CN115498884A - Working mode control method and circuit of switching power supply and switching power supply - Google Patents

Working mode control method and circuit of switching power supply and switching power supply Download PDF

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Publication number
CN115498884A
CN115498884A CN202211253657.XA CN202211253657A CN115498884A CN 115498884 A CN115498884 A CN 115498884A CN 202211253657 A CN202211253657 A CN 202211253657A CN 115498884 A CN115498884 A CN 115498884A
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China
Prior art keywords
power supply
switching power
clock
preset
output
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CN202211253657.XA
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Chinese (zh)
Inventor
王峰
应征
陈波
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BCD Shanghai Micro Electronics Ltd
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BCD Shanghai Micro Electronics Ltd
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Priority to CN202211253657.XA priority Critical patent/CN115498884A/en
Publication of CN115498884A publication Critical patent/CN115498884A/en
Priority to PCT/CN2023/107375 priority patent/WO2024078078A1/en
Priority to JP2023141878A priority patent/JP2024058585A/en
Pending legal-status Critical Current

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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/0048—Circuits or arrangements for reducing losses
    • H02M1/0054—Transistor switching losses
    • H02M1/0058—Transistor switching losses by employing soft switching techniques, i.e. commutation of transistors when applied voltage is zero or when current flow is zero
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
    • H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
    • H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/33569—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements
    • H02M3/33576—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements having at least one active switching element at the secondary side of an isolation transformer
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
    • Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Dc-Dc Converters (AREA)

Abstract

The invention discloses a switching power supply and a working mode control method and circuit thereof, and relates to the field of switching power supply control. And comprehensively controlling the switching power supply to enter different working modes according to the output voltage, the load and the input line voltage of the switching power supply. When the output voltage is smaller than the first preset voltage threshold and the load is a heavy load, the switching power supply is controlled to work in a CCM or DCM mode, and the problem that the switching power supply is low in working frequency and easy to damage due to the QR mode limitation when the switching power supply has a low output voltage requirement is solved. When the output voltage is not less than the first preset voltage threshold and the load is a heavy load, the switching power supply is controlled to work in one mode of CCM, DCM or QR according to the input line voltage, and the working efficiency of the switching power supply is ensured.

Description

Working mode control method and circuit of switching power supply and switching power supply
Technical Field
The present invention relates to the field of switching power supply control, and in particular, to a method and a circuit for controlling a working mode of a switching power supply with a wide output range, and a switching power supply.
Background
The switching power supply is widely applied due to the characteristics of simple circuit structure and capability of efficiently providing multi-path direct current output. The operation modes of the switching power supply include CCM (continuous Conduction Mode), DCM (discontinuous Conduction Mode), and QR (Quasi-Resonant Mode). In the prior art, when a load connected to the rear end of the switching power supply is heavy load and the input line voltage is high voltage, the switching power supply is controlled to work in the QR mode. However, when the switching power supply has a wider output voltage requirement, for example, a lower output voltage requirement, the operating frequency of the switching power supply is limited due to the characteristics of the QR mode, so that the stress of the transformer in the switching power supply is increased, and the problems of saturation of the magnetic element and damage to the switching power supply are easily caused.
Disclosure of Invention
The invention aims to provide a method and a circuit for controlling the working mode of a switching power supply and the switching power supply, which can comprehensively control the switching power supply to enter different working modes according to the output voltage, the load and the input line voltage of the switching power supply.
In order to solve the above technical problem, the present invention provides a method for controlling a working mode of a switching power supply, including:
judging whether the output voltage of the switching power supply is smaller than a first preset voltage threshold value or not;
if so, controlling the switching power supply to enter a CCM or DCM working mode when the load of the switching power supply meets a preset heavy load condition;
if not, when the load of the switching power supply meets the preset heavy-load condition, controlling the switching power supply to enter a CCM or DCM or a QR working mode according to the input line voltage of the switching power supply.
Preferably, after determining whether the output voltage of the switching power supply is smaller than a first preset voltage threshold, the method further includes:
and if so, controlling the switching power supply to enter a DCM working mode when the load of the switching power supply meets a preset light load condition.
Preferably, after determining whether the output voltage of the switching power supply is smaller than a first preset voltage threshold, the method further includes:
and if not, controlling the switching power supply to enter a DCM working mode when the load of the switching power supply meets a preset light load condition.
Preferably, the controlling the switching power supply to enter a CCM or DCM, or QR operating mode according to the input line voltage of the switching power supply includes:
when the input line voltage is greater than a second preset voltage threshold, controlling the switching power supply to enter a QR working mode;
and when the input line voltage is not greater than the second preset voltage threshold, controlling the switching power supply to enter the CCM or DCM working mode.
Preferably, the controlling the switching power supply to enter the CCM or DCM operation mode or the QR operation mode according to the input line voltage of the switching power supply includes:
and controlling the switching power supply to enter the QR working mode within the full voltage range of the input line voltage.
In order to solve the above technical problem, the present application further provides a working mode control circuit of a switching power supply, including:
the mode control module is used for generating a first clock signal when the output voltage of the switching power supply is smaller than a first preset voltage threshold and the load of the switching power supply meets a preset heavy load condition, and generating a second clock signal according to the input line voltage of the switching power supply when the output voltage is not smaller than the first preset voltage threshold and the load meets the preset heavy load condition;
and the power switch control module is used for controlling the state of a power switch in the switching power supply according to the first clock signal so as to control the switching power supply to enter a CCM or DCM working mode, and controlling the state of the power switch according to the second clock signal so as to control the switching power supply to enter the CCM or DCM or QR working mode.
Preferably, the mode control module comprises a clock output selector, a first clock module and a second clock module;
the output end of the first clock module and the output end of the second clock module are respectively connected with the first clock input end and the second clock input end of the clock output selector, and the output end of the clock output selector is used as the output end of the mode control module;
the first clock module is used for generating the first clock signal, and the frequency of the first clock signal is positively correlated with the size of the load;
the second clock module is used for generating a second clock signal based on the primary side resonance waveform when the valley number of the primary side resonance waveform of the switching power supply is not more than a preset valley number threshold value, and generating a second clock signal with the frequency positively correlated with the load size when the valley number of the primary side resonance waveform is more than the preset valley number threshold value;
the clock output selector is used for outputting a first clock signal generated by the first clock module when the output voltage is smaller than the first preset voltage threshold and the load meets the preset heavy load condition, and outputting a second clock signal output by the second clock output selector when the output voltage is not smaller than the first preset voltage threshold and the load meets the preset heavy load condition.
Preferably, the second clock module includes a second clock submodule, a valley bottom locking module and a second clock output selector;
the output end of the second clock submodule and the output end of the valley bottom locking module are respectively connected with the first input end and the second input end of the second clock output selector, and the output end of the second clock output selector is connected with the second clock input end of the clock output selector;
the second clock submodule is used for generating a second clock sub-signal when the valley number of the primary side resonance waveform of the switching power supply is larger than a preset valley number threshold value, the frequency of the second clock sub-signal is in negative correlation with the valley number of the primary side resonance waveform, and the valley number of the primary side resonance waveform is in negative correlation with the size of the load;
the valley bottom locking module is used for controlling the primary side resonance waveform to be opened at a plurality of valley bottoms when the number of valley bottoms of the primary side resonance waveform is not more than the preset valley bottom threshold value, and taking the primary side resonance waveform opened at the valley bottoms as a second clock valley bottom signal;
the second clock output selector is configured to output a second clock valley signal generated by the valley bottom locking module to the clock output selector as the second clock signal when the number of valleys of the primary-side resonant waveform is greater than the preset valley bottom threshold value, and output a second clock sub-signal generated by the second clock sub-module to the clock output selector as the second clock signal when the number of valleys of the primary-side resonant waveform is not greater than the preset valley bottom threshold value.
Preferably, the power switch control module comprises an and gate, a D flip-flop and a driving circuit;
the first input end of the AND gate and the clock signal input end of the D trigger are both connected with the output end of the mode control module, the positive phase output end of the D trigger is connected with the second input end of the AND gate, the output end of the AND gate is connected with the input end of the driving circuit, and the output end of the driving circuit is used as the output end of the power switch control module and is connected with the control end of the power switch;
the driving circuit is used for amplifying a signal output by the output end of the AND gate so as to control the state of the power switch.
Preferably, the mode control module is further configured to generate a third clock signal when the output voltage of the switching power supply is smaller than the first preset voltage threshold and the load meets a preset light load condition;
the power switch control module is further configured to control a state of the power switch based on the third clock signal so as to control the switching power supply to enter a DCM operation mode.
Preferably, the mode control module is further configured to generate a fourth clock signal when the output voltage of the switching power supply is not less than the first preset voltage threshold and the load meets a preset light load condition;
the power switch control module is further configured to control a state of the power switch based on the fourth clock signal so as to control the switching power supply to enter a DCM operation mode.
Preferably, the mode control module is specifically configured to generate a first clock signal when the output voltage of the switching power supply is less than a first preset voltage threshold and the load of the switching power supply meets a preset heavy load condition; generating a fifth clock signal when the output voltage is not less than the first preset voltage threshold, the load meets the preset overloading condition, and the input line voltage is greater than a second preset voltage threshold; generating a sixth clock signal when the output voltage is not less than the first preset voltage threshold, the load meets the preset overloading condition, and the input line voltage is not greater than a second preset voltage threshold;
the power switch control module is specifically used for controlling the state of a power switch in the switching power supply according to the first clock signal so as to control the switching power supply to enter a CCM or DCM working mode; controlling the state of the power switch according to the fifth clock signal so as to control the switching power supply to enter a QR (quick response) working mode; and controlling the state of the power switch according to the sixth clock signal so as to control the switching power supply to enter a CCM or DCM working mode.
Preferably, the mode control module is specifically configured to generate a first clock signal when an output voltage of the switching power supply is less than a first preset voltage threshold and a load of the switching power supply meets a preset heavy load condition, and generate the second clock signal when the output voltage is not less than the first preset voltage threshold, the load meets the preset heavy load condition and the input line voltage is within a full voltage range;
the power switch control module is specifically configured to control a state of the power switch according to the first clock signal so as to control the switching power supply to enter a CCM or DCM operating mode, and control a state of the power switch according to the second clock signal so as to control the switching power supply to enter a QR operating mode.
In order to solve the above technical problem, the present application further provides a switching power supply, including the above operating mode control circuit of the switching power supply, further including:
the rectifier filter module is used for converting input alternating current into direct current and outputting the filtered direct current to the primary side of the transformer;
the transformer;
the output module is arranged between the secondary side of the transformer and a load and used for generating voltage based on the voltage of the secondary side of the transformer, and the voltage values of the output voltages are different from each other;
and the control end of the power switch is connected with the output end of the control device of the switching power supply.
In summary, the present invention provides a method and a circuit for controlling a working mode of a switching power supply, and the switching power supply, wherein the switching power supply is controlled to enter different working modes according to an output voltage, a load and an input line voltage of the switching power supply. When the output voltage is smaller than the first preset voltage threshold and the load is a heavy load, the switching power supply is controlled to work in a CCM or DCM mode, and the problem that the switching power supply is low in working frequency and easy to damage due to the QR mode limitation when the switching power supply has a low output voltage requirement is solved. When the output voltage is not less than a first preset voltage threshold and the load is a heavy load, controlling the switching power supply to work in one mode of CCM, DCM or QR according to the input line voltage, and ensuring the working efficiency of the switching power supply; meanwhile, the method can be suitable for a switching power supply application system with a wider output voltage/current range.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed in the prior art and the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.
Fig. 1 is a schematic flow chart of a method for controlling an operating mode of a switching power supply according to the present invention;
fig. 2 is a schematic diagram of a first control manner of a method for controlling an operating mode of a switching power supply according to the present invention;
fig. 3 is a schematic diagram illustrating a second control manner of the method for controlling the operating mode of the switching power supply according to the present invention;
fig. 4 is a schematic diagram illustrating a third control manner of the method for controlling the operating mode of the switching power supply according to the present invention;
fig. 5 is a schematic structural diagram of a working mode control circuit of a switching power supply according to the present invention;
fig. 6 is a schematic structural diagram of a mode control module in a working mode control circuit of a switching power supply according to the present invention;
fig. 7 is a circuit diagram of a switching power supply according to the present invention.
Detailed Description
The core of the invention is to provide a method and a circuit for controlling the working mode of a switching power supply and the switching power supply, which can comprehensively control the switching power supply to enter different working modes according to the output voltage, the load and the input line voltage of the switching power supply.
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, belong to the protection scope of the present invention.
Referring to fig. 1, fig. 1 is a schematic flow chart of a method for controlling a working mode of a switching power supply according to the present invention, the method including:
s1: judging whether the output voltage of the switching power supply is smaller than a first preset voltage threshold value or not; if yes, entering S2; if not, entering S3;
s2: when the load of the switching power supply meets a preset heavy load condition, controlling the switching power supply to enter a CCM or DCM working mode;
s3: when the load of the switch power supply meets the preset heavy load condition, the switch power supply is controlled to enter a CCM or DCM working mode or a QR working mode according to the input line voltage of the switch power supply.
The switch power supply can provide multi-path output voltages with different voltage values, can be used as a charger and the like, and has wider application. At present, the common working modes of the switching power supply are three types: discontinuous mode of operation (DCM), continuous mode of operation (CCM), and quasi-resonant mode (QR). Each working mode has respective characteristics, and the DCM has the advantages of small switching loss and good stability, but also has the defects of lower working frequency and lower efficiency; CCM has the advantage of a relatively high operating frequency, but is prone to stability problems; the QR mode operates at a higher frequency and efficiency than DCM, but due to the conduction of the power tube near the bottom of the resonance valley, the spectrum is more concentrated and EMI is relatively poor.
When the switching power supply is controlled, the requirements under different conditions are usually met by combining the working modes, but in the prior art, generally, only the input line voltage of the switching power supply is high line voltage or low line voltage, and the condition that different working modes are selected as the condition that the load connected with the switching power supply is light load, heavy load or full load is adopted, so that the switching power supply with a wider output voltage range in practical application cannot select the most appropriate working mode when the requirements of different output voltages are met. For example, in the prior art, when the load is heavy and the input voltage is a high line voltage, the switching power supply is controlled to operate in the QR mode, and when the input voltage is a low line voltage, the switching power supply is controlled to operate in the CCM. However, when the load is heavy and the input voltage is high-line voltage, if the switching power supply needs to output a low output voltage and a large current (for example, when there is a multi-output), the operating characteristics of the QR mode itself cause a relatively large reduction in the system frequency when the switching power supply is fully loaded, which increases the stress of the transformer in the switching power supply, and tends to cause saturation of the magnetic elements, thereby causing power supply failure.
Therefore, in the present application, the output voltage, the load and the input line voltage of the switching power supply are simultaneously used as the selection basis for controlling the switching power supply to enter different operation modes. Specifically, the switching power supply is divided into two cases of a low output voltage and a high output voltage according to the output voltage, and the division is specifically performed by judging whether the output voltage of the switching power supply is smaller than a first preset voltage threshold. When the output voltage is smaller than the first preset voltage threshold, namely, the output voltage is a low output voltage, if the load is a heavy load, the switching power supply is controlled to work in a CCM or DCM working mode, the frequency of the switching power supply can be improved, the size of the switching power supply can be reduced, and the problems that in the prior art, the frequency of a system is reduced more, the stress of a transformer is increased, the saturation of magnetic elements is easy to occur, the power supply is damaged and the like due to the fact that the switching power supply is controlled to work in a QR mode under the condition can be avoided.
It should be noted that the specific value of the first preset voltage threshold may also be set according to actual situations, and may be set to 7.5V. The preset overloading condition is not particularly limited, and the full-loading condition can be included in the preset overloading condition.
The specific working mode of the switching power supply under the conditions that the output voltage is high voltage and the load is heavy load is not particularly limited, and the switching power supply can be selected to work in a QR mode all the time according to the difference of the input line voltage, or work in the QR mode when the input line voltage is high line voltage, and work in a CCM or DCM when the input line voltage is low line voltage.
In summary, the present invention provides a control method for a switching power supply, which comprehensively controls the switching power supply to enter different operating modes according to an output voltage, a load and an input line voltage of the switching power supply. When the output voltage is smaller than the first preset voltage threshold and the load is a heavy load, the switching power supply is controlled to work in a CCM or DCM mode, and the problem that the switching power supply is low in working frequency and easy to damage due to the QR mode limitation when the switching power supply has a low output voltage requirement is solved. When the output voltage is not less than the first preset voltage threshold and the load is a heavy load, the switching power supply is controlled to work in one mode of CCM, DCM or QR according to the input line voltage, and the working efficiency of the switching power supply is ensured.
On the basis of the above-described embodiment:
as a preferred embodiment, after determining whether the output voltage of the switching power supply is smaller than the first preset voltage threshold, the method further includes:
and if so, controlling the switching power supply to enter a DCM working mode when the load of the switching power supply meets a preset light load condition.
In order to further ensure that the switching power supply can select the most appropriate operating mode under various conditions, the operating mode of the switching power supply under light load is further provided in the embodiment. Referring to fig. 2, fig. 2 is a schematic diagram illustrating a first control manner of a method for controlling an operating mode of a switching power supply according to the present invention, in fig. 2, a horizontal axis represents a load, a vertical axis represents an input line voltage, vo represents an output voltage, and Vref represents a first predetermined voltage threshold. Specifically, it is still necessary to determine whether the switching power supply is a low output voltage or a high output voltage according to the output voltage of the switching power supply. In this embodiment, when the output voltage is smaller than the first preset voltage threshold, that is, the output voltage is a low output voltage, if the load is no-load, the switching power supply is controlled to use DCM as the operating mode, so that the size of the transformer can be reduced, and the system efficiency is also considered.
The preset light load condition required when the load is judged to be light load is not particularly limited, and the no-load condition can be included in the range of the preset light load condition.
In summary, in the embodiment, if the size of the switching power supply is preferably reduced in practical applications and the efficiency of the switching power supply is considered, the switching power supply is controlled to enter the DCM operation mode when the switching power supply simultaneously satisfies the condition that the load is no load and the output voltage is low.
As a preferred embodiment, after determining whether the output voltage of the switching power supply is smaller than the first preset voltage threshold, the method further includes:
and if not, controlling the switching power supply to enter a DCM working mode when the load of the switching power supply meets the preset light load condition.
In order to further ensure that the switching power supply can select the most appropriate operating mode under various conditions, the operating mode of the switching power supply under light load is further provided in the embodiment. Specifically, it is still necessary to determine whether the switching power supply is a low output voltage or a high output voltage according to the output voltage of the switching power supply. In this embodiment, when the output voltage is not less than the first predetermined voltage threshold, that is, the output voltage is a high output voltage, if the load is no load, the switching power supply is controlled to use DCM as the operating mode, so that the stability of the system can be ensured, and the switching loss can be reduced.
Referring to fig. 3, fig. 3 is a schematic diagram of a second control method of the method for controlling the operating mode of the switching power supply according to the present invention, in which a horizontal axis of fig. 3 is a load, a vertical axis thereof is an input line voltage, vo is an output voltage, and Vref is a first preset voltage threshold.
As a preferred embodiment, controlling the switching power supply to enter the CCM or DCM, or QR, operating mode according to the input line voltage of the switching power supply includes:
when the input line voltage is greater than a second preset voltage threshold value, controlling the switching power supply to enter a QR working mode;
and when the input line voltage is not greater than a second preset voltage threshold value, controlling the switching power supply to enter a CCM or DCM working mode.
In order to further ensure that the switching power supply can select the most appropriate operating mode under various conditions, in this embodiment, when the load at the rear end of the switching power supply is heavy or full, different operating modes are further selected according to different input line voltages. Specifically, when the load is heavy and the input line voltage is greater than a second preset voltage threshold value, namely, when the input line voltage is high line voltage, the switching power supply is controlled to enter a QR (quick response) working mode, so that the system efficiency is improved; when the load is a heavy load and the input line voltage is not greater than the second preset voltage threshold value, namely the low line voltage, the switching power supply is controlled to enter a CCM or DCM working mode, the system efficiency is further improved, and the small size of the switching power supply is ensured.
Referring to fig. 3, fig. 3 is a schematic diagram illustrating a second control manner of the method for controlling the operating mode of the switching power supply according to the present invention, in which a horizontal axis of fig. 3 is a load, a vertical axis thereof is an input line voltage, vo is an output voltage, vref is a first predetermined voltage threshold, and VL1 is a second predetermined voltage threshold.
The specific value of the second preset voltage threshold is not particularly limited, for example, when the output voltage of the switching power supply ranges from 3.3V to 20V or from 5V to 20V, the first preset voltage threshold may be 7.5V, and the second preset voltage threshold may be 180V.
As a preferred embodiment, controlling the switching power supply to enter the CCM or DCM, or QR, operating mode according to the input line voltage of the switching power supply includes:
and controlling the switching power supply to enter a QR (quick response) working mode in a full voltage range of the input line voltage.
Referring to fig. 4, fig. 4 is a schematic diagram illustrating a third control method of the method for controlling the operating mode of the switching power supply according to the present invention, in which a horizontal axis of fig. 4 is a load, a vertical axis thereof is an input line voltage, vo is an output voltage, and Vref is a first preset voltage threshold.
In order to further ensure that the switching power supply can select the most appropriate working mode under various conditions, in this embodiment, when the load at the rear end of the switching power supply is a heavy load, the switching power supply is controlled to always work in the QR working mode no matter the input line voltage is a low line voltage or a high line voltage, that is, the switching power supply is controlled to always work in the QR working mode in the full voltage range of the input line voltage, so that the efficiency of the switching power supply can be ensured to the greatest extent, and the performance of the switching power supply is improved. Therefore, the control strategy in the present embodiment can be selected in the case where the switching power supply is heavily loaded and the output voltage is high, with priority given to improving the system efficiency.
Referring to fig. 5, fig. 5 is a schematic structural diagram of a working mode control circuit of a switching power supply provided in the present invention, the control circuit includes:
the mode control module 1 is used for generating a first clock signal when the output voltage of the switching power supply is smaller than a first preset voltage threshold and the load of the switching power supply meets a preset overloading condition, and generating a second clock signal according to the input line voltage of the switching power supply when the output voltage is not smaller than the first preset voltage threshold and the load meets the preset overloading condition;
and the power switch control module 2 is used for controlling the state of a power switch in the switching power supply according to the first clock signal so as to control the switching power supply to enter a CCM or DCM working mode, and controlling the state of the power switch according to the second clock signal so as to control the switching power supply to enter the CCM or DCM or QR working mode.
In the application, the output voltage, the load and the input line voltage of the switching power supply are simultaneously used as selection bases for controlling the switching power supply to enter different working modes. Specifically, the switching power supply is divided into two cases, namely a low output voltage and a high output voltage according to the output voltage, and the division is specifically performed by judging whether the output voltage of the switching power supply is smaller than a first preset voltage threshold. When the output voltage is smaller than the first preset voltage threshold, that is, the output voltage is a low output voltage, if the load is a heavy load, the first clock signal is generated through the mode control module 1, and the power switch module can control the switch power supply to work in a CCM or DCM working mode based on the first clock signal after receiving the first clock signal, so that the frequency of the switch power supply can be increased, the size of the switch power supply can be reduced, and meanwhile, the problems that in the prior art, the system frequency is reduced more due to the fact that the switch power supply is controlled to work in a QR mode, the stress of a transformer is increased, magnetic element saturation is easy to occur, and the power supply is damaged and the like can be avoided.
It should be noted that the specific value of the first preset voltage threshold may be set according to practical situations, and may be set to 7.5V. The preset overloading condition is not particularly limited, and the overload condition can be set according to the actual condition.
The specific working mode of the switching power supply under the conditions that the output voltage is high voltage and the load is heavy load is not particularly limited, and the switching power supply can be selected to work in the QR mode all the time according to the difference of the input line voltage, or work in the QR mode when the input voltage is high line voltage, and work in the CCM or DCM mode when the input voltage is low line voltage. Specifically, the second clock signal is generated when the output voltage is not less than the first preset voltage threshold, that is, the output voltage is a high voltage and the load is a heavy load, and the second clock signal is related to the input line voltage of the switching power supply. The power switch control module 2 controls the switching power supply to enter a CCM or DCM working mode or a QR working mode based on the second clock signal.
In summary, the present invention discloses a working mode control circuit of a switching power supply, which includes a mode control module 1 and a power switch control module 2. The mode control module 1 comprehensively generates clock signals for controlling the switching power supply to enter different working modes based on the output voltage, the load and the input line voltage of the switching power supply. The power switch control module 2 controls the switching power supply to enter a CCM or DCM mode when the output voltage is smaller than a first preset voltage threshold and the load is a heavy load, so that the problem that the working frequency of the switching power supply is low and the switching power supply is easy to damage due to the restriction of a QR mode when the switching power supply has a low output voltage requirement is solved, the switching power supply enters the CCM or DCM mode when the output voltage is not smaller than the first preset voltage threshold and the load is the heavy load, or the QR mode works, and the working efficiency of the switching power supply is ensured.
On the basis of the above-described embodiment:
as a preferred embodiment, the mode control module 1 includes a clock output selector 011, a first clock module 012 and a second clock module 013;
the output end of the first clock module 012 and the output end of the second clock module 013 are respectively connected with the first clock input end and the second clock input end of the clock output selector 011, and the output end of the clock output selector 011 is used as the output end of the mode control module 1;
the first clock module 012 is configured to generate a first clock signal, where a frequency of the first clock signal is positively correlated to a magnitude of a load;
the second clock module 013 is configured to generate a second clock signal based on the primary side resonance waveform when the number of valley bottoms of the primary side resonance waveform of the switching power supply is not greater than the preset valley bottom threshold value, and generate a second clock signal whose frequency is in positive correlation with the size of the load when the number of valley bottoms of the primary side resonance waveform is greater than the preset valley bottom threshold value;
the clock output selector 011 is configured to output the first clock signal generated by the first clock module 012 when the output voltage is less than the first preset voltage threshold and the load meets the preset reload condition, and output the second clock signal output by the second clock output selector 133 when the output voltage is not less than the first preset voltage threshold and the load meets the preset reload condition.
In this embodiment, the first clock module itself may generate the first clock signal, and the frequency of the first clock signal is in positive correlation with the magnitude of the load, so that when the load is a heavy load, the frequency of the first clock signal is higher, and at this time, the power switch control module 2 may cause the switching power supply to enter the CCM operation mode when the state of the power switch is controlled by the first clock signal. When the load is decreased, the frequency of the first clock signal is decreased, and the power switch control module 2 may cause the switching power supply to enter the DCM operation mode when controlling the state of the power switch by the first clock signal.
The QR mode of operation switches on for the preceding several valleys of presetting the valley number threshold value at primary side resonance waveform, DCM mode of operation switches on for the random moment at primary side resonance waveform, consequently the second clock module generates the second clock signal so that switching power supply gets into QR mode based on primary side resonance waveform when the valley number of the primary side resonance waveform of switching power supply is not more than presetting the valley number threshold value, the size that generates frequency and load when the valley number of primary side resonance waveform is greater than presetting the valley number threshold value is positive correlation's second clock signal so that switching power supply gets into DCM mode.
As a preferred embodiment, the second clock module 013 includes the second clock submodule 131, the valley lock module 132, and the second clock output selector 133;
the output end of the second clock submodule 131 and the output end of the valley bottom locking module 132 are respectively connected with the first input end and the second input end of the second clock output selector 133, and the output end of the second clock output selector 133 is connected with the second clock input end of the clock output selector 011;
the second clock submodule 131 is configured to generate a second clock sub-signal when the number of valley bottoms of the primary-side resonant waveform of the switching power supply is greater than a preset valley bottom threshold, where the frequency of the second clock sub-signal is negatively related to the number of valley bottoms of the primary-side resonant waveform, and the number of valley bottoms of the primary-side resonant waveform is negatively related to the size of the load;
the valley bottom locking module 132 is configured to control the primary side resonance waveform to be opened at a plurality of valley bottoms of the valley bottoms when the number of valley bottoms of the primary side resonance waveform is not greater than the preset valley bottom threshold value, and use the primary side resonance waveform opened at the plurality of valley bottoms as a second clock valley bottom signal;
the second clock output selector 133 is configured to output the second clock bottom signal generated by the bottom locking module 132 to the clock output selector 011 as a second clock signal when the number of the bottoms of the primary side resonance waveform is greater than the preset bottom threshold, and output the second clock sub-signal generated by the second clock sub-module 131 to the clock output selector 011 as the second clock signal when the number of the bottoms of the primary side resonance waveform is not greater than the preset bottom threshold.
Referring to fig. 6, fig. 6 is a schematic structural diagram of a mode control module in a working mode control circuit of a switching power supply according to the present invention. In fig. 6, a clock selection 1 is a clock output selector 011, a frequency control 1 and the clock 1 jointly form a first clock module 012, a frequency control 2 and the clock 2 jointly form a second clock module 013, the clock selection 2 is a second clock output selector 133, N is the number of valleys of a primary side resonance waveform, N is a preset Valley threshold, COMP is a parameter positively correlated with a load, valley is a primary side resonance wave, line is an input Line voltage, vout is an output voltage, CLK1 is a first clock signal, CLK2 is a second clock signal, and CLK is a clock signal finally used for controlling a power switch. In addition, the Slope signal in fig. 6 is used to realize Slope compensation of the switching power supply in the CCM mode so as to suppress harmonic oscillation.
The present embodiment provides a specific structure of the mode control module 1 for generating the first clock signal and the second clock signal, and the clock output selector 011 can select whether to output the first clock signal generated by the first clock module 012 or the second clock signal generated by the second clock submodule 131, the bottom-of-valley lock module 132, and the second clock output selector 133 based on the output voltage of the switching power supply.
Specifically, the first clock module itself may generate the first clock signal, and the frequency of the first clock signal is in positive correlation with the size of the load, so that when the load is a heavy load, the frequency of the first clock signal is relatively high, and at this time, the power switch control module 2 may cause the switching power supply to enter the CCM operating mode when the state of the power switch is controlled by the first clock signal. When the load is decreased, the frequency of the first clock signal is decreased, and the power switch control module 2 may cause the switching power supply to enter the DCM operation mode when controlling the state of the power switch by the first clock signal.
Because the valley bottom number of the primary side resonance waveform is negatively correlated with the load size, when the load is a heavy load, the valley bottom number of the primary side resonance waveform is smaller than the preset valley bottom threshold value, and therefore the valley bottom locking module 132 is turned on at the valley bottoms of the valley bottoms number to generate a new clock signal, namely, a second clock valley bottom signal and takes the second clock valley bottom signal as the second clock signal, and when the power switch control module 2 controls the state of the power switch by using the signal, the switching power supply can enter the QR working mode. As the load is gradually reduced, the valley number of the primary-side resonant waveform is gradually increased until the valley number is not less than the preset valley threshold, so that the second clock sub-module 131 generates the second clock sub-signal and the frequency of the second clock sub-signal is in positive correlation with the load, and thus the switching power supply can enter the DCM operating mode when the power switch control module 2 controls the power switch by using the second clock sub-signal.
In summary, the mode control module 1 provided in this embodiment can generate clock signals for enabling the switching power supply to enter various operating modes, and then the clock output selector 011 in the mode control module 1 can select different clock signals under different conditions, so as to achieve the purpose of controlling the switching power supply to enter different operating modes under different conditions, and the circuit structure is simple and easy to implement.
As a preferred embodiment, the power switch control module 2 includes an and gate, a D flip-flop and a driving circuit;
the first input end of the AND gate and the clock signal input end of the D trigger are both connected with the output end of the mode control module 1, the normal phase output end of the D trigger is connected with the second input end of the AND gate, the output end of the AND gate is connected with the input end of the drive circuit, and the output end of the drive circuit is connected with the control end of the power switch as the output end of the power switch control module 2;
the driving circuit is used for amplifying a signal output by the output end of the AND gate so as to control the state of the power switch.
Referring to fig. 5, fig. 5 is a schematic structural diagram of a working mode control circuit of a switching power supply provided by the present invention, in fig. 5, COMP is a signal reflecting a load size, valley is a primary side resonance wave, line is an input Line voltage, vout is an output voltage, CLK is a clock signal for controlling a power switch, gate is a signal received by a control terminal of the power switch, and a Slope signal is used to implement Slope compensation of the switching power supply in a CCM mode so as to suppress harmonic oscillation.
The clock signal output by the mode control module 1 is connected with the clock signal input end of the D trigger in the power switch control module 2 and the first input end of the AND gate, the AND gate enables the clock signal output by the mode control module 11 and the signal output by the D trigger to be in phase and transmitted to the driving circuit, the driving circuit amplifies the signal output by the AND gate to a signal which can be used for controlling the power switch and then inputs the signal to the control end of the power switch so as to control the state of the power switch, and therefore the control of the working mode of the switching power supply is achieved.
In summary, the power switch control module 2 provided in this embodiment can achieve the purpose of controlling the power switch based on the first clock signal and the second clock signal, and the circuit structure is simple and easy to implement.
As a preferred embodiment, the mode control module 1 is further configured to generate a third clock signal when the output voltage of the switching power supply is less than a first preset voltage threshold and the load meets a preset light load condition;
the power switch control module 2 is further configured to control the state of the power switch based on the third clock signal so as to control the switching power supply to enter the DCM operation mode.
For the related description of this embodiment, please refer to an embodiment corresponding to the method for controlling the operating mode of the switching power supply, which is not described herein again.
As a preferred embodiment, the mode control module 1 is further configured to generate a fourth clock signal when the output voltage of the switching power supply is not less than the first preset voltage threshold and the load meets a preset light load condition;
the power switch control module 2 is further configured to control the state of the power switch based on the fourth clock signal so as to control the switching power supply to enter the DCM operation mode.
For the related introduction of this embodiment, please refer to an embodiment corresponding to the method for controlling the operating mode of the switching power supply, which is not described herein again.
As a preferred embodiment, the mode control module 1 is specifically configured to generate a first clock signal when the output voltage of the switching power supply is less than a first preset voltage threshold and the load of the switching power supply meets a preset heavy load condition; generating a fifth clock signal when the output voltage is not less than the first preset voltage threshold, the load meets the preset overloading condition, and the input line voltage is greater than the second preset voltage threshold; generating a sixth clock signal when the output voltage is not less than the first preset voltage threshold, the load meets the preset overloading condition, and the input line voltage is not greater than the second preset voltage threshold;
the power switch control module 2 is specifically configured to control a state of a power switch in the switching power supply according to the first clock signal so as to control the switching power supply to enter a CCM or DCM operating mode; controlling the state of the power switch according to a fifth clock signal so as to control the switching power supply to enter a QR working mode; and controlling the state of the power switch according to the sixth clock signal so as to control the switching power supply to enter a CCM or DCM working mode.
For the related description of this embodiment, please refer to an embodiment corresponding to the method for controlling the operating mode of the switching power supply, which is not described herein again.
As a preferred embodiment, the mode control module 1 is specifically configured to generate a first clock signal when the output voltage of the switching power supply is less than a first preset voltage threshold and the load of the switching power supply meets a preset heavy load condition, and generate a second clock signal when the output voltage is not less than the first preset voltage threshold and the load meets the preset heavy load condition and the input line voltage is within a full voltage range;
the power switch control module 2 is specifically configured to control the state of the power switch according to the first clock signal so as to control the switching power supply to enter the CCM or DCM operating mode, and control the state of the power switch according to the second clock signal so as to control the switching power supply to enter the QR operating mode.
For the related description of this embodiment, please refer to an embodiment corresponding to the method for controlling the operating mode of the switching power supply, which is not described herein again.
In order to solve the above technical problem, the present application further provides a switching power supply, including the above operating mode control circuit of the switching power supply, further including:
the rectifier filter module is used for converting input alternating current into direct current and outputting the filtered direct current to the primary side of the transformer;
a transformer;
the output module is arranged between the secondary side of the transformer and the load and used for generating voltage based on the voltage of the secondary side of the transformer, and the voltage values of the output voltages are different from each other;
and the control end of the power switch is connected with the output end of the control device of the switching power supply.
The switching power supply in the present application may be a switching power supply with a wide voltage output range, which is capable of selecting the most suitable operation mode when facing different output voltage requirements. Referring to fig. 7, fig. 7 is a circuit diagram of a switching power supply according to the present invention. The switching power supply in fig. 7 is a flyback switching power supply, and the switching power supply is enabled to work in different working modes by controlling the conduction condition of the power switch through the control device of the switching power supply, so as to ensure the working performance of the switching power supply.
In the present specification, the embodiments are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. The device disclosed in the embodiment corresponds to the method disclosed in the embodiment, so that the description is simple, and the relevant points can be referred to the description of the method part.
It is further noted that, in the present specification, relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrases "comprising one of 8230; \8230;" 8230; "does not exclude the presence of additional like elements in a process, method, article, or apparatus that comprises the element.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (14)

1. A method for controlling the working mode of a switching power supply is characterized by comprising the following steps:
judging whether the output voltage of the switching power supply is smaller than a first preset voltage threshold value or not;
if so, controlling the switching power supply to enter a CCM or DCM working mode when the load of the switching power supply meets a preset heavy load condition;
if not, when the load of the switching power supply meets the preset heavy-load condition, controlling the switching power supply to enter a CCM or DCM or a QR working mode according to the input line voltage of the switching power supply.
2. The method for controlling the operation mode of the switching power supply according to claim 1, further comprising, after determining whether the output voltage of the switching power supply is less than a first preset voltage threshold:
and if so, controlling the switching power supply to enter a DCM working mode when the load of the switching power supply meets a preset light load condition.
3. The method for controlling the operation mode of the switching power supply according to claim 1, further comprising, after determining whether the output voltage of the switching power supply is less than a first preset voltage threshold:
and if not, controlling the switching power supply to enter a DCM working mode when the load of the switching power supply meets a preset light load condition.
4. The method for controlling the operation mode of the switching power supply according to any one of claims 1 to 3, wherein controlling the switching power supply to enter the CCM or DCM, or QR, operation mode according to the input line voltage of the switching power supply comprises:
when the input line voltage is greater than a second preset voltage threshold, controlling the switching power supply to enter a QR working mode;
and when the input line voltage is not greater than the second preset voltage threshold value, controlling the switching power supply to enter the CCM or DCM working mode.
5. The method for controlling the operation mode of the switching power supply according to any one of claims 1 to 3, wherein controlling the switching power supply to enter the CCM or DCM, or QR, operation mode according to the input line voltage of the switching power supply comprises:
and controlling the switching power supply to enter the QR working mode within the full voltage range of the input line voltage.
6. An operation mode control circuit of a switching power supply, comprising:
the mode control module is used for generating a first clock signal when the output voltage of the switching power supply is smaller than a first preset voltage threshold and the load of the switching power supply meets a preset heavy load condition, and generating a second clock signal according to the input line voltage of the switching power supply when the output voltage is not smaller than the first preset voltage threshold and the load meets the preset heavy load condition;
and the power switch control module is used for controlling the state of a power switch in the switching power supply according to the first clock signal so as to control the switching power supply to enter a CCM or DCM working mode, and controlling the state of the power switch according to the second clock signal so as to control the switching power supply to enter the CCM or DCM working mode or QR working mode.
7. The operation mode control circuit of the switching power supply according to claim 6, wherein the mode control module comprises a clock output selector, a first clock module and a second clock module;
the output end of the first clock module and the output end of the second clock module are respectively connected with the first clock input end and the second clock input end of the clock output selector, and the output end of the clock output selector is used as the output end of the mode control module;
the first clock module is used for generating the first clock signal, and the frequency of the first clock signal is positively correlated with the size of the load;
the second clock module is used for generating a second clock signal based on the primary side resonance waveform when the valley number of the primary side resonance waveform of the switching power supply is not more than a preset valley number threshold value, and generating a second clock signal with the frequency positively correlated with the load size when the valley number of the primary side resonance waveform is more than the preset valley number threshold value;
the clock output selector is used for outputting a first clock signal generated by the first clock module when the output voltage is smaller than the first preset voltage threshold and the load meets the preset heavy load condition, and outputting a second clock signal output by the second clock output selector when the output voltage is not smaller than the first preset voltage threshold and the load meets the preset heavy load condition.
8. The operation mode control circuit of the switching power supply according to claim 7, wherein the second clock module includes a second clock submodule, a valley lock module, and a second clock output selector;
the output end of the second clock submodule and the output end of the valley bottom locking module are respectively connected with the first input end and the second input end of the second clock output selector, and the output end of the second clock output selector is connected with the second clock input end of the clock output selector;
the second clock sub-module is used for generating a second clock sub-signal when the number of valley bottoms of a primary side resonance waveform of the switching power supply is larger than a preset valley bottom threshold value, the frequency of the second clock sub-signal is in negative correlation with the number of valley bottoms of the primary side resonance waveform, and the number of valley bottoms of the primary side resonance waveform is in negative correlation with the size of the load;
the valley bottom locking module is used for controlling the primary side resonance waveform to be opened at a plurality of valley bottoms when the number of valley bottoms of the primary side resonance waveform is not more than the preset valley bottom threshold value, and taking the primary side resonance waveform opened at the valley bottoms as a second clock valley bottom signal;
the second clock output selector is configured to output a second clock valley signal generated by the valley bottom locking module to the clock output selector as the second clock signal when the number of valleys of the primary-side resonant waveform is greater than the preset valley bottom threshold value, and output a second clock sub-signal generated by the second clock sub-module to the clock output selector as the second clock signal when the number of valleys of the primary-side resonant waveform is not greater than the preset valley bottom threshold value.
9. The operation mode control circuit of the switching power supply according to claim 1, wherein the power switch control module comprises an and gate, a D flip-flop and a driving circuit;
the first input end of the AND gate and the clock signal input end of the D trigger are both connected with the output end of the mode control module, the normal phase output end of the D trigger is connected with the second input end of the AND gate, the output end of the AND gate is connected with the input end of the driving circuit, and the output end of the driving circuit is used as the output end of the power switch control module and is connected with the control end of the power switch;
the driving circuit is used for amplifying a signal output by the output end of the AND gate so as to control the state of the power switch.
10. The operating mode control circuit of the switching power supply according to claim 1, wherein the mode control module is further configured to generate a third clock signal when the output voltage of the switching power supply is less than the first preset voltage threshold and the load meets a preset light load condition;
the power switch control module is further configured to control a state of the power switch based on the third clock signal so as to control the switching power supply to enter a DCM operation mode.
11. The operating mode control circuit of the switching power supply according to claim 1, wherein the mode control module is further configured to generate a fourth clock signal when the output voltage of the switching power supply is not less than the first preset voltage threshold and the load meets a preset light load condition;
the power switch control module is further configured to control a state of the power switch based on the fourth clock signal so as to control the switching power supply to enter a DCM operation mode.
12. The operating mode control circuit of the switching power supply according to any one of claims 6 to 11, wherein the mode control module is specifically configured to generate the first clock signal when the output voltage of the switching power supply is less than a first preset voltage threshold and the load of the switching power supply meets a preset overload condition; generating a fifth clock signal when the output voltage is not less than the first preset voltage threshold, the load meets the preset overloading condition, and the input line voltage is greater than a second preset voltage threshold; generating a sixth clock signal when the output voltage is not less than the first preset voltage threshold, the load meets the preset overloading condition, and the input line voltage is not greater than a second preset voltage threshold;
the power switch control module is specifically used for controlling the state of a power switch in the switching power supply according to the first clock signal so as to control the switching power supply to enter a CCM or DCM working mode; controlling the state of the power switch according to the fifth clock signal so as to control the switching power supply to enter a QR (quick response) working mode; and controlling the state of the power switch according to the sixth clock signal so as to control the switching power supply to enter a CCM or DCM working mode.
13. The operation mode control circuit of the switching power supply according to any one of claims 6 to 11, wherein the mode control module is specifically configured to generate a first clock signal when the output voltage of the switching power supply is less than a first predetermined voltage threshold and the load of the switching power supply meets a predetermined reload condition, and to generate a second clock signal when the output voltage is not less than the first predetermined voltage threshold and the load meets the predetermined reload condition and the input line voltage is within a full voltage range;
the power switch control module is specifically configured to control the state of the power switch according to the first clock signal so as to control the switching power supply to enter a CCM or DCM working mode, and control the state of the power switch according to the second clock signal so as to control the switching power supply to enter a QR working mode.
14. A switching power supply, characterized by comprising an operation mode control circuit of the switching power supply according to any one of claims 6 to 13, and further comprising:
the rectifier filter module is used for converting input alternating current into direct current and outputting the filtered direct current to the primary side of the transformer;
the transformer;
the output module is arranged between the secondary side of the transformer and a load and used for generating voltage based on the voltage of the secondary side of the transformer, and the voltage values of the output voltages are different from each other;
and the control end of the power switch is connected with the output end of the control device of the switching power supply.
CN202211253657.XA 2022-10-13 2022-10-13 Working mode control method and circuit of switching power supply and switching power supply Pending CN115498884A (en)

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