Dual-winding planar transformer and printed circuit board for dual-winding planar transformer

Abstract

The embodiment of the invention relates to a duplex winding planar transformer and a printed circuit board for the duplex winding planar transformer, the winding planar transformer comprises a first primary winding, a second primary winding and a secondary winding which are constructed on four layers of stacked PCBs, the first primary winding is constructed on the first layer of PCB and the second layer of PCB, and the second primary winding is constructed on the second layer of PCB. The second primary winding is constructed on the fourth-layer PCB and the third-layer PCB, and the secondary winding is constructed on the second-layer PCB and the third-layer PCB. Each layer of PCB comprises a through hole used for connecting the primary winding and the secondary winding, and electric connection between the windings is achieved through the access through hole and the outlet through hole in each layer of PCB. According to the planar transformer, through reasonable layout and winding design, electrical connection and energy transfer between the windings are ensured. The double-winding planar transformer provided by the invention is simple in processing technology, low in manufacturing cost and beneficial to batch production.

Description

Technical Field

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

[0002] With the popularization of power fast charging technology, miniaturization and high frequency have become the main development trends of switching power supplies. The traditional winding transformer is large in size and heavy in weight, which limits the miniaturization of power supplies. Increasing the switching frequency helps to reduce the size and weight of magnetic components. Planar transformers have been widely used in switching power supplies in recent years because of their small size, high operating frequency, easier to achieve flat structure, and good heat dissipation performance and consistency.

[0003] PCB type planar transformer is a planar transformer that uses printed circuit board (PCB) as winding structure. Traditional transformers usually use coils wound on iron cores, while PCB type planar transformers replace the traditional winding structure by designing copper foil coils as windings on multi-layer PCBs. PCB type planar transformers are ideal for high power density and high frequency switching power supplies because they eliminate the winding skeleton.

[0004] PCB type planar transformer is mainly composed of two parts: magnetic core and multi-layer PCB. Traditional PCB type planar transformer usually uses 8-layer PCB, which is not only large in size but also increases the cost.

[0005] In addition, vias are required in the processing technology of PCB-type planar transformers to connect copper foils in different layers. Due to the magnetic core of existing PCB-type transformers and the structure of multi-layer PCBs, complex buried or blind hole processes are often required. These processes are highly complex, increasing the difficulty of manufacturing and becoming a key factor affecting the large-scale application of PCB-type planar transformers.

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

[0007] The purpose of the present invention is to provide a dual-winding planar transformer and a printed circuit board for the dual-winding planar transformer in view of the defects in the prior art. By optimizing the design of the PCB structure, the adaptation of the vias using only the through-hole process is achieved, and the first primary winding, the second primary winding and the secondary winding are reasonably designed based on the PCB, saving the traditional additional power supply winding. The dual-winding planar transformer proposed by the present invention has a simple processing technology, low cost, and is conducive to 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 PCB stacked in sequence, wherein the first primary winding is constructed on the first layer PCB and the second layer PCB, the second primary winding is constructed on the fourth layer PCB and the third layer PCB, and the secondary winding is constructed on the second layer PCB and the third layer PCB;

[0010] Each layer of PCB includes: a first same-name terminal, a first different-name terminal, a second same-name terminal and a second different-name terminal arranged on the first side, a secondary same-name terminal and a secondary different-name terminal arranged on the 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 same-name terminal and the secondary different-name terminal; wherein each of the two rows of through holes for electrical connection of the primary winding includes an access through hole and an access through hole; the access through holes in the second row on the second layer PCB are electrically connected to the access through holes in the first row through a first electrical connection line; the access through holes in the first row on the third layer PCB are electrically connected to the access through holes in the second row through a second electrical connection line;

[0011] The first layer PCB is provided with a first primary winding and a second primary winding; one end of the first primary winding is connected to the first same-name terminal B, is wound half a circle along the first direction, and the other end is connected to the access through hole of the second row; one end of the second primary winding is connected to the access through hole of the first row, is wound N circles plus half a circle along the first direction, and the other end is connected to the first different-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, is 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] The third layer PCB is provided with a second secondary winding; one end of the second secondary winding is connected to the through hole 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;

[0014] The fourth layer PCB is provided with a third primary winding and a fourth primary winding; one end of the third primary winding is connected to the second like-name terminal D, is wound M turns plus half a turn along 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 along 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 wire 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 along 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 access through holes on the second layer PCB and then connected back to the first row of access through holes on the first layer PCB, continues to be wound N turns plus half a turn along the first direction, and is connected to the first different-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 once along the first direction, is connected to the through hole for electrical connection of the secondary winding on the third-layer PCB through the through hole for electrical connection of the secondary winding on the second-layer PCB, is wound once again along the first direction, and the other end is connected to the secondary different-name terminal E.

[0019] Preferably, the third primary winding, the second electrical connection wire 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 along 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 access through holes on the third-layer PCB, and is then connected back to the second row of access through holes on the fourth-layer PCB, continues to be wound half a turn along the first direction, and is connected to the second different-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 disposed on the first side;

[0024] A secondary same-name terminal and a secondary different-name terminal are provided on the second side;

[0025] Two rows of through holes for electrical connection of the primary winding are arranged in the middle of the printed circuit board; each of the two rows of through holes for electrical connection of the primary winding includes an inlet through hole and an outlet through hole;

[0026] A group of through holes for electrical connection of the secondary winding is arranged between the secondary same-name terminal and the secondary different-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 of one row and the exit through holes of the other row is used for electrical connection of the primary winding.

[0028] The dual-winding planar transformer provided in the embodiment of the present invention optimizes the design of the PCB structure, realizes the adaptation of the via hole using only the through-hole process, and performs reasonable routing design for the first primary winding, the second primary winding and the secondary winding based on the PCB structure, thereby saving the traditional additional power supply winding. The dual-winding planar transformer proposed in the present invention has a simple processing technology, low cost, and is conducive to mass production. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

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

[0032] Figure 1D A schematic structural diagram of the fourth layer of the 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] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are 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 in sequence, as shown in AD of FIG. 1 from the first layer to the fourth layer, wherein the first primary winding is constructed on the first layer PCB and the second layer PCB, the second primary winding is constructed on the fourth layer PCB and the third layer PCB, and the secondary winding is constructed on the second layer PCB and the third layer PCB.

[0037] The structure of each layer of the printed circuit board (PCB) is as follows Figure 2 As 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 arranged 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 arranged in the middle of the printed circuit board; wherein each row includes an inlet through hole and an outlet through hole; such as 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. In the two rows of through holes for primary winding electrical connection, the connection between the access through holes in one row and the access through holes in the other row is used for the electrical connection of the primary winding.

[0041] A group of through holes 205 for electrical connection of the secondary winding is arranged between the secondary same-name terminal and the secondary different-name terminal.

[0042] The printed circuit board (PCB) of each layer of the double-winding planar transformer in 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 via 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 via 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 along 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 along 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, and 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 arranged 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 a half turn along the first direction, and the other end is connected to the first row of access through holes 201; one end of the fourth primary winding 32 is connected to the second row of access through holes 204, is wound half a turn along 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 starts from the first same-name terminal B on the first layer PCB, and after the first primary winding 11 is wound half a circle along the first direction, it is connected to the second row of access through holes 203 on the second layer PCB through the second row of access through holes 203 on the first layer PCB, and then connected to the first row of access through holes 202 on the second layer PCB through the first electrical connection line 41, and then connected back to the first row of access through holes 202 on the first layer PCB, and then the second primary winding 12 is wound N circles plus half a circle along the first direction, and connected to the first opposite-name terminal A.

[0050] The first secondary winding 21 and the second secondary winding 22 constitute a secondary winding. The secondary winding starts from the secondary same-name terminal F on the second-layer PCB, winds one circle along the first direction with the first secondary winding 21, is connected to the through hole 205 for secondary winding electrical connection on the third-layer PCB through the through hole 205 for secondary winding electrical connection on the second-layer PCB, and winds one circle along the first direction with the second secondary winding 22, and the other end is 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 starts from the second same-name terminal D on the fourth-layer PCB, and after winding the third primary winding 31 along the first direction for M turns plus half a turn, it is connected from the first row of access through holes 201 on the fourth-layer PCB to the first row of access through holes 201 on the third-layer PCB, and then connected from the second row of access through holes 204 on the third-layer PCB through the second electrical connection line 41, and then connected back to the second row of access through holes 204 on the fourth-layer PCB, and continues to wind half a turn along the first direction, and is connected to the second different-name terminal C.

[0052] In the specific example shown in Fig. 1, 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 the circuit function requirements in a specific implementation, and the values ​​of M and N can be equal or different.

[0054] In the dual-winding planar transformer of the present invention, the primary and secondary windings are realized by copper wire routing in a multi-layer PCB, and the multi-layer structure and through-holes of the PCB are used for electrical connection. The PCB structure of the present invention not only provides electrical connection of the windings, but also meets the specific requirements of the circuit for voltage and current by optimizing the routing. Through the precise design of the number of winding turns and the position of the through-holes, the secondary circuit can directly obtain the required voltage and current through the PCB, reducing the necessity of additional power supply windings in traditional transformers.

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

[0056] By designing the winding structure on the PCB, the processing steps of the winding are greatly simplified. The additional power supply winding of the traditional transformer requires a separate winding process, but the winding designed by the PCB structure of the present invention can be completed in one go when manufacturing the PCB, and only through-hole technology is supported. This not only saves the material of the additional power supply winding, but also simplifies the entire manufacturing process and reduces the process steps.

[0057] The dual-winding planar transformer provided in the embodiment of the present invention optimizes the design of the PCB structure, realizes the adaptation of the via hole using only the through-hole process, and performs reasonable routing design for the first primary winding, the second primary winding and the secondary winding based on the PCB structure, thereby saving the traditional additional power supply winding. The dual-winding planar transformer proposed in the present invention has a simple processing technology, low cost, and is conducive to 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 PCB stacked in sequence, wherein the first primary winding is constructed on the first layer PCB and the second layer PCB, the second primary winding is constructed on the fourth layer PCB and the third layer PCB, and the secondary winding is constructed on the second layer PCB and the third layer PCB; Each layer of PCB includes: a first same-name terminal, a first different-name terminal, a second same-name terminal and a second different-name terminal arranged on the first side, a secondary same-name terminal and a secondary different-name terminal arranged on the 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 same-name terminal and the secondary different-name terminal; wherein each of the two rows of through holes for electrical connection of the primary winding includes an access through hole and an access through hole; the access through holes in the second row on the second layer PCB are electrically connected to the access through holes in the first row through a first electrical connection line; the access through holes in the first row on the third layer PCB are electrically connected to the access through holes in the second row through a second electrical connection line; The first layer PCB is provided with a first primary winding and a second primary winding; one end of the first primary winding is connected to the first same-name terminal B, is wound half a circle along the first direction, and the other end is connected to the access through hole of the second row; one end of the second primary winding is connected to the access through hole of the first row, is wound N circles plus half a circle along the first direction, and the other end is connected to the first different-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, is wound one circle along the first direction, and the other end is connected to the through hole for electrical connection of the secondary winding; The third layer PCB is provided with a second secondary winding; one end of the second secondary winding is connected to the through hole 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; The fourth layer PCB is provided with a third primary winding and a fourth primary winding; one end of the third primary winding is connected to the second like-name terminal D, is wound M turns plus half a turn along 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 along 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 double-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 along 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 access through holes on the second layer PCB and then connected back to the first row of access through holes on the first layer PCB, continues to be wound N turns plus half a turn along the first direction, and is connected to the first different-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 once along the first direction, is connected to the through hole for electrical connection of the secondary winding on the third-layer PCB through the through hole for electrical connection of the secondary winding on the second-layer PCB, is wound once again along the first direction, and the other end is connected to the secondary different-name terminal E.

4. The double-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 along 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 access through holes on the third-layer PCB, and is then connected back to the second row of access through holes on the fourth-layer PCB, continues to be wound half a turn along the first direction, and is connected to the second different-name terminal C.

5. The double-winding planar transformer according to claim 1, characterized in that: 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 disposed on the first side; A secondary same-name terminal and a secondary different-name terminal are provided on the second side; Two rows of through holes for primary winding electrical connection are arranged in the middle of the printed circuit board; each of the two rows of through holes for primary winding electrical connection includes an inlet through hole and an outlet through hole; A group of through holes for electrical connection of the secondary winding is arranged between the secondary same-name terminal and the secondary different-name terminal.

7. The printed circuit board according to claim 6, characterized in that: The two rows of through holes used for electrical connection of the primary winding, wherein the connection between the access through holes in one row and the exit through holes in the other row is used for electrical connection of the primary winding.

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