A starting method and device of a switching power supply

Abstract

The application discloses a starting method and device of a switching power supply. When the switching power supply starts, the output power of the power circuit can be gradually increased by changing the control parameter from the first switching parameter to the second switching parameter, thereby reducing the impact current of the power circuit. In addition, when the difference between the output parameter of the power circuit and the expected parameter is not within the preset range, only the feedback output value of the feedback circuit is calculated and saved. When the difference is within the preset range or the control parameter is changed to the second switching parameter, the switching tube in the power circuit is controlled based on the feedback output value to stabilize the output parameter at the expected parameter, thereby avoiding a large feedback output value of the feedback circuit at the moment of switching the feedback circuit and avoiding a large inrush current. It can be seen that the starting method in the application can avoid impacting the switching power supply and improve the reliability and safety of the switching power supply.

Description

Technical Field

[0001] This invention relates to the field of switching power supply control, and in particular to a method and apparatus for starting a switching power supply. Background Technology

[0002] A switching power supply typically includes a control circuit and a power circuit. The control circuit controls the switching frequency or duty cycle of the switching transistors in the power circuit to ensure that the power circuit outputs power corresponding to the switching frequency or duty cycle, thereby supplying power to the load. Specifically, the control circuit includes a feedback control circuit and a drive control circuit. The feedback control circuit collects data on the output voltage or current of the power circuit, and the drive control circuit adjusts the frequency or duty cycle of the switching transistors based on the difference between the output voltage or current collected by the feedback control circuit and the desired value, thus stabilizing the output voltage or current of the power circuit at the desired value.

[0003] In the prior art, when controlling a power circuit, at the moment of startup, the output voltage or current of the power circuit acquired by the feedback control circuit is zero. Therefore, the difference between the output voltage or current and the expected value is relatively large. When controlling each switch in the power circuit based on this large value, there may be a large inrush current at the output terminal of the power circuit. This inrush current may cause damage to the components in the power circuit. Summary of the Invention

[0004] The purpose of this invention is to provide a startup method and apparatus for a switching power supply, which can reduce the inrush current of the power circuit and avoid a large feedback output value of the feedback circuit at the moment of switching the feedback circuit, thus avoiding the generation of a large surge current. It can be seen that the startup method in this application can avoid impacting the switching power supply and improve the reliability and safety of the switching power supply.

[0005] To address the aforementioned technical problems, this application provides a startup method for a switching power supply, applied to a control circuit within the switching power supply. The switching power supply includes a control circuit and a power circuit connected to the control circuit. The control circuit includes a drive circuit and a feedback circuit. The method includes:

[0006] S11: During the first preset time of startup of the switching power supply, the switching transistor in the power circuit is controlled to operate by a control parameter. The control parameter is gradually changed from a first switching parameter to a second switching parameter during the preset time. The output power of the power circuit corresponding to the first switching parameter is less than the output power of the power circuit corresponding to the second switching parameter.

[0007] S12: During the first preset time period, the output parameters of the power circuit are acquired in real time, including output voltage, output current, or output power.

[0008] S13: calculating a difference between the output parameter and an expected parameter within the first preset time;

[0009] S14: calculating a feedback output value of the feedback circuit based on the difference and saving within the first preset time;

[0010] S15: determining a feedback control parameter of the switch tube based on the current feedback output value when the difference between the output parameter and the expected parameter is within a preset range or the control parameter is changed to the second switch parameter, and controlling the switch tube in the power circuit to act based on the feedback control parameter, so as to stabilize the output parameter of the power circuit at the expected parameter.

[0011] Preferably, the S12, the S13 and the S14 are executed at least twice within the first preset time.

[0012] Preferably, the control parameter includes a working frequency and / or a duty cycle of the switch tube.

[0013] Preferably, the power circuit is an LLC half-bridge resonant circuit, the control parameter is a working frequency of the switch tube when the LLC half-bridge resonant circuit works in an inductive region, and the S11 comprises:

[0014] controlling the working frequency of the LLC half-bridge resonant circuit to be a maximum working frequency when the switching power supply starts;

[0015] controlling the working frequency to decrease by a first preset value every second preset time, the first preset time including a plurality of the second preset time;

[0016] controlling the switch tube in the power circuit to act based on the decreased working frequency.

[0017] Preferably, the power circuit is an LLC half-bridge resonant circuit, the control parameter is a working frequency of the switch tube when the LLC half-bridge resonant circuit works in a capacitive region, and the S11 comprises:

[0018] controlling the working frequency of the LLC half-bridge resonant circuit to be a minimum working frequency when the switching power supply starts;

[0019] controlling the working frequency to increase by a second preset value every third preset time, the first preset time including a plurality of the third preset time;

[0020] controlling the switch tube in the power circuit to act based on the increased working frequency.

[0021] Preferably, the control parameter is a duty cycle, and the S11 comprises:

[0022] controlling the switch tube in the power circuit to work with a minimum duty cycle when the switching power supply starts;

[0023] controlling the duty cycle to increase by a third preset value every fourth preset time, the first preset time comprising a plurality of the fourth preset time;

[0024] controlling the switch tube in the power circuit to act based on the increased duty cycle.

[0025] Preferably, the feedback output value of the feedback circuit is calculated and saved based on the difference, comprising:

[0026] the feedback output value of the feedback circuit is calculated using a PID algorithm based on the difference and preset PID parameters.

[0027] Preferably, after the S14, if the difference is not within the preset range, the steps of the S12, the S13 and the S14 are continuously executed.

[0028] Preferably, the S12, the S13 and the S14 are executed once every fifth preset time within the first preset time, the first preset time comprising a plurality of the fifth preset time.

[0029] To solve the above technical problems, the application further provides a starting device of a switching power supply, comprising:

[0030] a memory for storing a computer program;

[0031] a control circuit for implementing the steps of the starting method of the switching power supply when the computer program is executed.

[0032] The application provides a starting method and device of a switching power supply. When the switching power supply starts, the output power of the power circuit can be gradually increased by changing the control parameter from a first switch parameter to a second preset parameter, thereby reducing the impact current of the power circuit. In addition, when the difference between the output parameter of the power circuit and the expected parameter is not within the preset range, only the feedback output value of the feedback circuit is calculated and saved, that is, the feedback output value is updated in real time. When the difference is within the preset range or the control parameter changes to the second switch parameter, the switch tube in the power circuit is controlled to act based on the current feedback output value, so that the output parameter is stabilized at the expected parameter, thereby avoiding a large surge current caused by a large feedback output value of the feedback circuit at the moment of switching the feedback circuit. It can be seen that the starting method in the application can avoid impacting the switching power supply and improve the reliability and safety of the switching power supply. BRIEF DESCRIPTION OF DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the prior art and embodiments will be briefly introduced as follows. Obviously, the drawings described in the following embodiments are only some of the embodiments of the present application, and all other drawings obtained by those skilled in the art without creative effort based on these drawings also belong to the protection scope of the present application.

[0034] Figure 1 A flowchart of a starting method of a switching power supply provided by the present application;

[0035] Figure 2 A schematic diagram of a feedback circuit in the prior art;

[0036] Figure 3 A structural block diagram of an LLC half-bridge resonant circuit in the prior art;

[0037] Figure 4 A circuit schematic diagram of an LLC half-bridge resonant circuit in the prior art;

[0038] Figure 5 A structural schematic diagram of a Boost circuit in the prior art;

[0039] Figure 6 A structural block diagram of a starting device of a switching power supply provided by the present application. DETAILED DESCRIPTION

[0040] The core of the present application is to provide a starting method and device of a switching power supply, which can reduce the inrush current of a power circuit, and also avoid that the feedback output value of a feedback circuit is relatively large at the moment of switching the feedback circuit, so as to avoid generating a large inrush current. It can be seen that the starting method in the present application can avoid impacting the switching power supply, and improves the reliability and safety of the switching power supply.

[0041] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings of the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative effort also belong to the protection scope of the present application.

[0042] Please refer to Figure 1 , Figure 1 A flowchart of a starting method of a switching power supply provided by the present application, which is applied to a control circuit in the switching power supply. The switching power supply comprises the control circuit and a power circuit controlled by the control circuit. The control circuit comprises a driving circuit and a feedback circuit. The method comprises the following steps.

[0043] S11: in the first preset time after the switching power supply is started, the switching tube in the power circuit is controlled to act according to a control parameter, the control parameter is gradually changed from a first switching parameter to a second switching parameter in the preset time, the output power of the power circuit corresponding to the first switching parameter is less than the output power of the power circuit corresponding to the second switching parameter;

[0044] S12: in the first preset time, the output parameter of the power circuit is acquired in real time, the output parameter includes the output voltage or the output current or the output power;

[0045] S13: in the first preset time, the difference between the output parameter and the expected parameter is calculated;

[0046] S14: in the first preset time, the feedback output value of the feedback circuit is calculated based on the difference and saved;

[0047] After S14 is executed, if the difference is not within the expected value, S12, S13 and S14 are continuously executed.

[0048] The steps S12, S13 and S14 are executed at least twice in the first preset time. In a specific embodiment, the more the steps are executed, that is, the shorter the time interval between each execution and the previous execution, the more accurate the control of the output value in the soft start process.

[0049] S15: when the difference between the output parameter and the expected parameter is within the preset range or the control parameter is changed to the second switching parameter, the feedback control parameter of the switching tube is determined based on the current feedback output value, and the switching tube in the power circuit is controlled to act based on the feedback control parameter, so that the output parameter of the power circuit is stabilized at the expected parameter.

[0050] In the prior art, when the power circuit is controlled by using the digital control method, a large impact current may occur at the output end of the power circuit at the starting moment of the power circuit, which may cause damage to the components in the power circuit. In addition, the digital control method in the prior art cannot meet different power requirements of different loads.

[0051] To solve the above technical problems, the soft start program is designed to make the power circuit start soft at the start: specifically, during the soft start, the feedback circuit does not work, the soft start program controls the power circuit to start with small power, then controls the output power of the power circuit to gradually increase to the expected value, and the feedback loop operates during the soft start, but does not execute the operation result.

[0052] Specifically, the soft start method in the prior art is further described herein, please refer to Figure 2 , Figure 2A schematic diagram of a feedback circuit in the prior art. Wherein, Vin is the output voltage feedback value of the power circuit, Vref is the reference voltage value, Vo is the output voltage value of the regulator. According to the characteristics of the PID regulator, when the switch power supply is started, the output voltage of the power circuit is 0, so Vin is generally 0, and the difference with Vref is large, so the output Vo is a large value, so that the power circuit starts to work with the maximum power. Through the above control mode, the power (or voltage, current) at the output end starts to rise at the maximum rate, Vin increases, the difference with Vref gradually decreases, Vo gradually decreases, until Vfb is equal to Vref, the loop is closed, the circuit is stable output, and the starting process is completed. As can be seen from the above, the soft start method in the prior art has a large Vo when switching to the feedback program, and there may also be a surge current, which cannot complete the soft start effect.

[0053] Based on this, in addition to gradually increasing the output power of the power circuit at the moment of starting the switch power supply, the control method in the present application also calculates the feedback output value of the feedback circuit, but does not control the power circuit based on the feedback output value. When the difference between the output parameter and the expected parameter is within the preset range, or the control parameter of the switch tube changes to the second switch parameter, at this time, the difference between the corresponding output parameter and the expected parameter is small, and the feedback output value calculated based on the difference is small. Then, when the power circuit is controlled based on this feedback output value, a large surge current is avoided, thereby avoiding damage to the switch power supply.

[0054] Specifically, the way to gradually increase the output power of the power circuit is to gradually increase the control parameter from the first switch parameter to the second switch parameter, wherein the control parameter is a parameter for controlling the action of the switch tube in the power circuit, and the output power of the power circuit corresponding to the first switch parameter is less than the output power of the power circuit corresponding to the second switch parameter, so as to gradually increase the output power of the power circuit.

[0055] Wherein, when the output parameter of the power circuit is obtained within the first preset time, the output parameter can include but is not limited to output voltage or output current or output power, wherein the output voltage and the output current can both reflect the output power of the power circuit.

[0056] It should be noted that steps S12, S13 and S14 are executed after the switch power supply is started, and of course the first preset time is also included; and the technical solution of the present application solves the problem of the prior art by executing steps S12, S13 and S14 within the first preset time in combination with the step S11 of the soft start in the prior art.

[0057] In addition, as a preferred embodiment, the output parameter of the power circuit is obtained in real time, comprising:

[0058] The output parameter of the power circuit is sampled to obtain a sampled parameter.

[0059] The embodiment aims to provide a specific implementation of obtaining the output parameter of the power circuit, specifically, the output parameter of the power circuit is sampled to obtain the digital output parameter.

[0060] In addition, the feedback output value of the feedback circuit can be saved after being calculated in the application.

[0061] It should be noted that the control parameter is specifically determined according to the specific implementation of the power circuit, which is not particularly limited in the application.

[0062] It can be seen that the application can reduce the inrush current of the power circuit, and also avoid that the feedback output value of the feedback circuit is large at the moment of switching the feedback circuit, thereby avoiding generating a large inrush current. It can be seen that the starting method in the application can avoid impacting the switching power supply, thereby improving the reliability and safety of the switching power supply.

[0063] On the basis of the above embodiment:

[0064] As a preferred embodiment, the control parameter includes a working frequency and / or a duty cycle of the control switch tube.

[0065] The embodiment aims to provide a specific implementation of the control parameter, wherein the form of controlling the action of the switch tube in the power circuit includes working frequency control and duty cycle control. Therefore, the control parameter in the embodiment can be the working frequency or the duty cycle of the switch tube, and the specific form is determined according to the actual situation, which is not particularly limited in the application.

[0066] As a preferred embodiment, the power circuit is an LLC half-bridge resonant circuit, and the control parameter is the working frequency of the switch tube when the LLC half-bridge resonant circuit works in the inductive region; S11 includes:

[0067] When the switching power supply starts, the working frequency of the LLC half-bridge resonant circuit is controlled to be the maximum working frequency.

[0068] The working frequency is controlled to decrease by a first preset value every second preset time, and the first preset time includes a plurality of second preset times.

[0069] The action of the switch tube in the power circuit is controlled based on the reduced working frequency.

[0070] The embodiment aims to provide a specific implementation mode. When the power circuit is an LLC half-bridge resonant circuit, the circuit controls the output power of the power circuit by controlling the working frequency of the switch tube. When the circuit is designed to work in the inductive region, the output power of the LLC half-bridge resonant circuit is smaller when the working frequency of the switch tube is higher, that is, in the inductive region, the working frequency of the switch tube is negatively correlated with the output power. Therefore, the step S11 can be specifically:

[0071] When the switching power supply is started, the switch tube is controlled to work at the maximum working frequency to make the power circuit output the minimum power, and then the working frequency is controlled to decrease every certain time, that is, the output power of the power circuit is controlled to increase, so that the step of gradually increasing the output power of the power circuit is realized.

[0072] The switch tube can also be controlled to work at a larger power at the start of the switching power supply, and then the working frequency is controlled to gradually decrease. It is not necessarily the maximum working frequency.

[0073] In addition, the steps S12, S13 and S14 can be executed once every time the working frequency is changed.

[0074] It can be seen that the working frequency of the switch tube is controlled in the application to realize the function of gradually increasing the output power of the switching power supply, and the implementation mode is simple and reliable.

[0075] As a preferred embodiment, the power circuit is an LLC half-bridge resonant circuit, and the LLC half-bridge resonant circuit works in the capacitive region. The control parameter is the working frequency of the switch tube. The S11 includes:

[0076] When the switching power supply is started, the working frequency of the LLC half-bridge resonant circuit is controlled to be the minimum working frequency.

[0077] The working frequency is controlled to increase by a second preset value every third preset time. The first preset time includes a plurality of third preset times.

[0078] The switch tube in the power circuit is controlled to act based on the increased working frequency.

[0079] The embodiment aims to provide a specific implementation mode. When the power circuit is an LLC half-bridge resonant circuit, and when the circuit is designed to work in the capacitive region, the output power of the LLC half-bridge resonant circuit is smaller when the working frequency of the switch tube is lower, that is, in the capacitive region, the working frequency of the switch tube is positively correlated with the output power. Therefore, the step S11 can be specifically:

[0080] At the start of the switching power supply, the switching tube is controlled to work at the minimum working frequency first, so that the power circuit outputs minimum power, then the working frequency is controlled to increase every time interval, that is, the output power of the power circuit is controlled to increase, thereby realizing the step of gradually increasing the output power of the power circuit.

[0081] In the switching power supply, the switching tube can also be controlled to work at a small power first, and then gradually increase, not necessarily at the minimum working frequency.

[0082] In addition, the S12, S13 and S14 steps can be executed once every time the working frequency changes.

[0083] It can be seen that the application can realize the function of gradually increasing the output power of the switching power supply by controlling the working frequency of the switching tube, and the implementation is simple and reliable.

[0084] Please refer to Figure 3 and Figure 4 , Figure 3 is a structural block diagram of an LLC half-bridge resonant circuit in the prior art, Figure 4 is a circuit schematic diagram of an LLC half-bridge resonant circuit in the prior art. The LLC circuit power circuit includes a switching unit, a resonant unit, and a load unit. The switching unit includes a first switching tube S1 and a second switching tube S2, and a control circuit can control the conduction and turn-off of S1 and S2. A bus voltage Vbus is connected across S1 and S2 in series, and the control circuit controls the turn-on and turn-off of S1 and S2 to form a square wave generating circuit. By controlling the switching frequency of S1 and S2, the conversion of energy in the resonant unit and the load unit is controlled, thereby controlling the current, voltage, power and other parameters of the load unit. The resonant unit further includes a resonant inductor L1 and a resonant capacitor C1. The load unit includes a transformer T1, a rectifier circuit, a capacitor C2 and an external load R. The control circuit includes a sampling module, a driving module and a frequency control module.

[0085] Specifically, the sampling module is used to sample the voltage or current of the external load and transmit the sampling data to the frequency control module. In the control circuit, the frequency control module and the driving module are digitally controlled, the frequency control module outputs a frequency control signal to the driving module, and the driving module controls S1 and S2 to conduct or turn off at the frequency according to the signal, thereby outputting a square wave at a certain frequency to the resonant unit and the load unit in the rear stage.

[0086] In the frequency control module, the maximum frequency value fmax is preset, the frequency step is Δf, and the time step is Δt. The feedback control program is set in the frequency control module, and the parameters (voltage, current or power parameters) of the external load in the steady state are set and converted into the reference value Vref in the feedback control program.

[0087] Correspondingly, in the LLC circuit non-starting stage, the sampling module samples the current, voltage and other data of the external load, and transmits the sampling data to the frequency control module. The frequency control module converts the sampling data through analog-to-digital conversion into an input value Vin in the feedback control program. In the feedback control program, Vin is compared with Vref, and the corresponding frequency control mode is calculated, that is, a certain frequency is increased or a certain frequency is reduced, to control the current, voltage or power and other parameters of the external load to be constant.

[0088] In the LLC circuit soft-start stage, the control circuit controls the frequency of the LLC circuit to be fmax, and gradually increases the frequency so that it increases by Δf every Δt time. At the same time, the circuit parameters (voltage, current, power and other parameters) of the external load are monitored, and the difference with the set expected value is calculated. At the same time, the PID feedback program calculates the feedback control strategy according to the sampling data of the sampling module, and stores the output value. When the difference between the sampling data and the set expected value is within a certain range, the stored feedback control strategy is switched to perform corresponding control, so that the output parameters of the LLC circuit, that is, the voltage or current or power value of the external load, is stabilized to the set expected value.

[0089] As a preferred embodiment, when the control parameter is the duty cycle, S11 includes:

[0090] When the switching power supply starts, the switching tube in the power circuit is controlled to work at the minimum duty cycle;

[0091] The duty cycle is increased by a third preset value every fourth preset time, and the first preset time includes a plurality of fourth preset times;

[0092] The switching tube in the power circuit is controlled to act based on the increased duty cycle.

[0093] As a preferred embodiment, the power circuit is a Boost circuit.

[0094] This embodiment aims to provide a specific implementation method. When the power circuit is a duty cycle controlled circuit, the duty cycle of the switching tube is positively correlated with the output power. Therefore, the above step S11 can be specifically:

[0095] When the switching power supply starts, the switching tube is first controlled to work at the minimum duty cycle to make the power circuit output the minimum power, and then the duty cycle is controlled to increase every certain time, that is, the output power of the power circuit is controlled to increase, thereby realizing the step of gradually increasing the output power of the power circuit.

[0096] Among them, when the switching power supply starts, the switching tube can also be controlled to work at a smaller duty cycle, and then gradually increase it, which does not necessarily have to be the minimum duty cycle.

[0097] In addition, the duty cycle of the S12, S13 and S14 steps can be changed once, and executed once.

[0098] It can be seen that the output power of the switching power supply can be gradually increased by controlling the duty cycle of the switching tube, and the implementation is simple and reliable.

[0099] Please refer to Figure 5 , Figure 5 is a structural schematic diagram of the prior art Boost circuit. The Boost circuit includes an inductor L1, a diode D1, a switching tube S1, a capacitor C1 and an external load. The control circuit includes a sampling module, a duty cycle control module and a driving module.

[0100] The sampling module is used to sample the voltage or current of the external load and transmit the sampling data to the duty cycle control module; in the control circuit, the duty cycle control module and the driving module are digitally controlled; in the control circuit, the duty cycle control module outputs a duty cycle control signal to the driving module, and the driving module controls the S1 to be turned on at the duty cycle according to the signal.

[0101] In the switching power supply, the minimum duty cycle Dmin, the duty cycle step ΔD and the time step Δt are preset in the duty cycle control module. The feedback control program is set in the duty cycle control module, and the parameters (voltage, current or power, etc.) of the external load in the steady state are set and converted into the reference value Vref in the feedback control program.

[0102] Correspondingly, in the non-starting stage of the Boost circuit, the sampling module samples the current, voltage and other data of the external load and transmits the sampling data to the duty cycle control module. The duty cycle control module converts the sampling data through analog-to-digital conversion into the input value Vin in the feedback control program. In the feedback control program, Vin is compared with Vref, and the corresponding duty cycle control mode is calculated, that is, a certain duty cycle is increased or a certain duty cycle is reduced, to control the current, voltage or power of the external load to be constant.

[0103] In the soft start stage of the Boost circuit, the control circuit controls the duty cycle of the switch tube of the Boost circuit to be Dmin, and gradually increases the duty cycle, so that the duty cycle of the switch tube is increased by ΔD every Δt. Meanwhile, the circuit parameters (voltage, current or power parameters) of the external load are monitored, and the difference between the set expected value is calculated. Meanwhile, the PID feedback program calculates the feedback control strategy (increases or decreases the duty cycle) according to the sampling data of the sampling module, and stores the output value. When the difference between the sampling data and the set expected value is within a certain range, the stored feedback control strategy is switched to perform corresponding control, so that the output parameters of the Boost circuit, that is, the voltage or current value of the external load, are stabilized to the set expected value.

[0104] As a preferred embodiment, the feedback output value of the feedback circuit is calculated based on the difference and saved, including:

[0105] The feedback output value of the feedback circuit is calculated based on the difference, the preset proportional integral differential PID parameter, and the PID algorithm.

[0106] In the present application, when calculating the feedback output value, the PID algorithm is used based on the difference and the preset PID parameter. Specifically, in the PID algorithm, the preset PID parameter is: P=KP, I=KI, D=KD, and the PID algorithm is as follows:

[0107]

[0108] u k is the output value after the kth sampling, u o is the output value when the switch power supply is not started, e k is the circuit output value u k at the kth sampling, e k-1 is the difference between the circuit output value u k-1 at the k-1th sampling and the expected value, in the PID algorithm, the difference e k is calculated according to the circuit output u k and the expected value, and the above operation is performed, and the controller outputs the corresponding control strategy, such as increasing or decreasing the frequency or duty cycle, according to the operation result (feedback output value), so that u k is stabilized at the expected value.

[0109] As a preferred embodiment, S12, S13 and S14 are executed at least twice within the first preset time.

[0110] To avoid a large inrush current or impulse current, the steps S12, S13 and S14 are executed at least twice during the execution of S11 (i.e. within the first preset time). For example, the steps S12, S13 and S14 can be executed once with a change in duty cycle of at least twice; the steps S12, S13 and S14 can be executed once with a change in operating frequency of the switch tube of at least twice. The steps S12, S13 and S14 can also be executed at least twice during a change in duty cycle.

[0111] Similarly, as a preferred embodiment, the step S14 is executed once every fifth preset time within the first preset time, and the first preset time comprises a plurality of fifth preset times.

[0112] To avoid a large inrush current or impulse current, the steps S12, S13 and S14 are executed once every fifth preset time during the execution of S11 (i.e. within the first preset time), wherein the fifth preset time can be equal to the second preset time or the third preset time or the fourth preset time based on the above embodiment, and in this case, the corresponding can be a change (increase or decrease) in operating frequency of the switch tube executed once (i.e. within the first preset time); or an increase in duty cycle executed once (i.e. within the first preset time). The fifth preset time can also be another time, which is not particularly limited herein.

[0113] In specific embodiments, the more the steps S12, S13 and S14 are executed, i.e. the shorter the time interval between each execution and the previous execution, the more accurate the control of the output value in the soft start process.

[0114] Please refer to Figure 6 , Figure 6 A structure block diagram of a starting device of a switching power supply is provided in the present application, and the device comprises:

[0115] A memory 61 is used to store a computer program.

[0116] A control circuit 52 is used to implement the steps of the starting method of the switching power supply when the computer program is executed.

[0117] To solve the above technical problem, the present application further provides a starting device of a switching power supply. For the starting device of the switching power supply, please refer to the above embodiments, which will not be described herein again.

[0118] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. It will be apparent to those skilled in the art that various modifications and variations can be made in the present application without departing from the spirit or scope of the application. Thus, it is intended that the present application cover modifications and variations of this application provided they come within the scope of the appended claims and their equivalents.

[0119] It will be apparent to those skilled in the art that various modifications and variations can be made in the present application without departing from the spirit or scope of the application. Thus, it is intended that the present application cover modifications and variations of this application provided they come within the scope of the appended claims and their equivalents.

[0120] The above description of disclosed embodiments is intended to be illustrative and not restrictive. Many embodiments of the application will be apparent to those of skill in the art upon reviewing the above description. The scope of the application should, therefore, be determined not with reference to the above description, but instead should be given with reference to the appended claims, along with their full scope of equivalents.

Claims

1. A starting method of a switching power supply, characterized by, A control circuit applied to a switching power supply, the switching power supply comprising a control circuit and a power circuit controlled by the control circuit, the control circuit comprising a driving circuit and a feedback circuit, the method comprising: S11: controlling the switch tube in the power circuit to act with a control parameter within a first preset time after the switching power supply starts, the control parameter being gradually changed from a first switching parameter to a second switching parameter within the preset time, the output power of the power circuit corresponding to the first switching parameter being less than the output power of the power circuit corresponding to the second switching parameter; S12: acquiring an output parameter of the power circuit in real time within the first preset time, the output parameter comprising an output voltage or an output current or an output power; S13: calculating a difference between the output parameter and an expected parameter within the first preset time; S14: calculating a feedback output value of the feedback circuit based on the difference and saving the feedback output value within the first preset time; S15: determining a feedback control parameter of the switch tube based on the current feedback output value when the difference between the output parameter and the expected parameter is within a preset range, and controlling the switch tube in the power circuit to act based on the feedback control parameter, so that the output parameter of the power circuit is stabilized at the expected parameter; wherein, after the S14, if the difference is not within the preset range, the power circuit is not controlled based on the feedback output value, and the steps of S12, S13 and S14 are continued to be executed; the feedback output value is updated in real time.

2. The starting method of a switching power supply according to claim 1, wherein The S12, S13 and S14 are executed at least twice within the first preset time.

3. The starting method of a switching power supply according to claim 1, wherein The control parameter comprises a working frequency and / or a duty cycle of the switch tube.

4. The starting method of a switching power supply according to claim 1, wherein When the power circuit is an LLC half-bridge resonant circuit and the LLC half-bridge resonant circuit works in an inductive region, the control parameter is the working frequency of the switch tube; the S11 comprises: controlling the working frequency of the LLC half-bridge resonant circuit to be a maximum working frequency when the switching power supply starts; controlling the working frequency to decrease by a first preset value every second preset time, the first preset time comprising a plurality of second preset times; controlling the switch tube in the power circuit based on the decreased working frequency.

5. The starting method of a switching power supply according to claim 1, wherein When the power circuit is an LLC half-bridge resonant circuit and the LLC half-bridge resonant circuit works in a capacitive region, the control parameter is the working frequency of the switch tube; the S11 comprises: controlling the working frequency of the LLC half-bridge resonant circuit to be a minimum working frequency when the switching power supply starts; controlling the working frequency to increase by a second preset value every third preset time, the first preset time comprising a plurality of third preset times; controlling the switch tube in the power circuit based on the increased working frequency.

6. The starting method of a switching power supply according to claim 1, wherein When the control parameter is a duty cycle, the S11 comprises: controlling the switch tube in the power circuit to work with a minimum duty cycle when the switching power supply starts; The duty cycle is increased by a third preset value every fourth preset time, and the first preset time comprises a plurality of the fourth preset time. The switch tube in the power circuit is controlled to act based on the increased duty cycle.

7. The starting method of a switching power supply according to any one of claims 1 to 6, characterized in that, The feedback output value of the feedback circuit is calculated based on the difference value and saved, comprising: The feedback output value of the feedback circuit is calculated based on the difference value and preset proportional integral differential (PID) parameters using a PID algorithm.

8. The starting method of a switching power supply according to any one of claims 1 to 6, characterized in that, The S12, the S13 and the S14 are executed once every fifth preset time within the first preset time, and the first preset time comprises a plurality of the fifth preset time.

9. A starting device for a switching power supply, characterized by Comprise: A memory for storing a computer program; A control circuit for implementing the steps of the starting method of the switching power supply according to any one of claims 1-8 when the computer program is executed.

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