KR20220133496A - Transformer and Circuit Board Comprising the Same - Google Patents

Abstract

The present invention relates to a transformer bobbin and a transformer including the same. One embodiment of the transformer bobbin according to the present invention comprises: a core including an upper part of the core and a lower part of the core, having a first midfoot formed in an overlapping region in a first direction from the lower part of the core toward the upper part of the core, and having a second midfoot formed outside the overlapping region on the lower part of the core; and a first coil and a second coil having at least part thereof disposed in the core, wherein the bobbin has at least part thereof disposed in the core, and has a first midfoot penetration hole penetrated by the first midfoot and a second midfoot accommodation groove having the second midfoot disposed therein. Therefore, provided are a slimmed bobbin, a transformer and a circuit board including the same.

Description

Transformer and circuit board including same {Transformer and Circuit Board Comprising the Same}

The present invention relates to a transformer and a circuit board including the same.

The transformer is exemplarily used in a power supply device of a display device, and as the size and slimness of the display device are accelerated, high power density and high efficiency characteristics are required along with the slimming of the power supply device.

In response to such high-density and high-efficiency requirements, a high-frequency power supply (eg, LLC resonant converter) has been proposed as a power supply for driving an LED backlight, which must have a particularly wide voltage gain, and a planar transformer has been developed and used early on.

A planar transformer, for example, in an LLC resonant converter, increases the leakage flux through a core-shaped design without inserting a separate leakage layer or an I-type core between the primary and secondary coils to obtain desired resonance characteristics. Leakage inductance (Lk inductance) can be secured.

Here, in order to obtain a stable output voltage even with a wide voltage gain, it is necessary to reduce the leakage inductance, and thus, a high-frequency planar transformer having a small leakage inductance is required.

In particular, for high frequency driving of 160 ~ 300 kHz, it is necessary to adjust the leakage inductance (Lk inductance) to be lower than before. .

On the other hand, in the conventional transformer, the bobbin structure has a limit in slimming, and in order to obtain a more slimmer than the conventional transformer, the bobbin structure needs to be improved.

That is, a change to the conventional core structure is required to implement a lower and more sophisticated leakage inductance than in the prior art, and a change to the bobbin structure is also required to obtain a slimmer transformer.

An object of the present invention is to solve at least one of the above-mentioned problems of the prior art.

In particular, an object of the present invention is to provide a slimmer bobbin and a transformer, and a circuit board including the same.

One embodiment of the transformer according to the present invention includes an upper part of the core and a lower part of the core, wherein the first midfoot is formed in a region overlapping with the first direction from the lower part of the core to the upper part of the core, and the lower part of the core is formed. a core portion having a second midfoot formed outside the overlapping region; a coil unit including a first coil and a second coil, at least a portion of which is disposed in the core; and a bobbin disposed at least partly in the core part and accommodating at least part of the coil part.

Here, the lower part of the core may include: a first middle foot formed in a first direction from the lower part of the core toward the upper part of the core and a pair of first outer feet disposed with the first middle foot therebetween; and a second midfoot spaced apart from the first midfoot in a second direction perpendicular to the first direction and formed under the core.

In addition, the bobbin has a first midfoot through hole formed to allow the first midfoot to pass therethrough and a second midfoot receiving groove formed to receive the second midfoot through the bobbin.

In at least one embodiment of the present invention, the bobbin includes a first coil accommodating part providing an accommodating space for the first coil and a second coil accommodating part providing an accommodating space for the second coil. 1 bobbin part; and a second bobbin part including a first terminal part for the first coil and a second terminal part for the second coil.

Further, in at least one embodiment of the present invention, the second coil accommodating part is disposed above the first coil accommodating part with respect to the first direction, and the second bobbin part, wherein the second coil accommodating part is disposed inside A second coil receiving portion groove of the through groove and a first coil receiving portion groove extending laterally from a lower portion of the through groove and having the first coil receiving portion disposed therein are formed.

Here, the first bobbin part may include an upper plate, a middle plate, and a lower plate spaced apart from each other, the first coil accommodating part may be formed between the middle plate and the lower plate, and the second coil accommodating part may be formed between the upper plate and the middle plate. .

In at least one embodiment of the present invention, the first midfoot through-hole is formed to pass through the upper plate, the middle plate, and the lower plate, and the second midfoot receiving groove includes a lower portion of the first midfoot through hole in the lower plate. It is formed by extending laterally toward the terminal part.

In addition, in at least one embodiment of the present invention, the first bobbin portion, connecting between the upper plate and the middle plate, the upper rim surrounding the first midfoot through hole; and a lower rim connecting the middle plate and the lower plate and surrounding the lower part of the first midfoot through hole and the second midfoot receiving groove.

And, in at least one embodiment of the present invention, the upper plate is disposed inside and accommodated in the second coil accommodating part groove, and the middle plate and/or the lower plate is disposed and accommodated in the first coil accommodating part groove.

Herein, a fixing protrusion for preventing downward separation of the middle plate or the lower plate may be formed on the circumferential wall of the first coil receiving part groove.

Further, in at least one embodiment of the present invention, at least a portion of the peripheral wall of the second coil receiving portion groove is formed with a passage for communicating the second coil receiving space to the second terminal portion.

Here, the passage may be formed by opening at least a portion of a peripheral wall of the second coil receiving part groove toward the second terminal part.

In addition, in at least one embodiment of the present invention, the second terminal portion, a plurality of coil wire grooves are formed, and an inclined surface that increases from the passage to the coil wire groove is formed.

Here, the inclined surface may have a wider width toward the coil wire groove.

In at least one embodiment of the present invention, a pair of core guides disposed with the upper part of the core therebetween are formed on the upper plate to determine the position of the upper part of the core.

Further, in at least one embodiment of the present invention, a first terminal wire passage is formed in the middle plate of the first bobbin part, and the first terminal wire passage is communicated to the upper part of the first terminal part in the second bobbin part A second terminal wire passage is formed.

Here, a pair of pin portions may be formed on the first terminal portion with the second terminal wire passage interposed therebetween.

In at least one embodiment of the present invention, the core includes a pair of outer feet disposed with the first midfoot interposed therebetween, and a width and a height of a portion of the bobbin disposed in the core, respectively, are the pair of outer feet is smaller than the distance between the medial surfaces of the and the height of the groove between the first midfoot and the outer foot.

On the other hand, one embodiment of the circuit board according to the present invention includes the transformer of at least one embodiment described above.

Here, the transformer may be a transformer having a leakage inductance of 15 to 20 uH under a frequency of 160 to 300 kHz.

In addition, other electronic components may be mounted on the circuit board, and plating lines may be formed on the surface of the circuit board in a predetermined pattern for the construction of electrical circuits of such components. And, such a circuit board constitutes an LLC resonant converter by way of example and may be included in a power supply for a display.

According to the present invention, it is possible to obtain a slimmer bobbin and a transformer, and a circuit board including the transformer.

In particular, it is possible to obtain a bobbin suitable for a transformer having a new structure capable of lowering leakage inductance more precisely compared to a magnetic component having a conventional core structure, a transformer therefor, and a circuit board including the same.

1 shows a transformer as one embodiment of a magnetic component according to the present invention. (illustration of the primary coil and the primary coil is omitted in the drawing of FIG. 1 .)
FIG. 2 is an exploded perspective view of the transformer of FIG. 1 . (In FIG. 2, the primary coil and the secondary coil are shown together.)
Fig. 3 shows the core shown in Fig. 2;
FIG. 4 shows a lower part of the core of FIG. 3 . {(a) shows a plan view of the lower part of the core, (b) shows a front view of the lower part of the core.}
FIG. 5 shows an upper part of the core of FIG. 3 . {(a) shows an upside-down plan view of the upper part of the core of FIG. 3, and (b) shows a right-side view of the upper part of the core.}
6 and 7 show the first bobbin unit shown in FIG. 2 .
8 is a front view and a right side view of the first bobbin part of FIG. 6 .
9 and 10 show the second bobbin unit shown in FIG.
11 shows a state in which the first bobbin part 40 and the second bobbin part 30 are coupled.
12 shows a first embodiment of a method for winding a secondary coil in the present invention.
13 shows a second embodiment of a method for winding a secondary coil in the present invention.
14 shows the relationship between leakage inductance and gap for an embodiment core of the present invention.

Since the present invention can have various changes and can have various embodiments, specific embodiments are illustrated and described in the drawings. However, this is not intended to limit the present invention to a specific embodiment, it should be understood to include all modifications, equivalents and substitutes included in the spirit and scope of the present invention.

As used herein, the suffixes "module" and "part" are used only for nomenclature between components, and are interpreted as presupposing that they are physically and chemically separated or separated, or that they can be separated or separated. should not

Terms including an ordinal number such as “first” and “second” may be used to describe various elements, but the elements are not limited by the terms. The above terms are used only for the purpose of distinguishing one component from another.

The term “and/or” is used to include any combination of the plurality of items in question. For example, “A and/or B” includes all three cases such as “A”, “B”, and “A and B”.

When a component is referred to as being “connected” or “connected” to another component, it may be directly connected or connected to the other component, but it is understood that other components may exist in between. it should be

In the description of the embodiments, each layer (film), region, pattern or structures is referred to as “on” or “under” the substrate, each layer (film), region, pad or patterns. The description that it is formed on includes all those formed directly or through another layer. In addition, the standards for "upper/upper" or "lower/lower" are based on the appearance shown in the drawings for convenience, in principle, unless otherwise expressed in the specification or properties between each of the components, and the components It is only used to indicate the relative positional relationship between the elements for convenience, and should not be construed as limiting the actual position of the components. For example, "above B" only indicates that B is shown above A in the drawing, unless otherwise stated or unless A or B has to be located above B due to the nature of A or B, in the actual product, etc., B may be located under A, or B and A may be placed sideways left and right.

In addition, since the thickness or size of each layer (film), region, pattern, or structure in the drawings may be changed for clarity and convenience of description, it does not fully reflect the actual size.

The terms used in the present application are only used to describe specific embodiments, and are not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly dictates otherwise. In the present application, terms such as “comprise” or “have” are intended to designate that a feature, number, step, operation, component, part, or combination thereof described in the specification exists, but one or more other features It is to be understood that this does not preclude the possibility of the presence or addition of numbers, steps, operations, components, parts, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in a commonly used dictionary should be interpreted as having a meaning consistent with the meaning in the context of the related art, and should not be interpreted in an ideal or excessively formal meaning unless explicitly defined in the present application. does not

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

First, FIG. 1 shows a transformer as an embodiment of a magnetic component according to the present invention. (The illustration of the primary coil 50 and the secondary coil 60 is omitted in the drawing of FIG. 1 .) And, FIG. 2 is an exploded perspective view of the transformer of FIG. 1, and FIG. 3 is the core shown in FIG. 4 shows the core lower part 20 of the core of FIG. 3 {(a) shows a plan view of the core lower part 20, (b) shows a front view of the core lower part 20}, 5 shows the upper part of the core 10 of the core of FIG. 3 ((a) shows an upside-down plan view of the upper part of the core 10 of the core of FIG. 3, and (b) shows the right side view of the upper part of the core 10. }, FIGS. 6 and 7 show the first bobbin part 40 shown in FIG. 2 , and FIG. 8 shows a front view and a right side view of the first bobbin part 40 of FIG. 6 , FIGS. 9 and FIG. 10 shows the second bobbin part 30 shown in FIG. 2 , and FIG. 11 shows a state in which the first bobbin part 40 and the second bobbin part 30 are coupled.

The core shown in FIGS. 1 and 2 will be described in detail with reference to FIGS. 3 to 5 .

The core of this embodiment includes a core upper portion 10 and a core lower portion 20 , and the core upper portion 10 overlaps in a first direction from lower to upper with respect to the core lower portion 20 and is above the core lower portion 20 . It is a structure that is arranged and forms a single core.

The lower core 20 includes an open area Ao and a closed area Ac, and the closed area Ac includes the upper core 10 and the upper core 10 in a first direction from the core lower 20 to the core upper 10 . Defined as an overlapping and closed area, the open area Ao is an area formed extending from the closed area Ac in a second direction perpendicular to the first direction and not covered by the core upper portion 10. It is defined as an area exposed outside the closed area Ac.

In the present embodiment, the planar area of the open area Ao is smaller than the planar area of the closed area Ac.

In the closed region Ac, a pair of first outer foot lower portions 22a and 22b are formed with the first lower midfoot 21 and the first lower midfoot 21 interposed therebetween.

Here, the corner portion of the first midfoot lower 21 includes a round shape, and the first outer foot lower portions 22a and 22b have an angled shape at the corner (including a round shape with a radius much smaller than the round shape of the first midfoot) ), but is not limited thereto.

The first midfoot lower 21 has grooves r1 and r2 formed on both sides thereof, and is spaced apart from each other by the same distance from each of the first outer foot lower portions 22a and 22b.

In the open area Ao, the second middle foot 23 and a pair of second outer feet 24a and 24b disposed with the second middle foot 23 interposed therebetween are formed.

Here, as shown in FIG. 4 , the outer corner portion of the second midfoot 23 includes a round shape, and the second outer feet 24a and 24b are all angled in the corner portion (round of the second midfoot outer corner portion). round shape with a radius much smaller than the shape), but is not limited thereto.

The second middle foot 23 is also formed with grooves r1 and r2 on both sides, and is spaced apart from each other by a predetermined interval from the second outer foot 24a, 24b.

In the open region Ao, a groove portion r3 is formed between the first midfoot lower 21 and the second midfoot 23 and between the first outer foot lower portions 22a, 22b and the second outer foot 24a, 24b. and the first midfoot lower 21 and the second midfoot 23 are spaced apart by that much spaced apart by the groove portion r3.

The upper core 10 is disposed above the closed region Ac of the lower core 20, the first midfoot upper 11 is formed in the center, and a pair of first midfoot uppers 11 are interposed therebetween. Outer foot upper (12a, 12b) is disposed.

The first midfoot upper 11 is also formed with grooves r4 and r5 on both sides, and is disposed to be spaced apart from each other by the same distance from each of the first outer foot uppers 12a and 12b. In this embodiment, the grooves r4 and r5 of the upper core 10 and the grooves r1 and r2 of the lower portion of the core have the same width w.

In addition, the first midfoot upper 11 includes all round shapes at the corners thereof, and the first outer foot uppers 12a and 12b are all angled at the corners (a radius much smaller than the round shape of the first midfoot) including the round shape of), but is not limited thereto.

The closed region Ac of the upper core 10 and the lower core 20 has a shape structure symmetrical to each other in an assembled state.

The upper core 10 of FIG. 5 is a state in which the upper part of the core 10 shown in FIG. 3 is turned upside down (FIG. 5 (a)) and a view of the right side thereof (FIG. 5 (b)). In the assembled state as shown in FIG. 3 , the first midfoot upper 11 of the core upper 10 is disposed above the first midfoot lower 21 , and the upper first outer foot 12b and the lower first outer foot in FIG. 5 . The upper portion 12a is disposed above the lower first outer foot lower portion 22b and the upper first outer foot lower portion 22a of FIG. 4 , respectively.

Preferably, the upper core 10 is disposed to have a predetermined gap above the lower core 20 . To this end, a gap may be formed between the first midfoot upper/lower portion 11 and 21 and/or between the first outer foot upper/lower upper/lower portion 12a, 12b, 22a, 22b.

With the core upper portion 10 disposed over the core lower portion 20, the first midfoot upper 11 and the first midfoot lower 21 form a first midfoot, and the first outer foot upper 12a, 12b and the first Outer foot lower (22a, 22b) is to form a first outer foot.

3 to 5, in a state in which the upper core 10 is disposed over the lower core 20, the second midfoot 23 and the pair of second outer feet 24a, 24b, respectively, are viewed The first midfoot upper 11 and the pair of first outer foot uppers 12a, 12b and the first midfoot lower 21 and the pair of first outer foot lower portions 22a and 22b, respectively, are imaginary planes having the same end surfaces. It can be located on (P).

With respect to this core structure, the primary coil 50 (first coil) and the secondary coil 60 (second coil) are disposed inside the core, and the primary coil 50 includes the first midfoot 11 and 21 and the second coil. The closed area (Ac) and the open area (Ao) of the core are arranged in a wound structure while surrounding the second middle foot 23 , and the secondary coil 60 has a wound structure surrounding only the first middle foot 11 and 21 . It is arranged in the closed area Ac. In this case, a portion of the secondary coil 60 may be disposed in the open area Ao beyond the closed area Ac. In this embodiment, the total thickness of the primary coil 50 may be greater than the total thickness of the secondary coil 60 , but the thickness of the single secondary coil 60 is greater than the single primary coil 50 . .

And, in this embodiment, the number of turns of the primary coil 50 is greater than the number of turns of the secondary coil 60 .

In the closed region Ac, the primary coil 50 and the secondary coil 60 are linked, and in the open region Ao, both coils 50 and 60 are not linked. Voltage conversion is achieved in the closed region Ac where both coils 50 and 60 are linked, and the leakage inductance generated in the closed region Ac is offset by the leakage magnetic flux in the open region Ao, which is a non-bridging region. A leakage inductance of the desired magnitude is derived. Like the conventional EE core, it is possible to secure a leakage inductance lower than that of the prior art by offsetting the leakage inductance that occurs relatively large in the closed region Ac through the open region Ac to lower the total leakage inductance.

In the transformer of this embodiment, the leakage inductance is between the first midfoot lower 21 and the second midfoot 23 and/or the first outer foot lower part 22a, 22b and the second outer foot 24a, 24b, as will be described later. It can be adjusted according to the size of the gap between them.

Meanwhile, in the present embodiment, the bobbin includes a first bobbin part 40 and a second bobbin part 30 , and as shown in FIG. 11 , the first bobbin part 40 moves under the second bobbin part 30 . inserted and assembled.

In this embodiment, the first bobbin part 40 provides a primary coil accommodating part (first coil accommodating part) and a secondary coil accommodating part (second coil accommodating part), and the second bobbin part 30 is Terminals for the primary coil 50 and the secondary coil 60 are provided.

The first bobbin part 40 includes an upper plate 41 , a middle plate 42 and a lower plate 43 , and a secondary coil receiving part is formed between the upper plate 41 and the middle plate 42 , and the middle plate 42 and A primary coil receiving portion is formed between the lower plate 43 .

The first bobbin unit 40 has a first midfoot through hole 44 penetrating from the upper plate 41 to the lower plate 43 , and the lower plate 43 has a primary to be described later in the first midfoot through hole 44 . A second midfoot receiving groove 47 extending toward the terminal portion 32 (first terminal portion) to accommodate the second midfoot 23 is formed.

An upper rim 45 is formed between the upper plate 41 and the middle plate 42 to surround the upper portion of the first midfoot through hole 44 , and the first midfoot penetration is between the middle plate 42 and the lower plate 43 . A lower rim 46 is formed to surround the lower portion of the hole 44 and the second midfoot receiving groove 47 .

The primary coil receiving portion includes a space formed surrounding the lower rim 46, and the secondary coil receiving portion includes a space formed surrounding the upper rim 45, in each of those spaces the primary coil 50 and A secondary coil 60 is disposed.

A pair of core guides 41a and 41b protruding upwardly are included on the upper plate 41 of the first bobbin part 40 . In a state in which the first bobbin part 40 is inserted and coupled to the second bobbin part 30 , the pair of core guides 41a and 41b have a structure that protrudes higher above the upper surface of the second bobbin part 30 , and the one A core upper portion 10 is positioned between the pair of core guides 41a and 41b. Positioning of the core relative to the bobbin (or coil) is easily achieved because of the pair of core guides 41a and 41b.

The second bobbin part 30 has a primary terminal part 32 and a secondary terminal part 33 (second terminal part) on both sides, and a body part 31 between the terminal parts 32 and 33 .

In the primary terminal part 32, a first coil wire groove 32a is formed in the first pin part 32c into which terminal pins connected to the primary coil 50 terminal are inserted and fixed on both sides, and the primary coil ( 50) First wiring protrusions 32b for wiring a coil wire (hereinafter referred to as a terminal wire) leading to a terminal are formed.

A plurality of second coil wire grooves 33a are alternately arranged in a line in the secondary terminal part 33 , and second wiring protrusions 33b for wiring the coil wires are formed on the upper surface.

The secondary coil 60 in this embodiment includes four individual coil wires, each of which forms one turn for the secondary coil 60 . For this reason, the secondary terminal part 33 of this embodiment includes a total of eight second coil wire grooves 33a, respectively. At this time, each secondary coil 60 is drawn out through the second coil wire groove 33a, and may be in contact with a separate terminal pin (not shown).

In addition, the second bobbin part 30 has a middle plate receiving groove 36 of a non-penetrating groove in which the middle plate 42 (or lower plate 43) of the first bobbin part 40 is accommodated as a first coil receiving part groove at the lower part. this is formed In addition, the second bobbin part 30 is formed with an upper plate accommodating through-groove 34 of a through-groove for accommodating the upper plate 41 of the first bobbin part 40 as a second coil accommodating part groove.

Here, in order to prevent the middle plate 42 (or the lower plate 43) of the first bobbin part 40 from being displaced downward in the accommodated state on the peripheral wall of the middle plate receiving groove 36, a plurality of fixing protrusions 36a) is formed

In addition, a first terminal wire passage 42a through which the terminal wire of the primary coil 50 accommodated in the primary coil accommodating part passes is formed in the middle plate 42 of the first bobbin part 40, and the second bobbin part At 30 , a second terminal wire passage 35 corresponding to the first terminal wire passage 42a is formed so that the terminal wire of the primary coil 50 passes through the upper portion of the primary terminal part 32 . Protrusions 42b and 42c for fixing the coil wire of the primary coil 50 are formed on both sides of the first terminal wire passage 42a of the middle plate 42 of the first bobbin part 40 .

In the present embodiment, the peripheral wall 34a of the upper plate receiving through-groove 34 is disposed to surround the space of the secondary coil receiving portion. The secondary coil 60 is accommodated in the secondary coil accommodating part space formed in the space between the upper rim 45 of the first bobbin part 40 and the circumferential wall 34a of the upper plate accommodating through-groove 34 .

Here, the peripheral wall of the secondary terminal part 33 side of the peripheral wall 34a of the upper plate receiving through groove 34 has a wall height such that it opens toward the secondary terminal part 33, as shown in FIG. It has a low or almost no shape to provide a passage to the secondary terminal part 33 for each coil wire of the secondary coil 60, and gradually widens and increases in height toward the secondary terminal part 33 Since the inclined surface 37 is formed so as to gradually increase, it is possible to increase the degree of freedom in the arrangement of the terminal wires through the role of guiding and supporting the arrangement of the terminal wires of the secondary coil 60, and it is possible to facilitate the wiring work.

In the present embodiment, the width of the first bobbin part 40 is equal to or smaller than the width of the body part 31 of the second bobbin part 30 , and thus the first bobbin part 40 is the second bobbin part 30 . In a state coupled to ( 30 ), the first bobbin part 40 does not protrude out of the body part 31 of the second bobbin part 30 .

In addition, the width of the body part 31 of the second bobbin part 30 is equal to or smaller than the distance between the inner wall surfaces of the first outer legs 12a, 12b, 22a, 22b, and the first bobbin part 40 The height of the bobbin portion positioned inside the core in a state in which the second bobbin unit 30 and the second bobbin unit 30 are coupled to each other is the height of the groove formed between the first midfoot 11 and 21 and the first outer foot 12a, 12b, 22a, 22b (' r1 height + r4 height' or 'r2 height + r5 height') so that the bobbin is aligned and placed inside the core. That is, in a state in which the primary coil 50 and the secondary coil 60 are disposed in the first bobbin part 40 and the second bobbin part 30 , the combined body is completely accommodated in the cores 10 and 20 . .

Meanwhile, FIG. 12 shows an embodiment of a winding method of the secondary coil 60 in the present invention, and FIG. 13 shows a comparative example of a winding method of the secondary coil 60 in the present invention.

The figure shown in the upper part of FIG. 12 shows the wiring of the secondary coil 60 according to the first embodiment on the second bobbin unit 30 , and the figure shown at the bottom constitutes the secondary coil 60 . shows a wiring diagram in which each coil wire is connected to the second terminal pins.

In this embodiment, the second terminal pins ⑩ and ⑨ are connected to the second terminal pins ⑤ and ⑥, respectively, and the second terminal pins ⑧ and ⑦ are respectively connected to the second terminal pins ③ and ④ secondary coil 60 This is wired

Here, the second terminal pins ③ and ④ are + terminals, the second terminal pins ⑨ and ⑩ are - terminals, and the second terminal pins ⑤, ⑥, ⑦ and ⑧ are ground.

On the other hand, in the comparative example shown in FIG. 13, the second terminal pins ⑩ and ⑨ are respectively connected to the second terminal pins ③ and ④, and the second terminal pins ⑧ and ⑦ are respectively connected to the second terminal pins ⑤ and ⑥. The secondary coil 60 is wound. Here, the second terminal pins ③ and ⑥ are + terminals, the second terminal pins ⑧ and ⑨ are - terminals, and the second terminal pins ④, ⑤, ⑦, and ⑩ are ground.

Since the secondary coil 60 winding method of the above embodiment makes the total length of the secondary output winding the same, there is an effect of improving the current unbalance between the coil wires of the secondary coil 60 compared to the comparative example. In addition, the wiring and structure of the secondary coil 60 lowers the resistance to the applied current to increase the efficiency of the transformer, and has the effect of suppressing the heat generated in the transformer by lowering the heat generated by the resistance.

Meanwhile, FIG. 14 shows the leakage inductance of the core of the embodiment of the present invention (indicated as 'open core' in FIG. 14(b)) and the gap between the first midfoot lower part 21 and the second midfoot 23 (r3 spacing) ) represents the relationship between As shown in FIG. 14 , in the core of the embodiment of the present invention, the leakage inductance gradually decreases with a large change rate according to the increase in the spacing, and thus the leakage inductance lower than that of the conventional EE core can be reached.

Accordingly, the leakage inductance can be more precisely controlled by adjusting the distance between the first and second midfoot, and it is possible to adjust the leakage inductance to 15 to 20 uH for high-frequency driving of 160 to 300 kHz.

10: upper core 11: first midfoot upper
12: upper first exofoot
20: lower core 21: lower first midfoot
22: lower first outer foot 23: second middle foot
24: second exopod
30: second bobbin part 31: body part
32: primary terminal part 33: secondary terminal part
34: upper plate receiving through hole 35: second terminal wire passage
36: middle plate receiving groove
40: first bobbin part 41: top plate
42: middle plate 43: lower plate
44: first midfoot through hole 45: upper rim
46: lower rim 47: second midfoot receiving groove
50: primary coil
60: secondary coil
r1 to r5: groove part P: virtual plane
w : width

Claims (17)

a core portion including an upper core and a lower core;
a coil part disposed at least partially in the core part and including a first coil and a second coil; and
At least a portion is disposed in the core portion, including a bobbin for accommodating at least a portion of the coil portion,
The lower part of the core,
a first midfoot formed in a first direction from the lower part of the core toward the upper part of the core and a pair of first outfoot disposed with the first midfoot therebetween; and
and a second midfoot spaced apart from the first midfoot in a second direction perpendicular to the first direction and formed under the core,
The bobbin is
a first midfoot through hole formed to pass through the first midfoot and a second midfoot receiving groove formed to receive the second midfoot;
Transformer. According to claim 1,
The bobbin is
A first coil accommodating part providing an accommodating space for the first coil and a second coil accommodating part disposed on the first coil accommodating part in the first direction and providing an accommodating space for the second coil A first bobbin comprising; and
Comprising a second bobbin portion including a first terminal portion for the first coil and a second terminal portion for the second coil,
Transformer. 3. The method of claim 2,
The second bobbin part includes a second coil accommodating part groove formed so that the second coil accommodating part is disposed therein, and a first first coil accommodating part groove extending laterally from a lower portion of the second coil accommodating part groove and formed such that the first coil accommodating part is disposed therein. Containing a coil receiving part groove,
Transformer. 4. The method of claim 3,
The first bobbin unit includes an upper plate, a middle plate, and a lower plate spaced apart from each other,
The first coil receiving part is formed between the middle plate and the lower plate,
The second coil receiving portion is formed between the upper plate and the middle plate,
Transformer. 5. The method of claim 4,
The first midfoot through hole passes through the upper plate, the middle plate, and the lower plate,
The second midfoot receiving groove is formed to extend laterally from a lower portion of the first midfoot through hole toward the first terminal in the lower plate,
Transformer. 5. The method of claim 4,
The first bobbin unit,
an upper rim connecting the upper plate and the middle plate and surrounding the periphery of the first midfoot through hole; and
Connecting between the middle plate and the lower plate, further comprising a lower rim surrounding the periphery of the first midfoot through hole and the periphery of the second midfoot receiving groove,
Transformer. 5. The method of claim 4,
In the second coil receiving part groove, the upper plate is disposed inside and accommodated,
In the first coil receiving part groove, the middle plate and/or the lower plate is disposed and accommodated therein;
Transformer. 8. The method of claim 7,
The first coil receiving unit groove peripheral wall includes a fixing protrusion formed to prevent separation of the middle plate or the lower plate, the transformer. 8. The method of claim 7,
At least a portion of a peripheral wall of the second coil accommodating part groove is formed with a passage for communicating the second coil accommodating space to the second terminal part. 10. The method of claim 9,
The passage is formed by opening at least a portion of a peripheral wall of the second coil receiving part groove toward the second terminal part. 11. The method of claim 10,
The second terminal unit,
A plurality of coil wire grooves are formed,
An inclined surface that rises from the passage toward the coil wire groove is formed,
Transformer. 12. The method of claim 11,
The inclined surface becomes wider as it goes toward the coil wire groove, the transformer. 8. The method of claim 7,
The upper plate is formed with a pair of core guides disposed with the upper part of the core therebetween to determine the position of the upper part of the core. 5. The method of claim 4,
A first terminal wire passage is formed in the middle plate of the first bobbin part,
A second terminal wire passage for communicating the first terminal wire passage to an upper portion of the first terminal portion is formed in the second bobbin portion,
Transformer. 15. The method of claim 14,
A pair of pin portions disposed on the first terminal portion with the second terminal wire passage therebetween are formed. A circuit board comprising the transformer according to any one of claims 1 to 15. 17. The method of claim 16,
The transformer has a leakage inductance of 15 to 20 uH under a frequency of 160 to 300 kHz, a circuit board.

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