Glue pouring type planar transformer

Abstract

The invention relates to the technical field of power electronic planar transformers, and discloses a glue pouring type planar transformer which comprises a shell. The magnetic core assembly is arranged in the shell and comprises a first magnetic core and a second magnetic core which are oppositely arranged, the number of the magnetic core cavities is at least two, and the adjacent magnetic core cavities are communicated through an air gap; the winding assembly is correspondingly arranged between the first magnetic core and the second magnetic core, and part of the winding assembly is contained in the magnetic core cavity; part of the filling piece is correspondingly filled in the air gap and the magnetic core cavity; and the contact surfaces of the magnetic core assembly, the winding assembly and the filling piece are filled with the thermal interface material. Compared with the prior art, influences on the height of a magnetic core window and the length of an air gap are reduced, inductance value drift caused by great expansion of pouring sealant is avoided, meanwhile, stress borne by the magnetic core is reduced, the magnetic core is prevented from cracking, and structural stability and inductance value stability of the transformer under the high-temperature working condition are guaranteed.

Description

A potting type planar transformer Technical Field

[0001] This invention relates to the field of power electronic planar transformer technology, and specifically to a potting type planar transformer. Background Technology

[0002] A potting-type planar transformer is a type of transformer that uses a planar winding structure. After assembling the windings and the magnetic core, the entire transformer is potted with insulating glue. Its windings are usually printed circuit board windings or thin copper sheet windings. It features small size, low height, and high power density. The potted insulating glue can strengthen the fixing effect between the windings and the magnetic core, improve insulation performance and heat dissipation, and enhance the product's resistance to vibration and shock. It is widely used in fields with high requirements for miniaturization and reliability, such as communication power supplies, industrial power supplies, and new energy vehicle electronics.

[0003] In related technologies, the body of a potted planar transformer is assembled and placed inside a housing. The housing, core window, and air gap are all filled with potting compound, and the bottom is tightly attached to a heat dissipation plate, allowing heat to be conducted and dissipated from top to bottom. A vertical distance is reserved between the windings and the air gap because the potting compound has a high coefficient of thermal expansion. When the transformer is heated during operation, it expands significantly, generating thermal stress in the vertical direction, leading to a decrease in inductance and, in severe cases, core cracking, which is more pronounced in high-power applications. Furthermore, the thermal conductivity of the potting compound also affects the heat dissipation effect between the PCB windings and the upper core. Summary of the Invention

[0004] This invention provides a potting type planar transformer to solve the problems of large temperature variation and poor heat dissipation of transformers in related technologies.

[0005] The present invention provides a potting type planar transformer, comprising: a housing; a magnetic core assembly disposed inside the housing, the magnetic core assembly including a magnetic core cavity; a winding assembly, a portion of the winding assembly being accommodated in the magnetic core cavity; a filler, the filler abutting against a portion of the winding assembly; and a thermal interface material filling each contact surface of the magnetic core assembly, the winding assembly, and the filler.

[0006] Beneficial effects: By placing fillers in the core cavity and air gap, and filling the contact surfaces of the core assembly, winding assembly, and fillers with thermal interface material, the fillers, made of materials with low thermal expansion coefficients, exhibit minimal expansion at high temperatures compared to traditional potting compounds. This significantly reduces the impact on the core window height and air gap length, avoiding inductance drift caused by significant expansion of the potting compound. Simultaneously, it reduces the stress on the core, preventing core cracking and ensuring the structural and inductance stability of the transformer under high-temperature conditions. Furthermore, the thermal interface material effectively fills the gaps between components due to height tolerances, eliminating contact thermal resistance. Combined with the high thermal conductivity of the fillers, this improves the heat transfer efficiency between the core, windings, and fillers, laying the foundation for subsequent heat dissipation and solving the problems of high thermal expansion coefficients and low thermal conductivity of potting compounds in traditional structures.

[0007] In one optional embodiment, the magnetic core assembly includes a first magnetic core and a second magnetic core disposed opposite to each other. The first magnetic core and the second magnetic core are fastened together to form a magnetic core cavity or a magnetic core cavity and an air gap. At least two magnetic core cavities are provided, and adjacent magnetic core cavities are connected through the air gap. A portion of the filler is correspondingly filled in the air gap and / or the magnetic core cavity. A winding assembly is correspondingly disposed between the first magnetic core and the second magnetic core.

[0008] Beneficial effects: By interlocking the first and second magnetic cores to form at least two magnetic core cavities and connecting adjacent cavities via air gaps, and simultaneously arranging the winding assembly between the two magnetic cores, the overall magnetic circuit layout is optimized. This allows the magnetic field to form a balanced closed loop within multiple cavities, effectively reducing magnetic flux leakage and improving the magnetic coupling efficiency between the magnetic cores and windings, thereby enhancing the stability and efficiency of the transformer's energy conversion. Secondly, the interconnected structure of multiple cavities and air gaps provides suitable space for the precise filling of subsequent fillers and the uniform laying of thermal interface materials. This allows fillers with low thermal expansion coefficients and high thermal conductivity to fully cover the core magnetic circuit area, further consolidating the stability of the inductance value and avoiding the problems of localized magnetic concentration and heat accumulation that are prone to occur in single-cavity structures.

[0009] In an alternative embodiment, a potting compound is also included, which fills the gap between the housing and the core assembly and winding assembly.

[0010] Beneficial effects: It retains the insulation advantages of traditional potting structures, and further improves the overall insulation performance of the transformer by venting air from the shell through potting, thus avoiding the risk of leakage between internal components; at the same time, it does not affect the low thermal expansion and high thermal conductivity of the core cavity and air gap. Under the premise of ensuring stable inductance and heat dissipation efficiency, it also takes into account the overall structural sealing of the transformer, preventing external dust, moisture and other impurities from entering the interior, extending the service life of the transformer, and achieving synergistic optimization of insulation, sealing and core performance.

[0011] In one alternative embodiment, a heat sink is also included, with the bottom of the housing connected to the heat sink, and an air gap is reserved between the inner wall of the magnetic core cavity and the filler.

[0012] Beneficial effects: The heat sink is connected to the bottom of the housing, providing a stable heat dissipation path for the transformer. This allows the heat from the core and windings to be efficiently conducted to the heat sink and dissipated through the filler and thermal interface material, significantly reducing the overall temperature rise and solving the heat dissipation problem of long heat conduction paths and high thermal resistance in traditional structures. The air gap provides a buffer space for stress release. When the winding components expand due to heat, they can deform towards the air gap by squeezing the thermal interface material, utilizing the compressibility of the gas to release the longitudinal expansion stress. This further weakens the impact of thermal expansion on the core window height and air gap length, enhances the stability of the inductance value, and avoids component damage caused by stress concentration, thereby improving the transformer's resistance to thermal shock.

[0013] In one optional embodiment, the magnetic core assembly is an EE-shaped magnetic core structure. The first and second magnetic cores, which are arranged opposite to each other, are both E-shaped structures. The E-shaped structure has at least two grooves. The grooves in the EE-shaped magnetic core structure are connected to form a magnetic core cavity, so that the winding assembly includes at least two winding units that are spaced apart vertically. The filler is adapted to fit and adhere to the winding unit and the air gap, respectively.

[0014] Beneficial effects: The double-groove structure of the EE-shaped magnetic core forms a core cavity that can better accommodate multiple winding units, meeting the power requirements of high-power scenarios; the precise fit between the filler and each winding unit and the air gap ensures that the heat of each winding unit can be efficiently conducted through the filler, while uniformly dispersing thermal expansion stress and avoiding local stress concentration caused by uneven force distribution in multi-winding structures; compared with the traditional EE-shaped structure, it not only solves the problem of excessive potting compound and significant thermal expansion impact in high-power transformers, but also improves power density and heat dissipation uniformity through the adaptation of multiple windings and fillers, enabling high-power transformers to maintain stable inductance and reliable performance at high temperatures.

[0015] In one optional embodiment, the magnetic core assembly is an EI-shaped magnetic core structure. The first magnetic core and the second magnetic core arranged opposite to each other are of E-shaped structure and I-shaped structure. The E-shaped structure has at least two grooves, and the I-shaped structure has a planar structure at the corresponding groove. The grooves and planar structures in the EI-shaped magnetic core structure form a magnetic core cavity. The winding assembly includes at least one winding unit, and the filler is adapted and fitted to the winding unit and the air gap respectively.

[0016] Beneficial effects: The core cavity formed by the E-shaped groove and I-shaped plane of the EI-shaped magnetic core can match the installation requirements of a single winding unit, making it suitable for medium-to-low power and compact applications; the fit between the filler and the winding unit and air gap simplifies the structure and reduces assembly complexity while retaining the advantages of low thermal expansion and high thermal conductivity; compared with the traditional EI-shaped potting structure, it solves the core problems of inductance drift and insufficient heat dissipation, while also taking into account structural simplicity and cost control, so that the EI-shaped planar transformer can significantly improve performance and reliability while maintaining the original compact structure advantage.

[0017] In one alternative embodiment, the thermal interface material is a thermally conductive material with fluidity or elasticity, suitable for filling the gaps formed between the magnetic core assembly, the winding assembly, and the filler.

[0018] Beneficial effects: The thermal interface material is clearly defined as a thermally conductive material with fluidity or elasticity. Its fluidity allows it to fully fill the tiny gaps between the magnetic core assembly, winding assembly, and filler, eliminating contact thermal resistance and ensuring the continuity and efficiency of heat conduction. This solves the heat conduction bottleneck caused by gaps in traditional rigid connections. Its elasticity or fluidity also gives it stress buffering capabilities. When the component expands due to heat, the thermal interface material can absorb some of the expansion stress through deformation, preventing the stress from being directly transferred to the magnetic core or filler. At the same time, it works with air gaps to release stress step by step, further consolidating the stability of the inductance value. Moreover, its high thermal conductivity ensures heat dissipation efficiency, achieving the dual functions of stress buffering and enhanced heat dissipation.

[0019] In one alternative implementation, the winding assembly expands along the height of the core cavity when heated, causing the thermal interface material to deform laterally toward the air gap, and releasing the longitudinal expansion stress by compressing the gas in the air gap.

[0020] Beneficial effects: The thermal expansion of the winding assembly along the height of the core cavity is transformed into lateral deformation by compressing the fluid thermal interface material, and then the stress is released by compressing the gas in the air gap. This solves the problem of thermal expansion stress directly acting on the core in traditional structures, so that the core window height and air gap length are basically unaffected by thermal expansion, ensuring that the inductance remains basically unchanged at high temperatures. At the same time, the stepwise release of stress avoids local stress concentration, preventing damage such as core cracking and winding deformation, significantly improving the thermal stability and service life of the transformer, and is especially suitable for working environments with large temperature fluctuations.

[0021] In one alternative embodiment, an adhesive is also included to bond the first magnetic core and the second magnetic core.

[0022] Beneficial effects: By bonding the first and second magnetic cores with adhesive, the overall structural integrity of the magnetic core assembly is enhanced. The adhesive firmly fixes the relative positions of the upper and lower magnetic cores, preventing core displacement caused by vibration, thermal shock, and other factors during transformer operation, ensuring the stability of the magnetic circuit, and thus ensuring the consistency of the inductance value.

[0023] In one alternative embodiment, the winding assembly is provided with copper terminals that are electrically connected to the winding assembly.

[0024] Beneficial effects: The use of copper terminals and the implementation of electrical connections optimize the electrical connection performance of the transformer. Copper terminals possess excellent conductivity, reducing contact resistance and losses during current transmission, minimizing localized heating caused by poor contact, and further reducing overall temperature rise. Attached Figure Description

[0025] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0026] Figure 1 is a cross-sectional view of the related EI-shaped potted planar transformer; Figure 2 is a cross-sectional view of the related EE-shaped potted planar transformer; Figure 3 is a cross-sectional view of the EI-shaped potted planar transformer of the present invention; Figure 4 is a cross-sectional view of the EE-shaped potted planar transformer of the present invention; Figure 5 is a schematic diagram of the stress analysis of the potted planar transformer of the present invention; Figure 6 is an exploded view of the potted planar transformer of the present invention. Reference numerals: 1. Shell; 2. First magnetic core; 3. Second magnetic core; 4. Potting compound; 5. Magnetic core cavity; 6. Adhesive; 7. Heat sink; 8. Air gap; 10. Thermal interface material; 11. Air gap; 12. Filler. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] As shown in Figure 1, the body of a traditional EI core potted planar transformer consists of PCB windings and upper and lower interlocking magnetic cores. The area of ​​the magnetic core that houses the PCB is called a window. To obtain a suitable inductance value, there is an air gap on the central column of the magnetic core, and the side columns of the magnetic core are fixed with adhesive. The transformer body is placed in a housing, with the bottom of the housing in close contact with a heat sink. All gaps in the housing are filled with potting compound to expel air and improve the overall thermal conductivity and insulation performance of the transformer. In some scenarios, to increase power, multiple PCB windings and EE-shaped magnetic cores are used, as shown in Figure 2. In this structure, the lower PCB and the magnetic core are bonded with adhesive to fix the PCB, and a gap is left between the upper PCB and the magnetic core, which is filled with potting compound. In this structure, the upper and lower magnetic cores and PCB windings are the main heat sources, and heat is conducted from top to bottom to the heat sink. To reduce copper losses caused by the air gap edge effect, a certain vertical distance is usually required between the PCB windings and the air gap.

[0029] Because the window and air gap are filled with potting compound, and the potting compound has a high coefficient of thermal expansion, when the transformer is heated during operation, the potting compound expands significantly, causing large outward thermal stress in the height direction within the window and air gap. This increases the air gap length and window height, leading to a decrease in transformer inductance at high temperatures. In severe cases, excessive stress can even cause core cracking, ultimately resulting in transformer damage. These problems are particularly pronounced in high-power transformers. To reduce copper losses caused by air gap edge effects, high-power transformers have a large vertical distance from the winding to the air gap, and the air gap length is also longer. This results in the potting compound occupying a large portion of the height of the window and air gap, expanding even further at high temperatures, causing a more severe decrease in inductance.

[0030] The embodiments of the present invention are described below with reference to Figures 1 to 6.

[0031] According to an embodiment of the present invention, a potting type planar transformer is provided, comprising: a housing; a magnetic core assembly disposed inside the housing, the magnetic core assembly including a magnetic core cavity, adjacent magnetic core cavities being connected through an air gap; a winding assembly, a portion of which is housed within the magnetic core cavity; alternatively, traditional Litz wire, flat copper wire, or round copper wire can be used instead of PCB as the winding material, depending on the application requirements, achieving stable high-temperature inductance and efficient heat dissipation in conjunction with the filler 12. The winding assembly is provided with copper terminals, which are electrically connected to the winding assembly. The copper terminals have excellent conductivity, reducing contact resistance and losses during current transmission, reducing localized heating due to poor contact, and further reducing overall temperature rise. The filler 12 abuts against a portion of the winding assembly; a thermal interface material 10 fills the contact surfaces of the magnetic core assembly, the winding assembly, and the filler 12. The thermal interface material 10 can be selected from thermally conductive silicone grease, thermally conductive gel, or other high thermal conductivity materials with a certain elasticity or fluidity.

[0032] As shown in Figures 3 and 4, by setting filler 12 in the core cavity 5 and air gap 8, with some filler 12 corresponding to the air gap 8 and / or core cavity 5, and filling the contact surfaces of the core assembly, winding assembly and filler 12 with thermal interface material 10, the filler 12 is made of a material with a low coefficient of thermal expansion. Compared with the traditional potting compound 4, the expansion at high temperature is minimal, which greatly reduces the impact on the core window height and air gap 8 length, avoids inductance drift caused by the large expansion of the potting compound 4, and reduces the stress on the core, preventing core cracking and ensuring the structural stability and inductance stability of the transformer under high temperature conditions. At the same time, the thermal interface material 10 can effectively fill the gaps reserved between components due to height tolerance, eliminate contact thermal resistance, and improve the heat conduction efficiency between the core, winding and filler 12 in combination with the high thermal conductivity of filler 12, laying the foundation for subsequent heat dissipation and solving the problem of large coefficient of thermal expansion and low thermal conductivity of potting compound 4 in the traditional structure.

[0033] The magnetic core assembly includes a first magnetic core and a second magnetic core arranged opposite each other. The first and second magnetic cores are fastened together to form a magnetic core cavity or a magnetic core cavity and an air gap. At least two magnetic core cavities are provided, and adjacent magnetic core cavities are connected through the air gap. The winding assembly is correspondingly arranged between the first and second magnetic cores. By correspondingly fastening the first and second magnetic cores to form at least two magnetic core cavities and connecting adjacent cavities through the air gap, and simultaneously arranging the winding assembly between the two magnetic cores, the overall layout of the magnetic circuit is optimized. This allows the magnetic field to form a balanced closed loop in multiple cavities, effectively reducing magnetic flux leakage and improving the magnetic coupling efficiency between the magnetic core and the winding, thereby enhancing the stability and efficiency of the transformer's energy conversion. Secondly, the interconnected structure of multiple cavities and air gaps provides suitable space for the precise filling of subsequent fillers and the uniform laying of thermal interface materials. This allows fillers with low thermal expansion coefficients and high thermal conductivity to fully cover the core magnetic circuit area, further consolidating the stability of the inductance value and avoiding the problems of local magnetic concentration and heat accumulation that are prone to occur in single-cavity structures.

[0034] The transformer also includes potting compound 4, which fills the gaps between the housing 1 and the core assembly and winding assembly. This retains the insulation advantages of traditional potting structures, allowing air to escape from the housing 1 and further improving the overall insulation performance of the transformer, thus avoiding the risk of leakage between internal components. Furthermore, it does not affect the low thermal expansion and high thermal conductivity of the core cavity 5 and air gap 8. While ensuring stable inductance and efficient heat dissipation, it also maintains the overall structural sealing of the transformer, preventing external dust, moisture, and other impurities from entering, extending the transformer's service life, and achieving synergistic optimization of insulation, sealing, and core performance.

[0035] In one embodiment, a heat sink 7 is also included. The bottom of the housing 1 is connected to the heat sink 7, and an air gap 11 is reserved between the inner wall of the magnetic core cavity 5 and the filler 12. The connection between the heat sink 7 and the bottom of the housing 1 provides a stable heat dissipation path for the transformer, allowing the heat from the magnetic core and windings to be efficiently conducted to the heat sink 7 and dissipated through the filler 12 and the thermal interface material 10, significantly reducing the overall temperature rise and solving the heat dissipation problem of long heat conduction paths and high thermal resistance in traditional structures. The air gap 11 provides a buffer space for stress release. When the winding assembly expands due to heat, it can deform towards the air gap 11 by squeezing the thermal interface material 10, utilizing the compressibility of the gas to release the longitudinal expansion stress, further weakening the impact of thermal expansion on the height of the magnetic core window and the length of the air gap 8, enhancing the stability of the inductance value, and avoiding component damage caused by stress concentration, thereby improving the transformer's resistance to thermal shock.

[0036] Specifically, the magnetic core assembly is an EE-shaped magnetic core structure. The first magnetic core 2 and the second magnetic core 3, which are arranged opposite to each other, are both E-shaped structures. The E-shaped structure has at least two grooves. The grooves in the EE-shaped magnetic core structure are connected to form a magnetic core cavity 5, so that the winding assembly includes at least two winding units that are spaced apart vertically. The filler 12 is adapted and fitted to the winding unit and the air gap 8 respectively. The core cavity 5 formed by the double groove structure of the EE-shaped magnetic core can better accommodate multiple winding units and meet the power requirements of high-power scenarios. The precise fit between the filler 12 and each winding unit and the air gap 8 ensures that the heat of each winding unit can be efficiently conducted through the filler 12, while uniformly dispersing thermal expansion stress and avoiding local stress concentration caused by uneven force in multi-winding structures. Compared with the traditional EE-shaped structure, it not only solves the problem of large filling amount of potting compound 4 and significant impact of thermal expansion in high-power transformers, but also improves power density and heat dissipation uniformity through the adaptation of multiple windings and filler 12, so that high-power transformers can still maintain stable inductance and reliable performance at high temperatures.

[0037] Alternatively, the core assembly can be an EI-shaped core structure. One of the first core 2 and the second core 3, positioned opposite each other, has an E-shaped structure and the other an I-shaped structure. The E-shaped structure has at least two grooves, while the I-shaped structure has a planar structure corresponding to the grooves. The grooves and planar structure in the EI-shaped core structure form a core cavity 5. The winding assembly includes at least one winding unit, and the filler 12 is adapted and fitted to both the winding unit and the air gap 8. The core cavity 5 formed by the E-shaped grooves and the I-shaped planar structure of the EI-shaped core can match the installation requirements of a single winding unit, making it suitable for low-to-medium power, compact applications. The fit between the filler 12 and the winding unit and air gap 8 simplifies the structure and reduces assembly complexity while retaining the advantages of low thermal expansion and high thermal conductivity. Compared to the traditional EI-shaped potting structure, this design solves the core problems of inductance drift and insufficient heat dissipation, while also maintaining structural simplicity and cost control. This significantly improves the performance and reliability of the EI-shaped planar transformer while maintaining its original compact structure.

[0038] Specifically, the thermal interface material 10 is a fluid or elastic thermally conductive material suitable for filling the gaps formed between the magnetic core assembly, winding assembly, and filler 12. The fluidity of the thermal interface material 10 allows it to fully fill the tiny gaps between the magnetic core assembly, winding assembly, and filler 12, eliminating contact thermal resistance and ensuring the continuity and efficiency of heat conduction, thus solving the heat conduction bottleneck caused by gaps in traditional rigid connections. Its elastic or fluid properties also provide stress buffering capabilities. When the components expand due to heat, the thermal interface material 10 can absorb some of the expansion stress through deformation, preventing the stress from being directly transmitted to the magnetic core or filler 12. Simultaneously, in conjunction with the air gap 11, stress is released gradually, further consolidating the stability of the inductance value. Furthermore, its high thermal conductivity ensures efficient heat dissipation, achieving the dual functions of stress buffering and enhanced heat dissipation.

[0039] A stress analysis of the winding assembly reveals that the heating of the winding assembly generates a force F1 as it expands along the height of the magnetic core cavity 5. Since the coefficient of thermal expansion of the winding assembly is higher than that of the ceramic filler 12 and the magnetic core, its longitudinal expansion directly acts on the thermal interface material 10 at the contact surface, causing the thermal interface material 10 to deform laterally towards the air gap 11, generating a force F2. F2 releases the longitudinal expansion stress F3 by compressing the gas within the air gap 11, utilizing the compressibility of the gas. Taking a window height of 20mm as an example, when the temperature rises from 25℃ to 100℃, the ceramic expands only 0.016mm due to heat. This expansion is negligible for the elastic thermal interface material 10, which has a total thickness of approximately 1mm. In contrast, the traditional potting compound 4 expands to a height of 0.5mm under the same conditions, significantly affecting the window height and the length of the air gap 8. In this invention, the thermal expansion of the winding assembly is released in stages, which solves the problem that thermal expansion stress directly acts on the magnetic core in the traditional structure. This ensures that the height of the magnetic core window and the length of the air gap are basically unaffected by thermal expansion, thus ensuring that the inductance remains basically unchanged at high temperatures. At the same time, the staged release of stress avoids local stress concentration, preventing damage such as magnetic core cracking and winding deformation, and significantly improving the thermal stability and service life of the transformer.

[0040] Furthermore, it also includes adhesive 6, which bonds the first magnetic core 2 and the second magnetic core 3. By bonding the first magnetic core 2 and the second magnetic core 3 with adhesive 6, the overall structural integrity of the magnetic core assembly is strengthened. Adhesive 6 can firmly fix the relative positions of the upper and lower magnetic cores, preventing magnetic core displacement caused by vibration, thermal shock, and other factors during transformer operation, ensuring the stability of the magnetic circuit, and thus ensuring the consistency of the inductance value.

[0041] The winding assembly is equipped with copper terminals, which are electrically connected to the winding assembly. The use of copper terminals and their electrical connection optimizes the transformer's electrical connection performance. Copper terminals have excellent conductivity, reducing contact resistance and losses during current transmission, minimizing localized heating caused by poor contact, and further reducing overall temperature rise.

[0042] It is worth noting that the filler 12 is made of ceramic. Ceramic materials have a very low coefficient of thermal expansion, resulting in minimal expansion at high temperatures. This fundamentally suppresses changes in the core window height and air gap 8 length, effectively solving the inductance drift problem. Simultaneously, the thermal conductivity of ceramic is much higher than that of the potting compound 4, significantly improving heat transfer efficiency and enhancing heat dissipation. Furthermore, ceramic possesses excellent insulation properties and structural stability, ensuring electrical insulation while providing stable support for the winding components and core. This avoids structural problems caused by deformation or failure of the filler 12 itself, reliably guaranteeing the core performance advantages of the transformer. The thermal conductivity of ceramic is significantly higher than that of the potting compound 4. The thermal conductivity of alumina is typically 20~20 W / m / K, aluminum nitride is typically 140~220 W / m / K, and the potting compound 4 is typically 1~4 W / m / K. The coefficient of thermal expansion of ceramics is generally 6~10 ppm / ℃, which is about 1 / 30 of that of potting compound 4. It expands very little at high temperatures. Due to the small coefficient of expansion, the stress of the window on the magnetic core in the height direction is very small.

[0043] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A potting-type planar transformer, characterized in that, include: Housing (1); magnetic core assembly disposed inside the housing (1), the magnetic core assembly including a magnetic core cavity (5); winding assembly, a portion of the winding assembly being accommodated in the magnetic core cavity (5); filler (12), the filler (12) abutting against a portion of the winding assembly; thermal interface material (10), the thermal interface material (10) filling each contact surface of the magnetic core assembly, the winding assembly and the filler (12).

2. The potting type planar transformer according to claim 1, characterized in that, The magnetic core assembly includes a first magnetic core (2) and a second magnetic core (3) disposed opposite to each other. The first magnetic core (2) and the second magnetic core (3) are fastened together to form the magnetic core cavity (5) or the magnetic core cavity (5) and the air gap (8). At least two magnetic core cavities (5) are provided. Adjacent magnetic core cavities (5) are connected through the air gap (8). Part of the filler (12) is correspondingly filled in the air gap (8) and / or the magnetic core cavity (5). The winding assembly is correspondingly disposed between the first magnetic core (2) and the second magnetic core (3).

3. The potting-type planar transformer according to claim 1, characterized in that, It also includes potting compound (4), which fills the gap between the housing (1) and the magnetic core assembly and the winding assembly.

4. The potting-type planar transformer according to claim 1, characterized in that, It also includes a heat sink (7), the bottom of the housing (1) is connected to the heat sink (7), and an air gap (11) is reserved between the inner wall of the magnetic core cavity (5) and the filler (12).

5. The potting-type planar transformer according to claim 2, characterized in that, The magnetic core assembly is an EE-shaped magnetic core structure. The first magnetic core (2) and the second magnetic core (3) arranged opposite to each other are both E-shaped structures. The E-shaped structure has at least two grooves. The grooves in the EE-shaped magnetic core structure are connected to form the magnetic core cavity (5), so that the winding assembly includes at least two winding units arranged vertically and vertically. The filler (12) is adapted to fit the winding unit and the air gap (8) respectively.

6. The potting-type planar transformer according to claim 2, characterized in that, The magnetic core assembly is an EI-shaped magnetic core structure. The first magnetic core (2) and the second magnetic core (3) arranged opposite to each other are of E-shaped structure and I-shaped structure. The E-shaped structure has at least two grooves. The I-shaped structure is a planar structure corresponding to the grooves. The grooves and the planar structure in the EI-shaped magnetic core structure form the magnetic core cavity (5). The winding assembly includes at least one winding unit. The filler (12) is adapted to fit the winding unit and the air gap (8) respectively.

7. The potting-type planar transformer according to claim 1, characterized in that, The thermal interface material (10) is a thermally conductive material with fluidity or elasticity, suitable for filling the gap formed between the magnetic core assembly, the winding assembly and the filler (12).

8. The potting type planar transformer according to claim 4, characterized in that, The winding assembly expands along the height direction of the magnetic core cavity (5) when heated, causing the thermal interface material (10) to deform laterally in the direction of the air gap (11), and releasing the longitudinal expansion stress by compressing the gas in the air gap (11).

9. The potting-type planar transformer according to claim 2, characterized in that, It also includes adhesive (6), which bonds the first magnetic core (2) and the second magnetic core (3).

10. The potting type planar transformer according to claim 1, characterized in that, The winding assembly is provided with copper terminals, which are electrically connected to the winding assembly.

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