Integrally-formed inductor magnetic core structure

Abstract

The invention discloses an integrally-formed inductance core structure which comprises an inductance coil, a magnetic core and a dielectric layer, the inductance coil is wrapped by the magnetic core, the dielectric layer is arranged in the magnetic core, the central axis of the inductance coil is located on the plane where the dielectric layer is located, the inductance coil is separated by the dielectric layer, and the resistance value of the dielectric layer is higher than that of the inductance coil. According to the integrally-formed inductance magnetic core structure, the dielectric layer is arranged, the resistance value of the dielectric layer is higher than that of an inductance coil, the eddy-current loss of an inductor under high frequency can be reduced, and therefore the pressure resistance performance of the integrally-formed inductance magnetic core structure is improved, and the loss of the integrally-formed inductance magnetic core structure under high frequency is reduced. The invention relates to the field of integrally formed inductors.

Description

Technical Field

[0001] The present application relates to the field of integrally formed inductors, and in particular to an integrally formed inductor magnetic core structure. Background Art

[0002] Soft magnetic core is the key to inductors. Commonly used magnetic core materials include metals and alloys, ferrites, and soft magnetic composites. Soft magnetic composites (SMC), also known as magnetic powder cores, are made of magnetic particles that are bonded and pressed with surface insulation coatings. Magnetic powder cores combine the advantages of metal soft magnetism and ferrite soft magnetism. They have both high saturation magnetization and high resistivity. While obtaining high magnetic permeability, they can effectively reduce eddy current losses. In addition, it also has the advantages of three-dimensional isotropy, good frequency characteristics, and easy processing. Therefore, magnetic powder core materials are widely used in various medium and high frequency AC devices in the kHz to MHz range, such as power transformers, rectifiers and filter inductors, photovoltaic and vehicle inverters, and electromagnetic components in power drive systems. It is the fastest growing magnetic material in recent years.

[0003] When the one-piece molded inductor is working, an alternating current is usually passed through the coil and an alternating magnetic field and an alternating electric field perpendicular to the magnetic field are generated in the magnetic core. The soft magnetic core will produce eddy current loss in the alternating electric field, and repeated magnetization in the alternating magnetic field will produce hysteresis loss and residual loss. These three losses are closely related to the electrical and magnetic properties of the soft magnetic core.

[0004] Therefore, a new type of inductor core structure is needed to reduce eddy current loss at high frequency, thereby reducing the overall loss of the inductor and improving the voltage resistance performance of the inductor. Summary of the invention

[0005] The present application aims to solve at least one of the technical problems existing in the prior art. To this end, the present application proposes an integrally formed inductor core structure, which can reduce eddy current loss at high frequencies, reduce the overall loss of the inductor, and improve the withstand voltage performance of the integrally formed inductor.

[0006] According to the first aspect of the present application, the one-piece molded inductor core structure includes an inductor coil, a magnetic core and a dielectric layer, the magnetic core wraps the inductor coil, the dielectric layer is arranged in the magnetic core, the central axis of the inductor coil is located in the plane where the dielectric layer is located, the dielectric layer separates the inductor coil, and the resistance value of the dielectric layer is higher than the resistance value of the inductor coil.

[0007] The one-piece molded inductor core structure according to the embodiment of the present application has at least the following beneficial effects: by setting a dielectric layer, the resistance value of the dielectric layer is higher than that of the inductor coil, which can reduce the eddy current loss of the inductor at high frequency, thereby improving the voltage resistance performance of the one-piece molded inductor core structure and reducing the loss of the one-piece molded inductor core structure at high frequency.

[0008] According to some embodiments of the present application, at the intersection of the dielectric layer and the inductor coil, an angle between a plane where the dielectric layer is located and the electric field direction of the inductor coil is 60 to 90 degrees.

[0009] According to some embodiments of the present application, a resistance value of the dielectric layer is at least 1Ω / m.

[0010] According to some embodiments of the present application, the dielectric layer penetrates the magnetic core.

[0011] According to some embodiments of the present application, the dielectric layer is completely located inside the magnetic core.

[0012] According to some embodiments of the present application, the soft magnetic material in the dielectric layer includes, but is not limited to, manganese zinc ferrite, nickel zinc ferrite, carbonyl iron powder coated with an insulating layer, FeSiCr, and amorphous FeSiB.

[0013] According to some embodiments of the present application, the soft magnetic material is an integrally formed inductor prepared from carbonyl iron powder coated with a dielectric layer, FeSiCr, and amorphous FeSiB atomized spherical powder, or an inductor with a coil inside made of crushed amorphous powder.

[0014] According to some embodiments of the present application, the magnetic core is formed by pressing magnetic particles of one component, or by pressing a mixture of magnetic particles of several different components.

[0015] According to some embodiments of the present application, the shape of the magnetic core is a cube, a cuboid or a cylinder; the winding shape of the inductor coil is a circle, an ellipse or a polygon; and the shape of the dielectric layer is a sheet or a fan-shaped column.

[0016] According to some embodiments of the present application, the inductor coil is a solid or hollow wire; the inductor coil is a single-strand wire, a multi-strand wire or a Litz wire.

[0017] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings are used to provide further understanding of the technical solution disclosed in the present application and constitute a part of the specification. Together with the embodiments disclosed in the present application, they are used to explain the technical solution disclosed in the present application and do not constitute a limitation on the technical solution disclosed in the present application.

[0019] Figure 1 A three-dimensional diagram of the current core structure;

[0020] Figure 2Schematic diagram of the changes of soft magnetic particles during the pressing process;

[0021] Figure 3 It is a schematic diagram of the current direction, magnetic field direction and electric field direction in the inductor;

[0022] Figure 4 is the equivalent circuit diagram of soft magnetic particles;

[0023] Figure 5 This is the eddy current change diagram of soft magnetic particles before and after rupture;

[0024] Figure 6 A three-dimensional diagram of the integrally formed inductor core structure of an embodiment of the present application;

[0025] Figure 7 The effect of the dielectric layer in the integrally formed inductor magnetic core structure on the inductance of the integrally formed inductor at different frequencies in the embodiment of the present application;

[0026] Figure 8 The effect of the dielectric layer in the integrally formed inductor magnetic core structure on the total loss of the integrally formed inductor at different frequencies in the embodiment of the present application;

[0027] Fig. 9 This is a schematic structural diagram of an integrated inductor core structure using multiple dielectric layers in an embodiment of the present application.

[0028] Figure numerals: 100 - inductor, 200 - magnetic core, 300 - dielectric layer, 400 - soft magnetic particles with insulating coating, 500 - soft magnetic particles with broken insulating coating after pressing, 600 - equivalent resistance, 700 - equivalent capacitance, 800 - eddy current inside soft magnetic particles, 900 - eddy current between soft magnetic particles. DETAILED DESCRIPTION

[0029] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be understood as limiting the present application.

[0030] In the description of the present application, it should be understood that descriptions involving orientation, such as up, down, front, back, left, right, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0031] In the description of this application, "several" means more than one, "more" means more than two, "greater than", "less than", "exceed", etc. are understood to exclude the number itself, and "above", "below", "within", etc. are understood to include the number itself. If there is a description of "first" or "second", it is only used for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0032] In the description of this application, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in this application based on the specific content of the technical solution.

[0033] In the description of the present application, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0034] Soft magnetic core is the key to inductors. Commonly used magnetic core materials include metals and alloys, ferrites, and soft magnetic composites. Soft magnetic composites (SMC), also known as magnetic powder cores, are made of magnetic particles that are bonded and pressed with surface insulation coatings. Magnetic powder cores combine the advantages of metal soft magnetism and ferrite soft magnetism. They have both high saturation magnetization and high resistivity. While obtaining high magnetic permeability, they can effectively reduce eddy current losses. In addition, it also has the advantages of three-dimensional isotropy, good frequency characteristics, and easy processing. Therefore, magnetic powder core materials are widely used in various medium and high frequency AC devices in the kHz to MHz range, such as power transformers, rectifiers and filter inductors, photovoltaic and vehicle inverters, and electromagnetic components in power drive systems. It is the fastest growing magnetic material in recent years.

[0035] When the one-piece molded inductor is working, an alternating current is usually passed through the coil and an alternating magnetic field and an alternating electric field perpendicular to the magnetic field are generated in the magnetic core. The soft magnetic core will produce eddy current loss in the alternating electric field, and repeated magnetization in the alternating magnetic field will produce hysteresis loss and residual loss. These three losses are closely related to the electrical and magnetic properties of the soft magnetic core.

[0036] In this regard, the present application proposes an integrated inductor core structure. By setting a dielectric layer 300, the resistance value of the dielectric layer 300 is higher than that of the inductor coil 100, which can reduce the eddy current loss of the inductor at high frequency, thereby improving the voltage resistance performance of the integrated inductor core structure and reducing the loss of the integrated inductor core structure at high frequency.

[0037] At present, one-piece molded inductors are usually pressed and molded from iron-based soft magnetic alloys. Figure 1 , which includes a coil 100 and a magnetic core 200. It is a process of coating the surface of the soft magnetic alloy powder particles with an insulating shell layer through an insulating coating process. During the pressing process, the magnetic powder will deform, or the particles will rub against each other, causing the insulating coating layer of the magnetic powder to break and the particles to contact each other. Figure 2 The soft magnetic particles 400 with the insulating coating layer are under pressure to form soft magnetic particles 500 with the insulating coating layer broken after pressing.

[0038] According to Faraday's law of electromagnetic induction, when the integrally formed inductor is working, the direction of the magnetic induction intensity inside the magnetic core 200 is perpendicular to the coil, and the induced electric field is along the winding direction of the coil, such as Figure 3 As shown in the figure, due to factors such as particle deformation and friction between particles during the pressing process of the one-piece inductor, the coating layer on the surface of the particles fails, resulting in the inductor's magnetic core having a high conductivity.

[0039] Since inductors usually work in an alternating magnetic field, refer to Figure 4 In the direction of the induced electric field, the metal-based magnetic powder can be regarded as an equivalent inductor 600, the insulating coating between the magnetic powders can be regarded as an equivalent capacitor 700, and the equivalent circuit of two mutually contacting coated particles in the direction of the induced electric field can be regarded as a series capacitor and inductor.

[0040] At present, the resistivity of magnetic powder cores is usually improved by studying the coating process of soft magnetic composite materials. Under ideal conditions, the particles are insulated from each other, such as Figure 5 As shown in (a), the eddy current 800 inside the soft magnetic particles is confined inside the particles, and the eddy current 900 between the soft magnetic particles flows along the gaps between the soft magnetic particles. Its equivalent circuit is the equivalent resistance of n particles in the direction of the induced electric field and the equivalent capacitance of n dielectric layers in series:

[0041] ||Z x ||=R x +X c :

[0042] R x =R1+R2+…+R n ;

[0043]

[0044] Assuming that all particles have the same shape, dielectric layer thickness and shape, the equivalent resistance of the particles is the same, and the equivalent capacitance of the dielectric layer between particles is the same, that is:

[0045] R1=R2=…=R n ;

[0046] C1=C2=…=C n .

[0047] Therefore, the equivalent impedance of the equivalent circuit is:

[0048]

[0049] Without considering the phase difference between the current in the coil and the eddy current in the inductor, the current intensity in the loop is:

[0050]

[0051] The power loss of the loop due to eddy current is:

[0052] P=I 2 nR1.

[0053] However, during the pressing process, due to the deformation of the soft magnetic powder or the friction between the particles, the insulating coating of the magnetic powder core will be broken and the magnetic powder particles will contact each other. On the one hand, this will lead to a reduction in the dielectric layer in the equivalent circuit, and on the other hand, it will lead to the contact between the particles and the reduction of the equivalent resistance. Figure 5 As shown in (b) in the figure. Ideally, only the case where the dielectric layer fails due to rupture of the dielectric layer is considered, that is, the equivalent resistance of the equivalent circuit remains unchanged, and the equivalent inductance number decreases, that is, n decreases, and the impedance of the equivalent circuit |Z x | decreases, the equivalent current I increases, causing the eddy current loss power to increase. The energy of eddy current loss is eventually released in the form of heat. Therefore, an increase in equivalent current will generate more heat in the electric field loop, causing the inductor temperature to rise. Since the resistance part of the impedance is determined by the material properties, increasing the capacitive reactance of the electric field loop can reduce the current intensity of the eddy current and reduce the heat generated when the inductor is working.

[0054] In this regard, the present application proposes an integrated inductor core structure, referring to Figure 6 , which includes an inductor 100, a magnetic core 200 and a dielectric layer 300. The magnetic core 200 wraps the inductor 100, the dielectric layer 300 is arranged in the magnetic core 200, and the central axis of the inductor 100 is located in the plane where the dielectric layer 300 is located. It is worth noting that the dielectric layer 300 separates the inductor 100, and the resistance value of the dielectric layer 300 is higher than the resistance value of the inductor.

[0055] Since the dielectric layer 300 is parallel to the direction of the magnetic field, it has little effect on the inductance of the integrated inductor. Figure 7 The added dielectric layer 300 provides several high capacitive reactances in the path of the electric field, which can effectively reduce the eddy current intensity of the one-piece molded inductor when working at high frequency, and reduce the eddy current loss of the one-piece molded inductor. Figure 8 shown.

[0056] At the same time, since the added dielectric layer 300 is perpendicular to the induced electric field, it can be regarded as multiple capacitors connected in series in the electric field. In a series circuit, since the total voltage is distributed to each capacitor, the more dielectric layers 300 there are, the lower the voltage value across each dielectric layer 300. For an integrated inductor, since the withstand voltage strength of a single dielectric layer 300 is certain, adding a dielectric layer 300 to the magnetic core 200 can improve the withstand voltage strength of the integrated inductor.

[0057] Furthermore, the high-resistivity dielectric layer 300 can be specifically air, or other high-resistivity materials, such as ceramics, glass, resin, etc. In order to ensure the inductance performance of the device, it is preferred to have high magnetic permeability, high saturation induction and low coercivity, and at the same time have a high resistivity compared to the magnetic powder core, such as soft ferrite, etc. The high resistivity here means that the resistivity of the dielectric layer 300 material is at least one order of magnitude higher than that of the final formed magnetic powder core. The resistance value of the dielectric layer is at least 1Ω / m.

[0058] Furthermore, the number of dielectric layers 300 can be multiple, which further reduces the loss of the one-piece inductor core structure at high frequencies and improves the withstand voltage performance. Fig. 9 In (a), four dielectric layers 300 are symmetrically distributed in the magnetic core 200 . Fig. 9 In (b), eight dielectric layers 300 are symmetrically distributed in the magnetic core 200. The number of insulating layers can be determined according to actual needs.

[0059] The dielectric layers 300 are symmetrically distributed in the magnetic core 200 . The angles between every two adjacent dielectric layers 300 can be consistent, or different angles can be designed between adjacent dielectric layers at different positions.

[0060] Specifically, at the intersection of the dielectric layer 300 and the inductor 100 , the angle between the plane where the dielectric layer 300 is located and the electric field direction of the inductor 100 is 60 to 90°.

[0061] Specifically, the dielectric layer 300 can be pressed and molded by adding high-resistivity materials at corresponding positions through a specific mold before the one-piece molded inductor is pressed and molded, or openings can be added at specific positions through mechanical processing after the one-piece molded inductor is pressed and molded, and then filled with corresponding insulating materials.

[0062] Furthermore, by designing different molds, the dielectric layer 300 can be designed to be located inside the magnetic core 200 , perpendicular to the direction of the electric field in the magnetic core 200 when the inductor is working, and to penetrate or not penetrate the magnetic core 200 .

[0063] Specifically, the soft magnetic material in the dielectric layer includes, but is not limited to, manganese zinc ferrite, nickel zinc ferrite, carbonyl iron powder coated with an insulating layer, FeSiCr, and amorphous FeSiB.

[0064] Furthermore, the soft magnetic material is an integrally formed inductor made of carbonyl iron powder, FeSiCr and amorphous FeSiB atomized spherical powder coated with a dielectric layer, or an inductor with a coil inside made of crushed amorphous powder. In terms of composition, the magnetic core is pressed from magnetic particles of one component, or pressed from a mixture of magnetic particles of several different components.

[0065] Further, the shape of the magnetic core 200 is a cube, a cuboid or a cylinder; the winding shape of the inductor 100 is a circle, an ellipse or a polygon; the shape of the dielectric layer 300 is a sheet or a fan-shaped column. It is easy to understand that the winding shape of the inductor 100, the shape of the magnetic core 200 and the shape of the dielectric layer 300 can be changed according to actual conditions, and will not be repeated here.

[0066] Furthermore, the inductor 100 is a solid or hollow wire; the inductor 100 is a single-strand wire, a multi-strand wire or a Litz wire.

[0067] The embodiments of the present application are described in detail above in conjunction with the accompanying drawings, but the present application is not limited to the above embodiments. Various changes can be made within the knowledge of ordinary technicians in the relevant technical field without departing from the purpose of the present application. In addition, the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

Claims

1. An integrally formed inductor core structure, characterized in that: It includes an inductor coil, a magnetic core and a dielectric layer, wherein the magnetic core wraps the inductor coil, the dielectric layer is arranged in the magnetic core, the central axis of the inductor coil is located in the plane where the dielectric layer is located, the dielectric layer separates the inductor coil, and the resistance value of the dielectric layer is higher than the resistance value of the inductor coil.

2. The molded inductor core structure according to claim 1, characterized in that: At the intersection of the dielectric layer and the inductor coil, the angle between the plane where the dielectric layer is located and the electric field direction of the inductor coil is 60 to 90 degrees.

3. The molded inductor core structure according to claim 1, characterized in that: The resistance value of the dielectric layer is at least 1Ω / m.

4. The molded inductor core structure according to claim 1, characterized in that: The dielectric layer penetrates the magnetic core.

5. The molded inductor core structure according to claim 4, characterized in that: The dielectric layer is completely located inside the magnetic core.

6. The molded inductor core structure according to claim 1, characterized in that: The soft magnetic material in the dielectric layer includes but is not limited to manganese zinc ferrite, nickel zinc ferrite, carbonyl iron powder coated with an insulating layer, FeSiCr and amorphous FeSiB.

7. The molded inductor core structure according to claim 6, characterized in that: The soft magnetic material is an integrally formed inductor made of carbonyl iron powder coated with a dielectric layer, FeSiCr and amorphous FeSiB atomized spherical powder, or an inductor with a coil inside made of crushed amorphous powder.

8. The molded inductor core structure according to claim 1, characterized in that: The magnetic core is formed by pressing magnetic particles of one component, or by pressing magnetic particles of several different components after mixing.

9. The molded inductor core structure according to any one of claims 1 to 8, characterized in that: The shape of the magnetic core is a cube, a cuboid or a cylinder; the winding shape of the inductor coil is a circle, an ellipse or a polygon; the shape of the dielectric layer is a sheet or a sector column.

10. The molded inductor core structure according to any one of claims 1 to 8, characterized in that: The inductor coil is a solid or hollow wire; the inductor coil is a single-strand wire, a multi-strand wire or a Litz wire.

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