JP5405327B2 - Single-phase transformer and power distribution system using the same - Google Patents

Description

  The present invention relates to a single-phase transformer with improved winding arrangement and winding direction when a two-legged iron core is adopted, and a power distribution system using the single-phase transformer.

  In general, in an AC feeder system such as a Shinkansen, it is important to take measures to compensate for a voltage drop that occurs on the feeder side. For this reason, various techniques have been proposed for an AC feeding voltage compensation system (for example, Patent Document 1). In such a system, the single-phase transformer is a basic component, and high reliability is required.

  Hereinafter, a conventional example of a single-phase transformer employing a two-legged iron core will be described with reference to FIGS. 8 is a cross-sectional view of a conventional single-phase transformer, and FIG. 9 is a cross-sectional view taken along line AA of FIG. As shown in FIG. 8, the first iron core leg 1 and the second iron core leg 2 are arranged opposite to each other in the single-phase transformer.

  These iron core legs 1 and 2 are connected at their upper and lower portions by yoke portions. Each of the first core leg 1 and the second core leg 2 is wound with the secondary windings 3a and 3b, and the primary windings 4a and 4b are concentrically wound around the outer periphery thereof. That is, when viewed from the core legs 1 and 2, the primary windings 4a and 4b are wound on the outer peripheral side, and the secondary windings 3a and 3b are wound on the inner peripheral side (see FIG. 9). These windings 3a, 3b, 4a, and 4b are respectively connected in parallel or in series.

JP 2006-81325 A

  By the way, when a short circuit occurs on the secondary side of the single-phase transformer, a short circuit current that is several times to a dozen times as large as the rated current that normally flows flows through the winding. Therefore, a strong electromagnetic force is generated in the winding, and the mechanical force on the winding increases. As already described, in the conventional single-phase transformer, the primary windings 4a and 4b and the secondary windings 3a and 3b are configured concentrically.

  In this case, the direction of the electromagnetic force generated in the windings 3a, 3b, 4a and 4b is directed inward in the inner secondary windings 3a and 3b with respect to the radial direction of the windings 3a, 3b, 4a and 4b. The outer primary windings 4a and 4b go outward. The magnitude of the electromagnetic force in the radial direction of these windings 3a, 3b, 4a, and 4b (hereinafter referred to as radial electromagnetic force) depends on the density of the axial leakage magnetic flux interlinking with the windings 3a, 3b, 4a, and 4b. Proportional.

  That is, if the axial leakage magnetic flux of the windings 3a, 3b, 4a, and 4b is evenly distributed in the winding circumferential direction, the radial electromagnetic force is also uniform in the winding circumferential direction. Therefore, even if the radial electromagnetic force increases with the occurrence of the short-circuit current, this force acts evenly on the windings 3a, 3b, 4a and 4b. Therefore, there is no fear that the mechanical force that easily deforms the circular state of the windings 3a, 3b, 4a, and 4b is applied to the windings 3a, 3b, 4a, and 4b.

  However, if the axial leakage magnetic flux of the windings 3a, 3b, 4a and 4b is biased in the winding circumferential direction, the radial electromagnetic force is also biased. In this case, when a short-circuit current is generated, a strong radial electromagnetic force acts unevenly in the radial direction of the winding, and the mechanical force in the oblique direction is easy to deform the circular state of the windings 3a, 3b, 4a, and 4b. Is added to the windings 3a, 3b, 4a, 4b.

  This point will be described with reference to FIGS. FIG. 10 shows the current direction and the leakage flux in the single-phase transformer shown in FIGS. As shown in FIG. 10, secondary currents 6a and 6b flow in the secondary windings 3a and 3b, and primary currents 7a and 7b flow in the primary windings 4a and 4b. The direction of each current is represented by a cross (x) or dot (•) surrounded by a white arrow and a circle.

  A leakage flux 8a is generated by the secondary current 6a and the primary current 7a, and a leakage flux 8b is generated by the secondary current 6b and the primary current 7b. Leakage magnetic fluxes 8a and 8b are indicated by hatched arrows. Here, the internal and external positional relationships of the primary windings 4a, 4b and the secondary windings 3a, 3b with respect to the core legs 1, 2 are the same in the two core legs 1, 2.

  Thus, when coils having the same positional relationship between the primary side and the secondary side face each other, the leakage magnetic flux 8a and the leakage magnetic flux 8b are the same in the vicinity of the place where these coils face each other. Therefore, the magnetic path lengths of the leakage magnetic fluxes 8a and 8b at the locations where the coils face each other are substantially halved compared to the magnetic path lengths of the leakage magnetic fluxes 8a and 8b at other locations.

  Therefore, in the vicinity of the place where the coils face each other, the magnetic resistance is also halved compared to other places. As a result, as shown in FIG. 11, the density of the leakage magnetic fluxes 8a and 8b is high at a location where the magnetic resistance is small, that is, where the coils face each other (A portion surrounded by a one-dot chain line in FIG. 11). The density of the magnetic fluxes 8a and 8b is low (B portion surrounded by a two-dot chain line in FIG. 11).

  As described above, in the two sets of coils, when the positional relationship between the primary side and the secondary side is the same, there is a difference in the density of the leakage magnetic fluxes 8a and 8b between the place where the coils face each other and the other place. is there. Therefore, the inner radial electromagnetic force proportional to the density of the leakage magnetic fluxes 8a and 8b acts biased in the radial direction of the windings 3a, 3b, 4a and 4b.

  In particular, in the winding positioned on the outer peripheral side of the iron core leg, it is necessary to endure the outer radial electromagnetic force only by the tensile stress generated in the conductor of the winding. For this reason, if the outer radial electromagnetic force is biased and acts strongly in the circumferential direction of the winding, it is difficult to keep the winding located on the outer circumferential side in a circular state, which causes the winding to be deformed.

  The present invention has been proposed in view of such conventional circumstances, and its purpose is to equalize the distribution of axial leakage magnetic flux in the circumferential direction of the winding, and to generate a radial direction during secondary short-circuiting of the transformer. By making the electromagnetic force uniform in the circumferential direction of the winding, deformation of the winding is prevented, thereby improving the short-circuit resistance mechanical force, and a highly reliable single-phase transformer and a power distribution system using the same It is to provide.

In order to achieve the above object, a single-phase transformer according to the present invention has two core legs arranged opposite to each other and connected by upper and lower yoke portions of the core legs, and each core leg has a primary winding. In a single-phase transformer in which a wire and a secondary winding are wound concentrically, and the primary winding and the secondary winding are respectively connected in parallel or in series, one of the iron core legs has the primary winding on the outer peripheral side. The secondary winding is wound on the inner peripheral side, the other iron core leg is wound on the primary winding on the inner peripheral side, and the secondary winding is wound on the outer peripheral side. direction of the main magnetic flux formed in the core leg Ri Do in opposite directions, and the primary winding of the outer peripheral side, the direction of the current flowing through said secondary winding of the outer peripheral side, and opposite to each other characterized by being configured such that.

  In the present invention having the above configuration, the value of the magnetic resistance that determines the distribution of leakage flux in the circumferential direction of the winding is uniform in the circumferential direction of the winding. Therefore, the radial electromagnetic force proportional to the axial leakage flux density is also equalized in the circumferential direction of the winding. Thus, even if a short circuit occurs on the secondary side of the transformer and the radial electromagnetic force increases, the electromagnetic force is not biased in the circumferential direction of the winding, and the winding located on the outer circumferential side There is no risk of deformation of the circular state.

  According to the present invention, even if a short circuit occurs on the secondary side of the transformer, the distribution of the axial leakage magnetic flux is made uniform in the circumferential direction of the winding. To provide a single-phase transformer with improved reliability and a power distribution system using the same, which can act evenly in the circumferential direction to improve the short-circuit mechanical force and prevent deformation of the winding. it can.

Sectional drawing of 1st Embodiment which concerns on this invention. Explanatory drawing which shows the winding condition of the coil | winding in 1st Embodiment. Sectional drawing of 1st Embodiment (The direction of electric current and a leakage magnetic flux are included.) The top view which shows the circumferential direction distribution of leakage magnetic flux in 1st Embodiment. Sectional drawing of 2nd Embodiment which concerns on this invention. Sectional drawing of 2nd Embodiment (The direction of electric current and a leakage magnetic flux are included). The top view which shows the circumferential direction distribution of the leakage magnetic flux in 2nd Embodiment. Sectional drawing of the conventional single phase transformer. AA sectional drawing of FIG. Sectional drawing of a conventional single-phase transformer (including current direction and leakage flux). The top view which shows the circumferential direction distribution of the leakage magnetic flux in the conventional single phase transformer.

(1) First Embodiment [Configuration]
Hereinafter, the first embodiment according to the present invention will be specifically described with reference to FIGS. The first embodiment is applied to a single-phase transformer used in an AC feeder system such as a bullet train.

  FIG. 1 is a cross-sectional view of an iron core and a winding showing the first embodiment, FIG. 2 is an explanatory view showing the winding state of the winding, and FIG. 3 is a cross-sectional view showing the direction of current in the first embodiment. 4 is a plan view showing the distribution of leakage magnetic flux in the circumferential direction in the first embodiment. FIG. In addition, the same code | symbol is attached | subjected about the same member as the prior art example shown in FIGS. 8-11, and description is abbreviate | omitted.

  The structural features of the first embodiment are as follows. That is, in the first core leg 1, the primary winding 4a is wound on the outer peripheral side, and the secondary winding 3a is wound on the inner peripheral side. In the second core leg 2, the primary winding 4 b is wound on the inner peripheral side and the secondary winding 3 b is wound on the outer peripheral side, contrary to the arrangement of the first core leg 1.

  In FIG. 1, a cross (×) and a dot (•) surrounded by a double circle indicate the winding direction from the terminal U (or u) to the terminal V (or v) of each winding. FIG. 2 is a schematic representation of the winding directions of the primary windings 4a and 4b shown.

  As can be seen from FIGS. 1 and 2, the secondary winding 3a and the primary winding 4a wound around the first core leg 1, the secondary winding 3b wound around the second core leg 2 and the primary winding. In the wire 4b, the winding direction is reversed between the two iron core legs 1 and 2. This is because the direction of the main magnetic flux 5a induced in the first iron core leg 1 and the direction of the main magnetic flux 5b induced in the second iron core leg 2 are turned upside down with respect to each other. This is because the main magnetic fluxes 5a and 5b are circulated in the iron core. The primary currents 7a and 7b and the secondary currents 6a and 6b flowing in the primary windings 4a and 4b and the secondary windings 3a and 3b flow in a direction that cancels the ampere turns.

[Function and effect]
The operational effects of the first embodiment having the above-described configuration are as follows. FIG. 3 shows the direction of current in the windings 3a, 3b, 4a and 4b in the configuration of FIG. Here, as in FIG. 10, the directions of the currents 6a, 6b, 7a and 7b are represented by white arrows and circled crosses (x) or dots (.), And the leakage magnetic fluxes 8a and 8b are Represented by hatched arrows.

  In the first embodiment, the internal and external positional relationships of the primary windings 4a and 4b and the secondary windings 3a and 3b in the iron core legs 1 and 2 are opposite. Therefore, in the vicinity of the primary winding 4a and the secondary winding 3b located at the outermost periphery when viewed from the iron core legs 1 and 2 where the coils face each other, unlike the conventional example shown in FIG. Is different from the leakage magnetic flux 8b.

  Therefore, the magnetic path lengths of the leakage magnetic fluxes 8a and 8b are the same as those in other places even if the coils face each other, and the magnetic resistance is the same. As a result, as shown in FIG. 4, the magnetic resistance is uniform over the entire circumference of the windings 3 a, 3 b, 4 a, 4 b, and the leakage flux 8 a, 8 b becomes the windings 3 a, 3 b, 4 a, 4b is distributed evenly in the circumferential direction.

  That is, in the first embodiment, the axial magnetic flux density can be equalized in the circumferential direction of the windings 3a, 3b, 4a, 4b, and the inner radial direction generated in the windings 3a, 3b, 4a, 4b. The electromagnetic force and the outer radial electromagnetic force are equal. Therefore, there is no concern that the mechanical force acting on the windings 3a, 3b, 4a, 4b deforms the windings 3a, 3b, 4a, 4b.

  In particular, the primary winding 4a located on the outer peripheral side of the iron core leg 1 and the secondary winding 3b located on the outer peripheral side of the iron core leg 2 are caused by the tensile stress generated in the conductors of the respective windings 4a and 3a by the outer radial electromagnetic force. However, since the electromagnetic force is generated uniformly, there is no possibility that the windings 4a and 3a are deformed from the circular state. As described above, according to the first embodiment, even if a short circuit occurs on the secondary side of the transformer, the deformation of the windings 3a, 3b, 4a, and 4b can be reliably prevented, and the short circuit resistant machine Power can be improved and high reliability can be obtained.

(2) Second Embodiment [Configuration]
Next, a second embodiment of the single-phase transformer according to the present invention will be specifically described with reference to FIGS. FIG. 5 is a cross-sectional view of the iron core and windings showing the second embodiment, FIG. 6 is a cross-sectional view showing the direction of current in the second embodiment, and FIG. 7 is a circumferential direction of leakage magnetic flux in the second embodiment. It is a top view which shows distribution. In addition, the same code | symbol is attached | subjected about the member same as the member shown in FIGS. 1-4 and FIGS. 8-11.

  In the second embodiment, the primary windings 4a, 4b or the secondary windings 3a, 3b or both windings 3a, 3b, 4a, 4b are divided into two or more, and the divided windings 3a, 3b, 4a, 4b is comprised so that it may wind alternately from the inner peripheral side of the iron core legs 1 and 2 to the outer peripheral side.

  In the example shown in FIG. 5, the secondary winding 3 a of the first core leg 1 and the primary winding 4 b of the second core leg 2 are divided into two parts. In the first core leg 1, the secondary winding 3a, the primary winding 4a, and the secondary winding 3a are wound in this order from the inner peripheral side to the outer peripheral side. In the second core leg 2, the primary winding 4b, the secondary winding 3b, and the primary winding 4b are wound in this order from the inner peripheral side to the outer peripheral side.

[Function and effect]
In the second embodiment having the above configuration, the leakage magnetic fluxes 8a and 8b are as shown in FIG. 6 in the vicinity of the secondary winding 3a and the primary winding 4b located on the outermost periphery when viewed from the core legs 1 and 2. And the circumferential distribution of the leakage magnetic fluxes 8a and 8b is equalized (see FIG. 7). For this reason, in the single phase transformer comprised from the divided | segmented coil | winding, the effect similar to the said 1st Embodiment can be acquired.

(3) Other Embodiments The present invention is not limited to the above embodiments, and the shape and the like of each member can be changed as appropriate. For example, the present invention can be applied to a single-turn transformer having a series winding and a shunt winding.

  That is, the series winding that is not the common part of the primary winding and the secondary winding is wound on the outer peripheral side in one iron core leg and on the inner peripheral side in the other iron core leg. Further, the shunt winding, which is a common part of the primary winding and the secondary winding, is wound on the inner peripheral side of one iron core leg and on the outer peripheral side of the other iron core leg. Furthermore, the directions of the main magnetic fluxes in the two iron core legs are opposite to each other. In such an embodiment, the same effect as that of the first embodiment can be obtained in the auto-transformer suitable as the transformer in the feeder system.

  Furthermore, as a modification of the embodiment of the single-winding transformer, the series winding or the shunt winding or both windings are divided into two or more, and each divided winding is alternately turned from the inside to the outside of the core leg. It may be wound. Note that the number of winding divisions can be changed as appropriate, and the division target may be only the primary winding or the secondary winding, or both may be divided.

DESCRIPTION OF SYMBOLS 1 ... 1st iron core leg 2 ... 2nd iron core leg 3a, 3b ... Secondary winding 4a, 4b ... Primary winding 5a, 5b ... Main magnetic flux 6a, 6b ... Secondary current 7a, 7b ... Primary current 8a, 8b ... Leakage magnetic flux

Claims (4)

Two iron core legs are arranged opposite to each other, and are connected by upper and lower yoke portions of the iron core legs, and a primary winding and a secondary winding are concentrically wound around each iron core leg. And a single-phase transformer with secondary windings connected in parallel or in series,
On one of the iron core legs, the primary winding is wound on the outer peripheral side, and the secondary winding is wound on the inner peripheral side,
On the other iron core leg, the primary winding is wound on the inner peripheral side, and the secondary winding is wound on the outer peripheral side, respectively.
Further, Ri Do in directions opposite to each other of the main magnetic flux formed in two of the core legs,
A single-phase transformer configured such that directions of currents flowing through the primary winding on the outer peripheral side and the secondary winding on the outer peripheral side are opposite to each other .   2. The single-phase transformer according to claim 1, wherein the primary winding is a series winding and the secondary winding is a shunt winding to form a single-winding transformer. Dividing the primary winding or the secondary winding or both into two or more;
The single-phase transformer according to claim 1 or 2, wherein the divided windings are alternately wound from the inside to the outside of the iron core leg.   A power distribution system using the single-phase transformer according to any one of claims 1 to 3.

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