CN113077956B - High-power high-frequency five-phase magnetic integrated transformer - Google Patents

Abstract

The invention discloses a high-power high-frequency five-phase magnetic integrated transformer, and belongs to the technical field of high-frequency transformers. The transformer comprises five single-phase transformers, an upper magnetic cover, a lower magnetic cover and an insulation structure. The single-phase transformer comprises a magnetic core column, a primary coil and a secondary coil from inside to outside. Five single-phase transformers are arranged between the upper magnetic cover and the lower magnetic cover according to a regular pentagon staggered sequence, the input excitation phase difference of five primary coils is 72 degrees, the outgoing lines of the five primary coils are connected in a star shape, and the incoming lines of the five secondary coils are connected in a star shape. The insulation structure is arranged between the magnetic core column and the primary coil, between the primary coil and the secondary coil, between the five secondary coils and between the upper top cover and the lower top cover. The high-power high-frequency five-phase magnetic integrated transformer designed by the invention has the advantages of high power density, strong heat dissipation performance and high working stability, and has a large-range leakage inductance and excitation inductance adjusting interval.

Description

A high-power high-frequency five-phase magnetic integrated transformer

technical field

The invention relates to a high-power high-frequency five-phase magnetic integrated transformer, which belongs to the technical field of high-frequency transformers.

Background technique

The large-capacity new energy electric field is directly connected to the grid through the power frequency transformer, which occupies a large space and has a low power density. With the rapid development of power electronic technology, modular power electronic transformers have received more attention, which include two core components: high-power high-frequency transformers and power electronic converters.

For high-power high-frequency transformers, the increase in operating frequency can reduce the volume of high-power high-frequency transformers and improve power density. But at the same time, it will also lead to the increase of the core loss and winding loss of the high-power high-frequency transformer, and the miniaturization of the volume reduces the heat conduction area, which makes the heat dissipation of the high-power high-frequency transformer difficult. At the same time, with the increase of working voltage and power capacity, high-power high-frequency transformers have further increased insulation requirements. Therefore, high-power high-frequency transformers are usually wrapped with insulating materials, which leads to further decline in heat dissipation performance and affects the work of high-power high-frequency transformers. reliability.

Therefore, how to provide a high-power high-frequency transformer with good heat dissipation performance and operational reliability has become an urgent problem to be solved in the art.

In response to this problem, some scholars have proposed a high-power high-frequency multi-phase magnetic integrated transformer starting from the polyphase DC/DC converter. Polyphase DC/DC converters are more suitable for high-power applications due to their advantages of low current stress and low filter size requirements, but traditional polyphase DC/DC converters contain multiple high-power high-frequency single-phase transformers , occupies a large volume, and has a low power density, which is in urgent need of improvement. The high-power high-frequency multi-phase magnetic integrated transformer integrates multiple single-phase transformers in the multi-phase DC/DC converter topology into the same multi-column magnetic core, which can significantly increase the thermal conduction area without reducing the power density. , so as to improve the heat dissipation performance, and the simultaneous operation of multiple single-phase transformers can ensure that the high-power high-frequency multi-phase magnetic integrated transformer generates uniform heat, and local overheating will not occur. Therefore, high-power high-frequency polyphase magnetic integrated transformers have received more attention. However, the current research scope is mainly focused on low- and medium-power high-frequency three-phase magnetic integrated transformers. For example, in 2018, scholars from Kyushu University in Japan conducted research on the design and decoupling of low-power high-frequency three-phase magnetic integrated transformers. In 2020, British Columbia, Canada Scholars from Columbia University designed a high-frequency three-phase magnetic integrated transformer under medium power for the application of new energy vehicle charging piles. However, in the research of high frequency multiphase magnetic integrated transformer with more phases and higher power, there is no description or report on the technology similar to the present invention, and similar data at home and abroad have not been collected.

SUMMARY OF THE INVENTION

In view of the deficiencies of the prior art, in order to achieve better heat dissipation capability of high-power high-frequency transformers, the present invention further improves the working reliability of high-power high-frequency transformers and modular power electronic transformers. A high-power high-frequency five-phase magnetic integrated transformer is provided.

The purpose of the present invention is achieved in this way, the present invention provides a high-power high-frequency five-phase magnetic integrated transformer, including five identical single-phase transformers, an upper magnetic cover S, a lower magnetic cover X and an insulating structure; The insulating structure includes a primary insulating structure J1 and a secondary insulating structure J2, and the center positions of the upper magnetic cover S and the lower magnetic cover X are both provided with the same wire-passing hole K;

Denote any single-phase transformer among the five single-phase transformers as the i-phase transformer G _i , where _i represents the phase, i.e. i=A, B, C, D, E; The magnetic core column Z _i , a primary coil Y1 _i and a secondary coil Y2 _i are composed of the primary coil Y1 _i and the secondary coil Y2 _i in the same shape as the magnetic core column Z _i , and the three are kept concentric; The secondary insulating structure J2 is filled between Z _i and the primary coil Y1 _i , and the primary insulating structure J1 is filled between the primary coil Y1 _i and the secondary coil Y2 _i ;

Five single-phase transformers are arranged between the upper magnetic cover S and the lower magnetic cover X, and reserve a certain space with the upper magnetic cover S and the lower magnetic cover X; A regular pentagon is drawn with the passage holes K as the center, and five single-phase transformers are arranged in a wrong order at the five vertices of the regular pentagon. Specifically, from the A-phase transformer G _A Starting and rotating clockwise, they are: A-phase transformer G _A , C-phase transformer G _C , E-phase transformer G _E , B-phase transformer G _B and D-phase transformer _{G D} ; In the space opposite the magnetic cover S, a non-magnetic conductive material of the same thickness is laid, which forms an air gap layer Q; between the five secondary coils Y2 _i of the i-phase transformer G _i and the upper magnetic cover S, The space between it and the lower magnetic cover X is filled with a secondary insulating structure J2.

Preferably, the magnetic core column Z _i , the upper magnetic cover S and the lower magnetic cover X are all made of the same high magnetic permeability material, and the high magnetic permeability material is a material with an initial magnetic permeability greater than 2500, In the present invention, the operating frequency f of the high magnetic permeability material is greater than or equal to 20 kHz.

Preferably, the primary coil Y1 _i and the secondary coil Y2 _i are both wound by using stranded wires, wherein the wire diameter of a single turn of the wires in the stranded wires is smaller than the skin of the electromagnetic signal at the operating frequency depth.

Preferably, the input excitation phases of the primary coils Y1 _A , Y1 _B , Y1 _C , Y1 _D , and Y1 _E are sequentially different by 72°.

Preferably, the lead-in wires and lead-out wires of the five primary coils Y1 _i are wound with insulating tape, and then pass through the wire hole K of the upper magnetic cover, and the lead-out wires are star-connected; the five secondary The lead-in wire and lead-out wire of the coil Y2 _i are wrapped with insulating tape, and then pass through the wire hole K of the lower magnetic cover, and the lead-in wire is star-connected.

Preferably, the interiors of the primary insulating structure J1 and the secondary insulating structure J2 are filled with insulating materials, and the withstand temperatures of the primary insulating structure J1 and the secondary insulating structure J2 are both greater than the maximum operating temperature of the transformer.

Preferably, the thickness of the primary insulating structure J1 is 15mm-20mm, and the thickness of the secondary insulating structure J2 is 5mm-15mm.

Compared with the prior art, the beneficial effects of the present invention are:

1. The high-power high-frequency five-phase magnetic integrated transformer provided by the present invention is a high-power high-frequency transformer with good heat dissipation performance, high working reliability and high power density.

2. The high-power high-frequency five-phase magnetic integrated transformer provided by the present invention passes through the lead wires and lead-in wires of the five primary coils Y1 _i and the lead wires and lead-in wires of the five secondary coils Y2 _i from the upper magnetic cover respectively. The wire hole K and the wire hole K of the lower magnetic cover lead out, which can achieve high insulation strength.

3. The high-power high-frequency five-phase magnetic integrated transformer provided by the present invention, through the out-of-order arrangement of five single-phase transformers G _i , makes the magnetic flux in the upper magnetic cover S and the lower magnetic cover X mainly concentrate on the edge part, ensuring that Therefore, the magnetic flux will not accumulate near the wire hole K and become supersaturated.

4. The high-power high-frequency five-phase magnetic integrated transformer provided by the present invention is connected through the star connection of the lead wires of the five primary coils Y1 _i , the star connection of the lead wires of the five secondary coils Y2 _i , and the upper magnetic cover S. The non-magnetic conductive material sheet of the same thickness is laid in the space opposite to the five magnetic core pillars Z _i to ensure that the five single-phase transformers G _i can work independently and normally, and there will be no large phase-to-phase influence.

5. The high-power high-frequency five-phase magnetic integrated transformer provided by the present invention has a wide range of leakage inductance, excitation In the inductance adjustment range, an external inductance is not required for the applied five-phase DC/DC converter, and the zero-voltage soft-switching can be guaranteed to be turned on to improve efficiency.

Description of drawings

Fig. 1 is a three-dimensional schematic diagram of a high-power high-frequency five-phase magnetic integrated transformer according to an embodiment of the present invention;

Fig. 2 is a schematic diagram of five single-phase transformers arranged out of sequence in an embodiment of the present invention;

3 is a front view of a high-power high-frequency five-phase magnetic integrated transformer in an embodiment of the present invention;

4 is a schematic cross-sectional view of the stranded wire used by five primary coils and five secondary coils in an embodiment of the present invention;

5 is a schematic diagram of input excitation of five primary coils in an embodiment of the present invention;

6 is a simulation waveform of five primary winding currents in a high-power high-frequency five-phase magnetic integrated transformer obtained by magneto-electric co-simulation in the embodiment of the present invention;

7 is a simulation diagram of the top cover magnetic flux distribution at the moment when the excitation current in the A-phase primary coil of the high-power high-frequency five-phase magnetic integrated transformer reaches the maximum time obtained by the magneto-electric co-simulation in the embodiment of the present invention.

Detailed ways

The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings.

Fig. 1 is a schematic diagram of the three-dimensional structure of a high-power high-frequency five-phase magnetic integrated transformer in this embodiment, Fig. 2 is a schematic diagram of the arrangement of five single-phase transformers in this embodiment out of sequence, and Fig. 3 is a high-power high-frequency five-phase transformer in this embodiment. Front view of the magnetic integrated transformer. It can be seen from FIGS. 1-3 that the high-power high-frequency five-phase magnetic integrated transformer in this embodiment includes five identical single-phase transformers, an upper magnetic cover S, a lower magnetic cover X and an insulating structure; the insulating structure It includes a primary insulating structure J1 and a secondary insulating structure J2. The upper magnetic cover S and the lower magnetic cover X are both provided with the same wire-passing hole K at the center position.

Denote any single-phase transformer among the five single-phase transformers as the i-phase transformer G _i , where _i represents the phase, i.e. i=A, B, C, D, E; The magnetic core column Z _i , a primary coil Y1 _i and a secondary coil Y2 _i are composed of the primary coil Y1 _i and the secondary coil Y2 _i in the same shape as the magnetic core column Z _i , and the three are kept concentric; A secondary insulating structure J2 is filled between Z _i and the primary coil Y1 _i , and a primary insulating structure J1 is filled between the primary coil Y1 _i and the secondary coil Y2 _i .

The five single-phase transformers are arranged between the upper magnetic cover S and the lower magnetic cover X, and reserve a certain space with the upper magnetic cover S and the lower magnetic cover X. The two wire holes K on the upper magnetic cover S and the lower magnetic cover X are arranged concentrically, draw a regular pentagon with the wire hole K as the center, and arrange the five single-phase transformers in a regular pentagon in a wrong order. Specifically, starting from the A-phase transformer G _A and rotating clockwise, they are: A-phase transformer G _A , C-phase transformer G _C , E-phase transformer G _E , B-phase transformer G _B and D-phase Transformer G _D . In the space where the five magnetic core columns Z _i are opposite to the upper magnetic cover S, a non-magnetic conductive material of the same thickness is laid, and the non-magnetic conductive material forms an air gap layer Q; the five secondary coils of the i-phase transformer G _i The spaces between Y2 _i and the upper magnetic cover S and between the lower magnetic cover X are filled with secondary insulating structures J2.

As can be seen from FIG. 2 , in this embodiment, the cross-sections of the upper magnetic cover S and the lower magnetic cover X are both rounded regular pentagons, and there are wire-passing holes K of the same shape and size at the same position. Due to the flexible arrangement of the five magnetic core columns Z _i , the magnetic flux is mainly concentrated on the edge parts of the upper top cover S and the lower top cover X, that is, the magnetic flux around the two wire-passing holes K is very small and will not cause the upper cover S and the lower cover X. The magnetic flux of the magnetic cover S and the lower magnetic cover X is concentrated and then supersaturated. The upper magnetic cover S and the lower magnetic cover X are respectively above and below the five magnetic core columns Z _i , and the same thickness of non-magnetic conductive material is filled at the junction of the upper magnetic cover S and the five magnetic core columns Z _i to form The air gap layer Q is used to adjust the excitation inductance. The temperature tolerance of the non-magnetic material must be greater than the maximum working temperature of the transformer, and it is not easy to deform. Specific non-magnetic conductive materials can be epoxy resin sheets, acrylic sheets, and the like. During the specific production, the non-magnetic conductive material is glued on the top of the five magnetic core columns with AB, and fixed from above the upper magnetic cover S and below the lower magnetic cover X using a clamp.

In this embodiment, the magnetic core column Z _i , the upper magnetic cover S and the lower magnetic cover X are all made of the same magnetic permeability material, and the operating frequency f of the magnetic permeability material is greater than or equal to 20 kHz. Specifically, the five magnetic core legs Z _i , the upper magnetic cover S and the lower magnetic cover X are made of a ferrite material with an initial permeability greater than 2500, and the working frequency of the ferrite material is greater than 20 kHz.

In this embodiment, the primary coil Y1 _i and the secondary coil Y2 _i are both wound by using a multi-stranded wire, wherein the wire diameter of a single turn of the wire in the multi-stranded wire is smaller than the electromagnetic signal at the operating frequency skin depth. Figure 4 shows the state of the cut plane of the stranded wire. During specific production, according to the working frequency, the wire diameter of the single-turn wire is selected as 0.15mm, and the number of single-turn wires in the stranded wire is flexibly selected according to the current density of 4A/mm ² -6A/mm ² .

In this embodiment, the input excitation phases of the primary coils Y1 _A , Y1 _B , Y1 _C , Y1 _D , and Y1 _E differ by 72° in sequence. The specific state can be seen in Figure 5.

In this embodiment, the lead-in wires and lead-out wires of the five primary coils Y1 _i are wound with insulating tape, and then pass through the wire hole K of the upper magnetic cover, and the lead-out wires are star-connected. The lead-in wires and lead-out wires of the five secondary coils _Y2i are wound with insulating tape, and then pass through the wire-passing hole K of the lower magnetic cover, and the lead-in wires are connected in a star shape.

In the implementation of the present invention, the interiors of the primary insulating structure J1 and the secondary insulating structure J2 are filled with insulating materials, and the withstand temperatures of the primary insulating structure J1 and the secondary insulating structure J2 are both greater than the maximum working temperature of the transformer. The thickness of the primary insulating structure J1 is 15mm-20mm, and the thickness of the secondary insulating structure J2 is 5mm-15mm.

Specifically, the materials of the primary insulating structure J1 and the secondary insulating structure J2 are epoxy resin, electrical ceramics, phenolic resin, and the like. The main insulating structure J1 is used to withstand the high isolation voltage between the five primary coils Y1 _i and the five secondary coils Y2 _i , and its thickness is set to 15mm-20mm, in order to achieve a high isolation voltage of more than 10kV in combination with insulating materials. The secondary insulating structure J2 mainly bears the isolation voltage between the five magnetic core columns Z _i , the upper magnetic cover S, the lower magnetic cover X and the five primary coils Y1 _i and the five secondary coils Y2 _i , so its thickness is set 5mm-15mm. In addition, since the leakage magnetic flux mainly flows through the main insulating structure J1, the transformer proposed in the present invention can not only adjust the leakage inductance by using the magnetic core and coil parameters, but also adjust the inductance by using the size of the main insulating structure J1. , which effectively increases the adjustment range of the inductance.

The specific insulation structure and the size of the air gap Q are adjusted according to the insulation requirements, the best matching of leakage inductance and excitation inductance, so as to ensure that the applied five-phase LLC resonant converter no longer needs an external inductance, and can realize the five-phase type LLC resonant converter. The zero-voltage soft-switching of the switching devices in the LLC resonant converter is turned on.

In order to verify the technical effect of the present invention, the magnetoelectric co-simulation of the present invention is carried out to verify the validity of the transformer. The simulation results are shown in FIG. 6 and FIG. 7 .

6 is a simulation waveform of currents of five primary windings in a high-power high-frequency five-phase magnetic integrated transformer obtained by magneto-electric co-simulation in an embodiment of the present invention. As shown in Figure 6, the magnitudes of the currents flowing through the five primary coils Y1 _i are basically the same, and the phases are stable, indicating that the transformers work normally, and the five integrated single-phase transformers G _i can work independently and will not affect each other.

FIG. 7 is a simulation diagram of the magnetic flux distribution of the upper cover S at the moment when the excitation current in the primary coil of the A phase in the high-power high-frequency five-phase magnetic integrated transformer reaches the maximum time obtained by the magneto-electric co-simulation in this embodiment. As shown in FIG. 7 , the magnetic flux is mainly concentrated on the edge portion of the top cover S, and the magnetic flux near the wire hole K of the top cover is extremely small, and no magnetic flux saturation is formed.

The invention is applied to the five-phase LLC resonant converter, and can solve the problems of high insulation grade, high power density, high heat conduction area and high working reliability of traditional high-power high-frequency transformers. Through the optimal matching of the leakage inductance and excitation inductance according to the height of the air gap and the size of the insulation structure, the five-phase LLC resonant converter does not need an external inductance and can maintain the full-load soft-switching characteristics. The traditional DC/DC converter with grade power capacity has the advantages of small current stress and small filter size, which further ensures the high heat dissipation capacity and working reliability of the high-power high-frequency five-phase magnetic integrated transformer.

Claims (5)

1. a high-power high-frequency five-phase magnetic integrated transformer is characterized in that, comprising five identical single-phase transformers, an upper magnetic cover S, a lower magnetic cover X and an insulating structure; the insulating structure comprises a main insulating structure J1 and the secondary insulating structure J2, the center positions of the upper magnetic cover S and the lower magnetic cover X are both provided with the same wire-passing hole K; Denote any single-phase transformer among the five single-phase transformers as the i-phase transformer G _i , i represents the phase, i.e. i=A, B, C, D, E; the i-phase transformer G _i is changed from inside to outside by one The magnetic core column Z _i , a primary coil Y1 _i and a secondary coil Y2 _i are composed of the primary coil Y1 _i and the secondary coil Y2 _i in the same shape as the magnetic core column Z _i , and the three are kept concentric; The secondary insulating structure J2 is filled between Z _i and the primary coil Y1 _i , and the primary insulating structure J1 is filled between the primary coil Y1 _i and the secondary coil Y2 _i ; Five single-phase transformers are arranged between the upper magnetic cover S and the lower magnetic cover X, and reserve a certain space with the upper magnetic cover S and the lower magnetic cover X; A regular pentagon is drawn with the passage holes K as the center, and five single-phase transformers are arranged in a wrong order at the five vertices of the regular pentagon. Specifically, from the A-phase transformer G _A Starting and rotating clockwise, they are: A-phase transformer G _A , C-phase transformer G _C , E-phase transformer G _E , B-phase transformer G _B and D-phase transformer _{G D} ; In the space opposite the magnetic cover S, a non-magnetic conductive material of the same thickness is laid, which forms an air gap layer Q; between the five secondary coils Y2 _i of the i-phase transformer G _i and the upper magnetic cover S, The space between it and the lower magnetic cover X is filled with a secondary insulating structure J2; The input excitation phases of the primary coils Y1 _A , Y1 _B , Y1 _C , Y1 _D , and Y1 _E differ by 72° in sequence; The lead-in and lead-out wires of the five primary coils _Y1i are wound with insulating tape, and then pass through the wire hole K of the upper magnetic cover, and the lead-out wires are star-connected; the five secondary coils _Y2i The lead-in and lead-out wires are wrapped with insulating tape, and then pass through the wire hole K of the lower magnetic cover, and the lead-in wires are star-connected. 2. The high-power high-frequency five-phase magnetic integrated transformer according to claim 1, wherein the magnetic core column Z _i , the upper magnetic cover S and the lower magnetic cover X are all made of the same high permeability material Thus, the high magnetic permeability material is a material with an initial magnetic permeability greater than 2500, and the operating frequency f of the high magnetic permeability material is greater than or equal to 20 kHz. 3. The high-power high-frequency five-phase magnetic integrated transformer according to claim 1, wherein the primary coil Y1 _i and the secondary coil Y2 _i are both wound by using a multi-strand stranded wire, wherein the multi-strand The wire diameter of a single turn of wire in a stranded wire is less than the skin depth of the electromagnetic signal at the operating frequency. 4. The high-power high-frequency five-phase magnetic integrated transformer according to claim 1, wherein the main insulating structure J1 and the secondary insulating structure J2 are filled with insulating materials, and the main insulating structure J1 and the secondary insulating structure J2 are filled with insulating materials. The withstand temperature is greater than the maximum operating temperature of the transformer. 5 . The high-power high-frequency five-phase magnetic integrated transformer according to claim 1 , wherein the thickness of the main insulating structure J1 is 15mm-20mm, and the thickness of the secondary insulating structure J2 is 5mm-15mm. 6 .

Images