LLC conversion circuit, three-interleaved LLC converter and charging device

Abstract

This invention provides an LLC converter circuit, a three-interleaved LLC converter, and a charging device, relating to the field of power electronics technology. The LLC converter circuit includes a half-bridge resonant unit, a first transformer, a second transformer, a three-phase rectifier bridge, a first dual-path synchronous switching unit, and a second dual-path synchronous switching unit; both switches in the first and second dual-path synchronous switching units are simultaneously turned on and off. This invention achieves variation in the number of turns in the secondary winding through synchronous on / off control of the dual-path synchronous switching units; simultaneously, through the drive adjustment of the dual-path half-bridge resonant units, it achieves synchronous drive + interleaved drive mode switching, realizing a 2:1 gain variation; the primary and secondary sides cooperate to achieve multi-level adjustable gain, enabling wide-range output and high efficiency.

Description

Technical Field

[0001] This invention relates to the field of power electronics technology, and in particular to an LLC converter circuit, a triple-interleaved LLC converter, and a charging device. Background Technology

[0002] With increasing environmental awareness and the global pursuit of sustainable energy, the new energy vehicle industry has experienced rapid development. Electric vehicles, as a crucial component of new energy vehicles, are seeing rapid growth in their ownership, and the demand for them is also increasing. Charging stations, as essential supporting infrastructure for electric vehicles, directly influence the charging time, cost, and reliability of their core components, specifically the charging module. Currently, the ultra-wide constant power output range is a major design challenge in charging module technology: when designing charging modules with wide output voltage, satisfying both a wide output voltage range and constant power requirements, constant power across the entire voltage range results in extremely high current at low voltage output, creating an "efficiency bottleneck."

[0003] In existing technologies, traditional LLC power modules relying on frequency modulation have advantages such as high gain linearity and high system efficiency near the resonant frequency, enabling constant power output within the resonant range. However, when the power module operates over a wide voltage output range, the system typically operates at very high switching frequencies. This leads to a deterioration in the resonant current waveform, increased core and winding losses, and increased switching turn-off losses, all of which negatively impact the power module's efficiency and performance. Summary of the Invention

[0004] This invention provides an LLC converter circuit, a triple-interleaved LLC converter, and a charging device to solve the problems in the prior art.

[0005] In a first aspect, embodiments of the present invention provide an LLC converter circuit, comprising: a first half-bridge resonant unit, a second half-bridge resonant unit, a first transformer, a second transformer, a three-phase rectifier bridge, a first dual-channel synchronous switching unit, and a second dual-channel synchronous switching unit; The primary winding of the first transformer is connected to the resonant branch in the first half-bridge resonant unit, the first end of the secondary winding of the first transformer is connected to the first input end of the three-phase rectifier bridge, the second end of the secondary winding of the first transformer is connected to the first end of the second dual-path synchronous switching unit, and the center tap of the secondary winding of the first transformer is connected to the first end of the first dual-path synchronous switching unit. The primary winding of the second transformer is connected to the resonant branch in the second half-bridge resonant unit, the first end of the secondary winding of the second transformer is connected to the second end of the second dual-path synchronous switching unit, the second end of the secondary winding of the second transformer is connected to the second input end of the three-phase rectifier bridge, and the center tap of the secondary winding of the second transformer is connected to the second end of the first dual-path synchronous switching unit. The common terminal of the first dual-channel synchronous switching unit and the common terminal of the second dual-channel synchronous switching unit are both connected to the third input terminal of the three-phase rectifier bridge. Both the first half-bridge resonant unit and the second half-bridge resonant unit are powered by DC power. The first dual-path synchronous switching unit is used to: control the center tap of the secondary winding of the second transformer and the center tap of the secondary winding of the first transformer to be connected to the third input terminal of the three-phase rectifier bridge; or control the center tap of the secondary winding of the second transformer to be disconnected from the center tap of the secondary winding of the first transformer and the third input terminal of the three-phase rectifier bridge. The second dual-path synchronous switching unit is used to: control the second end of the secondary winding of the first transformer and the first end of the secondary winding of the second transformer to be connected to the third input terminal of the three-phase rectifier bridge; or control the second end of the secondary winding of the first transformer to be disconnected from the first end of the secondary winding of the second transformer and the third input terminal of the three-phase rectifier bridge.

[0006] Optionally, the first dual-channel synchronous switching unit includes: a double-pole single-throw relay; The normally open contacts of the first set of switches in the double-pole single-throw relay form the first end of the first dual-channel synchronous switching unit; The normally open contacts of the second set of switches in the double-pole single-throw relay form the second end of the first dual-channel synchronous switching unit; The common terminal of the first set of switches in the double-pole single-throw relay is connected to the common terminal of the second set of switches in the double-pole single-throw relay to form the common terminal of the first dual-channel synchronous switching unit.

[0007] Optionally, the above circuit may also include: a positive bus capacitor and a negative bus capacitor; The positive bus capacitor and the negative bus capacitor are connected in series between the positive DC bus and the negative DC bus.

[0008] Optionally, the first half-bridge resonant unit includes: a first half-bridge inverter sub-unit and a first resonant branch; The first end of the first resonant branch is connected to the output end of the first half-bridge inverter subunit, and the second end of the first resonant branch is connected to the first end of the primary winding of the first transformer. The second end of the primary winding of the first transformer is connected to the second input end of the first half-bridge inverter subunit; the first input end and the second input end of the first half-bridge inverter subunit are respectively used to connect to the positive and negative terminals of the DC power supply. The second half-bridge resonant unit includes: a second half-bridge inverter subunit and a second resonant branch; The first end of the second resonant branch is connected to the output end of the second half-bridge inverter subunit, and the second end of the second resonant branch is connected to the first end of the primary winding of the second transformer. The second end of the primary winding of the second transformer is connected to the second input end of the second half-bridge inverter subunit; the first input end of the second half-bridge inverter subunit is connected to the first input end of the first half-bridge inverter subunit, and the second input end of the second half-bridge inverter subunit is connected to the second input end of the first half-bridge inverter subunit.

[0009] Optionally, the first half-bridge inverter subunit may include: a first switch and a second switch; The first terminal of the first switch forms the first input terminal of the first half-bridge inverter subunit; the second terminal of the first switch is connected to the first terminal of the second switch to form the output terminal of the first half-bridge inverter subunit; the second terminal of the second switch forms the second input terminal of the first half-bridge inverter subunit. The second half-bridge inverter subunit includes: a third switch and a fourth switch; The first terminal of the third switch forms the first input terminal of the second half-bridge inverter subunit; the second terminal of the third switch is connected to the first terminal of the fourth switch to form the output terminal of the second half-bridge inverter subunit; the second terminal of the fourth switch forms the second input terminal of the second half-bridge inverter subunit. Among them, the first switch and the second switch are not turned on at the same time, and the third switch and the fourth switch are turned on at the same time.

[0010] Optionally, the above circuit may also include: a main control unit; The main control unit is used to: control the synchronization of the first and third switching transistors; control the first dual-path synchronous switching unit to connect both the center tap of the secondary winding of the second transformer and the center tap of the secondary winding of the first transformer to the third input terminal of the three-phase rectifier bridge; and control the second dual-path synchronous switching unit to disconnect the second end of the secondary winding of the first transformer from both the first end of the secondary winding of the second transformer and the third input terminal of the three-phase rectifier bridge; or The first and third switching transistors are synchronized; the first dual-path synchronous switching unit is controlled so that the center tap of the secondary winding of the second transformer is not connected to the center tap of the secondary winding of the first transformer or the third input terminal of the three-phase rectifier bridge; and the second dual-path synchronous switching unit is controlled so that the second end of the secondary winding of the first transformer and the first end of the secondary winding of the second transformer are both connected to the third input terminal of the three-phase rectifier bridge; or Control the first and third switching transistors to operate asynchronously; control the first dual-path synchronous switching unit to connect both the center tap of the secondary winding of the second transformer and the center tap of the secondary winding of the first transformer to the third input terminal of the three-phase rectifier bridge; and control the second dual-path synchronous switching unit to disconnect the second end of the secondary winding of the first transformer from both the first end of the secondary winding of the second transformer and the third input terminal of the three-phase rectifier bridge; or The first and third switching transistors are controlled to operate asynchronously; the first dual-path synchronous switching unit is controlled so that the center tap of the secondary winding of the second transformer is not connected to the center tap of the secondary winding of the first transformer or the third input terminal of the three-phase rectifier bridge; and the second dual-path synchronous switching unit is controlled so that the second end of the secondary winding of the first transformer and the first end of the secondary winding of the second transformer are both connected to the third input terminal of the three-phase rectifier bridge.

[0011] Optionally, the turns ratio of the two windings of the secondary winding of the first transformer and the turns ratio of the two windings of the secondary winding of the second transformer are both 3:1.

[0012] Optionally, the three-phase rectifier bridge includes: a first diode, a second diode, a third diode, a fourth diode, a fifth diode, and a sixth diode; The anode of the first diode is connected to the cathode of the second diode to form the first input terminal of the three-phase rectifier bridge. The cathode of the first diode is connected to the positive DC bus, and the anode of the second diode is connected to the negative DC bus. The anode of the third diode is connected to the cathode of the fourth diode to form the third input terminal of the three-phase rectifier bridge. The cathode of the third diode is connected to the positive DC bus, and the anode of the fourth diode is connected to the negative DC bus. The anode of the fifth diode is connected to the cathode of the sixth diode to form the second input terminal of the three-phase rectifier bridge. The cathode of the fifth diode is connected to the positive DC bus, and the anode of the sixth diode is connected to the negative DC bus. The positive DC bus and negative DC bus are used to connect to the load.

[0013] In a second aspect, embodiments of the present invention also provide a three-interleaved LLC converter, comprising: three LLC converter circuits as provided in the first aspect embodiments above; The half-bridge resonant units in the three LLC converter circuits are all connected to the DC power supply, and the three-phase rectifier bridges in the three LLC converter circuits are all connected to the load. The primary winding of the first transformer in the three LLC converter circuits is connected in a star configuration, and the primary winding of the second transformer in the three LLC converter circuits is connected in a star configuration.

[0014] Thirdly, embodiments of the present invention also provide a charging device, including the triple-interleaved LLC converter as provided in the second aspect embodiment above.

[0015] This invention provides an LLC converter circuit, a three-interleaved LLC converter, and a charging device. The LLC converter circuit includes: a first half-bridge resonant unit, a second half-bridge resonant unit, a first transformer, a second transformer, a three-phase rectifier bridge, a first dual-path synchronous switching unit, and a second dual-path synchronous switching unit. The primary winding of the first transformer is connected to the resonant branch of the first half-bridge resonant unit; the first end of the secondary winding of the first transformer is connected to the first input terminal of the three-phase rectifier bridge; the second end of the secondary winding of the first transformer is connected to the first end of the second dual-path synchronous switching unit; and the center tap of the secondary winding of the first transformer is connected to the first end of the first dual-path synchronous switching unit. The primary winding of the second transformer is connected to the resonant branch of the second half-bridge resonant unit; the first end of the secondary winding of the second transformer is connected to the second end of the second dual-path synchronous switching unit; the second end of the secondary winding of the second transformer is connected to the second input terminal of the three-phase rectifier bridge; and the center tap of the secondary winding of the second transformer is connected to the first dual-path synchronous switching unit. The second end of the unit is connected; the common end of the first dual-channel synchronous switching unit and the common end of the second dual-channel synchronous switching unit are both connected to the third input end of the three-phase rectifier bridge; the first half-bridge resonant unit and the second half-bridge resonant unit are both powered by DC power supply; wherein, the first dual-channel synchronous switching unit is used to: control the center tap of the secondary winding of the second transformer and the center tap of the secondary winding of the first transformer to be connected to the third input end of the three-phase rectifier bridge; or control the center tap of the secondary winding of the second transformer to be disconnected from the center tap of the secondary winding of the first transformer and the third input end of the three-phase rectifier bridge; the second dual-channel synchronous switching unit is used to: control the second end of the secondary winding of the first transformer and the first end of the secondary winding of the second transformer to be connected to the third input end of the three-phase rectifier bridge; or control the second end of the secondary winding of the first transformer to be disconnected from the first end of the secondary winding of the second transformer and the third input end of the three-phase rectifier bridge. This application employs two half-bridge resonant units. When the control signals of the two half-bridge resonant units are synchronized, it operates in synchronous drive mode, forming two independent half-bridge LLCs. In this mode, the two transformers function as if connected in series. When the control signals of the two half-bridge resonant units are asynchronous, it operates in interleaved drive mode, with the phases interleaved by 180°, forming a near-full-bridge LLC. In this mode, the two transformers function as if connected in parallel. Thus, without changing the hardware connections, a continuous gain adjustment range of approximately 2:1 is achieved, resulting in good system dynamic response and facilitating efficiency optimization under light loads. The secondary side uses a first dual-channel synchronous switching unit and a second dual-channel synchronous switching unit to change the number of turns in the effectively operating secondary winding, thereby achieving a step change in gain. The primary and secondary sides work together to generate four discrete gain values, ensuring that each operating range operates at its optimal state, improving circuit performance and reducing losses. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the circuit structure of an LLC converter circuit provided in an embodiment of the present invention; Figure 2 yes Figure 1 A schematic diagram of an equivalent circuit structure of the LLC converter circuit shown; Figure 3 yes Figure 1 A schematic diagram of another equivalent circuit structure of the LLC converter circuit shown. Figure 4 This is a schematic diagram of the circuit structure of a triple-interleaved LLC converter provided in an embodiment of the present invention; Figure 5 yes Figure 4 The diagram shows an equivalent circuit structure of a triple-interleaved LLC converter. Figure 6 yes Figure 4 The diagram shows another equivalent circuit structure of the triple-interleaved LLC converter. Figure 7 yes Figure 4 The diagram shows the third equivalent circuit structure of the triple-interleaved LLC converter. Figure 8 yes Figure 4 The diagram shows the fourth equivalent circuit structure of the triple-interleaved LLC converter. Detailed Implementation

[0017] 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 with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this solution, not all of them. Based on the embodiments of this solution, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this solution.

[0018] The term "comprising" and any other variations thereof in the specification, claims, and accompanying drawings of this invention mean "including but not limited to," and are intended to cover a non-exclusive inclusion, not limited to the examples listed herein. Furthermore, the terms "first" and "second," etc., are used to distinguish different objects, not to describe a specific order.

[0019] The implementation of the present invention will be described in detail below with reference to the accompanying drawings: Figure 1 This is a schematic diagram of an LLC converter circuit provided in an embodiment of the present invention. (Refer to...) Figure 1The LLC converter circuit includes: a first half-bridge resonant unit 11, a second half-bridge resonant unit 12, a first transformer (H1T1), a second transformer (H2T1), a three-phase rectifier bridge 13, a first dual-channel synchronous switching unit 14, and a second dual-channel synchronous switching unit 15. The primary winding of the first transformer (H1T1) is connected to the resonant branch in the first half-bridge resonant unit 11. The first end of the secondary winding of the first transformer (H1T1) is connected to the first input end of the three-phase rectifier bridge 13. The second end of the secondary winding of the first transformer (H1T1) is connected to the first end of the second dual-path synchronous switching unit 15. The center tap of the secondary winding of the first transformer (H1T1) is connected to the first end of the first dual-path synchronous switching unit 14. The primary winding of the second transformer (H2T1) is connected to the resonant branch in the second half-bridge resonant unit 12. The first end of the secondary winding of the second transformer (H2T1) is connected to the second end of the second dual-path synchronous switching unit 15. The second end of the secondary winding of the second transformer (H2T1) is connected to the second input end of the three-phase rectifier bridge 13. The center tap of the secondary winding of the second transformer (H2T1) is connected to the second end of the first dual-path synchronous switching unit 14. The common terminal of the first dual-channel synchronous switching unit 14 and the common terminal of the second dual-channel synchronous switching unit 15 are both connected to the third input terminal of the three-phase rectifier bridge 13. Both the first half-bridge resonant unit 11 and the second half-bridge resonant unit 12 are powered by DC power supply Vin. The first dual-path synchronous switching unit 14 is used to: control the center tap of the secondary winding of the second transformer (H2T1) and the center tap of the secondary winding of the first transformer (H1T1) to be connected to the third input terminal of the three-phase rectifier bridge 13; or control the center tap of the secondary winding of the second transformer (H2T1) to be disconnected from both the center tap of the secondary winding of the first transformer (H1T1) and the third input terminal of the three-phase rectifier bridge 13. The second dual-path synchronous switching unit 15 is used to: control the second end of the secondary winding of the first transformer (H1T1) and the first end of the secondary winding of the second transformer (H2T1) to be connected to the third input terminal of the three-phase rectifier bridge 13; or control the second end of the secondary winding of the first transformer (H1T1) to be disconnected from the first end of the secondary winding of the second transformer (H2T1) and the third input terminal of the three-phase rectifier bridge 13.

[0020] refer to Figure 1 This application adopts a coordinated control mechanism of primary-side driven phase control + secondary-side switch state switching. Through the combination of two sets of independent adjustment dimensions, four-segment discrete gain adjustment is achieved, dividing the ultra-wide output voltage range into four narrow gain intervals, so that the LLC resonant cavity can operate in the high-efficiency range near the resonant frequency throughout the entire operating range.

[0021] I. First Dimension This application sets up two half-bridge resonant units (first half-bridge resonant unit 11 and second half-bridge resonant unit 12). The two half-bridge resonant units are synchronously powered by DC power supply Vin, and the working mode can be switched by the phase configuration of the drive signal.

[0022] Synchronous drive mode: The drive signals of the two half-bridge resonant units are output in phase, and the two half-bridge resonant units form two independent half-bridge LLCs that work synchronously. At this time, the induced voltages of the secondary windings of the two transformers (H1T1 and H2T1) are in phase, the secondary windings work in series rectification mode, the equivalent turns ratio is the smallest, the circuit gain is the highest, and the gain is Kn*M.

[0023] Interleaved drive mode: The drive signals of the two half-bridge resonant units are output with a 180° phase interleaving. The resonant cavities in the two half-bridge resonant units operate asynchronously. The induced voltages of the secondary windings of the two transformers (H1T1 and H2T1) are out of phase, and the secondary windings operate in parallel rectification mode. The equivalent turns ratio is twice that of synchronous drive mode, and the circuit gain is half that of synchronous drive mode, achieving a 2:1 gain reduction. Kn*M.

[0024] Therefore, by configuring the phase of the driving signals of the first half-bridge resonant unit 11 and the second half-bridge resonant unit 12 on the primary side, the switching of the secondary side rectification mode can be achieved without changing the hardware topology, corresponding to a 2:1 gain change.

[0025] II. Second Dimension This application sets up a first dual-channel synchronous switching unit 14 and a second dual-channel synchronous switching unit 15. The number of winding turns is adjusted by switching between the two dual-channel synchronous switching units, thereby completing the step gain adjustment.

[0026] Partial winding pattern: Figure 2 It shows Figure 1 The diagram shows the equivalent circuit of the LLC converter circuit in partial winding mode. The first dual-path synchronous switching unit 14 is closed, and the center taps of the secondary windings of the second transformer (H2T1) and the first transformer (H1T1) are both connected to the third input terminal of the three-phase rectifier bridge 13. The second dual-path synchronous switching unit 15 is open (the second end of the secondary winding of the first transformer (H1T1) is not connected to the first end of the secondary winding of the second transformer (H2T1) or the third input terminal of the three-phase rectifier bridge 13). The secondary windings of both transformers are partially connected, the primary-secondary turns ratio of the transformers is less than 1, and the secondary windings of the two transformers are connected in series for full-bridge rectification. For example, if the turns ratio of the two windings of the secondary winding of the first transformer (H1T1) and the turns ratio of the two windings of the secondary winding of the second transformer (H2T1) are both 3:1, and the total number of turns is 8, then the gain is reduced to 6 / 8 of the full winding mode.

[0027] Full winding mode: Figure 3 It shows Figure 1 The equivalent circuit diagram of the LLC converter circuit in full-winding mode is shown. The first dual-channel synchronous switching unit 14 is open (the center tap of the secondary winding of the second transformer (H2T1) is not connected to the center tap of the secondary winding of the first transformer (H1T1) or the third input terminal of the three-phase rectifier bridge 13), and the second dual-channel synchronous switching unit 15 is closed (the second end of the secondary winding of the first transformer (H1T1) and the first end of the secondary winding of the second transformer (H2T1) are both connected to the third input terminal of the three-phase rectifier bridge 13). The secondary windings of both transformers are fully connected, the primary-secondary transformation ratio of the transformers is 1, and the secondary windings of the two transformers are connected in series for full-bridge rectification, achieving a gain change of 1.

[0028] By organically combining the adjustment methods of the two dimensions mentioned above, four stable operating modes can be formed. Taking the turns ratio of the two windings of the secondary winding of the first transformer (H1T1) and the turns ratio of the two windings of the secondary winding of the second transformer (H2T1) as 3:1, with a total of 8 turns, four gain modes of 8, 6, 4, and 3 are formed, dividing the ultra-wide output voltage range (such as 200V-1000V) into four relatively narrow gain intervals.

[0029] Gain 8 mode (1000V-750V) Primary-side synchronous drive, first dual-channel synchronous switching unit 14 is disconnected, second dual-channel synchronous switching unit 15 is closed, reference Figure 3 The two transformers have complete 8-turn windings connected in series, resulting in a total equivalent secondary winding count of 16 turns. A three-phase rectifier bridge of 13 rectifies the total induced voltage of the series windings, with a circuit gain of Kn*M. At this point, the circuit operates near its resonant frequency, achieving maximum voltage output without high-frequency offset and minimizing switching losses.

[0030] Gain 6 mode (750V-500V) Primary-side synchronous drive: the first dual-path synchronous switching unit 14 is closed, the second dual-path synchronous switching unit 15 is open, and the center taps of the secondary windings of the two transformers are connected to the rectifier circuit. (Reference) Figure 2 The effective number of winding turns was changed from 8 turns to 6 turns, the equivalent total number of secondary turns was 12 turns, and the circuit gain was... Kn*M achieves a 4:3 gain reduction. It adapts to the medium-to-high voltage output range without altering the primary-side operating frequency, simply by switching the switches, while fully preserving the soft-switching characteristics.

[0031] Gain 4 mode (500V-375V) The primary side is driven in a 180° staggered manner. The first dual-path synchronous switching unit 14 is disconnected, and the second dual-path synchronous switching unit 15 is closed. (Reference) Figure 3 The two transformers' complete 8-turn windings form a parallel structure with the third input terminal of the three-phase rectifier bridge 13 as the common point, with an equivalent secondary winding of 8 turns. The primary windings are interleaved, the two LLC circuits operate asynchronously, and the induced voltages on the secondary windings are in opposite phases, adapting to the parallel rectification mode. The circuit gain is [value missing]. Kn*M achieves a 2:1 gain reduction. Phase switching via primary-side drive adapts to low-voltage outputs, avoiding the extreme high-frequency operation of existing LLC low-voltage outputs and significantly reducing switching losses.

[0032] Gain 3 mode (375V-250V) The primary windings are driven in a 180° staggered manner. The first dual-path synchronous switching unit 14 is closed, and the second dual-path synchronous switching unit 15 is open. The parallel structure is maintained, and the center taps of the secondary windings of the two transformers are connected to the rectifier circuit. (Refer to...) Figure 2 The effective number of winding turns is switched to 6 turns, the equivalent number of secondary turns is 6 turns, and the circuit gain is... Kn*M achieves maximum gain reduction. Through coordinated switching of the primary and secondary sides, the circuit still operates in the high-efficiency range near the resonant frequency when outputting low voltage and high current, completely solving the low-voltage "efficiency depression" problem of traditional solutions.

[0033] In summary, this application achieves an ultra-wide gain regulation ratio of 8:3 through the coordinated control of primary-side drive phase switching and secondary-side winding turns switching, covering an ultra-wide output voltage range of 250V~1000V. This perfectly meets the market demand for full-voltage constant power output of new energy vehicle charging modules, eliminating the need for additional power conversion stages and significantly simplifying the system topology.

[0034] The two-dimensional gain adjustment design breaks down the total gain requirement into two smaller, easily implemented gain adjustment steps (2:1 and 4:3), dividing the system into four narrow gain ranges. Optimization is only needed for any one of these ranges (e.g., 1000V-750V), enabling constant power output across the entire 250V to 1000V range through mode switching. Furthermore, within each operating range, only a minimal frequency offset is required to adjust the output voltage, ensuring the resonant cavity always operates in the high-efficiency "golden region" near its resonant frequency. Compared to existing technologies, this application completely solves the "efficiency depression" problem caused by excessively high switching frequencies, soaring core and winding losses, and a sharp drop in efficiency during low-voltage, high-current output, achieving maximum weighted average efficiency and power density across the entire output voltage range.

[0035] Meanwhile, the four-segment gain division significantly reduces the maximum voltage stress on the secondary rectifier tube and filter capacitor in the high-voltage output range, avoiding the problem of devices bearing extreme voltage stress for a long time in the high-voltage mode of the traditional solution; on the other hand, in the low-voltage output range, the equivalent turns ratio is reduced by gain switching, which significantly reduces the current stress on the secondary winding and reduces conduction losses.

[0036] In one possible implementation, refer to Figure 1 The first dual-channel synchronous switching unit 14 includes: a double-pole single-throw relay; The normally open contacts of the first set of switches in the double-pole single-throw relay form the first terminal of the first dual-channel synchronous switching unit 14; The normally open contacts of the second set of switches in the double-pole single-throw relay form the second end of the first dual-channel synchronous switching unit 14; The common terminal of the first set of switches in the double-pole single-throw relay is connected to the common terminal of the second set of switches in the double-pole single-throw relay to form the common terminal of the first dual-channel synchronous switching unit 14.

[0037] This application utilizes the structural characteristics of a double-pole single-throw relay, which features synchronous operation, electrical isolation, and a combined common terminal for two sets of switches, to achieve on / off control of the center tap of the secondary winding of a transformer.

[0038] Relay energization (normally open contact closure): Two sets of switches are simultaneously turned on, and the center taps of the secondary windings of the first and second transformers are simultaneously connected to the third input terminal of the three-phase rectifier bridge 13. The effective number of turns of the secondary winding of the transformer is switched from 8 turns to 6 turns, and the length of the winding participating in rectification is shortened. Relay disconnection (normally open contact disconnection): Both sets of switches are turned off synchronously, the center taps of the secondary windings of the two transformers are not connected to the rectifier circuit, all 8 turns of the secondary winding participate in rectification, and the equivalent number of turns remains unchanged.

[0039] This application uses only two relays to switch the effective number of turns on the secondary side of the transformer, reducing the number of components and control complexity. Simultaneously, the two sets of switches on the double-pole single-throw relay are driven by the same coil, ensuring completely synchronized operation with no phase difference. This guarantees that the center taps on both secondary sides of the transformer are connected / disconnected simultaneously, avoiding problems such as winding asymmetry, rectification imbalance, and uneven voltage stress caused by single-sided connection, thus improving operational stability.

[0040] In one possible implementation, refer to Figure 1 The circuit also includes: positive bus capacitor CD1 and negative bus capacitor CD2; The positive bus capacitor CD1 and the negative bus capacitor CD2 are connected in series between the positive DC bus and the negative DC bus.

[0041] The positive bus capacitor CD1 and the negative bus capacitor CD2 are connected in series for filtering.

[0042] In one possible implementation, the first half-bridge resonant unit 11 may include: a first half-bridge inverter subunit 111 and a first resonant branch 112; The first end of the first resonant branch 112 is connected to the output end of the first half-bridge inverter subunit 111, and the second end of the first resonant branch 112 is connected to the first end of the primary winding of the first transformer (H1T1). The second end of the primary winding of the first transformer (H1T1) is connected to the second input end of the first half-bridge inverter subunit 111; the first input end and the second input end of the first half-bridge inverter subunit 111 are respectively used to connect to the positive and negative terminals of the DC power supply Vin. The second half-bridge resonant unit 12 may include: a second half-bridge inverter subunit 121 and a second resonant branch 122; The first end of the second resonant branch 122 is connected to the output end of the second half-bridge inverter subunit 121, and the second end of the second resonant branch 122 is connected to the first end of the primary winding of the second transformer (H2T1). The second end of the primary winding of the second transformer (H2T1) is connected to the second input end of the second half-bridge inverter subunit 121; the first input end of the second half-bridge inverter subunit 121 is connected to the first input end of the first half-bridge inverter subunit 111, and the second input end of the second half-bridge inverter subunit 121 is connected to the second input end of the first half-bridge inverter subunit 111.

[0043] Two half-bridge inverter sub-units invert the DC power input Vin into high-frequency AC excitation and send it to the corresponding resonant branch. Each resonant branch and the primary winding of the corresponding transformer together form an independent LLC resonant cavity.

[0044] In one possible implementation, the first half-bridge inverter subunit 111 may include a first switch (H1_mos1) and a second switch (H1_mos2). The first terminal of the first switch (H1_mos1) forms the first input terminal of the first half-bridge inverter sub-unit 111; the second terminal of the first switch (H1_mos1) is connected to the first terminal of the second switch (H1_mos2) to form the output terminal of the first half-bridge inverter sub-unit 111; the second terminal of the second switch (H1_mos2) forms the second input terminal of the first half-bridge inverter sub-unit 111. The second half-bridge inverter subunit 121 includes: a third switch (H2_mos1) and a fourth switch (H2_mos2); The first terminal of the third switch (H2_mos1) forms the first input terminal of the second half-bridge inverter sub-unit 121; the second terminal of the third switch (H2_mos1) is connected to the first terminal of the fourth switch (H2_mos2) to form the output terminal of the second half-bridge inverter sub-unit 121; the second terminal of the fourth switch (H2_mos2) forms the second input terminal of the second half-bridge inverter sub-unit 121. Among them, the first switch (H1_mos1) and the second switch (H1_mos2) are not turned on at the same time, and the third switch (H2_mos1) and the fourth switch (H2_mos2) are not turned on at the same time.

[0045] refer to Figure 1 The first half-bridge inverter subunit 111 and the second half-bridge inverter subunit 121 can both be composed of two switching transistors. The upper and lower switching transistors are turned on alternately to chop the fixed DC voltage into high-frequency AC power and send it into the resonant cavity.

[0046] In synchronous drive mode, the drive signals of the first switch (H1_mos1) and the third switch (H2_mos1) are synchronized, and the drive signals of the second switch (H1_mos2) and the fourth switch (H2_mos2) are synchronized; in interleaved drive mode, the drive signals of the first switch (H1_mos1) and the fourth switch (H2_mos2) are synchronized, and the drive signals of the second switch (H1_mos2) and the third switch (H2_mos1) are synchronized.

[0047] refer to Figure 1 The first resonant branch 112 and the second resonant branch 122 form resonant cavities with the first transformer and the second transformer, respectively (H1Cr1 and H1Lr1 correspond to H1T1, and H2Cr1 and H2Lr1 correspond to H2T1). For details, refer to [reference needed]. Figure 1 This will not be elaborated upon here.

[0048] In one possible implementation, refer to Figures 1-3 The circuit described above may further include: a main control unit; The main control unit is used to: synchronize the first switching transistor (H1_mos1) and the third switching transistor (H2_mos1); control the first dual-channel synchronous switching unit 14 to connect both the center tap of the secondary winding of the second transformer (H2T1) and the center tap of the secondary winding of the first transformer (H1T1) to the third input terminal of the three-phase rectifier bridge 13; and control the second dual-channel synchronous switching unit 15 to disconnect the second terminal of the secondary winding of the first transformer (H1T1) from the first terminal of the secondary winding of the second transformer (H2T1) and the third input terminal of the three-phase rectifier bridge 13; or The first switching transistor (H1_mos1) and the third switching transistor (H2_mos1) are synchronized; the first dual-channel synchronous switching unit 14 is controlled so that the center tap of the secondary winding of the second transformer (H2T1) is not connected to the center tap of the secondary winding of the first transformer (H1T1) or the third input terminal of the three-phase rectifier bridge 13; and the second dual-channel synchronous switching unit 15 is controlled so that the second end of the secondary winding of the first transformer (H1T1) and the first end of the secondary winding of the second transformer (H2T1) are both connected to the third input terminal of the three-phase rectifier bridge 13; or The first switch (H1_mos1) and the third switch (H2_mos1) are controlled to operate asynchronously; the first dual-channel synchronous switching unit 14 is controlled to connect the center tap of the secondary winding of the second transformer (H2T1) and the center tap of the secondary winding of the first transformer (H1T1) to the third input terminal of the three-phase rectifier bridge 13; and the second dual-channel synchronous switching unit 15 is controlled to disconnect the second end of the secondary winding of the first transformer (H1T1) from the first end of the secondary winding of the second transformer (H2T1) and the third input terminal of the three-phase rectifier bridge 13; or The first switch (H1_mos1) and the third switch (H2_mos1) are controlled to be asynchronous; the first dual-channel synchronous switching unit 14 is controlled so that the center tap of the secondary winding of the second transformer (H2T1) is not connected to the center tap of the secondary winding of the first transformer (H1T1) or the third input terminal of the three-phase rectifier bridge 13; and the second dual-channel synchronous switching unit 15 is controlled so that the second end of the secondary winding of the first transformer (H1T1) and the first end of the secondary winding of the second transformer (H2T1) are both connected to the third input terminal of the three-phase rectifier bridge 13.

[0049] This application achieves precise switching between four fixed operating modes through a two-dimensional coordinated scheduling of primary-side switch-driven phase control and secondary-side dual-path synchronous switch unit on / off control. The corresponding circuits include four-segment discrete gain adjustment (8, 6, 4, 3 segments), and the specific working principle is the same as described above, so it will not be repeated here. By switching modes, the ultra-wide output voltage range is divided into four narrow gain intervals, ensuring that the LLC resonant cavity operates in the optimal soft-switching range near the resonant frequency under all operating conditions.

[0050] In one possible implementation, the turns ratio of the two windings of the secondary winding of the first transformer and the turns ratio of the two windings of the secondary winding of the second transformer can both be 3:1.

[0051] In this application, the turns ratio of the two windings on the secondary side of the transformer is 3:1, which corresponds to a fixed step change of 4:3 in the equivalent turns ratio of the transformer. This perfectly coordinates with the 2:1 gain switching achieved by the synchronous / asynchronous drive on the primary side, realizing four discrete gain levels of 8, 6, 4, and 3. The gain range is evenly divided without blind spots, perfectly covering the ultra-wide output voltage range of 250V~1000V, solving the problem of traditional LLC wide-range gain adjustment relying on extreme frequency offset.

[0052] The 3:1 turns ratio enables bidirectional optimization of device stress under high and low voltage conditions: Under high voltage output conditions, connecting the full winding (4 turns) results in a smaller secondary winding current, significantly reducing the reverse recovery loss of the rectifier diode and the conduction loss of the winding; Under low voltage and high current conditions, connecting 3 turns results in fewer equivalent turns in the winding, greatly reducing the secondary current stress and conduction loss, perfectly adapting to the characteristics of low voltage and high current conditions.

[0053] Meanwhile, a 3:1 turns ratio can be achieved through continuous winding of the transformer bobbin, with precise center tap positioning. The coupling degree, leakage inductance, and DC resistance parameters of the two winding sections are highly consistent, and the secondary windings of the two transformers can achieve complete symmetrical matching. This avoids problems such as transformer magnetic saturation, circulating current between the two LLC resonant units, and rectification imbalance caused by winding parameter asymmetry from the hardware perspective.

[0054] In one possible implementation, refer to Figure 1 The three-phase rectifier bridge 13 includes: a first diode (S1_D1), a second diode (S1_D2), a third diode (S1_D3), a fourth diode (S1_D4), a fifth diode (S1_D5), and a sixth diode (S1_D6); The anode of the first diode (S1_D1) is connected to the cathode of the second diode (S1_D2) to form the first input terminal of the three-phase rectifier bridge 13. The cathode of the first diode (S1_D1) is connected to the positive DC bus, and the anode of the second diode (S1_D2) is connected to the negative DC bus. The anode of the third diode (S1_D3) is connected to the cathode of the fourth diode (S1_D4) to form the third input terminal of the three-phase rectifier bridge 13. The cathode of the third diode (S1_D3) is connected to the positive DC bus, and the anode of the fourth diode (S1_D4) is connected to the negative DC bus. The anode of the fifth diode (S1_D5) is connected to the cathode of the sixth diode (S1_D6) to form the second input terminal of the three-phase rectifier bridge 13. The cathode of the fifth diode (S1_D5) is connected to the positive DC bus, and the anode of the sixth diode (S1_D6) is connected to the negative DC bus. The positive DC bus and negative DC bus are used to connect to the load.

[0055] Corresponding to the above embodiments, refer to Figure 4 The present invention also provides a three-interleaved LLC converter, comprising: three LLC converter circuits as provided in the above embodiments; The half-bridge resonant units in the three LLC converter circuits are all connected to the DC power supply, and the three-phase rectifier bridges 13 in the three LLC converter circuits are all used to connect to the load. The primary windings of the first transformer in the three LLC converter circuits are connected in a star configuration, and the primary windings of the second transformer in the three LLC converter circuits are connected in a star configuration, dividing the circuit into three interleaved half-bridges H1 and H2.

[0056] refer to Figure 4 The triple-interleaved half-bridge H1 includes: upper switching transistors H1_mos1, H1_mos3, and H1_mos5; lower switching transistors H1_mos2, H1_mos4, and H1_mos6; resonant capacitors H1Cr1, H1Cr2, and H1Cr3; resonant inductors H1Lr1, H1Lr2, and H1Lr3; and transformers H1T1, H1T3, and H1T5. The three-interleaved half-bridge H2 includes: upper switching transistors H2_mos1, H2_mos3, and H2_mos5; lower switching transistors H2_mos2, H2_mos4, and H2_mos6; resonant capacitors H2Cr1, H2Cr2, and H2Cr3; resonant inductors H2Lr1, H2Lr2, and H2Lr3; and transformers H2T1, H2T3, and H2T5.

[0057] The secondary side includes six double-pole single-throw relays Q1, Q3, Q5, Q7, Q9, and Q11, diodes S1_D1, S1_D2, S1_D3, S1_D4, S1_D5, S1_D6, S3_D1, S3_D2, S3_D3, S3_D4, S3_D5, S3_D6, S5_D1, S5_D2, S5_D3, S5_D4, S5_D5, and S5_D6, positive bus capacitor CD1, negative bus capacitor CD2, and load Rs.

[0058] refer to Figure 4 In the three LLC converter circuits, the primary windings of the first transformer form an independent star connection, and the primary windings of the three second transformers form another independent star connection. Each star connection has its own independent potential midpoint. The star connection forces the input voltages of the three-phase primary windings to be completely symmetrical, achieving natural current sharing among the three phases from the hardware perspective, thus solving the problems of uneven current distribution between phases and large zero-sequence circulating current in traditional multi-phase interleaved LLC converters. Simultaneously, it provides a stable potential reference for switching between primary-side synchronous and asynchronous drive modes, ensuring that the three-phase operating states are completely consistent during 2:1 gain switching and avoiding switching shocks.

[0059] The drive signals of the three LLC converter circuits are sequentially phased by 120° electrical angles (0° for the first, 120° for the second, and 240° for the third), ensuring that the operating states of the three interleaved LLC converters are synchronously staggered. The three-phase waveforms, after being phase-shifted by 120°, are superimposed on the positive and negative DC buses. The switching of the three-phase drive modes and the switching of the secondary-side gain levels must be completely synchronized to avoid phase-to-phase voltage differences and circulating current surges caused by timing discrepancies, thus ensuring the stability of the circuit operation.

[0060] Similar to the LLC converter circuit, the triple-interleaved LLC converter also forms four gain modes: 8, 6, 4, and 3.

[0061] refer to Figure 5 Each of the first dual-path synchronous switching units 14 is disconnected, and each of the second dual-path synchronous switching units 15 is closed.

[0062] The three primary transformers are connected in a star configuration to form a three-interleaved half-bridge H1, and the three secondary transformers are connected in a star configuration to form a three-interleaved half-bridge H2. The opposite terminals of the three secondary transformers are connected separately. This forms a full-bridge rectifier circuit with the secondary windings of transformers H1T1 and H2T1 connected in series and diodes S1_D1, S1_D2, S1_D5, and S1_D6. Similarly, the secondary windings of transformers H1T3 and H2T3 are connected in series and diodes S3_D1, S3_D2, S3_D5, and S3_D6. Finally, the secondary windings of transformers H1T5 and H2T5 are connected in series and diodes S5_D1, S5_D2, S5_D5, and S5_D6. Each transformer's secondary winding has two windings connected in series, one with 6 turns and the other with 2 turns, forming a total of 8 turns. Similar to the principle of LLC converter circuit, during operation, the drive signals of the three interleaved half-bridges H1 and H2 are synchronized. At the same time, the secondary voltages of transformers H1T1, H1T3, and H1T5 of the three interleaved half-bridges H1 and H2T1, H2T3, and H2T5 of the three interleaved half-bridges H2 are connected in series in the same direction and superimposed to achieve the highest gain. At this time, the converter gain is Kn*M.

[0063] refer to Figure 6Each of the first dual-path synchronous switching units 14 is closed, and each of the second dual-path synchronous switching units 15 is open.

[0064] The primary drive signal remains synchronized, but only 6 turns of the secondary winding are connected, and 2 turns of the winding are open. The transformer secondary series rectifier circuit has only the gain of 6 turns of the winding. At this time, the converter gain is Kn*M.

[0065] refer to Figure 7 Each of the first dual-path synchronous switching units 14 is disconnected, and each of the second dual-path synchronous switching units 15 is closed.

[0066] The primary side still consists of two star-connected triple-crossing half-bridges, H1 and H2. The opposite terminals of the three transformers on the secondary side are connected sequentially, with the midpoint of the series connection connected to the rectifier bridge arm. Thus, transformer H1T1 is connected to diodes S1_D1, S1_D2, S1_D3, and S1_D4; transformer H2T1 is connected to diodes S1_D3, S1_D4, S1_D5, and S1_D6; and transformer H1... Transformer H3, along with diodes S3_D1, S3_D2, S3_D3, and S3_D4; transformer H2T3, along with diodes S3_D3, S3_D4, S3_D5, and S3_D6; transformer H1T5, along with diodes S5_D1, S5_D2, S5_D3, and S5_D4; and transformer H2T5, along with diodes S5_D3, S5_D4, S5_D5, and S5_D6, form a parallel full-bridge rectifier circuit. Furthermore, each transformer's secondary winding has two windings connected in series, one with 6 turns and the other with 2 turns, forming 8 turns. At this time, the drive signals for the three-interleaved half-bridges H1 and H2 are asynchronously out of phase by 180°. Simultaneously, the secondary voltages of transformers H1T1, H1T3, and H1T5 in H1 and H2T1, H2T3, and H2T5 in H2 are sequentially opposite. Each transformer's secondary winding is rectified independently, forming a parallel state, reducing the gain to half that of the series state. At this point, the converter gain is Kn*M.

[0067] refer to Figure 8 Each of the first dual-path synchronous switching units 14 is closed, and each of the second dual-path synchronous switching units 15 is open.

[0068] The primary drive signal remains asynchronous with a phase difference of 180°. All transformer secondary windings are connected to only 6 turns of winding, with 2 turns of winding open. The transformer secondary series rectifier circuit has only the gain of 6 turns of winding. At this time, the converter gain is Kn*M.

[0069] The triple-interleaved LLC converter provided in this application combines the advantages of wide range, high efficiency, high power density and high reliability. It is particularly suitable for demanding wide-range output applications such as electric vehicle chargers, photovoltaic inverters, and communication power supplies, and has extremely high practical value and prospects.

[0070] Corresponding to the above embodiments, this embodiment of the invention also provides a charging device, including the triple-interleaved LLC converter provided in the above embodiments.

[0071] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An LLC converter circuit, characterized in that, include: The system comprises a first half-bridge resonant unit, a second half-bridge resonant unit, a first transformer, a second transformer, a three-phase rectifier bridge, a first dual-channel synchronous switching unit, and a second dual-channel synchronous switching unit. The primary winding of the first transformer is connected to the resonant branch in the first half-bridge resonant unit, the first end of the secondary winding of the first transformer is connected to the first input end of the three-phase rectifier bridge, the second end of the secondary winding of the first transformer is connected to the first end of the second dual-path synchronous switching unit, and the center tap of the secondary winding of the first transformer is connected to the first end of the first dual-path synchronous switching unit. The primary winding of the second transformer is connected to the resonant branch in the second half-bridge resonant unit, the first end of the secondary winding of the second transformer is connected to the second end of the second dual-path synchronous switching unit, the second end of the secondary winding of the second transformer is connected to the second input end of the three-phase rectifier bridge, and the center tap of the secondary winding of the second transformer is connected to the second end of the first dual-path synchronous switching unit. The common terminal of the first dual-channel synchronous switching unit and the common terminal of the second dual-channel synchronous switching unit are both connected to the third input terminal of the three-phase rectifier bridge; Both the first half-bridge resonant unit and the second half-bridge resonant unit are powered by a DC power supply. The first dual-path synchronous switching unit is used to: control the center tap of the secondary winding of the second transformer and the center tap of the secondary winding of the first transformer to be connected to the third input terminal of the three-phase rectifier bridge; or control the center tap of the secondary winding of the second transformer to be disconnected from the center tap of the secondary winding of the first transformer and the third input terminal of the three-phase rectifier bridge. The second dual-path synchronous switching unit is used to: control the second end of the secondary winding of the first transformer and the first end of the secondary winding of the second transformer to be connected to the third input terminal of the three-phase rectifier bridge; or control the second end of the secondary winding of the first transformer to be disconnected from the first end of the secondary winding of the second transformer and the third input terminal of the three-phase rectifier bridge.

2. The LLC converter circuit as described in claim 1, characterized in that, The first dual-channel synchronous switching unit includes: a double-pole single-throw relay; The normally open contacts of the first set of switches in the double-pole single-throw relay form the first end of the first dual-channel synchronous switching unit; The normally open contacts of the second set of switches in the double-pole single-throw relay form the second end of the first dual-channel synchronous switching unit; The common terminal of the first set of switches in the double-pole single-throw relay is connected to the common terminal of the second set of switches in the double-pole single-throw relay to form the common terminal of the first dual-channel synchronous switching unit.

3. The LLC converter circuit as described in claim 1, characterized in that, Also includes: Positive bus capacitor and negative bus capacitor; The positive bus capacitor and the negative bus capacitor are connected in series between the positive DC bus and the negative DC bus.

4. The LLC converter circuit according to any one of claims 1 to 3, characterized in that, The first half-bridge resonant unit includes: a first half-bridge inverter sub-unit and a first resonant branch; The first end of the first resonant branch is connected to the output end of the first half-bridge inverter subunit, and the second end of the first resonant branch is connected to the first end of the primary winding of the first transformer. The second end of the primary winding of the first transformer is connected to the second input end of the first half-bridge inverter subunit; the first input end and the second input end of the first half-bridge inverter subunit are respectively used to connect to the positive and negative terminals of the DC power supply. The second half-bridge resonant unit includes: a second half-bridge inverter sub-unit and a second resonant branch; The first end of the second resonant branch is connected to the output end of the second half-bridge inverter subunit, and the second end of the second resonant branch is connected to the first end of the primary winding of the second transformer. The second end of the primary winding of the second transformer is connected to the second input end of the second half-bridge inverter subunit; the first input end of the second half-bridge inverter subunit is connected to the first input end of the first half-bridge inverter subunit, and the second input end of the second half-bridge inverter subunit is connected to the second input end of the first half-bridge inverter subunit.

5. The LLC converter circuit as described in claim 4, characterized in that, The first half-bridge inverter subunit includes: a first switch and a second switch; The first end of the first switch forms the first input terminal of the first half-bridge inverter subunit; the second end of the first switch is connected to the first end of the second switch to form the output terminal of the first half-bridge inverter subunit; the second end of the second switch forms the second input terminal of the first half-bridge inverter subunit. The second half-bridge inverter subunit includes: a third switch and a fourth switch; The first end of the third switch forms the first input terminal of the second half-bridge inverter subunit; the second end of the third switch is connected to the first end of the fourth switch to form the output terminal of the second half-bridge inverter subunit; the second end of the fourth switch forms the second input terminal of the second half-bridge inverter subunit. In this configuration, the first switch and the second switch are not turned on simultaneously, and the third switch and the fourth switch are turned on simultaneously.

6. The LLC converter circuit as described in claim 5, characterized in that, Also includes: Main control unit; The main control unit is used to: control the first switching transistor and the third switching transistor to synchronize; control the first dual-path synchronous switching unit to connect the center tap of the secondary winding of the second transformer and the center tap of the secondary winding of the first transformer to the third input terminal of the three-phase rectifier bridge; and control the second dual-path synchronous switching unit to disconnect the second end of the secondary winding of the first transformer from the first end of the secondary winding of the second transformer and the third input terminal of the three-phase rectifier bridge; or The first switching transistor is controlled to synchronize with the third switching transistor; the first dual-path synchronous switching unit is controlled so that the center tap of the secondary winding of the second transformer is not connected to the center tap of the secondary winding of the first transformer or the third input terminal of the three-phase rectifier bridge; and the second dual-path synchronous switching unit is controlled so that the second end of the secondary winding of the first transformer and the first end of the secondary winding of the second transformer are both connected to the third input terminal of the three-phase rectifier bridge; or Control the first switching transistor to be asynchronous with the third switching transistor; control the first dual-path synchronous switching unit to connect both the center tap of the secondary winding of the second transformer and the center tap of the secondary winding of the first transformer to the third input terminal of the three-phase rectifier bridge; and control the second dual-path synchronous switching unit to disconnect the second end of the secondary winding of the first transformer from both the first end of the secondary winding of the second transformer and the third input terminal of the three-phase rectifier bridge; or The first switching transistor is controlled to be asynchronous with the third switching transistor; the first dual-path synchronous switching unit is controlled to ensure that the center tap of the secondary winding of the second transformer is not connected to the center tap of the secondary winding of the first transformer or the third input terminal of the three-phase rectifier bridge; and the second dual-path synchronous switching unit is controlled to ensure that the second end of the secondary winding of the first transformer and the first end of the secondary winding of the second transformer are both connected to the third input terminal of the three-phase rectifier bridge.

7. The LLC converter circuit according to any one of claims 1 to 3, characterized in that, The turns ratio of the two windings of the secondary winding of the first transformer and the turns ratio of the two windings of the secondary winding of the second transformer are both 3:

1.

8. The LLC converter circuit according to any one of claims 1 to 3, characterized in that, The three-phase rectifier bridge includes: a first diode, a second diode, a third diode, a fourth diode, a fifth diode, and a sixth diode; The anode of the first diode is connected to the cathode of the second diode to form the first input terminal of the three-phase rectifier bridge. The cathode of the first diode is connected to the positive DC bus, and the anode of the second diode is connected to the negative DC bus. The anode of the third diode is connected to the cathode of the fourth diode to form the third input terminal of the three-phase rectifier bridge. The cathode of the third diode is connected to the positive DC bus, and the anode of the fourth diode is connected to the negative DC bus. The anode of the fifth diode is connected to the cathode of the sixth diode to form the second input terminal of the three-phase rectifier bridge. The cathode of the fifth diode is connected to the positive DC bus, and the anode of the sixth diode is connected to the negative DC bus. The positive DC bus and the negative DC bus are used to connect to the load.

9. A triple-interleaved LLC converter, characterized in that, include: Three LLC conversion circuits as described in any one of claims 1 to 8; The half-bridge resonant units in the three LLC converter circuits are all connected to the DC power supply, and the three-phase rectifier bridges in the three LLC converter circuits are all used to connect to the load. The primary windings of the first transformers in the three LLC conversion circuits are connected in a star configuration, and the primary windings of the second transformers in the three LLC conversion circuits are connected in a star configuration.

10. A charging device, characterized in that, Includes the triple-interleaved LLC converter as described in claim 9.

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