JP2008187015A - High voltage resin mold transformer - Google Patents

Abstract

A high voltage is not applied between an outer surface of a resin mold coil and an iron core to prevent partial discharge and to ensure a long life of a transformer.
A resin-molded coil including an iron core and a primary coil and a secondary coil wound around the iron core and integrally resin-molded with the iron core, wherein the primary coil having a low voltage is wound inside. A secondary coil having a high voltage is wound around the outer periphery of the primary coil via a resin insulating layer, and further, a ground potential means is provided on at least one of the outer periphery and both end surfaces of the secondary coil via the resin insulating layer. A high-voltage resin-molded transformer that is grounded. As this potential grounding means, there is a shield pseudo coil which is resin-molded together with the primary coil and the secondary coil, or a shield coating layer formed on the outer surface of the molded coil.
[Selection] Figure 1

Description

  The present invention relates to a resin molded transformer in which a winding is embedded in a resin, and more particularly to a high voltage resin molded transformer that insulates a high voltage of 1000 V or more between a primary coil and a secondary coil.

  Since the conventional high-voltage resin mold transformer has a working voltage of less than 1000 volts, partial discharge does not occur, and examination from the viewpoint of electrical insulation is unnecessary. For this reason, even a structure in which a film of an insulating material is simply wound between the primary coil and the secondary coil is sufficiently effective as insulation.

  However, a transformer in which a high voltage exceeding 1000 volts is applied to the primary coil and the secondary coil is required. If the voltage exceeds 1000 volts, the insulation between the primary coil and the secondary coil will not be obtained if only the film material is insulated, and a resin mold embedded in the resin including the primary coil, the secondary coil, and the film between them is required. Became. The primary coil, the secondary coil, and a spacer that maintains an insulation distance such as a film that insulates them together are resin-molded, so that sufficient insulation performance can be maintained up to insulation of about 2000 volts. With respect to these, Patent Document 1 and Patent Document 2 are detailed.

Japanese Patent Laid-Open No. 06-196336 JP-A-10-172833

  The need to insulate voltages exceeding 3000 volts between the primary and secondary coils has begun. However, increasing the insulation distance between the primary coil and the secondary coil increases the dimensions of the transformer, which is not preferable as a product. Therefore, a voltage exceeding 3000 volts must be endured between the primary coil and the secondary coil without making the shape so large. A cross-sectional view of a conventional high voltage resin mold transformer is shown in FIG.

  In the high voltage resin molded transformer, the primary coil 2 and the secondary coil 3 are separately resin-molded, and the primary coil 2 and the secondary coil 3 having a wide width are formed between the resin-molded primary coil 2 and the secondary coil 3. There is an air layer 4 of thickness d1. There is also an iron core between the resin-molded secondary coil 3 and the iron core 1-an air layer 5 having a thickness d2 between the side surfaces of the secondary coil, and an iron core between the end surface of the secondary coil 3 and the iron core 1- There is an air layer 6 of thickness d3 on the end face of the secondary coil. These air layers are mainly responsible for high voltage insulation. Therefore, these air layers are manufactured so as to have an electric field lower than 3 kV / mm, which is a breakdown electric field of air. As a result, the shape of the high voltage resin mold transformer is increased.

  Therefore, it is conceivable that the primary coil 2 and the secondary coil 3 are integrally resin-molded. In this case, since the primary coil and the secondary coil are insulated by the mold resin, a high electric field value is allowed. For example, the electric field can be increased to a high electric field value of about 15 kV / mm. Can do. However, a large air layer d2 is similarly required between the outer surface of the mold resin that covers the secondary coil 3 on the outer peripheral side and the iron core 1. Therefore, a high withstand voltage cannot be realized only by the conventional resin mold.

  An object of the present invention is to realize a withstand voltage performance of 3000 volts or more with a small transformer in which a primary coil 2 and a secondary coil 3 which are not realized in the prior art are integrally resin-molded.

  According to the present invention, an iron core, a primary coil wound around the iron core, and including a primary coil and a secondary coil integrally molded with the iron core and having a low voltage are wound inside, and the primary coil A secondary coil having a high voltage is wound around the outer periphery via a resin insulating layer, and a ground potential means is grounded via the resin insulating layer on at least one of the outer periphery and both end surfaces of the secondary coil. A high voltage resin molded transformer is provided.

  According to the present invention, long-term reliability can be maintained without causing partial discharge in the high-voltage resin mold transformer, and long-term operation is possible. In addition, since the transformer can be used up to a high voltage with the same size as the transformer of the prior art, the transformer can be miniaturized.

In the high voltage resin mold transformer according to the present invention, it is preferable that an air layer is not substantially present in a region where the primary coil, the secondary coil, and the ground potential means face each other. Further, an example of the means for providing the ground potential is an outer peripheral shield pseudo coil connected to the ground potential at one end of the secondary coil through the resin insulating layer. In this case, it is desirable that the length (l ₁ ) in the axial direction of the winding core of the secondary coil is 50% or less of the length (L) of the resin insulating layer between the primary coil and the secondary coil.

Another example of the means for providing the ground potential is an end-side shield pseudo coil connected to the ground potential at one end of the secondary coil through the resin insulating layer. Moreover, the means to be the ground potential can be an end-side shield pseudo coil connected to the ground potential at both ends of the secondary coil via the resin insulating layer. The length (l ₂ ) in the axial direction of the winding core of the secondary coil is desirably 50% or more of the length (L) of the resin insulating layer between the primary coil and the secondary coil.

  When the number of turns of the secondary coil is large, it is preferable that the means to be the ground potential is both the outer peripheral shield pseudo coil and the end shield pseudo coil. Thereby, the electric potential in the edge part of a temporary and a secondary coil can be relieve | moderated.

  As still another example of the means for providing the ground potential, a shield comprising a conductive paint layer formed on a portion of the resin outer surface of the resin mold coil facing the core and a semiconductive paint layer formed on both sides thereof. It is the formation of a paint layer. The semiconductive paint layer acts to relax the electrolysis at the end of the conductive paint layer.

  Thus, the present invention includes an iron core, a primary coil and a secondary coil wound around the iron core and integrally molded with the iron core, and the primary coil having a low voltage is wound inside, and the primary coil A secondary coil having a high voltage is wound around the outer periphery of the secondary coil, and at least one of the outer periphery and both end surface portions of the secondary coil is a conductive paint that has a ground potential via the resin insulating layer, and The present invention provides a high voltage resin mold transformer characterized in that a semiconductive paint formed on the outside thereof is formed. It is desirable that an air layer is not substantially present in a region where the primary coil, the secondary coil, and the ground potential means are opposed to each other.

  In order to realize a high voltage resin molded transformer with a small size, a structure in which all high voltages are insulated with resin may be used. It can be realized by molding the primary coil and the secondary coil integrally with resin. The remaining locations are (1) between the outer peripheral surface of the integrated coil and the iron core, and (2) between the iron core and the end surface of the integrated coil. If the insulation of these portions is applied to the mold resin, the allowable electric field value is high, so that the size can be considerably reduced. In order to bear the voltage at the mold resin part, if a low voltage or ground potential shield is placed outside the secondary coil that becomes a high voltage, and the resin is molded together with the shield, the voltage is borne by the mold resin part. Since it can be used in a high electric field up to the allowable electric field of the mold resin, the insulation distance can be shortened, and a small high-voltage resin mold transformer can be obtained.

FIG. 1 shows a partial cross-sectional front view of the high-voltage resin mold transformer according to the first embodiment of the present invention, and FIG. 2 shows a perspective view thereof. On the outer periphery of the primary coil 1 and the secondary coil 3 integrally molded with resin, an outer peripheral shield pseudo coil 8 grounded at one end is equal to the thickness of the molded resin layer between the primary coil 2 and the secondary coil 3 (d4 = d5) A mold resin layer 7 is provided between the secondary coil and the secondary coil. By doing in this way, it becomes the structure which bears equally the high voltage applied to the space between the secondary coil 3 and the iron core 1 with the mold resin 7 between the secondary coil 3 and the outer periphery shield pseudo-coil 8. Unlike the primary coil 2, the secondary coil 3 is wound around the central portion in the axial direction of the coil. This is to prevent voltage from being applied to the end face of the insulating resin layer. That is, in the case of the transformer shown in FIGS. 1 and 2, the axial length (l ₁ ) of the secondary coil is preferably 50% or less of the length (L) of the primary coil.

  At both ends of the outer peripheral shield pseudo coil 8, one end is connected to the ground potential, but the other end is in an open state because an induced potential is generated. FIG. 7 shows an example of electric field analysis of a conventional high voltage resin mold transformer. An equipotential line 9 is shown for every 5% of the potential difference when the outer peripheral frame is inside the iron core 1 and the low voltage primary coil 2 is set to 0% potential and the high voltage secondary coil 3 is set to 100% potential. is there. The portion of the mold resin 7 that wraps the primary coil 2 and the secondary coil 3 has a larger dielectric constant than the air layer 5, so that the shared voltage is so small that most of the voltage is applied to the air layer 5. In such a state, since the electric field of the air layer 5 exceeds 3 kV / mm, a partial discharge occurs, the mold resin layer gradually deteriorates due to the discharge, and finally dielectric breakdown occurs.

  On the other hand, FIG. 3 shows the electric field analysis result of the high voltage resin mold transformer according to the present invention. The size of the iron core 1 is the same as that of the conventional high voltage resin mold transformer shown in FIG. An outer peripheral shield coil 8 is disposed on the outer periphery of the primary coil 2 and the secondary coil 3, and these are included in a mold resin 7 for molding them integrally. As a result, the equipotential line 9 does not jump out to the air layer 5, and the air layer 5 does not share the voltage. Therefore, partial discharge does not occur in the air layer 5.

  FIG. 4 shows a partial cross-sectional front view of a high-voltage resin mold transformer according to a second embodiment of the present invention. When the winding amount of the secondary coil 3 is large, a wide coil is formed. In this case, the end face shield pseudo coil 10 is wound around the end face side of the secondary coil 3 and only one end thereof is grounded. The other end is not connected and is open. By setting the insulation length of the mold resin layer between the secondary coil 3 and the end face shield pseudo coil 10 to be equal to or greater than the insulation thickness of the primary coil 2 and the secondary coil 3, the insulation reliability is remarkably improved.

  The outer peripheral shield pseudo-coil 8 and the end shield pseudo-coil 10 are electrically connected to the iron core 1 by, for example, the lead wire 14 of FIG. 2 so that one end thereof is at the ground potential, and the other end is open. Therefore, the shield coil is described as a pseudo coil because it is structurally configured like a coil but does not have a function as a coil.

FIG. 5 is a perspective view of a high voltage resin mold transformer according to a third embodiment of the present invention. The end face and outer peripheral part of the mold coil 13 facing the iron core of the resin mold part are roughened by sandblasting or polishing paper or the like to have a width (l3) or more of the iron core 1, and the electric resistance value is 1 to 10 ⁸ Ω · m. A certain conductive paint 11 is applied, and a semiconductive paint 12 having an electric resistance value of 10 ⁶ to 10 ¹² Ω · m is applied to both ends thereof. By doing in this way, the effect similar to winding a shield pseudo coil is acquired, and a partial discharge etc. are not caused between a resin mold coil and an iron core. In this embodiment, since the treatment can be performed on the outer surface of the mold resin, the treatment is easy. However, since the mold release agent remains on the surface of the mold resin during production, it is important to remove the release agent and further polish the coated surface with sandblast or polishing powder in order to increase the adhesion of the paint.

  In the first embodiment, a high voltage applied to the secondary coil can be obtained by winding an outer peripheral surface coil, an end face shield pseudo coil, etc. around a high voltage resin mold transformer and connecting one end of each coil to the ground potential. Since no voltage is applied to the air layer on the outside of the iron core and the resin mold coil, and thus partial discharge does not occur, long-term reliability can be maintained and long-term operation is possible. Further, by winding these shield pseudo-coils, it is possible to use a high voltage with the same size as the transformer of the prior art, so that the transformer can be miniaturized.

  In the high-voltage resin mold transformer according to another embodiment, by applying a conductive paint that becomes a ground potential to the surface of the mold resin that faces the core more than the width of the core, it is equivalent to the case where the shield pseudo coil is embedded. An effect is obtained.

  According to the embodiment described above, the space between the iron core 1 and the coil can be zero or infinitely zero. Therefore, in the prior art, the air layers 5 and 6 that require about 20 mm can be reduced by about 40 mm in the horizontal and vertical dimensions, respectively. Therefore, the volume can be made smaller than the conventional one by the third power.

1 is a partial cross-sectional view of a high voltage resin molded transformer according to a first embodiment of the present invention. 1 is a perspective view of a high voltage resin mold transformer according to an embodiment of the present invention. The equipotential line distribution map of the high voltage mold transformer which becomes 1st Example of this invention. The partial sectional view of the high voltage mold transformer which becomes the 2nd example of the present invention. The front view of the high voltage mold transformer which becomes the 3rd Example of this invention. The front view which shows the high voltage molded transformer used as a prior art. The equipotential line distribution map of the high voltage mold transformer used as the 1st prior art.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Iron core, 2 ... Primary coil, 3 ... Secondary coil, 4 ... Primary coil-secondary coil air layer, 5 ... Secondary coil-iron outer peripheral air layer, 6 ... Secondary coil- iron core end surface air layer, 7 ... Mold Resin layer, 8... Outer side shield pseudo coil, 9... Equipotential line, 10... End face side shield pseudo coil, 11.

Claims (9)

  An iron core, and a primary coil and a secondary coil that are wound around the iron core and integrally molded with the iron core, and a primary coil having a low voltage are wound inside, and a resin insulating layer is formed on the outer periphery of the primary coil A secondary coil that is at a high voltage is wound around the secondary coil, and ground potential means is provided on at least one of the outer periphery and both end surface portions of the secondary coil via the resin insulating layer, and the ground potential means is grounded. High voltage resin mold transformer characterized by   2. The high voltage resin mold transformer according to claim 1, wherein an air layer is substantially absent in a region where the primary coil, the secondary coil and the ground potential means are opposed to each other.   3. The high-voltage resin according to claim 1, wherein the ground potential means is a peripheral shield pseudo coil connected to the ground potential at one end of the secondary coil via the resin insulating layer. Mold transformer.   4. The resin insulation layer between the primary coil and the secondary coil and the resin insulation layer between the secondary coil and the outer shield pseudo coil are substantially equal in thickness. The high voltage resin mold transformer described in 1.   The length in the axial direction of the winding core of the secondary coil is 50% or less of the length of the resin insulation layer between the primary coil and the secondary coil. The high voltage resin mold transformer described in 1.   3. The high voltage according to claim 1, wherein the means that becomes the ground potential is an end-side shield pseudo coil that is connected to the ground potential at one end of the secondary coil through the resin insulating layer. Resin mold transformer.   The length in the axial direction of the winding core of the secondary coil is 50% or more of the length of the resin insulating layer in the axial direction between the primary coil and the secondary coil. Voltage resin mold transformer.   An iron core, and a primary coil and a secondary coil that are wound around the iron core and integrally molded with the iron core, and a primary coil having a low voltage are wound inside, and a resin insulating layer is formed on the outer periphery of the primary coil A secondary coil that is at a high voltage is wound around the outer periphery of the secondary coil, and at least one of the end surface portions of the secondary coil is formed on the conductive paint layer and outside thereof as a ground potential means via the resin insulating layer. A high-voltage resin mold transformer characterized in that a shield coating layer made of a semiconductive paint layer is formed.   9. The high voltage resin molded transformer according to claim 8, wherein there is substantially no air layer in each region where the primary coil, the secondary coil, and the shield coating layer face each other.

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