a lactone group You can use the resin. Such a functional group or moiety may be, for example, an isocyanate group (-NCO), a hydroxy group (-OH), or a carboxyl group (-COOH).

Specifically, the curable resin may be a polyurethane resin, an acrylic resin, a polyester resin, an isocyanate resin, or an epoxy resin having at least one or more functional groups or portions as described above, but is not limited thereto.

According to an embodiment, the binder resin may include a polyurethane-based resin, an isocyanate-based curing agent, and an epoxy-based resin.

The flexible magnetic sheet may contain magnetic particles in an amount of 50% by weight or more, or 70% by weight or more. For example, the flexible magnetic sheet contains magnetic particles from 50% to 95%, 70% to 95%, 70% to 90%, 75% to 90%, 75% to 95% by weight %, 80% to 95% by weight, or 80% to 90% by weight. In addition, at this time, the magnetic particles may have the composition of Formula 1.

In addition, the flexible magnetic sheet may contain a binder resin in an amount of 5 wt% to 40 wt%, 5 wt% to 20 wt%, 5 wt% to 15 wt%, or 7 wt% to 15 wt%.

In addition, the flexible magnetic sheet is based on the total weight, as the binder resin, 6% to 12% by weight of a polyurethane resin, 0.5% to 2% by weight of an isocyanate-based curing agent and 0.3% to 1.5% by weight of It may contain an epoxy resin.

The thickness of the flexible magnetic sheet may be 0.01 mm to 4 mm, 0.01 mm to 2.5 mm, 0.05 mm to 2 mm, or 0.05 mm to 1 mm. In addition, the flexible magnetic sheet may be a stack of two or more thin magnetic thin-film magnetic sheets, in which case, the thickness of the magnetic thin-film sheet is 10 ㎛ to 3000 ㎛, 10 ㎛ to 500 ㎛, 40 ㎛ to 500 ㎛, 40 ㎛ To 250 µm, 50 µm to 250 µm, 50 µm to 200 µm, or 50 µm to 100 µm.

The flexible magnetic sheet may have excellent magnetic properties in the vicinity of a standard frequency for wireless charging of an electric vehicle (EV). For example, the flexible magnetic sheet may have a magnetic permeability of 100 to 300, or 190 to 250 with respect to an AC current at a frequency of 81 kHz to 90 kHz.

In addition, the flexible magnetic sheet has a magnetic permeability of 100 to 300 for an AC current at a frequency of 3 MHz, a magnetic permeability of 80 to 270 for an AC current at a frequency of 6.78 MHz, and 60 to 250 for an AC current at a frequency of 13.56 MHz. Can have a permeability of Alternatively, the flexible magnetic sheet has a magnetic permeability of 190 to 250 for an AC current of a 3 MHz frequency, a magnetic permeability of 180 to 230 for an AC current of a 6.78 MHz frequency, and 140 to 180 for an AC current of a frequency of 13.56 MHz. Can have a permeability of

In addition, the flexible magnetic sheet may have flexibility so that it can be applied to various devices. For example, the flexible magnetic sheet may not be cut even after bending 100 times, 1,000 times, or 10,000 times in a folding test under 90° and 35 RPM conditions. In addition, the flexible magnetic sheet may have a permeability change of about 10% or less, or about 5% or less after bending 100 times, 1,000 times, or 10,000 times in a bending test under 90° and 35 RPM conditions.

Magnetic sheet made up of multiple magnetic pieces

As another example, the flexible magnetic sheet may include a magnetic layer and a protective layer laminated on at least one surface thereof.

In this case, the magnetic layer may be composed of a plurality of magnetic pieces.

The plurality of magnetic pieces may be formed as 10 or more, 50 or more, or 100 or more per unit area (cm 2) of the flexible magnetic sheet.

Specifically, a plurality of cracks may be formed in the magnetic layer so that the magnetic layer may be divided into a plurality of magnetic pieces.

According to an example, the plurality of cracks formed in the ceramic sheet may be irregular cracks whose directionality and spacing are not uniform at all. According to another example, the plurality of cracks formed in the ceramic sheet may include cracks in at least two directions crossing each other. According to another example, the plurality of cracks formed in the ceramic sheet may include cracks in two directions orthogonal to each other. According to another example, the plurality of cracks formed in the ceramic sheet may be a mixture of fixed and irregular cracks.

The plurality of cracks may have an average spacing between parallel cracks of 5 mm or less, 3 mm or less, 1.5 mm or less, or 800 µm or less.

The material of the magnetic piece is not particularly limited as long as it exhibits magnetism. For example, the material of the magnetic piece may be a magnetic material having brittleness. More specifically, the material of the magnetic piece may be a sintered ferritic material, an Fe-based nanocrystal material, or an Fe-based amorphous material.

The thickness of the magnetic piece may be 0.01 mm to 5 mm, specifically 0.01 mm to 0.3 mm, or 0.03 mm to 0.2 mm.

The protective layer may serve to protect a plurality of magnetic pieces from being scattered from each other.

The protective layer may be a film having flexibility. For example, the protective layer may include a flexible polymer resin, specifically polyethylene terephthalate (PET), polyethylene (PE), polyvinyl chloride (PVC), polycarbonate (PC), polypropylene (PP), Or it may include a mixture of these materials.

The thickness of the protective layer may be 0.002 mm to 0.5 mm, specifically 0.005 mm to 0.05 mm.

Base material

The magnetic pad may further include a base substrate.

1A and 1B, the base substrate 130 may be disposed on the lower surface of the conductive wire 110 wound in the form of a flat coil to support the conductive wire 110 and the guide member 120. .

As an example, the base substrate 130 may have magnetism, and specifically may be a magnetic sheet. That is, the magnetic pad may further include a magnetic sheet disposed on a lower surface of the conductive wire wound in the form of a flat coil. Accordingly, referring to FIG. 2, the electromagnetic signal 300 generated from the conductive wire 110 wound in the form of a flat coil can be more effectively transmitted to the terminal facing the magnetic pad.

The magnetic sheet used as the base substrate may be a polymer type magnetic sheet (PMS), a ferritic sintered sheet, an Fe-based nanocrystal sheet, an Fe-based amorphous sheet, or the like.

The thickness of the magnetic sheet used as the base substrate is not particularly limited, but may be, for example, 0.01 cm to 5 cm, 0.05 cm to 2 cm, or 0.1 cm to 1 cm.

[Manufacturing method of magnetic pad]

3 illustrates a method of manufacturing a magnetic pad according to an embodiment.

Referring to FIG. 3, a method of manufacturing a magnetic pad according to an embodiment includes the step of winding a conductive wire 110 together with a guide member 120 in a flat coil shape, and the guide member 120 is magnetic. Have.

As a specific example, the method of manufacturing the magnetic pad includes the steps of coupling the conductive wire 110 to one surface of the guide member 120 (see FIG. 3A); And winding the guide member 120 coupled with the conductive wire 110 in a flat coil shape (see FIGS. 3B and 3C ).

As a more specific example, the method of manufacturing the magnetic pad includes: bonding the conductive wire to one surface of the flexible magnetic sheet; And erecting the flexible magnetic sheet coupled with the conductive wire and winding the flexible magnetic sheet around the core in the form of a flat coil.

Hereinafter, each step of the manufacturing method will be described in detail.

Preparation of conductive wire and guide member

First, the conductive wire and the guide member are prepared.

At this time, the conductive wire may be coupled to one surface of the guide member. For example, the bonding can be performed using an adhesive.

As the conductive wire, a conductive wire having the configuration as described above may be used.

In addition, when a flexible magnetic sheet is used as the guide member, physical properties such as magnetism may not be deteriorated even when wound in a flat coil shape.

Manufacturing of flexible magnetic sheet

As an example, the flexible magnetic sheet may be a polymer type magnetic sheet, and the polymer type magnetic sheet may be manufactured according to a conventional manufacturing process of a non-sintered polymer type magnetic sheet.

Specifically, the flexible magnetic sheet may be manufactured by a method including mixing magnetic particles and a binder resin, forming a sheet, and drying.

More specifically, the flexible magnetic sheet comprises the steps of: (i) dispersing magnetic particles in a binder resin and a solvent to prepare a slurry; And (ii) forming a sheet using the slurry and then drying it.

According to a preferred example, the method of manufacturing the flexible magnetic sheet includes: (i) preparing a binder resin by mixing a polyurethane-based resin, an isocyanate-based curing agent, and an epoxy-based resin; (ii) preparing a slurry by mixing magnetic particles and an organic solvent with the binder resin; And (iii) forming and drying the slurry into a sheet, wherein the flexible magnetic sheet is based on the total weight of the flexible magnetic sheet, as the binder resin, in an amount of 6% by weight to 12% by weight of polyurethane resin; 0.5% to 2% by weight of an isocyanate-based curing agent; And 0.3% to 1.5% by weight of an epoxy resin.

As a more specific example, magnetic particles are first added to a solvent together with a polyurethane resin, an epoxy resin, and an isocyanate-based curing agent, and then dispersed by a disperser (planetary mixer, homo mixer, no-bead mill, etc.) to about 100 cPs to 10,000 cPs. To prepare a slurry having a viscosity of. Thereafter, the slurry is coated on a carrier film by a comma coater or the like to form a dry magnetic sheet. The dried magnetic sheet may be manufactured as a flexible magnetic sheet by controlling the speed and temperature according to the thickness to be formed, removing the solvent through a dryer, and winding the formed sheet.

When the manufacturing process of the dry magnetic sheet is performed in a roll-to-roll process, a slurry containing magnetic particles and a binder resin is coated on a carrier film with a coater and then dried to prepare a dried magnetic sheet. In this case, the dry magnetic sheet may contain a binder resin in an uncured or partially cured state.

As such, the dried magnetic sheet may be a magnetic sheet in which curing of the binder resin is not completed. Accordingly, by thermally pressing the dry magnetic sheet, a magnetic sheet in which the binder resin is cured can be obtained. The thermal pressing may be performed under a pressure of 1 MPa to 100 MPa and a temperature condition of 100° C. to 300° C. Alternatively, the thermal pressing may be performed under a pressure of 5 MPa to 30 MPa and a temperature condition of 150°C to 200°C. In addition, the thermal pressurization may be performed for about 0.1 to 5 hours.

Manufacturing of a magnetic sheet composed of a plurality of magnetic pieces

As another example, the flexible magnetic sheet may include a magnetic layer and a protective layer laminated on at least one surface thereof, and the magnetic layer may be manufactured in a form consisting of a plurality of magnetic pieces.

At this time, the plurality of magnetic pieces may be obtained by forming cracks in a magnetic thin film having brittleness. Specifically, the flexible magnetic sheet includes: forming a protective layer on one or both surfaces of a magnetic thin film having brittleness; And forming a plurality of cracks in the magnetic thin film by pressing the obtained laminated sheet.

The brittle magnetic thin film may be a ceramic-based magnetic sheet subjected to a sintering treatment, and in this case, it may be manufactured through a conventional ceramic sintering process. For example, ceramic-based magnetic powder and a binder component are mixed and dispersed and cast by tape casting to form a green sheet and then sintered at a high temperature to manufacture it.

In addition, the protective layer may be a flexible film, and in this case, a flexible film that has already been molded may be laminated to a magnetic thin film, or a method of drying after coating a raw resin of the flexible film on a magnetic thin film may be used.

Thereafter, the process of forming a crack in the magnetic thin film may be performed by applying a flexural deformation force to the laminated sheet. Specifically, cracks may be formed in the magnetic thin film by passing the laminated sheet under a pressure roll.

Step of winding in the form of a flat coil

The core 200 may be used for winding in the form of a flat coil.

Specifically, the step of winding in the shape of a flat coil may be to obtain a flat coil by winding the conductive wire 110 and the guide member 120 around the core 200.

The core may have a circular, elliptical, polygonal, or rounded polygonal planar shape. Depending on the shape of the core, the shape of the planar coil wound thereon varies. For example, when the core is cylindrical, a circular planar coil is obtained. In contrast, when the core is in the shape of a square column, a planar coil having a square or a rectangular bottom surface with rounded corners is obtained.

Thereafter, when the planar coil is completed, the core may be removed from the planar coil.

Attachment of base material

A base substrate may be additionally attached to the lower surface of the conductive wire wound in the form of a flat coil. As the base substrate, one having the configuration and characteristics as described above may be used.

Manufacturing method according to another embodiment

According to another embodiment, a magnetic pad may be manufactured by winding a conductive wire in a flat coil shape and then inserting a flexible magnetic sheet between the conductive wires. At this time, the conductive wire and the guide member may not be coupled.

[Wireless charging element]

The wireless charging device according to an embodiment includes a magnetic pad according to the embodiment. For example, the wireless charging element may be a terminal used for wireless charging, that is, a transmitter or a receiver.

In addition to the magnetic pad, the wireless charging device may further include a terminal, a substrate, etc. necessary for power transmission/reception.

The magnetic pad according to the embodiment may increase a transmission rate of an electromagnetic signal by focusing a magnetic field generated from the conductive wire by means of a guide member provided between conductive wires wound in a planar coil shape.

In particular, the magnetic pad is manufactured by a simple method of winding a conductive wire together with a guide member in a planar coil shape without increasing the number of windings of a thick magnetic material or a planar coil, thereby exhibiting high magnetic properties.

Accordingly, the wireless charging device including the magnetic pad may be usefully used in an electric vehicle that requires a large amount of power transmission between a transmitter and a receiver.

[Example]

More specific examples are described below, but are not limited to the scope of these examples.

Manufacturing Example 1

42.8 parts by weight of flake-shaped sanddust powder, 15.4 parts by weight of a polyurethane-based resin dispersion (polyurethane-based resin 25% by weight, 2-butanone 75% by weight), 1.0 parts by weight of an isocyanate-based curing agent dispersion (62% by weight of an isocyanate-based curing agent, n- Butyl acetate 25% by weight, 2-butanone 13% by weight), 0.4 parts by weight of an epoxy resin dispersion (epoxy resin 70% by weight, n-butyl acetate 3% by weight, 2-butanone 15% by weight, toluene 13% by weight) , And 40.5 parts by weight of toluene were mixed in a planetary mixer at a speed of 40 rpm for 2 hours to prepare a magnetic powder slurry.

The magnetic powder slurry prepared above was coated on a carrier film by a comma coater, and dried at a temperature of about 110° C. to form a dry magnetic sheet. The dried magnetic sheet was compression-cured by a hot press process for about 30 minutes at a temperature of about 170° C. at a pressure of about 9 MPa to finally obtain a magnetic sheet having a thickness of 60 μm.

Example 1

The magnetic sheet obtained in Preparation Example 1 was cut into a long sheet having a width of 8 mm. A copper wire having a diameter of 5 mm was attached to one side of the cut magnetic sheet and wound around a cylindrical core four times. As a result, a magnetic sheet and a magnetic pad wound around a copper wire were obtained in the form of a flat spiral coil having an outer diameter of 8 cm and an inner diameter of 4 cm.

Example 2

The magnetic sheets obtained in Preparation Example 1 were stacked to have a thickness of about 1 mm, and cut into a long sheet having a width of 8 mm. A copper wire having a diameter of 5 mm was attached to one side of the cut magnetic sheet and wound around a cylindrical core 10 times. As a result, a magnetic pad wound around a magnetic sheet and a copper wire in the form of a flat spiral coil having an outer diameter of 25 cm and an inner diameter of 10 cm was obtained.

Comparative Example 1

A copper wire having a diameter of 5 mm was wound four times to obtain a flat spiral coil having an outer diameter of 8 cm and an inner diameter of 4 cm.

Comparative Example 2

A copper wire having a diameter of 5 mm was wound 10 times to obtain a flat spiral coil having an outer diameter of 25 cm and an inner diameter of 10 cm.

Comparative Example 3

A 1.2 mm thick ferrite sheet was cut into 10 cm in width and 10 cm in length. A copper wire having a diameter of 1 mm was wound 15 times to form a flat spiral coil having an outer diameter of 8.5 cm and an inner diameter of 3.5 cm. A magnetic pad was obtained by attaching the flat spiral coil to one surface of the ferrite sheet.

Test Example 1

For the magnetic pad of Example 1 and the coil of Comparative Example 1, the characteristics of the coil were measured at the standard frequency of EV wireless charging (85 kHz) using an LCR meter.

The results are shown in Table 1 below.

L: coil inductance (H)

R: AC resistance of coil (Ω)

Q: Q factor of coil (L/R ratio)

division L (μH) R (mΩ) Q (L/R) Comparative Example 1 1.853 66 14 Example 1 2.103 62 18

As shown in Table 1, compared to Comparative Example 1, the inductance (L) value of Example 1 increased by about 13.5%, the resistance (R) decreased, and the Q factor increased.

Test Example 2

Using the magnetic pad of Example 1 or the coil of Comparative Example 1 as a receiver (Rx), the magnetic pads of Comparative Example 3 as a transmitter (Tx), facing each other at 16 mm intervals, and then using an LCR meter. Thus, the coil characteristics were measured at the standard frequency of EV wireless charging (85 kHz). The results are shown in Tables 2 and 3 below.

L: coil inductance (μH)

R: AC resistance of coil (mΩ)

Q: Q factor of coil (quality factor)

k: Coupling coefficient between Tx-Rx

η: Estimated charging efficiency calculated based on coil characteristics (%)

division L (μH) R (mΩ) Q k η Tx 18.22 112 86 0.2732 82% Rx (Comparative Example 1) 1.855 75.37 13

division L (μH) R (mΩ) Q k η Tx 18.53 102 97 0.2882 84.6% Rx (Example 1) 2.045 73.16 15

As shown in Tables 2 and 3, compared to Comparative Example 1, the inductance (L) value of Example 1 was increased, the resistance (R) was decreased, and the Q factor was increased. In addition, compared to Comparative Example 1, the coupling coefficient (k) and charging efficiency (η) of Example 1 were increased.

Test Example 3

The magnetic pad of Example 2 or the two coils of Comparative Example 2 were stacked to form a receiver (Rx), and a flat spiral coil wound with a copper wire 15 times was used as a transmitter (Tx) to face each other at 42 mm intervals. Then, the coil characteristics were measured at the EV wireless charging standard frequency (85 kHz) using an LCR meter. The results are shown in Table 4 below.

L: coil inductance (μH)

k: Coupling coefficient between Tx-Rx

division L (μH) k Comparative Example 2 74.89 0.123 Example 2 80.64 0.127

As shown in Table 1, compared to Comparative Example 2, the inductance (L) value of Example 2 was increased by about 7.6%, and the coupling coefficient (k) was increased.

10: transmitter of wireless charging element, 20: receiver of wireless charging element,
100: magnetic pad, 110: conductive wire,
120: guide member, 121: magnetic particles,
122: binder resin, 130: base substrate,
200: core, 300: electromagnetic signal,
w: width of the guide member, t: thickness of the guide member,
a: The angle between the long axis of the magnetic particles and the plane direction of the base substrate (or planar coil).
d: Diameter (thickness) of the conductive wire.

Claims (15)

A conductive wire wound in a flat coil shape; And
A guide member disposed between the conductive wires; And
Including a magnetic sheet disposed on the lower surface of the conductive wire wound in the form of a flat coil,
The guide member is a flexible magnetic sheet comprising a binder resin and magnetic particles dispersed in the binder resin and having a magnetic permeability of 100 to 300 with respect to an AC current of a frequency of 81 kHz to 90 kHz,
The magnetic pad, wherein the magnetic particles have an aspect ratio of 1.1:1 to 50:1, wherein an average angle between a long axis of the magnetic particles and a plane direction of the planar coil is 75° to 105°.
The method of claim 1,
The magnetic pad, wherein the guide member has a width of 1 mm to 10 mm and a thickness of 0.05 mm to 2 mm.
The method of claim 1,
The magnetic pad, wherein the conductive wire has a diameter of 1 mm to 10 mm.
The method of claim 1,
The magnetic pad, wherein the width of the guide member is greater than or equal to the diameter of the conductive wire.
delete delete delete The method of claim 1,
The magnetic pad, wherein the planar coil is a planar spiral coil.
The method of claim 1,
The magnetic pad, wherein the planar coil has an outer diameter of 10 cm to 50 cm.
The method of claim 9,
The magnetic pad of the planar coil is formed by winding the conductive wire 10 to 30 times.
delete Winding the conductive wire together with the guide member in the form of a flat coil; And
Attaching a magnetic sheet to a lower surface of the conductive wire wound in the form of a flat coil,
The guide member is a flexible magnetic sheet comprising a binder resin and magnetic particles dispersed in the binder resin and having a magnetic permeability of 100 to 300 with respect to an AC current of a frequency of 81 kHz to 90 kHz,
The magnetic particles have an aspect ratio of 1.1:1 to 50:1, wherein the average angle between the long axis of the magnetic particles and the plane direction of the planar coil is 75° to 105°, a method of manufacturing a magnetic pad.
The method of claim 12,
The method of manufacturing the magnetic pad,
Coupling the conductive wire to one surface of the guide member; And
A method of manufacturing a magnetic pad comprising the step of winding the guide member coupled with the conductive wire into a flat coil shape.
A wireless charging device comprising the magnetic pad of claim 1.
The method of claim 14,
The wireless charging device is used in an electric vehicle, the wireless charging device.

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