Planar transformer integrated structure of current doubler rectifier converter
Patent Information
- Application Number
- CN202511326917.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-17
- Publication Date
- 2026-09-22
- Estimated Expiration
- 2045-09-17
AI Technical Summary
然而在MHz频率下高效率地处理大电流依然具有非常大的挑战性，磁件平面化之后，气隙的边缘效应会在绕组上感应出涡流，在高频率下，涡流损耗甚至会超过绕组损耗本身
[0019]本发明与现有技术相比，其有益效果是：本发明提供一种倍流整流变换器的平面变压器集成结构，该结构通过集成对称结构的设计，各路输出电流具有很好的均流特性，因而能够大幅度减小绕组损耗和端部损耗，同时拥有更高的集成度。相比于矩阵变压器，该平面变压器集成结构可以方便地设计成任意匝数的副边绕组，能够实现奇数匝变比，具有更宽的应用范围；该变压器结构可以降低变换器的损耗和体积，副边绕组的长度也有很大程度的减小，有利于获得更高的效率和功率密度。原边集成绕组结构一方面减少了原边绕组的长度；另一方面，在得到相同变压器变比的前提条件下，原边绕组绕制的圈数得益于集成结构而减少，绕组绘制的宽度增加，因此原边绕组的损耗也大大减少，有利于变换器效率提升。
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Abstract
Description
Technical Field
[0001] This invention relates to transformers, and more particularly to a planar transformer integrated structure for a current-doubler rectifier converter. Background Technology
[0002] With the rapid development of emerging technologies such as big data processing and artificial intelligence, the design of power supplies for high-performance chip motherboards faces severe challenges. The surge in energy consumption places higher demands on power electronic converters in terms of efficiency, power density, and current capability. On the one hand, with the development of high-performance chips, the supply voltage of terminal loads has dropped below 1V, but their current demand reaches hundreds or even thousands of amperes. On the other hand, the DC bus voltage of power supply systems is gradually increasing (e.g., from 12V to 48V or even higher) to reduce bus current and bus losses. Therefore, motherboard power supplies need to meet the requirements of high buck ratio and large output current. In addition, to improve the overall energy efficiency of the motherboard and reduce its size, improving the efficiency and power density of the power supply has become a key design factor.
[0003] Considering the basic characteristics of high step-down ratio and large output current, a high step-down ratio DC-DC converter based on active bridge and current doubler rectification is a better candidate for motherboard power supply. In this circuit, if the primary side of the transformer adopts a half-bridge structure, a transformer with a turns ratio of 8:1 is only needed to achieve a step-down ratio of more than 48:1. In addition, the two output inductors required by the traditional current doubler rectification circuit are integrated into the magnetizing inductor of the transformer, which greatly reduces the number of magnetic components and significantly improves the power density of the converter.
[0004] However, the shape and size limitations of the integrated transformer, making its height significantly higher than other components, remain a major constraint on overall efficiency and power density improvement. Planar transformers based on PCB windings have been widely researched and applied due to their advantages such as small size, good consistency, and flexible winding shape, enabling higher power density. However, efficiently handling large currents at MHz frequencies remains a significant challenge. After planarizing the magnetic components, the edge effect of the air gap induces eddy currents in the windings; at high frequencies, eddy current losses can even exceed the winding losses themselves. Simultaneously, under high current output conditions, issues such as parallel current sharing and large termination losses increase the complexity of planar transformer design and limit efficiency improvements.
[0005] Planar matrix transformers can effectively solve problems such as high winding end losses, but winding losses still dominate, and further reduction of winding losses remains a significant challenge. Compared to centralized transformers, matrix transformers have a significantly increased number of units and larger size, requiring integration to improve their density and efficiency. Furthermore, matrix transformers are not easily implemented with odd-numbered turns ratios, limiting their application scope and flexibility. Summary of the Invention
[0006] To address the problems existing in the prior art, the purpose of this invention is to provide a planar transformer integrated structure that enables a current-doubling rectifier converter with low winding losses and the ability to achieve odd turns ratios.
[0007] To achieve the above-mentioned objectives, the present invention provides the following technical solution:
[0008] A planar transformer integrated structure for a current multiplier rectifier converter includes a PCB board, a first transformer core, a second transformer core, a primary integrated winding, K first transformer secondary windings, K second transformer secondary windings, and 2K rectifier unit circuits, where K is a natural number not less than 2.
[0009] The first transformer core includes a core bottom and a core top. A raised central post is located in the center of the core bottom, and K raised side posts are located around its perimeter. The central post passes through a cutout in the center of the PCB board 1 and contacts the core top. The side posts pass through the outer edge of the PCB board and contact the core top. The second transformer core is a mirror image of the first transformer core. The primary winding is printed on the first surface of the PCB board and simultaneously winds N turns around the central post of both the first and second transformer cores, where N is a natural number. All primary windings are printed on the second surface of the PCB board. The K primary windings connected together encircle the central post once, and each primary winding is positioned between the central post and one side post, with equal lengths. Each primary winding is connected to the output terminal of the planar transformer via a rectifier unit circuit. The second secondary winding is a mirror image of the first secondary winding.
[0010] Furthermore, the rectifier unit circuit includes a current multiplier rectifier tube and a capacitor. The same-name terminal of the secondary winding 5 of the first transformer is connected to the drain of the current multiplier rectifier tube, the source of the current multiplier rectifier tube is grounded, the negative terminal of the capacitor is connected to the source of the current multiplier rectifier tube, the positive terminal is connected to the opposite-name terminal of the adjacent secondary winding of the first transformer, and the positive terminal is also connected to the output terminal of the planar transformer.
[0011] Furthermore, the current multiplier rectifier and capacitor are fixed to the PCB board by surface mount soldering.
[0012] Furthermore, the cross-sectional areas of the side columns of the first transformer core (2) and the second transformer core (3) are equal.
[0013] Furthermore, when K is even, the K side pillars are evenly distributed on the two sides directly opposite the central pillar. When K is odd, the K-1 side pillars are evenly distributed on the two sides directly opposite the central pillar, and the remaining side pillar is distributed on the third side of the central pillar, forming an axially symmetrical design.
[0014] Furthermore, the current in the secondary winding of the first transformer is in the opposite direction to the current in the secondary winding of the second transformer.
[0015] Furthermore, an insulating dielectric layer is provided between the primary integrated winding and the secondary winding 5 of the first transformer and the secondary winding 6 of the second transformer.
[0016] Furthermore, the primary-side integrated winding is connected to an active bridge circuit.
[0017] Furthermore, the primary-side integrated winding is uniformly distributed circumferentially around the central column of the first transformer core and the second transformer core.
[0018] A current-doubler rectifier converter includes the above-mentioned planar transformer integrated structure with several windings connected in series or parallel.
[0019] Compared with existing technologies, the advantages of this invention are as follows: This invention provides a planar transformer integrated structure for a current-doubling rectifier converter. Through the design of an integrated symmetrical structure, this structure exhibits excellent current-sharing characteristics for each output current, thus significantly reducing winding and end losses while achieving higher integration. Compared to matrix transformers, this planar transformer integrated structure can be easily designed with a secondary winding of arbitrary turns, enabling odd-numbered turns ratios and a wider range of applications. This transformer structure reduces converter losses and size, and the length of the secondary winding is also significantly reduced, which is beneficial for achieving higher efficiency and power density. The integrated primary winding structure reduces the length of the primary winding; furthermore, under the premise of achieving the same transformer turns ratio, the number of turns in the primary winding is reduced due to the integrated structure, and the winding width is increased. Therefore, the losses in the primary winding are also greatly reduced, which is beneficial for improving converter efficiency. Attached Figure Description
[0020] Figure 1 This is a 3D exploded view of the planar transformer integrated structure of the current doubler rectifier converter proposed in this invention;
[0021] Figure 2 This invention presents a specific layout scheme for the secondary winding and devices on the first surface of a PCB for the integrated planar transformer structure of the current doubler rectifier converter.
[0022] Figure 3 This invention provides a specific layout scheme for the primary-side integrated winding of the planar transformer integrated structure of the current doubler rectifier converter on the second surface of the PCB.
[0023] Figure 4The diagram shows the equivalent circuit and integrated structure of the planar transformer integrated structure of the current doubler rectifier converter proposed in this invention during the positive half-cycle. (a) is the equivalent circuit schematic diagram under this working state, (b) is a schematic diagram of the current flow direction of the secondary winding on the second surface of the PCB, and (c) is a schematic diagram of the current flow direction of the integrated winding on the primary side of the first surface of the PCB.
[0024] Figure 5 The diagram shows the equivalent circuit and integrated structure of the planar transformer integrated structure of the current doubler rectifier converter proposed in this invention during the negative half-cycle. (a) is the equivalent circuit schematic diagram under this working state, (b) is a schematic diagram of the current flow direction of the secondary winding on the second surface of the PCB, and (c) is a schematic diagram of the current flow direction of the integrated winding on the primary side of the first surface of the PCB.
[0025] Figure 6 The diagram shows the equivalent circuit and integrated structure of the planar transformer integrated structure of the current multiplier rectifier converter proposed in this invention during the dead time. (a) is the schematic diagram of the equivalent circuit under this working state, (b) is a schematic diagram of the current flow direction of the secondary winding on the second surface of the PCB, and (c) indicates that no current flows through the integrated winding on the primary side of the first surface of the PCB.
[0026] Figure 7 The diagram shows the circuit and planar transformer integrated structure of a current multiplier rectifier converter based on a matrix transformer. Taking the Ta transformer as an example, it contains K Ta sub-transformers. (a) is the equivalent circuit diagram, (b) is the structural diagram when K is odd, and (c) is the structural diagram when K is even.
[0027] Figure 8 The diagram shows the circuit and planar transformer integrated structure of a multi-transformer current multiplier rectifier converter, which includes multiple transformers. Taking Ta transformers as an example, each group contains K Ta sub-transformers. (a) is an equivalent circuit diagram, (b) is a planar transformer integrated structure diagram of a multi-transformer current multiplier rectifier converter, and (c) is a planar transformer integrated structure diagram of a multi-phase current multiplier rectifier converter with side column cancellation.
[0028] Figure 9 The diagram shows the winding method of the primary integrated winding of the planar transformer in a multi-transformer current multiplier rectifier converter. (a) is a schematic diagram of the winding method of the primary integrated winding of the planar transformer in a multi-transformer current multiplier rectifier converter, and (b) is a schematic diagram of the winding method of the primary integrated winding of the planar transformer in a multi-transformer current multiplier rectifier converter with side column cancellation.
[0029] Figure 10 This is a schematic diagram of the winding method of the integrated primary winding between the planar transformers in a current-multiplying rectifier converter. Detailed Implementation
[0030] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.
[0031] This invention provides a planar transformer integrated structure for a current-doubler rectifier converter, with K=2 as an example for structural description. Figure 1 and Figure 2 As shown, the embodiment of the present invention includes a PCB board 1, a first transformer core 2, a second transformer core 3, a primary integrated winding 4, two first transformer secondary windings 5, two second transformer secondary windings 6, and four rectifier unit circuits.
[0032] The first transformer core 2 includes a core bottom 21 and a core top 22. The core bottom 21 has a centrally located raised post 211 and two raised side posts 212 on either side. The central post 211 passes through a cutout in the center of the PCB board 1 and contacts the core top 22. The side posts 212 pass through the outer edge of the PCB board 1 and contact the core top 22. The second transformer core 3 is structurally symmetrical to the first transformer core 2. Specifically, it also includes a core bottom 31 and a core top 32. The core bottom 31 has a centrally located raised post 311 and two raised side posts 312 on either side. The central post 311 passes through a cutout in the center of the PCB board 1 and contacts the core top 32. The side posts 312 pass through the outer edge of the PCB board 1 and contact the core top 32. All side posts of the first transformer core 2 and the second transformer core 3 have the same cross-sectional area.
[0033] like Figure 3 As shown, the primary integrated winding 4 is printed on the first surface of the PCB board 1, and is uniformly wound N turns around the central column of the first transformer core 2 and the second transformer core 3, where N is a natural number. The primary integrated winding 4 is connected to an active bridge circuit. Two secondary windings 5 of the first transformers are printed on the second surface of the PCB board 1. The two secondary windings 5 are connected together and encircle the central column 211 once, with each secondary winding 5 positioned between the central column 211 and a side column 212. The secondary winding 6 of the second transformer is arranged in a mirror-symmetrical manner with the secondary windings 5 of the first transformers. An insulating dielectric layer is provided between the primary integrated winding 4 and the secondary windings 5 and 6 of the first and second transformers. In this embodiment, the first surface of the PCB board 1 is either the front or back side of the PCB board 1. When the first surface is the front side of the PCB board 1, the second surface is the back side of the PCB board 1; when the first surface is the back side of the PCB board 1, the second surface is the front side of the PCB board 1.
[0034] like Figure 2 and Figure 4 As shown, each of the first transformer secondary windings 5(L) ma1 L ma2) and each second transformer secondary winding 6 (L mb1 L mb2 Each current doubler rectifier diode (SR) is connected to the output of the planar transformer via a rectifier unit circuit. Each rectifier unit circuit includes a current doubler rectifier diode (SR) 7 and a capacitor (C) 8. This embodiment has a total of four current doubler rectifier diodes (SR) 7. a1 SR a2 SR b1 SR b2 ) and four capacitors 8 (C a1 C a2 C b1 C b2 The drain of the current multiplier rectifier 7 is connected to the same-name terminal of the secondary winding 5 of the first transformer. The source of the current multiplier rectifier 7 is grounded. The negative terminal of the capacitor 8 is connected to the source of the current multiplier rectifier 7, and the positive terminal is connected to the opposite-name terminal of the adjacent secondary winding 5 of the first transformer. The positive terminal is also connected to the output terminal Vo of the planar transformer. The rectifier unit circuit is set on the second surface of the PCB board 1, and the current multiplier rectifier 7 and the capacitor 8 are fixed on the PCB board 1 by surface mount soldering.
[0035] Figure 4 , Figure 5 , Figure 6 The working process and its equivalent circuit are shown. The primary integrated winding 4 and the secondary winding 5 (L) of the first transformer are also shown. ma1 L ma2 The first transformer T was formed. a Primary integrated winding 4 and secondary winding 6 of the second transformer (L) mb1 L mb2 The second transformer T was formed. b L in the primary integrated winding 4 and the secondary winding 5 of the first transformer ma1 The first T was formed a Sub-transformer T a1 The same applies to the others. Four current-multiplying rectifier diodes (SR) a1 SR a2 SR b1 SR b2 These are connected to the same-name output terminals of the four secondary windings, respectively. The side posts of the magnetic core have three line leads at the locations where the current multiplier rectifier tubes and capacitors are placed. The opposite-name terminals of the transformer secondary windings and the secondary ground are led out from these line leads. For the positive half-cycle, such as... Figure 4 As shown in (a), SR b1 SR b2 On, SR a1 SR a2 When turned off, the primary current is as follows Figure 4 The flow direction shown in (b) is T b secondary winding current i sb1 isb2 The current flows clockwise around the central column 311, exiting the transformer from two separate line leads. Through the symmetrical design of the magnetic components and circuit structure, SR... b1 SR b2 The currents are equal in magnitude. The voltage across each capacitor is Vo, and the voltage across each secondary winding is also Vo, equal in magnitude but opposite in direction to the capacitor voltage. All capacitors share a common ground. The voltage across the two secondary windings that wrap around the center column 311 is 2Vo, so the effective turns ratio of the secondary winding is 1 / 2. For the negative half-cycle, such as Figure 5 As shown, SR a1 SR a2 On, SR b1 SR b2 When turned off, the primary current flows as shown in the diagram. The operating process is similar to the positive half-cycle, except that T... a Secondary winding current i sa1 i sa2 The flow is counterclockwise around the central column 211 of the magnetic core. During the dead time, such as... Figure 6 As shown, T a T b The secondary winding is in freewheeling mode, SR a1 SR a2 SR b1 SR b2 When the circuit is turned on, no current flows through the primary winding, and the secondary winding current i sa1 i sa2 The flow around the middle column 211 is counterclockwise, and the secondary winding current i sb1 i sb2 The current flows clockwise around the central post 311 of the magnetic core and exits the transformer from three separate line leads. Through the symmetrical design of the magnetic components and circuit structure, SR... a1 SR a2 SR b1 SR b2 The average current is the same for all capacitors. The voltage across each capacitor is Vo.
[0036] The planar transformer integrated structure of the current-doubling rectifier converter proposed in this embodiment of the invention can achieve arbitrary turns ratios, and the equivalent circuit diagram is as follows. Figure 7 As shown in (a). Taking a Ta transformer as an example, when the number of secondary turns is 1 / K, Figure 7 (b) A schematic diagram of the specific structure when K is an odd number is given. Figure 7(c) A schematic diagram of the specific structure when K is even is given. In the diagram, when K is even, K side posts 212 are evenly distributed on the two sides directly opposite the central post 211. When K is odd, K-1 side posts 212 are evenly distributed on the two sides directly opposite the central post 211, and the remaining side post 212 is distributed on the third side of the central post 211. This method can achieve arbitrary turns ratios for the transformer. Assuming the desired turns ratio is N:1 / K, the winding that wraps around the central post of the magnetic core on the second surface is divided into K segments, each segment serving as a secondary winding. Each secondary winding passes through the space formed by the central post and the side posts of the magnetic core. K current-doubling rectifier diodes and K capacitors are integrated between adjacent secondary windings in the space formed between the center column and the side column of the magnetic core. The drain of each current-doubling rectifier diode is connected to the same-name terminal of an adjacent secondary winding segment, the source of the current-doubling rectifier diode is connected to the negative terminal of the capacitor, and the positive terminal of the capacitor is connected to the opposite-name terminal of another adjacent secondary winding segment. K output ports are set at the positive terminals of the capacitors to draw K output currents. The primary winding is wound N times around the center column of the Ta transformer. The Tb transformer is similarly constructed and will not be elaborated further. The number of PCB layers can be increased to allow for parallel windings as needed.
[0037] The planar transformer integrated structure of the current doubler rectifier converter proposed in this invention can realize the expansion of any group of transformers to form a current doubler rectifier converter. The circuit diagram is shown below. Figure 8 As shown in (a). Taking a Ta transformer as an example, Figure 8 (b) provides a detailed structural diagram of the M-group transformer circuit, demonstrating that this method can be used to expand the number of groups to any desired extent. The M-group transformer structure is arranged vertically, with M*K current-doubling rectifier diodes and M*K capacitors integrated on the secondary winding surface. Simultaneously, M*(K-1) line leads are opened at the synchronous rectifier diodes and capacitors on the core side posts, thus generating M*(K-1) output current paths. Based on the principle of magnetic flux cancellation, Figure 8 (c) Further canceling out adjacent side posts results in a structure with only K side posts, significantly reducing the core footprint. The same principle applies to the Tb transformer. The number of PCB layers can be increased to allow for parallel windings as needed.
[0038] The primary-side integrated winding method of the planar transformer integrated structure of the current multiplier rectifier converter proposed in this invention is as follows: Figure 9 As shown, under the transformer structure of group M, the primary integrated winding needs to be wound in the direction shown in the figure. The number of turns N is selected according to the turns ratio. The number of PCB layers can be increased to connect the windings in series or in parallel as needed.
[0039] The optimization method of the primary-side integrated winding in this invention is as follows: Figure 10 As shown, the primary-side integrated winding is directly wound around the middle columns of the transformers Ta and Tb of the current-multiplier rectifier converter. This primary-side integrated winding structure greatly simplifies the winding method of the primary-side winding. Based on Figure 9The primary-side integrated winding structure can also be used between transformers Ta and Tb to reduce the length of the primary-side integrated winding and reduce winding losses.
[0040] It should be understood that the embodiments and descriptions above are only the principles, main features and advantages of the present invention. Various changes and modifications can be made to the present invention without departing from the spirit and scope of the invention, and all such changes and modifications fall within the protection scope of the present invention.
Claims
1. A planar transformer integrated structure for a current multiplier rectifier converter, characterized in that: It includes a PCB board (1), a first transformer core (2), a second transformer core (3), a primary integrated winding (4), K first transformer secondary windings (5), K second transformer secondary windings (6), and 2K rectifier unit circuits, where K is a natural number not less than 2; The first transformer core (2) includes a core bottom (21) and a core top (22). The core bottom (21) has a raised central post (211) in the middle and K raised side posts (212) around its perimeter. The central post (211) passes through the hollowed-out part in the middle of the PCB board (1) and contacts the core top (22). The side posts (212) pass through the outer edge of the PCB board (1) and contact the core top (22). The second transformer core (3) is a mirror image of the first transformer core (2). The primary-side integrated winding (4) is printed on the first surface of the PCB board (1) and simultaneously surrounds the core. N turns are made around the center post of the first transformer core (2) and the second transformer core (3), where N is a natural number; all the secondary windings (5) of the first transformer are printed on the second surface of the PCB board (1), and K secondary windings (5) of the first transformer are connected together to surround the center post (211) 1 turn, and each secondary winding (5) of the first transformer is located between the center post (211) and a side post (212); each secondary winding (5) of the first transformer is connected to the output terminal of the planar transformer through a rectifier unit circuit; the secondary winding (6) of the second transformer is a mirror image symmetrical to the secondary winding (5) of the first transformer. The rectifier unit circuit includes a current multiplier rectifier tube (7) and a capacitor (8). The same-name terminal of the secondary winding (5) of the first transformer is connected to the drain of the current multiplier rectifier tube (7), the source of the current multiplier rectifier tube (7) is grounded, the negative terminal of the capacitor (8) is connected to the source of the current multiplier rectifier tube (7), the positive terminal is connected to the opposite-name terminal of the adjacent secondary winding (5) of the first transformer, and the positive terminal is also connected to the output terminal of the planar transformer.
2. The planar transformer integrated structure of the current multiplier rectifier converter according to claim 1, characterized in that: The current multiplier rectifier tube (7) and capacitor (8) are fixed on the PCB board (1) by surface mount soldering.
3. The planar transformer integrated structure of the current multiplier rectifier converter according to claim 1, characterized in that: The cross-sectional areas of the side columns of the first transformer core (2) and the second transformer core (3) are equal.
4. The planar transformer integrated structure of the current multiplier rectifier converter according to claim 1, characterized in that: When K is even, K side posts (212) are evenly placed on the two sides directly opposite to the middle post (211). When K is odd, K-1 side posts (212) are evenly placed on the two sides directly opposite to the middle post (211), and the remaining 1 side post (212) is placed on the third side of the middle post (211), and is designed in an axially symmetrical manner.
5. The planar transformer integrated structure of the current multiplier rectifier converter according to claim 1, characterized in that: The current in the secondary winding (5) of the first transformer is opposite in direction to the current in the secondary winding (6) of the second transformer.
6. The planar transformer integrated structure of the current multiplier rectifier converter according to claim 1, characterized in that: An insulating dielectric layer is provided between the primary integrated winding (4) and the secondary winding (5) of the first transformer and the secondary winding (6) of the second transformer.
7. The planar transformer integrated structure of the current multiplier rectifier converter according to claim 1, characterized in that: The primary-side integrated winding (4) is connected to the active bridge circuit.
8. The planar transformer integrated structure of the current multiplier rectifier converter according to claim 1, characterized in that: The primary-side integrated winding (4) is evenly distributed around the central column of the first transformer core (2) and the second transformer core (3).
9. A current-doubler rectifier converter, characterized in that, The planar transformer integrated structure includes a plurality of windings connected in series or in parallel, as described in any one of claims 1-8.