Reactor, converter, and power conversion device

Abstract

This reactor comprises a coil and a magnetic core. The magnetic core includes: a middle core part which is disposed inside the coil; and a first end core part and a second end core part which are disposed so as to connect respectively to a first end section and a second end section of the middle core part. The outer peripheral surface of the coil has a portion exposed from the magnetic core. The first end section and the second end section each have a first portion, and a second portion having a higher relative magnetic permeability than the first portion. The first end core part and the second end core part each have a first portion connected to the aforementioned first portion and a second portion connected to the aforementioned second portion. The relative magnetic permeability of the second portions of the first end core part and the second end core part is higher than the relative magnetic permeability of the first portions of the first end core part and the second end core part.

Description

Reactors, converters, and power conversion devices

[0001] The present disclosure relates to a reactor, a converter, and a power conversion device. This application claims priority from Japanese Patent Application No. 2024-027004 filed on February 26, 2024. The entire contents of the Japanese application are incorporated herein by reference.

[0002] The magnetic core of the reactor in Patent Document 1 includes core pieces formed by combining first core pieces and second core pieces. The first core pieces are formed from a composite material molded body in which soft magnetic powder is dispersed in resin. The second core pieces are formed from a powder compact of soft magnetic powder. The core pieces are manufactured by placing the second core pieces in a mold and molding the first core pieces around the second core pieces. Hereinafter, the portion formed from the composite material molded body will be referred to as the first portion, and the portion formed from the powder compact will be referred to as the second portion.

[0003] Japanese Patent Application Laid-Open No. 2022-45166

[0004] The reactor disclosed herein includes a coil and a magnetic core having an annular planar shape. The magnetic core has a middle core portion disposed inside the coil and first and second end core portions disposed facing the first and second end faces of the coil so as to connect to the first and second end faces of the middle core portion, respectively. The outer circumferential surface of the coil has a portion exposed from the magnetic core. Each of the first and second end portions has a first portion and a second portion having a higher relative magnetic permeability than the first portion. The first and second end core portions have a first portion connected to the first portion and a second portion connected to the second portion. The relative magnetic permeability of the second portions of the first and second end core portions is higher than the relative magnetic permeability of the first portions of the first and second end core portions.

[0005] FIG. 1 is a perspective view showing an outline of a reactor according to a first embodiment. FIG. 2 is a perspective view showing an outline of an exploded state of the reactor according to the first embodiment. FIG. 3 is a cross-sectional view taken along III-III in FIG. 1. FIG. 4 is a cross-sectional view taken along IV-IV in FIG. 1. FIG. 5 is a cross-sectional view taken along V-V in FIG. 1. FIG. 6 is a perspective view showing an outline of a reactor according to a second embodiment. FIG. 7 is a perspective view showing an outline of an exploded state of the reactor according to the second embodiment. FIG. 8 is a cross-sectional view taken along VIII-VIII in FIG. 6. FIG. 9 is a perspective view showing an outline of a reactor according to a third embodiment. FIG. 10 is a perspective view showing an outline of an exploded state of the reactor according to the third embodiment. FIG. 11 is a cross-sectional view taken along XI-XI in FIG. 9. FIG. 12 is a configuration diagram schematically showing a power supply system of a hybrid vehicle. FIG. 13 is a circuit diagram showing an example of a power conversion device including a converter.

[0006] [Problem to be Solved by the Present Disclosure] It is desired to manufacture a reactor that maintains high inductance and low loss even in a large current operating environment by using a core piece that combines a first portion and a second portion. In a core piece that combines a first portion and a second portion made of different materials, it is desired that the first portion and the second portion be well joined.

[0007] An object of the present disclosure is to provide a reactor that maintains high inductance and low loss even in a large current usage environment.

[0008] [Effects of the Present Disclosure] The reactor of the present disclosure maintains high inductance and low loss even in a usage environment with a large current.

[0009] <Description of Embodiments of the Present Disclosure> First, embodiments of the present disclosure will be listed and described.

[0010] (1) A reactor according to one aspect of the present disclosure includes a coil and a magnetic core having an annular planar shape. The magnetic core has a middle core portion disposed inside the coil and first and second end core portions disposed facing first and second end faces of the coil so as to connect to first and second end faces of the middle core portion, respectively. The outer circumferential surface of the coil has a portion exposed from the magnetic core. Each of the first and second end portions has a first portion and a second portion having a higher relative magnetic permeability than the first portion. The first and second end core portions have a first portion connected to the first portion and a second portion connected to the second portion. The relative magnetic permeability of the second portions of the first and second end core portions is higher than the relative magnetic permeability of the first portions of the first and second end core portions.

[0011] Generally, magnetic flux tends to leak near the joints between the end core portions and the middle core portion. In the reactor (1) described above, magnetic flux tends to pass through the second portions of the middle core portion and the second portions of the end core portions connected to these second portions near the joints. Furthermore, magnetic flux passing through the first portions of the middle core portion and the first portions of the end core portions connected to these first portions is easily attracted to the second portions of the middle core portion and the second portions of the end core portions. Therefore, the reactor (1) described above is less likely to leak magnetic flux from the joints. Therefore, the reactor (1) described above has low loss because loss can be reduced as leakage magnetic flux is reduced.

[0012] Although the reactor (1) above has a second portion with a higher relative magnetic permeability than the first portion, the influence of the second portion on magnetic saturation is relatively small, so that a high inductance can be maintained.

[0013] Because the second portions of the middle core portion are connected to the second portions of the end core portions, the second portions of the middle core portion and the second portions of the end core portions can be formed in series. Also, because the first portions of the middle core portion are connected to the first portions of the end core portions, the first portions of the middle core portion and the first portions of the end core portions can be formed in series. Therefore, the reactor of (1) above has excellent productivity.

[0014] (2) In the reactor of (1) above, the second portion may have a relative magnetic permeability of 50 or more and 500 or less.

[0015] The reactor (2) allows magnetic flux to easily pass through the second portion, and therefore leakage magnetic flux can easily be reduced.

[0016] (3) In the reactor of (1) or (2), the relative magnetic permeability of the first portion may be 5 or more and 50 or less.

[0017] The reactor (3) described above has a first portion whose relative permeability is in a specific low range, and therefore is less likely to experience magnetic saturation due to the presence of a second portion, and therefore is more likely to maintain a high inductance even in a high current operating environment.

[0018] (4) In the reactor according to any one of (1) to (3), the second portion may be formed of a powder compact of soft magnetic powder.

[0019] The reactor (4) allows magnetic flux to easily pass through the second portion, and therefore leakage magnetic flux can easily be reduced.

[0020] (5) In the reactor according to any one of (1) to (4), the first portion may be formed of a molded body of a composite material in which soft magnetic powder is dispersed in a resin.

[0021] The reactor of (5) above is less susceptible to magnetic saturation due to the provision of the second portion, and therefore is more likely to maintain a high inductance even in a large current operating environment. Furthermore, the reactor of (5) above is easier to manufacture.

[0022] (6) In any of the reactors (1) to (5) above, each of the second portions of the middle core portion may be provided at the center in a direction along the width of each of the first end portion and the second end portion.

[0023] The reactor of (6) above is easy to reduce leakage magnetic flux because magnetic flux easily passes through the center in the direction along the width of each end of the middle core portion.

[0024] (7) In any of the reactors (1) to (5) above, each of the second portions of the middle core portion may be provided at both ends in a direction along the width of each of the first end portion and the second end portion.

[0025] The reactor (7) has second portions at both ends where magnetic flux generally tends to leak, through which magnetic flux easily passes. Therefore, the reactor (7) can easily reduce leakage magnetic flux.

[0026] (8) In any of the reactors (1) to (5) above, each of the second portions of the middle core portion may be provided at either end in a direction along the width of each of the first end portion and the second end portion.

[0027] The reactor (8) has a second end portion, through which magnetic flux can easily pass, at the end portion where magnetic flux generally tends to leak, so that the reactor (8) can easily reduce leakage magnetic flux.

[0028] (9) In the reactor of any one of (1) to (5) above, the second portion of each of the first end core portion and the second end core portion may be provided at the center of the thickness of each of the first end core portion and the second end core portion.

[0029] The reactor (9) above allows magnetic flux to easily pass through the center of the thickness, and therefore leakage magnetic flux is easily reduced.

[0030] (10) In the reactor of any one of (1) to (5), the second portion of each of the middle core portions may be located at the center of the first end portion and the second end portion in the width direction and the center of the thickness direction. When viewed in the axial direction of the coil, the second portion of each of the first end core portion and the second end core portion has an overlapping portion that overlaps the second portion of the middle core portion, and an extension portion that extends outward from the overlapping portion in the width direction of each of the first end core portion and the second end core portion without overlapping the second portion of the middle core portion. Each of the overlapping portions is connected to the second portion of the middle core portion.

[0031] In the reactor of (10) above, near the joints between the end core portions and the middle core portion, magnetic flux easily passes through the second portions provided in the center of the middle core portion and the overlapping portions of the end core portions connected to these second portions. Furthermore, magnetic flux passing through the first portions of the middle core portion and the first portions of the end core portions connected to these first portions is easily attracted to the second portions of the middle core portion and the overlapping portions and extended portions of the end core portions. Therefore, in the reactor of (10) above, magnetic flux is less likely to leak from the joints.

[0032] (11) In the reactor of any one of (1) to (5), the second portions of the middle core portions may be provided at both ends of the first end portion and the second end portion in a widthwise direction and at a center in a thicknesswise direction. When viewed in the axial direction of the coil, the second portions of the first end core portion and the second end core portion each have an overlapping portion that overlaps the second portion of the middle core portion, and an extension portion that extends outward from the overlapping portion in a widthwise direction of the first end core portion and the second end core portion without overlapping the second portion of the middle core portion. Each of the overlapping portions is connected to a corresponding second portion of the middle core portion.

[0033] In the reactor of (11) above, near the joints between the end core portions and the middle core portion, magnetic flux easily passes through the second portions provided at both ends and the center of the middle core portion and the overlapping portions of the end core portions connected to these second portions. Furthermore, magnetic flux passing through the first portions of the middle core portion and the first portions of the end core portions connected to these first portions is easily attracted to the second portions of the middle core portion and the overlapping portions and extended portions of the end core portions. Therefore, the reactor of (11) above is less likely to leak magnetic flux from the joints.

[0034] (12) In the reactor of any one of (1) to (5), the second portion of each of the middle core portions may be located at either end of the first end portion or the second end portion in a widthwise direction and at the center in a thicknesswise direction. When viewed in the axial direction of the coil, the second portion of each of the first end core portion and the second end core portion has an overlapping portion that overlaps the second portion of the middle core portion, and an extension portion that extends outward from the overlapping portion in a widthwise direction of each of the first end core portion and the second end core portion without overlapping the second portion of the middle core portion. Each of the overlapping portions is connected to the second portion of the middle core portion.

[0035] In the reactor (12) described above, near the joints between the end core portions and the middle core portion, magnetic flux easily passes through the second portions provided at the ends and centers of the middle core portions and the overlapping portions of the end core portions connected to these second portions. Furthermore, magnetic flux passing through the first portions of the middle core portions and the first portions of the end core portions connected to these first portions is easily attracted to the second portions of the middle core portions and the overlapping portions and extension portions of the end core portions. Therefore, the reactor (12) described above is less likely to leak magnetic flux from the joints.

[0036] (13) In the reactor of any one of (1) to (12), the width of each of the second portions of the middle core portion may be 0.1 to 0.9 times the overall width of the middle core portion.

[0037] If the width of each second portion is 0.1 times or more the total width, leakage magnetic flux is likely to be reduced. If the width of each second portion is 0.9 times or less the total width, the proportion of the first portion in the middle core portion is likely to be large. Therefore, the reactor (13) is less likely to experience magnetic saturation due to the inclusion of the second portion, and therefore is likely to maintain high inductance even in a high-current operating environment. Furthermore, the joint area between the first portion of the first end core portion and the first portion of the second end core portion and the first portion of the middle core portion is likely to be large. Therefore, the first end core portion and the second end core portion and the middle core portion are likely to be joined well.

[0038] (14) In the reactor of any one of (1) to (13) above, the thickness of each of the second portions of the middle core portion may be 0.1 to 1.0 times the total thickness of the middle core portion.

[0039] When the thickness of each second portion is 0.1 times or more the total thickness, leakage magnetic flux is likely to be reduced. When the thickness of each second portion is 1.0 times or less the total thickness, the proportion of the first portion in the middle core portion is likely to be large. Therefore, the reactor (14) is less likely to experience magnetic saturation due to the inclusion of the second portion, and therefore is likely to maintain high inductance even in a high-current operating environment. Furthermore, the joint area between the first portion of the first end core portion and the first portion of the second end core portion and the first portion of the middle core portion is likely to be large. Therefore, the first end core portion and the second end core portion and the middle core portion are likely to be joined well.

[0040] (15) In the reactor of any one of (1) to (14), the length of each of the second portions of the middle core portion may be 0.05 to 0.45 times the overall length of the middle core portion.

[0041] If the length of each second portion is 0.05 times or more the total length, leakage magnetic flux is likely to be reduced. If the length of each second portion is 0.45 times or less the total length, the proportion of the first portion in the middle core portion is likely to be large. Therefore, the reactor (15) is less likely to experience magnetic saturation due to the inclusion of the second portion, and therefore is likely to maintain high inductance even in a large current operating environment.

[0042] (16) In the reactor of any one of (1) to (15) above, the thickness of the second portion of each of the first end core portion and the second end core portion may be 0.1 to 0.9 times the total thickness of each of the first end core portion and the second end core portion.

[0043] If the thickness of each second portion is 0.1 times or more the total thickness, leakage magnetic flux is likely to be reduced. If the thickness of each second portion is 0.9 times or less the total thickness, the proportion of the first portion in the first end core portion and the second end core portion is likely to be large. Therefore, the reactor (16) is less likely to experience magnetic saturation due to the inclusion of the second portion, and therefore is likely to maintain high inductance even in a high-current operating environment. Furthermore, the joint area between the first portion of the first end core portion and the first portion of the middle core portion is likely to be large. Therefore, the first end core portion and the second end core portion are likely to be joined well to the middle core portion.

[0044] (17) A converter according to one embodiment of the present disclosure includes the reactor described in any one of (1) to (16) above.

[0045] The converter has low loss due to the inclusion of the reactor.

[0046] (18) A power conversion device according to one embodiment of the present disclosure includes the converter described above in (17).

[0047] The power conversion device has low loss because it includes the converter.

[0048] Details of the embodiments of the present disclosure will be described below with reference to the drawings. The same reference numerals in the drawings indicate the same objects. In the drawings, some components may be exaggerated or simplified for ease of explanation. The dimensional ratios of the various parts in the drawings may also differ from the actual ratios.

[0049] First Embodiment [Reactor] A reactor 1 of the first embodiment will be described with reference to FIGS. 1 to 5 . As shown in FIG. 1 , the reactor 1 includes a coil 2 and a magnetic core 3. The coil 2 is configured with a spirally wound winding. The magnetic core 3 has an annular planar shape. The magnetic core 3 includes a middle core portion 4, a side core portion 5, a first end core portion 6, and a second end core portion 7. The middle core portion 4 is disposed inside the coil 2. The side core portion 5 is disposed outside the coil 2 in parallel with the middle core portion 4. The first end core portion 6 is disposed facing a first end face of the coil 2 so as to connect first ends of the middle core portion 4 and the side core portion 5. The second end core portion 7 is disposed facing a second end face of the coil 2 so as to connect second ends of the middle core portion 4 and the side core portion 5.

[0050] One of the features of the reactor 1 of embodiment 1 is that it satisfies the following requirements (a) to (d): (a) the outer circumferential surface of the coil 2 has a portion exposed from the magnetic core 3; (b) the first end 4a and the second end 4b of the middle core portion 4 have first portions 41 and second portions 42 that satisfy a specific magnitude relationship of relative permeability; (c) the first end core portion 6 and the second end core portion 7 have first portions 61, 71 and second portions 62, 72 that satisfy a specific magnitude relationship of relative permeability; (d) each first portion 41 of the middle core portion 4 is connected to the first portions 61, 71 of the first end core portion 6 and the second end core portion 7, and each second portion 42 of the middle core portion 4 is connected to the second portions 62, 72 of the first end core portion 6 and the second end core portion 7. 1 and 2, for the sake of convenience, the second portions 42, 62, and 72 are cross-hatched. This also applies to FIGS. 6, 7, 9, and 10, which will be referred to in the second and third embodiments described later.

[0051] In the following description, the X1 direction, X2 direction, Y1 direction, Y2 direction, Z1 direction, and Z2 direction are defined as follows: The X1 direction is the direction from the second end face of the coil 2 to the first end face along the axis of the coil 2. The X2 direction is the opposite direction to the X1 direction. The Y1 direction is the direction along which the middle core portion 4 and the side core portion 5 are arranged in parallel, and is the direction from the side core portion 5 to the middle core portion 4. The Y2 direction is the opposite direction to the Y1 direction. The Z1 direction is the direction perpendicular to both the X1 direction and the Y1 direction. The Z2 direction is the opposite direction to the Z1 direction.

[0052] The length of reactor 1 along the X1 direction is simply referred to as the length. The length of reactor 1 along the Y1 direction is referred to as the width. The length of reactor 1 along the Z1 direction is referred to as the thickness or height. The shape of magnetic core 3 when viewed in the Z2 direction is a planar shape. In other words, the above-mentioned magnetic core 3 having an annular planar shape means that the shape of magnetic core 3 when viewed in the Z2 direction is annular. For convenience of explanation, the Z1 direction is referred to as the top and the Z2 direction is referred to as the bottom.

[0053] [Coil] As shown in FIGS. 1 and 2 , the number of coils 2 in this example is one. A reactor 1 having one coil 2 is easier to form than a reactor having multiple coils 2. A reactor 1 having one coil 2 has fewer parts than a reactor having multiple coils 2. Therefore, a reactor 1 having one coil 2 is more productive. Having only one coil 2 makes it easier to reduce the width of the reactor 1 compared to a reactor having multiple coils 2 arranged in parallel in the Y2 direction. The multiple coils 2 have multiple winding portions in which the winding is wound in a spiral shape. The windings constituting each winding portion may be independent of each other or may be formed in a continuous manner. The windings constituting each winding portion may be independent of each other, and the windings may be connected to each other by a member that electrically connects the windings to each other.

[0054] As shown in FIG. 2 , the coil 2 has a racetrack-shaped cylindrical shape. As shown in FIG. 5 , the outer peripheral shape of the coil 2 when viewed from the X1 direction is also racetrack-shaped. That is, the end face shape of the coil 2 when viewed from the X1 direction is a racetrack-shaped frame. FIG. 5 shows the reactor 1 cut at a position between the middle core portion 4, the side core portion 5, and the first end core portion 6. The racetrack-shaped cylindrical shape of the coil 2 makes it easier to increase the contact area between the coil 2 and a planar installation object compared to when the coil 2 is a circular cylindrical shape with the same cross-sectional area. Therefore, the reactor 1 easily transfers heat from the coil 2 to the installation object. The installation object is, for example, a cooling base. Furthermore, the racetrack-shaped outer peripheral shape of the coil 2 allows the height of the coil 2 to be reduced. The coil 2 may also have a flat cylindrical shape. For example, the coil 2 may have a rectangular cylindrical shape in which the width of the coil 2 is greater than the height of the coil 2.

[0055] The outer peripheral surface of the coil 2 has a portion exposed from the magnetic core 3. The portion exposed from the magnetic core 3 refers to the portion of the outer peripheral surface of the coil 2 that is not in direct contact with the magnetic core 3. The outer peripheral surface of the coil 2 has an upper surface, a lower surface, a first side surface, and a second side surface. The upper surface and the lower surface face opposite each other. The upper surface faces the Z1 direction. The lower surface faces the Z2 direction. The first side surface and the second side surface face opposite each other. The first side surface faces the Y1 direction. The first side surface connects the upper surface and the lower surface. The second side surface faces the Y2 direction. In other words, the second side surface faces the side core portion 5. The second side surface connects the upper surface and the lower surface. In this example, the upper surface, lower surface, first side surface, and second side surface, i.e., the entire outer peripheral surface, are exposed from the magnetic core 3. The second side surface, which faces the side core portion 5 with a gap therebetween, is also included in the portion exposed from the magnetic core 3 .

[0056] The upper surface of the coil 2 in this example is substantially flush with the upper surfaces of the side core portions 5, the first end core portions 6, and the second end core portions 7, which will be described later. The lower surface of the coil 2 in this example is substantially flush with the lower surfaces of the side core portions 5, the first end core portions 6, and the second end core portions 7. In this specification, "two surfaces are substantially flush" means that the flatness of the two surfaces is 0.4 mm or less. The flatness of the two surfaces may further be 0.2 mm or less, 0.1 mm or less, or 0.05 mm or less. The flatness referred to here complies with JIS B 0621:1984, Definition and Expression of Geometric Deviation.

[0057] For example, when the exposed lower surface of the coil 2 comes into contact with an installation object, the heat of the coil 2 is directly conducted to the installation object. In this example, as described above, the lower surface of the coil 2 and the lower surfaces of the side core portions 5, first end core portions 6, and second end core portions 7 are substantially flush with each other, so that not only the heat of the coil 2 but also the heat of the side core portions 5, first end core portions 6, and second end core portions 7 is directly conducted to the installation object. This is also the case when the upper surface of the coil 2 comes into contact with the installation object. Therefore, the reactor 1 has excellent heat dissipation properties.

[0058] As shown in Figures 1 and 2, the windings that make up the coil 2 are a series of windings with no joints. The windings are well-known windings. The windings in this example use coated rectangular wire. The conductor wire of the coated rectangular wire is made of copper rectangular wire. The insulating coating of the coated rectangular wire is made of enamel. The coil 2 in this example is made by edgewise winding the coated rectangular wire. Unlike this example, the coil 2 may also be made by flatwise winding the coated rectangular wire.

[0059] Although not shown in the figure, the first and second ends of the winding in this example are drawn out in the same direction. Specifically, the first and second ends of the winding are drawn out in the Y1 direction at the first and second ends of the coil 2. That is, the first and second ends of the winding are drawn out so as to move away from the side core portion 5, which will be described later. The first end of the winding is along the upper surface of the coil 2. The second end of the winding is along the lower surface of the coil 2. The upper surface of the first end of the winding is substantially flush with the upper surface of the coil 2, and the lower surface of the second end of the winding is substantially flush with the lower surface of the coil 2. Therefore, the lower or upper surface of the coil 2 is likely to come into contact with the installation object.

[0060] Although not shown, the insulating coating is stripped off from the first and second ends of the winding to expose the conductor wire. Terminal members (not shown) are connected to the exposed conductor wire. An external device (not shown) is connected to the terminal members. The external device is, for example, a power supply that supplies power to the coil 2.

[0061] [Magnetic Core] The magnetic core 3 comprises a closed magnetic circuit formed by the middle core portion 4, the side core portions 5, the first end core portion 6, and the second end core portion 7. The planar shape of the magnetic core 3 in this example is a rectangular ring. For ease of explanation, in Figures 1 and 3, the boundaries between each of the first end core portion 6 and the second end core portion 7 and the middle core portion 4, and the boundaries between each of the first end core portion 6 and the second end core portion 7 and the side core portion 5 are indicated by two-dot chain lines. For ease of explanation, in Figures 2 and 3, the boundaries between each second portion 42 of the middle core portion 4 and each of the overlapping portions 62a of the first end core portion 6 and the overlapping portions 72a of the second end core portion 7 are indicated by two-dot chain lines. 2 and 3, for ease of explanation, the boundaries between the overlapping portion 62a of the first end core portion 6 and the overlapping portion 72a of the second end core portion 7 and the extension portion 62b of the first end core portion 6 and the extension portion 72b of the second end core portion 7 are shown by two-dot chain lines. In Fig. 4, for ease of explanation, the boundaries between the middle core portion 4 and the first end core portion 6 and the second end core portion 7 are shown by two-dot chain lines.

[0062] (Middle core portion) As shown in Figures 1, 3, and 4, the middle core portion 4 has a portion that is disposed inside the coil 2. The shape of the middle core portion 4 in this example corresponds to the shape of the inner peripheral contour of the coil 2. The shape of the middle core portion 4 is columnar. As shown in Figure 5, the outer peripheral shape of the middle core portion 4 when viewed from the X1 direction is a racetrack shape.

[0063] The width of the middle core portion 4 is greater than the thickness of the middle core portion 4. The width of the middle core portion 4 refers to the maximum length along the Y1 direction. The thickness of the middle core portion 4 refers to the maximum length along the Z1 direction. In this example, the width of the middle core portion 4 is greater than the width of the side core portions 5. The width of the side core portions 5 refers to the maximum length along the Y1 direction. In the reactor 1, the coil 2 is arranged in a middle core portion 4 that is wider than the side core portions 5, and therefore the width of the coil 2 is wider than that of the reactor 1X, in which the coil 2 is arranged in a middle core portion 4 that has the same width as the side core portions 5. The width of the coil 2 refers to the maximum length along the Y1 direction.

[0064] When the reactor 1 is installed on a planar installation target, the wide surface of the coil 2 comes into contact with the installation target. Therefore, the reactor 1 can have a larger contact area between the coil 2 and the installation target than the reactor 1X. The reactor 1 can more easily transfer heat from the coil 2 to the installation target than the reactor 1X. Therefore, the reactor 1 has excellent heat dissipation properties. The reactor 1 has the coil 2 arranged in the middle core portion 4, which is wider than the side core portion 5, so the cross-sectional area of ​​the coil 2 can be larger than the reactor 1X. Therefore, the reactor 1 can more easily increase the inductance even though it has only one coil 2 than the reactor 1X. Therefore, the reactor 1 has excellent inductance. The thickness of the middle core portion 4 is smaller than the thicknesses of the side core portions 5, the first end core portion 6, and the second end core portion 7.

[0065] As shown in FIGS. 3 and 4 , the first end 4a and the second end 4b of the middle core portion 4 in this example are composed of two types of portions, a first portion 41 and a second portion 42, which have different relative magnetic permeabilities. In FIG. 2 , for ease of explanation, the first portion 41 of the middle core portion 4 is shown separated from the first portion 61 of the first end core portion 6 and the first portion 71 of the second end core portion 7. However, in reality, the first portion 41 of the middle core portion 4 is formed continuously with the first portion 61 and the first portion 71. The first end 4a is the end of the middle core portion 4 in the X1 direction. The second end 4b is the end of the middle core portion 4 in the X2 direction. The relative magnetic permeability of the second portion 42 is greater than that of the first portion 41. Specific relative magnetic permeabilities of the first portion 41 and the second portion 42 will be described later. The portion of the middle core portion 4 between the first end 4a and the second end 4b is formed by the first portion 41. That is, a portion of each of the first end 4a and the second end 4b of the middle core portion 4 and the portion between the first end 4a and the second end 4b are constituted by the first portion 41, and a portion of each of the first end 4a and the second end 4b of the middle core portion 4 excluding the first portion 41 is constituted by the second portion 42.

[0066] Each second portion 42 is provided at the center of the width of the middle core portion 4, at both ends of the width, or at either end of the width. "Provided at the center of the width" refers to the first portion 41, the second portion 42, and the first portion 41 being arranged in this order in the Y1 direction on an X-Y cross section passing through the second portion 42. "Provided at the center of the width" as used herein includes cases where the center of the width of the middle core portion 4 coincides with the center of the width of the second portion 42, but also includes cases where the center of the width of the middle core portion 4 does not coincide with the center of the width of the second portion 42. "Provided at both ends of the width" refers to the second portion 42, the first portion 41, and the second portion 42 being arranged in this order in the Y1 direction on an X-Y cross section passing through the second portion 42. "Provided at either end of the width" refers to either the first arrangement or the second arrangement. The first arrangement mode refers to a mode in which the second portion 42 and the first portion 41 are arranged in this order toward the Y1 direction in an XY cross section passing through the second portion 42. The second arrangement mode refers to a mode in which the first portion 41 and the second portion 42 are arranged in this order toward the Y1 direction in an XY cross section passing through the second portion 42.

[0067] The width of each second portion 42 is, for example, 0.1 to 0.9 times the overall width of the middle core portion 4. That is, each second portion 42 does not extend over the entire width of the middle core portion 4. If the width of each second portion 42 is 0.1 times or more the overall width, leakage magnetic flux is likely to be reduced, and therefore loss is likely to be reduced. If the width of each second portion 42 is 0.9 times or less the overall width, the proportion of the first portion 41 in the middle core portion 4 is likely to be increased. Therefore, the reactor 1 is less likely to experience magnetic saturation due to the inclusion of the second portion 42, and therefore is likely to maintain high inductance even in a high-current operating environment. Furthermore, the joint area between the first portion 61, 71 and the first portion 41 of the middle core portion 4 is likely to be large. Therefore, the first end core portion 6 and the second end core portion 7 are likely to be joined to the middle core portion 4 favorably. The width of each second portion 42 may be, for example, 0.2 times or more and 0.8 times or less, or 0.3 times or more and 0.7 times or less, the total width.

[0068] The thickness of each second portion 42 is, for example, 0.1 to 1.0 times the total thickness of the middle core portion 4. If the thickness of each second portion 42 is 0.1 times or more the total thickness, leakage magnetic flux is likely to be reduced. If the thickness of each second portion 42 is 1.0 times or less the total thickness, the proportion of the first portion 41 in the middle core portion 4 is likely to be high. Therefore, the reactor 1 is less likely to experience magnetic saturation due to the inclusion of the second portion 42, and therefore is likely to maintain high inductance even in a high-current operating environment. Furthermore, the joint area between the first portions 61, 71 and the first portion 41 of the middle core portion 4 is likely to be large. Therefore, the first end core portion 6 and the second end core portion 7 are likely to be well joined to the middle core portion 4. The thickness of each second portion 42 may be, for example, 0.2 to 0.9 times or 0.3 to 0.8 times the total thickness.

[0069] When the thickness of each second portion 42 is 0.1 times or more but less than 1.0 times the total thickness, each second portion 42 does not extend over the entire length of the middle core portion 4 in the thickness direction. In this case, each second portion 42 is provided at the center, both ends, or either end of the middle core portion 4 in the thickness direction. "Provided in the center in the thickness direction" refers to the first portion 41, the second portion 42, and the first portion 41 being arranged in this order in the Z1 direction on an X-Z cross section passing through the second portion 42. "Provided in the center in the thickness direction" as used herein not only includes cases where the center of the thickness of the middle core portion 4 coincides with the center of the thickness of the second portion 42, but also includes cases where the center of the thickness of the middle core portion 4 does not coincide with the center of the thickness of the second portion 42. "Provided at both ends in the thickness direction" refers to the second portion 42, the first portion 41, and the second portion 42 being arranged in this order in the Z1 direction on an X-Z cross section passing through the second portion 42. The term "provided at either end in the direction along the thickness" refers to either the third arrangement form or the fourth arrangement form. The third arrangement form refers to an arrangement in which the second portion 42 and the first portion 41 are arranged in this order toward the Z1 direction in an X-Z cross section passing through the second portion 42. The fourth arrangement form refers to an arrangement in which the first portion 41 and the second portion 42 are arranged in this order toward the Z1 direction in an X-Z cross section passing through the second portion 42.

[0070] When the thickness of each second portion 42 is 1 time the total thickness, the second portion 42 extends over the entire length in the direction along the thickness of the middle core portion 4. In this case, the width of each second portion 42 is, for example, 0.1 to 0.9 times the total width of the middle core portion 4.

[0071] The length of each second portion 42 is, for example, 0.05 to 0.45 times the overall length of the middle core portion 4. If the length of each second portion 42 is 0.05 times or more the overall length, leakage magnetic flux is likely to be reduced. If the length of each second portion 42 is 0.45 times or less the overall length, the proportion of the first portion 41 in the middle core portion 4 is likely to be high. Therefore, the reactor 1 is less likely to experience magnetic saturation due to the inclusion of the second portions 42, and therefore is likely to maintain high inductance even in a high-current operating environment. The length of each second portion 42 may be, for example, 0.1 to 0.4 times or 0.15 to 0.35 times the overall length.

[0072] Each second portion 42 in this example is located at the center in the width direction of the middle core portion 4 in an X-Y cross section passing through the second portion 42, and at the center in the thickness direction of the middle core portion 4 in an X-Z cross section passing through the second portion 42. That is, the first end portion 4a and the second end portion 4b of the middle core portion 4 in this example are arranged in the order of first portion 41, second portion 42, and first portion 41 in the Y1 direction in an X-Y cross section passing through the second portion 42, and are arranged in the order of first portion 41, second portion 42, and first portion 41 in the Z1 direction in an X-Z cross section passing through the second portion 42.

[0073] Unlike this example, each second portion 42 may extend over the entire length in the direction along the width of the middle core portion 4, provided that the thickness of each second portion 42 is less than 1.0 times the total thickness of the middle core portion 4 and the thickness of each second portion 42 is located in the center in the direction along the thickness of the middle core portion 4.

[0074] (Side Core Portion) As shown in Figures 1, 3, and 5, the side core portion 5 is arranged in parallel with the middle core portion 4 without the coil 2 being disposed therein. In Figure 2, for convenience of explanation, the side core portion 5 is shown separated from the first end core portion 6 and the second end core portion 7, but in reality, the side core portion 5 is formed continuous with the first end core portion 6 and the second end core portion 7. The side core portion 5 is formed from a single member. In this example, the side core portion 5 is formed from a first portion made of the same material as the first portion 41 of the middle core portion 4.

[0075] The side core portion 5 has a quadrangular prism shape. As shown in Fig. 5, the outer peripheral shape of the side core portion 5 is rectangular when viewed from the X1 direction. Although the four corners of the outer peripheral shape of the side core portion 5 shown in Fig. 5 are angular, they may be rounded. As shown in Fig. 1, the length of the side core portion 5 in the X1 direction is the same as the length of the middle core portion 4 in the X1 direction.

[0076] In this example, the width of the side core portions 5 is smaller than the thickness of the side core portions 5. Unlike this example, the width of the side core portions 5 may be equal to or greater than the thickness of the side core portions 5. The thickness of the side core portions 5 in this example is greater than the thickness of the middle core portion 4. Unlike this example, the thickness of the side core portions 5 may be equal to the thickness of the middle core portion 4. The thickness of the side core portions 5 in this example is the same as the thickness of the first end core portions 6 and the second end core portions 7. Unlike this example, the thickness of the side core portions 5 may be smaller or greater than the thickness of the first end core portions 6 and the second end core portions 7.

[0077] (First end core portion and second end core portion) The first end core portion 6 connects first ends of the middle core portion 4 and the side core portion 5. The second end core portion 7 connects second ends of the middle core portion 4 and the side core portion 5. The first end core portion 6 and the second end core portion 7 have the same shape. The first end core portion 6 and the second end core portion 7 are shaped like square pillars.

[0078] As shown in Figures 1 and 2, the planar shapes of the first end core portion 6 and the second end core portion 7 are trapezoidal, with the width narrowing from the first end face to the second end face of the first end core portion 6 and the second end core portion 7. The first end face of the first end core portion 6 is a surface facing the X2 direction. The first end face of the second end core portion 7 is a surface facing the X1 direction. The first end faces of the first end core portion 6 and the second end core portion 7 are surfaces facing the middle core portion 4 and the side core portion 5. The second end face of the first end core portion 6 is a surface facing the X1 direction. The second end face of the second end core portion 7 is a surface facing the X2 direction.

[0079] In this example, as shown in Figure 5, the outer circumferential shape of the second end core portion 7 when viewed from the X1 direction is rectangular. The width of the second end core portion 7 is greater than the thickness of the second end core portion 7. Although not shown in the figure, the outer circumferential shape of the first end core portion 6 when viewed from the X2 direction is also rectangular. The width of the first end core portion 6 is the same as the width of the second end core portion 7. The thickness of the first end core portion 6 is the same as the thickness of the second end core portion 7. In other words, the width of the first end core portion 6 is greater than the thickness of the first end core portion 6.

[0080] The first end core portion 6 and the second end core portion 7 have first portions 61, 71 connected to the first portion 41 of the middle core portion 4, and second portions 62, 72 connected to the second portion 42 of the middle core portion 4. The relative permeability of the second portions 62, 72 is greater than the relative permeability of the first portions 61, 71. In this example, the first portions 61, 71 are made of the same material as the first portion 41. In this example, the second portions 62, 72 are made of the same material as the second portion 42. Because the first end core portion 6 and the second end core portion 7 have the same configuration, the following description will be given using the first end core portion 6 as an example.

[0081] In this example, the second portion 62 is provided at the center in the thickness direction of the first end core portion 6. "Provided at the center in the thickness direction" means that, in an X-Z cross section passing through the second portion 62, the first portion 61, the second portion 62, and the first portion 61 are arranged in this order toward the Z1 direction. "Provided at the center in the thickness direction" as used here not only includes a case where the center of the thickness of the first end core portion 6 coincides with the center of the thickness of the second portion 62, but also a case where the center of the thickness of the first end core portion 6 does not coincide with the center of the thickness of the second portion 62. In this example, the planar shape of the integrated body of the second portion 42 and the second portion 62 is T-shaped.

[0082] As shown in FIG. 3 , the second portion 62 in this example has an overlapping portion 62a and an extending portion 62b. As shown in FIGS. 3 and 4 , the overlapping portion 62a is a portion that overlaps with the second portion 42 when viewed from the X1 direction. The overlapping portion 62a is connected to the second portion 42. The width and thickness of the overlapping portion 62a are the same as those of the second portion 42. As shown in FIG. 3 , the extending portion 62b is a portion that extends from the overlapping portion 62a in the Y1 direction or the Y2 direction without overlapping with the second portion 42 when viewed from the X1 direction. The extending portion 62b in this example has a first extending portion 62b extending from the overlapping portion 62a in the Y1 direction and a second extending portion 62b extending in the Y2 direction. Unlike this example, the extension portion 62b may not have the second extension portion 62b and may be composed of only the first extension portion 62b, or may not have the first extension portion 62b and may be composed of only the second extension portion 62b.

[0083] When viewed from the X1 direction, the first extension portion 62b may be provided so as to overlap only the first portion 41 located at the end in the Y1 direction, or so as to overlap both the first portion 41 located at the end in the Y1 direction and the coil 2. When viewed from the X1 direction, the second extension portion 62b may be provided so as to overlap only the first portion 41 located at the end in the Y2 direction, or so as to overlap both the first portion 41 located at the end in the Y2 direction and the coil 2. When viewed from the X1 direction, the second extension portion 62b may be provided so as to extend between the coil 2 and the side core portion 5 in the Y2 direction, or so as to extend to a portion overlapping the side core portion 5.

[0084] When viewed from the X1 direction, the first extension portion 62b in this example is provided so as to overlap both the first portion 41 located at the end in the Y1 direction and the coil 2. When viewed from the X1 direction, the second extension portion 62b in this example is provided so as to extend to a position overlapping with the side core portion 5.

[0085] The width of the second portion 62 is, for example, 0.1 to 0.9 times the overall width of the first end core portion 6. That is, the second portion 62 does not extend over the entire width of the first end core portion 6. The overall width refers to the maximum length along the width of the first end core portion 6. In this example, the maximum length is the width of the first end face. Therefore, the width of the second portion 62 in this example is 0.1 to 0.9 times the width of the first end face. If the width of the second portion 62 is 0.1 times or more the overall width, leakage magnetic flux is likely to be reduced. If the width of the second portion 62 is 0.9 times or less the overall width, the proportion of the first portion 61 in the first end core portion 6 is likely to be high. Therefore, the reactor 1 is less likely to experience magnetic saturation due to the inclusion of the second portion 62, and therefore is likely to maintain high inductance even in a high-current operating environment. Furthermore, the joining area between the first portion 61 and the first portion 41 of the middle core portion 4 is likely to become large. The width of the second portion 62 may be 0.2 to 0.8 times, or 0.3 to 0.7 times, the total width.

[0086] When the second portion 62 has an overlapping portion 62a and an extending portion 62b as in this example, the total width of the overlapping portion 62a and the extending portion 62b satisfies the above range. The widths of the overlapping portion 62a and the extending portion 62b refer to the maximum length along the width of each portion. The width of the extending portion 62b may be the same as the width of the overlapping portion 62a, or may be smaller or larger than the width of the overlapping portion 62a.

[0087] As shown in FIG. 4 , the thickness of the second portion 62 is, for example, 0.1 to 0.9 times the total thickness of the first end core portion 6. That is, the second portion 62 does not extend over the entire length of the first end core portion 6 in the thickness direction. If the thickness of the second portion 62 is 0.1 times or more the total thickness, leakage magnetic flux is likely to be reduced. If the thickness of the second portion 62 is 0.9 times or less the total thickness, the proportion of the first portion 61 in the first end core portion 6 is likely to be large. Therefore, the reactor 1 is less likely to experience magnetic saturation due to the inclusion of the second portion 62, and therefore is likely to maintain high inductance even in a high-current operating environment. Furthermore, the joint area between the first portion 61 and the first portion 41 is likely to be large. Therefore, the first end core portion 6 and the middle core portion 4 are likely to be well joined. The thickness of the second portion 62 may be 0.2 to 0.8 times or 0.3 to 0.7 times the total thickness.

[0088] When the second portion 62 has an overlapping portion 62 a and an extending portion 62 b as in this example, the thickness of each of the overlapping portion 62 a and the extending portion 62 b satisfies the above-mentioned range. The thickness of the extending portion 62 b may be the same as the thickness of the overlapping portion 62 a, or may be smaller or larger than the thickness of the overlapping portion 62 a.

[0089] As shown in Fig. 3, the length of the second portion 62 is, for example, 0.1 to 1.0 times the total length of the first end core portion 6. If the length of the second portion 62 is 0.1 times or more the total length, leakage magnetic flux is likely to be reduced. If the length of the second portion 62 is 1.0 times or less the total length, the proportion of the first portion 61 in the first end core portion 6 is likely to be large. Therefore, magnetic saturation due to the inclusion of the second portion 62 is unlikely to occur in the reactor 1, and high inductance is likely to be maintained even in a large current usage environment. The length of the second portion 62 may be 0.2 to 0.9 times or 0.3 to 0.8 times the total length.

[0090] When the second portion 62 has an overlapping portion 62a and an extension portion 62b as in this example, the lengths of the overlapping portion 62a and the extension portion 62b each satisfy the above range. The length of the overlapping portion 62a is, for example, 0.1 to 1.0 times the total length. If the length of the overlapping portion 62a is 0.1 times or more the total length, leakage magnetic flux is likely to be reduced. If the length of the overlapping portion 62a is 1.0 times or less the total length, the proportion of the first portion 61 in the first end core portion 6 is likely to be high. Therefore, the reactor 1 is less likely to experience magnetic saturation due to the inclusion of the second portion 62, and therefore is likely to maintain high inductance even in a high-current operating environment. The length of the overlapping portion 62a may be 0.2 to 0.9 times, or 0.3 to 0.8 times the total length. In this example, the length of the overlapping portion 62a is 1 time the total length. The length of the extension portion 62b may be the same as the length of the overlapping portion 62a, or may be shorter or longer than the length of the overlapping portion 62a. In this example, the length of the extension portion 62b is shorter than the length of the overlapping portion 62a.

[0091] (First Corner to Fourth Corner) The first corner 81 is a corner formed by the Y2-direction end of the first end 4a of the middle core portion 4 and the first end core portion 6. The second corner 82 is a corner formed by the Y2-direction end of the second end 4b of the middle core portion 4 and the second end core portion 7. The third corner 83 is a corner formed by the Y1-direction end of the first end of the side core portion 5 and the first end core portion 6. The fourth corner 84 is a corner formed by the Y1-direction end of the second end of the side core portion 5 and the second end core portion 7. In this example, the first corner 81 is formed by the first portions 41 and 61. The second corner 82 is formed by the first portions 41 and 71. The third corner 83 is formed by the first portion and the first portion 61 of the side core portion 5. The fourth corner 84 is formed by the first portion and the first portion 71 of the side core portion 5.

[0092] (Relative Permeability) As described above, the relative permeability of the second portions 42, 62, and 72 is greater than that of the first portions 41, 61, and 71. While satisfying the magnitude relationship of the relative permeabilities, the relative permeability of the first portions 41, 61, and 71 is, for example, 5 or greater and 50 or less, and the relative permeability of the second portions 42, 62, and 72 is, for example, 50 or greater and 500 or less. When the relative permeability of the first portions 41, 61, and 71 satisfies the upper and lower limits, magnetic saturation associated with the presence of the second portions 42, 62, and 72 is unlikely to occur, making it easier to maintain high inductance even in a high-current operating environment. When the relative permeability of the second portions 42, 62, and 72 satisfies the upper and lower limits, magnetic flux easily passes through the second portions 42, 62, and 72, making it easier to reduce leakage flux. The relative magnetic permeability of the first portions 41, 61, 71 may be 10 or more and 45 or less, or 15 or more and 40 or less. The relative magnetic permeability of the second portions 42, 62, 72 may be 55 or more and 450 or less, or 60 or more and 400 or less.

[0093] The relative permeability is determined as follows. Ring-shaped measurement samples are cut out from each of the first portions 41, 61, and 71 and the second portions 42, 62, and 72. Each measurement sample is wound with 300 turns on the primary side and 20 turns on the secondary side. The B-H initial magnetization curve is measured in the range of H = 0 (Oe) to 100 (Oe), and the maximum slope of this B-H initial magnetization curve is found, and this maximum value is taken as the relative permeability. The magnetization curve here is what is known as a DC magnetization curve.

[0094] (Material) The first portions 41, 61, 71 and the second portions 42, 62, 72 are formed of molded bodies having different relative magnetic permeabilities. The molded bodies are either powder compacts or composite material compacts. For example, even if the first portions 41, 61, 71 and the second portions 42, 62, 72 are formed of powder compacts, the relative magnetic permeabilities will be different if at least one of the material and content ratio of the soft magnetic powder constituting the powder compacts is different. Furthermore, even if the first portions 41, 61, 71 and the second portions 42, 62, 72 are formed of composite material compacts, the relative magnetic permeabilities will be different if at least one of the soft magnetic powder and resin constituting the composite material is made of a different material, or if the soft magnetic powder and resin are made of the same material but have different content ratios. Therefore, the first portions 41, 61, 71 and the second portions 42, 62, 72 may be formed from powder compacts, or the first portions 41, 61, 71 and the second portions 42, 62, 72 may be formed from a compact of a composite material, or the first portions 41, 61, 71 may be formed from a compact of a composite material and the second portions 42, 62, 72 may be formed from powder compacts. In this example, the first portions 41, 61, 71 are formed from a compact of the same composite material, and the second portions 42, 62, 72 are formed from the same powder compact.

[0095] The content of soft magnetic powder in the resin of a composite material compact can be easily adjusted. Therefore, the magnetic properties of the composite material compact can be easily adjusted. Furthermore, compared to a powder compact, a composite material compact can be easily formed into a complex shape. The content of soft magnetic powder in the composite material compact is, for example, 20% by volume or more and 80% by volume or less. The content of resin in the composite material compact is, for example, 20% by volume or more and 80% by volume or less. These content percentages are relative to the volume of the composite material compact taken as 100%.

[0096] Compared to a composite material compact, a powder compact can have a higher proportion of soft magnetic powder in the magnetic core 3. Therefore, the powder compact can easily improve its magnetic properties. The magnetic properties are at least one of relative permeability and saturation magnetic flux density. Furthermore, compared to a composite material compact, the powder compact has a lower amount of resin and a higher amount of soft magnetic powder, resulting in excellent heat dissipation. The soft magnetic powder content in the powder compact is, for example, 85% by volume or more and 99% by volume or less. This content is the ratio relative to the volume of the powder compact taken as 100%.

[0097] The particles constituting the soft magnetic powder are, for example, soft magnetic metal particles, coated particles, or soft magnetic non-metal particles. The coated particles include soft magnetic metal particles and an insulating coating provided on the outer periphery of the soft magnetic metal particles. The soft magnetic metal is, for example, pure iron or an iron-based alloy. The iron-based alloy is, for example, an Fe—Si alloy or an Fe—Ni alloy. The insulating coating is, for example, a phosphate. The soft magnetic non-metal is, for example, a ferrite.

[0098] The resin of the composite material molded body is, for example, a thermosetting resin or a thermoplastic resin. Examples of the thermosetting resin include epoxy resin, phenolic resin, silicone resin, and urethane resin. Examples of the thermoplastic resin include polyphenylene sulfide (PPS) resin, polyamide (PA) resin, liquid crystal polymer (LCP), polyimide resin, and fluororesin. Examples of the PA resin include nylon 6, nylon 66, and nylon 9T.

[0099] The composite material compact may contain a filler, such as a non-magnetic powder of alumina or silica, which contributes to improving heat dissipation and electrical insulation.

[0100] The content of the soft magnetic powder in the composite material compact and the content of the soft magnetic powder in the powder compact are considered to be equivalent to the area ratio of the soft magnetic powder in the cross section of the compact. The content of the soft magnetic powder in the compact is determined as follows. The cross section of the compact is observed with a SEM (scanning electron microscope) to obtain an observation image. The cross section of the compact is any cross section. The magnification of the SEM is 200 times or more and 500 times or less. The number of observation images obtained is 10 or more. The total cross section area is 0.1 cm ２ That's all. One observation image may be acquired per cross section, or multiple observation images may be acquired per cross section. Each acquired observation image is subjected to image processing to extract the particle contours. Image processing may be, for example, binarization processing. The area proportion of soft magnetic particles in each observation image is calculated, and the average value of these area proportions is determined. This average value is considered to be the content ratio of soft magnetic powder.

[0101] (Flow of Magnetic Flux) Magnetic flux passes through the middle core portion 4, first end core portion 6, side core portion 5, second end core portion 7, and middle core portion 4 in this order. The magnetic flux tends to pass through the second portion 42 and the overlapping portion 62a of the second portion 62 near the joint between the first end portion 4a and the first end core portion 6. Although the first corner portion 81 is formed by the first portions 41 and 61, the magnetic flux tends to be attracted to the second portion 42, the overlapping portion 62a, and the second extension portion 62b at the first corner portion 81. Although the third corner portion 83 is formed by the first portion and the first portion 61 of the side core portion 5, the second extension portion 62b of the first end core portion 6 is provided near the third corner portion 83. Therefore, the magnetic flux tends to be attracted to the second extension portion 62b at the third corner portion 83.

[0102] Although the fourth corner portion 84 is formed by the first portion and the first portion 71 of the side core portion 5, magnetic flux is likely to be attracted to the second extension portion 72b of the second portion 72 at the fourth corner portion 84. The magnetic flux is likely to pass through the second extension portion 72b, the overlapping portion 72a, and the second portion 42 near the joint between the second end core portion 7 and the second end 4b. Although the second corner portion 82 is formed by the first portions 41, 71, magnetic flux is likely to be attracted to the second extension portion 72b, the overlapping portion 72a, and the second portion 42 at the second corner portion 82.

[0103] Therefore, in the reactor 1 of this example, magnetic flux is less likely to leak from each joint.

[0104] [Manufacturing Method] The reactor 1 of this example is manufactured by carrying out the following steps α and β.

[0105] In step α, the coil 2, the first one-piece member, and the second one-piece member are placed in a mold. The first one-piece member is an integral member of the second portion 42 of the first end portion 4a of the middle core portion 4 and the second portion 62 of the first end core portion 6. The second one-piece member is an integral member of the second portion 42 of the second end portion 4b of the middle core portion 4 and the second portion 72 of the second end core portion 7. The first and second one-piece members in this example are powder compacts.

[0106] In step β, the raw material for the composite material compact is filled into the interior and exterior of the coil 2 in the mold. The exterior of the coil 2 in the mold includes the forming spaces for the side core portions 5, the forming spaces for the first end core portions 6, and the forming spaces for the second end core portions 7. The raw material is a fluid material in which soft magnetic powder is dispersed in unsolidified resin. When the filled raw material resin solidifies, the first portions 41 of the middle core portions 4, the side core portions 5, the first portions 61 of the first end core portions 6, and the first portions 71 of the second end core portions 7 are formed. The first portions 61 of the first end core portions 6 and the first portions 71 of the second end core portions 7 are integrated with the first portion 41 of the middle core portion 4, and the first portions 61 of the first end core portions 6 and the first portions 71 of the second end core portions 7 are integrated with the side core portions 5. The first portion 61 of the middle core portion 4 and the first end core portion 6 is integrated with the first integral body, and the first portion 71 of the middle core portion 4 and the second end core portion 7 is integrated with the second integral body.

[0107] Since the reactor 1 can be manufactured by carrying out the steps α and β, the reactor 1 has excellent productivity.

[0108] 6 to 8 , a reactor 1 of a second embodiment will be described. The reactor 1 of the second embodiment differs from the first embodiment in the location of the second portion 42 in the middle core portion 4 and the locations of the second portions 62, 72 in the first end core portion 6 and the second end core portion 7. The following description will focus on the differences from the first embodiment, and a description of the same configurations and effects as those of the first embodiment will be omitted. This also applies to a third embodiment described later.

[0109] (Middle core portion) The second portions 42 of the first end 4a and the second end 4b of the middle core portion 4 are located at both ends in the direction along the width of the middle core portion 4 in the X-Y cross section of the middle core portion 4, and at the center in the direction along the thickness of the middle core portion 4 in the X-Z cross section of the middle core portion 4.

[0110] (First end core portion and second end core portion) Because the first end core portion 6 and the second end core portion 7 have the same configuration, the following description will be given using the first end core portion 6 as an example. The first end core portion 6 has two second portions 62. The two second portions 62 are provided in the center of the thickness of the first end core portion 6. A first portion 61 is provided between the two second portions 62. This first portion 61 is connected to the first portion 41 of the first end 4a of the middle core portion 4. In this example, the planar shape of the unit formed by each second portion 42 and each second portion 62 is L-shaped.

[0111] One of the two second portions 62 is composed of an overlapping portion 62a that overlaps with the second portion 42 provided at the Y1-direction end of the middle core portion 4, and an extension portion 62b that extends in the Y1 direction from the overlapping portion 62a. The length of the overlapping portion 62a is less than 1.0 times the overall length of the first end core portion 6. As shown in FIG. 8 , the extension portion 62b extending in the Y1 direction is provided so as to overlap the coil 2 when viewed from the X1 direction. The length of the extension portion 62b extending in the Y1 direction is the same as the length of the overlapping portion 62a.

[0112] The remaining second portion 62 of the two second portions 62 is composed of an overlapping portion 62a that overlaps with the second portion 42 provided at the Y2-direction end of the middle core portion 4, and an extension portion 62b that extends in the Y2 direction from the overlapping portion 62a. The length of the overlapping portion 62a is less than 1.0 times the total length. The extension portion 62b extending in the Y2 direction does not reach a point that overlaps with the side core portion 5 when viewed from the X1 direction, and is provided so as to overlap the coil 2. The length of the extension portion 62b extending in the Y2 direction is the same as the length of the overlapping portion 62a.

[0113] (First Corner to Fourth Corner) The first corner 81 is formed by the second portions 42 and 62. The second corner 82 is formed by the second portions 42 and 72. The third corner 83 is formed by the first portion of the side core portion 5 and the first portion 61. The fourth corner 84 is formed by the first portion of the side core portion 5 and the first portion 71.

[0114] (Flow of Magnetic Flux) Near the joint between the first end 4a and the first end core portion 6, magnetic flux easily passes through the second portion 42, the overlapping portion 62a of the second portion 62, and the extension portion 62b extending in the Y2 direction. Because the first corner portion 81 is formed by the second portions 42 and 62, magnetic flux passing through the first corner portion 81 is less likely to leak. Near the joint, magnetic flux also easily passes through the second portion 42, the overlapping portion 62a of the second portion 62, and the extension portion 62b connected to the overlapping portion 62a. The third corner portion 83 is formed by the first portion and the first portion 61 of the side core portion 5, and no second portion is provided near the third corner portion 83 to attract magnetic flux passing through the third corner portion 83. However, magnetic flux is less likely to leak from the third corner portion 83 than from the first corner portion 81.

[0115] The fourth corner 84 is defined by the first portion and the first portion 71 of the side core portion 5, and there is no second portion near the fourth corner 84 to which magnetic flux is attracted. However, magnetic flux is less likely to leak from the fourth corner 84 than from the second corner 82. Near the joint between the second end core portion 7 and the second end 4b, magnetic flux tends to pass through the extension 72b extending in the Y2 direction, the overlapping portion 72a connected to the extension 72b, and the second portion 42 connected to the overlapping portion 72a. Because the second corner 82 is defined by the second portions 42, 72, magnetic flux passing through the second corner 82 is less likely to leak. In addition, magnetic flux tends to pass through the overlapping portion 72a and the second portion 42 at the end in the Y1 direction.

[0116] Therefore, in the reactor 1 of this example, magnetic flux is less likely to leak from each joint.

[0117] 9 to 11 , a reactor 1 of a third embodiment will be described. The reactor 1 of the third embodiment differs from the reactor 1 of the first embodiment in the location of the second portion 42 in the middle core portion 4 and the locations of the second portions 62, 72 in the first end core portion 6 and the second end core portion 7.

[0118] (Middle core portion) The second portions 42 of the first end 4a and the second end 4b of the middle core portion 4 are provided at either end in the width direction of the middle core portion 4 in the X-Y cross section of the middle core portion 4, and at the center in the thickness direction of the middle core portion 4 in the X-Z cross section of the middle core portion 4. In this example, each second portion 42 is provided at an end in the Y1 direction.

[0119] (First End Core Portion / Second End Core Portion) Because the first end core portion 6 and the second end core portion 7 have the same configuration, the following description will be given using the first end core portion 6 as an example. The second portion 62 of the first end core portion 6, which is connected to the second portion 42, is located at the center of the thickness of the first end core portion 6. In this example, the planar shape of the integrated body of the second portion 42 and the second portion 62 is L-shaped. The second portion 62 is composed of an overlapping portion 62a that overlaps the second portion 42 located at the Y1-direction end of the middle core portion 4, and an extension portion 62b that extends in the Y1 direction from the overlapping portion 62a. The length of the overlapping portion 62a is less than 1.0 times the overall length of the first end core portion 6. As shown in FIG. 11 , the extension portion 62b is located so as to overlap the coil 2 when viewed from the X1 direction. The length of the extension portion 62b is the same as the length of the overlapping portion 62a.

[0120] (First Corner to Fourth Corner) The first corner 81 is formed by the first portions 41 and 61. The second corner 82 is formed by the first portions 41 and 71. The third corner 83 is formed by the first portion of the side core portion 5 and the first portion 61. The fourth corner 84 is formed by the first portion of the side core portion 5 and the first portion 71.

[0121] (Flow of magnetic flux) Near the joint between the first end 4a and the first end core portion 6, magnetic flux easily passes through the second portion 42 and the overlapping portion 62a and extended portion 62b of the second portion 62. Although the first corner portion 81 is formed by the first portions 41 and 61, magnetic flux is more easily attracted to the second portion 42 than to the first corner portion 81. Therefore, magnetic flux passing through the first corner portion 81 is less likely to leak. The third corner portion 83 is formed by the first portion and the first portion 61 of the side core portion 5, and there is no second portion near the third corner portion 83 to which magnetic flux is attracted. However, magnetic flux is less likely to leak from the third corner portion 83 than from the first corner portion 81.

[0122] The fourth corner 84 is defined by the first portion and the first portion 71 of the side core portion 5, and there is no second portion near the fourth corner 84 to which magnetic flux is attracted. However, magnetic flux is less likely to leak from the fourth corner 84 than from the second corner 82. The magnetic flux tends to pass through the extension portion 72b, the overlapping portion 72a, and the second portion 42 near the joint between the second end core portion 7 and the second end 4b. Although the second corner 82 is defined by the first portions 41, 71, the magnetic flux is easily attracted to the overlapping portion 72a and the second portion 42. Therefore, the magnetic flux passing through the second corner 82 is less likely to leak.

[0123] Therefore, in the reactor 1 of this example, magnetic flux is less likely to leak from each joint.

[0124] Fourth Embodiment Converter / Power Conversion Apparatus The reactor 1 according to any one of the first to third embodiments can be used in applications that satisfy the following current-carrying conditions. The maximum DC current is, for example, about 100 A or more and 1000 A or less. The average voltage is, for example, about 100 V or more and 1000 V or less. The operating frequency is, for example, about 5 kHz or more and 100 kHz or less. The reactor 1 according to any one of the first to third embodiments can be used as a component of a converter mounted on a vehicle 1200, typically an electric vehicle, a hybrid vehicle, or a fuel cell vehicle, or as a component of a power conversion apparatus that includes this converter.

[0125] As shown in Fig. 12 , vehicle 1200 includes a main battery 1210, a power conversion device 1100 connected to main battery 1210, and a motor 1220 that is driven by power supplied from main battery 1210 and used for traveling. Motor 1220 is typically a three-phase AC motor. Motor 1220 drives wheels 1250 during traveling and functions as a generator during regeneration. In the case of a hybrid vehicle, vehicle 1200 includes an engine 1300 in addition to motor 1220. Although Fig. 12 shows an inlet as a charging point for vehicle 1200, a plug may also be provided.

[0126] The power conversion device 1100 includes a converter 1110 and an inverter 1120. The converter 1110 is connected to a main battery 1210. The inverter 1120 is connected to the converter 1110. The inverter 1120 converts DC to AC and vice versa. The converter 1110 shown in this example boosts the input voltage of the main battery 1210, which is approximately 200 V to 300 V, to approximately 400 V to 700 V during vehicle 1200 travel, and supplies the voltage to the inverter 1120. During regeneration, the converter 1110 reduces the input voltage output from the motor 1220 via the inverter 1120 to a DC voltage suitable for the main battery 1210, and charges the main battery 1210. The input voltage is a DC voltage. During vehicle 1200 travel, the inverter 1120 converts the DC voltage boosted by the converter 1110 into a predetermined AC voltage and supplies the AC voltage to the motor 1220. During regeneration, inverter 1120 converts AC output from motor 1220 into DC and outputs it to converter 1110 .

[0127] As shown in FIG. 13 , the converter 1110 includes a plurality of switching elements 1111, a drive circuit 1112 that controls the operation of the switching elements 1111, and a reactor 1115. The converter 1110 converts the input voltage by repeatedly switching the switching elements 1111 on and off. The conversion of the input voltage here refers to boosting and bucking the voltage. The switching elements 1111 are power devices such as field-effect transistors and insulated gate bipolar transistors. The reactor 1115 utilizes the properties of a coil that hinders changes in current flowing through a circuit, and has the function of smoothing changes when the current increases or decreases due to switching operations. The reactor 1115 includes the reactor 1 of any one of the first to third embodiments. The power conversion device 1100 and the converter 1110 that include the reactor 1 have low loss.

[0128] In addition to converter 1110, vehicle 1200 also includes a power supply converter 1150 and an auxiliary power supply converter 1160. Power supply converter 1150 is connected to main battery 1210. Auxiliary power supply converter 1160 is connected to main battery 1210 and sub-battery 1230, which serves as a power source for auxiliary equipment 1240. Auxiliary power supply converter 1160 converts the high voltage of main battery 1210 to a low voltage. Converter 1110 typically performs DC-DC conversion, while power supply converter 1150 and auxiliary power supply converter 1160 perform AC-DC conversion. Some power supply converters 1150 perform DC-DC conversion. The reactors of power supply converter 1150 and auxiliary power supply converter 1160 may have the same configuration as reactor 1 of any of embodiments 1 to 3, but may be reactors whose size, shape, etc. are appropriately modified. Furthermore, the reactor 1 according to any one of the first to third embodiments can also be used in a converter that converts input power, such as a converter that only boosts voltage or a converter that only bucks voltage.

[0129] The present invention is not limited to these examples, but is defined by the scope of the claims, and is intended to include all modifications within the meaning and scope of the claims. For example, the first end core portion and the second end core portion may have extension portions extending outward from the overlap portion in a direction along the thickness of each of the first end core portion and the second end core portion.

[0130] REFERENCE SIGNS LIST 1 Reactor, 2 Coil, 3 Magnetic core 4 Middle core portion 4a First end portion, 4b Second end portion, 41 First portion, 42 Second portion 5 Side core portion 6 First end core portion 61 First portion, 62 Second portion, 62a Overlapping portion, 62b Extension portion 7 Second end core portion 71 First portion, 72 Second portion, 72a Overlapping portion, 72b Extension portion 81 First corner portion, 82 Second corner portion, 83 Third corner portion, 84 Fourth corner portion 1100 Power conversion device, 1110 Converter 1111 Switching element, 1112 Drive circuit 1115 Reactor, 1120 Inverter 1150 Converter for power supply device, 1160 Converter for auxiliary power supply 1200 Vehicle, 1210 Main battery, 1220 Motor 1230 Sub-battery, 1240 Auxiliary equipment 1250 Wheels, 1300 Engine

Claims

1. A reactor comprising: a coil; and a magnetic core having an annular planar shape, wherein the magnetic core has: a middle core portion arranged inside the coil; and first and second end core portions arranged facing first and second end faces of the coil so as to be connected to first and second end faces of the middle core portion, respectively; the outer peripheral surface of the coil has a portion exposed from the magnetic core; each of the first and second end portions has a first portion and a second portion having a higher relative permeability than the first portion; the first and second end core portions have a first portion connected to the first portion and a second portion connected to the second portion; and the relative permeability of the second portions of the first and second end core portions is higher than the relative permeability of the first portions of the first and second end core portions.

2. The reactor according to claim 1, wherein the relative permeability of the second portion is 50 or more and 500 or less.

3. The reactor according to claim 2, wherein the relative permeability of the first portion is 5 or more and 50 or less.

4. The reactor according to claim 1, wherein the second portion is made of a compacted body of soft magnetic powder.

5. The reactor according to claim 4, wherein the first portion is formed from a molded body of a composite material in which soft magnetic powder is dispersed in a resin.

6. The reactor according to claim 5, wherein each of the second portions of the middle core portion is provided at the center in a direction along the width of each of the first end portion and the second end portion.

7. The reactor according to claim 5, wherein each of the second portions of the middle core portion is provided at both ends in a direction along the width of each of the first end portion and the second end portion.

8. The reactor according to claim 5, wherein each of the second portions of the middle core portion is provided at either end in a direction along the width of each of the first end portion and the second end portion.

9. The reactor according to claim 5, wherein the second portion of each of the first end core portion and the second end core portion is provided at the center of the thickness of each of the first end core portion and the second end core portion.

10. The reactor described in claim 5, wherein each of the second portions of the middle core portion is located at the center in the width direction and the thickness direction of each of the first end and second end portions, and the second portion of each of the first end core portion and the second end core portion has, when viewed in the axial direction of the coil, an overlapping portion that overlaps with the second portion of the middle core portion, and an extension portion that extends from the overlapping portion toward the outside in the width direction of each of the first end core portion and the second end core portion without overlapping with the second portion of the middle core portion, and each of the overlapping portions is connected to each of the second portions of the middle core portion.

11. The reactor described in claim 5, wherein each of the second portions of the middle core portion is provided at both ends of each of the first end portion and the second end portion in a direction along the width and at the center in a direction along the thickness, and the second portion of each of the first end core portion and the second end core portion, when viewed in the axial direction of the coil, has an overlapping portion that overlaps with the second portion of the middle core portion, and an extension portion that extends from the overlapping portion toward the outside in a direction along the width of each of the first end core portion and the second end core portion without overlapping with the second portion of the middle core portion, and each of the overlapping portions is connected to each of the second portions of the middle core portion.

12. The reactor described in claim 5, wherein each of the second portions of the middle core portion is provided at either end in a direction along the width of each of the first end portion and the second end portion and at the center in a direction along the thickness, and the second portion of each of the first end core portion and the second end core portion, when viewed in the axial direction of the coil, has an overlapping portion that overlaps with the second portion of the middle core portion and an extension portion that extends from the overlapping portion toward the outside in a direction along the width of each of the first end core portion and the second end core portion without overlapping with the second portion of the middle core portion, and each of the overlapping portions is connected to each of the second portions of the middle core portion.

13. A reactor according to any one of claims 6 to 12, wherein the width of each of the second portions of the middle core portion is 0.1 to 0.9 times the overall width of the middle core portion.

14. A reactor according to any one of claims 6 to 12, wherein the thickness of each of the second portions of the middle core portion is 0.1 to 1.0 times the total thickness of the middle core portion.

15. A reactor according to any one of claims 6 to 12, wherein the length of each of the second portions of the middle core portion is 0.05 to 0.45 times the overall length of the middle core portion.

16. A reactor as described in any one of claims 6 to 12, wherein the thickness of the second portion of each of the first end core portion and the second end core portion is 0.1 to 0.9 times the total thickness of each of the first end core portion and the second end core portion.

17. A converter comprising the reactor according to any one of claims 1 to 5.

18. A power conversion device comprising the converter according to claim 17.

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