Light load control method, device and equipment of light storage pre-stage LLC resonant converter and medium

Abstract

The present application relates to the technical field of power electronic control, and particularly relates to a light load control method, device, equipment and medium of a light storage front-stage LLC resonant converter, the method comprising: inputting the difference between an output voltage and a voltage reference value of a frequency loop into a PI controller of the frequency loop; intersecting a sawtooth carrier wave and a modulation wave to generate a driving signal of a primary side switch tube, comparing the driving signal with an output limit, and judging whether the frequency loop is in a saturation state; inputting the difference between the output voltage and a voltage reference value of an intermittent loop into a PI controller of the intermittent loop to generate an output value; comparing the output value with a preset threshold value, judging whether the intermittent loop is in a saturation state; judging the operating condition of the LLC resonant converter according to whether the frequency loop and the intermittent loop are in the saturation state, and taking intermittent control under a light load condition by setting an intermittent control loop, so as to widen the input voltage range of the LLC resonant converter and effectively solve the problem of excessively high voltage gain of traditional frequency conversion control under a light load condition.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power electronic control, and particularly relates to a light load control method, device and equipment of a light storage front-stage LLC resonant converter and a medium. BACKGROUND

[0002] With the development of power electronic technology, the working efficiency and power density of power converters are increasingly required. Increasing the switching frequency can effectively reduce the volume of inductive elements in the converter, but higher switching frequency brings higher switching loss, which reduces the conversion efficiency. LLC resonant converters have more and more wide applications in light storage systems, direct current microgrids, ship power systems and the like due to the advantages of high efficiency, small size and easy to realize soft switching.

[0003] In existing researches, the LLC resonant converter often adopts a pulse frequency modulation (PFM) mode to regulate the output voltage. However, under light load conditions, the voltage gain of the traditional frequency conversion control is large, which greatly limits the input voltage range of the converter, and it is difficult to meet the application requirements of the wide range of input voltages of the light storage system. The intermittent control (PWM-burst) can widen the input voltage range to a certain extent, but the existing scheme still has the defects of large output voltage ripple and low efficiency.

[0004] The information disclosed in this BACKGROUND section is only for the purpose of enhancing the understanding of the background of the present application and should not be taken as an acknowledgment or any form of suggestion that this information forms prior art in the field. SUMMARY

[0005] The present application provides a light load control method, device, equipment and medium of a light storage front-stage LLC resonant converter, thereby effectively solving the problems in the background art.

[0006] In order to achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows: a light load control method of a light storage front-stage LLC resonant converter, two voltage closed loops are designed, including a frequency loop and an intermittent loop, the frequency loop is used for frequency conversion control of an output switch tube driving signal, and the intermittent loop is used for judging whether to enter an intermittent control working condition, including the following steps:

[0007] A first pressure difference value is obtained by subtracting the voltage reference value of the frequency loop from the output voltage, and the first pressure difference value is input into the PI controller of the frequency loop, and an output amplitude limiting is set;

[0008] A sawtooth carrier wave is generated according to the output of the PI controller of the frequency loop, and the sawtooth carrier wave intersects with a modulation wave to generate a driving signal of a primary side switch tube;

[0009] The drive signal is compared with the output limit to determine whether the frequency loop is in a saturated state;

[0010] The output voltage is subtracted from the voltage reference value of the intermittent loop to obtain a second pressure difference value, and the second pressure difference value is input into the PI controller of the intermittent loop to generate an output value of the PI controller;

[0011] The output value is compared with a preset threshold value to determine whether the intermittent loop is in a saturated state;

[0012] According to whether the frequency loop and the intermittent loop are in a saturated state, the operating condition of the LLC resonant converter is determined, so as to generate a switching tube drive signal with different characteristics to realize the control of the LLC resonant converter.

[0013] Further, the output limit of the frequency loop PI controller is set as the maximum number of counts, the upper limit of the output limit corresponds to the maximum number of counts of the minimum switching frequency, and the lower limit of the output limit corresponds to the maximum number of counts of the maximum switching frequency.

[0014] Further, it is judged whether the drive signal reaches the upper limit or the lower limit set, if yes, the frequency loop is in a saturated state; if not, the frequency loop is in an unsaturated state.

[0015] Further, the sawtooth carrier is generated according to the counting method, and according to the switching frequency and voltage gain under different outputs, the adjustment of the output voltage is realized.

[0016] Further, the duty cycle of the drive signal of the switching tube is fixed, and the amplitude of the modulation wave is 0.5 times the amplitude of the sawtooth carrier.

[0017] Further, the output value is compared with the preset threshold value to determine whether the output value reaches the upper limit or the lower limit of the preset threshold value, if yes, the intermittent loop is in a saturated state; if not, the intermittent loop is in an unsaturated state.

[0018] Further, the determination of the operating condition of the LLC resonant converter comprises:

[0019] When the frequency loop and the intermittent loop are both in an unsaturated state, the LLC resonant converter is in a normal operating condition;

[0020] When the frequency loop is in a negative saturated state and the intermittent loop is in an unsaturated state, the LLC resonant converter is in a negative saturated operating condition;

[0021] When the frequency loop and the intermittent loop are both in a saturated state, the LLC resonant converter is in an intermittent operating condition.

[0022] Further, in the normal working condition, the LLC resonant converter adjusts the switching frequency by frequency control to control the output voltage at the voltage reference value of the frequency loop;

[0023] In the negative saturation working condition, the output of the frequency loop PI controller is stabilized at the lower limit of the output amplitude limiting, the switching frequency is limited at the maximum switching frequency, and the gain is at the minimum value.

[0024] In the intermittent working condition, in response to the case that the load is too light and the input voltage is too high, the drive signal is turned off when the intermittent loop PI controller output is negative saturation, and the output voltage is dynamically stabilized at the voltage reference value of the intermittent loop.

[0025] The application also includes a light load control device of a light storage pre-stage LLC resonant converter, characterized in that the above method is used, comprising:

[0026] A frequency loop input unit is configured to obtain a first pressure difference value by subtracting the output voltage from the voltage reference value of the frequency loop, input the first pressure difference value into the PI controller of the frequency loop, and set an output amplitude limiting;

[0027] A signal conversion unit is configured to generate a sawtooth carrier wave according to the output of the PI controller of the frequency loop; the sawtooth carrier wave intersects with a modulation wave to generate a drive signal of the primary side switching tube;

[0028] A frequency loop comparison unit is configured to compare the drive signal with the output amplitude limiting to determine whether the frequency loop is in a saturation state;

[0029] An intermittent loop input unit is configured to obtain a second pressure difference value by subtracting the output voltage from the voltage reference value of the intermittent loop, input the second pressure difference value into the PI controller of the intermittent loop, and generate an output value of the PI controller;

[0030] An intermittent loop comparison unit is configured to compare the output value with a preset threshold value to determine whether the intermittent loop is in a saturation state;

[0031] A working condition determination unit is configured to determine the working condition of the LLC resonant converter according to whether the frequency loop and the intermittent loop are in a saturation state, so as to generate a switching tube drive signal with different characteristics to realize the control of the LLC resonant converter.

[0032] The application also includes a computer device, which comprises a memory, a processor, and a computer program stored in the memory and executable on the processor; when the processor executes the computer program, the method described above is realized.

[0033] The application also includes a storage medium, which stores a computer program; when the processor executes the computer program, the method described above is realized.

[0034] The beneficial effects of the present application are:

[0035] By setting the intermittent control loop, intermittent control is adopted under light load conditions, which widens the input voltage range of the LLC resonant converter. The problem of high voltage gain of the traditional LLC frequency conversion control under light load conditions is effectively solved, and the negative saturation condition is set to further widen the input voltage range,

[0036] Compared with the traditional intermittent control method using voltage hysteresis loop, the double-loop control design ensures the efficient operation of the LLC resonant converter under light load and normal load conditions, well suppresses the output voltage ripple, reduces the loss, and improves the conversion efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments described in the present application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0038] Figure 1 It is a flowchart of the light load control method of the front-stage LLC resonant converter of the optical storage;

[0039] Figure 2 It is a full-bridge LLC resonant converter topology structure diagram;

[0040] Figure 3 It is a full-bridge LLC resonant converter control block diagram;

[0041] Figure 4 It is a flowchart of the light load control method of the front-stage LLC resonant converter of the optical storage;

[0042] Figure 5 It is an output voltage and primary side switch tube drive waveform diagram under intermittent condition;

[0043] Figure 6 It is a load shedding output voltage waveform diagram;

[0044] Figure 7 It is a structure schematic diagram of the light load control device of the front-stage LLC resonant converter of the optical storage;

[0045] Figure 8 It is a structure schematic diagram of the computer equipment. DETAILED DESCRIPTION

[0046] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0047] like Figures 1 to 6 The diagram illustrates a light-load control method for an LLC resonant converter in the optical storage front-end. It designs two voltage closed loops: a frequency loop and an intermittent loop. The frequency loop is used to control the output switching transistor drive signal, and the intermittent loop is used to determine whether the intermittent control mode has been entered. Figure 1 As shown, it includes the following steps:

[0048] S10: Sample the output voltage V out Voltage reference value V of the frequency loop ref1 The first differential voltage value is obtained by subtraction and input into the PI controller of the frequency loop, and the output limit is set. It should be noted that the amplitude of the limit should not be fixed, but should be set according to the switching frequency range. In this embodiment, the resonant frequency is around 90kHz according to the component parameters. In order to make the main operating frequency of the LLC resonant converter near the resonant frequency, the switching frequency range is set to 60k-160kHz in this embodiment.

[0049] S20: A sawtooth carrier is generated based on the output of the PI controller of the frequency loop. The sawtooth carrier intersects with the modulation wave to generate the drive signal for the primary-side switching transistor.

[0050] S30: Compare the drive signal with the output limiting to determine whether the frequency loop is in a saturated state;

[0051] S40: Sample the output voltage V out Voltage reference value V of the intermittent loop ref2 The second differential pressure value is obtained by subtracting the first value and then input into the PI controller of the intermittent loop to generate the output value of the PI controller.

[0052] S50: Compare the output value with the preset threshold to determine whether the intermittent loop is in a saturated state;

[0053] S60: Based on whether the frequency loop and the intermittent loop are in a saturated state, the operating condition of the LLC resonant converter is determined, thereby generating switching transistor drive signals with different characteristics to control the LLC resonant converter.

[0054] The operating condition of the LLC resonant converter is determined by the saturation state of the outputs of the frequency loop and intermittent loop PI controllers, and different characteristic switching transistor drive signals are generated. The LLC resonant converter used in this embodiment, such as... Figure 2As shown, the primary side is a full-bridge inverter circuit composed of four MOSFETs; the secondary side is a full-bridge uncontrolled rectifier circuit composed of four diodes; the core part is a resonant cavity composed of resonant inductance L r , resonant capacitance C r , excitation inductance L m , which can realize zero-voltage turn-on of the primary side MOSFET and zero-current turn-off of the secondary side diode through resonance between elements, reduce converter loss, and improve conversion efficiency.

[0055] If the frequency loop enters a saturation state, it indicates that the system cannot further optimize the output by adjusting the frequency, at which point it can enter an intermittent mode or maintain the current operating state; if the intermittent loop enters a saturation state, it indicates that the control under light load has reached the limit, and the system will maintain the intermittent mode or automatically exit the intermittent mode when the load changes to restore normal operation; the double-loop control design ensures high-efficiency operation of the LLC resonant converter under light load and normal load conditions, while reducing energy consumption through intermittent control under light load.

[0056] By designing the frequency loop and the intermittent loop, the output of the converter is accurately controlled under light load conditions, reducing energy loss; at the same time, under light load, the switching frequency is reduced through intermittent control, reducing the number of switching-on and switching-off of the switching tube and reducing the switching loss; in addition, reducing switching actions can also reduce the heat loss of the switching tube and other power devices, prolonging the service life of the devices; through double-loop control of the frequency loop and the intermittent loop, the system can maintain high-efficiency and stable operation under light load. The judgment of the saturation state further prevents the system from being unstable under extreme conditions, improving the safety and reliability of the system.

[0057] The input voltage range of the LLC resonant converter is widened, effectively solving the problem of excessively high voltage gain under light load conditions in traditional variable-frequency control; and the negative saturation condition is set to further widen the input voltage range.

[0058] Compared with the traditional intermittent control method using a voltage hysteresis loop, the output voltage ripple is well suppressed, the loss is reduced, and the conversion efficiency is improved.

[0059] As a preferred embodiment of the above, in step S10, the output amplitude of the frequency loop PI controller is set to the maximum count number, the upper limit of the output amplitude corresponds to the maximum count number of the minimum switching frequency, and the lower limit of the output amplitude corresponds to the maximum count number of the maximum switching frequency; in this embodiment, the sampling interval is selected as 1 / 24000000, and the output amplitude upper limit 400 and lower limit 150 are set accordingly.

[0060] The design of the limiting link makes the output of the PI controller remain in a stable range, especially in the light load condition, which can prevent the system efficiency from decreasing due to too low switching frequency or the switching loss from increasing due to too high switching frequency, so that the load change under the light load condition can be more effectively adapted.

[0061] In the embodiment, it is judged whether the drive signal reaches the set upper limit or lower limit, if yes, the frequency loop is in the saturated state, if not, the frequency loop is in the unsaturated state; specifically, by judging whether the drive signal reaches the upper limit or lower limit, the system frequency adjustment can be effectively prevented from being excessive, and the system can be prevented from working unstably or the switching loss from increasing due to the frequency exceeding the design range. The judgment of the saturated state is helpful for the stable operation of the system.

[0062] In step S20, the sawtooth carrier is generated according to the counting method, the switching frequency and the voltage gain under different frequencies corresponding to different outputs are realized, and the adjustment of the output voltage is realized; specifically, by flexibly adjusting the frequency and the gain, the system can maintain a stable output voltage under different load conditions.

[0063] In the embodiment, in step S30, the duty cycle of the drive signal of the switching tube is fixed, and the amplitude of the modulation wave is 0.5 times the amplitude of the sawtooth carrier, which is helpful for realizing a more stable drive signal, which will help to smooth the output voltage waveform and reduce high-frequency oscillation and electromagnetic interference (EMI).

[0064] In step S50, the output value is compared with the preset threshold value to judge whether the output value reaches the upper limit or lower limit of the preset threshold value, if yes, the intermittent loop is in the saturated state, if not, the intermittent loop is in the unsaturated state, so as to realize the effective control of whether the LLC resonant converter enters the intermittent mode under the light load condition, avoid unnecessary frequent switching, and improve the control precision; under the light load condition, the intermittent mode is helpful for reducing the switching loss, and by comparing the output value with the threshold value, the converter can be prevented from frequently entering the unnecessary intermittent mode, so as to optimize the system efficiency, especially in the case that the load change is small.

[0065] As preferred in the above embodiment, in step S60, as shown in Figure 3 the running condition of the LLC resonant converter is judged, including:

[0066] When the frequency loop and the intermittent loop are both in the unsaturated state, the LLC resonant converter is in normal working condition;

[0067] When the frequency loop is in the negative saturated state and the intermittent loop is in the unsaturated state, the LLC resonant converter is in the negative saturated working condition;

[0068] When the frequency loop and the intermittent loop are both in the saturated state, the LLC resonant converter is in the intermittent working condition.

[0069] By monitoring the saturation state of the frequency loop and the intermittent loop at the same time, the current operation mode of the LLC resonant converter can be accurately judged, ensuring that under different load conditions, the system can make appropriate adjustments according to the working condition to avoid misjudgment or false operation; when both the frequency loop and the intermittent loop are not saturated, the system is in normal operation mode; when both are saturated, the system enters intermittent working condition, which ensures smooth transition from normal working condition to intermittent working condition, helps to further reduce power consumption and switching loss under light load conditions, and improves system efficiency. By accurately distinguishing different working conditions, the stability of the system is improved, and the life of the switching element is prolonged by reducing unnecessary high-frequency switching operations, thereby enhancing the reliability of the system.

[0070] In this embodiment, as shown in Figure 4 , under normal working condition, the LLC resonant converter adjusts the switching frequency through frequency control to control the output voltage at the voltage reference value V ref1 of the frequency loop; this means that the system will continue to adjust the switching frequency to match the desired voltage output, achieving stable output voltage;

[0071] Under negative saturation working condition, the output of the frequency loop PI controller is stabilized at the lower limit of the output amplitude, limiting the switching frequency to the maximum switching frequency, and the gain is at the minimum value; compared with the traditional LLC resonant converter, the voltage input range and the gain range are effectively increased;

[0072] Under intermittent working condition, in response to the situation of too light load and too high input voltage, when the intermittent loop PI controller output is negatively saturated, the drive signal is turned off, and the output voltage is dynamically stabilized at the voltage reference value V ref2 of the intermittent loop; this can avoid frequent switching actions, and by controlling the output voltage in a dynamic balance state, the output voltage fluctuation is reduced.

[0073] The present application is different from the traditional intermittent control method using voltage hysteresis loop; the intermittent loop controls the output voltage at V ref2 dynamic balance, rather than fluctuating within the upper and lower limits, effectively reducing the output voltage ripple and improving the stability and voltage control accuracy of the system.

[0074] Through frequency control and maximum frequency limitation under negative saturation working condition, the system is ensured to operate stably under various working conditions, improving the stability of the system; under negative saturation working condition, the system can effectively increase the voltage input range and the gain range, expanding the application range of the system; by dynamically balancing the output voltage, the voltage fluctuation in the traditional method is reduced, the stability and accuracy of the output voltage are improved; under intermittent working condition, unnecessary switching operations are avoided, thereby optimizing the energy efficiency of the system and reducing energy consumption.

[0075] With reference toFigure 4 , mainly including frequency loop and intermittent loop, the working state of the converter is divided into three working conditions: normal working condition, negative saturation working condition and intermittent working condition. ref1 When the frequency loop and the intermittent loop are not negative saturation, the converter runs in the normal working condition, and the output voltage is controlled at V ref2 .

[0076] To verify the effectiveness of the above control method, a specific example is given in the embodiment, and the main parameters are shown in Table 1:

[0077] Table 1 Key parameter table

[0078]

[0079]

[0080] In the intermittent working condition, the output voltage and the switch tube driving waveform are as shown in Figure 5 ; the load shedding output voltage waveform under the fixed input voltage is as shown in Figure 6 .

[0081] As shown in Figure 5 , the converter works in the intermittent working condition, and the output voltage is stably and dynamically stabilized at V ref2 = 780V, and the voltage ripple is small, which proves that the light load control method proposed in the embodiment has good steady-state performance.

[0082] As shown in Figure 6 , in the initial state, the load P1 = 10kW, the converter works in the normal working condition, at 0.15s, the load is switched to P2 = 5kW, the converter switches the working condition to the negative saturation working condition; at 0.3s, the load is switched to P3 = 0.5kW, and the converter switches the working condition to the intermittent working condition, and it can be seen from the figure that the voltage change is completed in a short time, and the voltage fluctuation is small, which proves that the control method in the embodiment has good dynamic performance.

[0083] The light load control strategy is applied to the LLC resonant converter, but is not limited to the topology structure as shown in Figure 2 .

[0084] The application also includes a light load control device for a light storage front-stage LLC resonant converter, which uses the method as described above, as shown in Figure 7 , comprising:

[0085] A frequency loop input unit is configured to obtain a first voltage difference by subtracting the output voltage from a voltage reference value of the frequency loop, and input the first voltage difference into a PI controller of the frequency loop, and set an output amplitude limiter;

[0086] A signal conversion unit is configured to generate a sawtooth carrier according to an output of the PI controller of the frequency loop, and intersect the sawtooth carrier with a modulation wave to generate a driving signal of the primary side switch tube;

[0087] A frequency loop comparison unit is configured to compare the driving signal with the output amplitude limiter, and determine whether the frequency loop is in a saturation state;

[0088] An intermittent loop input unit is configured to obtain a second voltage difference by subtracting the output voltage from a voltage reference value of the intermittent loop, and input the second voltage difference into a PI controller of the intermittent loop to generate an output value of the PI controller;

[0089] An intermittent loop comparison unit is configured to compare the output value with a preset threshold value, and determine whether the intermittent loop is in a saturation state;

[0090] A running condition determination unit is configured to determine a running condition of the LLC resonant converter according to whether the frequency loop and the intermittent loop are in the saturation state, so as to generate a switch tube driving signal with different characteristics to realize the control of the LLC resonant converter.

[0091] Referring to Figure 8 The computer device 400 provided by the embodiment of the present application includes a processor 410 and a memory 420, the memory 420 stores a computer program executable by the processor 410, and the computer program is executed by the processor 410 to perform the method as above.

[0092] The embodiment of the present application further provides a storage medium 430, and the storage medium 430 stores a computer program, and the computer program is executed by the processor 410 to perform the method as above.

[0093] The storage medium 430 can be implemented by any type of volatile or nonvolatile storage devices or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read only memory (EPROM), programmable read only memory (PROM), read-only memory (ROM), magnetic storage, flash memory, magnetic or optical disk.

[0094] In the description of the present application, the terms "first", "second", "third", etc. are used only to describe purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. The meaning of "plurality" is two or more, unless otherwise explicitly specified and limited.

[0095] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting", "fixing" and the like should be understood in a broad sense, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0096] In the description of the present application, the description of the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present application, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine the different embodiments or examples described in the present application and the features of the different embodiments or examples without contradiction.

[0097] Any processes or methods described in the flowcharts or otherwise described herein represent embodiments of processes that can be employed, and the claims are not limited to the precise steps or the order in which the steps are presented. It is possible, for example, that certain steps can be performed in an order other than that which is presented, or certain steps can be performed substantially simultaneously, or in reverse order, depending on the circumstances. It is also possible, for example, that certain steps can be performed by different entities than those presented, or that certain steps can be performed by a single entity, depending on the circumstances.

[0098] The logic and / or steps represented in the flowcharts or otherwise described herein, for example, can be considered as a list of steps to be executed in a certain order, and the claims are not limited to the precise order presented, or in which the steps are presented. It is possible, for example, that certain steps can be performed in an order other than that which is presented, or certain steps can be performed substantially simultaneously, or in reverse order, depending on the circumstances. It is also possible, for example, that certain steps can be performed by different entities than those presented, or that certain steps can be performed by a single entity, depending on the circumstances.

[0099] It should be understood that aspects of the application can be implemented in hardware, software, firmware or combinations thereof. In the embodiments described above, various steps or methods can be implemented, for example, in software or firmware that is stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, and in another embodiment, any of the following techniques, which are known in the art of making integrated circuits, can be used alone or in combination to implement the hardware: discrete logic circuitry having logic gates for implementing logic functions upon an application of data signals; application specific integrated circuits having appropriate combinational logic gates; programmable gate arrays (PGA), field programmable gate arrays (FPGA), and so forth.

[0100] Those skilled in the art can understand that all or part of the steps of the method carried out by the above-mentioned embodiments can be instructed by a program to complete the relevant hardware, and the program can be stored in a computer readable storage medium. When the program is executed, it includes one of the steps of the method embodiment or a combination thereof.

[0101] The storage medium mentioned above can be a read-only memory, a magnetic disk or an optical disk, etc. Although the embodiments of the present application have been shown and described above, it should be understood that the above-mentioned embodiments are exemplary and cannot be understood as limiting the present application. Those skilled in the art can make changes, modifications, replacements and variations to the above-mentioned embodiments within the scope of the present application.

Claims

1. A light load control method of a light storage pre-stage LLC resonant converter, characterized by, The two voltage loops include a frequency loop and an intermittent loop, the frequency loop is used for variable frequency control of the output switch tube driving signal, and the intermittent loop is used for judging whether to enter an intermittent control working condition, and the method comprises the following steps: A first pressure difference value is obtained by subtracting the output voltage from a voltage reference value of the frequency loop, and the first pressure difference value is input into a PI controller of the frequency loop, and an output limit is set; A sawtooth carrier is generated according to the PI controller output of the frequency loop, the sawtooth carrier is intersected with a modulation wave to generate a driving signal of the primary side switch tube; The driving signal is compared with the output limit to judge whether the frequency loop is in a saturation state; A second pressure difference value is obtained by subtracting the output voltage from a voltage reference value of the intermittent loop, and the second pressure difference value is input into a PI controller of the intermittent loop to generate an output value of the PI controller; The output value is compared with a preset threshold value to judge whether the intermittent loop is in a saturation state; According to whether the frequency loop and the intermittent loop are in the saturation state, the running condition of the LLC resonant converter is judged, so that different characteristic switch tube driving signals are generated to realize the control of the LLC resonant converter.

2. The light load control method of the optical storage pre-stage LLC resonant converter according to claim 1, wherein, The output limit of the PI controller of the frequency loop is set as a maximum count number, the upper limit of the output limit corresponds to the maximum count number of the minimum switching frequency, and the lower limit of the output limit corresponds to the maximum count number of the maximum switching frequency.

3. The light load control method of the optical reservoir preliminary stage LLC resonant converter according to claim 2, characterized by, It is judged whether the driving signal reaches the set upper limit or lower limit, if yes, the frequency loop is in the saturation state; If not, the frequency loop is in an unsaturated state.

4. The light load control method of the optical storage pre-stage LLC resonant converter of claim 1, wherein, The sawtooth carrier is generated according to the counting method, and the switching frequency and the voltage gain under different outputs corresponding to different frequencies are realized to realize the regulation of the output voltage.

5. The light load control method of the optical storage pre- stage LLC resonant converter according to claim 1, wherein, The duty cycle of the driving signal of the switch tube is fixed, and the amplitude of the modulation wave is 0.5 times the amplitude of the sawtooth carrier.

6. The light load control method of the optical reservoir preliminary stage LLC resonant converter according to claim 1, characterized by, The output value is compared with the preset threshold value to judge whether the output value reaches the upper limit or lower limit of the preset threshold value, if yes, the intermittent loop is in the saturation state; If not, the intermittent loop is in the unsaturated state.

7. The light load control method of the optical storage pre- stage LLC resonant converter according to claim 1, wherein, The judgment of the running condition of the LLC resonant converter comprises: When the frequency loop and the intermittent loop are both in the unsaturated state, the LLC resonant converter is in a normal working condition; When the frequency loop is saturated and the intermittent loop is in the unsaturated state, the LLC resonant converter is in a negative saturation working condition; When the frequency loop and the intermittent loop are both in the saturation state, the LLC resonant converter is in an intermittent working condition.

8. The light load control method of the optical storage pre-stage LLC resonant converter according to claim 7, wherein, In the normal working condition, the LLC resonant converter adjusts the switching frequency through variable frequency control to control the output voltage at the voltage reference value of the frequency loop; In the negative saturation working condition, the output of the PI controller of the frequency loop is stabilized at the lower limit of the output limit, the switching frequency is limited at the maximum switching frequency, and the gain is at the minimum value; In the intermittent working condition, the driving signal is turned off when the intermittent loop PI controller output is negative saturation, and the output voltage is dynamically stabilized at the voltage reference value of the intermittent loop.

9. A light load control apparatus for a light storage pre-stage LLC resonant converter, characterized by, The method comprises the following steps: A frequency loop input unit is configured to subtract the output voltage from a voltage reference value of the frequency loop to obtain a first voltage difference value, input the first voltage difference value into a PI controller of the frequency loop, and set an output limit; A signal conversion unit is configured to generate a sawtooth carrier wave according to an output of the PI controller of the frequency loop; the sawtooth carrier wave is intersected with a modulation wave to generate a driving signal of a primary side switch tube; A frequency loop comparison unit is configured to compare the driving signal with the output limit to determine whether the frequency loop is in a saturation state; An intermittent loop input unit is configured to subtract the output voltage from a voltage reference value of the intermittent loop to obtain a second voltage difference value, input the second voltage difference value into a PI controller of the intermittent loop, and generate an output value of the PI controller; An intermittent loop comparison unit is configured to compare the output value with a preset threshold value to determine whether the intermittent loop is in a saturation state; A working condition determination unit is configured to determine a working condition of the LLC resonant converter according to whether the frequency loop and the intermittent loop are in the saturation state, so as to generate a switch tube driving signal with different characteristics to realize the control of the LLC resonant converter.

10. A computer device comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, The processor executes the computer program to realize the method of any one of claims 1-8.

11. A storage medium having stored thereon a computer program, characterized in that The computer program is executed by the processor to realize the method of any one of claims 1-8.

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