A combined magnetic core having three magnetic flux loops and a three-port transformer thereof

Abstract

This invention discloses a combined magnetic core with three flux loops and its three-port transformer, relating to the field of high-frequency transformer technology in power electronic current converters. The combined magnetic core with three flux loops comprises multiple core blocks combined to form three flux loops. The three flux loops include a decoupled flux loop, a coupled flux loop, and a closed flux loop, with the length of the coupled flux loop being greater than the length of the decoupled flux loop. By controlling the length of the flux loops and the size of the window area formed by the flux loops, a deeply integrated three-port transformer is achieved. Simultaneously, by controlling the distance between the third winding and the gap, leakage flux cutting of the third winding is avoided. Through these measures, deep integration of magnetic components is achieved, reducing raw material costs and shrinking the size; furthermore, the transformer winding is prevented from being cut by leakage flux, improving the conversion efficiency of the current converter.

Description

Technical Field

[0001] This invention relates to the field of high-frequency transformer technology in current converters for power electronics, and more particularly to a combined magnetic core with three flux loops and its three-port transformer. Background Technology

[0002] As the industry places increasingly higher demands on the energy efficiency, power density, and cost of switching power supply products, power electronics engineers need to start with the selection of power supply product topology, magnetic component design, and semiconductor packaging type when developing and designing power supply products. Among these, magnetic component design, as one of the core components of power supply products, determines the power density, energy efficiency, and cost to a certain extent. For example, data center rack power supplies, flash charging or supercharging rack power supplies, and on-board chargers (AC-DC) and on-board DC-DC products convert AC grid power into DC power, which is then used to charge batteries for storage or directly supply DC loads, or convert DC power to DC power of another voltage level.

[0003] In existing isolated AC-DC and DC-DC power converter technologies, the isolation transformer in the isolated topology is usually equipped with a resonant inductor with matched parameters to achieve a maximum range of soft switching, thereby reducing the losses of the switching transistors and improving conversion efficiency. There are two common practices in the industry: one is to wind the isolation transformer and resonant inductor separately, with no magnetic coupling between them. However, this method results in a larger size and requires more copper and core materials, which is not conducive to improving power density. The other method uses cores such as ER / EE / EQ, which must be wound within the winding coil, to deeply magnetically integrate the isolation transformer and resonant inductor. The resonant inductor is generated using the leakage inductance of the transformer's primary and secondary windings. The advantage of this method is that the leakage inductance is easier to control and does not diffuse to the surrounding areas of the transformer body. However, the disadvantage is that heat is concentrated too much in the inner conductors of the transformer windings, and the leakage flux cuts the internal conductors of the transformer, leading to varying degrees of eddy current losses, exacerbating the heating of the transformer winding conductors, and hindering heat dissipation from the inner conductors of the transformer windings. Therefore, in engineering, it is usually necessary to reserve air ducts for the magnetic core for heat dissipation or use vacuum-sealed thermally conductive potting compound. The purpose is to fully fill the air gaps in the inner winding conductors of the transformer with thermally conductive compound to achieve the best heat conduction effect. However, reserving air ducts further increases the size of the device, which is not conducive to improving power density. The process of injecting thermally conductive compound during vacuuming is complicated and increases manufacturing costs.

[0004] In summary, when the resonant inductance in the current converter circuit is generated by the leakage inductance between the two windings of the transformer, and the power system requires the transformer winding conductors to be externally wound for better heat dissipation, these two technical challenges are constrained by factors such as the heat dissipation environment and leakage magnetic interference. If the current converter is a more highly integrated three-port network, then the corresponding isolation transformer should also be a three-port transformer, making the above technical difficulties even more prominent and limiting the realization of high power density in current converters to some extent. Therefore, the industry urgently needs to find a reasonable technical balance point to achieve deep magnetic integration to reduce size while maintaining good heat dissipation performance of the transformer winding conductors and maximizing conversion efficiency. Summary of the Invention

[0005] The purpose of this invention is to propose a combined magnetic core with three magnetic flux loops and its three-port transformer, aiming to solve the problems of existing transformers being unable to balance deep magnetic integration, size reduction, heat dissipation performance and conversion efficiency.

[0006] A composite magnetic core with three magnetic flux loops includes multiple magnetic core blocks, which are combined to form three magnetic flux loops. The three magnetic flux loops include a decoupling magnetic flux loop, a coupling magnetic flux loop, and a closed magnetic flux loop; The decoupling magnetic flux circuit includes a first magnetic circuit composed of at least one of the magnetic core blocks and a gap magnetic circuit composed of at least two of the magnetic core blocks, wherein the gap magnetic circuit has a gap. The coupled magnetic flux circuit and the decoupled magnetic flux circuit share the gap magnetic circuit. The coupled magnetic flux circuit includes a second magnetic circuit composed of at least one of the magnetic core blocks and the gap magnetic circuit. The first magnetic circuit and the second magnetic circuit are in contact with each other to form the closed magnetic flux loop, or the first magnetic circuit and the second magnetic circuit are respectively in contact with the gap magnetic circuit to form the closed magnetic flux loop; The length of the coupling magnetic flux loop is greater than the length of the decoupling magnetic flux loop; A decoupling window is formed between the first magnetic circuit and the gap magnetic circuit, and a coupling window is formed between the second magnetic circuit and the gap magnetic circuit. The area of ​​the coupling window is larger than the area of ​​the decoupling window. The decoupling window is used for a portion of the first winding coil to pass through, and the coupling window is used for a portion of the first winding coil, the second winding, and the third winding to pass through; The number of coil turns of the first winding passing through the coupling window is greater than the number of coil turns of the first winding passing through the decoupling window.

[0007] In one optional implementation of this application, the decoupling window, the gap, and the coupling window are arranged sequentially along a first direction, and the decoupling window and the coupling window are connected through the gap; The first magnetic circuit abuts against the first side of the gap magnetic circuit, and the second magnetic circuit abuts against the second side of the gap magnetic circuit. The first side and the second side of the gap magnetic circuit are two corresponding sides in the first direction.

[0008] In one optional implementation of this application, the area of ​​the effective magnetic flux cross-section of the first magnetic circuit is greater than or equal to the area of ​​the effective magnetic flux cross-section of the second magnetic circuit.

[0009] In one optional implementation of this application, the area of ​​the effective magnetic flux cross-section of the gap magnetic circuit is greater than or equal to the area of ​​the effective magnetic flux cross-section of the second magnetic circuit.

[0010] A three-port transformer includes the magnetic core described above, and also includes three transformer windings, namely a first winding, a second winding, and a third winding. The first winding includes a first decoupling coil, a second decoupling coil, and a first main coil. The first decoupling coil, the second decoupling coil, and the first main coil are wound from the same continuous wire. The first decoupling coil and the second decoupling coil are the two ends of the wire, and the first main coil is the middle part of the wire. The first decoupling coil and the second decoupling coil are arranged side by side in the decoupling window, and the first main coil, the second winding and the third winding are all arranged in the coupling window; The total number of turns of the first decoupling coil and the second decoupling coil is less than the number of turns of the first main coil.

[0011] In one optional implementation of this application, the first winding and the second winding are respectively wound with Litz wire with a diameter of less than 0.2 mm, the third winding is wound with copper foil, copper busbar or aluminum busbar, and the minimum distance between the third winding and the gap is not less than 2 mm.

[0012] In one optional implementation of this application, the first decoupling coil and the second decoupling coil are respectively wound on the first magnetic circuit, and the first main coil, the second winding and the third winding are jointly wound on the second magnetic circuit.

[0013] In one optional implementation of this application, the number of turns of the first winding and the number of turns of the second winding are both greater than the number of turns of the third winding.

[0014] In one optional implementation of this application, the number of turns of the first decoupling coil is the same as the number of turns of the second decoupling coil.

[0015] In one optional implementation of this application, the third winding is wound around the outer layer of the first main coil and the second winding.

[0016] The embodiments of the present invention have the following beneficial effects: In power electronic topology converter circuits where the resonant inductance is generated by the leakage inductance between the first and second windings of the transformer, a decoupling window is used for the first winding, and a coupling window is used for the first, second, and third windings. This allows for the use of externally wound transformer winding conductors, significantly improving both the thermal management of the transformer windings and the control of leakage flux between the first and second windings. It also achieves deep magnetic integration of the magnetic components, reducing their size and lowering raw material costs. By controlling the lengths of the decoupling and coupling flux loops, and the window areas formed by the decoupling and coupling flux loops respectively, the number of coil turns of the first winding passing through the coupling window and the number of coil turns of the first winding passing through the decoupling window are reasonably distributed to improve the area utilization of the decoupling and coupling windows, thereby compressing the size of the transformer core and maximizing the compression of the three-port transformer size and increasing the power density. Furthermore, by precisely controlling the minimum distance between the third winding and the gap, the third winding is prevented from being cut by leakage flux, thereby maximizing the reduction of eddy current losses and improving conversion efficiency. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] in: Figure 1 A top view of a combined magnetic core with three flux loops in one embodiment; Figure 2 A schematic diagram of a magnetic core block having a combined magnetic core with three magnetic flux loops in one embodiment; Figure 3 A schematic diagram of a magnetic core block having a combined magnetic core with three magnetic flux loops in another embodiment; Figure 4 A schematic diagram of a magnetic core block having a combined magnetic core with three magnetic flux loops in another embodiment; Figure 5 A schematic diagram of a magnetic core block with a combined magnetic core having three magnetic flux loops in other embodiments; Figure 6 This is a schematic diagram of the overall structure of a three-port transformer in one embodiment; Figure 7 This is a schematic diagram of the winding explosion of a three-port transformer in one embodiment; Figure 8 This is a schematic diagram showing the positional relationship between the gap and the third winding in a three-port transformer in one embodiment. Figure 9 This is a magnetic simulation diagram illustrating leakage flux control of a transformer with external windings in one embodiment. Figure 10 This is a magnetic simulation diagram of leakage flux control for a three-port transformer in one embodiment; Figure 11 This is a simulation diagram of a scenario where the third winding is close to the gap in one embodiment; Figure 12 This is a simulation diagram of a transformer in one embodiment, in which the resonant inductance is generated by the leakage inductance of the primary and secondary sides of the transformer. Figure 13 This is a schematic diagram of the equivalent circuit of a three-port transformer in one embodiment; Figure 14 This is a schematic diagram of the equivalent circuit of a three-port transformer in another embodiment.

[0019] Markings: 1. Decoupling flux circuit; 2. Coupled flux circuit; 3. Closed flux circuit; 4. First magnetic circuit; 5. Gap magnetic circuit; 51. Gap; 6. Second magnetic circuit; 7. Decoupling window; 8. Coupled window; 9. First winding; 91. First decoupling coil; 92. Second decoupling coil; 93. First main coil; 10. Second winding; 11. Third winding; 101. First side block; 102. First connecting post; 103. First intermediate block; 104. Second connecting post; 105. Second side block; 106. Third side block; 107. Third connecting post; 108. Second intermediate block; 109. Fourth connecting post; 110. Fourth side block. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] As the industry places increasingly higher demands on the energy efficiency, power density, and cost of switching power supply products, power electronics engineers need to start with the selection of power supply product topology, magnetic component design, and semiconductor packaging type when developing and designing power supply products. Among these, magnetic component design, as one of the core components of power supply products, determines the power density, energy efficiency, and cost to a certain extent. For example, data center rack power supplies, flash charging or supercharging rack power supplies, and on-board chargers (AC-DC) and on-board DC-DC products convert AC grid power into DC power, which is then used to charge batteries for storage or directly supply DC loads, or convert DC power to DC power of another voltage level.

[0022] In existing isolated AC-DC and DC-DC power converter technologies, the isolation transformer in the isolated topology typically incorporates a resonant inductor with matched parameters to achieve maximum soft switching range, thereby reducing switching transistor losses and improving conversion efficiency. Currently, the industry commonly uses a core with in-coil windings for three-port isolation transformers, achieving deep magnetic integration of the isolation transformer and resonant inductor. However, this requires reserving airflow for heat dissipation, increasing the device size. Therefore, this application provides a combined magnetic core with three flux loops, aiming to solve the technical problem of the current large core size.

[0023] Next, we will further describe a combined magnetic core with three magnetic flux loops provided in the embodiments of this application. For example... Figure 1 The image shown is a top view of a combined magnetic core with three magnetic flux loops provided in this embodiment, which specifically includes the following contents.

[0024] Multiple magnetic core blocks, when combined, form three magnetic flux loops.

[0025] In one embodiment, the number of magnetic core blocks can be 2, 3, 5, 8, or even more. This embodiment does not specifically limit the number of core blocks. Combining multiple core blocks can form 3 magnetic flux loops. The combination method can be determined according to the shape, structure, and / or preset position of each core block, with the aim of forming 3 magnetic flux loops after combination. In one embodiment, the 3 magnetic flux loops are positioned as 2 parallel magnetic flux loops and 1 magnetic flux loop located on the outer ring of these 2 parallel magnetic flux loops.

[0026] For ease of understanding, for example, Figures 2-6 As shown, in Figure 2In this design, two magnetic core blocks are used. These two magnetic core blocks have the same structure. Taking one magnetic core block as an example, it includes two cuboids: a first side block 101, a second side block 105, and a first middle block 103. The first middle block 103 has a first connecting post 102 and a second connecting post 104 on its two sides. The first connecting post 102 is located between the first side block 101 and the first middle block 103, and the second connecting post 104 is located between the second side block 105 and the first middle block 103. The other magnetic core block has a third side block 106, a fourth side block 110, a second middle block 108, a third connecting post 107, and a fourth connecting post 109.

[0027] Among them, with Figure 2 Taking the perspective of [the magnetic core blocks] as an example, the width of the edge blocks (the collective term for the first to fourth edge blocks) in the horizontal direction is greater than the width of the middle blocks (the collective term for the first to second middle blocks) in the horizontal direction, and the width of the middle blocks in the horizontal direction is greater than the width of the connecting posts (the collective term for the first to fourth connecting posts) in the horizontal direction. After connecting two magnetic core blocks side by side, the edge blocks of the two magnetic core blocks abut against each other, and the positions of the two middle blocks correspond to each other, forming 3 magnetic flux loops. The route of the first magnetic flux loop is: first side block 101, third side block 106, third connecting post 107, second intermediate block 108, first intermediate block 103, first connecting post 102, first side block 101; the route of the second magnetic flux loop is: second side block 105, second connecting post 104, first intermediate block 103, second intermediate block 108, fourth connecting post 109, fourth side block 110, second side block 105; the route of the third magnetic flux loop is: first side block 101, third side block 106, third connecting post 107, second intermediate block 108, fourth connecting post 109, fourth side block 110, second side block 105, second connecting post 104, first intermediate block 103, first connecting post 102, first side block 101.

[0028] exist Figure 3 In this design, four magnetic core blocks are used, designated as core blocks ad. For ease of understanding, the designation will be retained. Figure 2 The characteristic names of each magnetic core block structure in Figure 3 In section a, the first side block 101, the first connecting post 102, and the first intermediate block 103 are integrated into a whole to form magnetic core block a; the second connecting post 104 and the second side block 105 are integrated into a whole to form magnetic core block b; the third side block 106, the third connecting post 107, and the second intermediate block 108 are integrated into a whole to form magnetic core block c; and the fourth connecting post 109 and the fourth side block 110 are integrated into a whole to form magnetic core block d.

[0029] exist Figure 3 In b, with Figure 3The integration methods in 'a' are different. The first side block 101 and the first connecting post 102 are integrated into a whole to form magnetic core block a; the first middle block 103, the second connecting post 104 and the second side block 105 are integrated into a whole to form magnetic core block b; the third side block 106 and the third connecting post 107 are integrated into a whole to form magnetic core block c; and the second middle block 108, the fourth connecting post 109 and the fourth side block 110 are integrated into a whole to form magnetic core block d.

[0030] exist Figure 3 In c, with Figure 3 The integration methods in 'a' are different. The first side block 101 and the third side block 106 are integrated into a whole to become magnetic core block a; the second side block 105 and the fourth side block 110 are integrated into a whole to become magnetic core block b; the first connecting post 102, the first intermediate block 103 and the second connecting post 104 are integrated into a whole to become magnetic core block c; and the third connecting post 107, the second intermediate block 108 and the fourth connecting post 109 are integrated into a whole to become magnetic core block d.

[0031] exist Figure 4 In this design, six magnetic cores are used, designated af. For ease of understanding, the designation will be retained. Figure 2 The characteristic names of each magnetic core block structure in Figure 4 In the first side block 101 and the first connecting post 102 are integrated as a magnetic core block a; the first middle block 103 is a magnetic core block b; the second connecting post 104 and the second side block 105 are integrated as a magnetic core block c; the third side block 106 and the third connecting post 107 are integrated as a magnetic core block d; the second middle block 108 is a magnetic core block e; and the fourth connecting post 109 and the fourth side block 110 are integrated as a magnetic core block f.

[0032] exist Figure 5 In this design, eight magnetic cores are used, designated as ah. For ease of understanding, the following format will be used. Figure 2 The characteristic names of each magnetic core block structure in Figure 5 In the middle, the first side block 101 and the third side block 106 are a whole, forming magnetic core block a; the second side block 105 and the fourth side block 110 are a whole, forming magnetic core block b; the remaining first connecting post 102, first intermediate block 103, second connecting post 104, third connecting post 107, second intermediate block 108 and fourth connecting post 109 are each individually forming magnetic core block ch.

[0033] As can be seen, this embodiment does not limit the number or shape of the magnetic core blocks. For example, the first intermediate block 103 in the above embodiment can also be a whole composed of two magnetic core blocks. The magnetic core blocks can be combined together by mechanical or chemical connection.

[0034] Specifically, the three flux loops include decoupling flux loop 1, coupling flux loop 2, and closed flux loop 3. For example... Figure 1 As shown, in one embodiment, the decoupling magnetic flux loop 1 and the coupling magnetic flux loop 2 are two parallel magnetic circuits. The magnetic circuit corresponding to the closed magnetic flux loop 3 surrounds the magnetic circuits corresponding to the decoupling magnetic flux loop 1 and the coupling magnetic flux loop 2 inside it. That is, the closed magnetic flux loop 3 is located on the periphery of the decoupling magnetic flux loop 1 and the coupling magnetic flux loop 2.

[0035] In one embodiment, the decoupling magnetic flux circuit 1 includes a first magnetic circuit 4 composed of at least one magnetic core block and a gap magnetic circuit 5 composed of at least two magnetic core blocks, wherein the gap magnetic circuit 5 has a gap 51. The coupling magnetic flux circuit 2 and the decoupling magnetic flux circuit 1 share the gap magnetic circuit 5. The coupling magnetic flux circuit 2 includes a second magnetic circuit 6 composed of at least one magnetic core block and the gap magnetic circuit 5. The first magnetic circuit 4 and the second magnetic circuit 6 are in contact with each other to form a closed magnetic flux loop 3, or the first magnetic circuit 4 and the second magnetic circuit 6 are in contact with the gap magnetic circuit 5 respectively to form a closed magnetic flux loop 3.

[0036] For ease of understanding, such as Figure 2 As shown, the first magnetic circuit 4 includes a first side block 101, a first connecting post 102, a third side block 106, and a third connecting post 107; the gap magnetic circuit 5 includes a first intermediate block 103 and a second intermediate block 108; the second magnetic circuit 6 includes a second side block 105, a second connecting post 104, a fourth side block 110, and a fourth connecting post 109. In one embodiment, the first connecting post 102 contacts the second connecting post 104, the third connecting post 107 contacts the fourth connecting post 109, and the gap magnetic circuit 5 is located in the area between the four connecting posts, so that the magnetic flux path corresponding to the closed magnetic flux loop 3 does not pass through the gap magnetic circuit 5; in another embodiment, the first connecting post 102 and the second connecting post 104 respectively abut against both sides of the first intermediate block 103, and the third connecting post 107 and the fourth connecting post 109 respectively abut against both sides of the second intermediate block 108, so that the magnetic flux path corresponding to the closed magnetic flux loop 3 passes through a portion of the gap magnetic circuit 5.

[0037] In one embodiment, the length of the coupling flux loop 2 is greater than the length of the decoupling flux loop 1. That is, the length of the flux path corresponding to the coupling flux loop 2 is greater than the length of the flux path corresponding to the decoupling flux loop 1. This can be achieved by changing the length of the corresponding magnetic core block. For example, in one application scenario... Figure 2As shown, the lengths of the second connecting post 104 and the fourth connecting post 109 are increased, such that the length of the second connecting post 104 is greater than the lengths of the first connecting post 102 and the third connecting post 107, and the length of the fourth connecting post 109 is greater than the lengths of the first connecting post 102 and the third connecting post 107. In another application scenario, to further reduce the core size, the lengths of the first connecting post 102 and the third connecting post 107 are reduced, thus shortening the total length of the decoupled flux loop 1.

[0038] A decoupling window 7 is formed between the first magnetic circuit 4 and the gap magnetic circuit 5, and a coupling window 8 is formed between the second magnetic circuit 6 and the gap magnetic circuit 5. The area of ​​the coupling window 8 is larger than the area of ​​the decoupling window 7. The decoupling window 7 is used for a portion of the coil of the first winding 9 to pass through, and the coupling window 8 is used for a portion of the coil of the first winding 9, the second winding 10 and the third winding 11 to pass through; The number of turns of the first winding 9 passing through the coupling window 8 is greater than the number of turns of the first winding 9 passing through the decoupling window 7.

[0039] like Figure 1 As shown, after the first magnetic circuit 4 and the gap magnetic circuit 5 are combined, a through window, namely the decoupling window 7, is formed inside them; similarly, after the second magnetic circuit 6 and the gap magnetic circuit 5 are combined, a through window, namely the coupling window 8, is formed inside them. The decoupling window 7 corresponds to the decoupling magnetic flux loop 1, and the coupling window 8 corresponds to the coupling magnetic flux loop 2. Therefore, when installing the windings on the magnetic core, part of the coil of the first winding 9 is passed through the decoupling window 7, and part of the coil of the first winding 9, the second winding 10, and the third winding 11 are passed through the coupling window 8. It should be noted that, due to the position of the windings, the part of the coil of the first winding 9 passed through the decoupling window 7 is not completely magnetically coupled with the second winding 10 and the third winding 11, and is in a decoupling state. Therefore, in this embodiment, it is called the decoupling window 7 and the decoupling magnetic flux loop 1. Correspondingly, since the second winding 10 and the third winding 11 are passed through the same window, they are in a coupled state, and are therefore called the coupling window 8 and the coupling magnetic flux loop 2.

[0040] This configuration allows the first winding 9, which runs through the decoupling window 7, to form a certain amount of leakage inductance, which is equivalent to the resonant inductance in a current-changing circuit. This saves on raw material costs and reduces the core volume, thereby increasing the power density.

[0041] Using the above method, in a power electronic topology converter circuit where the resonant inductance is generated by the leakage inductance between the first winding 9 and the second winding 10 of the transformer, the decoupling window 7 is used for the first winding 9 to pass through, and the coupling window 8 is used for the first winding 9, the second winding 10, and the third winding 11 to pass through. This achieves the use of externally wound transformer winding conductors, thus significantly improving both the transformer winding thermal management problem and the leakage flux control problem between the first winding 9 and the second winding 10. It also achieves deep magnetic integration of magnetic components, reducing the size of the magnetic components themselves and lowering the cost of raw materials. By controlling the lengths of decoupling flux loop 1 and coupling flux loop 2, and controlling the window area sizes formed by decoupling flux loop 1 and coupling flux loop 2 respectively, the number of coil turns of the first winding 9 passing through coupling window 8 and the number of coil turns of the first winding 9 passing through decoupling window 7 are reasonably distributed, thereby improving the area utilization rate of decoupling window 7 and coupling window 8, compressing the size of the transformer core, and thus maximizing the compression of the three-port transformer size and increasing power density.

[0042] In another embodiment of this application, the decoupling window 7, the gap 51 and the coupling window 8 are arranged sequentially along the first direction, and the decoupling window 7 and the coupling window 8 are connected through the gap 51.

[0043] The first direction can be a horizontal direction in a horizontal plane or a vertical direction in a vertical plane; this embodiment does not specifically limit it. For ease of understanding, as follows: Figure 1 As shown, the first direction is Figure 1 The direction from left to right or from right to left.

[0044] The first magnetic circuit 4 abuts against the first side of the gap magnetic circuit 5, and the second magnetic circuit 6 abuts against the second side of the gap magnetic circuit 5. The first side and the second side of the gap magnetic circuit 5 are two corresponding sides in the first direction.

[0045] Specifically, such as Figure 1 As shown, the first magnetic circuit 4 is located to the left of the gap magnetic circuit 5, and the second magnetic circuit 6 is located to the right of the gap magnetic circuit 5.

[0046] Using the above method, the decoupling window 7, the gap 51 and the coupling window 8 are arranged sequentially along the first direction, so that the first magnetic circuit 4, the gap magnetic circuit 5 and the second magnetic circuit 6 are arranged sequentially along the first direction, which helps to control the core size.

[0047] In another embodiment of this application, the area of ​​the effective magnetic flux cross-section of the first magnetic circuit 4 is greater than or equal to the area of ​​the effective magnetic flux cross-section of the second magnetic circuit 6.

[0048] The effective magnetic flux cross section is a concept in electromagnetism and transformer design, usually represented by the symbol [symbol missing]. This is also commonly referred to as the effective cross-sectional area of ​​the magnetic core. For toroidal magnetic cores, it refers to the actual physical cross-sectional area of ​​the magnetic ring. Figure 2 For example, cutting the first connecting post 102 along a vertical plane perpendicular to the length direction of the second connecting post 104 yields a vertical surface of the first connecting post 102 that is the effective magnetic flux cross-section of the first magnetic circuit 4. Similarly, cutting the first side block 101 along a vertical plane parallel to the length direction of the second connecting post 104 yields a vertical surface of the first side block 101 that is also the effective magnetic flux cross-section of the first magnetic circuit 4. Dividing the second connecting post 104 along a vertical plane perpendicular to its length direction yields a vertical surface of the second connecting post 104 that is the effective magnetic flux cross-section of the second magnetic circuit 6. In one embodiment, since the first magnetic circuit 4 is composed of at least one magnetic core block and the second magnetic circuit 6 is composed of at least one magnetic core block, the cross-sectional area referred to in this embodiment refers to the maximum cross-sectional area.

[0049] By adopting the above method, setting the cross-sectional area of ​​the first magnetic circuit 4 to be greater than or equal to the cross-sectional area of ​​the second magnetic circuit 6 is beneficial to maintaining a reasonable magnetic flux density and preventing the magnetic core from entering a saturation state.

[0050] In another embodiment of this application, the area of ​​the effective magnetic flux cross-section of the gap magnetic circuit 5 is greater than or equal to the area of ​​the effective magnetic flux cross-section of the second magnetic circuit 6.

[0051] The effective magnetic flux cross section is a concept in electromagnetism and transformer design, usually represented by the symbol [symbol missing]. This is also commonly referred to as the effective cross-sectional area of ​​the magnetic core. For toroidal magnetic cores, it refers to the actual physical cross-sectional area of ​​the magnetic ring. Figure 2 For example, the vertical surface of the first intermediate block 103 facing the second intermediate block 108 can be used as the effective magnetic flux cross-section of the gap magnetic circuit 5. Similarly, the vertical surface of the second intermediate block 108 facing the first intermediate block 103 can also be used as the effective magnetic flux cross-section of the gap magnetic circuit 5. In one embodiment, since the gap magnetic circuit 5 is composed of at least two magnetic core blocks and the second magnetic circuit 6 is composed of at least one magnetic core block, the cross-sectional area referred to in this embodiment refers to the maximum cross-sectional area.

[0052] By adopting the above method, the cross-sectional area of ​​the gap magnetic circuit 5 is set to be greater than or equal to the cross-sectional area of ​​the second magnetic circuit 6, which is beneficial to maintaining a reasonable magnetic flux density and minimizing the volume of the three-port transformer.

[0053] This application also provides a three-port transformer, such as... Figure 6 and Figure 7 As shown, the magnetic core mentioned above is included, as well as three transformer windings, namely the first winding 9, the second winding 10 and the third winding 11. The first winding 9 includes a first decoupling coil 91, a second decoupling coil 92, and a first main coil 93. The first decoupling coil 91, the second decoupling coil 92, and the first main coil 93 are wound from the same continuous wire. The first decoupling coil 91 and the second decoupling coil 92 are the two ends of the wire, and the first main coil 93 is the middle part of the wire. The first decoupling coil 91 and the second decoupling coil 92 are arranged side by side in the decoupling window 7, and the first main coil 93, the second winding 10 and the third winding 11 are all arranged in the coupling window 8. The total number of turns of the first decoupling coil 91 and the second decoupling coil 92 is less than the number of turns of the first main coil 93.

[0054] It should be noted that when installing the first winding 9, the second winding 10, and the third winding 11, the first decoupling coil 91 and the second decoupling coil 92 are wound side by side and both pass through the decoupling window 7. Specifically, as shown... Figure 2 As shown, the first decoupling coil 91 is wound on the first connecting post 102, and the second decoupling coil 92 is wound on the third connecting post 107. The first main coil 93, the second winding 10, and the third winding 11 also each have two parts, one part is wound on the second connecting post 104, and the other part is wound on the fourth connecting post 109.

[0055] In one embodiment, the first main coil 93 and the second winding 10 are wound side by side in the coupling window 8 along a first direction, and the first main coil 93 is closer to the decoupling window 7 than the second winding 10. The third winding 11 is located on the outer periphery of the first main coil 93 and the second winding 10, or the third winding 11 is located on the outer periphery of the second winding 10, that is, the second winding 10 is located on the inner side of the third winding 11. In another embodiment, the first main coil 93 is located on the inner side of the second winding 10, and the second winding 10 is located on the inner side of the third winding.

[0056] Using the above method, the length of the coupling flux loop 2 in the magnetic core is greater than the length of the decoupling flux loop 1, providing conditions for the winding of the third winding 11. Simultaneously, the area of ​​the decoupling window 7 is smaller than the area of ​​the coupling window 8. The window area determines the number of turns; a larger window area allows for windings with more turns. Conversely, a smaller window area allows for windings with fewer turns, maximizing the utilization of the window area and minimizing the transformer size to maximize the power density of the current-changing product. Furthermore, since the number of turns in the first decoupling coil 91 and the second decoupling coil 92 is less than the number of turns in the first main coil 93, conditions are provided for a smaller decoupling window 7 area, maximizing the compression of the size of the decoupling flux loop 1, thereby reducing the overall transformer volume. This also allows for the retention of most of the first winding 9, which is coupled with the second winding 10 and the third winding 11, achieving controllable leakage inductance while maintaining a certain degree of magnetic coupling between the three windings.

[0057] In another embodiment of this application, the first winding 9 and the second winding 10 are respectively wound with Litz wire with a diameter of less than 0.2 mm, the third winding 11 is wound with copper foil, copper busbar or aluminum busbar, and the minimum distance between the third winding 11 and the gap 51 is not less than 2 mm.

[0058] In one embodiment, the first winding 9 and the second winding 10 are wound with Litz wire with a diameter of less than 0.1 mm, such as 0.05 mm or 0.06 mm, which helps to reduce AC losses caused by the skin effect in the first winding 9 and the second winding 10.

[0059] In one embodiment, such as Figure 8 As shown, the third winding 11 is wound with copper or aluminum busbars. To reduce its height and achieve better heat dissipation, after the copper or aluminum busbar winding is soldered to the PCB, the third winding 11 can be closed by PCB wiring. That is, a combination of copper or aluminum busbars and PCB wiring copper foil is used for winding. In this way, the size of the transformer itself is reduced, and the natural thermal conductivity of the PCB can be greatly utilized for heat dissipation.

[0060] Among them, such as Figure 8 and Figure 9 As shown, during the simulation, it was found that there is magnetic leakage at the location of gap 51. This leakage magnetic field cuts through the third winding 11, causing eddy current losses, unnecessary heat generation, increasing heat dissipation difficulty, and reducing conversion efficiency. Specifically, as... Figure 9As shown, although leakage flux has been significantly controlled, a small amount of leakage flux still radiates outwards from the transformer. Gap 51 still exhibits localized leakage flux, which can be mitigated by increasing the distance between the transformer conductors and gap 51 to avoid magnetic field interference or cutting of the transformer conductors. Therefore, the minimum distance between the third winding 11 and gap 51 is controlled to be beyond 2mm, such as 2.5mm or 3mm; this embodiment does not impose a specific limitation on this. Figure 10 As shown, after controlling the minimum distance between the third winding 11 and the gap 51 to more than 2mm, the heat generation improved significantly.

[0061] To better understand the effect of local leakage flux in gap 51 on the third winding 11, such as Figure 11 The figure shown is a simulation diagram when the minimum distance between the third winding 11 and the gap 51 is less than 2mm. Figure 11 It can be clearly seen that the side of the third winding 11 near the gap 51 is cut by leakage magnetic field, resulting in severe eddy current loss.

[0062] Furthermore, such as Figure 12 The diagram shows a simulation of a transformer with an internal coil winding and resonant inductance generated by the leakage inductance of the primary and secondary windings. The simulation results clearly show that the leakage flux creates a magnetic field that cuts the conductors wound inside the transformer, resulting in severe eddy current losses. The red area represents the heat generated by the eddy current effect. It is evident that the three-port transformer in this embodiment, with an external coil winding, significantly reduces eddy current losses. Furthermore, the minimum distance between the third winding 11 and the gap 51 is controlled to further reduce eddy current losses in the third winding 11. In addition, the third winding 11 is wound with copper foil, copper busbars, or aluminum busbars to increase its heat dissipation capacity, achieving the goal of simultaneously reducing overall and local eddy current losses and improving overall and local heat dissipation.

[0063] It should be noted that, since the length of the coupling magnetic flux loop 2 of the magnetic core is greater than the length of the decoupling magnetic flux loop 1, the third winding 11 has the condition of maintaining a certain distance from the gap 51.

[0064] By limiting the diameters of the first winding 9 and the second winding 10 using the above method, it is helpful to reduce the AC losses caused by the skin effect in the first winding 9 and the second winding 10. The third winding 11 is wound with copper foil, copper busbar or aluminum busbar, which helps to improve heat dissipation. In addition, the minimum distance between the third winding 11 and the gap 51 is greater than or equal to 2mm to avoid the third winding 11 being cut by leakage magnetic flux, thereby maximizing the reduction of eddy current losses and improving conversion efficiency.

[0065] In another embodiment of this application, such as Figure 13 and Figure 14As shown, the first decoupling coil 91 and the second decoupling coil 92 are respectively wound on the first magnetic circuit 4, and the first main coil 93, the second winding 10 and the third winding 11 are wound together on the second magnetic circuit 6.

[0066] In one embodiment, the first main coil 93 and the second winding 10 are not fully coupled, serving as the secondary winding of the transformer, while the first decoupling coil 91 and the second decoupling coil 92 serve as the primary winding of the transformer. Wherein, Figure 14 In this context, the first decoupling coil 91 and the second decoupling coil 92 are considered equivalent to the same coil.

[0067] Using the above method, the first decoupling coil 91, the second decoupling coil 92, and the leakage inductance generated by incomplete coupling are all equivalent to a resonant inductor. There is no need to set up a separate resonant inductor coil, which reduces the amount of wire used and lowers wire loss and material costs.

[0068] In another embodiment of this application, the number of turns of the first winding 9 and the number of turns of the second winding 10 are both greater than the number of turns of the third winding 11.

[0069] In another embodiment of this application, the number of turns of the first decoupling coil 91 is the same as the number of turns of the second decoupling coil 92.

[0070] Using the above method, the first decoupling coil 91 and the second decoupling coil 92, which have the same number of turns, ensure the consistency of leakage inductance.

[0071] In another embodiment of this application, the third winding 11 is wound around the outer layer of the first main coil 93 and the second winding 10.

[0072] By adopting the above method, the third winding 11 set on the outer layer can dissipate heat better while reducing space occupation, further constraining the size of the transformer.

[0073] The above description discloses only preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention. Therefore, equivalent variations made in accordance with the claims of the present invention are still within the scope of the present invention.

Claims

1. A composite magnetic core having three flux loops, characterized in that, It includes multiple magnetic core blocks, and the multiple magnetic core blocks are combined to form three magnetic flux loops; The three magnetic flux loops include a decoupling magnetic flux loop, a coupling magnetic flux loop, and a closed magnetic flux loop; The decoupling magnetic flux circuit includes a first magnetic circuit composed of at least one of the magnetic core blocks and a gap magnetic circuit composed of at least two of the magnetic core blocks, wherein the gap magnetic circuit has a gap. The coupled magnetic flux circuit and the decoupled magnetic flux circuit share the gap magnetic circuit. The coupled magnetic flux circuit includes a second magnetic circuit composed of at least one of the magnetic core blocks and the gap magnetic circuit. The first magnetic circuit and the second magnetic circuit are in contact with each other to form the closed magnetic flux loop, or the first magnetic circuit and the second magnetic circuit are respectively in contact with the gap magnetic circuit to form the closed magnetic flux loop; The length of the coupling magnetic flux loop is greater than the length of the decoupling magnetic flux loop; A decoupling window is formed between the first magnetic circuit and the gap magnetic circuit, and a coupling window is formed between the second magnetic circuit and the gap magnetic circuit. The area of ​​the coupling window is larger than the area of ​​the decoupling window. The decoupling window is used for a portion of the first winding coil to pass through, and the coupling window is used for a portion of the first winding coil, the second winding, and the third winding to pass through; The number of coil turns of the first winding passing through the coupling window is greater than the number of coil turns of the first winding passing through the decoupling window.

2. The combined magnetic core with three magnetic flux loops according to claim 1, characterized in that, The decoupling window, the gap, and the coupling window are arranged sequentially along a first direction, and the decoupling window and the coupling window are connected through the gap; The first magnetic circuit abuts against the first side of the gap magnetic circuit, and the second magnetic circuit abuts against the second side of the gap magnetic circuit. The first side and the second side of the gap magnetic circuit are two corresponding sides in the first direction.

3. The combined magnetic core with three flux loops according to claim 1, characterized in that, The area of ​​the effective magnetic flux cross section of the first magnetic circuit is greater than or equal to the area of ​​the effective magnetic flux cross section of the second magnetic circuit.

4. The combined magnetic core with three magnetic flux loops according to claim 1, characterized in that, The area of ​​the effective magnetic flux cross-section of the gap magnetic circuit is greater than or equal to the area of ​​the effective magnetic flux cross-section of the second magnetic circuit.

5. A three-port transformer, characterized in that, The magnetic core includes any one of claims 1-4, and further includes three transformer windings, the three transformer windings being a first winding, a second winding, and a third winding, respectively; The first winding includes a first decoupling coil, a second decoupling coil, and a first main coil. The first decoupling coil, the second decoupling coil, and the first main coil are wound from the same continuous wire. The first decoupling coil and the second decoupling coil are the two ends of the wire, and the first main coil is the middle part of the wire. The first decoupling coil and the second decoupling coil are arranged side by side in the decoupling window, and the first main coil, the second winding and the third winding are all arranged in the coupling window; The total number of turns of the first decoupling coil and the second decoupling coil is less than the number of turns of the first main coil.

6. The three-port transformer according to claim 5, characterized in that, The first winding and the second winding are respectively wound with Litz wire with a diameter of less than 0.2 mm, and the third winding is wound with copper foil, copper busbar or aluminum busbar, and the minimum distance between the third winding and the gap is not less than 2 mm.

7. The three-port transformer according to claim 5 or 6, characterized in that, The first decoupling coil and the second decoupling coil are respectively wound on the first magnetic circuit, and the first main coil, the second winding and the third winding are together wound on the second magnetic circuit.

8. The three-port transformer according to claim 5 or 6, characterized in that, The number of turns in the first winding and the number of turns in the second winding are both greater than the number of turns in the third winding.

9. The three-port transformer according to claim 5 or 6, characterized in that, The number of turns of the first decoupling coil is the same as the number of turns of the second decoupling coil.

10. The three-port transformer according to claim 5 or 6, characterized in that, The third winding is wound around the outer layer of the first main coil and the second winding.

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