JP2018166203A - Soft magnetic thin ribbon for magnetic core, magnetic core, coil unit, and wireless power transmission unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a soft magnetic thin ribbon for a magnetic core in which reduction in eddy current loss and maintenance of high inductance are compatible.SOLUTION: A soft magnetic thin ribbon 10 for a magnetic core according to the present invention, which is divided into small pieces, includes an inductance priority region 1a having a first average crack interval in which average crack intervals are different from each other and an eddy current suppressing priority region 1b having a second average crack interval.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a soft magnetic ribbon for a magnetic core, a magnetic core, a coil unit, and a wireless power transmission unit.

  A technology for transmitting power without using a power cord, so-called wireless power transmission technology, is attracting attention. Wireless power transfer technology can supply power from a power supply device to a power receiving device in a non-contact manner, so it can be applied to various products such as trains, electric vehicles, etc., home appliances, electronic devices, wireless communication devices, and toys. Is expected.

  In a device used for wireless power transmission, in order to achieve high power transmission efficiency, thin and light weight, and high power transmission, for example, a conductor member forming a coil included in a coil unit, a structure of a winding, a magnetic material The structure and material have been studied (for example, Patent Document 1).

For example, as disclosed in Patent Document 1, ferrite is often used as a magnetic material. However, in the case of a mobile device such as an automobile or a mobile device such as a smartphone, vibration and impact are applied to the device. Therefore, it is desirable that the magnetic material has high vibration resistance and impact resistance, but ferrite is a typical ceramic. It is easily damaged.
Also, mobile devices such as automobiles or portable devices such as smartphones are desired to be thin and light, but if they are thinned, they are more easily damaged, and ferrite has a low saturation magnetic flux density, especially in high output devices. However, there is a limit to reducing the thickness due to concerns about magnetic saturation.

  Patent Document 2 discloses a magnetic core for wireless power transmission that improves impact resistance and is not damaged by an impact such as dropping. However, the disclosed magnetic core for wireless power transmission is a ferrite resin composition molded body having a low permeability of 5 to 15 and a low saturation magnetic flux density because of the use of ferrite. Due to the low magnetic permeability, it is necessary to increase the number of coil windings in order to increase the inductance. Particularly in a high-power device, when the number of turns of the coil increases, the copper loss becomes very large and the efficiency is lowered. In addition, since the saturation magnetic flux density is low, a large magnetic core cross-sectional area is required for use in a high-power device, which is not suitable for downsizing the device.

  In making contactless transmission devices thinner, it is desirable that the magnetic material has a high saturation magnetic flux density so that magnetic saturation does not occur even if the magnetic core is made thinner. Metallic soft magnetic materials are known as soft magnetic materials having a high saturation magnetic flux density. However, metallic soft magnetic materials have a very low electrical resistivity, and when used as a magnetic core for wireless power transmission, There is a problem that the loss is very large and the efficiency is lowered.

As a method for reducing the influence of eddy current loss and improving the efficiency, a magnetic core using a soft magnetic ribbon divided into a plurality of small pieces as disclosed in Patent Document 3 is disclosed. Patent Document 4 discloses a structure for reducing eddy current loss, minimizing a decrease in magnetic permeability, and improving scattering of small pieces, which is a problem when dividing small pieces.
Patent Document 3 discloses a magnetic sheet that is divided so that a magnetic piece having an area of 0.01 mm ² or more and 25 mm ² or less is located in a portion corresponding to the central portion of the coil. It has been shown that the division near the center has a certain effect on eddy current reduction and the Q value of the coil is improved.
The magnetic cores disclosed in Patent Documents 3 and 4 are very thin due to the high saturation magnetic flux density of the magnetic material, and are improved in eddy current loss, which is a problem of metallic soft magnetic materials. It is suitable for realizing high transmission efficiency. However, the magnetic layer has a very small thickness of 30 μm, and magnetic saturation occurs in high-power transmission, so that the output that can be transmitted is limited.
When the magnetic body piece is divided so as to be located at the portion corresponding to the central portion of the coil as in Patent Document 3, it is possible to suppress the eddy current loss due to the magnetic flux passing through the inside of the coil, Eddy currents are not suppressed and are insufficient. Further, as shown in FIG. 1, when the entire surface is divided, the inductance when used as the core of the coil is lowered, so that it is necessary to wind many coils in order to obtain a desired inductance. Loss increases and transmission efficiency decreases.

Patent Document 5 discloses a magnetic sheet for magnetic shielding having two or more regions having different crack sizes (or smaller sizes) in the same magnetic sheet surface.
The magnetic sheet of Patent Document 5 is used as a magnetic shield for suppressing the magnetic flux when performing wireless power feeding (WPC), near field communication (NFC), etc. in a mobile device from reaching a battery installed in the vicinity of the coil. Yes. In order to obtain a high magnetic shielding effect, it is desirable to use a magnetic sheet having a large real part of complex permeability and a small imaginary part at the frequency used, and since the frequency bands used in WPC and NFC are different, the conventional magnetic permeability is different. In the case of using a magnetic sheet of a seed, in Patent Document 5, by changing the crack size of a metal ribbon or ferrite, different magnetic permeability regions suitable for each frequency are formed in the same plane and used. Thus, the volume occupied by the magnetic sheet in the mobile device is reduced.

JP 2012-70557 A International Publication No. 2015/064694 Japanese Patent No. 4836749 JP 2011-134959 A US Patent Application Publication No. 2016/0345473

  However, the magnetic sheet for magnetic shielding disclosed in Patent Document 5 has been made for the above purpose, and when considering application as a magnetic core for wireless power feeding, it is possible to reduce eddy current loss. It is not possible to maintain high inductance at the same time.

  In order to solve such a problem, the present inventor, in the soft magnetic ribbon constituting the magnetic core, reduces the crack size (reduced size) in order to suppress the eddy current in the region where the magnetic flux change is large. Compared with the region where the magnetic flux change is small, the crack size is increased in order to maintain a high inductance, that is, by providing two types of regions with different crack sizes in one soft magnetic ribbon, eddy current loss is reduced. The present invention was completed with the idea of achieving both reduction and maintaining high inductance.

  The present invention has been made in view of the above problems, and provides a soft magnetic ribbon for a magnetic core, a magnetic core, a coil unit, and a wireless power transmission unit that achieve both reduction of eddy current loss and maintenance of high inductance. For the purpose.

In order to solve the above problems, the following means are provided.
(1) The soft magnetic ribbon for a magnetic core according to an aspect of the present invention is a soft magnetic ribbon for a magnetic core divided into small pieces, and the soft magnetic ribbon for a magnetic core has an average crack interval between each other. Different inductance priority areas having a first average crack interval and eddy current suppression priority areas having a second average crack interval are included.

(2) In the above aspect, the inductance priority area is a coil arrangement area where a coil is arranged, the eddy current suppression priority area is a non-coil arrangement area where no coil is arranged, and the first average crack interval is It may be larger than the second average crack interval.

(3) In the aspect described above, a region having a third average crack interval smaller than the second average crack interval is further provided in the vicinity of the boundary between the coil arrangement region and the non-coil arrangement region.

(4) The magnetic core which concerns on 1 aspect of this invention is equipped with the soft-magnetic ribbon for magnetic cores which concerns on the said aspect.

(5) The coil unit which concerns on 1 aspect of this invention is equipped with the magnetic core which concerns on the said aspect, and the coil arrange | positioned on this magnetic core.

(6) A wireless power transmission unit according to an aspect of the present invention includes the coil unit according to the above aspect.

  According to the soft magnetic ribbon, magnetic core, coil unit, and wireless power transmission unit of the present invention, the magnetic core soft magnetic ribbon and magnetic core satisfying both reduction of eddy current loss and maintenance of high inductance. A coil unit and a wireless power transmission unit can be provided.

(A) is a top view of the soft-magnetic ribbon for magnetic cores concerning one Embodiment of this invention, (b) is a top view of the soft-magnetic ribbon for magnetic cores concerning other embodiment of this invention. is there. It is a figure for demonstrating the calculation method of an "average crack space | interval". It is a cross-sectional schematic diagram of the magnetic core concerning one Embodiment of this invention. (A) is a side surface schematic diagram of the coil unit concerning one Embodiment of this invention, (b) is the top view seen from the coil side. It is a side surface schematic diagram of the wireless electric power transmission unit which concerns on one Embodiment of this invention which used the coil unit concerning one Embodiment of this invention as a receiving coil unit and a power transmission coil unit. It is the side surface schematic diagram of the wireless power transmission unit which concerns on other embodiment of this invention which used the coil unit concerning other embodiment of this invention as a receiving coil unit and a power transmission coil unit. It is a graph which shows the magnitude | size of the inductance of an Example, the comparative example 1, and the comparative example 2. FIG. It is a graph which shows the magnitude | size of the power transmission efficiency of an Example, the comparative example 1, and the comparative example 2. FIG.

  Hereinafter, the present embodiment will be described in detail with appropriate reference to the drawings. In the drawings used in the following description, in order to make the characteristics of the present invention easier to understand, there are cases where the characteristic parts are enlarged for the sake of convenience, and the dimensional ratios of the respective components are different from actual ones. is there. The materials, dimensions, and the like exemplified in the following description are merely examples, and the present invention is not limited to these, and can be implemented with appropriate modifications within the scope of the effects of the present invention.

[Soft magnetic ribbon for magnetic core]
FIG. 1A is a plan view of a soft magnetic ribbon for a magnetic core according to one embodiment of the present invention, and FIG. 1B is a soft magnetic ribbon for a magnetic core according to another embodiment of the present invention. FIG.
A soft magnetic ribbon 10 for a magnetic core shown in FIG. 1A is a soft magnetic ribbon for a magnetic core divided into small pieces, and the soft magnetic ribbon for a magnetic core has different average crack intervals. An inductance priority region 1a having an average crack interval of 1 and an eddy current suppression priority region 1b having a second average crack interval.
A soft magnetic ribbon 10A for a magnetic core shown in FIG. 1B is a soft magnetic ribbon for a magnetic core divided into small pieces, and the soft magnetic ribbon for a magnetic core has different average crack intervals. Inductance priority region 1aa having an average crack interval of 1 and eddy current suppression priority region 1bb having a second average crack interval.

  Here, in this specification, the “average crack interval” means the number of cracks that intersect a line segment divided by the length of the line segment when a line segment is drawn in a cracked (divided, fragmented) region. It is a thing.

A method of calculating the “average crack interval” will be described with reference to a specific case shown in FIG. The numbers in FIG. 2 indicate numbers obtained by sequentially counting the intersections of cracks and line segments.
The example shown in FIG. 2 is a 4 mm × 4 mm square soft magnetic ribbon for a magnetic core, and cracks are generated by the fragmentation process. In the figure, cracks are indicated by solid lines, and line segments are indicated by dotted lines.
The line segment extends in one direction (the horizontal direction in the figure) of the soft magnetic ribbon for the square magnetic core, and is parallel to the direction orthogonal to the direction (the vertical direction in the figure) at 10 equal intervals. A line segment is drawn. At this time, the number of cracks crossing the line segment is measured to obtain the total number of cracks crossing the line segment, and the total crack length divided by the total number is defined as the average crack interval. When expressed in a calculation formula, the formula (1) is obtained.
Average crack interval [mm] = (total length of line segment) / (total number of cracks intersecting with line segment) (1)
When the example shown in FIG. 2 is applied to the calculation formula (1), the total number of cracks crossing the line segment is 46, and the total length of the line segment is 40 mm, so the average crack interval is about 40/46 [mm]. 0.87 mm.

Since the average crack interval varies depending on the selected region, it is preferable to calculate and average the plurality of regions.
Moreover, it is preferable to decide how to take the selection area.
For example, in the case of the soft magnetic ribbon 10 for a magnetic core shown in FIG. 1A, when calculating the average crack interval of the inductance priority area 1a, the center line A of the donut-shaped area is selected as the area to be selected. can do.

  In the present invention, the eddy current is reduced in size, but the reduction in the magnetic permeability of the soft magnetic ribbon for the magnetic core reduces the inductance. In view of this, the present inventor suggested that in the soft magnetic ribbon for the magnetic core, a region where a large eddy current is generated is sufficiently fragmented to suppress eddy current, but an inductance does not decrease in a region where a large eddy current is not generated. In order to reduce the eddy current loss and suppress the inductance drop (maintaining high inductance) by providing a small and large area in the soft magnetic ribbon for a magnetic core, which is configured so that it is not very small. ).

The inductance priority area is a coil arrangement area where the coil is arranged, the eddy current suppression priority area is a non-coil arrangement area where no coil is arranged, and the first average crack interval is larger than the second average crack interval. Is preferred. More preferably, the first average crack interval is 50 times or more the second crack interval. In this way, it is possible to further reduce eddy current loss.
In a coil unit used for wireless power transmission, a coil is arranged on one surface of a soft magnetic ribbon for a magnetic core. In the coil arrangement region where this coil is arranged, a change in magnetic flux density in the direction perpendicular to the coil surface is observed. Since it is small, the eddy current generated in the coil surface is not large. On the other hand, in the non-coil arrangement region where no coil is arranged, there is no cancellation of the direct component of the magnetic flux on the coil surface, so the change in magnetic flux density is larger than in the coil arrangement region, and vortices generated in the coil surface. The current is also large. For this reason, it is preferable that the non-coil arrangement region has priority over the suppression of eddy current, whereas the coil arrangement region has priority over the inductance reduction over the suppression of eddy current.
Therefore, the coil placement region is not subjected to the fragmentation process so much and the average crack interval (second average crack interval) is kept large, while the non-coil placement region is sufficiently fragmented to obtain the average crack interval. It is preferable to reduce (first average crack interval).
Here, in this specification, the “coil placement region” refers to a region where the coil is projected when the coil is placed on the soft magnetic ribbon for the magnetic core and viewed in plan from the coil side. The region is a “non-coil placement region”.

It is preferable to further have a region having a third average crack interval smaller than the second average crack interval in the vicinity of the boundary between the coil arrangement region and the non-coil arrangement region. For example, when the coil placement region has a donut shape, the vicinity of the boundary between the coil placement region and the non-coil placement region is close to the inner peripheral end or the outer peripheral end of the coil placement region. There are regions (hereinafter referred to as “inner peripheral edge proximity region” and “outer peripheral edge proximity region”). More preferably, the third average crack interval is 0.5 times or less with respect to the second crack interval.
Since the change in magnetic flux density is large at the boundary between the coil placement region and the non-coil placement region, it is preferable that the vicinity of the boundary region is further sufficiently subjected to fragmentation processing to suppress eddy currents. For example, when the coil placement area has a donut shape, the inner peripheral edge proximity area and the outer peripheral edge proximity area, which are areas where the magnetic flux enters the magnetic core, are more sufficiently fragmented. It is preferable to keep it. Both the inner peripheral end proximity region and the outer peripheral end proximity region include a part of the coil placement region and a part of the non-coil placement region.
Here, “near” in the “near boundary” is determined in consideration of both reduction of eddy current loss and maintenance of high inductance based on the soft magnetic ribbon for the magnetic core and the size of the coil. Although it is not limited to a specific numerical range, for example, in the case of a planar spiral coil, an area of about 10% or less of the coil diameter (outer diameter) on the inner side and outer side of the inner peripheral end, Alternatively, the region is about 10% or less of the coil diameter on the inner side and the outer side than the outer peripheral end. For example, in the case of a coil outer diameter of 130 mm, it is about +/− 13 mm from the inner and outer peripheral ends of the coil.

In the present invention, since the eddy current increases when the magnetic flux change is large, the eddy current is sufficiently reduced to suppress the eddy current, whereas the small eddy current is small when the magnetic flux change is small. The idea is to suppress the decrease in inductance as a whole without reducing the size so much (including the case where it is not applied at all) in order to avoid the decrease in inductance due to the conversion.
The magnitude of the magnetic flux change on the soft magnetic ribbon for the magnetic core is not two or three types, so it may be configured to have more types of average crack interval regions, or the change in the average crack interval It is good also as a structure which provided many substantially continuous area | regions. Or it is good also as a structure which estimated the magnetic flux change by simulation and provided the area | region where a mean crack space | interval differs according to the magnitude of the change.

  As the soft magnetic ribbon for the magnetic core, a known material can be used. For example, a magnetic alloy such as an amorphous alloy, a microcrystalline alloy, or permalloy can be used. Examples of the amorphous alloy material include an Fe-based amorphous soft magnetic material and a Co-based amorphous soft magnetic material, and examples of the microcrystalline alloy material include an Fe-based nanocrystalline soft magnetic material. There is something that consists of.

[Method for producing soft magnetic ribbon for magnetic core]
As a method for producing the soft magnetic ribbon for a magnetic core of the present invention, a known fragmentation method, that is, a method of dividing by applying an external force can be used.
As a method of dividing by applying an external force, for example, a method of pressing with a mold, a method of bending through a rolling roll, a method of providing a predetermined uneven pattern on the mold or roll, etc. are known. .
In order to provide two or more types of regions having different average crack intervals in one soft core ribbon for a magnetic core using these methods, the region pattern is set so that the external force applied to each region is different. Pattern media (pattern paper, mask, etc.) corresponding to the above may be used. Moreover, it is good also as a thing of the pattern corresponding to the area | region pattern for the uneven | corrugated pattern provided in the surface of a metal mold | die or a roll.

[Magnetic core]
FIG. 3 is a schematic cross-sectional view of a magnetic core according to an embodiment of the present invention.
A magnetic core 110 shown in FIG. 3 includes a laminated body M including a plurality of soft magnetic ribbons 10a to 10j for a magnetic core divided into small pieces, and adhesive layers 2a to 2i between adjacent soft magnetic ribbons. Among the ten magnetic core soft magnetic ribbons, at least one is the soft magnetic ribbon for the magnetic core of the present invention.
Further, the magnetic core 110 shown in FIG. 3 includes protective films 3 a and 3 b on the upper surface and the lower surface of the multilayer body M, respectively.
The magnetic core of the present invention has a soft magnetic ribbon for a magnetic core and an adhesive layer as main members in the same manner as an ordinary magnetic core, but may include other components as long as the effects of the present invention are achieved.

By having the adhesive layer, it is possible to suppress the falling off of the divided pieces.
As the adhesive layer, a known material can be used. For example, an adhesive made of an acrylic adhesive, silicone resin, butadiene resin, or the like, or a hot melt applied to the surface of the PET film substrate can be exemplified. . Moreover, as a base material, resin films, such as a fluororesin film like a polyimide film, a polyester film, a polyphenylene sulfide (PPS) film, a polypropylene (PP) film, polytetrafluoroethylene (PTFE) other than PET film, etc. Can be illustrated.

The magnetic core 110 shown in FIG. 3 includes a plurality of soft magnetic ribbons for the magnetic core, but one soft magnetic ribbon for the magnetic core may be used.
When the magnetic core of the present invention has a plurality of soft magnetic ribbons for the magnetic core, it is most effective that all are the soft magnetic ribbons for the magnetic core of the present invention. Of the plurality of soft magnetic ribbons for a magnetic core provided in the magnetic core of the present invention, when the number of soft magnetic ribbons for the magnetic core of the present invention is one, the magnetic core disposed on the outermost surface on which the coil is placed The soft magnetic ribbon for use is preferably the soft magnetic ribbon for a magnetic core of the present invention.

  As a method for producing the magnetic core of the present invention, a known method can be used.

[Coil unit]
FIG. 4A is a schematic side view of a coil unit according to an embodiment of the present invention, and FIG. 3B is a plan view of the coil unit viewed from the coil side.
A coil unit 100 shown in FIG. 4 includes a magnetic core 110 of the present invention and a coil 20 disposed on the magnetic core 110. The coil 20 is arranged in the inductance priority area (coil arrangement area) of the magnetic core 110.
The coil unit 100 shown in FIG. 4 can be used as both a power receiving coil unit and a power transmitting coil unit.

[Wireless power transmission unit]
FIG. 5 is a schematic side view of a wireless power transmission unit using a coil unit according to an embodiment of the present invention as a power receiving coil unit and a power transmitting coil unit. FIG. 5 shows the power receiving coil unit of the wireless power transmission unit. Only the power transmission coil unit is shown. Other components of the wireless power transmission unit include, for example, a power supply, an amplifier unit composed of an inverter, a power receiving unit composed of a rectifier, a charging unit for charging the received electricity to a storage battery, or a voltage suitable for equipment. There is a DCDC converter to make it.
A wireless power transmission unit 200 illustrated in FIG. 5 includes a power transmission coil unit 210 including a magnetic core 110 and a power transmission coil 20, and a power reception coil unit 220 including a magnetic core 130 and a power reception coil 40.

FIG. 6 is a schematic side view of a wireless power transmission unit in which a coil unit according to another embodiment of the present invention is used as a power receiving coil unit and a power transmission coil unit. Only the unit and the power transmission coil unit are shown.
A wireless power transmission unit 300 shown in FIG. 6 includes a power transmission coil unit 310 including a bobbin 111, a magnetic core 112, a metal shield 113, and a power transmission coil 20, and a power reception including a bobbin 131, a magnetic core 132, a metal shield 133, and a power reception coil 40. A coil unit 320.
In this embodiment, the power transmission coil unit 310 includes a bobbin 111 and a metal shield 113, and similarly, the power reception coil unit 320 includes a bobbin 131 and a metal shield 133, which is different from the embodiment illustrated in FIG.
The bobbin is a resin part for winding the coil neatly, and the metal shield is a metal plate for blocking the leakage magnetic flux so as not to affect peripheral devices.

  The embodiments of the present invention have been described in detail with reference to the drawings. However, the configurations and combinations of the embodiments in the embodiments are examples, and the addition and the omission of the configurations are within the scope not departing from the gist of the present invention. , Substitutions, and other changes are possible.

"Example 1"
1. Production of magnetic core (1) First, an Fe-based nanocrystal having a thickness of about 20 μm, which has been heat-treated on one side of a PET film (5 μm in combination with the PET film and the pressure-sensitive adhesive) coated with an adhesive on both sides to a thickness of 5 μm. Adhere soft magnetic ribbon (soft magnetic ribbon made of Fe-based nanocrystalline soft magnetic material) to magnetic sheet (PET film coated with adhesive on one side as adhesive layer) Fe-based nanocrystalline soft magnetic ribbon A pasted configuration was prepared, with a vertical and horizontal size of 150 mm × 150 mm.
(2) Next, the fragmentation size is set so that the portion not covered with the coil (eddy current suppression priority region) has an average crack interval of 0.07 mm and the portion covered with the coil (inductance priority region) has an average crack interval of 8 mm. A fragmented magnetic sheet subjected to the adjusted fragmentation treatment was produced.
(3) Next, the five-layered fragmented magnetic sheet produced in the same manner was placed and laminated so that the adhesive of the fragmented magnetic sheet and the Fe-based nanocrystalline soft magnetic ribbon were opposed to each other. Was a magnetic core.
2. Evaluation (1) Coil Inductance A 22-turn circular planar spiral coil (inner diameter 50 mm, outer diameter 132 mm, thickness 1.8 mm) is placed on the obtained magnetic core, and the inductance of the coil is measured using an LCR meter. It was measured.
(2) Transmission efficiency (output power / input power) η
A power transmission coil using a wireless power transmission device including a power transmission unit including a DC power source, an amplifier unit, a resonance capacitor, a power transmission coil unit, and a power reception unit including a power reception coil unit, a resonance capacitor, a rectifying and smoothing circuit, and an electronic load A ferrite plate having a thickness of 1.5 mm as a magnetic core of the unit and a power transmission coil unit using the magnetic core of Example 1 as a magnetic core of the power receiving coil unit are opposed to the power receiving coil unit so that the distance between the coils is 53 mm. The power transmission efficiency η (100 × (output power / input power)) when 250 W of power was received by wireless power transmission was measured.
Input power and output power were measured using a power meter (Yokogawa Electric WT210).

"Example 2"
Example except that the fragmentation process was performed so that the portion of the Fe-based nanocrystalline soft magnetic ribbon not covered with the coil had an average crack interval of 0.16 mm and the portion covered with the coil had an average crack interval of 8 mm In the same manner as in Example 1, the magnetic core of Example 2 was produced.

"Example 3"
Example except that the fragmentation process was performed so that the portion of the Fe-based nanocrystalline soft magnetic ribbon not covered with the coil had an average crack interval of 0.32 mm and the portion covered with the coil had an average crack interval of 8 mm In the same manner as in Example 1, the magnetic core of Example 3 was produced.

Example 4
Example except that the fragmentation process was performed so that the portion of the Fe-based nanocrystalline soft magnetic ribbon not covered with the coil had an average crack interval of 8 mm and the portion covered with the coil had an average crack interval of 0.16 mm In the same manner as in Example 1, a magnetic core of Example 4 was produced.

  Similarly to Examples 2 to 4, the coil inductance and the power transmission efficiency (output power / input power) were measured.

"Example 5"
A magnetic core of Example 5 was produced in the same manner as Example 1. The same measurements as in Examples 2 to 4 were performed except that a 22-turn square planar spiral coil (inner diameter 50 mm, outer diameter 130 mm, thickness 1.8 mm) was disposed on the obtained magnetic core.

"Comparative Example 1"
A magnetic core of Comparative Example 1 was produced in the same manner as in Example 1 except that the fragmentation treatment was performed so that the entire surface of the Fe-based nanocrystalline soft magnetic ribbon had an average crack interval of 0.07 mm.

"Comparative Example 2"
A magnetic core of Comparative Example 2 was produced in the same manner as in Example 1 except that the fragmentation process was performed so that the entire surface of the Fe-based nanocrystalline soft magnetic ribbon had an average crack interval of 8 mm.

  For Comparative Examples 1 and 2, as in Example 1, the coil inductance and power transmission efficiency (output power / input power) were measured.

“Comparative Example 3”
A magnetic core of Comparative Example 3 was produced in the same manner as Comparative Example 1. The same measurement as in Comparative Example 1 was performed, except that a 22-turn square planar spiral coil (inner diameter 50 mm, outer diameter 130 mm, thickness 1.8 mm) was disposed on the obtained magnetic core.

“Comparative Example 4”
A magnetic core of Comparative Example 4 was produced in the same manner as Comparative Example 2. The same measurement as in Comparative Example 2 was performed except that a 22-turn square planar spiral coil (inner diameter 50 mm, outer diameter 130 mm, thickness 1.8 mm) was disposed on the obtained magnetic core.

FIG. 7 compares the inductance measurement results of Example 1, Comparative Example 1, and Comparative Example 2. The plan view shown below the graph shows each receiving coil unit. A donut-like shape indicated by a dotted line shows a projection view of a coil (coil placement region).
FIG. 8 is a diagram illustrating measurement results of power transmission efficiency in Example 1, Comparative Example 1, and Comparative Example 2.

  As shown in FIGS. 7 and 8, in Example 1, higher coil transmission efficiency was obtained than in either Comparative Example 1 or Comparative Example 2 while maintaining high inductance of the coil.

  Table 1 summarizes the measurement results of Examples 1 to 5 and Comparative Examples 1 to 4. In any case of Examples 1-5, high power transmission efficiency is obtained, maintaining a high inductance with respect to Comparative Examples 1-4. In the case of Example 4 in which the average crack interval between the two regions is reversed, the inductance is slightly low, but the power transmission efficiency equivalent to that of Examples 1 to 3 is obtained.

"Example 6"
A magnetic sheet having an Fe-based amorphous soft magnetic ribbon bonded to one side of a PET film was used. Further, the fragmentation process was performed so that the portion not covered with the coil of the Fe-based amorphous soft magnetic ribbon had an average crack interval of 0.18 mm and the portion covered with the coil had an average crack interval of 10 mm. The other conditions were the same as in Example 1, and a magnetic core of Example 6 was produced.

“Comparative Example 5”
A magnetic sheet having an Fe-based amorphous soft magnetic ribbon bonded to one side of a PET film was used. Further, a magnetic core of Comparative Example 5 was produced in the same manner as Comparative Example 1 except that the fragmentation process was performed so that the entire surface of the Fe-based amorphous soft magnetic ribbon had an average crack interval of 10 mm.

“Comparative Example 6”
A magnetic core of Comparative Example 6 was produced in the same manner as Comparative Example 5 except that the fragmentation process was performed so that the entire surface of the Fe-based amorphous soft magnetic ribbon had an average crack interval of 0.18 mm.

  Table 2 summarizes the measurement results of Example 6 and Comparative Examples 5 and 6. Even when the type of the magnetic material is changed, the power transmission efficiency of Example 6 is higher than that of Comparative Examples 5 and 6, while maintaining high inductance.

"Example 7"
A region having a third crack interval smaller than the second average crack interval is provided in the vicinity of the boundary between the coil arrangement region (inductance priority region) and the non-coil arrangement region (eddy current suppression priority region). The fragmentation process was performed. Here, the third crack interval was set to 0.03 mm. Regarding other conditions, the magnetic core of Example 7 was produced in the same manner as in Example 1.

  As in Example 1, the coil inductance and power transmission efficiency (output power / input power) were measured. Table 3 summarizes the measurement results of Example 7. When there is a portion having the third crack interval, high power transmission efficiency is obtained while maintaining the same high inductance as in Examples 1 to 4.

1a, 1aa Inductance priority area (coil placement area)
1b, 1bb Eddy current suppression priority area (area for non-coil placement)
2a-2i Adhesive layer 3a, 3b Protective film 10, 10a-10j, 10A, soft magnetic ribbon for magnetic core 110, 112, 130, 132 Magnetic core
20, 40 Coil 100 Coil unit 200, 300 Wireless power transmission unit 210, 310 Power transmission coil unit 220, 320 Power reception coil unit M Laminate

Claims (6)

A soft magnetic ribbon for a magnetic core divided into small pieces,
The soft magnetic ribbon for a magnetic core has an inductance priority region having a first average crack interval and an eddy current suppression priority region having a second average crack interval, the average crack interval being different from each other. Magnetic ribbon. The inductance priority area is a coil arrangement area where a coil is arranged, and the eddy current suppression priority area is a non-coil arrangement area where a coil is not arranged,
The soft magnetic ribbon for a magnetic core according to claim 1, wherein the first average crack interval is larger than the second average crack interval.   The magnetic core according to claim 2, further comprising a region having a third average crack interval smaller than the second average crack interval in the vicinity of a boundary between the coil arrangement region and the non-coil arrangement region. Soft magnetic ribbon.   A magnetic core comprising the soft magnetic ribbon for a magnetic core according to claim 1.   A coil unit comprising the magnetic core according to claim 4 and a coil disposed on the magnetic core.   A wireless power transmission unit comprising the coil unit according to claim 5.

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