CN210865834U - Transformer and magnetic core thereof - Google Patents

Abstract

The utility model discloses a magnetic core of transformer is through being in by outer cylinder and setting the inside interior cylinder of outer cylinder constitutes, and the lateral surface of interior cylinder is provided with the winding recess that the round is used for the coiling transformer, just outer cylinder with the partial lateral surface of interior cylinder has equidistant clearance, the clearance is used for forming magnetic core of transformer's air gap. So that the transformer is thinner, the heat dissipation is better, and simultaneously, the transformer can be better suitable for the occasions with multi-output or fractional turn ratio.

Description

Transformer and magnetic core thereof

Technical Field

The utility model relates to a power electronics technique, more specifically say, relate to a transformer and magnetic core thereof.

Background

In an isolation module power supply, a plurality of circuit topologies have a multi-output function, and under many conditions of a flyback converter (flyback), because an IC is not high-voltage isolation, the output voltage of a secondary side needs to be regulated and controlled by controlling a primary side auxiliary winding. At present, a transformer module shown in fig. 1 is mostly adopted for high-isolation multi-output, and the transformer module is composed of a magnetic core and a framework wound with windings, and the structure has the disadvantages that the bottom plate is provided with the framework for winding the windings, the height of the transformer can be increased by the framework, the heat dissipation of the transformer can be influenced by the existence of the framework, and in addition, the transformer with the structure is inconvenient to realize the condition of fractional turn ratio due to the fixation of outgoing line pins.

SUMMERY OF THE UTILITY MODEL

In view of this, the utility model provides a transformer and magnetic core thereof to solve current transformer and be difficult to realize the problem of fractional turn ratio and be not suitable for the multiplexed output occasion.

In a first aspect, a transformer core is provided, comprising:

an outer cylinder; and the number of the first and second groups,

an inner cylinder disposed inside the outer cylinder;

the outer side surface of the inner cylinder is provided with a circle of groove, the groove is used for winding a winding of a transformer, and equidistant gaps are formed between the outer cylinder and part of the outer side surface of the inner cylinder.

Preferably, the inner leg forms a center leg of the transformer core, the outer leg forms a side leg of the transformer core, and a gap between the outer leg and the inner leg forms an air gap of the transformer core.

Preferably, the inner cylinder comprises a top part, a middle part and a bottom part which are closely connected, and the radial dimension of the middle part is smaller than that of the top part and the bottom part to form the groove.

Preferably, the top, middle and bottom of the inner cylinder are integrally formed.

Preferably, the column heights of the outer column and the inner column are the same.

Preferably, the outer side surfaces of the top and bottom of the inner cylinder have equidistant gaps with the outer cylinder.

Preferably, the top of the outer cylinder is provided with a plurality of grooves for penetrating through the leading-out ends of the windings.

Preferably, the top of the outer cylinder is provided with a plurality of pad pins, and the pad pins are used for connecting with the leading-out ends of the windings.

Preferably, a groove is formed in the pad pin, and the groove is used for placing the leading-out end of the winding.

Preferably, a plurality of clamping grooves are formed in the inner cylinder and correspond to the leading-out end of the outer cylinder, and the clamping grooves are used for fixing the winding to the leading-out end.

Preferably, the material of the outer cylinder is nickel zinc ferrite.

Preferably, the material of the inner cylinder is nickel zinc ferrite, manganese zinc ferrite or a metal powder core.

Preferably, the inner cylinder is a cylinder, a cuboid, a cube, a polygonal prism or an elliptic cylinder.

Preferably, the outer cylinder is a hollow cylinder, a cuboid, a cube, a polygonal prism or an elliptic cylinder.

In a second aspect, there is provided a transformer comprising:

the above-described transformer core; and the number of the first and second groups,

at least two transformer windings.

The utility model discloses the technique is through being in by outer cylinder and setting the inside interior cylinder of outer cylinder constitutes, and the lateral surface of interior cylinder is provided with the winding recess that the round is used for the coiling transformer, just outer cylinder with the partial lateral surface of interior cylinder has equidistant clearance, the clearance is used for forming the air gap of magnetic core of transformer. So that the transformer is thinner, the heat dissipation is better, and simultaneously, the transformer can be better suitable for the occasions with multi-output or fractional turn ratio.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required to be used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.

FIG. 1 is a schematic diagram of a power transformer module of the prior art;

fig. 2 is a schematic diagram of a transformer core structure according to the present invention;

fig. 3 is a longitudinal sectional view of the magnetic core of the transformer of the present invention;

fig. 4 is a schematic diagram of another transformer core structure according to the present invention;

fig. 5 is a bottom view of the magnetic core of the transformer of the present invention;

FIG. 6 is a schematic view of a magnetic circuit of a magnetic core of a transformer according to a comparative example;

fig. 7 is a schematic diagram of a magnetic circuit of a transformer core according to the present invention.

Detailed Description

The present invention will be described below based on examples, but the present invention is not limited to only these examples. In the following detailed description of the present invention, certain specific details are set forth in detail. It will be apparent to those skilled in the art that the present invention may be practiced without these specific details. Well-known methods, procedures, components and circuits have not been described in detail so as not to obscure the present invention.

Further, those of ordinary skill in the art will appreciate that the drawings provided herein are for illustrative purposes and are not necessarily drawn to scale.

Meanwhile, it should be understood that, in the following description, a "circuit" refers to a conductive loop constituted by at least one element or sub-circuit through electrical or electromagnetic connection. When an element or circuit is referred to as being "connected to" another element or element/circuit is referred to as being "connected between" two nodes, it may be directly coupled or connected to the other element or intervening elements may be present, and the connection between the elements may be physical, logical, or a combination thereof. In contrast, when an element is referred to as being "directly coupled" or "directly connected" to another element, it is intended that there are no intervening elements present.

Unless the context clearly requires otherwise, throughout the description and the claims, the words "comprise", "comprising", and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is, what is meant is "including, but not limited to".

In the description of the present invention, it is to be understood that the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance. In addition, in the description of the present invention, "a plurality" means two or more unless otherwise specified.

Fig. 2 is a schematic diagram of the structure of the transformer core according to the present invention. As shown in fig. 2, the transformer core includes an outer cylinder 1 and an inner cylinder 2 disposed inside the outer cylinder 1. The outer side surface of the inner cylinder 2 is provided with a circle of groove, the groove is used for winding a winding 3 of the transformer, and the outer cylinder 1 and the outer side surface of the inner cylinder 2 are provided with equidistant gaps. In the embodiment of the present invention, the outer column 1 is a hexagonal prism, the hollow part inside the outer column is a cylinder, and the inner column 2 is also a cylinder corresponding to the hollow part inside the outer column 1. Of course, the inner column 2 may also be a cylinder, a cuboid, a cube, a polygon prism, or an elliptic cylinder, and correspondingly, the hollow portion of the outer column 1 may also be a cylinder, a cuboid, a cube, a polygon prism, or an elliptic cylinder, so as to meet the requirement that the outer columns 1 and the inner column 2 partially have equal distance between the outer sides. The outer column 1 may be a cylinder, a cuboid, a cube, a polygon prism or an elliptic cylinder.

Fig. 3 is a longitudinal sectional view of the transformer core of the present invention. As shown in fig. 3, the longitudinal section of the inner cylinder 2 is in an i shape, and the inner cylinder 2 includes a top portion 21, a middle portion 22 and a bottom portion 23 which are closely connected. Preferably, the radial dimension of the middle portion 22 is set smaller than the radial dimension of the top portion 21 and the bottom portion 23 to form the groove, and the radial dimension of the top portion 21 and the bottom portion 23 is the same, so that the outer side surfaces of the top portion 21 and the bottom portion 23 of the inner cylinder 2 have an equidistant gap from the outer cylinder 1. Taking the magnetic core structure shown in fig. 2 as an example, when the inner cylinder 2 is a cylinder, the top 21, the middle 22 and the bottom 23 are all made of cylinders, and the cross-sectional radius of the middle 22 is smaller than that of the top 21 and the bottom 23. Preferably, the top portion 21, the middle portion 22 and the bottom portion 23 are integrally formed.

In addition, it will be appreciated that the column height of the inner column 2 is preferably the same as the column height of the outer column 1 to minimize the core size and to save core material.

Referring to fig. 3 again, in the utility model discloses in, constitute magnetic core's center pillar by interior cylinder 2, outer cylinder 1 constitutes magnetic core's side post, because top 21, middle part 22 and the bottom 23 zonulae occludens of interior cylinder 2 do not have the clearance, so the utility model discloses aim at forming magnetic core's air gap 4 by the equidistance clearance of outer cylinder 1 and interior cylinder 2 to realize the transformer of the fractional turn ratio of high accuracy.

Further, because the utility model discloses a magnetic core of transformer does not need the skeleton of coiling winding to reduce the size of transformer, thereby with the winding 3 coiling in the recess of inner cylinder 2, for the convenient lead wire, the utility model discloses still be provided with a plurality of pad pins 11 at outer cylinder 1's top, preferably, can choose silver-plated pad pin for use. The pad pin 11 is a thin sheet and is closely attached to the top of the outer cylinder 1. The pad pin 11 is further provided with a groove, and the groove on the pad pin 11 is used for placing a leading-out end of the winding 3. The pad pins 11 are used for connecting the leading-out ends of the windings 3, the placement positions and the number of the pad pins 11 are determined according to the turn ratio and the number of windings of the transformer, and meanwhile, the number of windings of the transformer is related to the number of output paths, so the pad pins 11 can be specifically arranged according to the turn ratio of the transformer and the number of output paths. Further, the number of the pad pins 11 is determined by the number of windings or the number of output paths of the transformer, and the placement position of the pad pins 11 is determined by the turn ratio of the transformer. For example, when the transformer is applied to a flyback converter with two-path output, the transformer has at least 1 primary winding and 2 secondary windings, and in many cases, the transformer also has 1 auxiliary winding, and when 4 windings are wound in the groove of the inner cylinder 2, 8 leading-out terminals need to be led out, and 8 pad pins 11 need to be arranged. If each winding is of integral turns, namely two leading-out terminals (including a wire inlet terminal and a wire outlet terminal) are led out from the same position of the inner column body 2, no requirement is made on the placement position of the welding disc pins 11. When a winding with fractional turns exists, for example, the turn ratio of the primary winding to the secondary winding needs to be 100:1, and if the groove space of the inner cylinder 2 is limited and the winding with 101 turns cannot be placed, the turn ratio of the primary winding to the secondary winding can be set to be 50:0.5, so that the turn ratio of the transformer is not changed, and the window area of the magnetic core of the transformer is enough to place the winding on the primary side and the secondary side. In this case, the two pad pins 11 for extracting the secondary winding may be provided at positions having an angular difference of 180 degrees, and similarly, when the secondary winding has 1/4 turns, the two pad pins 11 for extracting the secondary winding may be provided at positions having an angular difference of 90 degrees. Therefore, the inner column 2 is preferably a cylinder structure, so as to improve the versatility of the transformer core under different turn ratios. Meanwhile, on the occasion of multi-path output, the transformer has a larger window area and can be used for winding a winding, and the number and the positions of the leading-out ends can be more flexibly set according to the occasion, so that the transformer is more suitable for the multi-path output switching power supply.

Still further, a plurality of clamping grooves 21 are arranged on the inner cylinder 2 corresponding to the leading-out end of the outer cylinder 1, and the clamping grooves 21 are used for fixing the winding to the leading-out end.

Preferably, in order to keep up with the further reduction in the size of the transformer core, a plurality of recesses (not shown in the drawings) may be provided directly on the top of the outer column 1, the tops of the recesses being flush with the top of the outer column 1. The leading-out end of the winding 3 is embedded in the groove, so that the height of one pad pin can be saved. Because for prior art, the utility model discloses a bottom plate that is provided with the end of drawing forth can be removed to the transformer, consequently, thinner transformer structure can provide better radiating effect.

It should be noted that, the technical scheme of the utility model the end of drawing forth of winding 3 is drawn forth at the top of outer cylinder 1, and does not select at the middle part of the cylinder of outer cylinder 1, set up a through-hole and draw forth, the reason lies in: if the leading-out end is a through hole in the middle of the outer column, because the outer column body 1 is made of a magnetic material with high magnetic permeability, the leading-out end is surrounded by the magnetic material, and similarly to the winding lead wire passing through a ferrite magnetic ring, because large power current flows in the lead wire, very large magnetic flux is easily induced in the outer column body 1, and the side column (namely the outer magnetic column) is saturated.

In the embodiment of the present invention, since the nickel-zinc ferrite can improve the magnetic permeability and the saturation magnetic induction, and the magnetic loss is reduced, the material of the outer column 1 is preferably nickel-zinc ferrite, and the material of the inner column 2 can be one of nickel-zinc ferrite, manganese-zinc ferrite, or metal powder core.

Fig. 4 is a schematic diagram of another structure of the transformer core according to the present invention, and fig. 5 is a bottom view of the transformer core shown in fig. 4. In the embodiment of the present invention, the outer cylinder 1 is a cylinder, the hollow part inside the outer cylinder is a cylinder, and the inner cylinder 2 is also a cylinder corresponding to the hollow part inside the outer cylinder 1. In addition, as can be seen from the schematic and bottom views, the terminal pins are provided only at one end of the transformer core, i.e. the terminals of the windings 3 are preferably provided at the same end of the transformer to minimize the transformer core size, here specifically to reduce the height.

Fig. 6 is a schematic view of a magnetic circuit of a transformer core according to a comparative example, and fig. 7 is a schematic view of a magnetic circuit of a transformer core according to the present invention. The principle of the transformer of the present invention for achieving fractional turn ratio operation is set forth below in conjunction with a magnetic circuit diagram. Here, taking half turn as an example, that is, the turn ratio of the primary side to the secondary side is 1:1/2, fig. 6 shows a cross section of a conventional center pillar open air gap EE-type transformer structure, and fig. 7 shows a cross section of the transformer of the present invention. Wherein the open circles represent 1 turn windings on the primary side and the shaded circles represent 0.5 turn windings on the secondary side. The solid line in the figure shows the flux generated by the half turn of the primary side more.

It can be seen that although the primary-secondary turn ratio is 1:1/2 in fig. 6, most of the magnetic flux generated by the half turn of the primary side is away from the side pole, and the main magnetic flux actually going through the center pole is very little, so the actual turn ratio can not achieve 1:1/2, and the transformer core has no air gap in the side pole, and the magnetic resistance is small, so the saturation of the side pole is easily caused. In the transformer of the present invention in fig. 7, the magnetic flux generated by the half turn of the primary side is almost completely removed from the central pillar, so that the magnetic flux can be coupled to the secondary side to form a more accurate turn ratio of 1: 1/2.

On the other hand, the transformer in the prior art shown in fig. 1 can theoretically realize fractional turns, but due to the existence of the base plate, and the winding end of the base plate is separated from the leading-out end, the winding end is on the opposite side, so that the leading-out end is fixed in position and cannot be adjusted according to the turn ratio. Reversely view the utility model discloses a transformer structure does not have the bottom plate, need not to consider the bottom plate lead wire and changes the position that the transformer draws forth the end. Therefore, the required number of turns or turn ratio can be precisely adjusted by the angle of the terminal pin.

Therefore, the utility model discloses a magnetic core of transformer is through being in by outer cylinder and setting the inside interior cylinder of outer cylinder constitutes, and the lateral surface of interior cylinder is provided with the winding recess that the round is used for the coiling transformer, just outer cylinder with the part lateral surface of interior cylinder has the equidistant clearance, the clearance is used for forming magnetic core of transformer's air gap. So that the transformer is thinner, the heat dissipation is better, and simultaneously, the transformer can be better suitable for the occasions with multi-output or fractional turn ratio.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included within the protection scope of the present invention.

Claims (15)

1. A magnetic core for a transformer, comprising:

an outer cylinder; and the number of the first and second groups,

an inner cylinder disposed inside the outer cylinder;

the outer side surface of the inner cylinder is provided with a circle of groove, the groove is used for winding a winding of a transformer, and equidistant gaps are formed between the outer cylinder and part of the outer side surface of the inner cylinder.

2. The transformer core according to claim 1, wherein the inner leg forms a center leg of the transformer core, the outer leg forms a side leg of the transformer core, and a gap between the outer leg and the inner leg forms an air gap of the transformer core.

3. The transformer core according to claim 1, wherein the inner leg comprises a top portion, a middle portion and a bottom portion that are closely coupled, and wherein the middle portion has a radial dimension that is smaller than the radial dimensions of the top portion and the bottom portion to form the recess.

4. The transformer core according to claim 3, wherein the top, middle and bottom portions of the inner leg are integrally formed.

5. The transformer core according to claim 1, wherein the leg heights of the outer leg and the inner leg are the same.

6. The transformer core according to claim 3, wherein the top and bottom outer sides of the inner leg have an equidistant gap from the outer leg.

7. A transformer core according to claim 1 wherein the top of the outer leg is provided with a plurality of slots for passing through the exit ends of the windings.

8. The transformer core according to claim 1, wherein the top of the outer leg is provided with a plurality of land pins for connecting to terminals of the windings.

9. The transformer core according to claim 8, wherein the land pins have a groove for receiving the terminals of the windings.

10. The transformer core according to claim 7 or 8, wherein a plurality of slots are disposed on the inner leg corresponding to the positions of the lead-out ends of the outer leg, and the slots are used for fixing the windings to the lead-out ends.

11. The transformer core according to claim 1, wherein the material of the outer leg is nickel zinc ferrite.

12. The transformer core according to claim 1, wherein the material of the inner leg is a nickel zinc ferrite, a manganese zinc ferrite, or a metal powder core.

13. The transformer core according to claim 1, wherein the inner cylinder is a cylinder, a cuboid, a cube, a polygonal prism, or an elliptic cylinder.

14. The transformer core according to claim 1, wherein the outer cylinder is a hollow cylinder, a cuboid, a cube, a polygonal prism, or an elliptical cylinder.

15. A transformer, comprising:

the transformer core of any of claims 1-14; and the number of the first and second groups,

at least two transformer windings.

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