Magnetic element, topological structure, and leakage inductance energy recovery method

Abstract

A magnetic element, a topological structure, and a leakage inductance energy recovery method, relating to the technical field of power electronics. The magnetic element comprises a magnetic core structure and a coil structure. The magnetic core structure comprises an upper magnetic core base and a lower magnetic core base which are arranged opposite to each other, and N magnetic core middle posts and at least one side post which are provided between the upper magnetic core base and the lower magnetic core base, N being a natural number greater than 1. The coil structure comprises N coils respectively wound on the magnetic core middle posts, wherein the winding directions of the coils on adjacent magnetic core middle posts are opposite, and an air gap is formed at at least one of three positions, i.e., a position between the upper bottom surface of each magnetic core middle post and the upper magnetic core base, a position between the lower bottom surface of each magnetic core middle post and the lower magnetic core base, and a position on the side surface of each magnetic core middle post. In the magnetic element of the present application, magnetic core posts are integrated on a same magnetic core base, and the winding directions of coils on adjacent magnetic core middle posts are set to be opposite, so that the purposes of reducing the weight of a magnetic core and reducing the loss of the magnetic core can be achieved.

Description

Magnetic element, topology and leakage energy recovery method

[0001] Related applications

[0002] The present application claims priority to the Chinese patent application No. 202411047838.6 filed on July 31, 2024, and incorporates by reference the entire disclosure of the above patent application as part of the present application. TECHNICAL FIELD

[0003] The present application belongs to the technical field of power electronics, and specifically relates to a magnetic element, a topology and a leakage energy recovery method. BACKGROUND

[0004] The flyback converter has great commercial appeal due to its simple structure and low cost. In the application scenarios of high-power switching power supplies, by means of interleaving flyback converters in parallel, the input and output currents become more and more continuous while the power is expanded, thereby alleviating the electromagnetic interference problem caused by the discontinuous input and output currents of the flyback converter.

[0005] In the traditional multi-phase parallel flyback converter, each flyback conversion module has an independent flyback transformer, which has the disadvantages of large volume and weight of the magnetic element, resulting in high core loss. SUMMARY

[0006] In order to solve the above problems, the present application provides a magnetic element, a topology and a leakage energy recovery method, which can reduce the weight of the magnetic core and thereby reduce the core loss.

[0007] An embodiment of the present application provides a magnetic element, which comprises a magnetic core structure and a coil structure, wherein:

[0008] The magnetic core structure comprises an upper magnetic core base and a lower magnetic core base arranged oppositely, and N magnetic core columns and at least one edge column arranged between the upper magnetic core base and the lower magnetic core base, N being a natural number greater than 1;

[0009] The coil structure comprises N coils wound on each of the magnetic core columns, wherein:

[0010] The winding directions of the coils on adjacent magnetic core columns are opposite;

[0011] At least one of the upper bottom surface of the magnetic core column and the upper magnetic core base, the lower bottom surface of the magnetic core column and the lower magnetic core base, and the side surface of the magnetic core column is provided with an air gap.

[0012] A further embodiment of the present application provides a topology for an interleaved parallel flyback converter, comprising: a voltage source, an absorption circuit, a power unit and an output circuit, wherein:

[0013] The power unit comprises N parallel power circuits, each power circuit comprising a clamping tube, a transformer, a primary side switch tube and a secondary side 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, and 1≤i≤N;

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

[0015] Each transformer comprises a magnetic core column and a coil wound on the magnetic core column of the foregoing embodiment.

[0016] A further embodiment of the present application provides a leakage energy recovery method using the topology of the foregoing embodiment, the method comprising:

[0017] The phase difference of the driving control signals of the adjacent two primary side switch tubes is 360° / N.

[0018] The absorption circuit absorbs the leakage energy of the N transformers and releases the leakage energy of the N transformers to the output circuit through the conduction of the active clamping tube.

[0019] The beneficial effects of the present application are: by integrating the magnetic core columns on the same magnetic core base and setting the winding directions of the adjacent structures in opposite directions, the weight and loss of the magnetic core are reduced; in addition, by sharing one clamping capacitor through multiple parallel power circuits, the number of power switch tubes of the present application is greatly reduced compared to the conventional multi-path interleaved parallel active clamping flyback converter topology, effectively reducing the cost loss caused by the large number of switch tubes in the prior art; at the same time, the active clamping tube (active clamping) can recover all the leakage energy of the transformer, reducing the energy loss caused by the leakage inductance of the transformer, thereby further improving the energy conversion efficiency of the flyback converter while reducing the cost.

[0020] Other features and advantages of the present application will become apparent from the following detailed description of exemplary embodiments thereof, with reference to the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0021] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the present application and, together with the description, serve to explain the principles of the present application.

[0022] Fig. 1 is a schematic diagram of a structure of a magnetic element according to an embodiment of the present application.

[0023] Fig. 2 is a schematic diagram of a structure of a magnetic element according to an embodiment of the present application.

[0024] Fig. 3 is a schematic diagram of a structure of a magnetic element according to an embodiment of the present application.

[0025] Fig. 4 is a schematic diagram of a structure of a magnetic element according to an embodiment of the present application.

[0026] Fig. 5 is a schematic diagram of a structure of a magnetic element according to an embodiment of the present application.

[0027] Fig. 6 is a schematic diagram of a structure of a magnetic element according to an embodiment of the present application.

[0028] Fig. 7 is a schematic diagram of a structure of a magnetic element according to an embodiment of the present application.

[0029] Fig. 8 is a structural diagram of a topology of an N-way interleaved parallel flyback converter according to an embodiment of the present application.

[0030] Fig. 9 is a schematic diagram of a structure of N transformers integrated as a magnetic element in a topology of an N-way interleaved parallel flyback converter according to an embodiment of the present application.

[0031] Fig. 10 is a structural diagram of a topology of a 2-way interleaved parallel flyback converter according to an embodiment of the present application.

[0032] Fig. 11 is a schematic diagram of a structure of 2 transformers integrated as a magnetic element in a topology of a 2-way interleaved parallel flyback converter according to an embodiment of the present application.

[0033] Fig. 12 is a structural diagram of a topology of a conventional 2-way interleaved parallel flyback converter.

[0034] Fig. 13 is a structural diagram of a topology of a 3-way interleaved parallel flyback converter according to an embodiment of the present application.

[0035] Fig. 14 is a schematic diagram of a structure of 3 transformers integrated as a magnetic element in a topology of a 3-way interleaved parallel flyback converter according to an embodiment of the present application.

[0036] Fig. 15 is a structural diagram of a topology of a conventional 3-way interleaved parallel flyback converter.

[0037] Fig. 16 is a structural diagram of a topology of a conventional N-way interleaved parallel flyback converter.

[0038] Fig. 17 is an exemplary flowchart of a leakage energy recycling method according to an embodiment of the present application.

[0039] Fig. 18 is a structure diagram of a topology of a 4-way interleaved parallel flyback converter according to an embodiment of the present application.

[0040] Fig. 19 is one of exemplary waveform diagrams of leakage energy absorption and release of the topology shown in Fig. 18.

[0041] Fig. 20 is another of exemplary waveform diagrams of leakage energy absorption and release of the topology shown in Fig. 18. DETAILED DESCRIPTION

[0042] Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that the relative arrangement of the components and steps set forth in the embodiments, as well as the numerical expressions and values, are not limitations on the scope of the present application, unless otherwise specifically stated.

[0043] The following description of at least one exemplary embodiment is merely exemplary in nature and is in no way intended to limit the scope of the application, its application, or uses.

[0044] Techniques, methods, and devices known to those of ordinary skill in the relevant art can not be discussed in detail herein. However, where appropriate, such techniques, methods, and devices can be viewed as part of the specification.

[0045] In all of the examples shown and discussed herein, any specific values should be interpreted as merely exemplary, and not as a limitation. Thus, other examples of the exemplary embodiments can have different values.

[0046] As shown in Fig. 1, one embodiment of the present application provides a magnetic element, comprising a magnetic core structure and a coil structure, wherein:

[0047] Fig. 2 shows a schematic diagram of the magnetic core structure, as shown in Fig. 2, the magnetic core structure comprises oppositely arranged upper magnetic core base 101 and lower magnetic core base 103, and N magnetic core columns 102 and at least one side column 104 arranged between the upper magnetic core base and the lower magnetic core base, wherein N is a natural number greater than 1.

[0048] As shown in Fig. 1, the coil structure comprises N coils 201 wound on each magnetic core column respectively, and the winding direction of the coils on adjacent magnetic core columns is opposite.

[0049] In the embodiment, the winding directions of the coils of the adjacent magnetic core columns are opposite, for example, the winding direction of the coil of the mth magnetic core column is clockwise winding from left to right, and the winding direction of the coil of the m+1th magnetic core column is counterclockwise winding, so that the magnetic fluxes flowing through the adjacent magnetic core columns are opposite. Specifically, referring to FIG. 3, which is a top view of FIG. 1, the winding directions of the coils wound on the magnetic core columns are shown, for example, the coil of the 1st magnetic core column O1 is clockwise winding, the coil of the 2nd magnetic core column O2 is counterclockwise winding, the coil of the 3rd magnetic core column O3 is clockwise winding, and so on, so that the winding directions of the coils of all the magnetic core columns can be determined, which will not be described herein again.

[0050] In the embodiment, as shown in FIG. 2, the N magnetic core columns are arranged in a row, and specifically, referring to FIG. 3, the centers of the orthographic projections of the magnetic core columns on the upper magnetic core base or the lower magnetic core base are on a straight line, and specifically, O1, O2, O3, …, ON are on a straight line. In addition, in the embodiment, as shown in FIG. 2, all the magnetic core columns are located on the same side of the edge column.

[0051] It should be further noted that in the embodiment, an air gap is formed on each magnetic core column, and specifically, the air gap can be formed at the position between the upper bottom surface of the magnetic core column and the upper magnetic core base (i.e., the position of reference numeral 1 in FIG. 1), the position between the lower bottom surface of the magnetic core column and the lower magnetic core base (i.e., the position of reference numeral 2 in FIG. 1), and the side surface of the magnetic core column (e.g., the position of reference numeral 3 in FIG. 1), and specifically:

[0052] As shown in FIG. 4, the air gap is formed between the upper bottom surface of the magnetic core column 102 and the upper magnetic core base 101; the air gap is formed on the side surface of the magnetic core column 102, for example, the air gap is formed at the middle position of the magnetic core column 102 as shown in FIGS. 5 and 6; and as shown in FIG. 7, the air gap is formed between the lower bottom surface of the magnetic core column 102 and the lower magnetic core base 103.

[0053] It should be further noted that the air gap on each magnetic core column can be a single air gap as shown in FIGS. 4-7, or a plurality of segmented air gaps, that is, in the embodiment, the air gap is formed at at least one of the positions between the upper bottom surface of each magnetic core column and the upper magnetic core base, the positions between the lower bottom surface of each magnetic core column and the lower magnetic core base, and the side surface of each magnetic core column.

[0054] For example, for the 1st magnetic core column, two air gaps can be formed at the position of reference numeral 1 and the position of reference numeral 2 of the 1st magnetic core column; a plurality of air gaps can be formed at the position of reference numeral 3 of the 1st magnetic core column, and so on, which will not be limited herein.

[0055] The magnetic element provided by the embodiment can realize opposite directions of magnetic flux flowing through adjacent magnetic core columns, reduce the weight of the magnetic core and reduce the loss of the magnetic core by integrating the N magnetic core columns on the same magnetic core base and setting opposite winding directions of the coils on the adjacent magnetic core columns.

[0056] Further, due to the existence of leakage inductance, the energy conversion efficiency of the flyback converter is limited, and the industry has invented active clamping technology to realize the recycling of leakage energy of the flyback converter to improve the energy conversion efficiency; however, the applicant finds that although the more the number of the interleaved parallel flyback converters is, the more continuous the input current and the output current become, which is more suitable for high-power application scenarios, but if all the power circuits in the multi-path interleaved parallel flyback converter adopt the active clamping technology, the number of power switches will double and the cost will greatly increase.

[0057] Based on this, one embodiment of the present application also provides a topology structure for an interleaved parallel flyback converter, as shown in FIG. 8, which comprises a voltage source Uin, an absorption circuit 1, a power unit 2 and an output circuit 3, wherein:

[0058] The power unit 2 comprises N parallel power circuits, each of which comprises a clamping tube, a transformer, a primary side switch tube and a secondary side switch tube, wherein the clamping tube of the i-th power circuit 2i is an 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;

[0059] The absorption circuit 1, the power unit 2 and the voltage source Uin are connected, and the absorption circuit 1 is used to absorb the leakage energy of the N transformers (all transformers) and release the leakage energy of all the transformers to the output circuit 3 through the active clamping tube Va; each transformer comprises the magnetic core column of the foregoing embodiment and the coil wound on the magnetic core column.

[0060] 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 comprises a transformer, the N transformers of the present embodiment are designed in an integrated manner, each transformer comprises the magnetic core column of the foregoing embodiment and the coil wound on the magnetic core column, and the coil satisfies the winding mode of the foregoing embodiment.

[0061] In the circuit diagram and the magnetic core structure of the N-way power module in interleaved parallel connection, two windings of the mth transformer are wound on the mth magnetic core column, wherein the winding directions of the coils of the mth transformer and the m+1th transformer are opposite, wherein m>0 and m<=N, it should be understood that the coils on each magnetic core column include a primary winding and a secondary winding, the winding methods of the primary winding and the secondary winding are the same, and the specific explanation is as follows: if the primary winding of the mth transformer is wound on the mth magnetic core column from the m-A end in the clockwise direction, the primary coil of the m+1th transformer adjacent to the mth transformer should be wound on the m+1th magnetic core column from the m+1-B end in the counterclockwise direction.

[0062] The winding method is described by taking FIG. 8 as an example. The N-way power module includes N transformers, i.e., a transformer T1, a transformer T2, a transformer T3, and a transformer TN, wherein two windings of the transformer T1 are wound on the first magnetic core column, two windings of the transformer T2 are wound on the second magnetic core column, and two windings of the transformer T3 are wound on the third magnetic core column, wherein the winding directions of the primary coils (primary windings) of the transformer T1 and the transformer T2 are opposite, the winding directions of the primary coils of the transformer 1 and the transformer 3 are the same, i.e., the winding directions of the transformer T2 and the transformer T3 are opposite.

[0063] The specific explanation is as follows: as shown in FIG. 9, if the primary coil of the transformer T1 is wound on the first magnetic core column from the 1-A end in the clockwise direction, the primary coil of the transformer T2 should be wound on the second magnetic core column from the 2-B end in the counterclockwise direction, and the primary coil of the transformer T3 should be wound on the third magnetic core column from the 3-A end in the clockwise direction, and 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, which will not be described herein again.

[0064] In addition, the applicant finds that, for a transformer, the leakage magnetic flux between windings or between a winding and a core causes a part of the magnetic field not to be completely captured by all windings, and an induced electromotive force is generated. This part of energy (i.e., leakage energy) is dissipated in the transformer, affecting the efficiency and performance of the transformer.

[0065] Therefore, based on the topology structure of the interleaved parallel flyback converter in the embodiment, the absorption circuit 1 can absorb the leakage energy of all transformers, and release the leakage 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 the embodiment, the N parallel power circuits share one absorption circuit, thereby reducing the number of power switch tubes and reducing the cost.

[0066] Further, as shown in FIG. 8, the i-th power circuit 2i includes an active clamp tube Va, an i-th transformer Ti, an i-th primary side switch tube Qi, and an i-th secondary side switch tube Di, wherein:

[0067] The i-th transformer includes an i-th coil, and the i-th coil includes an i-th primary side winding and an i-th secondary side winding;

[0068] The same name end of the i-th primary side winding is connected with the snubber circuit 1;

[0069] The non-same name end of the i-th primary side winding is connected with the source of the active clamp tube Va and the drain of the i-th primary side switch tube Qi;

[0070] The non-same name end of the i-th secondary side winding is connected with the anode of the i-th secondary side switch tube Di;

[0071] The same name end of the i-th secondary side winding and the cathode of the i-th secondary side switch tube Di are connected with the output circuit 3;

[0072] The drain of the active clamp tube Va is connected with the snubber circuit 1, and the gate of the active clamp tube Va is used for inputting a clamping control signal, wherein the clamping control signal is used for controlling the conduction and the closing of the active clamp tube Va;

[0073] The source of the i-th primary side switch tube Qi is connected with the negative electrode of the voltage source Uin, and the gate of the i-th primary side switch tube Qi is used for inputting an i-th driving control signal, wherein the i-th driving control signal is used for controlling the conduction and the closing of the i-th primary side switch tube Qi.

[0074] Further, as shown in FIG. 8, the circuit structure and the circuit connection relationship of the remaining (N-1) power circuits are the same, and the circuit structure and the circuit connection relationship of the m-th power circuit among them are taken as an example for description:

[0075] The m-th power circuit 2m includes an m-th passive clamp tube Vpm, an m-th transformer Tm, an m-th primary side switch tube Qm, and an m-th secondary side switch tube, wherein:

[0076] The m-th transformer includes an m-th coil, and the m-th coil includes an m-th primary side winding and an m-th secondary side winding;

[0077] The same name end of the m-th primary side winding is connected with the positive electrode of the voltage source Uin;

[0078] The non-same name end of the m-th primary side winding is connected with the anode of the m-th passive clamp tube Vpm and the drain of the m-th primary side switch tube Qm;

[0079] The non-same name end of the m-th secondary side winding is connected with the anode of the m-th secondary side switch tube Dm;

[0080] The same name end of the m-th secondary side winding and the cathode of the m-th secondary side switch tube Dm are connected with the output circuit 3;

[0081] The negative electrode of the mth passive clamp tube Vpm is connected with the absorption circuit 1.

[0082] The source electrode of the mth primary-side switch tube Qm is connected with the negative electrode of the voltage source Uin, and the gate electrode of the mth primary-side switch tube Qm is used for inputting the mth driving control signal, wherein the mth driving control signal is used for controlling the conduction and the closing of the mth primary-side switch tube, wherein m further satisfies 1≤m≤N and m≠i.

[0083] It should be noted that, in order to realize the interleaving parallel connection between the power circuits, so that the input and output currents are continuous, in the embodiment, the phase difference between the driving control signals of the adjacent two primary-side switch tubes is 360° / N. That is to say, the phase difference between the adjacent two driving control signals among the 1st driving control signal, the 2nd driving control signal, the 3rd driving control signal, …, and the Nth driving control signal is 360° / N.

[0084] In an optional mode of the embodiment, as shown in FIG. 8, the absorption circuit 1 includes a clamp capacitor C1, wherein:

[0085] The absorption circuit is used for absorbing the leakage energy of the N transformers through the clamp capacitor C1, and releasing the leakage energy of the N transformers to the output circuit 3 through the active clamp tube.

[0086] The first end of the clamp capacitor C1 is connected with the primary winding common end of the N transformers (i.e. all the transformers) and the positive electrode of the voltage source Uin, and the second end of the clamp capacitor is connected with the drain electrode of the active clamp tube and the negative electrodes of all the passive clamp tubes.

[0087] In another optional mode of the embodiment, as shown in FIG. 10, the absorption circuit 1 further includes a clamp resistor R1, wherein the first end of the clamp resistor R1 is connected with the positive electrode of the voltage source Uin and the first end of the clamp capacitor C1; and the second end of the clamp resistor R1 is connected with the second end of the clamp capacitor C1, the drain electrode of the active clamp tube and the negative electrodes of all the passive clamp tubes.

[0088] Referring to FIG. 8, the N parallel-connected power circuits share one clamp capacitor C1, which can absorb the leakage energy of the corresponding transformer when the power circuit is turned on, and release the absorbed leakage energy of the transformer to the output circuit through the active clamp tube when the active clamp tube is turned on.

[0089] It should be noted that the active clamp tube is turned on after the i-th primary side switch tube is turned off, and the remaining (N-1) primary side switch tubes are turned on staggered before the i-th primary side switch tube is turned off, that is, before the i-th primary side switch tube is turned off, the clamp capacitor can absorb all the leakage energy of the transformer, and when the active clamp tube is turned on, the absorbed leakage energy of the transformer is released to the output circuit through the active clamp tube, thereby improving the energy conversion efficiency of the interleaved parallel flyback converter.

[0090] Further, as shown in FIG. 8, the output circuit 3 includes an output capacitor C0, wherein:

[0091] The first end of the output capacitor C0 is connected to the negative poles of all the secondary side switch tubes, and the second end of the output capacitor C0 is connected to the same name end of the secondary side windings of all the transformers. It should be understood that, as shown in FIG. 8, the output circuit 3 is further connected to a load, which will not be described in detail herein.

[0092] So far, the topology structure for the interleaved parallel flyback converter proposed in the embodiments of the present application has N transformers designed integrally, each transformer including the aforementioned magnetic core column and the coil wound on the magnetic core column, and the coil satisfies the winding mode of the aforementioned embodiments, thereby achieving the purposes of reducing the weight of the magnetic core and reducing the loss of the magnetic core. In addition, the plurality of parallel power circuits share one clamp capacitor, which can absorb all the leakage energy of the transformer, so that the number of power switch tubes of the present application is greatly reduced compared with the topology architecture of the conventional multi-path interleaved parallel active clamp flyback converter, effectively reducing the cost problem caused by the large number of switch tubes in the prior art. At the same time, all the leakage energy of the transformer can be recovered through the conduction of the active clamp tube (active clamp), that is, all the absorbed leakage energy of the transformer is released to the output circuit through the active clamp tube, reducing the energy loss caused by the leakage inductance of the transformer, thereby further improving the energy conversion efficiency of the flyback converter while reducing the cost.

[0093] Next, as shown in FIG. 10, taking N=2 and i=1 as an example, the topology structure for the interleaved parallel flyback converter of the present application is described:

[0094] Specifically, FIG. 10 is a topology structure for interleaved parallel of 2-way flyback converter power circuits, wherein: the first power circuit adopts active clamp technology, and the clamp tube is an active switch tube Va; the second power circuit adopts the traditional passive clamp technology, and the clamp tube is a passive clamp tube Vp2, which is a diode device such as a silicon diode or a silicon carbide diode, which is not limited in the present application.

[0095] The first power circuit and the second power circuit share a clamping capacitor C1. In the topology, the power switch tubes are active clamping tubes Va, the first primary side switch tube Q1 and the second primary side switch tube Q2, that is, the number of power switch tubes is 3.

[0096] In addition, in the topology of the power circuit of the 2-way flyback converter shown in FIG. 10, 2 transformers are included. The 2 transformers of the embodiment are designed to be integrated. Each transformer includes the aforementioned magnetic core column and the coil wound on the magnetic core column. The coil satisfies the winding mode of the aforementioned embodiment.

[0097] Specifically, as shown in FIG. 11, the two windings of the transformer T1 are wound on the magnetic core column 1, and the two windings of the transformer T2 are wound on the magnetic core column 2. The winding directions of the coils of the two transformers are opposite. Specifically, if the primary side coil of the transformer 1 is wound on the magnetic core column 1 from the 1-A end in the clockwise direction, the primary side coil of the corresponding transformer 2 is wound on the magnetic core column 2 from the 2-B end in the counterclockwise direction.

[0098] FIG. 12 shows a schematic diagram of the power circuit of the traditional 2-way active clamping flyback converter in interleaved parallel connection. As can be seen, the number of power switch tubes of the traditional interleaved parallel active clamping flyback converter is 4, which are marked as Y1, Y2, Q1 and Q2. In the topology of the 2-way interleaved parallel connection of the present application, the number of power switch tubes is 3. Compared with the prior art, the number of power switch tubes of the present application is reduced by 25%. In the topology of the traditional 2-way active clamping flyback converter, the T1 transformer and the T2 transformer are arranged separately. Compared with the prior art, the T1 transformer and the T2 transformer of the present application are arranged integrally, so as to reduce the weight of the magnetic core and the loss of the magnetic core.

[0099] Next, as shown in FIG. 13, the topology of the present application for the interleaved parallel flyback converter is described by taking N=3 and i=1 as an example:

[0100] Specifically, FIG. 13 shows the topology of the power circuit of the 3-way flyback converter in interleaved parallel connection. The first power circuit adopts active clamping technology, and the clamping tube is an active switch tube. The second power circuit and the third power circuit adopt the traditional passive clamping technology, and the clamping tubes are the second passive clamping tube Vp2 and the third passive clamping tube Vp3, respectively. In FIG. 4, the second passive clamping tube Vp2 and the third passive clamping tube Vp3 are diode devices, such as silicon diodes or silicon carbide diodes. The present application does not limit this.

[0101] The first power circuit, the second power circuit and the third power circuit share a clamping capacitor C1, and in the topology, the power switch tubes are active clamping tubes Va, the first primary side switch tube Q1, the second primary side switch tube Q2 and the third primary side switch tube Q3, that is, the number of power switch tubes is 4.

[0102] In addition, in the topology of the power circuit of the 3-way flyback converter shown in FIG. 13, 3 transformers are included, and the 3 transformers of the embodiment are designed in an integrated manner, each transformer including the aforementioned magnetic core column and the coil wound on the magnetic core column, wherein the coil satisfies the winding mode of the aforementioned embodiment.

[0103] Specifically, as shown in FIG. 14, two windings of the transformer T1 are wound on the magnetic core column 1, and two windings of the transformer T3 are wound on the magnetic core column 3, wherein the winding directions of the primary coils of the transformer T1 and the transformer T2 are opposite, and the winding directions of the primary coils of the transformer T1 and the transformer T3 are the same, which will be explained in detail as follows: if the primary coil of the transformer T1 is wound on the magnetic core column 1 from the 1-A end in a clockwise direction, then the corresponding primary coil of the transformer T2 is wound on the magnetic core column 2 from the 2-B end in a counterclockwise direction, and the corresponding primary coil of the transformer T3 is wound on the magnetic core column 3 from the 3-A end in a clockwise direction.

[0104] FIG. 15 shows a schematic diagram of the power circuit of the conventional 3-way active clamping flyback converter in interleaved parallel connection, and it can be seen that the number of power switch tubes of the conventional active clamping flyback converter in interleaved parallel connection is 6, which are marked as Y1, Y2, Y3, Q1, Q2 and Q3. Compared with the prior art, the number of power switch tubes in the topology of the 3-way interleaved parallel connection of the present application is reduced by 33% based on the number of power switch tubes in the topology of the present application, which is 4. In the topology of the conventional 3-way active clamping flyback converter, the transformer T1, the transformer T2 and the transformer T3 are arranged separately, and compared with the prior art, the transformer T1, the transformer T2 and the transformer T3 of the present application are arranged in an integrated manner, thereby achieving the purpose of reducing the weight of the magnetic core and reducing the loss of the magnetic core.

[0105] Next, taking the foregoing Figure 8 as an example, when the power circuits of the N-way flyback converter are interleaved in parallel, among them: the first power circuit adopts active clamping technology, and the clamping tube is a main active switch tube Va; the remaining (N-1) power circuits (i.e. the second power circuit, the third power circuit, …, the Nth power circuit) adopt passive clamping technology, and the clamping tubes are the second passive clamping tube Vp2, the third passive clamping tube Vp3, …, the Nth passive clamping tube VpN respectively, and the second passive clamping tube Vp2, the third passive clamping tube Vp3, …, the Nth passive clamping tube VpN of Figure 8 are diode devices, such as silicon diodes or silicon carbide diodes, which are not limited by the present application.

[0106] The first power circuit, the second power circuit, the third power circuit, …, the Nth power circuit share a clamping capacitor C1, and in this topology, the power switch tubes are the active clamping tube Va, the first primary side switch tube Q1, the second primary side switch tube Q2, the third primary side switch tube Q3, …, the Nth primary side switch tube QN, that is, the number of power switch tubes is (N+1).

[0107] Figure 16 shows a schematic diagram of the traditional N-way active clamping flyback power module interleaved in parallel, it can be seen that the number of power switch tubes of the traditional interleaved parallel active clamping flyback converter is 2N, and the labels are Y1, Y2, Y3, …, YN, Q1, Q2, Q3, …, QN. In the topology of the N-way interleaved parallel topology of the present application, the number of power switch tubes is (N+1), compared with the prior art, the number of power tubes of the present application is reduced by (N-1) / 2N; and in the topology of the traditional N-way active clamping flyback converter, the T1 transformer, the T2 transformer, …, the TN transformer are arranged separately, compared with the prior art, the T1 transformer, the T2 transformer, …, the TN transformer of the present application are integrated, so as to reduce the weight of the magnetic core and the loss of the magnetic core.

[0108] It should be seen that, in the extreme case, compared with the prior art, the number of power switch tubes of the present application can be reduced by nearly 50%, and the cost of the power switch tube is close to the traditional passive clamping topology, however, the traditional passive clamping topology cannot recover the leakage energy, therefore, it is further verified that the topology for interleaved parallel flyback converter proposed in the present application not only can reduce the cost loss of the power switch tube, but also can recover all the leakage energy of the transformer, reduce the energy loss caused by the leakage inductance of the transformer, and improve the energy conversion efficiency of the flyback converter.

[0109] 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 switch tube is a silicon MOSFET, a silicon carbide MOSFET or a gallium nitride device; and the transistor type of the secondary side switch 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 an improper limitation on the present application.

[0110] To further reduce the energy loss of the power switch tube, on the basis of the topology structure proposed in the foregoing embodiments, as shown in FIG. 17, the present application further provides a drain energy recovery method, which comprises the following steps:

[0111] Step 10, configuring the phase difference of the driving control signals of the adjacent two primary side switch tubes to be 360° / N.

[0112] Step 20, absorbing the drain energy of the N transformers by the absorption circuit, and releasing the drain energy of the N transformers to the output circuit through the conduction of the active clamping tube.

[0113] It should be noted that since the principle of the problem solved by the drain energy recovery method relies on the foregoing topology structure, the foregoing embodiments and the beneficial effects brought by them also apply to the present embodiment, and therefore the same parts will not be described again.

[0114] In the present embodiment, let the whole primary side switch tube from conduction to closing be one power switch period, and the clamping control signal is used to control the active clamping tube to conduct once every r power switch periods to perform the absorption and release of the drain energy, wherein r is a natural number greater than 0.

[0115] That is, as shown in FIG. 8, the N flyback converters share one drain energy absorption capacitor, i.e., the clamping capacitor C1, and one drain energy recovery clamping power switch tube, i.e., the active clamping tube Va. The active clamping tube can conduct once every r power switch periods under the control of the clamping control signal to perform the recovery of the drain energy once.

[0116] On the basis of the whole primary side switch tube from conduction to closing being one power switch period, in r power switch periods, the clamping capacitor continuously absorbs the energy of (r x N) leakage inductors, and through the opening of the active clamping tube once, the clamping capacitor continuously absorbs the energy of (r x N) leakage inductors is released to the output circuit at one time.

[0117] In the embodiment, for the application scenario of N flyback converters in parallel, the absorption of leakage energy can be achieved (r x N) times through the shared clamping capacitor, and the energy of (r x N) leakage inductors is recovered to the output circuit through the conduction of the active clamping power switch once. Since the active clamping power switch is turned on each time, the corresponding loss will occur. Therefore, the greater the r is, the fewer the times of turning on the active clamping power switch, and the less the loss caused, and the higher the efficiency of energy recovery.

[0118] Next, the topology of the power circuit of the 4-way flyback converter shown in FIG. 18 is taken as an example to illustrate the interleaved parallel topology, wherein 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 side switch Q1 inputs the first driving control signal, the gate of the second primary side switch Q2 inputs the second driving control signal, the gate of the third primary side switch Q3 inputs the third driving control signal, and the gate of the fourth primary side switch Q4 inputs the fourth driving control signal.

[0119] As shown in FIGS. 19 and 20, the phase difference between two adjacent driving control signals in the first driving control signal, the second driving control signal, the third driving control signal and the fourth driving control signal is 90°, so that the interleaved conduction of the first power circuit, the second power circuit, the third power circuit and the fourth power circuit can be realized.

[0120] It should be noted that, as shown in FIG. 19, according to the waveform diagram of the first driving control signal, the second driving control signal, the third driving control signal and the fourth driving control signal, it can be known that the first primary side switch is in the conduction state continuously on the left side of the dashed line l1 (the left side of the horizontal coordinate 25.01), is switched to the off state at the dashed line l1, and the second primary side switch, the third primary side switch and the fourth primary side switch also complete one conduction and off on the left side of the dashed line l1.

[0121] According to the clamping control signal waveform diagram of the active clamping tube, it can be known that on the left side of the dashed line l1, the clamping control signal is at the low level, the active clamping tube is off, and the clamping capacitor continuously absorbs the leakage energy of the fourth transformer, the third transformer, the second transformer and the first transformer. As can be seen from the waveform diagram of the clamping capacitor, after the fourth primary side switch, the third primary side switch, the second primary side switch and the first primary side switch are turned off, the voltage of the clamping capacitor will rise by a step, which means that the clamping capacitor absorbs the leakage energy of the corresponding power circuit.

[0122] At the dashed line l1, the first driving control signal (the i driving control signal) is switched to the low level, the first primary side switch (the i primary side switch) is turned off, the clamping control signal is switched to the high level, and the active clamping tube is turned on.

[0123] It should be noted that the delay time interval after the first primary switch tube is closed is the duration of the active clamp tube, that is, the interval time between the dashed line l1 and the dashed line l2. When the active clamp tube is turned on, the active clamp tube is used to release the total leakage energy of the transformer absorbed by the clamping capacitor to the output circuit, so as to realize the recovery of the leakage energy.

[0124] From the voltage waveform graph of the clamping capacitor, it can be seen that after the active clamp tube is turned on, the voltage of the clamping capacitor will drop a large step, that is, the leakage energy absorbed in the clamping capacitor is released and recovered once. Correspondingly, it can be seen from the waveform graph of the first output current of the first power circuit that there is a relatively large boost pulse, which means that the leakage energy is released to the output circuit through the first power circuit (active clamp tube). Similarly, there is also a large boost pulse on the total output current of the output circuit.

[0125] It should be noted that the first output current is the current flowing through node A in FIG. 18, and the total output current is the current flowing through node A.

[0126] From the waveform graph of the output voltage, it can be seen that after the active clamp tube is turned on, the leakage energy is released to the output circuit through the first power circuit (active clamp tube), and there is a boost pulse on the waveform graph of the output voltage.

[0127] In addition, as shown in FIG. 19, from the waveform graph of the first control signal to the fourth control signal, it can be seen that on the left side of the dashed line l1, that is, before time 25.01, the first primary switch tube to the fourth primary switch tube only experience one conduction to closing, that is, r is 1, the clamping capacitor absorbs the leakage energy of four transformers, and the peak value of the voltage of the clamping capacitor is about 590, the active clamp tube is turned on, and the leakage energy of four transformers is released to the output circuit.

[0128] That is, in each switching cycle, the active clamp tube on the first power circuit recovers the leakage energy once.

[0129] It should be noted that, as shown in FIG. 20, according to the waveform graphs of the first driving control signal, the second driving control signal, the third driving control signal and the fourth driving control signal, it can be seen that the first primary switch tube is in a conduction state on the left side of the dashed line (left side of the horizontal coordinate 25.03), and is switched to a closing state at the dashed line l3, and the second primary switch tube, the third primary switch tube and the fourth primary switch tube also complete one conduction and closing on the left side of the dashed line l1.

[0130] According to the clamping control signal waveform diagram of the active clamping tube, on the left side of the dashed line l3, the clamping control signal is at a low level, the active clamping tube is closed, and the clamping capacitor continuously absorbs the leakage energy of the 4th transformer, the 3rd transformer, the 2nd transformer and the 1st transformer. As can be seen from the waveform diagram of the clamping capacitor, after the 4th primary side switch tube, the 3rd primary side switch tube, the 2nd primary side switch tube and the 1st primary side switch tube are closed, the voltage of the clamping capacitor will rise by a step, which means that the clamping capacitor absorbs the leakage energy of the corresponding power circuit.

[0131] It should be noted that, unlike the foregoing FIG. 19, as shown in FIG. 20, from the waveform diagram of the 1st control signal to the 4th control signal, on the left side of the dashed line l3, that is, at time 25.03 and before, the 1st primary side switch tube to the 4th primary side switch tube undergoes two times of conduction to closing, that is, r is 2, the clamping capacitor absorbs the leakage energy of the two 4 transformers, which is equivalent to absorbing the leakage energy of 8 transformers, and the peak value of the voltage of the clamping capacitor is about 630, which is higher than the leakage energy when r is 1.

[0132] Further, at the dashed line l1, the 1st drive control signal (the i-th drive control signal) is switched to a low level, the 1st primary side switch tube (the i-th primary side switch tube) is closed, the clamping control signal is switched to a high level, and the active clamping tube is turned on.

[0133] It should be noted that the delay time interval after the 1st primary side switch tube is closed is the continuous conduction time of the active clamping tube, that is, the interval time between the dashed line l3 and the dashed line l4. When the active clamping tube is turned on, the active clamping tube is used to release the leakage energy of 8 transformers absorbed by the clamping capacitor to the output circuit, so as to realize the recovery of the leakage energy.

[0134] As can be seen from the voltage waveform diagram of the clamping capacitor, after the active clamping tube is turned on, the voltage of the clamping capacitor will drop by a large step, which means that the leakage energy absorbed in the clamping capacitor is recovered once. Correspondingly, it can be seen that there is a relatively large boost pulse on the waveform diagram of the 1st output current of the 1st power circuit, which means that the leakage energy is released to the output circuit through the 1st power circuit (active clamping tube). Similarly, there is also a large boost pulse on the total output current of the output circuit.

[0135] As can be seen from the waveform diagram of the output voltage, after the active clamping tube is turned on, the leakage energy is released to the output circuit through the 1st power circuit (active clamping tube), and there is a boost pulse on the waveform diagram of the output voltage.

[0136] That is, in every two switching periods, the active clamping tube on the 1st power circuit recovers the leakage energy once.

[0137] It can be seen that, for the same multi-path topology, the greater the r, the greater the leakage energy recovered at one time, and because the active switch tube will be turned on each time, the corresponding loss will be generated, and thus the greater the r, the fewer the times of turning on the active switch tube, the more leakage energy absorbed on the clamping capacitor, thereby resulting in less loss of the power switch tube and higher efficiency of recovering leakage energy.

[0138] It can be understood that the above examples are only examples for better understanding the technical solutions of the embodiments of the present application, and are not the only limitation of the embodiments of the present application.

[0139] It should be noted that, in the description of the present application, the orientation or position relationship indicated by the terms "upper", "lower", etc. is based on the orientation or position relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application. For those of ordinary skill in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0140] It should also be noted that, in the description of the present application, the relationship 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 the entities or operations. Moreover, the terms "include", "contain" or any other variant thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or device. Without more limitations, the element defined by the statement "including a…" does not exclude the presence of another identical element in the process, method, article or device including the element.

[0141] In the embodiments of the present application, the singular form "one", "the" and the like includes the plural form and should be broadly understood as "one kind" or "one type" rather than limited to the meaning of "one"; in addition, the term "said" should be understood to include both the singular form and the plural form, 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.

[0142] It should be understood that the various forms of flow shown above can be reordered, added or deleted. For example, the steps described in the present disclosure can be executed in parallel, sequentially or in different order, as long as the desired results of the technical solutions of the present disclosure can be achieved, which is not limited herein.

[0143] The foregoing detailed description has set forth various embodiments of the present disclosure via examples and / or specific tissue but is not meant to be limiting. It will be understood that modifications, combinations, sub-combinations, and alternatives can become apparent to those of ordinary skill in the art upon reading the foregoing description, and can be made without departing from the scope and spirit of the disclosure. Accordingly, the scope of the present disclosure should be determined by reference to the appended claims.

[0144] It should be understood that various forms of flow shown above can be re-ordered, added to, or deleted from without departing from the scope of the present disclosure. For example, the steps recited in the present disclosure can be executed in parallel, executed in an order other than that described, or executed in a different order, so long as the desired results of the present disclosure are achieved. The present disclosure is not limited in this regard.

[0145] While certain embodiments of the application have been described herein as including particular features, components, or steps, other embodiments are possible having a combination of features, components, or steps different from those described, without departing from the scope of the present application. The scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A magnetic element, comprising a magnetic core structure and a coil structure, wherein: the magnetic core structure comprises oppositely arranged upper and lower magnetic core bases and N magnetic core columns and at least one side column arranged between the upper and lower magnetic core bases, N being a natural number greater than 1; the coil structure comprises N coils respectively wound on each of the magnetic core columns, wherein: winding directions of the coils on adjacent magnetic core columns are opposite; and at least one of upper bottom surfaces of the magnetic core columns and the upper magnetic core base, lower bottom surfaces of the magnetic core columns and the lower magnetic core base, and side surfaces of the magnetic core columns is provided with an air gap; the N magnetic core columns are located on the same side of the side column; and centers of projections of each of the magnetic core columns on the upper or lower magnetic core base are on a straight line. The magnetic element further comprises: a voltage source, an absorption circuit, a power unit, and an output circuit, wherein: the power unit comprises N power circuits connected in parallel, each of which comprises a clamping tube, a transformer, a primary switch tube, and a secondary switch tube, wherein a clamping tube of an i th power circuit is an active clamping tube, and clamping tubes of the remaining (N-1) power circuits are passive clamping tubes, N being a natural number greater than 1, and 1≤i≤N; the absorption circuit is connected to the voltage source and the power unit, and is configured to absorb leakage energy of N transformers and release the leakage energy of the N transformers to the output circuit through the active clamping tube; and each of the transformers comprises the magnetic core column according to any one of claims 1-3 and a coil wound on the magnetic core column. The i th power circuit comprises 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 comprising an i th primary winding and an i th secondary winding; a same name end of the i th primary winding is connected to the absorption circuit; a non-same name end of the i th primary winding is connected to a source of the active clamping tube and a drain of the i th primary switch tube; a non-same name end of the i th secondary winding is connected to a positive electrode of the i th secondary switch tube; a same name end of the i th secondary winding, a negative electrode of the i th secondary switch tube, and the output circuit are connected; a drain of the active clamping tube is connected to the absorption circuit, and a gate of the active clamping tube is configured to input a clamping control signal, wherein the clamping control signal is configured to control conduction and turn-off of the active clamping tube; and a source of the i th primary switch tube is connected to a negative electrode of the voltage source, and a gate of the i th primary switch tube is configured to input an i th driving control signal, wherein the i th driving control signal is configured to control conduction and turn-off of the i th primary switch tube. The remaining (N-1) power circuits have the same circuit structure and circuit connection relationship, wherein an m th power circuit comprises an m th passive clamping tube, an m th transformer, an m th primary switch tube, and an m th secondary switch tube, wherein: the m th transformer comprises an m th coil comprising an m th primary winding and an m th secondary winding. ​ 2. The magnetic element of claim 1, wherein, ​ 3. The magnetic element of claim 1, wherein, ​ 4. A topology for interleaved parallel flyback converter, wherein, ​ ​ ​ ​ ​ 5. The topology of claim 4, wherein, ​ ​ ​ ​ ​ ​ ​ ​ 6. The topology of claim 4, wherein, ​ ​ The same name end of the mth primary winding is connected to the positive pole of the voltage source; The non-same name end of the mth primary winding is connected to the positive pole of the mth passive clamp tube and the drain of the mth primary switch tube; The non-same name end of the mth secondary winding is connected to the positive pole of the mth secondary switch tube; The same name end of the mth secondary winding and the negative pole of the mth secondary switch tube are connected to the output circuit; The negative pole of the mth passive clamp tube is connected to the absorption circuit; The source of the mth primary switch tube is connected to the negative pole of the voltage source, and the gate of the mth primary switch tube is used for inputting the mth drive control signal, wherein the mth drive control signal is used for controlling the conduction and the closing of the mth primary switch tube, wherein 1≤m≤N and m≠i.

7. The topology of claim 4, wherein, The phase difference of the drive control signals of the adjacent two primary switch tubes is 360° / N.

8. The topology of claim 5, wherein, The absorption circuit comprises a clamp capacitor, wherein: The absorption circuit is used for absorbing the leakage energy of the N transformers through the clamp capacitor, and releasing the leakage energy of the N transformers to the output circuit through the active clamp tube.

9. The topology of claim 8, wherein, The first end of the clamp capacitor is connected to the same name end of the primary winding of the N transformers and the positive pole of the voltage source, and the second end of the clamp capacitor is connected to the drain of the active clamp tube and the negative pole of all passive clamp tubes.

10. The topology of claim 4, wherein, The output circuit comprises an output capacitor, wherein: The first end of the output capacitor is connected to the negative pole of all secondary switch tubes; The second end of the output capacitor is connected to the same name end of the secondary winding of all transformers.

11. The topology of any one of claims 4-10, wherein: The transistor type of the active clamp tube is silicon MOSFET, silicon carbide MOSFET or gallium nitride device; The transistor type of the passive clamp tube is silicon diode or silicon carbide diode; The transistor type of the primary switch tube is silicon MOSFET, silicon carbide MOSFET or gallium nitride device; The transistor type of the secondary switch tube is diode or MOSFET.

12. A leakage energy recovery method using the topology of any one of claims 4-11, comprising: configuring the phase difference of the drive control signals of the adjacent two primary switch tubes to be 360° / N; The absorption circuit absorbs the leakage energy of the N transformers and releases the leakage energy of the N transformers to the output circuit through the conduction of the active clamp tube.

13. The method of claim 12, wherein, From the conduction to the closing of all primary switch tubes, it is one power switching period, and the clamp control signal controls the conduction of the active clamp tube once every r power switching periods, and the leakage energy recovery is performed once, wherein r is a natural number greater than 0.

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