LLC resonant converter in charging module, control method of LLC resonant converter and computer equipment

Abstract

The invention belongs to the technical field of LLC resonant converters, and particularly relates to an LLC resonant converter in a charging module, a control method of the LLC resonant converter and computer equipment. The method comprises the steps that when the load of a charging module drops suddenly, if the absolute value of the voltage error between the given voltage and the output voltage of the charging module is smaller than a set voltage error threshold value, a corresponding control mode is executed according to the adjustment result of the voltage error to adjust the driving pulse of the LLC resonant converter so as to reduce the output voltage of the charging module; wherein when the frequency of the driving pulse is smaller than the upper limit of the frequency of the driving pulse, the executed control mode is a PFM control mode used for increasing the frequency of the driving pulse; when the width of the driving pulse is greater than the lower limit of the width of the driving pulse, the executed control mode is a PWM control mode for reducing the width of the driving pulse; when the frequency of the driving pulse is greater than or equal to the upper frequency limit of the driving pulse and the width is less than or equal to the lower width limit of the driving pulse, the executed control mode is a Burst control mode.

Description

Technical Field

[0001] The present invention belongs to the technical field of LLC resonant converters, and in particular relates to an LLC resonant converter in a charging module, a control method thereof, and a computer device. Background Art

[0002] In the prior art, LLC resonant converters are widely used in charging modules. When a charging module based on LLC resonant converter experiences a sudden drop in output load (such as load shedding), the output voltage will change transiently. At this time, it is usually necessary to turn off the drive pulse of the switch device of the LLC resonant converter. This measure can reduce the transient value of the output voltage, but at the same time it will cause a large stress spike in the LLC switch device, resulting in excessive stress and possible damage to the switch device.

[0003] In order to solve the technical problem that the driving pulse of the LLC resonant converter switching device is turned off when the charging module is unloaded, the stress exceeds the standard and damages the switching device, the prior art proposes technical means to solve the problem from the hardware level, such as selecting a switching device that can withstand greater stress and adding an RCD absorption circuit. However, while solving the problem, the cost of the charging module is also increased. Summary of the invention

[0004] The object of the present invention is to provide an LLC resonant converter in a charging module and a control method and computer equipment thereof, so as to solve the technical problem of high cost caused by improving the hardware to prevent damage to the LLC resonant converter switching device caused by a sudden drop in the charging module load.

[0005] In order to solve the above technical problems, the present invention provides a control method of an LLC resonant converter in a charging module, the method comprising: When the load of the charging module drops suddenly, if the absolute value of the voltage error between the given voltage and the output voltage of the charging module is less than the set voltage error threshold, a corresponding control mode is executed according to the adjustment result of the voltage error to adjust the driving pulse of the LLC resonant converter to reduce the output voltage of the charging module; Among them, when the frequency of the driving pulse is less than the upper limit of the frequency of the driving pulse, the executed control mode is the PFM control mode for increasing the frequency of the driving pulse; when the width of the driving pulse is greater than the lower limit of the width of the driving pulse, the executed control mode is the PWM control mode for reducing the width of the driving pulse; when the frequency of the driving pulse is greater than or equal to the upper limit of the frequency of the driving pulse, and the width is less than or equal to the lower limit of the width of the driving pulse, the executed control mode is the Burst control mode.

[0006] Furthermore, when the frequency of the driving pulse is less than the upper limit of the frequency of the driving pulse, and the width is greater than the lower limit of the width of the driving pulse, the PFM control mode is preferentially used.

[0007] Furthermore, when the absolute value of the voltage error is greater than or equal to a set error threshold, the driving pulse is turned off.

[0008] Furthermore, the method also includes: when the charging module operates normally, adjusting the drive pulse according to the smaller value of the adjustment value of the voltage error and the adjustment value of the current error, the voltage error is the given voltage of the charging module minus the output voltage, and the current error is the given current of the charging module minus the output current.

[0009] Further, the adjustment value of the voltage error is a PI adjustment value of the voltage error.

[0010] Further, the adjustment value of the current error is a PI adjustment value of the current error.

[0011] The present invention is a pioneering invention, and its beneficial effects are as follows: the control method of the LLC resonant converter in the charging module of the present invention, after the load of the charging module is reduced and the output voltage is increased, if the absolute value of the error between the voltage set value and the output voltage is less than the set voltage error threshold, the driving pulse of the LLC switch device is modulated according to the voltage error to reduce the output voltage of the charging module. The method for adjusting the driving pulse includes: if the frequency of the driving pulse does not exceed the upper limit, the driving pulse frequency is increased through the PFM mode; if the width of the driving pulse is not lower than the lower limit, the driving pulse width is reduced through the PWM mode; if the frequency of the driving pulse exceeds the upper limit and the width is less than the lower limit, the driving pulse is intermittently closed through the Burst mode. By adjusting the driving pulse, the output voltage of the charging module is reduced, thereby reducing the absolute value of the error between the voltage set value and the output voltage. While adjusting the output voltage, the driving pulse will not be directly closed, which can avoid damage to the LLC switch device of the charging module, and there is no need to increase the hardware circuit of the charging module or replace the switch device that can withstand greater stress, without increasing the hardware cost.

[0012] To solve the above technical problems, the present invention further provides a computer device, comprising a processor, wherein the processor implements the method steps described in the control method of the LLC resonant converter in the charging module of the present invention when executing a computer program.

[0013] The present invention is a pioneering invention, and its beneficial effects are the same as those of the control method of the LLC resonant converter in the charging module of the present invention.

[0014] To solve the above technical problems, the present invention also provides an LLC resonant converter in a charging module, including an LLC controller, the LLC controller including a processor, and the processor implements the method steps described in the control method of the LLC resonant converter in the charging module of the present invention when executing a computer program.

[0015] The present invention is a pioneering invention, and its beneficial effects are the same as those of the control method of the LLC resonant converter in the charging module of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a control principle diagram of the charging module of the method embodiment of the present invention when it is operating normally; Figure 2 is a control principle diagram of a charging module when load dump occurs in a method embodiment of the present invention; Figure 3 The flowchart of adjusting the driving pulse according to the method embodiment of the present invention. DETAILED DESCRIPTION

[0017] The LLC resonant converter in a charging module of the present invention and its control method and computer equipment, after the load of the charging module is reduced and the output voltage is increased, if the absolute value of the error between the voltage set value and the output voltage is less than the set voltage error threshold, the driving pulse of the LLC switch device is modulated according to the voltage error to reduce the output voltage of the charging module. The method for adjusting the driving pulse includes: if the frequency of the driving pulse does not exceed the upper limit, the driving pulse frequency is increased through the PFM mode; if the width of the driving pulse is not lower than the lower limit, the driving pulse width is reduced through the PWM mode; if the frequency of the driving pulse exceeds the upper limit and the width is less than the lower limit, the driving pulse is intermittently closed through the Burst mode. By adjusting the driving pulse, the output voltage of the charging module is reduced, thereby reducing the absolute value of the error between the voltage set value and the output voltage. The driving pulse will not be directly closed while adjusting the output voltage, which can avoid damage to the LLC switch device of the charging module, and there is no need to increase the hardware circuit of the charging module or replace the switch device that can withstand greater stress, without increasing the hardware cost.

[0018] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0019] Method Example: The control method of the LLC resonant converter in the charging module of the present invention does not require modification or addition of hardware circuits, does not increase costs, and only requires improving software to reduce the voltage transient peak value of the load dump to within the range required by the standard; it can avoid the stress exceeding standard problem caused by the prior art. The specific method is as follows: When the charging module of this embodiment operates normally, the controller of the LLC resonant converter adopts voltage and current dual-loop parallel control, such as Figure 1 As shown, the voltage given value U ref And the output voltage sampling value U out The difference U error As the input value of PI controller 1, the output value of the voltage loop is obtained after PI controller 1; the current given value I ref The output voltage sampling value I out The difference current error I error As the input value of PI controller 2, the output value of the current loop is obtained after PI controller 2; the minimum value of the voltage loop and the current loop output value is taken as the output value of the overall loop; finally, the frequency f or pulse width delta is adjusted according to the output value of the overall loop to adjust the drive pulse.

[0020] When the charging module suddenly reduces its load, the voltage setting value U ref unchanged, output voltage U out Increases, at this time the voltage loop error U error It is a negative value with a large absolute value. The output of the voltage control branch is smaller than the output of the current control branch. The output of the entire control loop is the voltage loop error U error Therefore, in this embodiment, the LLC controller can adopt voltage regulation control when the load of the charging module drops suddenly, such as Figure 2 As shown, the adjustment value of the voltage error between the given voltage and the output voltage of the charging module is directly used as the input of the drive pulse adjustment, and the corresponding control mode is selected to adjust the drive pulse.

[0021] Specific methods for adjusting the drive pulse, such as Figure 3 As shown, the following steps are included: Step 1: Determine whether the absolute value of the voltage error between the given voltage and the output voltage of the charging module is less than a set voltage error threshold.

[0022] In this embodiment, the voltage error between the given voltage and the output voltage of the charging module is the voltage loop error U error , set the voltage error threshold to set the voltage loop error threshold U errorSet When comparing, we only need to convert the voltage loop error U error And set the voltage loop error threshold U errorSet By comparing, it can be determined whether the absolute value of the error between the given voltage and the output voltage of the charging module is less than the set voltage error threshold.

[0023] If the voltage loop error U error Greater than or equal to the set voltage loop error threshold U errorSetAt this time, the absolute value of the voltage loop error is less than the set voltage error threshold. The output voltage of the charging module can be reduced by adjusting the driving pulse of the LLC switch device, thereby increasing the voltage loop error U error , reducing the absolute value of the voltage loop error to make it close to zero. Therefore, at this time, the subsequent steps are to increase the voltage loop error U by frequency modulation and width modulation of the driving pulse of the switching device. error .

[0024] If the voltage loop error U error If the absolute value of the voltage loop error is greater than or equal to the set voltage loop error threshold, the driving pulse of the switching device of the LLC resonant converter can be turned off. At this time, the output voltage of the charging module after load reduction is greatly increased. At this time, the driving pulse needs to be turned off to reduce the output voltage of the charging module as quickly as possible.

[0025] Step 2: Determine whether the frequency f of the drive pulse is less than the upper limit f of the drive pulse frequency uplimt .

[0026] If the drive pulse frequency f is less than the drive frequency upper limit f uplimt PFM control is used to modulate the frequency of the drive pulse according to the overall output value of the control loop to increase the frequency of the drive pulse. Since the frequency of the drive pulse is inversely proportional to the output voltage of the charging module, the higher the drive pulse frequency, the lower the output voltage of the charging module. Therefore, when the frequency of the drive pulse does not reach the upper limit, the frequency of the drive pulse can be increased through PFM control to reduce the output voltage of the charging module, thereby increasing the voltage loop error U. error , reduce the absolute value of the voltage loop error. After entering the PFM control mode, the drive pulse modulation process ends.

[0027] If the frequency f of the driving pulse is greater than or equal to the upper limit of the driving pulse frequency f uplimt , it is no longer possible to use the PFM control mode to reduce the voltage loop error by increasing the frequency of the drive pulse and enter the subsequent drive pulse modulation process.

[0028] Step 3: Determine whether the width of the driving pulse is greater than the lower limit of the driving pulse width.

[0029] If the width of the driving pulse is greater than the lower limit of the driving pulse width, the PWM control mode is used to adjust the width of the driving pulse according to the output value of the entire control loop. Since the width of the driving pulse is proportional to the output voltage of the charging module, the PWM control mode can reduce the width of the driving pulse to reduce the output voltage of the charging module, thereby reducing the voltage loop error U error After entering the PFM control mode, the drive pulse modulation process ends.

[0030] If the width of the driving pulse is less than or equal to the lower limit of the driving pulse width, it is no longer possible to reduce the output voltage of the charging module by reducing the width of the driving pulse, thereby reducing the voltage loop error U. error , it is necessary to enter the subsequent process to modulate the pulse.

[0031] Step 4: Use the Burst control mode to modulate the drive pulse.

[0032] In the Burst control mode, the output voltage of the charging module is reduced by regularly opening and closing the drive pulse and hiccuping the output, thereby reducing the voltage loop error.

[0033] Through the above-mentioned drive pulse modulation process, after the charging module is unloaded, when the output voltage rises to be greater than the voltage given value, if the absolute value of the difference between the voltage given value and the output voltage is small, the control method of the LLC resonant converter in the charging module of the present invention can reduce the output voltage by modulating the drive pulse, without directly turning off the drive pulse, and can prevent the stress spike when the drive pulse is turned off from causing damage to the LLC switch device. Specifically, since the PFM control mode is more suitable for use under heavy load conditions and the PWM control mode is more suitable for use under light load conditions, the PFM control mode is preferentially used in this embodiment to reduce the output voltage of the charging module by increasing the frequency of the drive pulse; when the pulse frequency increases to the upper limit of the pulse frequency and cannot be adjusted, the PWM mode is used again to reduce the output voltage of the charging module by reducing the pulse width. In this embodiment, when the width of the drive pulse reaches the lower limit and cannot be adjusted, the Burst control mode is used to reduce the output voltage of the charging module by regularly opening and closing the drive pulse, which can reduce the stress spike and is not easy to damage the LLC switch device. Only when the absolute value of the difference between the voltage setting value and the output voltage is large and greater than the absolute value of the set voltage loop error threshold, the output voltage of the charging module is reduced by turning off the drive pulse.

[0034] In this embodiment, the voltage error between the given voltage and the output voltage of the charging module is the voltage loop error U error It is equal to the voltage given value minus the output voltage of the charging module. When the load of the charging module drops suddenly, the output voltage of the charging module rises, so the voltage loop error U error As another implementation, the error between the given voltage and the output voltage of the charging module may also be equal to the output voltage of the voltage module minus the given voltage value, which is a positive value during the load reduction process.

[0035] According to the industry standard of the charging module, when the DC circuit load drops suddenly, the maximum peak voltage output by the charging module should not be greater than the larger value of 110% of the voltage limit setting value before the load drop and the voltage limit setting value +50V DC. At the same time, since the voltage loop error in this embodiment is the voltage set value minus the output voltage. Therefore, in this embodiment, the voltage error threshold is set to the maximum value of 10% of the required voltage and 50V. At the same time, since the voltage loop error in this embodiment is U error is a negative value, in order to facilitate the comparison of the voltage loop error U error and the set voltage error threshold. In this embodiment, the voltage loop error U error The voltage loop error threshold is set to the opposite value of the voltage error threshold. errorSet For comparison, if U error <U errorSet This means that the absolute value of the error between the given voltage and the output voltage of the charging module is less than or equal to the set voltage error threshold. Set the voltage loop error threshold U errorSet =-max (demand voltage*10%, 50V). As another embodiment, if the error between the given voltage and the output voltage of the charging module is equal to the output voltage of the voltage module minus the given voltage value, which is a positive value during the load reduction process, it is not necessary to take the opposite of the set voltage error threshold for comparison.

[0036] Computer equipment example: A computer device of the present invention includes a processor, and the processor implements the steps of the control method of the LLC resonant converter in the charging module as described in the method embodiment of the present invention when executing a computer program. The specific process, principle and beneficial effects of the method have been described in detail in the method embodiment, and will not be repeated in this embodiment.

[0037] The processor may be a microprocessor MCU, a programmable logic device FPGA or other processing device.

[0038] LLC resonant converter embodiment: An LLC resonant converter in a charging module of the present invention includes an LLC controller, the LLC controller includes a processor, and the processor implements the steps of the control method of the LLC resonant converter in the charging module as described in the method embodiment of the present invention when executing a computer program. The specific process, principle and beneficial effects of the method have been described in detail in the method embodiment, and will not be repeated in this embodiment.

[0039] The processor may be a microprocessor MCU, a programmable logic device FPGA or other processing device.

Claims

1. A control method for an LLC resonant converter in a charging module, characterized in that: The method includes: When the load of the charging module drops suddenly, if the absolute value of the voltage error between the given voltage and the output voltage of the charging module is less than the set voltage error threshold, a corresponding control mode is executed according to the adjustment result of the voltage error to adjust the driving pulse of the LLC resonant converter to reduce the output voltage of the charging module; Among them, when the frequency of the driving pulse is less than the upper limit of the frequency of the driving pulse, the executed control mode is the PFM control mode for increasing the frequency of the driving pulse; when the width of the driving pulse is greater than the lower limit of the width of the driving pulse, the executed control mode is the PWM control mode for reducing the width of the driving pulse; when the frequency of the driving pulse is greater than or equal to the upper limit of the frequency of the driving pulse, and the width is less than or equal to the lower limit of the width of the driving pulse, the executed control mode is the Burst control mode.

2. The control method of the LLC resonant converter in the charging module according to claim 1, characterized in that: When the frequency of the driving pulse is less than the upper limit of the frequency of the driving pulse, and the width is greater than the lower limit of the width of the driving pulse, the PFM control mode is preferentially used.

3. The control method of the LLC resonant converter in the charging module according to claim 1, characterized in that: When the absolute value of the voltage error is greater than or equal to a set error threshold, the driving pulse is turned off.

4. The control method of the LLC resonant converter in the charging module according to any one of claims 1 to 3, characterized in that: The method also includes: when the charging module operates normally, adjusting the driving pulse according to the smaller value of the adjustment value of the voltage error and the adjustment value of the current error, the voltage error is the given voltage of the charging module minus the output voltage, and the current error is the given current of the charging module minus the output current.

5. The control method of the LLC resonant converter in the charging module according to claim 4, characterized in that: The adjustment value of the voltage error is the PI adjustment value of the voltage error.

6. The control method of the LLC resonant converter in the charging module according to claim 4, characterized in that: The adjustment value of the current error is the PI adjustment value of the current error.

7. A computer device comprising a processor, characterized in that: The processor implements the steps of the control method of the LLC resonant converter in the charging module according to any one of claims 1 to 6 when executing the computer program.

8. An LLC resonant converter in a charging module, comprising an LLC controller, wherein the LLC controller comprises a processor, characterized in that: The processor implements the steps of the control method of the LLC resonant converter in the charging module according to any one of claims 1 to 6 when executing the computer program.

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