Reactors, converters, and power conversion devices

Abstract

To provide a reactor capable of securing high inductance even under a high current.SOLUTION: A reactor comprises a coil and a magnetic core consisting of a plurality of core pieces. The magnetic core is θ-shaped and the magnetic core includes: a middle core part which is disposed inside of the coil; side core parts which are disposed in parallel with the middle core part so as to hold the coil therebetween; and end core parts which are disposed so as to face both ends of the coil. The plurality of core pieces includes a low B core piece and a high B core piece, and the low B core piece and the high B core piece consist of materials of different saturated magnetic flux densities. The saturated magnetic flux density of the low B core piece is lower than the saturated magnetic flux density of the high B core piece, and a ratio BS of the magnetic core is 0.5 or more and 1.0 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 Art

[0002] Patent Document 1 discloses a reactor including a coil and a magnetic core. The magnetic core in the reactor of Patent Document 1 is a combination of a first core portion and a second core portion. The first core portion and the second core portion are each formed of a molded body of a different material.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In order to cope with an increase in the current of a converter, there is a need for a reactor that can ensure a high inductance even at high currents.

[0005] One object of the present disclosure is to provide a reactor that can ensure a high inductance even at high currents.

Means for Solving the Problems

[0006] The reactor of the present disclosure includes a coil and a magnetic core composed of a plurality of core pieces, the shape of the magnetic core is θ-shaped, the magnetic core includes a middle core portion disposed inside the coil, a side core portion disposed in parallel with the middle core portion so as to sandwich the coil, and an end core portion disposed to face both ends of the coil. The plurality of core pieces include low-B core pieces and high-B core pieces. The low-B core piece and the high-B core piece are composed of materials with different saturation magnetic flux densities. The saturation magnetic flux density of the low-B core piece is lower than that of the high-B core piece. The ratio BS of the magnetic core is 0.5 or more and 1.0 or less. The ratio BS is the ratio of the sum of the product BSe, which is the product of the saturation magnetic flux density Be and cross-sectional area Se in the end core, and the product BSs, which is the product of the saturation magnetic flux density Bs and cross-sectional area Ss in the side core, to the product BSm, which is the product of the saturation magnetic flux density Bm and cross-sectional area Sm in the middle core. [Effects of the Invention]

[0007] The reactor of this disclosure can ensure high inductance even at high currents. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a schematic perspective view of a reactor according to an embodiment. [Figure 2] Figure 2 is a schematic plan view of the reactor according to the embodiment. [Figure 3] Figure 3 is a schematic plan view showing the configuration of the magnetic core provided in the reactor according to the embodiment. [Figure 4] Figure 4 is a cross-sectional view taken along line IV-IV in Figure 2. [Figure 5] Figure 5 is a cross-sectional view of the VV section of Figure 2. [Figure 6] Figure 6 is a schematic plan view showing another example of the configuration of a magnetic core provided in a reactor according to the embodiment. [Figure 7] Figure 7 is a schematic plan view showing another example of the configuration of a magnetic core provided in a reactor according to the embodiment. [Figure 8] Figure 8 is a schematic plan view showing another example of the configuration of a magnetic core provided in a reactor according to the embodiment. [Figure 9] Figure 9 is a schematic diagram showing the power supply system of a hybrid vehicle. [Figure 10] FIG. 10 is a circuit diagram schematically showing a power conversion device including a converter.

Mode for Carrying Out the Invention

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

[0010] (1) The reactor of the present disclosure includes a coil and a magnetic core composed of a plurality of core pieces, the shape of the magnetic core is θ-shaped, the magnetic core includes a middle core portion disposed inside the coil, a side core portion disposed in parallel with the middle core portion so as to sandwich the coil, and an end core portion disposed facing both ends of the coil, the plurality of core pieces include low-B core pieces and high-B core pieces, the low-B core pieces and the high-B core pieces are made of materials having different saturation magnetic flux densities, the saturation magnetic flux density of the low-B core pieces is lower than that of the high-B core pieces, the specific BS of the magnetic core is 0.5 or more and 1.0 or less, the specific BS is the ratio of the sum of the product BSe of the saturation magnetic flux density Be and the cross-sectional area Se in the end core portion and the product BSs of the saturation magnetic flux density Bs and the cross-sectional area Ss in the side core portion to the product BSm of the saturation magnetic flux density Bm and the cross-sectional area Sm in the middle core portion.

[0011] The reactor of this disclosure can ensure high inductance even at high currents. A magnetic core with a ratio BS of 0.5 or more and 1.0 or less can delay magnetic saturation in the middle core portion, improving inductance at high currents. "Delaying magnetic saturation" means suppressing magnetic saturation at a specific current value and preventing a decrease in inductance at that current value. For example, while a conventional reactor may experience magnetic saturation at 300A, a reactor with the configuration of this disclosure will cause magnetic saturation to occur at 350A. In this case, the reactor with the configuration of this disclosure can maintain high inductance at 300A. In this way, delaying magnetic saturation allows for a higher current value at which magnetic saturation occurs.

[0012] The reactor of this disclosure does not have a magnetic core composed of a single material. In the reactor of this disclosure, the multiple core pieces constituting the magnetic core include high-B core pieces and low-B core pieces composed of materials with different saturation magnetic flux densities. The fact that the magnetic core is composed of multiple materials makes it easier to adjust the overall magnetic properties of the magnetic core to obtain a predetermined inductance.

[0013] (2) In the reactor described in (1) above, The saturation magnetic flux density of the aforementioned high-B core piece is 1.0T or more and 2.5T or less. The saturation magnetic flux density of the low-B core piece may be 0.5T or more and 1.7T or less.

[0014] The configuration described in (2) above makes it easier to obtain the desired inductance.

[0015] (3) In the reactor described in (1) or (2) above, The aforementioned high-B core piece may be made of a compacted body of soft magnetic powder.

[0016] Generally, compacted soft magnetic powders have a high saturation magnetic flux density. Because the high-B core pieces are composed of compacted powders, it is easy to adjust the saturation magnetic flux density of the high-B core pieces between 1.0T and 2.5T.

[0017] (4) In any of the reactors described in (1) to (3) above, The low-B core piece may be composed of a molded body of a composite material in which soft magnetic powder is dispersed in a resin.

[0018] Generally, the saturation magnetic flux density of a composite material molded body is low. Because the low-B core piece is composed of a composite material molded body, it is easier to adjust the saturation magnetic flux density of the low-B core piece between 0.5T and 1.7T.

[0019] (5) In any of the reactors described in (1) to (4) above, The number of the aforementioned core pieces is two. The number of low-B core pieces and the number of high-B core pieces may each be one.

[0020] The configuration described in (5) above has good manufacturability for the magnetic core because it requires a small number of core pieces.

[0021] (6) In the reactor described in (5) above, The side core portion has a first side core portion and a second side core portion. The end core portion comprises a first end core portion and a second end core portion. The low B core piece is E-shaped, having a part of the middle core portion, a first end core portion, a part of the first side core portion, and a part of the second side core portion. The high B core piece may be E-shaped, having the remainder of the middle core portion, the second end core portion, the remainder of the first side core portion, and the remainder of the second side core portion.

[0022] The configuration described in (6) above allows for the creation of a magnetic core that can ensure high inductance even at high currents. Even if the high-B core piece is a compacted powder molded body, it can be molded as long as the high-B core piece is E-shaped.

[0023] (7) In the reactor described in (5) above, The side core portion has a first side core portion and a second side core portion. The end core portion comprises a first end core portion and a second end core portion. Either the low-B core piece or the high-B core piece is E-shaped, having a part of the middle core portion, the first end core portion, the first side core portion, and the second side core portion. The remaining core piece from the low-B core piece and the high-B core piece may be T-shaped, having the remaining portion of the middle core and the second end core portion.

[0024] The configuration described in (7) above allows for the creation of a magnetic core that can ensure high inductance even at high currents. T-shaped core pieces are easier to mold than E-shaped core pieces. Even if the high-B core piece is a compacted powder molded body, molding is easy if the high-B core piece is T-shaped.

[0025] (8) In any of the reactors described in (1) to (4) above, The number of at least one of the low-B core pieces and the high-B core pieces may be two or more.

[0026] The configuration described in (8) above allows for fine-tuning of the magnetic properties of the magnetic core, as at least two of either the low-B core pieces or the high-B core pieces are present.

[0027] (9) In the reactor described in (8) above, The side core portion has a first side core portion and a second side core portion. The end core portion comprises a first end core portion and a second end core portion. The aforementioned middle core section is A first middle core portion coupled to the first end core portion, A second middle core portion is coupled to the second end core portion, It has a third middle core portion disposed between the first middle core portion and the second middle core portion, The aforementioned plurality of core pieces are The T-shaped first end core piece that constitutes the first middle core portion and the first end core portion, The T-shaped second end core piece that constitutes the second middle core portion and the second end core portion, The I-shaped middle core piece that constitutes the third middle core section, The I-shaped first side core piece that constitutes the first side core portion, The second side core portion comprises an I-shaped second side core piece, The first end core piece and the second end core piece are either the low-B core piece or the high-B core piece. The middle core piece, the first side core piece, and the second side core piece may be the remaining core piece from the low B core piece and the high B core piece.

[0028] The configuration described in (9) above allows for the creation of a magnetic core that can ensure high inductance even at high currents. T-shaped core pieces are easier to mold than E-shaped core pieces. Even if the high-B core piece is a compacted powder molded body, molding is easy if the high-B core piece is T-shaped.

[0029] (10) In the reactor described in (8) above, The side core portion has a first side core portion and a second side core portion. The end core portion comprises a first end core portion and a second end core portion. The aforementioned plurality of core pieces are The I-shaped first end core piece that constitutes the first end core portion, The I-shaped second end core piece that constitutes the second end core portion, The I-shaped middle core piece that constitutes the middle core portion, The I-shaped first side core piece that constitutes the first side core portion, The second side core portion comprises an I-shaped second side core piece, The first end core piece and the second end core piece are either the low-B core piece or the high-B core piece. The middle core piece, the first side core piece, and the second side core piece may be the remaining core piece from the low B core piece and the high B core piece.

[0030] The above configuration (10) can create a magnetic core that can secure high inductance even at high currents. The I-shaped core piece is easy to mold. If the high-B core piece is a compacted powder molded body, then if the high-B core piece is I-shaped, Easy to mold That is the case.

[0031] (11) In any of the reactors described in (1) to (10) above, The middle core portion may have a gap.

[0032] The configuration described in (11) above allows for adjustment of the inductance and suppression of magnetic saturation through the gap.

[0033] (12) In the reactor described in (11) above, The length of the gap portion may be 0.5 mm or more and 3 mm or less.

[0034] According to the configuration in (12) above, a predetermined inductance is easily obtained.

[0035] (13) The converters of this disclosure The reactor is provided as described in any one of (1) to (12) above.

[0036] The converter of this disclosure, having the reactor of this disclosure, operates stably even at high currents.

[0037] (14) The power converter of the present disclosure is The device is equipped with the converter described in (13) above.

[0038] The power conversion device of this disclosure, since it is equipped with a converter of this disclosure, operates stably even at high currents.

[0039] [Details of the embodiments of this disclosure] Specific examples of embodiments of the present disclosure will be described with reference to the drawings. Identical reference numerals in the drawings indicate the same or corresponding parts. However, the present invention is not limited to these examples and is intended to be included in the claims, with all modifications within the meaning and scope equivalent to the claims.

[0040] [Embodiment] <Reactor> A reactor 1 according to an embodiment will be described with reference to Figures 1 to 8. As shown in Figure 1, the reactor 1 comprises a coil 2 and a magnetic core 3. As shown in Figure 2, the shape of the magnetic core 3 is θ-shaped. The magnetic core 3 comprises a middle core portion 31, a side core portion 33, and an end core portion 35. As shown in Figure 3, the magnetic core 3 is composed of a plurality of core pieces 4. The plurality of core pieces 4 include low-B core pieces 4L and high-B core pieces 4H. Figure 1 is a perspective view of the reactor 1 viewed from diagonally above. Figure 2 is a plan view of the reactor 1 viewed from above. In Figure 2, the coil 2 is shown in cross-section. Figure 3 is a plan view of the magnetic core 3 viewed from above.

[0041] One of the features of the reactor 1 of this embodiment is that it satisfies the following requirements (a) and (b). (a) The low-B core piece 4L and the high-B core piece 4H are composed of materials with different saturation magnetic flux densities. (b) The ratio BS of the magnetic core 3 is 0.5 or more and 1.0 or less.

[0042] "Middle core," "side core," and "end core" refer to specific parts of the magnetic core. "Core piece" refers to a single component formed from the same material. "Low B core piece" and "high B core piece" are names for core pieces classified according to the saturation magnetic flux density of the constituent material. A single core piece may constitute part or all of a core piece, or a single core piece may constitute multiple core pieces. In the drawings, boundaries between core pieces are shown with solid lines, and boundaries between multiple core pieces within a single core piece are shown with dashed lines.

[0043] The configuration of reactor 1 will be described in detail below. In the following description, the X, Y, and Z directions in reactor 1 are defined as follows: The X direction is the direction along the axis of coil 2, from the first end 2a to the second end 2b. The line parallel to the X direction is defined as the X-axis. The Y direction is the direction perpendicular to the axis of coil 2, that is, perpendicular to the X direction, and is the direction in which the middle core section 31 and the side core section 33 are parallel. Specifically, it is the direction from the second side core section 332 to the first side core section 331. The line parallel to the Y direction is defined as the Y-axis. The Z direction is the direction perpendicular to both the X and Y directions, and is the direction from the bottom surface to the top surface of coil 2. The Z direction is perpendicular to the XY plane. The line parallel to the Z direction is defined as the Z-axis. The X, Y, and Z axes are perpendicular to each other. In the following description, "height" refers to the length along the Z direction.

[0044] ≪Coil≫ As shown in Figure 1, coil 2 is positioned in the middle core portion 31 of the magnetic core 3. Coil 2 is constructed by winding a wire in a spiral shape. The winding is, for example, a coated flat wire having a conductor wire and an insulating coating covering the conductor wire. The conductor wire is, for example, a flat wire made of copper. The insulating coating is, for example, made of enamel. Coil 2 in this example is an edgewise coil in which coated flat wire is wound in a spiral shape.

[0045] Coil 2 has a cylindrical shape. The shape of coil 2 may be polygonal or cylindrical. A polygonal shape means that the contour shape of the end face of coil 2 is polygonal. Polygonal shapes include, for example, quadrilaterals, hexagons, and octagons. A quadrilateral shape includes a rectangular shape. A rectangular shape also includes a square shape. For example, a quadrilateral is not limited to a geometric quadrilateral, but also includes quadrilaterals with modifications to the details, such as a shape in which at least one of the four corners is rounded. A cylindrical shape means that the contour shape of the end face of coil 2 is circular. A circular shape includes not only a perfect circle, but also an oval shape and an ellipse shape. In this example, the shape of coil 2 is a rectangular cylinder.

[0046] Coil 2 has a first end 2a and a second end 2b. Although not shown in Figure 1, the ends of the winding are drawn out from the first end 2a and the second end 2b, respectively. The ends of the winding are drawn out, for example, upwards in Figure 1, i.e., in the Z-axis direction. The ends of the winding are connected to a busbar (not shown). The busbar connects coil 2 to a power supply (not shown). The busbar is a long, thin, plate-shaped conductor made of metal.

[0047] Magnetic Core A coil 2 is arranged in the magnetic core 3. As shown in Figure 2, the magnetic core 3 in this example has a middle core portion 31, a side core portion 33, and an end core portion 35. The magnetic core 3 has a θ-shaped form in plan view.

[0048] A θ-shaped closed magnetic path is formed in the magnetic core 3. 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 section 31, through the end core section 35 and the side core section 33, and back to the middle core section 31.

[0049] (Middle core section) The middle core portion 31 is located inside the coil 2. There is one middle core portion 31. The middle core portion 31 extends along the X direction. The length Lm of the middle core portion 31 is the same as or greater than the length of the coil 2. The length Lm of the middle core portion 31 refers to the length along the direction in which the middle core portion 31 extends, i.e., the X direction. Both ends of the middle core portion 31 may protrude from both ends of the coil 2. These protruding parts are also part of the middle core portion 31. The shape of the middle core portion 31 generally corresponds to the inner shape of the coil 2. In this example, the shape of the middle core portion 31 is approximately a rectangular parallelepiped. In this example, the width Wm and height of the middle core portion 31 are constant in the direction along the length of the middle core portion 31, i.e., the X direction. The width Wm of the middle core portion 31 refers to the length along the Y direction.

[0050] The middle core portion 31 is positioned 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 first end of the middle core portion 31 is connected to the first end core portion 35a. The second end of the middle core portion 31 is connected to the second end core portion 35b. "Connected" means that the core portions are integrated so that they do not separate from each other. Connected core portions include cases where the core portions are integrally molded and cases where the core portions are joined together. When the core portions are integrally molded, there are no seams between the connected core portions. When the core portions are joined together, there are seams between the connected core portions. In the latter case, for example, the core portions may be bonded together, or the core portions may be integrated together by a resin mold. The resin mold is a series of molded members formed to cover at least a portion of the outer circumferential surface of the magnetic core 3.

[0051] The middle core section 31 in this example has a first middle core section 31a and a second middle core section 31b. The first middle core section 31a and the second middle core section 31b are arranged in series along the X-axis. The first middle core section 31a is connected to the first end core section 35a. The second middle core section 31b is connected to the second end core section 35b. The lengths of the first middle core section 31a and the second middle core section 31b can be set as appropriate. The lengths of the first middle core section 31a and the second middle core section 31b may be the same or different. In this example, the middle core section 31 is evenly divided into two parts, the first middle core section 31a and the second middle core section 31b, but the middle core section 31 does not have to be divided, or it may be divided into three or more parts.

[0052] In this example, the middle core portion 31 is made of a single material. That is, the first middle core portion 31a and the second middle core portion 31b are made of the same material. Unlike this example, the first middle core portion 31a and the second middle core portion 31b may be made of different materials.

[0053] In this example, the middle core portion 31 has a gap portion 31g. The gap portion 31g is located between the first middle core portion 31a and the second middle core portion 31b. Having a gap portion 31g in the middle core portion 31 allows for adjustment of the inductance of the reactor 1 and suppression of magnetic saturation. The gap portion 31g is located inside the coil 2. When the gap portion 31g is located inside the coil 2, the leakage flux from the gap portion 31g is reduced compared to when the gap portion 31g is exposed from the coil 2. 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. The gap portion 31g may be omitted. If there is no gap portion 31g, 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.

[0054] The length of the gap 31g is set appropriately so that a predetermined inductance can be obtained. For example, the length of the gap 31g is 0.5 mm or more and 3 mm or less. The length of the gap 31g refers to the length along the X direction. The length of the gap 31g may also be 1 mm or more and 2.5 mm or 1 mm or more and 2 mm or less. The smaller the length of the gap 31g, the easier it is to reduce losses due to leakage flux from the gap 31g. If the middle core 31 has a gap 31g, the length of the middle core 31 is the sum of the length of the first middle core 31a, the length of the second middle core 31b, and the length of the gap 31g.

[0055] (Side core section) The side core section 33 is located outside the coil 2. As shown in Figure 2, the side core section 33 is arranged in parallel with the middle core section 31, sandwiching the coil 2. The side core section 33 extends along the X direction. The side core section 33 is arranged roughly parallel to the middle core section 31. The length Ls of the side core section 33 is equal to the length Lm of the middle core section 31. The length Ls of the side core section 33 refers to the length along the direction in which the side core section 33 extends, i.e., the X direction. In this example, the shape of the side core section 33 is approximately a rectangular parallelepiped. In this example, the width Ws and height of the side core section 33 are constant in the direction along the length of the side core section 33, i.e., the X direction. The width Ws of the side core section 33 refers to the length along the Y direction.

[0056] The side core portion 33 is positioned between the first end core portion 35a and the second end core portion 35b. The first end of the side core portion 33 is connected to the first end core portion 35a. The second end of the side core portion 33 is connected to the second end core portion 35b.

[0057] There are two side core sections 33. Each side core section 33 has a first side core section 331 and a second side core section 332. The first side core section 331 and the second side core section 332 are arranged in parallel with a gap between them in the Y direction. The first side core section 331 and the second side core section 332 are arranged symmetrically with respect to the center of the middle core section 31.

[0058] In this example, the first side core section 331 and the second side core section 332 are made of the same material. Unlike this example, the first side core section 331 and the second side core section 332 may be made of different materials. Also, in this example, the shape and dimensions of the first side core section 331 and the second side core section 332 are the same. Here, dimensions refer to length, width, and height. Unlike this example, the shape and dimensions of the first side core section 331 and the second side core section 332 may be different. For example, the width Ws and / or height of the first side core section 331 and the second side core section 332 may differ.

[0059] (End core section) The end core portion 35 is located outside the coil 2. The end core portion 35 is positioned opposite both ends of the coil 2. The end core portion 35 extends along the Y direction. The end core portion 35 is positioned approximately perpendicular to the middle core portion 31 and the side core portion 33. In this example, the shape of the end core portion 35 is approximately a rectangular parallelepiped.

[0060] There are two end core sections 35. Each end core section 35 has a first end core section 35a and a second end core section 35b. The first end core section 35a and the second end core section 35b are arranged in parallel with a gap between them in the X direction. The inner surface of the first end core section 35a faces the first end 2a of the coil 2. The inner surface of the second end core section 35b faces the second end 2b of the coil 2. The first end of the middle core section 31, the first end of the first side core section 331, and the first end of the second side core section 332 are connected to the inner surface of the first end core section 35a. The second end of the middle core section 31, the second end of the first side core section 331, and the second end of the second side core section 332 are connected to the inner surface of the second end core section 35b.

[0061] The end core portion 35 only needs to have a length Le connecting the first side core portion 331 and the second side core portion 332. The length Le of the end core portion 35 refers to the length along the direction in which the end core portion 35 extends, i.e., the Y direction. In this example, the width We and height of the end core portion 35 are constant in the direction along the length of the end core portion 35, i.e., the Y direction. The width We of the end core portion 35 refers to the length along the X direction.

[0062] In this example, the first end core portion 35a and the second end core portion 35b are made of the same material. Unlike this example, the first end core portion 35a and the second end core portion 35b may be made of different materials. Also, in this example, the shape and dimensions of the first end core portion 35a and the second end core portion 35b are the same. Unlike this example, the shape and dimensions of the first end core portion 35a and the second end core portion 35b may be different. For example, the width We and / or height of the first end core portion 35a and the second end core portion 35b may differ.

[0063] The heights of the middle core section 31, the side core section 33, and the end core section 35 may be the same or different. The widths of the side core section 33 and the end core section 35 may be the same or different.

[0064] ≪Core Piece≫ As shown in Figure 3, the magnetic core 3 in this example is composed of multiple core pieces 4. Each core piece 4 is made of a molded body of soft magnetic material. The multiple core pieces 4 include low-B core pieces 4L and high-B core pieces 4H. In Figure 3, different hatching is applied to the low-B core pieces 4L and high-B core pieces 4H for clarity. The coil 2 is also shown in Figure 3. The configuration of the magnetic core 3 shown in Figure 3 is an example of the arrangement of the multiple core pieces 4. In this example, there are a total of six core pieces 4, two of which are high-B core pieces 4H and four of which are low-B core pieces 4L.

[0065] (Saturation magnetic flux density of the core piece) The low-B core piece 4L and the high-B core piece 4H are composed of materials with different saturation magnetic flux densities. The saturation magnetic flux density of the low-B core piece 4L is lower than that of the high-B core piece 4H. The saturation magnetic flux density of the high-B core piece 4H is, for example, 1.0T to 2.5T. The saturation magnetic flux density of the low-B core piece 4L is, for example, 0.5T to 1.7T. If the saturation magnetic flux densities of the high-B core piece 4H and the low-B core piece 4L are within the above ranges, the desired inductance is easily obtained. The saturation magnetic flux density of the high-B core piece 4H may further be 1.3T to 2.2T or 1.5T to 2.0T. The saturation magnetic flux density of the low-B core piece 4L may further be 0.7T to 1.5T or 0.9T to 1.4T. The saturation magnetic flux density can be determined by measuring the magnetic flux density when a magnetic field of 10,000 Oe (Oersted) is applied and the field is magnetically saturated. 10,000 Oe is approximately 800 kA / m.

[0066] (Materials for the core piece) The material of each core piece 4 is, for example, a compacted soft magnetic powder or a molded composite material. Because the magnetic core 3 is composed of multiple materials, it is easier to adjust the overall magnetic properties of the magnetic core to obtain a predetermined inductance compared to a magnetic core composed of a single material.

[0067] The compacted article is formed by compressing and molding raw material powder containing soft magnetic powder. Because the compacted article has a relatively high content of soft magnetic powder, it has high magnetic properties. Magnetic properties include, for example, relative permeability and saturation magnetic flux density. The relative permeability of the compacted article is, for example, 100 to 500. The saturation magnetic flux density of the compacted article is, for example, 1.0 T to 2.5 T. The compacted article may contain, for example, at least one of a binder resin and a molding aid. The content of soft magnetic powder in the compacted article is, for example, more than 80 volume% and 99.99 volume% or less, when the compacted article is considered to be 100 volume%. The content of soft magnetic powder in the compacted article may be further 85 volume% to 99 volume%.

[0068] A molded composite material is formed by dispersing soft magnetic powder in a resin. The molded composite material is produced by filling a mold with a raw material containing dispersed soft magnetic powder in unsolidified resin, and then solidifying the resin. The content of soft magnetic powder in the molded composite material can be easily adjusted. Therefore, the magnetic properties of the molded composite material are easily adjustable. The content of soft magnetic powder in the molded composite material is, for example, 30% to 80% by volume, when the molded composite material is considered to be 100% by volume. The content of soft magnetic powder in the composite material may be further 50% or more, or even 60% or more by volume.

[0069] Composite material molded articles have a lower soft magnetic powder content compared to powder compacted articles. Therefore, composite material molded articles have lower magnetic properties compared to powder compacted articles. The relative permeability of composite material molded articles is, for example, between 5 and 50. The saturation magnetic flux density of composite material molded articles is, for example, between 0.5T and 1.7T. Because composite material molded articles have a structure in which soft magnetic powder is dispersed in the resin, they have less iron loss compared to powder compacted articles.

[0070] The content of soft magnetic powder is considered equivalent to the area ratio of soft magnetic powder in the cross-section of the molded body constituting the core piece 4. The content of soft magnetic powder can be determined as follows: Observe the cross-section of the molded body with a scanning electron microscope (SEM) and acquire observation images. The SEM magnification should be, for example, between 200x and 500x. Acquire at least 10 observation images. The total area of ​​the observation images 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 soft magnetic particles. The image processing is, for example, binarization. The total area of ​​the soft magnetic particles is calculated in each observation image, and the area ratio of the soft magnetic powder in each observation image is determined. The average value of the area ratio in all observation images is considered to be the soft magnetic powder content.

[0071] 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 circumference of the 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, ferrite.

[0072] The resin used in the composite material may be a thermoplastic resin or a thermosetting resin. Examples of thermoplastic resins include polyphenylene sulfide resin, polytetrafluoroethylene resin, liquid crystal polymer, polyamide resin, polybutylene terephthalate resin, or acrylonitrile butadiene styrene resin. Examples of polyamide resins include nylon 6, nylon 66, or nylon 9T. Examples of thermosetting resins include unsaturated polyester resin, epoxy resin, urethane resin, or silicone resin.

[0073] In this example, the high-B core piece 4H is made of a compacted powder body, while the low-B core piece 4L is made of a composite material body. If the high-B core piece 4H is made of a compacted powder body, it is easy to adjust its saturation magnetic flux density to be between 1.0T and 2.5T. If the low-B core piece 4L is made of a composite material body, it is easy to adjust its saturation magnetic flux density to be between 0.5T and 1.7T.

[0074] (Arrangement configuration of core pieces) <First Arrangement Form> In this example, the magnetic core 3 is composed of a middle core section 31, a side core section 33, and an end core section 35, each made up of independent core pieces 4. The arrangement of the core pieces 4 shown in Figure 3 is called the first arrangement. The multiple core pieces 4 include a middle core piece 41, a first side core piece 431, a second side core piece 432, a first end core piece 45a, and a second end core piece 45b. "Middle core piece," "first side core piece," "second side core piece," "first end core piece," and "second end core piece" are names for core pieces classified according to the core section they constitute. The middle core piece 41 is an I-shaped core piece 4 that constitutes the middle core section 31. In this example, the middle core section 31 includes a first middle core piece 41a that constitutes the first middle core section 31a and a second middle core piece 41b that constitutes the second middle core section 31b. The first side core piece 431 is an I-shaped core piece 4 that constitutes the first side core section 331. The second side core piece 432 is an I-shaped core piece 4 that constitutes the second side core section 332. The first end core piece 45a is an I-shaped core piece 4 that constitutes the first end core section 35a. The second end core piece 45b is an I-shaped core piece 4 that constitutes the second end core section 35b.

[0075] As shown in Figure 3, the middle core portion 31 is composed of two core pieces 4, a first middle core piece 41a and a second middle core piece 41b, and a gap portion 31g. The first side core portion 331 and the second side core portion 332, and the first end core portion 35a and the second end core portion 35b are each composed of one core piece 4. The first side core portion 331 and the second side core portion 332 are each composed of the first side core piece 431 and the second side core piece 432. The first end core portion 35a and the second end core portion 35b are each composed of the first end core piece 45a and the second end core piece 45b. The first end core piece 45a and the second end core piece 45b are high-B core pieces 4H. In other words, the first end core portion 35a and the second end core portion 35b are composed of compacted molded bodies. The first middle core piece 41a and the second middle core piece 41b, and the first side core piece 431 and the second side core piece 432 are low-B core pieces 4L. In other words, the first middle core section 31a and the second middle core section 31b are made of a molded composite material. The first side core section 331 and the second side core section 332 are made of a molded composite material.

[0076] The high-B core piece 4H and the low-B core piece 4L may be interchanged. That is, the first end core piece 45a and the second end core piece 45b may be low-B core pieces 4L made of a molded composite material, and the first middle core piece 41a and the second middle core piece 41b, and the first side core piece 431 and the second side core piece 432 may be high-B core pieces 4H made of a compacted powder molded material.

[0077] In the magnetic core 3 shown in Figure 3, the number of low-B core pieces 4L and the number of high-B core pieces 4H are both two or more. Having at least two of either the low-B core pieces 4L or the high-B core pieces 4H makes it easier to finely adjust the magnetic properties of the entire magnetic core 3.

[0078] (Magnetic core ratio BS) The ratio BS of the magnetic core 3 is between 0.5 and 1.0. This ratio BS is the ratio of the sum of the product BSe (saturation magnetic flux density Be and cross-sectional area Se) in the end core 35 and the product BSs (saturation magnetic flux density Bs and cross-sectional area Ss) in the side core 33 to the product BSm (saturation magnetic flux density Bm and cross-sectional area Sm) in the middle core 31. By having a ratio BS between 0.5 and 1.0, magnetic saturation in the middle core can be delayed, improving inductance at high currents. Therefore, high inductance can be ensured even at high currents. The ratio BS may also be between 0.5 and 0.9, 0.6 and 0.9, or 0.6 and 0.8.

[0079] The ratio BS of magnetic core 3 can be calculated using the following formula. Ratio BS=[(product BSe)+(product BSs)] / (product BSm) Product BSm=Bm×Sm Product BSe=Be×Se Product BSs=Bs×Ss Product BSm refers to the product of the saturation magnetic flux density Bm and the cross-sectional area Sm in the middle core section 31. Product BSe refers to the product of the saturation magnetic flux density Be and the cross-sectional area Se in the end core section 35. Product BSs refers to the product of the saturation magnetic flux density Bs and the cross-sectional area Ss in the side core section 33.

[0080] The cross-sectional area of ​​each core refers to the area of ​​the cross-section perpendicular to the direction in which the magnetic flux flows in each core when a closed magnetic path is formed in the magnetic core 3. The direction in which the magnetic flux flows in each core coincides with the direction in which each core extends, that is, the direction along the length of each core.

[0081] The cross-sectional area Sm of the middle core portion 31 in this example is the area of ​​the cross section 31x perpendicular to the X direction, as shown in Figure 4. The shape of the cross section 31x of the middle core portion 31 in this example is rectangular. The cross-sectional area Sm of the middle core portion 31 is the product of the width Wm and height Hm of the middle core portion 31. The cross-sectional area Sm is constant in the X direction. The cross-sectional area Ss of the side core portion 33 in this example is the area of ​​the cross section 33x perpendicular to the X direction. The cross-sectional area Ss is the area of ​​the cross section 33x of one side core portion 33. The shape of the cross section 33x of the side core portion 33 in this example is rectangular. The cross-sectional area Ss of the side core portion 33 is the product of the width Ws and height Hs of the side core portion 33. The cross-sectional area Ss is constant in the X direction. The cross-sectional area Se of the end core portion 35 in this example is the area of ​​the cross section 35x perpendicular to the Y direction, as shown in Figure 5. The cross-sectional area Se is the area of ​​the cross-section 35x of one end core portion 35. In this example, the shape of the cross-section 35x of the end core portion 35 is rectangular. The cross-sectional area Se of the end core portion 35 is the product of the width We and height He of the end core portion 35. The cross-sectional area Se of the end core portion 35 is the cross-sectional area of ​​the portion corresponding to the area between the middle core portion 31 and the side core portion 33. The cross-sectional area Se is constant in the Y direction.

[0082] In this example, the height Hm of the middle core section 31, the height Hs of the side core section 33, and the height He of the end core section 35 are substantially equal. Also, the width Ws of the side core section 33 and the width We of the end core section 35 are substantially equal. Unlike this example, the height Hm of the middle core section 31, the height Hs of the side core section 33, and the height He of the end core section 35 may be different.

[0083] The saturation magnetic flux density of each core section is determined by the material of the core piece 4 that constitutes each core section. In this example, the saturation magnetic flux density Bm of the middle core section 31 and the saturation magnetic flux density Bs of the side core section 33 are the saturation magnetic flux densities of the low-B core piece 4L, which is made of a molded composite material, as shown in Figure 3. In this example, the saturation magnetic flux density Be of the end core section 35 is the saturation magnetic flux density of the high-B core piece 4H, which is made of a compacted powder molded body.

[0084] Unlike this example, for example, the first middle core section 31a and the second middle core section 31b in the middle core section 31 may be made of materials with different saturation magnetic flux densities. That is, either the first middle core piece 41a or the second middle core piece 41b may be a low-B core piece 4L. In this case, the product BSm of the middle core section 31 can be determined as follows: Determine the ratio of the first middle core section 31a and the second middle core section 31b, respectively, when the total volume of the first middle core section 31a and the second middle core section 31b is set to 1. In this example, the ratio of the first middle core section 31a corresponds to the ratio of the length of the first middle core section 31a to the length of the middle core section 31. The ratio of the second middle core section 31b corresponds to the ratio of the length of the second middle core section 31b to the length of the middle core section 31. However, here, the length of the middle core section 31 excludes the length of the gap section 31g. The product of the saturation magnetic flux density Bma and the cross-sectional area Sm in the first middle core section 31a is multiplied by the ratio of the first middle core section 31a to obtain the value, and this value is called the product BSma. The product of the saturation magnetic flux density Bmb and the cross-sectional area Sm in the second middle core section 31b is multiplied by the ratio of the second middle core section 31b to obtain the value, and this value is called the product BSmb. Then, the sum of the product BSma of the first middle core section 31a and the product BSmb of the second middle core section 31b is considered to be the product BSm of the middle core section 31.

[0085] In this example, the first side core portion 331 and the second side core portion 332 are made of the same material, and their shapes and dimensions are also the same. In other words, the first side core piece 431 and the second side core piece 432 have the same configuration. In this case, the product BSs of the side core portions 33 can be calculated from the saturation magnetic flux density Bs and cross-sectional area Ss of one of the side core portions 33, which is either the first side core portion 331 or the second side core portion 332.

[0086] Unlike this example, for example, the first side core portion 331 and the second side core portion 332 may be made of materials with different saturation magnetic flux densities. That is, either the first side core piece 431 or the second side core piece 432 may be a high-B core piece 4H. In this case, the product BSs of the side core portion 33 is determined as follows: The product BSs1 of the saturation magnetic flux density Bs1 and the cross-sectional area Sm in the first side core portion 331 is determined, and the product BSs2 of the saturation magnetic flux density Bs2 and the cross-sectional area Sm in the second side core portion 332 is determined. Then, the average value of the product BSs1 of the first side core portion 331 and the product BSs2 of the second side core portion 332 is considered as the product BSs of the side core portion 33.

[0087] Furthermore, unlike this example, if, for example, the width Ws of the first side core section 331 and the width Ws of the second side core section 332 are different, the product BSs of the side core section 33 can be determined as follows: The product BSs1 of the saturation magnetic flux density Bs and the cross-sectional area Ss1 in the first side core section 331 and the product BSs2 of the saturation magnetic flux density Bs and the cross-sectional area Ss2 in the second side core section 332 are determined, respectively. Then, the average value of the product BSs1 of the first side core section 331 and the product BSs2 of the second side core section 332 is considered as the product BSs of the side core section 33.

[0088] In this example, the first end core portion 35a and the second end core portion 35b are made of the same material, and their shapes and dimensions are also the same. In other words, the first end core piece 45a and the second end core piece 45b have the same configuration. In this case, the product BSe of the end core portions 35 can be calculated from the saturation magnetic flux density Be and cross-sectional area Se of one of the end core portions 35, which is either the first end core portion 35a or the second end core portion 35b.

[0089] Unlike this example, for example, the first end core portion 35a and the second end core portion 35b may be made of materials with different saturation magnetic flux densities. That is, either the first end core piece 45a or the second end core piece 45b may be a low-B core piece 4L. In this case, the product BSe of the end core portion 35 is determined as follows: The product BSe of the saturation magnetic flux density Bea and the cross-sectional area Se in the first end core portion 35a is determined, and the product BSe of the saturation magnetic flux density Beb and the cross-sectional area Se in the second end core portion 35b is determined. Then, the average value of the product BSe of the first end core portion 35a and the product BSe of the second end core portion 35b is considered as the product BSe of the end core portion 35.

[0090] Furthermore, unlike this example, if, for example, the width We of the first end core portion 35a and the width We of the second end core portion 35b are different, the product BSe of the end core portion 35 can be determined as follows: The product BSe of the saturation magnetic flux density Be and cross-sectional area Sea in the first end core portion 35a is determined, and the product BSe of the saturation magnetic flux density Be and cross-sectional area Seb in the second end core portion 35b is determined. Then, the average value of the product BSe of the first end core portion 35a and the product BSe of the second end core portion 35b is considered as the product BSe of the end core portion 35.

[0091] [Differentiation] The arrangement of the core pieces 4 that make up the magnetic core 3 can be changed as appropriate. A modified example of the magnetic core 3 will be described with reference to Figures 6 to 8. The following explanation will focus on the differences from the configuration of the magnetic core 3 shown in Figure 3. In Figures 6 to 8, the boundaries between core pieces 4 are shown with solid lines, and the boundaries of each core section within a single core piece 4 are shown with dashed lines. The coil 2 is also shown in Figures 6 to 8.

[0092] (Variation 1) <Second Arrangement> The configuration of the magnetic core 3 shown in Figure 6 represents a second arrangement. In the magnetic core 3 shown in Figure 6, the middle core portion 31 has a first middle core portion 31a, a second middle core portion 31b, and a third middle core portion 31c. The third middle core portion 31c is positioned between the first middle core portion 31a and the second middle core portion 31b. The first middle core portion 31a, the third middle core portion 31c, and the second middle core portion 31b are arranged in series along the X-axis. The lengths of the first middle core portion 31a, the second middle core portion 31b, and the third middle core portion 31c can be set as appropriate. In the example shown in Figure 6, a gap portion 31g is positioned between the third middle core portion 31c and the second middle core portion 31b. The first middle core portion 31a and the third middle core portion 31c are in contact with each other. Unlike the example shown in Figure 6, the gap portion 31g may be positioned between the third middle core portion 31c and the first middle core portion 31a. Furthermore, gaps 31g may be provided both between the third middle core portion 31c and the first middle core portion 31a, and between the third middle core portion 31c and the second middle core portion 31b. The gaps 31g are also optional.

[0093] In the example shown in Figure 6, the multiple core pieces 4 include a middle core piece 41, a first side core piece 431, a second side core piece 432, a first end core piece 45a, and a second end core piece 45b. The first end core piece 45a is a T-shaped core piece 4 that constitutes the first middle core portion 31a and the first end core portion 35a. The second end core piece 45b is a T-shaped core piece 4 that constitutes the second middle core portion 31b and the second end core portion 35b. The middle core piece 41 is an I-shaped core piece 4 that constitutes the third middle core portion 31c. The first side core piece 431 is an I-shaped core piece 4 that constitutes the first side core portion 331. The second side core piece 432 is an I-shaped core piece 4 that constitutes the second side core portion 332.

[0094] As shown in Figure 6, the middle core section 31 is composed of a part of the first end core piece 45a, a part of the second end core piece 45b, the middle core piece 41, and the gap section 31g. The first end core piece 45a and the second end core piece 45b are high-B core pieces 4H. In other words, the first middle core section 31a and the first end core section 35a are composed of a integrally molded compacted body. The second middle core section 31b and the second end core section 35b are composed of a integrally molded compacted body. The middle core piece 41, the first side core piece 431, and the second side core piece 432 are low-B core pieces 4L. In other words, the third middle core section 31c is composed of a composite material molded body. The third middle core section 31c is composed of a different material from the first middle core section 31a and the second middle core section 31b. The first side core section 331 and the second side core section 332 are composed of a composite material molded body.

[0095] The high-B core piece 4H and the low-B core piece 4L may be interchanged. That is, the first end core piece 45a and the second end core piece 45b may be low-B core pieces 4L made of a molded composite material, and the middle core piece 41, the first side core piece 431, and the second side core piece 432 may be high-B core pieces 4H made of a compacted powder molded material.

[0096] The magnetic core 3 shown in Figure 6, like the magnetic core 3 shown in Figure 3, has at least two low-B core pieces 4L and at least two high-B core pieces 4H. Having at least two of either the low-B core pieces 4L or the high-B core pieces 4H makes it easier to finely adjust the overall magnetic properties of the magnetic core 3.

[0097] (Modification 2) <Third Arrangement> The configuration of the magnetic core 3 shown in Figure 7 represents a third arrangement. The magnetic core 3 shown in Figure 7 is composed of an E-shaped low-B core piece 4L and an E-shaped high-B core piece 4H. In the magnetic core 3 shown in Figure 7, the first side core portion 331 and the second side core portion 332 are each divided into two parts, having first parts 331a, 332a and second parts 331b, 332b, respectively. In the first side core portion 331, the first part 331a and the second part 331b are arranged in series along the X-axis. In the second side core portion 332, the first part 332a and the second part 332b are arranged in series along the X-axis. The first parts 331a, 332a are coupled to the first end core portion 35a. The second parts 331b, 332b are coupled to the second end core portion 35b. The lengths of the first parts 331a, 332a and the second parts 331b, 332b can be set as appropriate. In the example shown in Figure 7, the first parts 331a, 332a and the second parts 331b, 332b are in contact with each other. Unlike the example shown in Figure 7, there may be a gap between the first parts 331a, 332a and the second parts 331b, 332b.

[0098] In the example shown in Figure 7, the low-B core piece 4L is an E-shaped core piece 4 having a first middle core portion 31a, a first end core portion 35a, a first portion 331a of the first side core portion 331, and a first portion 332a of the second side core portion 332. In other words, the first middle core portion 31a, the first end core portion 35a, the first portion 331a of the first side core portion 331, and the first portion 332a of the second side core portion 332 are made of a molded body of a composite material that is integrally molded. The high-B core piece 4H is an E-shaped core piece 4 having a second middle core portion 31b, a second end core portion 35b, a second portion 331b of the first side core portion 331, and a second portion 332b of the second side core portion 332. In other words, the second middle core portion 31b, the second end core portion 35b, the second part 331b of the first side core portion 331, and the second part 332b of the second side core portion 332 are all made from a single molded compacted body. In the example shown in Figure 7, the first middle core portion 31a corresponds to a part of the middle core portion 31, and the second middle core portion 31b corresponds to the remainder of the middle core portion 31. The first part 331a of the first side core portion 331 corresponds to a part of the first side core portion 331, and the second part 331b corresponds to the remainder of the first side core portion 331. The first part 332a of the second side core portion 332 corresponds to a part of the second side core portion 332, and the second part 332b corresponds to the remainder of the second side core portion 332.

[0099] When the first parts 331a, 332a and the second parts 331b, 332b are made of materials with different saturation magnetic flux densities, the product BSs of the side core parts 33 is determined as follows: The product BSs1 of the saturation magnetic flux density Bs1 and the cross-sectional area Sm in the first side core part 331 is determined, and the product BSs2 of the saturation magnetic flux density Bs2 and the cross-sectional area Sm in the second side core part 332 is determined. The product BSs1 of the first side core part 331 is determined as follows. The ratios of the first part 331a and the second part 331b are determined when the total volume of the first part 331a and the second part 331b is set to 1. In the example shown in Figure 7, the ratio of the first part 331a corresponds to the ratio of the length of the first part 331a to the length of the first side core part 331. The ratio of the second part 331b corresponds to the ratio of the length of the second part 331b to the length of the first side core part 331. The product of the saturation magnetic flux density and the cross-sectional area in the first part 331a is multiplied by the ratio of the first part 331a, and this value is taken as the product BSs1a. The product of the saturation magnetic flux density and the cross-sectional area in the second part 331b is multiplied by the ratio of the second part 331b, and this value is taken as the product BSs1b. Then, the sum of the product BSs1a of the first part 331a and the product BSs2b of the second part 331b is considered as the product BSs1 of the first side core part 331. The product BSs2 of the second side core section 332 is obtained in the same manner as the product BSs1 of the first side core section 331. Then, the average value of the product BSs1 of the first side core section 331 and the product BSs2 of the second side core section 332 is considered to be the product BSs of the side core section 33.

[0100] (Variation 3) <Fourth configuration> The configuration of the magnetic core 3 shown in Figure 8 represents the fourth arrangement. The magnetic core 3 shown in Figure 8 is composed of an E-shaped low-B core piece 4L and a T-shaped high-B core piece 4H.

[0101] In the example shown in Figure 8, the low-B core piece 4L is an E-shaped core piece 4 having a first middle core portion 31a, a first end core portion 35a, a first side core portion 331, and a second side core portion 332. That is, 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 made of a molded composite material formed integrally. The high-B core piece 4H is a T-shaped core piece 4 having a second middle core portion 31b and a second end core portion 35b. That is, the second middle core portion 31b and the second end core portion 35b are made of a molded compacted powder material formed integrally. In the example shown in Figure 8, the first middle core portion 31a corresponds to a part of the middle core portion 31, and the second middle core portion 31b corresponds to the remainder of the middle core portion 31.

[0102] The shapes of the high-B core piece 4H and the low-B core piece 4L may be swapped. That is, the high-B core piece 4H may be an E-shaped core piece 4 having a first middle core portion 31a, a first end core portion 35a, a first side core portion 331, and a second side core portion 332, and the low-B core piece 4L may be a T-shaped core piece 4 having a second middle core portion 31b and a second end core portion 35b.

[0103] In the magnetic core 3 shown in Figures 7 and 8, there are two core pieces 4. Since there is one low-B core piece 4L and one high-B core piece 4H, the number of core pieces 4 is small, resulting in good manufacturability of the magnetic core 3.

[0104] <Converters / Power Converters> The reactor 1 of this embodiment can be used for applications that satisfy the following energizing conditions. These conditions include, for example, a maximum DC current of approximately 100A to 1000A, an average voltage of approximately 100V to 1000V, and an operating frequency of approximately 5kHz to 100kHz. The reactor 1 of this embodiment can typically be used as a component of a converter mounted in vehicles such as electric vehicles and hybrid vehicles, and as a component of a power conversion device equipped with this converter.

[0105] As shown in Figure 9, the vehicle 1200, such as a hybrid vehicle or electric vehicle, 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 driving. The motor 1220 is typically a three-phase AC motor. The motor 1220 drives the wheels 1250 during driving and functions as a generator during regeneration. In the case of a hybrid vehicle, the vehicle 1200 is equipped with an engine 1300 in addition to the motor 1220. In Figure 9, an inlet is shown as the charging point of the vehicle 1200, but it can also be configured with a plug.

[0106] The power converter 1100 includes a converter 1110 connected to the main battery 1210 and an inverter 1120 connected to the converter 1110 that performs mutual conversion between DC and AC. In this example, the converter 1110 boosts the input voltage of the main battery 1210, which is approximately 200V to 300V, to approximately 400V to 700V when the vehicle 1200 is running, 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, thereby charging the main battery 1210. The input voltage is a DC voltage. When the vehicle 1200 is running, the inverter 1120 converts the DC voltage boosted by the converter 1110 into a predetermined AC voltage and supplies power to the motor 1220. During regeneration, it converts the AC output from the motor 1220 into DC voltage and outputs it to the converter 1110.

[0107] As shown in Figure 10, 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, and performs input voltage conversion by repeatedly switching ON / OFF. Input voltage conversion in this case refers to step-up or step-down conversion. 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 that tries to oppose 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 the embodiment.

[0108] Vehicle 1200 includes, in addition to converter 1110, a power supply device converter 1150 connected to the main battery 1210, and an auxiliary power converter 1160 connected to the main battery 1210 and a sub-battery 1230 which serves as a power source for auxiliary equipment 1240, and which converts the high voltage of the main battery 1210 to low voltage. Converter 1110 typically performs DC-DC conversion, while the power supply device converter 1150 and the auxiliary power converter 1160 perform AC-DC conversion. Some power supply device converters 1150 also perform DC-DC conversion. The reactors of the power supply device converter 1150 and the auxiliary power converter 1160 have the same configuration as reactor 1 in the embodiment, and reactors with appropriately changed size or shape can be used. Furthermore, reactor 1 in the embodiment can also be used in converters that perform input power conversion, such as converters that only perform voltage boosting or converters that only perform voltage bucking.

[0109] [Test Example 1] The inductance and loss were evaluated for a reactor with a configuration similar to reactor 1 in the embodiment.

[0110] In Test Example 1, a magnetic core 3 with the configuration shown in Figure 3 was used. The first middle core piece 41a and the second middle core piece 41b constituting the middle core portion 31 are low-B core pieces 4L made of a molded composite material. The first side core piece 431 and the second side core piece 432 constituting the side core portion 33 teeth The first end core piece 45a and the second end core piece 45b constituting the end core portion 35 are high B core pieces 4H made of compacted powder.

[0111] In Test Example 1, reactor models No. 1-0 to No. 1-5, shown in Table 1, were designed. Models No. 1-0 to No. 1-5 are designed with magnetic cores such that the ratio BS is 1.2 to 0.4. The magnetic core of No. 1-0, designed to have a ratio BS of 1.2, is used as the reference. The configuration of the reference magnetic core is shown below.

[0112] (Dimensions of the magnetic core) • Magnetic core length L: 77mm • Magnetic core width W: 82mm • Magnetic core height H: 30mm Length L is the dimension in the X direction, as shown in Figure 1. Width W is the dimension in the Y direction. Height H is the dimension in the Z direction.

[0113] (Dimensions of each core section) • Middle core length Lm: 47mm • Width of the middle core section: 30mm Gap length: 1.5mm • Side core length Ls: 47mm • Side core width Ws: 15mm • End core length Le: 82mm • End core width We: 15mm Each core section has a height of 30mm.

[0114] (Materials of the core pieces that make up each core section) • Middle core section: Molded body of composite material • Side core section: Molded body of composite material • End core section: Compacted powder body The saturation magnetic flux density B of a compacted powder body is 1.7T. The saturation magnetic flux density B of a composite material body is 1.2T.

[0115] Models No. 1-1 to No. 1-5 are models in which the ratio BS of the magnetic core has been adjusted by reducing the width of the side core and end core sections, respectively, compared to the standard magnetic core No. 1-0. The length and width of the magnetic cores No. 1-0 to No. 1-5, as well as the width and cross-sectional area of ​​each core section, are shown in Table 1. The product of the saturation magnetic flux density and cross-sectional area in each core section is also shown in Table 1.

[0116] [Table 1]

[0117] We performed inductance and loss analyses for reactor models No. 1-0 through No. 1-5. For the inductance and loss analyses, we used JMAG-Designer 22.0, a commercially available electromagnetic field analysis software manufactured by JSOL Corporation, and performed magnetic field transient response analysis.

[0118] (Analysis of inductance) The inductance was analyzed when currents of 250A and 300A were passed through the coil. The maximum inductance was determined from the flux linkage of the coil at current values ​​of 250A and 300A. Table 2 shows the inductances for 250A and 300A for each model. The inductances shown in Table 2 are expressed as a ratio with the inductance of No. 1-0 as the reference (100%). An inductance of 99% or more is considered equivalent to or better than No. 1-0.

[0119] (Analysis of losses) The losses were analyzed when a DC current of 0A, input voltage of 300V, output voltage of 600V, and frequency of 20kHz were applied to a coil. These losses include iron losses in the magnetic core and losses in the coil. The losses for each model are shown in Table 2. The losses are shown as a percentage with the coil loss of No. 1-0 as the baseline (100%).

[0120] [Table 2]

[0121] As shown in Table 2, models No. 1-1 to No. 1-4 show improved inductance at 250A and 300A compared to No. 1-0. In other words, models with magnetic cores designed so that the ratio BS is between 0.5 and 1.0 exhibit high inductance at high currents. In particular, models No. 1-2 and No. 1-3 have higher inductance at 250A and 300A than No. 1-1. Furthermore, models No. 1-1 to No. 1-4 have lower losses compared to No. 1-0. In addition, as shown in Table 1, models No. 1-1 to No. 1-4 have smaller magnetic core length and width, and smaller magnetic core size compared to No. 1-0.

[0122] [Test Example 2] In Test Example 2, in the magnetic core 3 with the configuration shown in Figure 3, the high-B core piece 4H and the low-B core piece 4L of They were swapped. The first middle core piece 41a and the second middle core piece 41b that constitute the middle core section 31 are high B core pieces 4H made of compacted powder. The first side core piece 431 and the second side core piece 432 that constitute the side core section 33 teeth The first end core piece 45a and the second end core piece 45b that constitute the end core portion 35 are low B core pieces 4L that are made from molded composite materials.

[0123] In Test Example 2, we designed reactor models No. 2-0 to No. 2-5, as shown in Table 3. Models No. 2-0 to No. 2-5 are designed with magnetic cores such that the ratio BS is 1.2 to 0.4. The magnetic core of No. 2-0, designed to have a ratio BS of 1.2, is used as the reference. The configuration of the reference magnetic core is shown below.

[0124] (Dimensions of the magnetic core) • Magnetic core length L: 89mm • Magnetic core width W: 94mm • Magnetic core height H: 30mm

[0125] (Dimensions of each core section) • Middle core length Lm: 47mm • Width of the middle core section: 30mm Gap length: 1.5mm • Side core length Ls: 47mm • Side core width Ws: 21mm • End core length Le: 94mm • End core width We: 21mm Each core section has a height of 30mm.

[0126] (Materials of the core pieces that make up each core section) • Middle core section: Compacted powder body • Side core section: Compacted powder body • End core section: Molded body of composite material The saturation magnetic flux density B of a compacted powder body is 1.7T. The saturation magnetic flux density B of a composite material body is 1.2T.

[0127] Models No. 2-1 to No. 2-5 are models in which the ratio BS of the magnetic core has been adjusted by reducing the width of the side core and end core sections, respectively, compared to the reference magnetic core No. 2-0. The length and width of the magnetic cores No. 2-0 to No. 2-5, as well as the width and cross-sectional area of ​​each core section, are shown in Table 3. The product of the saturation magnetic flux density and cross-sectional area in each core section is also shown in Table 3.

[0128] [Table 3]

[0129] We analyzed the inductance and losses of reactor models No. 2-0 through No. 2-5. The inductance and losses for each model were determined in the same manner as in Test Example 1. The results are shown in Table 4.

[0130] [Table 4]

[0131] As shown in Table 4, the inductance at 250A for models No. 2-1 to No. 2-4 is over 99%, which is equivalent to or better than No. 2-0. The inductance at 300A for models No. 2-1 to No. 2-4 is improved compared to No. 2-0. In other words, models with magnetic cores designed so that the ratio BS is between 0.5 and 1.0 exhibit high inductance at high currents. In particular, models No. 2-1 to No. 2-3 have higher inductance at 250A and 300A than No. 2-0. Furthermore, models No. 2-1 to No. 2-4 have lower losses compared to No. 2-0. In addition, as shown in Table 3, models No. 2-1 to No. 2-4 have smaller magnetic core lengths and widths, and smaller magnetic core sizes compared to No. 2-0. [Explanation of Symbols]

[0132] 1 Reactor 2 coils 2a first end, 2b second end 3 Magnetic core 31 Middle Core Section 31a First middle core section, 31b Second middle core section, 31c Third middle core section 31g gap 31x cross section 33 Side core section 331 First side core section, 332 Second side core section 331a,332a first part, 331b,332b second part 33x cross section 35 End core section 35a First end core section, 35b Second end core section 35x cross section 4 core pieces 4H High B core pieces, 4L Low B core pieces 41 Middle Core Pieces 41a First middle core piece, 41b Second middle core piece 431 First side core piece, 432 Second side core piece 45a First end core piece, 45b Second end core piece 1100 Power Converter, 1110 Converter 1111 Switching element, 1112 Drive circuit 1115 Reactor, 1120 Inverter 1150 Converter for power supply equipment, 1160 Converter for auxiliary power supply equipment 1200 vehicles 1210 main battery, 1220 motor 1230 Sub-battery, 1240 Auxiliary equipment, 1250 Wheels, 1300 Engine L Length, W Width, H Height Lm, Ls, Le Length Wm, Ws, We width Hm, Hs, He Height

Claims

1. It comprises a coil and a magnetic core composed of multiple core pieces, The shape of the magnetic core is θ-shaped, The magnetic core is The middle core portion is located inside the coil, A side core portion is arranged in parallel with the middle core portion so as to sandwich the coil, The coil comprises end core portions arranged to face both ends of the coil, The plurality of core pieces include low-B core pieces and high-B core pieces. The low-B core piece and the high-B core piece are made of materials with different saturation magnetic flux densities. The saturation magnetic flux density of the low-B core piece is lower than that of the high-B core piece. The ratio BS of the magnetic core is 0.5 or more and 1.0 or less. The ratio BS is the ratio of the sum of the product BSe (saturation magnetic flux density Be and cross-sectional area Se) in the end core and the product BSs (saturation magnetic flux density Bs and cross-sectional area Ss) in the side core to the product BSm (saturation magnetic flux density Bm and cross-sectional area Sm) in the middle core. Reactor.

2. The saturation magnetic flux density of the aforementioned high-B core piece is 1.0 T or more and 2.5 T or less. The reactor according to claim 1, wherein the saturation magnetic flux density of the low-B core piece is 0.5 T or more and 1.7 T or less.

3. The reactor according to claim 1 or claim 2, wherein the high-B core piece is composed of a compacted molded body of soft magnetic powder.

4. The reactor according to claim 1 or claim 2, wherein the low-B core piece is composed of a molded body of a composite material in which soft magnetic powder is dispersed in a resin.

5. The number of the aforementioned core pieces is two. The reactor according to claim 1 or claim 2, wherein the number of low-B core pieces and the number of high-B core pieces are each one.

6. The side core portion has a first side core portion and a second side core portion. The end core portion comprises a first end core portion and a second end core portion. The low B core piece is E-shaped, having a part of the middle core portion, a first end core portion, a part of the first side core portion, and a part of the second side core portion. The reactor according to claim 5, wherein the high B core piece is E-shaped, having the remainder of the middle core portion, the second end core portion, the remainder of the first side core portion, and the remainder of the second side core portion.

7. The side core portion has a first side core portion and a second side core portion. The end core portion comprises a first end core portion and a second end core portion. Either the low-B core piece or the high-B core piece is E-shaped, having a part of the middle core portion, the first end core portion, the first side core portion, and the second side core portion. The reactor according to claim 5, wherein the remaining core piece of the low B core piece and the high B core piece is T-shaped, having the remainder of the middle core portion and the second end core portion.

8. The reactor according to claim 1 or claim 2, wherein the number of at least one of the low-B core pieces and the high-B core pieces is two or more.

9. The side core portion has a first side core portion and a second side core portion. The end core portion comprises a first end core portion and a second end core portion. The aforementioned middle core section is A first middle core portion coupled to the first end core portion, A second middle core portion is coupled to the second end core portion, It has a third middle core portion disposed between the first middle core portion and the second middle core portion, The aforementioned plurality of core pieces are The T-shaped first end core piece that constitutes the first middle core portion and the first end core portion, The T-shaped second end core piece that constitutes the second middle core portion and the second end core portion, The I-shaped middle core piece that constitutes the third middle core portion, The I-shaped first side core piece that constitutes the first side core portion, The second side core portion comprises an I-shaped second side core piece, The first end core piece and the second end core piece are either the low-B core piece or the high-B core piece. The reactor according to claim 8, wherein the middle core piece, the first side core piece, and the second side core piece are the remaining core pieces from the low B core piece and the high B core piece.

10. The side core portion has a first side core portion and a second side core portion. The end core portion comprises a first end core portion and a second end core portion. The aforementioned plurality of core pieces are The I-shaped first end core piece that constitutes the first end core portion, The I-shaped second end core piece that constitutes the second end core portion, The I-shaped middle core piece that constitutes the middle core portion, The I-shaped first side core piece that constitutes the first side core portion, The second side core portion comprises an I-shaped second side core piece, The first end core piece and the second end core piece are either the low B core piece or the high B core piece. The reactor according to claim 8, wherein the middle core piece, the first side core piece, and the second side core piece are the remaining core pieces from the low B core piece and the high B core piece.

11. The reactor according to claim 1 or claim 2, wherein the middle core portion has a gap portion.

12. The reactor according to claim 11, wherein the length of the gap portion is 0.5 mm or more and 3 mm or less.

13. A reactor comprising the reactor according to claim 1 or claim 2, converter.

14. A converter according to claim 13, Power converter.

Images