CLLC resonant transformer based on magnetic integration and reinforced heat dissipation

Abstract

The application discloses a CLLC resonant transformer based on magnetic integration and reinforced heat dissipation. The transformer comprises a magnetic core assembly, a framework, a winding and a pouring sealant, the magnetic core assembly is provided with a main air gap, a plurality of groups of first through holes are arranged on the framework, and at least one group of the first through holes is located at a position opposite to the main air gap, a winding path of the winding avoids the first through hole opposite to the main air gap and covers the remaining first through holes; the magnetic core assembly comprises a magnetic core middle column and a magnetic core side column, and the magnetic core side column is provided with a second through hole. The first through hole and the second through hole are opened, so that the pouring sealant can flow into the transformer and fully infiltrate the connection between the winding and the framework and the gap between the outermost winding and the side column. The structure constructs a continuous and efficient heat dissipation path from the inside to the outside, significantly reduces the temperature rise of the transformer, thereby allowing the copper wire consumption to be reduced to reduce the cost, and the integrity and reliability of the pouring are improved.

Description

Technical Field

[0001] This invention relates to the field of high-frequency switching power supply technology, specifically to a CLLC resonant transformer based on magnetic integration and enhanced heat dissipation. Background Technology

[0002] CLLC resonant transformers typically integrate the resonant inductor with the transformer magnetically. This resonant inductor is implemented in the transformer as a leakage inductance, which can reduce the number of components and increase power density.

[0003] However, existing magnetically integrated CLLC transformers suffer from poor heat dissipation and high copper losses. The main hotspot areas are near the core air gap, at the connection between the winding and the bobbin, and between the outermost winding (tightly wrapped by the core) and the side posts. In traditional potting processes, the potting compound cannot fully penetrate the transformer interior, leaving air gaps, especially in the aforementioned hotspot areas. Heat cannot be effectively dissipated, leading to localized temperature rises. To ensure the temperature rise remains within acceptable limits, designs often require the use of more Litz wire strands to reduce current density, increasing copper usage and cost.

[0004] Therefore, there is an urgent need for a magnetically integrated CLLC transformer structure that can effectively improve internal heat dissipation, reduce temperature rise, and save material costs. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a CLLC resonant transformer based on magnetic integration and enhanced heat dissipation, which features optimized heat dissipation path, good potting effect, and effective reduction of temperature rise and cost.

[0006] To achieve the above objectives, the technical solution provided by the present invention is as follows: A CLLC resonant transformer based on magnetic integration and enhanced heat dissipation includes a core assembly, a frame, windings wound on the frame, and potting compound filling the transformer interior. The core assembly has a main air gap and includes a yoke, a core center post, and core side posts. The frame has multiple sets of first through holes, at least one set of which is located directly opposite the main air gap. The winding path of the windings avoids the first through holes directly opposite the main air gap and covers the remaining first through holes. The frame is fitted around the core center post and inside the core side posts. The core side posts have at least one second through hole. Both the first and second through holes allow the potting compound to pass through. The potting compound located between the windings and the frame, between the frame and the core center post, and inside the first through hole constitutes a first heat dissipation path. The potting compound between the outermost winding and the side post, and inside the second through hole constitutes a second heat dissipation path.

[0007] With the above structure, a first through hole is opened at the position of the skeleton directly opposite the main air gap, and a second through hole is opened at the side post of the magnetic core. This allows the potting compound to flow directly into the transformer and fully wet the spaces such as the connection between the winding and the skeleton, the gap between the skeleton and the middle post of the magnetic core, and the gap between the outermost winding and the side post. This breaks the limitation of the potting compound in the traditional structure that it is difficult to penetrate into the internal hot spot area. By utilizing the high thermal conductivity of the potting compound, a first heat dissipation path is constructed from the high heat area inside the middle post of the magnetic core and the winding to the outside, and a second heat dissipation path is constructed from the outside of the high heat area of ​​the winding that was originally closed by the side post of the magnetic core to the outside. This effectively solves the problems of poor heat dissipation and local temperature rise in the existing technology, and allows for optimization of copper wire usage to reduce costs while reducing temperature rise.

[0008] Preferably, each group of first through holes includes a plurality of first through holes evenly distributed in the circumferential direction of the skeleton, and each group of first through holes is distributed along the length direction of the skeleton. This increases the total opening area of ​​the first through holes while ensuring the structural strength of the skeleton, allowing the potting compound to flow more evenly in all areas of the skeleton.

[0009] Preferably, a gap is provided between the skeleton and the core post to allow the potting compound to pass through, so that the potting compound can fully wet the contact interface between the core post and the skeleton, further enhancing the heat dissipation capacity of the central magnetic circuit area.

[0010] Preferably, the second through hole is a round hole, a square hole, or a slot-shaped hole, and the total volume of all the second through holes does not exceed 20% of the volume of the magnetic core side post. The two ends of the second through hole extend to the yoke in the length direction. While ensuring that the potting compound can pass through effectively and increasing the heat dissipation area of ​​the outer layer of the winding, it avoids affecting the mechanical strength and magnetic circuit performance of the magnetic core side post due to the excessively large opening. The sufficiently long second through hole can expand the second heat dissipation path, so that the high-heat winding area that was originally closed by the side post can obtain sufficient heat dissipation area.

[0011] Preferably, the winding includes a primary winding and a secondary winding, and the frame includes a hollow winding bobbin and a plurality of baffles disposed on the outer arc surface of the winding bobbin. The plurality of baffles include end baffles located at both ends of the winding bobbin and air gap baffles corresponding to both ends of the main air gap. A winding region for winding the winding is formed between the end baffles and the air gap baffles, separating the winding region from the main air gap region to prevent the winding from affecting the flow of potting compound.

[0012] Preferably, at least one first through hole is provided in the area between the two air gap baffles, and at least one first through hole is provided in each position of the winding area corresponding to multiple windings or winding coils, so that each winding area can obtain a direct potting compound flow channel and enhance the heat dissipation capacity of the central magnetic circuit area.

[0013] Preferably, the plurality of baffles further includes a winding baffle disposed in the winding region. The winding baffle divides the winding region into a plurality of sub-winding regions. Each winding is divided into a plurality of coils wound on different sub-winding regions. Different coils of the same winding are connected in series and wound on different winding regions. The segmented winding structure facilitates flexible adjustment of the transformer leakage inductance to adapt to different parameter requirements.

[0014] Preferably, the magnetic core column is further provided with a secondary air gap, the width of which is less than or equal to the width of the main air gap. By setting the secondary air gap, the magnetic circuit distribution can be further optimized and the electromagnetic characteristics of the transformer can be adjusted.

[0015] Preferably, a heat-conducting but non-magnetic pad is provided in the secondary air gap. The pad is in contact with the two end faces of the magnetic core column separated by the secondary air gap. By filling the secondary air gap with the heat-conducting pad, the effective conduction of heat from the column is ensured while maintaining a stable air gap width.

[0016] Preferably, the magnetic core assembly is an EE type magnetic core, an EI type magnetic core, a PQ type magnetic core, or an RM type magnetic core, and the main air gap is located in the middle column. The above magnetic core structures can be well adapted to the skeleton openings and side column openings to ensure that the potting compound forms an efficient heat dissipation path.

[0017] This invention establishes a direct heat dissipation channel from internal hot spots to the outside by using openings directly opposite the main air gap of the core and the side posts of the magnetic core. This significantly increases the heat dissipation area of ​​the outermost winding, greatly reducing the overall temperature rise. Due to the enhanced heat dissipation capacity, within the same design-allowed temperature rise limit, a higher current density (i.e., fewer strands of Litz wire) can be used, thereby reducing the amount of copper used in the winding and directly lowering material costs. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the transformer structure according to Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the magnetic core structure of Embodiment 1 of the present invention; Figure 3 This is a three-dimensional exploded view of the transformer in Embodiment 1 of the present invention; Figure 4 This is a three-dimensional exploded view of the transformer in Embodiment 2 of the present invention; Figure 5 This is a schematic diagram of the transformer structure in Embodiment 3 of the present invention. Detailed Implementation

[0019] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0020] Example 1

[0021] refer to Figures 1 to 3 This embodiment provides a CLLC resonant transformer based on magnetic integration and enhanced heat dissipation. The CLLC resonant transformer includes a magnetic core assembly, a frame 3, windings wound on the frame 3, and potting compound (not shown in the figure) filling the inside of the transformer.

[0022] The magnetic core assembly is of type EE, EI, PQ, or RM; in this embodiment, the magnetic core assembly used is type PQ, see reference. Figure 2 The transformer includes a first magnetic core 1 and a second magnetic core 2 with symmetrical structure. Both the first magnetic core 1 and the second magnetic core 2 include a yoke 101, a core center post 102 perpendicularly disposed at the geometric center of the yoke 101, and two core side posts 103 perpendicularly disposed at the edges of the yoke 101. The core center posts of the first magnetic core 1 and the second magnetic core 2 are connected to each other to form the central magnetic circuit of the transformer. A main air gap 104 is provided between the two core center posts 102. The main air gap 104 is perpendicular to the central axis of the magnetic core. The width of the main air gap 104 can be used to adjust the excitation inductance value of the transformer. The core side posts 103 of the first magnetic core 1 and the second magnetic core 2 are connected to each other to form the outer magnetic circuit of the transformer. There is no gap between the two core side posts 103.

[0023] The frame 3 is fitted around the two opposing magnetic core pillars 102, with a gap between it and the magnetic core pillars 102 allowing potting compound to pass through. The frame 3 includes a hollow winding drum and multiple baffles disposed on the outer arc surface of the winding drum and perpendicular to the central axis of the winding drum. The baffles are disposed at different positions along the length of the winding drum, including end baffles at both ends of the winding drum and air gap baffles corresponding to both ends of the main air gap 104. The spacing between the two air gap baffles can be used to adjust the resonant inductance value of the transformer. The frame 3 is made of engineering plastics with high thermal conductivity (such as PPS, PA46) or has embedded high thermal conductivity materials. The winding includes a primary winding 4 and a secondary winding 5. The area between adjacent end baffles and air gap baffles on the frame 3 is the winding area, and the primary winding 4 and secondary winding 5 are wound on the two winding areas respectively.

[0024] refer to Figure 3The bobbin of the skeleton 3 is provided with a plurality of first through holes 301. These plurality of first through holes 301 can be divided into multiple groups, each group including a plurality of first through holes 301 evenly arranged circumferentially on the bobbin. The multiple groups of first through holes 301 are distributed along the length of the bobbin. At least one group of first through holes 301 is located between two air gap baffles, that is, this group of first through holes 301 is located directly opposite the main air gap 104, and the winding paths of the primary winding 4 and the secondary winding 5 avoid the first through holes 301. The remaining groups of first through holes 301 are located in multiple winding areas on the skeleton 3. The shape of the first through holes 301 can be circular, elliptical, elongated, or polygonal, and its size and number are based on the principle of ensuring smooth flow of potting compound without weakening the mechanical strength of the skeleton. During potting, the potting compound can flow directly into the skeleton from the main air gap 104 through the first through hole facing the main air gap 104 without obstruction, and fully penetrate to the contact interface between the winding and the inner wall of the skeleton, so as to efficiently conduct the heat of this key connection to the external heat sink.

[0025] The magnetic core side post 103 is located on the periphery of the frame 3 and the winding. Each magnetic core side post 103 has a notch facing another magnetic core side post 103. The notches of two mating magnetic core side posts 103 are combined to form a second through hole 105. The second through hole 105 is a round hole, a square hole or a slot-shaped hole. The volume of the second through hole 105 does not exceed 20% of the volume of the side post. The two ends of the second through hole 105 extend to the yoke 101 in the length direction to increase the heat dissipation area. The width of the second through hole 105 is determined according to the material properties of the magnetic core to avoid the mechanical strength of the magnetic core side post 103 being insufficient due to the excessively large opening area.

[0026] The transformer is filled with potting compound, which fills the gaps between the various structures of the transformer, including the gap between the core column 102 and the frame 3, the first through hole 301, the second through hole 105, and the space on the inner and outer surfaces of the windings. During potting, the potting compound flows into the transformer interior from between the second through hole 105 and the core column 103, directly contacting and wrapping the outermost surface of the windings. This significantly increases the effective contact and heat dissipation area between the potting compound and the windings (especially in high-temperature areas) without significantly affecting the magnetic circuit performance. Simultaneously, it flows into the gap between the core column 102 and the frame 3 from the first through hole 301, thus wetting all windings and the core, forming a continuous heat dissipation path from the inside to the outside of the transformer. The potting compound is a high thermal conductivity silicone gel, with a thermal conductivity typically greater than 0.6. In the encapsulation process, the transformer is placed in a potting mold, and high thermal conductivity silicone gel is injected into the potting mold. After the potting compound cures, a complete and efficient heat dissipation network is formed. According to tests, under the same output power and heat dissipation conditions, the transformer in this embodiment has a center point temperature rise that is reduced by about 25% compared to the transformer with a traditional closed structure, and the amount of copper wire used can be reduced by about 10%.

[0027] Example 2

[0028] refer to Figure 4 The CLLC resonant transformer provided in this embodiment has a basically the same structure as the transformer described in the embodiment. The difference is that the core column 102 of the first magnetic core 1 and the second magnetic core 2 of the transformer in this embodiment each has an auxiliary air gap 106. The auxiliary air gap 106 is perpendicular to the central axis of the magnetic core. The width of the auxiliary air gap 106 is smaller than the width of the main air gap 104. The first magnetic core 1 and the second magnetic core 2 are still structurally symmetrical. The secondary air gap 106 contains a heat-conducting but non-magnetic pad, such as a heat-conducting ceramic sheet, a heat-conducting silicone sheet, or an epoxy board. The pad is in close contact with the two end faces of the magnetic core column 102 separated by the secondary air gap 106. When the pad is a heat-conducting ceramic sheet or an epoxy board, the pad is fixed to the two end faces of the magnetic core column 102 by adhesive bonding. If the pad is a heat-conducting silicone sheet, a pad of the same material but different thickness can be set in the main air gap 104. By utilizing the hollow skeleton and the fact that the inner diameter is slightly larger than that of the magnetic core column, it is ensured that the magnetic core column 102 does not undergo lateral displacement, while ensuring that the widths of the main air gap 104 and the secondary air gap 106 are within an acceptable error range.

[0029] Example 3

[0030] refer to Figure 5 The CLLC resonant transformer provided in this embodiment has a basically the same structure as the transformer described in the previous embodiment, the difference being in the frame 3 and the windings on the frame 3. The frame 3 includes a winding drum and multiple baffles. In addition to the end baffles and air gap baffles, a winding baffle is added to each of the original two winding regions. The winding baffles are also perpendicular to the central axis of the winding drum, dividing the original two winding regions into four winding regions. The primary winding 4 and the secondary winding 5 are each divided into two coils connected in series. The two coils of the primary winding 4 are wound in the two sub-winding regions near the ends, and the two coils of the secondary winding 5 are wound in the two sub-winding regions near the middle. This segmented winding structure, by controlling the structure of the primary winding 4 and the secondary winding 5, allows for further adjustment of the transformer leakage inductance, making it suitable for the design of specific resonant parameters.

[0031] Based on the above structural design, the resonant transformer proposed in this invention first establishes a direct heat dissipation channel from the internal hot spots (winding connections) to the outside through an opening design directly opposite the main air gap of the core; secondly, the opening design of the magnetic core side posts significantly increases the heat dissipation area of ​​the outermost winding. These two opening designs work together to efficiently dissipate heat from the transformer's interior through the potting compound, reducing the overall temperature rise by 15%-30% compared to traditional structures. Due to the enhanced heat dissipation capacity, within the same design-allowed temperature rise limit, a higher current density (i.e., fewer strands of Litz wire) can be used, thereby reducing the amount of copper used in the primary and secondary windings and directly lowering material costs.

[0032] On the other hand, the perforated structure ensures that the potting compound can completely fill more than 90% of the voids inside the transformer, improving insulation uniformity, mechanical stability, and long-term reliability. The perforations in the frame avoid the winding area, and the optimized design of the perforations on the core side posts has minimal impact on key electrical parameters such as leakage inductance (resonant inductance) and magnetizing inductance, ensuring the operating characteristics of the CLLC resonant circuit. This invention's resonant transformer requires no complex processes; it only requires adding a perforation process to existing frame and core molds, making it easy to industrialize.

[0033] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any brief modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A CLLC resonant transformer based on magnetic integration and enhanced heat dissipation, comprising a core assembly, a frame, windings wound on the frame, and potting compound filling the transformer interior, wherein the core assembly has a main air gap, and the core assembly includes a yoke, a core center post, and core side posts, characterized in that, The skeleton is provided with multiple sets of first through holes, at least one set of first through holes is located directly opposite the main air gap, the winding path of the winding avoids the first through holes directly opposite the main air gap and covers the remaining first through holes; the skeleton is sleeved around the outer periphery of the magnetic core center column and inside the magnetic core side column, and the magnetic core side column is provided with at least one second through hole; both the first through hole and the second through hole allow the potting compound to pass through.

2. The CLLC resonant transformer based on magnetic integration and enhanced heat dissipation according to claim 1, characterized in that, Each group of first through holes includes a plurality of first through holes evenly arranged in the circumferential direction of the skeleton, and each group of first through holes is distributed on the skeleton along the length direction of the skeleton.

3. The CLLC resonant transformer based on magnetic integration and enhanced heat dissipation according to claim 1, characterized in that: A gap is provided between the skeleton and the central column of the magnetic core to allow the potting compound to pass through.

4. The CLLC resonant transformer based on magnetic integration and enhanced heat dissipation according to claim 1, characterized in that: The second through hole is a round hole, a square hole, or a slot-shaped hole, and the total volume of all the second through holes does not exceed 20% of the volume of the side post of the magnetic core. The two ends of the second through hole extend to the yoke in the length direction.

5. The CLLC resonant transformer based on magnetic integration and enhanced heat dissipation according to claim 1, characterized in that: The winding includes a primary winding and a secondary winding. The frame includes a hollow winding drum and multiple baffles disposed on the outer arc surface of the winding drum. The multiple baffles include end baffles located at both ends of the winding drum and air gap baffles corresponding to both ends of the main air gap. A winding region for winding the winding is formed between the end baffles and the air gap baffles.

6. The CLLC resonant transformer based on magnetic integration and enhanced heat dissipation according to claim 5, characterized in that: The area between the two air gap baffles is provided with at least one first through hole, and the winding area is provided with at least one first through hole at each position corresponding to multiple windings or winding coils.

7. The CLLC resonant transformer based on magnetic integration and enhanced heat dissipation according to claim 5, characterized in that: The plurality of baffles also include winding baffles disposed in the winding region, the winding baffles dividing the winding region into a plurality of sub-winding regions, each winding being divided into a plurality of coils wound on different sub-winding regions, and different coils of the same winding being connected in series and wound on different winding regions.

8. The CLLC resonant transformer based on magnetic integration and enhanced heat dissipation according to claim 1, characterized in that: The magnetic core also has a secondary air gap, the width of which is less than or equal to the width of the main air gap.

9. The CLLC resonant transformer based on magnetic integration and enhanced heat dissipation according to claim 8, characterized in that: The secondary air gap contains a heat-conducting but non-magnetic pad, which is in contact with the two end faces of the magnetic core column separated by the secondary air gap.

10. The CLLC resonant transformer based on magnetic integration and enhanced heat dissipation according to claim 1, characterized in that: The magnetic core assembly is an EE type magnetic core, an EI type magnetic core, a PQ type magnetic core, or an RM type magnetic core, and the main air gap is located in the middle column.

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