JP2016072315A - Transformer structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce AC resistance, while suppressing increase in size of a transformer.SOLUTION: A transformer structure includes an upper core 200A, a lower core, a winding frame, a planar winding constituting a primary winding 202 wound around the core, and a secondary winding wound around the core. The planar winding has a first conductor 255, the perpendicular direction of the principal surface of which is in parallel with the scroll of the secondary winding, and a second conductor 256 connected with the first conductor and provided on the inner peripheral side of the planar winding. The second conductor 256 is thicker than the first conductor 255 in the scroll direction of the secondary winding.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a transformer structure, and more particularly to a transformer structure used in a DCDC converter used in an electric vehicle or a plug-in hybrid vehicle.

  As a configuration method in the case of a transformer having a large secondary winding current, it is known to use a plate-like winding having a large current capacity as disclosed in Japanese Patent Application Laid-Open No. 2002-237416. In that case, due to the ease of drawing out the winding and the physical dimension restrictions as a transformer, the main surface of the flat plate-like winding is often arranged so as to face in a substantially vertical direction with respect to the winding axis. In this method, it is necessary to increase the cross-sectional area of the plate winding in order to reduce the conductor resistance when suppressing the heat generation of the transformer to expand the operating temperature range of the transformer or further increasing the current capacity. Become. However, increasing the winding volume will inevitably affect the transformer outer shape. If the conductor thickness is increased, the height must be increased, and if the conductor width is increased, the width must be increased. I don't get it.

  The current flowing through the winding is an alternating current and is affected by the skin effect. Since the inner diameter of the flat plate winding is different from the outer diameter of the outer periphery, the distance on the inner diameter side of the winding is different from the distance on the outer diameter side of the winding. Due to this, the current distribution in the winding of the alternating current flowing through the conductor surface layer is not necessarily uniform on the inner diameter side of the winding and the outer diameter side of the winding. Is low, a large amount of current flows, and there is a tendency that the AC resistance is high and the current is small on the outer peripheral side having a long distance.

  When this current distribution is taken into account and the cross-sectional area is increased, it is effective to increase the surface area on the inner peripheral side, that is, it is necessary to cope with the direction of increasing the conductor thickness. It will increase.

JP 2002-237416 A

  The subject of this invention is aiming at reduction of alternating current resistance, suppressing the enlargement of a transformer.

  In order to solve the above-mentioned problems, a transformer structure according to the present invention comprises a plate, a core, a winding frame, a primary winding that winds the core, and a secondary winding that winds the core. The plate-like winding includes a first conductor portion whose main surface is perpendicular to the winding axis of the secondary-side winding, and the plate-like winding connected to the first conductor portion. A second conductor portion provided on the inner peripheral side of the second conductor portion, and the second conductor portion is thicker than the first conductor portion in the winding axis direction of the secondary winding.

  Thereby, it becomes possible to enlarge the surface area of the inner peripheral side where AC resistance is low, and AC resistance can be effectively reduced. By adding the second conductor portion, it is possible to increase the cross-sectional area of the plate winding while effectively reducing the plate winding AC resistance. The conductor loss of the winding can be reduced and heat generation can be suppressed. Alternatively, by adding the second conductor portion, in the cross-sectional area of the plate-shaped winding, the amount of increase in the second conductor portion provided on the inner peripheral portion can be subtracted from the outer peripheral portion direction. Since the width of the first conductor portion main surface can be reduced while maintaining the cross-sectional area, the outer shape of the transformer can be reduced.

  According to the present invention, the AC resistance can be reduced while suppressing an increase in size of the transformer.

It is a development perspective view of the transformer concerning this embodiment. The upper side is a top view of the transformer 100, and the lower side is a cross-sectional view seen from the direction of the arrow of the cross section AA. It is an expanded sectional view of the part B of FIG. It is an alternating current distribution figure at the time of using a flat copper plate for a secondary winding. It is an alternating current distribution diagram at the time of using the secondary winding 201 concerning this embodiment. It is the trans | transformer 101 which concerns on other embodiment, Comprising: The upper side is a top view of the trans | transformer 101, and the lower side is sectional drawing seen from the arrow direction of the cross section AA. It is an expanded sectional view of the part B of FIG. FIG. 10 is a cross-sectional view of the vicinity of a second conductor portion 258, which is a transformer 102 according to another embodiment. FIG. 6 is a developed perspective view of a transformer 103 according to another embodiment. 6 is an enlarged cross-sectional view of the vicinity of a second conductor portion 256 and a second conductor portion 356. FIG.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

  FIG. 1 is an exploded perspective view of a transformer 100 according to the present embodiment. In FIG. 2, the upper side is a top view of the transformer 100, and the lower side is a cross-sectional view seen from the direction of the arrow of the cross section AA. 3 is an enlarged cross-sectional view of a portion B in FIG.

  The core includes an upper core 200A and a lower core 200B. In the upper core 200A and the lower core 200B, a cylindrical magnetic leg 250A and a cylindrical magnetic leg 250B are respectively arranged in the center, and two magnetic legs 251A, 252A, a magnetic leg 251B, and a magnetic leg 252B are provided on both sides thereof. PQ type core.

The secondary winding 201 is composed of a flat conductor, and in this embodiment is composed of one turn. Since both ends of the secondary winding 201 are connected to the circuit, one end 253 of the annular winding portion 255 and the other end 254 of the annular winding portion 255 extend outward from the center of the transformer 100. It is bent and pulled out by the same member as the winding part 255.
The secondary winding 201 is arranged so that the vertical direction P of the main surface of the winding portion 255 is parallel to the winding axis direction W in order to suppress the height of the transformer 100.

  Winding portion 255 is defined as the first conductor portion. A second conductor portion 256 bent in a direction substantially parallel to the winding axis direction W is provided on the inner peripheral portion of the first conductor portion (winding portion 255). The second conductor portion 256 has a cylindrical shape extending in a direction substantially parallel to the winding axis direction W. Thus, in the winding axis direction W, the second conductor portion 256 is formed larger than the first conductor portion (winding portion 255). In other words, a large thickness is formed at the inner periphery of the secondary winding 201.

  The primary winding 202 has the same winding axis as the secondary winding 201 and is wound around the bobbin 203. The bobbin 203 is provided to ensure insulation between the upper core 200A and the lower core 200B, the primary winding 202 and the secondary winding 201, and further to ensure insulation between the primary winding 202 and the secondary winding 201. Further, the bobbin 203 is provided with an uneven portion for fixing the secondary winding 201.

  The background of this embodiment and the operation of the first conductor portion (winding portion 255) and the second conductor portion 256 according to this embodiment will be described below.

  The transformer 100 has a core loss (iron loss) that is a magnetic loss and a conduction loss (copper loss) of the winding conductor as inevitable losses due to its configuration, and most of them are converted into heat. The This embodiment focuses on the effect of reducing the copper loss of the latter. In particular, by reducing the conductor loss of the secondary winding 201, the heat generation is suppressed and the size is reduced, and the power density per volume is reduced. The purpose is to raise.

  As the secondary winding 201, as a means for effectively reducing the copper loss, a method using a plate-like winding is adopted. Specifically, it is a flat copper plate, etc., which saves space, makes it easy to secure the required cross-sectional area according to the winding current, and facilitates the winding work, and also facilitates workability by pressing. This is because there are several advantages.

  However, when an alternating current passes through the secondary winding 201 during operation, the alternating current is concentrated on the surface of the conductor due to the skin effect. Therefore, when a single flat copper plate is used, the conductor loss tends to increase. In addition, a flat copper plate inevitably has a difference in conduction distance between the inner and outer circumferences of the winding, and as a result, the AC resistance is low on the inner circumference and high on the outer circumference.

  FIG. 4 is an AC current distribution diagram when a flat copper plate is used for the secondary winding. As shown in FIG. 4, it is clear that the alternating current is large on the inner peripheral side and small on the outer peripheral side. In order to effectively reduce the copper loss as the secondary winding, it can be said that it is effective to increase the cross-sectional area on the inner peripheral side and enlarge the surface area.

  The simplest method for realizing this is to increase the thickness of the entire flat copper plate and increase the surface area on the inner peripheral side while increasing the cross-sectional area. The outer peripheral side where the AC resistance is large is also thick and not efficient, leading to an increase in the overall height of the transformer, and causes problems such as an increase in cost and a decrease in workability.

  Therefore, in the present embodiment, the plate-like winding as the secondary winding 201 has a first conductor portion (winding portion 255) and a second conductor portion 256, and the first conductor portion is perpendicular to the main surface thereof. Is arranged in parallel with the winding axis direction W of the secondary winding 201. Furthermore, the 2nd conductor part 256 is comprised so that it may connect with a 1st conductor part in the inner peripheral side with large alternating current distribution of a plate-shaped 1st conductor part. The second conductor portion 256 is configured to be thicker than the first conductor portion in the winding axis direction.

  By configuring in this way, it is possible to effectively increase the surface area only on the inner peripheral side where the AC resistance is small, without changing the thickness, on the outer peripheral side where the AC resistance is large. Therefore, the conduction loss (copper loss) of the secondary winding 201 can be reduced.

With this action, the following effects can be expected.
One of the effects is an effect that heat generation of the transformer 100 can be suppressed. FIG. 5 is an AC current distribution diagram when the secondary winding 201 according to the present embodiment is used. In the example in which the thickness on the inner circumference side of the winding is increased without changing the outer circumference diameter of the annular ring, the increase in the inner circumferential surface area and the increase in the cross-sectional area of the annular winding portion can be achieved simultaneously. For this reason, the conductor loss can be further reduced than in the case of FIG.
The second conductor portion 256 extends in a direction parallel to the winding axis direction W and is formed on the side close to the center of the transformer 100, so that it can be realized without affecting the height of the transformer 100. That is, when the annular outer peripheral diameter of the annular winding portion 255 is not changed, the conductor loss can be reduced while maintaining the outer shape of the transformer 100, so that the heat generation of the transformer 100 can be reduced. .

  Another effect is that the transformer 100 can be miniaturized. As shown in FIG. 5, even if the cross-sectional area of the winding portion 255 is the same, the decrease in the AC resistance exceeds the decrease in the DC resistance and effectively decreases, so that the outer diameter of the ring can be reduced. The width of the main surface of the line can be reduced. That is, even if the outer diameter of the annular winding portion (that is, the outer shape of the secondary winding 201) is reduced, the conductor resistance can be reduced, so that the outer shape of the transformer can be reduced as shown in FIG.

If the second conductor portion 256 is processed into a cylindrical shape as in the present embodiment, an extra punched portion on the inner circumferential side of the winding may be secured and formed by pressing and drawing. Therefore, the material and construction cost burden can be reduced simply by reducing the number of punched parts. Of course, different processing methods may be used as long as the same shape can be realized.
FIG. 6 is a transformer 101 according to another embodiment, in which the upper side is a top view of the transformer 101 and the lower side is a sectional view as seen from the direction of the arrow of the section AA. 7 is an enlarged cross-sectional view of a portion B in FIG.

  In the present embodiment, the extending direction of the inner peripheral side portion of the winding portion 255 is extended toward the outer shape side of the transformer 101. That is, the second conductor portion 257 is a case where the extending direction is extended toward the outer shape side of the transformer 101. In this case also, the effect of reducing the conductor loss can be obtained and heat generation can be suppressed.

  FIG. 8 is a cross-sectional view of the transformer 102 according to another embodiment and in the vicinity of the second conductor portion 258. In the present embodiment, the second conductor portion 258 includes a protruding portion 258A that protrudes upward from the upper surface of the winding portion 255 and a protruding portion 258B that protrudes downward from the lower surface of the winding portion 255. Thereby, it is set as the structure where thickness is large in the inner peripheral part of a plate-shaped winding, conductor loss can be reduced, and heat generation can be suppressed.

  FIG. 9 is an exploded perspective view of a transformer 102 according to another embodiment. FIG. 10 is an enlarged cross-sectional view of the vicinity of the second conductor portion 256 and the second conductor portion 356.

  A difference from the previous embodiments is that a winding 355 is provided. Winding 355 is arranged opposite to winding 255 with primary winding 202 interposed therebetween. The winding part 355 is arranged so that the vertical direction of the main surface thereof is parallel to the winding axis direction W of the winding 355. Further, the second conductor portion 356 is configured to be connected to the winding 355 on the inner peripheral side where the AC current distribution of the plate-like winding 355 is large. The second conductor portion 356 is configured to be thicker than the winding 355 in the winding axis direction. The direction in which the thickness of the second conductor portion 356 increases is the opposite direction to the second conductor portion 256 in the winding axis direction W.

With the configuration of this embodiment, without increasing the height of the transformer 102, the cross-sectional area and the conductor surface area on the inner peripheral side, which are means for reducing the copper loss of the secondary winding 255 and the winding 355, are increased. And the amount can be approximately equal for both windings. That is, approximately the same amount of conductor resistance can be reduced by both windings, and conductor loss can be reduced.
In addition, when the extension of the cylindrical portion that is the second conductor portion 356 is extended toward the outer side of the transformer, the height of the transformer 102 may increase, and the extension length is restricted from the outer shape of the transformer 102. Although the degree of freedom is reduced, the effect of reducing the heat generated by the transformer 102 can be obtained because the effect of reducing the conductor loss can be secured.

  In addition, if the cylindrical part which is the 2nd conductor part 356 is a method in an Example, if the punching part by the side of a coil inner periphery is ensured and it forms by press work and drawing processing, Since it is good, only the number of punched parts is reduced, and the material / construction cost burden can be reduced. Of course, different processing methods can be used as long as the same shape can be realized.

DESCRIPTION OF SYMBOLS 100 ... Transformer, 101 ... Transformer, 102 ... Transformer, 200A ... Upper core, 200B ... Lower core, 201 ... Secondary winding, 202 ... Primary winding, 203 ... Bobbin, 250A ... Cylindrical magnetic leg, 250B ... Cylindrical magnetic Leg, 251A ... Magnetic leg, 251B ... Magnetic leg, 252A ... Magnetic leg, 252B ... Magnetic leg, 253 ... One end, 254 ... Other end, 255 ... Winding part, 256 ... Second conductor part, 257 ... Second conductor part 258A ... Projection, 258B ... Projection, 355 ... Winding

Claims (2)

The core,
With bobbin,
A primary winding for winding the core;
A plate-like winding constituting a secondary winding that winds the core, and
The plate-like winding is provided on the inner peripheral side of the plate-like winding connected to the first conductor portion in which the vertical direction of the main surface is parallel to the winding axis of the secondary-side winding. A second conductor portion,
The second conductor portion is a transformer structure having a thickness larger than that of the first conductor portion in the winding axis direction of the secondary winding. The transformer structure according to claim 1,
The plate-like winding is provided with two first conductor portions so as to sandwich the primary winding,
Each of the first conductor parts is a transformer structure connected to the second conductor part.