LLC circuit topology and switching power supply

Abstract

The utility model provides an LLC circuit topology and a switching power supply. The LLC circuit topology comprises a three-phase staggered LLC unit, a first switch unit and a first rectification unit, the input end of the three-phase staggered LLC unit is used for receiving three-phase input voltage; the three-phase staggered LLC unit comprises a three-phase LLC branch; each phase of LLC branch comprises a phase of transformer; a first switch unit is arranged between the first ends of the secondary coils of the transformers of all phases in the three-phase staggered LLC unit, so that secondary coil coupling or secondary coil decoupling is achieved between the LLC branches of all phases. The first end of the secondary coil of each phase transformer in the three-phase interleaving LLC unit is respectively connected with the first input end, the second input end and the third input end of the first rectification unit; the output end of the three-phase interleaving LLC unit is correspondingly connected to the output end of the first rectification unit in parallel and used for outputting voltage. According to the utility model, the gain variation range of the LLC circuit topology can be widened.

Description

Technical Field

[0001] The utility model relates to the technical field of switching power supplies, in particular to an LLC circuit topology and a switching power supply. Background Art

[0002] The power density of switching power supplies is increasing, and the input voltage range and output voltage range are becoming wider and wider, which poses greater challenges to the design of the main circuit inside the switching power supply.

[0003] As the main circuit inside the switching power supply, the LLC circuit needs to maintain a relatively wide gain range under conditions such as wide-range input, wide-range output, and wide constant-power output, so as to enable the switching power supply to achieve a wide input voltage range and output voltage range, reduce the losses of semiconductor devices and magnetic devices inside the switching power supply, improve the overall efficiency, and thus enable the switching power supply to operate at the optimal control point within the full range.

[0004] Therefore, how to design the LLC circuit so that it can maintain a relatively wide gain range to meet the requirements of the wide input voltage range and wide output voltage range of the switching power supply is an urgent problem to be solved. Summary of the Utility Model

[0005] The embodiment of the utility model provides an LLC circuit topology and a switching power supply to broaden the gain change range of the LLC circuit.

[0006] In a first aspect, the embodiment of the utility model provides an LLC circuit topology, including a three-phase interleaved LLC unit, a first switch unit, and a first rectification unit;

[0007] The input end of the three-phase interleaved LLC unit is used to receive a three-phase input voltage; the three-phase interleaved LLC unit includes three-phase LLC branches; each phase of LLC branch includes a phase transformer;

[0008] A first switch unit is arranged between the first ends of the secondary coils of the transformers in each phase of the three-phase interleaved LLC unit, so as to realize secondary coil coupling or secondary coil decoupling between each phase of LLC branches;

[0009] The first ends of the secondary coils of the transformers in each phase of the three-phase interleaved LLC unit are respectively connected to the first input end, the second input end, and the third input end of the first rectification unit;

[0010] The output end of the three-phase interleaved LLC unit is correspondingly connected in parallel to the output end of the first rectification unit for outputting voltage.

[0011] In a possible implementation manner, the first switch unit includes: a first switch and a second switch;

[0012] One end of the first switch is connected to the first end of the secondary coil of the first-phase transformer in the three-phase interleaved LLC unit, and the other end of the first switch is connected to the first end of the secondary coil of the second-phase transformer in the three-phase interleaved LLC unit;

[0013] One end of the second switch is connected to the first end of the secondary coil of the second-phase transformer in the three-phase interleaved LLC unit, and the other end of the second switch is connected to the first end of the secondary coil of the third-phase transformer in the three-phase interleaved LLC unit.

[0014] In a possible implementation, it further includes: a second switch unit;

[0015] The primary coils of the transformers in each phase of the three-phase interleaved LLC unit are connected through the second switch unit to achieve primary coil coupling or primary coil decoupling.

[0016] In a possible implementation, the second switch unit includes: a first switch module and a second switch module;

[0017] The respective end points on one side of the first switch module are respectively connected to the first ends of the primary coils of the transformers in each phase of the three-phase interleaved LLC unit; the respective end points on the other side of the first switch module are interconnected;

[0018] The respective end points on one side of the second switch module are respectively connected to the first ends of the primary coils of the transformers in each phase of the three-phase interleaved LLC unit; the respective end points on the other side of the second switch module are all grounded.

[0019] In a possible implementation, the first switch module includes: a third switch, a fourth switch, and a fifth switch;

[0020] One end of the third switch is connected to the first end of the primary coil of the first-phase transformer in the three-phase interleaved LLC unit;

[0021] One end of the fourth switch is connected to the first end of the primary coil of the second-phase transformer in the three-phase interleaved LLC unit;

[0022] One end of the fifth switch is connected to the first end of the primary coil of the third-phase transformer in the three-phase interleaved LLC unit;

[0023] The other end of the third switch is respectively connected to the other ends of the fourth switch and the fifth switch.

[0024] In a possible implementation, the second switch module includes: a sixth switch, a seventh switch, and an eighth switch;

[0025] One end of the sixth switch is connected to the first end of the primary coil of the first-phase transformer in the three-phase interleaved LLC unit;

[0026] One end of the seventh switch is connected to the first end of the primary coil of the second-phase transformer in the three-phase interleaved LLC unit;

[0027] One end of the eighth switch is connected to the first end of the primary coil of the third-phase transformer in the three-phase interleaved LLC unit;

[0028] The other ends of the sixth switch, the seventh switch, and the eighth switch are all grounded.

[0029] In a possible implementation manner, the first rectification unit includes: a first diode, a second diode, a third diode, a fourth diode, a fifth diode, and a sixth diode;

[0030] The negative electrode of the first diode is respectively connected to the negative electrode of the second diode, the negative electrode of the third diode, and an output end of the three-phase interleaved LLC unit;

[0031] The positive electrode of the first diode is respectively connected to the negative electrode of the fourth diode, and the first end of the secondary coil of the first-phase transformer in the three-phase interleaved LLC unit;

[0032] The positive electrode of the second diode is respectively connected to the negative electrode of the fifth diode, and the first end of the secondary coil of the second-phase transformer in the three-phase interleaved LLC unit;

[0033] The positive electrode of the third diode is respectively connected to the negative electrode of the sixth diode, and the first end of the secondary coil of the third-phase transformer in the three-phase interleaved LLC unit;

[0034] The positive electrode of the fourth diode is respectively connected to the positive electrode of the fifth diode, the positive electrode of the sixth diode, and another output end of the three-phase interleaved LLC unit.

[0035] In a possible implementation manner, the three-phase interleaved LLC unit further includes: a switch control module and a second rectification unit;

[0036] The voltage input end of the switch control module is used to receive a three-phase input voltage;

[0037] The output ends of the switch control module are respectively used to connect to the input ends of each phase of LLC branches;

[0038] The first output ends of each phase of LLC branches are respectively connected to the first input end, the second input end, and the third input end of the first rectification unit;

[0039] The second output ends of the respective phase LLC branches are respectively connected to the first input end, the second input end, and the third input end of the second rectifying unit;

[0040] The output end of the second rectifying unit is correspondingly connected in parallel to the output end of the first rectifying unit.

[0041] In a possible implementation manner, each phase LLC branch includes: a capacitor, an inductor, and a transformer;

[0042] The capacitor and the inductor are connected in series, and one end after series connection is connected to the output end of the switch control module;

[0043] One end after series connection is connected to the second end of the primary coil of the transformer;

[0044] The first end of the primary coil of the transformer is respectively connected to the first ends of the primary coils of the transformers in the remaining phase LLC branches;

[0045] The first end of the secondary coil of the transformer is connected to the first rectifying unit;

[0046] The second end of the secondary coil of the transformer is connected to the second rectifying unit.

[0047] In a second aspect, an embodiment of the present invention provides a switching power supply, including the LLC circuit topology according to any one of the first aspects.

[0048] The embodiment of the present invention provides an LLC circuit topology and a switching power supply. By providing a first switching unit between the first ends of the secondary coils of the transformers of each phase in a three-phase interleaved LLC unit, the secondary coils of the transformers of each phase in the three-phase interleaved LLC unit can be coupled or decoupled by changing the switching state of the first switching unit, thereby broadening the gain change range of the LLC circuit. Description of the Drawings

[0049] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for use in the embodiments or the description of the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0050] Figure 1 It is a schematic structural diagram of an LLC circuit topology provided by an embodiment of the present invention;

[0051] Figure 2 It is a schematic structural diagram of a three-phase interleaved LLC unit in the related art;

[0052] Figure 3It is a schematic structural diagram of an LLC circuit topology provided by another embodiment of the present utility model. Detailed implementation manners

[0053] In order to enable those skilled in the art to better understand this solution, the technical solutions in the embodiments of this solution will be clearly described below in conjunction with the accompanying drawings in the embodiments of this solution. Obviously, the described embodiments are some, rather than all, of the embodiments of this solution. Based on the embodiments in this solution, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of this solution.

[0054] The term "including" in the specification, claims and above-mentioned accompanying drawings of this solution, as well as any other deformation, means "including but not limited to", and is intended to cover non-exclusive inclusion, not limited to the examples listed in the text. In addition, terms such as "first" and "second" are used to distinguish different objects, rather than to describe a specific order.

[0055] As the main circuit inside the switching power supply, the LLC circuit needs to maintain a relatively wide gain change range in order to enable the switching power supply to achieve a relatively wide input voltage range and output voltage range. Therefore, how to design the LLC circuit so that it can maintain a relatively wide gain change range is an urgent problem to be solved. [[ID=...]]

[0056] With the idea of broadening the gain change range of the LLC circuit, in the specific implementation manner of this application, a first switching unit is arranged between the first ends of the secondary coils of the transformers of each phase of the three-phase interleaved LLC unit. By changing the switching state of the first switching unit, the secondary coils of the transformers of each phase of the three-phase interleaved LLC unit can be coupled or decoupled, thereby broadening the gain change range of the LLC circuit.

[0057] The implementation of the present utility model will be described in detail below in conjunction with specific accompanying drawings:

[0058] Figure 1 It is a schematic structural diagram of an LLC circuit topology provided by an embodiment of the present utility model. Refer to Figure 1 , this LLC circuit topology includes: a three-phase interleaved LLC unit 11, a first switching unit 12, and a first rectifying unit 13.

[0059] The input end of the three-phase interleaved LLC unit 11 is used to receive a three-phase input voltage; the three-phase interleaved LLC unit 11 includes three-phase LLC branches 111; each phase of LLC branch 111 includes a phase transformer;

[0060] A first switching unit 12 is arranged between the first ends of the secondary coils of the transformers of each phase in the three-phase interleaved LLC unit 11, so as to realize secondary coil coupling or secondary coil decoupling between the LLC branches of each phase;

[0061] The first ends of the secondary coils of the transformers of each phase in the three-phase interleaved LLC unit 11 are respectively connected to the first input end, the second input end and the third input end of the first rectifying unit 13;

[0062] The output end of the three-phase interleaved LLC unit 11 is correspondingly connected in parallel to the output end of the first rectifying unit 13 for outputting voltage.

[0063] In the related art, the circuit topology of the three-phase interleaved LLC unit is usually as Figure 2 shown. The control phase sequence of each phase in the three-phase interleaved LLC unit differs by 120°. The first ends of the primary coils of the transformers of each phase are interconnected, and the first ends of the secondary coils are interconnected, respectively forming the primary coil midpoint Op and the secondary coil midpoint Os. Under ideal conditions, the zero-sequence components of the primary coil midpoint Op and the secondary coil midpoint Os are 0, that is, three-way complete coupling. Under the condition of three-way complete coupling, the output rectification gain of the three-phase interleaved LLC unit is times that of the single-phase output rectification gain. Usually, the three-phase interleaved LLC unit operates under the condition of three-way complete coupling for high-gain rectification, but it cannot meet the requirement of a wide gain change range.

[0064] Considering that the LLC branches of each phase in the three-phase interleaved LLC unit are interleaved and paralleled, and the control phases of each phase differ by a fixed phase value, there is a coupling relationship inside the three-phase interleaved LLC unit. On this basis, in the embodiment of the present invention, a first switching unit 12 is arranged between the first ends of the secondary coils of the transformers of each phase in the three-phase interleaved LLC unit 11 to realize secondary coil coupling or secondary coil decoupling, thereby broadening the gain transformation range of the LLC circuit topology.

[0065] Among them, when the first switching unit 12 is closed, the first ends of the secondary coils of the transformers of each phase are interconnected to form the secondary coil midpoint 0s. That is, the secondary coils of the transformers of each phase are mutually coupled, and the LLC circuit is in the high-gain rectification mode. When the first switching unit 12 is opened, the secondary coil midpoint 0s disappears, the secondary coils of the transformers of each phase are decoupled, and each transformer outputs through the second rectifying unit by single path. The gain at this time is of the high-gain rectification mode. By changing the on-off state of the first switching unit 12, the gain of the LLC circuit topology can be changed, so as to achieve the purpose of broadening the gain change range.

[0066] In some embodiments, referring to Figure 1 , the three-phase interleaved LLC unit 11 further includes: a switch control module 112 and a second rectifying unit 113.

[0067] The voltage input terminal of the switch control module 112 is used to receive a three-phase input voltage;

[0068] The output terminals of the switch control module 112 are respectively used to connect the input terminals of each phase LLC branch 111;

[0069] The first output terminals of each phase LLC branch 111 are respectively connected to the first input terminal, the second input terminal, and the third input terminal of the first rectification unit 13;

[0070] The second output terminals of each phase LLC branch 111 are respectively connected to the first input terminal, the second input terminal, and the third input terminal of the second rectification unit 113;

[0071] The output terminal of the second rectification unit 113 is correspondingly connected in parallel to the output terminal of the first rectification unit 13.

[0072] Specifically, refer to Figure 1 , the switch control module 112 includes six switching tubes. The midpoint of every two switching tubes is connected to a phase LLC branch, used to receive a three-phase input voltage, and respectively transfer each phase voltage to the corresponding LLC branch. Usually, an input capacitor C1 can be connected in parallel at the input terminal of the switch control module 112 to stabilize the input voltage.

[0073] Here, the first output terminal of each phase LLC branch is the first end of the secondary coil of the transformer of each phase LLC branch, and the second output terminal of each phase LLC branch is the second end of the secondary coil of the transformer of each phase LLC branch.

[0074] In some embodiments, each phase LLC branch 111 includes: a capacitor, an inductor, and a transformer;

[0075] The capacitor and the inductor are connected in series, and one end after series connection is connected to the output terminal of the switch control module 112;

[0076] One end after series connection is connected to the second end of the primary coil of the transformer;

[0077] The first end of the primary coil of the transformer is respectively connected to the first end of the primary coil of the transformer in the remaining phase LLC branches;

[0078] The first end of the secondary coil of the transformer is connected to the first rectification unit;

[0079] The second end of the secondary coil of the transformer is connected to the second rectification unit.

[0080] Specifically, refer to Figure 1, taking the first-phase LLC branch as an example, the capacitor Cr1 and the inductor Lr1 are connected in series. One end of the series connection is connected to an output terminal of the switch control module 112, and the other end of the series connection is connected to the second end of the primary coil of the first-phase transformer T1. The first end of the primary coil of the first-phase transformer T1 is connected to the first ends of the primary coils of the transformers of the remaining two phases to achieve primary coil coupling. The first end of the secondary coil of the first-phase transformer T1 is connected to an input terminal of the second rectification unit 113, and the second end of the secondary coil of the first-phase transformer T1 is connected to an input terminal of the first rectification unit 13.

[0081] In some embodiments, referring to Figure 1 , the first rectification unit 13 includes: a first diode D1, a second diode D2, a third diode D3, a fourth diode D4, a fifth diode D5, and a sixth diode D6.

[0082] The negative electrode of the first diode D1 is respectively connected to the negative electrodes of the second diode D2, the third diode D3, and an output terminal of the three-phase interleaved LLC unit 11;

[0083] The positive electrode of the first diode D1 is respectively connected to the negative electrode of the fourth diode D4 and the first end of the secondary coil of the first-phase transformer T1 in the three-phase interleaved LLC unit 11;

[0084] The positive electrode of the second diode D2 is respectively connected to the negative electrode of the fifth diode D5 and the first end of the secondary coil of the second-phase transformer T2 in the three-phase interleaved LLC unit 11;

[0085] The positive electrode of the third diode D3 is respectively connected to the negative electrode of the sixth diode D6 and the first end of the secondary coil of the third-phase transformer T3 in the three-phase interleaved LLC unit 11;

[0086] The positive electrode of the fourth diode D4 is respectively connected to the positive electrodes of the fifth diode D5, the sixth diode D6, and another output terminal of the three-phase interleaved LLC unit 11.

[0087] Here, the first rectification unit can provide a single-path rectification output path for each phase transformer in the state of secondary coil decoupling to ensure that each phase transformer can output rectification separately in a single path. Usually, an output capacitor C2 can be connected in parallel at the output terminal of the first rectification unit to stabilize the output voltage.

[0088] Among them, the circuit topologies of the second rectification unit and the first rectification unit are the same, which will not be elaborated here.

[0089] In the embodiment of the present utility model, a first switching unit is provided at the first end of the secondary coil of each phase transformer of the three-phase interleaved LLC unit. By changing the switching state of the first switching unit, secondary coil coupling or secondary coil decoupling can be achieved, thereby changing the gain of the three-phase interleaved LLC unit and broadening the gain variation range of the LLC circuit topology.

[0090] In some embodiments, referring to Figure 1 , the first switching unit 12 includes: a first switch K1 and a second switch K2.

[0091] One end of the first switch K1 is connected to the first end of the secondary coil of the first-phase transformer T1 in the three-phase interleaved LLC unit 11, and the other end of the first switch K1 is connected to the first end of the secondary coil of the second-phase transformer T2 in the three-phase interleaved LLC unit 11;

[0092] One end of the second switch K2 is connected to the first end of the secondary coil of the second-phase transformer T2 in the three-phase interleaved LLC unit 11, and the other end of the second switch K2 is connected to the first end of the secondary coil of the third-phase transformer T3 in the three-phase interleaved LLC unit 11.

[0093] Here, when the first switch K1 and the second switch K2 are closed simultaneously, the first switching unit 12 is in the closed state. At this time, the first ends of the secondary coils of the first-phase transformer T1, the second-phase transformer T2, and the third-phase transformer T3 in the three-phase interleaved LLC unit 11 are interconnected to form the secondary coil midpoint Os. The secondary coils of the transformers in each phase of the three-phase interleaved LLC unit 11 are coupled to each other, and the gain increases.

[0094] When the first switch K1 and the second switch K2 are opened simultaneously, the first switching unit 12 is in the open state. At this time, the secondary coil midpoint Os disappears, and the secondary coils of the transformers in each phase of the three-phase interleaved LLC unit 11 are decoupled, and the gain decreases.

[0095] In some embodiments, referring to Figure 3 , the above LLC circuit topology further includes: a second switching unit 31.

[0096] The primary coils of the transformers in each phase of the three-phase interleaved LLC unit are connected through the second switching unit 31 to achieve primary coil coupling or primary coil decoupling.

[0097] Similarly, by providing a second switching unit on the primary coil side of each phase transformer in the three-phase interleaved LLC unit, primary coil coupling or primary coil decoupling can be achieved, thereby further broadening the gain variation range on the primary side.

[0098] In some embodiments, referring to Figure 3 , the second switching unit 31 includes: a first switching module 311 and a second switching module 312.

[0099] Each end point on one side of the first switch module 311 is respectively connected to the first end of the primary coil of each phase transformer in the three-phase interleaved LLC unit; each end point on the other side of the first switch module 311 is interconnected.

[0100] Each end point on one side of the second switch module 312 is respectively connected to the first end of the primary coil of each phase transformer in the three-phase interleaved LLC unit; each end point on the other side of the second switch module 312 is grounded.

[0101] In some embodiments, the first switch module 311 includes: a third switch K3, a fourth switch K4, and a fifth switch K5.

[0102] One end of the third switch K3 is connected to the first end of the primary coil of the first-phase transformer in the three-phase interleaved LLC unit.

[0103] One end of the fourth switch K4 is connected to the first end of the primary coil of the second-phase transformer in the three-phase interleaved LLC unit.

[0104] One end of the fifth switch K5 is connected to the first end of the primary coil of the third-phase transformer in the three-phase interleaved LLC unit.

[0105] The other end of the third switch K3 is respectively connected to the other ends of the fourth switch K4 and the fifth switch K5.

[0106] Among them, each end point on one side of the first switch module refers to one end of the third switch, one end of the fourth switch, and one end of the fifth switch. Each end point on the other side of the first switch module refers to the other end of the third switch, the other end of the fourth switch, and the other end of the fifth switch.

[0107] In some embodiments, the second switch module 312 includes: a sixth switch K6, a seventh switch K7, and an eighth switch K8.

[0108] One end of the sixth switch K6 is connected to the first end of the primary coil of the first-phase transformer in the three-phase interleaved LLC unit.

[0109] One end of the seventh switch K7 is connected to the first end of the primary coil of the second-phase transformer in the three-phase interleaved LLC unit.

[0110] One end of the eighth switch K8 is connected to the first end of the primary coil of the third-phase transformer in the three-phase interleaved LLC unit.

[0111] The other ends of the sixth switch K6, the seventh switch K7, and the eighth switch K8 are all grounded.

[0112] Among them, the endpoints on one side of the second switch module refer to one end of the sixth switch, one end of the seventh switch, and one end of the eighth switch. The endpoints on the other side of the second switch module refer to the other end of the sixth switch, the other end of the seventh switch, and the other end of the eighth switch.

[0113] Here, when the third switch K3, the fourth switch K4, and the fifth switch K5 are all closed, and the sixth switch K6, the seventh switch K7, and the eighth switch K8 are all open, the first ends of the primary coils of the transformers in each phase of the three-phase interleaved LLC unit are interconnected to form the primary coil midpoint Op. The three-phase interleaved LLC unit 11 operates in a three-phase interleaved state, that is, a high-gain topology state.

[0114] When the third switch K3, the fourth switch K4, and the fifth switch K5 are all open, and the sixth switch K6, the seventh switch K7, and the eighth switch K8 are all closed, the primary coil midpoint Op disappears. At this time, the three-phase interleaved LLC unit is converted into three half-bridge primary decoupled LLCs, and the gain changes to that in the three-phase interleaved state.

[0115] Here, by setting the second switch unit on the primary coil side of the transformer, the primary gain change range of the LLC circuit topology can be further widened.

[0116] In the embodiment of the present utility model, the primary side of the transformer in the LLC circuit topology can be converted from a multi-interleaved coupling state to a decoupled single-channel half-bridge state. The secondary side can be converted from a multi-interleaved coupling rectification state to a decoupled single-channel rectification state. The primary side and the secondary side each have a two-stage gain change range, and the primary side gain state and the secondary gain state can be arbitrarily matched according to actual requirements, so as to widen the gain change range of the LLC circuit topology and improve the ease for circuit designers.

[0117] Based on the above LLC circuit topology, the present utility model further provides a switching power supply, including the above LLC circuit topology.

[0118] The above embodiments are only used to illustrate the technical solutions of the present utility model, rather than to limit it; although the present utility model has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present utility model.

Claims

1. An LLC circuit topology, characterized in that, Comprising: A three-phase interleaved LLC unit, a first switching unit, and a first rectifying unit; The input end of the three-phase interleaved LLC unit is used to receive a three-phase input voltage; the three-phase interleaved LLC unit includes three-phase LLC branches; each phase of LLC branch includes a phase transformer; A first switching unit is arranged between the first ends of the secondary coils of the transformers in each phase of the three-phase interleaved LLC unit, so that secondary coil coupling or secondary coil decoupling is achieved between the LLC branches of each phase; The first ends of the secondary coils of the transformers in each phase of the three-phase interleaved LLC unit are respectively connected to the first input end, the second input end, and the third input end of the first rectifying unit; The output end of the three-phase interleaved LLC unit is correspondingly connected in parallel to the output end of the first rectifying unit for outputting a voltage.

2. The LLC circuit topology according to claim 1, characterized in that, The first switching unit includes: a first switch and a second switch; One end of the first switch is connected to the first end of the secondary coil of the first-phase transformer in the three-phase interleaved LLC unit, and the other end of the first switch is connected to the first end of the secondary coil of the second-phase transformer in the three-phase interleaved LLC unit; One end of the second switch is connected to the first end of the secondary coil of the second-phase transformer in the three-phase interleaved LLC unit, and the other end of the second switch is connected to the first end of the secondary coil of the third-phase transformer in the three-phase interleaved LLC unit.

3. The LLC circuit topology according to claim 1 or 2, characterized in that, Further comprising: A second switching unit; The primary coils of the transformers in each phase of the three-phase interleaved LLC unit are connected through the second switching unit to achieve primary coil coupling or primary coil decoupling.

4. The LLC circuit topology according to claim 3, characterized in that, The second switching unit includes: a first switching module and a second switching module; The respective end points on one side of the first switching module are respectively connected to the first ends of the primary coils of the transformers in each phase of the three-phase interleaved LLC unit; the respective end points on the other side of the first switching module are interconnected; The respective end points on one side of the second switching module are respectively connected to the first ends of the primary coils of the transformers in each phase of the three-phase interleaved LLC unit; the respective end points on the other side of the second switching module are all grounded.

5. The LLC circuit topology according to claim 4, characterized in that, The first switching module includes: a third switch, a fourth switch, and a fifth switch; One end of the third switch is connected to the first end of the primary coil of the first-phase transformer in the three-phase interleaved LLC unit; One end of the fourth switch is connected to the first end of the primary coil of the second-phase transformer in the three-phase interleaved LLC unit; One end of the fifth switch is connected to the first end of the primary coil of the third-phase transformer in the three-phase interleaved LLC unit; The other end of the third switch is respectively connected to the other ends of the fourth switch and the fifth switch.

6. The LLC circuit topology according to claim 4, characterized in that, The second switching module includes: a sixth switch, a seventh switch, and an eighth switch; One end of the sixth switch is connected to the first end of the primary coil of the first-phase transformer in the three-phase interleaved LLC unit; One end of the seventh switch is connected to the first end of the primary coil of the second-phase transformer in the three-phase interleaved LLC unit; One end of the eighth switch is connected to the first end of the primary coil of the third-phase transformer in the three-phase interleaved LLC unit; The other ends of the sixth switch, the seventh switch, and the eighth switch are all grounded.

7. The LLC circuit topology according to claim 1 or 2, characterized in that, The first rectifying unit includes: a first diode, a second diode, a third diode, a fourth diode, a fifth diode, and a sixth diode; The negative electrode of the first diode is respectively connected to the negative electrode of the second diode, the negative electrode of the third diode, and an output terminal of the three-phase interleaved LLC unit; The positive electrode of the first diode is respectively connected to the negative electrode of the fourth diode and the first end of the secondary coil of the first-phase transformer in the three-phase interleaved LLC unit; The positive electrode of the second diode is respectively connected to the negative electrode of the fifth diode and the first end of the secondary coil of the second-phase transformer in the three-phase interleaved LLC unit; The positive electrode of the third diode is respectively connected to the negative electrode of the sixth diode and the first end of the secondary coil of the third-phase transformer in the three-phase interleaved LLC unit; The positive electrode of the fourth diode is respectively connected to the positive electrode of the fifth diode, the positive electrode of the sixth diode, and the other output terminal of the three-phase interleaved LLC unit.

8. The LLC circuit topology according to claim 1 or 2, characterized in that, The three-phase interleaved LLC unit further includes: a switch control module and a second rectifying unit; The voltage input terminal of the switch control module is used to receive a three-phase input voltage; The output terminals of the switch control module are respectively used to connect the input terminals of each phase of the LLC branch; The first output terminals of each phase of the LLC branch are respectively connected to the first input terminal, the second input terminal, and the third input terminal of the first rectifying unit; The second output terminals of each phase of the LLC branch are respectively connected to the first input terminal, the second input terminal, and the third input terminal of the second rectifying unit; The output terminals of the second rectifying unit are correspondingly connected in parallel to the output terminals of the first rectifying unit.

9. The LLC circuit topology according to claim 8, characterized in that, Each phase of the LLC branch includes: a capacitor, an inductor, and a transformer; The capacitor and the inductor are connected in series, and one end after series connection is connected to the output terminal of the switch control module; One end after series connection is connected to the second end of the primary coil of the transformer; The first end of the primary coil of the transformer is respectively connected to the first end of the primary coil of the transformer in the remaining phase LLC branches; The first end of the secondary coil of the transformer is connected to the first rectifying unit; The second end of the secondary coil of the transformer is connected to the second rectifying unit.

10. A switching power supply, characterized in that, It includes the LLC circuit topology according to any one of claims 1-9.

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