JP7345249B2 - reactor - Google Patents

Description

The present invention relates to the structure of a core included in a reactor.

Conventionally, in order to maintain the overall shape of the core well, a configuration in which a through hole is provided in the core instead of a gap is known. Patent Document 1 discloses a reactor having this type of core.

The reactor of Patent Document 1 has a coil and a core, and a plurality of through holes having mutually different opening cross-sectional shapes to form a gap are provided in a region of the core around which the coil is wound. It becomes.

JP2006-351920A

However, in the configuration of Patent Document 1, since a plurality of through holes are provided, a plurality of bridge portions are formed between the through holes, compared to a case where one through hole is provided. As a result, the total amount of magnetic flux passing through the bridge portion increases, resulting in an increase in iron loss occurring in the core.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a reactor that can alleviate concentration of magnetic flux at the bridge portion and reduce iron loss occurring in the core.

The problem to be solved by the present invention is as described above, and next, the means for solving this problem and the effects thereof will be explained.

According to one aspect of the present invention, a reactor having the following configuration is provided. That is, this reactor includes a core and a coil. The core is made of a magnetic material. The coil is wound around the core. The core has an elongated penetrating portion that penetrates the core. When viewed in the penetrating direction in which the penetrating portion passes through the core, the opening contour of the penetrating portion is closed. The shape of the penetration part when viewed in the penetration direction is an elongated shape, and at least one end in the longitudinal direction has a width wider than the width of the middle part in the longitudinal direction. The penetrating portion is formed to penetrate the core in an axial direction of the core. A plurality of the penetrating portions are formed and arranged at equal intervals in the circumferential direction of the core. The intermediate portion of the penetrating portion has a constant width in the transverse direction, which is a direction perpendicular to the penetrating direction and the longitudinal direction.

Thereby, the inductance (performance) of the reactor can be adjusted well without cutting the core, and magnetic flux saturation of the core can be avoided. In addition, by widening the width of the longitudinal end of the penetration part, concentration of magnetic flux near the end can be alleviated, and iron loss occurring in the core and heat generation amount in the core can be reduced. . Furthermore, since the core is not completely divided, a certain degree of mechanical strength can be ensured. Therefore, the shape of the core can be maintained well, and handling such as transportation is easy. Furthermore, since the core is not completely separated, the hum (noise) generated from the core can be reduced. A cylindrical reactor with good performance can be provided. The shape of the penetrating part is simplified, and the inductance of the reactor can be easily adjusted.

According to the present invention, it is possible to provide a reactor that can alleviate concentration of magnetic flux at the bridge portion and reduce iron loss occurring in the core.

FIG. 1 is a perspective view showing the overall configuration of a reactor according to an embodiment of the present invention. (a) A schematic diagram showing the configuration of a gapped core. (b) A perspective view showing the configuration of a core with a gap. FIG. 3 is a cross-sectional perspective view showing the configuration of the core. FIG. 3 is a partial plan view showing a slit portion. (a) A schematic diagram showing the flow of magnetic flux in the vicinity of a simple-shaped slit section. (b) A schematic diagram showing the flow of magnetic flux near the slit portion of this embodiment. FIG. 7 is a plan view showing a modification of the slit portion. FIG. 7 is a plan view showing a modification of the slit portion.

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing the overall configuration of a reactor 100 according to an embodiment of the present invention. FIG. 2 is a diagram illustrating a gapped core as a comparative example. FIG. 3 is a cross-sectional perspective view showing the configuration of the core 1. As shown in FIG. FIG. 4 is a partial plan view showing the slit portion 10. As shown in FIG.

The reactor 100 shown in FIG. 1 is connected to a power conversion device (for example, an inverter, a DC/DC converter, etc.). The reactor 100 is used, for example, to suppress current pulsations (ripples) generated by switching of an unillustrated semiconductor device included in a power converter.

As shown in FIG. 1, the reactor 100 mainly includes a core 1 made of a magnetic material and a coil 2 wound around the core 1. The coil 2 is composed of, for example, a wire wound into a coil.

As shown in FIG. 1, the core 1 is a winding axis of the coil 2, and is disposed to penetrate inside the coil 2. As shown in FIGS. 1 and 3, the core 1 is formed into a cylindrical shape with both axial ends open. The core 1 is constructed by, for example, laminating annular silicon steel plates in the axial direction by a known method.

Conventionally, it has been known to adjust the inductance of the reactor 100x and prevent magnetic flux saturation of the core 1x by forming a gap (air gap) 20 in the core 1x of the reactor 100x used in a high-voltage power conversion device. ing. This gap 20, as shown in FIG. 2, is a gap formed by cutting the core 1x. The gap 20 is formed to completely divide the loop-shaped core 1x.

For example, insulating paper or the like is provided to fill the gap 20. Thereby, the shape of the gap 20 (and thus the core 1x) can be maintained.

ただし、μ₀は、真空の透磁率である。μ_sは、コア１ｘの材料の比透磁率である。Ｓは、コア１ｘの断面積である。Ｎは、コイル２の巻回数である。ｇは、磁束が流れる磁路におけるギャップ２０の長さである。ｌは、磁束が流れる磁路の長さである。Ｌ_gは、コア１ｘのうちギャップ２０の部分のみにおけるインダクタンスである。Ｌ_cは、コア１ｘのうち材料の部分のみにおけるインダクタンスである。 Here, adjustment of the inductance of the reactor 100 by the gap 20 will be briefly explained using the following equations (1), (2), and (3).

However, μ ₀ is the magnetic permeability of vacuum. μ _s is the relative magnetic permeability of the material of the core 1x. S is the cross-sectional area of core 1x. N is the number of turns of the coil 2. g is the length of the gap 20 in the magnetic path through which the magnetic flux flows. l is the length of the magnetic path through which the magnetic flux flows. L _g is the inductance only in the gap 20 portion of the core 1x. L _c is the inductance only in the material portion of the core 1x.

As is known, the inductance L of the reactor 100x corresponds to the inductance L _g of the gap 20 portion of the core 1x and the inductance L _c of the material portion of the core 1x connected in parallel. Therefore, the above equation (3) can be easily obtained from the above equations (1) and (2).

As is known, the relative magnetic permeability μ _s of the silicon steel plate constituting the core 1x is about 4000. When the length l of the magnetic path through which the magnetic flux flows is, for example, 20 to 100 mm, l/μ _s is in the range of 0.005 to 0.025. Therefore, since g is much larger than l/ _μs , l/ _μs can be ignored with respect to g. That is, from the above equations (1) and (3), the inductance L of the reactor 100x is approximately equal to the inductance L _g in the case of only the gap 20. Therefore, by forming the gap 20 in the core 1x, the inductance of the reactor 100 can be easily adjusted to fall within a desired range.

Note that when a plurality of gaps 20 are formed in the core 1x as shown in FIG. 2(b), the core 1x is completely divided into a plurality of members. Therefore, in order to maintain the overall shape of the core 1x (in other words, the length of the gap 20, etc.), it is necessary to separately provide a structure for holding the core 1x from the outside. This results in an increase in manufacturing man-hours and costs.

Furthermore, in the case of a completely separated gap 20, the generation of magnetic force in the gap 20 causes humming, which causes noise.

In consideration of this point, a slit portion 10 is formed in the core 1 of the reactor 100 of this embodiment instead of the gap 20 described above. The slit portion 10 is formed so as to penetrate the core 1 in a direction parallel to the axial direction of the core 1 . When viewed in this penetrating direction, the opening contour of the slit portion 10 is closed, and the slit portion 10 is formed so as not to be connected to either the inner wall or the outer wall of the cylindrical core 1. Thereby, the inductance of the reactor 100 can be adjusted appropriately without completely dividing the core 1. As a result, the mechanical strength of the core 1 can be ensured to a certain extent, so that the overall shape of the core 1 can be maintained well and the number of manufacturing steps can be reduced. Further, since the core 1 is not completely divided, noise can be reduced.

A plurality of slit portions 10 are formed in the core 1 of this embodiment. The plurality of slit portions 10 are arranged at equal intervals in the circumferential direction of the core 1.

As shown in FIGS. 3 and 4, each slit portion 10 is arranged at an intermediate portion (radially intermediate portion) between an inner wall and an outer wall of the core 1 formed in a cylindrical shape. Thereby, a bridge portion 3 is formed between the slit portion 10 and each of the inner and outer walls of the core 1.

The bridge portion 3 is a portion that connects the portions of the core 1 located on both sides of the slit portion 10 in the width direction to each other. The length of the bridge portion 3 in the longitudinal direction of the slit portion 10 (bridge width W shown in FIG. 4) is set to a predetermined value so that the passing magnetic flux is saturated in order to reduce the influence on inductance. Due to the presence of this bridge portion 3, as explained above, the overall shape of the core 1 can be maintained well, and noise can be reduced.

Each slit portion 10 is formed so as to penetrate the core in the axial direction of the core 1 (that is, the direction in which the silicon steel plates constituting the core 1 are laminated). In other words, slits of the same shape are formed in corresponding positions in each silicon steel plate. By stacking these silicon steel plates, a plurality of slits are joined and the above-mentioned slit portion 10 is formed.

The slit portion 10 is formed to be elongated so as to extend in the radial direction of the core 1 (in other words, in the direction perpendicular to the axial direction) when viewed in the axial direction of the core 1 . The direction in which the slit portion 10 extends can also be said to be the direction in which the two walls (inner wall and outer wall) forming the core 1 face each other. The slit portion 10 has an intermediate portion 11 and two end portions 12. In the following description, in order to identify each of the two ends 12, the end 12 closer to the inner circumference of the core 1 will be referred to as the inner circumference end 12a, and the end 12 closer to the outer circumference of the core 1 will be referred to as the inner circumference end 12a. The side end portion 12 is sometimes referred to as an outer peripheral end portion 12b.

The intermediate portion 11 is located between the two end portions 12 in the longitudinal direction of the slit portion 10, as shown in FIG. When viewed in the axial direction of the core 1, the intermediate portion 11 is formed to have the same width over the entire length (the entire length of the intermediate portion 11 in the longitudinal direction of the slit portion 10). That is, the width L2 of the intermediate portion 11 in the direction perpendicular to the longitudinal direction of the slit portion 10 is constant. Thereby, the shape of the slit portion 10 becomes simple, and the inductance of the reactor 100 can be easily adjusted.

As shown in FIG. 4, the end portions 12 are provided at both ends of the intermediate portion 11 in the longitudinal direction of the slit portion 10. The end portions 12 are smoothly connected to both ends of the intermediate portion 11, respectively. In this connecting portion, the opening contour of the slit portion 10 is formed by smoothly connecting curved lines and/or straight lines so that no corners are formed.

When viewed in the axial direction of the core 1 , the end portion 12 increases in the direction perpendicular to the longitudinal direction of the slit portion 10 as it moves away from the connection point with the intermediate portion 11 (or from the longitudinally intermediate portion of the slit portion 10 ). It is formed in a trumpet shape with a widening width L1.

As a result, as shown in FIG. 4, the width L1 of the end portion 12 is longer than the width L2 of the intermediate portion 11 (L1>L2).

Specifically, the inner peripheral end portion 12a widens from the connection point with the intermediate portion 11 so as to gradually increase the width of the slit portion 10 as it approaches the inner wall of the core 1. The outer peripheral end portion 12b widens from the connection point with the intermediate portion 11 so as to gradually increase the width of the slit portion 10 as it approaches the outer wall of the core 1.

In this way, the slit portion 10 is formed which narrows from the end portions 12 on both sides toward the middle portion 11. Since the intermediate portion 11 and the end portion 12 are smoothly connected, the slit portion 10 has a smooth shape and is elongated when viewed in the axial direction of the core 1. Thereby, the slit portion 10 can be easily formed, and the formation of corners where magnetic flux tends to concentrate can be avoided.

Next, the slit section 10 of this embodiment and the simple-shaped slit section 30 will be compared, and the effects of the slit section 10 of this embodiment will be explained with reference to FIG. FIG. 5A is a schematic diagram showing the flow of magnetic flux in the vicinity of the simple-shaped slit portion 30. FIG. 5(b) is a schematic diagram showing the flow of magnetic flux near the slit portion 10 of this embodiment.

The simple-shaped slit portion 30 has the same width over the entire length of the slit portion 30, as shown in FIG. 5(a). That is, the slit portion 30 is not formed with the wide end portion 12 as in this embodiment.

When a simple-shaped slit portion 30 is formed in the core 1 as shown in FIG. 5(a), the magnetic resistance in the slit portion 30 becomes larger than that in the core 1. Therefore, at both ends of the slit portion 30, the magnetic flux avoids the slit portion 30 and passes through the bridge portion 3. Therefore, magnetic flux concentrates on the bridge portion 3 formed between both ends of the slit portion 30 and each of the inner and outer walls of the core 1. As is known, the iron loss generated in the core 1 is proportional to the square of the magnetic flux density. As a result, the concentration of magnetic flux increases the magnetic flux density, resulting in a large amount of iron loss. If the iron loss is large, the performance of the reactor 100 will deteriorate and the amount of heat generated will increase, and as a result, measures such as cooling will be required.

In this regard, in the slit portion 10 of this embodiment shown in FIG. 5(b), as explained above, the intermediate portion 11 is An end portion 12 is formed having a width L1 that is longer than a width L2.

As is known, magnetic resistance is proportional to the length of the magnetic path through which the magnetic flux flows. Therefore, as explained above, since the length of the magnetic path (i.e. L1) through which the magnetic flux flows in the end portion 12 is longer than the length (i.e. L2) through which the magnetic flux flows in the intermediate portion 11, the end portion 12 has a larger magnetic reluctance than the intermediate portion 11.

In this way, the end portion 12 has a higher magnetic resistance than each of the portions on both sides of the end portion 12 (ie, the bridge portion and the intermediate portion 11) in the radial direction of the core 1. As a result, as shown in FIG. 5(b), a part of the magnetic flux near the end portion 12 flows avoidably from the bridge portion 3 toward the intermediate portion 11, thereby alleviating the concentration of magnetic flux in the bridge portion 3. I can do it.

Therefore, the reactor 100 of this embodiment can reduce the iron loss generated in the core 1 and the amount of heat generated in the core 1. Therefore, the cooling structure for cooling the core 1 can also be simplified.

In order to confirm the effects of the reactor 100 of this embodiment, the inventor of this application performed simulation calculations for each of the simple-shaped slit portion 30 and the slit portion 10 of this embodiment. Note that the conditions for performing the simulation are that the length of the bridge portion 3 (bridge width W) is 5% of the radial length of the core 1, and the width L1 of the end portion 12 is equal to the width L2 of the intermediate portion 11 and the bridge. The sum is twice the width W (2×W) (ie, L1=L2+2×W).

According to the simulation results, the iron loss can be reduced by 14% in the case of FIG. 5(b) where the slit portion has the shape of this embodiment compared to the case of FIG. 5(a) where the slit portion has a simple shape. was completed. Furthermore, in the case of FIG. 5(b), the inductance value was improved by 6% due to the decrease in the magnetic flux passing through the bridge portion 3 compared to the case of FIG. 5(a).

In this way, it was confirmed that the core 1 in which the slit portion 10 of the present embodiment was formed was able to reduce the occurrence of iron loss more than in the case of the slit portion 30 having a simple shape.

As explained above, the reactor 100 of this embodiment includes the core 1 and the coil 2. The core 1 is made of a magnetic material. Coil 2 is wound around core 1 . The core 1 has an elongated slit portion 10 that penetrates the core 1 . When viewed in the penetrating direction in which the slit section 10 penetrates the core 1, the opening contour of the slit section 10 is closed. The shape of the slit portion 10 when viewed in the penetrating direction is an elongated shape, and both end portions 12 in the longitudinal direction have a width L1 wider than the width L2 of the intermediate portion 11 in the longitudinal direction.

Thereby, the inductance (performance) of the reactor 100 can be adjusted favorably without cutting the core 1, and magnetic flux saturation of the core 1 can be avoided. In addition, by widening the width of the longitudinal end of the slit portion 10, concentration of magnetic flux near the end 12 can be alleviated, and iron loss occurring in the core 1 and heat generation amount in the core 1 can be reduced. can do. Further, since the core 1 is not completely divided, a certain degree of mechanical strength can be ensured. Therefore, the shape of the core 1 can be maintained well, and handling such as transportation is easy. Furthermore, since the core 1 is not completely divided, the hum (noise) generated from the core 1 can be reduced.

Furthermore, in the reactor 100 of this embodiment, the intermediate portion 11 of the slit portion 10 has a constant width in the transverse direction, which is a direction perpendicular to the penetration direction and the longitudinal direction.

Thereby, the shape of the slit portion 10 becomes simple, and the inductance of the reactor 100 can be easily adjusted.

In addition, in the reactor 100 of this embodiment, when viewed in the penetration direction, the portion of the opening contour of the slit portion 10 that extends generally along the longitudinal direction of the slit portion 10 is a smooth series of curved lines and/or straight lines. It has a similar shape.

Thereby, it is possible to avoid the formation of corners where magnetic flux concentrates, and the slit portion 10 can be easily formed.

Moreover, in the reactor 100 of this embodiment, the core 1 is formed in a cylindrical shape. The slit portion 10 is formed to penetrate the core 1 in the axial direction of the core 1 . A plurality of slit portions 10 are formed at equal intervals in the circumferential direction of the core 1 .

Thereby, a cylindrical reactor with good performance can be provided.

Although the preferred embodiments of the present invention have been described above, the above configuration can be modified as follows, for example.

The slit portion 10 may be formed to penetrate the core 1 in the radial direction of the core 1 (in other words, to connect the inner wall and the outer wall of the cylindrical core 1). In addition, it is preferable that the slit part 10 penetrates the core 1 in the lamination direction of the silicon steel plates which constitute the core 1.

As shown in FIG. 6, the slit portion 10 may be formed such that the inner peripheral end 12a has a larger area than the outer peripheral end 12b when viewed in the axial direction of the core 1. In this way, by forming the inner circumferential end 12a so as to have a larger magnetic resistance than the outer circumferential end 12b on the inside of the core 1 where magnetic flux tends to concentrate, The effect of alleviating magnetic flux concentration in the nearby bridge portion 3 can be improved.

Instead of forming both of the two end portions 12 of the slit portion 10 with a wide width, only one end portion 12 may be formed with a wide width. For example, only the end portion 12 of the core 1 closer to the inner wall side may be formed to have a wider width, or only the end portion closer to the outer wall side may be formed to have a wider width.

The slit portion 10 may be changed into various shapes as shown in FIG. 7, for example, as long as the end portion in the longitudinal direction can be formed wider than the middle portion. That is, the shape of the end portion 12 may be formed into, for example, a circle, a square, a trapezoid, etc., in addition to a trumpet shape. In the intermediate portion 11 of the slit portion 10, the width may not be uniform.

The core 1 is not limited to being formed in a cylindrical shape, but may be formed in a rectangular tube shape, for example.

1 core 2 coil 10 slit part (penetrating part)
11 Middle part 12 End part 100 Reactor

Claims (2)

A reactor comprising a core made of a magnetic material and a coil wound around the core,
The core has an elongated penetrating portion that penetrates the core,
When viewed in the penetrating direction in which the penetrating portion penetrates the core, the opening contour of the penetrating portion is closed;
The shape of the penetration part when viewed in the penetration direction is an elongated shape, and at least one end in the longitudinal direction has a width wider than the width of the intermediate part in the longitudinal direction,
The core is formed in a cylindrical shape,
The penetrating portion is formed to penetrate the core in the axial direction of the core,
A plurality of the penetrating portions are formed at equal intervals in the circumferential direction of the core,
The reactor is characterized in that the intermediate portion of the penetrating portion has a constant width in the transverse direction, which is a direction perpendicular to the penetrating direction and the longitudinal direction. The reactor according to claim 1 ,
A reactor characterized in that, when viewed in the penetration direction, a portion of the opening contour of the penetration portion that extends generally along the longitudinal direction has a shape in which curves and/or straight lines are smoothly connected.

Images