WO2023138564A1

WO2023138564A1 - Magnetic integrated matrix transformer and isolated dc/dc converter

Info

Publication number: WO2023138564A1
Application number: PCT/CN2023/072555
Authority: WO
Inventors: 陈乾宏; 陈俊杰; 朱俊辉; 徐幸灿; 张斌; 柯光洁; 徐立刚; 温振霖; 任小永; 张之梁
Original assignee: 南京航空航天大学; 江苏展芯半导体技术有限公司
Priority date: 2022-01-20
Filing date: 2023-01-17
Publication date: 2023-07-27
Also published as: CN114093620B; CN114093620A

Abstract

The present invention belongs to the technical field of power electronics. Disclosed are a magnetic integrated matrix transformer and an isolated DC/DC converter. The magnetic integrated matrix transformer comprises a magnetic core, a primary winding, a secondary winding and a rectification unit, wherein the magnetic core is provided with a base; a middle column and at least three side columns are formed on the base; at least one secondary winding is wound on the magnetic core; each secondary winding is at least wound on two adjacent side columns; and the middle column is used for winding the primary winding. By means of the present invention, a secondary winding structure of a transformer is flexibly configured without changing a magnetic core, and any turn ratio of the transformer and the output of any number of paths of secondary sides are realized, such that the volume and weight of the transformer can be reduced, thereby increasing the power density of a converter; and the requirements of the converter for frequency ranges in different operating occasions can also be met, such that a magnetic part has flexibility and universality. Moreover, secondary windings of the transformer also have a current equalization effect when being arranged in an orthogonal manner, and a good heat dissipation effect can also be achieved using a metal shell wrapping the magnetic core.

Description

A Magnetic Integrated Matrix Transformer and Isolated DC/DC Converter

technical field

The invention relates to a magnetic integrated matrix transformer and an isolated DC/DC converter based on the magnetic integrated matrix transformer, belonging to the technical field of power electronics.

Background technique

With the development of power electronics technology and the progress of high-frequency semiconductor devices, switching converters are developing in the direction of high frequency, integration and modularization. High frequency, high efficiency, high power density and integration are the development trends of switching converters. At the same time, due to the increasing demand for data center power supplies and high dynamic response power supplies, switching converters are also developing towards low-voltage and high-current applications. Traditional transformers have been difficult to meet the requirements of miniaturization and high power density. In order to improve the efficiency and power density of this type of converter and reduce the uneven current caused by parallel connection of devices, matrix transformers with input windings connected in series and output windings connected in parallel are widely used in isolated DC/DC converters such as LLC resonant converters and phase-shifted full-bridge converters.

Due to the demand for miniaturization of the switching converter, increasing the switching frequency is one of the effective means to reduce the size and weight of the passive components of the converter, thereby increasing its power density. However, increasing the frequency increases additional loss on the one hand, and reduces the utilization rate of the magnetic core on the other hand. In addition, if the converter operates in a wider frequency range, it will bring about the problem of a larger transformer size. Therefore, the current matrix transformer design often cannot take into account the requirements of high frequency, small size and high efficiency of the converter. Considering that magnetic components are the key to limit the efficiency and power density of converters, magnetic integration technology has become an effective way to reduce the loss of magnetic parts and reduce the volume and weight of converters.

Magnetically integrated matrix transformers, such as D.Huang, S.Ji, FCLee, "LLC Resonant Converter With Matrix Transformer", IEEE-TPE, 2014pp.4339-4347 integrate multiple separated magnetic cores into a single integrated magnetic core, make full use of the magnetic core structure and winding structure of the transformer, and reconstruct and optimize the magnetic core structure based on the customized magnetic core to realize the integrated transformer in one magnetic core. However, this type of magnetically integrated matrix transformer solution uses a lot of iron and has a large loss. At the same time, the existing magnetic integrated matrix transformer is a customized product, which cannot be changed after being designed according to a certain gain and frequency range index, which is not flexible enough and not universal. When the converter is applied in different working occasions and the design indicators of the converter such as the transformer turn ratio or the number of secondary circuits change, it is necessary to redesign and customize new magnetic parts. Not only the design process is complicated, but also time-consuming. S.WANG, H.WU, FCLEEE, ET Al. 2017pp.9072-9082 In the low-voltage and large current LLC resonance converter, the four-circular magnetic column structure magnetic core is used to integrate magnetic parts of the matrix transformer However, in this type of integration, the primary and secondary windings of the transformer need to turn around the magnetic column in sequence. The overall planar size of the magnetic core and the footprint of the transformer winding are not significantly improved, and the path and resistance of the primary winding are relatively large.

In addition to the design freedom of the integrated magnetic core, the overall size, volume and weight, and the copper loss of the primary and secondary windings of the transformer, there is still room for optimization. The current sharing characteristics of the integrated unit also need to be fully considered to ensure that the magnetic flux of the transformer is balanced and there are no concentrated hot spots. Most of the current magnetic integrated matrix transformers use compact copper foil in the printed circuit board (PCB) to replace the round copper wire of the traditional power transformer, which can reduce the volume of the power transformer and reduce the AC loss of the winding at high frequencies. However, when the PCB winding on the secondary side of the transformer has multiple outputs, whether the magnetic circuit is asymmetrical, the winding parameters are inconsistent, or the secondary side is connected in parallel, it will bring current sharing problems to the converter. At the same time, when the integration level of the transformer is further improved, excellent heat dissipation performance is also a necessary condition to ensure that the integrated magnetic converter can operate stably and become practical. However, the existing integrated magnetic converter is still limited by temperature rise.

Contents of the invention

The object of the present invention is to provide a magnetically integrated matrix transformer structure for the problems of poor flexibility and lack of versatility of the matrix transformer in the existing isolated DC/DC converter.

Another object of the present invention is to provide an isolated DC/DC converter.

Concrete technical scheme of the present invention is as follows:

A magnetic integrated matrix transformer, comprising a magnetic core, a primary winding, a secondary winding and a rectifier unit, the magnetic core is provided with a base, a central column and at least three side columns are formed on the base; at least one secondary winding is wound on the magnetic core, each secondary winding is wound on at least two adjacent side columns, each side column is wound by at least one secondary winding, the central column is used for winding the primary winding, the magnetic core and the secondary winding wound on the side columns form a transformer assembly; the magnetic integrated matrix transformer consists of two structures The same transformer components are combined, and the two transformer components are rotated 90° or 180° to be misplaced and combined. After the combination, the central columns of the two are aligned and connected, and the side columns are aligned and connected. At least one set of aligned side columns is simultaneously wound by two secondary windings;

The primary winding is wound on the center leg of one magnetic core, or wound on the center legs of two magnetic cores at the same time.

Further, each side column on the magnetic core is a cylinder or a polygonal column, and is located on a concentric circle centered on the central column or on a regular polygon centered on the central column.

Further, the number of side legs wound by each secondary winding is the same.

Further, when the rectification unit is full-wave rectification, each or two secondary windings on the magnetic core form one output through the rectification unit; when the rectification unit is full-bridge rectification, every two secondary windings on the magnetic core form one output through the rectification unit.

Further, the exterior of the two sets of transformer assemblies is coated with a metal shell, and a heat-conducting insulating pad is provided between the metal shell and the transformer assembly, and the metal shell is connected to the outlet end of the transformer assembly or the rectifier unit that is at the same potential as the output voltage V _o to form a closed path for the secondary current.

Further, in the magnetic core, the effective magnetic permeability area of the central column is A _{e_c} , the effective magnetic permeability area of a single side column is A _{e_s} , the primary and secondary side turns ratio of the magnetic integrated matrix transformer is N _p /N _s , the number of turns of the primary side winding around the center column is n _pt , and the number of turns of a single secondary winding around m _s side columns is n _sq , then the primary and secondary side turns ratio satisfies the following relationship:

Further, the primary winding and the secondary winding adopt planar winding or wound winding.

Further, the magnetic core is made of ferrite, microcrystalline, ultrafine crystal or permalloy; the metal shell is made of aluminum alloy, silver, gold or copper; the primary and secondary windings are specifically made of copper wire, litz wire, PCB winding or copper foil.

An isolated DC/DC converter, using the magnetic integrated matrix transformer structure, by changing the number of secondary windings of the magnetic integrated matrix transformer, the number of side columns wound by the secondary windings, or changing the number of upper columns on the magnetic core, to adjust the output gain of the isolated DC/DC converter, or to expand the switching frequency range, or to reduce the size of the magnetic core.

The number of secondary windings of the transformer, the number of winding side columns of the secondary winding and the effective magnetic permeability area can be flexibly configured according to the requirements of any turn ratio of the transformer or any number of secondary outputs, which can not only reduce the volume and weight of the magnetic parts, but also adapt to the frequency range requirements of the converter in different working situations, adjust the output gain of the converter, and make the matrix transformer flexible and versatile.

The magnetic integrated matrix transformer of the present invention is suitable for isolated DC/DC converters such as LLC resonant converters, phase-shifting full-bridge converters, etc., which contain primary side series and secondary side multi-channel parallel matrix transformers. The secondary side rectification circuit can use full bridge rectification or full wave rectification circuit.

Compared with the prior art, the present invention has the following advantages:

1. The present invention provides a magnetically integrated matrix transformer, which adopts a magnetic core with a central column and at least three side columns, and each secondary winding is wound on at least two adjacent side columns, so as to improve the utilization rate of the magnetic core and the efficiency of the converter.

2. The present invention designs a relatively general magnetic structure. By flexibly configuring the number of transformer secondary windings and the number of winding side columns, a magnetic core structure can be used to adapt to the design of converters in different workplaces, so as to meet the needs of any transformer turn ratio or secondary output.

3. In the magnetic integrated matrix transformer of the present invention, when the two transformer components are rotated 90° and combined with each other, Each secondary winding has magnetic flux coupling with another orthogonally adjacent winding, so as to ensure magnetic flux balance and realize automatic compensation current sharing.

4. In the present invention, the primary winding of the transformer surrounds the middle column of the magnetic core with a chain of turns, the path of the chain of turns is short, and the resistance is small, which is beneficial to saving copper and improving the efficiency of the converter.

5. In the magnetic integrated matrix transformer of the present invention, the cladding structure of the metal shell improves the heat dissipation performance of the device and the magnetic core, and improves the overall efficiency of the converter.

6. The isolated DC/DC converter of the present invention can not only reduce the size of the magnetic core, improve the utilization rate of the magnetic core and the efficiency of the converter, but also improve the freedom and flexibility of the output gain of the converter and the adjustment of the operating frequency range by changing the number of winding side columns and the number of upper side columns of the magnetic core.

7. The isolated DC/DC converter designed by the present invention meets the actual requirements of output gain adjustment and working frequency range conversion through the transformer magnetic core structure and secondary winding winding method.

Description of drawings

The accompanying drawings described here are used to provide a further understanding of the present invention and constitute a part of the application. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations to the present invention.

Figure 1 is a schematic diagram of an existing LLC resonant converter;

Fig. 2 is the plane schematic diagram that the primary and secondary windings of the transformer of the present invention are wound around the magnetic core column;

3A and FIG. 3B are respectively one of the lower and upper square magnetic core quadrangular column transformer assembly structures of the embodiment;

Fig. 4A and Fig. 4B are respectively the lower part and the upper part of the square magnetic core quadrangular column type transformer assembly structure of the embodiment;

Fig. 5A and Fig. 5B are respectively the lower part and the upper part of the hexagonal magnetic core hexagonal column type transformer assembly structure of the embodiment;

Fig. 6A and Fig. 6B are respectively the lower part and the upper part of the octagonal magnetic core octagonal column transformer assembly structure of the embodiment;

FIG. 7 is a schematic structural diagram of a full-wave rectification magnetic integrated matrix transformer wound on two adjacent side columns in an embodiment;

Fig. 8A and Fig. 8B are respectively the structural plane schematic diagrams of the transformer sub-units of the lower part and the upper part of the magnetic integrated matrix transformer in the embodiment;

Fig. 9 is a side view structural schematic diagram of a transformer subunit structure in the magnetic integrated matrix transformer of the embodiment;

Fig. 10 is a schematic diagram of the secondary winding shared side columns in the upper and lower transformer assemblies of the magnetic integrated matrix transformer in the embodiment;

Fig. 11 is a schematic diagram of the secondary winding current and magnetic flux flow of the magnetic integrated matrix transformer in the embodiment;

Fig. 12 is a side-view structure schematic diagram and a heat conduction schematic diagram of the magnetic integrated matrix transformer in the embodiment;

Fig. 13 is a schematic diagram of the configuration and distribution of the primary and secondary windings of the magnetic integrated matrix transformer in the embodiment;

Fig. 14 is a schematic structural diagram of a full-wave rectification type magnetic integrated matrix transformer wound around three adjacent side columns in an embodiment;

15A and 15B are schematic plan views of the structure of the transformer subunits in the lower and upper parts of the magnetic integrated matrix transformer in the embodiment, respectively;

Fig. 16 is a side-view structure schematic diagram of a transformer subunit structure in the magnetic integrated matrix transformer in the embodiment;

Fig. 17 is a schematic structural diagram of a full-wave rectification type magnetic integrated matrix transformer wound around four adjacent side columns in an embodiment;

18A and 18B are schematic plan views of the structure of the transformer subunits in the lower and upper parts of the magnetic integrated matrix transformer in the embodiment, respectively;

Fig. 19 is a side view structural diagram of a transformer subunit structure in the magnetic integrated matrix transformer in the embodiment;

Fig. 20 is a schematic structural diagram of a full-bridge rectifying magnetically integrated matrix transformer winding two adjacent side columns in an embodiment;

Fig. 21A and Fig. 21B are respectively the structural plane schematic diagrams of the transformer subunits in the lower part and the upper part of the magnetic integration matrix transformer in the embodiment;

Fig. 22 is a schematic side view of a transformer subunit structure in the magnetic integrated matrix transformer in the embodiment;

Figure 23 is a three-dimensional simulation model of the magnetic integrated matrix transformer built in Maxwell.

Fig. 24 is the magnetic density distribution result diagram of the magnetic integration matrix transformer finite element simulation;

Figure 25 is the experimental waveform of the LLC type DC/DC isolation converter prototype;

Figure 26 shows the distribution of secondary side synchronous rectifier tubes of the LLC type DC/DC isolation converter;

Figure 27 shows the heat generation of the synchronous rectifier tube on the secondary side of the LLC type DC/DC isolation converter (at full load for 1 minute);

Figure 28 shows the heat generation of the magnetic integrated matrix transformer of the LLC type DC/DC isolation converter (when the machine is fully loaded for 5 minutes).

Explanation of symbols in the figure:

001 is the magnetic core; 002 is the primary winding; 003, 003A and 003B are the secondary windings; 004 is the middle column of the magnetic core; 005 is the side column of the magnetic core; Metal shell; 102, 102A and 102B are full-wave secondary windings; 103 is the first outlet end of full-wave secondary winding; 104 is full-wave secondary winding 105, 105A and 105B are the center tap terminals of the full-wave secondary winding; 106A and 106B are the secondary windings of the full bridge; 107 is the first outgoing terminal of the secondary winding of the full bridge; 108 is the second outgoing terminal of the secondary winding of the full bridge; 109 is an insulating thermal pad;

The name of the main symbol in the figure: V_in- Input side DC power supply, C_in- Input filter capacitor, V_o- Output side DC power supply, C_f- output filter capacitor, Q₁, Q₂-Primary switch, SR₁、SR₂、SR₃、SR₄、SR₅、SR₆、SR_2n-1、SR_2n- Secondary switch, C_r- Resonant capacitance, L_r- Resonant inductance, L_m1, L_m2, L_m3, L_mn- magnetizing inductance, i_p- primary winding current, i_s0i_s1i_s2i_s3i_s4i_s5i_s6i_sn-Single secondary winding current, T_s1-Single secondary winding, T_s2-Single secondary winding, M_s12-Mutual inductance of two mutually coupled secondary windings, A_{e_c}- the effective permeable area of the pole in the core, A_{e_s}- effective permeable area of a single core side leg, SR_1a、SR_1b、SR_2a、SR_2b- Synchronous rectifiers on the secondary side.

Detailed ways

For ease of description, spatially relative terms such as "upper," "lower," "left," and "right" may be used herein to describe the relationship of one element or feature relative to another element or feature shown in the figures. It will be understood that the spatial terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as "below" other elements or features would then be positioned "above" the other elements or features. Thus, the exemplary term "below" can encompass both an orientation of above and below, the device can be otherwise positioned (rotated 90° or at other orientations), and the spatially relative specifications used herein should be interpreted accordingly.

Isolated DC/DC converters include LLC resonant converters, phase-shifted full-bridge converters, etc. Taking the LLC resonant converter as an example, the schematic diagram of the existing LLC resonant converter before integration is shown in Figure 1, which includes n discrete transformers and has n outputs on the secondary side.

In order to reduce volume and improve efficiency, the present invention adopts magnetic integration technology to integrate n discrete transformers into one magnetic part at the same time. The magnetic integrated matrix transformer of the present invention is composed of two identical transformer assemblies, the transformer assembly includes a magnetic core and a secondary winding wound on the magnetic core; each magnetic core is provided with a base, and a central column and at least three side columns are formed on the base; each magnetic core is wound with at least one secondary winding, each secondary winding is wound on at least two adjacent side columns, the central column is used for winding the primary winding, and the magnetic core and the secondary windings wound on the side columns form a transformer assembly.

Generally, only one set of primary windings can be wound on one transformer assembly, or it can be wound on two combined transformers at the same time.

The magnetic integrated matrix transformer is composed of two transformer components with the same structure. The same structure refers to the same structure of the magnetic core and the same winding method of the secondary winding. The two transformer components are rotated 90° or 180° with each other and combined, after combination The central columns of the two are aligned and connected, and the side columns are aligned and connected. At least one set of aligned side columns is simultaneously wound by two secondary windings.

Fig. 2 is a schematic plan view of the winding of the primary winding and the secondary winding in the transformer assembly of the present invention around the magnetic core. The magnetic core includes a central column and n _s side columns (n _s is not less than 3), and each side column is evenly located on a concentric circle centered on the central column.

The primary winding is wound on the middle leg, where the solid line represents the secondary winding wound on the lower leg of the magnetic core, and the current flowing through it is represented by _is0 , _is2 , i _s4 , i _s6 ...; the dotted line represents the secondary winding wound on the leg of the upper magnetic core, and the current flowing through it is represented by _is1 , _is3 , _is5 ...; each secondary winding is wound on two leg.

图2中两个变压器组件结构相同，两个变压器组件相互之间旋转180°错位组合，拼合后两个变压器组件中至少1组对正相接的边柱被两个副边绕组同时绕制，即存在磁通交叉耦合，如图中i _s0所在副边绕组与i _s1所在副边绕组存在重叠；i _s1所在副边绕组与i _s2所在副边绕组存在重叠；i _s2所在副边绕组与i _s3所在副边绕组存在重叠；i _s3所在副边绕组与i _s4所在副边绕组存在重叠；i _s4所在副边绕组与i _s5所在副边绕组存在重叠；i _s5所在副边绕组与i _s6所在副边绕组存在重叠。 i _sn means that the number of side columns and the number of secondary windings can be changed arbitrarily. Similarly, the number of side legs wound by the secondary winding and the number of aligned and connected side legs that are simultaneously wound can also be changed arbitrarily. Wherein, the number of side columns is at least 3, the number of side columns wound by the secondary side winding is at least 2, and the number of aligned and connected side columns that are simultaneously wound is at least 1.

The technical solution of the present invention will be described in detail below in conjunction with the accompanying drawings.

Transformer assembly embodiment 1:

In this example, the magnetic core adopts a square structure. For the lower quadrangular column transformer assembly with square magnetic core, refer to FIG. 3A , and for the upper square magnetic core quadrangular column transformer assembly, refer to FIG. 3B . The core is provided with a base, the base is provided with a center column and four side columns, and the four side columns are evenly distributed on a square centered on the center column; two secondary windings are wound on the side columns, each secondary winding is wound on two adjacent side columns, and the center column is used to wind the primary winding, and the magnetic core and the secondary windings wound on the side columns form a transformer assembly; two transformer assemblies with the same structural design are rotated 90° to each other and combined, and after the combination, the center columns of the two are aligned and connected, and the side columns are aligned. , the secondary windings of the two are perpendicular to each other, and each group of side columns that are aligned with each other is wound by the upper and lower secondary windings. It is further assembled into a magnetically integrated matrix transformer. The primary winding is wound on the center leg of one magnetic core, or wound on the center legs of two magnetic cores at the same time.

As shown in Figure 3A, in this example, the discrete magnetic cores in the traditional matrix transformer are integrated to obtain a transformer assembly. The primary winding 002 is wound on the middle column, and the secondary winding 003 can be wound on any number of side columns n _sq (2≤n _sq ≤4). Similarly, cores every third or every fourth Each adjacent side column can be wound around a secondary winding, and the number of secondary windings can be freely configured. On the one hand, the magnetic integration structure can reduce the volume of the magnetic parts, thereby increasing the power density of the converter; on the other hand, it provides a relatively general magnetic part structure design, which can not only meet the requirements of any turn ratio of the transformer or any number of secondary outputs, but also adapt to the needs of different operating frequencies of the converter, thereby improving the degree of freedom and flexibility of the output gain of the converter and the adjustment of the operating frequency range.

Transformer assembly embodiment 2:

In this example, the magnetic core adopts a square structure, the lower quadrangular column transformer assembly with square magnetic core refers to FIG. 4A , and the upper square magnetic core quadrangular column transformer assembly refers to FIG. 4B . The magnetic core is provided with a base, the base is provided with a central column and four side columns, and the four side columns are evenly distributed on a square centered on the central column; two secondary windings are wound on the side columns, one secondary winding 003A is wound on three adjacent side columns, the other secondary winding 003B is wound on two adjacent side columns, the central column is used to wind the primary winding 002, the magnetic core and the secondary winding wound on the side columns form a transformer assembly; two transformer assemblies with the same structural design rotate with each other 180° dislocation combination, after the combination, the center columns of the two are aligned and connected, and the side columns are aligned and connected, and each set of aligned side columns is simultaneously wound by the upper and lower secondary windings. It is further assembled into a magnetically integrated matrix transformer.

As shown in Fig. 4A, in this example, the discrete magnetic cores in the traditional matrix transformer are integrated to obtain a transformer assembly. The primary winding 002 is wound on the central column, and the secondary winding can be wound on any number of side columns n _sq (2≤n _sq ≤6). In this example, a secondary winding 003A is wound around two adjacent side columns and a secondary winding 003B is wound around three adjacent side columns on each magnetic core, and a total of two secondary windings are wound. Similarly, the combination of other secondary windings of the magnetic core can be combined arbitrarily, and the number of secondary windings can be freely configured. In addition to the advantages of transformer component embodiment 1, the magnetic core adopting this structure can realize output of different voltages between secondary sides, and is suitable for simultaneous realization of main power and auxiliary power or valley-bottom open sampling circuit.

Transformer assembly embodiment 3:

In this example, the magnetic core adopts a regular hexagonal structure. Refer to FIG. 5A for the lower hexagonal magnetic core hexagonal column transformer assembly, and refer to FIG. 5B for the upper hexagonal magnetic core hexagonal columnar transformer assembly. The magnetic core is provided with a base, the base is provided with a central column and six side columns, and the six side columns are evenly distributed on a regular hexagon centered on the central column; three secondary windings are wound on the six side columns, each secondary winding is wound on two adjacent side columns, and the central column is used to wind the primary winding, and the magnetic core and the secondary winding wound on the side columns form a transformer assembly; Alignment is connected, and each group is aligned with each other The side column is wound by upper and lower secondary side windings. It is further assembled into a magnetically integrated matrix transformer. The primary winding is wound on the center leg of one magnetic core, or wound on the center legs of two magnetic cores at the same time.

As shown in Fig. 5A, in this example, the discrete magnetic cores in the traditional matrix transformer are integrated to obtain a transformer assembly. The primary winding 002 is wound on the middle column, and the secondary winding can be wound on any number of side columns n _sq (2≤n _sq ≤6). In this example, the magnetic core is used to wind a secondary winding every two adjacent columns, and a total of three secondary windings are wound. Similarly, the magnetic core can be wound with a secondary winding every three or every four or every five or every six adjacent columns, and the number of secondary windings can be freely configured. In addition to the advantages of the first embodiment of the transformer assembly, the magnetic core with this structure can further adjust the output gain of the converter by changing the number of columns on the upper side of the magnetic core under the same magnetic permeability area, reduce the volume of the magnetic parts, and adapt to a wider frequency range.

Transformer assembly embodiment 4:

In this example, the magnetic core adopts a regular octagonal structure. Refer to FIG. 6A for the lower octagonal magnetic core octagonal column transformer assembly, and refer to FIG. 6B for the upper octagonal magnetic core octagonal columnar transformer assembly. The magnetic core is provided with a base, and the middle part of the base is provided with a central column and eight side columns, and the eight side columns are evenly distributed on a regular octagon centered on the central column; two secondary windings are wound on the side columns, each secondary winding is wound on four adjacent side columns, and the central column is used to wind the primary winding, and the magnetic core and the secondary windings wound on the side columns form a transformer assembly; The columns are aligned and connected, and the secondary side windings of the two are perpendicular to each other, and each group of aligned side columns is wound by the upper and lower secondary side windings. It is further assembled into a magnetically integrated matrix transformer. The primary winding is wound on the center leg of one magnetic core, or wound on the center legs of two magnetic cores at the same time.

As shown in Fig. 6A, in this example, the discrete magnetic cores in the traditional matrix transformer are integrated to obtain a transformer assembly. The primary winding 002 is wound on the middle column, and the secondary winding can be wound on any number of side columns n _sq (2≤n _sq ≤8). In this example, a magnetic core is used to wind a secondary winding every four adjacent columns, and a total of two secondary windings are wound. Similarly, a magnetic core can be wound with a secondary winding every two, every three, every five, every six, every seven, or every eight adjacent columns, and the number of secondary windings can be freely combined and configured. In addition to the advantages of the first embodiment of the transformer assembly, the magnetic core adopting this structure can further adjust the output gain of the converter, reduce the volume of the magnetic parts, and adapt to a wider frequency range by changing the number of columns on the upper side of the magnetic core under the same magnetic permeability area.

The structure of the transformer assembly involved in the present invention is not limited to the structures involved in the above embodiments. According to the above embodiments, the number of side columns of the transformer assembly structure of the present invention can be increased or decreased, and the shape of the magnetic core can be changed accordingly. In particular, when the number of side columns of the magnetic core is ²ⁿ (n=2, 3, 4...), as shown in Fig. 4A and Fig. 4B or Fig. 6A and Fig. 6B, the two transformer components of the magnetic integrated matrix transformer can be rotated 90° to each other and misplaced and assembled. At this time, the turn chain paths of the respective secondary windings of the two transformer components are in an orthogonal form, so that the magnetic fluxes of the secondary windings are cross-coupled to each other. It is beneficial to achieve current sharing.

The following embodiments of the present invention are described by taking a transformer assembly with a quadrangular column structure with a square magnetic core as an example.

Embodiment 1 of magnetic integrated matrix transformer:

As shown in Figure 7, the structure of the magnetic integrated matrix transformer of the present invention adopts the structure of the transformer assembly embodiment 1, including five parts: magnetic core 001, primary winding 002, secondary winding 003, rectification units 100A and 100B, and metal shell 101. Among them, the magnetic core 001 is an integrated magnetic part adopting a square magnetic core with four sides, and the magnetic core material can be made of ferrite, microcrystalline, ultrafine crystal or permalloy. Windings 002 and 003 can be planar windings or wound windings, including copper wires, litz wires, PCB windings, copper foil, etc. The magnetic core 001 and the secondary winding 003 form a transformer assembly. The rectification units 100A and 100B are composed of power switch tubes and capacitors or diodes and capacitors. The metal shell 101 is made of copper, aluminum alloy, silver, gold and the like.

In this embodiment, the secondary winding 003 adopts a full-wave rectification structure. The number S of full-wave secondary windings (S=2*n, n=1, 2, 3, . . . ) can be flexibly configured according to the converter gain and frequency range.

Taking the case where the secondary side has four outputs as an example, there are four full-wave windings in total, and one full-wave secondary winding is wound on two adjacent side columns. 8A and 8B are schematic plan views of the structure of two transformer subunits. FIG. 8A is the lower transformer subunit, and FIG. 8B is the upper transformer subunit after being rotated by 90°. Each transformer subunit includes a transformer assembly, a primary winding, a rectifier unit and a metal case. Among them, two primary side winding components are respectively wound on the middle pole of the magnetic core of the upper and lower transformer sub-units. The metal shell is also divided into two parts, which are respectively coated on the outside of the upper and lower transformer sub-units. The two secondary windings are respectively connected to the rectification unit 100A and the rectification unit 100B, and a metal shell 101 is provided outside.

FIG. 9 shows a schematic perspective view of the above structure. Wherein the primary winding 002 surrounds the middle column of the magnetic core; the metal shell 101 wraps the outer surface of the magnetic core. One full-wave secondary winding 102A or 102B contains two full-wave windings, each full-wave winding has three terminals, and each full-wave secondary winding is electrically connected to the metal shell 101 and the rectifier unit 100 . The specific connection form is: one full-wave secondary winding 102A or 102B corresponds to two rectifier units 100, and each full-wave secondary winding 102A or 102B includes a first outlet terminal 103, a second outlet terminal 104, and a center tap terminal 105. _o , connected to the metal shell 101 . The positions of the two full-wave secondary windings 102A and 102B are 180° relative to each other, and are wound up and down in layers.

The magnetic integrated matrix transformer shown in Figure 7 is composed of two upper and lower structures as shown in Figure 9, and the two are rotated 90° and combined with each other. After the combination, the middle columns of the two are aligned and connected, and the side columns are aligned. In the upper and lower transformer components, The secondary windings with the same name and the same end share a set of side columns. Referring to FIG. 10, the secondary winding T _s1 in the lower transformer assembly and the secondary winding T _s2 in the upper transformer assembly are simultaneously wound on a group of positively connected side columns 006. By sharing the side leg 006 of the magnetic core, the mutual cross-coupling M _s12 of the magnetic flux can exist between the secondary windings, so as to ensure the balance of the magnetic flux and realize the automatic compensation current sharing.

After adopting the above method, the turn chain path of the secondary winding of the transformer is shown in Fig. 11 . The secondary winding current flows sequentially through the first outlet terminal 103, the full-wave secondary winding 102, the center tap terminal 105, the metal shell 101, and the rectifier unit 100, thereby forming a closed loop around the top cover of the magnetic core. The metal shell 101 is responsible for coupling the main magnetic flux and guiding it, and is also used for combining the transformer components. The metal shell 101 includes a top cover plane and no less than two side planes, and wraps the top cover outer plane of the magnetic core and at least two opposite side planes of the magnetic core. As shown in FIG. 12 , the rectifier unit 100 is connected to the inner plane of the top cover of the metal case 101 through an insulating heat conduction pad 109 , and this connection method can also be used between the magnetic core 001 and the inner plane of the top cover of the metal case 101 . The material of the insulating heat conduction pad 109 can be selected from silica gel, silicone grease, alumina ceramics and the like.

Referring to Fig. 13 , the effective magnetic permeability area of the central column 004 is A _{e_c} , and the primary windings surround the central column with a chain of turns; the effective magnetic permeability area of a single side column 005 is A _{e_s} . When the primary and secondary turns ratio of the primary and secondary parallel matrix transformers is N _p /N _s , the number of turns of the primary winding around the center column is n _pt , and the number of turns of a single secondary winding around m _s side columns is n _sq , the primary and secondary turns ratio satisfies the following relationship:

Among them, n _pt ×A _{e_c} represents the total effective magnetic permeability area of the central column to which the turns of the primary winding are linked, and m _s ×n _sq ×A _{e_s} represents the entire effective magnetic permeability area of the side column to which the turns of the secondary winding of the matrix transformer are linked.

Embodiment 1 of the isolated DC/DC converter:

Based on the first embodiment of the magnetic integrated matrix transformer described above, this example provides an isolated DC/DC converter. Wherein, each isolated DC/DC converter includes a magnetically integrated matrix transformer, and the secondary side constitutes multiple outputs. On the one hand, by changing the number of secondary windings of the transformer or the number of side legs wound by a single secondary winding, or changing the size of the magnetic core, it can adapt to the needs of any turn ratio of the transformer or any number of secondary outputs, thereby adjusting the output gain of the converter.

On the other hand, taking the LLC resonant converter as an example, when the primary and secondary sides of the converter are not separated, according to the law of electromagnetic induction, that is, volt-second balance, the number of turns of the secondary winding of the transformer satisfies the relational expression:

Among them, V _o is the output voltage of the converter, f _smin is the minimum value of the switching frequency of the converter, and ΔB is the magnetic flux variation of the transformer core. In order to ensure safe operation of the transformer within the entire switching frequency range, the flux variation ΔB usually takes a preset upper limit value ΔB _max .

① It can be seen from the above formula that when the output voltage V _o , the number of secondary turns N _s and the effective magnetic permeability area A _{e_s} of the side columns are constant, the more the number n _sq of the side columns wound by a single secondary winding, the smaller the minimum switching frequency f _smin of the converter. Therefore, the switching frequency range of the converter meeting the ΔB _max limit can be very wide without affecting the converter gain and transformer size, and without increasing the number of transformer winding turns. Therefore, in this embodiment, the same magnetic core structure can be used to meet the frequency range requirements of converters in different working situations, so that the matrix transformer has flexibility and versatility. In particular, when the secondary winding is a PCB-type winding, the fewer turns reduces the number of holes in the PCB-type winding, which can reduce the loss of the holes, and is beneficial to improve the efficiency and heat dissipation of the converter.

②When the effective magnetic permeability area A _{e_s} of the side column needs to be reduced due to the size requirement of the transformer, the output voltage V _o and the number of secondary turns N _s can also be kept unchanged by increasing the number n _sq of the side column wound by the single secondary side winding. Since a slight reduction in the effective magnetic permeability area A _{e_s} of the side columns has a more obvious effect on the size of the magnetic core, and the increase in the number n _sq of the side columns wound by a single secondary winding has a greater impact on the reduction of f _smin , so compared with the traditional solution, the present invention can use a smaller-sized magnetic core to increase the power density of the converter.

Embodiment 2 of magnetic integrated matrix transformer:

As shown in Figure 14, the magnetic integrated matrix transformer of the present invention adopts a square magnetic core structure, including five parts: magnetic core 001, primary winding 002, secondary winding 003, rectification unit 100A, rectification unit 100B and metal shell 101. Among them, the magnetic core 001 is an integrated magnetic part adopting a square magnetic core with four sides, and the magnetic core material can be made of ferrite, microcrystalline, ultrafine crystal or permalloy. Windings 002 and 003 can be planar windings or wound windings, including copper wires, litz wires, PCB windings, copper foil, etc. The magnetic core 001 and the two secondary windings 003 form a transformer assembly. Both the rectification units 100A and 100B are composed of power switch tubes and capacitors or diodes and capacitors. The metal shell 101 is made of copper, aluminum alloy, silver, gold and the like.

The difference between this embodiment and Embodiment 1 of the magnetic integrated matrix transformer is that the magnetic integrated matrix transformer with the secondary full-wave rectifier winding structure takes the secondary output as an example, there are two full-wave windings in total, and one full-wave secondary winding is wound on three adjacent side columns. 15A and 15B are schematic plan views of the structure of two transformer subunits. FIG. 15A is the lower transformer subunit, and FIG. 15B is the upper transformer subunit after being rotated by 180°. each transformer The transformer subunit includes a transformer assembly, a primary winding, a rectifier unit and a metal case. Among them, two primary side winding components are respectively wound on the middle pole of the magnetic core of the upper and lower transformer sub-units. The metal shell is also divided into two parts, respectively covering the outside of the upper and lower transformer sub-units. The two secondary windings are respectively connected to the rectification unit 100A and the rectification unit 100B, and a metal shell 101 is provided outside.

FIG. 16 shows a schematic perspective view of the above structure. Wherein the metal shell 101 is wrapped on the outer surface of the magnetic core. One full-wave secondary winding 102 includes two full-wave windings, and each full-wave winding has three terminals. Each full-wave secondary winding is electrically connected to the metal shell 101 and the rectifier unit 100 . The specific connection form is: the all -wave vice edge 102 corresponds to two rectified units 100, each full wave auxiliary wound group 102 includes the first line end 103, the second outline 104, the central tap end 105, the first outline 103 and the second outline 104 are each and a diode cathode connection in a rectification unit _100. Connect with metal shell 101. The positions of the two full-wave windings of one full-wave secondary winding 102 are mirror-symmetrical around the central column, and are wound up and down in layers.

The magnetically integrated matrix transformer shown in FIG. 14 is composed of two upper and lower structures as shown in FIG. 16 , and the primary winding 002 is sandwiched between the upper and lower transformer components. The two transformer components are rotated 180° and combined with each other. After the combination, the central columns of the two are aligned and connected, and the side columns are aligned and connected. Each set of side columns aligned with each other is wound by upper and lower side windings. In the upper and lower transformer components, the secondary windings with the same terminal and the same name share two sets of side columns.

In this embodiment, the winding path of the secondary winding of the transformer and the flexible configuration effect on the frequency range, magnetic core size, and converter gain are similar to those in the first embodiment, and will not be repeated here.

Embodiment 3 of magnetic integrated matrix transformer:

As shown in Figure 17, the magnetic integrated matrix transformer of the present invention adopts a square magnetic core structure, including four parts: a magnetic core 001, a primary winding 002, a secondary winding 003, and rectification units 100A and 100B. Among them, the magnetic core 001 is an integrated magnetic part adopting a square magnetic core with four sides, and the magnetic core material can be made of ferrite, microcrystalline, ultrafine crystal or permalloy. The primary winding 002 and the secondary winding 003 can be planar windings or wound windings, including copper wires, litz wires, PCB windings, copper foils, and the like. The magnetic core 001 and the secondary winding 003 form a transformer assembly. The rectification unit 100A and the rectification unit 100B are composed of a power switch tube and a capacitor or a diode and a capacitor.

The difference between this embodiment and Embodiment 1 of the magnetic integrated matrix transformer is that, taking the secondary side with two outputs as an example, there are two full-wave windings in total, and one full-wave secondary winding is wound on four adjacent side columns, and the metal shell 101 is not used in this embodiment. Figures 18A and 18B show the two transformations of the magnetic integrated matrix transformer using the secondary full-wave rectifier winding structure. Figure 18A is the lower transformer subunit, and Figure 18B is the upper transformer subunit rotated by 90°. Each transformer subunit includes a transformer assembly, a primary winding and a rectification unit. Among them, two primary side winding components are respectively wound on the middle pole of the magnetic core of the upper and lower transformer sub-units. The two secondary windings are respectively connected to the rectification unit 100A and the rectification unit 100B.

FIG. 19 shows a schematic perspective view of the above structure. One of the full-wave secondary windings 102 includes two full-wave windings, and each full-wave winding has four terminals. Each full-wave secondary winding is electrically connected to the rectifier unit 100 . The specific connection form is: one full-wave secondary winding 102 corresponds to two rectifier units 100, and each full-wave secondary winding 102 includes a first outlet 103, a second outlet 104, and center tap terminals 105A and 105B. _o . The positions of the two full-wave windings of one full-wave secondary winding 102 are mirror-symmetrical around the central column, and are wound up and down in layers.

The magnetically integrated matrix transformer shown in Figure 17 is composed of two upper and lower structures shown in Figure 19, and the primary winding 002 is sandwiched between the upper and lower transformer components. The two transformer components are rotated 90° to each other and combined. After the combination, the central columns of the two are aligned and connected, and the side columns are aligned and connected. The secondary windings of the two are perpendicular to each other. Each set of side columns aligned with each other is wound by upper and lower side windings. In the upper and lower transformer assemblies, the secondary windings with the same end of the same name share four sets of side columns.

Embodiment 4 of magnetic integrated matrix transformer:

Fig. 20 is a magnetic integrated matrix transformer of the present invention, which adopts a square magnetic core structure, including five parts: a magnetic core 001, a primary winding 002, a secondary winding 003, rectification units 100A and 100B, and a metal shell 101. Among them, the magnetic core 001 is an integrated magnetic part adopting a square magnetic core with four sides, and the magnetic core material can be made of ferrite, microcrystalline, ultrafine crystal or permalloy. Windings 002 and 003 can be planar windings or wound windings, including copper wires, litz wires, PCB windings, copper foil, etc. The magnetic core 001 and the secondary winding 003 form a transformer assembly. The rectification units 100A and 100B are composed of power switches and capacitors or diodes and capacitors. The metal shell 101 is made of copper, aluminum alloy, silver, gold and the like.

The difference between this embodiment and the magnetic integrated matrix transformer embodiment 1 is that the secondary winding 003 is arranged in a full-bridge rectification structure. The number S (S=2*n, n=1, 2, 3, . . . ) of the secondary winding of the full bridge can be flexibly configured according to the converter gain and frequency range.

Taking two outputs on the secondary side as an example, there are two full-bridge windings in total, and one full-bridge secondary winding contains two full-bridge secondary winding units. A full-bridge secondary winding is wound on two adjacent side columns. Figures 21A and 21B show the planar schematic diagrams of the two transformer subunit structures of the magnetically integrated matrix transformer using the secondary full-bridge rectifier winding structure. Figure 21A shows the transformer subunit at the lower part, and Figure 21B shows the transformer subunit at the upper part after being rotated by 90°. Each transformer subunit includes a transformer assembly, a primary winding, a rectifier unit and a metal case. Among them, two primary side winding components are respectively wound on the middle pole of the magnetic core of the upper and lower transformer sub-units. The metal shell is also divided into two parts, which are respectively coated on the outside of the upper and lower transformer sub-units. The two secondary windings are respectively connected to the rectification unit 100A and the rectification unit 100B, and a metal shell 101 is provided outside.

FIG. 22 shows a schematic perspective view of the above structure. Wherein the metal shell 101 is wrapped on the outer surface of the magnetic core. One full-bridge secondary winding includes two full-bridge secondary winding units 106A and 106B, and each full-bridge winding unit 106A or 106B includes two terminals. Each full-bridge secondary winding unit 106A or 106B is electrically connected to the metal case 101 and the rectifier unit 100 . The specific connection form is: one full-bridge secondary winding unit 106A or 106B corresponds to two rectifier units 100A and 100B, and each full-bridge secondary winding unit 106A or 106B includes a first outlet terminal 107 of the full-bridge secondary winding and a second outlet terminal 108 of the full-bridge secondary winding. The second outlet terminal 108 of the winding is connected to the anode of the diode or the source of the rectifier tube in another rectifier unit 100B, and the positive output terminal V _o of the rectifier unit is connected to the metal shell 101 . The positions of the two full-bridge winding units of one full-bridge secondary winding are mirror-symmetrical around the central column, and are wound on the same layer.

The magnetically integrated matrix transformer shown in Figure 20 is composed of two upper and lower structures as shown in Figure 22, and the primary winding 002 is sandwiched between the upper and lower transformer components. The two transformer components are rotated 90° to each other and combined. After the combination, the central columns of the two are aligned and connected, and the side columns are aligned and connected. The secondary windings of the two are perpendicular to each other. Each set of side columns aligned with each other is wound by upper and lower side windings. In the upper and lower transformer components, the secondary windings with the same terminal and the same name share a set of side columns.

The content described in this specification is only an illustration of the present invention. Those skilled in the technical field of the present invention can make various modifications or supplements to the described specific embodiments or adopt similar methods to replace them, as long as they do not deviate from the content of the present invention description or exceed the scope defined in the claims, all should belong to the protection scope of the present invention.

Test example one:

In order to verify the superiority and feasibility of the present invention, the Ansys Maxwell simulation software is used to carry out electromagnetic finite element simulation on the structure of the embodiment 1 of the magnetic integrated matrix transformer of the present invention shown in Figure 7. The three-dimensional simulation model of the magnetic integrated matrix transformer built in Maxwell is shown in Figure 23, and the magnetic density distribution result of the magnetic integrated matrix transformer finite element simulation is shown in Figure 24. It can be seen from the figure that the secondary windings with the same name and the same end in the upper and lower square magnetic core four-sided cylindrical transformer components share the side columns, so that there is mutual flux between the secondary windings Cross-coupling, the magnetic density at each side column of the magnetic core is basically the same, which proves that the magnetic integrated matrix transformer of the present invention can achieve better magnetic balance and current sharing effects.

Test embodiment two:

In order to verify the superiority and feasibility of the present invention, the structure of Embodiment 1 of the magnetic integrated matrix transformer of the present invention is used to realize a 200V-400V input, 10-14V output, and a rated power of 500W. The LLC DC/DC isolation converter prototype is manufactured. The metal shell material is copper material, the transformer turns ratio is 12:1, and the resonance frequency is 560kHz.

Referring to Fig. 25, the prototype can run stably under the working conditions of 300V input and 562kHz switching frequency, which proves the effectiveness and feasibility of the isolated DC/DC converter designed by the present invention. Referring to Figure 26 and Figure 27, it can be seen from the thermal imaging results when the prototype is fully loaded for 1 minute that the temperature of the synchronous rectifier SR _1a is 41.6°C, the temperature of the _synchronous rectifier SR _1b is 41.2°C, the temperature of the synchronous rectifier SR _2a is 41.3°C, and the temperature of the synchronous rectifier SR _2b is 41.5°C. The heating conditions of the rectifier tubes SR _2a and _SR _2b are the same, and the temperature is balanced, which shows that the current sharing effect of the magnetic integrated matrix transformer of the present invention is good.

Referring to Fig. 28, through the temperature rise experiment of the magnetic integrated matrix transformer of the present invention, and observing the temperature of the synchronous rectifier through the metal shell, it can be seen that after the prototype is fully loaded and baked for 5 minutes, the temperature of the synchronous rectifier SR _1a is 47.4°C, the temperature of the synchronous rectifier SR _1b is 47.3°C, the temperature of the synchronous rectifier SR _2a is 47.3°C, and the temperature of the synchronous rectifier SR _2b is 46.4°C, and the current sharing effect is good. At the same time, the highest temperature in the entire prototype is 57.6°C. It can be seen that the metal shell cladding structure has a good heat dissipation effect, which improves the heat dissipation performance of the device and the magnetic core.

Claims

A magnetic integrated matrix transformer, including a magnetic core, a primary winding, a secondary winding and a rectifier unit, is characterized in that:

The magnetic core is provided with a base, a central column and at least three side columns are formed on the base; at least one secondary winding is wound on the magnetic core, each secondary winding is wound on at least two adjacent side columns, each side column is wound by at least one secondary winding, the central column is used for winding the primary winding, the magnetic core and the secondary winding wound on the side columns form a transformer assembly; the magnetic integrated matrix transformer is composed of two transformer assemblies with the same structure, and the two transformer assemblies rotate 90° or 180° After the combination, the center columns of the two are aligned and connected, and the side columns are aligned and connected. At least one set of aligned side columns is simultaneously wound by two secondary side windings; the primary side winding is wound on the center column of one magnetic core, or is wound on the center columns of two magnetic cores at the same time.
The magnetically integrated matrix transformer according to claim 1, wherein each side column on the magnetic core is a cylinder or a polygonal column, and is located on a concentric circle centered on the center column or on a regular polygon centered on the center column.
The magnetically integrated matrix transformer according to claim 2, characterized in that: each secondary winding has the same number of side columns.
According to the magnetic integrated matrix transformer according to any one of claims 1-3, it is characterized in that: when the rectification unit is full-wave rectification, each or two secondary windings on the magnetic core form one output through the rectification unit; when the rectification unit is full-bridge rectification, each two secondary windings on the magnetic core form one output through the rectification unit.
According to the described magnetic integrated matrix transformer of claim 4, it is characterized in that: two sets of transformer components are covered with metal shells, and a heat-conducting insulating pad is provided between the metal shells and the transformer components, and the metal shell is connected to the output terminal of the output voltage V o equipotential in the transformer component or the rectifier unit to form a closed path for the secondary current.
According to claim 5, the magnetic integrated matrix transformer is characterized in that: in the magnetic core, the effective magnetic permeability area of the middle column is A e_c , the effective magnetic area of a single side column is A e_s , the primary and secondary side turns ratio of the magnetic integrated matrix transformer is N p /N s , the number of turns of the primary side winding around the center column is n pt , and the number of turns of a single secondary winding around m s side columns is n sq , then the primary and secondary side turns ratio satisfies the following relationship:
An isolated DC/DC converter, characterized in that: the isolated DC/DC converter is designed using the magnetic integrated matrix transformer of claim 1, by changing the number of secondary windings of the magnetic integrated matrix transformer, the number of side columns wound by the secondary windings, or changing the number of upper columns on the magnetic core to adjust the output gain of the isolated DC/DC converter, or to expand the switching frequency range, or to reduce the size of the magnetic core.
An isolated DC/DC converter, characterized in that: the isolated DC/DC converter is designed using the magnetic integrated matrix transformer of claim 5, by changing the number of secondary windings of the magnetic integrated matrix transformer, the number of winding side columns of the secondary winding, or changing the number of upper columns on the magnetic core to adjust the output gain of the isolated DC/DC converter, or to expand the switching frequency range, or to reduce the size of the magnetic core.