A three-phase positive coupled inductor for switched-capacitor converters

Abstract

This invention discloses a three-phase positively coupled inductor for a switched-capacitor converter, relating to the field of inductor technology. Addressing the problem of high inductance loss and difficulty in miniaturization of existing inductors when applied to resonant switched-capacitor converters, this invention includes a printed circuit board (PCB). The PCB contains a magnetic core with a first winding, a second winding, and a third winding running through it. The second winding has the opposite winding direction to the first winding, while the third winding has the same winding direction as the first winding. When connected to the switched-capacitor converter circuit, the current flowing through the second winding is opposite to the current flowing through the first winding, and the current flowing through the third winding is the same as the current flowing through the first winding. This invention achieves magnetic integration through a PCB-embedded three-phase positively coupled structure to reduce the inductor size, while simultaneously increasing the inductance density through the positive coupling effect, resulting in higher inductance and lower inductance loss.

Description

Technical Field

[0001] This invention relates to the field of inductor technology, and more particularly to a three-phase positively coupled inductor for a switched capacitor converter. Background Technology

[0002] Traditional switched-capacitor converters (SCDCs) boast very high efficiency and power density due to the absence of magnetic components such as inductors and transformers. However, during switching commutation, the charging and discharging behavior of the flying capacitor in this topology causes a sudden surge in current, generating severe inrush current spikes. This leads to problems such as high switching losses, strong electromagnetic interference, and low device reliability. To suppress current spikes, existing technologies connect a resonant inductor in series with the flying capacitor branch, forming a resonant switched-capacitor converter. The resonant inductor and flying capacitor form a resonant network, enabling soft switching. However, the introduction of the resonant inductor introduces new drawbacks: as a magnetic component, the resonant inductor increases core and winding losses, limiting the improvement of power density in resonant switched-capacitor converters; furthermore, resonant inductors are typically discrete, resulting in large size and high profile, which restricts the integration of resonant switched-capacitor converters.

[0003] To reduce inductor size, magnetic integration technology has been developed, mainly including two types: planar magnetic integration and three-dimensional magnetic integration. However, existing integration schemes are mostly designed for two-phase designs or other topologies (such as Buck converters), and fail to take into account the specific current phase relationship (i.e., 180° staggered currents in each phase) that the three-phase resonant inductors in resonant switched capacitor converters need to satisfy.

[0004] For example, a PCB-embedded four-phase reverse-coupled inductor structure for a 20MHz integrated voltage regulator uses a magnetic core with good permeability retention at high frequencies and a negatively coupled inductor design, suitable for four-phase Buck converter applications. Its advantage lies in maintaining stable inductance values ​​by offsetting DC bias through coupling. However, in resonant switched-capacitor converters, the inductor currents in each phase exhibit sinusoidal waveforms, and there is no DC bias issue. If a positively coupled inductor structure is used, the inductance density can be effectively increased through magnetic integration, without needing to consider the decrease in inductance value caused by DC bias.

[0005] Therefore, there is an urgent need to develop a low-profile, low-loss, easily integrated, and high-inductance-density positively coupled inductor structure suitable for resonant switched-capacitor converters. Summary of the Invention

[0006] To address the aforementioned problems, this invention aims to provide a three-phase positively coupled inductor for a switched-capacitor converter. The inductor adopts a PCB-embedded three-phase positively coupled structure. By setting the second winding to be opposite in direction to the first and third windings and connecting it to the corresponding branch of the switched-capacitor converter, the inductor can achieve magnetic integration to reduce its size while ensuring that its three-phase currents satisfy a 180° staggered phase relationship in the circuit. The resulting positive coupling effect increases the inductance density, thereby achieving a higher inductance value and lower inductance loss.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: On one hand, the present invention provides a three-phase positively coupled inductor for a switched-capacitor converter, comprising: a printed circuit board, and further comprising: The magnetic core is embedded inside the printed circuit board; The first winding is disposed through the magnetic core; The second winding is disposed through the magnetic core and is wound in the opposite direction to the first winding; The third winding is disposed through the magnetic core and has the same winding direction as the first winding.

[0008] Furthermore, the configuration method of the inductor when connected to the switched capacitor converter circuit is as follows: The direction of the current flowing through the second winding is opposite to the direction of the current flowing through the first winding, and the direction of the current flowing through the third winding is the same as the direction of the current flowing through the first winding.

[0009] Furthermore, the magnetic core is provided with: Multiple central magnetic pillars are used to wind the first winding, the second winding, and the third winding.

[0010] Furthermore, the first winding includes: The first through-hole winding is disposed on both sides of the plurality of central magnetic pillars; The first surface winding is disposed on the upper and lower surfaces of the plurality of central magnetic pillars and is connected to the first through-hole winding.

[0011] Furthermore, the second winding includes: The second via winding is disposed on one side of the first via winding; The second surface winding is disposed on the upper and lower surfaces of the plurality of central magnetic pillars and is connected to the second through-hole winding.

[0012] Furthermore, the third winding includes: The third via winding is disposed on one side of the second via winding; The third surface winding is disposed on the upper and lower surfaces of the plurality of central magnetic pillars and is connected to the third through-hole winding.

[0013] On the other hand, the present invention provides a method for manufacturing a three-phase positively coupled inductor for a switched capacitor converter, the method comprising the following steps: The magnetic core is embedded inside the printed circuit board; A first through-hole winding, a second through-hole winding, and a third through-hole winding are sequentially arranged on both sides of multiple central magnetic pillars; A first surface winding, a second surface winding, and a third surface winding are respectively provided on the upper and lower surfaces of multiple central magnetic pillars; Inductors are formed by stacking and laminating the layers of a printed circuit board.

[0014] In another aspect, the present invention provides a switched capacitor converter, which includes the inductor as described above.

[0015] The beneficial effects of this invention are: (1) By setting the second winding to be opposite to the winding direction of the first and third windings and connecting it to the corresponding branch of the switched capacitor converter, the three-phase currents satisfy the 180° staggered phase relationship. This solves the problem that traditional discrete inductors or general integrated inductors cannot directly meet the specific phase constraints of the resonant switched capacitor converter, eliminates the need for complex external phase adjustment circuits, simplifies system design, and achieves synergistic optimization of structure, phase and performance. (2) In this invention, the positive coupling effect between the three-phase windings improves the equivalent inductance of each winding and achieves a higher inductance density in the same volume. At the same time, the magnetic integration design reduces the total volume of the magnetic core and the winding length, improves the heating of the magnetic core, and reduces the magnetic core loss and winding loss, thereby improving the overall power conversion efficiency. When actually applied to the switched capacitor converter, it can achieve a peak efficiency of 97.35% and a full load efficiency of 94.18%. (3) The present invention adopts PCB embedded technology, which makes the inductor have a flat and low profile structure, making it easy to integrate with the main circuit of the switched capacitor converter in three-dimensional space. By arranging the external circuit and active devices above the inductor, the three-dimensional integration of passive and active devices is realized, which significantly saves space and improves the power density and integration of the converter. (4) The present invention realizes the embedding and winding integration of inductors based on mature PCB technology, with a short production cycle, suitable for mass production, and can effectively reduce mass production costs. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of a three-phase positively coupled inductor for a switched capacitor converter proposed in this invention.

[0017] Figure 2 This is a schematic diagram of the magnetic core proposed in this invention.

[0018] Figure 3 This is a schematic diagram of the winding method of the first winding proposed in this invention.

[0019] Figure 4 This is a schematic diagram of the laminated structure of the inductor proposed in this invention.

[0020] Figure 5 This is a schematic diagram of the inductor proposed in this invention applied to a switched capacitor converter.

[0021] Figure 6 The images show a comparison between the physical switched-capacitor converter based on the inductor proposed in this invention and the physical switched-capacitor converter based on discrete inductors.

[0022] The above figures include the following reference numerals: 1. Magnetic core; 11. Central magnetic column; 12. Through hole; 2. First winding; 21. First through hole winding; 22. First surface winding; 3. Second winding; 31. Second through hole winding; 32. Second surface winding; 4. Third winding; 41. Third through hole winding; 42. Third surface winding. Detailed Implementation

[0023] To enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be further described below with reference to the accompanying drawings and embodiments. Obviously, the described embodiments are only a part of the embodiments, and not all of the embodiments.

[0024] In the description of this invention, it should be understood that the terms "front", "rear", "left", "right", "upper", "lower", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0025] Example 1: See attached document Figure 1This application discloses a three-phase positively coupled inductor for a switched-capacitor converter, comprising: a printed circuit board, wherein a magnetic core 1 is disposed inside the printed circuit board, and a first winding 2, a second winding 3, and a third winding 4 are disposed through the magnetic core 1. The first winding 2 and the third winding 4 are wound in the same direction, and the second winding 3 is wound in the opposite direction to the first winding 2 and the third winding 4. The first winding 2, the second winding 3, and the third winding 4 are configured such that when connected to the circuit of the switched-capacitor converter, the current flowing through the first winding 2... The current flowing through the second winding 3 With the current flowing through the third winding 4 satisfy The phase relationship is determined to achieve a three-phase positively coupled inductor structure. It should be noted that while this embodiment uses a three-phase positively coupled inductor structure, those skilled in the art can also use any multi-phase positively coupled structure to achieve the inductor function according to actual needs.

[0026] Specifically, the printed circuit board adopts ordinary PCB organic substrate (such as FR4) process and embedding process, or it can realize 3D winding through direct copper-clad ceramic substrate (DBC), direct copper-plated ceramic substrate (DPC), active metal brazing (AMB) and co-firing process to realize the function of embedded three-phase positive coupling inductor.

[0027] Furthermore, the magnetic core 1 is made of DSH125 magnetic powder core material, which can also be replaced by power ferrite, high-permeability ferrite, or nanocrystalline materials; the shape of the magnetic core 1 is cuboid, which can also be replaced by circular or other irregular shapes; the magnetic core 1 is provided with two central magnetic pillars 11, which are cuboid in shape, but can also be replaced by polygonal pillars, cylinders, or irregular pillars; through holes 12 are provided on both sides of the central magnetic pillars 11, and the through holes 12 are composed of circular stretched bodies and rectangular stretched bodies. The structure of the magnetic core 1 is shown in the attached figure. Figure 2 As shown.

[0028] Further, the first winding 2 includes a first through-hole winding 21 and a first surface winding 22. The first through-hole winding 21 is located within the through hole 12, and the first surface winding 22 is disposed on the upper and lower surfaces of the central magnetic post 11. Specifically, the winding direction is as follows: the first through-hole winding 21 on the left side is connected to the first through-hole winding 21 in the middle through the first surface winding 22 disposed on the lower surface of the central magnetic post 11, and the first through-hole winding 21 in the middle is connected to the first through-hole winding 21 on the right side through the first surface winding 22 disposed on the upper surface of the central magnetic post 11, forming a single turn of winding. (See attached diagram) Figure 3The diagram shows a schematic of the winding method of the first winding 2.

[0029] Furthermore, the second winding 3 includes a second through-hole winding 31 and a second surface winding 32. The second through-hole winding 31 is located inside the through hole 12, and the second surface winding 32 is disposed on the upper and lower surfaces of the central magnetic post 11. Specifically, the winding direction is as follows: the second through-hole winding 31 on the left side is connected to the second through-hole winding 31 in the middle through the second surface winding 32 disposed on the upper surface of the central magnetic post 11, and the second through-hole winding 31 in the middle is connected to the second through-hole winding 31 on the right side through the second surface winding 32 disposed on the lower surface of the central magnetic post 11, forming a winding with a winding direction opposite to that of the first winding 2.

[0030] Furthermore, the third winding 4 includes a third through-hole winding 41 and a third surface winding 42. The third through-hole winding 41 is located inside the through hole 12, and the third surface winding 42 is disposed on the upper and lower surfaces of the central magnetic post 11, with the specific winding direction being the same as that of the first winding 2.

[0031] In this embodiment, the second winding 3 is located between the first winding 2 and the third winding 4. However, it can be rearranged in any other spatial order without affecting the function of the inductor. In this embodiment, the winding direction of the second winding 3 is opposite to that of the first winding 2 and the third winding 4, and the inductor current satisfies… The phase relationship is such that a three-phase positively coupled inductor structure is achieved. Those skilled in the art can also replace it with the same inductor current direction and winding direction for the three phases to achieve positive coupling. In this embodiment, the three-phase inductor current and winding direction are parallel and parallel. If adjacent windings are placed at a certain angle in the same plane, the same function can be achieved.

[0032] More specifically, the first winding 2, the second winding 3, and the third winding 4 pass through two central magnetic pillars 11 on the same plane from above and below, respectively. The magnetic flux in the two central magnetic pillars 11 is opposite to each other and is in the same direction as the magnetic flux generated by the other phase windings. The number of central magnetic pillars 11 can also be set to one or more, as long as the magnetic flux is in the same direction as the other phase windings, the same function can be achieved.

[0033] Furthermore, the inductor described in this embodiment achieves a three-phase positive coupling structure through via windings and surface windings. The same function can also be achieved by 3D integration inductors formed by drilling holes in a low-temperature co-fired ceramic (LTCC) substrate, filling with silver, and sintering.

[0034] The method for manufacturing the inductor described in this embodiment is as follows: First, prepare an FR4 substrate with a thickness of about 1mm and a rectangular cavity for embedding the magnetic core 1. At the same time, prepare multiple isolation layers and six copper layers as the medium and conductor materials for forming the winding. Then, the magnetic core 1 is embedded in the rectangular cavity of the FR4 substrate; Then, a first via winding 21, a second via winding 31, and a third via winding 41 are sequentially arranged in the through hole 12. A first surface winding 22, a second surface winding 32, and a third surface winding 42 are respectively arranged on the upper and lower surfaces of the central magnetic post 11. The specific arrangement method of the windings is to form the conductive paths of the first via winding 21, the second via winding 31, the third via winding 41, and the corresponding first surface winding 22, the second surface winding 32, and the third surface winding 42 on the corresponding copper layers by laser drilling and patterning processes. The via holes formed by laser drilling are electrically connected between layers through electroplating or copper filling processes to improve the current carrying capacity. Finally, the FR4 substrate with embedded magnetic core 1, the copper layers with fabricated windings, and multiple isolation layers are aligned and stacked in a preset order. Then, a hydraulic press is used to press them together under specific temperature and pressure conditions. During the pressing process, the molten high thermal conductivity interface material bonds the layers together to form a complete inductor. Among them, magnetic core 1 is located in the middle fourth and fifth copper layers.

[0035] The laminated structure of the inductor described in this embodiment is shown in the attached figure. Figure 4 As shown.

[0036] Example 2: This embodiment analyzes the inductance density of the inductor described in Embodiment 1.

[0037] First, the formula for calculating the inductance density of a basic inductor unit consisting of a one-turn winding is: ; In the formula, Represents inductance density. Represents self-perception, This represents the volume of the basic unit of an inductor.

[0038] The formula for calculating the inductance density of an inductor integrated from three-phase windings is as follows: ; In the formula, For mutual intuition, This represents the volume of the magnetic core.

[0039] As can be seen from the above formula, the closer the adjacent windings are, the greater the mutual inductance; the greater the mutual inductance, the greater the total inductance value, and the greater the inductance density.

[0040] Example 3: This embodiment applies the inductor described in Embodiment 1 to a switched capacitor converter to verify the performance of the inductor of the present invention.

[0041] When this invention is applied to switched-capacitor converters, the external circuitry and active components are placed on the top layer (i.e., the top layer) above the inductor, achieving 3D integration of passive components, as shown in the attached figure. Figure 5 As shown, when the output power reaches 180W, the power density of the switched capacitor converter based on this invention reaches 2475W / in. 3 The power density of switched capacitor converters based on traditional solutions is only 1235W / in. 3 As can be seen, the power density of the switched capacitor converter based on the present invention is increased by nearly two times. Due to the low loss of the inductor described in the present invention, the peak efficiency of the present invention reaches 97.35% and the full-load efficiency reaches 94.18% when applied to the switched capacitor converter. Therefore, the inductor described in the present invention has the potential to be applied to high-efficiency, high-power-density, and highly integrated converters.

[0042] As attached Figure 6 The image shows a comparison between a physical switched-capacitor converter based on the inductor described in this invention and a physical switched-capacitor converter based on a discrete inductor. (The image includes a reference to an appendix.) Figure 6 (a) is a photograph of a switched-capacitor converter based on the inductor described in this invention. Figure 6 (b) is a photograph of a switched-capacitor converter based on discrete inductors. (Attached) Figure 6 (a) The overall dimensions of the switched capacitor converter are 50mm in length and 35mm in width. Figure 6 (b) The overall dimensions of the switched capacitor converter are 56mm in length and 38mm in width. The comparison results show that the switched capacitor converter based on the inductor described in this invention is significantly smaller in size and has a higher integration, effectively reducing the space waste of the switched capacitor converter topology.

[0043] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A three-phase positively coupled inductor for a switched-capacitor converter, comprising: The printed circuit board is characterized by further comprising: A magnetic core (1) is embedded inside the printed circuit board; The first winding (2) is disposed through the magnetic core (1); The second winding (3) is disposed through the magnetic core (1) and is in the opposite winding direction to the first winding (2); The third winding (4) is disposed through the magnetic core (1) and has the same winding direction as the first winding (2).

2. A three-phase positively coupled inductor for a switched-capacitor converter according to claim 1, characterized in that, The configuration method for the inductor when connected to the switched capacitor converter circuit is as follows: The direction of the current flowing through the second winding (3) is opposite to the direction of the current flowing through the first winding (2), and the direction of the current flowing through the third winding (4) is the same as the direction of the current flowing through the first winding (2).

3. A three-phase positively coupled inductor for a switched-capacitor converter according to claim 2, characterized in that, The magnetic core (1) is provided with: Multiple central magnetic pillars (11) are used to wind the first winding (2), the second winding (3) and the third winding (4).

4. A three-phase positively coupled inductor for a switched-capacitor converter according to claim 3, characterized in that, The first winding (2) includes: The first through-hole winding (21) is disposed on both sides of the plurality of central magnetic pillars (11); The first surface winding (22) is disposed on the upper and lower surfaces of the plurality of central magnetic pillars (11) and is connected to the first through-hole winding (21).

5. A three-phase positively coupled inductor for a switched-capacitor converter according to claim 4, characterized in that, The second winding (3) includes: The second through-hole winding (31) is disposed on one side of the first through-hole winding (21); The second surface winding (32) is disposed on the upper and lower surfaces of the plurality of central magnetic pillars (11) and is connected to the second through-hole winding (31).

6. A three-phase positively coupled inductor for a switched-capacitor converter according to claim 5, characterized in that, The third winding (4) includes: The third through-hole winding (41) is disposed on one side of the second through-hole winding (31); The third surface winding (42) is disposed on the upper and lower surfaces of the plurality of central magnetic pillars (11) and is connected to the third through-hole winding (41).

7. The method for manufacturing a three-phase positively coupled inductor for a switched-capacitor converter as described in claim 6, characterized in that, The method includes the following steps: The magnetic core (1) is embedded inside the printed circuit board; A first through-hole winding (21), a second through-hole winding (31) and a third through-hole winding (41) are arranged sequentially on both sides of multiple central magnetic pillars (11). A first surface winding (22), a second surface winding (32), and a third surface winding (42) are respectively provided on the upper and lower surfaces of multiple central magnetic pillars (11). Inductors are formed by stacking and laminating the layers of a printed circuit board.

8. A switched capacitor converter, characterized in that: The switched capacitor converter includes the inductor as described in any one of claims 1-6.

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