An integrally formed inductor core structure

Abstract

The application discloses an integrally-formed inductance magnetic core structure, which comprises an inductance coil, a magnetic core and a dielectric layer. The magnetic core wraps the inductance coil, and the dielectric layer is arranged in the magnetic core. The central axis of the inductance coil is located in the plane where the dielectric layer is located. The dielectric layer separates the inductance coil, and the resistance value of the dielectric layer is higher than that of the inductance coil. The integrally-formed inductance magnetic core structure is provided with the dielectric layer, the resistance value of the dielectric layer is higher than that of the inductance coil, the eddy current loss of the inductance under high frequency can be reduced, the pressure resistance 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 application relates to the integrally-formed inductance field.

Description

TECHNICAL FIELD

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

[0002] The soft magnetic core is the key of the inductor. The commonly used magnetic core materials include metals and alloys, ferrite and soft magnetic composite materials. The soft magnetic composite material (SMC) is also called magnetic powder core, which is made by bonding and pressing of magnetic particles coated with surface insulation. The magnetic powder core combines the advantages of metal soft magnetic and ferrite soft magnetic, has high saturation magnetization and high resistivity, and can effectively reduce the eddy current loss while obtaining high permeability. In addition, it also has the advantages of three-dimensional isotropy, good frequency characteristics, easy processing, etc. Therefore, the magnetic powder core material is widely used in various kHz~MHz range high frequency alternating current devices, such as power transformer, rectifier and filter inductor, photovoltaic and vehicle-mounted inverter, and electromagnetic components in power drive system, etc., and is the fastest growing magnetic material in application in recent years.

[0003] During the operation of the integrally formed inductor, an alternating current is usually passed through the coil to generate an alternating magnetic field in the magnetic core and an alternating electric field perpendicular to the magnetic field. The soft magnetic core will generate eddy current loss in the alternating electric field and hysteresis loss and residual loss due to repeated magnetization in the alternating magnetic field. These three kinds of losses are closely related to the electrical and magnetic properties of the soft magnetic core.

[0004] To this end, a new type of inductor magnetic core structure is needed to reduce the eddy current loss at high frequency, thereby reducing the overall loss of the inductor and improving the voltage resistance performance of the inductor. SUMMARY

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

[0006] According to the integrally formed inductor magnetic core structure of the first aspect of the present application, the magnetic core wraps the inductor coil, and 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 that of the inductor coil.

[0007] According to the integrally formed inductor magnetic core structure of the present application, at least the following beneficial effects are achieved: by arranging the 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 integrally formed inductor magnetic core structure and reducing the loss of the integrally formed inductor magnetic core structure at high frequency.

[0008] According to some embodiments of the present application, the dielectric layer is intersected by the inductor coil, and the angle between the plane where the dielectric layer is located and the electric field direction of the inductor coil is 60-90°.

[0009] According to some embodiments of the present application, the resistance value of the dielectric layer is at least 1 Ω / 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 dielectric layer comprises soft magnetic material, and the soft magnetic material comprises at least one of 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 atomized spherical powder or broken amorphous powder of carbonyl iron powder coated with an insulating layer, FeSiCr, and amorphous FeSiB.

[0014] According to some embodiments of the present application, the magnetic core is pressed from magnetic particles of one component or is pressed after mixing 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; and the inductor coil is a single-strand wire or a multi-strand wire.

[0017] Additional aspects and advantages of the present application will be in part apparent and in part pointed out hereinafter. BRIEF DESCRIPTION OF DRAWINGS

[0018] The accompanying drawings are included to provide a further understanding of the present application, and constitute a part of the specification, illustrate embodiments of the present application and explain the technical solutions of the present application, and do not constitute a limitation on the technical solutions of the present application.

[0019] Figure 1 It is a three-dimensional diagram of the current magnetic core structure;

[0020] Figure 2 It is a schematic diagram of the change of the soft magnetic particles during the pressing process;

[0021] Figure 3 Fig. 1 is a schematic diagram of the current direction, magnetic field direction and electric field direction in the inductor coil;

[0022] Figure 4 Fig. 2 is an equivalent circuit diagram of the soft magnetic particles;

[0023] Figure 5 Fig. 3 is a diagram of the eddy current change of the soft magnetic particles before and after the rupture;

[0024] Figure 6 Fig. 4 is a three-dimensional diagram of the integrally formed inductor magnetic core structure of the embodiment of the present application;

[0025] Figure 7 Fig. 5 is the influence of the dielectric layer in the integrally formed inductor magnetic core structure of the embodiment of the present application on the inductance of the integrally formed inductor at different frequencies;

[0026] Figure 8 Fig. 6 is the influence of the dielectric layer in the integrally formed inductor magnetic core structure of the embodiment of the present application on the total loss of the integrally formed inductor at different frequencies;

[0027] Figure 9 Fig. 7 is a structural schematic diagram of the integrally formed inductor magnetic core structure of the embodiment of the present application using multiple dielectric layers.

[0028] Fig. 1 is a schematic diagram of the current direction, magnetic field direction and electric field direction in the inductor coil; DETAILED DESCRIPTION

[0029] The embodiments of the present application are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar notations represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the accompanying drawings are exemplary, only for explaining the present application, and cannot be understood as a limitation of the present application.

[0030] In the description of the present application, it is understood that the orientation description, such as the orientation or position relationship indicated by up, down, front, back, left, right, etc. is based on the orientation or position relationship shown in the drawings, only for the convenience of describing the present application and simplifying the description, and is not intended to indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application.

[0031] In the description of the present application, the meaning of several is more than one, the meaning of multiple is more than two, greater than, less than, more than, etc. are understood as not including the number, above, below, etc. are understood as including the number. If it is described as first, 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 indicated technical features or the sequence of indicated technical features.

[0032] In the description of the present application, unless otherwise explicitly limited, the words such as setting, installing, connecting, etc. should be broadly understood, and those skilled in the art can reasonably determine the specific meaning of the above words in the present application in combination with the specific content of the technical solution.

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

[0034] The soft magnetic core is the key of the inductor. The commonly used magnetic core materials include metals and alloys, ferrite and soft magnetic composite materials. Soft magnetic composite material (SMC) is also called magnetic powder core, which is bonded and pressed by magnetic particles coated with surface insulation. The magnetic powder core combines the advantages of metal soft magnetic and ferrite soft magnetic, has high saturation magnetization and high resistivity, can effectively reduce the eddy current loss while obtaining high permeability. In addition, it also has the advantages of three-dimensional isotropy, good frequency characteristics, easy processing, etc. Therefore, the magnetic powder core material is widely used in various kHz~MHz range high frequency alternating current devices, such as power transformer, rectifier and filter inductor, photovoltaic and vehicle-mounted inverter, and electromagnetic components in power drive system, etc. It is the fastest growing magnetic material in application in recent years.

[0035] When the integrally formed inductor works, 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 hysteresis loss and residual loss in the alternating magnetic field. The three kinds of losses are closely related to the electrical and magnetic properties of the soft magnetic core.

[0036] To this end, the application provides an integrally formed inductor magnetic core structure. By arranging a dielectric layer 300, the resistance 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 of the integrally formed inductor magnetic core structure and reducing the loss of the integrally formed inductor magnetic core structure at high frequency.

[0037] At present, integrally formed inductors are usually made of iron-based soft magnetic alloy by pressing. Referring to Figure 1 , it includes a coil 100 and a magnetic core 200. It is coated with an insulating shell layer on the surface of the soft magnetic alloy powder particles by an insulation 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. Referring to Figure 2 , the soft magnetic particles 400 with an insulating coating layer are under pressure, forming soft magnetic particles 500 with broken insulating coating layers after pressing.

[0038] According to Faraday's law of electromagnetic induction, when the integrally formed inductor is working, 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, as shown in Figure 3 . Due to the deformation of the particles and the friction between the particles during the pressing process of the integrally formed inductor, the coating layer on the surface of the particles fails, resulting in high conductivity of the magnetic core of the inductor.

[0039] Since the inductor usually works in an alternating magnetic field, referring to Figure 4 , in the direction of the induced electric field, the metal-based magnetic powder can be regarded as an equivalent inductor 600, and the insulating coating layer between the magnetic powders can be regarded as an equivalent capacitor 700. The equivalent circuit of two particles with coating layers in the direction of the induced electric field can be regarded as a series connection of a capacitor and an inductor.

[0040] At present, the insulation coating process of soft magnetic composite materials is usually studied to improve the resistivity of the magnetic powder core. Under ideal conditions, the particles are insulated from each other, as shown in Figure 5 (a), the eddy current 800 inside the soft magnetic particles is limited inside the particles, and the eddy current 900 between the soft magnetic particles flows through the gap between the soft magnetic particles. The equivalent circuit is a series connection of the equivalent resistance of n particles in the direction of the induced electric field and the equivalent capacitance of n dielectric layers:

[0041] ;

[0042] ;

[0043] .

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

[0045] ;

[0046] .

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

[0052] .

[0053] However, during the compression molding process, due to the deformation of the soft magnetic powder or the mutual friction between the particles, the insulation coating of the magnetic powder core may be broken, and the magnetic powder particles may be in contact with each other, which on the one hand leads to a decrease in the dielectric layer in the equivalent circuit, and on the other hand leads to a decrease in the equivalent resistance between the particles, as shown in (b) of Figure 5 In an ideal case, only the dielectric layer failure caused by the dielectric layer rupture is considered, that is, the equivalent resistance of the equivalent circuit does not change, the number of equivalent inductors decreases, that is, n decreases, and the impedance of the equivalent circuit decreases, the equivalent current I increases, causing the eddy current loss power to increase. The energy of the eddy current loss is finally released in the form of heat, so that the increase of the equivalent current will generate more heat in the electric field loop, causing the temperature of the inductor 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 during the operation of the inductor.

[0054] To this end, the present application provides an integrally formed inductor magnetic core structure, referring to Figure 6 which includes an inductor coil 100, a magnetic core 200, and a dielectric layer 300. The magnetic core 200 wraps the inductor coil 100, the dielectric layer 300 is arranged in the magnetic core 200, and the central axis of the inductor coil 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 coil 100, and the resistance value of the dielectric layer 300 is higher than that of the inductor coil.

[0055] Since the dielectric layer 300 is parallel to the magnetic field direction, it has little effect on the inductance of the integrally formed inductor, as Figure 7The increased dielectric layer 300 provides several high capacitance on the passage of electric field, which can effectively reduce the eddy current intensity of the integrally formed inductor at high frequency, and reduce the eddy current loss of the integrally formed inductor, as shown in Figure 8 As shown in the figure.

[0056] At the same time, since the increased dielectric layer 300 is perpendicular to the induced electric field, it can be regarded as a series of capacitors in the electric field. In a series circuit, the total voltage is distributed to each capacitor, so the more dielectric layers 300, the lower the voltage across each dielectric layer 300. For the integrally formed inductor, since the withstand voltage of a single dielectric layer 300 is certain, increasing the dielectric layer 300 in the magnetic core 200 can improve the withstand voltage of the integrally formed inductor.

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

[0058] Further, the number of dielectric layers 300 can be multiple, further reducing the loss of the integrally formed inductor magnetic core structure at high frequency and improving the withstand voltage performance. For example, Figure 9 (a) in the figure, the magnetic core 200 is symmetrically distributed with 4 dielectric layers 300. Figure 9 (b) in the figure, the magnetic core 200 is symmetrically distributed with 8 dielectric layers 300. 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, and the included angle between every two adjacent dielectric layers 300 can be consistent, or different included angles can be designed between adjacent insulating layers at different positions.

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

[0061] Specifically, the dielectric layer 300 can be added with high resistivity material at the corresponding position through a special mold before the integrally formed inductor is pressed, and then pressed, or the dielectric layer 300 can be added with an opening at a specific position through mechanical processing after the integrally formed inductor is pressed, and then filled with corresponding insulating material.

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

[0063] Specifically, the dielectric layer includes soft magnetic material, and the soft magnetic material includes at least one of manganese-zinc ferrite, nickel-zinc ferrite, carbonyl iron powder coated with an insulating layer, FeSiCr, and amorphous FeSiB.

[0064] Further, the soft magnetic material is atomized spherical powder or broken amorphous powder of carbonyl iron powder coated with an insulating layer, FeSiCr, and amorphous FeSiB. In terms of composition, the magnetic core is pressed from magnetic particles of one composition, or is pressed after mixing magnetic particles of several different compositions.

[0065] Further, the shape of the magnetic core 200 is a cube, a cuboid, or a cylinder; the winding shape of the inductor coil 100 is a circle, an ellipse, or a polygon; and the shape of the dielectric layer 300 is a sheet or a fan-shaped column. It is easily understood that the winding shape of the inductor coil 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 described here.

[0066] Further, the inductor coil 100 is a solid or hollow wire; the inductor coil 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 combination with the drawings, but the present application is not limited to the above embodiments, and various changes can be made within the knowledge of those skilled in the art 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 by, The inductor coil, the magnetic core and the dielectric layer, the magnetic core wraps the inductor coil, the dielectric layer is arranged in the magnetic core, the inductor coil's central axis is located in the plane where the dielectric layer is located, the dielectric layer separates the inductor coil, the resistance value of the dielectric layer is higher than the resistance value of the inductor coil.

2. The integrally formed inductor core structure of claim 1, wherein: The intersection of the dielectric layer and the inductor coil, the plane where the dielectric layer is located and the electric field direction of the inductor coil form an angle of 60 to 90 degrees.

3. The integrally formed inductor core structure of claim 1, wherein: The resistance value of the dielectric layer is at least 1 Ω / m.

4. The integrally formed inductor core structure of claim 1, wherein: The dielectric layer penetrates the magnetic core.

5. The integrally formed inductor core structure of claim 4, wherein: The dielectric layer is completely located inside the magnetic core.

6. The integrally formed inductor core structure of claim 1, wherein: The dielectric layer includes soft magnetic material, the soft magnetic material includes at least one of manganese zinc ferrite, nickel zinc ferrite, carbonyl iron powder coated with an insulating layer, FeSiCr and amorphous FeSiB.

7. The integrally formed inductor core structure of claim 6, wherein: The soft magnetic material is atomized spherical powder or broken amorphous powder coated with an insulating layer.

8. The integrally formed inductor core structure of claim 1, wherein: The magnetic core is pressed from magnetic particles of one component, or is pressed after mixing magnetic particles of several different components.

9. The integrally formed inductor core structure of any of claims 1 to 8, wherein: 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 fan-shaped column.

10. The integrally formed inductor core structure of any one of claims 1 to 8, wherein: The inductor coil is a solid or hollow wire; the inductor coil is a single or multi-strand wire.

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