JP2020096008A - Iron core with gap for stationary induction apparatus - Google Patents

Abstract

To suppress generation of variations in the distribution of leakage flux at each phase in an iron core with a gap provided at an upper end of a leg part.SOLUTION: The iron core with gap for stationary induction apparatus includes a plurality of leg parts around which a winding is wound and upper and lower yoke parts with which the plurality of leg parts are joined. At a butt joined part of the upper end of each leg part to the upper yoke part, a gap is provided. At both ends of the upper yoke part, there is provided an eaves projecting more laterally than the leg part positioned at both the ends.SELECTED DRAWING: Figure 1

Description

Embodiments of the present invention relate to a core with a gap for a stationary induction device.

In an iron core of a static induction device, for example, a three-phase transformer used in a semiconductor power conversion device, three legs are respectively wound with windings of each phase, and they are provided so as to connect them vertically. It is composed of upper and lower yoke parts. Each of these legs and yoke portion is formed by laminating a plurality of electromagnetic steel plates. In addition, a gap is provided between the upper end of each leg and the lower surface of the upper yoke, and an insulator made of a non-magnetic material is placed in the gap to improve magnetic saturation characteristics. And so on.

JP-A-6-283351

In the transformer with a gap as described above, a leakage magnetic flux leaks into the space so as to spread between the upper end portion of the leg portion of the iron core and the upper yoke portion across the gap portion. However, the spread of the leakage flux is larger in the central leg of the three legs than in the left and right legs. Such variations in the distribution of leakage magnetic flux change the coil impedance of each phase, which may cause variations in the characteristics of the transformer. In this case, it is possible to shift the position of the gap below the leg, but if the gap is hidden inside the winding, the manufacturing process becomes complicated, and the width of the gap cannot be made uniform due to the weight of the iron core. However, there is a problem that the leakage magnetic flux affects the local heating of the windings and other structural members, and it is preferable that the gap be provided above the leg.

Therefore, there is provided a core with a gap for a static induction device, in which a gap is provided at the upper ends of the legs, and the variation in the distribution of the leakage magnetic flux in each phase can be suppressed.

The iron core with a gap for a static induction device according to the embodiment includes a plurality of leg portions on which windings are wound, and upper and lower yoke portions to which the plurality of leg portions are joined, and A gap is provided at the butt joint between the upper end of each leg and the upper yoke portion, and at both ends of the upper yoke portion, an eaves portion protruding laterally beyond the legs located at both ends is provided. It is provided.

1 is a perspective view schematically showing the configuration of a transformer according to the first embodiment. Front view showing the top of the transformer The figure which shows the test result which investigated the fluctuation rate of the exciting current in the eaves part of various dimensions. A front view (a), a plan view (b) of the right end portion of the upper yoke portion for explaining the length dimension S from the leg side surface of the eaves portion, and a plan view (c) of the upper yoke portion removed. Front view (a) and plan view (b) of the right end portion of the upper yoke portion for explaining various dimensions a to d of the eaves portion. The 2nd Embodiment is shown and the front view which shows roughly the structure of a transformer. The 3rd Embodiment is shown, and the front view which shows the structure of a transformer roughly. The 4th Embodiment, It is a front view which shows the structure of a transformer roughly. Perspective view of the upper end of one leg The perspective view which shows 5th Embodiment and shows the structure of a transformer roughly. Side view of transformer Top view of one leg The perspective view which shows 6th Embodiment and shows the structure of a transformer roughly. Front view of transformer Side view of the upper part

Hereinafter, some embodiments applied to, for example, a three-phase transformer for power electronics will be described with reference to the drawings. In addition, the same reference numerals are given to the same portions among the plurality of embodiments, and repeated description will be omitted.

(1) First Embodiment A first embodiment will be described with reference to FIGS. 1 to 5. FIG. 1 schematically shows a main part configuration of a three-phase transformer 1 as a stationary induction device of the present embodiment. This transformer 1 is configured by mounting three windings 3 on an iron core 2 with a gap (hereinafter simply referred to as “iron core 2”) according to this embodiment.

The iron core 2 includes an upper yoke portion 4 and a lower yoke portion 5 extending in the left-right direction in the figure, and three leg portions 6 that vertically connect the yoke portions 4 and 5. Each of the yoke portions 4 and 5 and each leg portion 6 is configured by laminating a plurality of electromagnetic steel plates made of, for example, a silicon steel plate in the front-back direction (thickness direction) in the drawing. The iron core 2 as a whole is constructed by butt-joining the yoke portions 4 and 5 and the leg portions 6. The lower yoke portion 5 and the three leg portions 6 may be integrally provided, that is, the E-shaped electromagnetic steel plates may be laminated. Further, as the magnetic steel sheet, for example, a grain-oriented magnetic steel sheet is used.

At this time, each of the leg portions 6 is formed in a so-called chamfered front, rear, left and right edges so as to form a substantially octagonal shape when viewed from above, as partially shown in FIG. 4(c). .. Specifically, as partially shown in FIG. 4(c), it is made up of three parts of approximately equal thickness in the front-rear direction (stacking direction), of which the electromagnetic steel plate of the same width dimension is formed in the central part. It is stacked. In the front portion in the thickness direction, the electromagnetic steel sheets are laminated in a form that gradually narrows toward the front, and in the rear portion, the electromagnetic steel sheets are laminated in a manner that gradually narrows toward the rear. There is.

Although not shown in detail, the winding 3 has an inner peripheral side winding 3a on the low voltage side and an outer peripheral side winding 3b on the high voltage side. As shown in FIG. 1, windings 3 for three phases (three) are wound around the outer circumference of each leg 6. In this case, since the front, rear, left, and right edges of each leg 6 are so-called chamfered, the outer shape of each leg 6 is close to a circular shape, and the winding 3 when wound is wound. The gap between the inner peripheral surface of the armature 3 and the leg 6 is reduced.

Now, in the iron core 2 of the present embodiment, as shown in FIGS. 1 and 2, the gap 7 is formed at the butt joint portion between the upper end portion of each leg portion 6 and the lower surface of the upper yoke portion 4. ing. The gap 7 is located in the upper part exposed from the upper end of the winding 3. Although not shown, an insulator made of a non-magnetic material such as insulating paper having a predetermined thickness is inserted in the gap 7 portion. Further, at both ends of the upper yoke portion 4, eaves portions 8 which protrude laterally beyond the leg portions 6 located at both ends are integrally provided.

In the present embodiment, the eaves portions 8, 8 have the same cross section as the upper yoke portion 4, that is, the same thickness and height dimension, and are provided so as to extend to the left and right sides in the drawing. At this time, FIGS. 4 and 5 show the eaves portion 8 on the right side as a representative, and the protruding length dimension S of the eaves portion 8 from the side surface of the leg extension 6 is at least the inner circumference in plan view. It extends so as to hang over the side winding 3a, and at the same time, extends so as not to exceed at least the outer peripheral edge portion of the outer circumferential side winding 3b in a plan view. The eaves portion 8 on the left side is also provided symmetrically with the right side.

Next, the operation and effect of the above configuration will be described with reference to FIGS. In the transformer 1 having the above-described configuration, the gap 7 is provided between the upper end portion of each leg portion 6 of the iron core 2 and the upper yoke portion 4, so that the gap 7 portion is sandwiched between the leg portions 6 and Leakage magnetic flux leaks into the space so as to spread between the upper end portion and the upper yoke portion 4. In this case, if the distribution of the leakage magnetic flux varies among the three legs 6, the magnetic flux interlinking with the winding 3 is different, so that the coil impedance of each phase changes and the transformer 1 There is a possibility that the characteristics may change.

However, in the present embodiment, the eaves portions 8 are provided at both end portions of the upper yoke portion 4 so as to extend laterally beyond the leg portions 6 located at both ends. As a result, the leg portions 6 located at the left and right ends and the leg portion 6 located in the central portion face the upper yoke portion 4 across the gap 7, that is, the positional relationship with the upper yoke portion 4. The shape and shape of all the legs 6 can be made equal. As a result, even if there is a situation in which a leakage magnetic flux that spreads in space is generated in the gap 7, the leakage magnetic flux distribution state. In other words, the form of crossing the space between the leg portion 6 and the upper yoke portion 4 becomes uniform in each leg portion 6, that is, in each phase, and it is possible to prevent the occurrence of the trouble due to the variation of the distribution of the leakage magnetic flux. it can.

In addition, the present inventors conducted a test to find out how long the lateral extension of the leg portion 6 should extend laterally from the side surface of the leg portion 6 when the eave portion 8 is provided to suppress the fluctuation of the exciting current. The test results are shown in FIG. Here, the extension length dimension from the side surface of the leg portion 6 of the eaves portion 8 is S, and as shown in FIG. 5, the value of the length S is −10 mm, 0 mm, a(40) mm, b(85 ) Mm, c (130) mm, and d (175) mm, six samples were examined for the maximum fluctuation rate of the exciting current. In the test results of FIG. 3, the horizontal axis represents the distance (mm) from the side surface of the leg portion 6, and the vertical axis represents the maximum fluctuation rate of the exciting current.

From this result, when the value of the dimension S is -10 mm and 0 mm, that is, when the eaves portion 8 is not provided, the maximum fluctuation rate of the exciting current is relatively large. On the other hand, in the eaves portion 8 having a length of about 40 mm from the side surface of the leg portion 6 of a, that is, a length enough to hang over the inner winding 3a in a plan view, the maximum fluctuation rate of the exciting current can be made relatively small. It was Similarly, similar test results were obtained for b and c. Furthermore, the effect of d, which is lengthened until it exceeds the outer peripheral end of the outer peripheral winding 3b in plan view, is not much different from that of shorter d.

As described above, according to the iron core 2 of the present embodiment, the leg 7 is provided with the gap 7 at the upper end thereof, and the eaves 8 are provided at both ends of the upper yoke 4, so that the phases of each phase are different. It is possible to obtain an excellent effect that the variation in the distribution of the leakage magnetic flux can be suppressed. In particular, in the present embodiment, the length of the eaves portion 8 is set so as to extend over at least the inner circumference side winding 3a in a plan view, and thus it is possible to obtain a sufficient effect to equalize the distribution state of the leakage magnetic flux in the gap 7. You can Further, in the present embodiment, the length of the eaves portion 8 is set so as not to exceed the outer circumference side winding 3b, so that it is possible to obtain a sufficient effect without making the eaves portion 8 excessively large.

(2) Second Embodiment FIG. 6 shows a transformer 11 according to a second embodiment. The iron core 12 of the transformer 11 is also made of a laminated iron core, and includes an upper yoke portion 14 and a lower yoke portion 15, and three leg portions 16 that vertically connect the yoke portions 14 and 15. ing. At this time, a gap 17 is provided below each leg 16 in a state where a part 16a of the upper end of the leg 16 is joined to the upper yoke portion 14 above. It should be noted that both ends of the upper yoke portion 14 are not provided with eaves, and substantially match the side surfaces of the legs 16 in a plan view.

In the second embodiment, the position of the gap 17 is not directly below the lower surface of the upper yoke portion 14 but slightly below it. Therefore, the gap 17 exists in the middle of the leg portion 16, and the distance in the height direction to the upper yoke portion 14 when the leakage magnetic flux flows increases. As a result, in all the leg portions 16, the leakage magnetic flux is distributed so as to swell and flow in the space between both sides of the gap 17, and the distribution of the leakage magnetic flux becomes uniform in each leg portion. Therefore, according to the present embodiment as well, it is possible to obtain an effect that the variation in the distribution of the leakage magnetic flux in each phase can be suppressed in the case where the gap 17 is provided at the upper end portion of the leg portion 16.

(3) Third Embodiment FIG. 7 shows a transformer 21 according to a third embodiment. The iron core 22 of the transformer 21 is also made of a laminated iron core, and includes an upper yoke portion 24 and a lower yoke portion 25, and three leg portions 26 that vertically connect the yoke portions 24, 25. ing. A gap 27 is provided between the upper end surface of each leg portion 26 and the lower surface of the upper yoke portion 24. At this time, in the present embodiment, a grain-oriented electrical steel sheet whose rolling direction is the vertical direction is used for the portion 26a of each leg portion 26 located below the gap 27. The non-oriented electrical steel sheet is used in the other parts of the iron core 22. It should be noted that both ends of the upper yoke portion 24 are not provided with eaves, and substantially match the side surfaces of the legs 26 in a plan view.

In the third embodiment, in the part 26a of the lower portion of the gap 27 of the leg portion 26, the magnetic flux easily flows in the vertical direction, and the leakage magnetic flux is less likely to be generated in the direction in which the magnetic flux spreads in the space. Therefore, according to the present embodiment, it is possible to suppress the generation of the leakage magnetic flux itself, and to suppress the variation of the leakage magnetic flux distribution in each phase in the case where the gap 27 is provided at the upper end of the leg portion 26. The effect that can be obtained can be obtained.

(4) Fourth Embodiment FIGS. 8 and 9 show a fourth embodiment. As shown in FIG. 8, the iron core 32 of the transformer 31 according to the present embodiment is also made of a laminated iron core, includes an upper yoke portion 34 and a lower yoke portion 35, and connects the yoke portions 34, 35 between them. It is provided with three legs 36 that are vertically connected. A gap 37 is provided between the upper end surface of each leg portion 36 and the lower surface of the upper yoke portion 34. At this time, as shown in FIG. 9, the side surface of the upper end portion of each leg portion 36 is formed as an inclined surface 36 a that becomes narrower toward the gap 37. It should be noted that both ends of the upper yoke portion 34 are not provided with eaves, and substantially match the side surfaces of the leg portions 36 in a plan view.

In the fourth embodiment, the side surface of the upper end portion of the leg portion 36 is the inclined surface 36a, so that the distance between the inclined surface 36a and the lower surface of the upper yoke portion 34 is shortened, and the space is reduced. Leakage magnetic flux is less likely to be generated in the expanding direction. Therefore, according to the present embodiment, it is possible to suppress the generation of the leakage magnetic flux itself, that is, the swelling to the lateral space, and to provide the gap 37 at the upper end portion of the leg portion 36 so that the leakage in each phase is prevented. It is possible to obtain the effect of suppressing variations in the distribution of magnetic flux.

(5) Fifth Embodiment Next, a fifth embodiment will be described with reference to FIGS. 10 and 11 schematically show the overall configuration of the transformer 41 according to the fifth embodiment. The iron core 42 of the transformer 41 is also made of a laminated iron core, and includes an upper yoke portion 44 and a lower yoke portion 45, and three leg portions 46 that vertically connect the yoke portions 44, 45. ing. A gap 47 is provided between the upper end surface of each leg portion 46 and the lower surface of the upper yoke portion 44. At this time, as shown in FIG. 12, each of the leg portions 46 is chamfered at the front, rear, left and right edges so as to form a substantially octagonal shape when viewed from above, as in the first embodiment. It is configured in the form.

Then, in the present embodiment, as shown in FIGS. 10 and 11, the upper yoke portion 44 is composed of three portions having substantially equal thickness in the front-rear direction (stacking direction), of which the front portion and the rear portion are Are laminated with electromagnetic steel sheets having the same width dimension (height dimension), and in the central portion 44a, electromagnetic steel sheets having larger width dimensions (dimensions in the height direction) are laminated. Thus, the upper yoke portion 44 has a shape in which the central portion in the thickness direction has a larger cross-sectional area than the front portion and the rear portion. As shown in FIG. 11, the lower yoke portion 45 is also symmetrical to the upper yoke portion 44, and the central portion 45a is convex downward.

In the fifth embodiment, in each leg portion 46, the magnetic resistance in the central portion in the thickness direction is smaller than the magnetic resistance in the front portion and the rear portion, and the magnetic flux easily flows in the central portion in the thickness direction. The magnetic flux becomes relatively difficult to flow. Further, also in the upper yoke portion 44, the magnetic resistance of the central portion 44a in the thickness direction becomes smaller than the magnetic resistance of the front portion and the rear portion, magnetic flux easily flows in the central portion 44a in the thickness direction, and the front and rear portions relatively. It becomes difficult for the magnetic flux to flow. As a result, leakage magnetic flux is less likely to be generated in the direction in which the gap 47 extends into the space.

According to the present embodiment, the magnetic flux easily flows in the central portion of the iron core 42 in the thickness direction, and the magnetic flux relatively less flows in the front and rear portions in the thickness direction, so that the generation of the leakage magnetic flux can be suppressed. As a result, it is possible to obtain the effect of suppressing variations in the distribution of the leakage magnetic flux in each phase.

(6) Sixth Embodiment and Other Embodiments FIGS. 11 to 13 show a sixth embodiment, and a configuration different from that of the fifth embodiment will be described below. The iron core 52 of the transformer 51 according to the sixth embodiment is also formed of a laminated iron core, includes an upper yoke portion 54 and a lower yoke portion 55, and connects the yoke portions 54, 55 vertically. A book leg 56 is provided. A gap 57 is provided between the upper end surface of each leg portion 56 and the lower surface of the upper yoke portion 54 as described later.

At this time, each leg portion 56 is made up of three portions having an approximately equal thickness in the front-rear direction (stacking direction), and the front portion and the rear portion thereof have front and rear left and right portions so as to form a substantially octagonal shape when viewed from above. The edge is configured in a so-called chamfered form. Then, as shown in FIG. 13, in the central portion of the three portions of each leg portion 56, electromagnetic steel sheets having a slightly smaller height dimension are laminated, whereby the upper end portion of each leg portion 56 is A recessed groove portion 56a is formed at the center in the thickness direction.

On the other hand, the lower surface portion of the upper yoke portion 54 is configured such that the central portion in the thickness direction is formed by laminating electromagnetic steel sheets that are longer in the height direction (longer in the downward direction) than the front portion and the rear portion. A convex portion 54a that is convex downward is provided so as to mesh with the concave groove portion 56a. As a result, the gap 57 formed between the upper end surface of each leg portion 56 and the lower surface portion of the upper yoke portion 54 has an uneven shape when viewed from the side. Further, eaves portions 58 are integrally provided at both ends of the upper yoke portion 54. The lower yoke portion 55 has a flat lower surface.

According to the sixth embodiment as described above, since the eaves portions 58 are provided at both ends of the upper yoke portion 54, it is possible to suppress the variation in the distribution of the leakage magnetic flux in each phase. Then, like the fifth embodiment, the magnetic flux easily flows in the central portion in the thickness direction of the iron core 52 as a whole, and the magnetic flux relatively less flows in the front and rear portions. As a result, leakage magnetic flux is less likely to occur in the direction in which the gap 57 extends into the space. As a result, according to the present embodiment, in the case where the gap 57 is provided at the upper end portion of the leg portion 56, it is possible to further enhance the effect of suppressing the variation in the distribution of the leakage magnetic flux in each phase. In addition to this, it is possible to increase the cross-sectional area of the central portion without increasing the upper yoke portion 54 in the height direction.

In addition, in the said 6th Embodiment, although it comprised so that the upper yoke part 54 might be provided with the eaves part 58, even if it does not have the eaves part 58, the effect which suppresses the variation of the distribution of the leakage magnetic flux in each phase can be obtained. You can Further, in each of the above-described embodiments, the present invention is applied to a three-phase transformer as a stationary induction device, but it is also possible to apply to a four-phase or more transformer as a stationary induction device. It can also be applied to reactors. In addition, various modifications can be made to the joint structure of the yoke portion and the leg portion.

The embodiments described above are presented as examples, and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the scope equivalent thereto.

In the drawing, 1, 11, 21, 31, 41, 51 are transformers (stationary induction devices), 2, 12, 22, 32, 42, 52 are iron cores (iron cores with a gap), 3 are winding wires 4, 14 , 24, 34, 44, 54 are upper yoke portions, 5, 15, 25, 35, 45, 55 are lower yoke portions, 6, 16, 26, 36, 46, 56 are leg portions, 7, 17, 27, 37, 47 and 57 are gaps, and 8 and 58 are eaves.

Claims (8)

A plurality of legs around which the winding is wound,
With the upper and lower yoke portions to which the plurality of leg portions are joined,
A gap is provided at the butt joint between the upper end of each leg and the upper yoke portion,
An iron core with a gap for a static induction device, in which both ends of the upper yoke portion are provided with eaves portions that extend laterally beyond the legs located at both ends. The winding includes an inner circumference side winding and an outer circumference side winding,
The iron core with a gap for a static induction device according to claim 1, wherein the length of the eave portion extends so as to extend over at least the inner peripheral winding in a plan view. The winding includes an inner circumference side winding and an outer circumference side winding,
The iron core with a gap for a static induction device according to claim 1 or 2, wherein a length of the eave portion extends so as not to exceed at least the outer peripheral winding in a plan view. A plurality of legs around which the winding is wound,
With the upper and lower yoke portions to which the plurality of leg portions are joined,
A core with a gap for a static induction device, wherein a gap is provided below an upper end of each leg in a state where a part of an upper end of the leg is joined to the upper yoke portion. A plurality of legs around which the winding is wound,
With the upper and lower yoke portions to which the plurality of leg portions are joined,
A gap is provided at the butt joint between the upper end of each leg and the upper yoke portion,
A core with a gap for a static induction device in which a grain-oriented electrical steel sheet having a rolling direction as an up-down direction is used for a portion of the leg portion located below the gap. A plurality of legs around which the winding is wound,
With the upper and lower yoke portions to which the plurality of leg portions are joined,
A gap is provided at the butt joint between the upper end of each leg and the upper yoke portion,
An iron core with a gap for a static induction device, wherein a side surface of an upper end portion of each leg portion is formed in an inclined surface shape narrowing toward the gap. A plurality of legs around which the winding is wound,
With the upper and lower yoke portions to which the plurality of leg portions are joined,
A gap is provided at the butt joint between the upper end of each leg and the upper yoke portion,
The leg portions located at least at both ends of the leg portion have a shape that narrows toward the front in the front portion in the thickness direction of the side surface, and has a width toward the rear in the rear portion in the thickness direction of the side surface. The shape is narrowed,
The iron core with a gap for a static induction device, wherein the central portion of the upper yoke portion in the thickness direction has a larger cross-sectional area than the front portion and the rear portion. The upper end of each of the legs is configured such that the central portion in the thickness direction is formed into a groove shape, and the lower surface portion of the upper yoke portion is formed such that the central portion in the thickness direction is formed into a convex shape,
The core with a gap for a static induction device according to claim 7, wherein the gap is provided between them.

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