Control method and device of LLC resonant converter and electronic equipment

Abstract

The application belongs to the technical field of electronic circuits, and provides a control method and device of an LLC resonant converter and electronic equipment, the method comprising: if the current control period needs to be switched from a voltage loop to a current loop, updating the current loop PI output of the previous control period to the voltage loop PI output of the previous control period; if the current control period needs to be switched from the current loop to the voltage loop, updating the voltage loop PI output of the previous control period to the current loop PI output of the previous control period; and selecting the smaller value from the voltage loop PI output and the current loop PI output of the current control period to control the LLC resonant converter. The application can realize smooth switching of the LLC resonant converter control loop and improve system stability.

Description

Technical Field

[0001] This invention belongs to the field of electronic circuit technology, and particularly relates to a control method, device and electronic equipment for LLC resonant converter. Background Technology

[0002] Whether it's the power module used in charging piles, or vehicle power modules, military power modules, or general power modules, they all typically use LLC resonant converters to achieve high-frequency resonant soft-switching control.

[0003] Generally, LLC resonant converters employ a control strategy of parallel voltage and current loops. For example, a 1500W module with an output voltage of 24V and a full load capacity of 63A will have a closed voltage loop and maintain an output voltage of 24V when the load is less than or equal to 63A, while the current loop remains open. As the load increases, the voltage loop opens and the current loop closes. With increasing load, the voltage decreases more and more, and the current loop maintains an output of 63A. However, in this control strategy, if the load is suddenly increased or decreased, output voltage oscillations or overshoots can easily occur when switching control loops, affecting system stability. Summary of the Invention

[0004] In view of this, embodiments of the present invention provide a control method, apparatus and electronic device for an LLC resonant converter, so as to achieve smooth switching of the control loop of the LLC resonant converter and improve system stability.

[0005] The first aspect of this invention provides a control method for an LLC resonant converter. The LLC resonant converter adopts a parallel control method of voltage loop and current loop. In each control cycle, only one control loop controls the LLC resonant converter. This control loop is either a voltage loop or a current loop.

[0006] The control methods for LLC resonant converters include:

[0007] Determine whether the control loop needs to be switched in the current control cycle;

[0008] If the current control cycle needs to switch from the voltage loop to the current loop, the current loop PI output of the previous control cycle is updated to the voltage loop PI output of the previous control cycle. The voltage loop PI output of the current control cycle is calculated based on the voltage loop PI output of the previous control cycle, and the current loop PI output of the current control cycle is calculated based on the updated current loop PI output of the previous control cycle. The smaller value between the voltage loop PI output and the current loop PI output of the current control cycle is selected to control the LLC resonant converter.

[0009] If the current control cycle needs to switch from the current loop to the voltage loop, the voltage loop PI output of the previous control cycle is updated to the current loop PI output of the previous control cycle. The current loop PI output of the current control cycle is calculated based on the current loop PI output of the previous control cycle, and the voltage loop PI output of the current control cycle is calculated based on the updated voltage loop PI output of the previous control cycle. The smaller value between the voltage loop PI output and the current loop PI output of the current control cycle is selected to control the LLC resonant converter.

[0010] Optionally, determine whether the control loop needs to be switched in the current control cycle, including:

[0011] The control parameters are obtained by acquiring the output voltage error and output current error of the LLC resonant converter in the current control cycle, as well as the voltage loop PI output and current loop PI output of the previous control cycle.

[0012] If the control loop of the previous control cycle was a voltage loop, then determine whether the conditions for switching to a current loop are met based on the control parameters. If they are met, then it is determined that the voltage loop needs to be switched to a current loop in the current control cycle.

[0013] If the control loop of the previous control cycle was a current loop, then the control parameters are used to determine whether the conditions for switching to a voltage loop are met. If they are met, then the current control cycle needs to switch the current loop to a voltage loop.

[0014] Optionally, the conditions for switching to the current loop are:

[0015] The output voltage error of the LLC resonant converter in the current control cycle is greater than the output voltage error of the LLC resonant converter in the previous control cycle, and the difference between the two is greater than the first preset threshold.

[0016] And the voltage loop PI output of the previous control cycle is less than the current loop PI output of the previous control cycle.

[0017] Optionally, the conditions for switching to the voltage loop are:

[0018] The output current error of the LLC resonant converter in the current control cycle is greater than the output current error of the LLC resonant converter in the previous control cycle, and the difference between the two is greater than the second preset threshold.

[0019] And the current loop PI output of the previous control cycle is less than the voltage loop PI output of the previous control cycle.

[0020] Optionally, the voltage loop PI output for the current control cycle is calculated based on the voltage loop PI output of the previous control cycle, including:

[0021] Calculate Vpiout0 = Vpiout1 + Ka * Verr0 - Kb * Verr1, and limit Vpiout0 to use it as the voltage loop PI output for the current control cycle; where Vpiout1 is the voltage loop PI output of the previous control cycle, Verr0 is the output voltage error of the LLC resonant converter in the current control cycle, Verr1 is the output voltage error of the LLC resonant converter in the previous control cycle, and Ka and Kb are preset coefficients.

[0022] Optionally, the current loop PI output for the current control cycle is calculated based on the current loop PI output of the previous control cycle, including:

[0023] Calculate Ipiout0 = Ipiout1 + Ka * Ierr0 - Kb * Ierr1, and limit Ipiout0 to use as the current loop PI output for the current control cycle; where Ipiout1 is the current loop PI output of the previous control cycle, Ierr0 is the output current error of the LLC resonant converter in the current control cycle, Ierr1 is the output current error of the LLC resonant converter in the previous control cycle, and Ka and Kb are preset coefficients.

[0024] Optionally, if the current control cycle does not require switching the control loop, the voltage loop PI output of the current control cycle is directly calculated based on the voltage loop PI output of the previous control cycle, and the current loop PI output of the current control cycle is directly calculated based on the current loop PI output of the previous control cycle. The smaller value is selected from the voltage loop PI output and the current loop PI output of the current control cycle to control the LLC resonant converter.

[0025] A second aspect of the present invention provides a control device for an LLC resonant converter. The LLC resonant converter adopts a parallel control method of voltage loop and current loop. In each control cycle, only one control loop controls the LLC resonant converter. The control loop is either a voltage loop or a current loop.

[0026] The control device for the LLC resonant converter includes:

[0027] The judgment module is used to determine whether the control loop needs to be switched in the current control cycle;

[0028] The control module is used to update the current loop PI output of the previous control cycle to the voltage loop PI output of the previous control cycle if the current control cycle needs to switch from the voltage loop to the current loop. It then calculates the voltage loop PI output of the current control cycle based on the voltage loop PI output of the previous control cycle, calculates the current loop PI output of the current control cycle based on the updated current loop PI output of the previous control cycle, and selects the smaller value from the voltage loop PI output and current loop PI output of the current control cycle to control the LLC resonant converter. Conversely, if the current control cycle needs to switch from the current loop to the voltage loop, the module updates the voltage loop PI output of the previous control cycle to the current loop PI output of the previous control cycle, calculates the current loop PI output of the current control cycle based on the current loop PI output of the previous control cycle, calculates the current loop PI output of the current control cycle based on the updated voltage loop PI output of the previous control cycle, and selects the smaller value from the voltage loop PI output and current loop PI output of the current control cycle to control the LLC resonant converter.

[0029] A third aspect of the present invention provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the control method for the LLC resonant converter as described in the first aspect above.

[0030] A fourth aspect of the present invention provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of the control method for the LLC resonant converter as described in the first aspect above.

[0031] The beneficial effects of the embodiments of the present invention compared with the prior art are as follows:

[0032] This invention addresses the issue that output voltage oscillations during control loop switching occur because both loops are open. Therefore, when switching from a voltage loop to a current loop, the voltage loop PI output from the previous control cycle is assigned to the current loop PI output value from the previous control cycle. This accelerates the closing speed of the current loop, achieving the effect that when one loop is open, the other loop approaches closed loop status. The same principle applies when switching from a current loop to a voltage loop. This invention minimizes the time gap between the two open loops, ensuring smooth control loop switching and thus improving system response speed and stability. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 This is a schematic diagram of parallel control of a conventional LLC resonant converter provided in an embodiment of the present invention;

[0035] Figure 2 This is a flowchart of the parallel control of a conventional LLC resonant converter provided in an embodiment of the present invention;

[0036] Figure 3 This is a flowchart of the control method for an LLC resonant converter provided in an embodiment of the present invention;

[0037] Figure 4 This is a schematic diagram of the control method for an LLC resonant converter provided in an embodiment of the present invention;

[0038] Figure 5 This is a control flowchart provided in an embodiment of the present invention when the voltage loop is switched to the current loop;

[0039] Figure 6 This is a control flowchart provided in an embodiment of the present invention when the current loop is switched to the voltage loop;

[0040] Figure 7 This is a structural diagram of the control device for the LLC resonant converter provided in an embodiment of the present invention;

[0041] Figure 8 This is a structural diagram of the electronic device provided in an embodiment of the present invention. Detailed Implementation

[0042] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of the invention. However, those skilled in the art will understand that the invention can be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods are omitted so as not to obscure the description of the invention with unnecessary detail.

[0043] To illustrate the technical solution described in this invention, specific embodiments are described below.

[0044] When a power module is operating in the voltage loop, a sudden application of a full load or a load heavier than full load can cause output voltage oscillations when switching from the voltage loop to the current loop. Conversely, when the power module is operating in the current loop, removing a full load or a load heavier than full load can cause output voltage oscillations or overshoots when switching from the current loop to the voltage loop. The inventors of this application have discovered that the output voltage oscillations during the switching between the voltage loop and the current loop occur because both loops are open during the switching process. Therefore, based on the idea that "if one loop is open during switching, the other loop approaches a closed loop," a smooth switching method for the voltage loop and current loop for LLC topologies has been designed.

[0045] The method in this embodiment is applicable to schemes that control LLC resonant converters with parallel voltage and current loops. For conventional control strategies, see [link to relevant documentation]. Figure 1 and Figure 2 As shown, the voltage reference value Vref is subtracted from the voltage sampling value Vout to obtain the voltage error value Verr0. The current error value is limited, and the previous voltage loop error value Verr1 is updated with the current voltage loop error value Verr0. The voltage loop PI output Vpiout is calculated and limited. The current reference value Iref is subtracted from the current sampling value Iout to obtain the current error value Ierr0. The current error value is limited, and the previous current loop error value Ierr1 is updated with the current current loop error value Ierr0. The current loop PI output Ipiout is calculated and limited. The smaller value between Vpiout and Ipiout is selected as the final PI output value. The final PI output value is used to change the value of the PWM period register in real time, thereby modifying the operating frequency in real time. This process realizes frequency modulation control.

[0046] When switching control loops, taking the switch from voltage loop to current loop as an example, the following situations may occur:

[0047] When a sudden load is applied, the voltage loop is about to open. The voltage error value Verr0 of the current control cycle is larger than the voltage error value Verr1 of the previous control cycle, indicating that the voltage loop is showing signs of closed-loop failure. Although the voltage loop is about to open, the current loop also remains open, or even more severely so. Therefore, the current loop selection is still the voltage loop, which is still trying its best to close. However, the voltage loop closure is already nominal and can no longer achieve effective control. The system is showing a tendency to switch to the current loop, but at this time, the current loop is also open. It will take several control cycles for the current loop to close. At this point, it is equivalent to both loops being open, causing output voltage oscillation.

[0048] See Figure 3 As shown, this embodiment of the invention provides a control method for an LLC resonant converter, which includes the following steps:

[0049] Step S101: Determine whether the control loop needs to be switched in the current control cycle.

[0050] In this embodiment, when the load changes, if the current control loop (voltage loop or current loop) can no longer effectively control the LLC resonant converter, it is necessary to switch to another control loop.

[0051] Step S1021: If the current control cycle needs to switch from voltage loop to current loop, then update the current loop PI output of the previous control cycle to the voltage loop PI output of the previous control cycle. Calculate the voltage loop PI output of the current control cycle based on the voltage loop PI output of the previous control cycle, and calculate the current loop PI output of the current control cycle based on the updated current loop PI output of the previous control cycle. Select the smaller value from the voltage loop PI output and the current loop PI output of the current control cycle to control the LLC resonant converter.

[0052] Step S1022: If the current control cycle needs to switch from the current loop to the voltage loop, then update the voltage loop PI output of the previous control cycle to the current loop PI output of the previous control cycle. Calculate the current loop PI output of the current control cycle based on the current loop PI output of the previous control cycle, and calculate the voltage loop PI output of the current control cycle based on the updated voltage loop PI output of the previous control cycle. Select the smaller value from the voltage loop PI output and the current loop PI output of the current control cycle to control the LLC resonant converter.

[0053] In this embodiment, to ensure smooth switching of the control loops, when the switching conditions are met, once one loop transitions from a closed loop to an open loop, the other loop is immediately brought infinitely closer to a closed loop, thus minimizing the time interval between the two loops becoming open. For details, see [link to documentation]. Figure 4 As shown:

[0054] When the voltage loop is closed, there is a voltage loop switching to current loop judgment, that is, it is judged whether the conditions for switching from voltage loop to current loop are met. If the conditions are met, the voltage loop PI output of the previous control cycle is assigned to the current loop PI output value of the previous control cycle, thereby accelerating the current loop closure and realizing a smooth switching adjustment process. If the switching conditions are not met, no adjustment is performed and PI control is performed directly.

[0055] When the current loop is closed, there is a current loop to voltage loop switching judgment, that is, to determine whether the conditions for switching from the current loop to the voltage loop are met. If the conditions are met, the current loop PI output of the previous control cycle is assigned to the voltage loop PI output value of the previous control cycle, thereby accelerating the voltage loop closure and realizing a smooth switching adjustment process. If the switching conditions are not met, no adjustment is performed and PI control is performed directly.

[0056] As can be seen, the embodiments of the present invention take into account that the output voltage oscillation during control loop switching is due to the phenomenon of both loops being open. Therefore, when switching from the voltage loop to the current loop, the PI output value of the voltage loop in the previous control cycle is assigned to the PI output value of the current loop in the previous control cycle, thereby accelerating the closing speed of the current loop. This achieves the effect that when one loop is open, the other loop approaches closed loop almost instantly. The same principle applies when switching from the current loop to the voltage loop. The present invention can minimize the time interval between the two loops being open, ensuring smooth switching of the control loop, thereby improving the system's response speed and stability.

[0057] As one possible implementation, step S101, determining whether the control loop needs to be switched in the current control cycle, can be detailed as follows:

[0058] The control parameters are obtained by acquiring the output voltage error and output current error of the LLC resonant converter in the current control cycle, as well as the voltage loop PI output and current loop PI output of the previous control cycle.

[0059] If the control loop of the previous control cycle was a voltage loop, then determine whether the conditions for switching to a current loop are met based on the control parameters. If they are met, then it is determined that the voltage loop needs to be switched to a current loop in the current control cycle.

[0060] If the control loop of the previous control cycle was a current loop, then the control parameters are used to determine whether the conditions for switching to a voltage loop are met. If they are met, then the current control cycle needs to switch the current loop to a voltage loop.

[0061] Furthermore, the conditions for switching to the current loop are:

[0062] The output voltage error of the LLC resonant converter in the current control cycle is greater than the output voltage error of the LLC resonant converter in the previous control cycle, and the difference between the two is greater than the first preset threshold.

[0063] And the voltage loop PI output of the previous control cycle is less than the current loop PI output of the previous control cycle.

[0064] Furthermore, the conditions for switching to the voltage loop are:

[0065] The output current error of the LLC resonant converter in the current control cycle is greater than the output current error of the LLC resonant converter in the previous control cycle, and the difference between the two is greater than the second preset threshold.

[0066] And the current loop PI output of the previous control cycle is less than the voltage loop PI output of the previous control cycle.

[0067] In this embodiment, taking the switching to the current loop as an example, if the output voltage error of the LLC resonant converter in the current control cycle is greater than the output voltage error of the LLC resonant converter in the previous control cycle, and the difference between the two is greater than a first preset threshold, it means that the voltage loop is about to open. The current error is larger than the previous error plus a small threshold, indicating that the voltage loop has shown signs of closing. If the voltage loop PI output in the previous control cycle is less than the current loop PI output in the previous control cycle, it means that although the voltage loop is about to open, the current loop is also open, or even more severely open. Therefore, the current loop selection remains the voltage loop, which is still trying to close. If both conditions are met simultaneously, it means that the voltage loop should be switched to the current loop. However, since the current loop is more open than the voltage loop, it means that relying on the system's own PI regulation to achieve current loop closure will take some time. Therefore, to accelerate the closure speed, the PI output value of the current loop needs to be as close as possible to the closed loop. Since the voltage loop has just exited the closed loop, the PI output value of the voltage loop is very close to the PI output value of the closed loop. Therefore, assigning the PI output of the voltage loop to the PI output of the current loop can achieve the rapid closure of the current loop.

[0068] As one possible implementation, the voltage loop PI output for the current control cycle is calculated based on the voltage loop PI output of the previous control cycle, which can be described in detail as follows:

[0069] Calculate Vpiout0 = Vpiout1 + Ka * Verr0 - Kb * Verr1, and limit Vpiout0 to use it as the voltage loop PI output for the current control cycle; where Vpiout1 is the voltage loop PI output of the previous control cycle, Verr0 is the output voltage error of the LLC resonant converter in the current control cycle, Verr1 is the output voltage error of the LLC resonant converter in the previous control cycle, and Ka and Kb are preset coefficients.

[0070] As one possible implementation, the current loop PI output for the current control cycle is calculated based on the current loop PI output of the previous control cycle, which can be described in detail as follows:

[0071] Calculate Ipiout0 = Ipiout1 + Ka * Ierr0 - Kb * Ierr1, and limit Ipiout0 to use as the current loop PI output for the current control cycle; where Ipiout1 is the current loop PI output of the previous control cycle, Ierr0 is the output current error of the LLC resonant converter in the current control cycle, Ierr1 is the output current error of the LLC resonant converter in the previous control cycle, and Ka and Kb are preset coefficients.

[0072] As one possible implementation, regardless of whether the current voltage loop or current loop is closed, if the conditions for the corresponding switching control loop mentioned above are not met, the voltage loop PI output of the current control cycle is directly calculated based on the voltage loop PI output of the previous control cycle, and the current loop PI output of the current control cycle is directly calculated based on the current loop PI output of the previous control cycle. The smaller value is selected from the voltage loop PI output and the current loop PI output of the current control cycle to control the LLC resonant converter.

[0073] Based on the above, when the previous cycle was voltage loop control, the following was executed: Figure 5 The steps shown are as follows:

[0074] Step 1: Subtract the voltage sample value Vout from the voltage reference value Vref to obtain the voltage error value Verr0. Limit the current error value and then proceed to step 2.

[0075] Step 2: Determine whether the current voltage loop error value Verr0 is greater than the previous voltage loop error value Verr1 plus a preset threshold, and whether the current loop PI output Ipiout1 of the previous control cycle is greater than the voltage loop PI output Vpiout1 of the previous control cycle. If they are met, assign the voltage loop PI output Vpiout1 of the previous control cycle to the current loop PI output Ipiout1, and proceed to step 3; otherwise, proceed directly to step 3.

[0076] Step 3: Perform voltage loop closure, and simultaneously update the previous voltage loop error value Verr1 with the current voltage loop error value Verr0. Limit the current voltage loop PI output Vpiout0, and proceed to step 4.

[0077] Step 4: Subtract the current sampling value Iout from the current reference value Iref to obtain the current error value Ierr0, and limit the current error value before proceeding to step 5.

[0078] Step 5: Perform current loop closure, and simultaneously update the previous current loop error value Ierr1 with the current current loop error value Ierr0. Limit the current loop PI output Ipiout0, and proceed to step 6.

[0079] Step 6: Select the smaller value between Vpiout0 and Ierr0 as the final PI output value.

[0080] Based on the above, when the previous cycle was current loop control, the following was executed: Figure 6 The steps shown are as follows:

[0081] Step 1: Subtract the current sampling value Iout from the current reference value Iref to obtain the current error value Ierr0. Limit the current error value and then proceed to step 2.

[0082] Step 2: Determine whether the current loop error value Ierr0 is greater than the previous current loop error value Ierr1 plus a preset threshold, and whether the voltage loop PI output Vpiout1 of the previous control cycle is greater than the current loop PI output Ipiout1 of the previous control cycle. If they are met, assign the current loop PI output Ipiout1 of the previous control cycle to the voltage loop PI output Vpiout1, and proceed to step 3; otherwise, proceed directly to step 3.

[0083] Step 3: Perform current loop closure, and simultaneously update the previous current loop error value Ierr1 with the current current loop error value Ierr0. Limit the current loop PI output Ipiout0, and proceed to step 4.

[0084] Step 4: Subtract the voltage sample value Vout from the voltage reference value Vref to obtain the voltage error value Verr0, and limit the current error value before proceeding to step 5.

[0085] Step 5: Perform voltage loop closure, and simultaneously update the previous voltage loop error value Verr1 with the current voltage loop error value Verr0. Limit the current voltage loop PI output Vpiout0, and proceed to step 6.

[0086] Step 6: Select the smaller value between Vpiout0 and Ierr0 as the final PI output value.

[0087] Through simulation experiments, using the smooth switching method of this invention, during sudden loading, the voltage loop can quickly switch to the current loop without generating prolonged voltage oscillations; during sudden deloading, the current loop can quickly switch back to the voltage loop without generating high voltage overshoot. This invention improves system stability by accelerating the entry into another loop and reducing the time gap between two open loops.

[0088] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0089] See Figure 7 As shown, this embodiment of the invention provides a control device for an LLC resonant converter. The LLC resonant converter adopts a parallel control method of voltage loop and current loop. In each control cycle, only one control loop controls the LLC resonant converter. This control loop is either a voltage loop or a current loop.

[0090] The control device 70 for the LLC resonant converter includes:

[0091] The judgment module 71 is used to determine whether the control loop needs to be switched in the current control cycle.

[0092] The control module 72 is configured to, if the current control cycle requires switching from the voltage loop to the current loop, update the current loop PI output of the previous control cycle to the voltage loop PI output of the previous control cycle, calculate the voltage loop PI output of the current control cycle based on the voltage loop PI output of the previous control cycle, calculate the current loop PI output of the current control cycle based on the updated current loop PI output of the previous control cycle, and select the smaller value from the voltage loop PI output and current loop PI output of the current control cycle to control the LLC resonant converter; if the current control cycle requires switching from the current loop to the voltage loop, update the voltage loop PI output of the previous control cycle to the current loop PI output of the previous control cycle, calculate the current loop PI output of the current control cycle based on the current loop PI output of the previous control cycle, calculate the voltage loop PI output of the current control cycle based on the updated voltage loop PI output of the previous control cycle, and select the smaller value from the voltage loop PI output and current loop PI output of the current control cycle to control the LLC resonant converter.

[0093] As one possible implementation, the judgment module 71 is specifically used for:

[0094] The control parameters are obtained by acquiring the output voltage error and output current error of the LLC resonant converter in the current control cycle, as well as the voltage loop PI output and current loop PI output of the previous control cycle.

[0095] If the control loop of the previous control cycle was a voltage loop, then determine whether the conditions for switching to a current loop are met based on the control parameters. If they are met, then it is determined that the voltage loop needs to be switched to a current loop in the current control cycle.

[0096] If the control loop of the previous control cycle was a current loop, then the control parameters are used to determine whether the conditions for switching to a voltage loop are met. If they are met, then the current control cycle needs to switch the current loop to a voltage loop.

[0097] As one possible implementation, the conditions for switching to a current loop are:

[0098] The output voltage error of the LLC resonant converter in the current control cycle is greater than the output voltage error of the LLC resonant converter in the previous control cycle, and the difference between the two is greater than the first preset threshold.

[0099] And the voltage loop PI output of the previous control cycle is less than the current loop PI output of the previous control cycle.

[0100] As one possible implementation, the conditions for switching to a voltage loop are:

[0101] The output current error of the LLC resonant converter in the current control cycle is greater than the output current error of the LLC resonant converter in the previous control cycle, and the difference between the two is greater than the second preset threshold.

[0102] And the current loop PI output of the previous control cycle is less than the voltage loop PI output of the previous control cycle.

[0103] As one possible implementation, control module 72 is specifically used for:

[0104] Calculate Vpiout0 = Vpiout1 + Ka * Verr0 - Kb * Verr1, and limit Vpiout0 to use it as the voltage loop PI output for the current control cycle; where Vpiout1 is the voltage loop PI output of the previous control cycle, Verr0 is the output voltage error of the LLC resonant converter in the current control cycle, Verr1 is the output voltage error of the LLC resonant converter in the previous control cycle, and Ka and Kb are preset coefficients.

[0105] As one possible implementation, control module 72 is specifically used for:

[0106] Calculate Ipiout0 = Ipiout1 + Ka * Ierr0 - Kb * Ierr1, and limit Ipiout0 to use as the current loop PI output for the current control cycle; where Ipiout1 is the current loop PI output of the previous control cycle, Ierr0 is the output current error of the LLC resonant converter in the current control cycle, Ierr1 is the output current error of the LLC resonant converter in the previous control cycle, and Ka and Kb are preset coefficients.

[0107] As one possible implementation, the control module 72 is also specifically used for:

[0108] If the current control cycle does not require switching the control loop, the voltage loop PI output of the current control cycle is directly calculated based on the voltage loop PI output of the previous control cycle, and the current loop PI output of the current control cycle is directly calculated based on the current loop PI output of the previous control cycle. The smaller value is selected from the voltage loop PI output and the current loop PI output of the current control cycle to control the LLC resonant converter.

[0109] Figure 8 This is a schematic diagram of an electronic device 80 provided in an embodiment of the present invention. Figure 8As shown, the electronic device 80 of this embodiment includes: a processor 81, a memory 82, and a computer program 83 stored in the memory 82 and executable on the processor 81, such as a control program for an LLC resonant converter. When the processor 81 executes the computer program 83, it implements the steps in the control method embodiments of the various LLC resonant converters described above. Alternatively, when the processor 81 executes the computer program 83, it implements the functions of each module in the various device embodiments described above, for example... Figure 7 The functions of modules 71 to 72 are shown.

[0110] For example, computer program 83 may be divided into one or more modules / units, one or more of which are stored in memory 82 and executed by processor 81 to complete the present invention. One or more modules / units may be a series of computer program instruction segments capable of performing a specific function, which describe the execution process of computer program 83 in electronic device 80.

[0111] Electronic device 80 can be a desktop computer, laptop, handheld computer, cloud server, or other computing device. Electronic device 80 may include, but is not limited to, a processor 81 and a memory 82. Those skilled in the art will understand that... Figure 8 This is merely an example of electronic device 80 and does not constitute a limitation on electronic device 80. It may include more or fewer components than shown, or combine certain components, or different components. For example, electronic device 80 may also include input / output devices, network access devices, buses, etc.

[0112] The processor 81 may be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor.

[0113] The memory 82 can be an internal storage unit of the electronic device 80, such as a hard disk or RAM of the electronic device 80. The memory 82 can also be an external storage device of the electronic device 80, such as a plug-in hard disk, Smart Media Card (SMC), Secure Digital (SD) card, or Flash Card equipped on the electronic device 80. Furthermore, the memory 82 can include both internal and external storage units of the electronic device 80. The memory 82 is used to store computer programs and other programs and data required by the electronic device 80. The memory 82 can also be used to temporarily store data that has been output or will be output.

[0114] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is merely an example. In practical applications, the above functions can be assigned to different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit. Furthermore, the specific names of the functional units and modules are only for easy differentiation and are not intended to limit the scope of protection of this application. The specific working process of the units and modules in the above system can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0115] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0116] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0117] In the embodiments provided by this invention, it should be understood that the disclosed devices / electronic devices and methods can be implemented in other ways. For example, the device / electronic device embodiments described above are merely illustrative. For instance, the division of modules or units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0118] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0119] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0120] If an integrated module / unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the methods of the above embodiments of the present invention can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include: any entity or device capable of carrying computer program code, recording media, USB flash drives, portable hard drives, magnetic disks, optical disks, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signals, telecommunication signals, and software distribution media, etc. It should be noted that the content included in the computer-readable medium can be appropriately added or removed according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, the computer-readable medium does not include electrical carrier signals and telecommunication signals.

[0121] 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, and should all be included within the protection scope of the present invention.

Claims

1. A control method for an LLC resonant converter, characterized in that, The LLC resonant converter adopts a parallel control method of voltage loop and current loop. In each control cycle, only one control loop controls the LLC resonant converter. This control loop is either the voltage loop or the current loop. The method includes: Determine whether the control loop needs to be switched in the current control cycle; If the current control cycle needs to switch from the voltage loop to the current loop, the current loop PI output of the previous control cycle is updated to the voltage loop PI output of the previous control cycle. The voltage loop PI output of the current control cycle is calculated based on the voltage loop PI output of the previous control cycle, and the current loop PI output of the current control cycle is calculated based on the updated current loop PI output of the previous control cycle. The smaller value between the voltage loop PI output and the current loop PI output of the current control cycle is selected to control the LLC resonant converter. If the current control cycle needs to switch from the current loop to the voltage loop, the voltage loop PI output of the previous control cycle is updated to the current loop PI output of the previous control cycle. The current loop PI output of the current control cycle is calculated based on the current loop PI output of the previous control cycle, and the voltage loop PI output of the current control cycle is calculated based on the updated voltage loop PI output of the previous control cycle. The smaller value between the voltage loop PI output and the current loop PI output of the current control cycle is selected to control the LLC resonant converter. Determining whether a control loop needs to be switched in the current control cycle includes: If the control loop of the previous control cycle was a voltage loop, then in the current control cycle, if the output voltage error of the LLC resonant converter is greater than the output voltage error of the LLC resonant converter in the previous control cycle and the difference between the two is greater than the first preset threshold, and the voltage loop PI output of the previous control cycle is less than the current loop PI output of the previous control cycle, it is determined that the voltage loop needs to be switched to the current loop in the current control cycle. If the control loop of the previous control cycle was a current loop, then in the current control cycle, if the output current error of the LLC resonant converter is greater than the output current error of the LLC resonant converter in the previous control cycle and the difference between the two is greater than the second preset threshold, and the current loop PI output of the previous control cycle is less than the voltage loop PI output of the previous control cycle, then it is determined that the current loop needs to be switched to the voltage loop in the current control cycle.

2. The control method for the LLC resonant converter as described in claim 1, characterized in that, The voltage loop PI output for the current control cycle is calculated based on the voltage loop PI output of the previous control cycle, including: Calculate Vpiout0 = Vpiout1 + Ka Verr0-Kb Verr1 is used as the voltage loop PI output for the current control cycle after limiting Vpiout0; where Vpiout1 is the voltage loop PI output of the previous control cycle, Verr0 is the output voltage error of the LLC resonant converter in the current control cycle, Verr1 is the output voltage error of the LLC resonant converter in the previous control cycle, and Ka and Kb are preset coefficients.

3. The control method for the LLC resonant converter as described in claim 1, characterized in that, The current loop PI output for the current control cycle is calculated based on the current loop PI output of the previous control cycle, including: Calculate Ipiout0 = Ipiout1 + Ka Ierr0-Kb Ierr1 is used as the current loop PI output for the current control cycle after Ipiout0 is limited; where Ipiout1 is the current loop PI output of the previous control cycle, Ierr0 is the output current error of the LLC resonant converter in the current control cycle, Ierr1 is the output current error of the LLC resonant converter in the previous control cycle, and Ka and Kb are preset coefficients.

4. The control method for the LLC resonant converter as described in any one of claims 1-3, characterized in that, If the current control cycle does not require switching the control loop, the voltage loop PI output of the current control cycle is directly calculated based on the voltage loop PI output of the previous control cycle, and the current loop PI output of the current control cycle is directly calculated based on the current loop PI output of the previous control cycle. The smaller value is selected from the voltage loop PI output and the current loop PI output of the current control cycle to control the LLC resonant converter.

5. A control device for an LLC resonant converter, characterized in that, The LLC resonant converter adopts a parallel control method of voltage loop and current loop. In each control cycle, only one control loop controls the LLC resonant converter. This control loop is either the voltage loop or the current loop. The device includes: The judgment module is used to determine whether the control loop needs to be switched in the current control cycle; The control module is configured to, if the current control cycle requires switching from the voltage loop to the current loop, update the current loop PI output of the previous control cycle to the voltage loop PI output of the previous control cycle, calculate the voltage loop PI output of the current control cycle based on the voltage loop PI output of the previous control cycle, calculate the current loop PI output of the current control cycle based on the updated current loop PI output of the previous control cycle, and select the smaller value from the voltage loop PI output and current loop PI output of the current control cycle to control the LLC resonant converter; if the current control cycle requires switching from the current loop to the voltage loop, update the voltage loop PI output of the previous control cycle to the current loop PI output of the previous control cycle, calculate the current loop PI output of the current control cycle based on the current loop PI output of the previous control cycle, calculate the voltage loop PI output of the current control cycle based on the updated voltage loop PI output of the previous control cycle, and select the smaller value from the voltage loop PI output and current loop PI output of the current control cycle to control the LLC resonant converter. Determining whether a control loop needs to be switched in the current control cycle includes: If the control loop of the previous control cycle was a voltage loop, then in the current control cycle, if the output voltage error of the LLC resonant converter is greater than the output voltage error of the LLC resonant converter in the previous control cycle and the difference between the two is greater than the first preset threshold, and the voltage loop PI output of the previous control cycle is less than the current loop PI output of the previous control cycle, it is determined that the voltage loop needs to be switched to the current loop in the current control cycle. If the control loop of the previous control cycle was a current loop, then in the current control cycle, if the output current error of the LLC resonant converter is greater than the output current error of the LLC resonant converter in the previous control cycle and the difference between the two is greater than the second preset threshold, and the current loop PI output of the previous control cycle is less than the voltage loop PI output of the previous control cycle, then it is determined that the current loop needs to be switched to the voltage loop in the current control cycle.

6. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the method as described in any one of claims 1 to 4.

7. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by a processor, it implements the steps of the method as described in any one of claims 1 to 4.

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