Coupled inductor

Abstract

A coupled inductor, characterized in that it comprises a magnetic core, a mounting seat, a first coil, a second coil, a terminal, an insulating element, and a magnetic cover, wherein the magnetic core and the terminal are each mounted on the mounting seat, and wherein the first coil and the second coil are each wound on the magnetic core and arranged sequentially along the axial direction of the magnetic core and are each connected to the terminal, and wherein the insulating element is placed on the magnetic core and is located between the first coil and the second coil; and wherein the magnetic cover covers the mounting seat and forms an interior space with the mounting seat, and wherein the magnetic core is received in the interior space, and wherein an air gap is provided between the magnetic core and the bottom of the magnetic cover, which is filled with a magnetic layer.

Description

TECHNICAL FIELD

[0001] The present invention relates to the technical field of electronic components, in particular to a coupled inductor. STATE OF THE ART

[0002] Currently, high efficiency, energy conservation, and environmental protection are the development directions of the electronics industry, and small size, low radiation, and high power density have become the mainstream designs on the market. Gallium nitride, silicon carbide, and other semiconductor technologies can significantly improve the switching frequency of power supplies and reduce losses, thereby further compressing product sizes. In existing coupled inductors, there is an air gap between the magnetic core and the bottom of the magnetic cover, and there is a phenomenon of edge flux radiation to the coil, leading to a rise in the temperature of the inductor. CONTENT OF THE PRESENT INVENTION

[0003] In view of this, the present invention provides a coupled inductor to solve the technical problem in existing coupled inductors that a phenomenon of radiation of the edge flux to the coil due to the presence of the air gap leads to the temperature rise of the inductor.

[0004] In order to solve the above technical problems, the present invention uses a following technical solution: a coupled inductor comprising a magnetic core, a mounting seat, a first coil, a second coil, a terminal, an insulating member, and a magnetic cover, wherein the magnetic core and the terminal are each mounted on the mounting seat, and wherein the first coil and the second coil are each wound on the magnetic core and arranged sequentially along the axial direction of the magnetic core, and are each connected to the terminal, and wherein the insulating member is fitted on the magnetic core and is located between the first coil and the second coil; and wherein the magnetic cover covers the mounting seat and forms an internal space with the mounting seat, and wherein the magnetic core is housed in the internal space, and wherein an air gap filled with a magnetic layer is provided between the magnetic core and the bottom of the magnetic cover. In some embodiments of the coupled inductor, the manufacturing steps of the magnetic layer are as follows: Providing an epoxy resin raw material; Providing a soft magnetic powder; performing an insulating treatment on the soft magnetic powder; Stirring and mixing the epoxy resin raw material and the soft magnetic powder in a weight ratio of 9:1 to obtain the magnetic layer in a liquid state.

[0005] In some embodiments of the coupled inductor, the epoxy resin raw material has a viscosity (25°C) of 5000 cps-7000 cps.

[0006] In some embodiments of the coupled inductor, the step of providing a soft magnetic powder comprises: Providing a raw magnetic powder, wherein the raw magnetic powder is one of ferrite material, ferrosilicon, ferrosilicon-aluminum, ferrosilicon-chromium; Providing a 200-mesh, 300-mesh, 400-mesh sieve and sieving the raw magnetic powder; Proportioning the soft magnetic powder in a ratio of 5%-15% for +200 mesh, 45%-55% for -200 mesh and +300 mesh, 20%-30% for -300 mesh and +400 mesh and 10%-20% for -400 mesh to obtain the soft magnetic powder.

[0007] In some embodiments of the coupled inductor, in the step of stirring and mixing the epoxy resin raw material and the soft magnetic powder in a weight ratio of 9:1, the stirring and mixing time is 15 min-20 min.

[0008] In some embodiments of the coupled inductor, the magnetic core comprises a table body and a post body, wherein the post body is connected to the central part of the table body, and wherein the diameter of the table body is larger than that of the post body such that the table body has a projection protruding from the post body, and wherein an orthographic projection of the magnetic layer on a surface of the projection facing the magnetic layer is at least partially located on the surface; and wherein the insulating element is a structural element made of a magnetic material.

[0009] In some embodiments of the coupled inductor, the first coil and the second coil are each flat, wherein the outer diameter of the first coil and the outer diameter of the second coil are the same as the diameter of the table body.

[0010] In some embodiments of the coupled inductor, the outer diameter of the insulating element is the same as that of the first coil.

[0011] In some embodiments of the coupled inductor, the second coil is located on a side of the first coil facing away from the mounting seat, wherein the distance between a side of the second coil facing away from the first coil and the bottom of the magnet cover is greater than or equal to three times the distance between a side of the magnet core facing away from the mounting seat and the bottom of the magnet cover.

[0012] In some embodiments of the coupled inductor, a recess is provided on the mounting seat, wherein the table body is received in the recess.

[0013] The implementation of the embodiment of the present invention has the following advantageous effects: The coupled inductor has a technical effect of reducing the radiation of the fringe flux onto the coil and further reducing the temperature rise of the inductor. In particular, the present invention solves the technical problem in existing coupled inductors that a phenomenon of radiation of the fringe flux onto the coil due to the presence of the air gap leads to the temperature rise of the inductor. Furthermore, the present invention further has the following effects: 1. It can enable the magnetic circuit to be closed to reduce the radiation of the fringe flux onto the coil, reduce the eddy current loss of the coil at the air gap, and increase the efficiency of the inductor. 2.After the magnetic circuit is closed, the inductance value is increased, and at the same time, the impedance of the coil is increased, so that for the characteristic of the same direction of the common mode noise signal, the impedance of the two coils is superimposed and the common mode noise is suppressed, thereby improving the EMC filtering effect; and for the characteristic of the opposite direction of the current with differential mode, the magnetic field between the two coils can form an additional circuit along the intermediate insulating element, and the differential mode noise is suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly explain the technical solution in the embodiments of the present invention or the prior art, the figures to be used in the explanation of the embodiment or the prior art are briefly presented below. Obviously, the figures described below show only some embodiments of the present invention. Those of ordinary skill in the art can derive other figures based on the figures without requiring creative work. Fig. 1 shows a schematic diagram of the structure of a coupled inductor in one embodiment. Fig. Figure 2 shows a schematic exploded diagram of the structure of a coupled inductor according to Fig. 1. Fig. Figure 3 shows a schematic diagram of a partial structure of a coupled inductor according to Fig. 1. Fig. 4 shows a schematic diagram of a partial structure of the assembly according to Fig. 3. Fig. 5 shows a schematic diagram of the structure of an assembly seat in an embodiment. Fig. 6 shows a schematic diagram of the structure of an insulating element in an embodiment. Fig. 7 shows a schematic diagram of a magnetic circuit in an embodiment of the present invention. Fig. Figure 8 shows a comparative test chart of the DC bias capability of the magnetic core and the magnetic layer made of different materials of the present invention. Fig. Figure 9 shows a side view of the loss comparison of the magnetic core and the magnetic layer made of different materials of the present invention. List of reference symbols 1 assembly seat 11 Recess 2 magnetic core 21 table body 22 post bodies 3 First coil 4 Second coil 5 Insulating element 6 Magnetic cover 7 Connection 8 Magnetic layer DETAILED DESCRIPTION

[0015] To facilitate understanding of the present invention, the present invention will be explained more fully below with reference to the accompanying drawings. Preferred embodiments of the present invention are illustrated in the drawings. However, the present invention may be embodied in many different forms and is not limited to the embodiments explained herein. On the contrary, these examples are provided to provide a thorough and complete understanding of the disclosed content of the present invention.

[0016] It should be noted that when an element is described as being "attached" to another element, the element may be located directly on top of the other element, or there may be another intervening element. When an element is viewed as being "connected" to another element, the element may be directly connected to the other element, or there may be another intervening element. Terms used in the description, such as "vertical," "horizontal," "left," "right," and similar expressions, are used only to clarify the purpose.

[0017] Unless otherwise specified, all technical and scientific terms used in the description have the same meanings as commonly understood by one of ordinary skill in the art to which the present invention pertains. The terms used in the description of the present invention are intended only to explain the scope of the detailed embodiments, rather than to limit the present invention. The terms "and / or" used in the description include any and all combinations of one or more associated listed elements.

[0018] As in Fig. As shown in Figures 1 to 7, in one embodiment of the coupled inductor, the coupled inductor comprises a magnetic core 2, a mounting seat 1, a first coil 3, a second coil 4, a terminal 7, an insulating member 5, and a magnetic cover 6. The magnetic core 2 and the terminal 7 are each mounted on the mounting seat 1. The first coil 3 and the second coil 4 are each wound on the magnetic core 2 and arranged sequentially along the axial direction of the magnetic core 2, and are each connected to the terminal 7. The insulating member 5 is placed on the magnetic core 2 and is located between the first coil 3 and the second coil 4. The magnetic cover 6 covers the mounting seat 1 and forms an internal space with the mounting seat 1. The magnetic core 2 is accommodated in the internal space. An air gap filled with a magnetic layer 8 is provided between the magnetic core 2 and the bottom of the magnetic cover 6.

[0019] In the present embodiment, the gap between the magnetic core 2 and the bottom of the magnetic cover 6 is filled with a magnetic layer 8, thereby solving the technical problem in existing coupled inductors that a phenomenon of radiation of the fringe flux onto the coil due to the presence of the air gap leads to the temperature rise of the inductor. Furthermore, the present invention further has the following effects: 1. it can enable the magnetic circuit to be closed to reduce the radiation of the fringe flux onto the coil, reduce the eddy current loss of the coil at the air gap, and increase the efficiency of the inductor; 2.After closing the magnetic circuit, the inductance value is increased, and at the same time, the impedance of the coil is increased, so that for the same direction of the common mode noise signal characteristic, the impedance of the two coils is superimposed and the common mode noise is suppressed, thereby improving the EMC filtering effect; and for the opposite direction of the current with differential mode, the magnetic field between the two coils can form an additional circuit along the intermediate insulating element 5, and the differential mode noise is suppressed.

[0020] In one embodiment of the coupled inductor, the manufacturing steps of the magnetic layer 8 are as follows: Providing an epoxy resin raw material; Providing a soft magnetic powder; performing an insulating treatment on the soft magnetic powder; Stirring and mixing the epoxy resin raw material and the soft magnetic powder in a weight ratio of 9:1 to obtain the magnetic layer 8 in a liquid state.

[0021] In the present embodiment, the magnetic layer 8 of the present invention is made of epoxy resin and soft magnetic powder, and by setting the weight ratio to 9:1, the magnetic layer 8 can be obtained in the liquid state, and after being filled into the air gap, it can be cured so that it is more completely filled into the air gap and comes into contact with the magnetic core 2 and the bottom of the magnetic cover 6, respectively, to achieve better reduction of the radiation of the fringe flux to the coil.

[0022] In one embodiment of the coupled inductor, the epoxy resin raw material has a viscosity (25°C) of 5000 cps-7000 cps.

[0023] In the present embodiment, by selecting the epoxy resin raw material with lower viscosity and then combining the soft magnetic powder in the weight ratio, a better mixing effect can be achieved, which contributes to the soft magnetic powder being completely and uniformly melted into the epoxy resin, so that a better magnetic effect can be achieved.

[0024] In one embodiment of the coupled inductor, the step of providing a soft magnetic powder comprises: Providing a raw magnetic powder, wherein the raw magnetic powder is one of ferrite material, ferrosilicon, ferrosilicon-aluminum, ferrosilicon-chromium; Providing a 200-mesh, 300-mesh, 400-mesh sieve and sieving the raw magnetic powder; Proportioning the soft magnetic powder in a ratio of 5%-15% for +200 mesh, 45%-55% for -200 mesh and +300 mesh, 20%-30% for -300 mesh and +400 mesh and 10%-20% for -400 mesh to obtain the soft magnetic powder.

[0025] In the present embodiment, by sifting the particle size of the raw magnetic powder, a magnetic material having high density, high effective permeability, high quality factor, and low eddy current loss can be provided in the finished magnetic layer 8.

[0026] In one embodiment of the coupled inductor, in the step of stirring and mixing the epoxy resin raw material and the soft magnetic powder in a weight ratio of 9:1, the stirring and mixing time is 15 min-20 min.

[0027] In the present embodiment, a high-speed dispersing to mixing method is used in the mixing process, and the mixing time is 15-20 minutes, which contributes to complete mixing.

[0028] In combination with the above embodiment, in one embodiment of the coupled inductor, the manufacturing steps of the magnetic layer 8 are as follows: Provide an epoxy resin raw material with a viscosity (25°C) of 5000 cps-7000 cps. Prepare a raw magnetic powder, prepare a 200-mesh, 300-mesh, and 400-mesh sieve, and sieve the raw magnetic powder; proportion the soft magnetic powder in a ratio of 5%-15% for +200 mesh, 45%-55% for -200 mesh and +300 mesh, 20%-30% for -300 mesh and +400 mesh, and 10%-20% for -400 mesh to obtain the soft magnetic powder. performing an insulating treatment on the soft magnetic powder; Stirring and mixing the epoxy resin raw material and the soft magnetic powder in a weight ratio of 9:1, using a high-speed dispersing method, the stirring and mixing time being 15 min-20 min to obtain the magnetic layer 8 in a liquid state. Embodiment 1 for the manufacturing steps of the magnetic layer 8: Providing an epoxy resin raw material with a viscosity (25°C) of 5000 cps; Preparing a raw magnetic powder, preparing a 200-mesh, 300-mesh, and 400-mesh sieve, and sieving the raw magnetic powder; proportioning the soft magnetic powder in a ratio of 5% for +200 mesh, 55% for -200 mesh and +300 mesh, 20% for -300 mesh and +400 mesh, and 20% for -400 mesh to obtain the soft magnetic powder; performing an insulating treatment on the soft magnetic powder; Stirring and mixing the epoxy resin raw material and the soft magnetic powder in a weight ratio of 9:1, using a high-speed dispersing method, the stirring and mixing time being 15 min, to obtain the magnetic layer 8 in a liquid state.

[0029] Example 2 for the manufacturing steps of the magnetic layer 8: Providing an epoxy resin raw material with a viscosity (25°C) of 6000 cps; Providing a raw magnetic powder, providing a 200-mesh, 300-mesh, and 400-mesh sieve, and sieving the raw magnetic powder; proportioning the soft magnetic powder in a ratio of 10% for +200 mesh, 50% for -200 mesh and +300 mesh, 25% for -300 mesh and +400 mesh, and 15% for -400 mesh to obtain the soft magnetic powder; performing an insulating treatment on the soft magnetic powder; Stirring and mixing the epoxy resin raw material and the soft magnetic powder in a weight ratio of 9:1, using a high-speed dispersing method, the stirring and mixing time being 15 min, to obtain the magnetic layer 8 in a liquid state.

[0030] Example 3 for the manufacturing steps of the magnetic layer 8: Providing an epoxy resin raw material with a viscosity (25°C) of 6000 cps; Providing a raw magnetic powder, providing a 200-mesh, 300-mesh, and 400-mesh sieve, and sieving the raw magnetic powder; proportioning the soft magnetic powder in a ratio of 10% for +200 mesh, 45% for -200 mesh and +300 mesh, 30% for -300 mesh and +400 mesh, and 15% for -400 mesh to obtain the soft magnetic powder; performing an insulating treatment on the soft magnetic powder; Stirring and mixing the epoxy resin raw material and the soft magnetic powder in a weight ratio of 9:1, using a high-speed dispersing method, the stirring and mixing time being 18 min, to obtain the magnetic layer 8 in a liquid state.

[0031] Example 4 for the manufacturing steps of the magnetic layer 8: Providing an epoxy resin raw material with a viscosity (25°C) of 7000 cps; Providing a raw magnetic powder, providing a 200-mesh, 300-mesh, and 400-mesh sieve, and sieving the raw magnetic powder; proportioning the soft magnetic powder in a ratio of 15% for +200 mesh, 55% for -200 mesh and +300 mesh, 20% for -300 mesh and +400 mesh, and 10% for -400 mesh to obtain the soft magnetic powder; performing an insulating treatment on the soft magnetic powder; Stirring and mixing the epoxy resin raw material and the soft magnetic powder in a weight ratio of 9:1, using a high-speed dispersing method, the stirring and mixing time being 20 min, to obtain the magnetic layer 8 in a liquid state.

[0032] Example 5 for the manufacturing steps of the magnetic layer 8: Providing an epoxy resin raw material with a viscosity (25°C) of 6000 cps; Preparing a raw magnetic powder, preparing a 200-mesh, 300-mesh, and 400-mesh sieve, and sieving the raw magnetic powder; proportioning the soft magnetic powder in a ratio of 5% for +200 mesh, 55% for -200 mesh and +300 mesh, 20% for -300 mesh and +400 mesh, and 20% for -400 mesh to obtain the soft magnetic powder; performing an insulating treatment on the soft magnetic powder; Stirring and mixing the epoxy resin raw material and the soft magnetic powder in a weight ratio of 9:1, using a high-speed dispersing method, the stirring and mixing time being 20 min, to obtain the magnetic layer 8 in a liquid state.

[0033] Example 5 for the manufacturing steps of the magnetic layer 8: Providing an epoxy resin raw material with a viscosity (25°C) of 6000 cps; Providing a raw magnetic powder, providing a 200-mesh, 300-mesh, and 400-mesh sieve, and sieving the raw magnetic powder; Proportioning the soft magnetic powder in a ratio of 10% for +200 mesh, 50% for -200 mesh and +300 mesh, 30% for -300 mesh and +400 mesh, and 10% for -400 mesh to obtain the soft magnetic powder; performing an insulating treatment on the soft magnetic powder; Stirring and mixing the epoxy resin raw material and the soft magnetic powder in a weight ratio of 9:1, using a high-speed dispersing method, the stirring and mixing time being 16 min, to obtain the magnetic layer 8 in a liquid state.

[0034] In one embodiment of the coupled inductor, the magnetic core 2 comprises a table body 21 and a post body 22, wherein the post body 22 is connected to the central part of the table body 21, and wherein the diameter of the table body 21 is larger than that of the post body 22, so that the table body 21 has a projection protruding from the post body 22, and wherein an orthographic projection of the magnetic layer 8 is located at least partially on a surface of the projection facing the magnetic layer 8. The insulating element 5 is a structural element made of a magnetic material.

[0035] In the present embodiment, both the table body 21 and the column body 22 have a circular cross section, and by making the diameter of the table body 21 larger than that of the post body 22 and arranging the post body 22 in the center of the table body 21, the entire axial cross section of the magnetic core 2 can be T-shaped, resulting in an increase in the inductance value.In addition, it can be understood that the second coil 4 is closer to the air gap than the first coil 3, and there is a small amount of magnetic leakage, so the inductance value is relatively small, and a magnetic circuit is formed between the table body 21 and the insulating member 5 and between the insulating member 5 and the magnetic layer 8, so that when used as a common mode inductor, it can respectively form a magnetic circuit with the first coil 3 and the second coil 4 to form a separate small inductance, and the influence of magnetic leakage makes it possible that a small inductance value still remains after the two inductors are balanced, and this small inductance value can play a role in suppressing the signal noise of differential mode.

[0036] The arrangement of the insulating element 5 with magnetism has the following effects: 1. the two coils form a corresponding circuit between them, which can be used as two power inductors; 2. between the first coil 3 and the second coil 4; 3. the magnetic field is collected, the induction value is increased, and the coupling coefficient is increased.

[0037] In particular, the insulating element 5 may be made of Ni-Zn ferrite or Mn-Zn ferrite or of metal alloy powder, magnetic powder core, such as iron-silicon-aluminum, iron-silicon, iron-nickel or other materials.

[0038] In one embodiment of the coupled inductor, the first coil 3 and the second coil 4 are each flat, wherein the outer diameter of the first coil 3 and the outer diameter of the second coil 4 are the same as the diameter of the table body 21.

[0039] In the present embodiment, the existing round enameled wire of the magnetic core 2 is replaced by the flat-shaped first coil 3 and the second coil 4 covered with the magnetic core 2, so that the same number of turns of the flat-shaped first coil 3 and the second coil 4 increases the cross-sectional area of ​​the wire compared to the round enameled wire, reduces the DCR value of the first coil 3 and the second coil 4, and achieves a larger overcurrent capability, thereby increasing the output efficiency.

[0040] In one embodiment of the coupled inductor, the outer diameter of the insulating element 5 is the same as that of the first coil 3.

[0041] In the present embodiment, the size of the insulating member 5 corresponds to the size of the first coil 3 and the second coil 4, which can achieve better insulation of the first coil 3 and the second coil 4.

[0042] In one embodiment of the coupled inductor, the second coil 4 is located on a side of the first coil 3 facing away from the mounting seat 1, wherein the distance between a side of the second coil 4 facing away from the first coil 3 and the bottom of the magnet cover 6 is greater than or equal to three times the distance between a side of the magnet core 2 facing away from the mounting seat 1 and the bottom of the magnet cover 6.

[0043] In the present embodiment, it can be avoided that radiation of the air gap onto the coil causes additional eddy current losses, thus reducing the heat generation of the inductor.

[0044] In one embodiment of the coupled inductor, a recess 11 is provided on the mounting seat 1, wherein the table body 21 is received in the recess 11.

[0045] With the arrangement of the recess 11, a positioning effect can be achieved, which makes it possible to accommodate the table body 21 in the recess 11 and to facilitate the installation of the magnetic core 2.

[0046] In addition, the terminal 7 is provided on the mounting seat 1, and both the first coil 3 and the second coil 4 are connected to the terminal 7 on the mounting seat 1 by means of pins. By fitting the magnetic cover 6 to the mounting seat 1, the structural layout is compact and can also provide a shielding effect. There is no need for additional sealing treatment on the top of the inductor, and the production line becomes relatively shorter, which improves production efficiency. The shielding structure reduces the leakage of the magnetic field and achieves good resistance to electromagnetic interference. In addition, the insulation combination of double flat single-layer coils can achieve the effect of improving the withstand voltage.

[0047] In addition, the magnetic core 2 and the magnetic layer 8 of the present invention can also be made of different materials, and the magnetic core 2 and the magnetic layer 8 are made of the same material, and different materials also have different effects.

[0048] The magnetic core 2 and the magnetic layer 8 made of iron-silicon material can store more energy and achieve better DC bias capability, which is suitable for the design of high-performance energy storage application, and solves the current problem of the existing ferrite high-current coupling inductor with a small saturation current.

[0049] The magnetic core 2 and magnetic layer 8 made of FeNi exhibit the strongest DC bias capability, while the inductor exhibits lower loss, making it suitable for high-voltage and high-power designs with high current and high voltage ripple. This solves the problem of temperature rise caused by heat generation in the inductor in high-frequency and high-voltage applications.

[0050] The magnetic core 2 and the ferrosilicon-aluminum magnetic layer 8 have lower core losses and a lower magnetostriction coefficient, which reduces the risk of noise generation. This solves the problem of high-frequency noise on the circuit board.

[0051] The magnetic core 2 and the magnetic layer 8 made of ferrosilicon-chromium have a medium loss and a medium DC bias, which is suitable for low and medium power applications.

[0052] The magnetic core 2 and the magnetic layer 8 made of ferrite material exhibit smoother current linearity, making them suitable for a wide range of low-pass filter circuit designs. Furthermore, the ui value of the ferrite core is higher than that of the powder magnetic core, allowing for the development of larger inductance values. Example: Loss condition of different materials (ferrite for the magnetic cover, properties after combining different materials).

[0053] For the comparative testing of the DC bias capability of the magnetic core 2 and the magnetic layer 8 of each material type with the magnetic cover 6 as ferrite, reference is made to Fig. 8. Comparative testing of the loss of the magnetic core 2 of each material type with the magnetic cover 6 as ferrite.

[0054] The respective technical features of the above embodiments can be combined arbitrarily. To simplify the explanation, not all possible combinations of the respective technical features in the above embodiments are explained. However, the combinations of the technical features shall be considered to be within the scope of the description in the case of no conflicts.

[0055] The above embodiments represent only some embodiments of the present invention. The explanations are relatively specific and detailed, but should not be construed as limitations on the scope of the present application. It should be noted that those skilled in the art can make various improvements and modifications without departing from the concept of the present invention. These improvements and modifications should also be considered to be within the scope of the present invention. Therefore, the scope of the present invention should be defined by the claims.

Claims

[1] Coupled inductor, characterized by that it comprises a magnetic core, a mounting seat, a first coil, a second coil, a terminal, an insulating member, and a magnetic cover, wherein the magnetic core and the terminal are each mounted on the mounting seat, and wherein the first coil and the second coil are each wound on the magnetic core and arranged one after the other along the axial direction of the magnetic core and are each connected to the terminal, and wherein the insulating member is placed on the magnetic core and is located between the first coil and the second coil; and wherein the magnetic cover covers the mounting seat and forms an internal space with the mounting seat, and wherein the magnetic core is accommodated in the internal space, and wherein an air gap filled with a magnetic layer is provided between the magnetic core and the bottom of the magnetic cover. [2] Coupled inductor according to claim 1, characterized bythat the manufacturing steps of the magnetic layer are as follows: Providing an epoxy resin raw material; Providing a soft magnetic powder; performing an insulating treatment on the soft magnetic powder; Stirring and mixing the epoxy resin raw material and the soft magnetic powder in a weight ratio of 9:1 to obtain the magnetic layer in a liquid state. [3] Coupled inductor according to claim 2, characterized by that the epoxy resin raw material has a viscosity (25°C) of 5000 cps-7000 cps. [4] Coupled inductor according to claim 2, characterized by that the step of providing a soft magnetic powder comprises: Providing a raw magnetic powder, wherein the raw magnetic powder is one of ferrite material, ferrosilicon, ferrosilicon-aluminum, ferrosilicon-chromium; Providing a 200-mesh, 300-mesh, 400-mesh sieve and sieving the raw magnetic powder; Proportioning the soft magnetic powder in a ratio of 5%-15% for +200 mesh, 45%-55% for -200 mesh and +300 mesh, 20%-30% for -300 mesh and +400 mesh and 10%-20% for -400 mesh to obtain the soft magnetic powder. [5] Coupled inductor according to claim 2, characterized by that in the step of stirring and mixing the epoxy resin raw material and the soft magnetic powder in a weight ratio of 9:1, the stirring and mixing time is 15 min-20 min. [6] Coupled inductor according to claim 1, characterized byin that the magnetic core comprises a table body and a post body, wherein the post body is connected to the central part of the table body, and wherein the diameter of the table body is larger than that of the post body, so that the table body has a projection protruding from the post body, and wherein an orthographic projection of the magnetic layer on a surface of the projection facing the magnetic layer is at least partially located on the surface; and wherein the insulating element is a structural element made of a magnetic material. [7] Coupled inductor according to claim 1, characterized by that the first coil and the second coil are each flat, wherein the outer diameter of the first coil and the outer diameter of the second coil are the same as the diameter of the table body. [8] Coupled inductor according to claim 7, characterized bythat the outer diameter of the insulating element is the same as that of the first coil. [9] Coupled inductor according to claim 1, characterized by that the second coil is located on a side of the first coil facing away from the mounting seat, wherein the distance between a side of the second coil facing away from the first coil and the bottom of the magnet cover is greater than or equal to three times the distance between a side of the magnet core facing away from the mounting seat and the bottom of the magnet cover. [10] Coupled inductor according to claim 6, characterized by that a recess is provided on the mounting seat, wherein the table body is received in the recess.

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