CN217690729U

CN217690729U - Planar transformer

Info

Publication number: CN217690729U
Application number: CN202221207466.5U
Authority: CN
Inventors: 赵自强; 周喜强; 张少磊
Original assignee: Shaanxi Changling Maiteng Electronics Co ltd
Current assignee: Shaanxi Changling Maiteng Electronics Co ltd
Priority date: 2022-05-19
Filing date: 2022-05-19
Publication date: 2022-10-28
Anticipated expiration: 2032-05-19

Abstract

The utility model discloses a planar transformer, which comprises a first magnetic core, a second magnetic core, a primary PCB winding, a secondary PCB winding, an input pin and an output pin; the first magnetic core and the second magnetic core are E-shaped, the open ends of the first magnetic core and the second magnetic core are arranged oppositely up and down, and an air gap is formed between the opposite middle columns of the first magnetic core and the second magnetic core; the primary PCB windings and the secondary PCB windings are arranged in a cavity formed by the first magnetic core and the second magnetic core in a laminated mode, and meanwhile the secondary PCB windings are symmetrically arranged on the upper side and the lower side of the primary PCB windings according to the number; a gap is reserved between the upper end surface of the secondary PCB winding on the uppermost layer and the first magnetic core; the center of the primary PCB winding and the center of the air gap are positioned on the same horizontal plane, the input pin is connected with the primary PCB winding, and the output pin is connected with the secondary PCB winding. The distance between the secondary PCB windings positioned at the upper side and the lower side of the primary PCB winding and the air gap in the magnetic core is the same, so that the purpose of consistent output voltage is achieved.

Description

Planar transformer

Technical Field

The utility model belongs to the technical field of switching power supply transformer, concretely relates to planar transformer.

Background

Due to the flat structure mode and the tight coupling between the windings of the planar transformer, the size of the transformer is greatly reduced, and the requirement of miniaturization of modern power electronics is met. However, due to the special structure of the printed circuit board, different windings of the same turn are designed on different circuit layers, so that the distance between the winding and the air gap is different; however, in an LLC resonant circuit or a flyback circuit with a center tap, the influence of leakage flux on its output voltage is extremely significant, and the conventional structure cannot meet the requirements of these two circuits, so designing a transformer structure with the same winding and air gap spacing is an urgent problem to be solved at present.

SUMMERY OF THE UTILITY MODEL

In order to solve the above problems existing in the prior art, the utility model provides a planar transformer. The to-be-solved technical problem of the utility model is realized through following technical scheme:

a planar transformer comprises a first magnetic core, a second magnetic core, a primary PCB winding, a secondary PCB winding, an input pin and an output pin; wherein the content of the first and second substances,

the first magnetic core and the second magnetic core are E-shaped, the open ends of the first magnetic core and the second magnetic core are arranged up and down oppositely, and an air gap is formed between the middle columns of the first magnetic core and the second magnetic core which are opposite; the secondary PCB windings are arranged between the first magnetic core and the second magnetic core in a stacked mode, the primary PCB windings and the secondary PCB windings are sleeved on the middle columns of the first magnetic core and the second magnetic core through holes in the middle of the primary PCB windings and the secondary PCB windings respectively, the part clamped between the first magnetic core and the second magnetic core is located in a cavity formed by the first magnetic core and the second magnetic core, and meanwhile the secondary PCB windings are symmetrically arranged on the upper side and the lower side of the primary PCB windings in number; a gap is reserved between the upper end surface of the secondary PCB winding on the uppermost layer and the first magnetic core; the center of the primary PCB winding and the center of the air gap are located on the same horizontal plane, the input pin is connected with the primary PCB winding, and the output pin is connected with the secondary PCB winding.

Further, the maximum height of the first magnetic core is greater than the maximum height of the second magnetic core.

Further, the primary PCB winding and the secondary PCB winding, the secondary PCB winding and the second magnetic core of the lowest layer, and the first magnetic core and the second magnetic core are bonded through epoxy resin.

Further, the first magnetic core and the second magnetic core are ferrite magnetic cores.

The utility model has the advantages that:

1. the planar transformer has the advantages that the primary PCB winding is positioned in the center of the air gap by adjusting the heights of the upper and lower magnetic cores, and the distances from the secondary PCB windings positioned on the upper and lower sides of the primary PCB winding to the air gap in the magnetic core are the same, so that the influences of the drain electrodes on the secondary windings are the same, and the purpose of consistent output voltage is achieved;

2. the traditional enameled wire is replaced by the PCB winding, so that the high-frequency loss of the winding is reduced.

The present invention will be described in further detail with reference to the accompanying drawings and examples.

Drawings

Fig. 1 is a schematic structural view of the present invention;

FIG. 2 is a schematic diagram of the structure of a first magnetic core and a second magnetic core;

fig. 3 is an exploded view of the present invention.

Description of reference numerals:

1-a first magnetic core; 2-a second magnetic core; 3-primary PCB winding; 4-secondary PCB winding; 5-an input pin; 6-an output pin; 7-air gap.

Detailed Description

The present invention will be described in further detail with reference to specific examples, but the present invention is not limited thereto.

Please refer to fig. 1-3 simultaneously, an embodiment of the present invention provides a planar transformer, which is used for an LLC resonant circuit or a planar transformer of a flyback circuit with a center tap at an output end, and specifically includes: the transformer comprises a first magnetic core 1, a second magnetic core 2, a primary PCB winding 3, a secondary PCB winding 4, an input pin 5 and an output pin 6; wherein the content of the first and second substances,

the first magnetic core 1 and the second magnetic core 2 are E-shaped, the open ends of the first magnetic core 1 and the second magnetic core 2 are arranged up and down oppositely, and the first magnetic core 1 is positioned above the second magnetic core 2; an air gap 7 is arranged between the opposite center pillars of the first magnetic core 1 and the second magnetic core 2, and the air gap 7 is used for adjusting the effective permeability.

The number of the secondary PCB windings is two, the primary PCB winding 3 and the secondary PCB winding 4 are arranged between the first magnetic core 1 and the second magnetic core 2 in a stacked mode, and are respectively sleeved on the middle columns of the first magnetic core 1 and the second magnetic core 2 through holes in the middle of the primary PCB winding 3 and the secondary PCB winding 4, the primary PCB winding 3 and the secondary PCB winding 4 clamped between the first magnetic core 1 and the second magnetic core 2 are located in a cavity formed by the first magnetic core 1 and the second magnetic core 2, and meanwhile the two secondary PCB windings 4 are respectively arranged on the upper side and the lower side of the primary PCB winding 3; the PCB winding adopts a secondary-primary-secondary sandwich distribution structure, and in addition, the traditional enameled wire is replaced by a printed copper wire on a printed circuit board, so that the high-frequency loss of the traditional winding is reduced.

A gap is reserved between the upper end face of the secondary PCB winding 4 on the uppermost layer and the first magnetic core 1, so that the planar transformer can work normally.

Due to the existence of the air gap 7, severe edge magnetic flux exists at the edge of the air gap 7, the distances between different windings and the air gap 7 are different in the processing process of the planar transformer, the influence of the edge magnetic flux on the different windings is also different, so that the output voltage of the windings with the same number of turns is deviated, the zero potential is deviated, and the circuit cannot work normally; therefore, the utility model discloses in, will the maximum height value design of first magnetic core 1 is greater than the height value of second magnetic core 2 makes the center of elementary PCB winding 3 with the center of air gap 7 is located same horizontal plane, and elementary PCB winding 3 is located promptly the center of air gap 7, then the distance that is located secondary PCB winding 4 of the upper and lower both sides of elementary PCB winding 3 apart from magnetic core center pillar air gap 7 is the same, and then makes the influence of magnetic leakage to two secondary PCB windings the same, thereby reaches the unanimous purpose that gets of output voltage.

Through holes are formed in two sides of one end of the primary PCB winding 3, and the input pin 5 is fixed in the through holes so as to be fixed with the primary PCB winding 3; through holes are formed in two sides of one end of each of the secondary PCB windings 4 positioned on the upper side and the lower side of the primary PCB winding 3, the output pins 6 are fixed in the through holes so as to be fixed with the secondary PCB windings 4, and the output pins 6 penetrate through the two secondary PCB windings 4 so as to be connected in series.

If there are 4 or more secondary PCB windings 4, two secondary PCB windings 4 symmetrically disposed with the center of the air gap 7 as a symmetrical line are fixedly connected through the output pin 6.

Between primary PCB winding 3 and upper and lower two-layer secondary PCB winding 4, the secondary PCB winding 4 of lower floor and lower floor between the second magnetic core 2 and between first magnetic core 1 and the second magnetic core 2 all bond through epoxy, guarantee the fastness of whole structure.

If there are four secondary PCB windings 4, that is, the PCB windings adopt a secondary-primary-secondary distribution structure, the upper two layers of secondary PCB windings 4, the primary PCB windings 3 and the upper and lower adjacent secondary PCB windings 4, the lower two layers of secondary PCB windings 4, the lowermost secondary PCB windings 4 and the lower second magnetic core 2, and the first magnetic core 1 and the second magnetic core 2 are bonded by epoxy resin.

Preferably, the first magnetic core 1 and the second magnetic core 2 are both made of ferrite materials with high saturation and low loss.

Bonding the primary PCB winding 3 and the two secondary PCB windings 4 together by epoxy resin, respectively welding an input pin 5 and an output pin 6 with the primary PCB winding 3 and the secondary PCB winding 4 through welding pads, then loading the PCB windings with the pins into the second magnetic core 2, bonding the lower secondary PCB winding 4 with the second magnetic core 2, and then bonding the first magnetic core 1 on the second magnetic core 2 by epoxy resin.

In the description of the present invention, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implying any number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically limited otherwise.

The foregoing is a more detailed description of the present invention, taken in conjunction with the specific preferred embodiments thereof, and it is not intended that the invention be limited to the specific embodiments shown and described. To the utility model belongs to the technical field of ordinary technical personnel, do not deviate from the utility model discloses under the prerequisite of design, can also make a plurality of simple deductions or replacement, all should regard as belonging to the utility model discloses a protection scope.

Claims

1. A planar transformer, comprising: the PCB comprises a first magnetic core, a second magnetic core, a primary PCB winding, a secondary PCB winding, an input pin and an output pin; wherein, the first and the second end of the pipe are connected with each other,

2. The planar transformer of claim 1, wherein a maximum height of the first magnetic core is greater than a maximum height of the second magnetic core.

3. The planar transformer according to claim 1 or 2, wherein the primary and secondary PCB windings, the secondary and secondary PCB windings, the lowermost secondary and lower second magnetic cores, and the first and second magnetic cores are bonded by epoxy.

4. The planar transformer according to claim 1, wherein the first and second cores are ferrite cores.