Core components, reactors, converters, and power conversion devices

Abstract

To provide core pieces with excellent productivity. [Solution] The core piece comprises a first portion made of a molded composite material and a second portion made of a compacted powder molded body. The second portion has a base end portion that extends in a direction perpendicular to the axis, straddling the axis of the middle core portion, and a protruding portion that extends along the axis from the base end portion to the middle core portion. The base end portion has two inner end faces that are spaced apart from the end face of the coil. The protruding portion has two side surfaces that face each other across the axis and connect to each of the two inner end faces, and an end face that connects the side surfaces. The first portion has a portion that covers from each of the two corners, which are made up of each of the two inner end faces and each of the two side surfaces, to each of the two corners, which are made up of each of the two side surfaces and the end face. Each of the two corners is made up of a curved surface.

Description

Technical Field

[0001] The present disclosure relates to a core piece, a reactor, a converter, and a power conversion device.

Background Art

[0002] The reactor disclosed in Patent Document 1 includes a coil and a magnetic core. The coil has a cylindrical winding portion. The magnetic core has a first core piece and a second core piece combined in a first direction along the axis of the coil.

[0003] The shape of each core piece is E-shaped. Each core piece has an end core portion, a middle core portion, a first side core portion, and a second side core portion. The end core portion faces the end face of the winding portion. The middle core portion has a portion disposed inside the winding portion. The first side core portion and the second side core portion are disposed facing each other so as to sandwich the middle core portion. The first side core portion and the second side core portion are disposed outside the winding portion. The end core portion connects the middle core portion, the first side core portion, and the second side core portion.

[0004] Each core piece includes a first region and a second region having a higher relative permeability than the first region. The first region includes two corner portions each formed by the middle core portion and the end core portion. The second region includes a base end region and a protruding region. The base end region extends in the end core portion across the axis of the middle core portion in the parallel direction of the middle core portion and the two side core portions. The protruding region protrudes from the base end region toward the middle core portion. Each core piece is typically manufactured by disposing the second region in a mold and molding the first region around it.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

[0006] It is desirable to have excellent productivity in producing the core pieces that make up the reactor.

[0007] One of the objectives of this disclosure is to provide core pieces with superior productivity. [Means for solving the problem]

[0008] The core piece of this disclosure comprises a middle core portion disposed inside the coil and an end core portion disposed opposite the end face of the coil so as to be connected to the middle core portion. The core piece comprises a first portion made of a molded composite material in which soft magnetic powder is dispersed in a resin and a second portion made of a compacted molded soft magnetic powder. The second portion has, in the end core portion, a base end portion extending in a direction perpendicular to the axis of the middle core portion and straddling the axis of the middle core portion, and a protruding portion extending along the axis from the base end portion to the middle core portion. The base end portion has two inner end faces that are spaced apart from the end face of the coil. The protruding portion has two side surfaces that are opposite each other across the axis and connected to each of the two inner end faces, and an end face that connects the side surfaces. The first portion has a portion that covers from each of the two corners, each formed by each of the two inner end faces and each of the two side faces, to each of the two corners, each formed by each of the two side faces and the end face. Each of the two corners is formed by a curved surface. [Effects of the Invention]

[0009] The core piece of this disclosure offers excellent productivity. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a schematic perspective view showing the reactor of Embodiment 1. [Figure 2] Figure 2 is a schematic perspective view showing the reactor of Embodiment 1 in a disassembled state. [Figure 3] Figure 3 is a schematic top view showing the reactor of Embodiment 1. [Figure 4] Figure 4 is a schematic bottom view showing the reactor of Embodiment 1. [Figure 5] Figure 5 is an enlarged view of region A1 in Figure 4. [Figure 6] Figure 6 is a schematic top view showing the first core piece provided in the reactor of Embodiment 2. [Figure 7] Figure 7 is a schematic bottom view showing the first core piece provided in the reactor of Embodiment 2. [Figure 8] Figure 8 is a schematic bottom view showing the first core piece provided in the reactor of Embodiment 3. [Figure 9] Figure 9 is an enlarged view of area A2 in Figure 8. [Figure 10] Figure 10 is an enlarged view of area A3 in Figure 8. [Figure 11] Figure 11 is a schematic diagram showing the power supply system of a hybrid vehicle. [Figure 12] Figure 12 is a circuit diagram showing an example of a power conversion device equipped with a converter. [Modes for carrying out the invention]

[0011] [Description of Embodiments in this Disclosure] First, the embodiments of this disclosure will be listed and described.

[0012] (1) A core piece according to one embodiment of the present disclosure comprises a middle core portion disposed inside a coil and an end core portion disposed opposite the end face of the coil so as to be connected to the middle core portion. The core piece comprises a first portion made of a molded composite material in which soft magnetic powder is dispersed in a resin and a second portion made of a compacted molded soft magnetic powder. The second portion has, in the end core portion, a base end portion extending in a direction perpendicular to the axis of the middle core portion and straddling the axis of the middle core portion, and a protruding portion extending along the axis from the base end portion to the middle core portion. The base end portion has two inner end faces that are spaced apart from the end face of the coil. The protruding portion has two side surfaces that are opposite each other across the axis and connected to each of the two inner end faces, and an end face that connects the side surfaces. The first portion has a portion that covers from each of the two corners, each formed by each of the two inner end faces and each of the two side faces, to each of the two corners, each formed by each of the two side faces and the end face. Each of the two corners is formed by a curved surface.

[0013] The core piece described in (1) above is typically manufactured by placing the second part in a mold and molding the first part around it. The thermal expansion coefficient of the first part, which is made of a composite material molded body, is greater than that of the second part, which is made of a powder molded body. Therefore, when the constituent material of the first part is filled around the second part placed in the mold and solidified, the first part shrinks more than the second part. Unlike the core piece described in (1) above, if the two corners covered by the first part are not made of curved surfaces, the corners are prone to causing damage such as chipping or cracking of the constituent material of the first part. One reason for this damage is that the difference in thermal expansion coefficients between the first and second parts results in a difference in the amount of shrinkage of each part. In contrast, the core piece described in (1) above has two corners covered by the first part that are made of curved surfaces, so that the difference in thermal expansion coefficients makes it less likely for the corners to be the starting point for damage to the first part. Therefore, the core piece described in (1) above has excellent productivity.

[0014] (2) In the core piece of (1) above, the radius of curvature of the curved surface may be 0.5 mm or more and 10 mm or less.

[0015] If the radius of curvature is 0.5 mm or more, the first part is less likely to be damaged during the manufacture of the core piece. If the radius of curvature is 10 mm or less, the magnetic path area of the core piece is less likely to become small.

[0016] (3) In the core piece of (1) or (2) above, the base end part may be provided over the entire length in the direction orthogonal to the axis in the end core part.

[0017] The core piece of (3) above is more likely to increase the relative permeability of the end core part as compared with the case where the base end part is not provided over the entire length in the direction orthogonal to the axis in the end core part.

[0018] (4) In the core piece of (1) to (3) above, the relative permeability of the second part may be 50 or more and 500 or less.

[0019] The reactor of (4) above is likely to reduce leakage flux because magnetic flux easily passes through the second part, and it is easy to construct a reactor with reduced leakage flux.

[0020] (5) In the core piece of any one of (1) to (4) above, the relative permeability of the first part may be 5 or more and 50 or less.

[0021] The core piece of (5) above is likely to construct a reactor with reduced leakage flux. Moreover, since the core piece of (5) above has a first part with a relatively low specific relative permeability in a specific low range, magnetic saturation associated with providing the second part is less likely to occur, and it is easy to construct a reactor that can maintain a high inductance even in an environment where a large current is used.

[0022] (6) A reactor according to one embodiment of the present disclosure includes a coil and a magnetic core having a first core piece and a second core piece combined in a first direction along the axis of the coil. The first core piece is a core piece of any one of (1) to (5) above.

[0023] The reactor described in (6) above offers excellent productivity.

[0024] (7) A converter according to one embodiment of the present disclosure comprises the reactor described in (6) above.

[0025] The above converter, equipped with the above reactor, offers excellent productivity.

[0026] (8) A power converter according to one embodiment of the present disclosure comprises the converter described in (7) above.

[0027] The above power conversion device, equipped with the above converter, offers excellent productivity.

[0028] [Details of the embodiments of this disclosure] The details of embodiments of this disclosure will be described below with reference to the drawings. The same reference numerals in the drawings indicate the same parts. In each drawing, some parts of the configuration may be exaggerated or simplified for ease of explanation. The dimensional ratios of parts in the drawings may also differ from those of the actual components.

[0029] [Embodiment 1] <Reactor> The reactor 1 of Embodiment 1 will be described with reference to Figures 1 to 5. The reactor 1 comprises a coil 2 and a magnetic core 3, as shown in Figure 1. The magnetic core 3 comprises a first core piece 31 and a second core piece 32. The first core piece 31 and the second core piece 32 are combined in a first direction D1 along the axis of the coil 2. One of the features of the reactor 1 of Embodiment 1 is that the first core piece 31 is composed of a specific core piece.

[0030] In the following explanation, we will use the first direction D1, the second direction D2, and the third direction D3 as defined below. The first direction D1 is a direction along the axis of the coil 2, and is the direction from the first end face 20a of the coil 2 toward the second end face 20b. The second direction D2 is perpendicular to the first direction D1 and is the direction along which the first middle core portion 41, the first side core portion 51, and the second side core portion 52 are arranged in parallel. The third direction D3 is perpendicular to both the first direction D1 and the second direction D2.

[0031] ≪Coil≫ As shown in Figures 1 to 4, the coil 2 in this example has one winding section 20. In Figures 3 and 4, the winding section 20 is shown with a dashed line for ease of explanation. The winding section 20 is constructed by winding a series of windings without joints in a spiral shape. Unlike this example, there may be multiple winding sections 20. In that case, the windings constituting each winding section 20 may be independent of each other or may be constructed in a series. The windings constituting each winding section 20 may be independent of each other, and each winding may be connected to each other by a component that electrically connects each winding to itself.

[0032] A coil 2 with one winding section 20 is easier to form than a coil 2 with multiple winding sections 20. A reactor 1 with one winding section 20 has fewer parts than a reactor 1 with multiple winding sections 20. Therefore, a reactor 1 with one winding section 20 has superior productivity. Having only one winding section 20 makes it easier to shorten the width of the reactor 1 compared to when multiple winding sections 20 are arranged in parallel in the second direction D2.

[0033] The shape of coil 2 in this example is rectangular, as shown in Figure 2. The outer circumference of coil 2, viewed along the first direction D1, is rectangular. That is, the end face shape of coil 2, viewed along the first direction D1, is rectangular. Because coil 2 is rectangular, it is easier to increase the contact area between coil 2 and the planar mounting surface compared to when coil 2 is circular with the same cross-sectional area. Therefore, reactor 1 can easily transfer heat from coil 2 to the mounting surface. The mounting surface is, for example, a cooling base. In addition, because the outer circumference of coil 2 is rectangular, it is easier to reduce the height of coil 2. Unlike this example, the shape of coil 2 may be a racetrack-shaped cylinder or a circular cylinder.

[0034] The windings in this example of coil 2 are insulated flat wires. The conductor wires of the insulated flat wires are made of copper flat wires. The insulating coating of the insulated flat wires is made of enamel. In this example, coil 2 is made by winding the insulated flat wires edgewise. Unlike this example, coil 2 may be made by winding the insulated flat wires flatwise. Unlike this example, the windings may be insulated round wires. The windings are known windings.

[0035] Although not shown in the illustration, both ends of the winding are drawn out from the winding section 20. The insulation coating is stripped from both ends of the winding, exposing the conductor wires. Terminal members (not shown) are connected to the exposed conductor wires. External devices (not shown) are connected to the terminal members. The external devices are, for example, power supplies that provide power to coil 2.

[0036] Magnetic Core The magnetic core 3 comprises a middle core portion 4, a first side core portion 51, a second side core portion 52, a first end core portion 61, and a second end core portion 62. The magnetic core 3 forms a closed magnetic circuit through a combination of these core portions. As shown in Figures 3 and 4, the planar shape of the magnetic core 3 in this example, viewed along the third direction D3, is θ-shaped. In Figures 3 and 4, for convenience of explanation, the boundaries between the first middle core portion 41 and the first end core portion 61, the boundaries between the first side core portion 51 and the second side core portion 52 and the first end core portion 61, and the boundaries between the second middle core portion 42 and the second end core portion 62 are shown by dashed lines. The magnetic core 3 comprises a first core piece 31 and a second core piece 32. The first core piece 31 and the second core piece 32 are combined along the first direction D1.

[0037] The first core piece 31 comprises a first portion 7a made of a molded composite material and a second portion 7b made of a compacted powder. As will be described later, the relative permeability of the molded composite material and the compacted powder are different. The magnetic core 3 controls the flow of magnetic flux by arranging regions with different relative permeability at predetermined locations. In Figures 1 to 5, cross-hatching is applied to the second portion 7b for ease of explanation. This is also the case in Figures 6 to 10, which will be referenced in Embodiments 2 and 3 described later. In the following description, in each of the side core portions 51, 52 and each of the end core portions 61, 62, the side farther from the winding portion 20 is referred to as the outside, and the side closer to the winding portion 20 is referred to as the inside.

[0038] [Middle Core Section] The middle core portion 4 has a portion that is positioned inside the winding portion 20. The shape of the middle core portion 4 generally corresponds to the inner circumference shape of the winding portion 20. In this example, the shape of the middle core portion 4 is a rectangular column. That is, the end face shape of the middle core portion 4 when viewed from the axial direction is rectangular. A gap exists between the outer circumference surface of the middle core portion 4 and the inner circumference surface of the winding portion 20.

[0039] The length of the middle core portion 4 along the first direction D1 is equal to or greater than the length of the winding portion 20 along the first direction D1. In this example, the length of the middle core portion 4 along the first direction D1 is slightly longer than the length of the winding portion 20 along the first direction D1, as shown in Figures 3 and 4. In other words, the middle core portion 4 comprises a portion located inside the winding portion 20 and a portion located outside the winding portion 20. Both ends of the middle core portion 4 are located outside the winding portion 20.

[0040] As shown in Figures 2 to 4, the middle core section 4 is composed of a first middle core section 41, a second middle core section 42, and a gap section 33, which will be described later. In this example, as shown in Figures 3 and 4, the width of the first middle core section 41 along the second direction D2 is the same as the width of the second middle core section 42 along the second direction D2.

[0041] [First side core section, second side core section] The first side core section 51 and the second side core section 52 are arranged on the outside of the winding section 20, alongside the middle core section 4. The first side core section 51 and the second side core section 52 are arranged so as to sandwich the winding section 20 from the outside. The first side core section 51, the second side core section 52, and the middle core section 4 are arranged in parallel in the second direction D2.

[0042] The shape of each side core portion 51, 52 is not particularly limited, as long as it extends along the first direction D1 on the outside of the winding portion 20. In this example, each side core portion 51, 52 is a rectangular columnar body extending along the first direction D1. In this example, where the shape of the winding portion 20 is a rectangular cylinder, each side core portion 51, 52 is arranged to face two of the four faces that constitute the outer circumferential surface of the winding portion 20, which are opposite each other. The remaining two faces of the winding portion 20 do not face the magnetic core 3.

[0043] In this example, the shape and dimensions of both side core sections 51 and 52 are identical. The length of each side core section 51 and 52 along the first direction D1 is the same as the length of the middle core section 4 along the first direction D1. In this example, the sum of the cross-sectional areas of the first side core section 51 and the second side core section 52 is the same as the cross-sectional area of ​​the middle core section 4. Here, the cross-sectional area is the cross-sectional area of ​​the cutting plane perpendicular to the first direction D1 in each core section 4, 51, and 52. In this example, the length of each side core section 51 and 52 along the second direction D2 is shorter than the length of the middle core section 4 along the second direction D2. In this example, the sum of the length of the first side core section 51 along the second direction D2 and the length of the second side core section 52 along the second direction D2 is shorter than the length of the middle core section 4 along the second direction D2. In this example, the length of each side core section 51, 52 along the third direction D3 is the same as the length of the first middle section 411 along the third direction D3. The upper surfaces of all core sections 41, 42, 51, 52, 61, 62 facing the third direction D3 are flush. The lower surfaces of all core sections 41, 42, 51, 52, 61, 62 facing away from the third direction D3 are flush.

[0044] Unlike this example, the total length of each side core section 51, 52 along the second direction D2 may be the same as the length of the middle core section 4 along the second direction D2, or it may be longer than the length of the middle core section 4 along the second direction D2. The length of each side core section 51, 52 along the third direction D3 may be shorter than the length of the middle core section 4 along the third direction D3, or it may be longer than the length of the middle core section 4 along the third direction D3. The length of each side core section 51, 52 along the third direction D3 may be shorter than the length of the winding section 20 along the third direction D3. The length of each side core section 51, 52 along the third direction D3 may be equal to or greater than the length of the winding section 20 along the third direction D3. The shapes and dimensions of both side core sections 51, 52 may be different from each other.

[0045] [First end core section, second end core section] The first end core portion 61 is positioned on the outside of the winding portion 20, facing the first end face 20a. The first end core portion 61 connects the first middle core portion 41 and the two side core portions 51 and 52. The second end core portion 62 is positioned on the outside of the winding portion 20, facing the second end face 20b. The second end core portion 62 is positioned to connect to the second middle core portion 42.

[0046] The shape of each end core portion 61, 62 is not particularly limited. In this example, each end core portion 61, 62 is a rectangular body that is elongated in the second direction D2. In this example, the shape and dimensions of both end core portions 61, 62 are the same. The length of each end core portion 61, 62 along the first direction D1 is the same as the length of each side core portion 51, 52 along the second direction D2. The length of each end core portion 61, 62 along the third direction D3 is the same as the length of each side core portion 51, 52 along the third direction D3. The shape and dimensions of both end core portions 61, 62 may be different from each other.

[0047] [First core piece, second core piece] As shown in Figures 3 and 4, the magnetic core 3 in this example is constructed by combining a first core piece 31 and a second core piece 32 such that a gap 33 is provided between the first core piece 31 and the second core piece 32. The shapes of the first core piece 31 and the second core piece 32 may be symmetrical or asymmetrical. Symmetrical means that the shape and size are the same. Asymmetrical means that the shapes are different. In this example, the shapes of the first core piece 31 and the second core piece 32 are asymmetrical. The planar shape of the first core piece 31 is E-shaped. The planar shape of the second core piece 32 in this example is T-shaped. That is, the combination of the first core piece 31 and the second core piece 32 is of type ET. Unlike this example, the planar shape of the second core piece 32 may be E-shaped or I-shaped. That is, the combination of the first core piece 31 and the second core piece 32 may be, for example, type EE or type EI. The first core piece 31 comprises a first end core portion 61, a first middle core portion 41, a first side core portion 51, and a second side core portion 52. The second core piece 32 comprises a second end core portion 62 and a second middle core portion 42.

[0048] As shown in Figures 2 to 4, the first core piece 31 in this example comprises a first part 7a made of a molded composite material and a second part 7b made of a compacted powder. The relative permeability of the second part 7b is higher than that of the first part 7a. The first core piece 31 is typically manufactured by placing the second part 7b in a mold and molding the first part 7a around it. In Figure 2, for the sake of explanation, the first part 7a and the second part 7b are shown separately, but in reality they are formed as a single unit. The first core piece 31 may also be formed by combining the individually molded first part 7a and the second part 7b. Unlike the first core piece 31, the second core piece 32 in this example is composed of a single part.

[0049] <1st part> The planar shape of the first part 7a in this example is E-shaped, as shown in Figures 3 and 4. The first part 7a in this example has two first end parts 611 which are part of the first end core part 61, a first middle part 411 which is part of the first middle core part 41, and two side core parts 51 and 52. Each first end part 611, the first middle part 411, and the two side core parts 51 and 52 are integrally constructed.

[0050] Each first end portion 611 connects the first middle portion 411 to each of the side core portions 51 and 52. Each first end portion 611 is a portion located on the inside of the first end core portion 61. The shape of each first end portion 611 is a thin rectangular columnar body. As shown in Figure 4, each first end portion 611 is composed of an inner portion 611a, a central portion 611b, and an outer portion 611c, which are arranged in order from the first middle portion 411 toward each side core portion 51 and 52, as will be described later. Each inner portion 611a is connected to the lateral portion 411a of the first middle portion 411, as will be described later. Each central portion 611b faces the first end face 20a of the winding portion 20. Each outer portion 611c is connected to each side core portion 51 and 52. Each portion 611a, 611b, and 611c is constructed as a single unit.

[0051] The first middle section 411 has two lateral sections 411a and one connecting section 411b. Each lateral section 411a covers each side surface 73a of the protruding section 73, which will be described later, as shown in Figure 5. The connecting section 411b connects both lateral sections 411a and covers the end surface 73b of the protruding section 73. Each lateral section 411a and the connecting section 411b cover each first corner 751 of the protruding section 73. Each section 411a and 411b is constructed as a single unit.

[0052] Each first corner 741 is formed by the central portion 611b and each inner portion 611a of the first end portion 611, and the lateral portion 411a of the first middle portion 411. The central portion 611b, inner portion 611a, lateral portion 411a, and connecting portion 411b cover the area from the first corner 741 to the first corner 751. Each second corner 742 is formed by the central portion 611b and each outer portion 611c of the first end portion 611, and the side core portions 51, 52.

[0053] As shown in Figure 2, a recess 71 corresponding to the shape of the second part 7b is formed in the first part 7a. In this example, the recess 71 is formed corresponding to the protruding part 73. A part of the first part 7a is positioned in the inner region extending from the base end portion 72 to the protruding part 73. This first part 7a integrally constitutes the first end core portion 61, the first middle core portion 41, and both side core portions 51 and 52.

[0054] <Second part> The second portion 7b has a base portion 72 extending in the second direction D2 and a protruding portion 73 extending in the first direction D1. The base portion 72 and the protruding portion 73 are integrally formed. The planar shape of the second portion 7b in this example is T-shaped, as shown in Figures 3 and 4. The base portion 72 and the protruding portion 73 are rectangular columnar bodies. The base portion 72 and a part of the protruding portion 73 constitute the second end portion 612, which is part of the first end core portion 611. The first end core portion 611 is composed of the second end portion 612 and the first end portion 611 described above. The shape of the second end portion 612 is a T-shaped columnar body. The tip portion of the protruding portion 73 is the second middle portion 412, which is part of the first middle core portion 411. The first middle core portion 41 is composed of the second middle portion 412 and the first middle portion 411 described above.

[0055] 《Proximal part》 The base end portion 72 is located off-center to the outside of the first end core portion 61. That is, the base end portion 72 is provided at a distance from the surface of the first end core portion 61 that faces the first end face 20a of the winding portion 20.

[0056] The base end portion 72 is provided in the first end core portion 61 so as to extend along the second direction D2, straddling the axis 410 of the first middle core portion 41. In Figures 3 and 4, the axis 410 is shown as a dashed line. The axis 410 is a straight line extending from the center line of the first middle core portion 41. As described above, the cross-sectional shape of the middle core portion 4 in this example is rectangular. Therefore, the axis 410 in this example is a straight line extending along the first direction D1, passing through the intersection of the diagonals of the rectangle. When viewed from a third direction D3, the axis 410 in this example is a straight line extending along the first direction D1 of the first middle core portion 41 so as to bisect the length of the first middle core portion 41 along the second direction D2.

[0057] The base end portion 72 may extend beyond each first corner portion 741 in the second direction D2 in the first end core portion 61. In this example, the base end portion 72 is provided at both ends of the first end core portion 61 along the second direction D2. By providing the base end portion 72 at both ends of the first end core portion 61, it is easier to increase the relative permeability of the first end core portion 61 compared to when it is not provided at both ends.

[0058] The base portion 72 has two inner end faces 72a, as shown in Figures 3 and 4. The two inner end faces 72a are arranged to sandwich the protruding portion 73 along the second direction D2. Each inner end face 72a is a face facing the first direction D1. Each inner end face 72a is spaced apart from the first end face 20a of the winding portion 20. Each inner end face 72a is covered by each first end portion 611.

[0059] 《Protruding part》 The protruding portion 73 extends from the base end portion 72 toward the second middle core portion 42. In this example, the protruding portion 73 spans from the first end core portion 61 to the first middle core portion 41. The protruding portion 73 has the function of attracting the magnetic flux flowing from the first middle core portion 41 toward the first end core portion 61, or the function of guiding the magnetic flux flowing from the first end core portion 61 toward the first middle core portion 41 into the winding portion 20. Having either of these functions reduces the leakage magnetic flux from the first corner portion 741. The shape of the protruding portion 73 is not particularly limited as long as it has either of these functions. In this example, the protruding portion 73 is a rectangular parallelepiped extending along the first direction D1.

[0060] The protruding portion 73 has two sides 73a and a tip surface 73b, as shown in Figure 5. Each side 73a is a surface facing the second direction D2. Each side 73a is connected to each inner end surface 72a of the base portion 72 shown in Figure 4. Two corners are formed by each side 73a and each inner end surface 72a. Each corner is covered by each first corner 741. The tip surface 73b is a surface facing the first direction D1. The tip surface 73b connects both sides 73a. Each first corner 751 is formed by the tip surface 73b and each side 73a. Each first corner 751 is covered by a lateral portion 411a and a connecting portion 441b. Each first corner 751 is composed of a curved surface. When the first core piece 31 is manufactured by filling the area around the second part 7b, which is placed in a mold, with the constituent material of the first part 7a and solidifying it, a difference in the amount of shrinkage occurs in each part 7a and 7b due to the difference in the thermal expansion coefficients of the first part 7a and the second part 7b. However, because each first corner 751 is made of a curved surface, damage such as chipping or cracking of the constituent material of the first part 7a due to the difference in the amount of shrinkage is less likely to occur.

[0061] The radius of curvature R1 of each first corner 751 is, for example, 0.5 mm or more and 10 mm or less. If the radius of curvature R1 is 0.5 mm or more, the first part 7a is less likely to be damaged during the manufacture of the first core piece 31. If the radius of curvature R1 is 10 mm or less, the magnetic path area of ​​the first core piece 31 is less likely to be reduced. The radius of curvature R1 may also be 1.0 mm or more and 8.0 mm or less, or 1.5 mm or more and 5.0 mm or less.

[0062] The tip surface 73b of the protruding portion 73 shown in Figure 3 does not reach the first end surface 20a of the winding portion 20 and may be located outside the winding portion 20, flush with the first end surface 20a of the winding portion 20, or located inside the winding portion 20. In this example, the tip surface 73b is located inside the winding portion 20. By having the tip surface 73b located inside the winding portion 20, leakage flux is easily suppressed even if a misalignment due to dimensional tolerance occurs during, for example, the assembly of the coil 2 and the magnetic core 3. The length along the first direction D1 between the first end surface 20a of the winding portion 20 and the tip surface 73b inside the winding portion 20 is, for example, 1 / 10 or less, 1 / 20 or less, or 1 / 30 or less of the total length of the winding portion 20.

[0063] [Gap] The gap portion 33 is provided between the first end face 41e of the first middle core portion 41 and the second end face 42e of the second middle core portion 42. By providing the gap portion 33, the inductance of the reactor 1 can be easily adjusted. The gap portion 33 is located inside the winding portion 20. The gap portion 33 is made of a material having a lower relative permeability than the first core piece 31 and the second core piece 32. The constituent material of the gap portion 33 can preferably be, for example, a non-magnetic ceramic or resin. The gap portion 33 may also be an air gap. If the molded resin portion described later is provided, the gap portion 33 may be made of a part of the molded resin portion.

[0064] <Material> The first part 7a of the first core piece 31 is made of a molded composite material. The molded composite material is a molded body in which soft magnetic powder is dispersed in a resin. The second part 7b is made of a compacted powder molded body. The compacted powder molded body is a molded body made by compressing soft magnetic powder. The second core piece 32 is made of either a compacted powder molded body or a molded composite material. The second core piece 32 may be made of a molded body with a different relative permeability from the first part 7a or the second part 7b, or it may be made of a molded body with the same relative permeability. For example, even if the second core piece 32 and the second part 7b are made of compacted powder molded bodies, if the material and content ratio of the soft magnetic powder constituting the compacted powder molded bodies are different, their relative permeability will be different. Furthermore, even if the second core piece 32 and the first part 7a are made of a composite material molded body, if at least one of the materials constituting the composite material, the soft magnetic powder and the resin, is different, or if the materials of the soft magnetic powder and the resin are the same but the content ratio of the soft magnetic powder and the resin is different, their relative permeability will be different. In this example, the second core piece 32 is made of the same powder compacted body as the powder compacted body constituting the second part 7b.

[0065] The composite material molded body allows for easy adjustment of the content ratio of soft magnetic powder in the resin. Therefore, the magnetic properties of the composite material molded body are easy to adjust. Furthermore, the composite material molded body is easier to form even in complex shapes compared to powder compacted molded bodies. The relative permeability of the composite material molded body is, for example, 5 to 50. By satisfying the above upper and lower limits for the relative permeability of the composite material molded body, magnetic saturation associated with the inclusion of powder compacted molded bodies is less likely to occur, making it easier to maintain high inductance even in high-current operating environments. The relative permeability of the composite material molded body may also be 10 to 45, or 15 to 40. The content ratio of soft magnetic powder in the composite material molded body is, for example, 20% to 80% by volume. The content ratio of resin in the composite material molded body is, for example, 20% to 80% by volume. These content ratios are relative to the volume of the composite material molded body, which is set to 100%.

[0066] Compared to molded bodies made of composite materials, powder compacts allow for a higher proportion of soft magnetic powder in the magnetic core 3. Therefore, powder compacts are easier to improve in terms of magnetic properties. Magnetic properties include relative permeability and saturation magnetic flux density. Furthermore, powder compacts have superior heat dissipation compared to molded bodies made of composite materials because they contain less resin and more soft magnetic powder. The relative permeability of a powder compact is, for example, 50 to 500. By satisfying the above upper and lower limits for the relative permeability of a powder compact, magnetic flux passes through the powder compact easily, thus reducing leakage flux. The relative permeability of a powder compact may also be 55 to 450, or 60 to 400. The content ratio of soft magnetic powder in a powder compact is, for example, 85% to 99% by volume. This content ratio is the ratio relative to the volume of the powder compact when the volume is considered to be 100%.

[0067] The particles constituting the soft magnetic powder are, for example, particles of soft magnetic metal, coated particles, or particles of soft magnetic nonmetal. The coated particles consist of soft magnetic metal particles and an insulating coating provided on the outer circumference 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 nonmetal is, for example, ferrite.

[0068] The resin in a composite molded article is, for example, a thermosetting resin or a thermoplastic resin. Thermosetting resins include, for example, epoxy resins, phenolic resins, silicone resins, or urethane resins. Thermoplastic resins include, for example, polyphenylene sulfide (PPS) resins, polyamide (PA) resins, liquid crystal polymers (LCP), polyimide resins, or fluororesins. PA resins include, for example, nylon 6, nylon 66, or nylon 9T.

[0069] The molded composite material may contain fillers. These fillers are non-magnetic powders, such as alumina or silica. The fillers contribute to improved heat dissipation and electrical insulation.

[0070] The relative permeability of each molded body is determined as follows: Ring-shaped measurement samples are cut from both the composite material molded body and the compacted powder molded body. Each measurement sample is wound with 300 turns on the primary side and 20 turns on the secondary side. The initial magnetization curve of the BH is measured in the range H=0(Oe) to 100(Oe), and the maximum value of the slope of this initial magnetization curve is determined. This maximum value is taken as the relative permeability. The magnetization curve referred to here is the so-called DC magnetization curve.

[0071] The content ratio of soft magnetic powder in a composite material molded body and in a compacted powder molded body is considered equivalent to the area ratio of soft magnetic powder in the cross-section of the molded body. The content ratio of soft magnetic powder in the molded body is determined as follows: Observe the cross-section of the molded body with an SEM (scanning electron microscope) and acquire an observation image. The cross-section of the molded body can be any cross-section. The SEM magnification should be between 200x and 500x. Acquire at least 10 observation images. The total cross-sectional area should be 0.1 cm². 2 The above procedure is followed. One observation image may be obtained for each cross-section, or multiple observation images may be obtained for each cross-section. Each obtained observation image is processed to extract the contours of the particles. For example, binarization can be used as an image processing method. The area ratio of soft magnetic particles is calculated for each observation image, and the average value of these area ratios is determined. This average value is considered to be the content ratio of soft magnetic powder.

[0072] ≪Other≫ The reactor 1, although not shown in the illustration, may include a molded resin portion that covers at least a part of the magnetic core 3. The molded resin portion has the function of protecting the magnetic core 3 from the external environment. The molded resin portion may further cover the coil 2. In other words, the molded resin portion is provided so as to cover at least a part of the combination of the coil 2 and the magnetic core 3. The entire combination may be covered by the molded resin portion, or at least one of the first and second surfaces of the outer circumferential surface of the winding portion 20 that face each other in the third direction D3 may be exposed from the molded resin portion without being covered. If the molded resin portion is interposed between the coil 2 and the magnetic core 3, it is easier to insulate the coil 2 and the magnetic core 3. The resin constituting the molded resin portion may be, for example, a resin similar to the resin of the composite material described above. The constituent material of the molded resin portion may contain the filler described above, similar to the composite material.

[0073] [Embodiment 2] <Reactor> The reactor of Embodiment 2 shown in Figures 6 and 7 differs from the reactor 1 of Embodiment 1 in that the second portion 7b has a stepped portion 76 in which the edges of the first and second surfaces facing the third direction D3 of the second portion 7b are locally lowered. The following description will focus on the differences from Embodiment 1. The description of the same configuration and effects as in Embodiment 1 will be omitted. These points are also the same in Embodiment 3, which will be described later.

[0074] The lower step portion 76 is provided on the edge portion of the first and second surfaces of the second portion 7b that connects to the first portion 7a. In this example, the lower step portion 76 consists of the inner edge portion 721 on the first and second surfaces of the base portion 72 of the second portion 7b, and the tip edge portion 731 and both side edges 732 on the first and second surfaces of the protruding portion 73. The lower step portion 76 is covered by the first portion 7a. Therefore, the second portion 7b and the first portion 7a are easily joined together firmly.

[0075] The step difference, which is the length along the third direction D3 between the area of ​​the first and second surfaces excluding the lower step portion 76 and the lower step portion 76, is, for example, 1 mm or more and 10 mm or less. If the step difference is 1 mm or more, the second portion 7b and the first portion 7a are more easily joined firmly. If the step difference is 10 mm or less, the volume of the second portion 7b is less likely to decrease, making it easier to attract magnetic flux. The step difference may also be 1 mm or more and 7 mm or less, 1 mm or more and 4 mm or less, or 1 mm or more and 3 mm or less.

[0076] [Embodiment 3] <Reactor> The reactor of Embodiment 3 shown in Figures 8 to 10 differs from the reactor of Embodiment 1 in that both side surfaces 72b along the second direction D2 at the base end portion 72 are located in a region corresponding to the area between the first corner portion 741 and the second corner portion 742.

[0077] 《Proximal part》 Both side surfaces 72b may be located in a region flush with the outer surface of the winding portion 20. Each side surface 72b is connected to each inner end surface 72a. Two second corners 752 are formed by each inner end surface 72a and each side surface 72b. Each second corner 752 is covered by the first end portion 611. Each second corner 752 is made of a curved surface. The fact that each second corner 752 is made of a curved surface makes it difficult for the constituent material of the first portion 7a to be damaged during the manufacturing of the first core piece 31. The upper and lower limits of the radius of curvature R2 of each corner 751 are the same as the upper and lower limits of the radius of curvature R1 of the first corner 751. The radius of curvature R2 of each corner 751 may be the same as or different from the radius of curvature R1 of the first corner 751 within the above range.

[0078] [Embodiment 4] <Converters / Power Converters> A reactor 1 according to any of Embodiments 1 to 3 can be used for applications that satisfy the following energizing conditions: The maximum DC current is, for example, about 100A to 1000A. The average voltage is, for example, about 100V to 1000V. The operating frequency is, for example, about 5kHz to 100kHz. A reactor 1 according to any of Embodiments 1 to 3 can typically be used as a component of a converter mounted on a vehicle 1200 such as an electric vehicle, a hybrid vehicle, or a fuel cell vehicle, or as a component of a power conversion device equipped with such a converter.

[0079] As shown in Figure 11, the vehicle 1200 includes a main battery 1210, a power converter 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 propulsion. The motor 1220 is typically a three-phase AC motor. The motor 1220 drives the wheels 1250 during propulsion and functions as a generator during regenerative braking. In the case of a hybrid vehicle, the vehicle 1200 is equipped with an engine 1300 in addition to the motor 1220. In Figure 11, an inlet is shown as the charging point of the vehicle 1200, but it can also be equipped with a plug.

[0080] The power converter 1100 includes a converter 1110 and an inverter 1120. The converter 1110 is connected to the main battery 1210. The inverter 1120 is connected to the converter 1110. The inverter 1120 performs mutual conversion between DC and AC. In this example, the converter 1110, when the vehicle 1200 is running, boosts the input voltage of the main battery 1210, which is approximately 200V to 300V, to approximately 400V to 700V and supplies power to the inverter 1120. During regeneration, the converter 1110 steps down 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. When the vehicle 1200 is running, the inverter 1120 converts the DC boosted by the converter 1110 into a predetermined AC and supplies power to the motor 1220. During regeneration, the inverter 1120 converts the AC output from the motor 1220 into DC and outputs it to the converter 1110.

[0081] As shown in Figure 12, the converter 1110 comprises 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 ON / OFF. In this case, the input voltage conversion is step-up or step-down. Power devices such as field-effect transistors and insulated-gate bipolar transistors are used as switching elements 1111. The reactor 1115 utilizes the property of a coil to resist changes in the current that is about to flow through the circuit, and has the function of smoothing the change when the current tries to increase or decrease due to the switching operation. The reactor 1115 is provided as reactor 1 of any of Embodiments 1 to 3. Power conversion devices 1100 and converters 1110 equipped with reactor 1 have excellent productivity.

[0082] Vehicle 1200 includes a converter 1110, a power supply converter 1150, and an auxiliary power converter 1160. The power supply converter 1150 is connected to the main battery 1210. The auxiliary power converter 1160 is connected to the sub-battery 1230, which is the power source for the auxiliary equipment 1240, and the main battery 1210. The auxiliary power converter 1160 converts the high voltage of the main battery 1210 to low voltage. The converter 1110 typically performs DC-DC conversion, while the power supply converter 1150 and the auxiliary power converter 1160 perform AC-DC conversion. Some power supply converters 1150 also perform DC-DC conversion. The reactors of the power supply converter 1150 and the auxiliary power converter 1160 have the same configuration as reactor 1 of any of Embodiments 1 to 3, and reactors with appropriately modified size and shape can be used. Furthermore, for converters that perform input power conversion, such as converters that only boost voltage or converters that only buck voltage, any of the reactors 1 from Embodiment 1 to Embodiment 3 can be used.

[0083] The present invention is not limited to these examples, but is intended to include all modifications within the meaning and scope of the claims as shown, and equivalents thereof.

[0084] For example, the combination of the first core piece and the second core piece may be of the ET type as described in Embodiment 1, etc., or of the EE type. Furthermore, the second portion may have side protruding portions that project from both ends in the direction along the second direction D2 toward the first side core portion and the second side core portion. [Explanation of symbols]

[0085] 1 Reactor 2 coils Volume 20 20a 1st end face 20b 2nd end face 3 Magnetic core 31. First core piece 32 Second Core Piece 33 Gap section 4. Middle Core Section 41. First Middle Core Section 410 axis 41e 1st end face 411 First Middle Section 411a Lateral site 411b Connection site 412 Second Middle Section 42. Second Middle Core Section 42e 2nd end face 51 First side core section 52 Second side core section 61 First end core section 611 First End Section 611a Medial part 611b Central part 611c External part 612 Second End Section 62 Second End Core Section 7a Part 1 71 recess 7b 2nd part 72 Proximal part 72a Inner end surface 72b side 721 Inner edge 73 Protruding part 73a side 73b Tip surface 731 Tip edge 732 Side edge 741 First corner 742 Second corner 751 1st corner 752 Second corner 76 Low section 1100 Power converter 1110 converter 1111 Switching elements 1112 Drive Circuit 1115 Reactor 1120 Inverter 1150 Converter for power supply device 1160 Auxiliary Power Converter 1200 vehicles 1210 Main Battery 1220 Motor 1230 Sub-battery 1240 Auxiliary equipment 1250 wheels 1300 engine A1, A2, A3 area

Claims

1. A core piece comprising a middle core portion disposed inside the coil and an end core portion disposed facing the end face of the coil so as to be connected to the middle core portion, A first part is made of a molded composite material in which soft magnetic powder is dispersed in a resin, A second part comprising a compacted molded body of soft magnetic powder, The second part is, In the end core portion, a base end portion extends along a direction perpendicular to the axis, straddling the axis of the middle core portion, It has a protruding portion that extends along the axis from the base end portion to the middle core portion, The base end portion has two inner end faces that are spaced apart from the end face of the coil, The aforementioned protruding portion is Two side surfaces that face each other across the aforementioned axis and are connected to each of the two inner end surfaces, It has an end face that connects the aforementioned side surfaces, The first portion has a portion that covers from each of the two corners formed by each of the two inner end faces and each of the two side faces to each of the two corners formed by each of the two side faces and the end face, Each of the two aforementioned corners is composed of a curved surface. Core piece.

2. The core piece according to claim 1, wherein the radius of curvature of the curved surface is 0.5 mm or more and 10 mm or less.

3. The core piece according to claim 1 or 2, wherein the base end portion is provided along the entire length in the direction perpendicular to the axis in the end core portion.

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

5. The core piece according to claim 4, wherein the relative permeability of the first portion is 5 or more and 50 or less.

6. Coil and, The magnetic core comprises a first core piece and a second core piece arranged in a first direction along the axis of the coil, The first core piece is the core piece described in claim 1 or claim 2. Reactor.

7. The reactor comprises the reactor described in claim 6, converter.

8. A converter comprising the converter described in claim 7, Power converter.

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