Reactor, converter, and power conversion device

Abstract

To provide a reactor capable of reducing loss of a coil.SOLUTION: A reactor includes a coil and a magnetic core, wherein the magnetic core includes a first core and a second core, the first core includes a first end core part and a side core part, the second core includes a second end core part, at least one of the first core and the second core includes at least a part of a middle core part, the middle core part is arranged in the coil, the side core part is arranged in parallel with the middle core part so as to sandwich the coil, the relative permeability of the first core is lower than the relative permeability of the second core, the side core part has a first end bonded to the first end core part and has a second end bonded to the second end core part, a second interval between the side core part and the coil at the second end is larger than a first interval between the side core part and the coil at the first end, and a ratio of the first interval to the second interval is 0.32 or more and 0.70 or less.SELECTED DRAWING: Figure 3

Description

[Technical field]

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

[0002] A reactor is a component of a converter mounted on a vehicle such as a hybrid vehicle. The reactor includes a coil and a magnetic core. The reactor shown in Figs. 5 to 8 of Patent Document 1 includes one coil and a magnetic core formed by combining two core pieces. This magnetic core is a so-called EE-type core consisting of two E-shaped core pieces. This magnetic core is configured in a θ-shape by combining the two core pieces so that their end faces face each other. The magnetic core has an end core portion, a middle core portion, and a side core portion. The end core portion is disposed so as to face the end face of the coil. The middle core portion is disposed inside the coil. The side core portion is disposed in parallel with the middle core portion so as to sandwich the coil. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2016-201509 A Summary of the Invention [Problem to be solved by the invention]

[0004] It is desirable to reduce coil losses due to leakage flux from the magnetic core.

[0005] An object of the present disclosure is to provide a reactor capable of reducing coil loss. [Means for solving the problem]

[0006] The reactor of the present disclosure includes: The coil has a cylindrical shape and a magnetic core has a θ shape. the coil has a first end surface and a second end surface; The magnetic core includes a first core and a second core, The first core includes a first end core portion and a side core portion, the second core includes a second end core portion, At least one of the first core and the second core includes at least a portion of a middle core portion, the first end core portion is disposed to face the first end surface of the coil, the second end core portion is disposed to face the second end surface of the coil, The middle core portion is disposed within the coil, the side core portion includes a first side core portion and a second side core portion arranged in parallel with the middle core portion so as to sandwich the coil therebetween, the relative permeability of the first core is lower than the relative permeability of the second core, the first side core portion and the second side core portion each have a first end joined to the first end core portion and a second end joined to the second end core portion, a first distance between the first side core portion and the coil and a second distance between the second side core portion and the coil at the second end are larger than a first distance at the first end, The ratio of the first interval to the second interval is equal to or greater than 0.32 and is equal to or less than 0.70. Effect of the Invention

[0007] The reactor of the present disclosure can reduce coil loss. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic perspective view showing a reactor according to the first embodiment. [Diagram 2] FIG. 2 is a schematic plan view showing the reactor according to the first embodiment. [Diagram 3]FIG. 3 is a schematic plan view showing half of the reactor shown in FIG. [Figure 4] FIG. 4 is a schematic plan view showing the reactor according to the second embodiment. [Diagram 5] FIG. 5 is a schematic plan view showing half of the reactor shown in FIG. [Figure 6] FIG. 6 is a schematic diagram showing the power supply system of a hybrid vehicle. [Figure 7] FIG. 7 is a circuit diagram showing a schematic diagram of a power conversion device including a converter. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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

[0010] (1) The reactor of the present disclosure is The coil has a cylindrical shape and a magnetic core has a θ shape. the coil has a first end surface and a second end surface; The magnetic core includes a first core and a second core, The first core includes a first end core portion and a side core portion, the second core includes a second end core portion, At least one of the first core and the second core includes at least a portion of a middle core portion, the first end core portion is disposed to face the first end surface of the coil, the second end core portion is disposed to face the second end surface of the coil, The middle core portion is disposed within the coil, the side core portion includes a first side core portion and a second side core portion arranged in parallel with the middle core portion so as to sandwich the coil therebetween, the relative permeability of the first core is lower than the relative permeability of the second core, the first side core portion and the second side core portion each have a first end joined to the first end core portion and a second end joined to the second end core portion, a first distance between the first side core portion and the coil and a second distance between the second side core portion and the coil at the second end are larger than a first distance at the first end, The ratio of the first interval to the second interval is equal to or greater than 0.32 and is equal to or less than 0.70.

[0011] The reactor of the present disclosure can reduce coil loss. When the relative permeability of the side core portion is low and the relative permeability of the second end core portion is high, leakage flux may occur in the vicinity of the second end, shortcutting from the side core portion to the second end core portion. This leakage flux links with the coil, causing loss in the coil. According to the reactor of the present disclosure, the second interval at the second end is larger than the first interval at the first end, so that leakage flux linking with the coil can be suppressed. Since leakage flux to the coil is reduced, coil loss can be reduced. Since the ratio of the first interval to the second interval is 0.70 or less, leakage flux to the coil is sufficiently suppressed, so that coil loss can be effectively reduced. In particular, when the ratio of the first interval to the second interval is 0.32 or more and 0.70 or less, coil loss can be effectively reduced while suppressing a decrease in inductance.

[0012] By making the magnetic properties of the first core and the second core different, it is possible to adjust the magnetic properties of the entire magnetic core. By making the relative permeability of the first core lower than that of the second core, it is easy to obtain a predetermined inductance.

[0013] (2) In the reactor described in (1) above, The middle core portion has a first middle core portion and a second middle core portion, the first middle core portion is connected to the first end core portion, The second middle core portion may be joined to the second end core portion.

[0014] The above configuration (2) can differentiate the magnetic characteristics of the first middle core portion from the second middle core portion, allowing the magnetic characteristics of the entire magnetic core to be adjusted.

[0015] (3) In the reactor described in (2) above, The middle core portion may have a gap portion between the first middle core portion and the second middle core portion.

[0016] The above configuration (3) makes it possible to adjust the magnetic characteristics of the entire magnetic core by using the gap portion.

[0017] (4) In the reactor according to any one of (1) to (3), The first side core portion and the second side core portion may each have a tapered shape whose width decreases from the first end to the second end.

[0018] The above configuration (4) makes it easy to reduce coil loss.

[0019] (5) In the reactor according to any one of (1) to (3), The first side core portion and the second side core portion may each have a stepped shape whose width narrows from the first end to the second end.

[0020] The above configuration (5) makes it easy to reduce coil loss.

[0021] (6) In the reactor according to any one of (1) to (5), The first core may have a relative magnetic permeability of 5 or more and 50 or less.

[0022] The above configuration (6) makes it easy to obtain a predetermined inductance.

[0023] (7) In the reactor according to any one of (1) to (6), The first core may be formed of a molded body of a composite material in which soft magnetic powder is dispersed in a resin.

[0024] Generally, the relative magnetic permeability of a composite material molded body is low. The above configuration (7) makes it easy to configure a magnetic core in which the relative magnetic permeability of the first core is lower than that of the second core. Since the first core is configured from a composite material molded body, it is easy to adjust the relative magnetic permeability of the first core to, for example, 5 or more and 50 or less.

[0025] (8) In the reactor according to any one of (1) to (7), The second core may have a relative magnetic permeability of 100 or more and 500 or less.

[0026] The above configuration (8) makes it easy to obtain a predetermined inductance.

[0027] (9) In the reactor according to any one of (1) to (8), The second core may be formed of a powder compact.

[0028] Generally, the powder compact has a high relative magnetic permeability. The above configuration (9) makes it easy to configure a magnetic core in which the relative magnetic permeability of the first core is lower than that of the second core. By configuring the second core from the powder compact, it is easy to adjust the relative magnetic permeability of the second core to, for example, 100 or more and 500 or less.

[0029] (10) The converter of the present disclosure is The reactor is provided as described in any one of (1) to (9) above.

[0030] The converter of the present disclosure has low loss because it includes the reactor of the present disclosure.

[0031] (11) The power conversion device of the present disclosure includes: The converter includes the converter described in (10) above.

[0032] The power conversion device of the present disclosure includes the converter of the present disclosure, and therefore has low loss.

[0033] [Details of the embodiment 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. Note that the present invention is not limited to these examples, but is indicated by the claims, and is intended to include all modifications within the meaning and scope of the claims.

[0034] [Embodiment 1] [Reactor] A reactor 1a of the first embodiment will be described with reference to Figs. 1 to 3. The reactor 1a includes a coil 2 and a magnetic core 3. The magnetic core 3 includes a first core 3a and a second core 3b. As shown in Fig. 2, the magnetic core 3 is configured by combining the first core 3a and the second core 3b. The magnetic core 3 is formed in a θ shape by a middle core portion 31, a side core portion 33, and an end core portion 35. Fig. 1 is a perspective view of the reactor 1a seen from above. Fig. 2 is a plan view of the reactor 1a seen from above. Fig. 3 is a partial plan view showing only half of the reactor 1a shown in Fig. 2.

[0035] The reactor 1a of the first embodiment is characterized in that it satisfies the following requirements (a) and (b). (a) The relative permeability of the first core 3a is lower than the relative permeability of the second core 3b. (b) As shown in FIG. 3, the second distance D2 is larger than the first distance D1, and the ratio D1 / D2 of the first distance D1 to the second distance D2 is equal to or greater than 0.32 and equal to or less than 0.70.

[0036] In the reactor 1a, the second distance D2 is larger than the first distance D1, so that the loss in the coil 2 can be reduced. In particular, the ratio D1 / D2 of the first distance D1 to the second distance D2 is 0.32 or more and 0.70 or less, so that the loss in the coil 2 can be effectively reduced while suppressing a decrease in inductance. The configuration of the reactor 1a will be described in detail below.

[0037] <Coil> As shown in Figs. 1 and 2, the coil 2 is disposed in the middle core portion 31 of the magnetic core 3. The coil 2 has a cylindrical shape. The coil 2 has a first end face 2a and a second end face 2b. In this embodiment, the coil 2 is an edgewise coil formed by edgewise winding a rectangular wire.

[0038] The shape of the coil 2 may be a polygonal tube or a cylindrical shape. The polygonal tube means that the contour shape of the end face of the coil 2 is polygonal. The polygonal shape is, for example, a quadrangle, a hexagon, and an octagon. The quadrangle includes a rectangle. The rectangle includes a square. The quadrangle is not limited to a geometric quadrangle, but includes a shape formed by connecting four corners. That is, it also includes a quadrangle with changes made in details, such as a shape in which the four corners are rounded by chamfering, or a shape in which the four corners are chamfered linearly. The cylindrical shape means that the contour shape of the end face of the coil 2 is circular. The circular shape includes not only a perfect circle shape but also an ellipse shape. In this embodiment, the shape of the coil 2 is a rectangular tube.

[0039] <Magnetic core> As shown in Figures 1 and 2, the magnetic core 3 has middle core portions 31, side core portions 33, and end core portions 35. In Figures 2 and 3, the boundaries between the middle core portions 31 and the end core portions 35 and the boundaries between the side core portions 33 and the end core portions 35 are indicated by two-dot chain lines. This also applies to Figures 4 and 5 described below. As shown in Figure 2, the magnetic core 3 has a θ-shape in a plan view.

[0040] In the following description, the X-axis direction, the Y-axis direction, and the Z-axis direction are defined as follows. The X-axis direction is a direction along the axis of the coil 2, and is a direction from the first end face 2a to the second end face 2b. The Y-axis direction is a direction in which the middle core portion 31 and the side core portion 33 are arranged in parallel, and is a direction from the middle core portion 31 to the side core portion 33. The Y-axis direction is perpendicular to the X-axis direction. The direction from the middle core portion 31 to the first side core portion 331 is defined as the Y1 direction. The direction from the middle core portion 31 to the second side core portion 332 is defined as the Y2 direction. The Z-axis direction is perpendicular to both the X-axis direction and the Y-axis direction. The Z direction is a direction from bottom to top when the XY plane including the X-axis and the Y-axis is horizontal.

[0041] The magnetic core 3 forms a closed magnetic circuit in a θ shape. When the coil 2 is energized, magnetic flux flows through the magnetic core 3. The magnetic flux generated by the coil 2 flows from the middle core portion 31, through the end core portions 35 and the side core portions 33, and back to the middle core portion 31. The dashed arrows in Fig. 2 indicate the flow of magnetic flux. This is also true in Fig. 4, which will be described later.

[0042] (Middle core section) The middle core portion 31 is disposed in the coil 2 as shown in FIG. 2. There is one middle core portion 31. The middle core portion 31 extends in the X-axis direction. The direction along the length of the middle core portion 31 coincides with the direction along the axis of the coil 2. The length of the middle core portion 31 is equal to or longer than the length of the coil 2. The length here refers to the distance along the X-axis direction. Both ends of the middle core portion 31 may protrude from both end faces of the coil 2. The protruding portions are also part of the middle core portion 31. The shape of the middle core portion 31 corresponds to the inner shape of the coil 2. In this embodiment, the shape of the middle core portion 31 is substantially rectangular parallelepiped.

[0043] The middle core portion 31 is disposed between the first end core portion 35a and the second end core portion 35b. The first end core portion 35a and the second end core portion 35b will be described later. The middle core portion 31 has a first end 32a and a second end 32b. The first end 32a is connected to the first end core portion 35a. The second end 32b is connected to the second end core portion 35b.

[0044] In this embodiment, the middle core portion 31 has a first middle core portion 31a and a second middle core portion 31b. The first middle core portion 31a and the second middle core portion 31b are arranged in series along the X-axis direction. The boundary between the first middle core portion 31a and the second middle core portion 31b is located inside the coil 2. The first middle core portion 31a includes a first end 32a that is coupled to the first end core portion 35a. The second middle core portion 31b includes a second end 32b that is coupled to the second end core portion 35b. "Coupled" means that they are stuck together and do not separate. The first middle core portion 31a and the first end core portion 35a may be molded integrally. When the first middle core portion 31a and the first end core portion 35a are each separate and independent parts, for example, the first end 32a may be bonded to the first end core portion 35a, or the first middle core portion 31a and the first end core portion 35a may be integrated by being at least partially covered with a resin mold. The second middle core portion 31b and the second end core portion 35b may be molded integrally. When the second middle core portion 31b and the second end core portion 35b are independent separate parts, for example, the second end 32b may be bonded to the second end core portion 35b, or the second middle core portion 31b and the second end core portion 35b may be integrated by being at least partially covered with a resin mold. The resin mold is a molding member formed in a continuous manner so as to cover at least a portion of each of the first core 3a and the second core 3b. In this embodiment, the first middle core portion 31a and the first end core portion 35a are molded integrally. The second middle core portion 31b and the second end core portion 35b are molded integrally.

[0045] The length of each of the first middle core portion 31a and the second middle core portion 31b can be set appropriately. In this embodiment, the length of the first middle core portion 31a is different from the length of the second middle core portion 31b. The first middle core portion 31a may be longer than the second middle core portion 31b. The length of the first middle core portion 31a may be shorter than the second middle core portion 31b. The length of the first middle core portion 31a may be the same as the length of the second middle core portion 31b.

[0046] In this embodiment, the middle core portion 31 has a gap portion 31g. The gap portion 31g is provided between the first middle core portion 31a and the second middle core portion 31b. The middle core portion 31 has the gap portion 31g, so that the inductance can be adjusted. The gap portion 31g is located inside the coil 2. When the gap portion 31g is located inside the coil 2, the leakage magnetic flux from the gap portion 31g is reduced compared to when the gap portion 31g is exposed from the coil 2. Therefore, it is easy to suppress the leakage magnetic flux from the gap portion 31g from interlinking with the coil 2. The loss caused by the leakage magnetic flux from the gap portion 31g can be reduced. The length of the gap portion 31g is appropriately set so as to obtain a predetermined inductance. The length of the gap portion 31g is, for example, 0.1 mm or more and 3 mm or less, 0.3 mm or more and 2.5 mm or less, or further 0.5 mm or more and 2 mm or less. The gap portion 31g may be an air gap. The gap portion 31g may be made of a non-magnetic material such as resin or ceramics. When the middle core portion 31 has the gap portion 31g, the length of the middle core portion 31 is the total length of the first middle core portion 31a, the second middle core portion 31b, and the gap portion 31g. The gap portion 31g may be omitted. When the gap portion 31g is omitted, the first middle core portion 31a and the second middle core portion 31b are in contact with each other, and there is substantially no gap between the first middle core portion 31a and the second middle core portion 31b.

[0047] (End core part) As shown in FIG. 2, the end core portion 35 is disposed outside the coil 2. The end core portion 35 is disposed so as to face both end faces of the coil 2. The number of end core portions 35 is two. The end core portion 35 has a first end core portion 35a and a second end core portion 35b. The first end core portion 35a and the second end core portion 35b are disposed at an interval in the X-axis direction. The first end core portion 35a and the second end core portion 35b each have an inner surface facing each other. The first end core portion 35a faces the first end face 2a of the coil 2. The first end 32a of the middle core portion 31 is coupled to the first end core portion 35a. The second end core portion 35b faces the second end face 2b of the coil 2. The second end core portion 35b is coupled to the second end face 2b of the coil 2.

[0048] The shape of each of the first end core portion 35a and the second end core portion 35b is not particularly limited as long as it is a shape that forms a predetermined magnetic path. In this embodiment, each of the first end core portion 35a and the second end core portion 35b is substantially rectangular parallelepiped in shape.

[0049] (Side core part) As shown in FIG. 2 , the side core portions 33 are disposed outside the coil 2. The side core portions 33 are disposed in parallel with the middle core portion 31 so as to sandwich the coil 2. There are two side core portions 33. The side core portions 33 extend in the X-axis direction. The direction along the length of the side core portions 33 is parallel to the direction along the length of the middle core portion 31. The length of the side core portions 33 is equal to the length of the middle core portion 31.

[0050] The side core portion 33 has a first side core portion 331 and a second side core portion 332. The first side core portion 331 and the second side core portion 332 are arranged at an interval in the Y axis direction. The first side core portion 331 is arranged away from the middle core portion 31 in the Y1 direction. The second side core portion 332 is arranged away from the middle core portion 31 in the Y2 direction. In this embodiment, the first side core portion 331 and the second side core portion 332 are arranged symmetrically with respect to the center line of the middle core portion 31.

[0051] The first side core portion 331 and the second side core portion 332 are disposed between the first end core portion 35a and the second end core portion 35b. The first side core portion 331 and the second side core portion 332 each have a first end 34a and a second end 34b. The first end 34a is joined to the first end core portion 35a. The second end 34b is joined to the second end core portion 35b.

[0052] In this embodiment, the side core portion 33 and the first end core portion 35a are integrally molded. The side core portion 33 and the first end core portion 35a may be separate independent parts. In this case, for example, the first end 34a may be bonded to the first end core portion 35a, or the side core portion 33 and the first end core portion 35a may be integrated by at least a part of them being covered with a resin mold. In this embodiment, the side core portion 33 and the second end core portion 35b are separate independent parts. The side core portion 33 and the second end core portion 35b are integrated by a resin mold (not shown). The second end 34b of the side core portion 33 may be bonded to the second end core portion 35b.

[0053] <Spacing between side core and coil> In this embodiment, the interval between the first side core portion 331 and the coil 2 and the interval between the second side core portion 332 and the coil 2 are not constant along the X-axis direction. In other words, the interval between the side core portion 33 and the coil 2 is not constant along the entire length of the side core portion 33. The interval between the side core portion 33 and the coil 2 increases from the first end 34a toward the second end 34b. The interval between the side core portion 33 and the coil 2 refers to the interval between the inner surface of the side core portion 33 and the outer peripheral surface of the coil 2. The inner surface of the side core portion 33 is the surface facing the outer peripheral surface of the coil 2.

[0054] The interval between the side core portion 33 and the coil 2 will be described in detail with reference to FIG. 3. FIG. 3 shows only one half of the reactor 1a shown in FIG. 2, which is divided into two parts by the center line of the middle core portion 31, including the first side core portion 331. Here, the interval between the first side core portion 331 and the coil 2 will be described with reference to FIG. 3, but the interval between the second side core portion 332 and the coil 2 is similar. The interval between the first side core portion 331 and the coil 2 is larger in the second interval D2 at the second end 34b than in the first interval D1 at the first end 34a. The first interval D1 refers to the interval between the inner surface located at the first end 34a among the inner surfaces of the first side core portion 331 and a virtual surface extending the outer circumferential surface of the coil 2. When the corner between the end face of the first end 34a and the inner surface is chamfered, it is considered that there is no chamfering. In other words, the interval between the corner between the extended surface of the end face of the first end 34a and the extended surface of the inner surface and the virtual surface is considered to be the first interval D1. The second distance D2 refers to the distance between the inner surface located at the second end 34b among the inner surfaces of the first side core portion 331 and an imaginary plane extending from the outer circumferential surface of the coil 2. When the corner between the end face of the second end 34b and the inner surface is chamfered, it is considered that there is no chamfering. In other words, the distance between the corner between the extended surface of the end face of the second end 34b and the extended surface of the inner surface and the imaginary plane is considered to be the second distance D2.

[0055] The ratio of the first interval D1 to the second interval D2 is 0.32 or more and 0.70 or less. The ratio of the first interval D1 to the second interval D2 is expressed as D1 / D2. The smaller the ratio D1 / D2, the larger the second interval D2. The larger the second interval D2, the larger the interval between the side core portion 33 and the coil 2 in the region near the second end 34b. Therefore, it is possible to suppress the leakage flux that takes a shortcut from the side core portion 33 toward the second end core portion 35b in the region near the second end 34b from interlinking with the coil 2. Since the leakage flux to the coil 2 is reduced, the loss of the coil 2 can be reduced. Since the ratio D1 / D2 is 0.70 or less, the leakage flux to the coil 2 is sufficiently suppressed, so that the loss of the coil 2 can be effectively reduced. If the ratio D1 / D2 is too small, that is, if the second interval D2 is too large, there is a risk that the inductance will decrease, and it may be difficult to obtain a predetermined inductance. When the ratio D1 / D2 is 0.32 or more, it is easy to suppress a decrease in inductance. The ratio D1 / D2 may be further set to 0.35 or more and 0.70 or less, or 0.40 or more and 0.60 or less.

[0056] <Side core shape> The side core portion 33 has a shape in which the width of the side core portion 33 narrows from the first end 34a toward the second end 34b. The side core portion 33 only needs to have a width of the second end 34b narrower than the width of the first end 34a. The side core portion 33 only needs to have a narrower width at least in a portion between the first end 34a and the second end 34b, and may have a constant width in a portion between the first end 34a and the second end 34b. The width of the side core portion 33 is the dimension of the side core portion 33 in the Y-axis direction. In this embodiment, the shape of the first side core portion 331 and the shape of the second side core portion 332 are symmetrical with respect to the center line of the middle core portion 31.

[0057] The shape of the side core portion 33 in this embodiment will be described in detail with reference to FIG. 3. Here, the shape of the first side core portion 331 will be described. The first side core portion 331 has a tapered shape. The tapered shape refers to a shape having a portion whose width continuously narrows from the first end 34a to the second end 34b. In this embodiment, the first side core portion 331 is formed in a tapered shape over the entire length. The inner surface of the first side core portion 331 has an inclined surface 33t inclined with respect to the outer circumferential surface of the coil 2. The inclined surface 33t inclines from the first end 34a to the second end 34b so as to move away from the outer circumferential surface of the coil 2. The angle of the inclined surface 33t with respect to the outer circumferential surface of the coil 2 is appropriately set so that the ratio of the first interval D1 to the second interval D2 satisfies a predetermined range. The angle of the inclined surface 33t refers to the angle between the inclined surface 33t and the outer circumferential surface of the coil 2. The outer circumferential surface of the coil 2 is parallel to the X-axis. The angle of the inclined surface 33t can be appropriately set depending on the length of the first side core portion 331. The angle of the inclined surface 33t is, for example, not less than 1° and less than 5°, and further not less than 2° and not more than 4°.

[0058] (First core, second core) 2, the magnetic core 3 is composed of a first core 3a and a second core 3b. In this embodiment, the first core 3a has an E-shape, and the second core 3b has a T-shape. In other words, the magnetic core 3 is an ET type composed of the E-shaped first core 3a and the T-shaped second core 3b.

[0059] (First Core) The first core 3a includes a first end core portion 35a and a side core portion 33. In this embodiment, the first core 3a has a first end core portion 35a, a first middle core portion 31a, a first side core portion 331, and a second side core portion 332. The first middle core portion 31a, the first end core portion 35a, the first side core portion 331, and the second side core portion 332 are integrally molded. Since the first core 3a is an integrally molded product, the core portions constituting the first core 3a are made of the same material. That is, the magnetic properties of the core portions constituting the first core 3a are substantially the same. The shape of the first core 3a is E-shaped in a plan view.

[0060] (Second core) The second core 3b includes a second end core portion 35b. In this embodiment, the second core 3b has a second end core portion 35b and a second middle core portion 31b. The second end core portion 35b and the second middle core portion 31b are integrally molded. Since the second core 3b is an integrally molded product, the core portions constituting the second core 3b are made of the same material. That is, the magnetic properties of the core portions constituting the second core 3b are substantially the same. The shape of the second core 3b is T-shaped in a plan view.

[0061] At least one of the first core 3a and the second core 3b includes at least a part of the middle core portion 31. The first core 3a may have the entire middle core portion 31. When the first core 3a has the entire middle core portion 31, the second core 3b has only the second end core portion 35b. In this case, the shape of the second core 3b is I-shaped in plan view. The second core 3b may have the entire middle core portion 31. When the second core 3b has the entire middle core portion 31, the first core 3a is composed of a first end core portion 35a, a first side core portion 331, and a second side core portion 332. In this case, the shape of the first core 3a is U-shaped in plan view.

[0062] <First core - second relative permeability> The relative permeability of the first core 3a is lower than that of the second core 3b. That is, in the magnetic core 3, the relative permeability of the side core portion 33 is lower than that of the second end core portion 35b. The relative permeability of each of the first core 3a and the second core 3b is appropriately set so as to obtain a predetermined inductance while satisfying the above relationship. The relative permeability of the first core 3a is, for example, 5 or more and 50 or less. The relative permeability of the second core 3b is, for example, 50 or more and 500 or less. If the relative permeability of the first core 3a is in the range of 5 or more and 50 or less and the relative permeability of the second core 3b is in the range of 50 or more and 500 or less, a predetermined inductance is easily obtained. The relative permeability of the first core 3a may be 10 or more and 45 or less, or further 15 or more and 40 or less. The relative permeability of the second core 3b may be 100 or more and 450 or less, or further 150 or more and 400 or less. The difference between the relative permeability of the first core 3a and the relative permeability of the second core 3b is, for example, not less than 50. The difference between the relative permeability of the first core 3a and the relative permeability of the second core 3b may be not less than 50 and not more than 450, or further not less than 100 and not more than 400.

[0063] The relative permeability can be calculated as follows: A ring-shaped measurement sample is cut out from each of the first core 3a and the second core 3b. Each measurement sample is wound with 300 turns on the primary side and 20 turns on the secondary side. The BH initial magnetization curve is measured in the range of H=0 (Oe) to 100 (Oe), and the maximum value of B / H of this BH initial magnetization curve is calculated. This maximum value is the relative permeability. The magnetization curve referred to here is the so-called DC magnetization curve.

[0064] <Materials of the first and second cores> The first core 3a and the second core 3b are each composed of a molded body of a soft magnetic material. The molded body is, for example, a powder compact or a composite material compact. The first core 3a and the second core 3b are composed of molded bodies of different materials. The different materials include not only the case where the materials of the individual components are different in each molded body constituting the first core 3a and the second core 3b, but also the case where the materials of the individual components are the same but the contents of the components are different. For example, even if the first core 3a and the second core 3b are composed of a powder compact, if at least one of the material and the content of the soft magnetic powder constituting the powder compact is different, they are different materials. Also, even if the first core 3a and the second core 3b are composed of a composite material compact, if at least one of the material and the content of the soft magnetic powder constituting the composite material is different, they are different materials.

[0065] The powder compact is formed by compression molding raw material powder containing soft magnetic powder. The powder compact contains a larger amount of soft magnetic powder than the compact of the composite material. Therefore, the powder compact has higher magnetic properties than the compact of the composite material. The magnetic properties are, for example, relative permeability and saturation magnetic flux density. The powder compact may contain, for example, at least one of a binder resin and a molding aid. The content of the soft magnetic powder in the powder compact is, for example, 85% by volume or more and 99.99% by volume or less, when the powder compact is 100% by volume.

[0066] The composite material compact is formed by dispersing soft magnetic powder in resin. The composite material compact is obtained by filling a mold with a fluid material in which soft magnetic powder is dispersed in unsolidified resin, and solidifying the resin. The content of the soft magnetic powder in the composite material compact can be easily adjusted. Therefore, the magnetic properties of the composite material compact can be easily adjusted. 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, when the composite material compact is 100% by volume.

[0067] The particles constituting the soft magnetic powder are at least one selected from the group consisting of soft magnetic metal particles, coated particles having an insulating coating on the outer periphery of soft magnetic metal particles, and soft magnetic nonmetal particles. The soft magnetic metal is, for example, pure iron or an iron-based alloy. The iron-based alloy is, for example, an Fe (iron)-Si (silicon) alloy or an Fe-Ni (nickel) alloy. The insulating coating is, for example, a phosphate. The soft magnetic nonmetal is, for example, a ferrite.

[0068] In this embodiment, the first core 3a is made of a composite material molded body. The second core 3b is made of a powder compact. The first core 3a is made of a composite material molded body and the second core 3b is made of a powder compact, so that the magnetic properties of the entire magnetic core 3 can be adjusted. In addition, when the first core 3a is made of a composite material molded body, the relative magnetic permeability of the first core 3a is likely to be 5 or more and 50 or less. When the second core 3b is made of a powder compact, the relative magnetic permeability of the second core 3b is likely to be 100 or more and 500 or less.

[0069] [Embodiment 2] A reactor 1b of the second embodiment will be described with reference to Fig. 4 and Fig. 5. The reactor 1b of the second embodiment differs from the reactor 1a of the first embodiment in that the side core portion 33 has a stepped shape. The following description will focus on the differences from the first embodiment. Configurations similar to those of the first embodiment are given the same reference numerals and description thereof will be omitted.

[0070] The shape of the side core portion 33 in this embodiment will be described in detail with reference to FIG. 5. Here, the shape of the first side core portion 331 will be described. The side core portion 33 has a stepped shape. The stepped shape refers to a shape having a portion whose width gradually narrows from the first end 34a to the second end 34b. The inner surface of the first side core portion 331 has a step portion 33s. In this embodiment, the step portion 33s is located at the center of the length of the first side core portion 331. The first side core portion 331 is divided into two regions by one step portion 33s. The region from the first end 34a to the step portion 33s is the first region 341. The region from the step portion 33s to the second end 34b is the second region 342. The width of the second region 342 is narrower than the width of the first region 341. The inner side surface of the first region 341 and the inner side surface of the second region 342 are each parallel to the outer circumferential surface of the coil 2. The interval between the inner surface of the second region 342 and the outer peripheral surface of the coil 2 is larger than the interval between the inner surface of the first region 341 and the outer peripheral surface of the coil 2. The width of the step 33s is appropriately set so that the ratio of the first interval D1 to the second interval D2 satisfies a predetermined range. The width of the step 33s corresponds to the distance along the Y-axis direction of the step 33s. The width of the step 33s is equal to the difference between the distance from the outer peripheral surface of the coil 2 to the inner surface of the second region 342 and the distance from the outer peripheral surface of the coil 2 to the inner surface of the first region 341. In other words, the width of the step 33s is expressed as D2-D1. The width of the step 33s is, for example, 1 mm or more and less than 5 mm, and further 1.25 mm or more and 4 mm or less.

[0071] In this embodiment, the number of step portions 33s is one, but there may be multiple step portions 33s. When the number of step portions 33s is n, the number of regions constituting the side core portion 33 is n+1. The n+1th region is closer to the second end 34b than the nth region, and the width of the n+1th region is narrower than the width of the nth region. The width gradually narrows from the first region toward the n+1th region.

[0072] The shape of the side core portion 33 may be a combination of a tapered shape and a stepped shape. Modified examples of the shape of the side core portion 33 include the following shapes. (1) In FIG. 5, first region 341 may have a tapered shape, and second region 342 may have no step portion 33s with respect to first region 341 and may have a constant width. (2) In FIG. 5, first region 341 may be tapered, and second region 342 may have step 33s with respect to first region 341 and may have a constant width. (3) In FIG. 5, first region 341 has a shape with a constant width, and second region 342 does not have step portion 33s with respect to first region 341, and may have a tapered shape. (4) In FIG. 5, first region 341 has a shape with a constant width, and second region 342 has step portion 33s with respect to first region 341, and may have a tapered shape.

[0073] [Embodiment 3] [Converter / Power Conversion Device] The reactor of the embodiment can be used in applications that satisfy the following energization conditions. The energization conditions are, for example, a maximum DC current of about 100 A to 1000 A, an average voltage of about 100 V to 1000 V, and an operating frequency of about 5 kHz to 100 kHz. The reactor of the embodiment can be used as a component of a converter mounted on a vehicle such as an electric vehicle or a hybrid vehicle, and as a component of a power conversion device including the converter.

[0074] As shown in Fig. 6, 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. The motor 1220 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. Although Fig. 6 shows an inlet as a charging point for the vehicle 1200, a form including a plug may be used.

[0075] 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 about 200V to 300V, to about 400V to 700V when the vehicle 1200 is running, and supplies power to the inverter 1120. During regeneration, the converter 1110 lowers 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. During regeneration, the inverter 1120 converts the AC output from the motor 1220 into DC and outputs it to the converter 1110.

[0076] As shown in FIG. 7, 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 switching on and off. The conversion of the input voltage means stepping up and down the voltage here. The switching elements 1111 are power devices such as field effect transistors and insulated gate bipolar transistors. The reactor 1115 has a function of smoothing the change when the current increases or decreases due to the switching operation by utilizing the properties of a coil that prevents a change in the current flowing through the circuit. The reactor 1115 includes the reactor of the embodiment. By including the reactor of the embodiment, the loss of the power conversion device 1100 and the converter 1110 is small.

[0077] In addition to the converter 1110, the vehicle 1200 includes a power supply converter 1150 connected to the main battery 1210, and an auxiliary power converter 1160 connected to the sub-battery 1230 serving as a power source for the auxiliary devices 1240 and the main battery 1210 to convert the high voltage of the main battery 1210 to a 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 of the power supply converters 1150 perform DC-DC conversion. The reactors of the power supply converter 1150 and the auxiliary power converter 1160 may have the same configuration as the reactor of the embodiment, and may be appropriately changed in size or shape. The reactor of the embodiment may also be used as a converter that converts input power and that only boosts or only lowers the voltage.

[0078] <Test Example 1> The inductance and loss of a reactor having a configuration similar to that of the reactor 1a of the first embodiment were evaluated.

[0079] In Test Example 1, reactors of Sample No. 1-0 to Sample No. 1-7 shown in Table 1 were designed. Sample No. 1-0 to Sample No. 1-7 are models in which the angle of the inclined surface 33t on the inner surface of the side core portion 33 is changed in the range of 0° to 7°. The basic configuration of the designed reactor is shown below.

[0080] (Magnetic core size) Length of magnetic core 3 L: 80mm Magnetic core 3 width W: 65mm Height of magnetic core 3: 25mm 1, the length L is the dimension of the magnetic core 3 in the X-axis direction. The width W is the dimension of the magnetic core 3 in the Y-axis direction. The height H is the dimension of the magnetic core 3 in the Z-axis direction. (Size of each core) Length of middle core 31: 53mm Width of middle core 31: 25mm Length of each of the first side core portion 331 and the second side core portion 332: 53 mm Width of each of the first side core portion 331 and the second side core portion 332: 9 mm Length of each of the first end core portion 35a and the second end core portion 35b: 13.5 mm Width of each of the first end core portion 35a and the second end core portion 35b: 65 mm Length of gap 31g: 2mm The length of each core portion is the dimension in the X-axis direction. The width of each core portion is the dimension in the Y-axis direction. The height of each core portion, i.e., the dimension in the Z-axis direction, is 25 mm.

[0081] Relative permeability of first core 3a: 20 Relative permeability of second core 3b: 200

[0082] The angles of the inclined surfaces in Sample No. 1-0 to Sample No. 1-7 are shown in Table 1. The first distance D1, the second distance D2, and the ratio (D1 / D2) of the first distance D1 to the second distance D2 for each sample are also shown in Table 1. In Sample No. 1-0, in which the angle of the inclined surface 33t is 0°, the distance between the side core portion 33 and the coil 2 is constant over the entire length of the side core portion 33. That is, in Sample No. 1-0, the ratio of the first distance D1 to the second distance D2 is 1. The first distance D1 and the second distance D2 in Sample No. 1-0 are each 2 mm.

[0083] The inductance and loss of each sample reactor were analyzed using JMAG-Designer21.0, a commercially available electromagnetic field analysis software made by JSOL Corporation, to perform a magnetic field transient response analysis.

[0084] (Inductance Analysis) The inductance was analyzed when currents of 0A to 400A were passed through the coil. The maximum inductance value was obtained from the amount of magnetic flux linkage in the coil when the current value was 0A. The inductance of each sample is shown in Table 1. The inductance shown in Table 1 is shown as a ratio, with the inductance of sample No. 1-0 as the reference (100%).

[0085] (Loss Analysis) The loss was analyzed when a DC current of 0A, an input voltage of 300V, an output voltage of 600V, and a frequency of 20kHz were applied to the coil. The coil loss was obtained from the magnetic flux density distribution and current density distribution. The coil loss for each sample is shown in Table 1. The coil loss shown in Table 1 is shown as a percentage, with the coil loss of sample No. 1-0 taken as the reference (100%).

[0086] [Table 1]

[0087] As shown in Table 1, the coil loss of Sample No. 1-1 to Sample No. 1-7 is reduced by 1% or more compared to the coil loss of Sample No. 1-0. In Sample No. 1-1 to Sample No. 1-7, the second distance D2 is larger than the first distance D1, and the ratio of the first distance D1 to the second distance D2 is 0.70 or less. From the results of Sample No. 1-1 to Sample No. 1-7, it can be seen that the larger the second distance D2 is, that is, the smaller the ratio of the first distance D1 to the second distance D2 is, the easier it is to obtain the effect of reducing the coil loss. However, it can be seen that the smaller the ratio of the first distance D1 to the second distance D2 is, the smaller the inductance is compared to the inductance of Sample No. 1-0. The inductance of Sample No. 1-1 to Sample No. 1-4 is reduced by less than 5% compared to the inductance of Sample No. 1-0. If the reduction in inductance is less than 5%, it can be considered to be approximately the same as Sample No. 1-0. In samples No. 1-1 to No. 1-4, the ratio of the first distance D1 to the second distance D2 is 0.32 or more. It is considered that the ratio of the first distance D1 to the second distance D2 that can maintain a good inductance and reduce coil loss is 0.32 or more and 0.70 or less.

[0088] <Test Example 2> The inductance and loss of a reactor having a similar configuration to the reactor 1b of the second embodiment were evaluated.

[0089] In Test Example 2, reactors were designed as Sample No. 2-0 to Sample No. 2-4 shown in Table 2. Samples No. 2-0 to No. 2-4 are models in which the width of the step portion 33s on the inner surface of the side core portion 33 is changed in the range from 0 mm to 5 mm. The basic configuration of the designed reactor is the same as that of Test Example 1.

[0090] The width of the step in the reactors of samples No. 2-0 to No. 2-4 is shown in Table 2. The first distance D1, the second distance D2, and the ratio (D1 / D2) of the first distance D1 to the second distance D2 for each sample are also shown in Table 1. In sample No. 2-0, in which the width of the step is 0 mm, the distance between the side core portion 33 and the coil 2 is constant over the entire length of the side core portion 33. That is, in sample No. 2-0, the ratio of the first distance D1 to the second distance D2 is 1. The first distance D1 and the second distance D2 in sample No. 2-0 are each 2 mm.

[0091] The inductance and loss of the reactor of each sample were analyzed. The inductance and coil loss of each sample were determined in the same manner as in Test Example 1. The inductance and coil loss of each sample are shown in Table 2. The inductance shown in Table 2 is shown as a ratio with the inductance of sample No. 2-0 as the reference (100%). The coil loss shown in Table 2 is shown as a ratio with the coil loss of sample No. 2-0 as the reference (100%).

[0092] [Table 2]

[0093] As shown in Table 2, the coil loss of Sample No. 2-1 to Sample No. 2-4 is reduced by 1% or more, and even 2% or more, compared to the coil loss of Sample No. 2-0. Sample No. 2-1 to Sample No. 2-4 have a ratio of the first distance D1 to the second distance D2 of 0.70 or less. The inductance of Sample No. 2-1 to Sample No. 2-3 is reduced by less than 5% compared to the inductance of Sample No. 2-0. From the results of Test Example 2 as well, it is considered that the ratio of the first distance D1 to the second distance D2 that can maintain a good inductance and have the effect of reducing coil loss is 0.32 or more and 0.70 or less. [Explanation of symbols]

[0094] 1a, 1b Reactor 2 Coil 2a first end face, 2b second end face 3. Magnetic core 3a 1st core, 3b 2nd core 31 Middle Core Division 31a first middle core portion, 31b second middle core portion 31g Gap section 32a first end, 32b second end 33 Side core part 331 first side core portion, 332 second side core portion 33t slope, 33s step 34a first end, 34b second end 341 first area, 342 second area 35 End Core Section 35a first end core portion, 35b second end core portion D1 first interval, D2 second interval L length, W width, H height 1100 Power conversion device 1110 converter, 1111 switching element, 1112 drive circuit 1115 Reactor, 1120 Inverter 1150 Converter for power supply device, 1160 Converter for auxiliary power supply 1200 vehicles 1210 Main battery, 1220 Motor, 1230 Sub battery 1240 Auxiliary equipment, 1250 Wheels 1300 Engine

Claims

1. The coil has a cylindrical shape and a magnetic core has a θ shape. the coil has a first end surface and a second end surface; The magnetic core includes a first core and a second core, The first core includes a first end core portion and a side core portion, the second core includes a second end core portion, At least one of the first core and the second core includes at least a portion of a middle core portion, the first end core portion is disposed to face the first end surface of the coil, the second end core portion is disposed to face the second end surface of the coil, The middle core portion is disposed within the coil, the side core portion includes a first side core portion and a second side core portion arranged in parallel with the middle core portion so as to sandwich the coil therebetween, the relative permeability of the first core is lower than the relative permeability of the second core, the first side core portion and the second side core portion each have a first end joined to the first end core portion and a second end joined to the second end core portion, a first distance between the first side core portion and the coil and a second distance between the second side core portion and the coil at the second end are larger than a first distance at the first end, a ratio of the first interval to the second interval is 0.32 or more and 0.70 or less; Reactor.

2. The middle core portion has a first middle core portion and a second middle core portion, the first middle core portion is connected to the first end core portion, The reactor according to claim 1 , wherein the second middle core portion is coupled to the second end core portion.

3. The reactor according to claim 2 , wherein the middle core portion has a gap portion between the first middle core portion and the second middle core portion.

4. The reactor according to claim 1 , wherein each of the first side core portion and the second side core portion has a tapered shape whose width decreases from the first end toward the second end.

5. The reactor according to claim 1 , wherein each of the first side core portion and the second side core portion has a stepped shape whose width narrows from the first end toward the second end.

6. The reactor according to claim 1 , wherein the first core has a relative magnetic permeability of 5 or more and 50 or less.

7. The reactor according to claim 1 , wherein the first core is formed of a molded body made of a composite material in which soft magnetic powder is dispersed in a resin.

8. The reactor according to claim 1 , wherein the second core has a relative permeability of 100 or more and 500 or less.

9. The reactor according to claim 1 , wherein the second core is formed of a powder compact.

10. A reactor comprising the reactor according to any one of claims 1 to 9. converter.

11. A converter comprising: Power conversion equipment.

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