Magnetic core structure, transformer, and micro inverter

Abstract

The present application provides a magnetic core structure, a transformer, and a micro inverter. The magnetic core structure comprises two magnetic cores. Each magnetic core comprises: a middle column, comprising a middle column outer wall; a first side column, surrounding the middle column and comprising a first side column inner wall, a first side column outer wall, and N openings, N being a positive number greater than or equal to 1; a first space, formed by the first side column inner wall and the middle column outer wall; second side columns, surrounding the first side column and comprising second side column inner walls and K notches, K being an integer greater or equal to 1; a second space, formed by the first side column outer wall and the second side column inner walls; and a magnetic yoke, provided at the bottom of the first space and the bottom of the second space and connected to the first side column, the second side columns, and the middle column. The middle column, the first side column, the second side columns and the openings of one magnetic core are arranged opposite to those of the other magnetic core, respectively. The present application solves the problem in the prior art that existing magnetic core structures cannot consider both heat dissipation and EMC interference, and can improve the heat dissipation capability and reduce EMC interference.

Description

Magnetic core structure, transformer and micro inverter

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on March 26, 2024, with application number 202420607660.5 and application name “Magnetic core structure, transformer and micro inverter”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application belongs to the technical field of transformers, and in particular relates to a magnetic core structure, a transformer, and a micro inverter. Background Art

[0003] Traditional core structures, such as EE, ER, EQ, PQ, and P-type, can all be used in integrated transformer designs, but each has its own drawbacks. EE cores offer excellent heat dissipation, but suffer from significant magnetic flux leakage and high actual leakage inductance losses. ER, EQ, and PQ core structures are relatively well-balanced, but electromagnetic compatibility (EMC) interference still exists. P-type cores offer excellent shielding but poor heat dissipation.

[0004] Therefore, there is an urgent need to provide a magnetic core structure that takes into account both heat dissipation and reduction of EMC interference. Summary of the Invention

[0005] The embodiments of the present application provide a magnetic core structure, a transformer, and a micro-inverter to solve the problem that the existing magnetic core structure cannot take into account both heat dissipation and EMC interference, thereby improving heat dissipation capacity and reducing EMC interference.

[0006] In a first aspect, the present application provides a magnetic core structure, comprising two magnetic cores, each magnetic core comprising: a middle column, which includes a middle column outer wall; a first side column, surrounding the middle column, which includes a first side column inner wall, a first side column outer wall and N openings, where N is a positive number greater than or equal to 1; a first space, formed by the first side column inner wall and the middle column outer wall; a second side column, surrounding the first side column, which includes the second side column inner wall and K gaps, where K is an integer greater than or equal to 1; a second space, formed by the first side column outer wall and the second side column inner wall; a magnetic yoke, arranged at the bottom of the first space and the second space and connecting the first side column, the second side column and the middle column; the middle column, the first side column, the second side column and the openings of the two magnetic cores are arranged relatively to each other.

[0007] In a possible implementation, the height of the first side column is lower than that of the middle column.

[0008] In a possible implementation, a first air gap exists between the middle legs of the two magnetic cores; a second air gap exists between the first side legs of the two magnetic cores, and the second air gap is larger than the first air gap.

[0009] In a possible implementation, the gaps of the two magnetic cores are arranged opposite to each other.

[0010] In a possible implementation, a heat dissipation material is further included, and the heat dissipation material is filled in the gap.

[0011] In a possible implementation, the magnetic yoke includes a slot, and the slot is used to connect the opening and the gap.

[0012] In one possible implementation, K is an integer greater than or equal to 2, and K gaps are evenly arranged on the second side column.

[0013] In a second aspect, the present application provides a transformer comprising a first winding, a second winding and a magnetic core structure as described above; the first winding is arranged on a middle column and led out through an opening; the second winding is arranged on a first side column.

[0014] In a possible implementation, a heat dissipation material is further included; the heat dissipation material is filled in the gap, and the first winding and the second winding are in contact with the heat dissipation material.

[0015] In a third aspect, the present application provides a micro inverter, comprising a housing and a circuit mainboard disposed in the housing, wherein at least one transformer as described in any one of the above items is mounted on the circuit mainboard.

[0016] The magnetic core structure provided by the embodiments of the present application includes but is not limited to the following technical effects:

[0017] The magnetic core structure forms a first space and a second space through the center column, the first side column, and the second side column. The first space can accommodate the first winding, and the second space can accommodate the second winding. K gaps are provided in the second side column so that heat dissipation material can be subsequently filled into the gaps. This allows the heat dissipation material to completely penetrate the magnetic core and the winding interior, achieving heat dissipation. Furthermore, by having the first side column surround the center column, the second side column surround the first side column, and the second winding surround the first side column, the magnetic core structure has better electromagnetic compatibility, generates less electromagnetic interference to the outside world, and improves anti-interference capabilities. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] FIG1 is a schematic diagram of a magnetic core structure provided in an embodiment of the present application.

[0019] FIG2 is a schematic diagram of an exploded view of a transformer provided in an embodiment of the present application.

[0020] FIG3 is a schematic diagram of a transformer structure provided in an embodiment of the present application.

[0021] Description of main component symbols DETAILED DESCRIPTION

[0022] It should be noted that the terms "first" and "second" in the specification, claims, and drawings of this application are used to distinguish similar objects, not to describe a specific order or precedence. Unless otherwise specified, in the specification, claims, and drawings of this application, " / " represents or. For example, A / B can represent A or B. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone.

[0023] It is understood that the connection relationships described in this application refer to direct or indirect connections. For example, A and B are connected or A is electrically connected to B. This can mean that A and B are directly connected, or that A and B are indirectly connected through one or more other electrical components. For example, A and C can be directly connected, and C can be directly connected to B, so that A and B are connected through C.

[0024] The following will describe some embodiments with reference to the accompanying drawings. In the absence of conflict, the following embodiments and features therein may be combined with each other.

[0025] As the power of photovoltaic panels continues to increase, the power of microinverters is also growing. To maintain a compact form factor, the power density is often increased, which in turn poses greater challenges to the inverter's heat dissipation and electromagnetic compatibility (EMC). Generally speaking, microinverters all use isolated solutions and can be roughly divided into three categories: single-stage, DC-DC-AC, and DC-AC-AC. Common topologies include flyback, forward, push-pull, resonant, and single-phase dual active bridge (DAB). Among these, the LLC resonant converter leverages its soft switching advantages, achieving high overall efficiency, especially near the resonance point. The resonant inductor, resonant capacitor, and transformer (magnetizing inductor) constitute key parameters of the resonant cavity. The resonant inductor is often integrated (partially or fully) using the transformer's leakage inductance to increase power density, but this also further exacerbates transformer heat dissipation. Furthermore, the compact layout of the microinverter means that the transformer has a significant impact on EMC. Traditional core structures, such as EE, ER, EQ, PQ, and P, can all be used in integrated transformer designs, but each has its own drawbacks. EE cores offer excellent heat dissipation, but suffer from significant magnetic flux leakage, resulting in significant leakage inductance losses. ER, EQ, and PQ core structures are relatively balanced, but magnetic flux leakage still generates eddy current losses and EMC interference in the housing. P-type cores offer excellent shielding but poor heat dissipation.

[0026] In view of this, the embodiments of the present application provide a magnetic core structure, a transformer, and a micro inverter, which solve the problem that the existing magnetic core structure cannot take into account both heat dissipation and EMC interference, and can improve heat dissipation capacity and reduce EMC interference.

[0027] Please refer to FIG1 for an exemplary description of a magnetic core 100 provided in an embodiment of the present application. As shown in FIG1 , the magnetic core 100 includes a center column 10, a first side column 20, a first space 30, a second side column 40, a second space 50, and a yoke 60. The center column 10 includes a center column outer wall 11. The first side column 20 surrounds the center column 10 and includes a first side column inner wall 21, a first side column outer wall 22, and N openings 23, where N is a positive number greater than or equal to 1. The first side column inner wall 21 and the center column outer wall 11 form a first space 30. The second side column 40 surrounds the first side column 20 and includes a second side column inner wall 42. The first side column outer wall 22 and the second side column inner wall 42 form a second space 50. The yoke 60 is disposed at the bottom of the first space 30 and the second space 50 and connects the first side column 20, the second side column 40, and the center column 10.

[0028] In the embodiment of the present application, a first space 30 and a second space 50 are formed by the middle column 10, the first side column 20 and the second side column 40, so that the first winding 200 (as shown in FIG2 ) can be accommodated in the first space 30, and the second winding 300 (as shown in FIG2 ) can be accommodated in the second space 50. K gaps are set on the second side column so that the heat dissipation material can be filled into the gaps later, so that the heat dissipation material can completely penetrate into the magnetic core and the winding to achieve heat dissipation. Furthermore, by the first side column 20 surrounding the middle column 10, the second side column 40 surrounding the first side column 20, and the second winding 200 surrounding the first side column 20, the electromagnetic compatibility of the magnetic core 100 is better, the electromagnetic interference generated to the outside world is small, and the anti-interference ability is improved.

[0029] The following describes in detail the arrangement of the various components on the magnetic core 100 .

[0030] In the embodiment of the present application, the center post 10 is used to wind the first winding 200. The center post 10 includes a center post outer wall 11. Specifically, the first winding 200 can be wound on the center post outer wall 11. If the center post 10 is a single unit, the center post outer wall 11 is the outer surface of the unit. The lower surface of the center post 10 is connected to the magnetic yoke 60. The upper surface of the center post 10 is disposed opposite the upper surface of the center post 10 of another magnetic core 100 (as shown in FIG. 2 ).

[0031] In some embodiments, the center column 10 may include multiple sub-columns (not shown), located in the center of the magnetic core 100 and spaced apart from one another. These sub-columns can be considered a single entity, and the first winding 200 can be disposed outside this entity. Specifically, the side of the sub-columns facing the first side column 20 forms the outer wall of the center column. In other words, the side of the sub-columns facing the first side column 20 constitutes the exterior of the entity, and the first winding 200 passes through the side of the sub-columns facing the first side column 20.

[0032] Among them, the middle column 10 and the sub-columns can include but are not limited to the following shapes: cylinder, elliptical column, cube, rectangular parallelepiped, etc., and this application does not make specific limitations on this.

[0033] In the embodiment of the present application, the center column 10 or the sub-columns can be integrally die-cast with the yoke 60 , or the center column 10 or the sub-columns can be separate bodies.

[0034] In the embodiment of the present application, the first side limb 20 is used to wind the second winding 300. The first side limb 20 is configured to ensure that the second winding 300 surrounds the outer periphery of the first winding 200 (e.g., the second winding 300 surrounds the first winding 200) and can lead the coil of the first winding 200 out.

[0035] Specifically, the first side column 20 surrounds the center column 10 , and the first side column 20 includes a first side column inner wall 21 , a first side column outer wall 22 , and N openings 23 , where N is a positive number greater than or equal to 1.

[0036] The first side column 20 surrounding the middle column 10 may include but is not limited to the following situations:

[0037] Situation 1: The first side column 20 is a whole, and the first side column 20 is sleeved on the outer side of the middle column outer wall 11 .

[0038] For example, as shown in FIG. 1 , the first side column 20 is annular with an opening 23 , and the annular opening 23 is sleeved on the outer side of the center column outer wall 11 .

[0039] In the second scenario, when the first side column 20 includes two or more sub-side columns, the two or more sub-side columns are evenly arranged on the outer side of the center column outer wall 11 .

[0040] For example, taking the sub-side column as an arc column, the first side column 20 includes two arc columns (not shown), which are evenly arranged on the outside of the outer wall 11 of the middle column, and the two arc columns are arranged opposite to each other, that is, the middle column 10 is located in the space surrounded by the two arc columns.

[0041] It can be understood that the first side column 20 can include more sub-side columns, such as 5, 6, 7, etc. sub-side columns, and the multiple sub-side columns are evenly arranged on the outside of the middle column outer wall 11 to surround the middle column 10.

[0042] In an embodiment of the present application, when the first side column 20 includes two or more sub-side columns, the air gap of the first side column 20 (i.e., the second air gap) can be segmented into multiple small air gaps, thereby reducing the high-frequency loss of the first winding 200 and the second winding 300 caused by the edge magnetic flux.

[0043] The first side column 20 and the sub-side column may include, but are not limited to, the following shapes: a cylinder, an elliptical cylinder, an arc column, a cube, a cuboid, etc., which are not specifically limited in this application.

[0044] In the embodiment of the present application, when the first side pillar 20 is a single unit, one opening 23 is provided thereon. When the first side pillar 20 includes two or more sub-side pillars, two or more openings 23 may be provided thereon. For example, if the first side pillar 20 includes two sub-side pillars, and the two sub-side pillars are spaced apart from each other, the first side pillar 20 may include two openings 23.

[0045] In the embodiment of the present application, at least one opening 23 in the first side column 20 is used to allow the coil of the first winding 200 to extend / lead out.

[0046] The shape of the opening 23 includes, but is not limited to, a rectangle, a square, and a fan-shaped shape, which is not specifically limited in this application.

[0047] In the embodiment of the present application, the first side column inner wall 21 is the side of the first side column 20 close to the center column 10 , and the first side column outer wall 22 is the side of the first side column 20 away from the center column 10 .

[0048] In the embodiment of the present application, the first space 30 is formed by the first side column inner wall 21 and the middle column outer wall 11 , that is, the first space 30 is formed between the first side column inner wall 21 and the middle column outer wall 11 .

[0049] In the embodiment of the present application, the first side legs 20 are lower than the center leg 10. Since the first side legs 20 are lower than the center leg 10, when two magnetic cores 100 are combined, a first air gap exists between the center legs 10 of the two magnetic cores 100, and a second air gap exists between the first side legs 20 of the two magnetic cores 100, and the second air gap is larger than the first air gap.

[0050] The first air gap and the second air gap may be air or other filling solid materials with a magnetic permeability similar to that of air, and are used to adjust the equivalent magnetic permeability of the leakage magnetic circuit to adjust the leakage inductance.

[0051] In the embodiment of the present application, the first side column 20 or the sub-side column can be die-casted integrally with the yoke 60, or the first side column 20 or the sub-side column can be a separate body.

[0052] In the embodiment of the present application, the second side pillar 40 surrounds the first side pillar 20. The second side pillar 40 is provided with K notches 41 and has a second side pillar inner wall 42. K is an integer greater than or equal to 1. K and N may be the same or different. In some embodiments, K is greater than N.

[0053] In the embodiment of the present application, the K notches 41 are evenly arranged on the second side column 40. The heat dissipation material (not shown) is completely infiltrated into the magnetic core 100 and the windings (such as the first winding 200 and the second winding 300) by using the notches 41.

[0054] The second side column inner wall 42 is a side of the side wall of the second side column 40 close to the first side column 20 .

[0055] The second side column 40 may include, but is not limited to, the following shapes: a cylinder, an elliptical cylinder, a cube, a cuboid, and the like.

[0056] The shape of the notch 41 includes, but is not limited to, a rectangle, a square, and a fan-shaped shape, which is not specifically limited in this application.

[0057] In the embodiment of the present application, the second space 50 is formed by the first side column outer wall 22 and the second side column inner wall 42 , that is, the second space 50 is formed between the first side column outer wall 22 and the second side column inner wall 42 .

[0058] In the embodiment of the present application, the yoke 60 includes a slot 61 , which is used to connect the opening 23 and the notch 41 .

[0059] As shown in FIG. 1 , the slot 61 connects the opening 23 and the notch 41 , so that the first winding 200 and the second winding 300 can be led out therefrom.

[0060] It is understandable that the second winding 300 can also be led out through the notch 41 on the second side column 40 .

[0061] In other embodiments, the yoke 60 includes multiple slots 61. In addition to the above-mentioned slots 61 for connecting the opening 23 and the notch 41, the remaining slots 61 are only used to connect with the opening 23. The slots 61 for connecting with the opening 23 can be arranged around, in the middle or at other positions of the yoke 60, and this application does not make specific limitations on this.

[0062] As shown in FIG. 1 , four slots 61 for communicating with the openings 23 may be provided around the yoke 60 , and the second side column 40 may also be provided with four openings 23 on the four sides connected to the yoke 60 , and the four slots 61 are communicated with the four openings 23 .

[0063] In the embodiment of the present application, the shape of the yoke 60 includes but is not limited to: square or rectangular, and the present application does not make any specific limitation on this.

[0064] Please refer to FIG. 2 and FIG. 3 for an exemplary introduction to the transformer 1000 provided in an embodiment of the present application.

[0065] The transformer 1000 provided in the embodiment of the present application includes the magnetic core structure 1 provided in the embodiment of the present application, a first winding 200 and a second winding 300 .

[0066] The magnetic core structure 1 provided in the embodiment of the present application includes two magnetic cores 100. The two magnetic cores 100 included in the magnetic core structure 1 have similar structures, and the center column 10, first side column 20, second side column 40, opening 23 and notch 41 of the two magnetic cores 100 are arranged opposite to each other.

[0067] In the embodiment of the present application, the magnetic core structure 1 may further include a heat dissipation material (not shown), and the heat dissipation material is filled in the gap 41 .

[0068] The heat dissipation material may include a high thermal conductivity insulating silicone material or other filling material with good thermal conductivity, such as thermal conductive adhesive, which is not specifically limited in this application.

[0069] The first winding 200 is disposed on the center column 10 and accommodated in the first space 30 . The first winding 200 is led out through the opening 23 .

[0070] The second winding 300 is disposed on the first side column 20 and accommodated in the second space 50 .

[0071] The first winding 200 and the second winding 300 include, but are not limited to, film-wrapped Litz wire, silk-wrapped Litz wire, or three-layer insulated Litz wire, which is not specifically limited in this application.

[0072] In some embodiments, a smaller copper wire winding can be selected, and some EMC measures (such as differential mode inductance, X and Y capacitors) and investment time can be omitted.

[0073] In the embodiment of the present application, a heat dissipation material is filled in the gap 41, and the first winding 200 and the second winding 300 are in contact with the heat dissipation material. The first winding 200 and the second winding 300 are in contact with the heat dissipation material, which has a high heat conduction rate. The first winding 200 and the second winding 300 can achieve contact heat conduction by contacting the heat dissipation material, thereby improving heat dissipation efficiency.

[0074] In the embodiment of the present application, based on the fact that the height of the first side column 20 is lower than that of the middle column 10 and the second air gap is larger than the first air gap, the leakage inductance of the transformer 1000 can be controlled by adjusting the size of the air gap of the first side column 20, thereby realizing the integration of the resonant inductance (partial or full) by utilizing the leakage inductance of the transformer 1000, reducing the product size, improving the product power density, and reducing the cost.

[0075] Furthermore, by providing corresponding slots 61 and notches 41 on the second side column 40 and the yoke 60, heat dissipation materials such as thermally conductive adhesive can be completely infiltrated into the magnetic core 100 and the winding by utilizing the notches 41 and / or slots 61, thereby achieving heat dissipation and fixation of the transformer 1000 through encapsulation measures, effectively reducing the temperature rise rate of the transformer 1000, improving the environmental tolerance of the transformer 1000, and extending the life of the transformer 1000.

[0076] Furthermore, by the first side column 20 surrounding the middle column 10, the second side column 40 surrounding the first side column 20, and the second winding 200 surrounding the first side column 20, the electromagnetic compatibility of the magnetic core 100 is better, the electromagnetic interference generated to the outside world is small, and the anti-interference ability is improved.

[0077] Furthermore, when the first side column 20 includes two or more sub-side columns, the air gap of the first side column 20 (i.e., the second air gap) can be segmented into multiple small air gaps, thereby reducing the high-frequency loss of the first winding 200 and the second winding 300 caused by the edge magnetic flux.

[0078] The embodiment of the present application provides a micro inverter, comprising a housing and a circuit board disposed in the housing, wherein the circuit board is mounted with the above-mentioned transformer 1000. The micro inverter can be applied to a resonant topology.

[0079] Among them, the micro inverter can be a one-to-one, one-to-two, one-to-four, one-to-six, one-to-eight and other micro inverters, which are respectively suitable for photovoltaic systems with one photovoltaic panel output, two photovoltaic panels output, four photovoltaic panels output, six photovoltaic panels output and eight photovoltaic panels output.

[0080] An embodiment of the present application provides a photovoltaic system, comprising a photovoltaic power generation unit and the above-mentioned micro-inverter, wherein the output of the photovoltaic power generation unit is electrically connected to the micro-inverter, wherein the specific structure of the micro-inverter refers to the above-mentioned embodiment. Since the present photovoltaic system adopts all the technical solutions of all the above-mentioned embodiments of the micro-inverter, it has at least all the beneficial effects brought about by the technical solutions of the above-mentioned embodiments, which will not be repeated here one by one.

[0081] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application and are not intended to limit them. In actual application, the entire content of the technical solutions described in any embodiment of the present application can be implemented, or some content can be added, or some content can be deleted, or some content can be changed / replaced. Although the present application is described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present application can be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present application.

Claims

1. A magnetic core structure, characterized in that: Comprising two magnetic cores, each of the magnetic cores comprises: a central column, comprising an outer wall of the central column; a first side column surrounding the middle column, comprising a first side column inner wall, a first side column outer wall, and N openings, where N is an integer greater than or equal to 1; A first space is formed by the inner wall of the first side column and the outer wall of the middle column; a second side column surrounding the first side column, comprising an inner wall of the second side column and K notches, where K is an integer greater than or equal to 1; A second space is formed by the outer wall of the first side column and the inner wall of the second side column; a magnetic yoke, provided at the bottom of the first space and the second space and connecting the first side column, the second side column and the middle column; The middle column, the first side column, the second side column and the opening of the two magnetic cores are arranged opposite to each other.

2. The magnetic core structure according to claim 1, wherein: The first side column is lower in height than the middle column.

3. The magnetic core structure according to claim 2, wherein: There is a first air gap between the middle columns of the two magnetic cores; there is a second air gap between the first side columns of the two magnetic cores, and the second air gap is larger than the first air gap. The magnetic core structure according to claim 1 , further comprising a heat dissipation material, wherein the heat dissipation material is filled in the gap.

5. The magnetic core structure according to claim 4, wherein: K is an integer greater than or equal to 2, and the K notches are evenly arranged on the second side column.

6. The magnetic core structure according to claim 1, wherein: The notches and the openings of the two magnetic cores are arranged opposite to each other.

7. The magnetic core structure according to any one of claims 1 to 6, wherein: The magnetic yoke includes a slot, and the slot is used to connect the opening and the gap.

8. A transformer, characterized in that: comprising a first winding, a second winding and a magnetic core structure according to any one of claims 1 to 7; The first winding is arranged on the center column and led out through the opening; The second winding is arranged on the first side column.

9. The transformer according to claim 8, characterized in that Also includes heat dissipation materials; The heat dissipation material is filled in the gap, and the first winding and the second winding are in contact with the heat dissipation material.

10. A micro inverter, characterized in that: The utility model comprises a housing and a circuit main board arranged in the housing, wherein at least one transformer according to any one of claims 8 to 9 is mounted on the circuit main board.

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