JP5824001B2 - Trance - Google Patents

Description

  The present invention relates to a transformer in which a primary winding and a secondary winding are wound around a core.

In power converters such as DCDC converters and chargers mounted on electric vehicles and hybrid vehicles, switching power supply circuits are used due to the downsizing of devices. However, switching loss is reduced and EMC (Electro-Magnetic) From the viewpoint of compatibility, a soft switching method is effective in which a pseudo-resonance phenomenon is generated using a capacitor and an inductor, and a switching operation is performed at a point where the voltage or current becomes zero.
In such a soft switching system, there has been proposed a composite transformer that allows the transformer to function as a primary-side resonance inductor, thereby reducing the size and weight of the equipment and reducing the cost associated with reducing the number of parts. Yes.

  As the transformer, the primary side and the secondary side of the transformer are divided into winding parts, and the first primary winding, the second primary winding, and the secondary winding are covered with a central magnetic leg such as an EE core. By mounting on the bobbin and providing a gap in the central magnetic leg of the core, a loose coupling with a coupling coefficient of 0.73 is realized, and a leakage inductance necessary as a resonant circuit inductor on the primary side and secondary side is obtained. What is generated by a transformer is known (for example, see Patent Document 1).

JP 2009-17714 A

  When the inductor for the resonance circuit is generated by the leakage inductance of the transformer, adopting a structure in which the primary winding and the secondary winding of the transformer are divided by the bobbin can be easily loosely coupled, and the leakage inductance can be generated. Although it is possible, fine adjustment is difficult because the value of leakage inductance becomes discrete.

  In addition, when the coupling coefficient is increased in the split configuration in which the primary winding and the secondary winding are split by the bobbin, the number of splits must be increased, and the number of bobbin rods increases, so that Since the decrease in the winding space factor in the case will be reduced, the size will be increased and the cost will be increased.

Further, when the number of divisions increases, wiring between the bobbins becomes difficult, and a complicated configuration is unavoidable, resulting in deterioration of assembling property and cost increase.
In addition, accumulation of tolerances in the dimensions between the bobbin inner ribs may cause problems in that it is difficult to manage the dimensions of the transformer shape, and the core size must be increased.

  Further, when the thickness of the bobbin rod is reduced in order to increase the coupling coefficient, there is a concern that the rigidity at the collar portion cannot be ensured and is damaged during assembly.

As a method of actively obtaining the leakage inductance, there is a transformer in which a secondary winding is wound around a bobbin surrounding a core via a primary winding and an insulating tape, in addition to the divided structure in the above publication.
This transformer has a structure that generates a leakage inductance according to the thickness of the insulating tape, but the variation in the leakage inductance increases due to the variation in the insulating tape thickness due to the tension variation in the insulating tape. There is.

In addition, when a large leakage inductance is generated, it is necessary to increase the separation distance between the primary winding and the secondary winding. As a result, the thickness of the insulating tape is increased or the number of turns of the insulating tape is increased. It will be necessary.
For this reason, there is a problem that the heat resistance between the insulating tapes increases due to the increase in the thickness of the tape, whereby the heat of the primary winding is trapped, that is, the heat dissipation is deteriorated.

  Also, if an insulating tape with a large dimensional tolerance is laminated together on the primary winding, the dimensional tolerance will accumulate, and when the transformer is actively dissipated, for example, the transformer body is stored in the case and insulated. When filling the conductive resin, the distance from the wall surface of the case is set according to the tolerance variation. As a result, there is a problem that the thickness of the insulating resin is increased and heat dissipation is deteriorated.

  Further, when the number of windings of the insulating tape is increased, deterioration of assembling property and dimensional accuracy and accompanying cost increase can be problems.

In addition to the above, as a method for positively obtaining the leakage inductance, there is a measure for providing a gap in the core central magnetic leg.
However, in this case, there is a problem that the excitation inductance in the primary winding and the secondary winding is reduced, the primary winding current value is increased, and the amount of heat generation is increased.
In addition, when the gap is obtained with a sheet or the like, the problem of cost increase arises because gap management is required.

  It is an object of the present invention to solve such a problem, and it is easy to finely adjust the leakage inductance, to suppress the variation, and to reduce the space factor of the winding while suppressing the heat dissipation. The purpose of this is to provide an inexpensive transformer without hindering the reduction in size and weight.

ここで、Ｌleakは、リーケージインダクタンス、μは透磁率、Ｔは前記一次巻線の導線のターン数、δは前記離間距離、Δ１は前記一次巻線の径方向の高さ、Δ２は前記二次巻線の径方向の高さ、ｈは前記ボビンの軸線方向の前記一次巻線の長さ、Ｌは前記一次巻線及び前記二次巻線のそれぞれの周長を加えた値を２で割った長さ、qは対称鎖交数である。 A transformer according to the present invention includes a core, a bobbin provided surrounding the core, an inner winding wound around the bobbin, an insulating member provided surrounding the inner winding, and the insulating member An outer winding wound around the inner winding, a transformer in which the other transforms according to the voltage of one of the inner winding and the outer winding,
The insulating member is Ri Oh rigid spacer for holding a distance between the outer winding and the inner winding,
The inner winding is a primary winding and the outer winding is a secondary winding;
The separation distance is a value obtained by the following equation with respect to the leakage inductance .

Here, Lleak is the leakage inductance, μ is the magnetic permeability, T is the number of turns of the conducting wire of the primary winding, δ is the separation distance, Δ1 is the radial height of the primary winding, and Δ2 is the secondary winding. The height in the radial direction of the winding, h is the length of the primary winding in the axial direction of the bobbin, and L is a value obtained by adding the respective peripheral lengths of the primary winding and the secondary winding divided by 2. Length, q is the number of symmetrical linkages.

  According to the transformer of the present invention, a leakage spacer is used as an insulating member interposed between the inner winding and the outer winding so as to maintain a separation distance between the inner winding and the outer winding. Fine adjustment of the inductance is easy, variation thereof can be suppressed, heat dissipation is ensured while suppressing a decrease in the space factor of the winding, and an inexpensive transformer can be obtained without hindering miniaturization and weight reduction.

It is a front sectional view showing a transformer body of a transformer in Embodiment 1 of this invention. It is a front sectional view showing a transformer body of a transformer in Embodiment 2 of this invention. It is a principal part plane sectional view of the transformer in Embodiment 3 of this invention. It is a principal part plane sectional view which shows the modification of the trans | transformer of Embodiment 3 of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same or equivalent members and parts will be described with the same reference numerals.
Embodiment 1.
1 is a front sectional view showing a transformer body of a transformer according to Embodiment 1 of the present invention.
In this transformer, a transformer main body is placed in a case, and the case is filled with an insulating resin.
The transformer body of the transformer includes a U-shaped core 3 composed of the first core portion 1 and the second core portion 2, a bobbin 5 surrounding each of the pair of pillar portions 4 of the core 3, and each bobbin 5 A primary winding 6 that is an inner winding that surrounds the resin, a resin spacer 7 that is a cylindrical rigid spacer that surrounds each primary winding 5, and a secondary winding that is an outer winding that surrounds each resin spacer 7. 8 and.

The primary winding 6 has a single-layer structure having a specified resistance value, and is configured by winding the outer periphery of the bobbin 5 with a specified number of turns with an enameled wire that is a conducting wire.
The secondary winding 8 has a single-layer structure having a specified resistance value, and is configured by winding the outer periphery of the resin spacer 7 with a specified number of turns with an enameled wire that is a conducting wire.

  With respect to the core 3 according to this embodiment, the magnetic path is formed inside the winding, not the EE type outer iron core that forms the magnetic path outside the winding described in Japanese Patent Laid-Open No. 2009-17714. The inner iron type U core is used.

  The leakage inductance in the transformer of this embodiment is given by the following equation.

  Here, Lleak is the leakage inductance, μ is the magnetic permeability, T is the number of turns of the primary winding 6 (number of turns of the enamel wire), and δ is the separation distance δ (between the primary winding 6 and the secondary winding 8). Distance), Δ1 is the height of the primary winding 6 (the length in the radial direction of the bobbin 5), Δ2 is the height of the secondary winding 8 (the length in the radial direction of the bobbin 5), and h is the winding width (of the bobbin 5 A length of the primary winding 6 in the axial direction), L is an average circumference (a value obtained by adding the circumferences of the primary winding 6 and the secondary winding 8 and divided by 2), and q is a symmetric chain. The number of intersections.

In order to obtain a desired leakage inductance, each parameter of the equation (1) is designed. In the transformer of this embodiment, the separation distance δ is focused.
Other parameters, for example, the number of turns 6 of the primary winding T is the primary side excitation current, the primary side coil heating value, the magnetic flux density, the iron loss, the conversion efficiency, and the winding width h is the size, winding occupation rate, winding heating value , Conversion efficiency, high frequency characteristics, thermal resistance, winding height Δ1, Δ2 is a trade-off relationship between size, winding heat generation, conversion efficiency, and greatly affects the basic performance of transformer, size, and the costs associated with it It is difficult to change because it can affect it.
Further, as can be seen from the above (1), the variation in the separation distance δ is multiplied by μ (T ² L / qh) to be the variation in leakage inductance. Therefore, in order to suppress the variation in leakage inductance, the separation distance The point is how to stabilize δ.

  Thus, in the transformer in which the separation distance δ is secured by the resin spacer 7 while the variation in the dimension of the separation distance δ greatly affects the leakage inductance, the variation in the thickness of the resin spacer 7 can be suppressed, and the leakage inductance can be suppressed. Can be suppressed.

In the transformer of this embodiment, the winding width h is 66 mm (33 mm × 2 legs), the magnetic permeability μ is 4π × 10 ⁻⁷ H / m, the primary winding 6 turns number T is 36, and the primary winding 6 height Δ1. Is 2.4 mm, the secondary winding 8 height Δ2 is 2.3 mm, the average circumference L is 106 mm, the symmetric linkage number q is 1, and the separation distance δ is 1.3 mm, the leakage inductance is 6. 45 μH.
Since the conventional insulating tape has a tolerance of about 20% with respect to the representative thickness, the variation in leakage inductance is about ± 0.70 μH.
On the other hand, in the case of the resin spacer 7 of this embodiment, when it is a PPS molded part, when the thickness of the part is 3 mm or less, the tolerance is ± 0.1 mm, so the variation in leakage inductance is ± 0.00. In this embodiment, the variation can be reduced by about 37%.

  The above is an example, and as the separation distance δ increases, the thickness tolerance as the absolute value of the insulating tape increases. However, since the resin spacer 7 hardly changes, the amount of leakage inductance variation suppression is further increased. .

  Further, the leakage inductance can be finely adjusted by changing the thickness of the resin spacer 7 in the transformer that is relatively tightly coupled by the resin spacer 7.

  Moreover, the area ratio of the primary winding 6 and the secondary winding 8 in the area | region in the bobbin 5 can be enlarged, the fall of a space factor can be suppressed and size reduction of a transformer can be implement | achieved.

  Further, since the winding thickness tolerance can be suppressed by the resin spacer 7, when the heat of the transformer main body is radiated by the insulating resin, the variation of the insulating resin thickness can be suppressed and stable heat dissipation performance can be exhibited. .

  Further, in a transformer having a winding width h of 33 mm and a separation distance δ of 1.3 mm, when the separation distance δ is constituted by a nomex tape (thermal conductivity: 0.12 W / m / K) of a general-purpose insulating tape, the heat The typical value of the resistance is 3.2 K / W, and in the transformer in which the heat generation amount in the primary winding 6 is 12.3 W, about 40 K is provided between the primary winding 6 and the secondary winding 8 in which the insulating tape is interposed. Temperature difference occurs.

  On the other hand, when the resin spacer 7 is used as the separation distance δ and the PPS molded part is used (thermal conductivity: 0.29 W / m / K), the thermal resistance is 1.3 K / W, and the amount of heat generated in the primary winding 6 In the transformer with 12.3 W, the temperature is 16K between the primary winding 6 and the secondary winding 8 with the resin spacer 7 interposed therebetween, and the temperature difference is reduced by 60% compared to the case of using the conventional insulating tape. It becomes possible.

Further, when the thickness of the insulating tape varies by 20%, the variation in the thermal resistance of the insulating tape becomes about ± 0.7 K / W, and a temperature variation of about ± 9 K occurs.
On the other hand, when the separation distance δ is the resin spacer 7, the thickness tolerance of the PPS molded part and the resin spacer 7 is ± 0.1 mm, and even if the thermal conductivity is the same as that of the insulating tape, the thermal resistance variation is ± 0.2 K / W, the temperature The variation can be suppressed to about ± 2.5K.

  The above is an example, and as the separation distance δ increases, the tolerance absolute value of the insulating tape increases, whereas the resin spacer 7 hardly changes, so between the spacers due to variations in thermal resistance. The variation in the temperature difference is further increased, and the heat dissipation performance can be stabilized.

  Moreover, when creating a large inductance, conventionally, the insulating tape had to be wound a plurality of times, but it is only necessary to interpose the resin spacer 7 between the primary winding 6 and the secondary winding 8, Assemblability is improved and costs can be reduced.

  In addition, regarding the complication of the wiring structure, which is a problem in the above-described divided configuration, the use of the resin spacer 7 can simplify the wiring structure, improve the assembling property, and contribute to further cost reduction. Become.

Embodiment 2. FIG.
FIG. 2 is a front sectional view showing a transformer body of the transformer according to the second embodiment of the present invention.
In this embodiment, a rigid spacer composed of a nonmagnetic metal spacer 9 and an insulating tape 10 is used in place of the resin spacer 7 of the first embodiment.
The cylindrical nonmagnetic metal spacer 9 is for generating a leakage inductance, and is formed with slits extending in the entire axial direction.

In this embodiment, after forming the primary winding 6 by winding the outer periphery of the bobbin 5 with a specified number of turns with an enameled wire, the insulating tape 10 is wound around the outer periphery of the primary winding 6 a predetermined number of times, For example, an aluminum nonmagnetic metal spacer 9 is attached.
Thereafter, the insulating tape 10 is wound around the outer periphery of the nonmagnetic metal spacer 9 a specified number of times, and then the enameled wire, which is a conducting wire, is wound a specified number of turns to form the secondary winding 8.

  In this embodiment, by using the non-magnetic metal spacer 9, it is possible to have a large and excellent heat dissipation compared with the case where leakage inductance is generated using a conventional insulating tape, and the primary winding 6 By efficiently releasing heat to the outside, the transformer can be reduced in size, weight, and cost.

In a transformer having a winding width h of 33 mm and a separation distance δ of 1.3 mm, when the separation distance δ is composed of an aluminum nonmagnetic metal spacer 9 (thermal conductivity: 137 W / m / K), a nonmagnetic metal spacer The thermal resistance of 9 is 2.9 × 10 ⁻³ K / W, and the thermal resistance of the insulating tape 10 is ^0.5 K / W (thickness: 0.22 mm) in total on the inside and outside of the nonmagnetic metal spacer 9. Become.
In the transformer in which the heat generation amount in the primary winding 6 is 12.3 W, the temperature difference between the non-magnetic metal spacers 9 is 0.04K, and the temperature difference between the insulating tapes 10 is 6.2K. It becomes 4.8K, and the temperature difference can be reduced by 85% compared to the case of using the conventional Nomec tape.

  Since the nonmagnetic metal spacer 9 is formed with slits extending in the entire area in the axial direction, one-turn short-circuit of the transformer is suppressed and normal transformer operation is ensured.

  In addition, the rigid spacer is composed of the nonmagnetic metal spacer 9 and the insulating tape 10 and is nonmagnetic. Therefore, the rigid spacer is caused by the leakage magnetic flux generated between the separation distance δ between the primary winding 6 and the secondary winding 8. Generation of eddy current is suppressed.

Embodiment 3 FIG.
FIG. 3 is a plan sectional view showing the main part of the transformer of the third embodiment.
The rigid spacer composed of the nonmagnetic metal spacer 9 and the insulating tape 10 of this embodiment is composed of a plurality of divided spacer bodies 11 which are separated from each other in the circumferential direction of the primary winding 6.
The divided spacer body 11 is disposed in close contact with each corner portion of the rectangular primary winding 6.
Other configurations are the same as those of the transformer of the second embodiment.

In the first and second embodiments, cylindrical rigid spacers are used, and when the radial winding height varies in the primary winding 6 and the secondary winding 8, the primary winding 6 and the rigid body are used. Adhesion between the spacer and the rigid spacer and the secondary winding 8 is deteriorated, and an air layer is formed in the gap therebetween.
After that, when the transformer main body is placed in the case and filled with the insulating resin, the air layer remains as it is.
On the other hand, in this embodiment, even if the winding height varies in the primary winding 6 and the secondary winding 8, the divided spacer body 11 is connected to the primary winding 6 and the secondary winding 8. By closely contacting the corner portion, the generation of the air layer can be reduced, the air layer contained in the insulating resin in the case can be reduced, and the heat dissipation of the transformer is improved.

Even if a one-turn short circuit is possible only by forming a slit extending in the axial direction in the rigid spacer, the leakage magnetic flux necessary for the resonant circuit is converted into heat as eddy current loss in the nonmagnetic metal spacer 9 although it is a minute amount. As a result, the leakage inductance decreases.
For this reason, the rigid spacer is configured by the divided spacer body 11 so as to suppress the amount of leakage magnetic flux passing through the nonmagnetic metal spacer 9 and suppress the decrease in leakage inductance.

As shown in FIG. 4, the divided spacer body 11 may be brought into close contact with an intermediate portion between the corner portions of the primary winding 6 and the secondary winding 8.
Further, the resin spacer 7 of the first embodiment may also be composed of a plurality of divided spacer bodies that are separated from each other in the circumferential direction of the primary winding 6.

Embodiment 4 FIG.
In this embodiment, a metal spacer in which an insulating film is formed on the nonmagnetic metal spacer 9 is used as the rigid spacer.
Other configurations are the same as those of the transformer of the second embodiment.

When the nonmagnetic metal spacer 9 is used, insulation is not ensured between the primary winding 6 and the secondary winding 8.
For example, when the corner portion of the nonmagnetic metal spacer 9 is a right angle, the enameled wire insulation film is damaged when the secondary winding 8 is formed by winding the enamel wire around the nonmagnetic metal spacer 9 during assembly. As a result, insulation failure occurs between the nonmagnetic metal spacer 9 and the secondary winding 8.

On the other hand, in the metal spacer of this embodiment, since the insulating film is formed on the nonmagnetic metal spacer 9, even if the enameled wire insulating film is damaged, the nonmagnetic metal spacer 9 and the secondary winding Insulation is ensured between the transformer 8 and the transformer can be operated normally.
In addition, since a separate insulating tape or the like is not required, it is possible to contribute to a reduction in heat resistance and material cost inside the transformer and an improvement in assembly.

Embodiment 5 FIG.
In this embodiment, the corner portion of the metal spacer is chamfered.
Other configurations are the same as those of the transformer of the fourth embodiment.

In the metal spacer of this embodiment, since the corner portion is chamfered, damage to the insulating film of the enamel wire at the corner portion when the enamel wire is wound around the outer periphery of the metal spacer during assembly is reduced.
In addition, also about each rigid spacer of Embodiment 1-3, the damage of the insulating film of the enamel wire at the time of an assembly is reduced by chamfering a corner part.

In each of the above embodiments, the inner iron type transformer has been described. However, the present invention can also be applied to an outer iron type transformer.
In each of the above embodiments, the inner winding is the primary winding 6 and the outer winding is the secondary winding 8, but the inner winding is the secondary winding and the outer winding is the primary winding. It may be a winding.
In addition, the primary winding 6 and the secondary winding 8 both have a single-layer structure in which enameled wires, which are conductive wires, are wound, but the primary winding and the secondary winding may have a multilayer structure.
Further, although the PPS resin is used as the resin spacer, this is an example, and for example, a PBT resin, an ABS resin, or a PA resin may be used.
Moreover, although aluminum was used as the nonmagnetic metal spacer, this is an example, and for example, copper or nonmagnetic stainless steel may be used.

  DESCRIPTION OF SYMBOLS 1 1st core part, 2nd core part, 3 core, 4 pillar part, 5 bobbin, 6 primary winding (inner side winding), 7 resin spacer, 8 secondary winding (outer side winding), 9 Nonmagnetic metal spacer, 10 insulating tape, 11 split spacer body.

Claims (7)

The core,
A bobbin provided around the core;
An inner winding wound around this bobbin,
An insulating member provided around the inner winding;
An outer winding wound around the insulating member,
A transformer in which the other transforms according to the voltage of one of the inner winding and the outer winding,
The insulating member is Ri Oh rigid spacer for holding a distance between the outer winding and the inner winding,
The inner winding is a primary winding and the outer winding is a secondary winding;
The separation distance is a transformer which is a value obtained by the following equation with respect to the leakage inductance .

Here, Lleak is the leakage inductance, μ is the magnetic permeability, T is the number of turns of the conducting wire of the primary winding, δ is the separation distance, Δ1 is the radial height of the primary winding, and Δ2 is the secondary winding. The height in the radial direction of the winding, h is the length of the primary winding in the axial direction of the bobbin, and L is a value obtained by adding the respective peripheral lengths of the primary winding and the secondary winding divided by 2. Length, q is the number of symmetrical linkages. The core,
A bobbin provided around the core;
An inner winding wound around this bobbin,
An insulating member provided around the inner winding;
An outer winding wound around the insulating member,
A transformer in which the other transforms according to the voltage of one of the inner winding and the outer winding,
The insulating member is a rigid spacer that maintains a separation distance between the inner winding and the outer winding,
The outer winding is a primary winding, and the inner winding is a secondary winding;
The separation distance is a transformer which is a value obtained by the following equation with respect to the leakage inductance .

Here, Lleak is the leakage inductance, μ is the magnetic permeability, T is the number of turns of the conducting wire of the primary winding, δ is the separation distance, Δ1 is the radial height of the primary winding, and Δ2 is the secondary winding. The height in the radial direction of the winding, h is the length of the primary winding in the axial direction of the bobbin, and L is a value obtained by adding the respective peripheral lengths of the primary winding and the secondary winding divided by 2. Length, q is the number of symmetrical linkages. The transformer according to claim 1, wherein the rigid spacer is a resin spacer. The said rigid spacer is comprised from the non-magnetic metal spacer which has the slit extended and formed in the whole region along the axial direction of the said bobbin, and the insulating tape wound around the surface of this non-magnetic metal spacer. The transformer according to 1 or 2 . The said rigid spacer is comprised from the nonmagnetic metal spacer which has the slit extended and formed in the whole region along the axial direction of the said bobbin, and the insulating film formed in the surface of this nonmagnetic metal spacer. Or the transformer according to 2 . The transformer according to any one of claims 1 to 5 , wherein the rigid spacer is configured by a plurality of divided spacer bodies that are separated from each other in the circumferential direction of the inner winding. The transformer according to any one of claims 1 to 6 , wherein a corner portion of the rigid spacer is chamfered.

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