Soft start method and device of CLLC direct-current transformer

Abstract

The embodiment of the invention provides a soft start method and device for a CLLC direct-current transformer. The method comprises the steps that the switching frequency of a switching device in the CLLC direct-current transformer is set to be equal to the resonant frequency of an LC series resonant cavity; driving signals of the switching device in the CLLC direct-current transformer are set to be in a primary side and secondary side synchronous mode; in the starting process of the CLLC direct-current transformer, the duty ratio of the switching device is controlled to be increased to the preset threshold value according to the preset stepping value, the problem that no-load soft starting of a traditional CLLC direct-current transformer is difficult to achieve is solved, and impact current in the starting process is effectively restrained.

Description

Technical Field

[0001] The embodiments of the present invention relate to the field of communications, and in particular, to a soft starting method and device for a CLLC DC transformer. Background Art

[0002] DC transformers are widely used in electric vehicle chargers, data center power supplies, energy storage systems, and solid-state transformers. Among the existing DC transformer topologies, CLLC DC transformers have received widespread attention in the industry due to their good bidirectional power flow characteristics and soft switching characteristics. However, during the startup process, the instantaneous charging of the large-capacity filter capacitor by the CLLC DC transformer causes a large inrush current to be generated in the circuit, which increases the stress of the switching devices and resonant components and may even destroy the device.

[0003] In the prior art, the inrush current is usually suppressed by soft starting schemes such as frequency reduction soft starting, duty cycle variable soft starting or phase shift soft starting. However, these schemes cannot achieve soft starting of the CLLC DC transformer under no-load conditions. Summary of the invention

[0004] The embodiments of the present invention provide a soft starting method and device for a CLLC DC transformer, so as to at least solve the problem in the related art that the soft starting of the CLLC DC transformer under no-load condition cannot be achieved.

[0005] According to an embodiment of the present invention, a soft starting method for a CLLC DC transformer is provided, comprising:

[0006] Setting the switching frequency of the switch device in the CLLC DC transformer to be equal to the resonant frequency of the LC series resonant cavity;

[0007] Setting the driving signal of the switching device in the CLLC DC transformer to a primary side and a secondary side synchronization mode;

[0008] During the startup of the CLLC DC transformer, the duty cycle of the switching device is controlled to increase to a preset threshold value according to a preset step value.

[0009] In an exemplary embodiment, setting the switching frequency of the switching device in the CLLC DC transformer equal to the resonant frequency of the LC series resonant cavity includes:

[0010] The initial frequency of the switching device in the primary side of the CLLC DC transformer is set to be equal to the primary side LC series resonant cavity frequency, and the initial frequency of the switching device in the secondary side is set to be equal to the secondary side LC series resonant cavity frequency.

[0011] In an exemplary embodiment, the primary side and the secondary side of the CLLC DC transformer are both half-bridge circuits, and the driving signal of the switching device in the CLLC DC transformer is set to a primary side and a secondary side synchronous mode, including:

[0012] The switch device driving signals at corresponding positions of the primary half-bridge circuit and the secondary half-bridge circuit are set to be the same.

[0013] In an exemplary embodiment, the primary side and the secondary side of the CLLC DC transformer are both full-bridge circuits, and the driving signal of the switching device in the CLLC DC transformer is set to a primary side and a secondary side synchronous mode, including:

[0014] The switch device drive signals at corresponding positions of the primary full-bridge circuit and the secondary full-bridge circuit are set to be the same, and the switch device drive signals at diagonal positions of the primary full-bridge circuit are the same, and the switch device drive signals at the same half bridge are opposite, and the switch device drive signals at diagonal positions of the secondary full-bridge circuit are the same, and the switch device drive signals at the same half bridge are opposite.

[0015] In an exemplary embodiment, the initial duty cycle of the switching device is 0, and the preset threshold is 0.5.

[0016] In an exemplary embodiment, controlling the duty cycle of the switching device to gradually increase to a preset threshold value according to a preset step value includes:

[0017] The duty cycle of the primary-side switching device and the duty cycle of the secondary-side switching device are respectively controlled to increase from 0 to 0.5 according to a preset step value.

[0018] According to another embodiment of the present invention, a soft start device for a CLLC DC transformer is provided, which is applied to the CLLC DC transformer and includes:

[0019] A first setting module, used to set the switching frequency of the switch device in the CLLC DC transformer to be equal to the resonant frequency of the LC series resonant cavity;

[0020] A second setting module is used to set the driving signal of the switching device in the CLLC DC transformer to a primary side and a secondary side synchronization mode;

[0021] The control module is used to control the duty cycle of the switching device to increase to a preset threshold value according to a preset step value during the startup of the CLLC DC transformer.

[0022] In an exemplary embodiment, the first setting module includes:

[0023] The first setting submodule is used to set the initial frequency of the switching device in the primary side of the CLLC DC transformer to be equal to the primary side LC series resonant cavity frequency, and the initial frequency of the switching device in the secondary side to be equal to the secondary side LC series resonant cavity frequency.

[0024] In an exemplary embodiment, the primary side and the secondary side of the CLLC DC transformer are both half-bridge circuits, and the second setting module includes:

[0025] The second setting submodule is used to set the switch device driving signals at corresponding positions of the primary half-bridge circuit and the secondary half-bridge circuit to be the same.

[0026] In an exemplary embodiment, the primary side and the secondary side of the CLLC DC transformer are both full-bridge circuits, and the second setting module includes:

[0027] The third setting submodule is used to set the switch device driving signals at corresponding positions of the primary full-bridge circuit and the secondary full-bridge circuit to be the same, and the switch device driving signals of the primary full-bridge circuit at diagonal positions are the same, and the switch device driving signals at the same half bridge are opposite, and the switch device driving signals of the secondary full-bridge circuit at diagonal positions are the same, and the switch device driving signals at the same half bridge are opposite.

[0028] According to yet another embodiment of the present invention, a computer-readable storage medium is provided, in which a computer program is stored, wherein the computer program is configured to execute the steps of any one of the above method embodiments when run.

[0029] According to yet another embodiment of the present invention, there is provided an electronic device, including a memory and a processor, wherein the memory stores a computer program, and the processor is configured to run the computer program to execute the steps in any one of the above method embodiments.

[0030] The present invention solves the problem that traditional CLLC DC transformers are difficult to achieve no-load soft starting by setting the switching frequency of the switching device in the CLLC DC transformer equal to the resonant frequency of the LC series resonant cavity, setting the primary side drive signal and the secondary side of the switching device to be synchronized, and during the startup of the CLLC DC transformer, controlling the duty cycle of the switching device to increase to a preset threshold value according to a preset step value, thereby effectively suppressing the impact current during the startup process. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a flow chart of a soft starting method of a CLLC DC transformer according to an embodiment of the present invention;

[0032] Figure 2 A full-bridge CLLC DC transformer according to an embodiment of the present invention;

[0033] Figure 3 A half-bridge CLLC DC transformer according to an embodiment of the present invention;

[0034] Figure 4 1 is a driving waveform diagram of a soft-start process of a full-bridge CLLC DC transformer according to an embodiment of the present invention;

[0035] Figure 5 4 is a structural block diagram of a soft starting device for a CLLC DC transformer according to an embodiment of the present invention. DETAILED DESCRIPTION

[0036] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings and in combination with the embodiments.

[0037] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence.

[0038] In electric vehicle chargers, data center power supplies, energy storage systems, and solid-state transformers, electrical energy is converted through two-stage converters, AC-DC and DC-DC. The DC-DC converter, as an important stage, realizes the functions of DC voltage conversion and electrical isolation. In some scenarios, in order to further improve system efficiency, the DC-DC converter operates at a fixed voltage gain. Under this condition, the DC converter is also called a DC transformer. In the category of DC transformers, adding a resonant cavity can make it easier to achieve soft switching of switching devices and improve the efficiency of DC transformers. Introducing a series LC resonant cavity on both the primary and secondary sides forms a CLLC type DC transformer.

[0039] In response to the problem of inrush current during the starting process of the CLLC DC transformer, traditional soft start solutions include frequency reduction soft start, duty cycle soft start and phase shift soft start. All of the above three solutions only apply drive to the primary switching device, and the secondary side is a diode uncontrolled rectifier. Frequency reduction soft start uses the characteristic that the gain of the CLLC DC transformer is low when the switching frequency is high, sets the initial switching frequency to a high level, and gradually reduces the switching frequency during the starting process, thereby suppressing the inrush current during the starting process to achieve soft start. However, this solution requires the initial switching frequency to be set high, and at the same time, due to the problem of the no-load gain curve being upturned due to the parasitic capacitance of the transformer, this solution cannot complete soft start under no-load conditions. Duty cycle soft start and phase shift soft start control the duty cycle of the primary AC square wave voltage by changing the duty cycle of the primary switching device and changing the phase shift angle between the two half-bridges, respectively, to suppress the inrush current during the starting process, but also due to the problem of the CLLC no-load gain curve being upturned, soft start under no-load conditions cannot be achieved. That is, the existing solution cannot achieve soft start of the CLLC DC transformer under no-load conditions.

[0040] The core concept of the embodiment of the present invention is that during the soft start process, by setting the switching frequency of the switching device in the CLLC DC transformer equal to the resonant frequency of the series resonant cavity, setting the drive signal of the primary switching device and the drive signal of the secondary switching device synchronously, and controlling the duty cycle of the switching device to increase to a preset threshold value according to a preset step value, the impact current during the startup process is suppressed, and the problem that the traditional CLLC DC transformer is difficult to achieve no-load soft start is solved.

[0041] In this embodiment, a soft starting method of a CLLC DC transformer is provided. Figure 1 is a flow chart of a soft starting method of a CLLC DC transformer according to an embodiment of the present invention. Figure 1 As shown, the process includes the following steps:

[0042] Step S101, setting the switching frequency of the switching device in the CLLC DC transformer to be equal to the resonant frequency of the LC series resonant cavity.

[0043] like Figure 2 The full-bridge CLLC DC transformer according to an embodiment of the present invention is shown, comprising a primary full bridge (1), a secondary full bridge (5), a primary LC series resonant cavity (2), a secondary LC series resonant cavity (4) and a transformer (3); the primary full bridge (1) is composed of switch devices (Q1-Q4), the secondary full bridge (5) is composed of switch devices (S1-S4), and the series resonant cavities (2) and (4) are both composed of a resonant inductor (Lr) and a resonant capacitor (Cr) connected in series.

[0044] As an example, the initial switching frequency of the switching device in the CLLC DC transformer can be set equal to the resonant frequency f of the LC series resonant cavity. s , where the resonant frequency of the LC series resonant cavity is s The specific calculation formula is:

[0045]

[0046] Among them, C r With L r They represent the resonant capacitance and resonant inductance of the resonant cavity respectively.

[0047] In an optional embodiment, setting the switching frequency of the switching device in the CLLC DC transformer equal to the resonant frequency of the LC series resonant cavity includes: setting the initial frequency of the switching device in the primary side of the CLLC DC transformer equal to the primary LC series resonant cavity frequency, and setting the initial frequency of the switching device in the secondary side equal to the secondary LC series resonant cavity frequency.

[0048] By setting the initial frequency of the switch device in the primary side of the CLLC DC transformer to be equal to the primary side LC series resonant cavity frequency, and the initial frequency of the switch device in the secondary side to be equal to the secondary side LC series resonant cavity frequency, the primary side switch device frequency can be maintained equal to the resonant frequency of the primary side series resonant cavity, and the secondary side switch device frequency can be maintained equal to the resonant frequency of the secondary side series resonant cavity during the soft start process, so that the switching frequency of the switch device in the CLLC DC transformer remains unchanged, and the problem of the no-load gain curve being warped due to the parasitic capacitance of the transformer can be avoided. At the same time, since the switching frequency is equal to the resonant frequency, no additional closed-loop control is required, and the drive circuit of the switch device is easy to implement and has low cost.

[0049] It should be noted that both the primary full-bridge circuit (1) and the secondary full-bridge circuit (5) in the CLLC DC transformer targeted by the present invention can be arbitrarily replaced by half-bridge circuits, and the embodiments of the present invention are not limited thereto.

[0050] Step S102, setting the driving signal of the switching device in the CLLC DC transformer to a primary side and secondary side synchronization mode.

[0051] As an example, the driving signal of the switching device in the CLLC DC transformer can be set to a primary-side and secondary-side synchronous mode to facilitate driving the primary-side switching device and the secondary-side switching device at the same time.

[0052] In an optional embodiment, the primary and secondary sides of the CLLC DC transformer are both full-bridge circuits, and the driving signals of the switching devices in the CLLC DC transformer are set to a primary and secondary synchronization mode, including: setting the driving signals of the switching devices at corresponding positions of the primary full-bridge circuit and the secondary full-bridge circuit to be the same, and the driving signals of the switching devices in the diagonal position of the primary full-bridge circuit are the same, and the driving signals of the switching devices in the same half bridge are opposite, and the driving signals of the switching devices in the diagonal position of the secondary full-bridge circuit are the same, and the driving signals of the switching devices in the same half bridge are opposite.

[0053] As an example, if both the primary and secondary sides of the CLLC DC transformer are full-bridge circuits, such as Figure 2 The figure shows a full-bridge CLLC DC transformer according to an embodiment of the present invention. The driving signals of the switching devices at the corresponding positions of the primary full-bridge circuit and the secondary full-bridge circuit can be set to be the same. For example, the Q1 driving signal can be set to be the same as the S3 driving signal, the Q2 driving signal can be set to be the same as the S4 driving signal, the Q3 driving signal can be set to be the same as the S1 driving signal, and the Q4 driving signal can be set to be the same as the S2 driving signal.

[0054] The driving signals of the switch devices in the diagonal position of the primary full-bridge circuit can be set to be the same, and the driving signals of the switch devices in the same half bridge can be set to be opposite. For example, the Q1 driving signal can be set to be the same as the Q4 driving signal, and the Q2 driving signal can be set to be the same as the Q3 driving signal; the Q1 driving signal can be set to be 180° different from the Q2 driving signal, and the Q3 driving signal can be set to be 180° different from the Q4 driving signal.

[0055] At the same time, the switch drive signals of the diagonal position of the secondary full-bridge circuit can be set to be the same, and the switch drive signals of the same half-bridge can be set to be opposite. For example, the S1 drive signal can be set to be the same as the S4 drive signal, and the S2 drive signal can be set to be the same as the S3 drive signal; the S1 drive signal can be set to be 180° different from the S2 drive signal, and the S3 drive signal can be set to be 180° different from the S4 drive signal.

[0056] Through the above method, the upper and lower switch tubes at corresponding positions in the primary full bridge can be turned on alternately, ensuring that the resonant current always flows through the switching device, and the port voltage of the resonant cavity is always equal to the input voltage, thereby avoiding the high-frequency oscillation of the resonant current caused by the participation of parasitic capacitance in the resonance in the traditional variable duty cycle method.

[0057] In an optional embodiment, both the primary and secondary sides of the CLLC DC transformer are half-bridge circuits, and the driving signal of the switching device in the CLLC DC transformer is set to a primary and secondary synchronization mode, including: setting the driving signal of the switching device at the corresponding position of the primary half-bridge circuit and the secondary half-bridge circuit to be the same.

[0058] Reference Figure 3 , Figure 3 A half-bridge CLLC DC transformer according to an embodiment of the present invention comprises a primary half bridge (1), a secondary half bridge (5), a primary LC series resonant cavity (2), a secondary LC series resonant cavity (4) and a transformer (3); the primary full bridge (1) is composed of switch devices (Q1-Q2), the secondary full bridge (5) is composed of switch devices (S1-S2), and the series resonant cavities (2) and (4) are both composed of a resonant inductor (Lr) and a resonant capacitor (Cr) connected in series.

[0059] As an example, if the primary and secondary sides of the CLLC DC transformer are both half-bridge circuits, the switch device drive signals at corresponding positions of the primary half-bridge circuit and the secondary half-bridge circuit can be set to be the same, for example, the Q1 drive signal is set to be the same as the S1 drive signal, and the Q2 drive signal is set to be the same as the S2 drive signal.

[0060] It should be noted that the execution order of step S101 and step S102 in the embodiment of the present invention is interchangeable, that is, step S102 may be executed first, and then step S101 may be executed.

[0061] Step S103, during the startup of the CLLC DC transformer, controlling the duty cycle of the switching device to increase to a preset threshold value according to a preset step value.

[0062] As an example, during the startup of the CLLC DC transformer, the duty cycle of the switching device can be controlled to increase to a preset threshold value according to a preset step value, thereby achieving soft starting of the no-load CLLC DC transformer.

[0063] In an optional embodiment, the initial duty cycle of the switching device is 0, and the preset threshold is 0.5.

[0064] In an optional embodiment, the duty cycle of the switching device is controlled to gradually increase to a preset threshold value according to a preset step value, including: respectively controlling the duty cycle of the switching device on the primary side and the duty cycle of the switching device on the secondary side to increase from 0 to 0.5 according to a preset step value.

[0065] As an example, Figure 4 : is a driving waveform diagram of the soft starting process of the full-bridge CLLC DC transformer according to an embodiment of the present invention, referring to Figure 4 , the initial duty cycle d of the switch device in the CLLC DC transformer can be set to 0, and the duty cycle d of the drive signal can start from 0 and gradually increase from 0 according to the preset step value. Its expression is:

[0066] d=d0+Δd

[0067] Wherein, d0 represents the duty cycle at the last moment, and Δd represents the step value of the duty cycle. In the process of increasing the duty cycle, it is detected whether the current duty cycle d reaches 0.5. If it does not reach 0.5, it continues to increase according to the step value.

[0068] After the duty cycle d reaches 0.5, the duty cycle of the switching device can be maintained at 0.5, and the soft start process ends. The driving waveform of the driving signal of the switching device over time during the entire soft start process is as follows: Figure 4 shown.

[0069] It should be noted that the duty cycle increasing method in the embodiment of the present invention covers all commonly used functions, such as linear growth, quadratic function growth, exponential growth, etc., as well as any combination of these commonly used functions.

[0070] In order to further enable those skilled in the art to understand the soft start process of the CLLC DC transformer of the present invention, this embodiment is described by Example 1 and Example 2:

[0071] Example 1

[0072] In this embodiment, a full-bridge CLLC DC transformer is soft-started under no-load conditions. The specific parameters of the CLLC DC transformer are shown in Table 1:

[0073] Table 1 Circuit specific parameters

[0074]

[0075]

[0076] In this embodiment, the switching frequency of the full-bridge CLLC DC transformer is set equal to the resonant frequency. During the soft start process, the duty cycle d gradually increases linearly from 0 to 0.5 in 0-0.05s, and then remains unchanged at 0.5. During the start-up process of the circuit, the maximum peak value of the resonant cavity current is 44.5A, and the output capacitor voltage is slowly charged to the rated voltage of 60V, which better realizes the suppression of the impact current.

[0077] Example 2

[0078] In this embodiment, the half-bridge CLLC DC transformer is soft-started under no-load condition.

[0079] In this embodiment, the switching frequency of the half-bridge CLLC DC transformer is first set to be equal to the resonant frequency. During the soft start process, the duty cycle d is gradually increased linearly from 0 to 0.5 in 0-0.05s, and then remains unchanged at 0.5. During the start-up process of the circuit, the maximum peak value of the resonant cavity current is 34.5A, and the output capacitor voltage is slowly charged to the rated voltage of 60V, which better achieves the suppression of the impact current.

[0080] The present invention solves the problem that it is difficult to achieve no-load soft starting in a traditional CLLC DC transformer by setting the switching frequency of the switching device in the CLLC DC transformer equal to the resonant frequency of the LC series resonant cavity, setting the primary side drive signal and the secondary side of the switching device to be synchronized, and controlling the duty cycle of the switching device to increase to a preset threshold value according to a preset step value during the startup of the CLLC DC transformer, thereby effectively suppressing the impact current during the startup process. In addition, the control method of the circuit is simple and does not require additional closed-loop control. At the same time, since the switching frequency is equal to the resonant frequency, the driving circuit of the switching device is easy to implement and has low cost.

[0081] Through the description of the above implementation methods, those skilled in the art can clearly understand that the method according to the above embodiment can be implemented by means of software plus a necessary general hardware platform, and of course can also be implemented by hardware, but in many cases the former is a better implementation method. Based on such an understanding, the technical solution of the present invention, or the part that contributes to the prior art, can be embodied in the form of a software product, which is stored in a storage medium (such as ROM / RAM, a magnetic disk, or an optical disk), and includes a number of instructions for enabling a terminal device (which can be a mobile phone, a computer, a server, or a network device, etc.) to execute the methods described in each embodiment of the present invention.

[0082] In this embodiment, a soft start device for a CLLC DC transformer is also provided, which is used to implement the above-mentioned embodiments and preferred implementation modes, and the descriptions that have been made will not be repeated. As used below, the term "module" can implement a combination of software and / or hardware of a predetermined function. Although the devices described in the following embodiments are preferably implemented in software, the implementation of hardware, or a combination of software and hardware, is also possible and conceivable.

[0083] FIG. 5 is a block diagram of a soft start device for a CLLC DC transformer according to an embodiment of the present invention, which is applied to a CLLC DC transformer, such as Figure 5 As shown, the device comprises:

[0084] A first setting module 501 is used to set the switching frequency of the switch device in the CLLC DC transformer to be equal to the resonant frequency of the LC series resonant cavity;

[0085] A second setting module 502 is used to set the driving signal of the switch device in the CLLC DC transformer to a primary side and secondary side synchronization mode;

[0086] The control module 503 is used to control the duty cycle of the switching device to increase to a preset threshold value according to a preset step value during the startup of the CLLC DC transformer.

[0087] In an optional embodiment, the first setting module 501 includes:

[0088] The first setting submodule is used to set the initial frequency of the switching device in the primary side of the CLLC DC transformer to be equal to the primary side LC series resonant cavity frequency, and the initial frequency of the switching device in the secondary side to be equal to the secondary side LC series resonant cavity frequency.

[0089] In an optional embodiment, both the primary side and the secondary side of the CLLC DC transformer are half-bridge circuits, and the second setting module 502 includes:

[0090] The second setting submodule is used to set the switch device driving signals at corresponding positions of the primary half-bridge circuit and the secondary half-bridge circuit to be the same.

[0091] In an optional embodiment, both the primary side and the secondary side of the CLLC DC transformer are full-bridge circuits, and the second setting module includes:

[0092] The third setting submodule is used to set the switch device driving signals at corresponding positions of the primary full-bridge circuit and the secondary full-bridge circuit to be the same, and the switch device driving signals of the primary full-bridge circuit at diagonal positions are the same, and the switch device driving signals at the same half bridge are opposite, and the switch device driving signals of the secondary full-bridge circuit at diagonal positions are the same, and the switch device driving signals at the same half bridge are opposite.

[0093] In an optional embodiment, the initial duty cycle of the switching device is 0, and the preset threshold is 0.5.

[0094] In an optional embodiment, the control module 503 includes:

[0095] The control submodule is used to control the duty cycle of the primary side switch device and the duty cycle of the secondary side switch device to increase from 0 to 0.5 according to a preset step value.

[0096] It should be noted that the above modules can be implemented by software or hardware. For the latter, it can be implemented in the following ways, but not limited to: the above modules are all located in the same processor; or the above modules are located in different processors in any combination.

[0097] An embodiment of the present invention further provides a computer-readable storage medium, in which a computer program is stored, wherein the computer program is configured to execute the steps of any of the above method embodiments when running.

[0098] In an exemplary embodiment, the computer-readable storage medium may include, but is not limited to, various media that can store computer programs, such as a USB flash drive, a read-only memory (ROM), a random access memory (RAM), a mobile hard disk, a magnetic disk or an optical disk.

[0099] An embodiment of the present invention further provides an electronic device, including a memory and a processor, wherein a computer program is stored in the memory, and the processor is configured to run the computer program to execute the steps in any one of the above method embodiments.

[0100] In an exemplary embodiment, the electronic device may further include a transmission device and an input / output device, wherein the transmission device is connected to the processor, and the input / output device is connected to the processor.

[0101] For specific examples in this embodiment, reference may be made to the examples described in the above embodiments and exemplary implementation modes, and this embodiment will not be described in detail herein.

[0102] Obviously, those skilled in the art should understand that the above modules or steps of the present invention can be implemented by a general computing device, they can be concentrated on a single computing device, or distributed on a network composed of multiple computing devices, they can be implemented by a program code executable by a computing device, so that they can be stored in a storage device and executed by the computing device, and in some cases, the steps shown or described can be executed in a different order than here, or they can be made into individual integrated circuit modules, or multiple modules or steps therein can be made into a single integrated circuit module for implementation. Thus, the present invention is not limited to any specific combination of hardware and software.

[0103] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A soft starting method for a CLLC DC transformer, characterized in that: include: Setting the switching frequency of the switch device in the CLLC DC transformer to be equal to the resonant frequency of the LC series resonant cavity; Setting the driving signal of the switching device in the CLLC DC transformer to a primary side and a secondary side synchronization mode; During the startup of the CLLC DC transformer, the duty cycle of the switching device is controlled to increase to a preset threshold value according to a preset step value.

2. The method according to claim 1, characterized in that The step of setting the switching frequency of the switching device in the CLLC DC transformer to be equal to the resonant frequency of the LC series resonant cavity comprises: The initial frequency of the switching device in the primary side of the CLLC DC transformer is set to be equal to the primary side LC series resonant cavity frequency, and the initial frequency of the switching device in the secondary side is set to be equal to the secondary side LC series resonant cavity frequency.

3. The method according to claim 1, characterized in that The primary side and the secondary side of the CLLC DC transformer are both half-bridge circuits, and the driving signal of the switch device in the CLLC DC transformer is set to a primary side and a secondary side synchronous mode, including: The switch device driving signals at corresponding positions of the primary half-bridge circuit and the secondary half-bridge circuit are set to be the same.

4. The method according to claim 1, characterized in that: The primary side and the secondary side of the CLLC DC transformer are both full-bridge circuits, and the driving signal of the switch device in the CLLC DC transformer is set to a primary side and a secondary side synchronous mode, including: The driving signals of the switching devices at corresponding positions of the primary full-bridge circuit and the secondary full-bridge circuit are set to be the same, and the driving signals of the switching devices at diagonal positions of different half-bridges in the primary full-bridge circuit are the same, and the driving signals of the switching devices at the same half-bridge are opposite, and the driving signals of the switching devices at diagonal positions of different half-bridges in the secondary full-bridge circuit are the same, and the driving signals of the switching devices at the same half-bridge are opposite.

5. The method according to claim 1, characterized in that The initial duty cycle of the switching device is 0, and the preset threshold is 0.

5.

6. The method according to claim 5, characterized in that The step of controlling the duty cycle of the switch device to gradually increase to a preset threshold value according to a preset step value includes: The duty cycle of the primary-side switching device and the duty cycle of the secondary-side switching device are respectively controlled to increase from 0 to 0.5 according to a preset step value.

7. A soft start device for a CLLC DC transformer, applied to a CLLC DC transformer, characterized in that: include: A first setting module, used to set the switching frequency of the switch device in the CLLC DC transformer to be equal to the resonant frequency of the LC series resonant cavity; A second setting module is used to set the driving signal of the switching device in the CLLC DC transformer to a primary side and a secondary side synchronization mode; The control module is used to control the duty cycle of the switching device to increase to a preset threshold value according to a preset step value during the startup of the CLLC DC transformer.

8. The device according to claim 7, characterized in that The first setting module includes: The first setting submodule is used to set the initial frequency of the switching device in the primary side of the CLLC DC transformer to be equal to the primary side LC series resonant cavity frequency, and the initial frequency of the switching device in the secondary side to be equal to the secondary side LC series resonant cavity frequency.

9. The device according to claim 7, characterized in that The primary side and the secondary side of the CLLC DC transformer are both half-bridge circuits, and the second setting module includes: The second setting submodule is used to set the switch device driving signals at corresponding positions of the primary half-bridge circuit and the secondary half-bridge circuit to be the same.

10. The device according to claim 7, characterized in that The primary side and the secondary side of the CLLC DC transformer are both full-bridge circuits, and the second setting module includes: The third setting submodule is used to set the switch device driving signals at corresponding positions of the primary full-bridge circuit and the secondary full-bridge circuit to be the same, and the switch device driving signals of the primary full-bridge circuit at diagonal positions are the same, and the switch device driving signals at the same half bridge are opposite, and the switch device driving signals of the secondary full-bridge circuit at diagonal positions are the same, and the switch device driving signals at the same half bridge are opposite.

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