KR102647356B1 - Method for manufacturing a resonant converter transformer having enhanced heat dissipation structure - Google Patents

Abstract

An object of the present invention is to provide a method for manufacturing a resonant converter transformer having an excellent heat dissipation structure that facilitates dissipating heat generated from windings and cores due to fringing effects to the outside. The method for manufacturing a resonant converter transformer includes the steps of forming a transformer core assembly; providing a resonant inductor; forming a resonant converter transformer in which the resonant inductor and the transformer core assembly are connected in series; arranging the resonant converter transformer inside a metal case; and filling, drying, and curing the space inside the metal case. According to the present invention, even when a magnetic gap is formed in a large current application, the operating temperature of the ferrite transformer core can be stably maintained.

Description

Method for manufacturing a resonant converter transformer with excellent heat dissipation structure {METHOD FOR MANUFACTURING A RESONANT CONVERTER TRANSFORMER HAVING ENHANCED HEAT DISSIPATION STRUCTURE}

The present invention relates to a method of manufacturing a resonant converter transformer, and more specifically, to a method of manufacturing a resonant converter transformer having an excellent heat dissipation structure that can stably maintain the operating temperature of the ferrite transformer core.

In resonant converters, a core made of ferrite material is used to form a completely closed circuit in the transformer, but there is a problem in that the ferrite core may be magnetically saturated when a large current is required. When using a ferrite core with a large capacity to prevent magnetic flux saturation of the transformer, it is not efficient because the ferrite core is expensive. In order to handle more magnetic flux within a ferrite core of the same capacity, a semi-closed circuit can be formed by leaving a magnetic gap such as an air gap. This means that when an air gap is formed in a ferrite core with high permeability, the magnetic resistance in the magnetic gap increases. Because it is larger than the core, magnetic flux saturation of the ferrite core can be prevented.

However, when forming a magnetic gap, some magnetic flux leaks due to a fringing effect at the edge of the magnetic gap of the ferrite core, generating an eddy current in the winding wound around the core, which causes the winding to And the ferrite core adjacent to it may also be heated to around 120°C, which is the normal operating temperature of the ferrite core, which may adversely affect the operation of the transformer.

(Patent Document 1) KR 10-2022-0072038 A1 (2022. 06. 02.)

Patent Document 1 proposes a core structure with a stepped longitudinal cross-section in the direction of the air gap of the transformer core to reduce the fringing effect itself. However, when using a large current, the windings and core are heated due to the fringing effect occurring in the core, causing damage to the transformer. The problem of reduced efficiency still exists.

Therefore, the present invention solves the problem of heating of the windings and core due to the fringing effect occurring in a resonant converter transformer, and provides an excellent heat dissipation structure that facilitates dissipation of the heat of the winding and core generated by the fringing effect to the outside. The technical task is to provide a method of manufacturing a resonant converter transformer having a.

The technical problem to be achieved by the present invention is not limited to the technical problem mentioned above, and other technical problems not mentioned can be clearly understood by those skilled in the art from the description below. There will be.

In order to achieve this technical problem, in one aspect of the present invention, there is a method of manufacturing a resonant converter transformer, which includes stacking transformer cores by disposing one or more middle cores sandwiched between ceramic plates within the magnetic gap of a ferrite core having a magnetic gap. Forming a body and arranging a plurality of the laminates in parallel so that the magnetic paths are parallel to each other and spaced apart from each other by a distance d1 to form a transformer core assembly, providing a resonance inductor, winding a winding around the resonance inductor and the transformer core assembly. forming a resonant converter transformer in which the resonant inductor and the transformer core assembly are connected in series, disposing the resonant converter transformer inside a metal case, and placing the resonant converter transformer inside the metal case. Injecting a heat dissipating molding liquid having a low thermal conductivity of 1 to 5 W/mK to remove air, including the gap d1 within the transformer core assembly, the gap d3 between the resonant inductor and the transformer core assembly, and the gap between windings. A method of manufacturing a resonant converter transformer is provided, including the steps of filling the space inside a metal case, drying, and curing.

In one aspect of the invention, providing the resonant inductor includes forming a resonant inductor core laminate by disposing one or more middle cores sandwiched between ceramic plates within a magnetic gap of a ferrite core having a magnetic gap, and forming the resonant inductor core laminate. It includes forming a resonance inductor assembly by arranging a plurality of lines in parallel so that the magnetic paths are parallel to each other and spaced apart from each other by a distance d2, and the heat dissipating molding liquid fills the gap d2 in the resonance inductor assembly.

According to the present invention, it is possible to provide a resonant converter transformer with an excellent heat dissipation structure that can stably maintain the operating temperature of the ferrite transformer core even when a magnetic gap is formed when using a large current.

The effects of the present invention are not limited to the effects described above, and should be understood to include all effects that can be inferred from the configuration of the invention described in the detailed description or claims of the present invention.

1 is an explanatory diagram explaining the fringing effect in the transformer air gap.
Figure 2 is a circuit diagram of a general LLC converter.
Figure 3 is an assembly diagram of a transformer core assembly according to an embodiment of the present invention.
Figure 4A is an isometric view of a transformer core assembly according to one embodiment of the present invention.
Figure 4b is a right side view of the transformer core assembly of Figure 4a.
Figure 4C is a top view of the transformer core assembly of Figure 4A.
Figure 5 is an assembly diagram of a resonance inductor assembly according to an embodiment of the present invention.
Figure 6a is an isometric view of a resonant inductor assembly according to an embodiment of the present invention.
FIG. 6B is a right side view of the resonant inductor assembly of FIG. 6A.
Figure 6C is a top view of the resonant inductor assembly of Figure 6A.
Figure 7 is a cross-sectional view of a winding wound in a resonant converter transformer according to an embodiment of the present invention.
Figure 8 is an assembly diagram of a resonant converter transformer according to an embodiment of the present invention assembled in a case.
Figure 9 is an isometric view of the resonant converter transformer according to an embodiment of the present invention mounted in the case, and is an isometric view with the case top plate removed.
Figure 10 is a photo of a resonant converter transformer product in which the resonant converter transformer is mounted in a case and molded with heat-dissipating resin according to an embodiment of the present invention.
Figure 11 is a schematic flowchart of a method of manufacturing a resonant converter transformer according to an embodiment of the present invention.
FIG. 12 is a graph showing the results of measuring temperatures near the core and windings during operation of the resonant converter transformer according to an embodiment of the present invention.

Hereinafter, the present invention will be described with reference to the attached drawings. However, the present invention may be implemented in various different forms and, therefore, is not limited to the embodiments described herein. In order to clearly explain the present invention in the drawings, parts that are not related to the description are omitted, and similar parts are given similar reference numerals throughout the specification. The dimensions of each component in the attached drawings are schematically shown for easy visualization and do not define or limit the dimensions of the components of the actual wireless power reception device.

Throughout the specification, when a part is said to be "connected (connected, contacted, combined)" with another part, this means not only "directly connected" but also "indirectly connected" with another member in between. "Includes cases where it is. Additionally, when a part is said to “include” a certain component, this does not mean that other components are excluded, but that other components can be added, unless specifically stated to the contrary.

The terms used herein are only used to describe specific embodiments and are not intended to limit the invention. Singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, terms such as “comprise” or “have” are intended to designate the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, but are not intended to indicate the presence of one or more other features. It should be understood that it does not exclude in advance the possibility of the existence or addition of elements, numbers, steps, operations, components, parts, or combinations thereof.

Preferred embodiments are presented below to aid understanding of the present invention, but these are merely illustrative of the present invention, and it is clear to those skilled in the art that various changes and modifications are possible within the scope and spirit of the present invention, and such changes and modifications are possible. It is natural that modifications fall within the scope of the attached patent claims.

1 is an explanatory diagram explaining the fringing effect in the transformer air gap. When current is supplied to the winding 20 wound around a transformer core in which E-type ferrite cores 10a and 10b with short central feet are stacked vertically to form an air gap 30, magnetic flux 40 is generated within the core, forming a magnetic circuit. Since the permeability of the air present in the air gap 30 is considerably lower than that of the core, some magnetic flux leaks from the edge of the air gap and spreads to the outside of the air gap, generating leakage magnetic flux 50, which is called the fringing effect. In general, if the air gap is quite small, this fringing effect can be ignored. However, if the air gap is formed to a considerable length, for example, several millimeters, to prevent magnetic saturation of the transformer, this fringing effect can be ignored. does not exist. When a winding is wound near the air gap 30, an eddy current is generated within the winding due to the influence of the leakage magnetic flux 50, and the eddy current may heat the winding by interfering with the flow of current flowing in the winding. In some cases, the ferrite core may heat up. Heating it beyond the normal operating temperature of 120℃ can have a negative effect on transformer efficiency.

A circuit diagram of a general LLC converter will be described with reference to FIG. 2. An LLC resonant converter 10 as shown in FIG. 1 is proposed as a circuit to satisfy the requirements for high efficiency and high density of converters, such as in electric vehicle (EV) charging systems and photovoltaic (PV) systems. The LLC resonant converter 10 has a resonant converter transformer 12 consisting of a resonant inductor (Lr: 11) and a transformer (T1: 13) connected in series thereto, and the zero of the MOSFET and diode located in the first and second transformers -It is possible to implement a high-efficiency high-frequency converter through voltage switching (ZVS). For convenience of explanation, refer to the LLC converter circuit diagram, but the present invention is applicable to all general resonant converter transformers.

Below, with reference to the drawings, a method of manufacturing a resonant converter transformer with an excellent heat dissipation structure according to an embodiment of the present invention will be described.

FIGS. 3 and 4 are for the transformer core assembly 300 corresponding to the transformer 13 in the circuit diagram of FIG. 2, and FIGS. 5 and 6 are for the resonance inductor assembly corresponding to the resonance inductor 11 in the circuit diagram of FIG. 2. 500, and FIGS. 7 to 11 relate to the assembly and manufacturing method of the resonant converter transformer 900 corresponding to the resonant converter transformer 12 of the circuit diagram of FIG. 2, and FIG. 12 shows the performance test results. It's about.

With reference to FIGS. 3 and 4 , a transformer core assembly 300 according to an embodiment of the present invention will be described. FIG. 3 is an assembly diagram of the transformer core assembly 300 according to an embodiment of the present invention, FIG. 4A is an isometric view of the transformer core assembly 300, and FIG. 4B is a right side view of the transformer core assembly 300 of FIG. 4A. , FIG. 4C is a top view of the transformer core assembly 300 of FIG. 4A.

The transformer core assembly 300 is made by stacking E-type ferrite cores 310-1 and 320-1 with a short center foot up and down to form a magnetic gap, and includes a middle core 331-1 sandwiched between ceramic plates within the magnetic gap. It has a first transformer core stack 301 in which one or more 342-1) are disposed, and a plurality of second to fourth transformer core stacks 302, 303, 304 configured in the same manner, the transformer core stack The transformer core assembly 300 is formed by arranging the bodies 301, 302, 303, and 304 in parallel so that their magnetic paths are parallel to each other and spaced apart from each other by a distance d1. In one embodiment, the case where E-type ferrite cores are stacked top and bottom has been described, but one side can be stacked with an E-type core and the other side can be with an E-type core or an I-type core.

The first transformer core stack 301 has a first middle core 331-1 and a second middle core 332-1, and a lower ferrite core 310-1 and a first middle core 331-1. ), between the first middle core (331-1) and the second middle core (332-1), and between the upper ferrite core (320-1) and the second middle core (332-1), respectively, the ceramic plate (341) -1, 342-1, 343-1) are interposed and stacked to fill the magnetic gap without an air gap. The cross sections of the ceramic plates (341-1, 342-1, 343-1) and the cross sections of the middle cores (331-1, 332-1) are the shapes of the surfaces of the central feet of the ferrite cores (310-1, 320-1). is substantially the same as, and the thickness of the ceramic plate (341-1, 342-1, 343-1) and the thickness of the middle core (331-1, 332-1) can be determined according to the specifications of the required transformer product. However, in the embodiments of FIGS. 3 and 4, the thickness of the ceramic plates 341-1, 342-1, and 343-1 is each about 1 mm, and the thickness of the middle cores 331-1 and 332-1 is about 10 mm each. am. The number of middle cores in each laminate can be one or more, and in one embodiment, two middle cores and three ceramic plates are used.

The ceramic plates (341-1, 342-1, 343-1) are made of alumina (Al ₂ O ₃ ), aluminum nitride (AlN), or magnesium oxide (MgO), which have higher permeability than air and excellent thermal conductivity, and By inserting a ceramic plate with a higher magnetic permeability, the fringing effect can be reduced compared to the case of an air gap. As in one embodiment, the thickness of the three ceramic plates is a total of 3 mm, so the fringing effect is reduced compared to the case where the gap is 3 mm at a time. As it is distributed into three parts, the fringing effect can be reduced as a result, and the thermal conductivity of the ceramic plate is excellent, so heat from the core and winding can be easily dissipated via the ceramic plate.

In the same manner as the first transformer core stack 301, the second transformer core stack 302 has a first middle core 331-2 and a second middle core 332-2, and a lower ferrite core. Between the core 310-2 and the first middle core 331-2, between the first middle core 331-2 and the second middle core 332-2, and between the upper ferrite core 320-2 and the second middle core 332-2. Ceramic plates 341-2, 342-2, and 343-2 are interposed between the two middle cores 332-2, respectively, and the third transformer core laminate 303 includes the first middle core 331-2. 3) and a second middle core (332-3), between the lower ferrite core (310-3) and the first middle core (331-3), the first middle core (331-3) and the second middle core ( 332-3) and between the upper ferrite core 320-3 and the second middle core 332-3, respectively, ceramic plates 341-3, 342-3, and 343-3 are interposed and stacked, 4 The transformer core stack 304 has a first middle core 331-4 and a second middle core 332-4, and a lower ferrite core 310-4 and a first middle core 331-4. between, between the first middle core 331-4 and the second middle core 332-4, and between the upper ferrite core 320-4 and the second middle core 332-4, respectively, a ceramic plate 341- 4, 342-4, 343-4) are interposed and laminated.

As shown in FIG. 4, in the transformer core assembly 300, adjacent transformer core laminates 3101, 302, 303, and 304 are spaced apart from each other by a distance d1 from the upper surface to the lower surface of the transformer core assembly 300. The length of the gap d1 may be determined depending on the specifications of the required transformer product, but is approximately 1 mm in the embodiments of FIGS. 3 and 4.

In the transformer core assembly 300, the transformer core laminates 301, 302, 303, and 304 having magnetic paths parallel to each other are spaced apart from each other by an interval d1, so the magnetic paths formed in the core are not blocked by the presence of the interval d1, so the transformer In addition to not adversely affecting performance, the gap d1 serves as a heat dissipation passage through which heat generated in the ferrite core, middle core, ceramic plate, and winding can be dissipated to the outside through the upper and lower surfaces of the transformer core assembly 300. . That is, compared to a large-capacity transformer core in which the gap d1 is not formed, in the case of one embodiment of FIGS. 3 and 4, the transformer core assembly 300 has three gaps d1 extending from the upper surface to the lower surface of the transformer core assembly 300. Because it is formed, the heat generated inside the transformer core can be easily dissipated to the outside through the gap d1.

In particular, one side of the ceramic plate made of alumina (Al ₂ O3), aluminum nitride (AlN), or magnesium oxide (MgO), which has excellent thermal conductivity, is exposed to the gap d1, so heat is released through the ceramic plate to the outside via the gap d1. Since it can be easily dissipated, heat dissipation of the transformer core assembly 300 becomes easy even when a magnetic gap is formed by the combination of the gap d1 and the ceramic play. In addition, as explained below, the space of the transformer core assembly 300 including the gap d1 is filled with heat-dissipating molding fluid while removing air through a separate process, so the transformer core assembly 300 filled with heat-dissipating molding fluid Heat dissipation to the outside becomes easy through the gap d1.

A resonance inductor assembly 500 according to an embodiment of the present invention will be described with reference to FIGS. 5 and 6 . FIG. 5 is an assembly diagram of a resonance inductor assembly according to an embodiment of the present invention, FIG. 6A is an isometric view of a resonance inductor assembly according to an embodiment of the present invention, and FIG. 6B is a right side view of the resonance inductor assembly of FIG. 6A. 6c is a top view of the resonant inductor assembly of FIG. 6a.

The resonance inductor assembly 500 is made by stacking E-type ferrite cores 510-1 and 520-1 with a short center foot up and down to form a magnetic gap, and includes a middle core 531-1 sandwiched between ceramic plates within the magnetic gap. , 532-1, 533-1, and 534-1), and has a first resonance inductor stack 501 in which one or more (532-1, 533-1, 534-1) is disposed, and a second resonance inductor stack 502 configured in the same manner. The resonance inductor assembly 500 is formed by arranging the magnetic fields 501 and 502 in parallel so that their magnetic paths are parallel to each other and spaced apart from each other by a distance d2. In one embodiment, the case where E-type ferrite cores are stacked top and bottom has been described, but one side can be stacked with an E-type core and the other side can be with an E-type core or an I-type core.

The first resonance inductor stack 501 has first to fourth middle cores 531-1, 532-1, 533-1, and 534-1, and a lower ferrite core 510-1 and a first middle core. Between the cores 531-1, between the first middle core 531-1 and the second middle core 532-1, between the second middle core 532-1 and the third middle core 533-1, A ceramic plate 541-1 between the third middle core 533-1 and the fourth middle core 534-1, and between the upper ferrite core 520-1 and the fourth middle core 534-1, respectively. 542-1, 543-1, 544-1, 545-1) are interposed and stacked to fill the magnetic gap without an air gap. The cross sections of the ceramic plates (541-1, 542-1, 543-1, 544-1, and 545-1) and the cross sections of the middle cores (531-1, 532-1, 533-1, and 534-1) are ferrite cores. It is substantially the same as the shape of the surface of the central foot of (510-1, 520-1), and the thickness and middle of the ceramic plates (541-1, 542-1, 543-1, 544-1, 545-1) The thickness of the cores 531-1, 532-1, 533-1, and 534-1 may be determined according to the specifications of the required transformer product, but in the embodiments of FIGS. 5 and 6, the ceramic plates 541-1, The thickness of the middle cores (542-1, 543-1, 544-1, and 545-1) is about 1 mm each, and the thickness of the middle cores (531-1, 532-1, 533-1, and 534-1) is about 5 mm each. The number of middle cores in each laminate can be one or more, and in one embodiment, four middle cores and five ceramic plates are used.

Ceramic plates (541-1, 542-1, 543-1, 544-1, 545-1) are made of alumina (Al ₂ O ₃ ), aluminum nitride (AlN), or magnesium oxide, which have higher permeability than air and excellent thermal conductivity. The fringing effect can be reduced compared to the case of an air gap by inserting a ceramic plate that is made of (MgO) and has a higher magnetic permeability than air. As in one embodiment, the thickness of the five ceramic plates is a total of 5 mm, so the gap is 5 mm at a time. Compared to the case of , the fringing effect is dispersed into 5 parts, which can ultimately reduce the fringing effect, and the heat from the core and winding can be easily dissipated due to excellent thermal conductivity.

As shown in FIG. 6, in the resonance inductor assembly 500, adjacent resonance inductor stacks 501 and 502 are spaced apart from each other by a distance d2 from the upper surface to the lower surface of the resonance inductor assembly 500. The length of the gap d2 may be determined depending on the specifications of the required transformer product, but is approximately 1 mm in the embodiments of FIGS. 5 and 6.

In the resonant inductor assembly 500, like the transformer core assembly 300, the resonant inductor stacks 501 and 502 are spaced apart from each other by the distance d2, so the magnetic field formed in the core is not blocked by the presence of the distance d2, thereby causing resonance. In addition to not adversely affecting inductor performance, the gap d2 serves as a heat dissipation passage through which heat generated in the ferrite core, middle core, ceramic plate, and winding can be dissipated to the outside from the upper and lower surfaces of the resonance inductor assembly 500. . In particular, one side of the ceramic plate made of alumina (Al ₂ O3), aluminum nitride (AlN), or magnesium oxide (MgO), which has excellent thermal conductivity, is exposed to the gap d2, so heat is released through the ceramic plate to the outside via the gap d2. Since it can be easily dissipated, heat dissipation of the resonance inductor assembly 500 becomes easy even when a magnetic gap is formed by the combination of the spacing d2 and the ceramic play. In addition, as explained below, the space of the resonance inductor assembly 500 including the gap d2 is filled with heat dissipating molding fluid while removing air through a separate process, making it easier to dissipate heat to the outside through the gap d2. I do it. If the capacity of the core of the resonant inductor is sufficient according to the specifications of the required transformer product, a general resonant inductor with a completely closed circuit without a magnetic gap or spacing d2 can be used.

7 to 10, a resonant converter transformer according to an embodiment of the present invention will be described. Figure 7 is a cross-sectional view of a winding wound around a resonant converter transformer according to an embodiment of the present invention, Figure 8 is an assembly diagram of a resonant converter transformer according to an embodiment of the present invention assembled in a case, and Figure 9 is a view of a resonant converter transformer according to an embodiment of the present invention. 10 is an isometric view of a resonant converter transformer according to an embodiment of the present invention mounted in a case, with the case top plate removed, and FIG. This is a product photo of a resonant converter transformer.

A bobbin 720 is commonly inserted into the central foot portion of the transformer core assembly 300, and a bobbin 710 is commonly inserted into the central foot portion of the resonant inductor assembly 500 and wound on the winding 730 to form the transformer core assembly ( 300 and the resonance inductor core assembly 500 are connected in series (750) to form a resonance converter transformer (700). The distance d3 between the series-connected transformer core assembly 300 and the resonant inductor core assembly 500 is not particularly limited as long as the series connection is guaranteed and may be determined depending on product implementation.

The resonant converter transformer 700 with the winding wound is connected to the bottom of the metal case 800 with thermal interface material (TIM) plates 810 and 820 disposed at the lower portions of the transformer core assembly 300 and the resonance inductor assembly 500, respectively. The resonant converter transformer 700 is placed inside the metal case 800 by being placed on the plate 850a. The metal case 800 has a lower plate 850a, an upper plate 850b, and four side plates 860a, 860b, 870a, and 870b, and a lower plate 850a, an upper plate 850b, and a side plate ( A heat sink structure 890 may be formed on 870a and 870b). The metal case 800 can be closed by being coupled by conventional means such as a connecting rod 830, a connecting hole 880, and a screw. In FIGS. 8 and 9, the top plate 850b is removed for convenience of illustration. .

The resonant converter transformer 700 injects heat dissipating molding fluid into the metal case 800 disposed inside to remove air, while removing the gap d1 within the transformer core assembly 300, the gap d2 within the resonance inductor assembly 500, and the resonance inductor. The space inside the metal case 800, including the gap d3 between the assembly 300 and the transformer core assembly 500, and the space between the windings 730, is filled, dried, and cured to produce the final resonant converter transformer product 900. get

The heat dissipating molding liquid may contain at least one polymer such as epoxy, silicone, urethane, etc., and may include alumina, aluminum hydroxide (Al(OH) ₃ , ATH) , BN (Boron nitride), and the like, and may be formed to include a mixture of a heat-resistant polymer and a heat-conductive filler. Heat dissipating molding fluid has low thermal conductivity of 1~5 W/mK and low viscosity of less than 20,000 cPoise.

Since the heat dissipating molding liquid has low thermal conductivity and low viscosity, there is a gap d1 within the transformer core assembly 300, a gap d2 within the resonance inductor assembly 500, a gap d3 between the resonance inductor assembly 300 and the transformer core assembly 500, and The space inside the metal case 800, including the space between the windings 730, can be efficiently filled, and the gap d1 within the transformer core assembly 300 molded with the heat dissipating molding fluid, and the gap d2 within the resonant inductor assembly 500 , the gap d3 between the resonant inductor assembly 300 and the transformer core assembly 500, and the space between the windings 730, heat is dissipated through the upper and lower plates 850a and 850b on which the heat sink structure 890 is formed. ensures efficient release.

Next, with reference to FIG. 11, a method of manufacturing a resonant converter transformer according to an embodiment of the present invention will be described.

In step S110, one or more middle cores sandwiched between ceramic plates are disposed within the magnetic gap of the ferrite core having a magnetic gap to form a transformer core laminate, and the laminate is arranged in a plurality of magnetic paths so that the magnetic paths are parallel to each other and spaced apart from each other by a distance d1. Arranged in parallel to form a transformer core assembly 300.

In step S120, one or more middle cores sandwiched between ceramic plates are disposed within the magnetic gap of the ferrite core having a magnetic gap to form a resonance inductor core stack, and the stack is arranged so that the magnetic paths are parallel to each other and spaced apart from each other by a distance d2. A plurality of resonance inductors are arranged in parallel to form a resonance inductor assembly 500.

The transformer core assembly 300 is made by stacking E-type ferrite cores 310-1 and 320-1 with a short center foot up and down to form a magnetic gap, and includes a middle core 331-1 sandwiched between ceramic plates within the magnetic gap. It has a first transformer core stack 301 in which one or more 342-1) are disposed, and a plurality of second to fourth transformer core stacks 302, 303, 304 configured in the same manner, the transformer core stack The transformer core assembly 300 is formed by arranging the bodies 301, 302, 303, and 304 in parallel so that the magnetic paths are parallel to each other and spaced apart from each other by a distance d1, and the transformer core assembly 300 is a transformer having magnetic paths parallel to each other. The core stacks 301, 302, 303, and 304 are formed to be spaced apart from each other by a distance d1.

In step S130, the winding 730 is wound around the resonance inductor assembly 500 and the transformer core assembly 300 to form a resonance converter transformer 700 in which the resonance inductor assembly 500 and the transformer core assembly 300 are connected in series. .

The resonance inductor assembly 500 is made by stacking E-type ferrite cores 510-1 and 520-1 with a short center foot up and down to form a magnetic gap, and includes a middle core 531-1 sandwiched between ceramic plates within the magnetic gap. , 532-1, 533-1, and 534-1), and has a first resonance inductor stack 501 in which one or more (532-1, 533-1, 534-1) are disposed, and a second resonance inductor stack 502 configured in the same manner. The resonance inductor assembly 500 is formed by arranging the magnetic paths 501 and 502 in parallel so that the magnetic paths are parallel to each other and spaced apart from each other by a distance d2. In the resonance inductor assembly 500, the resonance inductor stacks 501 and 502 are spaced apart from each other by a distance d2. They are formed to be spaced apart from each other as much as possible.

In step S140, the resonant converter transformer 700 is placed inside the metal case 800 with thermal interface material plates 810 and 820 disposed below the resonant inductor assembly 500 and the transformer core assembly 300, respectively. do.

A bobbin 720 is commonly inserted into the central foot portion of the transformer core assembly 300, and a bobbin 710 is commonly inserted into the central foot portion of the resonant inductor assembly 500 and wound on the winding 730 to form the transformer core assembly ( 300) and the resonance inductor core assembly 500 are connected in series (750) to form a resonance type converter transformer 700, and the resonance type converter transformer 700 with a winding is connected to the transformer core assembly 300 and the resonance inductor assembly 500. ) is disposed on the bottom plate 850a of the metal case 800 with thermal interface material (TIM) plates 810 and 820 at the bottom, respectively, to form a resonant converter transformer 700 inside the metal case 800. is placed.

In step S150, air is removed by injecting a heat dissipating molding liquid into the metal case 800 in which the resonant converter transformer 700 is disposed, and the gap d1 within the transformer core assembly 300 and the gap within the resonance inductor assembly 500 are formed. The space inside the metal case 800, including d2, the gap d3 between the resonant inductor assembly 500 and the transformer core assembly 300, and the gap between the windings 730, is filled, dried, and hardened to finally form a resonant converter transformer. Obtain product (900).

The drying may be performed at 60°C to 100°C for 30 to 90 minutes, and the heat dissipating molding liquid may have a low thermal conductivity of 1 to 5 W/mK and a low viscosity of 20,000 cPoise or less.

Experiment example

A resonant converter transformer product 900 according to an embodiment of the present invention manufactured according to the manufacturing method of FIG. 11 was prepared. The performance values for the resonant converter transformer product 900 are shown in [Table 1] below.

V _{in nom} 650~800 (V) V _{out nom} 200~1000 (V) I _{out_max} ~50 (A) P _out 30 (kW) f _sw 80~220 (kHz)

<Performance values of the resonant converter transformer product manufactured according to the experiment of the present invention>

FIG. 12 is a graph showing the results of measuring temperatures near the core and near the windings during operation of the prepared resonant converter transformer product 900. Using a thermocouple temperature sensor, the winding temperature near the inner winding adjacent to the core and the core temperature near the central foot adjacent to the winding were measured and recorded with a temperature recorder device.

As shown in the graph of FIG. 12, when the power was turned on at t0, the temperature increased from t1, and when the power was turned off at t2, the temperature near the core of the blue line maintained a stable temperature and fell at a maximum of about 97°C at t3. The temperature near the core of the blue line was about 85 ℃, and the temperature near the winding of the red line maintained a stable temperature, reaching a maximum of about 76 ℃ at t3, and the temperature dropped all the way to t4, and it took 1 hour from t0 to t4. It has been done.

As can be seen from this, in the resonant converter transformer product 900 according to an embodiment of the present invention, one or more middle cores interposed between ceramic plates are disposed within the magnetic gap of the ferrite core having a magnetic gap to form a transformer. A core laminate is formed, and the laminate forms a transformer core assembly 300 in which magnetic paths are parallel to each other and spaced apart from each other by a distance d1, and the ceramic plates are interposed within the magnetic gap of the ferrite core having a magnetic gap. A resonance inductor core stack is formed by arranging one or more middle cores, and a plurality of the stacks are arranged in parallel so that the magnetic paths are parallel to each other and spaced apart from each other by a distance d2 to form a resonance inductor assembly 500, and a resonance converter transformer is formed. While removing air by injecting a heat dissipating molding liquid into the metal case 800 placed inside (700), the gap d1 within the transformer core assembly 300, the gap d2 within the resonance inductor assembly 500, and the resonance inductor assembly 500 It has an excellent heat dissipation structure formed by filling, drying, and curing the space inside the metal case 800, including the gap d3 between the transformer core assembly 300 and the gap between the windings 730, and the maximum output current (I _out Even when a magnetic gap was formed when using a large current of 50A or less _(-max ), the ferrite transformer core showed excellent heat dissipation characteristics, with the operating temperature of the ferrite transformer core being up to approximately 97℃, stably lower than the normal operating temperature of 120℃ of the ferrite core. .

The description of the present invention described above is for illustrative purposes, and those skilled in the art will understand that the present invention can be easily modified into other specific forms without changing the technical idea or essential features of the present invention. will be. Therefore, the embodiments described above should be understood in all respects as illustrative and not restrictive.

The scope of the present invention is indicated by the patent claims described below, and all changes or modified forms derived from the meaning and scope of the claims and their equivalent concepts should be construed as being included in the scope of the present invention.

10: LLC resonant converter 11: Resonant inductor
12: resonant converter transformer 13: transformer
10a, 10b: Ferrite core 30: Air gap
40: magnetic flux 50: leakage magnetic flux
300: Transformer core assembly 301: First transformer core laminate
331-1: first middle core 341-1: first ceramic plate
310-1, 320-1: Ferrite core 500: Resonant inductor assembly
501: first resonance inductor assembly 531-1: first middle core
541-1: first ceramic plate 510-1, 520-1: ferrite core
700: Resonant converter transformer 710, 720: Bobbin
730: winding 800: metal case
810, 820: thermal interface material plate
830: connecting rod 880: connecting hole
890: Heat sink structure 900: Resonant converter transformer product

Claims (12)

A method of manufacturing a resonant converter transformer, comprising:
A transformer core laminate is formed by arranging one or more middle cores interposed between ceramic plates within the magnetic gap of a ferrite core having a magnetic gap, and a plurality of the laminates are arranged in parallel so that the magnetic paths are parallel to each other and spaced apart from each other by a distance d1 to form a transformer. forming a core assembly;
providing a resonant inductor;
Winding a winding around the resonance inductor and the transformer core assembly to form a resonance converter transformer in which the resonance inductor and the transformer core assembly are connected in series;
Placing the resonant converter transformer inside a metal case; and
A heat dissipating molding liquid having a low thermal conductivity of 1 to 5 W/mK is injected into the metal case in which the resonant converter transformer is disposed to remove air while removing the gap d1 within the transformer core assembly, the resonant inductor and the transformer. A method of manufacturing a resonant converter transformer, comprising the steps of filling, drying, and curing the space inside the metal case, including the gap d3 between core assemblies and the gap between windings. In claim 1,
The step of providing the resonance inductor includes:
A resonance inductor core laminate is formed by placing one or more middle cores interposed between ceramic plates within the magnetic gap of a ferrite core having a magnetic gap, and a plurality of the laminates are arranged in parallel so that the magnetic paths are parallel to each other and spaced apart from each other by a distance d2. It includes forming a resonant inductor assembly,
A method of manufacturing a resonant converter transformer, wherein the heat dissipating molding liquid fills the gap d2 in the resonant inductor assembly. In claim 2,
The step of placing the resonant converter transformer inside the metal case includes:
A method of manufacturing a resonant converter transformer, comprising the step of disposing the resonant converter transformer on a bottom plate of the metal case with a thermal interface material plate interposed between the resonant inductor assembly and the transformer core assembly. In claim 1,
The ferrite core of the transformer core assembly is formed by stacking E-type ferrite cores with a short center foot vertically to form a magnetic gap. In claim 1,
The ferrite core of the transformer core assembly is formed by vertically stacking an E-type core on one side and an E-type core or I-type core on the other side. In claim 1,
The transformer core laminate has a first middle core and a second middle core, between the lower ferrite core and the first middle core, between the first middle core and the second middle core, and between the upper ferrite core and the second middle core. A method of manufacturing a resonant converter transformer, wherein ceramic plates are interposed and stacked to fill the magnetic gap without an air gap. In claim 1 or claim 2,
The ceramic plate is made of alumina (Al ₂ O ₃ ), aluminum nitride (AlN), or magnesium oxide (MgO). In claim 1 or claim 2,
The heat dissipating molding liquid is a polymer containing at least one of epoxy, silicon, and urethane, alumina, aluminum hydroxide (Al(OH) ₃ , ATH), and BN ( A method of manufacturing a resonant converter transformer comprising a mixture of at least one thermally conductive filler of boron nitride. In claim 1 or claim 2,
A method of manufacturing a resonant converter transformer, wherein the heat dissipating molding liquid has a low viscosity of 20,000 cPoise or less. In claim 2,
The ferrite core of the resonant inductor assembly is formed by stacking E-type ferrite cores with a short central foot vertically to form a magnetic gap. In claim 10,
The resonance inductor laminate has first to fourth middle cores, between the lower ferrite core and the first middle core, between the first middle core and the second middle core, between the second middle core and the third middle core, and A method of manufacturing a resonant converter transformer, wherein a ceramic plate is interposed between the third middle core and the fourth middle core, and between the upper ferrite core and the fourth middle core, and is stacked to fill the magnetic gap without an air gap. In claim 1 or claim 2,
A method of manufacturing a resonant converter transformer, wherein the resonant converter transformer is for large currents with a maximum output current (I _out-max ) of 50A or less.