Planar transformer and PCB winding cross layer changing structure

Abstract

The utility model relates to the technical field of planar transformers, in particular to a planar transformer and PCB winding cross layer changing structure. The PCB winding cross layer-changing structure comprises a first PCB and a second PCB, the second PCB and the first PCB are arranged in a stacked mode; the first winding is arranged on a part of the first PCB and a part of the second PCB; the second winding is arranged on the part, opposite to the first winding, of the first PCB and the part, opposite to the first winding, of the second PCB; one end of part of the first winding and one end of part of the second winding on the first PCB are connected in series, and one end of part of the first winding and one end of part of the second winding on the second PCB are connected in series. According to the planar transformer, the windings are crossed to change layers, the current of a loop formed by different windings, the rectifier tubes and the capacitors is forced to be equalized, and the planar transformer has the effects of reducing winding loss and facilitating the size reduction and power density improvement of the planar transformer.

Description

Technical Field

[0001] This utility model relates to the technical field of planar transformers, and in particular to a planar transformer and PCB winding cross-layer structure. Background Technology

[0002] A PCB-type planar transformer is a planar transformer that uses a printed circuit board (PCB) as its winding structure. It mainly consists of a magnetic core and a multi-layer PCB. Due to its small size and high power density, it is widely used in various power supply designs. With the development of power electronics technology, there are increasing demands for smaller size, larger winding current, and higher power density in PCB-type planar transformers. Therefore, the number of PCB winding layers and parallel components in planar transformers in power supplies is increasing. This poses significant challenges to PCB winding design, component layout, and return current layout, requiring special consideration of issues such as parallel current sharing of multi-layer windings, parallel current sharing of components, and parallel current sharing of current loops.

[0003] like Figure 1 The diagram shows a PCB winding structure 1 used in a planar transformer. The primary winding 11 includes a Z-layer winding, and the secondary winding 12 includes a first secondary winding 121 and a second secondary winding 122. The first secondary winding 121 is arranged on the X layer, and the second secondary winding 122 is arranged on the Y layer. The first secondary winding 121, capacitor Co11211, and rectifier SR1 1212 form a current loop i1, and the second secondary winding 122, capacitor Co21221, and rectifier SR2 1222 form a current loop i2. The outputs V+ of the two windings are connected through via Via11213, and the V- of the two windings are connected through via Via2 1223, jointly outputting a DC component.

[0004] In the existing PCB winding structure described above, the two windings belong to independent circuits and are located on different PCB layers, resulting in different coupling relationships. Furthermore, due to the different heat dissipation conditions of the windings on different PCB layers, the conductivity of the conductors varies, leading to uneven current distribution between the x-layer and y-layer windings. This can easily increase winding losses, reduce winding utilization, and consequently affect the performance of the PCB planar transformer. Utility Model Content

[0005] To address the issues of inconsistent coupling relationships and uneven current distribution in multi-layer windings of current PCB-type planar transformers, this invention aims to provide a cross-layer swapping structure for PCB windings of a planar transformer. This cross-layer swapping design forces current sharing across different layers of PCB windings, rectifier tubes, and capacitors, thereby balancing the temperature of different PCB layers and improving the performance of the planar transformer.

[0006] To achieve the objective of this utility model, a PCB winding cross-layer switching structure is provided, which adopts the following technical solution:

[0007] A PCB winding cross-layer switching structure includes:

[0008] First PCB board;

[0009] The second PCB board is stacked on top of the first PCB board;

[0010] The first winding is arranged on a portion of the first PCB board and a portion of the second PCB board;

[0011] The second winding is arranged on the portion of the first PCB board opposite to the first winding and on the portion of the second PCB board opposite to the first winding;

[0012] On the first PCB, a portion of the first winding and a portion of the second winding are connected in series at one end, and on the second PCB, a portion of the first winding and a portion of the second winding are connected in series at one end.

[0013] By adopting the above technical solution, a portion of the first winding circuits on the first PCB board and the second PCB board are interconnected to form a first winding circuit, and a portion of the second winding circuits on the first PCB board and the second PCB board are interconnected to form a second winding circuit. The two winding circuits are arranged vertically. Under this arrangement, for example, when the first winding and the second winding are used as secondary windings, no matter how the primary and secondary windings are distributed, the positions of the two secondary windings relative to the primary winding are always the same, which solves the problem of different coupling relationships caused by the different positions of the two sets of secondary windings relative to the primary winding.

[0014] Meanwhile, through the above technical solution, the current in the first winding and the current in the second winding can flow crosswise on the same PCB board. Part of the current in the first winding can flow into the second winding, and part of the current in the second winding can flow into the first winding, thereby achieving the effect of forcing the current in different windings and circuits to flow equally and improving the performance of the planar transformer.

[0015] The implementation can include any or all of the following features.

[0016] In some embodiments, the first windings on the first PCB board and the second PCB board are diagonally distributed, and the second windings on the first PCB board and the second PCB board are diagonally distributed. On the same PCB board, the current directions of the first winding and the second winding are the same.

[0017] The above technical solution provides a preferred arrangement of the first winding and the second winding, which not only enables the first winding and the second winding to form a complete winding circuit and allows the current in the first winding and the second winding to flow crosswise, but also allows the current component of the first winding in the first PCB board flowing downward into the first winding in the second PCB board to be opposite to and cancel out the current component of the second winding in the second PCB board flowing upward into the second winding in the first PCB board, so that there are through holes in the upper and lower PCB boards through which no current flows.

[0018] In some implementations, the first winding and the second winding on the first PCB board are connected in series through a first element, the input terminal of the first element is connected to the current output terminal of the first winding, and the output terminal of the first element is connected to the current input terminal of the second winding.

[0019] In some implementations, the first winding and the second winding on the second PCB are connected in series via a second element, wherein the input terminal of the second element is connected to the current output terminal of the second winding, and the output terminal of the second element is connected to the current input terminal of the first winding.

[0020] In some implementations, the first element and the second element are located on the same side of the first PCB board and the second PCB board.

[0021] In some implementations, the output of the first element is connected to a third element, and the output of the second element is connected to a fourth element.

[0022] In some embodiments, the first and second elements are capacitors, and the third and fourth elements are rectifiers.

[0023] In the above technical solution, by connecting half of the first winding and half of the second winding in the PCB board in series with a capacitor, impedance matching can be achieved between the winding and its preceding and following circuits. The high-frequency AC current component will take the path of least impedance, so that the AC current component of the first winding flows out of the first winding, flows through the first element and the third element, and then flows into the second winding. Similarly, the AC current component of the second winding flows out of the second winding, flows through the second element and the fourth element, and then flows into the first winding. This forces the AC components of the circuit composed of the first winding and the second and fourth elements to be the same as those of the circuit composed of the second winding and the first and third elements, effectively improving the current unevenness of the existing PCB winding structure.

[0024] In some embodiments, a portion of the first winding on the first PCB and a portion of the first winding on the second PCB are coupled; a portion of the second winding on the first PCB and a portion of the second winding on the second PCB are coupled.

[0025] In some implementations, the positive voltage output terminals of the first winding and the second winding are coupled, and the negative voltage output terminals of the first winding and the second winding are coupled.

[0026] In the above technical solution, the coupling can be achieved through a through hole, but is not limited to. When the connection is achieved through a through hole, the heat conduction path is increased, making the heat of the two windings more balanced, and further improving the situation of uneven current caused by different conductivity due to different temperatures.

[0027] This utility model also provides a planar transformer, which adopts the following technical solution:

[0028] A planar transformer includes a planar magnetic core, characterized in that it includes at least one PCB winding cross-swapping structure as described in any of the preceding claims, wherein the PCB winding cross-swapping structure and the planar magnetic core are fixedly connected.

[0029] In the above technical solution, the AC current component of the circuit composed of different windings, rectifier tubes and capacitors is forced to be equal by the cross-layer PCB winding structure. This allows the upper and lower sets of capacitors and rectifier tubes to bear the same AC current component, avoiding the problems of large current stress on rectifier tubes and capacitors on one side and uneven current between circuits composed of different windings, rectifier tubes and capacitors, thereby improving the performance of the planar transformer.

[0030] In summary, this utility model provides a planar transformer PCB winding cross-layer switching structure, which has the following beneficial effects:

[0031] First, under the winding distribution structure of this application, when the cross-layer PCB winding structure of this application is used as the secondary winding, no matter how the primary and secondary windings are distributed, the positions of the two secondary windings relative to the primary winding are always the same, which solves the problem of different coupling relationships caused by the different positions of the two sets of secondary windings relative to the primary winding.

[0032] Second, by designing the winding connection method, the current component in the circuit composed of the first winding, the first element, and the third element is forced to be the same as the current component in the circuit composed of the second winding, the second element, and the fourth element. This ensures that the AC current component borne by the capacitors and rectifier tubes of the upper and lower windings is the same, thus avoiding the problem of high current stress on the capacitors and rectifier tubes on one side.

[0033] Third, the winding circuits on the PCB are split and rearranged so that one winding is distributed on the upper and lower PCBs, which can balance the temperature of different PCBs and improve the performance of the planar transformer.

[0034] Fourth, the two windings are connected by multiple sets of through holes, which increases the heat conduction path and makes the heat of the two parts more balanced. At the same time, it can also improve the situation of uneven DC current caused by different conductivity due to different temperatures. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of an existing PCB winding structure;

[0036] Figure 2 This is a schematic diagram of the PCB winding cross-layer replacement structure of this application;

[0037] Figure 3 This is a schematic diagram of the PCB winding cross-layer switching structure applied to the primary winding in this application;

[0038] Figure 4 This is a schematic diagram of a planar transformer that utilizes the PCB winding cross-layer switching structure of this application.

[0039] Explanation of reference numerals in the attached figures:

[0040] 1. Existing PCB winding structure;

[0041] 11. Primary winding;

[0042] 12. Secondary winding; 121. First secondary winding; 1211. Capacitor Co1; 1212. Rectifier tube SR1; 1213. Through hole Via1; 122. Second secondary winding; 1221. Capacitor Co2; 1222. Rectifier tube SR2; 1223. Through hole Via2;

[0043] 2. PCB winding cross-layer switching structure;

[0044] 21. First PCB board;

[0045] 22. Second PCB board;

[0046] 23. First winding; 231. Upper part of first winding; 232. Lower part of first winding; 233. First element; 234. Third element;

[0047] 24. Second winding; 241. Upper part of second winding; 242. Lower part of second winding; 243. Second element; 244. Fourth element;

[0048] 25. First through hole;

[0049] 26. Second through hole;

[0050] 27. Third through hole;

[0051] 28. Fourth through hole;

[0052] 3. Planar magnetic core;

[0053] 4. PCB layered structure; 41. Primary winding PCB board; 42. Secondary winding PCB board. Detailed Implementation

[0054] To make the objectives and technical solutions of the present utility model clearer, the technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present utility model. All other embodiments obtained by those skilled in the art based on the described embodiments of the present utility model without creative effort are within the scope of protection of the present utility model. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. The directional terms mentioned in the following embodiments, such as up, down, left, right, front, back, bottom, and top, are only for reference to the accompanying drawings. Therefore, the directional terms used are for illustrative purposes and not for limiting the present utility model.

[0055] Figure 1 This is a schematic diagram of the existing PCB winding structure 1 in a planar transformer. The Z layer is arranged as the primary winding 11, and the X and Y layers are arranged as the secondary windings 12. Specifically, the X layer is arranged as the first secondary winding 121, and the Y layer is arranged as the second secondary winding 122. The first secondary winding 121, together with capacitor Co1 1211 and rectifier SR1 1212, forms a first current loop, and the current flowing through the first current loop is i1. The second secondary winding 122, together with capacitor Co2 1221 and rectifier SR2 1222, forms a second current loop, and the current flowing through the second current loop is i2. The outputs of the two windings are connected through vias Via1 1213 and Via2 1223, respectively, and together output a DC component.

[0056] This winding structure presents several problems. For example, when the positions of the first secondary winding 121 or the second secondary winding 122 relative to the primary winding 11 are different, the coupling relationships between the two secondary windings 12 and the primary winding 11 are not the same. Therefore, the magnitudes of the induced currents in the first secondary winding 121 and the second secondary winding 122 will also differ. On the other hand, the current loops formed by the two secondary windings 12 are relatively independent, and inconsistencies in the rectifier diodes, capacitors, and loop parameters can lead to uneven current distribution in the two loops. Moreover, because the two secondary windings 12 are located at different positions in the PCB stack-up, and the heat dissipation conditions of the windings in different PCB layers are different, the conductivity of conductors at different temperatures is different, resulting in uneven current distribution between the x-layer and y-layer windings. This poses a severe challenge to the design of the winding stack-up structure.

[0057] This utility model first discloses a PCB winding cross-layer switching structure 2, which can effectively improve the problems of different coupling relationships and uneven current distribution in the above-mentioned PCB winding structures. (Refer to...) Figure 2 The Z-th layer winding is the primary winding, and the PCB winding cross-layer structure 2 is the secondary winding, which includes at least a first PCB board 21 and a second PCB board 22. The first PCB board 21 and the second PCB board 22 are stacked, and the first winding 23 and the second winding 24 are also cross-arranged on the first PCB board 21 and the second PCB board 22.

[0058] Specifically, refer to Figure 2 The windings on the first PCB board 21 include an upper first winding 231 and an upper second winding 241, and the windings on the second PCB board 22 include a lower first winding 232 and a lower second winding 242. The upper first winding 231 and the lower first winding 232 are diagonally distributed, and the upper second winding 241 and the lower second winding 242 are also diagonally distributed. The windings on the first PCB board 21 are designated as the Xth layer windings, and the windings on the second PCB board 22 are designated as the Yth layer windings. Preferably, the lengths of the upper first winding 231 and the upper second winding 241 are each half the total length of the Xth layer windings, and the lengths of the lower first winding 232 and the lower second winding 242 are each half the total length of the Yth layer windings.

[0059] Reference Figure 2 As an example, the upper first winding 231 is located in the rear half of the first PCB board 21, the lower first winding 232 is located in the front half of the second PCB board 22, the upper second winding 241 is located in the front half of the first PCB board 21, and the lower second winding 242 is located in the rear half of the second PCB board 22, forming a winding layout in which the lines connecting the upper first winding 231 and the lower first winding 232 intersect with the lines connecting the upper second winding 241 and the lower second winding 242. In the same PCB board or the same layer of windings, the current flowing through the first winding 23 and the second winding 24 is in the same direction. For example, in the Xth layer of windings, the current in the upper first winding 231 and the upper second winding 241 is in the same direction. In this winding layout, the first winding 23 and the second winding 24 form a complete winding loop. On the same PCB plane, a portion of the current between the two windings (23; 24) flows between them, achieving a current sharing effect.

[0060] Furthermore, the upper first winding 231 and the upper second winding 241 are spaced apart at their closest ends, and connected in series at their other ends via a first element 233. Similarly, the lower first winding 232 and the lower second winding 242 are spaced apart at their closest ends, and connected in series at their other ends via a second element 243. The first element 233 and the second element 243 are located on the same side of the first PCB board 21 and the second PCB board 22. At the end where the first winding 23 and the second winding 24 are spaced apart, the upper first winding 231 and the lower first winding 232 are connected via a first through hole 25, and the upper second winding 241 and the lower second winding 242 are connected via a second through hole 26. The positive pressure ends of the first winding 23 and the second winding 24 are connected via a third through hole 27, and the negative pressure ends of the first winding 23 and the second winding 24 are connected via a fourth through hole 28. Thus, the two windings are connected by multiple through holes, increasing the heat conduction path and making the heat of the two windings more even.

[0061] Reference Figure 2 The first winding, second element 243, and fourth element 244 form a circuit, and the second winding 24, first element 233, and third element 234 form a circuit. To force the AC current component in the circuit formed by the first winding, second element 243, and fourth element 244 to be the same as the AC current component in the circuit formed by the second winding, first element 233, and third element 234, the input terminal of the first element 233 is connected to the current output terminal of the upper part of the first winding 231, and the output terminal of the first element 233 is connected to the current input terminal of the upper part of the second winding 241. The output terminal of the first element 233 is connected to the second winding 24 and then to the third element 234. The input terminal of the second element 243 is connected to the current output terminal of the lower part of the second winding 242, and the output terminal of the second element 243 is connected to the current input terminal of the lower part of the first winding 232. The output terminal of the second element 243 is connected to the first winding 23 and then to the fourth element 244. The first element 233 and the second element 243 are preferably capacitors, and the third element 234 and the fourth element 244 are preferably rectifiers.

[0062] The implementation principle of a PCB winding cross-layer switching structure according to this utility model embodiment is as follows:

[0063] Reference Figure 2 As an example, in the PCB winding cross-layer structure 2 of this application, the first PCB board 21 is located on the Xth layer, the second PCB board is located on the Yth layer, the first winding 23 and the second winding 24 serve as secondary windings, and the windings on the Zth layer PCB board serve as primary windings. Under this winding distribution structure of this application, regardless of how the primary and secondary windings are distributed, the positions of the two secondary windings relative to the primary windings are always the same, solving the problem of different coupling relationships caused by the different positions of the two sets of secondary windings relative to the primary winding.

[0064] Reference Figure 2 Let i1 be the AC current component flowing through the first winding 23, and let i1 be the current direction indicated by arrow A in the figure. Let i2 be the AC current component flowing through the second winding 24, and let i2 be the current direction indicated by arrow B in the figure. Figure 2 In the winding configuration, after i1 flows out of the first winding 23, a portion may flow downwards through the third through-hole 27 into the second element 243, while another portion may flow into the first element 233. After i2 flows out of the second winding 24, a portion may flow upwards through the third through-hole 27 into the first element 233, while another portion may flow into the second element 243. High-frequency AC components follow the path of least impedance. The first element 233 has the least impedance to i1, and the second element 243 has the least impedance to i2. Even if current flows into the third through-hole 27, the current paths of i1 and i2 in the third through-hole 27 are opposite and cancel each other out. That is, in the winding layout connection of this invention, no current flows through the third through-hole 27. The current path is as follows: Figure 2 As shown, the AC current component i1 of the first winding 23 flows out of the winding, passes through the first element 233 and the third element 234, and then flows into the second winding 24. Similarly, the AC current component i2 of the second winding 24 flows out of the winding, passes through the second element 243 and the fourth element 244, and then flows into the first winding 23. This forces i1 and i2 to be the same, effectively solving the problem of uneven current between the upper and lower PCB windings. It also ensures that the AC current component borne by the upper and lower winding circuits, including capacitors (233; 243) and rectifier tubes (234; 244), is the same, avoiding the problem of high current stress on capacitors and rectifier tubes on one side of the circuit. At the same time, the two windings (23; 24) are connected by multiple through holes, including the first through hole 25, the second through hole 26, the third through hole 27, and the fourth through hole 28, increasing the heat conduction path and making the heat of the two windings more balanced. Therefore, it can also improve the situation of uneven current caused by different conductivity due to different temperatures.

[0065] Reference Figure 2 Although the first winding 23 and the second winding 24 shown in the figure are circular, this is only an example and does not constitute a unique limitation on the shape of the first winding 23 and the second winding 24. For example, the first winding 23 and the second winding 24 can also be square.

[0066] This PCB winding structure of the present application can be used not only as a secondary winding, but also, as shown in the reference... Figure 3 In other embodiments, it can also be used as a primary winding structure in two stacked PCBs. Figure 3 In the circuit, the PCB winding cross-swapping structure 2 formed by the Xth and Yth layers serves as the secondary winding, and the PCB winding cross-swapping structure 2 formed by the Wth and Zth layers serves as the primary winding.

[0067] This invention, through winding cross-layer switching, eliminates the coupling relationship between the primary and secondary windings from the positional limitation of the two secondary windings relative to the primary winding. It also forces the current to be evenly distributed across the circuits composed of different windings, rectifier tubes, and capacitors, thereby balancing the temperature of different PCB layers. This reduces winding losses and facilitates the reduction of planar transformer size and the increase of power density.

[0068] Reference Figure 4 This utility model also discloses a planar transformer using the above-mentioned PCB winding cross-layer structure 2, including a planar magnetic core 3 and a PCB stack-up structure 4, wherein the planar magnetic core 3 and the PCB stack-up structure 4 are fixedly connected. As an example, the shape and structure of the planar magnetic core 3, the shape and number of layer pairs of the PCB stack-up structure 4, and the connection method between the planar magnetic core 3 and the PCB stack-up structure 4 may be, but are not limited to, other than... Figure 4 As shown, other existing technologies can also be used, along with other conventional structures for connecting planar transformers.

[0069] Reference Figure 4 The PCB stack-up structure 4 includes a primary winding PCB board 41 and a secondary winding PCB board 42. The primary winding PCB board 41 and the secondary winding PCB board 42 are alternately stacked. Two secondary winding PCB boards 42 or two primary winding PCB boards 41 utilize the aforementioned PCB winding cross-layer structure 2. Figure 4 As an example, the PCB winding cross-layer structure 2 is applied to the two secondary winding PCB boards 42.

[0070] Reference Figure 4 In a multilayer PCB planar transformer including the PCB winding cross-swapping structure 2, the PCB winding cross-swapping structure 2 is arranged in a position that makes the entire PCB stack-up structure 4 horizontally symmetrical. In other embodiments, the PCB winding cross-swapping structure 2 can also be arranged in a position that makes the entire PCB stack-up structure 4 non-horizontally symmetrical; for example, the PCB winding cross-swapping structure 2 can be applied to... Figure 4 The PCB stack-up structure 4 described herein consists of the first secondary winding PCB board 42 and the second secondary winding PCB board 42 arranged from top to bottom.

[0071] Of course, the above embodiments are the preferred embodiments of this utility model, and are only used to illustrate the technical concept and features of this utility model. Their purpose is to enable those skilled in the art to understand the content of this utility model and implement it accordingly, and should not be used to limit the protection scope of this utility model. All modifications made in accordance with the spirit and essence of the main technical solution of this utility model should be included within the protection scope of this utility model.

Claims

1. A PCB winding crossover interleaving structure, characterized in that, The application relates to a PCB winding cross-layer structure. The application relates to a PCB winding cross-layer structure. The application relates to a PCB winding cross-layer structure. The application relates to a PCB winding cross-layer structure. The application relates to a PCB winding cross-layer structure. The application relates to a PCB winding cross-layer structure.

2. The PCB winding crossover interleaving structure of claim 1, wherein, The application relates to a PCB winding cross-layer structure.

3. A PCB winding crossover interleaving structure as claimed in claim 2, wherein, The application relates to a PCB winding cross-layer structure.

4. The PCB winding crossover interleaving structure of claim 3, wherein, The application relates to a PCB winding cross-layer structure.

5. A PCB winding crossover interleaving structure as claimed in claim 4, wherein, The application relates to a PCB winding cross-layer structure.

6. A PCB winding crossover interleaving structure as claimed in claim 5, wherein, The application relates to a PCB winding cross-layer structure.

7. A PCB winding crossover interleaving structure as claimed in claim 6, wherein, The application relates to a PCB winding cross-layer structure.

8. The PCB winding crossover layer- change structure of claim 1, wherein, The application relates to a PCB winding cross-layer structure. The application relates to a PCB winding cross-layer structure.

9. The PCB winding crossover layer- crossing structure of claim 1, wherein, The application relates to a PCB winding cross-layer structure.

10. A planar transformer comprising a planar magnetic core, characterized by The application relates to a PCB winding cross-layer structure. The application relates to a PCB winding cross-layer structure. The application relates to a PCB winding cross-layer structure. The application relates to a PCB winding cross-layer structure. The application relates to a PCB winding cross-layer structure. The application relates to a PCB winding cross-layer structure. The application relates to a PCB winding cross-layer structure. The application relates to a PCB winding cross-layer structure. The application relates to a PCB winding cross-layer structure. The application relates to a PCB winding cross-layer structure. The application relates to a PCB winding cross-layer structure. The application relates to a PCB winding cross-layer structure. The application relates to a PCB winding cross-layer structure. The application relates to a PCB winding cross-layer structure. 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