Magnetic element and topological structure for interleaving flyback converter

Abstract

The utility model provides a magnetic element and a topological structure used for an interleaving flyback converter, and relates to the technical field of power electronics, and the magnetic element comprises a magnetic core structure and a coil structure. The magnetic core structure comprises an upper magnetic core base, a lower magnetic core base, N magnetic core middle columns and at least one side column, wherein the upper magnetic core base and the lower magnetic core base are oppositely arranged, the N magnetic core middle columns and the at least one side column are arranged between the upper magnetic core base and the lower magnetic core base, and N is a natural number larger than 1. The coil structure comprises N coils wound on the magnetic core middle columns respectively, the winding directions of the coils on the adjacent magnetic core middle columns are opposite, and an air gap is formed in at least one of the three positions including the position between the upper bottom face of each magnetic core middle column and the upper magnetic core base, the position between the lower bottom face of each magnetic core middle column and the lower magnetic core base and the side face of each magnetic core middle column. According to the magnetic element, the magnetic core columns are integrated on the same magnetic core base, and the winding directions of the coils of the adjacent magnetic core middle columns are opposite, so that the purposes of reducing the weight of the magnetic core and reducing the loss of the magnetic core can be achieved.

Description

Technical Field

[0001] This application belongs to the field of power electronics technology. Specifically, it relates to a magnetic component and a topology structure for an interleaved parallel flyback converter. Background Art

[0002] Due to advantages such as simple structure and low cost, the flyback converter has great commercial attractiveness. Currently, in the application scenario of high-power switching power supplies, by interleaving and paralleling flyback converters, while expanding the power, the input and output currents can become more and more continuous, thereby alleviating the electromagnetic interference problem caused by the discontinuous input and output currents of the flyback converter.

[0003] However, in traditional multi-phase parallel flyback converters, each flyback conversion module has an independent flyback transformer, which has the disadvantages of large magnetic component volume and weight, resulting in high core loss. Summary of the Utility Model

[0004] Aiming at at least one problem existing in the prior art, this application provides a magnetic component and a topology structure for an interleaved parallel flyback converter.

[0005] According to the first aspect of this application, a magnetic component is provided, which includes a core structure and a coil structure, wherein:

[0006] The core structure includes an upper core base and a lower core base arranged oppositely, and N core middle columns and at least one side column arranged between the upper core base and the lower core base, where N is a natural number greater than 1;

[0007] The coil structure includes N coils respectively wound around the core middle columns, wherein:

[0008] The winding directions of the coils on adjacent core middle columns are opposite;

[0009] An air gap is provided at least at one of the three positions: between the upper bottom surface of the core middle column and the upper core base, between the lower bottom surface of the core middle column and the lower core base, and the side surface of the core middle column.

[0010] In some alternative ways of this embodiment, the N core middle columns are located on the same side of the side column.

[0011] In some alternative ways of this embodiment, the centers of the orthographic projections of the core middle columns on the upper core base or the lower core base are on a straight line.

[0012] According to the second aspect of this application, a topology structure for an interleaved parallel flyback converter is provided, which includes: a voltage source, an absorption circuit, a power unit, and an output circuit, wherein:

[0013] The power unit includes N power circuits connected in parallel. Each power circuit includes a clamping tube, a transformer, a primary switching tube, and a secondary switching tube. Among them, the clamping tube of the i-th power circuit is an active clamping tube, and the clamping tubes of the remaining (N - 1) power circuits are passive clamping tubes. N is a natural number greater than 1, and 1 ≤ i ≤ N;

[0014] Among them, the absorption circuit, the power unit are connected to the voltage source. The absorption circuit is used to absorb the leakage inductance energy of the N transformers, and release the leakage inductance energy of the N transformers to the output circuit through the active clamping tube;

[0015] Among them, each transformer includes the middle column of the magnetic core described in the first aspect and the coil wound around the middle column of the magnetic core.

[0016] In some alternative embodiments of the present embodiment, the i-th power circuit includes an active clamping tube, the i-th transformer, the i-th primary switching tube, and the i-th secondary switching tube, where:

[0017] The i-th transformer includes an i-th coil, and the i-th coil includes an i-th primary winding and an i-th secondary winding;

[0018] The same-named end of the i-th primary winding is connected to the absorption circuit;

[0019] The non-same-named end of the i-th primary winding is connected to the source electrode of the active clamping tube and the drain electrode of the i-th primary switching tube;

[0020] The non-same-named end of the i-th secondary winding is connected to the positive electrode of the i-th secondary switching tube;

[0021] The same-named end of the i-th secondary winding, the negative electrode of the i-th secondary switching tube are connected to the output circuit;

[0022] The drain electrode of the active clamping tube is connected to the absorption circuit, and the gate electrode of the active clamping tube is used to input a clamping control signal. Among them, the clamping control signal is used to control the conduction and cut-off of the active clamping tube;

[0023] The source electrode of the i-th primary switching tube is connected to the negative electrode of the voltage source, and the gate electrode of the i-th primary switching tube is used to input an i-th drive control signal. Among them, the i-th drive control signal is used to control the conduction and cut-off of the i-th primary switching tube.

[0024] In some alternative embodiments of the present embodiment, the circuit structures and circuit connection relationships of the remaining (N - 1) power circuits are the same. Among them, the m-th power circuit includes an m-th passive clamping tube, an m-th transformer, an m-th primary switching tube, and an m-th secondary switching tube, where:

[0025] The m-th transformer includes an m-th coil, and the m-th coil includes an m-th primary winding and an m-th secondary winding;

[0026] The same-named end of the m-th primary winding is connected to the positive pole of the voltage source;

[0027] The non-same-named end of the m-th primary winding is connected to the positive pole of the m-th passive clamping tube and the drain of the m-th primary switch tube;

[0028] The non-same-named end of the m-th secondary winding is connected to the positive pole of the m-th secondary switch tube;

[0029] The same-named end of the m-th secondary winding, the negative pole of the m-th secondary switch tube are connected to the output circuit;

[0030] The negative pole of the m-th passive clamping tube is connected to the absorption circuit;

[0031] The source of the m-th primary switch tube is connected to the negative pole of the voltage source, and the gate of the m-th primary switch tube is used to input an m-th drive control signal, where the m-th drive control signal is used to control the on and off of the m-th primary switch tube, where 1 ≤ m ≤ N and m ≠ i.

[0032] In some alternative ways of this embodiment, the phase difference between the drive control signals of two adjacent primary switch tubes is 360° / N.

[0033] In some alternative ways of this embodiment, the absorption circuit includes a clamping capacitor, where:

[0034] The absorption circuit is used to absorb the leakage inductance energy of the N transformers through the clamping capacitor, and release the leakage inductance energy of the N transformers to the output circuit through the active clamping tube.

[0035] In some alternative ways of this embodiment, the first end of the clamping capacitor is connected to the same-named end of the primary windings of the N transformers and the positive pole of the voltage source, and the second end of the clamping capacitor is connected to the drain of the active clamping tube and the negative poles of all the passive clamping tubes.

[0036] In some alternative ways of this embodiment, the output circuit includes an output capacitor, where:

[0037] The first end of the output capacitor is connected to the negative poles of all the secondary switch tubes;

[0038] The second end of the output capacitor is connected to the same-named ends of the secondary windings of all the transformers.

[0039] In some alternative embodiments of the present embodiment, the transistor type of the active clamping tube is a silicon MOSFET, a silicon carbide MOSFET, or a gallium nitride device;

[0040] The transistor type of the passive clamping tube is a silicon diode or a silicon carbide diode;

[0041] The transistor type of the primary side switching tube is a silicon MOSFET, a silicon carbide MOSFET, or a gallium nitride device;

[0042] The transistor type of the secondary side switching tube is a diode or a MOSFET.

[0043] A magnetic component and a topology structure for a interleaved flyback converter provided by the present application integrate magnetic core columns on the same magnetic core base and set the winding directions of coils on adjacent middle magnetic core columns to be opposite, so as to achieve the purpose of reducing the weight of the magnetic core and the core loss; in addition, by sharing a clamping capacitor among multiple parallel power circuits, the number of power switching tubes in the present application is greatly reduced compared to the topology architecture of traditional multi-channel interleaved flyback converters with active clamping, effectively reducing the cost loss caused by a large number of switching tubes in the prior art; at the same time, the active clamping tube (active clamp) can recover all the energy of the transformer leakage inductance, reducing the energy loss caused by the transformer leakage inductance, thereby further improving the energy conversion efficiency of the flyback converter while reducing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0045] Figure 1 One of the schematic structural diagrams of the magnetic component according to an embodiment of the present application;

[0046] Figure 2 Another schematic structural diagram of the magnetic component according to an embodiment of the present application;

[0047] Figure 3 Another schematic structural diagram of the magnetic component according to an embodiment of the present application;

[0048] Figure 4 Another schematic structural diagram of the magnetic component according to an embodiment of the present application;

[0049] Figure 5 Another schematic structural diagram of the magnetic component according to an embodiment of the present application;

[0050] Figure 6 The sixth structural schematic diagram of the magnetic component according to the embodiment of the present application;

[0051] Figure 7 The seventh structural schematic diagram of the magnetic component according to the embodiment of the present application;

[0052] Figure 8 The structural diagram of the topology of the N-channel interleaved flyback converter according to the embodiment of the present application;

[0053] Figure 9 The structural schematic diagram of integrating N transformers into a magnetic component in the topology of the N-channel interleaved flyback converter according to the embodiment of the present application;

[0054] Figure 10 The structural diagram of the topology of the 2-channel interleaved flyback converter according to the embodiment of the present application;

[0055] Figure 11 The structural schematic diagram of integrating 2 transformers into a magnetic component in the topology of the 2-channel interleaved flyback converter according to the embodiment of the present application;

[0056] Figure 12 The structural diagram of the topology of the traditional 2-channel interleaved flyback converter;

[0057] Figure 13 The structural diagram of the topology of the 3-channel interleaved flyback converter according to the embodiment of the present application;

[0058] Figure 14 The structural schematic diagram of integrating 3 transformers into a magnetic component in the topology of the 3-channel interleaved flyback converter according to the embodiment of the present application;

[0059] Figure 15 The structural diagram of the topology of the traditional 3-channel interleaved flyback converter;

[0060] Figure 16 The structural diagram of the topology of the traditional N-channel interleaved flyback converter;

[0061] Figure 17 The exemplary flowchart of the leakage inductance energy recovery method according to the embodiment of the present application;

[0062] Figure 18 The structural diagram of the topology of the 4-channel interleaved flyback converter according to the embodiment of the present application;

[0063] Figure 19 For Figure 18 One of the exemplary waveform diagrams of absorbing and releasing leakage inductance energy for the shown topology;

[0064] Figure 20 For Figure 18 Exemplary waveform diagram two for leakage inductance energy recycling and release of the shown topology structure. Specific implementation manners

[0065] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0066] To solve at least one problem raised in the background art, such as Figure 1 shown, an embodiment of the present application provides a magnetic component, including a magnetic core structure and a coil structure, wherein:

[0067] Figure 2 The schematic diagram of the magnetic core structure is shown. As Figure 2 shown, the magnetic core structure includes an upper magnetic core base 101 and a lower magnetic core base 103 arranged oppositely, and N magnetic core middle columns 102 and at least one side column 104 arranged between the upper magnetic core base and the lower magnetic core base, where N is a natural number greater than 1;

[0068] As Figure 1 shown, the coil structure includes N coils 201 respectively wound around each of the magnetic core middle columns, and the winding directions of the coils on adjacent magnetic core middle columns are opposite.

[0069] In this embodiment, the coil directions of adjacent magnetic core middle columns are opposite. For example, if the winding method of the coil on the m-th magnetic core middle column from left to right is clockwise winding, then the winding method of the coil on the (m + 1)-th magnetic core middle column is counterclockwise winding. The effect achieved thereby is that the magnetic flux directions flowing through adjacent magnetic core middle columns are opposite. Specifically, refer to Figure 3 , which is Figure 1 the top view of, which shows the winding directions of the coils wound around the magnetic core middle columns. For example, the coil on the first magnetic core middle column O1 is wound clockwise, the coil on the second magnetic core middle column O2 is wound counterclockwise, the coil on the third magnetic core middle column O3 is wound clockwise, and so on. By analogy, the winding directions of the coils on all magnetic core middle columns can be determined, and the present application will not elaborate herein.

[0070] In this embodiment, as Figure 2 shown, N magnetic core middle columns are arranged in a row. Specifically, refer to Figure 3, the centers of the orthographic projections of the middle columns of the respective magnetic cores on the upper magnetic core base or the lower magnetic core base are on a straight line. Specifically, O1, O2, O3... ON are on a straight line. Additionally, in this embodiment, as Figure 2 shown, all the middle columns of the magnetic cores are on the same side of the side columns.

[0071] It should also be noted that in this embodiment, an air gap is provided on each middle column of the magnetic core. Specifically, the position where the air gap is provided can be between the upper bottom surface of the middle column of the magnetic core and the upper magnetic core base (i.e., Figure 1 the label 1 position), between the lower bottom surface of the middle column of the magnetic core and the lower magnetic core base (i.e., Figure 1 the label 2 position), and on the side surface of the middle column of the magnetic core (for example, Figure 1 the label 3 position). Specifically:

[0072] As Figure 4 shown, the air gap is provided between the upper bottom surface of the middle column 102 of the magnetic core and the upper magnetic core base 101; the air gap is provided on the side surface of the middle column 102 of the magnetic core. For example, Figure 5 and Figure 6 shown, the air gap is provided at the middle position of the middle column 102 of the magnetic core; as Figure 7 shown, the air gap is provided between the lower bottom surface of the middle column 102 of the magnetic core and the lower magnetic core base 103.

[0073] It should also be noted that the air gaps on the respective middle columns of the magnetic cores can be a single air gap as Figures 4 - 7 shown, or multiple segmented air gaps. That is to say, in this embodiment, the air gap is provided at at least one of the three positions between the upper bottom surface of each middle column of the magnetic core and the upper magnetic core base, between the lower bottom surface of each middle column of the magnetic core and the lower magnetic core base, and on the side surface of each middle column of the magnetic core.

[0074] For example, for the first middle column of the magnetic core, two air gaps can be provided at the label 1 position and the label 2 position of the first middle column of the magnetic core; multiple air gaps can also be provided at the label 3 position of the first middle column of the magnetic core, etc. The present application does not make any limitations in this regard.

[0075] The magnetic component provided in this embodiment, by integrating N middle columns of the magnetic cores on the same magnetic core base and setting the winding directions of the coils on adjacent middle columns of the magnetic cores to be opposite, on the basis of being able to make the magnetic flux directions flowing through adjacent middle columns of the magnetic cores opposite, achieves the purpose of reducing the weight of the magnetic core and reducing the magnetic core loss.

[0076] Furthermore, due to the existence of leakage inductance, the energy conversion efficiency of the flyback converter is limited. The industry has proposed the active clamp technology to recover the energy of the leakage inductance of the flyback converter and improve the energy conversion efficiency. However, the applicant has found that although the more flyback converters in interleaved parallel connection, the more continuous the input current and output current will be, making it more suitable for high-power application scenarios, if all the power circuits in the multi-path interleaved parallel flyback converter adopt the active clamp technology, problems such as doubling the number of power switching tubes and a significant increase in cost will be faced.

[0077] Based on this, an embodiment of the present application further provides a topology structure for an interleaved parallel flyback converter, as Figure 8 shown. The topology structure includes: a voltage source Uin, an absorption circuit 1, a power unit 2, and an output circuit 3, where:

[0078] The power unit 2 includes N parallel power circuits. Each power circuit includes a clamping tube, a transformer, a primary side switching tube, and a secondary side switching tube. Among them, the clamping tube of the i-th power circuit 2i is the active clamping tube Va, and the clamping tubes of the remaining (N - 1) power circuits are passive clamping tubes. N is a natural number greater than 1, and 1 ≤ i ≤ N;

[0079] Among them, the absorption circuit 1 and the power unit 2 are connected to the voltage source Uin. The absorption circuit 1 is used to absorb the leakage inductance energy of N transformers (all transformers) and release the leakage inductance energy of all transformers to the output circuit 3 through the active clamping tube Va; each transformer includes the magnetic core middle column of the foregoing embodiment and the coil wound around the magnetic core middle column.

[0080] That is to say, in the topology structure for the parallel flyback converter of the present application, N flyback converters are connected in parallel. Each flyback converter includes a transformer. The N transformers of this embodiment are integrally designed. Each transformer includes the magnetic core middle column of the foregoing embodiment and the coil wound around the magnetic core middle column. The coil satisfies the winding method of the foregoing embodiment.

[0081] In the circuit diagram and magnetic core structure of the N-way power modules in interleaved parallel connection, the two windings of the m-th transformer are wound around the m-th magnetic core middle column. Among them, the winding directions of the coils of the m-th transformer and the (m + 1)-th transformer are opposite, where m > 0 and m <= N. It should be understood that the coils on each magnetic core middle column include a primary side winding and a secondary side winding, and the winding methods of the primary side winding and the secondary side winding are the same. The specific explanation is as follows: If the primary side winding of the m-th transformer starts winding from the m-A end on the m-th magnetic core middle column in the clockwise direction, then the primary side coil of the (m + 1)-th transformer adjacent to the m-th transformer starts winding from the (m + 1)-B end on the (m + 1)-th magnetic core middle column, and the winding direction should be counterclockwise.

[0082] Take Figure 8 as an example to illustrate the above winding method. The N-way power module includes N transformers, namely transformer T1, transformer T2, transformer T3... transformer TN. Among them, the two windings of transformer T1 are wound on the middle column of the first magnetic core, the two windings of transformer T2 are wound on the middle column of the second magnetic core, and the two windings of transformer T3 are wound on the middle column of the third magnetic core. The winding directions of the primary coils (primary windings) of transformer T1 and transformer T2 are opposite, and the winding directions of the primary coils of transformer 1 and transformer 3 are the same, that is, the winding directions of transformer T2 and transformer T3 are opposite.

[0083] The specific explanation is as follows: As Figure 9 shown, if the primary coil of transformer T1 starts winding from the 1-A end on the middle column of the first magnetic core, and the winding direction is clockwise, then the primary coil of the corresponding transformer T2 starts winding from the 2-B end on the middle column of the second magnetic core, and the winding direction should be counterclockwise. The primary coil of the corresponding transformer T3 starts winding from the 3-A end on the middle column of the third magnetic core, and the winding direction should be clockwise. The winding methods of the coils of the remaining transformers also follow the principle that the winding directions of the coils of adjacent transformers are opposite. This application will not elaborate here.

[0084] In addition, the applicant found that for a transformer, due to the leakage magnetic flux generated by the incomplete coupling of the magnetic flux between windings or between the winding and the iron core, part of the magnetic field cannot completely capture all the windings, resulting in an induced electromotive force. This part of the energy (i.e., leakage inductance energy) will be dissipated in the transformer, affecting the efficiency and performance of the transformer.

[0085] Therefore, based on the topology structure of the interleaved parallel flyback converter in this embodiment, the absorption circuit 1 can absorb the leakage inductance energy of all transformers, and release the leakage inductance energy of all transformers to the output circuit 3 through the active clamping tube Va, thereby improving the energy conversion efficiency of the flyback converter; and in this embodiment, N parallel power circuits share one absorption circuit, which can reduce the number of power switching tubes and reduce costs.

[0086] Furthermore, as Figure 8 shown, the i-th power circuit 2i includes an active clamping tube Va, the i-th transformer Ti, the i-th primary switching tube Qi, and the i-th secondary switching tube Di, where:

[0087] The i-th transformer includes an i-th coil, and the i-th coil includes an i-th primary winding and an i-th secondary winding;

[0088] The same-name end of the i-th primary winding is connected to the absorption circuit 1;

[0089] The non - corresponding terminal of the i - th primary winding is connected to the source of the active clamping transistor Va and the drain of the i - th primary switching transistor Qi;

[0090] The non - corresponding terminal of the i - th secondary winding is connected to the positive electrode of the i - th secondary switching transistor Di;

[0091] The corresponding terminal of the i - th secondary winding, the negative electrode of the i - th secondary switching transistor Di are connected to the output circuit 3;

[0092] The drain of the active clamping transistor Va is connected to the absorption circuit 1, and the gate of the active clamping transistor Va is used to input a clamping control signal, where the clamping control signal is used to control the on - off of the active clamping transistor Va;

[0093] The source of the i - th primary switching transistor Qi is connected to the negative electrode of the voltage source Uin, and the gate of the i - th primary switching transistor Qi is used to input the i - th drive control signal, where the i - th drive control signal is used to control the on - off of the i - th primary switching transistor Qi.

[0094] Further, as Figure 8 shown, the circuit structures and circuit connection relationships of the remaining (N - 1) power circuits are the same. Taking the circuit structure and circuit connection relationship of the m - th power circuit as an example for illustration:

[0095] The m - th power circuit 2m includes the m - th passive clamping transistor Vpm, the m - th transformer Tm, the m - th primary switching transistor Qm, and the m - th secondary switching transistor, where:

[0096] The m - th transformer includes the m - th coil, and the m - th coil includes the m - th primary winding and the m - th secondary winding;

[0097] The corresponding terminal of the m - th primary winding is connected to the positive electrode of the voltage source Uin;

[0098] The non - corresponding terminal of the m - th primary winding is connected to the positive electrode of the m - th passive clamping transistor Vpm and the drain of the m - th primary switching transistor Qm;

[0099] The non - corresponding terminal of the m - th secondary winding is connected to the positive electrode of the m - th secondary switching transistor Dm;

[0100] The corresponding terminal of the m - th secondary winding, the negative electrode of the m - th secondary switching transistor Dm are connected to the output circuit 3;

[0101] The negative electrode of the m - th passive clamping transistor Vpm is connected to the absorption circuit 1;

[0102] The source of the m-th primary side switching transistor Qm is connected to the negative pole of the voltage source Uin, and the gate of the m-th primary side switching transistor Qm is used to input the m-th driving control signal, where the m-th driving control signal is used to control the conduction and cut-off of the m-th primary side switching transistor, where m further satisfies 1 ≤ m ≤ N and m ≠ i.

[0103] It should be noted that, in order to achieve interleaved parallel connection between each power circuit and make the input and output currents continuous, in this embodiment, the phase difference between the driving control signals of two adjacent primary side switching transistors is 360° / N. That is to say, the phase difference between two adjacent driving control signals among the first driving control signal, the second driving control signal, the third driving control signal... the N-th driving control signal is 360° / N.

[0104] In an alternative manner of this embodiment, as Figure 8 shown, the absorption circuit 1 includes a clamping capacitor C1, where:

[0105] The absorption circuit is used to absorb the leakage inductance energy of N transformers through the clamping capacitor C1, and release the leakage inductance energy of the N transformers to the output circuit 3 through the active clamping transistor.

[0106] Wherein, the first end of the clamping capacitor C1 is connected to the same-name end of the primary windings of the N transformers (i.e., all transformers) and the positive pole of the voltage source Uin, and the second end of the clamping capacitor is connected to the drain of the active clamping transistor and the negative poles of all passive clamping transistors.

[0107] In another alternative manner of this embodiment, as Figure 10 shown, the absorption circuit 1 further includes a clamping resistor R1, where the first end of the clamping resistor R1 is connected to the positive pole of the voltage source Uin and the first end of the clamping capacitor C1; the second end of the clamping resistor R1 is connected to the second end of the clamping capacitor C1, the drain of the active clamping transistor and the negative poles of all passive clamping transistors.

[0108] See Figure 8 , the N power circuits connected in parallel share a clamping capacitor C1. When each power circuit is conducting, the clamping capacitor C1 can absorb the leakage inductance energy of the corresponding transformer, and when the active clamping transistor is conducting, release the absorbed leakage inductance energy of the transformer to the output circuit.

[0109] It should be noted that the active clamping tube conducts after the i-th primary switch tube is turned off, and before the i-th primary switch tube is turned off, the remaining (N - 1) primary switch tubes conduct alternately. That is to say, before the i-th primary switch tube is turned off, the clamping capacitor can absorb all the leakage inductance energy of the transformer, and when the active clamping tube conducts, the absorbed leakage inductance energy of the transformer is released to the output circuit through the active clamping tube, thereby improving the energy conversion efficiency of the interleaved flyback converter.

[0110] Further, as Figure 8 shown, the output circuit 3 includes an output capacitor C0, where:

[0111] The first end of the output capacitor C0 is connected to the negative electrodes of all the secondary switch tubes; the second end of the output capacitor C0 is connected to the same-name ends of the secondary windings of all the transformers. It should be understood that, as Figure 8 shown, the output circuit 3 is further externally connected to a load, which will not be elaborated in this application.

[0112] So far, for the topology structure of the interleaved flyback converter proposed in the embodiments of this application, N transformers are integrally designed. Each transformer includes the magnetic core middle column and the coil wound around the magnetic core middle column in the foregoing embodiments, and the coil satisfies the winding method in the foregoing embodiments, so as to achieve the purpose of reducing the weight of the magnetic core and reducing the magnetic core loss; in addition, multiple parallel power circuits share a clamping capacitor, and this clamping capacitor can absorb all the leakage inductance energy of the transformers, making the number of power switch tubes in this application much less than that of the traditional multi-path interleaved active-clamped flyback converter topology, effectively reducing the cost problem caused by the large number of switch tubes in the prior art; at the same time, through one conduction of the active clamping tube (active clamping), all the leakage inductance energy of the transformers can be recovered, that is, the absorbed leakage inductance energy of all the transformers is released to the output circuit through the active clamping tube, reducing the energy loss caused by the transformer leakage inductance, thereby further improving the energy conversion efficiency of the flyback converter while reducing the cost.

[0113] Next, as Figure 10 shown, taking N = 2 and i = 1 as an example, the topology structure of the interleaved flyback converter of this application is described:

[0114] Specifically, Figure 10 is the topology structure of the interleaved parallel connection of the power circuits of a 2-path flyback converter, where: the first power circuit adopts the active clamping technology, and its clamping tube is an active switch tube Va; the second power circuit adopts the traditional passive clamping technology, and its clamping tube is a passive clamping tube Vp2, Figure 10 where the passive clamping tube Vp2 is a diode device, such as a silicon diode or a silicon carbide diode, which is not limited in this application.

[0115] The first power circuit and the second power circuit share a clamping capacitor C1. In this topology, the power switching transistors are the active clamping transistor Va, the first primary switching transistor Q1, and the second primary switching transistor Q2. That is to say, the number of power switching transistors is 3.

[0116] In addition, in Figure 10 the topology where the power circuits of the two-channel flyback converters shown are interleaved and paralleled, there are a total of 2 transformers. The two transformers in this embodiment are integrally designed. Each transformer includes the central leg of the magnetic core and the coil wound around the central leg of the magnetic core in the foregoing embodiment, where the coil satisfies the winding method in the foregoing embodiment.

[0117] Specifically, as Figure 11 shown, the two windings of transformer T1 are wound around the central leg 1 of the magnetic core, and the two windings of transformer T2 are wound around the central leg 2 of the magnetic core. The winding directions of the coils of the two transformers are opposite. The specific explanation is as follows: If the primary coil of transformer 1 starts winding from the 1-A end on the central leg 1 of the magnetic core in the clockwise direction, then the primary coil of the corresponding transformer 2 starts winding from the 2-B end on the central leg 2 of the magnetic core, and the winding direction should be counterclockwise.

[0118] Figure 12 Figure shows a schematic diagram of the interleaved parallel connection of the power circuits of a traditional two-channel active-clamped flyback converter. It can be seen that the number of power switching transistors in the traditional interleaved parallel active-clamped flyback converter is 4, labeled as Y1, Y2, Q1, and Q2 respectively. Based on the fact that the number of power switching transistors in the two-channel interleaved parallel topology of this application is 3, compared with the prior art, the number of power switching transistors in this application is reduced by 25%. And in the topology of the traditional two-channel active-clamped flyback converter, transformer T1 and transformer T2 are separately arranged. Compared with the prior art, transformer T1 and transformer T2 in this application are integrally deployed, so as to achieve the purpose of reducing the weight of the magnetic core and reducing the core loss.

[0119] Next, as Figure 13 shown, taking N = 3 and i = 1 as an example, the topology of the interleaved parallel flyback converter of this application is described:

[0120] Specifically, Figure 13 it is the interleaved parallel topology of the power circuit of a three-channel flyback converter, where: the first power circuit adopts the active clamping technology, and its clamping transistor is an active switching transistor; the second power circuit and the third power circuit adopt the traditional passive clamping technology, and their clamping transistors are the second passive clamping transistor Vp2 and the third passive clamping transistor Vp3 respectively, Figure 4 where the second passive clamping transistor Vp2 and the third passive clamping transistor Vp3 in are diode devices, such as silicon diodes or silicon carbide diodes. This application does not make any limitations in this regard.

[0121] The first power circuit, the second power circuit, and the third power circuit share a clamping capacitor C1. In this topology, the power switching transistors are the active clamping transistor Va, the first primary switching transistor Q1, the second primary switching transistor Q2, and the third primary switching transistor Q3. That is to say, the number of power switching transistors is 4.

[0122] In addition, in Figure 13 the topology where the power circuits of the three isolated flyback converters shown are interleaved and paralleled, a total of 3 transformers are included. The three transformers in this embodiment are integrally designed. Each transformer includes the middle leg of the magnetic core and the coil wound around the middle leg of the magnetic core in the foregoing embodiment, where the coil satisfies the winding method of the foregoing embodiment.

[0123] Specifically, as Figure 14 shown, the two windings of transformer T1 are wound around the middle leg 1 of the magnetic core, and the two windings of transformer T3 are wound around the middle leg 3 of the magnetic core. The winding directions of the primary coils of transformer T1 and transformer T2 are opposite, and the winding directions of the primary coils of transformer T1 and transformer T3 are the same. The specific explanation is as follows: If the primary coil of transformer T1 starts winding from the 1-A end on the middle leg 1 of the magnetic core in the clockwise direction, then the primary coil of the corresponding transformer T2 should start winding from the 2-B end on the middle leg 2 of the magnetic core in the counterclockwise direction, and the primary coil of the corresponding transformer T3 should start winding from the 3-A end on the middle leg 3 of the magnetic core in the clockwise direction.

[0124] Figure 15 shows a schematic diagram of the interleaved parallel connection of the power circuits of a traditional three-way active-clamped flyback converter. It can be seen that the number of power switching transistors in the traditional interleaved parallel active-clamped flyback converter is 6, labeled as Y1, Y2, Y3, Q1, Q2, and Q3 respectively. Based on the fact that the number of power switching transistors in the three-way interleaved parallel topology of this application is 4, compared with the prior art, the number of power switching transistors in this application is reduced by 33%; and in the topology of the traditional three-way active-clamped flyback converter, transformers T1, T2, and T3 are separately arranged. Compared with the prior art, transformers T1, T2, and T3 in this application are integrally deployed, so as to achieve the purpose of reducing the weight of the magnetic core and reducing the core loss.

[0125] Next, with the foregoing Figure 8For example, when the power circuits of an N-channel flyback converter are interleaved and paralleled, where: the first power circuit adopts the active clamp technology, and its clamping transistor is an active switch Va; the remaining (N - 1) power circuits (i.e., the second power circuit, the third power circuit... the Nth power circuit) adopt the passive clamp technology, and their clamping transistors are the second passive clamping transistor Vp2, the third passive clamping transistor Vp3... the Nth passive clamping transistor VpN, and Figure 8 The second passive clamping transistor Vp2, the third passive clamping transistor Vp3... the Nth passive clamping transistor VpN are diode devices, such as silicon diodes or silicon carbide diodes, and this application does not limit this.

[0126] The first power circuit, the second power circuit, the third power circuit... the Nth power circuit share a clamping capacitor C1. In this topology, the power switching transistors are the active clamping transistor Va, the first primary switching transistor Q1, the second primary switching transistor Q2, the third primary switching transistor Q3... the Nth primary switching transistor QN. That is to say, the number of power switching transistors is (N + 1).

[0127] Figure 16 The schematic diagram of the interleaved parallel connection of the traditional N-channel active clamp flyback power module is shown. It can be seen that the number of power switching transistors of the traditional interleaved parallel active clamp flyback converter is 2N, labeled as Y1, Y2, Y3,... YN, Q1, Q2, Q3... QN respectively. Based on the fact that the number of power switching transistors in the N-channel interleaved parallel topology of this application is (N + 1), compared with the prior art, the power transistors in the embodiments of this application are reduced by (N - 1) / 2N; and in the topology of the traditional N-channel active clamp flyback converter, the T1 transformer, the T2 transformer... the TN transformer are separately arranged. Compared with the prior art, the T1 transformer, the T2 transformer... the TN transformer of this application are integrally deployed, so as to achieve the purpose of reducing the weight of the magnetic core and reducing the magnetic core loss.

[0128] It should be noted that in the extreme case, compared with the prior art, the number of power switching transistors in the embodiments of this application can be reduced by nearly 50%, and the cost of the power switching transistors is infinitely close to that of the traditional passive clamp topology. However, the traditional passive clamp topology often cannot recover the energy of the leakage inductance. Therefore, it is further verified that the topology proposed in the embodiments of this application for the interleaved parallel flyback converter can not only reduce the cost loss of the power switching transistors, but also recover all the energy of the transformer leakage inductance, reduce the energy loss caused by the transformer leakage inductance, and improve the energy conversion efficiency of the flyback converter.

[0129] It should be noted that in the present application, the transistor type of the active clamping tube is a silicon MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor), a silicon carbide MOSFET, or a gallium nitride device; the transistor type of the passive clamping tube is a silicon diode or a silicon carbide diode; the transistor type of the primary side switching tube is a silicon MOSFET, a silicon carbide MOSFET, or a gallium nitride device; the transistor type of the secondary side switching tube is a diode or a MOSFET. It should be understood that the device symbols in the drawings are only examples and do not constitute improper limitations to the present application.

[0130] To further reduce the energy loss of the power switching tubes, based on the topological structure proposed in the foregoing embodiment, as Figure 17 shown, another embodiment of the present application provides a method for recovering leakage inductance energy, including:

[0131] Step 10: Configure the phases of the drive control signals of two adjacent primary side switching tubes to differ by 360° / N;

[0132] Step 20: The absorption circuit absorbs the leakage inductance energy of N transformers, and releases the leakage inductance energy of the N transformers to the output circuit through the conduction of the active clamping tube.

[0133] It should be noted that since the principle of the problem solved by this method for recovering leakage inductance energy relies on the foregoing topological structure, the foregoing embodiment and the resulting beneficial effects are equally applicable to this embodiment. Therefore, the same parts will not be described again.

[0134] In this embodiment, let the process from the conduction to the turn-off of all the primary side switching tubes be a power switching cycle. The clamping control signal is used to control the active clamping tube to conduct after every r power switching cycles, and perform one absorption and release of the leakage inductance energy, where r is a natural number greater than 0.

[0135] That is to say, as Figure 8 shown, N flyback converters share a leakage inductance energy absorption capacitor, that is, the clamping capacitor C1, and share a leakage inductance energy recovery clamping power switching tube, that is, the active clamping tube Va. Under the control of the clamping control signal, the active clamping tube can conduct once every r power switching cycles to perform one recovery of the leakage inductance energy.

[0136] Based on the process from the conduction to the turn-off of all the primary side switching tubes being a power switching cycle, in r power switching cycles, the clamping capacitor continuously absorbs the energy of (r×N) leakage inductances, and by turning on the active clamping tube once, the energy of (r×N) leakage inductances continuously absorbed by the clamping capacitor is released to the output circuit at one time.

[0137] In this embodiment, for the application scenario of N flyback converters in parallel, through the shared clamping capacitor, the absorption of leakage inductance energy can be achieved (r×N) times. Through one conduction of the active clamping transistor, the energy of (r×N) leakage inductances is recycled to the output circuit. Among them, since there is a corresponding loss every time the active clamping power switch transistor is turned on, the larger r is, the fewer times the active clamping power switch transistor is turned on, the less loss is brought, and the higher the efficiency of recycling energy is.

[0138] Next, Figure 18 Taking the interleaved parallel topology of the power circuit of the 4-way flyback converter shown as an example for explanation. Among them, i is 1. The first power circuit, the second power circuit, the third power circuit, and the fourth power circuit share a clamping capacitor C1. The gate of the first primary switch Q1 inputs the first drive control signal, the gate of the second primary switch Q2 inputs the second drive control signal, the gate of the third primary switch Q3 inputs the third drive control signal, and the gate of the fourth primary switch Q4 inputs the fourth drive control signal.

[0139] As Figure 19 and Figure 20 shown, the phase difference between two adjacent drive control signals among the first drive control signal, the second drive control signal, the third drive control signal, and the fourth drive control signal is 90°, so as to realize the interleaved conduction of the first power circuit, the second power circuit, the third power circuit, and the fourth power circuit.

[0140] It should be noted that as Figure 19 shown, according to the waveform diagrams of the first drive control signal, the second drive control signal, the third drive control signal, and the fourth drive control signal, it can be seen that the first primary switch is continuously in the on state on the left side of the dotted line l1 (to the left of the abscissa 25.01) and switches to the off state at the dotted line l1. The second primary switch, the third primary switch, and the fourth primary switch also complete one conduction and turn-off on the left side of the dotted line l1.

[0141] According to the waveform diagram of the clamping control signal of the active clamping transistor, it can be seen that on the left side of the dotted line l1, the clamping control signal is at a low level, the active clamping transistor is turned off, and the clamping capacitor continuously absorbs the leakage inductance energy of the fourth transformer, the third transformer, the second transformer, and the first transformer. From the waveform diagram of the clamping capacitor, after the fourth primary switch, the third primary switch, the second primary switch, and the first primary switch are turned off, the voltage of the clamping capacitor will increase by one step, indicating that the clamping capacitor absorbs the leakage inductance energy of the corresponding power circuit.

[0142] At the dotted line l1, the first drive control signal (the i-th drive control signal) switches to a low level, the first primary switch (the i-th primary switch) turns off, the clamping control signal switches to a high level, and the active clamping transistor conducts.

[0143] It should be noted that the delay time after the first primary switch turns off is the continuous conduction time of the active clamping transistor, that is, the interval time between the dotted line l1 and the dotted line l2. When the active clamping transistor conducts, the active clamping transistor is used to release all the leakage inductance energy absorbed by the clamping capacitor to the output circuit, realizing the recovery of the leakage inductance energy.

[0144] From the voltage waveform diagram of the clamping capacitor, after the active clamping transistor is turned on, the voltage of the clamping capacitor will drop by a large step, which means that the leakage inductance energy absorbed in the clamping capacitor is released and recovered once. Correspondingly, a relatively large boost pulse can be seen on the waveform diagram of the first output current of the first power circuit, which means that the leakage inductance energy is released to the output circuit through the first power circuit (active clamping transistor). Similarly, a large boost pulse can also be seen on the total output current of the output circuit.

[0145] It should be noted that the first output current is Figure 18 the current before flowing through node A, and the total output current is the current after flowing through node A.

[0146] From the waveform diagram of the output voltage, after the active clamping transistor is turned on, the leakage inductance energy is released to the output circuit through the first power circuit (active clamping transistor), and there is a boost pulse on the waveform diagram of the output voltage.

[0147] In addition, as Figure 19 shown, from the waveform diagrams of the first control signal to the fourth control signal, on the left side of the dotted line l1, that is, before time 25.01, the first primary switch to the fourth primary switch only experience one conduction to turn off. That is to say, r is 1, the clamping capacitor absorbs the leakage inductance energy of 4 transformers, the peak voltage of the clamping capacitor is about 590 at most, and the active clamping transistor is turned on to release the leakage inductance energy absorbed by 4 transformers to the output circuit.

[0148] That is, in each switching cycle, the active clamping transistor on the first power circuit recovers the leakage inductance energy once.

[0149] It should be noted that as Figure 20As shown, according to the waveform diagram of the first drive control signal, the second drive control signal, the third drive control signal and the fourth drive control signal, the first primary switch tube is continuously in the on state on the left side of the dotted line (the left side of the horizontal axis 25.03), and is switched to the off state at the dotted line l3, and the second primary switch tube, the third primary switch tube and the fourth primary switch tube on the left side of the dotted line l1 also complete one turn-on and turn-off.

[0150] According to the clamping control signal waveform of the active clamping tube, on the left side of the dotted line l3, the clamping control signal is at a low level, the active clamping tube is turned off, and the clamping capacitor continues to absorb the leakage inductance energy of the 4th transformer, the 3rd transformer, the 2nd transformer and the 1st transformer. From the waveform of the clamping capacitor, after the 4th primary switch tube, the 3rd primary switch tube, the 2nd primary switch tube and the 1st primary switch tube are turned off, the voltage of the clamping capacitor will increase by one step, which means that the clamping capacitor absorbs the leakage inductance energy of the corresponding power circuit.

[0151] It should be noted that Figure 19 The difference is that, Figure 20 As shown, from the waveform diagram of the 1st control signal to the 4th control signal, at the dotted line l3 and the left side, that is, time 25.03 and before, the 1st primary switch tube to the 4th primary switch tube experienced two times of conduction to shutdown, that is, r is 2, and the clamping capacitor absorbs the leakage inductance energy of the four transformers twice, which is equivalent to absorbing 8 parts of the leakage inductance energy of the transformer. The maximum voltage peak of the clamping capacitor is around 630, which is higher than the leakage inductance energy when r is 1.

[0152] Further, at the dotted line l1, the first drive control signal (the i-th drive control signal) is switched to a low level, the first primary switch tube (the i-th primary switch tube) is turned off, the clamp control signal is switched to a high level, and the active clamp tube is turned on.

[0153] It should be noted that the delay time after the first primary side switch tube is turned off is the continuous conduction time of the active clamp tube, that is, the interval time between the dotted line l3 and the dotted line l4. When the active clamp tube is turned on, the active clamp tube is used to release the 8 parts of the transformer leakage inductance energy absorbed by the clamping capacitor to the output circuit, thereby realizing the recovery of the leakage inductance energy.

[0154] From the voltage waveform of the clamping capacitor, after the active clamping tube is turned on, the voltage of the clamping capacitor will drop a large step, which means that the leakage inductance energy absorbed in the clamping capacitor is released and recovered. Correspondingly, we can see that there is a relatively large boost pulse on the waveform of the first output current of the first power circuit, which means that the leakage inductance energy is released to the output circuit through the first power circuit (active clamping tube). It can also be seen that there is a large boost pulse on the total output current of the output circuit.

[0155] From the waveform diagram of the output voltage, after the active clamp transistor is turned on, the leakage inductance energy is released to the output circuit through the first power circuit (active clamp transistor), and there is a boost pulse on the waveform diagram of the output voltage.

[0156] That is, in every two switching cycles, the active clamp transistor on the first power circuit recovers the leakage inductance energy once.

[0157] It can be seen that for the same multi-path topology, the larger the r, the greater the leakage inductance energy recovered at one time. And since there are corresponding losses every time the active switch transistor is turned on, thus, the larger the r, the fewer the number of times the active switch transistor is turned on, and the more leakage inductance energy absorbed by the clamping capacitor, resulting in less loss of the power switch transistor and higher efficiency of recovering the leakage inductance energy.

[0158] It can be understood that the above examples are only examples listed for better understanding the technical solutions of the embodiments of the present application, and do not serve as the sole limitation to the embodiments of the present application.

[0159] It should be noted that in the description of the present application, the orientation or positional relationship indicated by terms such as "upper", "lower", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present application. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0160] It should also be noted that in the description of the present application, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including a..." does not exclude the existence of additional identical elements in the process, method, article or device including the said element.

[0161] In the embodiments of the present application, singular forms such as "a" and "the" include plural forms and should be broadly understood as "a kind of" or "a class of" rather than being limited to the meaning of "one"; in addition, the term "the" should be understood to include both singular and plural forms unless the context clearly indicates otherwise. In addition, the term "according to" should be understood as "at least partially according to...", and the term "based on" should be understood as "at least partially based on...", unless the context clearly indicates otherwise.

[0162] It should be understood that various forms of the processes shown above can be used, steps can be reordered, added or deleted. For example, the steps described in this disclosure can be executed in parallel, sequentially, or in a different order, as long as the desired results of the technical solutions of this disclosure can be achieved, and no limitations are imposed herein.

[0163] The above specific embodiments do not constitute a limitation on the protection scope of this disclosure. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this disclosure shall be included within the protection scope of this disclosure.

Claims

1. A magnetic element, characterized in that: It includes a magnetic core structure and a coil structure, wherein: The magnetic core structure comprises an upper magnetic core base and a lower magnetic core base arranged opposite to each other, and N magnetic core middle columns and at least one side column arranged between the upper magnetic core base and the lower magnetic core base, where N is a natural number greater than 1; The coil structure comprises N coils respectively wound on the middle poles of the magnetic cores, wherein: The winding directions of the coils on the adjacent magnetic core middle columns are opposite; An air gap is provided at at least one of the three positions: between the upper bottom surface of the magnetic core center column and the upper magnetic core base, between the lower bottom surface of the magnetic core center column and the lower magnetic core base, and on the side surface of the magnetic core center column.

2. The magnetic element according to claim 1, characterized in that: The N magnetic core middle columns are located on the same side of the side columns.

3. The magnetic element according to claim 1, characterized in that: The centers of the orthographic projections of the core columns of each magnetic core on the upper magnetic core base or the lower magnetic core base are on a straight line.

4. A topology structure for interleaved parallel flyback converters, characterized in that: include: A voltage source, an absorption circuit, a power unit, and an output circuit, wherein: The power unit includes N parallel power circuits, each power circuit includes a clamping tube, a transformer, a primary switch tube and a secondary switch tube, wherein the clamping tube of the i-th power circuit is an active clamping tube, and the clamping tubes of the remaining (N-1) power circuits are passive clamping tubes, N is a natural number greater than 1, 1≤i≤N; The absorption circuit and the power unit are connected to the voltage source, and the absorption circuit is used to absorb the leakage inductance energy of the N transformers, and release the leakage inductance energy of the N transformers to the output circuit through the active clamping tube; Wherein, each of the transformers comprises a magnetic core center column as described in any one of claims 1 to 3 and a coil wound on the magnetic core center column.

5. The topological structure according to claim 4, characterized in that: The i-th power circuit includes an active clamping tube, an i-th transformer, an i-th primary switch tube and an i-th secondary switch tube, wherein: The i-th transformer comprises an i-th coil, and the i-th coil comprises an i-th primary winding and an i-th secondary winding; The same-name end of the i-th primary winding is connected to the absorption circuit; The non-identical end of the i-th primary winding is connected to the source of the active clamping tube and the drain of the i-th primary switching tube; The non-identical end of the i-th secondary winding is connected to the positive electrode of the i-th secondary switch tube; The same-name end of the i-th secondary winding and the negative electrode of the i-th secondary switch tube are connected to the output circuit; The drain of the active clamping tube is connected to the absorption circuit, and the gate of the active clamping tube is used to input a clamping control signal, wherein the clamping control signal is used to control the conduction and shutdown of the active clamping tube; The source of the i-th primary switch tube is connected to the negative electrode of the voltage source, and the gate of the i-th primary switch tube is used to input the i-th drive control signal, wherein the i-th drive control signal is used to control the conduction and shutdown of the i-th primary switch tube.

6. The topological structure according to claim 4, characterized in that: The circuit structures and circuit connection relationships of the remaining (N-1) power circuits are the same, wherein the mth power circuit includes the mth passive clamping tube, the mth transformer, the mth primary switch tube, and the mth secondary switch tube, wherein: The mth transformer comprises an mth coil, and the mth coil comprises an mth primary winding and an mth secondary winding; The same-name end of the mth primary winding is connected to the positive electrode of the voltage source; The non-identical end of the mth primary winding is connected to the positive electrode of the mth passive clamping tube and the drain of the mth primary switching tube; The non-identical end of the mth secondary winding is connected to the positive electrode of the mth secondary switch tube; The same-name end of the mth secondary winding and the negative electrode of the mth secondary switch tube are connected to the output circuit; The negative electrode of the mth passive clamping tube is connected to the absorption circuit; The source of the mth primary switch tube is connected to the negative electrode of the voltage source, and the gate of the mth primary switch tube is used to input the mth drive control signal, wherein the mth drive control signal is used to control the conduction and shutdown of the mth primary switch tube, wherein 1≤m≤N and m≠i.

7. The topological structure according to claim 4, characterized in that: The phase difference between the driving control signals of two adjacent primary switch tubes is 360° / N.

8. The topological structure according to claim 5, characterized in that: The absorption circuit includes a clamping capacitor, wherein: The absorption circuit is used to absorb the leakage inductance energy of the N transformers through the clamping capacitor, and release the leakage inductance energy of the N transformers to the output circuit through the active clamping tube.

9. The topological structure according to claim 8, characterized in that: The first end of the clamping capacitor is connected to the same-name end of the primary windings of the N transformers and the positive electrode of the voltage source, and the second end of the clamping capacitor is connected to the drain of the active clamping tube and the negative electrodes of all passive clamping tubes.

10. The topological structure according to claim 4, characterized in that: The output circuit includes an output capacitor, wherein: The first end of the output capacitor is connected to the negative electrodes of all the secondary side switch tubes; The second end of the output capacitor is connected to the same-named end of the secondary windings of all transformers.

11. The topological structure according to any one of claims 4 to 10, characterized in that: The transistor type of the active clamp tube is a silicon MOSFET, a silicon carbide MOSFET or a gallium nitride device; The transistor type of the passive clamping tube is a silicon diode or a silicon carbide diode; The transistor type of the primary switch tube is a silicon MOSFET, a silicon carbide MOSFET or a gallium nitride device; The transistor type of the secondary side switch tube is a diode or a MOSFET.

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