An LLC resonant conversion circuit and an LLC resonant converter

Abstract

The application discloses an LLC resonant conversion circuit and an LLC resonant converter, wherein the LLC resonant conversion circuit comprises an input end, a first half-bridge LLC circuit, a second half-bridge LLC circuit, an output end, a conversion device, a first driving end and a second driving end; the first half-bridge LLC circuit and the second half-bridge LLC circuit are connected in parallel between the input end and the output end; the conversion device is connected with resonant cavities of the two half-bridge LLC circuits respectively and is used for connecting the two resonant cavities in series; different driving signals are input into the two driving ends in a cross mode, so that the current of the resonant cavity of each half-bridge LLC circuit passes through the resonant cavity of the other half-bridge LLC circuit, the currents of the resonant cavities of the two LLC circuits are equal, the rectified output currents of the two half-bridge LLC circuits are also equal, and the problem of uneven current in parallel can be solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of circuit, in particular to an LLC resonant conversion circuit and an LLC resonant converter. BACKGROUND

[0002] The LLC resonant conversion circuit is widely used because of low loss and high efficiency in the working process. However, the LLC resonant conversion circuit is very sensitive to the parameters of the device, especially the parameters of the resonant cavity, such as the inductance of the resonant inductor and the capacitance of the resonant capacitor. Compared with the resistor, the inductance and the capacitance usually have large errors and are not easy to control. The change of the parameters of the device of the resonant cavity will change the state of the resonant cavity and cause poor consistency of the final product.

[0003] If two LLC circuits are connected in parallel, the parallel current will not be uniform due to the obvious influence of the parameters of the resonant cavity on the gain. SUMMARY

[0004] The present application provides an LLC resonant conversion circuit and an LLC resonant converter to solve the problem of uneven parallel current caused by the parallel connection of two LLC circuits in the prior art.

[0005] In a first aspect, an embodiment of the present application provides an LLC resonant conversion circuit, which comprises an input end, a first half-bridge LLC circuit, a second half-bridge LLC circuit, an output end, a conversion device, a first driving end and a second driving end, wherein,

[0006] The first LLC half-bridge circuit and the second LLC half-bridge circuit are connected in parallel between the input end and the output end;

[0007] The conversion device is connected with a first resonant cavity of the first LLC half-bridge circuit and a second resonant cavity of the second LLC half-bridge circuit respectively;

[0008] The conversion device is configured to disconnect a path between a first lower chopping switch of the first LLC half-bridge circuit and the first resonant cavity, disconnect a path between a second lower chopping switch of the second LLC half-bridge circuit and the second resonant cavity, and connect the first resonant cavity and the second resonant cavity in series;

[0009] The first driving end is connected with a control end of a first upper chopping switch of the first LLC half-bridge circuit and a control end of a second lower chopping switch of the second LLC half-bridge circuit;

[0010] The second driving end is connected with the first lower chopping switch and the second upper chopping switch.

[0011] In a possible implementation, the input end includes a first input end and a second input end;

[0012] The output end includes a first output end and a second output end;

[0013] The first half-bridge LLC circuit includes the first upper clamp switch, the first lower clamp switch, a first resonant inductor, a first resonant capacitor, and a first rectification circuit including a first isolation transformer, wherein,

[0014] The first resonant inductor and the first resonant capacitor are connected in series to form a first resonant cavity, a first end of the first upper clamp switch is connected to the first input end, a second end of the first upper clamp switch is connected to a first end of the first lower clamp switch and a first end of the first resonant cavity, a second end of the first resonant cavity is connected to a first end of the conversion device, a second end of the first lower clamp switch is connected to the second input end, a positive output end of the first rectification circuit is connected to the first output end, and a negative output end of the first rectification circuit is connected to the second output end;

[0015] The second half-bridge LLC circuit includes the second upper clamp switch, the second lower clamp switch, a second resonant inductor, a second resonant capacitor, and a second rectification circuit including a second isolation transformer, wherein,

[0016] The second resonant inductor and the second resonant capacitor are connected in series to form a second resonant cavity, a first end of the second upper clamp switch is connected to the first input end, a second end of the second upper clamp switch is connected to a first end of the second lower clamp switch and a first end of the second resonant cavity, a second end of the second resonant cavity is connected to a second end of the conversion device, a second end of the second lower clamp switch is connected to the second input end, a positive output end of the second rectification circuit is connected to the second output end, and a negative output end of the second rectification circuit is connected to the second output end.

[0017] In a possible implementation, the conversion device is a jumper;

[0018] A first jumper port of the jumper serves as the first end of the conversion device, a second jumper port of the jumper serves as the second end of the conversion device, a third jumper port of the jumper is connected to the second end of the first lower clamp switch, and a fourth jumper port of the jumper is connected to the second end of the second lower clamp switch, wherein,

[0019] A first jumper is connected between the first jumper port and the second jumper port.

[0020] In a possible implementation, the first jumper is not connected between the first jumper port and the second jumper port, a second jumper is connected between the first jumper port and the third jumper port, and a third jumper is connected between the second jumper port and the fourth jumper port, so as to make the path between the first lower chopper switch and the first resonant cavity conductive, the path between the second lower chopper switch and the second resonant cavity conductive, and the path between the first resonant cavity and the second resonant cavity disconnected.

[0021] In a possible implementation, the conversion device is a first single-pole double-throw switch and a second single-pole double-throw switch.

[0022] The fixed contact of the first single-pole double-throw switch is a first end of the conversion device, the first moving contact of the first single-pole double-throw switch is connected with a second end of the first lower chopper switch, and the second moving contact of the first single-pole double-throw switch is connected with a second moving contact of the second single-pole double-throw switch.

[0023] The fixed contact of the second single-pole double-throw switch is a second end of the conversion device, the first moving contact of the second single-pole double-throw switch is connected with a second end of the second lower chopper switch, and the second moving contact of the second single-pole double-throw switch is connected with a second moving contact of the second single-pole double-throw switch.

[0024] The fixed contact of the first single-pole double-throw switch is connected with the second moving contact of the first single-pole double-throw switch, and the fixed contact of the second single-pole double-throw switch is connected with the second moving contact of the second single-pole double-throw switch.

[0025] In a possible implementation, the fixed contact of the first single-pole double-throw switch is connected with the second moving contact of the first single-pole double-throw switch, and the fixed contact of the second single-pole double-throw switch is connected with the second moving contact of the second single-pole double-throw switch.

[0026] In a possible implementation, the conversion device is a connection line.

[0027] A first end of the connection line is a first end of the conversion device, and a second end of the connection line is a second end of the conversion device.

[0028] In a possible implementation, one end of the first resonant inductor is a first end of the first resonant cavity, and one end of the first resonant capacitor is a second end of the first resonant cavity.

[0029] One end of the second resonant inductor is a first end of the second resonant cavity, and one end of the second resonant capacitor is a second end of the second resonant cavity.

[0030] In a possible implementation, the first rectifier circuit and the second rectifier circuit are both full-bridge rectifier circuits.

[0031] The first rectifying circuit and the second rectifying circuit are full-wave rectifying circuits.

[0032] In a second aspect, the embodiments of the present application provide an LLC resonant converter comprising the LLC resonant conversion circuit of any one of the first aspect.

[0033] The present application has the following advantages:

[0034] The LLC resonant conversion circuit provided by the present application can disconnect the path between the first lower clamp switch of the first half-bridge LLC circuit and the first resonant cavity, disconnect the path between the second lower clamp switch of the second half-bridge LLC circuit and the second resonant cavity, and connect the first resonant cavity and the second resonant cavity in series. The first driving end is connected with the control end of the first upper clamp switch and the control end of the second lower clamp switch, and the second driving end is connected with the control end of the second upper clamp switch and the control end of the first lower clamp switch. Since the first resonant cavity and the second resonant cavity can be connected in series, and the first driving end and the second driving end are cross-connected, the current of the resonant cavity of each half-bridge LLC circuit has to pass through the resonant cavity of the other half-bridge LLC circuit, so that the currents of the resonant cavities of the two LLC circuits are equal, the rectified output currents of the two half-bridge LLC circuits are also equal, and the problem of uneven current in parallel can be solved. BRIEF DESCRIPTION OF DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0036] Figure 1 A schematic diagram of an LLC resonant conversion circuit provided by the related art;

[0037] Figure 2 A schematic diagram of an LLC resonant conversion circuit provided by the embodiments of the present application;

[0038] Figure 3 A schematic diagram of another LLC resonant conversion circuit provided by the embodiments of the present application;

[0039] Figure 4 A schematic diagram of another LLC resonant conversion circuit provided by the embodiments of the present application;

[0040] Figure 5 A schematic diagram of another LLC resonant conversion circuit provided by the embodiments of the present application;

[0041] Figure 6 A schematic diagram of a first rectifier circuit and a second rectifier circuit of an LLC resonant conversion circuit provided for an embodiment of the present application is shown in FIG. 1.

[0042] Figure 7 A schematic diagram of a first rectifier circuit and a second rectifier circuit of another LLC resonant conversion circuit provided for an embodiment of the present application is shown in FIG. 2.

[0043] Figure 8 A current flow direction schematic diagram of mode 1 of an LLC resonant conversion circuit provided for an embodiment of the present application is shown in FIG. 3.

[0044] Figure 9 A current flow direction schematic diagram of mode 2 of an LLC resonant conversion circuit provided for an embodiment of the present application is shown in FIG. 4.

[0045] Figure 10 A current flow direction schematic diagram of mode 3 of an LLC resonant conversion circuit provided for an embodiment of the present application is shown in FIG. 5.

[0046] Figure 11 A current flow direction schematic diagram of mode 2 of an LLC resonant conversion circuit provided for an embodiment of the present application is shown in FIG. 6. DETAILED DESCRIPTION

[0047] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all the other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the scope of protection of the present application.

[0048] As shown in FIG. 1, an LLC resonant conversion circuit in the related art includes two half-bridge LLC circuits connected in parallel to an input end and an output end, and each half-bridge LLC circuit includes a half-bridge chopper circuit, a resonant inductor, a rectifier circuit and a resonant capacitor. Figure 1

[0049] Figure 1 ​One of the two half-bridge LLC circuits comprises a half-bridge chopper circuit composed of a switching tube S1 and a switching tube S2, a first end of the switching tube S1 is connected with one end of an input end of the LLC resonant conversion circuit, a second end of the switching tube S1 is connected with a first end of the switching tube S2, a second end of the switching tube S2 is connected with the other end of the input end of the LLC resonant conversion circuit, control ends of the switching tube S1 and the switching tube S2 are connected with different driving ends for inputting different driving signals to control the switching tubes to be turned on and turned off, the resonant inductor L1, the rectifier circuit Rec1 and the resonant capacitor C1 are connected in series and then connected between the first end of the switching tube S2 and the second end of the switching tube S2, the other two ends of the rectifier circuit Rec1 are connected with an output end of the LLC resonant conversion circuit.

[0050] Figure 1 The other of the two half-bridge LLC circuits comprises a half-bridge chopper circuit composed of a switching tube S3 and a switching tube S4, a first end of the switching tube S3 is connected with one end of an input end of the LLC resonant conversion circuit, a second end of the switching tube S3 is connected with a first end of the switching tube S4, a second end of the switching tube S4 is connected with the other end of the input end of the LLC resonant conversion circuit, control ends of the switching tube S3 and the switching tube S4 are connected with different driving ends for inputting different driving signals to control the switching tubes to be turned on and turned off, the resonant inductor L2, the rectifier circuit Rec2 and the resonant capacitor C2 are connected in series and then connected between the first end of the switching tube S4 and the second end of the switching tube S4, the other two ends of the rectifier circuit Rec2 are connected with an output end of the LLC resonant conversion circuit.

[0051] As shown in the LLC resonant conversion circuit, Figure 1 by controlling the switching frequency of the switching tubes, the impedance of the resonant cavity is changed to realize the function of adjusting the voltage output at the output end, when the two half-bridge LLC circuits are connected in parallel and share the driving signals, the control frequencies of the two half-bridge LLC circuits are the same, at this time, whether the output is current-sharing completely depends on the device parameters of the resonant cavity, when the device parameters of the resonant cavities of the two half-bridge LLC circuits are inconsistent, the resonant cavity currents of the two half-bridge LLC circuits are quite different, which leads to serious current-sharing imbalance.

[0052] Based on the above problems, the embodiment of the present application provides an LLC resonant conversion circuit, as shown in the figure, Figure 2 the circuit comprises an input end (C1 and C2), a first half-bridge LLC circuit 10, a second half-bridge LLC circuit 20, an output end (D1 and D2), a conversion device 30, a first driving end A and a second driving end B, wherein:

[0053] the first LLC half-bridge circuit 10 and the second LLC half-bridge circuit 20 are connected in parallel between the input end (C1 and C2) and the output end (D1 and D2);

[0054] The switching device 30 is connected with the first resonant cavity of the first half-bridge LLC circuit 10 and the second resonant cavity of the second half-bridge LLC circuit 20 respectively, and is used for disconnecting the path between the first lower clamp switch S6 of the first half-bridge LLC circuit 10 and the first resonant cavity, disconnecting the path between the second lower clamp switch S8 of the second half-bridge LLC circuit 20 and the second resonant cavity, and connecting the first resonant cavity and the second resonant cavity in series;

[0055] The first driving end A is connected with the control end of the first upper clamp switch S5 of the first half-bridge LLC circuit 10 and the control end of the second lower clamp switch S8 of the second half-bridge LLC circuit 20.

[0056] The second driving end B is connected with the control end of the first lower clamp switch S6 of the first half-bridge LLC circuit 10 and the control end of the second upper clamp switch S7 of the second half-bridge LLC circuit 20.

[0057] In the above LLC resonant conversion circuit, the switching device can disconnect the path between the first lower clamp switch S6 of the first half-bridge LLC circuit 10 and the first resonant cavity, disconnect the path between the second lower clamp switch S8 of the second half-bridge LLC circuit 20 and the second resonant cavity, and connect the first resonant cavity and the second resonant cavity in series, the first driving end A is connected with the control end of the first upper clamp switch S5 and the control end of the second lower clamp switch S8, and the second driving end B is connected with the control end of the second upper clamp switch S5 and the control end of the first lower clamp switch S6. Since the first resonant cavity and the second resonant cavity can be connected in series, and the first driving end A and the second driving end B are cross-connected, the current of the resonant cavity of each half-bridge LLC circuit passes through the resonant cavity of the other half-bridge LLC circuit, so that the currents of the resonant cavities of the two LLC circuits are equal, the rectified output currents of the two half-bridge LLC circuits are also equal, and the problem of uneven current in parallel can be solved.

[0058] In the embodiment of the present application, the driving signal A and the driving signal B are driving signals with a phase difference of 180 degrees, the driving signal A is used for driving the first upper clamp switch S5 and the second lower clamp switch S8, and the driving signal B is used for driving the first lower clamp switch S6 and the second upper clamp switch S7.

[0059] It should be noted that the clamp switch in the embodiment of the present application can be a switch tube, such as an IGBT device, or a MOSFET device or a diode device.

[0060] It should be noted that the resonant cavity in the embodiment of the present application is an equivalent series circuit composed of a resonant inductor and a resonant capacitor. In order to clearly illustrate the technical features of the present application, only one resonant cavity is shown in the schematic diagram. For example, the resonant capacitor and the resonant inductor can be connected in series, or the inductor can be connected in series in the upper branch and the capacitor can be connected in series in the lower branch according to the schematic diagram, which are all series connections from the point of view of the circuit.

[0061] In a specific implementation, as shown in Figure 2 the input end can include a first input end C1 and a second input end C2, the output end includes a first output end D1 and a second output end D2, the first half-bridge LLC circuit 10 includes a first upper chopping switch S5, a first resonant inductor L3, a first resonant capacitor C3, and a first rectifier circuit Rec3 including a first isolation transformer, wherein,

[0062] the first resonant inductor L3 and the first resonant capacitor C3 are connected in series to form a first resonant cavity, a first end of the first upper chopping switch S5 is connected to the first input end C1, a second end of the first upper chopping switch S5 is connected to a first end of a first lower chopping switch S6 and a first end of the first resonant cavity, a second end of the first resonant cavity is connected to a first end of the conversion device 30, a second end of the first lower chopping switch S6 is connected to the second input end C2, a positive output end of the first rectifier circuit Rec3 is connected to the first output end D1, and a negative output end of the first rectifier circuit Rec3 is connected to the second output end D2.

[0063] the second half-bridge LLC circuit 20 includes a second upper chopping switch S7, a second lower chopping switch S8, a second resonant inductor L4, a second resonant capacitor C4, and a second rectifier circuit Rec4 including a second isolation transformer, wherein,

[0064] the second resonant inductor L4 and the second resonant capacitor C4 are connected in series to form a second resonant cavity, a first end of the second upper chopping switch S7 is connected to the first input end C1, a second end of the second upper chopping switch S7 is connected to a first end of the second lower chopping switch S8 and a first end of the second resonant cavity, a second end of the second resonant cavity is connected to a second end of the conversion device 30, a second end of the second lower chopping switch S8 is connected to the second input end C2, a positive output end of the second rectifier circuit Rec4 is connected to the first output end D1, and a negative output end of the second rectifier circuit Rec4 is connected to the second output end D2.

[0065] In a specific implementation, the conversion device 30 can be a jumper, a single-pole double-throw switch, such as a single-pole double-throw relay, or a connection line.

[0066] The following will be described with examples of a jumper, a single-pole double-throw switch, and a connection line, respectively.

[0067] As shown in Figure 3 , it is a schematic diagram of an LLC resonant conversion circuit provided by an embodiment of the present application, from Figure 3As can be seen, the first jumper port E1 of jumper 301 serves as the first end of the conversion device 30 and is connected to the second end of the first resonant cavity; the second jumper port E2 of jumper 301 serves as the second end of the conversion device 30; the third jumper port E3 of jumper 301 is connected to the second end of the first lower chopper switch S6; and the fourth jumper port E4 of jumper 301 is connected to the second end of the second lower chopper switch S8.

[0068] When a first jumper is connected between the first jumper port E1 and the second jumper port E2, the path between the first resonant cavity and the first lower chopper switch S6 is broken, and the path between the second resonant cavity and the second lower chopper switch S8 is broken, and the first and second resonant cavities are connected in series; when a second jumper is connected between the first jumper port E1 and the third jumper port E3, and a third jumper is connected between the second jumper port E2 and the fourth jumper port E4, the path between the first resonant cavity and the first lower chopper switch S6 is connected, the path between the second resonant cavity and the second lower chopper switch S8 is connected, and the path between the first and second resonant cavities is broken.

[0069] In the above embodiment, when a second jumper is connected between the first jumper port E1 and the third jumper port E3, and a third jumper is connected between the second jumper port E2 and the fourth jumper port E4, that is... Figure 1 The LLC resonant converter circuit shown is illustrated.

[0070] In one embodiment, such as Figure 4 The diagram shown is a schematic of an LLC resonant converter circuit provided in an embodiment of the present invention. Figure 4 As can be seen from the diagram, the conversion device 30 includes a first single-pole double-throw switch S21 and a second single-pole double-throw switch S22. The fixed contact of the first single-pole double-throw switch S21 serves as the first end of the conversion device and is connected to the second end of the first resonant cavity. The first moving contact of the first single-pole double-throw switch S21 is connected to the second end of the first lower chopper switch S6. The second moving contact of the first single-pole double-throw switch S21 is connected to the second moving contact of the second single-pole double-throw switch S22. The fixed contact of the second single-pole double-throw switch S22 serves as the second end of the conversion device 30, and the first moving contact of the second single-pole double-throw switch is connected to the second end of the second lower chopper switch.

[0071] When the fixed contact of the first single-pole double-throw switch S21 is connected to the second moving contact of the first single-pole double-throw switch S21, and the fixed contact of the second single-pole double-throw switch S22 is connected to the second moving contact of the second single-pole double-throw switch S22, the path between the first lower chopper switch S6 and the first resonant cavity is disconnected, the path between the second lower chopper switch S8 and the second resonant cavity is disconnected, and the first resonant cavity and the second resonant cavity are connected in series.

[0072] When the fixed contact of the first single-pole double-throw switch S21 is connected with the first movable contact of the first single-pole double-throw switch S21, and the fixed contact of the second single-pole double-throw switch S22 is connected with the first movable contact of the second single-pole double-throw switch S22, the path between the first lower chopper switch S6 and the first resonant cavity is turned on, and the path between the second lower chopper switch S8 and the second resonant cavity is turned on, that is Figure 1 the LLC resonant conversion circuit shown in the figure.

[0073] In an embodiment, as Figure 5 shown, a schematic diagram of an LLC resonant conversion circuit provided by an embodiment of the present application can be seen from Figure 5 , the conversion device 30 includes a connection line 201;

[0074] The first end of the connection line 201 is the first end of the conversion device 30 and is connected with the first resonant capacitor C3, and the second end of the connection line 201 is the second end of the conversion device 30 and is connected with the second resonant capacitor C4.

[0075] In implementation, the rectifier circuit in the embodiment of the present application can be a full-bridge rectifier circuit or a full-wave rectifier circuit, wherein the full-bridge rectifier circuit and the full-wave rectifier circuit can both include an isolation transformer.

[0076] As Figure 6 shown, a schematic diagram of the first rectifier circuit and the second rectifier circuit of the LLC resonant conversion circuit provided by an embodiment of the present application.

[0077] The first rectifier circuit Rec3 includes a first isolation transformer T1, a first switch S9, a second switch S10, a third switch S11 and a fourth switch S12, wherein the first switch S9 and the second switch S10 are connected in series to form a first bridge arm, the third switch S11 and the fourth switch S12 are connected in series to form a second bridge arm, the first bridge arm and the second bridge arm are connected in parallel, and the two ends after being connected in parallel are the positive output end and the negative output end of the first rectifier circuit Rec3, the primary winding of the first isolation transformer T1 is connected with the first resonant inductor L3 and the first resonant capacitor C3, and the secondary winding of the first isolation transformer T1 is connected with the midpoint of the first bridge arm and the midpoint of the second bridge arm;

[0078] The second rectifier circuit Rec4 includes a second isolation transformer T2, a fifth switch S13, a sixth switch S14, a seventh switch S15 and an eighth switch S16, wherein the fifth switch S13 and the sixth switch S14 are connected in series to form a third bridge arm, the seventh switch S15 and the eighth switch S16 are connected in series to form a fourth bridge arm, the third bridge arm and the fourth bridge arm are connected in parallel, and the two ends of the parallel connection are used as the positive output end and the negative output end of the first rectifier circuit Rec4, the primary winding of the second isolation transformer T2 is connected with the second resonant inductor L4 and the second resonant capacitor C4, and the secondary winding of the second isolation transformer T2 is connected with the midpoint of the third bridge arm and the midpoint of the fourth bridge arm.

[0079] As shown in Figure 7 , another schematic diagram of the first rectifier circuit and the second rectifier circuit in the LLC resonant conversion circuit provided by the embodiment of the present application is shown.

[0080] The first rectifier circuit Rec3 includes a first isolation transformer T1, a ninth switch S17 and a tenth switch S18, wherein the ninth switch S17 and the tenth switch S18 are connected in series to form a fifth bridge arm, the primary winding of the first isolation transformer T1 is connected with the first resonant inductor L3 and the first resonant capacitor C3, the first end of the secondary winding of the first isolation transformer T1 is connected with one end of the fifth bridge arm, the second end of the first isolation transformer T1 is connected with the other end of the fifth bridge arm, and the midpoint of the fifth bridge arm and the third end of the first isolation transformer T1 are used as the positive output end and the negative output end of the first rectifier circuit Rec3.

[0081] The second rectifier circuit Rec4 includes a second isolation transformer T2, an eleventh switch S19 and a twelfth switch S18, wherein the eleventh switch S19 and the twelfth switch S18 are connected in series to form a sixth bridge arm, the primary winding of the second isolation transformer T2 is connected with the second resonant inductor L4 and the second resonant capacitor C4, the first end of the secondary winding of the second isolation transformer T1 is connected with one end of the sixth bridge arm, the second end of the second isolation transformer T2 is connected with the other end of the sixth bridge arm, and the midpoint of the sixth bridge arm and the third end of the second isolation transformer T2 are used as the positive output end and the negative output end of the second rectifier circuit Rec4.

[0082] It should be noted that, Figure 6 and Figure 7 The switches in the above can be a switching tube, such as an IGBT device, or a MOSFET device or a diode device.

[0083] The structure of the LLC resonant conversion circuit provided by the embodiment of the present application is described above, and the working mode of the LLC resonant conversion circuit provided by the present application is described below by taking a single-pole double-throw switch as an example.

[0084] Depending on the combination of driving signals, the LLC resonant converter circuit provided in this embodiment of the invention can have the following four operating modes.

[0085] Mode 1:

[0086] The first upper chopper switch S5 is turned on, the first lower chopper switch S6 is turned off, the second upper chopper switch S7 is turned off, and the second lower chopper switch S8 is turned on. Figure 8 As shown, the current loop starts from the input terminal C1, passes through the first upper chopper switch S5, the first resonant inductor L3, the first rectifier circuit Rec1, the first resonant capacitor C3, the second resonant capacitor C4, the second rectifier circuit Rec2, the second resonant inductor L4, the second lower chopper switch S8, and returns to the second input terminal C2.

[0087] Mode 2:

[0088] The first upper chopper switch S5 is off, the second lower chopper switch S8 is off, the first lower chopper switch S6 is on, and the second upper chopper switch S7 is on. Figure 9 As shown, the current switches to the first lower chopper switch S6, passes sequentially through the first resonant inductor L3, the first rectifier circuit Rec3, the first resonant capacitor C3, the second resonant capacitor C4, the second rectifier circuit Rec4, the second resonant inductor L4, and then to the second upper chopper switch S7, returning to the first input terminal C1.

[0089] Compared to mode 1, the current in the resonant cavity continues to flow, and the direction remains unchanged.

[0090] Mode 3:

[0091] The first upper chopper switch S5 is off, the second lower chopper switch S8 is off, the first lower chopper switch S6 is on, and the second upper chopper switch S7 is on. Figure 10 As shown, the current loop starts from the first input terminal C1, passes through the second upper chopper switch S7, the second resonant inductor L4, the second rectifier circuit Rec4, the second resonant capacitor C4, the first resonant capacitor C3, the first rectifier circuit Rec3, the first resonant inductor L3, then to the first lower chopper switch S6, and finally returns to the second input terminal C2.

[0092] Since the current in mode 2 flows through the body diodes of the first lower chopper switch and the second upper chopper switch, mode 3 is entered at this time, and the switching devices achieve zero voltage turn-on (ZVS).

[0093] Mode 4:

[0094] The first upper chopper switch S5 is off, the second lower chopper switch S8 is off, the first lower chopper switch S6 is on, and the second upper chopper switch S7 is on. Figure 11As shown, the current is switched to the second lower chopping switch S8, sequentially passes through the second resonant inductor L4, the second rectifier circuit Rec4, the second resonant capacitor C4, the first resonant capacitor C3, the first rectifier circuit Rec3, the first resonant inductor L3, and then reaches the first upper chopping switch S5, and finally returns to the first input end C1.

[0095] Compared with mode 3, the current in the resonant cavity continues to flow, and the direction remains unchanged.

[0096] Through the analysis of the working modes of the circuit, in the four modes, the two resonant cavities are connected in series, and the current always flows through the first resonant cavity and the second resonant cavity at the same time. In this way, it is ensured that the currents of the two resonant cavities are equal, and the currents rectified by the two LLC resonant circuits are also equal, thereby realizing complete current sharing of the two LLCs in parallel. The driving signals of the two LLC resonant circuits are cross-connected, so as to ensure that the working states of the two LLC resonant circuits are complementary and differ by 180 degrees, and the directions of the currents of the two LLCs are not conflicted.

[0097] The application inserts a conversion device between the switching devices and the resonant cavities of the two half-bridge LLC circuits. When the two half-bridge LLC circuits operate in parallel, the conversion device disconnects the switching devices and the resonant cavities, and connects the resonant cavities of the two half-bridge LLC circuits in series. The two driving signals are cross-connected, so that the working states of the two half-bridge LLC circuits are complementary and differ by 180 degrees, that is, when the upper switching device of the first half-bridge LLC circuit is turned on and the lower switching device is turned off, the lower switching device of the second half-bridge LLC circuit is turned on, and the upper switching device is turned off at the same time; when the upper switching device of the first half-bridge LLC circuit is turned off and the lower switching device is turned on, the lower switching device of the second half-bridge LLC circuit is turned off, and the upper switching device is turned on at the same time. Through the above steps, the state of the two half-bridge LLC circuits operating in parallel is changed. The resonant cavity current of each half-bridge LLC circuit passes through the resonant cavity of the other half-bridge LLC circuit. Through the change of the working state of the circuit, the currents of the two resonant cavities are forced to be equal, the rectified output currents of the two half-bridge LLC circuits are also equal, and the problem of complete current sharing of the two LLCs in parallel is solved.

[0098] Based on the same inventive concept, the embodiments of the application also provide an LLC resonant converter, which comprises any one of the LLC resonant conversion circuits described above. The implementation of the LLC resonant converter can refer to the implementation of the LLC resonant conversion circuit, and the repeated parts will not be described herein.

[0099] Those skilled in the art can make various modifications and variations to the application without departing from the spirit and scope of the application. Thus, if these modifications and variations of the application fall within the scope of the claims of the application and equivalent technologies thereof, the application also intends to include these modifications and variations.

Claims

1. An LLC resonant conversion circuit, characterized by, The circuit comprises an input end, a first half-bridge LLC circuit, a second half-bridge LLC circuit, an output end, a conversion device, a first driving end and a second driving end, wherein the first half-bridge LLC circuit and the second half-bridge LLC circuit are connected in parallel between the input end and the output end; the conversion device is connected with a first resonant cavity of the first half-bridge LLC circuit and a second resonant cavity of the second half-bridge LLC circuit respectively; The conversion device is configured to disconnect a path between a first lower clamp switch of the first half-bridge LLC circuit and the first resonant cavity, disconnect a path between a second lower clamp switch of the second half-bridge LLC circuit and the second resonant cavity, and connect the first resonant cavity and the second resonant cavity in series; The first driving end is connected with a control end of a first upper clamp switch of the first half-bridge LLC circuit and a control end of a second lower clamp switch of the second half-bridge LLC circuit; The second driving end is connected with the first lower clamp switch and a second upper clamp switch of the second half-bridge LLC circuit; The input end comprises a first input end and a second input end, and the LLC resonant conversion circuit comprises the following four working modes: Mode 1: the first upper clamp switch is turned on, the first lower clamp switch is turned off, the second upper clamp switch is turned off, and the second lower clamp switch is turned on, so that the current flows from the first input end, sequentially passes through the first upper clamp switch, a first resonant inductor of the first half-bridge LLC circuit, a first rectifier circuit of the first half-bridge LLC circuit, a first resonant capacitor of the first half-bridge LLC circuit, a second resonant capacitor of the second half-bridge LLC circuit, a second rectifier circuit of the second half-bridge LLC circuit, a second resonant inductor of the second half-bridge LLC circuit, the second lower clamp switch, and returns to the second input end; Mode 2: the first upper clamp switch is turned off, the second lower clamp switch is turned off, the first lower clamp switch is turned on, and the second upper clamp switch is turned on, so that the current switches to the first lower clamp switch, sequentially passes through the first resonant inductor, the first rectifier circuit, the first resonant capacitor, the second resonant capacitor, the second rectifier circuit, the second resonant inductor, and then reaches the second upper clamp switch, and finally returns to the first input end; Mode 3: The first upper clamp switch is turned off, the second lower clamp switch is turned off, the first lower clamp switch is turned on, and the second upper clamp switch is turned on, so that the current flows from the first input end, sequentially passes through the second upper clamp switch, the second resonant inductor, the second rectifier circuit, the second resonant capacitor, the first resonant capacitor, the first rectifier circuit, the first resonant inductor, and then reaches the first lower clamp switch, and finally returns to the second input end; Mode 4: The first upper chopper switch is off, the second lower chopper switch is off, the first lower chopper switch is on, and the second upper chopper switch is on, so that the current is switched to the second lower chopper switch, sequentially passes through the second resonant inductor, the second rectifier circuit, the second resonant capacitor, the first resonant capacitor, the first rectifier circuit, the first resonant inductor, and then reaches the first upper chopper switch, and finally returns to the first input end.

2. The circuit of claim 1, wherein, The input end includes a first input end and a second input end; the output end includes a first output end and a second output end. The first half-bridge LLC circuit includes the first upper chopper switch, the first lower chopper switch, a first resonant inductor, a first resonant capacitor, and a first rectifier circuit including a first isolation transformer, wherein the first resonant inductor and the first resonant capacitor are connected in series to form a first resonant cavity, a first end of the first upper chopper switch is connected to the first input end, a second end of the first upper chopper switch is connected to a first end of the first lower chopper switch and a first end of the first resonant cavity, a second end of the first resonant cavity is connected to a first end of the conversion device, a second end of the first lower chopper switch is connected to the second input end, a positive output end of the first rectifier circuit is connected to the first output end, and a negative output end of the first rectifier circuit is connected to the second output end; the second half-bridge LLC circuit includes the second upper chopper switch, the second lower chopper switch, a second resonant inductor, a second resonant capacitor, and a second rectifier circuit including a second isolation transformer, wherein the second resonant inductor and the second resonant capacitor are connected in series to form a second resonant cavity, a first end of the second upper chopper switch is connected to the first input end, a second end of the second upper chopper switch is connected to a first end of the second lower chopper switch and a first end of the second resonant cavity, a second end of the second resonant cavity is connected to a second end of the conversion device, a second end of the second lower chopper switch is connected to the second input end, a positive output end of the second rectifier circuit is connected to the second output end, and a negative output end of the second rectifier circuit is connected to the second output end.

3. The circuit of claim 2, wherein, The conversion device is a jumper; a first jumper port of the jumper serves as a first end of the conversion device, a second jumper port of the jumper serves as a second end of the conversion device, a third jumper port of the jumper is connected to a second end of the first lower chopper switch, and a fourth jumper port of the jumper is connected to a second end of the second lower chopper switch, wherein a first jumper is connected between the first jumper port and the second jumper port.

4. The circuit of claim 3, wherein, The first jumper is not connected between the first jumper port and the second jumper port, the second jumper is connected between the first jumper port and the third jumper port, and the third jumper is connected between the second jumper port and the fourth jumper port, so that a path between the first lower chopper switch and the first resonant cavity is turned on, a path between the second lower chopper switch and the second resonant cavity is turned on, and a path between the first resonant cavity and the second resonant cavity is turned off.

5. The circuit of claim 2, wherein, The conversion device is a first single-pole double-throw switch and a second single-pole double-throw switch; a fixed contact of the first single-pole double-throw switch is a first end of the conversion device, a first moving contact of the first single-pole double-throw switch is connected with a second end of the first lower chopper switch, and a second moving contact of the first single-pole double-throw switch is connected with a second moving contact of the second single-pole double-throw switch. A fixed contact of the second single-pole double-throw switch is a second end of the conversion device, and a first moving contact of the second single-pole double-throw switch is connected with a second end of the second lower chopper switch.

6. The circuit of claim 5, wherein, The fixed contact of the first single-pole double-throw switch is connected with the second moving contact of the first single-pole double-throw switch, and the fixed contact of the second single-pole double-throw switch is connected with the second moving contact of the second single-pole double-throw switch.

7. The circuit of claim 2, wherein, The conversion device is a connecting line; a first end of the connecting line is a first end of the conversion device, and a second end of the connecting line is a second end of the conversion device.

8. The circuit of claim 2, wherein, One end of the first resonant inductor is a first end of the first resonant cavity, and one end of the first resonant capacitor is a second end of the first resonant cavity; one end of the second resonant inductor is a first end of the second resonant cavity, and one end of the second resonant capacitor is a second end of the second resonant cavity.

9. A circuit as claimed in any one of claims 2 to 8, wherein, The first rectifier circuit and the second rectifier circuit are both full-bridge rectifier circuits; or the first rectifier circuit and the second rectifier circuit are both full-wave rectifier circuits.

10. An LLC resonant converter, characterized by, The LLC resonant conversion circuit comprises the LLC resonant conversion circuit according to any one of claims 1-9. The LLC resonant conversion circuit comprises the LLC resonant conversion circuit according to any one of claims 1-9.

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