Magnet, manufacturing method therefor, and electronic device

Abstract

The present application provides a magnet, a manufacturing method therefor, and an electronic device. The magnet of the present application comprises a soft magnetic material and a hard magnetic material, the mass ratio of the soft magnetic material to the hard magnetic material being (90-99):(1-10), and the magnet having a magnetic field. Using the magnet can significantly improve a bias property of an inductor while maintaining a high initial magnetic permeability of a magnet core, without increasing the number of turns in an inductor coil.

Description

Magnet and its preparation method, and electronic device

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office of the People's Republic of China on March 28, 2024, with application number 202410366678.5 and application name "Magnet and its preparation method, and electronic device", all of which are incorporated by reference into this application. Technical Field

[0003] The present application relates to magnetic materials, and in particular to a magnet and a preparation method thereof, and an electronic device. Background Art

[0004] As a power transmission device for energy, inductors have a significant impact on system cost and efficiency, typically requiring high permeability, high bias characteristics, and low losses. Traditional soft magnetic materials used to manufacture inductors primarily include ferrite and FeSi alloy powders, such as FeSi and FeSiAl. Ferrites have very high initial permeability, but poor saturation resistance, resulting in low bias characteristics. To improve saturation resistance, air gaps are introduced during inductor design, but this also reduces initial permeability, necessitating an increase in the number of coil turns to improve initial inductance. FeSi alloy powders have slightly better core bias characteristics than ferrites, but achieving both high initial permeability and high bias characteristics is difficult. To balance initial and bias performance, increasing the number of coil turns is an effective approach. Therefore, for ferrite inductors, initial performance degrades after the air gap is introduced, necessitating the addition of additional coils to maintain performance, thus failing to fully exploit the advantages of ferrite's high initial permeability. For alloy powder inductors, this is primarily achieved by adding coils. Given the intrinsic properties of FeSi alloy powders, high permeability makes it difficult to achieve high bias, and high permeability at high bias makes it difficult to achieve high permeability, resulting in a corresponding increase in cost. Currently, material performance development has reached saturation, making it extremely difficult to simultaneously improve both permeability and bias characteristics from the material side. Design-side improvement options are also very limited. A new material needs to be developed to achieve improvements in both initial permeability and bias characteristics without increasing the number of coil turns. Summary of the Invention

[0005] The present application provides a magnet, a preparation method thereof, and an electronic device, so as to maintain a high initial magnetic permeability of the inductor while significantly improving the bias characteristics of the inductor without increasing the number of turns of the coil in the inductor.

[0006] In a first aspect, the present application provides a magnet comprising a soft magnetic material and a hard magnetic material, wherein the mass ratio of the soft magnetic material to the hard magnetic material is (90-99):(10-1), and the magnet has a magnetic field.

[0007] The magnet of the present application, by adding a certain amount of hard magnetic material to the soft magnetic material, can orient the hard magnetic material through magnetic field forming or magnetic field heat treatment, so that the magnet has a magnetic field in a preset direction. The inductor prepared using the magnet of the present application, because its magnetic core has a magnetic field with a certain preset direction, the magnetic field can be opposite to the direction of the magnetic field generated after the inductor is energized, thereby offsetting part of the magnetic flux generated during the inductor energization process, thereby ensuring that the inductor obtains a significant improvement in the bias characteristics when the initial magnetic permeability decreases at a low rate, and the loss remains basically unchanged. The inductor formed by the magnet of the present application can improve the bias characteristics by 10%-40% while keeping the inductor design structure unchanged, effectively expanding the high current application scenario. While keeping the bias characteristics unchanged, the volume of the inductor can be reduced by 10%-50%, the resistance of the coil can be reduced by 10%-50%, and the cost can be reduced by 10%-40%.

[0008] In an optional implementation, the mass ratio of the soft magnetic material to the hard magnetic material is (92-97):(8-3).

[0009] The soft magnetic material includes at least one of ferrite, iron-silicon alloy powder, or sendust alloy powder, and the hard magnetic material includes at least one of permanent magnet ferrite, neodymium-iron-boron, samarium-cobalt, samarium-iron-nitride, manganese-bismuth, or iron-nitride.

[0010] In a second aspect, the present application provides a method for preparing a magnet, comprising: subjecting a composite powder comprising the soft magnetic material and the hard magnetic material to a molding process and a heat treatment to obtain the magnet; wherein at least one of the molding process and the heat treatment is performed in a magnetic field environment.

[0011] The magnet manufacturing method provided in this application achieves permanent magnetism in the hard magnetic material of the composite magnetic powder by magnetizing it during a molding or heat treatment process. This results in the resulting magnet possessing a magnetic field with a predetermined direction. When used to manufacture inductors, this magnet can partially offset the inductor's magnetic flux, thereby improving the inductor's bias characteristics.

[0012] When a magnetic field is applied during the forming process, the intensity of the magnetic field during the forming process is 1.5 T to 2.5 T. When a magnetic field is applied during the heat treatment, the intensity of the magnetic field applied during the heat treatment is greater than 2.5 T.

[0013] In a third aspect, the present application provides an electronic device comprising a circuit board and an inductor, the inductor comprising a magnetic core and a coil, at least part of the magnetic conductive portion of the magnetic core comprising the magnet of the first aspect of the present application; the coil is wound around part of the magnetic conductive portion of the magnetic core, wherein the direction of the magnetic field of the magnet is opposite to the direction of the magnetic field generated when the coil is energized.

[0014] In the electronic device of the present application, at least part of the magnetic conductive part of the magnetic core in the inductor includes the magnet of the present application, and the direction of the magnetic field of the magnet is opposite to the direction of the magnetic field generated after the coil is energized. Therefore, the magnetic field of the magnet can be used to offset the magnetic flux generated by the inductor during operation, improve the anti-saturation characteristics of the inductor, and thereby improve the bias characteristics of the inductor.

[0015] The magnetic core may be an E-shaped magnetic core, a U-shaped magnetic core or a Japanese-shaped magnetic core.

[0016] In one implementation, the magnetic core in the electronic device includes:

[0017] Center column, used for winding coils;

[0018] Side columns are provided on the sides of the center column, and the side columns are provided in parallel with the center column;

[0019] Wherein, at least one of the central column or the side column includes the magnet of the present application.

[0020] The magnetic core in the electronic device of the present application, the middle column and the side column are the high magnetic flux conduction parts of the magnetic core. At least one of the middle column and the side column includes the magnet of the present application, which can further enhance the magnetic flux generated by the inductor during operation, improve the anti-saturation characteristics of the inductor, and thereby improve the bias characteristics of the inductor.

[0021] The inductor used in the electronic device of this application can have at least one of the center and side legs of its core primarily formed from the magnet of this application. While maintaining the inductor design structure unchanged, the bias characteristics can be improved by 10%-40%, effectively expanding high-current application scenarios such as energy storage systems. While maintaining the bias characteristics unchanged, the inductor volume can be reduced by 10%-50%, the coil resistance can be reduced by 10%-50%, and the cost can be reduced by 10%-40%.

[0022] The electronic device of the present application may be, for example, a power converter, a current stabilizer, a filter, etc. The above electronic devices may be used in energy storage systems, communication equipment systems, and control systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] FIG1 is a schematic structural diagram of an inductor according to an embodiment;

[0024] FIG2 is a schematic structural diagram of a magnetic core according to an embodiment;

[0025] FIG3 is a schematic structural diagram of a magnetic core in an inductor according to an embodiment;

[0026] FIG4 is a schematic structural diagram of a magnetic core in an inductor according to another embodiment;

[0027] FIG5 is a schematic structural diagram of a magnetic core in an inductor according to another embodiment.

[0028] Reference numerals: 1 - inductor; 10 - magnetic core; 11 - middle column; 12 - side column; 13 - bottom plate; 14 - top plate; 20 - coil. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solutions and advantages of this application clearer, this application will be further described in detail below with reference to the accompanying drawings.

[0030] The terms used in the following embodiments are only for the purpose of describing specific embodiments and are not intended to limit the present application. As used in the specification and appended claims of this application, the singular expressions "a", "an", "above", "the", and "this" are intended to also include expressions such as "one or more", unless the context clearly indicates otherwise.

[0031] References to "one embodiment" or "some embodiments" in this specification mean that a particular feature, structure, or characteristic described in conjunction with that embodiment is included in one or more embodiments of the present application. Thus, phrases such as "in one embodiment," "in some embodiments," "in other embodiments," and "in yet other embodiments" appearing in various places in this specification do not necessarily refer to the same embodiment, but rather mean "one or more but not all embodiments," unless otherwise specifically emphasized. The terms "including," "comprising," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized.

[0032] Magnetic components are fundamental for converting electrical and magnetic energy. They primarily include transformers and inductors, and are widely used in industries such as communications, energy, automotive, and healthcare. They are crucial components for ensuring the safe and stable operation of electrical and electronic equipment. As core components in energy devices such as new energy inverters, inductors significantly impact system cost and efficiency. The current development trend for inductors in various new energy inverters is toward miniaturization, higher frequencies, and a shift toward low losses and high DC bias. Specifically, new energy inverters and new energy vehicles require inductors to exhibit strong anti-saturation properties. Inductance decreases with increasing DC bias. If the inductance decreases too much, the inductor becomes magnetically saturated and loses its effectiveness. High bias characteristics in inductors improve their ability to withstand DC current, effectively creating a high DC bias characteristic.

[0033] Figure 1 is a schematic diagram of the structure of an inductor according to one embodiment. As shown in Figure 1 , the inductor 1 includes a magnetic core 10 and a coil 20. Coil 20 is wound around at least a portion of the center leg of magnetic core 10. The number of turns of coil 20 can be designed based on the specific characteristics of the inductor.

[0034] The magnetic core in the embodiments of the present application may include a center column and side columns. The center column is used to wind the coil. The side columns are disposed to the sides of the center column and may be arranged parallel to the center column. At least one of the center column or the side columns includes the magnet of the present application. The direction of the magnetic field of the magnet is opposite to the direction of the magnetic field generated by the coil when energized.

[0035] Figure 2 is a schematic diagram of the structure of a magnetic core according to one embodiment. As shown in Figure 2 , the magnetic core 10 may be an E-shaped magnetic core. The magnetic core 10 may include a base plate 13, a center column 11, and two side columns 12. The center column 11 and the side columns 12 are both connected to the base plate 13, with the center column 11 positioned between the two side columns 12 and arranged parallel to the two side columns 12. Referring to Figures 1 and 2 , a coil 20 is wound around the surface of the center column 11.

[0036] The magnetic core of existing inductors is typically made of soft magnetic materials, such as ferrite or alloy powder. To improve the bias characteristics of the inductor, this is usually achieved by creating an air gap in the center leg or increasing the number of coil turns. However, creating an air gap in the center leg reduces the initial magnetic permeability, necessitating increasing the number of coil turns to maintain this reduction. Increasing the number of coil turns also increases the overall resistance of the inductor, which in turn increases the size and cost of the inductor and increases the heat dissipation during operation.

[0037] To solve the above problems, the present application provides a magnet comprising a soft magnetic material and a hard magnetic material. Wherein, the mass ratio of the soft magnetic material to the hard magnetic material is (90-99):(10-1), such as (92-97):(8-3), and another example is (93-96):(7-4). Based on the overall mass of the magnet, the mass proportion of the soft magnetic material can be, for example, 90-99%, such as 92-97%, and another example is 93-96%, and the mass proportion of the hard magnetic material can be, for example, 1-10%, such as 2-9%, and another example is 3-8%, and another example is 4-7%. Exemplarily, the mass proportion of the soft magnetic material in the magnet can be, for example, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% or a value between any two of the above values. The mass proportion of the hard magnetic material in the magnet may be, for example, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% or any value between any two of the above values.

[0038] As an example, the soft magnetic material includes, but is not limited to, at least one of ferrite, iron-silicon alloy powder, or sendust alloy powder. The hard magnetic material includes, but is not limited to, at least one of permanent magnet ferrite, neodymium-iron-boron, samarium-cobalt, samarium-iron-nitride, manganese-bismuth, or iron-nitride.

[0039] The magnet of the embodiment of the present application has a magnetic field with a preset direction. For example, the magnet can be magnetized during the preparation process of the magnet so that the hard magnetic material in the magnet obtains a permanent magnetic field. By setting a magnetic field with a preset direction, during the use of the inductor, a relatively large current needs to be applied to magnetize the magnetic core to a level without a preset magnetic field, which is equivalent to improving the bias characteristics of the inductor. It is understandable that in the battery core of the embodiment of the present application, the preset magnetic flux is provided by the hard magnetic material therein, and the direction of the preset magnetic field is fixed, which is suitable for DC scenarios and can always maintain a state of offsetting the inductor magnetic flux.

[0040] Wherein, a magnet having a preset magnetic field can be prepared by the following method: a composite powder comprising the soft magnetic material and the hard magnetic material is subjected to a molding process and a heat treatment to obtain the magnet. Wherein, during the preparation of the magnet, a magnetic field can be applied during the molding process of the magnet, or during the heat treatment process of the magnet, or during both the molding process of the magnet and the heat treatment process of the magnet. When a magnetic field is applied during the molding process of the magnet, the intensity of the magnetic field in the molding process is 1.5T-2.5T. When a magnetic field is applied during the heat treatment process of the magnet, the intensity of the applied magnetic field in the heat treatment is greater than 2.5T. A magnet with good orientation can be formed by magnetic field molding or magnetic field heat treatment. By optimizing the intensity of the magnetic field, the degree of orientation of the magnet can be controlled, and the degree of optimization of the bias characteristics can be determined.

[0041] When the magnet of the present application is used to make a magnetic core, the magnet of the present application can be used to form at least a partial structure of the magnetic core, such as a magnetic center column or side column.

[0042] FIG3 is a schematic diagram of the structure of a magnetic core in an inductor according to an embodiment. As shown in FIG3 , the magnetic core 10 may be a Japanese-shaped magnetic core, and may include a bottom plate 13, a top plate 14, side columns 12, and a middle column 11. The bottom plate 13, the top plate 14, and the two side columns 12 form a frame, and the middle column 11 is arranged in the frame, with its two ends respectively connected to the bottom plate 13 and the top plate 14. The side columns 12 on both sides are arranged on both sides of the middle column 11. In the structure shown in FIG3 , the middle column 11 may be formed by the magnet of the embodiment of the present application.

[0043] Figure 4 is a schematic diagram of the structure of a magnetic core in an inductor according to another embodiment. As shown in Figure 4 , the two side legs 12 in the magnetic core can be made of the magnet according to the embodiment of the present application.

[0044] Figure 5 is a schematic diagram of the structure of a magnetic core in an inductor according to another embodiment. As shown in Figure 5 , one side column 12 in the magnetic core can be made of the magnet according to the embodiment of the present application.

[0045] When the center and side legs are formed from the magnets of the present invention, the magnets can generate a magnetic field with a predetermined direction within the magnetic core. This direction is opposite to the magnetic field generated by the inductor coil when energized. Since the inductor generates magnetic flux within the coil when energized, the predetermined magnetic field can partially offset the inductor's magnetic flux, thereby improving the inductor's bias characteristics.

[0046] In addition to being used to form the center column and side columns, the magnet can also be used to form the bottom plate and top plate, which will not be described in detail here. In addition, the structure of the magnetic core above is only an example, and the magnetic core of this application can also be an E-shaped magnetic core or a U-shaped magnetic core.

[0047] Based on the same technical purpose, an embodiment of the present application also provides an electronic device comprising a circuit board and an inductor. At least a portion of the magnetically conductive portion of the magnetic core of the inductor comprises the magnet of the embodiment of the present application. A coil is wound around the portion of the magnetically conductive portion of the magnetic core, and the magnetic field of the magnet is directed in the opposite direction to the magnetic field generated when the coil is energized.

[0048] The performance of the magnetic core of the present application will be further described in detail below with reference to the embodiments and comparative examples.

[0049] Example 1

[0050] This embodiment is a magnetic core, and the results can be seen in Figure 3. The magnetic core includes a bottom plate 13, a top plate 14, a middle column 11 and side columns 12 on both sides. Among them, the material of the middle column 11 includes soft magnetic material and hard magnetic material. The soft magnetic material is alloy powder, and the hard magnetic material is neodymium iron boron. The mass ratio of alloy powder to neodymium iron boron is 90:10. The above raw materials are evenly mixed in a mixer to form a composite magnetic powder, which is formed using a traditional magnetic powder core process, placed in a magnetic field hot sintering furnace, and heat treated at an annealing temperature of 550-850°C. The magnetic field strength is 3T to form a high magnetic permeability and high bias magnetic core with a specific orientation of neodymium iron boron permanent magnets.

[0051] Example 2

[0052] This embodiment is a magnetic core, and the results can be seen in Figure 3. The magnetic core includes a bottom plate 13, a top plate 14, a middle column 11 and side columns 12 on both sides. Among them, the material of the middle column 11 includes soft magnetic material and hard magnetic material. The soft magnetic material is alloy powder, and the hard magnetic material is samarium iron nitrogen. The mass ratio of alloy powder to samarium iron nitrogen is 90:10. The above raw materials are evenly mixed in a mixer to form a composite magnetic powder. The magnetic field forming hot pressing process is used for forming, with a hot pressing temperature of 80-200°C, a pressure of 50-500MPa, and a magnetic field strength of 2T to form a magnetic core blank with a specific orientation of samarium iron nitrogen permanent magnet. The blank is placed in a heat treatment furnace and heat treated at an annealing temperature of 100-500°C to form a high magnetic permeability and high bias magnetic core.

[0053] Example 3

[0054] The difference between the magnetic core of this embodiment and that of embodiment 1 is that the ratio of the soft magnetic material to the hard magnetic material of the center column is different, specifically 92:8.

[0055] Example 4

[0056] The difference between the magnetic core of this embodiment and that of embodiment 1 is that the ratio of the soft magnetic material to the hard magnetic material of the center column is different, specifically 94:6.

[0057] Example 5

[0058] The difference between the magnetic core of this embodiment and that of embodiment 1 is that the ratio of the soft magnetic material to the hard magnetic material of the center column is different, specifically 96:4.

[0059] Example 6

[0060] The difference between the magnetic core of this embodiment and that of embodiment 1 is that the ratio of the soft magnetic material to the hard magnetic material of the center column is different, specifically 98:2.

[0061] Comparative Example 1

[0062] The difference between the magnetic core of this comparative example and that of Example 1 is that the ratio of the soft magnetic material to the hard magnetic material of the center column is different, specifically 80:20.

[0063] Comparative Example 2

[0064] The difference between the magnetic core of this comparative example and that of Example 1 is that the ratio of the soft magnetic material to the hard magnetic material of the center column is different, specifically 99.5:0.5.

[0065] The raw material ratios of the magnetic cores of various embodiments and comparative examples are listed in Table 1.

[0066] Inductors were assembled using the magnetic cores of each embodiment, and the bias characteristics of the corresponding inductors of each embodiment and comparative example were tested with the same number of turns. The test results are listed in Table 1. The assembled inductors of each embodiment and comparative example were identical except for the center leg.

[0067] The bias characteristic test process is as follows: With all components other than the center column of the fixed inductor unchanged, the relevant tests are performed with different center columns. Initial inductance is measured using a conventional LCR meter, and saturation inductance is measured using a DC bias tester at a current of 30A. Bias characteristic = saturation inductance / initial inductance.

[0068] Table 1

[0069] Referring to Table 1, the inductors corresponding to the magnetic cores of Examples 1-6 can improve the bias characteristics by 20% while keeping the inductor design structure unchanged, and the initial magnetic permeability is not significantly reduced compared to the inductor of pure soft magnetic material in Comparative Example 2, effectively expanding high current application scenarios, such as energy storage systems.

[0070] The initial inductances of the inductors corresponding to Examples 1-6 are all above 9.9μH, while the initial inductance of Comparative Example 1 is below 8.5μH, which is much lower than the initial magnetic flux of the inductors of Examples 1-6. This shows that when the content of hard magnetic material exceeds 10%, the initial magnetic permeability of the inductor will drop significantly. Although the bias characteristics of the inductor composed of the magnetic core of Comparative Example 1 have been greatly improved, the initial magnetic flux is relatively low, which also shows that its initial magnetic permeability is low and does not meet the requirements of high current application scenarios.

[0071] In addition, while keeping the inductor bias characteristics unchanged, the number of coil turns in the inductor can be significantly reduced, the volume of the inductor can be reduced by 30%, the resistance of the coil can be reduced by 20%, and the cost can be reduced by 20%.

[0072] The above are only specific embodiments of the present application, but the scope of protection of this application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A magnet, characterized in that: The invention comprises a soft magnetic material and a hard magnetic material, wherein the mass ratio of the soft magnetic material to the hard magnetic material is (90-99):(10-1), and the magnet has a magnetic field.

2. The magnet according to claim 1, wherein The mass ratio of the soft magnetic material to the hard magnetic material is (92-97):(8-3).

3. The magnet according to claim 1 or 2, characterized in that The soft magnetic material includes ferrite, iron-silicon alloy powder, or sendust alloy powder.

4. The magnet according to any one of claims 1 to 3, characterized in that The hard magnetic material includes at least one of permanent magnet ferrite, neodymium iron boron, samarium cobalt, samarium iron nitrogen, manganese bismuth, and iron nitrogen.

5. A method for preparing a magnet, characterized in that: The preparation method is used to prepare the magnet according to any one of claims 1 to 4, comprising: The magnet is obtained by subjecting a composite powder comprising the soft magnetic material and the hard magnetic material to a molding process and a heat treatment; wherein at least one of the molding process and the heat treatment is performed in a magnetic field environment.

6. The preparation method according to claim 5, characterized in that When a magnetic field is applied during the molding process, the applied magnetic field strength is 1.5T-2.5T; when a magnetic field is applied during the heat treatment, the applied magnetic field strength is greater than 2.5T.

7. An electronic device, characterized in that: The inductor comprises a circuit board and an inductor, wherein the inductor comprises a magnetic core and a coil, wherein at least a portion of the magnetic conductive portion of the magnetic core comprises the magnet according to any one of claims 1 to 4; and the coil is wound around the portion of the magnetic conductive portion of the magnetic core; The direction of the magnetic field of the magnet is opposite to the direction of the magnetic field generated when the coil is energized.

8. The electronic device according to claim 7, wherein: The magnetic core comprises: a center column for winding the coil; Side columns are provided on the sides of the center column, and the side columns are provided in parallel with the center column; Wherein, at least one of the center column or the side column includes the magnet.

9. The electronic device according to claim 7 or 8, characterized in that: The magnetic core is an E-shaped magnetic core, a U-shaped magnetic core or a Japanese-shaped magnetic core.

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