Core piece, reactor, converter, and power conversion device

Abstract

Provided is a core piece for constituting a magnetic core disposed inside and outside a coil, the core piece comprising: a first block part disposed so as to face an end face of the coil; and a plurality of second block parts that have side faces facing either an inner side face or an outer side face of the coil, and that are disposed so that the side faces face each other. The first block part comprises a first part composed of a powder compact of soft magnetic powder, and a second part composed of a molded body of a composite material in which soft magnetic powder is dispersed in a resin. The first part and the second part overlap in a direction along the height of the first block part. The ratio of the height of the first part to the height of the first block part is more than 0.5 and less than 1.

Description

Core piece, reactor, converter, and power conversion device

[0001] This disclosure relates to a core piece, a reactor, a converter, and a power conversion device. This application claims priority based on Japanese Patent Application No. 2023-096753 filed on June 13, 2023, and incorporates by reference all of the contents of that application.

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

[0003] JP 2022-45166 A

[0004] The core pieces disclosed herein are core pieces for constituting a magnetic core arranged inside and outside a coil, and include a first block portion arranged to face an end face of the coil, and multiple second block portions having side faces facing either the inner or outer surface of the coil, the side faces facing each other. The first block portion includes a first section formed of a pressed compact of soft magnetic powder, and a second section formed of a compact of a composite material in which soft magnetic powder is dispersed in resin. The first section and the second section overlap in a direction along the height of the first block portion. The ratio of the height of the first section to the height of the first block portion is greater than 0.5 and less than 1. The height of the first block portion and the height of the first section are each lengths along a direction perpendicular to both the axis of the coil and the direction in which the multiple second block portions are arranged.

[0005] FIG. 1 is a schematic perspective view showing a core lamination of a first embodiment. FIG. 2 is a schematic perspective view of an exploded core lamination of the first embodiment. FIG. 3 is a schematic perspective view showing a core lamination of a second embodiment. FIG. 4 is a schematic perspective view showing a core lamination of a third embodiment. FIG. 5 is a schematic perspective view showing a core lamination of a fourth embodiment. FIG. 6 is a schematic perspective view showing a reactor of a fifth embodiment. FIG. 7 is a schematic diagram showing the flow of magnetic flux in a magnetic core of a reactor of a fifth embodiment. FIG. 8 is a schematic plan view showing a magnetic core of a reactor of a sixth embodiment. FIG. 9 is a schematic plan view showing a magnetic core of a reactor of a seventh embodiment. FIG. 10 is a configuration diagram schematically showing a power supply system of a hybrid vehicle. FIG. 11 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 under 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] One object of the present disclosure is to provide a core piece that can be used to manufacture a reactor having a first portion and a second portion made of different materials that are well joined and that maintains high inductance and low loss even in a high-current operating environment. Another object of the present disclosure is to provide a reactor that includes the core piece. Another object of the present disclosure is to provide a converter that includes the reactor. Another object of the present disclosure is to provide a power conversion device that includes the converter.

[0008] [Effects of the Present Disclosure] The core piece of the present disclosure is formed by favorably joining a first portion and a second portion made of different materials, and can be used to manufacture a reactor that maintains high inductance and low loss even in a high-current usage environment.

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

[0010] (1) A core piece according to an embodiment of the present disclosure is a core piece for constituting a magnetic core disposed inside and outside a coil, and includes a first block portion disposed to face an end face of the coil, and a plurality of second block portions having side faces facing either the inner or outer surface of the coil and disposed so that the side faces face each other. The first block portion includes a first section formed of a compact of soft magnetic powder, and a second section formed of a compact of a composite material in which soft magnetic powder is dispersed in resin. The first section and the second section overlap in a direction along the height of the first block portion. The ratio of the height of the first section to the height of the first block portion is greater than 0.5 and less than 1. The height of the first block portion and the height of the first section are each lengths along a direction perpendicular to both the axis of the coil and the direction in which the plurality of second block portions are arranged.

[0011] The core pieces described above enable the manufacture of reactors that maintain high inductance and low loss even in high-current operating environments. Powder compacts have higher magnetic permeability than compacts made of composite materials. When the first section made of the powder compact is positioned within a predetermined height range of the first block section, leakage magnetic flux from the first block section is likely to be reduced, making it less likely for loss to worsen. On the other hand, powder compacts are prone to magnetic saturation. Because the first block section is positioned facing the end face of the coil, in other words, the first block section is positioned outside the coil, the effect of the powder compact positioned in this first block section on magnetic saturation is relatively small, allowing high inductance to be maintained. Because the first section and the second section overlap in the direction along the height of the first block section, they are well joined over a relatively large surface area.

[0012] (2) In the core piece described in (1) above, the plurality of second block portions may be formed of a molded body of the composite material so as to be continuous with the second region.

[0013] When the second block portion is formed from a composite material molded body, the gap provided in the second block portion can be small. For example, if the gap of the second block portion placed in the coil is small, leakage flux from the gap is small, and loss is less likely to increase. Because the composite material molded body is configured so that the second portion of the first block portion and the second block portion are continuous, the first block portion and the second block portion are firmly bonded to each other. When the first block portion and the second block portion are firmly bonded to each other, the first block portion and the second block portion can be easily handled as a single unit.

[0014] (3) In the core piece described in (1) or (2) above, the first block portion may have a first surface and a second surface facing each other in a direction along the height of the first block portion, the first portion may have the first surface, and the second portion may have the second surface.

[0015] In the core piece (3) above, the first portion and the second portion can be easily arranged in the height direction of the first block portion.

[0016] (4) In the core piece according to any one of (1) to (3), the first and second portions may overlap in a direction along the thickness of the first block portion, and the ratio of the thickness of the first portion to the thickness of the first block portion may be 0.6 or more. Each of the thickness of the first block portion and the thickness of the first portion is a length along the axis of the coil.

[0017] When the first and second portions overlap in the direction along the thickness of the first block portion as well as the height of the first block portion, they are joined well over a relatively large surface. If the thickness ratio is 0.6 or more, leakage flux from the first block portion is likely to be reduced, and loss is unlikely to increase.

[0018] (5) In the core piece described in any one of (1) to (4) above, the first block portion may have an outer end surface facing outward in a direction along the axis of the coil, and the first portion may have the outer end surface.

[0019] In the core piece (5) above, the first portion and the second portion can be easily arranged in the thickness direction of the first block portion.

[0020] (6) A reactor according to an embodiment of the present disclosure comprises a magnetic core formed by combining first core pieces and second core pieces, and a coil arranged in a part of the magnetic core, and at least one of the first core pieces and the second core pieces is a core piece described in any one of (1) to (5) above.

[0021] A reactor equipped with a magnetic core including the core pieces described above maintains high inductance and low loss even in a large current operating environment.

[0022] (7) A converter according to an embodiment of the present disclosure includes the reactor described in (6) above.

[0023] A converter equipped with the reactor described above maintains high inductance and low loss even under conditions of high current usage.

[0024] (8) A power conversion device according to an embodiment of the present disclosure includes the converter described in (7) above.

[0025] A power conversion device including the converter described above maintains high inductance and low loss even under conditions of high current usage.

[0026] [Details of the Embodiments of the Present Disclosure] Specific examples 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 each drawing, for the convenience of explanation, some components may be exaggerated or simplified. The dimensional ratios of each part in the drawings may also differ from the actual ratios. Note that the present invention is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0027] <Embodiment 1> <Core Laminate> A core laminate 1α of embodiment 1 will be described with reference to FIGS. 1 and 2. The core laminate 1α is a component of a reactor 7 (FIG. 6), which will be described later. The core laminate 1α constitutes a magnetic core 8 disposed inside and outside a coil 9 (FIGS. 6 and 7) of the reactor 7. The core laminate 1α includes a first block portion 110 and a plurality of second block portions 120. The first block portion 110 is disposed outside the winding portion 90 (FIGS. 6 and 7) of the coil 9. One of the features of the core laminate 1α of embodiment 1 is that the first block portion 110 includes a first portion 11 and a second portion 12, and the first portion 11 is disposed within a predetermined height range of the first block portion 110. The first portion 11 is a portion formed by powder compaction. The second portion 12 is a portion formed by a composite material compact. In the core laminate 1α of embodiment 1, the plurality of second block portions 120 also include the second portion 12. The core piece 1α of the first embodiment is an integral piece formed by integrally molding a first block portion 110 and a plurality of second block portions 120. Below, the materials of the first portion 11 and the second portion 12 will be described first, and then the configurations of the first block portion 110 and the second block portion 120 will be described in order. In each drawing, the first portion 11 is cross-hatched for ease of understanding.

[0028] In the following description, the first direction D1, the second direction D2, and the third direction D3 may be used. The first direction D1 is the direction along the axis of the winding portion 90 of the coil 9 (FIGS. 6 and 7). The direction along the axis of the winding portion 90 is also the direction along the axis of the second block portion 120. The second direction D2 is the direction in which the multiple second block portions 120 are arranged. The third direction D3 is a direction perpendicular to both the first direction D1 and the second direction D2. The first direction D1, the second direction D2, and the third direction D3 are perpendicular to each other. In each figure, the first direction D1, the second direction D2, and the third direction D3 are each indicated by a single arrow. In the following description, the opposite directions of the first direction D1, the second direction D2, and the third direction D3 may also be referred to as the first direction D1, the second direction D2, and the third direction D3.

[0029] [First Region] The first region 11 is a region formed of a powder compact of soft magnetic powder. The powder compact is obtained by pressing raw material powder containing soft magnetic powder. The powder compact can have a higher content of soft magnetic powder in the compact compared to a compact of a composite material described below. A powder compact with a higher content of soft magnetic powder has high magnetic permeability. The content of soft magnetic powder in the powder compact is, for example, more than 80 volume %, 85 volume % or more, 90 volume % or more, or 95 volume % or more, when the powder compact is taken as 100 volume %. The raw material powder may contain a lubricant.

[0030] The soft magnetic powder is formed of, 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, ferrite.

[0031] [Second Region] The second region 12 is a region formed of a composite material compact in which soft magnetic powder is dispersed in resin. A composite material compact is manufactured by filling a mold with raw material in which soft magnetic powder is mixed and dispersed in unsolidified resin, and then solidifying the resin. The magnetic properties of the composite material, such as permeability or saturation magnetic flux density, can be easily reduced by adjusting the content of soft magnetic powder in the resin. In particular, the content of soft magnetic powder can be easily adjusted to be low, making it easy to reduce the permeability of the composite material. Although a composite material compact has lower permeability than a powder compact, it is less likely to become magnetically saturated under high-current operating conditions and has low iron loss. A composite material compact can be easily molded into complex shapes compared to a powder compact.

[0032] The soft magnetic powder forming the composite material compact is the same as the soft magnetic powder forming the powder compact described above. The content of the soft magnetic powder in the composite material compact is, for example, 20% by volume or more and 80% by volume or less, assuming the composite material to be 100% by volume.

[0033] The resin forming the composite material molded body is, for example, a thermosetting resin or a thermoplastic resin. Examples of thermosetting resins include epoxy resin, phenolic resin, silicone resin, and urethane resin. Examples of thermoplastic resins include polyphenylene sulfide (PPS) resin, polybutylene terephthalate (PBT), polyamide (PA) resin, liquid crystal polymer (LCP), polyimide (PI) resin, and fluororesin. Examples of polyamide resins include nylon 6, nylon 66, and nylon 9T. The resin content in the composite material molded body is, for example, 20% by volume or more and 80% by volume or less, assuming the composite material to be 100% by volume.

[0034] The composite material may contain a filler in addition to the resin. The filler contributes to improving heat dissipation. For example, a powder of a non-magnetic material such as ceramics or carbon nanotubes can be used as the filler. The ceramic is, for example, a metal or non-metal oxide, nitride, or carbide. An example of an oxide is alumina, silica, or magnesium oxide. An example of a nitride is silicon nitride, aluminum nitride, or boron nitride. An example of a carbide is silicon carbide.

[0035] [First Block Portion] The first block portion 110 is an area arranged to face an end surface 91 (FIGS. 6 and 7) of the winding portion 90 of the coil 9, which will be described later. The first block portion 110 may be referred to as an end core portion 5.

[0036] The first block portion 110 is disposed outside the winding portion 90 so as to connect the plurality of second block portions 120. The shape of the first block portion 110 may be any shape that connects the plurality of second block portions 120. In this example, the first block portion 110 is a rectangular block body.

[0037] The first block portion 110 includes a first portion 11 and a second portion 12. The first portion 11 and the second portion 12 overlap in a direction along the height of the first block portion 110. The direction along the height of the first block portion 110 is a third direction D3. The first block portion 110 includes a first surface 111 and a second surface 112 that face each other in the third direction D3. In this example, the first portion 11 includes the first surface 111, and the second portion 12 includes the second surface 112. The first portion 11 in this example is formed as a single block body that includes the first surface 111. The second portion 12 in this example covers the surface of the first portion 11 opposite the first surface 111. By covering the first portion 11, the second portion 12 includes the second surface 112.

[0038] The first block portion 110 has an outer end surface 113 facing outward in the first direction D1. In this example, the outer end surface 113 is composed of a first portion 11 and a second portion 12. In other words, each of the first portion 11 and the second portion 12 in this example is arranged to have the outer end surface 113. The first block portion 110 has two side surfaces 115 facing each other in the second direction D2. In this example, each side surface 115 is composed of the first portion 11 and the second portion 12. In other words, each of the first portion 11 and the second portion 12 in this example is arranged to have two side surfaces 115. In this example, the first portion 11 is composed of a single block body that includes the first surface 111, a portion of the outer end surface 113, and a portion of each of the two side surfaces 115.

[0039] The ratio H1 / H0 of the height H1 of the first portion 11 to the height H0 of the first block portion 110 is greater than 0.5 and less than 1. The height of the first block portion 110 and the height of the first portion 11 are each lengths along the third direction D3. As described above, a powder compact has a higher magnetic permeability than a compact made of a composite material. If the ratio H1 / H0 is greater than 0.5, the first portion 11 made of the powder compact will be arranged over a relatively wide area of ​​the first block portion 110. If the first portion 11 is arranged over a relatively wide area, leakage magnetic flux from the first block portion 110 is likely to be reduced, and loss is less likely to increase.

[0040] As described above, the powder compact is prone to magnetic saturation. However, because the first block portion 110 is disposed so as to face the end surface 91 (FIGS. 6 and 7) of the winding portion 90, in other words, the first block portion 110 is disposed outside the winding portion 90, the influence of the powder compact disposed on this first block portion 110 on magnetic saturation is relatively small. Therefore, the first block portion 110 can maintain a high inductance.

[0041] If the ratio H1 / H0 is less than 1, the first portion 11 and the second portion 12 are joined over a relatively large surface. In this example, the second portion 12 is joined over the entire surface of the first portion 11 opposite the first surface 111. If the ratio H1 / H0 is less than 1, the first portion 11 and the second portion 12 are joined to each other well.

[0042] The ratio H1 / H0 may be 0.6 or more and less than 1, 0.7 or more and less than 1, 0.8 or more and less than 1, or 0.8 or more and less than 0.9.

[0043] The second portion 12 of the first block portion 110 is connected to the second portion 12 of the second block portion 120, which will be described later. The second portion 12 of the first block portion 110 is a thin plate-like portion that protrudes from each second block portion 120. The second portion 12 of the first block portion 110 integrates the plurality of second block portions 120, which will be described later. The height of the second portion 12 of the first block portion 110 changes depending on the ratio H1 / H0.

[0044] The first portion 11 and the second portion 12 of the first block portion 110 may overlap in a direction along the thickness of the first block portion 110. The direction along the thickness of the first block portion 110 is a first direction D1. In this example, the first portion 11 and the second portion 12 of the first block portion 110 do not overlap in the direction along the thickness of the first block portion 110. In this example, the first portion 11 is disposed across the entire thickness of the first block portion 110. The ratio T1 / T0 of the thickness T1 of the first portion 11 to the thickness T0 of the first block portion 110 will be described in embodiment 3 with reference to FIG. 4 .

[0045] The first portion 11 and the second portion 12 of the first block portion 110 may overlap in the direction along the width of the first block portion 110. The direction along the width of the first block portion 110 is the second direction D2. In this example, the first portion 11 and the second portion 12 of the first block portion 110 do not overlap in the direction along the width of the first block portion 110. In this example, the first portion 11 is disposed across the entire width of the first block portion 110. The ratio W1 / W0 of the width W1 of the first portion 11 to the width W0 of the first block portion 110 will be described in embodiment 4 with reference to FIG. 5 .

[0046] [Second Block Portion] Each second block portion 120 is a region having a side surface 125 facing either the inner surface 92 or the outer surface 93 ( FIG. 7 ) of the winding portion 90. The multiple second block portions 120 are arranged so that the side surfaces 125 face each other. Each second block portion 120 has multiple side surfaces 125. In each second block portion 120, any one of the multiple side surfaces 125 may face the side surface 125 of an adjacent second block portion 120. The second block portion 120 arranged inside the winding portion 90 has the side surface 125 facing the inner surface 92 of the winding portion 90. The second block portion 120 arranged inside the winding portion 90 is sometimes referred to as a middle core portion 21. The second block portion 120 arranged outside the winding portion 90 has the side surface 125 facing the outer surface 93 of the winding portion 90. The second block portion 120 disposed outside the winding portion 90 may be referred to as a side core portion 31 , 41 .

[0047] The three second block portions 120 are connected to the same surface of one first block portion 110 and extend in the same direction. In each drawing, the boundaries between the first block portion 110 and each second block portion 120 are indicated by two-dot chain lines.

[0048] Of the multiple second block portions 120, the middle core portion 21 has a portion that is disposed inside the winding portion 90 (FIGS. 6 and 7). The middle core portion 21 is a portion that extends in a direction intersecting with the first block portion 110, and may have a portion that is disposed outside the winding portion 90. In other words, the middle core portion 21 may have a portion that is disposed inside the winding portion 90 and a portion that is disposed outside the winding portion 90. The shape of the middle core portion 21 roughly corresponds to the inner peripheral shape of the winding portion 90. In this example, the middle core portion 21 is a rectangular block body. The corners of the middle core portion 21 are rounded to fit the corners of the winding portion 90.

[0049] Of the multiple second block portions 120, two side core portions 31, 41 are arranged side by side with the middle core portion 21 outside the winding portion 90 ( FIGS. 6 and 7 ). The two side core portions 31, 41 are arranged to sandwich the middle core portion 21 with a gap between them. Each side core portion 31, 41 may have any shape as long as it is arranged side by side with the middle core portion 21. In this example, each side core portion 31, 41 is a rectangular block body. In this example, the two side core portions 31, 41 have the same shape and dimensions. In this example, the length of each side core portion 31, 41 along the first direction D1 is longer than the length of the middle core portion 21 along the first direction D1. The length of each side core portion 31, 41 along the first direction D1 may be the same as or shorter than the length of the middle core portion 21 along the first direction D1. In this example, the length of each side core portion 31, 41 along the second direction D2 is shorter than the length of the middle core portion 21 along the second direction D2. In this example, the total length of each side core portion 31, 41 along the second direction D2 is shorter than the length of the middle core portion 21 along the second direction D2. The total length of each side core portion 31, 41 along the second direction D2 may be equal to or greater than the length of the middle core portion 21 along the second direction D2. In this example, the length of each side core portion 31, 41 along the third direction D3 is the same as the length of the middle core portion 21 along the third direction D3. The length of each side core portion 31, 41 along the third direction D3 may be shorter or longer than the length of the middle core portion 21 along the third direction D3. The shapes and dimensions of the two side core portions 31, 41 may be different.

[0050] Each second block portion 120 includes at least the second portion 12. Each second block portion 120 may include only the second portion 12. At least one of the plurality of second block portions 120 may include the first portion 11 and the second portion 12.

[0051] The second portion 12 of each second block portion 120 is provided, for example, so as to be continuous with the second portion 12 of the first block portion 110. The second portion 12 of each second block portion 120 is, for example, a molded product with no joint between it and the second portion 12 of the first block portion 110. In this example, each second block portion 120 consists of only the second portion 12.

[0052] The second portion 12 of the first block portion 110 and the second portion 12 of each second block portion 120 may be formed of a molded body of the same composite material. The second portion 12 of the first block portion 110 and the second portion 12 of each second block portion 120 may include molded bodies of different composite materials. For example, the second portion 12 of the first block portion 110 and the second portion 12 of each second block portion 120 may be formed of molded bodies of different composite materials. Among the multiple second block portions 120, the second portion 12 of the middle core portion 21 arranged inside the winding portion 90 and the second portion 12 of the side core portions 31, 41 arranged outside the winding portion 90 may be formed of molded bodies of different composite materials. In this case, the second portion 12 of the first block portion 110 and the second portion 12 of the side core portions 31, 41 may be formed of molded bodies of the same composite material. For example, the portion disposed inside the winding portion 90 (FIGS. 6 and 7) and the portion disposed outside the winding portion 90 may be formed of molded bodies made of different composite materials.

[0053] "Different composite materials" means that the types and contents of the constituent materials of the composite materials are at least partially different. "Different types of constituent materials" means that the types of soft magnetic powder and the types of resin are different. "Different types of soft magnetic powder" means, for example, that the compositions of the soft magnetic powder are different. "Different contents of constituent materials" means that the contents of the soft magnetic powder in the resin are different.

[0054] When the second block portion 120 includes the first portion 11, the first portion 11 is provided, for example, so as to be continuous with the first portion 11 of the first block portion 110. The first portion 11 of the first block portion 110 and the first portion 11 of the second block portion 120 may be provided discontinuously. An embodiment in which the second block portion 120 includes the first portion 11 and the second portion 12 will be described in embodiment 7 with reference to FIG. 9 .

[0055] The core piece 1α of this example includes one first block portion 110 and three second block portions 120. The core piece 1α of this example has an E-shape configured by the one first block portion 110 and the three second block portions 120.

[0056] <<Method of Manufacturing Core Piece>> The above-described core piece 1α is manufactured by, for example, carrying out the following first, second, and third steps. The first, second, and third steps are carried out in this order.

[0057] [First Step] In the first step, a mold and partial core pieces are prepared. The mold has a first space and a plurality of second spaces that communicate with each other. The first space is a space for molding the first block portion 110 described above. Each second space is a space for molding the second block portion 120 described above. Each second space extends in a direction intersecting the first space and is arranged side by side with each other. The partial core pieces are compacts made of soft magnetic powder. The partial core pieces are the first portions 11 of the first block portion 110 described above.

[0058] [Second Step] In the second step, the partial core pieces are arranged in a part of the first space, and the remainder of the first space is an empty space with the partial core pieces arranged therein.

[0059] [Third Step] In the third step, a composite material having soft magnetic powder dispersed in resin is filled into the remaining first spaces and each second space so as to cover a portion of the partial core piece. When the composite material solidifies, it becomes the second portion 12 described above. When the composite material filled into the remaining first spaces so as to cover a portion of the partial core piece solidifies, it becomes the second portion 12 of the first block portion 110 described above. When the composite material filled into each second space solidifies, it becomes the second portion 12 of the second block portion 120 described above.

[0060] <Embodiment 2> A core piece 1β of embodiment 2 will be described with reference to Fig. 3. The core piece 1β of embodiment 2 differs from the core piece 1α of embodiment 1 in the overlapping location between the first portion 11 and the second portion 12 in the first block portion 110. The core piece 1β of embodiment 2 has the same configuration as the core piece 1α of embodiment 1 except for the overlapping location.

[0061] In the core piece 1β of this example, the second portion 12 of the first block portion 110 is arranged to sandwich the first portion 11 in the third direction D3. The first portion 11 of the first block portion 110 of this example does not include the first surface 111 or the second surface 112 of the first block portion 110. The first portion 11 of the first block portion 110 of this example is configured as a single block body that includes a portion of the outer end surface 113 of the first block portion 110 and portions of each of the two side surfaces 115. In this example, the second portion 12 of the first block portion 110 includes the first surface 111, the second surface 112, the remainder of the outer end surface 113, and the remainder of each of the two side surfaces 115.

[0062] In the core piece 1β of this example, the ratio H1 / H0 of the height H1 of the first portion 11 to the height H0 of the first block portion 110 is also greater than 0.5 and less than 1. When the ratio H1 / H0 is greater than 0.5, leakage magnetic flux from the first block portion 110 is likely to be reduced regardless of where the first portion 11 is located in the direction along the height of the first block portion 110, and loss is unlikely to increase.

[0063] When the first portion 11 is disposed between the second portions 12, the first portion 11 and the second portion 12 are more effectively bonded to each other. In this example, the entire surfaces of the two surfaces of the first portion 11 that face each other in the third direction D3 are bonded to the second portion 12.

[0064] <Embodiment 3> A core piece 1γ of embodiment 3 will be described with reference to Fig. 4. The core piece 1γ of embodiment 3 is different from the core piece 1α of embodiment 1 in the thickness T1 of the first portion 11 of the first block portion 110. The core piece 1γ of embodiment 3 has the same configuration as the core piece 1α of embodiment 1, except for the thickness T1 of the first portion 11.

[0065] In the core piece 1γ of this example, the first portion 11 and the second portion 12 of the first block portion 110 overlap not only in the direction along the height of the first block portion 110 but also in the direction along the thickness thereof.

[0066] In this example, the second portion 12 of the first block portion 110 includes a connecting portion 12A and a flange portion 12B. The connecting portion 12A is a plate-like member provided to connect multiple second block portions 120. Each second block portion 120 is connected to the same surface of the connecting portion 12A. A portion of the connecting portion 12A overlaps the first portion 11 in a direction along the thickness of the first block portion 110. The flange portion 12B is a plate-like member provided to protrude from the connecting portion 12A in the first direction D1. The flange portion 12B overlaps the first portion 11 in a direction along the height of the first block portion 110.

[0067] The ratio T1 / T0 of the thickness T1 of the first portion 11 to the thickness T0 of the first block portion 110 is, for example, 0.6 or more. The thickness T0 of the first block portion 110 includes the thickness of the connecting portion 12A and the protruding length of the flange portion 12B. The thickness of the connecting portion 12A is the length obtained by subtracting the thickness T1 from the thickness T0 shown in FIG. 4. The thickness of the connecting portion 12A may be as thin as a thin film. The dashed line shown in FIG. 4 indicates the boundary between the connecting portion 12A and the flange portion 12B. The thickness of the connecting portion 12A is the length between the dashed line and the two-dot chain line shown in FIG. 4. If the ratio T1 / T0 is 0.6 or more, the first portion 11 made of a powder compact is disposed over a relatively wide area of ​​the first block portion 110. If the first portion 11 is disposed over a relatively wide area, leakage magnetic flux from the first block portion 110 is likely to be reduced, and loss is less likely to increase.

[0068] The ratio T1 / T0 may be 0.6 or more and 1 or less, 0.65 or more and 1 or less, 0.7 or more and 1 or less, 0.8 or more and 1 or less, 0.9 or more and 1 or less, or 1. When the ratio T1 / T0 is 1, the first portion 11 is disposed throughout the entire thickness of the first block portion 110, as shown in FIG.

[0069] The ratio T1 / T0 may be less than 1. If the ratio T1 / T0 is less than 1, the first portion 11 and the second portion 12 are joined over a relatively large surface area. If the ratio T1 / T0 is less than 1, the first portion 11 and the second portion 12 are joined to each other well.

[0070] The ratio T1 / T0 may be 0.6 or more and less than 1, 0.65 or more and less than 1, 0.7 or more and less than 1, or 0.8 or more and less than 0.9.

[0071] <Fourth Embodiment> A core piece 1δ of a fourth embodiment will be described with reference to Fig. 5. The core piece 1δ of the fourth embodiment differs from the core piece 1α of the first embodiment in the width W1 of the first portion 11 of the first block portion 110. The core piece 1δ of the fourth embodiment has the same configuration as the core piece 1α of the first embodiment, except for the width W1 of the first portion 11. For ease of explanation, Fig. 5 shows the core piece 1δ from a different direction than Fig. 1.

[0072] In the core piece 1δ of this example, the first portion 11 and the second portion 12 of the first block portion 110 also overlap in the direction along the width of the first block portion 110. The first portion 11 comprises a portion of the first surface 111 and a portion of the outer end surface 113 of the first block portion 110. The first portion 11 does not comprise a side surface 115. The second portion 12 covers the side surfaces of the first portion 11, thereby comprising the two side surfaces 115 of the first block portion 110. The second portion 12 also comprises the second surface 112 of the first block portion 110, the remainder of the first surface 111, and the remainder of the outer end surface 113.

[0073] The ratio W1 / W0 of the width W1 of the first portion 11 to the width W0 of the first block portion 110 is, for example, 0.3 or more. In this example, the corners of the first portion 11 are rounded. In this case, the width W1 of the first portion 11 is the widest width. If the ratio W1 / W0 is 0.3 or more, the first portion 11 made of a powder molded body is arranged over a relatively wide area of ​​the first block portion 110. If the first portion 11 is arranged over a relatively wide area, leakage magnetic flux from the first block portion 110 is likely to be reduced, and loss is less likely to increase.

[0074] The ratio W1 / W0 may be 0.3 or more and 1 or less, 0.4 or more and 1 or less, 0.5 or more and 1 or less, 0.6 or more and 1 or less, 0.7 or more and 1 or less, 0.8 or more and 1 or less, 0.9 or more and 1 or less, or 1. When the ratio W1 / W0 is 1, the first portion 11 is disposed across the entire width of the first block portion 110, as shown in FIG.

[0075] The ratio W1 / W0 may be less than 1. If the ratio W1 / W0 is less than 1, the first portion 11 and the second portion 12 are joined over a relatively large surface area. If the ratio W1 / W0 is less than 1, the first portion 11 and the second portion 12 are joined to each other well.

[0076] The ratio W1 / W0 may be 0.3 or more and less than 1, 0.4 or more and less than 1, 0.5 or more and less than 1, 0.6 or more and less than 1, 0.7 or more and less than 1, 0.8 or more and less than 1, or 0.8 or more and less than 0.9.

[0077] <Fifth Embodiment> <Reactor> A reactor 7 of the fifth embodiment will be described with reference to FIGS. 6 and 7 . The reactor 7 includes a magnetic core 8 and a coil 9. The magnetic core 8 is configured by combining first core laminations 81 and second core laminations 82. The first core laminations 81 and the second core laminations 82 are split laminations formed by dividing the magnetic core 8 so that the magnetic core 8 is separated in the first direction D1. The coil 9 is disposed in a portion of the magnetic core 8. One feature of the reactor 7 of the fifth embodiment is that at least one of the first core laminations 81 and the second core laminations 82 is the core laminations 1α of the first embodiment. At least one of the first core laminations 81 and the second core laminations 82 may be the core laminations 1β of the second embodiment, the core laminations 1γ of the third embodiment, or the core laminations 1δ of the fourth embodiment. In this example, both the first core laminations 81 and the second core laminations 82 are the core laminations 1α of the first embodiment. The first core laminations 81 and the second core laminations 82 are symmetrical with respect to the middle position of the magnetic core 8 in the first direction D1.

[0078] [Magnetic Core] The magnetic core 8 is a magnetic member for forming a circular magnetic path by excitation of the coil 9. The magnetic core 8 in this example is configured in an overall θ shape by combining first core pieces 81 and second core pieces 82.

[0079] The magnetic core 8 includes a middle core portion 2, two side core portions 3 and 4, and two end core portions 5 and 6. In Figures 6 and 7, the boundaries between the middle core portion 21 and the end core portion 5, and the boundaries between the side core portions 3 and 4 and the end core portion 5 are indicated by two-dot chain lines.

[0080] The middle core portion 2 has a portion disposed inside the winding portion 90 of the coil 9, which will be described later. In this example, the middle core portion 2 includes a middle core portion 21 of the first core lamination 81, a middle core portion 22 of the second core lamination 82, and a gap 2g. The middle core portions 21 and 22 are one of the multiple second block portions 120 of the core lamination 1α described above. The middle core portions 21 and 22 have the same length along the second direction D2. The middle core portions 21 and 22 have the same length along the third direction D3. The gap 2g is provided between the middle core portion 21 of the first core lamination 81 and the middle core portion 22 of the second core lamination 82. Providing the gap 2g makes it easy to adjust the inductance of the reactor 7. For example, a gap material (not shown) is disposed in the gap 2g. Known gap materials can be used for the gap material. The gap material can be formed from, for example, non-magnetic ceramics or resin. The gap 2g may be an air gap without a gap material. When the reactor 7 includes a molded resin portion (described later), the gap 2g may be filled with a resin that forms the molded resin portion. In this case, the resin that forms the molded resin portion serves as the gap material.

[0081] The length of the middle core portion 2 in the first direction D1 is equal to or greater than the length of the winding portion 90 in the first direction D1. In this example, the length of the middle core portion 2 in the first direction D1 is slightly longer than the length of the winding portion 90 in the first direction D1. In other words, the middle core portion 2 has a portion that is disposed inside the winding portion 90 and a portion that is disposed outside the winding portion 90. Both end portions of the middle core portion 2 are located outside the winding portion 90.

[0082] The side core portion 3 includes a side core portion 31 of the first core piece 81 and a side core portion 32 of the second core piece 82. The side core portions 31, 32 are one of the plurality of second block portions 120 of the core piece 1α described above. In this example, no gap is provided between the side core portions 31, 32. In other words, the end faces of the side core portions 31, 32 are in contact with each other. The side core portion 4 includes a side core portion 41 of the first core piece 81 and a side core portion 42 of the second core piece 82. The side core portions 41, 42 are one of the plurality of second block portions 120 of the core piece 1α described above. In this example, no gap is provided between the side core portions 41, 42. In other words, the end faces of the side core portions 41, 42 are in contact with each other.

[0083] The end core portions 5 and 6 are the first block portions 110 of the core piece 1α described above.

[0084] The magnetic core 8 is formed by connecting one middle core portion 2, two side core portions 3 and 4, and two end core portions 5 and 6, so that when a coil 9, which will be described later, is excited, magnetic flux flows and a closed magnetic circuit is formed. As shown by the dashed arrows in Figure 7, the magnetic flux flows from the middle core portion 2 to the end core portion 5, from the end core portion 5 to each of the two side core portions 3 and 4, from each of the side core portions 3 and 4 to the end core portion 6, and from the end core portion 6 to the middle core portion 2.

[0085] In this example, since both the first core laminations 81 and the second core laminations 82 are the core laminations 1α of the first embodiment, leakage flux from the end core portions 5 and 6 tends to be small, and loss is less likely to increase.

[0086] [Coil] The coil 9 has at least one winding portion 90. In this example, the coil 9 has one winding portion 90. The winding portion 90 is formed by spirally winding a single wire. Both ends of the wire are drawn out from the respective ends of the winding portion 90. Terminal fittings (not shown) are attached to both ends of the wire drawn out from the winding portion 90. An external device (not shown) is connected to the terminal fittings. In Figures 5 and 6, only the winding portion 90 is shown, and the ends of the wire are omitted.

[0087] The windings may be any known type of winding. The windings in this example are coated rectangular wires made of conductor wires with insulating coatings. The conductor wires are made of, for example, copper rectangular wires. The insulating coatings are made of, for example, enamel. The winding portion 90 in this example is an edgewise coil made by edgewise winding the coated rectangular wires.

[0088] The winding portion 90 has a rectangular cylindrical shape. That is, the end face 91 of the winding portion 90 in this example has a rectangular frame shape. The winding portion 90 has an inner surface 92 and an outer surface 93. The inner surface 92 faces the middle core portion 2. There is a gap between the inner surface 92 and the outer peripheral surface of the middle core portion 2. If the reactor 7 includes a molded resin portion (not shown), this gap is filled with resin that forms the molded resin portion. The outer surface 93 faces the side core portions 3 and 4. The end face 91 faces the end core portions 5 and 6. The corners of the winding portion 90 in this example are rounded. When the winding portion 90 has a rectangular cylindrical shape, the contact area between the winding portion 90 and the installation object tends to be larger compared to when the winding portion is cylindrical with the same cross-sectional area. A larger contact area between the winding portion 90 and the installation object improves the heat dissipation performance of the reactor 7. If the contact area between the winding part 90 and the installation object is large, the installation state of the winding part 90 relative to the installation object is likely to be stable.

[0089] [Others] Although not shown, the reactor 7 may include a molded resin portion. The molded resin portion covers at least a portion of the magnetic core 8. The molded resin portion functions to protect the magnetic core 8 from the external environment. The molded resin portion may also cover the coil 9. That is, the molded resin portion is provided so as to cover at least a portion of the assembly of the magnetic core 8 and the coil 9. The molded resin portion integrates the magnetic core 8 and the coil 9. A portion of the outer circumferential surface of the magnetic core 8 or at least a portion of the outer circumferential surface of the coil 9 may be exposed from the molded resin portion. If the molded resin portion is provided between the magnetic core 8 and the coil 9, the insulation between the magnetic core 8 and the coil 9 is likely to be improved. If the molded resin portion is provided between the middle core portion 21 of the first core lamination 81 and the middle core portion 22 of the second core lamination 82, the molded resin portion provided therebetween functions as a gap material for the magnetic core 8. The resin forming the molded resin portion is, for example, the same resin as the resin of the composite material described above. The material forming the molded resin portion may contain the above-mentioned filler, similar to the composite material.

[0090] Although not shown, the reactor 7 may include a retaining member. The retaining member is disposed between the magnetic core 8 and the coil 9 and serves to electrically insulate the magnetic core 8 from the coil 9. The retaining member defines the relative positions of the magnetic core 8 and the coil 9 and maintains their positioning. The retaining member is disposed, for example, between the end surface 91 of the winding portion 90 and the end core portions 5 and 6. The retaining member disposed between the end surface 91 of the winding portion 90 and the end core portions 5 and 6 is, for example, a frame-shaped member. The retaining member is disposed, for example, between the inner circumferential surface of the winding portion 90 and the outer circumferential surface of the middle core portion 2. The retaining member disposed between the inner circumferential surface of the winding portion 90 and the outer circumferential surface of the middle core portion 2 is, for example, a cylindrical member. The retaining member disposed between the inner circumferential surface of the winding portion 90 and the outer circumferential surface of the middle core portion 2 is, for example, structured to allow unsolidified resin forming the molded resin portion to flow between the winding portion 90 and the middle core portion 2.

[0091] <Sixth Embodiment> A reactor of the sixth embodiment will be described with reference to Fig. 8 . The reactor of the sixth embodiment differs from the reactor 7 of the fifth embodiment in the combination of the first core laminations 81 and the second core laminations 82. The reactor of the sixth embodiment has the same configuration as the reactor 7 of the fifth embodiment except for the combination of the first core laminations 81 and the second core laminations 82. For ease of explanation, Fig. 8 shows the reactor from a direction in which the first surface 111 shown in Fig. 1 can be seen. For ease of explanation, Fig. 8 shows the winding portion 90 of the coil 9 in cross section.

[0092] The first core lamination 81 of this example includes one first block portion 110 and three second block portions 120. One first block portion 110 is the same as the first block portion 110 of the core lamination 1α of the first embodiment. For ease of explanation, FIG. 8 illustrates the reactor from the direction in which the first surface 111 shown in FIG. 1 is visible. In the first block portion 110, the first portion 11 and the second portion 12 overlap in the direction along the height of the first block portion 110. The first block portion 110 is the end core portion 5. Of the three second block portions 120, the middle core portion 21 disposed inside the winding portion 90 has a shorter length along the first direction D1 than the side core portions 3 and 4 disposed outside the winding portion 90. The first core lamination 81 of this example has an E-shape in which the middle core portion 21 has the shorter length. Each second block portion 120 is composed of a second portion 12.

[0093] The second core laminations 82 of this example include an end core portion 6 and a middle core portion 22. The second core laminations 82 of this example have a T-shape made up of the end core portion 6 and the middle core portion 22. Both the end core portion 6 and the middle core portion 22 are made up of a first portion 11. The second core laminations 82 of this example are made up of only the first portion 11 and do not include a second portion 12. The second core laminations 82 of this example are an integrated body in which the end core portion 6 and the middle core portion 22 are integrally molded.

[0094] In this example, the magnetic core 8 has a θ-shape by combining the E-shaped first core pieces 81 and the T-shaped second core pieces 82 .

[0095] In this example, the first core piece 81 has the first block portion 110 of the core piece 1α of embodiment 1, and the second core piece 82 is composed of the first portion 11, so that leakage magnetic flux from each end core portion 5, 6 is likely to be reduced and loss is less likely to worsen.

[0096] <Seventh Embodiment> A reactor of the seventh embodiment will be described with reference to Fig. 9 . The reactor of the seventh embodiment differs from the reactor 7 of the fifth embodiment and the reactor of the sixth embodiment in the combination of the first core laminations 81 and the second core laminations 82. The reactor of the seventh embodiment has the same configuration as the reactor 7 of the fifth embodiment except for the combination of the first core laminations 81 and the second core laminations 82. For ease of explanation, Fig. 9 shows the reactor from a direction in which the first surface 111 shown in Fig. 1 is visible. For ease of explanation, Fig. 9 shows the winding portion 90 of the coil 9 in cross section.

[0097] The first core lamination 81 of this example includes one first block portion 110 and three second block portions 120. One first block portion 110 is the same as the first block portion 110 of the core lamination 1α of embodiment 1. For convenience of explanation, FIG. 9 illustrates the reactor from the direction in which the first surface 111 shown in FIG. 1 is visible. In the first block portion 110, the first portion 11 and the second portion 12 overlap in the direction along the height of the first block portion 110. The first block portion 110 is the end core portion 5. Of the three second block portions 120, the middle core portion 21 disposed inside the winding portion 90 has a shorter length along the first direction D1 than the side core portions 3 and 4 disposed outside the winding portion 90. The first core lamination 81 of this example has an E-shape in which the middle core portion 21 has the short length.

[0098] The middle core portion 21 is composed of a first portion 11 and a second portion 12. The first portion 11 of the middle core portion 21 is an integral block body with no joint between it and the first portion 11 of the first block portion 110. The block body composed of the first portion 11 of the middle core portion 21 and the first portion 11 of the first block portion 110 has a T-shape. The second portion 12 of the middle core portion 21 covers the end face and first surface of the first portion 11 of the middle core portion 21 and is configured to be continuous with the second portion 12 of the first block portion 110. The side core portions 3, 4 are composed of the second portions 12.

[0099] The second core laminations 82 of this example are the same as the second core laminations 82 of the sixth embodiment.

[0100] In this example, the magnetic core 8 has a θ-shape by combining the E-shaped first core pieces 81 and the T-shaped second core pieces 82 .

[0101] In this example, the first block portion 110 of the first core piece 81 that constitutes the end core portion 5 has the first portion 11, and the second core piece 82 is also composed of the first portion 11, so that leakage magnetic flux from each end core portion 5, 6 is likely to be reduced and loss is unlikely to worsen.

[0102] <Modifications> Although not shown, the coil may have two winding portions. In this case, the magnetic core has two inner core portions and two outer core portions. The two inner core portions are arranged to face the inner surfaces of the winding portions. The two outer core portions are arranged to connect the end faces of the two inner core portions. The two outer core portions have portions arranged to face the end faces of each winding portion. The core pieces that make up the magnetic core are, for example, formed of a U-shaped block body. The U-shaped core piece is formed by joining a first block portion and a second block portion. The first block portion is the outer core portion, and the second block portion is the inner core portion. The first block portion has a first portion and a second portion, and the first portion is arranged within a predetermined height range of the first block portion.

[0103] Eighth Embodiment Converter / Power Conversion Apparatus The reactor 7 described above can be used in applications that satisfy the following energization conditions. The energization conditions include, for example, a maximum DC current of approximately 100 A to 1000 A, an average voltage of approximately 100 V to 1000 V, and an operating frequency of approximately 5 kHz to 100 kHz. The reactor 7 described above is typically used as a component of a converter mounted on a vehicle such as an electric vehicle or a hybrid vehicle, or as a component of a power conversion apparatus that includes this converter.

[0104] As shown in Fig. 10 , a vehicle 1200 such as a hybrid vehicle or an electric vehicle includes a main battery 1210, a power conversion device 1100 connected to the main battery 1210, and a motor 1220 that is driven by power supplied from the main battery 1210 and used for traveling. The motor 1220 is typically a three-phase AC motor that drives wheels 1250 during traveling and functions as a generator during regeneration. In the case of a hybrid vehicle, the vehicle 1200 includes an engine 1300 in addition to the motor 1220. In Fig. 10 , the charging point of the vehicle 1200 is an inlet, but a plug may also be provided.

[0105] The power conversion device 1100 includes a converter 1110 connected to a main battery 1210, and an inverter 1120 connected to the converter 1110 and performing mutual conversion between direct current and alternating current. The converter 1110 shown in this example boosts the input voltage of the main battery 1210, which is approximately 200 V or more and 300 V or less, to approximately 400 V or more and 700 V or less, when the vehicle 1200 is running, and supplies power to the inverter 1120. During regeneration, the converter 1110 reduces the input voltage output from the motor 1220 via the inverter 1120 to a direct current voltage suitable for the main battery 1210, and charges the main battery 1210. The input voltage is a direct current voltage. When the vehicle 1200 is running, the inverter 1120 converts the DC boosted by the converter 1110 into a predetermined AC and supplies it to the motor 1220, and when regenerating, it converts the AC output from the motor 1220 into DC and outputs it to the converter 1110.

[0106] As shown in FIG. 11 , 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, and converts the input voltage by repeatedly turning the elements on and off. The conversion of the input voltage here refers to boosting or 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 the current flowing through the circuit, and has the function of smoothing out changes when the current increases or decreases due to switching operations. The reactor 1115 includes the reactor 7 described above.

[0107] In addition to converter 1110, vehicle 1200 also includes a power supply converter 1150 connected to main battery 1210, and an auxiliary power supply converter 1160 connected to main battery 1210 and sub-battery 1230, which serves as a power source for auxiliary equipment 1240, and converts the high voltage of main battery 1210 to 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 can have a configuration similar to reactor 7 described above, but can be reactors with appropriately modified size, shape, etc. Furthermore, reactor 7 described above can also be used in converters that convert input power, such as converters that only step up or converters that only step down.

[0108] [Test Example] Reactors were fabricated using various core pieces each combining a first portion made of a powder compact and a second portion made of a composite material compact, and the inductance and loss of the reactors were investigated.

[0109] Each sample in the test example used a magnetic core made up of two core pieces of the same shape and size. The shape of the magnetic core was the same as that of magnetic core 8 shown in Figure 6. Each core piece included one first block portion and three second block portions. The first block portion was arranged to face the end face of the winding portion of the coil. The three second block portions had side faces facing either the inner or outer surface of the winding portion, and were arranged so that the side faces faced each other. Of the three second block portions, the middle core portion had a portion that was arranged inside the winding portion. Of the three second block portions, two side core portions were arranged outside the winding portion to sandwich the middle core portion.

[0110] In each core piece, the first block portion is formed by combining the first portion and the second portion. In each core piece, the second block portion is formed only by the second portion. In each sample, the material of the powder compact forming the first portion is the same. In each sample, the material of the composite material compact forming the second portion is the same.

[0111] In each test example, a coil of the same shape and size was used.

[0112] <Test Example 1> In Test Example 1, the first and second parts constituting the first block part were stacked in a direction along the height of the first block part, and samples with different heights of the first part were prepared, and the effect of the height of the first part of the first block part was investigated.

[0113] <<Samples>> Samples No. 1-1 to 1-6 were produced, each having a first block portion with a different height of the first portion. Samples No. 1-1 to 1-6 differed in the ratio H1 / H0 of the height H1 of the first portion to the height H0 of the first block portion. The ratio H1 / H0 of Sample No. 1-1 was 0.17. The ratio H1 / H0 of Sample No. 1-2 was 0.33. The ratio H1 / H0 of Sample No. 1-3 was 0.50. The ratio H1 / H0 of Sample No. 1-4 was 0.67. The ratio H1 / H0 of Sample No. 1-5 was 0.83. The ratio H1 / H0 of Sample No. 1-6 was 1.00.

[0114] In all of Sample No. 1-1 to Sample No. 1-6, the ratio T1 / T0 of the thickness T1 of the first portion to the thickness T0 of the first block portion was 1.00. In all of Sample No. 1-1 to Sample No. 1-6, the ratio W1 / W0 of the width W1 of the first portion to the width W0 of the first block portion was 1.00.

[0115] In Sample No. 1-10, the first block portion is composed of only the second portion and does not include the first portion.

[0116] <<Inductance>> The inductance of each sample reactor was determined when a direct current of 250 A was passed through the coil. To analyze the inductance, commercially available electromagnetic field analysis software, JMAG-Designer 22.0 manufactured by JSOL Corporation, was used. The results are shown in Table 1. In Table 1, the values ​​are expressed relative to the results of sample No. 1-10, which is set to 100 percent.

[0117] <Losses> The losses when the reactor was driven were determined for each sample reactor. To analyze the losses, commercially available electromagnetic field analysis software, JMAG-Designer 22.0, manufactured by JSOL Corporation, was used. The reactor was driven under the following conditions: DC current 0 A, input voltage 300 V, output voltage 600 V, and frequency 20 kHz. Under these conditions, the losses in the coil and total losses were determined. The total losses include the losses in the coil, the losses in the magnetic core, and the losses in the case when the reactor was placed in the case. The results are shown in Table 1. In Table 1, the values ​​are expressed relative to the results of Samples 1-10, which are set to 100 percent.

[0118]

[0119] As shown in Table 1, when the ratio H1 / H0 exceeds 0.50, the total loss is smaller than that of Sample No. 1-10. When the ratio H1 / H0 exceeds 0.50, the first portion made of the powder compact is disposed over a relatively wide area of ​​the first block portion. It is believed that the relatively wide area of ​​the first portion made of the powder compact with high magnetic permeability reduces leakage magnetic flux from the first block portion, preventing deterioration of loss.

[0120] As shown in Table 1, even if the ratio H1 / H0 increases, the rate of decrease in inductance is small. Although the powder compact is prone to magnetic saturation, because the first block portion is arranged to face the end face of the winding portion, it is thought that the effect of the powder compact arranged in this first block portion on magnetic saturation is relatively small. In other words, it is thought that even if the ratio H1 / H0 increases, the first block portion can maintain a high inductance.

[0121] In the first block portion, it is required that the first portion and the second portion are bonded well. If the ratio H1 / H0 is less than 1.00, the first portion and the second portion overlap in the direction along the height of the first block portion, and the first portion and the second portion are bonded over a relatively large surface. Therefore, if the ratio H1 / H0 is less than 1.00, it is considered that the first portion and the second portion can be bonded well to each other.

[0122] [Test Example 2] In Test Example 2, the first and second parts constituting the first block part were stacked in a direction along the thickness of the first block part, and samples with different thicknesses of the first part were prepared, and the effect of the thickness of the first part of the first block part was investigated.

[0123] <<Samples>> Samples No. 2-1 to 2-5 were prepared, each having a first block portion with a different first portion thickness. Samples No. 2-1 to 2-5 differed in the ratio T1 / T0 of the thickness T1 of the first portion to the thickness T0 of the first block portion. The ratio T1 / T0 of Sample No. 2-1 was 0.29. The ratio T1 / T0 of Sample No. 2-2 was 0.47. The ratio T1 / T0 of Sample No. 2-3 was 0.65. The ratio T1 / T0 of Sample No. 2-4 was 0.82. The ratio T1 / T0 of Sample No. 2-5 was 1.00.

[0124] In all of Sample No. 2-1 to Sample No. 2-5, the ratio H1 / H0 of the height H1 of the first portion to the height H0 of the first block portion was 1.00. In all of Sample No. 2-1 to Sample No. 2-5, the ratio W1 / W0 of the width W1 of the first portion to the width W0 of the first block portion was 1.00.

[0125] In Sample No. 2-10, the first block portion is composed of only the second portion and does not include the first portion. Sample No. 2-10 is the same as Sample No. 1-10.

[0126] <<Inductance>> For each reactor sample, the inductance was determined when a direct current of 250 A was passed through the coil, as in Test Example 1. The results are shown in Table 2. In Table 2, the results are shown as relative values, with the result of Sample No. 2-10 being set to 100 percent.

[0127] <<Loss>> For each sample reactor, the loss when the reactor was driven was determined in the same manner as in Test Example 1. The results are shown in Table 2. In Table 2, the loss is shown as a relative value, with the result of Sample No. 2-10 being set to 100 percent.

[0128]

[0129] As shown in Table 2, when the ratio T1 / T0 exceeds 0.47, the total loss is smaller than that of Sample No. 2-10. When the ratio T1 / T0 exceeds 0.47, the first portion made of the powder compact is disposed over a relatively wide area of ​​the first block portion. It is believed that the relatively wide area of ​​the first portion made of the powder compact with high magnetic permeability reduces leakage magnetic flux from the first block portion, preventing deterioration of loss.

[0130] As shown in Table 2, even if the ratio T1 / T0 increases, the rate of decrease in inductance is small. Although the powder compact is prone to magnetic saturation, because the first block portion is arranged to face the end face of the winding portion, it is thought that the effect of the powder compact arranged in this first block portion on magnetic saturation is relatively small. In other words, it is thought that even if the ratio T1 / T0 increases, the first block portion can maintain a high inductance.

[0131] Looking at Test Example 1 and Test Example 2 as a whole, it is considered that when the ratio H1 / H0 is greater than 0.50 and less than 1.00 and the ratio T1 / T0 is greater than 0.47, it is possible to reduce loss and also to bond the first portion and the second portion to each other well.

[0132] [Test Example 3] In Test Example 3, the first and second parts constituting the first block part were stacked in a direction along the width of the first block part, and samples with different widths of the first part were prepared, and the effect of the width of the first part of the first block part was investigated.

[0133] <<Samples>> Samples No. 3-1 to 3-6 were prepared, each having a first block portion with a different first portion width. Samples No. 3-1 to 3-6 differed in the ratio W1 / W0 of the width W1 of the first portion to the width W0 of the first block portion. The ratio W1 / W0 of Sample No. 3-1 was 0.33. The ratio W1 / W0 of Sample No. 3-2 was 0.47. The ratio W1 / W0 of Sample No. 3-3 was 0.60. The ratio W1 / W0 of Sample No. 3-4 was 0.73. The ratio W1 / W0 of Sample No. 3-5 was 0.87. The ratio W1 / W0 of Sample No. 3-6 was 1.00.

[0134] In all of Sample No. 3-1 to Sample No. 3-6, the ratio H1 / H0 of the height H1 of the first portion to the height H0 of the first block portion was 1.00. In all of Sample No. 3-1 to Sample No. 3-6, the ratio T1 / T0 of the thickness T1 of the first portion to the thickness T0 of the first block portion was 1.00.

[0135] In Sample No. 3-10, the first block portion is composed of only the second portion and does not include the first portion. Sample No. 3-10 is the same as Sample No. 1-10.

[0136] <<Inductance>> For each reactor sample, the inductance was determined when a direct current of 250 A was passed through the coil, as in Test Example 1. The results are shown in Table 3. In Table 3, the results are shown as relative values, with the result of Sample No. 3-10 being set to 100 percent.

[0137] <<Loss>> For each sample reactor, the loss when the reactor was driven was determined in the same manner as in Test Example 1. The results are shown in Table 3. In Table 3, the loss is shown as a relative value, with the result of Sample No. 3-10 being set to 100 percent.

[0138]

[0139] As shown in Table 3, all of Sample No. 3-1 to Sample No. 3-6 had smaller total losses than Sample No. 3-10. Comparing Sample No. 3-1 to Sample No. 3-6, the larger the ratio W1 / W0, the smaller the coil loss and total loss. The larger the ratio W1 / W0, the more the first portion made of the powder compact is disposed over a relatively wide area of ​​the first block portion. It is believed that the relatively wide area of ​​the first portion made of the powder compact with high magnetic permeability reduces leakage magnetic flux from the first block portion, preventing deterioration of loss.

[0140] As shown in Table 3, even if the ratio W1 / W0 increases, the rate of decrease in inductance is small. Although the powder compact is prone to magnetic saturation, because the first block portion is arranged to face the end face of the winding portion, it is thought that the effect of the powder compact arranged in this first block portion on magnetic saturation is relatively small. In other words, it is thought that even if the ratio W1 / W0 increases, the first block portion can maintain a high inductance.

[0141] Looking at Test Example 1 and Test Example 3 as a whole, it is considered that when the ratio H1 / H0 is greater than 0.50 and less than 1.00 and the ratio W1 / W0 is 0.30 or more, it is possible to reduce loss and also to join the first portion and the second portion to each other well.

[0142] 1α, 1β, 1γ, 1δ Core piece 11 First portion 12 Second portion, 12A Connecting portion, 12B Flange portion 110 First block portion 111 First surface 112 Second surface 113 Outer end surface 115 Side surface 120 Second block portion 125 Side surface 2, 21, 22 Middle core portion 3, 31, 32 Side core portion 4, 41, 42 Side core portion 5 End core portion 6 End core portion 2g Gap 7 Reactor 8 Magnetic core 81 First core piece 82 Second core piece 9 Coil 90 Winding portion 91 End surface 92 Inner surface 93 Outer surface D1 First direction, D2 Second direction, D3 Third direction H0, H1 Height T0, T1 Thickness W0, W1 Width 1100 Power conversion device, 1110 converter, 1111 switching element, 1112 drive circuit, 1115 reactor, 1120 inverter, 1150 power supply device converter, 1160 auxiliary power supply converter, 1200 vehicle, 1210 main battery, 1220 motor, 1230 sub-battery, 1240 auxiliary devices, 1250 wheels, 1300 engine

Claims

1. A core piece for constituting a magnetic core arranged inside and outside a coil, comprising: a first block portion arranged to face an end face of the coil; and a plurality of second block portions having side faces facing either the inner or outer surface of the coil, the side faces facing each other, the first block portion comprising: a first portion made of a pressed powder compact of soft magnetic powder; and a second portion made of a compact of a composite material in which soft magnetic powder is dispersed in resin, the first portion and the second portion overlap in a direction along the height of the first block portion, the ratio of the height of the first portion to the height of the first block portion being greater than 0.5 and less than 1, and the height of the first block portion and the height of the first portion each being a length along a direction perpendicular to both the direction along the axis of the coil and the direction in which the plurality of second block portions are arranged.

2. A core piece according to claim 1, wherein said plurality of second block portions are formed of a molded body of said composite material so as to be continuous with said second portion.

3. A core piece as described in claim 1 or claim 2, wherein the first block portion has a first surface and a second surface facing each other in a direction along the height of the first block portion, the first portion has the first surface, and the second portion has the second surface.

4. A core piece according to any one of claims 1 to 3, wherein the first portion and the second portion overlap in a direction along the thickness of the first block portion, the ratio of the thickness of the first portion to the thickness of the first block portion is 0.6 or more, and each of the thickness of the first block portion and the thickness of the first portion is a length along the axis of the coil.

5. A core piece according to any one of claims 1 to 4, wherein the first block portion has an outer end surface facing outward in a direction along the axis of the coil, and the first portion has the outer end surface.

6. A reactor comprising: a magnetic core formed by combining first core pieces and second core pieces; and a coil arranged in a part of the magnetic core, wherein at least one of the first core pieces and the second core pieces is a core piece as defined in any one of claims 1 to 5.

7. A converter comprising the reactor according to claim 6.

8. A power conversion device comprising the converter according to claim 7.

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