Magnetic structure based on transverse magnetic field heat treatment, magnetic device and preparation method

Abstract

The invention provides a magnetic structure based on transverse magnetic field heat treatment, a magnetic device and a preparation method. The preparation method of the magnetic structure comprises the following steps: step 1, preparing a formed magnetic structure; and 2, performing magnetic field heat treatment on the magnetic structure, wherein the included angle between the direction of a magnetic field applied in the magnetic field heat treatment and the target magnetic flux direction of the magnetic structure is 80-100 degrees. In the heat treatment process, transverse magnetic anisotropy is artificially and purposefully established in the magnetic powder particles, the direct-current magnetic field saturation resistance of the magnetic structure is improved from the intrinsic characteristic of the material, and the direct-current bias performance of the magnetic structure is enhanced. Under the alternating-current and direct-current superposition working condition, the magnetic structure can ensure proper magnetic conductivity and can also have extremely high direct-current magnetic field saturation resistance. The magnetic structure can be a magnetic powder core or be used for manufacturing the magnetic powder core, so that the performance of the magnetic powder core better conforms to actual application scenes with large direct-current components such as PFC inductors and energy storage inductors, and the stability of a circuit and the miniaturization of components are guaranteed.

Description

Technical Field

[0001] This invention belongs to the field of magnetic structure heat treatment technology, and particularly relates to magnetic structures, magnetic devices and their preparation methods based on transverse magnetic field heat treatment. Background Technology

[0002] Soft magnetic composite materials (magnetic powder cores) are key fundamental components in modern power electronics technology, widely used in energy storage inductors, power factor correction (PFC) inductors, and electromagnetic interference (EMI) filters in inverters, frequency converters, switching power supplies, and other equipment. Their performance directly affects the efficiency, power density, and reliability of power conversion equipment.

[0003] In many practical applications, magnetic powder cores often operate under complex conditions where AC and DC magnetic fields act simultaneously. Specifically, a large DC bias magnetic field is superimposed on top of a high-frequency AC magnetic field. This is particularly common in high-current inductors of PFC circuits and DC choppers. Therefore, the DC bias characteristic of magnetic powder cores—that is, their ability to maintain effective permeability under the influence of a DC magnetic field—has become one of the core indicators for evaluating their performance.

[0004] In related technologies, the performance of magnetic powder cores is typically improved by optimizing the magnetic powder itself, such as using amorphous or nanocrystalline materials with high saturation magnetic induction. Another approach is to optimize the magnetic circuit structure through ring orientation preparation methods, directionally aligning the magnetic powder to optimize the magnetic circuit and reduce magnetic reluctance. However, these methods primarily aim for high initial permeability. But in AC / DC superposition field conditions, high permeability means a lower magnetic field strength is required to magnetize the material to saturation, causing the magnetic core to enter magnetic saturation more quickly. This leads to a sharp drop in effective permeability and a significant decrease in inductance, severely impacting circuit stability and component miniaturization. Furthermore, in high DC bias applications, high initial permeability results in poor core saturation resistance and unsatisfactory DC superposition characteristics. It is difficult to simultaneously achieve appropriate permeability and excellent DC saturation resistance. Summary of the Invention

[0005] The technical objective of this invention is to provide a magnetic structure, magnetic device, and fabrication method based on transverse magnetic field heat treatment. This aims to solve the technical problems in related technologies where the effective permeability of magnetic powder cores drops sharply under AC / DC superimposed field conditions; and simultaneously, it is difficult to simultaneously achieve appropriate permeability and excellent resistance to DC saturation. To solve the above-mentioned technical problems, the present invention is implemented as follows.

[0006] The first aspect of the present invention provides a method for preparing a magnetic structure based on transverse magnetic field heat treatment. The preparation method includes: step 1, preparing a shaped magnetic structure; step 2, subjecting the magnetic structure to magnetic field heat treatment, wherein the angle between the direction of the magnetic field applied during the magnetic field heat treatment and the direction of the target magnetic flux of the magnetic structure is 80°~100°.

[0007] Further, in some embodiments, step 2 includes: step 21, placing the magnetic structure between two permanent magnets or two electromagnets, with the angle between the magnetic field direction between the two permanent magnets or two electromagnets and the target magnetic flux direction of the magnetic structure being 80°~100°; step 22, placing the two permanent magnets or two electromagnets and the magnetic structure from step 21 in a heat treatment furnace under vacuum or a protective atmosphere, and heating them; step 23, setting coils on both sides of the heat treatment furnace, and passing current through them during the heat preservation stage, so that the angle between the magnetic field direction generated by the coils and the target magnetic flux direction of the magnetic structure is 80°~100°; step 24, removing the magnetic structure from the heat treatment furnace to obtain the heat-treated magnetic structure.

[0008] Furthermore, in some embodiments, the heating temperature in step 22 is 300~1100℃; the heating rate is 1~20℃ / min; and / or, the current in step 23 is 1~500A.

[0009] Further, in some embodiments, step 1 includes: step 11, preparing magnetic powder; step 12, insulating and coating the magnetic powder; step 13, adding a release agent to the magnetic powder; and step 14, obtaining a mold and molding the magnetic powder to obtain a shaped magnetic structure.

[0010] Furthermore, in some embodiments, the magnetic powder includes one or more of Fe, FeSi, FeSiAl, FeSiB, FeSiCr, FeNi, FeNiMo, FeSiAlNi, carbonyl Fe, amorphous magnetic powder, and nanocrystalline magnetic powder.

[0011] Further, in some embodiments, step 12 includes: preparing a phosphoric acid alcohol solution, wherein the mass ratio of phosphoric acid to alcohol is 0.001~0.005; mixing the phosphoric acid alcohol solution with magnetic powder, stirring and drying; wherein the mass ratio of the phosphoric acid alcohol solution to the magnetic powder of step 11 is 0.20~1.

[0012] Further, in some embodiments, step 12 includes: mixing resin, organic solvent, curing agent and magnetic powder, heating and stirring until the organic solvent evaporates, and then stirring and drying; wherein the mass ratio of the resin to the magnetic powder in step 11 is 0.005~0.06, the mass ratio of the organic solvent to the magnetic powder in step 11 is 0.02~0.1, and the mass ratio of the curing agent to the organic solvent is 0.02~0.05.

[0013] Furthermore, in some embodiments, the molding pressure in step 14 is 600~2200 MPa.

[0014] A second aspect of the present invention provides a magnetic structure, characterized in that it is prepared by the above-described preparation method.

[0015] Furthermore, in some embodiments, the magnetic structure is ring-shaped, square, elliptical, cylindrical, rhomboid, EQ-shaped, U-shaped, E-shaped, or irregularly shaped.

[0016] A third aspect of the present invention provides a magnetic device comprising the magnetic structure described above.

[0017] The heat treatment method of this invention has the following advantages compared with related technologies: This invention primarily designs the heat treatment process for magnetic structures. During heat treatment, a stable magnetic field is applied in a direction perpendicular or nearly perpendicular to the target magnetic flux direction of the magnetic structure. For example, if the target magnetic flux direction is longitudinal, a transverse magnetic field heat treatment can artificially and purposefully establish a transverse magnetic anisotropy within the magnetic powder particles. This anisotropy makes longitudinal magnetization difficult, thereby increasing transverse permeability and decreasing longitudinal permeability. This improves the magnetic structure's resistance to DC magnetic field saturation from the material's intrinsic properties, enhancing its DC bias performance. Therefore, this invention transforms the traditional longitudinal magnetic field heat treatment used to increase permeability into a transverse magnetic field heat treatment aimed at enhancing DC bias characteristics. This invention does not blindly pursue high permeability, but rather actively and controllably reduces the initial permeability for stable DC bias characteristics, resulting in a higher and more stable inductance across the entire operating current range. Therefore, in the case of AC and DC superposition, the magnetic structure of the present invention can not only ensure appropriate permeability, but also have extremely strong resistance to DC magnetic field saturation, making the performance of the magnetic structure more suitable for practical application scenarios with large DC components, such as PFC inductors and energy storage inductors, ensuring circuit stability and miniaturization of components. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art 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.

[0019] Figure 1 This is a schematic diagram of the heat treatment method for the magnetic structure in an embodiment of the present invention.

[0020] In the attached drawings, the reference numerals indicate: 1. Cover plate; 2. Core post. Detailed Implementation

[0021] Soft magnetic composite materials (magnetic powder cores) are key fundamental components in modern power electronics technology, widely used in energy storage inductors, power factor correction (PFC) inductors, and electromagnetic interference (EMI) filters in inverters, frequency converters, switching power supplies, and other equipment. Their performance directly affects the efficiency, power density, and reliability of power conversion equipment.

[0022] In many practical applications, magnetic powder cores often operate under complex conditions where AC and DC magnetic fields act simultaneously. Specifically, a large DC bias magnetic field is superimposed on top of a high-frequency AC magnetic field. This is particularly common in high-current inductors of PFC circuits and DC choppers. Therefore, the DC bias characteristic of magnetic powder cores—that is, their ability to maintain effective permeability under the influence of a DC magnetic field—has become one of the core indicators for evaluating their performance.

[0023] In many practical applications, magnetic powder cores often operate under complex conditions where AC and DC magnetic fields act simultaneously. Specifically, a large DC bias magnetic field is superimposed on top of a high-frequency AC magnetic field. This is particularly common in high-current inductors of PFC circuits and DC choppers. Therefore, the DC bias characteristic of magnetic powder cores—that is, their ability to maintain effective permeability under the influence of a DC magnetic field—has become one of the core indicators for evaluating their performance.

[0024] In related technologies, the performance of magnetic powder cores is typically improved by optimizing the magnetic powder itself, such as using amorphous or nanocrystalline materials with high saturation magnetic induction. Another approach is to optimize the magnetic circuit structure through ring orientation preparation methods, directionally aligning the magnetic powder to optimize the magnetic circuit and reduce magnetic reluctance. However, these methods primarily aim for high initial permeability. But in applications with superimposed DC fields, high permeability means a lower magnetic field strength is required to magnetize the material to saturation, causing the core to enter magnetic saturation more quickly. This results in a sharp drop in effective permeability and a significant decrease in inductance, severely impacting circuit stability and component miniaturization. Furthermore, in high DC bias applications, high initial permeability leads to poor core saturation resistance and unsatisfactory DC superposition characteristics. It is difficult to simultaneously achieve appropriate permeability and excellent DC saturation resistance.

[0025] Among related technologies, heat treatment processes are used to eliminate internal stress and regulate the magnetic structure. Currently, magnetic field heat treatment is an effective post-processing method. The main method employed is longitudinal magnetic field heat treatment, which involves annealing the magnetic powder core along its axial direction (i.e., the direction of the future working magnetic field) to align the magnetic moments in an orderly manner, thereby improving the longitudinal permeability of the material. However, the established longitudinal magnetic anisotropy makes the magnetic moments more prone to saturation under a DC bias field, leading to a sharp decrease in effective permeability and unstable inductance. This weakens the DC bias performance of the magnetic core, making it difficult to meet the requirements of high-current, high-bias applications (such as PFC inductors and energy storage inductors) for component performance stability and power density. In other words, the heat treatment processes in related technologies cannot meet the requirements of applications with high DC bias characteristics.

[0026] Therefore, there is an urgent need in this field for a novel processing method that can fundamentally enhance the ability of magnetic powder cores to resist DC magnetic field interference without significantly changing the core structure or reducing the saturation magnetic induction intensity of the material, that is, significantly improve their DC bias characteristics.

[0027] The following is a description of the technical solution provided by the present invention. For those skilled in the art, based on the ideas of the embodiments of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

[0028] Please see Figure 1 The first aspect of the present invention provides a method for preparing a magnetic structure based on transverse magnetic field heat treatment. The preparation method includes: step 1, preparing a shaped magnetic structure; step 2, subjecting the magnetic structure to magnetic field heat treatment, wherein the angle between the direction of the magnetic field applied in the magnetic field heat treatment and the direction of the target magnetic flux of the magnetic structure is 80°~100°.

[0029] This invention primarily designs the heat treatment process for the magnetic structure. During heat treatment, a stable magnetic field is applied in a direction perpendicular or nearly perpendicular to the target magnetic flux direction of the magnetic structure. For example, if the target magnetic flux direction is longitudinal, a transverse magnetic field heat treatment can be used to artificially and purposefully establish a transverse magnetic anisotropy within the magnetic powder particles. This anisotropy makes longitudinal magnetization difficult, thereby increasing transverse permeability and decreasing longitudinal permeability. This improves the magnetic structure's resistance to DC magnetic field saturation from the material's intrinsic properties, enhancing its DC bias performance. Therefore, this invention transforms the traditional longitudinal magnetic field heat treatment used to increase permeability into a transverse magnetic field heat treatment aimed at enhancing DC bias characteristics. This invention does not blindly pursue high permeability but actively and controllably reduces the initial permeability for stable DC bias characteristics, resulting in a higher and more stable inductance across the entire operating current range. Therefore, in AC / DC superposition conditions, the magnetic structure of this invention not only ensures appropriate permeability but also possesses extremely strong resistance to DC magnetic field saturation.

[0030] For example, the angle between the direction of the applied magnetic field and the direction of the magnetic flux of the target magnetic structure in magnetic heat treatment can be 80°, 82°, 85°, 88°, 90°, 92°, 95°, 98°, or 100°, etc. Figure 1 It can indicate that the direction of the magnetic field applied in magnetic field heat treatment is perpendicular to the magnetic flux direction of the target magnetic structure.

[0031] Understandably, the target magnetic flux direction of a magnetic structure is the direction of the expected working magnetic field of the magnetic structure, which is usually parallel to the axis of the magnetic structure.

[0032] Furthermore, the heat treatment process for the magnetic structure in this embodiment of the invention is applicable to magnetic structures of various shapes. For example, the magnetic structure can be ring-shaped, square, elliptical, cylindrical, rhomboid, EQ-shaped, U-shaped, E-shaped, or irregularly shaped, etc. Depending on the shape, the magnetic structure can be directly used as a magnetic powder core, or as a cover plate and core pillar for a magnetic powder core, and then the cover plate and core pillar are spliced ​​together to form the magnetic powder core. It has wide applications and strong practicality.

[0033] For example, a ring-shaped magnetic structure can be used directly as a magnetic powder core.

[0034] For example, please see Figure 1A square-shaped magnetic structure can serve as the cover plate 1, and a cylindrical magnetic structure can serve as the core column 2. Two cover plates 1 can be positioned on either side of the core column 2 along its axial direction, allowing them to be perpendicularly joined to form a magnetic powder core. The dashed line A represents the target magnetic flux direction of the magnetic structure; the double arrow B represents the direction of the magnetic field applied during magnetic field heat treatment of the core column; and the double arrow C represents the direction of the magnetic field applied during magnetic field heat treatment of the cover plate. This results in a magnetic powder core that not only maintains appropriate permeability but also possesses strong resistance to DC magnetic field saturation. This makes the performance of the magnetic powder core more suitable for practical applications with large DC components, such as PFC inductors and energy storage inductors, ensuring circuit stability and component miniaturization.

[0035] Furthermore, in some embodiments, step 2 includes: Step 21: Place the magnetic structure between two permanent magnets or two electromagnets, and the angle between the direction of the magnetic field between the two permanent magnets or two electromagnets and the direction of the target magnetic flux of the magnetic structure is 80°~100°. Step 22: Under vacuum or a protective atmosphere, place the two permanent magnets or two electromagnets and the magnetic structure from step 21 in a heat treatment furnace and heat them. Step 23: Set up coils on both sides of the heat treatment furnace, and pass current through them during the heat preservation stage so that the angle between the direction of the magnetic field generated by the coils and the direction of the magnetic flux of the target magnetic structure is 80°~100°. Step 24: Remove the magnetic structure from the heat treatment furnace to obtain the heat-treated magnetic structure.

[0036] In this embodiment of the invention, a magnetic structure is positioned between two permanent magnets or two electromagnets. The magnetic structure and the two permanent magnets, or the magnetic structure and the two electromagnets, with their relative positions determined, are placed in a heat treatment furnace. The magnetic structure is then heat-treated under a vacuum or protective atmosphere. During the heat treatment stage, the magnetic structure is heated to a specific temperature sufficient to activate atomic diffusion (typically below the Curie point), thereby eliminating internal residual stress generated during the material's fabrication process and providing energy for atomic rearrangement, leading to a more stable crystal structure. Additionally, coils are positioned on both sides of the heat treatment furnace. These coils generate magnetic fields, and the target magnetic flux direction of the magnetic structure is perpendicular or nearly perpendicular to the direction of the magnetic field generated by the coils, allowing the coils to generate a transverse magnetic field. Simultaneously, the two permanent magnets or two electromagnets enhance the strength of the transverse magnetic field. By subjecting the magnetic structure to magnetic field heat treatment, a magnetic anisotropy can be established within the magnetic powder. This artificially introduced anisotropy means that magnetization along the magnetic field direction becomes easier, while magnetization perpendicular to this direction becomes more difficult. The direct result is that although the overall initial permeability of the material decreases due to the restricted freedom of domain movement, the magnetization process becomes more controllable and linear along the expected DC bias direction. When a DC bias current is applied, the domains need to overcome a higher energy barrier to undergo irreversible flipping or violent movement, which allows the magnetic core to maintain a high effective permeability under a high DC magnetic field, significantly delaying the onset of magnetic saturation. In other words, the embodiments of the present invention enhance the ability of the magnetic structure to resist DC magnetic field interference from the intrinsic properties of the material by introducing transverse magnetic anisotropy. The magnetic structure treated by the method of the present invention exhibits a slow decay of effective permeability under a high-voltage DC bias field, demonstrating excellent DC superposition characteristics. This directly solves the core technical problem of easy saturation and sharp drop in inductance of traditional high-permeability materials under AC / DC superposition conditions, laying the foundation for the development of high-performance, high-reliability power inductor components.

[0037] For example, heat treatment furnaces include, but are not limited to, heat treatment furnaces, box furnaces, pit furnaces, etc.

[0038] Furthermore, in some embodiments, the magnetic structure is located at the center of two permanent magnets or two electromagnets, so that the magnetic structure is in a region with uniform magnetic field strength, thereby allowing for better heat treatment of the magnetic structure.

[0039] Furthermore, in some embodiments, the heating temperature in step 22 is 300~1100℃; the heating rate is 1~20℃ / min; and / or, the current in step 23 is 1~500A.

[0040] Specifically, the heating temperature can be 300, 400, 500, 600, 700, 800, 900, 1000, or 1100℃, etc. The heating rate can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20℃ / min, etc. By controlling the heating temperature and heating rate, the heat treatment process of the magnetic structure can be controlled. Excessively high heating temperatures will damage the integrity of the internal insulation of the magnetic structure, leading to overall performance deterioration; excessively rapid heating rates will prevent the internal stress of the magnetic structure from being released, resulting in the formation of microcracks or direct cracking; excessively slow heating rates will affect efficiency. Therefore, by controlling the heating temperature between 300 and 1100℃ and the heating rate between 1 and 20℃ / min, the entire heat treatment process can be carried out more effectively, resulting in a magnetic structure with superior performance.

[0041] Furthermore, the current can be 1, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 200, 300, 400, or 500 A, etc. The magnitude of the current controls the strength of the magnetic field generated by the coil, thereby regulating the heat treatment process of the magnetic structure. Too low a current cannot effectively improve the preferred orientation of the magnetic structure, while too high a current will cause an excessive decrease in the overall inductance of the magnetic structure, affecting normal operation. Therefore, by controlling the current between 1 and 500 A, the entire heat treatment process can be carried out more effectively, resulting in a magnetic structure with superior performance.

[0042] Furthermore, in some embodiments, step 1 includes: Step 11: Prepare magnetic powder; Step 12: Insulate the magnetic powder; Step 13: Add release agent to magnetic powder; Step 14: Obtain the mold and mold the magnetic powder to obtain the shaped magnetic structure.

[0043] Specifically, in the embodiments of the present invention, a shaped magnetic structure can be prepared first using conventional methods for preparing magnetic structures, and then the magnetic structure can be subjected to a heat treatment process. There is no need to make significant changes to the front-end processes such as powder preparation, insulation, mixing, and pressing. It can be achieved simply by adding a transverse magnetic field in the heat treatment furnace. This makes the heat treatment process of the embodiments of the present invention highly compatible with existing production lines, easy to promote industrialization, and relatively low in implementation cost.

[0044] Understandably, different shapes of magnetic structures can be obtained by using different molds, which have wide applications and strong practicality.

[0045] Furthermore, in some embodiments, the magnetic powder includes one or more of Fe, FeSi, FeSiAl, FeSiB, FeSiCr, FeNi, FeNiMo, FeSiAlNi, carbonyl Fe, amorphous magnetic powder, and nanocrystalline magnetic powder.

[0046] The heat treatment process for magnetic structures in this invention is not limited to iron-based amorphous materials, but can also be applied to soft magnetic materials such as nanocrystalline and permalloy powders. It has broad technical applicability and opens up new directions for the future development of serialized and specialized high-performance magnetic structure products.

[0047] Furthermore, the insulation covering method in step 12 may include inorganic insulation covering, organic insulation covering, or organic-inorganic composite insulation covering, etc.

[0048] In some embodiments, the magnetic powder can be insulated using an inorganic insulating coating method. For example, a phosphating process can be used for coating. Step 12 includes: preparing a phosphoric acid-alcohol solution, wherein the mass ratio of phosphoric acid to alcohol is 0.001~0.005; mixing the phosphoric acid-alcohol solution with the magnetic powder, stirring and drying; wherein the mass ratio of the phosphoric acid-alcohol solution to the magnetic powder is 0.20~1. The drying temperature can be 60~100℃, and the drying time is 1~6 h. Additionally, inorganic insulating coating may also include inorganic oxides such as silicon dioxide, magnesium oxide, calcium oxide, and manganese oxide, and silicates such as calcium silicate and sodium silicate. Simultaneously, in-situ oxidation processes such as chromic acid passivation and nitric acid passivation can be performed.

[0049] In some embodiments, the magnetic powder can be insulated by organic insulating coating. Step 12 includes: mixing resin, organic solvent, curing agent and magnetic powder, heating and stirring until the organic solvent evaporates, and then stirring and drying; wherein the mass ratio of resin to magnetic powder in step 11 is 0.005~0.06, the mass ratio of organic solvent to magnetic powder in step 11 is 0.02~0.1, and the mass ratio of curing agent to organic solvent is 0.02~0.05. Alternatively, the specific process can be: dissolving resin in organic solvent, then adding curing agent, then adding magnetic powder, and stirring at 60~100℃ for 10~15 min until anhydrous ethanol evaporates, and then letting it stand in a 60~120℃ forced-air drying oven for 1~8 h to fully dry, taking it out and stirring every 10~20 min during the drying process to avoid powder caking.

[0050] For example, organic insulating coatings may include silicone resins, epoxy resins, phenolic resins, modified silicone resins, modified epoxy resins, etc.

[0051] For example, organic solvents may include acetone, anhydrous ethanol, propylene glycol, etc.

[0052] For example, the curing agent may include KH550, KH560, KH570, KH792, A-151, etc.

[0053] Further, in some embodiments, step 13 specifically includes: drying the magnetic powder obtained in step 12, adding a release agent, and mixing them evenly, wherein the mass ratio of the release agent to the magnetic powder in step 12 is 0.001~0.004.

[0054] For example, the release agent may include zinc stearate or barium stearate.

[0055] Furthermore, in some embodiments, the molding pressure in step 14 is 600~2200 MPa.

[0056] Furthermore, in some embodiments, after step 2, the magnetic structure may be impregnated, cured, and sprayed.

[0057] Specifically, the impregnation liquid components may include a resin matrix (including but not limited to epoxy resins, silicone resins, polyurethane resins, and phenolic resins), a curing agent (crosslinking agents, including but not limited to acid anhydrides, amines, latent agents, and condensation reaction agents), a diluent (including but not limited to active diluents such as n-butyl glycidyl ether and 1,4-butanediol diglycidyl ether, and inactive diluents such as acetone, toluene, xylene, and alcohols), and auxiliary additives (including but not limited to defoamers, leveling agents, coupling agents, and pigments). The impregnated magnetic structure can be subjected to a curing heat treatment at a temperature of 140–300 °C. The cured magnetic structure can then be sprayed. The spraying process involves both liquid and powder materials, used for liquid or powder spraying. The spraying materials include the main film-forming substances (including but not limited to epoxy resin, modified epoxy resin, organic resin, and polyester resin), curing agents (crosslinking agents, including but not limited to acid anhydrides, amines, latent agents, and condensation reaction agents), pigments and fillers (including but not limited to titanium dioxide, carbon black, iron oxide red, barium sulfate, silica fume, talc, and kaolin), solvents (diluents, including but not limited to propylene glycol methyl ether, xylene, and butyl acetate), and auxiliary additives (including but not limited to dispersants, leveling agents, defoamers, and silane coupling agents). The magnetic structure after spraying can undergo curing heat treatment, with the curing heat treatment temperature ranging from 140 to 300 ℃.

[0058] A second aspect of the present invention provides a magnetic structure, which is prepared by a method for preparing magnetic structures.

[0059] Specifically, the magnetic structure prepared by the above method undergoes a magnetic field heat treatment process, resulting in a magnetic structure with excellent DC bias performance. By introducing transverse magnetic anisotropy, the ability of the magnetic structure to resist DC magnetic field interference is enhanced from the intrinsic properties of the material. The magnetic structure treated by the method of this invention exhibits slow decay of effective permeability under high-voltage DC bias, demonstrating excellent DC superposition characteristics. This directly solves the core technical problem of easy saturation and sharp drop in inductance of traditional high-permeability materials under AC / DC superposition conditions, laying the foundation for the development of high-performance, high-reliability power inductor components.

[0060] A third aspect of the present invention provides a magnetic device, including a magnetic structure.

[0061] Specifically, the magnetic devices can be inductors, transformers, etc. The magnetic structure prepared using this invention can be directly used as a magnetic powder core or used to fabricate magnetic powder cores. The magnetic powder core can be used as a magnetic core element to fabricate magnetic devices. Specifically, it can be used to fabricate power inductors, thereby enabling them to withstand larger DC currents without saturation within the same volume, or to achieve miniaturization of inductor elements within the same current specification, thus effectively improving the power density of the power module. Simultaneously, the stability of the inductance enhances the operational reliability of the entire circuit system.

[0062] Furthermore, a fourth aspect of the present invention can also provide a power supply module, including a magnetic device. The power supply module can be a PFC circuit, a DC-DC converter, etc.

[0063] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

Claims

1. A method for preparing a magnetic structure based on transverse magnetic field heat treatment, characterized in that, The preparation method includes: Step 1: Prepare the shaped magnetic structure; Step 2: Perform magnetic field heat treatment on the magnetic structure, and the angle between the direction of the magnetic field applied during the magnetic field heat treatment and the direction of the target magnetic flux of the magnetic structure is 80°~100°.

2. The preparation method according to claim 1, characterized in that, Step 2 includes: Step 21: Place the magnetic structure between two permanent magnets or two electromagnets, and the angle between the direction of the magnetic field between the two permanent magnets or two electromagnets and the direction of the target magnetic flux of the magnetic structure is 80°~100°. Step 22: Under vacuum or a protective atmosphere, place the two permanent magnets or two electromagnets and the magnetic structure from step 21 in a heat treatment furnace and heat them. Step 23: Set coils on both sides of the heat treatment furnace, and pass current through them during the heat preservation stage so that the angle between the direction of the magnetic field generated by the coil and the direction of the magnetic flux of the target magnetic structure is 80°~100°. Step 24: Remove the magnetic structure from the heat treatment furnace to obtain the heat-treated magnetic structure.

3. The preparation method according to claim 1, characterized in that, The heating temperature in step 22 is 300~1100℃; the heating rate is 1~20℃ / min; and / or the current in step 23 is 1~500A.

4. The preparation method according to claim 1, characterized in that, Step 1 includes: Step 11: Prepare magnetic powder; Step 12: Insulate the magnetic powder; Step 13: Add release agent to magnetic powder; Step 14: Obtain the mold and mold the magnetic powder to obtain the shaped magnetic structure.

5. The preparation method according to claim 4, characterized in that, The magnetic powder includes one or more of Fe, FeSi, FeSiAl, FeSiB, FeSiCr, FeNi, FeNiMo, FeSiAlNi, carbonyl Fe, amorphous magnetic powder, and nanocrystalline magnetic powder.

6. The preparation method according to claim 4, characterized in that, Step 12 includes: preparing a phosphoric acid-alcohol solution, wherein the mass ratio of phosphoric acid to alcohol is 0.001~0.005; mixing the phosphoric acid-alcohol solution with magnetic powder, stirring and drying; wherein the mass ratio of the phosphoric acid-alcohol solution to the magnetic powder from step 11 is 0.20~1; or, Step 12 includes: mixing resin, organic solvent, curing agent and magnetic powder, heating and stirring until the organic solvent evaporates, and then stirring and drying; wherein the mass ratio of the resin to the magnetic powder in step 11 is 0.005~0.06, the mass ratio of the organic solvent to the magnetic powder in step 11 is 0.02~0.1, and the mass ratio of the curing agent to the organic solvent is 0.02~0.

05.

7. The preparation method according to claim 4, characterized in that, The molding pressure in step 14 is 600~2200MPa.

8. A magnetic structure based on transverse magnetic field heat treatment, characterized in that, It is prepared by the preparation method according to any one of claims 1 to 7.

9. The magnetic structure according to claim 8, characterized in that, The magnetic structure is ring-shaped, square, elliptical, cylindrical, rhomboid, EQ-shaped, U-shaped, E-shaped, or irregular in shape.

10. A magnetic device, characterized in that, Includes the magnetic structure as described in claim 8 or 9.

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