Transformer and LLC resonant converter comprising same
By designing a new winding structure in the transformer of the LLC resonant converter, increasing the winding window area and core thickness, the problem of excessive transformer volume is solved, and miniaturization and high power capacity are achieved.
Patent Information
- Application Number
- CN202280100606.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2022-09-28
- Publication Date
- 2025-05-13
AI Technical Summary
In the existing LLC resonant converters, transformers occupy a large volume and are difficult to meet the needs of high power capacity and miniaturization, especially in power supply devices for electronic equipment such as televisions.
By adding a winding frame design in the transformer, the winding area of the primary and secondary coils is guided by the outer side of the core, the winding area and core thickness are increased, the actual volume of the core is reduced, and the power capacity is increased.
The transformer is miniaturized, while improving the heating problem, generating stable leakage inductance, improving working stability, and increasing the power capacity without increasing the actual core volume.
Smart Images
Figure CN119998898A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a transformer and an LLC (Inductor-Inductor-Capacitor: inductor-inductor-capacitor) resonant converter comprising the transformer. Background Art
[0002] In order to achieve high efficiency and high power density, LLC resonant converters capable of performing ZVS (Zero Voltage Switching) operation are increasingly used in power supply devices.
[0003] Considering the characteristics of the control action IC and the switching device, the existing LLC resonant converter mainly adopts an operating frequency of 80 to 120 kHz.
[0004] However, as the resolution of televisions has developed towards 4K / 8K in recent years, the operating frequency has increased, and the power capacity of the power supply devices of such televisions has also increased. Therefore, if the traditional design method is used, there will be a problem of increased size. Summary of the invention
[0005] Problems to be solved by the invention
[0006] An object of the present invention is to provide a solution for miniaturizing a transformer that occupies a relatively large volume in an LLC resonant converter.
[0007] Technical solutions to the problem
[0008] The LLC resonant converter of an embodiment of the present invention may include: a square wave generator; a resonant circuit, composed of a resonant capacitor, a resonant inductor and a transformer; and a rectifier circuit, the transformer may include: a winding frame; a primary coil, wound on the winding frame; a secondary coil, wound on the winding frame; and a core body, including an upper core member and a lower core member, the upper core member and the lower core member are combined around the primary coil and the secondary coil; the winding frame may include a first winding frame structure and a second winding frame structure, the first winding frame structure and the second winding frame structure guide the winding area of the primary coil and the secondary coil on the outside of the core body.
[0009] The transformer of an embodiment of the present invention may include: a winding frame; a primary coil, wound on the winding frame; a secondary coil, wound on the winding frame; and a core body, including an upper core member and a lower core member, the upper core member and the lower core member are combined around the primary coil and the secondary coil, the winding frame includes a first winding frame structure and a second winding frame structure, the first winding frame structure and the second winding frame structure guide the winding area of the primary coil and the secondary coil on the outside of the core body.
[0010] The upper core member and the lower core member may be assembled between the first bobbin member and the second bobbin member.
[0011] The first bobbin structure and the second bobbin structure may guide the primary coil and the secondary coil arranged between the upper core member and the lower core member to be arranged straightly.
[0012] The primary coil and the secondary coil may be arranged to be spaced apart from each other by a predetermined distance or more.
[0013] The secondary coil may include: a straight winding portion arranged straight; and a connection portion extending from the straight winding portion and immersed in the power board.
[0014] The connection portion includes at least a first connection portion and a second connection portion, and the length of the first connection portion may be different from the length of the second connection portion.
[0015] Either the first connection portion or the second connection portion may be connected closer to the rectifier circuit than the other connection portion.
[0016] The transformer may further include a heat sink disposed between the other connection portion and the rectifier circuit.
[0017] Only the primary coil and the secondary coil may be arranged between the upper core member and the lower core member.
[0018] Effects of the Invention
[0019] According to an embodiment of the present invention, the winding frame is composed of a first winding frame structure and a second winding frame structure for guiding the winding areas of the primary coil and the secondary coil on the outside of the core body, thereby having the advantages of improving the heat generation problem by increasing the winding window area in the core body, and increasing the power capacity without increasing the actual volume of the core body by increasing the thickness of the core body.
[0020] According to the embodiment of the present invention, the primary coil and the secondary coil are spaced apart and arranged in a straight line, thereby having the advantage of being able to generate a stable leakage inductance.
[0021] According to the embodiment of the present invention, the connection portion of the secondary coil connected to the power board is arranged close to the rectifier circuit to minimize the leakage inductance component caused by the PCB pattern, thereby having the advantage of improving the working stability.
[0022] According to the embodiment of the present invention, by making the length of the connection portion of the secondary coil connected to the power board different, there is an advantage that components such as a heat sink can be added. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] Figure 1 is a circuit diagram showing one example of a power supply device including an LLC resonant converter.
[0024] Figure 2 is a cross-sectional view of an existing transformer.
[0025] Figure 3 1 is a top view showing a winding frame of a conventional transformer.
[0026] Figure 4 is a cross-sectional view of a transformer according to an embodiment of the present invention.
[0027] Figure 5 It is a diagram showing a winding frame of a transformer according to an embodiment of the present invention.
[0028] Figure 6 The primary coil and the secondary coil are shown wound on Figure 5 Figure showing the situation of the winding rack.
[0029] Figure 7 1 is a diagram showing an example of a state in which the secondary coil of the transformer according to the first embodiment of the present invention is connected to a power board.
[0030] Figure 8 1 is a diagram showing an example of a state in which a secondary coil of a transformer according to a second embodiment of the present invention is connected to a power board. DETAILED DESCRIPTION
[0031] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the accompanying drawings, the same reference numerals refer to the same or similar components.
[0032] The suffixes "module" and "unit" used in the following description for the constituent elements are only given or used interchangeably in consideration of the convenience of writing the specification, and they themselves do not have meanings or functions that distinguish one from another.
[0033] In the following description, unless explicitly stated otherwise, “connection” between constituent elements includes not only direct connection between the constituent elements but also indirect connection through at least one other constituent element.
[0034] Various electronic devices such as televisions include power supply devices, and such power supply devices may use an LLC topology. That is, an LLC resonant converter may be used in the power supply device.
[0035] Figure 1 is a circuit diagram showing one example of a power supply device including an LLC resonant converter.
[0036] Reference Figure 1 The LLC resonant converter 1 may include a square wave generator 10 , a resonant circuit 20 , and a rectifying circuit 40 .
[0037] The square wave generator 10 includes a plurality of switch elements, which can be turned on alternately to generate a square wave voltage.
[0038] The resonant circuit 20 is composed of a resonant capacitor, a resonant inductor and a transformer 30, and can filter out high-order harmonic currents. That is, even if a square wave voltage is applied, the resonant circuit 20 can only allow a sinusoidal wave current to flow.
[0039] The resonance circuit 20 includes a transformer 30, which is a device that changes the value of an AC voltage or current using an electromagnetic induction phenomenon.
[0040] The rectifier circuit 40 includes a rectifier diode and a capacitor, and these components can be used to rectify the AC current to generate a DC voltage. According to an embodiment, the rectifier circuit 40 can be a SR (Synchronous Rectifier) circuit, but this is only an example and should not be limited thereto.
[0041] The square wave generator 10 and the rectifier circuit 40 are only examples, and thus other circuits may also be used. Figure 1 Configurations other than those shown.
[0042] On the other hand, if the load of the electronic device increases, the power capacity of the power supply device increases, which may cause the size of the power supply device to increase. Therefore, an object of the present invention is to provide a solution for miniaturizing the transformer 30 that occupies a large volume in the power supply device.
[0043] According to an embodiment, the present invention can provide a miniaturized transformer 30 by increasing the operating frequency of the LLC resonant converter 1 .
[0044] Specifically, if the resonant frequency of the LLC resonant converter 1 increases, the peak current decreases, thereby reducing the magnetizing inductance (Lm) of the transformer 30. Therefore, the number of turns of the core and the primary and secondary coils can be reduced, thereby reducing the size of the transformer 30. For example, when the resonant frequency of the LLC resonant converter 1 increases from 100kHz to 250kHz, the magnetizing inductance (Lm) decreases from 210uH to 100uH, thereby reducing the primary coil from 24 turns to 12 turns and the secondary coil from 2 turns to 1 turn, thereby reducing the size of the transformer 30.
[0045] On the other hand, in the prior art, the LLC resonant converter 1 is usually configured with a plurality of transformers. The present invention aims to reduce the size of the transformer 30 by implementing a plurality of transformers into one transformer 30. For example, in the prior art, three transformers with effective cross-sectional areas (Ae: Effective cross-sectional area) of the core are used, respectively, and the present invention aims to implement it as a transformer with an effective cross-sectional area of 450. However, in this case, the problem of a smaller winding window area may occur, resulting in heating of the primary coil and the secondary coil. In addition, if only the size of an existing core and a core proposed by the present invention is compared, the size of the core will increase, so there is a hidden danger of cracking or bending. Therefore, the present invention aims to propose a solution that can increase the winding window area while minimizing the increase in the volume of the core itself. According to one embodiment, by removing the winding frame in the winding window area, the actual winding window area is increased while minimizing the increase in the volume of the core itself. Before explaining this point, the structure of the existing transformer is first explained.
[0046] Figure 2 is a cross-sectional view of an existing transformer. Figure 3 It is a figure which shows the winding frame of a conventional transformer.
[0047] The conventional transformer may include: a winding frame 300 ; a primary coil 32 and a secondary coil 33 wound on the winding frame 300 ; and a core 34 assembled on the winding frame 300 wound with the primary coil 32 and the secondary coil 33 .
[0048] The core 34 is made of ferrite and may include an upper core member 34a and a lower core member 34b having an E shape. The upper core member 34a and the lower core member 34b may be connected to the upper side and the lower side of the bobbin 10, respectively.
[0049] A hollow portion S1 where the upper core member 34a and the lower core member 34b are closely attached may be formed in the center of the bobbin 300. A first section bobbin 301 around which the primary coil 32 is wound may be formed around the hollow portion S1, and a second section bobbin 302 around which the secondary coil 33 is wound may be formed with a gap S2 between the first section bobbin 301 and the second section bobbin 302.
[0050] like Figure 2As shown in the cross-sectional view, on the inner side of the core 34, the first section winding frame 301 can surround the inner side, upper part and lower part of the primary coil 32, and the second section winding frame 302 can surround the inner side, upper part and lower part of the secondary coil 33. That is, according to the prior art, since at least a part of the winding frame 300 occupies the winding window area of the core 34, there is a problem that the heating problem is more serious, and there is a limitation that the size of the core 34 needs to be increased in order to increase the number of windings.
[0051] Therefore, the present invention aims to improve the heating problem by providing a transformer that removes the winding frame within the winding window area of the core 34, thereby ensuring the winding window area, and by increasing the thickness of the core 34 in the direction of the winding window area, increasing the power capacity while maintaining the actual volume of the core 34.
[0052] Figure 4 is a cross-sectional view of a transformer according to an embodiment of the present invention, Figure 5 1 is a diagram showing a winding frame of a transformer according to an embodiment of the present invention, Figure 6 The primary coil and the secondary coil are shown wound on Figure 5 Figure showing the situation of the winding rack.
[0053] The transformer 3000 of the embodiment of the present invention may include: a winding frame 100 ; a primary coil 32 wound on the winding frame 100 ; a secondary coil 33 wound on the winding frame 100 ; and a core 34 .
[0054] The core body 34 may include an upper core member 34a and a lower core member 34b coupled to the periphery of the primary coil 32 and the secondary coil 33. That is, the upper core member 34a and the lower core member 34b may be respectively assembled on the upper side and the lower side of the primary coil 32 and the secondary coil 33. Only the primary coil 32 and the secondary coil 33 may be disposed between the upper core member 34a and the lower core member 34b.
[0055] The bobbin 100 may include a first bobbin member 101 and a second bobbin member 102 that guide the winding area of the primary coil 32 and the secondary coil 33 outside the core 34. That is, the core 34 may be disposed between the first bobbin member 101 and the second bobbin member 102. An upper core member 34a and a lower core member 34b may be assembled between the first bobbin member 101 and the second bobbin member 102.
[0056] The first winding frame structure 101 and the second winding frame structure 102 can guide the winding area of the primary coil 32 and the secondary coil 33, respectively. For example, the first winding frame structure 101 and the second winding frame structure 102 can both be formed with a groove (not shown) or a partition wall (not shown) for guiding the winding area of the primary coil 32 and the winding area of the secondary coil 33, but this is only an example and should not be limited to this. That is, the first winding frame structure 101 and the second winding frame structure 102 can be formed with a groove (not shown) or a partition wall (not shown) as described later, so that the primary coil 32 and the secondary coil 33 are arranged straight or separated by a predetermined distance.
[0057] In particular, the first bobbin structure 101 and the second bobbin structure 102 can guide the primary coil 32 and the secondary coil 33 disposed inside the core body 34, that is, between the upper core member 34a and the lower core member 34b, to be disposed straightly. Figure 6 It can be confirmed that the primary coil 32 and the secondary coil 33 are arranged flat along the y direction.
[0058] In addition, the first winding frame structure 101 and the second winding frame structure 102 can guide the area where the primary coil 32 and the secondary coil 33 are wound so that the primary coil 32 and the secondary coil 33 are arranged at a predetermined distance or more. That is, if the primary coil 32 and the secondary coil 33 are wound along a groove (not shown) or a partition wall (not shown) formed in the first winding frame structure 101 and the second winding frame structure 102, the primary coil 32 and the secondary coil 33 can be arranged at a predetermined distance or more. Figure 4 and Figure 6 As shown, a gap S3 may be formed between the primary coil 32 and the secondary coil 33 .
[0059] As described above, according to the embodiment of the present invention, even without a segmented bobbin, the primary coil 32 and the secondary coil 33 are separated by a predetermined distance or more, so leakage inductance can be generated, and since the primary coil 32 and the secondary coil 33 are arranged in a straight line, the separation distance between the primary coil 32 and the secondary coil 33 is not fixed, thereby having the advantage of minimizing the problem of variable leakage inductance. That is, the primary coil 32 and the secondary coil 33 are guided to be separated by a predetermined distance and arranged in a straight line by the first bobbin structure 101 and the second bobbin structure 102 arranged outside the core body 34, thereby having the advantage of being able to generate a stable leakage inductance.
[0060] On the other hand, the first bobbin structure 101 and the second bobbin structure 102 may be formed as a structure in which a lower plate portion 1010 and an upper plate portion 1020 are combined, respectively. However, this is only an example and should not be limited thereto.
[0061] The primary coil 32 may be arranged straight between the first bobbin structure 101 and the second bobbin structure 102, and may be arranged in a bent shape on the first bobbin structure 101 and the second bobbin structure 102. The primary coil 32 may be arranged straight between the upper core member 34a and the lower core member 34b, and may be arranged in a bent shape along a semicircle on the first bobbin structure 101 and the second bobbin structure 102.
[0062] The secondary coil 33 may be arranged straight between the first bobbin member 101 and the second bobbin member 102. The secondary coil 33 may be arranged straight between the upper core member 34a and the lower core member 34b. The straightly arranged portion of the secondary coil 33 may be referred to as a straight winding portion 331, but such a name is only an example for convenience of explanation and is not limited thereto.
[0063] Furthermore, the secondary coil 33 disposed on the first bobbin structure 101 may be disposed in a curved shape. For example, the secondary coil 33 may be disposed along a semicircular shape on the first bobbin structure 101. The secondary coil 33 disposed on the first bobbin structure 101 may be a curved portion (not shown) connecting the straight winding portions 331 located on both sides of the primary coil 32.
[0064] The secondary coil 33 disposed on the second winding frame structure 102 may be connected to the power board 500 (see Figure 7 That is, the connecting portion 332 may extend from the straight winding portion 331 and be dipped into the power board 500 (refer to Figure 7 ).
[0065] That is, the secondary coil 33 may include a straight winding portion 331 arranged in a straight manner, a bent portion (not shown) between the straight winding portions 331, and a curved portion extending from the straight winding portion 331 and connected to the power board 500 (see Figure 7 ) at least one of the connection portions 332 connected.
[0066] Next, refer to Figure 7 and Figure 8 , a situation in which the secondary coil of the transformer in an embodiment of the present invention is connected to a power board is described.
[0067] Figure 7 is an exemplary diagram showing a situation where the secondary coil of the transformer according to the first embodiment of the present invention is connected to a power board, Figure 8 1 is a diagram showing an example of a state in which a secondary coil of a transformer according to a second embodiment of the present invention is connected to a power board.
[0068] exist Figure 7 and Figure 8 In the figure, the winding frame 100 is not shown for the convenience of explanation, but this is only for the convenience of explanation and is not limited to this.
[0069] First, the connection portion 332 of the secondary coil 33 may include a first connection portion 332a and a second connection portion 332b. Either of the first connection portion 332a and the second connection portion 332b may be one end of the secondary coil 33, and the other may be the other end of the secondary coil 33. That is, the first connection portion 332a may be an end of either side of the secondary coil 33, and the second connection portion 332b may be an end of the other side of the secondary coil 33.
[0070] exist Figure 7 and Figure 8 In the example of FIG. 1 , the secondary coil 33 is formed into two layers (2-layer) respectively arranged in the upper layer and the lower layer, that is, the first connection part 332a and the second connection part 332b corresponding to the secondary coil 33 arranged in the upper layer and the first connection part 332a and the second connection part 332b corresponding to the secondary coil 33 arranged in the lower layer are shown. That is, in Figure 7 and Figure 8 In the example, two first connection parts 332a and two second connection parts 332b are shown respectively, but this is only an example and should not be limited to this.
[0071] The first connection portion 332a and the second connection portion 332b may be connected to the power board 500 by welding or the like. The power board 500 may be formed with an impregnation area 501 connected to the first connection portion 332a and the second connection portion 332b.
[0072] According to one embodiment, when the first connection portion 332a and the second connection portion 332b are immersed in the power board 500, the plurality of coils can be immersed together. That is, in the prior art, each secondary coil 33 is welded to a pin to be fastened to the PCB, but in this case, unwelded parts are generated, resulting in heating problems, and there is a disadvantage of increased contact resistance. Therefore, according to one embodiment of the present invention, the secondary coil 33 is directly immersed in the PCB in the form of straight winding, thereby minimizing the generation of unwelded parts and minimizing the contact resistance problem.
[0073] On the other hand, at least one of the first connection portion 332a and the second connection portion 332b can be connected to the power board 500 adjacent to the rectifier circuit 40. The rectifier circuit 40 works by sensing the voltage passing through the PCB pattern in the output of the transformer 3000, so the PCB pattern may induce an inductance component, which affects the sensing of the rectifier circuit 40 and causes unstable operation. Therefore, by configuring at least one of the first connection portion 332a and the second connection portion 332b adjacent to the rectifier circuit 40, the leakage inductance component caused by the PCB pattern can be minimized, and the working stability can be improved.
[0074] According to the first embodiment, Figure 7 As shown, the first connection portion 332a and the second connection portion 332b may be disposed adjacent to the rectifier circuit 40. That is, the first connection portion 332a and the second connection portion 332b may be immersed in the power board 500 and the distance between them and the rectifier circuit 40 may be minimized.
[0075] According to the second embodiment, Figure 8 As shown, only one of the first connection portion 332a and the second connection portion 332b may be arranged adjacent to the rectifier circuit 40. That is, the length of the first connection portion 332a and the length of the second connection portion 332b may be different. Either one of the first connection portion 332a and the second connection portion 332b may be connected closer to the rectifier circuit 40 than the other.
[0076] Specifically, first, when observing the secondary coil 33 disposed in the upper layer, it can be confirmed that the length d1 of the second connection portion 332b is longer than the length d2 of the first connection portion 332a. That is, it can be confirmed that, in the case of the secondary coil 33 disposed in the upper layer, the second connection portion 332b is connected to the impregnated area 501 of the power board 500 closer to the rectifier circuit 40 than the first connection portion 332a is connected to the impregnated area 501 of the power board 500.
[0077] By observing the secondary coil 33 disposed in the lower layer, it can be confirmed that the length d1 of the first connection portion 332a is longer than the length d2 of the second connection portion 332b. In other words, it can be confirmed that, in the case of the secondary coil 33 disposed in the lower layer, the first connection portion 332a connected to the impregnated area 501 of the power board 500 is closer to the rectifier circuit 40 than the second connection portion 332b connected to the impregnated area 501 of the power board 500.
[0078] As described above, when only one of the first connection portion 332a and the second connection portion 332b is arranged close to the rectifier circuit 40, there is an advantage that a component can be added to the space between the other connection portion and the rectifier circuit 40. Figure 8 In the example of FIG. 3 , when only one of the first connection portion 332a and the second connection portion 332b is arranged close to the rectifier circuit 40, the transformer 3000 may further include a heat dissipation portion 400 arranged between the other connection portion and the rectifier circuit 40. This has the advantage of being able to improve the heat dissipation effect on the output of the secondary coil 33.
[0079] The above description is merely an exemplary description of the technical concept of the present invention. For those skilled in the art to which the present invention belongs, various modifications and variations can be made without departing from the essential features of the present invention.
[0080] Therefore, the embodiments disclosed in the present invention are not intended to limit the technical concept of the present invention but to explain the present invention, and the scope of the technical concept of the present invention is not limited to such embodiments.
[0081] The protection scope of the present invention should be interpreted by the claims, and should be interpreted as that all technical ideas within the equivalent scope thereof fall within the protection scope of the present invention.
Claims
1. A transformer, wherein: include: Winding rack; A primary coil, wound on the winding frame; A secondary coil, wound on the winding frame; as well as a core body including an upper core member and a lower core member, the upper core member and the lower core member being combined around the primary coil and the secondary coil; The bobbin includes a first bobbin member and a second bobbin member that guide winding regions of the primary coil and the secondary coil at an outer side of the core.
2. The transformer according to claim 1, wherein: The upper core member and the lower core member are assembled between the first bobbin member and the second bobbin member.
3. The transformer according to claim 1, wherein: The first bobbin member and the second bobbin member guide the primary coil and the secondary coil arranged between the upper core member and the lower core member so as to be arranged straightly.
4. The transformer according to claim 3, wherein: The primary coil and the secondary coil are arranged to be spaced apart from each other by a predetermined distance or more.
5. The transformer according to claim 1, wherein: The secondary coil comprises: A straight winding portion, in a straight configuration; and The connecting portion extends from the straight winding portion and is immersed in the power board.
6. The transformer according to claim 5, wherein: The connecting portion at least includes a first connecting portion and a second connecting portion; The length of the first connection portion is different from the length of the second connection portion.
7. The transformer according to claim 6, wherein: One of the first connection portion and the second connection portion is connected closer to the rectifier circuit than the other connection portion.
8. The transformer according to claim 7, wherein: It also includes a heat dissipation portion arranged between the other connection portion and the rectifier circuit.
9. The transformer according to claim 1, wherein: Only the primary coil and the secondary coil are arranged between the upper core member and the lower core member.
10. An LLC resonant converter, wherein: include: Square wave generator; A resonant circuit, composed of a resonant capacitor, a resonant inductor and a transformer; as well as Rectification circuit; The transformer comprises: Winding rack; A primary coil, wound on the winding frame; a secondary coil, wound on the winding frame; and a core body including an upper core member and a lower core member, the upper core member and the lower core member being combined around the primary coil and the secondary coil; The bobbin includes a first bobbin member and a second bobbin member that guide winding regions of the primary coil and the secondary coil at an outer side of the core.