Large-current planar transformer

Abstract

The invention belongs to power electronic conversion devices and high-frequency magnetic elements, and particularly discloses a high-current planar transformer which comprises a magnetic core and a plurality of PCBs (printed circuit boards), and the PCBs are sequentially arranged layer by layer. At least one layer of PCB wires is arranged on each PCB, one or more turns of PCB wires are arranged, and each PCB wire comprises two connecting ports; and the connecting ports of the PCB wires are distributed at the mounting positions on the four sides of the rectangular PCB. On one hand, the length of the PCB wire at the port joint is reduced, the loss of the copper wire is reduced, and the efficiency of the transformer is improved; and on the other hand, the size of the PCB in a large-current application scene is reduced, and the power density of the transformer is improved.

Description

Technical Field

[0001] The invention relates to a power electronic conversion device and a high-frequency magnetic element, and in particular to a large-current planar transformer. Background Art

[0002] Traditional transformers are vertically wound structures with mature design solutions, but they are not conducive to the development of high frequency, miniaturization, and high efficiency. Unlike traditional vertically wound transformers that use a skeleton structure and enameled wire winding, planar transformers use flat magnetic cores, omit the skeleton, and use multi-layer PCB (Printed Circuit Board) boards as conductors. They have significant advantages in height size and are receiving more and more attention. In addition, planar transformers also have the characteristics of stable parameter performance, good batch consistency, and excellent adaptability to automated production, and have broad application prospects.

[0003] For the sake of process and economy, there are two major forms of multi-layer PCB conductors. One is a multi-layer printed PCB. The other is a combination of multiple double-layer (or four-layer) printed PCBs.

[0004] like Figure 1 As shown, a double-layer PCB board with copper cladding on both sides is a sandwich structure. The front and back sides of the insulating substrate 11 are thin copper layers 13A1 and thin copper layers 13A2 respectively. The copper layer 13A1 and the copper layer 13A2 are connected by drilling and copper deposition processes. The main steps are: drilling a board hole 12 at the position where the copper layer 13A1 and the copper layer 13A2 need to be connected. Immerse the drilled board in a special solution to activate the hole wall material so that it is easier to absorb copper ions. The activated drilled PCB board is immersed in a chemical reagent containing copper ions, so that the copper ions are deposited on the surface of the hole wall to form a conductive layer. At this time, the copper layer 13A1 and the copper layer 13A2 are electrically conductive through the copper deposition hole 12.

[0005] The manufacturing process of multi-layer PCB is much more complicated than that of double-layer PCB, and the cost increases accordingly. Figure 2 As shown in the figure, the main process flow is described by taking the production of a 4-layer PCB board as an example. First, the double-layer PCB board 1A, the insulating substrate 11C, and the double-layer PCB board 1B are stacked in sequence. Under a vacuum, high pressure, and high temperature environment, the stacked boards are pressed for a long time to form a complete multi-layer PCB board. The multi-layer PCB board has 4 layers of PCB conductor layers from top to bottom, namely 13A1, 13A2, 13B1, and 13B2, and there is an insulating substrate between adjacent conductor layers as isolation.

[0006] like Figure 3As shown, the connection between different wire layers of a multi-layer PCB is similar to the connection between wire layers of a double-layer PCB, and is also realized based on drilling and copper deposition. However, compared with a double-layer PCB, the specific process for realizing the connection of wire layers of a multi-layer PCB is more complicated and more expensive. Among them, in case 1, hole 12 is a through hole, connecting all wire layers 13A1, 13A2, 13B1, and 13B2 from the top layer to the bottom layer. In case 2, hole 12 is a buried hole, connecting the inner layer 13A2 and 13B1, and not connecting the outer layer 13A1 and 13B2. The production cost of case 2 is higher than that of case 1.

[0007] For PCB boards with more layers, such as 6-layer boards, 8-layer boards, 10-layer boards, etc., the production is also based on the main steps of stacking, pressing, drilling, copper plating, etc. The more layers there are, the more complicated the specific production process is, and the higher the cost is.

[0008] like Figure 4 As shown in FIG. 1 , if multiple double-layer PCB boards are directly connected, the process can be significantly simplified and the cost can be reduced. Also, taking the connection of 4-layer PCB wires as an example, two connection situations are described.

[0009] In case 1, two double-layer PCB boards 1A and 1B are used to connect the wire layers 13A2, 13B1, and 13B2 through holes 12A and 12B. The specific implementation steps are: 1) Drill hole 12A at the edge of PCB board 1A and drill hole 12B at the edge of PCB board 1B. The drilling position is used for subsequent wire layer connection, and the drilling position is consistent. Since wire layer 13A1 does not participate in the connection, it is ensured during the design that there is a certain isolation space between wire layer 13A1 and hole 12A to avoid miscommunication between subsequent wire layer 13A1 and other wire layers. 2) Stack the double-layer PCB boards 1A and 1B, ensure insulation between wire layers 13A2 and 13B1 (insulation pads, insulation glue, etc.), and align holes 12A and 12B. Use metal connecting columns 4 to connect wire layers 13A2, 13B1, and 13B2 at the drilling position. The metal connecting column can be a copper column, a welding rod, or other metal connection structure. The connection form can be a fastener connection or a welding connection.

[0010] When multiple double-layer PCB boards are used for connection, in addition to drilling holes on the edges to achieve connection, the copper plating process of the double-layer PCB board itself can also be used to achieve connection between the two copper layers of the double-layer board. Figure 4 In the illustrated case 2, two double-layer PCB boards 1A and 1B are used to connect a total of 4 conductive layers. The conductive layers 13A1 and 13A2 are connected through the copper conductive via 12A1, the conductive layers 13A2 and 13B1 are connected through the metal conductive column 4, and the conductive layers 13B1 and 13B2 are connected through the copper conductive via 12B1.

[0011] Due to the characteristics of simple process, flexible wiring, convenient modification and low cost, using multiple double-layer PCB boards instead of one multi-layer PCB board as the conductor of the planar transformer has attracted wide attention in the industry. With the maturity of the 4-layer PCB board process and the reduction of costs, in some occasions, multiple 4-layer PCB boards will also be connected. The principle is the same as that of connecting multiple double-layer PCB boards.

[0012] However, despite its many advantages, using multiple double-layer PCB boards as transformer conductors requires designing a connection structure at the edge of the PCB board to achieve the connection of different double-layer PCB board conductor layers. In high-current application scenarios, there are problems such as low PCB board utilization and large transformer size, which limits its application in high-current situations.

[0013] like Figure 5 As shown, the planar transformer is composed of a PCB board 1 and a magnetic core 2. The PCB board serves as a conductor of the transformer.

[0014] like Figure 6 As shown, the PCB board 1 is composed of an insulating substrate 11 and a conductor copper layer 13 printed on the substrate. A hole 12 is dug in the middle of the substrate for mounting the magnetic core. The conductor 13 has two ports 131 and 132, which serve as the input and output terminals of the layer and are used to achieve connection with other conductor layers.

[0015] like Figure 7 As shown, the size of PCB board 1 needs to match the magnetic core 2. Therefore, the width and height of the PCB board are limited. The PCB board's winding width x1 and x2 need to be smaller than the core window width c1. The width x5 of the hole 12 in the middle of the PCB board needs to be larger than the core center column size c3. The total height of multiple double-layer PCB boards should be smaller than the core window height c2.

[0016] like Figure 8 As shown, on the PCB, the size of the copper layer 13 of the conductor needs to match the insulating substrate 11, further limiting the space available for winding on the PCB. These limitations include: the conductor width y1 should be as uniform as possible everywhere to ensure consistent current density. The distance y between the edge of the substrate and the adjacent conductor 2a ,y 2b It should meet the insulation and process requirements. The distance y3 between the wires should meet the insulation requirements.

[0017] like Fig. 9 As shown in the figure, examples of PCB conductor layout with different space utilization are given. Fig. 9 (a) shows a case where the board space utilization is low, 1 turn, and low current. Fig. 9 (b) shows a case with high board space utilization, 1 turn, and high current. Fig. 9(c) shows another case with high board space utilization, 4 turns, and small current. The larger the current, the larger the conductor cross-sectional area required, and under the same conditions, the larger the wire width y1 required.

[0018] Fig. 9 (b) shows the case where one turn of wire is arranged on one layer of PCB. If the current is further increased, multiple layers of PCB wires can be connected in parallel to achieve a higher current design. Fig. 9 (c) shows the case where 4 turns of wire are arranged on one layer of PCB. If the number of turns is further increased, multiple layers of PCB wires can be connected in series to achieve a design with more turns. Current conduction is achieved between each layer of PCB wires through ports.

[0019] like Fig.10 As shown in the figure, the problem caused by the increase of current is explained by taking 4 turns of high current wire as an example. Two double-layer PCB boards 1A and 1B are arranged up and down, and each PCB board has two layers of PCB wires on the top and bottom surfaces. Each layer of wires is arranged with one turn, and the current conduction is realized through the ports of different layers of PCB wires.

[0020] like Fig.11 As shown, specifically: in the first layer, the current flows into the a end and flows out of the b1 end. At the b1 port of the first layer and the b2 port of the second layer, the first and second layers of PCB wires are connected and the current is conducted by drilling and depositing copper. In the second layer, the current flows into the b2 end and flows out of the c1 end. At the c1 port of the second layer and the c2 port of the third layer, the second and third layers of PCB wires are connected and the current is conducted by drilling and adding conductive columns on the edge of the PCB. In the third layer, the current flows into the c2 end and flows out of the d1 end. At the d1 port of the third layer and the d2 port of the fourth layer, the third and fourth layers of PCB wires are connected and the current is conducted by drilling and depositing copper. In the fourth layer, the current flows into the d2 end and flows out of the e end.

[0021] The problem caused by this arrangement is that ports a, c1, c2, and e are all located on the side of edge 1. Since large currents require a larger current-carrying area, the width of the PCB conductor increases, and the design space of the conductor port area is insufficient, so ports c1 and c2 used to connect the second and third layers of PCB conductor currents exceed the range of edge 1 of the PCB board. Therefore, edge 1 extends outward, and the length of edge 2 increases, eventually forming a Fig.12 The wire arrangement of a high current planar transformer is shown.

[0022] Fig.12It represents the common high-current planar transformer conductor arrangement in the prior art. Multiple connection terminals are designed on the short side of the rectangular PCB board to realize the connection of different PCB board conductor layers. The space utilization rate of the PCB board is low, and there are many blank areas at the connection of the conductor ports of each layer. When the current becomes larger and the maximum conductor width allowed by a layer of PCB board cannot meet the current-carrying area, the current can be increased based on the parallel connection of multiple layers of PCB conductors. The more complex the connection form, the more required connection ports. If all the connection terminals cannot be arranged on the short side of one side of the rectangular PCB board, the remaining connection terminals need to be arranged on the short side of the other side of the PCB board.

[0023] In summary, when planar transformers are used in high current scenarios, they are limited by the layout of traditional centralized connection terminals. The wire length at the multi-layer port connection becomes longer and the PCB size increases, which is not conducive to the miniaturization, lightweight and high efficiency design of planar transformers, limiting the application of planar transformers in high current scenarios.

[0024] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present invention, and therefore may include information that does not constitute the prior art known to ordinary technicians in the field. Summary of the invention

[0025] The purpose of the present invention is to solve the technical problems existing in the background technology, and for this purpose, a high current planar transformer is provided.

[0026] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0027] A high current planar transformer comprises a magnetic core and a plurality of PCB boards, wherein the plurality of PCB boards are arranged in layers;

[0028] At least one layer of PCB conductors is provided on each PCB board, the PCB conductors are arranged in one turn or multiple turns, and the PCB conductors include two connection ports;

[0029] When the PCB conductor is arranged in one turn:

[0030] One connection port of each layer of PCB conductor is arranged on the PCB board, and the other connection port is arranged on the edge of the PCB board away from the magnetic core;

[0031] The connection ports arranged at the edge of the PCB board away from the magnetic core are arranged in a cycle according to a specific position distribution, wherein a specific position distribution cycle is: one edge of the long side of the PCB board, one edge of the short side of the PCB board, one edge of the short side of the PCB board, and two edges of the long side of the PCB board.

[0032] The following is a technical solution further defined in the present invention, wherein the PCB conductor includes a current inflow port and a current outflow port;

[0033] When the PCB conductor is arranged in one turn and has four layers of PCB conductors:

[0034] The current inflow port of the first layer PCB conductor is arranged at an edge of the long side of the PCB board and away from the magnetic core, and the current outflow port is arranged on the PCB board;

[0035] The current outflow port of the first layer PCB conductor is connected to the current inflow port of the second layer PCB conductor;

[0036] The current inflow port of the second layer PCB conductor is arranged on the PCB board, and the current outflow port is arranged at an edge of the short side of the PCB board;

[0037] The current outflow port of the second-layer PCB conductor is connected to the current inflow port of the third-layer PCB conductor;

[0038] The current inflow port of the third layer PCB conductor is arranged at an edge of the short side of the PCB board, and the current outflow port is arranged on the PCB board;

[0039] The current outflow port of the third-layer PCB conductor is connected to the current inflow port of the fourth-layer PCB conductor;

[0040] The current inflow port of the fourth layer PCB conductor is arranged on the PCB board, and the current outflow port is arranged at the second edge of the long side of the PCB board and away from the magnetic core.

[0041] The following is a technical solution further defined by the present invention, drilling holes at the edge of the PCB board and installing conductive pillars to achieve current conduction between the connection ports arranged at the edge;

[0042] Drill copper holes on the PCB board to achieve current conduction between the connection ports arranged on the PCB board.

[0043] The following is a technical solution further defined by the present invention: when the PCB conductor is arranged with multiple turns: one connection port of each layer of PCB conductor is arranged on the PCB board, and the other connection port is arranged at the position of the second edge of the short side of the PCB board.

[0044] Compared with the prior art, the present invention has the following technical effects:

[0045] The present invention optimizes the wire connection ends between multi-layer PCBs from the traditional centralized arrangement to a distributed arrangement, making full use of the installation positions on the four sides of the rectangular PCB board, and achieving the following beneficial effects: on the one hand, the length of the PCB wire at the port connection is reduced, the loss of the copper wire is reduced, and the efficiency of the transformer is improved; on the other hand, the size of the PCB board in the high current application scenario is reduced, which is conducive to improving the power density of the transformer.

[0046] The present invention is further described below in conjunction with the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in 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 ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0048] Figure 1 This is a schematic diagram of the structure of a double-layer PCB board with copper cladding on both sides; the left side is a three-dimensional diagram, and the right side is a schematic diagram of the wire layer connection (also a cross-sectional view of the PCB board);

[0049] Figure 2 This is a schematic diagram of the structure of a 4-layer PCB board, where the left side is a schematic diagram of the structure in stacking; the right side is a schematic diagram of the structure after lamination;

[0050] Figure 3 1 is a schematic diagram of the connection of the conductor layer of a multi-layer PCB board, wherein the left side is a schematic diagram of the connection of the conductor layer of a multi-layer PCB board in case 1, and the right side is a schematic diagram of the connection of the conductor layer of a multi-layer PCB board in case 2;

[0051] Figure 4 This is a schematic diagram of the connection between two double-layer PCB boards, where: Figure 4 (a) is the schematic diagram of the PCB connection before connection in case 1. Figure 4 (b) is a schematic diagram of PCB board connection after connection in case 1; Figure 4 (c) is the schematic diagram of the PCB connection before connection in case 2. Figure 4 (d) is a schematic diagram of PCB board connection after connection in case 2;

[0052] Figure 5 Schematic diagram of the structure of a planar transformer, wherein the left side is a schematic diagram of the structure of a PCB board, and the right side is a schematic diagram of the structure of a combination of a PCB board and a magnetic core;

[0053] Figure 6 It is a schematic diagram of the distribution of PCB conductors, wherein the left side is a schematic diagram of the PCB board insulation substrate structure, and the right side is a schematic diagram of the PCB conductor structure;

[0054] Figure 7 This is the connection diagram between the magnetic core and the PCB board, where: Figure 7 (a) is a three-dimensional diagram of the magnetic core. Figure 7 (b) is the front view of the magnetic core. Figure 7 (c) is a top view of the PCB board;

[0055] Figure 8 It is a diagram of the coordination and connection relationship between the insulating substrate and the conductor layer of the PCB board, wherein the left side is a schematic diagram of the insulating substrate structure of the PCB board, and the right side is a schematic diagram of the PCB conductor structure;

[0056] Fig. 9 This is a schematic diagram of PCB conductor layout with different space utilization rates, where: Fig. 9 (a) is a schematic diagram of PCB conductor layout with low space utilization. Fig. 9 (b) is a schematic diagram of a PCB conductor layout with high space utilization. Fig. 9 (c) is a schematic diagram of another PCB conductor arrangement with high space utilization;

[0057] Fig.10 This is a schematic diagram of the connection of 4 turns of high current wire based on two double-layer PCB boards;

[0058] Fig.11 This is a schematic diagram of the planar transformer conductor layout in which the PCB conductor has the problem of widening under high current. Fig.11 (a) is the first layer PCB conductor distribution diagram, Fig.11 (b) is the second layer PCB conductor distribution diagram, Fig.11 (c) is the third layer PCB conductor distribution diagram, Fig.11 (d) is the fourth layer PCB conductor distribution diagram;

[0059] Fig.12 This is a schematic diagram of the common high-current planar transformer conductor arrangement in the prior art, in which: Fig.12 (a) is the first layer PCB conductor distribution diagram, Fig.12 (b) is the second layer PCB conductor distribution diagram, Fig.12 (c) is the third layer PCB conductor distribution diagram, Fig.12 (d) is the fourth layer PCB conductor distribution diagram;

[0060] Fig.13 This is a schematic diagram of the conductor arrangement of a planar transformer with the PCB connection ends centrally arranged on the long side, where: Fig.13 (a) is the first layer PCB conductor distribution diagram, Fig.13 (b) is the second layer PCB conductor distribution diagram, Fig.13 (c) is the third layer PCB conductor distribution diagram, Fig.13 (d) is the fourth layer PCB conductor distribution diagram;

[0061] Fig.14 This is a schematic diagram of the uneven distribution of the magnetic field in the core caused by the long-side concentrated wire connection end;

[0062] Fig.15 Schematic diagram of the distributed arrangement of the multi-layer PCB conductor connection ends of the present invention, wherein: Fig.15 (a) is the first layer PCB conductor distribution diagram, Fig.15 (b) is the second layer PCB conductor distribution diagram, Fig.15 (c) is the third layer PCB conductor distribution diagram, Fig.15 (d) is the fourth layer PCB conductor distribution diagram;

[0063] Fig.16 1 is a schematic diagram of the structure of the present invention using 12 double-layer PCB boards, wherein the left side is a schematic diagram of the structure of the 12 double-layer PCB boards matching the magnetic core, and the right side is a schematic diagram of the position distribution structure of the 12 double-layer PCB boards;

[0064] Fig.17 It is a distribution diagram of the arrangement of the PCB wire connection terminals of each PCB board of the present invention;

[0065] Fig.18 It is a schematic diagram comparing the structures of a high-current planar transformer using a traditional centralized wire connection end and a high-current planar transformer using a distributed wire connection end of the present invention, wherein the left side is a schematic diagram of the structure of a high-current planar transformer using a traditional centralized wire connection end, and the right side is a schematic diagram of the structure of a high-current planar transformer using a distributed wire connection end of the present invention. DETAILED DESCRIPTION

[0066] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific embodiments disclosed below.

[0067] like Fig.13 As shown in FIG. 1 , if the connection ends of the multi-layer PCB are arranged on the long side of the PCB, the problem of the PCB board becoming larger in size can be solved. Fig.14As shown, the centralized arrangement of the PCB connection terminals on the long side will cause uneven distribution of the magnetic field of the core. This is because, on the side of side 4, the area where the connection terminals b1, b2, c1, c2, d1, and d2 are located is close to the magnetic core. On the side of side 4, the current density in the connection terminal area is large and the magnetic field level is high. On the side of side 2, there is no connection terminal and the magnetic field level is small. Therefore, the magnetic field distribution of the magnetic core is very uneven. The half of the magnetic core close to the connection terminal is a high magnetic field B1, and the half of the magnetic core away from the connection terminal is a low magnetic field B2. Since the core temperature is closely related to the magnetic field distribution level, the magnetic core with severely uneven magnetic field distribution is prone to breakage due to uneven temperature distribution. Therefore, the practical value of the centralized connection terminals arranged on the long side is limited.

[0068] like Fig.15 As shown, the present invention provides a high-current planar transformer, showing another multi-layer PCB connection terminal arrangement suitable for high current. Specifically: in the first layer, the current flows in from the a end and flows out from the b1 end. At the b1 port of the first layer and the b2 port of the second layer, the first and second layers of PCB wire connection and current conduction are achieved by drilling and copper deposition. In the second layer, the current flows in from the b2 end and flows out from the c1 end. At the c1 port of the second layer and the c2 port of the third layer, the second and third layers of PCB wire connection and current conduction are achieved by drilling holes on the edge of the PCB and adding conductive columns. In the third layer, the current flows in from the c2 end and flows out from the d1 end. At the d1 port of the third layer and the d2 port of the fourth layer, the third and fourth layers of PCB wire connection and current conduction are achieved by drilling and copper deposition. In the fourth layer, the current flows in from the d2 end and flows out from the e end.

[0069] Fig.15 In the scheme shown, the arrangement position of the multi-layer PCB wire connection port is far away from the magnetic core, which will not cause serious uneven distribution of the magnetic field of the magnetic core. At the same time, because the connection ports are arranged in a distributed manner, scattered at edge 2, edge 3, and edge 4, the space utilization rate of the PCB board is improved, avoiding the additional increase of the wire loop length and the PCB board size to meet the space requirements of the high-current PCB wire connection.

[0070] pass Fig.16 and Fig.17 , a specific example of the present invention is described. The planar transformer in this example has a large current and uses 12 double-layer PCB boards, with a total of 24 PCB conductor layers.

[0071] Among them, PCB boards 1A, 1B, and 1C are arranged with primary wires. The primary side has 12 turns, and each PCB wire layer is arranged with 2 turns. Due to the large current, two layers of PCB wire layers need to be connected in parallel. Holes 121 and 127 are drilled at the edge of the PCB board, which serve as both the input and output terminals of the primary side and the parallel terminals of the multi-layer wires of the primary side. Holes 123 and 125 are drilled at the edge of the PCB board, which serve as the series terminals of the multi-layer wires of the primary side. Holes are drilled at the edge of the PCB board, and additional metal connecting columns are installed to achieve current conduction. At the same time, PCB board 1A is drilled with copper countersunk holes 122 to achieve conduction between wire layers 13A1 and 13A2. PCB board 1B is drilled with copper countersunk holes 124 to achieve conduction between wire layers 13B1 and 13B2. PCB board 1C is drilled with copper countersunk holes 126 to achieve conduction between wire layers 13C1 and 13C2.

[0072] PCB boards 1D and 1E are used to arrange the secondary side wires. The secondary side has 4 turns, and each PCB wire layer has 1 turn. Due to the large current, 3 layers of PCB wire layers need to be connected in parallel. Holes 128 and 1212 are drilled at the edge of the PCB board, which serve as both the input and output terminals of the secondary side and the parallel terminals of the multi-layer wires of the secondary side. Hole 1210 is drilled at the edge of the PCB board, which serves as the series terminal of the multi-layer wires of the secondary side. Holes are drilled at the edge of the PCB board, and additional metal connecting columns are installed to achieve current conduction. At the same time, PCB board 1D drills copper holes 129 to achieve conduction between wire layers 13D1 and 13D2. PCB board 1E drills copper holes 1211 to achieve conduction between wire layers 13E1 and 13E2.

[0073] like Fig.18 As shown, the present invention proposes that in the design of a high-current planar transformer, the wire connection ends between multi-layer PCBs are optimized from the traditional centralized arrangement to a distributed arrangement. The traditional solution only uses the installation positions on the two short sides of the PCB board. In the high-current scenario, the wire cross-sectional area is large, and the design space at the connection between layers is insufficient, so the size of the PCB board needs to be expanded. The present invention achieves the following beneficial effects by making full use of the installation positions on the four sides of the rectangular PCB board.

[0074] On the one hand, reducing the length of the PCB wire at the port connection reduces the loss of the copper wire, which is beneficial to improving the efficiency of the transformer. On the other hand, reducing the size of the PCB board in high-current application scenarios is beneficial to improving the power density of the transformer.

[0075] Therefore, in high current applications, the PCB wire connection ends of the planar transformer are dispersed on the long and short sides of the PCB board, and the connection ends should be away from the transformer core to avoid uneven distribution of the core magnetic field, thereby improving the efficiency and power density of the high current planar transformer.

[0076] The secondary side (or primary side) of the planar transformer uses multiple (greater than or equal to 2) PCB boards connected to each other (in series or in parallel), and multiple (greater than or equal to 3) connection ends of the secondary side (or primary side) are dispersedly arranged on multiple (greater than or equal to 1) edges of the PCB.

[0077] The above is only a preferred embodiment of the present invention, and does not limit the present invention in any form. Any technician familiar with the art can make many possible changes and modifications to the technical solution of the present invention by using the above disclosed methods and technical contents without departing from the scope of the technical solution of the present invention, or modify it into an equivalent embodiment of equivalent changes. Therefore, all equivalent changes made according to the shape, structure and principle of the present invention without departing from the content of the technical solution of the present invention should be included in the protection scope of the present invention.

Claims

1. A high current planar transformer, characterized in that: It includes a magnetic core and a plurality of PCB boards, and the plurality of PCB boards are arranged in layers; At least one layer of PCB conductors is provided on each PCB board, the PCB conductors are arranged in one turn or multiple turns, and the PCB conductors include two connection ports; When the PCB conductor is arranged in one turn: One connection port of each layer of PCB conductor is arranged on the PCB board, and the other connection port is arranged on the edge of the PCB board away from the magnetic core; The connection ports arranged at the edge of the PCB board away from the magnetic core are arranged in a cycle according to a specific position distribution, wherein a specific position distribution cycle is: one edge of the long side of the PCB board, one edge of the short side of the PCB board, one edge of the short side of the PCB board, and two edges of the long side of the PCB board.

2. A high current planar transformer as claimed in claim 1, characterized in that: The PCB conductor includes a current inflow port and a current outflow port; When the PCB conductor is arranged in one turn and has four layers of PCB conductors: The current inflow port of the first layer PCB conductor is arranged at an edge of the long side of the PCB board and away from the magnetic core, and the current outflow port is arranged on the PCB board; The current outflow port of the first layer PCB conductor is connected to the current inflow port of the second layer PCB conductor; The current inflow port of the second layer PCB conductor is arranged on the PCB board, and the current outflow port is arranged at an edge of the short side of the PCB board; The current outflow port of the second-layer PCB conductor is connected to the current inflow port of the third-layer PCB conductor; The current inflow port of the third layer PCB conductor is arranged at an edge of the short side of the PCB board, and the current outflow port is arranged on the PCB board; The current outflow port of the third-layer PCB conductor is connected to the current inflow port of the fourth-layer PCB conductor; The current inflow port of the fourth layer PCB conductor is arranged on the PCB board, and the current outflow port is arranged at the second edge of the long side of the PCB board and away from the magnetic core.

3. A high current planar transformer as claimed in claim 2, characterized in that: Drill holes at the edge of the PCB board and install conductive pillars to achieve current conduction between the connection ports arranged at the edge; Drill copper holes on the PCB board to achieve current conduction between the connection ports arranged on the PCB board.

4. A high current planar transformer as claimed in claim 2, characterized in that: When the PCB conductor is arranged with multiple turns: one connection port of each layer of the PCB conductor is arranged on the PCB board, and the other connection port is arranged at the position of the second edge of the short side of the PCB board.

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