CN110911088A

CN110911088A - LTCC high-voltage transformer

Info

Publication number: CN110911088A
Application number: CN201911216902.8A
Authority: CN
Inventors: 赵斌; 王刚; 王东蕾; 赵燕
Original assignee: Institute of Electronics of CAS
Current assignee: Institute of Electronics of CAS
Priority date: 2019-11-29
Filing date: 2019-11-29
Publication date: 2020-03-24
Anticipated expiration: 2039-11-29
Also published as: CN110911088B; WO2021104424A1

Abstract

The utility model provides an LTCC high-voltage transformer, which comprises an upper side column, a magnetic core middle column, a lower side column, a primary coil, a secondary coil, a first medium and a second medium, wherein the upper side column, the magnetic core middle column and the lower side column are sequentially arranged from top to bottom, and the primary coil and the secondary coil are arranged on the magnetic core middle column; the first mediums are uniformly distributed on the magnetic core center posts along the longitudinal direction; and the second mediums are respectively arranged between the two adjacent turns of coils. The magnetic leakage of the horizontal direction and the vertical direction of the transformer can be effectively reduced, and the effect of low leakage inductance is realized.

Description

LTCC high-voltage transformer

Technical Field

The present disclosure relates to the field of power equipment, and in particular, to a Low temperature co-fired ceramic (LTCC) based high voltage transformer.

Background

The Low Temperature Co-fired Ceramic (Low Temperature Co-fired Ceramic) technology is widely applied to the field of radio frequency microwaves, and in recent years, research on magnetic devices based on the LTCC technology is carried out at home and abroad along with development of high-frequency ferrite materials suitable for the LTCC technology and the working frequency band of a switching power supply. By adopting the LTCC process, the magnetic device with high power density and ultrathin size can be manufactured. In addition, the LTCC material and the semiconductor material have similar thermal expansion coefficients, and the three-dimensional integration of the power supply can be realized. The LTCC planar high-voltage transformer integrates and sinters the winding, the magnetic core and the outgoing line together to form an SMD packaging device with low profile, thereby having the advantages of low cost, low loss, small volume, high reliability, convenience for mass production and the like.

However, the common high-voltage transformer is assembled by encapsulating a high-voltage coil by using a discrete ferrite core and an organic insulating material, and has the disadvantages of complicated process, incapability of automatic production and high cost; contains organic materials, cannot be sealed, and has poor temperature resistance and humidity resistance; the problems of non-integrated structure, large thermal resistance, low power density and the like require technicians to further develop more suitable solutions.

Disclosure of Invention

Technical problem to be solved

The present disclosure provides an LTCC high voltage transformer to at least partially solve the technical problems as set forth above.

(II) technical scheme

According to an aspect of the present disclosure, there is provided an LTCC high voltage transformer, comprising in order from top to bottom: the upper side column, the magnetic core middle column and the lower side column; further comprising:

a primary coil and a secondary coil fired in the magnetic core center posts;

the first mediums are uniformly distributed on the magnetic core center posts along the longitudinal direction;

and the second mediums are respectively arranged between the adjacent two turns of primary coils, two turns of secondary coils or the primary coils and the secondary coils.

In some embodiments of the present disclosure, further comprising: and the connecting holes are respectively arranged on the first medium.

In some embodiments of the present disclosure, the material of the superior post is a high magnetic permeability material having a magnetic permeability of not less than 400.

In some embodiments of the present disclosure, the material of the lower leg is a high permeability material having a permeability of not less than 400.

In some embodiments of the present disclosure, the material of the post in the magnetic core is a low permeability material having a permeability of no greater than 100.

In some embodiments of the present disclosure, the upper leg and the lower leg have a relative permeability greater than a relative permeability of the center leg of the magnetic core.

In some embodiments of the present disclosure, adjacent primary coils are filled with a plurality of the second mediums.

(III) advantageous effects

According to the technical scheme, the LTCC high-voltage transformer disclosed by the invention has at least one or part of the following beneficial effects:

(1) this disclosure has realized the requirement to adjusting transformer excitation inductance in practical application through the first medium that sets up on the magnetic core center pillar.

(2) According to the low leakage inductance liquid crystal display panel, the second medium between two adjacent turns is applied, the magnetic leakage in the vertical direction is effectively reduced, and the effect of low leakage inductance is achieved.

(3) According to the transformer, the high-permeability material and the low-permeability material are applied, so that the magnetic leakage in the horizontal direction of the transformer is effectively reduced, and the effect of low leakage inductance is realized.

(4) According to the transformer, the overlapping area between the primary and the secondary is reduced by adopting the transformer winding structure, and the parasitic capacitance is effectively reduced.

(5) This openly through set up the connecting hole on the magnetic core center pillar, the effectual problem of layering in the sintering process that has avoided leading in the medium to cause.

Drawings

Fig. 1 is a schematic structural diagram of an LTCC transformer using a transformer winding structure in the prior art.

Fig. 2 is a schematic diagram of leakage magnetic flux distribution when a transformer winding structure is adopted in the prior art.

Fig. 3 is a schematic structural diagram of an LTCC transformer using a planar transformer winding structure in the prior art.

Fig. 4 is a schematic structural diagram of an LTCC high voltage transformer according to an embodiment of the disclosure.

[ description of main reference numerals in the drawings ] of the embodiments of the present disclosure

1-upper side column;

2-lower side column;

3-a magnetic core center post;

4-a primary coil;

5-a secondary coil;

6-a first medium;

7-a second medium;

8-connecting hole.

Detailed Description

For the purpose of promoting a better understanding of the objects, aspects and advantages of the present disclosure, reference is made to the following detailed description taken in conjunction with the accompanying drawings.

Certain embodiments of the present disclosure will now be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments of the disclosure are shown. Indeed, various embodiments of the disclosure may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements.

Fig. 1 is a schematic structural diagram of an LTCC transformer using a transformer winding structure in the prior art. Fig. 2 is a schematic diagram of leakage magnetic flux distribution when a transformer winding structure is adopted in the prior art. As shown in fig. 1, when the transformer winding structure is adopted, the leakage flux distribution is divided into horizontal leakage flux and vertical leakage flux as shown in fig. 2.

In which horizontal leakage flux, as shown in fig. 2, due to the LTCC transformer sintering the winding and the magnetic core together, a magnetic medium is filled between two adjacent layers of conductors. Therefore, the magnetic resistance of the magnetic medium between the two layers of conductors is comparable to the magnetic resistance of the upper and lower side columns of the transformer, and leakage magnetic flux in the horizontal direction is caused.

The vertical leakage flux is similar to the horizontal leakage flux, and as shown in fig. 2, the LTCC transformer sinters the winding and the magnetic core together, so that a magnetic medium is filled between two adjacent turns of the winding. Therefore, the magnetic resistance of the magnetic medium between two adjacent turns is comparable to that of the center leg and the side legs of the transformer core, thereby causing leakage flux in the vertical direction. Unlike the horizontal leakage flux, the magnetic resistance of the center leg of the magnetic core will further increase as the air gap of the center leg of the magnetic core increases, resulting in further increase of the leakage flux in the vertical direction.

The measures generally taken in practical applications to reduce the leakage inductance are: the adoption of the staggered winding structure can reduce the leakage flux in the vertical direction, but cannot solve the leakage flux in the horizontal direction. In particular, when the air gap is opened in the core leg, a large leakage inductance still exists even if the cross winding structure is adopted. In the flyback converter, the voltage stress of a main switching tube is large due to the existence of large leakage inductance, and the efficiency of the converter is reduced.

Fig. 3 is a schematic structural diagram of an LTCC transformer using a planar transformer winding structure in the prior art. As shown in fig. 3, the leakage inductance in the vertical direction can be effectively reduced by adopting the planar transformer winding structure. When the staggered winding structure is adopted, the coupling coefficient of the primary and the secondary of the transformer can be improved to more than 90%. However, as can be seen from fig. 3, in the planar transformer winding structure, the overlapping area of the primary and secondary of the transformer is significantly increased, compared to the transformer winding structure, thereby causing a large parasitic capacitance. In a flyback converter, this parasitic capacitance limits the output voltage of the converter, while increasing the winding loss of the transformer, reducing efficiency.

In a first exemplary embodiment of the present disclosure, an LTCC high voltage transformer is provided. Fig. 4 is a schematic structural diagram of an LTCC high voltage transformer according to an embodiment of the disclosure. As shown in fig. 4, the LTCC high voltage transformer of the present disclosure includes: the magnetic core comprises an upper side column 1, a magnetic core middle column 3, a lower side column 2, a primary coil 4, a secondary coil 5, a first medium 6 and a second medium 7, wherein the upper side column 1, the magnetic core middle column 3 and the lower side column 2 are sequentially arranged from top to bottom, and the primary coil 4 and the secondary coil 5 are fired in the magnetic core middle column 3; the first mediums 6 are uniformly distributed on the magnetic core center pillar 3 along the longitudinal direction, and the second mediums 7 are respectively arranged between two adjacent turns of coils. It should be noted here that two adjacent turns of the coil may be a primary coil 4 with two turns, a secondary coil 5 with two turns, or a primary coil 4 with one turn of the secondary coil 5. In a specific embodiment, when the second medium 7 is disposed between two adjacent turns of the secondary coil 5, the two adjacent turns of the secondary coil 5 can be completely filled by disposing the second medium 7. The first medium 6 is provided with a plurality of connection holes 8. The upper side column 1 and the lower side column 2 are made of high-magnetic-permeability materials; and the material of the magnetic core center pillar 3 is a low magnetic permeability material. Here, it should be noted that the magnetic permeability of the high magnetic permeability material is not less than 400; the low permeability material has a permeability of not more than 100.

The components of the LTCC high voltage transformer of the present invention are described in detail below.

The material with high magnetic permeability selected for the upper column 1 is 40012 of ESL company, but is not limited thereto, and other materials known to those skilled in the art to achieve similar effects may be used. The upper side column 1 can be designed into different shapes according to the actual design requirement, and the thickness is designed according to the requirement on leakage inductance and the requirement on size. The relative permeability of the high-permeability material selected for the upper column 1 is greater than that of the low-permeability material selected for the central column 3 of the magnetic core. By applying a high-permeability material to the upper side column 1, the leakage flux of the LTCC high-voltage transformer provided by the present disclosure in the horizontal direction is suppressed.

The high permeability material chosen for the lower leg 2 is 40011 from ESL, but is not limited thereto, and other materials known to those skilled in the art to achieve similar results may be used. The material is the same as the material with high magnetic permeability selected for the upper side column 1. The lower edge column 2 can be designed into different shapes according to the actual design requirement, and the thickness is designed according to the requirement on leakage inductance and the requirement on size. The relative permeability of the high-permeability material selected for the lower side column 2 is greater than that of the low-permeability material selected for the central column 3 of the magnetic core. By applying a high-permeability material to the lower side column 2, the leakage flux of the LTCC high-voltage transformer provided by the present disclosure in the horizontal direction is suppressed.

The low permeability material selected for the post 3 of the core is 4926-R from ESL, but is not limited thereto, and other materials known to those skilled in the art to achieve similar effects may be used. According to actual design requirements, the magnetic core center pillars 3 can be designed into different shapes, and the thicknesses of the two adjacent layers are designed according to the requirements of the compressive strength and the leakage inductance of the converter. The relative permeability of the low-permeability material selected for the central pillar 3 of the magnetic core is smaller than that of the high-permeability material selected for the lower side pillar 2 or the upper side pillar 1. By applying the low-permeability material to the magnetic core center pillar 3, the leakage flux of the LTCC high-voltage transformer provided by the present disclosure in the horizontal direction is suppressed.

The first medium 6 is a non-magnetic medium and is used as an air gap of the LTCC high-voltage transformer. And designing the thickness of the air gap according to the actual circuit requirement so as to meet the required excitation inductance.

And a plurality of connection holes 8 for connecting the magnetic materials divided by the first medium 6 are provided on the first medium 6 of the center pillar 3 of the magnetic core in order to prevent delamination during sintering.

The primary coil 4 is designed with turns according to the actual circuit requirements, and the width and thickness of the primary coil 4 are further adjusted according to the alternating current resistance requirements of the efficiency team and the volume limitation of the transformer.

The secondary coil 5 is similar to the primary coil 4. The number of turns is designed according to the actual circuit requirement, and the width and thickness of the primary coil 4 are further adjusted according to the requirement of the alternating current resistance of the efficiency team and the limitation of the transformer volume.

And a second medium 7, which is a non-magnetic-conductive medium, for increasing the magnetic resistance of the leg 3 in the vertical direction of the core, thereby reducing the magnetic flux leakage of the leg in the vertical direction of the core.

So far, the embodiments of the present disclosure have been described in detail with reference to the accompanying drawings. It is to be noted that, in the attached drawings or in the description, the implementation modes not shown or described are all the modes known by the ordinary skilled person in the field of technology, and are not described in detail. Further, the above definitions of the various elements and methods are not limited to the various specific structures, shapes or arrangements of parts mentioned in the examples, which may be easily modified or substituted by those of ordinary skill in the art.

From the above description, those skilled in the art should clearly recognize that the LTCC high voltage transformer of the present disclosure is applicable.

In summary, the present disclosure provides an LTCC transformer, which can be used to replace a high-voltage transformer in a current high-reliability high-voltage application (such as a high-voltage ignition device, an atomic clock ion pump power supply, a vacuum electronic device power supply, etc.), greatly improve the reliability of a system, reduce the volume and reduce the cost, is a promising technology, has a very broad application prospect, and has an important meaning for miniaturization of equipment.

It should also be noted that directional terms, such as "upper", "lower", "front", "rear", "left", "right", and the like, used in the embodiments are only directions referring to the drawings, and are not intended to limit the scope of the present disclosure. Throughout the drawings, like elements are represented by like or similar reference numerals. Conventional structures or constructions will be omitted when they may obscure the understanding of the present disclosure.

And the shapes and sizes of the respective components in the drawings do not reflect actual sizes and proportions, but merely illustrate the contents of the embodiments of the present disclosure. Furthermore, in the claims, any reference signs placed between parentheses shall not be construed as limiting the claim.

Unless otherwise indicated, the numerical parameters set forth in the specification and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by the present disclosure. In particular, all numbers expressing quantities of ingredients, reaction conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term "about". Generally, the expression is meant to encompass variations of ± 10% in some embodiments, 5% in some embodiments, 1% in some embodiments, 0.5% in some embodiments by the specified amount.

Furthermore, the word "comprising" does not exclude the presence of elements or steps not listed in a claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements.

The use of ordinal numbers such as "first," "second," "third," etc., in the specification and claims to modify a corresponding element does not by itself connote any ordinal number of the element or any ordering of one element from another or the order of manufacture, and the use of the ordinal numbers is only used to distinguish one element having a certain name from another element having a same name.

Similarly, it should be appreciated that in the foregoing description of exemplary embodiments of the disclosure, various features of the disclosure are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various disclosed aspects. However, the disclosed method should not be interpreted as reflecting an intention that: that is, the claimed disclosure requires more features than are expressly recited in each claim. Rather, as the following claims reflect, disclosed aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the claims following the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of this disclosure.

The above-mentioned embodiments are intended to illustrate the objects, aspects and advantages of the present disclosure in further detail, and it should be understood that the above-mentioned embodiments are only illustrative of the present disclosure and are not intended to limit the present disclosure, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present disclosure should be included in the scope of the present disclosure.

Claims

1. An LTCC high voltage transformer, comprising in order from top to bottom: the upper side column, the magnetic core middle column and the lower side column; further comprising:

a primary coil and a secondary coil fired in the magnetic core center posts;

2. The LTCC high voltage transformer of claim 1, further comprising:

and the connecting holes are respectively arranged on the first medium.

3. The LTCC high voltage transformer of claim 1, wherein the material of the upper leg is a high magnetic permeability material having a magnetic permeability of no less than 400.

4. The LTCC high voltage transformer of claim 1, wherein the material of the lower leg is a high magnetic permeability material having a magnetic permeability of no less than 400.

5. The LTCC high voltage transformer of claim 1, wherein the material of the core legs is a low permeability material having a permeability of no greater than 100.

6. The LTCC high voltage transformer of claim 1, wherein the upper leg and the lower leg have a relative permeability greater than a relative permeability of the center leg of the magnetic core.

7. The LTCC high voltage transformer of claim 1, wherein a plurality of the second dielectrics are filled between adjacent primary windings.