A coupling transformer and PFC circuit

Abstract

This utility model discloses a coupling transformer and a PFC circuit. The transformer comprises a magnetic core, windings, and a bottom component. The magnetic core is mounted on the bottom component and includes a central post, side posts, and a yoke. The windings are wound on the central post, and air ducts are formed between the windings and the side posts on both sides, allowing airflow to pass through both sides of the coupling transformer. This technical solution significantly enhances the penetration of cooling airflow and the heat dissipation capacity of the magnetic core and windings (improving heat dissipation effect) without adding extra structure or volume, based on the formed air ducts. This avoids the temperature rise and heat dissipation difficulties caused by the coupling transformer's proximity to the PFC inductor heat source in interleaved parallel PFC circuits, thereby reducing the overall temperature rise of the transformer.

Description

Technical Field

[0001] This utility model relates to the field of transformer technology, and in particular to a coupling transformer and a PFC circuit. Background Technology

[0002] With the development of new energy sources, charging equipment, and high-power-density power electronic systems, power factor correction (PFC) circuits are widely used to improve power quality and system efficiency. In high-power power electronic devices, interleaved parallel technology is typically used to improve current handling capacity and reduce current ripple. This technology effectively achieves higher power capacity output through multi-channel parallel operation, while avoiding the current unevenness problem caused by direct parallel connection of switching devices.

[0003] In PFC circuits, interleaved parallel structures can significantly increase the frequency and reduce the amplitude of input current ripple, thereby optimizing filter design and reducing switching losses. However, when two independent inductors are used as each PFC channel, the difficulty in achieving perfect consistency in device parameters can easily lead to current unevenness in the parallel paths. To address this issue, the industry commonly employs a coupled transformer structure, using magnetic coupling to achieve current balancing between different channels and improve system stability.

[0004] However, in practical applications, coupling transformers are among the magnetic components with significant heat loss, and they are often arranged side-by-side with PFC inductors, forming localized heat source concentration areas that easily lead to poor heat dissipation. Excessive local temperature rise will affect system reliability and lifespan. Current heat dissipation improvement solutions for magnetic components mainly focus on adding holes to the magnetic core to enhance heat dissipation. However, in interleaved parallel PFC circuits, the coupling transformer and PFC inductor are too close together, resulting in severe thermal interference. Simply modifying the magnetic core or adjusting its position cannot fundamentally solve the heat dissipation bottleneck problem. Utility Model Content

[0005] The main objective of this invention is to provide a coupling transformer and a PFC circuit to at least solve the technical problem of poor heat dissipation of coupling transformers in related technologies.

[0006] To achieve the above objectives, this utility model provides the following technical solution:

[0007] A first aspect of this utility model is to provide a coupling transformer, the coupling transformer comprising a magnetic core, windings and a bottom component;

[0008] The magnetic core is disposed on the bottom component and includes a central column, side columns located on both sides of the central column, and a magnetic yoke. The magnetic yoke is used to connect the central column and the side columns.

[0009] The winding is wound on the central column;

[0010] The winding and the side posts on both sides form a through-flow air duct, which is used to allow airflow to pass through both sides of the coupling transformer.

[0011] A second aspect of this utility model also provides a PFC circuit, including a circuit board body, a PFC inductor, and a coupling transformer as described in the first aspect, wherein the PFC inductor and the coupling transformer are disposed on the circuit board body.

[0012] This utility model discloses a coupling transformer and PFC circuit. By setting a central column and two side columns in the magnetic core structure, and using windings wound on the central column, a through-flow air channel is reserved between the windings and the side columns, allowing airflow to pass through both sides of the coupling transformer. This technical solution significantly enhances the penetration of cooling airflow and the heat dissipation capacity of the magnetic core and windings (improving heat dissipation effect) without increasing additional structure or volume. It avoids the temperature rise and heat dissipation difficulties caused by the coupling transformer's proximity to the PFC inductor heat source in interleaved parallel PFC circuits, thereby reducing the overall temperature rise of the transformer. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of the present invention or related technologies, the drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 A three-dimensional schematic diagram of the coupling transformer provided in the embodiments of this application;

[0015] Figure 2 This is a schematic diagram of the magnetic core structure in an embodiment of this application;

[0016] Figure 3 A front view of the coupling transformer provided in an embodiment of this application;

[0017] Figure 4 A top view of the coupling transformer provided in an embodiment of this application;

[0018] Figure 5 A side view of the coupling transformer provided in an embodiment of this application.

[0019] Reference numerals: 1. Coupling transformer; 10. Magnetic core; 20. Bottom component; 30. Winding; 101. Middle column; 102. Side column; 103. Magnetic yoke; 104. Air duct; 201. Pin terminal; 301. First winding portion; 302. Second winding portion; 303. Detailed Implementation

[0020] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0021] It should be noted that related terms such as "first" and "second" can be used to describe various components, but these terms do not limit the component. These terms are only used to distinguish one component from another. For example, without departing from the scope of this utility model, the first component can be referred to as the second component, and the second component can similarly be referred to as the first component. The term "and / or" refers to any one or more combinations of related and descriptive terms.

[0022] Please refer to them in order. Figures 1 to 5 This application provides a coupling transformer 1 to improve the heat dissipation performance of magnetic components under high power density conditions. It is especially suitable for the situation in parallel PFC circuits where the coupling transformer is adjacent to the heat source of the PFC inductor, resulting in high temperature rise and difficult heat dissipation.

[0023] The coupling transformer 1 includes a magnetic core 10, a winding 30, and a bottom component 20. The components are described below:

[0024] The magnetic core 10 is fixedly mounted on the bottom component 20 to support and accommodate the winding 30 and provide a magnetic flux channel. Generally, the magnetic core 10 has a typical EE structure (EE-type magnetic core), including a central post 101, two side posts 102 located on either side of the central post, and a yoke 103 connecting the central post 101 and the side posts 102. The central post 101 carries the winding 30, while the yoke 103 forms a complete magnetic circuit.

[0025] The winding 30 is uniformly wound on the outer circumferential surface of the central column 101, with a consistent spacing between adjacent turns. The gap between turns helps to enhance the heat dissipation efficiency of the winding body, while increasing the heat dissipation area of ​​the central column and improving the thermal distribution of the magnetic core.

[0026] In this design, a through-flow air duct 104 is formed between the winding 30 and the side posts 102 on both sides, allowing airflow to pass through both sides of the coupling transformer 1. That is, a predetermined distance is reserved between the two end faces of the winding 30 and the corresponding side posts 102, forming an air channel extending along the front-to-back direction of the device. Thus, the air duct 104 can guide the cooling airflow in a preset direction (e.g., under forced air cooling conditions). Figure 1 middle (Used to indicate the flow direction from front to back) passing through, significantly reducing the local temperature rise of the magnetic core and windings, and improving the thermal balance of the device.

[0027] As can be seen, the coupling transformer in this embodiment of the application sets a central column and two side columns in the magnetic core structure, and uses windings to wind on the central column, so that a through air channel is reserved between the windings and the side columns. Finally, the airflow passes through both sides of the coupling transformer through the air channel, thereby significantly enhancing the penetration of cooling airflow and the heat dissipation capacity of the magnetic core and windings (improving the heat dissipation effect) without adding extra structure and volume. This avoids the phenomenon of temperature rise and heat dissipation difficulty caused by the coupling transformer being adjacent to the heat source of the PFC inductor in the interleaved parallel PFC circuit, thereby reducing the overall temperature rise of the transformer.

[0028] It should be noted that the formation of air duct 104 includes at least the following two scenarios:

[0029] In one scenario, the air duct 104 is directly formed by the gap between the two ends of the winding 30 wound on the central column 101 and the side columns 102 on both sides of the central column 101.

[0030] In another scenario, the air duct 104 is formed by the overall width of the winding 30 being smaller than the spacing between the side columns 102 on both sides of the central column 101, meaning that symmetrically distributed air duct space is reserved during the structural design phase.

[0031] In both of the above methods, the air duct 104 can be understood as a hollow area. When this hollow area is combined with external heat dissipation components (fans, etc.), it will naturally form an airflow channel (i.e., air duct). Since the air duct 104 runs through the front and back directions of the coupling transformer 1, the airflow can enter from one side, pass through the gaps on both sides of the winding, and then exit from the other side, thereby achieving forced air cooling and improving the overall heat dissipation performance of the transformer.

[0032] In an optional embodiment of this application, the air duct 104 is divided into two independently distributed parts, namely the first air duct and the second air duct.

[0033] Specifically, the first air duct is formed by the gap between one end of the winding 30 and the side post 102 located on one side of that end. One end of the winding 30 and the side post 102 are located on the same side of the coupling transformer 1. For example, when observing... Figure 2 In the structure shown, the first air duct is located on the left side of the coupling transformer 1. The second air duct is formed by the gap between the other end of the winding 30 and another side post 102 located on one side of that end, with the other end of the winding 30 and the side post 102 located on the other side of the coupling transformer 1. For example, in... Figure 3 In the structure shown, the second air duct is located to the right of the coupling transformer 1.

[0034] With the symmetrical distributed air duct structure of this embodiment, that is, the first air duct and the second air duct are both connected in the front and rear directions of the coupling transformer 1, it can be ensured that the airflow entering from the front direction can pass through the two air ducts respectively, thereby increasing the heat dissipation contact area between the transformer winding and the magnetic core, achieving efficient forced cooling, and significantly reducing the temperature rise of the magnetic core.

[0035] In an optional embodiment of this application, the width of the air duct 104, i.e. the gap between the winding 30 and the two side posts 102, is set to 2mm to 4mm in the length direction of the bottom member 20.

[0036] Specifically, the duct width of 2mm to 4mm is a result of a comprehensive balance of factors such as heat dissipation performance, electrical and structural limitations, process feasibility, and cost-effectiveness. In the case of forced air cooling, this width can effectively guide airflow through both sides of the coupling transformer 1, significantly improving the heat dissipation capacity of the magnetic core 10 and winding 30.

[0037] Among these factors, a duct width of 3mm achieves the best overall effect. Firstly, from a heat dissipation perspective, when using forced air cooling, a 3mm duct width is sufficient to ensure that airflow can effectively penetrate the internal structure of the coupling transformer 1, improving the heat exchange efficiency of the magnetic core 10 and winding 30. Secondly, in terms of structural design, this gap size can adequately accommodate tolerance accumulation during assembly, preventing the winding 30 from encroaching on the duct space or physically interfering with the side post 102 due to thermal expansion and contraction during manufacturing or operation, ensuring mechanical stability and insulation safety. Furthermore, a 3mm gap facilitates efficient winding by automated winding equipment and also simplifies manual operation and quality inspection, making it a technologically feasible size choice in industrial manufacturing. By controlling the duct width to a minimum while meeting thermal performance and assembly requirements, the overall volume of the coupling transformer can be reduced, thereby increasing the module's power density and saving production costs. Therefore, the 3mm duct width not only reflects an optimized balance between heat dissipation efficiency and economy but also aligns with the compact trend of high-power-density power electronic equipment.

[0038] It should also be understood that the width of the air duct in the embodiments of this application is not limited to a specific value. It can be appropriately adjusted according to the specific application scenario, heat dissipation requirements and actual conditions such as structural space, so as to achieve the best balance between structural compactness and cost control while ensuring heat exchange efficiency.

[0039] In an optional embodiment of this application, the winding 30 can be a flat copper wire, that is, the radial cross-section is non-circular and generally elliptical.

[0040] Specifically, the flat copper wire is wound in multiple turns uniformly on the central post 101 of the magnetic core 10, with a consistent coil spacing between adjacent turns. This embodiment utilizes flat copper wire, which has a larger contact area compared to traditional round wire, thus improving heat dissipation efficiency. Simultaneously, by maintaining a consistent turn spacing during winding, heat accumulation caused by localized stacking is avoided, further enhancing the overall heat dissipation uniformity of the winding. Furthermore, the consistent turn spacing also facilitates uniform heat conduction.

[0041] In an optional embodiment of this application, the bottom component 20 is provided with a first positioning hole (not shown) and a second positioning hole (not shown).

[0042] Specifically, the first positioning hole is used to guide one end of the winding 30 to be led out from the top of the magnetic core column 101, bend perpendicular to one side column 102 and insert into the bottom component to achieve a vertical insertion structure and ensure that the lead wire does not block the air passage 104 formed between the side column and the winding; the second positioning hole is used to guide the other end of the winding 30 to be led out from the bottom of the core column 101, bend along the direction of the other side column 102 and insert into the bottom component.

[0043] This embodiment, through the pre-set wire path and positioning hole structure, not only ensures neat wire routing and avoids obstructing the ventilation effect of the air duct, but also improves the operability and safety of the winding connection, further enhancing the reliability and insulation performance of the transformer assembly structure.

[0044] In an optional embodiment of this application, the winding 30 includes three sequentially connected parts: a first winding part 301, a second winding part 302, and a third winding part 303.

[0045] The first winding portion 301 is the main winding structure, which is wound on the central column 101 of the magnetic core 10 to form the induction turns of the coupling transformer 1; the second winding portion 302 is led out from one end of the central column 101 and is perpendicular to the adjacent side column 102; the third winding portion 303 is inserted perpendicularly into the positioning hole of the bottom component 20 and serves as the external pin terminal 201 to realize electrical connection or lead out.

[0046] Furthermore, in order not to obstruct the air duct 104, the third winding portion 303 is positioned on the left and right sides or outside the boundary range of the air duct in the height direction of the bottom component 20, thereby ensuring that the airflow can smoothly pass through the gap between the winding 30 and the side post 102 from the front and rear directions, without affecting the ventilation efficiency of the air duct and ensuring the overall heat exchange performance.

[0047] In addition, the third winding section 303 is covered with high-temperature insulating tape 304 to enhance the heat resistance and safety of the transformer's internal insulation structure, prevent the winding ends from contacting the magnetic core or other metal parts and causing a breakdown risk, and improve the overall insulation stability of the device.

[0048] In an optional embodiment of this application, the coupling transformer 1 is installed and positioned using a customized bottom component 20. The thickness of this bottom component is set to 1 mm, which is an optimized choice derived after comprehensively balancing various technical requirements such as mechanical strength, insulation performance, and assembly tolerances.

[0049] Specifically, the 1mm thick bottom component has sufficient structural rigidity to provide stable support during use and installation, preventing transformer structure instability caused by deformation of the bottom component; on the other hand, this thickness helps to reduce the overall weight of the module, meeting the lightweight requirements of high power density equipment.

[0050] Furthermore, the 1mm thickness ensures the necessary insulation distance between the magnetic core 10 and the electrode pins under space-constrained conditions, effectively preventing insulation failure. Simultaneously, this thickness accommodates potential unevenness on the ferrite core's mating surface, providing a degree of elastic absorption, reducing the risk of localized stress concentration, extending core life, and improving assembly consistency.

[0051] It should also be understood that the thickness of the bottom component in the embodiments of this application is not limited to a specific value. It can be appropriately adjusted according to the specific application scenario, heat dissipation requirements and actual conditions such as structural space, so as to achieve the best balance between structural compactness and cost control while ensuring heat exchange efficiency.

[0052] This application also provides a PFC circuit, including a circuit board body, a PFC inductor, and a coupling transformer as described in the above embodiments, wherein the PFC inductor and the coupling transformer are disposed on the circuit board body.

[0053] Specifically, the main board of the PFC circuit serves as a structural platform that carries and connects various power electronic components. The PFC inductor and coupling transformer are arranged side by side on the main board, forming the key magnetic component unit in the PFC boost converter topology. By arranging the coupling transformer with the aforementioned symmetrical airflow design within the forced air cooling duct reserved on the board, the overall heat dissipation efficiency and thermal stability of the module can be significantly improved.

[0054] The coupling transformer and PFC circuit of this invention also have the following beneficial effects:

[0055] 1) By leaving certain air ducts on both sides of the PFC coupling transformer and placing it in a reasonable and unobstructed air duct, the structure is simple and ensures that the magnetic core, coil and air have a large area of ​​contact. The front and rear air ducts can ensure that high-speed cold air can completely penetrate through both sides of the coupling transformer, enhancing the heat dissipation of the magnetic core and coil.

[0056] 2) Flat copper wire coils are used for winding on the central column, ensuring a uniform distribution of gaps between coil turns. This helps with heat dissipation of the coil itself and increases the heat dissipation area on the surface of the central column, resulting in more uniform heat dissipation.

[0057] 3) A customized bottom component is used to position the coil leads, ensuring that the leads are bent 90° toward the side post and perpendicular to the bottom component section, so as not to block the air duct. The size of the opening on the bottom component is determined according to the cross-sectional area of ​​the coil.

[0058] In summary, the embodiments of this application reduce the temperature rise of the PFC coupling transformer, avoid the phenomenon that the heat source is relatively concentrated and difficult to dissipate due to the coupling transformer being close to the PFC inductor in the interleaved parallel PFC circuit, thereby further improving the power density; in addition, the structure is simple, which simplifies the processing technology and saves manufacturing costs; and ensures the reliability of the product.

[0059] The specific embodiments of the utility model have been described in detail above, but they are only examples, and the utility model is not limited to the specific embodiments described above. For those skilled in the art, any equivalent modifications or substitutions to the utility model are also within the scope of the utility model. Therefore, all equivalent transformations, modifications, and improvements made without departing from the spirit and principles of the utility model should be covered within the scope of the utility model.

Claims

1. A coupled transformer, characterized by, The coupling transformer includes a magnetic core, windings, and a bottom component; The magnetic core is disposed on the bottom component and includes a central column, side columns located on both sides of the central column, and a magnetic yoke. The magnetic yoke is used to connect the central column and the side columns. The winding is wound on the central column; The winding and the side posts on both sides form a through-flow air duct, which is used to allow airflow to pass through both sides of the coupling transformer.

2. The coupled transformer of claim 1, wherein, The air duct is formed by the gap between the two ends of the winding wound on the central column and the side columns on both sides of the central column; or, The air duct is formed by the width of the winding being smaller than the spacing between the side columns on both sides of the central column.

3. The coupling transformer as described in claim 2, characterized in that, The air duct includes a first air duct and a second air duct; The first air duct is formed by the gap between one end of the winding and a side post; wherein one end of the winding and a side post are located on one side of the coupling transformer; The second air duct is formed by the gap between the other end of the winding and the other side post; wherein the other end of the winding and the other side post are on the other side of the coupling transformer.

4. The coupled transformer of claim 2, wherein, The gap is 2 mm to 4 mm along the length of the bottom member.

5. The coupled transformer of claim 2, wherein, The winding comprises flat copper wire; The flat copper wire is wound on the central column, and the flat copper wire forms a multi-turn coil with the same spacing between adjacent turns.

6. The coupled transformer of claim 5, wherein, The bottom component is provided with a first positioning hole and a second positioning hole; The first positioning hole is used to guide one end of the winding to bend vertically from the top of the central column and into the side column, and the second positioning hole is used to guide the other end of the winding to bend vertically from the bottom of the central column and into the side column.

7. The coupled transformer of claim 5, wherein, The winding includes a first winding portion, a second winding portion, and a third winding portion connected in sequence; The first winding portion is wound on the central column, the second winding portion is perpendicular to the side column, and the third winding portion is perpendicular to the bottom component.

8. The coupled transformer of claim 7, wherein, The third winding portion does not obstruct the air duct in the height direction of the bottom component.

9. The coupled transformer of claim 7, wherein, The third winding is wrapped with high-temperature insulating tape.

10. A PFC circuit, characterized by, The circuit includes a circuit board body, a PFC inductor, and a coupling transformer as described in any one of claims 1 to 9, wherein the PFC inductor and the coupling transformer are disposed on the circuit board body.

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