A control method and device of an LLC circuit

Abstract

The application discloses a control method and device of an LLC circuit, in which, when the LLC circuit is started, the reference value of the input positive end of a current loop module or the feedback value of the input negative end is dynamically changed, and the reference value or the feedback value is kept synchronous change with the output voltage of a power module; when the power module is controlled based on the dynamically changed reference value or feedback value, the output current of the power module is gradually increased, but since the reference value or the feedback value is established synchronously with the output voltage, the control signal for controlling the power module is small at the moment when the LLC circuit is started, the increasing rate of the output current of the power module can be reduced, that is, the output current can be slowly increased, and thus the power module can be prevented from appearing in the mode of hiccup during the starting process, the stress of each device in the LLC circuit is reduced, and the starting time is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of LLC circuit control, in particular to a LLC circuit control method and device. BACKGROUND

[0002] In a traditional LLC (power supply resonant circuit) circuit, especially in a constant current output LLC circuit, in its starting process, the current loop first starts to work, the input end of the current loop is the difference between the target current and zero, so that the output current of the LLC circuit starts to rise at the maximum rate, and the output voltage of the LLC circuit and the transmitted power start to increase.

[0003] In order to ensure the stability of the output voltage of the LLC circuit, a large capacitor is usually arranged at the output end of the LLC circuit, and the capacitor will cause the output current of the LLC circuit to increase instantaneously due to its own charging effect at the moment of starting, which may directly increase to the target current, that is, the difference at the input end of the current loop is zero, and the current loop is in a closed loop state, while the energy transmitted by the LLC circuit has not reached the set value, at this time the LLC circuit enters an intermittent working mode (i.e. hiccup mode), and the output voltage and the transmitted power of the LLC circuit start to increase intermittently, resulting in an increase in the stress of each device in the LLC circuit and a longer starting time.

[0004] It should be noted that the above-mentioned hiccup mode is different from the hiccup mode existing in the steady state working of the LLC circuit. Next, the hiccup mode of the LLC circuit in the steady state working will be described: when the LLC circuit is in a light load and steady state, the power transmitted by the LLC circuit is low, and due to the frequency characteristics of some LLC circuits, the working frequency is relatively high when the load is light, which is much higher than the set maximum frequency, at this time the LLC circuit will enter an intermittent working mode, that is, the switch tube in the LLC circuit works for a period of time and then stops working, and then enters the working mode. At this time, since the power transmitted by the LLC circuit is low, the stress on the device is much smaller than that in the hiccup mode during the starting process of the LLC circuit. Therefore, it is necessary to provide a method to avoid the hiccup mode of the LLC circuit during the starting process. SUMMARY

[0005] The purpose of the present application is to provide a LLC circuit control method and device, since the reference value at the input positive terminal or the feedback value at the input negative terminal is dynamically changed, the output current can be slowly increased, thereby avoiding the hiccup mode during the starting process, reducing the stress on each device in the LLC circuit and reducing the starting time.

[0006] To solve the above technical problems, the present application provides a LLC circuit control method applied to the LLC circuit, the LLC circuit comprising a current loop module and a power module, comprising:

[0007] In the starting process of the LLC circuit, the reference value of the input positive end of the current loop module or the feedback value of the input negative end thereof is dynamically changed so as to make the reference value or the feedback value change synchronously with the output voltage of the power module;

[0008] In the starting process of the LLC circuit, the power module is controlled according to the reference value and the feedback value so as to make the output current gradually increase but not be greater than the target current.

[0009] Preferably, the LLC circuit further comprises a sampling module for sampling the output current of the LLC circuit to obtain a sampling value; the reference value is a target current value;

[0010] The feedback value of the input negative end of the current loop module is dynamically changed so as to make the feedback value change synchronously with the output voltage of the power module, comprising

[0011] In the first time period, the output current of the input negative end of the current loop module is compensated, the sum of the compensation value and the sampling value is the feedback value, and the compensation value is gradually reduced to zero by a first parameter.

[0012] Preferably, the LLC circuit further comprises a sampling module for sampling the output current of the LLC circuit to obtain a sampling value; the feedback value is the sampling value of the LLC circuit;

[0013] The reference value of the input positive end of the current loop module is dynamically changed so as to make the reference value change synchronously with the output voltage of the power module, comprising:

[0014] The reference value of the input positive end of the current loop module is gradually increased to a target current by a second parameter in a second time period.

[0015] Preferably, the sampling module is a sampling resistor, and the reference value and the second parameter are voltage parameters;

[0016] The reference value of the input positive end of the current loop module is gradually increased to a target current by a second parameter in a second time period, comprising:

[0017] The reference value of the input positive end of the current loop module is gradually increased to a target voltage by the second voltage in the second time period through a charging delay circuit;

[0018] The second voltage is the product of the second parameter and the resistance value of the sampling resistor, and the target voltage is the product of the target current and the resistance value of the sampling resistor;

[0019] The current loop module comprises a DC / DC circuit;

[0020] The output end of the charging delay circuit is connected with the power supply end of the current loop module, and is connected with the input positive end of the current loop module through the DC / DC circuit. Preferably, the charging delay circuit is an RC delay charging circuit or a three-terminal voltage-stabilized delay charging circuit.

[0021] Preferably, the first time period and the second time period are both not less than the time for the LLC circuit to complete starting.

[0022] Preferably, the time for the LLC circuit to complete starting is the time from the LLC circuit being powered on to the output voltage of the power module reaching a preset voltage.

[0023] Preferably, the preset voltage is equal to N times of the rated output voltage of the power module, where 0.7≤N≤1.

[0024] Preferably, the first time period and the second time period are both not greater than 1.1 times of T, where T is the time from the LLC circuit being powered on to the output voltage of the power module reaching the rated output voltage.

[0025] To solve the above technical problem, the application further provides a control device of an LLC circuit, comprising:

[0026] an adjusting module, configured to control a reference value of an input positive end of the current loop module or a feedback value of an input negative end thereof to dynamically change during starting of the LLC circuit, so that the reference value or the feedback value changes synchronously with the output voltage of the power module;

[0027] a loop control module, configured to control the power module according to the reference value and the feedback value during starting of the LLC circuit, so that the output current gradually increases but is not greater than a target current.

[0028] The application provides a control method and device of an LLC circuit. In the scheme, when the LLC circuit is powered on, a reference value of an input positive end of a current loop module or a feedback value of an input negative end thereof is controlled to dynamically change, and the reference value or the feedback value is caused to change synchronously with an output voltage of a power module. When the power module is controlled based on the dynamically changed reference value or feedback value, the output current of the power module gradually increases. However, because the reference value or the feedback value is established synchronously with the output voltage, the control signal for controlling the power module to act is small at the moment when the LLC circuit is powered on, the rate at which the output current of the power module increases can be reduced, that is, the output current can be slowly increased, and the power module is prevented from entering a hiccup mode during starting, the stress on devices in the LLC circuit is reduced, and the starting time is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the prior art and embodiments. Obviously, the drawings described below are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained without creative labor on the basis of these drawings.

[0030] Figure 1 A flowchart of a control method of an LLC circuit provided by the present application is shown in the figure.

[0031] Figure 2 A structural block diagram of an LLC circuit provided by the present application is shown in the figure.

[0032] Figure 3 A schematic diagram of a current loop module provided by the present application is shown in the figure.

[0033] Figure 4 A schematic diagram of an RC delay charging circuit provided by the present application is shown in the figure.

[0034] Figure 5 A schematic diagram of a three-terminal voltage-stabilizing delay circuit provided by the present application is shown in the figure.

[0035] Figure 6 A whole topology schematic diagram of an LLC circuit provided by the present application is shown in the figure.

[0036] Figure 7 A structural block diagram of a control device of an LLC circuit provided by the present application is shown in the figure. DETAILED DESCRIPTION

[0037] The core of the present application is to provide a control method and device of an LLC circuit. Since the reference value of the input positive terminal of the loop module or the feedback value of the input negative terminal is dynamically changed in the process of starting up, the output current of the power module can be slowly increased, and then the hiccup mode in the process of starting up can be avoided, the stress of each device in the LLC circuit is reduced, and the starting-up time is reduced.

[0038] In order to make the purpose, technical solutions and advantages of the embodiments of the present application more clear, the following will combine the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present application.

[0039] Considering that the current loop module 22 in the prior art outputs a control signal for controlling the output current of the power module 23 to increase at the maximum rate at the starting moment of the LLC circuit, in the process, due to the effect of the capacitance at the output end of the power module 23, the output current of the power module 23 may reach the target current instantaneously, at this moment, the LLC circuit transmitted power has not reached the set value, and the LLC circuit enters the intermittent working mode, increases the stress of the device, and increases the starting time of the LLC circuit.

[0040] Please refer to Figure 1 and Figure 2 , Figure 1 a flowchart of a control method of an LLC circuit provided by the present application, Figure 2 a structural block diagram of the LLC circuit provided by the present application, the method is applied to the LLC circuit, the LLC circuit comprises a current loop module 22 and a power module 23, comprising:

[0041] S11: in the starting process of the LLC circuit, the reference value of the input positive end or the feedback value of the input negative end of the current loop module 22 is dynamically changed, so that the reference value or the feedback value changes synchronously with the output voltage of the power module 23;

[0042] S12: in the starting process of the LLC circuit, the power module 23 is controlled according to the reference value and the feedback value, so that the output current gradually increases but is not greater than the target current.

[0043] Please refer to Figure 3 , Figure 3 the schematic diagram of the current loop module provided by the present application. The current loop module 22 comprises an operational amplifier and its peripheral circuit. Wherein I+ is the input positive end, I- is the input negative end, Iout is the output end, Vcc is the operational amplifier power supply end, and the operational amplifier is powered.

[0044] Because in the starting process of the LLC circuit, the difference value of the input end of the current loop module 22 is related to the size of the control signal for controlling the power module 23, specifically, the greater the difference value, the greater the control signal output by the current loop module 22, so that the output current of the power module 23 rises at the fastest rate, until it is stabilized at the reference value of the input positive end of the current loop module 22, at this moment, the change rate of the corresponding output current of the power module 23 is larger.

[0045] Therefore, in the dynamic change process of the control reference value and the feedback value in the application, the size of the control reference value or the feedback value is controlled, so that the rate of change of the output current is controlled in the startup process, the current loop is prevented from forming a closed loop, that is, the power module 23 is prevented from stopping increasing the output voltage when the current loop is closed and the output power has not reached the set value. In addition, when the power module 23 is controlled to act, the output current of the power module 23 can be continuously less than the reference value, so that the current loop is always in the process of adjusting the output current of the power module 23 until it stabilizes at the reference value, that is, in the startup process, the power module 23 will always be controlled to work, and the power module 23 does not exist. The time to stop working, thereby avoiding the occurrence of the hiccup mode, reducing the stress of each device in the power module 23, and reducing the startup time of the LLC circuit.

[0046] It should be noted that the synchronous change in the application can refer to the synchronous change in time and value, for example, the reference value can be increased when the output voltage is increased.

[0047] In summary, the method in the application can continuously increase the output current, and the current loop module 22 does not exist. The time of closed loop is avoided, and the hiccup mode is avoided in the startup process, the stress of each device in the LLC circuit is reduced, and the startup time is reduced.

[0048] Based on the above embodiment:

[0049] As a preferred embodiment, the LLC circuit further comprises a sampling module 21 for sampling the output current of the LLC circuit to obtain a sampling value; the reference value is a target current value;

[0050] The feedback value of the input negative end of the current loop module is dynamically changed to make the feedback value change synchronously with the output voltage of the power module, comprising

[0051] In the first time period, the output current of the input negative end of the current loop module is compensated, the sum of the compensation value and the sampling value is the feedback value, and the compensation value is gradually reduced to zero from the first parameter.

[0052] The embodiment aims to provide a specific implementation mode for controlling the difference between the input positive end and the input negative end of the current loop module 22 to be less than a preset value. Specifically, the output current of the input negative end can be compensated during the startup process of the LLC circuit, and the compensation value is gradually reduced, so that the sum of the compensation value and the sampling value of the input negative end changes synchronously with the output voltage. The synchronous change here can be the synchronous change of the compensation value and the output voltage, specifically, the compensation value can be reduced synchronously when the output voltage is increased.

[0053] In addition, to ensure that the current loop module 22 does not exist in the process of starting the closed loop, the reference value of the input positive terminal can be limited to be greater than the sum of the preset parameter and the output current in the first time period, so that the current loop module 22 continuously controls the power module 23 in this process, and the power module 23 avoids frequent start-stop operations.

[0054] For example, when the output current needs to be controlled to be stable at 5A, the reference value of the input positive terminal is set to 5A, and the output current of the power module 23 is 0A when the LLC circuit is started, at this time, the input negative terminal can be compensated by 4A, so that the difference between the positive terminal and the negative terminal is 1A, and the current loop module 22 controls the power module 23 based on the difference of 1A, and gradually reduces the compensation until it is reduced to 0 when the output current is about to be adjusted to 5A, and the starting of the LLC circuit is completed.

[0055] In summary, the input negative terminal of the current loop module 22 and the output terminal of the power module can be controlled to change synchronously by the method in the embodiment, the LLC circuit can avoid the working mode of hiccup in the starting process, the starting time is reduced, and the implementation is simple and reliable.

[0056] As a preferred embodiment, the LLC circuit further comprises a sampling module 21 for sampling the output current of the LLC circuit to obtain a sampling value, and the feedback value is the sampling value of the LLC circuit.

[0057] The reference value of the input positive terminal of the current loop module 22 is dynamically changed to make the reference value and the output voltage of the power module 23 change synchronously, which comprises:

[0058] The reference value of the input positive terminal of the current loop module 22 is gradually increased to a target current by a second parameter in a second time period.

[0059] The embodiment aims to provide a specific implementation mode of controlling the reference value of the input positive terminal of the current loop module 22 and the output voltage to change synchronously, and specifically, the reference value of the input positive terminal can be adjusted during the starting of the LLC circuit.

[0060] In addition, to further ensure that the current loop module 22 does not exist in the process of starting the closed loop, the reference value of the input positive terminal can be limited to be greater than the sum of the preset parameter and the output current in the first time period, so that the current loop module 22 continuously controls the power module 23 in this process, and the power module 23 avoids frequent start-stop operations.

[0061] It should be noted that the current loop closed loop refers to that the reference value of the positive input terminal of the current loop is equal to the feedback value of the negative input terminal in a period of time, that is, a stable state is reached.

[0062] For example, when the output current needs to be controlled to be stable at 5A, the reference value of the input positive terminal can be gradually increased from 1A to 5A in the first time period. When the LLC circuit is just started, the output current of the power module 23 is 0A, and at this time, the current of the input positive terminal is 1A, so that the difference between the positive terminal and the negative terminal is 1A. The current loop module 22 controls the power module 23 based on the difference of 1A, and gradually increases the reference value after the output current is increased, so as to adjust the output parameter and control the starting power supply to complete the starting.

[0063] In summary, through the manner in the embodiment, the reference value of the input positive terminal of the current loop module 22 can be controlled to change synchronously with the output voltage, which can avoid the working mode of the LLC circuit in the starting process, reduce the starting time, and the implementation is simple and reliable.

[0064] As a preferred embodiment, the reference value of the input positive terminal of the current loop module 22 is gradually increased from the second parameter to the target current in the second time period, comprising:

[0065] The reference value of the input positive terminal of the current loop module 22 is gradually increased from the second voltage to the target voltage in the second time period through the charging delay circuit;

[0066] The second voltage is the product of the second parameter and the resistance value of the sampling resistor, and the target voltage is the product of the target current and the resistance value of the sampling resistor;

[0067] The current loop module comprises a DC / DC circuit;

[0068] The output end of the charging delay circuit is connected with the power supply end of the current loop module, and the input positive terminal of the current loop module is connected through the DC / DC circuit.

[0069] Specifically, when the output current of the power module 23 is collected by the sampling resistor, the reference value of the input positive terminal of the current loop module 22 and the parameter of the input negative terminal are both voltage parameters. At this time, the reference value of the input positive terminal is controlled to be gradually increased from the second parameter to the target current in the second time period, that is, the reference value of the input positive terminal is controlled to be increased from the second voltage corresponding to the second parameter to the target voltage corresponding to the target current. The specific implementation manner in the implementation process can be but is not limited to the charging delay circuit. The charging time is the above-mentioned second time period, and the charging time (the second time period) can be adjusted by adjusting the specific parameters in the charging delay circuit.

[0070] As a preferred embodiment, the charging delay circuit is an RC delay charging circuit or a three-terminal voltage stabilizing delay charging circuit.

[0071] In the embodiment, the charging delay circuit can be an RC delay charging circuit, please refer toFigure 4 , Figure 4 The schematic diagram of the RC delay charging circuit provided by the application, wherein, the RC delay charging circuit comprises a first resistor R1 and a first capacitor C1, one end of the R1 inputs a target voltage, the other end of the R1 is connected with one end of the C1, and the other end of the C1 is connected with the input positive end of the current loop module 22 as an output end of the RC circuit, and the voltage of the input positive end of the current loop module 22 gradually increases to the target voltage in the second time period due to the charging effect of the RC circuit when the LLC circuit starts. The charging time (the second time period) can be adjusted by adjusting the resistance value of the R1 and the capacitance value of the C1.

[0072] In addition, the charging delay circuit in the embodiment can also be a three-terminal voltage stabilizing delay circuit, please refer to Figure 5 , Figure 5 The schematic diagram of the three-terminal voltage stabilizing delay circuit provided by the application, the three-terminal voltage stabilizing delay circuit comprises a second resistor, a second capacitor, a triode, a voltage stabilizing tube, a third capacitor, a third resistor, a fourth resistor and a fifth resistor, wherein, one end of the second resistor is connected with the first end of the triode as an input end, and inputs a target voltage, the other end of the second resistor is connected with the control end of the triode, the cathode of the voltage stabilizing tube, the first end of the third capacitor and the first end of the second capacitor respectively, the second end of the second capacitor is connected with the anode of the voltage stabilizing tube, the first end of the fifth resistor and the ground end respectively, the control end of the voltage stabilizing tube is connected with the second end of the fifth resistor, the first end of the third resistor and the first end of the fourth resistor respectively, the second end of the third resistor is connected with the second end of the third capacitor, the second end of the fourth resistor is connected with the second end of the triode as an output end, and is connected with the input positive end of the current loop module 22. The charging time (the second time period) can be adjusted by adjusting the capacitance value of the second capacitor.

[0073] In summary, the two charging circuits described above can gradually increase the reference value from the second parameter to the target parameter, and the implementation is simple and reliable. Of course, other implementation methods can also be used, which are not limited in the application.

[0074] Please refer to Figure 6 , Figure 6 The overall topology schematic diagram of the LLC circuit provided by the application. The RC delay charging circuit is used to gradually increase the reference value of the input positive end of the current loop module 22, and further comprises a coil coupled with the transformer T0 in the power module 23 and a diode D2. The cathode of the diode D2 is connected with the In end of the RC delay circuit, the Out end of the delay circuit is connected with the Vcc end of the current loop module to supply power for the current loop module. A direct current voltage source DC is arranged at the I+ end and the Vcc end of the current loop module 22, the output voltage VI+ of the direct current voltage source and the Vcc together establish, that is, the value of VI+ increases or decreases at the same time as the Vcc, and when the Vcc reaches a steady value, VI+ also maintains a steady state.

[0075] As a preferred embodiment, the first time period and the second time period are both not less than a time for the LLC circuit to complete starting.

[0076] The present application is to ensure that the hiccup mode is avoided during the starting process of the LLC circuit, that is, the power module 23 in the LLC circuit is prevented from frequently starting and stopping during the starting process of the LLC circuit. Therefore, the first time period and the second time period described above are both not less than the time for the LLC circuit to complete starting in this embodiment, so as to ensure that the power module 23 is controlled by the above working mode during the starting process of the LLC circuit, and the hiccup mode is avoided.

[0077] As a preferred embodiment, the time for the LLC circuit to complete starting is the time from the LLC circuit being powered on to the output voltage of the power module 23 reaching a preset voltage.

[0078] The present embodiment aims to define that the time for the LLC circuit to complete starting is the time from the LLC circuit being powered on to the output voltage of the power module 23 reaching a preset voltage. As a preferred embodiment, the preset voltage is equal to N times of the rated output voltage of the power module 23, and 0.7≤N≤1. The preset voltage can be but is not limited to 70% of the rated voltage, that is, when the output voltage reaches 70% of the rated voltage, it can be determined that the LLC circuit has completed starting.

[0079] The above is only to select the voltage as the parameter for determining whether the LLC circuit has completed starting in the present embodiment, and the output current and output power of the power module 23 can also be used for determination, which is not limited herein.

[0080] In summary, the lower limit threshold of the first time period and the second time period can be defined by the method in the present application, so as to ensure that there is no hiccup mode during the starting process.

[0081] As a preferred embodiment, the first time period and the second time period are both not greater than 1.1*T, and T is the time from the LLC circuit being powered on to the output voltage of the power module 23 reaching the rated voltage.

[0082] The present application is to ensure that the hiccup mode is avoided during the starting process of the LLC circuit, that is, the power module 23 in the LLC circuit is prevented from frequently starting and stopping during the starting process of the LLC circuit. Therefore, the above process only needs to continue until the LLC circuit completes starting, and after the LLC circuit completes starting, the normal closed-loop control can be performed.

[0083] Therefore, the embodiment aims to limit the upper limit value of the first time period and the second time period to 1.1 times of the time from the startup of the LLC circuit to the time when the output voltage of the power module 23 reaches the rated voltage. Of course, the output voltage is only one parameter selected here, and the output current or the output power of the power module 23 can also be selected to limit the upper limit value. The specific manner is not described here.

[0084] Please refer to Figure 7 , Figure 7 The application provides a structural block diagram of a control device of an LLC circuit, and the device comprises:

[0085] The adjusting module 71 is used for dynamically changing the reference value of the input positive end or the feedback value of the input negative end of the current loop module in the startup process of the LLC circuit, so that the reference value or the feedback value is synchronously changed with the output voltage of the power module.

[0086] The loop control module 72 is used for controlling the power module according to the reference value and the feedback value in the startup process of the LLC circuit, so that the output current is gradually increased but is not greater than the target current.

[0087] To solve the above technical problems, the application further provides a control device of an LLC circuit. The control device of the LLC circuit is introduced in the above embodiment, and details are not described here.

[0088] It should be noted that, in the specification, the relationship terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or sequence between the entities or operations. Moreover, the terms "include", "contain" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to the process, method, article or device. Without more limitations, the element limited by the statement "including a" does not exclude the presence of another same element in the process, method, article or device including the element.

[0089] Those skilled in the art will further realize that the mechanisms of the various examples described herein are capable of being implemented using any number of combinations of the described features. Accordingly, these examples are not limited to the mechanisms described herein, but rather, the intent is to cover all modifications and alternatives equivalent thereto. The preceding description of the examples is illustrative, and not restrictive. Many other examples will be apparent to those of skill in the art upon reviewing the above description. The scope of the examples should, therefore, be determined not with reference to the above description, but instead should be given to the appended claims, along with their full scope of equivalents.

[0090] The above description of disclosed examples is intended to be illustrative, and not restrictive. Many other examples will be apparent to those of skill in the art upon reviewing the above description. The scope of examples should, therefore, be determined not with reference to the above description, but instead should be given to the appended claims, along with their full scope of equivalents.

Claims

1. A control method for an LLC circuit, characterized in that, The control method is applied to the LLC circuit, which includes a current loop module and a power module, and includes: During the LLC circuit startup process, the reference value at the positive input terminal or the feedback value at the negative input terminal of the current loop module is dynamically changed so that the reference value or the feedback value changes synchronously with the output voltage of the power module. During the LLC circuit startup process, the power module is controlled according to the reference value and the feedback value, so that the output current gradually increases but does not exceed the target current.

2. The control method for the LLC circuit as described in claim 1, characterized in that, The LLC circuit also includes a sampling module for sampling the output current of the LLC circuit to obtain a sampled value; the reference value is the target current value. The feedback value at the negative input terminal of the current loop module is dynamically changed to synchronize with the output voltage of the power module, including: During the first time period, the output current at the negative input terminal of the current loop module is compensated, and the sum of the compensation value and the sampled value is the feedback value. The compensation value is then controlled to gradually decrease from the first parameter to zero.

3. The control method for the LLC circuit as described in claim 1, characterized in that, The LLC circuit also includes a sampling module for sampling the output current of the LLC circuit to obtain a sampled value; the feedback value is the sampled value of the LLC circuit. Controlling the dynamic change of the reference value at the positive input terminal of the current loop module so that the reference value changes synchronously with the output voltage of the power module includes: The reference value of the positive input terminal of the current loop module is controlled to gradually increase from the second parameter to the target current during the second time period.

4. The control method for the LLC circuit as described in claim 3, characterized in that, The sampling module is a sampling resistor, and the reference value and the second parameter are both voltage parameters. The reference value at the positive input terminal of the current loop module is controlled to gradually increase from the second parameter to the target current during the second time period, including: The reference value at the positive input terminal of the current loop module is controlled by the charging delay circuit to gradually increase from the second voltage to the target voltage during the second time period. The second voltage is the product of the second parameter and the resistance value of the sampling resistor, and the target voltage is the product of the target current and the resistance value of the sampling resistor; The current loop module includes a DC / DC circuit; The output terminal of the charging delay circuit is connected to the power supply terminal of the current loop module, and is connected to the positive input terminal of the current loop module through the DC / DC circuit.

5. The control method for the LLC circuit as described in claim 4, characterized in that, The charging delay circuit is an RC delay charging circuit or a three-terminal voltage-regulated delay charging circuit.

6. The control method for the LLC circuit as described in claim 2, characterized in that, The first time period is not less than the time required for the LLC circuit to complete its startup.

7. The control method for the LLC circuit as described in claim 3, characterized in that, The second time period is not less than the time required for the LLC circuit to complete its startup.

8. The control method for the LLC circuit as described in claim 6 or 7, characterized in that, The LLC circuit completes the startup time from the time the LLC circuit is powered on until the output voltage of the power module reaches the preset voltage.

9. The control method for the LLC circuit as described in claim 8, characterized in that, The preset voltage is equal to N times the rated output voltage of the power module, where 0.7 ≤ N ≤ 1.

10. The control method for the LLC circuit as described in claim 6, characterized in that, The first time period is no greater than 1.1 times T, where T is the time from when the LLC circuit is turned on to when the output voltage of the power module reaches the rated output voltage.

11. The control method for the LLC circuit as described in claim 7, characterized in that, The second time period is no greater than 1.1 times T, where T is the time from when the LLC circuit is turned on to when the output voltage of the power module reaches the rated output voltage.

12. A control device for an LLC circuit, characterized in that, include: The adjustment module is used to control the dynamic change of the reference value at the positive input terminal or the feedback value at the negative input terminal of the current loop module during the LLC circuit startup process, so that the reference value or the feedback value changes synchronously with the output voltage of the power module. The loop control module is used to control the power module according to the reference value and the feedback value during the startup process of the LLC circuit, so that the output current gradually increases but does not exceed the target current.

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