Control method, device and equipment of LLC constant-current switching power supply and power supply system

Abstract

The invention provides a control method, device and equipment of an LLC constant-current switching power supply and a power supply system. The method comprises the following steps: acquiring an output current and an output voltage; configuring a preset output voltage and a preset output current; switching between current closed-loop control and voltage closed-loop control is carried out according to the change trend of the output voltage and the output current; loop calculation is carried out through current closed-loop control, and a switch control period is obtained; in each switching control period, the magnitude of the switching frequency is dynamically adjusted according to the output current and the preset output current to realize constant current control; and the pulse widths of the primary side switching tube and the secondary side switching tube are synchronously adjusted according to the switching frequency and the resonant frequency in the constant current control. According to the invention, the current ripple of the LLC constant-current switching power supply can be effectively suppressed, the overshoot phenomenon of output voltage and current is avoided, and the conversion efficiency and safe use requirements of the power supply are ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of switching power supplies, and in particular to a control method, device, equipment and power supply system for an LLC constant current switching power supply. Background Art

[0002] Some loads require a stable output from the power supply when they are working. For example, semiconductor lasers are widely used in many fields because of their small size, light weight, low cost and high conversion efficiency. The core conversion device, the laser diode, has a steep volt-ampere characteristic curve, which means that even a small voltage fluctuation may cause a significant current change, leading to instability in the load working state. Therefore, using voltage mode drive becomes quite challenging, while using a constant current power supply drive can more conveniently and stably adjust the output power.

[0003] As the output power of semiconductor lasers continues to increase, the requirements for driving power supplies also increase. Although high-power switching power supplies can meet the power requirements, their output power ripple often cannot meet the specific requirements of laser diodes. The stability of the driving current is directly related to the quality of the output laser and the service life of the laser.

[0004] LLC resonant soft switching technology has been widely used in the field of medium and high power power conversion due to its excellent energy conversion efficiency. However, when applied to laser diode driving, this technology faces three major challenges: first, under light load conditions, there is a gain distortion problem, which will cause output voltage fluctuations and impact the laser diode; second, the Burst mode is used under light load, and the current ripple is not optimized, which may cause excessive ripple and noise; finally, during the pulse frequency modulation (PFM) process, voltage overshoot is prone to occur, which will not only cause unstable laser light output, but may even damage the diode. Summary of the invention

[0005] In view of the above problems, the embodiments of the present invention provide a control method, device, equipment and power supply system for an LLC constant current switching power supply to solve the existing technical problems.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0007] In a first aspect, the present invention provides a control method for an LLC constant current switching power supply, wherein the LLC constant current switching power supply comprises: an LLC resonant circuit, a transformer and a synchronous rectification circuit, wherein the LLC resonant circuit is connected to a primary winding of the transformer, wherein the synchronous rectification circuit is connected to a secondary winding of the transformer, wherein a primary side switch tube is provided in the LLC resonant circuit, and a secondary side switch tube is provided in the synchronous rectification circuit, wherein both the primary side switch tube and the secondary side switch tube are active switch tubes;

[0008] The control method comprises:

[0009] Collect output current and output voltage;

[0010] Configure preset output voltage and preset output current;

[0011] Switch between current closed-loop control and voltage closed-loop control according to the changing trends of output voltage and output current;

[0012] Perform loop calculation through current closed-loop control to obtain the switch control period;

[0013] In each switching control cycle, the switching frequency is dynamically adjusted according to the comparison result between the output current and the preset output current to achieve constant current control;

[0014] In constant current control, the pulse widths of the primary side switch tube and the secondary side switch tube are synchronously adjusted according to the comparison result between the switching frequency and the resonant frequency.

[0015] In one embodiment, switching between current closed-loop control and voltage closed-loop control according to the variation trends of the output voltage and the output current includes:

[0016] The output voltage is compared with the preset output voltage, and if the output voltage is less than the preset output voltage, current closed-loop control is performed;

[0017] Compare the output voltage with the preset output voltage, and if the output voltage is greater than the preset output voltage, perform voltage closed-loop control;

[0018] After executing the voltage closed-loop control, the output current is compared with the preset output current. If the output current is greater than the preset output current, the current closed-loop control is executed; if the output current is less than the preset output current, the voltage closed-loop control is maintained.

[0019] In one embodiment, the step of synchronously adjusting the pulse width of the primary-side switch tube and the secondary-side switch tube according to the comparison result of the switching frequency and the resonant frequency includes:

[0020] When the output current is different from the preset output current, determine whether the switching frequency is greater than the resonant frequency. If so, set the pulse width of the primary side switch tube to half the switching control period minus the dead time, so that the turn-on time of the secondary side switch tube is the same as the corresponding primary side switch tube, and the pulse width of the secondary side switch tube is the same as the primary side pulse width; if not, set the pulse width of the primary side switch tube to half the switching control period minus the dead time, so that the turn-on time of the secondary side switch tube is the same as the corresponding primary side switch tube, and the pulse width of the secondary side switch tube is set to half of the resonant period.

[0021] In one embodiment, in each switch control cycle, dynamically adjusting the switching frequency according to the comparison result between the output current and the preset output current to achieve constant current control includes:

[0022] If the output current is equal to the preset output current, the switching frequency is kept unchanged;

[0023] If the output current is greater than the preset output current, the switching frequency is increased;

[0024] If the output current is less than the preset output current, the switching frequency is reduced.

[0025] In a second aspect, the present invention provides a control device for an LLC constant current switching power supply, the LLC constant current switching power supply comprising: an LLC resonant circuit, a transformer and a synchronous rectification circuit, the LLC resonant circuit is connected to the primary winding of the transformer, the synchronous rectification circuit is connected to the secondary winding of the transformer, a primary side switch tube is provided in the LLC resonant circuit, a secondary side switch tube is provided in the synchronous rectification circuit, and both the primary side switch tube and the secondary side switch tube are active switch tubes;

[0026] The control device comprises:

[0027] Acquisition module: used to collect output current and output voltage;

[0028] Configuration module: used to configure the preset output voltage and preset output current;

[0029] Switching module: used to switch between current closed-loop control and voltage closed-loop control according to the changing trends of output voltage and output current;

[0030] Calculation module: used to perform loop calculation through current closed-loop control to obtain the switch control period;

[0031] The first adjustment module is used to dynamically adjust the switching frequency according to the comparison result between the output current and the preset output current in each switching control cycle to achieve constant current control;

[0032] The second adjustment module is used to synchronously adjust the pulse width of the primary side switch tube and the secondary side switch tube according to the comparison result of the switching frequency and the resonant frequency in the constant current control.

[0033] In one embodiment, the switching module is specifically used for:

[0034] The output voltage is compared with the preset output voltage, and if the output voltage is less than the preset output voltage, current closed-loop control is performed;

[0035] Compare the output voltage with the preset output voltage, and if the output voltage is greater than the preset output voltage, perform voltage closed-loop control;

[0036] After executing the voltage closed-loop control, the output current is compared with the preset output current. If the output current is greater than the preset output current, the current closed-loop control is executed; if the output current is less than the preset output current, the voltage closed-loop control is maintained.

[0037] In one embodiment, the first adjustment module is specifically used to:

[0038] If the output current is equal to the preset output current, the switching frequency is kept unchanged;

[0039] If the output current is greater than the preset output current, the switching frequency is increased;

[0040] If the output current is less than the preset output current, the switching frequency is reduced.

[0041] In one embodiment, the second adjustment module is specifically used for:

[0042] When the output current is different from the preset output current, determine whether the switching frequency is greater than the resonant frequency. If so, set the pulse width of the primary side switch tube to half the switching control period minus the dead time, so that the turn-on time of the secondary side switch tube is the same as the corresponding primary side switch tube, and the pulse width of the secondary side switch tube is the same as the primary side pulse width; if not, set the pulse width of the primary side switch tube to half the switching control period minus the dead time, so that the turn-on time of the secondary side switch tube is the same as the corresponding primary side switch tube, and the pulse width of the secondary side switch tube is set to half of the resonant period.

[0043] In a third aspect, the present invention provides an electronic device, comprising: a processor and a memory;

[0044] The memory is used to store computer programs;

[0045] The processor is used to execute the steps in the control method of an LLC constant current switching power supply provided in any one of the first aspects by calling the computer program.

[0046] In a fourth aspect, the present invention provides a power supply system, which includes the electronic device as described in the third aspect and the LLC constant current switching power supply as described in the first aspect or the steps of a control method of the LLC constant current switching power supply as shown in any possible implementation of the first aspect.

[0047] The beneficial effects of the present invention are as follows: by synchronously controlling the active switch tubes of the primary and secondary sides, power reflux under light load conditions and synchronous rectification under heavy load conditions are achieved, effectively solving the ripple problem under light load and the energy conversion efficiency problem under heavy load. Under different working conditions, by synchronously controlling the active switch tubes of the primary and secondary sides and adjusting the pulse width to adapt to different output voltage conditions, not only the influence of ripple is considered, but also the overshoot phenomenon in the gain adjustment process is avoided, thereby optimizing the power supply efficiency under heavy load. The LLC constant current power supply achieves low ripple control within the full load range; when applied to loads such as semiconductor lasers, by reducing the adjustment step size during frequency modulation, the output ripple under light load and heavy load conditions can be effectively suppressed, meeting the use requirements of semiconductor lasers, avoiding voltage and current overshoot, and ensuring the safety of laser operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 FIG. 1 is a schematic diagram of a circuit structure of an LLC constant current switching power supply provided by an embodiment of the present invention;

[0049] Figure 2 FIG. 1 is a flow chart of a control method of an LLC constant current switching power supply provided by an embodiment of the present invention;

[0050] Figure 3 The figure is a schematic diagram of the process of switching the current and voltage closed-loop control in one embodiment of the present invention;

[0051] Figure 4 The figure is a schematic diagram of the waveform of the control pulse when the voltage gain is less than 1 in one embodiment of the present invention;

[0052] Figure 5 It is a schematic diagram of the waveform of the control pulse when the voltage gain is greater than 1 in one embodiment of the present invention;

[0053] Figure 6 The figure is a schematic diagram of the process of current closed-loop control in one embodiment of the present invention;

[0054] Figure 7 FIG. 1 is a schematic diagram of a waveform of power return in an embodiment of the present invention;

[0055] Figure 8 The figure is a schematic structural diagram of a control device of an LLC constant current switching power supply in one embodiment of the present invention;

[0056] Fig. 9 FIG. 1 is a schematic structural diagram of an electronic device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0057] In order to make the purpose, technical solution and advantages of the present invention clearer and more understandable, the present invention is further described below in conjunction with the accompanying drawings and specific implementation methods. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0058] Based on the shortcomings of the prior art, the embodiment of the present invention provides a specific implementation of a control method for an LLC constant current switching power supply, such as Figure 1 Combined with Figure 2 As shown, the LLC constant current switching power supply includes: an LLC resonant circuit, a transformer and a synchronous rectification circuit. The LLC resonant circuit is connected to the primary winding of the transformer, and the synchronous rectification circuit is connected to the secondary winding of the transformer. A primary side switch tube is provided in the LLC resonant circuit, and a secondary side switch tube is provided in the synchronous rectification circuit. Both the primary side switch tube and the secondary side switch tube are active switch tubes.

[0059] More specifically, the LLC resonant circuit can be a half-bridge LLC resonant circuit or a full-bridge LLC resonant circuit; the synchronous rectification circuit can be a half-bridge synchronous rectification circuit or a full-bridge synchronous rectification circuit; no matter which combination of the LLC resonant circuit and the synchronous rectification circuit is used, the switch tubes in the LLC resonant circuit and the synchronous rectification circuit must use active switch tubes to achieve rapid switching between the "on" and "off" states in the working state and the purpose of rapid switching current in the circuit. For example Figure 1 A switching power supply circuit is presented in which the primary side of the transformer is a half-bridge LLC resonant circuit and the secondary side is a full-bridge synchronous rectification switch circuit. The half-bridge LLC resonant circuit includes a resonant circuit, a first switch circuit and a first filter circuit. The resonant circuit includes a resonant inductor Lr, a resonant capacitor Cr and an excitation inductor Lm. The first switch circuit includes a first switch tube S1 and a second switch tube S2 (i.e., a primary side switch tube). The first filter circuit includes a first filter capacitor Cin. The full-bridge synchronous rectification switch circuit includes a second switch circuit and a second filter circuit. The second switch circuit includes a third switch tube S3, a fourth switch tube S4, a fifth switch tube S5 and a sixth switch tube S6 (i.e., a secondary side switch tube). The second filter circuit includes a second filter capacitor Co. Each device is arranged according to Figure 1 The structure shown is connected.

[0060] Control methods include:

[0061] S110: Collect output current I0 and output voltage V0.

[0062] The output current I0 and the output voltage V0 refer to the current and voltage at the load connection end of the secondary side of the transformer, respectively. When obtaining the output current I0, a current sensing resistor can be connected in series at the load connection end, the voltage across the resistor can be measured, and the current value can be calculated by Ohm's law; a current transformer can also be installed at the load connection end, and the current of the primary side can be indirectly obtained by measuring the voltage or current of the secondary coil of the current transformer; a Hall element can also be installed at the load connection end, and the current can be calculated using the Hall voltage generated by the Hall element. When obtaining the output voltage V0, a ​​voltage divider resistor can be connected to the load connection end, and the voltage can be reduced to a measurable range using a resistor voltage divider circuit before measurement; a voltage sensor (such as a resistive, capacitive, inductive, etc.) can also be installed at the load connection end to convert the measured voltage into a measurable electrical signal to obtain the voltage value; when it is necessary to collect the output current I0 and the output voltage V0, an embedded system (such as a single-chip microcomputer, DSP, etc.) can be used to collect the output current I0 and the output voltage V0 in real time.

[0063] S120: Configure the preset output voltage V oref and preset output current V oref .

[0064] Preset output voltage V oref and preset output current I oref They respectively refer to the expected output voltage value and expected output current value that need to be set according to actual conditions in voltage closed-loop control and current closed-loop control.

[0065] S130: Switching between current closed-loop control and voltage closed-loop control according to the change trends of the output voltage V0 and the output current I0.

[0066] When the fluctuation of output voltage V0 or output current I0 is detected, these change trends are analyzed in real time, and the current closed-loop control or voltage closed-loop control is decided according to the preset switching control strategy. If the change of output current I0 is more significant, current closed-loop control may be selected to ensure stable current output; conversely, if the fluctuation of output voltage V0 is more critical, it will switch to voltage closed-loop control to maintain voltage stability. This dynamic switching mechanism can effectively cope with different working conditions and ensure the efficient and stable operation of the switching power supply.

[0067] Specifically, Figure 3 The schematic diagram of the current and voltage closed-loop control switching process is shown in Figure 3 In the output voltage V0 and the preset output voltage V oref For comparison, if the output voltage V0 is less than the preset output voltage V oref , then current closed-loop control is performed;

[0068] The output voltage V0 and the preset output voltage V oref Compare, if the output voltage V0 is greater than the preset output voltage V oref , then voltage closed-loop control is performed;

[0069] After executing the voltage closed-loop control, the output current I0 and the preset output current I oref For comparison, if the output current I0 is greater than the preset output current I oref , the current closed-loop control is executed; if the output current I0 is less than the preset output current I oref , the voltage closed-loop control is maintained.

[0070] S140: Perform loop calculation through current closed-loop control to obtain the switch control period T S .

[0071] Switching control period T S The following methods can be used to obtain it:

[0072] The resonant current in the resonant cavity is collected; the collected resonant current is integrated to obtain an integral value representing the current size; a resonant current closed-loop control strategy is constructed based on the integral value using a proportional-integral controller; a switch-on and switch-off signal of the switch tube is generated based on the output signal of the resonant current closed-loop control strategy using a PWM module; a switching frequency f of the switch-on and switch-off signal is generated based on the switching frequency f of the switch-on and switch-off signal s The limitation of , determine the appropriate control period Ts; use a high-precision clock source to ensure that the control period Ts is synchronized with the period of the PWM signal, and obtain a high-precision switch control period T S .

[0073] S150: In each switch control cycle T S According to the output current I0 and the preset output current I oref The comparison result dynamically adjusts the switching frequency f s The size of the current can be adjusted to achieve constant current control (i.e. constant current control mode).

[0074] Specifically, see Figure 6 , if the output current I0 and the preset output current I oref If the switching frequency is equal, then keep the switching frequency f s unchanged; if the output current I0 is greater than the preset output current I oref , then increase the switching frequency f s ; If the output current I0 is less than the preset output current I oref , then reduce the switching frequency f s This real-time adjustment ensures that the output current I0 remains at a constant level to meet the needs of the specific application.

[0075] See also Figure 7 ,exist Figure 7 The horizontal axis is time. r is the resonant current, i Lm is the transformer excitation current, i s is the secondary current, i s1 is the current of the first switch tube S1, i s3 is the current of the third switch tube S3. Through the adjustment of the above steps, Figure 7 It can be seen that during the time t0-t1, when the secondary current i s When it is negative, the resonant current i r There is a current smaller than the transformer excitation current i Lm This indicates that the secondary energy flows to the primary side during this stage. s When it is negative, it means that the current direction in the secondary circuit is opposite to the normal load current direction. r Less than the transformer excitation current i Lm When the secondary side is fed back to the primary side, it indicates that the energy fed back from the secondary side to the primary side is not enough to maintain the magnetic flux of the primary side, so the magnetic flux of the primary side may decrease. In this case, the energy of the secondary side flows to the primary side through the transformer. This energy feedback mechanism helps to avoid excessive secondary voltage, because when the secondary side energy is fed back to the primary side, the secondary side voltage will decrease. At the same time, this regulation of energy flow also helps to suppress the current ripple caused by voltage fluctuations to ensure the stability of the power supply and the normal operation of electronic equipment.

[0076] S160: In constant current control (i.e., constant current control mode), according to the switching frequency f and the resonant frequency f r The comparison result is used to synchronously adjust the pulse width of the primary side switch tube and the secondary side switch tube.

[0077] Switching frequency f s and the resonant frequency f r The size relationship between them determines the voltage gain. When adjusting the pulse width of the primary side switch tube and the secondary side switch tube, synchronous adjustment is performed. That is to say, the pulse starting points of the primary side switch tube and the secondary side switch tube are adjusted at the same time (i.e. synchronous rectification). This can significantly reduce the energy loss in the rectification process, reduce electromagnetic interference, optimize the current path and increase the power density, thereby significantly improving the energy conversion efficiency.

[0078] Specifically, see Figure 6 , when the output current I0 is equal to the preset output current I oref When different, determine the switching frequency f s Is it greater than the resonant frequency f r If so, set the primary switch pulse width to half the switch control period T SSubtract the dead time to make the switch on the secondary side the same as the corresponding switch on the primary side, and make the pulse width of the switch on the secondary side the same as the pulse width of the primary side (such as Figure 4 If not, the pulse width of the primary switch tube is set to half the switch control period T S Subtract the dead time to make the switch on the secondary side the same as the corresponding switch on the primary side, and set the pulse width of the switch on the secondary side to the resonant period T r Half of Figure 5 shown).

[0079] When adjusting, the pulse width is adjusted to the switching control period T S Or the resonant period T r Half of the adjustment step size, that is, reducing the adjustment step size during frequency modulation. Reducing the adjustment step size means that during the adjustment process, the frequency value changed each time is smaller, which makes the entire adjustment process more delicate and slow, and can more accurately approach the target frequency, reducing the sudden jump caused by too large a step size, thereby avoiding the occurrence of overshoot. Secondly, reducing the step size helps the stability of the adjustment process, so that it can smoothly transition to the target state. In addition, by reducing the adjustment step size, the stability and clarity of the signal can be maintained, thereby improving the overall quality of the signal.

[0080] In this embodiment, by synchronously controlling the active switch tubes on the primary and secondary sides, power reflux under light load conditions and synchronous rectification under heavy load conditions are achieved, effectively solving the ripple problem under light load and the energy conversion efficiency problem under heavy load. Under different working conditions, by synchronously controlling the active switch tubes on the primary and secondary sides and adjusting the pulse width to adapt to different output voltage conditions, not only the influence of ripple is considered, but also the overshoot phenomenon in the gain adjustment process is avoided, thereby optimizing the power supply efficiency under heavy load. The LLC constant current power supply achieves low ripple control within the full load range; when applied to loads such as semiconductor lasers, by reducing the adjustment step size during frequency modulation, the output ripple under light load and heavy load conditions can be effectively suppressed, meeting the use requirements of semiconductor lasers, avoiding voltage and current overshoot, and ensuring the safety of laser operation.

[0081] Based on the same inventive concept, the embodiment of the present application also provides a control device for an LLC constant current switching power supply, which can be used to implement a control method for an LLC constant current switching power supply described in the above embodiment, as described in the following embodiment. Since the principle of solving the problem by a control device for an LLC constant current switching power supply is similar to that of a control method for an LLC constant current switching power supply, the implementation of a control device for an LLC constant current switching power supply can refer to the implementation of a control method for an LLC constant current switching power supply, and the repeated parts will not be repeated. As used below, the term "unit" or "module" can be a combination of software and / or hardware that implements a predetermined function. Although the system described in the following embodiments is preferably implemented in software, the implementation of hardware, or a combination of software and hardware, is also possible and conceived.

[0082] The present invention provides a control device for an LLC constant current switching power supply. The LLC constant current switching power supply comprises: an LLC resonant circuit, a transformer and a synchronous rectification circuit. The LLC resonant circuit is connected to a primary winding of the transformer, the synchronous rectification circuit is connected to a secondary winding of the transformer, a primary side switch tube is provided in the LLC resonant circuit, a secondary side switch tube is provided in the synchronous rectification circuit, and both the primary side switch tube and the secondary side switch tube are active switch tubes.

[0083] like Figure 8 As shown, the control device includes:

[0084] Collection module 210: used to collect output current and output voltage;

[0085] Configuration module 220: used to configure a preset output voltage and a preset output current;

[0086] Switching module 230: used to switch between current closed-loop control and voltage closed-loop control according to the changing trends of output voltage and output current;

[0087] Calculation module 240: used to perform loop calculation through current closed-loop control to obtain a switch control period;

[0088] The first adjustment module 250 is used to dynamically adjust the switching frequency according to the comparison result between the output current and the preset output current in each switching control cycle to achieve constant current control;

[0089] The second adjustment module 260 is used to synchronously adjust the pulse width of the primary side switch tube and the secondary side switch tube according to the comparison result between the switching frequency and the resonant frequency in the constant current control.

[0090] In one embodiment, the switching module 230 is specifically used for:

[0091] The output voltage is compared with the preset output voltage, and if the output voltage is less than the preset output voltage, current closed-loop control is performed;

[0092] Compare the output voltage with the preset output voltage, and if the output voltage is greater than the preset output voltage, perform voltage closed-loop control;

[0093] After executing the voltage closed-loop control, the output current is compared with the preset output current. If the output current is greater than the preset output current, the current closed-loop control is executed; if the output current is less than the preset output current, the voltage closed-loop control is maintained.

[0094] In one embodiment, the first adjustment module 250 is specifically used for:

[0095] If the output current is equal to the preset output current, the switching frequency is kept unchanged;

[0096] If the output current is greater than the preset output current, the switching frequency is increased;

[0097] If the output current is less than the preset output current, the switching frequency is reduced.

[0098] In one embodiment, the second adjustment module 260 is specifically used for:

[0099] When the output current is different from the preset output current, determine whether the switching frequency is greater than the resonant frequency. If so, set the pulse width of the primary side switch tube to half the switching control period minus the dead time, so that the turn-on time of the secondary side switch tube is the same as the corresponding primary side switch tube, and the pulse width of the secondary side switch tube is the same as the primary side pulse width; if not, set the pulse width of the primary side switch tube to half the switching control period minus the dead time, so that the turn-on time of the secondary side switch tube is the same as the corresponding primary side switch tube, and the pulse width of the secondary side switch tube is set to half of the resonant period.

[0100] The embodiments of the present application also provide a specific implementation of an electronic device that can implement all the steps in the method in the above embodiments, see Fig. 9 , the electronic device 300 specifically includes the following contents:

[0101] Processor 310, memory 320, communication unit 330 and bus 340;

[0102] The processor 310 , the memory 320 , and the communication unit 330 communicate with each other via the bus 340 ; the communication unit 330 is used to implement information transmission between server-side devices and terminal devices and other related devices.

[0103] The processor 310 is used to call the computer program in the memory 320. When the processor executes the computer program, all the steps in the control method of an LLC constant current switching power supply in the above embodiment are implemented.

[0104] Those skilled in the art should understand that the memory may be, but is not limited to, a random access memory (RAM), a read only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable read-only memory (EEPROM), etc. The memory is used to store programs, and the processor executes the program after receiving the execution instruction. Furthermore, the software program and module in the above-mentioned memory may also include an operating system, which may include various software components and / or drivers for managing system tasks (such as memory management, storage device control, power management, etc.), and may communicate with various hardware or software components to provide an operating environment for other software components.

[0105] The processor may be an integrated circuit chip having the ability to process signals. The above-mentioned processor may be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc. The methods, steps, and logic block diagrams disclosed in the embodiments of the present application may be implemented or executed. The general-purpose processor may be a microprocessor or the processor may be any conventional processor, etc.

[0106] The present application also provides a power supply system, which includes steps of a method for controlling an LLC constant current switching power supply as shown in an electronic device and an LLC constant current switching power supply or any possible implementation.

[0107] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A control method for an LLC constant current switching power supply, characterized in that: The LLC constant current switching power supply comprises: an LLC resonant circuit, a transformer and a synchronous rectification circuit, wherein the LLC resonant circuit is connected to the primary winding of the transformer, the synchronous rectification circuit is connected to the secondary winding of the transformer, a primary side switch tube is provided in the LLC resonant circuit, a secondary side switch tube is provided in the synchronous rectification circuit, and both the primary side switch tube and the secondary side switch tube are active switch tubes; The control method comprises: Collect output current and output voltage; Configure preset output voltage and preset output current; Switch between current closed-loop control and voltage closed-loop control according to the changing trends of output voltage and output current; Perform loop calculation through current closed-loop control to obtain the switch control period; In each switching control cycle, the switching frequency is dynamically adjusted according to the comparison result between the output current and the preset output current to achieve constant current control; In constant current control, the pulse widths of the primary side switch tube and the secondary side switch tube are synchronously adjusted according to the comparison result between the switching frequency and the resonant frequency.

2. A control method for an LLC constant current switching power supply as claimed in claim 1, characterized in that: The switching between current closed-loop control and voltage closed-loop control according to the variation trend of the output voltage and the output current comprises: The output voltage is compared with the preset output voltage, and if the output voltage is less than the preset output voltage, current closed-loop control is performed; Compare the output voltage with the preset output voltage, and if the output voltage is greater than the preset output voltage, perform voltage closed-loop control; After executing the voltage closed-loop control, the output current is compared with the preset output current. If the output current is greater than the preset output current, the current closed-loop control is executed; if the output current is less than the preset output current, the voltage closed-loop control is maintained.

3. A control method for an LLC constant current switching power supply as claimed in claim 2, characterized in that: The step of synchronously adjusting the pulse width of the primary side switch tube and the secondary side switch tube according to the comparison result of the switching frequency and the resonant frequency includes: When the output current is different from the preset output current, determine whether the switching frequency is greater than the resonant frequency. If so, set the pulse width of the primary side switch tube to half the switching control period minus the dead time, so that the turn-on time of the secondary side switch tube is the same as the corresponding primary side switch tube, and the pulse width of the secondary side switch tube is the same as the primary side pulse width; if not, set the pulse width of the primary side switch tube to half the switching control period minus the dead time, so that the turn-on time of the secondary side switch tube is the same as the corresponding primary side switch tube, and the pulse width of the secondary side switch tube is set to half of the resonant period.

4. A control method for an LLC constant current switching power supply as claimed in claim 1, characterized in that: In each switch control cycle, dynamically adjusting the switching frequency according to the comparison result between the output current and the preset output current to achieve constant current control includes: If the output current is equal to the preset output current, the switching frequency is kept unchanged; If the output current is greater than the preset output current, the switching frequency is increased; If the output current is less than the preset output current, the switching frequency is reduced.

5. A control device for LLC constant current switching power supply, characterized in that: The LLC constant current switching power supply comprises: an LLC resonant circuit, a transformer and a synchronous rectification circuit, wherein the LLC resonant circuit is connected to the primary winding of the transformer, the synchronous rectification circuit is connected to the secondary winding of the transformer, a primary side switch tube is provided in the LLC resonant circuit, a secondary side switch tube is provided in the synchronous rectification circuit, and both the primary side switch tube and the secondary side switch tube are active switch tubes; The control device comprises: Acquisition module: used to collect output current and output voltage; Configuration module: used to configure the preset output voltage and preset output current; Switching module: used to switch between current closed-loop control and voltage closed-loop control according to the changing trends of output voltage and output current; Calculation module: used to perform loop calculation through current closed-loop control to obtain the switch control period; The first adjustment module is used to dynamically adjust the switching frequency according to the comparison result between the output current and the preset output current in each switching control cycle to achieve constant current control; The second adjustment module is used to synchronously adjust the pulse width of the primary side switch tube and the secondary side switch tube according to the comparison result of the switching frequency and the resonant frequency in the constant current control.

6. A control device for an LLC constant current switching power supply as claimed in claim 5, characterized in that: The switching module is specifically used for: The output voltage is compared with the preset output voltage, and if the output voltage is less than the preset output voltage, current closed-loop control is performed; Compare the output voltage with the preset output voltage, and if the output voltage is greater than the preset output voltage, perform voltage closed-loop control; After executing the voltage closed-loop control, the output current is compared with the preset output current. If the output current is greater than the preset output current, the current closed-loop control is executed; if the output current is less than the preset output current, the voltage closed-loop control is maintained.

7. A control device for an LLC constant current switching power supply as claimed in claim 6, characterized in that: The first adjustment module is specifically used for: If the output current is equal to the preset output current, the switching frequency is kept unchanged; If the output current is greater than the preset output current, the switching frequency is increased; If the output current is less than the preset output current, the switching frequency is reduced.

8. The control device of an LLC constant current switching power supply as claimed in claim 5, characterized in that: The second adjustment module is specifically used for: When the output current is different from the preset output current, it is determined whether the switching frequency is greater than the resonant frequency. If so, the pulse width of the primary switch tube is set to half the switching control period minus the dead time, so that the turn-on time of the secondary switch tube is the same as that of the corresponding primary switch tube, and the pulse width of the secondary switch tube is the same as that of the primary pulse width; If not, the pulse width of the primary switch tube is set to half the switch control period minus the dead time, so that the turn-on time of the secondary switch tube is the same as the corresponding primary switch tube, and the pulse width of the secondary switch tube is set to half of the resonant period.

9. An electronic device, characterized in that: include: Processor and memory; The memory is used to store computer programs; The processor is used to execute the steps of the method according to any one of claims 1 to 4 by calling a computer program stored in a memory.

10. A power supply system, characterized in that: The power supply system comprises the electronic device as claimed in claim 9 and the LLC constant current switching power supply as claimed in claim 1.

Images