Core, transformer, and circuit board structure

Abstract

The present disclosure relates to a core, a transformer, and a circuit board structure. The core includes: a base, a first surface of the base having a first protruding member; a second protruding member disposed within the first protruding member, wherein a first accommodation space is formed between the second protruding member and the first protruding member, and the first accommodation space is configured to accommodate a first winding; and a third protruding member disposed within the second protruding member, wherein a second accommodation space is formed between the third protruding member and the second protruding member, and the second accommodation space is configured to accommodate a second winding. The core defines a first opening at a position outside the second protruding member, such that a lead-out portion of the first winding is configured to extend out of the first opening. The core defines a second opening at a side of the core away from the first opening, such that a lead-out portion of the second winding is configured to extend out of the second opening. The second opening is located at the side away from the first opening, and the leading-out portions of the first winding and the second winding are led out from the two sides away from each other, so that the wiring is shortened when the first winding and the second winding are connected to an external circuit.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present disclosure claims priority to Chinese patent application No. 2024102882486, filed on March 13, 2024, and entitled "CORE, TRANSFORMER, AND CIRCUIT BOARD STRUCTURE," the entire content of which is incorporated herein by reference.TECHNICAL FIELD

[0002] The present disclosure relates to the technical field of power electronics, and in particular to a core, a transformer, and a circuit board structure.BACKGROUND

[0003] A transformer is an electrical device for changing an alternating current voltage, which achieves voltage transformation between input and output based on the principle of electromagnetic induction. The transformer typically includes two or more windings. According to a turns ratio of the transformer (i.e., a ratio of a number of turns of a primary winding to a number of turns of a secondary winding), an input voltage can be stepped up or down to a required output voltage level.

[0004] In the related art, to connect the windings of the transformer to an external circuit, a primary winding and a secondary winding are led out from an opening(s) on the same side, and the opening arrangement is unreasonable.SUMMARY

[0005] Accordingly, it is necessary to provide a core, a transformer, and a circuit board structure for addressing the problem of unreasonable opening arrangement when the conventional transformer is connected to the external circuit.

[0006] In a first aspect, the present disclosure provides a core, including: a base, a first surface of the base having a first protruding member; a second protruding member disposed within the first protruding member, where a first accommodation space is formed between the second protruding member and the first protruding member, and the first accommodation space is configured to accommodate a first winding; and a third protruding member disposed within the second protruding member, where a second accommodation space is formed between the third protruding member and the second protruding member, and the second accommodation space is configured to accommodate a second winding; where the core defines a first opening at a position outside the second protruding member, such that a lead-out portion of the first winding is configured to extend out of the first opening; and the core defines a second opening at a side of the core away from the first opening, such that a lead-out portion of the second winding is configured to extend out of the second opening.

[0007] In an embodiment, the first opening is defined in the first protruding member or is defined between the first protruding member and the second protruding member.

[0008] In an embodiment, the second opening is defined at a position outside the third protruding member.

[0009] In an embodiment, the second winding is formed by a plurality of wires wound in parallel, the second opening includes a first sub-opening and a second sub-opening, the first sub-opening is configured to receive first ends of the plurality of wires therethrough, and the second sub-opening is configured to receive second ends of the plurality of wires therethrough.

[0010] In an embodiment, a shape of the first sub-opening and / or the second sub-opening corresponds to a shape of the plurality of wires and the number of the plurality of wires.

[0011] In an embodiment, all of the base, the second protruding member, and the first protruding member are provided with openings, and the openings are communicated with each other to form the second opening.

[0012] In an embodiment, a width of the second opening increases progressively or in a stepwise manner in a radially outward direction.

[0013] In an embodiment, with the base as a reference, a height of the second protruding member is lower than a height of the first protruding member by a preset distance.

[0014] In an embodiment, the preset distance is determined based on a number of turns of the first winding, a number of turns of the second winding, vacuum permeability, and an effective magnetic flux area of the first protruding member, the second protruding member, and the third protruding member.

[0015] In an embodiment, a material of the second protruding member is different from materials of the first protruding member and the third protruding member.

[0016] In a second aspect, the present disclosure further provides a transformer, including: the core of any one of the above-described embodiments in the first aspect; a first winding disposed in the first accommodation space, where a lead-out portion of the first winding is configured to extend out of the first opening; and a second winding disposed in the second accommodation space, where a lead-out portion of the second winding is configured to extend out of the second opening.

[0017] In an embodiment, the transformer includes two said cores; the two cores are disposed opposite to each other, the first accommodation spaces of the two cores form a first winding space, the second accommodation spaces of the two cores form a second winding space, the first openings of the two cores form a first opening space, and the second openings of the two cores form a second opening space; the first winding is disposed in the first winding space, and the lead-out portion of the first winding is configured to extend out of the first opening space; and the second winding is disposed in the second winding space, and the lead-out portion of the second winding is configured to extend out of the second opening space.

[0018] In an embodiment, the two cores are identical.

[0019] In an embodiment, the first winding accommodates the second winding therein, and the lead-out portion of the second winding does not pass over the first winding when extending out of the second opening.

[0020] In an embodiment, the first winding is configured to be electrically connected to a first circuit, and the second winding is configured to be electrically connected to a second circuit.

[0021] In an embodiment, the transformer further includes a mounting plate. A first hole and a second hole are defined in the mounting plate, the core is connected to the mounting plate, the lead-out portion of the first winding passes through the first hole after extending out of the core, and the lead-out portion of the second winding passes through the second hole after extending out of the core.

[0022] In an embodiment, the mounting plate has a protruding structure on a side of the first opening. The first hole is defined in the protruding structure, a distance between the first hole and the core satisfies a first preset requirement, and a distance between the second hole and the core satisfies a second preset requirement.

[0023] In an embodiment, a third hole is defined in the mounting plate and located between the first hole and the second hole.

[0024] In an embodiment, the transformer further includes a first bobbin and a second bobbin. The first bobbin is disposed in the first accommodation space, the first bobbin is configured to fix the first winding, the first bobbin includes a first limiting portion, and the first limiting portion is configured to limit the lead-out portion of the first winding. The second bobbin is disposed in the second accommodation space, the second bobbin is configured to fix the second winding, the second bobbin includes a second limiting portion, and the second limiting portion is configured to limit the lead-out portion of the second winding. The second limiting portion is engaged with the second opening.

[0025] In a third aspect, the present disclosure further provides a circuit board structure, including: a circuit board provided with a first circuit and a second circuit; and the transformer of any one of the above-described embodiments in the second aspect, disposed on the circuit board, wherein the first winding is electrically connected to the first circuit, and the second winding is electrically connected to the second circuit.

[0026] In an embodiment, N first circuits, M second circuits, and M transformers constitute a transformer module. The circuit board structure includes at least one transformer module, where N and M are positive integers, and N is less than or equal to M.

[0027] In an embodiment, the first circuit is disposed at a first side of the circuit board, the second circuit is disposed at a second side of the circuit board, the transformer is disposed between the first circuit and the second circuit, the first opening space of the transformer faces the first circuit, and the second opening space of the transformer faces the second circuit.

[0028] In an embodiment, a fourth hole is defined at a position corresponding to the transformer in the circuit board.

[0029] Regarding the above-described core, transformer, and circuit board structure, the core includes the base, the first protruding member provided on the first surface of the base, the second protruding member, and the third protruding member. The first accommodation space that is configured to accommodate the first winding is formed between the first protruding member and the second protruding member. The second accommodation space that is configured to accommodate the second winding is formed between the second protruding member and the third protruding member. As such, the first winding formed in this manner is located at an outer side, and the second winding is located at an inner side. To allow the lead-out portions of the first winding and the second winding to be led out for connection with other electronic components, the core provided by the present disclosure is provided with the first opening and the second opening, and the second opening is located at a side away from the first opening, such that the lead-out portions of the first winding and the second winding are led out from two sides away from each other. In an aspect, the lead-out portion of the second winding does not require the first winding to be designed with a special recess for leading out, which simplifies the processing of the first winding, and assembly of the first winding and the second winding. In another aspect, the core provided by the present disclosure allows the first circuit to be disposed at a side of the first opening and the second circuit to be disposed at a side of the second opening, such that a physical layout of the first circuit and the second circuit is more reasonable. For example, the physical layout of the circuits can reduce interference caused by different circuit components, and can further make overall wiring on the circuit board shorter, thereby saving area on the circuit board. In addition, the first winding and the second winding do not overlap with each other, and in particular, there is no overlap between the lead-out portion of the first winding and the second winding, and there is no overlap between the lead-out portion of the second winding and the first winding. This avoids the physical interference between the first winding and the second winding, facilitates the processing and assembly of the winding structure of the transformer, and avoids the proximity effect between the first winding and the second winding, thereby increasing the utilization of the windings.BRIEF DESCRIPTION OF THE DRAWINGS

[0030] To more clearly describe the technical solutions in the embodiments of the present disclosure or in the related art, the accompanying drawings required for describing the embodiments or the related art are briefly introduced below. Apparently, the accompanying drawings in the following description merely involve some embodiments of the present disclosure. For those of ordinary skill in the art, other drawings can also be obtained based on these accompanying drawings without inventive efforts. FIG. 1 is a schematic diagram illustrating a lead-out manner of a first winding and a second winding in the related art. FIG. 2 is a schematic structural diagram illustrating a core in an embodiment. FIG. 3 is a schematic structural diagram illustrating a core accommodating windings in an embodiment. FIG. 4 is a schematic diagram illustrating both a lead-out portion of a first winding and a lead-out portion of a second winding extending out of a core in an embodiment. FIG. 5 is a schematic diagram illustrating a first opening defined between a first protruding member and a second protruding member in an embodiment. FIG. 6 is a schematic diagram illustrating a second opening defined at a position outside a third protruding member in an embodiment. FIG. 7 is a schematic diagram illustrating a shape of a first sub-opening and / or a second sub-opening in an embodiment. FIG. 8 is a schematic diagram illustrating a shape of a first sub-opening and / or a second sub-opening in another embodiment. FIG. 9 is a side view of a core in an embodiment. FIG. 10 is a schematic structural diagram illustrating a transformer in an embodiment. FIG. 11 is a schematic structural diagram illustrating a transformer in which a first winding and a second winding are not shown in another embodiment. FIG. 12 is an exploded view of a transformer in an embodiment. FIG. 13 is a schematic structural diagram illustrating a transformer having a mounting plate in an embodiment. FIG. 14 is a schematic diagram illustrating a position relationship between a mounting plate and a core when a transformer has a mounting plate in an embodiment. FIG. 15 is a schematic diagram of a circuit board structure using the above-described transformer in an embodiment. FIG. 16 is a schematic diagram illustrating a circuit board of the first circuit, the second circuit, and the transformer in FIG. 15 in an embodiment.

[0031] Description of reference signs: 10, core; 11, base; 12, first protruding member; 13, second protruding member; 14, third protruding member; 15, first winding; 16, second winding; 161, wire; 20, transformer; 21, first bobbin; 22, second bobbin; 23, mounting plate; 231, first hole; 232, second hole; 233, protruding structure; 234, third hole; 24, cover plate; 30, circuit board structure; 31, circuit board; 311, first side of the circuit board; 312, second side of the circuit board; 32, first circuit; 33, second circuit; 34, transformer module; S1, first surface; S2, second surface; Q1, first opening; Q2, second opening; P1, first accommodation space; P2, second accommodation space.DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] The technical solutions in the embodiments of the present disclosure are clearly and completely described below with reference to the accompanying drawings in the embodiments of the present disclosure. Apparently, the described embodiments are merely some embodiments of the present disclosure, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present disclosure without any inventive efforts fall within the scope of protection of the present disclosure.

[0033] To make the above objectives, features, and advantages of the present disclosure more apparent and understandable, specific embodiments of the present disclosure are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to facilitate full understanding of the present disclosure. However, the present disclosure can be implemented in many other manners different from those described herein, and similar improvements can be made by those skilled in the art without departing from the connotation of the present disclosure. Therefore, the present disclosure is not limited by the specific embodiments disclosed below.

[0034] In the description of the present disclosure, it should be understood that the terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", and "circumferential" indicate orientations or position relationships as shown in the accompanying drawings, and are merely intended to facilitate the description of the present disclosure and simplify the description, rather than indicating or implying that the indicated device or element must have a particular orientation, or be constructed and operated in a particular orientation. Therefore, such terms should not be understood as a limitation on the present disclosure.

[0035] In addition, the terms "first" and "second" are used for descriptive purposes only, and should not be understood as indicating or implying relative importance or implying the number of technical features indicated. Thus, a feature defined by "first" or "second" can explicitly or implicitly include at least one such feature. In the description of the present disclosure, the meaning of "a plurality of" is at least two, such as two or three, unless explicitly and specifically defined otherwise.

[0036] In the present disclosure, unless otherwise explicitly specified or defined, the terms such as "mounted", "coupled", "connected", and "fixed" should be understood in a broad sense. For example, such terms may mean a fixed connection, a detachable connection, or an integral connection; may mean a mechanical connection or an electrical connection; may mean a direct connection, or an indirect connection via an intermediate medium; and may mean an internal communication between two elements or an interactive relationship between two elements, unless otherwise explicitly defined. For those of ordinary skill in the art, the specific meanings of the above terms in the present disclosure can be understood according to specific situations.

[0037] In the present disclosure, unless otherwise explicitly specified and defined, a first feature being "above" or "below" a second feature can mean that the first feature and the second feature are in direct contact, or that the first feature and the second feature are in indirect contact via an intermediate medium. Moreover, the first feature being "on", "above", or "over" the second feature can mean that the first feature is directly above or obliquely above the second feature, or merely indicates that a horizontal height of the first feature is higher than that of the second feature. The first feature being "under", "below", or "beneath" the second feature can mean that the first feature is directly below or obliquely below the second feature, or merely indicates that the horizontal height of the first feature is lower than that of the second feature.

[0038] It should be noted that, when an element is referred to as being "fixed on" or "disposed on" another element, the element can be directly on the another element or an intermediate element can also be present. When an element is referred to as being "connected to" another element, the element can be directly connected to the another element, or an intermediate element can also be present. The terms "vertical", "horizontal", "upper", "lower", "left", "right", and similar expressions used herein are for illustrative purposes only, and do not represent the only implementation.

[0039] A transformer is composed of a core and windings. For example, the core can be an iron core made of a magnetic material, such as ferrite or a material of an iron powder core. The material of the iron powder core may be iron-silicon-aluminum, iron-silicon, or the like.

[0040] FIG. 1 shows a core in the related art. As shown in FIG. 1, the core includes a center magnetic post, a middle magnetic post, and an outer magnetic post. The middle magnetic post and the outer magnetic post are open on the same side, and are configured to lead out a primary winding and a secondary winding, i.e., the primary winding and the secondary winding are both led out from an opening W.

[0041] Such opening arrangement firstly makes assembly of the primary winding and the secondary winding relatively difficult, and secondly, when the primary winding and the secondary winding are connected to a circuit on an external circuit board, wiring is overly long, which occupies more area on the circuit board and has an impact on performance of other functions.

[0042] Accordingly, an embodiment of the present disclosure provides a core 10 that can reduce an area occupied on a circuit board, such that more area on the circuit board can be allocated for placing heat dissipating components.

[0043] Referring to FIG. 2, FIG. 2 shows a schematic diagram of the core 10 in an embodiment of the present disclosure. This embodiment provides the core 10, which includes a base 11, a first protruding member 12, a second protruding member 13, and a third protruding member 14. A first surface S1 of the base 11 is provided with the first protruding member 12. The second protruding member 13 and the third protruding member 14 are each located on the base 11. The second protruding member 13 is disposed within the first protruding member 12. The first surface S1 of the base 11, the first protruding member 12, and the second protruding member 13 surround to form a first accommodation space P1 between the second protruding member 13 and the first protruding member 12. The third protruding member 14 is disposed within the second protruding member 13. The first surface S1 of the base 11, the second protruding member 13, and the third protruding member 14 surround to form a second accommodation space P2 between the third protruding member 14 and the second protruding member 13.

[0044] The first protruding member 12 is a protrusion along an edge of the first surface S1 of the base 11. The base 11 and the first protruding member 12 jointly form an enclosure structure that is hollow inside and open at one end. Optionally, the second protruding member 13 is located within the first protruding member 12, i.e., located inside the enclosure structure. The second protruding member 13 can be an annular structure. The third protruding member 14 is located inside the annular structure and is smaller than the inner ring of the annular structure, such that the first accommodation space P1 is formed between the first protruding member 12 and the second protruding member 13, and the second accommodation space P2 is formed between the second protruding member 13 and the third protruding member 14. As such, the first accommodation space P1 and the second accommodation space P2 may be formed as concentric circles.

[0045] Optionally, the base 11 can be a disc-shaped structure or a substantially disc-shaped structure. In this case, the first protruding member 12 and the base 11 form a cylindrical structure that is hollow inside and open at one end. The annular second protruding member 13 is located inside the cylindrical structure, and the third protruding member 14 is located inside the second protruding member 13. The third protruding member 14 can be a cylindrical structure. Optionally, the base 11, the first protruding member 12, the second protruding member 13, and the third protruding member 14 can be concentric.

[0046] Optionally, a material of the second protruding member 13 can be different from a material of the first protruding member 12 and a material of the third protruding member 14, such that magnetic permeability of the second protruding member 13 is different from magnetic permeability of the first protruding member 12 and magnetic permeability of the third protruding member 14, thereby making the density of a magnetic field more uniform.

[0047] Optionally, the first protruding member 12, the second protruding member 13, the third protruding member 14, and the base 11 are made of the same material, and the same mold can be used during manufacturing, thereby improving manufacturing efficiency. Optionally, the first protruding member 12, the second protruding member 13, the third protruding member 14, and the base 11 can be an integrally formed structure.

[0048] Referring to FIG. 3, FIG. 3 shows a schematic structural diagram of the core 10 accommodating windings in an embodiment. The first accommodation space P1 is configured to accommodate a first winding 15. The second accommodation space P2 is configured to accommodate a second winding 16. The winding is formed by winding a wire. For example, the winding can be formed by winding a single wire, or can be formed by a plurality of wires wound in parallel. The plurality of wires can be insulated or uninsulated from each other. In an optional implementation, the winding is formed by the plurality of wires wound in parallel, and the plurality of wires are uninsulated from each other. For example, the winding can be formed by 2000 extremely fine wires wound in parallel. In another optional implementation, the plurality of wires are insulated from each other. For example, after 2000 extremely fine wires are formed into a single wire coated with an insulating material, two such wires each coated with the insulating material are wound in parallel to form the winding.

[0049] Referring to FIG. 2, with the third protruding member 14, the second protruding member 13, and the first protruding member 12 arranged in order from the inside to the outside, the core 10 defines a first opening Q1 at a position outside the second protruding member 13. The first winding 15 is accommodated in the first accommodation space P1. The first accommodation space P1 is located in a region outside the second protruding member 13. A lead-out portion of the first winding 15 passes through the first opening Q1 and extends out of the core 10.

[0050] The core 10 defines a second opening Q2 at a side of the core away from the first opening Q1. A lead-out portion of the second winding 16 passes through the second opening Q2 and then extends out of the core 10. The second opening Q2 being away from the first opening Q1 refers to that, when a position of the first opening Q1 is determined, the second opening Q2 is at a relatively large angle from the first opening Q1, for example, the second opening Q2 and the first opening Q1 are arranged at opposite sides.

[0051] Referring to FIG. 4, FIG. 4 shows a schematic diagram illustrating respective lead-out portions of the first winding 15 and the second winding 16 extending out of the core in an embodiment. FIG. 4 shows a view taken from the direction A in FIG. 3. The winding is formed by winding a wire. The lead-out portion can be an unwound part of the wire. For example, the lead-out portion can be an end portion of the wire. As shown in FIG. 4, the lead-out portion of the first winding is denoted by 15-1, and the lead-out portion of the second winding is denoted by 16-1.

[0052] When the core 10 is assembled with the first winding 15 and the second winding 16, the lead-out portion of the first winding 15 is configured to extend out from the first opening Q1. Optionally, both a first end and a second end of the first winding 15 are configured to extend out from the first opening Q1, and are configured to be electrically connected to a circuit element on an AC side. The first end and the second end of the first winding 15 can be end leads of the wire, such as, two pins at an end portion of the first winding 15. The lead-out portion of the second winding 16 is configured to extend out from the second opening Q2. Optionally, both a first end and a second end of the second winding 16 are configured to extend out from the second opening Q2, and are configured to be electrically connected to a circuit element on a DC side. The first end and the second end of the second winding 16 can be end leads of the wire, such as, two pins at an end portion of the second winding 16.

[0053] In a feasible implementation, the second opening Q2 is located at a side of the core 10 opposite to the first opening Q1. In other feasible implementations, an angle between a line connecting a center of the second opening Q2 and a center of the third protruding member 14 and a line connecting a center of the first opening Q1 and the center of the third protruding member 14 can be between 90° and 180°, inclusive of 90° and 180°. In a specific embodiment, the angle between the line connecting the center of the second opening Q2 and the center of the third protruding member 14 and the line connecting the center of the first opening Q1 and the center of the third protruding member 14 is 90°.

[0054] The core provided by the present disclosure defines the first opening Q1 and the second opening Q2. The second opening Q2 is located at the side away from the first opening Q1, such that the lead-out portions of the first winding 15 and the second winding 16 are led out from two sides away from each other. In an aspect, the lead-out portion of the second winding 16 does not require the first winding 15 to be designed with a special recess for leading out, which simplifies the processing of the first winding 15, and the assembly of the first winding 15 and the second winding 16.

[0055] In another aspect, the core provided by the present disclosure allows the first circuit to be disposed at a side of the first opening Q1 and the second circuit to be disposed at a side of the second opening Q2, such that a physical layout of the first circuit and the second circuit is more reasonable. For example, the physical layout of the circuits can reduce interference caused by different circuit components, and can further make overall wiring length on the circuit board shorter, thereby saving area on the circuit board.

[0056] In addition, the first winding 15 and the second winding 16 do not overlap with each other, which avoids physical interference between the first winding 15 and the second winding 16, facilitating the processing and assembly of a winding structure of a transformer. Moreover, a proximity effect between the first winding 15 and the second winding 16 can be avoided, thereby increasing utilization of the windings. The proximity effect refers to a phenomenon in which, when the first winding 15 and the second winding 16 carry alternating currents, respectively, in opposite directions, alternating magnetic fields generated by each winding induce an eddy current in the other winding, causing the actual current distribution in the other winding to concentrate toward one side of the cross section, resulting in an increase in the resistance of the winding and a decrease in the utilization of the winding.

[0057] In an embodiment, continuing to refer to FIG. 2, the first opening Q1 is defined in the first protruding member 12. Optionally, the first opening Q1 is configured to extend along the first protruding member 12 to the base 11.

[0058] In another exemplary embodiment, referring to FIG. 5, FIG. 5 shows a schematic diagram illustrating the first opening Q1 defined between the first protruding member 12 and the second protruding member 13 in an embodiment. In this case, the first opening Q1 is defined in the base 11. With such an opening arrangement, the first protruding member 12 is not required to have an opening, which can reduce magnetic flux leakage and increase an effective magnetic flux area of the core.

[0059] Continuing to refer to FIG. 5, the first opening Q1 can be a plurality of small holes, such that each pin of the lead-out portion of the first winding 15 extends into a corresponding small hole. Optionally, the first opening Q1 can also be a single large hole, and all pins of the lead-out portion of the first winding 15 extend out of the single large hole.

[0060] In an embodiment, referring to FIG. 6, FIG. 6 shows a schematic diagram illustrating second openings Q2 defined at a position outside the third protruding member 14 in an embodiment. The second openings Q2 are defined in the base 11. In this embodiment, the second openings Q2 are defined in the base 11, and the lead-out portion of the second winding 16 extends downward out of the second openings Q2. Optionally, the second openings Q2 are defined in the second protruding member 13 and in the base 11 between the second protruding member 13 and the first protruding member 12 (this embodiment is not shown in FIG. 6). The lead-out portion of the second winding 16 extends downward out of the base after extending out from the second protruding member 13. With such an opening arrangement, the first protruding member 12 and / or the second protruding member 13 is not required to have an opening, which can reduce the magnetic flux leakage and increase the effective magnetic flux area of the core.

[0061] A formula for magnetic flux density is B = L×I / (N×Ae), where Ae is the effective magnetic flux area of the core, i.e., the area of a cross section of the first protruding member 12, the second protruding member 13, and the third protruding member 14, B is the magnetic flux density, and I is the current in the winding. It can be derived from the formula that Ae is inversely proportional to B. An excessively large magnetic flux density B of the transformer can cause the transformer to easily saturate. Therefore, to ensure that B is relatively small, Ae should be relatively large. Considering constraints on a volume of the transformer, the effective magnetic flux area Ae should be increased as much as possible under a condition that the volume of the transformer remains unchanged.

[0062] Optionally, the second winding 16 is formed by a plurality of wires 161 wound in parallel. Winding in parallel refers to winding two or more wires in parallel to form an integral body. The winding formed by the plurality of wires wound in parallel can also increase the current that can be applied to the winding.

[0063] FIG. 7 shows a schematic diagram illustrating a shape of a first sub-opening and / or a second sub-opening in an embodiment. As shown in FIG. 7, when the wires 161 are cylindrical and there are two wires 161, the shape of the sub-opening can be a rounded rectangular hole with arc-shaped ends and a straight middle portion.

[0064] FIG. 8 shows a schematic diagram illustrating a shape of a first sub-opening and / or a second sub-opening in another embodiment. As shown in FIG. 8, when the wires 161 are cylindrical and there are three wires 161, the shape of the sub-opening can be a triangular hole with three rounded corners and straight sides. Optionally, when there are three wires 161, the shape of the sub-opening can also be consistent with the shape when there are two wires 161, except that the length of the straight middle portion is extended, such that the three wires 161 are arranged side by side.

[0065] A cross section of the wire 161 is typically circular. When the first sub-opening and / or the second sub-opening is configured as a perfect circle, there is redundant movable space in the sub-opening when a plurality of wires 161 extend together into the sub-opening, causing the wires 161 tend to swing in the sub-opening, and the wires 161 tend to detach and cause an open circuit after being electrically connected to an external circuit. Therefore, it is necessary to limit the position of the wires 161 through the sub-opening. In this embodiment, the shape of the first sub-opening and / or the second sub-opening corresponds to the shape of the plurality of wires 161 and the number of the wires 161, such that the wires 161 are limited within the first sub-opening and / or the second sub-opening without swinging.

[0066] Continuing to refer to FIG. 2, in an exemplary embodiment, all of the base 11, the second protruding member 13, and the first protruding member 12 are provided with openings, and the openings are communicated with each other to form the second opening Q2. The base 11 also has an opening at a side away from the first opening Q1, and the opening of the base 11 is configured to extend from the third protruding member 14 to an outside. The second protruding member 13 and the first protruding member 12 each have an opening at the side away from the first opening Q1. As such, the openings formed by the base 11, the second protruding member 13, and the first protruding member 12 are sequentially communicated with each other to form the second opening Q2. Referring to FIG. 3, the communicating second opening Q2 can provide a large accommodation space, such that the first winding 15 can partially protrude laterally in a direction away from the third protruding member 13, thereby providing more space for the second winding 16. In addition, when all of the base 11, the second protruding member 13, and the first protruding member 12 are provided with openings and the openings are communicated with each other, a consecutive integral structure can be formed when a mold is designed, facilitating the processing and manufacturing of the core and the assembly of the windings.

[0067] Continuing to refer to FIG. 2, in an exemplary embodiment, a width of the second opening Q2 increases progressively or in a stepwise manner in a radially outward direction, and the radially outward direction refers to a radial direction of the core. As such, the area of the opening of the first protruding member 12 is larger than the area of the opening of the second protruding member 13, and the first protruding member 12 can provide a clearance space for the first winding 15. Referring to FIG. 3, the first winding 15 is configured to protrude outward at a position of the opening of the first protruding member 12, such that the second winding 16 located inside the first winding 15 has a large accommodation space, facilitating arrangement when the second winding 16 has a plurality of wires 161.

[0068] Referring to FIG. 9, FIG. 9 shows a side view of the core 10 observed from the direction indicated by the arrow B in FIG. 2 in an embodiment. In an exemplary embodiment, with the base 11 as a reference, a height of the second protruding member 13 is lower than a height of the first protruding member 12, and a height difference therebetween is a preset distance. As such, an air gap is formed at a side of the second protruding member 13 away from the base 11, and leakage inductance can be controlled through the air gap. In addition, referring to FIG. 11, when two cores 10 jointly form a transformer, the air gap is formed between the two second protruding members 13.

[0069] The core 10 is configured to assemble a transformer. A formula for inductance L of the transformer is equal to N 2< ×u×Ae / lg, where N is the number of turns of the winding coil, u is the vacuum permeability which is a constant, Ae is the effective magnetic flux area of the magnetic posts of the first protruding member 12, the second protruding member 13, and the third protruding member 14, and lg is the length of the air gap. Therefore, the smaller the air gap of the transformer, the less the magnetic flux leakage, such that current distribution on a copper wire can be not affected, and the copper loss is small. According to the above formula, the preset distance by which the second protruding member 13 is lower than the first protruding member 12 can be determined based on a number of turns of the first winding 15, a number of turns of the second winding 16, vacuum permeability, and the effective magnetic flux area of the first protruding member 12, the second protruding member 13, and the third protruding member 14.

[0070] Based on the same technical concept, an embodiment of the present disclosure further provides a transformer 20. In an exemplary embodiment, the transformer 20 includes the above-described core 10, the first winding 15, and the second winding 16. The core 10 includes the base 11, the second protruding member 13, and the third protruding member 14. The first surface S1 of the base 11 is provided with the first protruding member 12. The second protruding member 13 is disposed within the first protruding member 12. The first accommodation space P1 is formed between the second protruding member 13 and the first protruding member 12. The third protruding member 14 is disposed within the second protruding member 13. The second accommodation space P2 is formed between the third protruding member 14 and the second protruding member 13.

[0071] The core 10 defines the first opening Q1 at a position outside the second protruding member 13. The core 10 defines the second opening Q2 at a side away from the first opening Q1. The first winding 15 is disposed in the first accommodation space P1, and the lead-out portion of the first winding 15 is configured to extend out of the first opening Q1. The second winding 16 is disposed in the second accommodation space P2, and the lead-out portion of the second winding 16 is configured to extend out of the second opening Q2. After the lead-out portions of the first winding 15 and the second winding 16 extend out of the core 10, the lead-out portions can be electrically connected to an external circuit. For example, the lead-out portion of the first winding 15 can be electrically connected to the first circuit after extending out of the core 10, and the lead-out portion of the second winding 16 can be electrically connected to the second circuit after extending out of the core 10.

[0072] In the transformer 20 provided by the present disclosure, the second opening Q2 is located at the side away from the first opening Q1, such that the lead-out portions of the first winding 15 and the second winding 16 are led out from two sides away from each other. In an aspect, the lead-out portion of the second winding 16 does not require the first winding 15 to be designed with a special recess for leading out, which simplifies the processing of the first winding 15, and the assembly of the first winding 15 and the second winding 16. In another aspect, the transformer 20 provided by the present disclosure allows the first circuit to be disposed at a side of the first opening Q1 and the second circuit to be disposed at a side of the second opening Q2, such that a physical layout of the first circuit and the second circuit is more reasonable. For example, the physical layout of the circuits can reduce interference caused by different circuit components, and can further make overall wiring on the circuit board shorter, thereby saving area on the circuit board.

[0073] Referring to FIG. 10, FIG. 10 shows a schematic structural diagram of the transformer 20 in an embodiment. In an exemplary embodiment, the transformer 20 can include a cover plate 24. The cover plate 24 is disposed over the core 10 to shield the first winding 15 and the second winding 16, as well as the second protruding member 13 and the third protruding member 14. Optionally, the cover plate 24 can be any type of magnetic plate.

[0074] Referring to FIG. 11, FIG. 11 shows a schematic structural diagram of the transformer 20 including two cores 10 in another embodiment, in which the first winding 15 and the second winding 16 are not shown. In this embodiment, the transformer includes two cores 10, and the two cores 10 are disposed opposite to each other. The two cores 10 are disposed opposite to each other and are bonded together. The first protruding members 12 of the two cores 10 face each other. The second protruding members 13 of the two cores 10 face each other. The third protruding members 14 of the two cores 10 face each other. The two first accommodation spaces P1 collectively form the first winding space R1. The two second accommodation spaces P2 collectively form the second winding space R2. The first openings Q1 of the two cores 10 form a first opening space. The second openings Q2 of the two cores 10 form a second opening space. The first winding 15 is disposed in the first winding space R1. The lead-out portion of the first winding 15 is configured to extend out of the first opening space. The second winding 16 is disposed in the second winding space R2. The lead-out portion of the second winding 16 is configured to extend out of the second opening space.

[0075] In an embodiment, the two cores 10 are identical, and are symmetrically bonded together. In this embodiment, only one mold is required during manufacturing, which improves manufacturing efficiency and reduces mold-making cost.

[0076] Referring to FIG. 12, FIG. 12 shows an exploded view of the transformer 20 in an embodiment. Optionally, the first winding 15 is disposed in the first winding space R1. The second winding 16 is disposed in the second winding space R2. The lead-out portions of the first winding 15 and the second winding 16 extend out of the first opening space and the second opening space of the transformer 20, respectively. The first winding 15 accommodates the second winding 16 therein. The lead-out portion of the second winding 16 does not pass over the first winding 15 when extending out of the second opening space.

[0077] The first winding 15 and the second winding 16 do not overlap with each other, which avoids physical interference between the first winding 15 and the second winding 16. In particular, there is no overlap between the lead-out portion of the first winding and the second winding, and there is no overlap between the lead-out portion of the second winding and the first winding. This facilitates the processing and assembly of the winding structure of the transformer, and can avoid the proximity effect between the first winding 15 and the second winding 16, thereby increasing the utilization of the windings.

[0078] In a feasible implementation, the transformer 20 further includes a first bobbin 21 and a second bobbin 22. The first bobbin 21 is disposed in the first accommodation space P1, and is configured to fix the first winding 15. The second bobbin is disposed in the second accommodation space P2, and is configured to fix the second winding 16. The function of the bobbins is to support and fix the windings, and to provide appropriate structural support. Optionally, the bobbin can be a cylindrical structure made of an insulating material. The winding is wound around the bobbin, such that the winding can be effectively supported, preventing the winding from loosening or deforming.

[0079] The first bobbin 21 includes a first limiting portion. The first limiting portion is configured to limit the lead-out portion of the first winding 15. The second bobbin 22 includes a second limiting portion. The second limiting portion is configured to limit the lead-out portion of the second winding 16 and prevent the lead-out portion from swinging. The second limiting portion is engaged with the second opening Q2, further enhancing the limiting effect on the lead-out portion of the second winding 16.

[0080] Optionally, the transformer 20 further includes a mounting plate 23. Referring to FIG. 13, FIG. 13 shows a schematic structural diagram of the transformer 20 having the mounting plate 23 in an embodiment. FIG. 13 is an assembled view of FIG. 12, with the mounting plate 23 added to FIG. 12. The core 10 is connected to the mounting plate 23. The mounting plate 23 is disposed on the second surface S2 of the base 11 (as shown in FIG. 4), i.e., a surface facing away from the first protruding member 12, the second protruding member 13, and the third protruding member 14. The mounting plate 23 has a first hole 231 and a second hole 232. The lead-out portion of the first winding 15 passes through the first hole 231 after extending out of the core 10. The lead-out portion of the second winding 16 passes through the second hole 232 after extending out of the core 10.

[0081] Optionally, the first hole 231 and / or the second hole 232 can include a plurality of sub-holes, and the shape of the sub-holes corresponds to the winding. For example, when the second winding 16 is formed by a plurality of wires wound in parallel, the shape of the second hole 232 corresponds to the shape and the number of the wires.

[0082] To make the distance between the winding and the core 10 satisfy requirements of safety specification, the distance between the lead-out portion of the first winding 15 and the core 10 should satisfy a first preset requirement, and the distance between the lead-out portion of the second winding 16 and the core 10 should satisfy a second preset requirement. The mounting plate 23 is provided with a protruding structure 233 on a side of the first opening Q1. The first hole 231 is defined in the protruding structure 233, and a distance between the first hole 231 and the core 10 satisfies the first preset requirement, such that the distance between the lead-out portion of the first winding 15 and the core 10 satisfies the requirements of safety specification when the lead-out portion of the first winding 15 passes through the first hole 231. When all of the base 11, the second protruding member 13, and the first protruding member 12 are provided with openings and the openings are communicated with each other to form the second opening Q2, a position of the second hole 232 can be selected within a range of the second opening Q2. In this case, a distance between the second hole 232 and the core 10 should satisfy the second preset requirement, such that the distance between the lead-out portion of the second winding 16 and the core 10 satisfies the requirements of safety specification when the lead-out portion of the second winding 16 passes through the second hole 232.

[0083] Referring to FIG. 14, FIG. 14 shows a schematic diagram illustrating a position relationship between the mounting plate 23 and the core when the transformer 20 has the mounting plate 23 in an embodiment. FIG. 14 is a view of the core 10 in FIG. 2 with the mounting plate 23 assembled, as viewed from the direction of arrow C. When the transformer 20 is assembled with the mounting plate 23, the mounting plate 23 is disposed on the second surface S2 of the base 11 of one of the cores 10. Optionally, the lead-out portions of the first winding 15 and the second winding 16 can be configured to extend out of the core 10 and pass through the mounting plate 23.

[0084] To satisfy the requirements of safety specification, a distance L1 between the two sub-holes of the first hole 231 on the mounting plate 23 should be greater than 2 mm, such that a spacing distance between pins of the lead-out portion of the first winding 15 satisfies the requirements. A distance L2 between the first hole 231 and the third protruding member 14 should be greater than 3.5 mm, such that the distance between the lead-out portion of the first winding 15 and the core 10 satisfies the requirements. A distance L3 between the two sub-holes of the second hole 232 on the mounting plate 23 can be in the range of 3 mm to 6 mm, ensuring that a spacing between pins of the second winding 16 is neither excessively small nor excessively large. The spacing should not be excessively small, to prevent solder bridging. The spacing should not be excessively large, to facilitate the routing of the second winding 16. A distance L4 from an edge of the third protruding member 14 to an edge of the mounting plate 23 at the second opening Q2 can be in the range of 17 mm to 23 mm, such that the accommodation space of the second opening Q2 is enlarged and a distance between the second hole 232 and the core 10 is greater than 1 mm, satisfying the requirements of safety specification. A width L5 of the first protruding member 12 can be in the range of 1.5 mm to 3.5 mm, a width L7 of the second protruding member 13 can be in the range of 2.5 mm to 4.5 mm, and a radius L6 of the third protruding member 14 can be in the range of 8 mm to 12 mm, ensuring the sufficient effective magnetic flux area, such that the magnetic flux of the transformer under normal operating conditions is less than 0.25T. In addition, a width of the formed air gap can be in the range of 1.5 mm to 2.5 mm to optimize the leakage inductance of the transformer.

[0085] In an embodiment, the mounting plate 23 is further provided with a third hole 234. The third hole 234 is located between the first hole 231 and the second hole 232. Optionally, the third hole can be configured to mount a heat dissipation component to reduce the temperature of the transformer 20 during use, thereby extending service life of the transformer 20.

[0086] Based on the same technical concept, an embodiment of the present disclosure further provides a circuit board structure. Referring to FIG. 15, FIG. 15 shows a schematic diagram of a circuit board structure 30 using the above-described transformer 20 in an embodiment. The circuit board structure 30 includes a circuit board 31 and the transformer 20 disposed on the circuit board 31. The circuit board 31 is provided with the first circuit 32 and the second circuit 33. The first winding 15 of the transformer 20 is electrically connected to the first circuit 32, and the second winding 16 of the transformer 20 is electrically connected to the second circuit 33.

[0087] Referring to FIG. 16, FIG. 16 shows a schematic diagram illustrating a circuit board of the first circuit 32, the second circuit 33, and the transformer 20 in FIG. 15 in an embodiment. As shown in FIG. 16, the first winding is electrically connected to the first circuit 32, and the second winding is electrically connected to the second circuit 33. The first circuit 32 is provided with a first terminal 32-1, and a voltage of the first terminal 32-1 can be an alternating-current voltage or a direct-current voltage. The second circuit 33 is provided with a second terminal 33-1, and a voltage of the second terminal 33-1 can be an alternating-current voltage or a direct-current voltage.

[0088] Regarding the first circuit 32 and the second circuit 33, some implementations are provided below.

[0089] When the voltage of the first terminal 32-1 is a direct-current voltage, and the voltage of the second terminal 33-1 is an alternating-current voltage, the first circuit 32, the transformer 20, and the second circuit 33 constitute a DC-to-AC conversion circuit.

[0090] When the voltage of the first terminal 32-1 is a direct-current voltage, and the voltage of the second terminal 33-1 is a direct-current voltage, the first circuit 32, the transformer 20, and the second circuit 33 constitute a DC-to-DC conversion circuit.

[0091] When the voltage of the first terminal 32-1 is an alternating-current voltage, and the voltage of the second terminal 33-1 is a direct-current voltage, the first circuit 32, the transformer 20, and the second circuit 33 constitute an AC-to-DC conversion circuit.

[0092] When the voltage of the first terminal 32-1 is an alternating-current voltage, and the voltage of the second terminal 33-1 is an alternating-current voltage, the first circuit 32, the transformer 20, and the second circuit 33 constitute an AC-to-AC conversion circuit.

[0093] Optionally, the first circuit 32 can be an H-bridge circuit. The H-bridge circuit consists of four switching devices. Different current paths can be achieved by controlling on / off states of the four switching devices. Optionally, the second circuit 33 can be a cyclo-converter circuit. The cyclo-converter circuit converts an input AC power into an output AC power of a different frequency, and generally consists of controlled electronic switching devices. The output voltage waveform and a frequency are adjusted through timely triggering and control of the switching components.

[0094] In an exemplary embodiment, referring to FIG. 15, the first circuit 32 is disposed at the first side 311 of the circuit board. The second circuit 33 is disposed at the second side 312 of the circuit board. The transformer 20 is disposed between the first circuit 32 and the second circuit 33. The first opening Q1 of the transformer 20 faces the first circuit 32, and the second opening Q2 of the transformer 20 faces the second circuit 33. Optionally, the first side 311 of the circuit board and the second side 312 of the circuit board are not located at the same side of the circuit board, and can be located at two sides of the circuit board away from each other. In addition, the first side 311 of the circuit board and the second side 312 of the circuit board can be located at two opposite sides of the circuit board. The position of the transformer is not limited to being exactly in the middle. Any position that can reduce the length of the wiring falls within the scope of protection of the embodiments of the present disclosure. With such arrangement, the first circuit 32 and the second circuit 33 can be reasonably laid out on the circuit board 31, the length of the wiring is reduced, and the area of the circuit board 31 is maximally utilized. Moreover, copper on the circuit board has loss, and requirements of heat dissipation for the circuit board are also strict. Thus, the reduction in the length of the wiring can reduce the loss.

[0095] Optionally, the circuit board 31 can be provided with a fourth hole below the transformer 20. The lead-out portion of the transformer 20 is directly connected to the circuit, and there is no wiring at the position where the transformer 20 is placed. Therefore, the circuit board 31 can be provided with the fourth hole at the position corresponding to the transformer 20. The fourth hole can be configured to mount a heat dissipation component to cool the transformer 20, thereby extending effective operating time of the transformer 20.

[0096] In an exemplary embodiment, N first circuits 32, M second circuits 33, and M transformers 20 constitute a transformer module 34. The circuit board structure 30 includes at least one transformer module 34. N and M are positive integers. N is less than or equal to M. For example, as shown in FIG. 15, one first circuit 32, two second circuits 33, and two transformers 20 constitute one transformer module 34. One first circuit 32 is electrically connected to the first windings of a plurality of transformers 20. One second circuit 33 is electrically connected to the second winding 16 of one of the plurality of transformers 20. Optionally, with the first circuit 32, the plurality of transformers 20, and the plurality of second circuits 33 as one transformer module 34, a plurality of transformer modules 34 can be provided on the circuit board 31.

[0097] The technical features of the above embodiments can be arbitrarily combined. For simplicity of description, not all possible combinations of the technical features in the above embodiments are described. However, all combinations of these technical features should be considered to be within the scope described in the specification, as long as there are no contradictions in the combinations of these technical features.

[0098] The above embodiments merely show some implementations of the present disclosure. The descriptions thereof are specific and detailed, but they should not be construed as limiting the scope of the disclosure. It should be noted that those of ordinary skill in the art can further make modifications and improvements without departing from the inventive concept of the present disclosure, and these modifications and improvements all fall within the scope of protection of the present disclosure. Therefore, the scope of protection of the present disclosure should be determined by the appended claims.

Claims

1. A core, comprising: a base, a first surface of the base having a first protruding member; a second protruding member disposed within the first protruding member, wherein a first accommodation space is formed between the second protruding member and the first protruding member, and the first accommodation space is configured to accommodate a first winding; and a third protruding member disposed within the second protruding member, wherein a second accommodation space is formed between the third protruding member and the second protruding member, and the second accommodation space is configured to accommodate a second winding; wherein the core defines a first opening at a position outside the second protruding member, such that a lead-out portion of the first winding is configured to extend out of the first opening; and the core defines a second opening at a side of the core away from the first opening, such that a lead-out portion of the second winding is configured to extend out of the second opening.

2. The core according to claim 1, wherein the first opening is defined in the first protruding member or is defined between the first protruding member and the second protruding member.

3. The core according to claim 1, wherein the second opening is defined at a position outside the third protruding member.

4. The core according to claim 3, wherein the second winding is formed by a plurality of wires wound in parallel, the second opening comprises a first sub-opening and a second sub-opening, the first sub-opening is configured to receive first ends of the plurality of wires therethrough, and the second sub-opening is configured to receive second ends of the plurality of wires therethrough.

5. The core according to claim 4, wherein a shape of the first sub-opening and / or the second sub-opening corresponds to a shape of the plurality of wires and the number of the plurality of wires.

6. The core according to claim 1, wherein all of the base, the second protruding member, and the first protruding member are provided with openings, and the openings are communicated with each other to form the second opening.

7. The core according to claim 6, wherein a width of the second opening increases progressively or in a stepwise manner in a radially outward direction.

8. The core according to claim 1, wherein, with the base as a reference, a height of the second protruding member is lower than a height of the first protruding member by a preset distance.

9. The core according to claim 8, wherein the preset distance is determined based on a number of turns of the first winding, a number of turns of the second winding, vacuum permeability, and an effective magnetic flux area of the first protruding member, the second protruding member, and the third protruding member.

10. The core according to any one of claims 1 to 9, wherein a material of the second protruding member is different from materials of the first protruding member and the third protruding member.

11. A transformer, comprising: the core according to any one of claims 1 to 10; a first winding disposed in the first accommodation space, wherein a lead-out portion of the first winding is configured to extend out of the first opening; and a second winding disposed in the second accommodation space, wherein a lead-out portion of the second winding is configured to extend out of the second opening.

12. The transformer according to claim 11, wherein the transformer comprises two said cores; the two cores are disposed opposite to each other, the first accommodation spaces of the two cores form a first winding space, the second accommodation spaces of the two cores form a second winding space, the first openings of the two cores form a first opening space, and the second openings of the two cores form a second opening space; the first winding is disposed in the first winding space, and the lead-out portion of the first winding is configured to extend out of the first opening space; and the second winding is disposed in the second winding space, and the lead-out portion of the second winding is configured to extend out of the second opening space.

13. The transformer according to claim 12, wherein the two cores are identical.

14. The transformer according to claim 11, wherein the first winding accommodates the second winding therein, and the lead-out portion of the second winding does not pass over the first winding when extending out of the second opening.

15. The transformer according to claim 11, wherein the transformer further comprises a mounting plate, a first hole and a second hole are defined in the mounting plate, the core is connected to the mounting plate, the lead-out portion of the first winding passes through the first hole after extending out of the core, and the lead-out portion of the second winding passes through the second hole after extending out of the core.

16. The transformer according to claim 15, wherein the mounting plate has a protruding structure on a side of the first opening, the first hole is defined in the protruding structure, a distance between the first hole and the core satisfies a first preset requirement, and a distance between the second hole and the core satisfies a second preset requirement.

17. The transformer according to claim 15, wherein a third hole is defined in the mounting plate and located between the first hole and the second hole.

18. The transformer according to claim 11, wherein the transformer further comprises a first bobbin and a second bobbin, the first bobbin is disposed in the first accommodation space and configured to fix the first winding, the first bobbin comprises a first limiting portion, the first limiting portion is configured to limit the lead-out portion of the first winding, the second bobbin is disposed in the second accommodation space and configured to fix the second winding, the second bobbin comprises a second limiting portion, and the second limiting portion is configured to limit the lead-out portion of the second winding, wherein the second limiting portion is engaged with the second opening.

19. A circuit board structure, comprising: a circuit board provided with a first circuit and a second circuit; and the transformer according to any one of claims 11 to 18, disposed on the circuit board, wherein the first winding is electrically connected to the first circuit, and the second winding is electrically connected to the second circuit.

20. The circuit board structure according to claim 19, wherein N said first circuits, M said second circuits, and M said transformers constitute a transformer module, and the circuit board structure comprises at least one transformer module, wherein N and M are positive integers, and N is less than or equal to M.

21. The circuit board structure according to claim 19, wherein the first circuit is disposed at a first side of the circuit board, the second circuit is disposed at a second side of the circuit board, the transformer is disposed between the first circuit and the second circuit, the first opening space of the transformer faces the first circuit, and the second opening space of the transformer faces the second circuit.

22. The circuit board structure according to claim 19, wherein a fourth hole is defined at a position corresponding to the transformer in the circuit board.

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