Two-winding planar transformer and printed circuit board for the same

Abstract

An embodiment of the present invention relates to a dual-winding planar transformer and a printed circuit board for the dual-winding planar transformer. The planar transformer includes a first primary winding, a second primary winding, and a secondary winding, which are constructed on four stacked PCB layers, wherein the first primary winding is constructed on the first and second PCB layers, the second primary winding is constructed on the fourth and third PCB layers, and the secondary winding is constructed on the second and third PCB layers. Each PCB layer includes through holes for connecting the primary and secondary windings, and electrical connections between the windings at each level are achieved through access through holes and access through holes on each PCB layer. The planar transformer ensures electrical connection and energy transfer between the windings through a reasonable layout and winding design. The dual-winding planar transformer proposed in the present invention has a simple processing technology, low cost, and is conducive to mass production.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic power, and in particular to a double-winding planar transformer and a printed circuit board for the double-winding planar transformer. Background Art

[0002] With the widespread adoption of fast-charging technology, miniaturization and higher frequencies have become key development trends in switching power supplies. The bulk and weight of traditional wound transformers limit the miniaturization of power supplies. Increasing the switching frequency helps reduce the size and weight of magnetic components. Planar transformers have gained widespread application in switching power supplies in recent years due to their compact size, high operating frequency, ease of achieving a flatter structure, and excellent heat dissipation performance and consistency.

[0003] PCB-type planar transformers utilize a printed circuit board (PCB) as their winding structure. While traditional transformers typically use coils wound around an iron core, PCB-type planar transformers utilize copper foil coils designed on a multilayer PCB as their windings, replacing the traditional wire-wound structure. Because they eliminate the winding bobbin, PCB-type planar transformers are ideal for high-power density and high-frequency switching power supplies.

[0004] PCB-based planar transformers primarily consist of two components: a magnetic core and a multi-layer PCB. Traditional PCB-based planar transformers typically use an eight-layer PCB, which is both bulky and expensive.

[0005] Furthermore, the manufacturing process for PCB-based planar transformers requires the use of vias to connect copper foils on different layers. Due to the magnetic core and multi-layer PCB structure of existing PCB-based transformers, complex buried or blind via processes are often required. These complex processes increase manufacturing difficulty and are a key factor hindering the large-scale application of PCB-based planar transformers.

[0006] Therefore, the number of layers of the transformer PCB and the appropriate processing technology in the PCB type planar transformer are important indicators for considering the planar transformer. Summary of the Invention

[0007] The present invention addresses the shortcomings of the prior art by providing a dual-winding planar transformer and a printed circuit board (PCB) for such a transformer. By optimizing the PCB structure, the vias are adapted using only through-hole technology. A rational routing design is implemented for the first primary winding, the second primary winding, and the secondary winding based on the PCB, eliminating the need for a conventional additional power supply winding. The dual-winding planar transformer proposed in this invention features a simple manufacturing process, low cost, and is suitable for mass production.

[0008] To achieve the above object, the present invention provides a dual-winding planar transformer, comprising: a first primary winding, a second primary winding, and a secondary winding;

[0009] The dual-winding planar transformer is constructed on four layers of printed circuit boards (PCBs) stacked sequentially, wherein the first primary winding is constructed on the first and second layers of PCBs, the second primary winding is constructed on the fourth and third layers of PCBs, and the secondary winding is constructed on the second and third layers of PCBs;

[0010] Each layer of the PCB includes: a first like-name terminal, a first opposite-name terminal, a second like-name terminal, and a second opposite-name terminal arranged on a first side; a secondary like-name terminal and a secondary opposite-name terminal arranged on a second side; two rows of through-holes for electrical connection of the primary winding arranged in the middle of the PCB; and a group of through-holes for electrical connection of the secondary winding arranged between the secondary like-name terminals and the secondary opposite-name terminals; wherein each of the two rows of through-holes for electrical connection of the primary winding includes an input through-hole and an output through-hole; the second row of input through-holes on the second layer of the PCB are electrically connected to the first row of output through-holes via a first electrical connection line; and the first row of input through-holes on the third layer of the PCB are electrically connected to the second row of output through-holes via a second electrical connection line.

[0011] A first primary winding and a second primary winding are provided on the first layer PCB; one end of the first primary winding is connected to the first like-name terminal B, wound half a turn in the first direction, and the other end is connected to the second row of access through holes; one end of the second primary winding is connected to the first row of access through holes, wound N turns plus half a turn in the first direction, and the other end is connected to the first unlike-name terminal A; N is a positive integer greater than 2;

[0012] A first secondary winding is provided on the second layer PCB; one end of the first secondary winding is connected to the secondary same-name terminal F, wound one circle along the first direction, and the other end is connected to the through hole for electrical connection of the secondary winding;

[0013] A second secondary winding is provided on the third layer PCB; one end of the second secondary winding is connected to the through hole for electrical connection of the secondary winding, wound one circle along the first direction, and the other end is connected to the secondary opposite-name terminal E;

[0014] A third primary winding and a fourth primary winding are provided on the fourth layer PCB; one end of the third primary winding is connected to the second like-name terminal D, is wound M turns plus half a turn in the first direction, and the other end is connected to the first row of access through holes; one end of the fourth primary winding is connected to the second row of access through holes, is wound half a turn in the first direction, and the other end is connected to the second unlike-name terminal C; M is a positive integer greater than 2.

[0015] Preferably, the first primary winding, the first electrical connection line and the second primary winding constitute the first primary winding;

[0016] The first primary winding starts from the first like-name terminal B on the first layer PCB, is wound half a turn in the first direction, is connected to the second row of access through-holes on the second layer PCB through the second row of access through-holes, is connected through the first row of output through-holes on the second layer PCB, and is then connected back to the first row of output through-holes on the first layer PCB, and continues to be wound N turns plus half a turn in the first direction, and is connected to the first opposite-name terminal A.

[0017] Preferably, the first secondary winding and the second secondary winding constitute the secondary winding;

[0018] The secondary winding has one end connected to the secondary same-name terminal F on the second-layer PCB, is wound one circle along the first direction, is connected to the through-hole for secondary winding electrical connection on the third-layer PCB through the through-hole for secondary winding electrical connection on the second-layer PCB, is wound one circle along the first direction again, and the other end is connected to the secondary opposite-name terminal E.

[0019] Preferably, the third primary winding, the second electrical connection line and the fourth primary winding constitute the second primary winding;

[0020] The second primary winding starts from the second like-name terminal D on the fourth layer PCB, is wound M turns plus half a turn in the first direction, is connected to the first row of access through holes on the third layer PCB through the first row of access through holes, is connected through the second row of output through holes on the third layer PCB, and is then connected back to the second row of output through holes on the fourth layer PCB, continues to be wound half a turn in the first direction, and is connected to the second opposite-name terminal C.

[0021] Preferably, M=N.

[0022] In a second aspect, an embodiment of the present invention provides a printed circuit board for the dual-winding planar transformer according to the first aspect, the printed circuit board comprising:

[0023] A first same-name end, a first different-name end, a second same-name end, and a second different-name end provided on the first side;

[0024] A secondary homonymous terminal and a secondary heteronymous terminal are provided on the second side;

[0025] Two rows of through holes for electrical connection of the primary winding are provided in the middle of the printed circuit board; each row of the two rows of through holes for electrical connection of the primary winding includes an input through hole and an output through hole;

[0026] A group of through holes for electrical connection of the secondary winding is arranged between the secondary like-name terminal and the secondary unlike-name terminal.

[0027] Preferably, the two rows of through holes for electrical connection of the primary winding, wherein the connection between the access through holes in one row and the output through holes in the other row is used for electrical connection of the primary winding.

[0028] The dual-winding planar transformer provided in this embodiment optimizes the PCB structure, enabling the adaptation of vias using only through-hole technology. Based on the PCB structure, the first primary winding, the second primary winding, and the secondary winding are rationally designed for routing, eliminating the need for traditional additional power supply windings. The dual-winding planar transformer proposed in this invention features a simple manufacturing process, low cost, and is suitable for mass production. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1A A schematic structural diagram of the first layer of a dual-winding planar transformer provided in an embodiment of the present invention;

[0030] Figure 1B A schematic structural diagram of the second layer of a dual-winding planar transformer provided in an embodiment of the present invention;

[0031] Figure 1C A schematic structural diagram of the third layer of a dual-winding planar transformer provided in an embodiment of the present invention;

[0032] Figure 1D A schematic structural diagram of the fourth layer of a dual-winding planar transformer provided in an embodiment of the present invention;

[0033] Figure 2 A schematic diagram of a single-layer structure of a printed circuit board provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0034] To make the objectives, technical solutions, and advantages of the present invention more apparent, the present invention will be further described in detail below with reference to the accompanying drawings. It is apparent that the embodiments described are only some, not all, of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are intended to fall within the scope of protection of the present invention.

[0035] An embodiment of the present invention provides a dual-winding planar transformer, comprising a first primary winding, a second primary winding, and a secondary winding.

[0036] The dual-winding planar transformer is constructed on four layers of printed circuit boards (PCBs) stacked sequentially, as shown in AD in Figure 1 from the first layer to the fourth layer, respectively. The first primary winding is constructed on the first and second layers of the PCB, the second primary winding is constructed on the fourth and third layers of the PCB, and the secondary winding is constructed on the second and third layers of the PCB.

[0037] The structure of each layer of the printed circuit board (PCB) is as follows Figure 2 Shown, including:

[0038] A first same-name end B, a first different-name end A, a second same-name end D, and a second different-name end C are provided on the first side;

[0039] A secondary same-name terminal F and a secondary different-name terminal E provided on the second side;

[0040] Two rows of through holes for electrical connection of the primary winding are provided in the middle of the printed circuit board; wherein each row includes an inlet through hole and an outlet through hole; Figure 2 As shown, it specifically includes a first row of access through-holes 201, a first row of access through-holes 202, a second row of access through-holes 203, and a second row of access through-holes 204. Of the two rows of through-holes used for electrical connection of the primary winding, the connection between the access through-holes in one row and the access through-holes in the other row is used for electrical connection of the primary winding.

[0041] A set of through holes 205 for electrical connection of the secondary winding is provided between the secondary like-name terminal and the secondary unlike-name terminal.

[0042] The printed circuit board (PCB) of each layer of the dual-winding planar transformer of the present invention has the same structure, which can greatly save costs.

[0043] Combined with Figure 1 and Figure 2 Based on the above PCB structure, the second row of access through holes 203 on the second layer PCB and the first row of access through holes 202 are electrically connected through the first electrical connection line 41; the first row of access through holes 201 on the third layer PCB and the second row of access through holes 204 are electrically connected through the second electrical connection line 42.

[0044] A first primary winding 11 and a second primary winding 12 are provided on the first layer PCB; one end of the first primary winding 11 is connected to the first like-name terminal B, wound half a circle in the first direction, and the other end is connected to the second row of access through-holes 203; one end of the second primary winding 12 is connected to the first row of access through-holes 201, wound N circles plus half a circle in the first direction, and the other end is connected to the first unlike-name terminal A; N is a positive integer greater than 2; in the illustration of the present invention, the first direction is clockwise, but in actual implementation, it can also be counterclockwise.

[0045] A first secondary winding 21 is provided on the second layer PCB; one end of the first secondary winding 21 is connected to the secondary same-name terminal F, wound one circle along the first direction, and the other end is connected to the through hole 205 for electrical connection of the secondary winding.

[0046] A second secondary winding 22 is provided on the third layer PCB; one end of the second secondary winding is connected to the through hole 205 for electrical connection of the secondary winding, and is wound one circle along the first direction, and the other end is connected to the secondary opposite-name terminal E.

[0047] A third primary winding 31 and a fourth primary winding 32 are provided on the fourth layer PCB; one end of the third primary winding 31 is connected to the second like-name terminal D, is wound M turns plus half a turn in the first direction, and the other end is connected to the first row of access holes 201; one end of the fourth primary winding 32 is connected to the second row of access holes 204, is wound half a turn in the first direction, and the other end is connected to the second unlike-name terminal C; M is a positive integer greater than 2.

[0048] Through the above-mentioned 4-layer PCB and electrical connection settings, the construction of the first primary winding, the second primary winding and the secondary winding is achieved.

[0049] The first primary winding 11, the first electrical connection line 41, and the second primary winding 12 constitute the first primary winding. The first primary winding begins at the first like-named terminal B on the first layer PCB. After winding half a turn in the first direction, the first primary winding 11 is connected to the second row of access holes 203 on the second layer PCB through the second row of access holes 203 on the first layer PCB. Then, through the first electrical connection line 41, it is connected to the first row of access holes 202 on the second layer PCB, and then back to the first row of access holes 202 on the first layer PCB. The second primary winding 12 continues winding N turns plus half a turn in the first direction, connecting to the first opposite-named terminal A.

[0050] The first secondary winding 21 and the second secondary winding 22 constitute the secondary winding. The secondary winding begins at the secondary like-name terminal F on the second-layer PCB, winds around the first secondary winding 21 for one turn in the first direction, connects to the secondary electrical connection through-hole 205 on the second-layer PCB, and winds around the second secondary winding 22 for another turn in the first direction, with the other end connected to the secondary opposite-name terminal E.

[0051] The third primary winding 31, the second electrical connection line 41, and the fourth primary winding 32 constitute the second primary winding. The second primary winding begins at the second like-name terminal D on the fourth-layer PCB. After winding the third primary winding 31 for M turns plus a half turn in the first direction, it connects from the first row of access vias 201 on the fourth-layer PCB to the first row of access vias 201 on the third-layer PCB. Then, through the second electrical connection line 41, it connects through the second row of exit vias 204 on the third-layer PCB, and then back to the second row of exit vias 204 on the fourth-layer PCB. It continues winding half a turn in the first direction, and connects to the second opposite-name terminal C.

[0052] In the specific example shown in FIG1 , N=M=6. That is, the first primary winding and the second primary winding are both wound 7 turns in the clockwise direction, and the secondary winding is wound 2 turns in the clockwise direction.

[0053] It can be understood that the specific values ​​of N and M can be adjusted according to circuit function requirements in specific implementations, and the values ​​of M and N can be equal or different.

[0054] In the dual-winding planar transformer of this invention, the primary and secondary windings are implemented using copper wire routing within a multilayer PCB, leveraging the PCB's multilayer structure and through-holes for electrical connection. This PCB structure not only provides electrical connection for the windings but also optimizes the routing to meet the specific voltage and current requirements of the circuit. Precisely designed winding turns and via placement allow the secondary circuit to directly receive the required voltage and current through the PCB, eliminating the need for additional power windings in traditional transformers.

[0055] The dual-winding planar transformer provided by the present invention is based on an optimized design of a PCB structure. Through a reasonable routing layout and via connections, the windings are formed directly on a multi-layer PCB. This structure allows multiple windings to share the same PCB, reducing the need for physical coils. At the same time, the electromagnetic coupling between the primary and secondary windings is optimized, providing a stable output voltage. Therefore, a traditional additional power supply winding is no longer required, and a stable voltage can be directly provided to the secondary circuit, reducing the need for an auxiliary power supply.

[0056] By designing the winding structure on a PCB, the winding manufacturing process is greatly simplified. While the additional power supply winding of a traditional transformer requires a separate winding process, the winding structure designed with the present invention can be completed directly during PCB manufacturing, using only through-hole technology. This not only saves material for the additional power supply winding, but also simplifies the entire manufacturing process and reduces the number of process steps.

[0057] The dual-winding planar transformer provided in this embodiment optimizes the PCB structure, enabling the adaptation of vias using only through-hole technology. Based on the PCB structure, the first primary winding, the second primary winding, and the secondary winding are rationally designed for routing, eliminating the need for traditional additional power supply windings. The dual-winding planar transformer proposed in this invention features a simple manufacturing process, low cost, and is suitable for mass production.

[0058] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A double-winding planar transformer, characterized in that: The dual-winding planar transformer comprises: a first primary winding, a second primary winding and a secondary winding; The dual-winding planar transformer is constructed on four layers of printed circuit boards (PCBs) stacked sequentially, wherein the first primary winding is constructed on the first and second layers of PCBs, the second primary winding is constructed on the fourth and third layers of PCBs, and the secondary winding is constructed on the second and third layers of PCBs; Each layer of the PCB includes: a first like-name terminal, a first opposite-name terminal, a second like-name terminal, and a second opposite-name terminal arranged on a first side; a secondary like-name terminal and a secondary opposite-name terminal arranged on a second side; two rows of through-holes for electrical connection of the primary winding arranged in the middle of the PCB; and a group of through-holes for electrical connection of the secondary winding arranged between the secondary like-name terminals and the secondary opposite-name terminals; wherein each of the two rows of through-holes for electrical connection of the primary winding includes an input through-hole and an output through-hole; the second row of input through-holes on the second layer of the PCB are electrically connected to the first row of output through-holes via a first electrical connection line; and the first row of input through-holes on the third layer of the PCB are electrically connected to the second row of output through-holes via a second electrical connection line. A first primary winding and a second primary winding are provided on the first layer PCB; one end of the first primary winding is connected to the first like-name terminal B, wound half a turn in the first direction, and the other end is connected to the second row of access through holes; one end of the second primary winding is connected to the first row of access through holes, wound N turns plus half a turn in the first direction, and the other end is connected to the first unlike-name terminal A; N is a positive integer greater than 2; A first secondary winding is provided on the second layer PCB; one end of the first secondary winding is connected to the secondary same-name terminal F, wound one circle along the first direction, and the other end is connected to the through hole for electrical connection of the secondary winding; A second secondary winding is provided on the third layer PCB; one end of the second secondary winding is connected to the through hole for electrical connection of the secondary winding, wound one circle along the first direction, and the other end is connected to the secondary opposite-name terminal E; A third primary winding and a fourth primary winding are provided on the fourth layer PCB; one end of the third primary winding is connected to the second like-name terminal D, is wound M turns plus half a turn in the first direction, and the other end is connected to the first row of access through holes; one end of the fourth primary winding is connected to the second row of access through holes, is wound half a turn in the first direction, and the other end is connected to the second unlike-name terminal C; M is a positive integer greater than 2.

2. The dual-winding planar transformer according to claim 1, characterized in that: The first primary winding, the first electrical connection line and the second primary winding constitute the first primary winding; The first primary winding starts from the first like-name terminal B on the first layer PCB, is wound half a turn in the first direction, is connected to the second row of access through-holes on the second layer PCB through the second row of access through-holes, is connected through the first row of output through-holes on the second layer PCB, and is then connected back to the first row of output through-holes on the first layer PCB, and continues to be wound N turns plus half a turn in the first direction, and is connected to the first opposite-name terminal A.

3. The double-winding planar transformer according to claim 1, characterized in that: The first secondary winding and the second secondary winding constitute the secondary winding; The secondary winding has one end connected to the secondary same-name terminal F on the second-layer PCB, is wound one circle along the first direction, is connected to the through-hole for secondary winding electrical connection on the third-layer PCB through the through-hole for secondary winding electrical connection on the second-layer PCB, is wound one circle along the first direction again, and the other end is connected to the secondary opposite-name terminal E.

4. The dual-winding planar transformer according to claim 1, characterized in that: The third primary winding, the second electrical connection line and the fourth primary winding constitute the second primary winding; The second primary winding starts from the second like-name terminal D on the fourth layer PCB, is wound M turns plus half a turn in the first direction, is connected to the first row of access through holes on the third layer PCB through the first row of access through holes, is connected through the second row of output through holes on the third layer PCB, and is then connected back to the second row of output through holes on the fourth layer PCB, continues to be wound half a turn in the first direction, and is connected to the second opposite-name terminal C.

5. The dual-winding planar transformer according to claim 1, wherein: M=N.

6. A printed circuit board for a double-winding planar transformer according to any one of claims 1 to 5, characterized in that: The printed circuit board comprises: A first same-name end, a first different-name end, a second same-name end, and a second different-name end provided on the first side; A secondary homonymous terminal and a secondary heteronymous terminal are provided on the second side; Two rows of through holes for electrical connection of the primary winding are provided in the middle of the printed circuit board; each row of the two rows of through holes for electrical connection of the primary winding includes an input through hole and an output through hole; A group of through holes for electrical connection of the secondary winding is arranged between the secondary like-name terminal and the secondary unlike-name terminal.

7. The printed circuit board according to claim 6, wherein: The two rows of through holes for electrical connection of the primary winding, wherein the connection between the input through holes in one row and the output through holes in the other row are used for electrical connection of the primary winding.

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