A method and circuit for controlling the operating mode of a switching power supply, and a switching power supply

Abstract

The application discloses a working mode control method and circuit of a switching power supply and the switching power supply, and relates to the field of switching power supply control. The switching power supply is controlled to enter different working modes according to the output voltage, load and input line voltage of the switching power supply. When the output voltage is less than a first preset voltage threshold and the load is heavy, the switching power supply is controlled to work in the CCM or DCM mode, so that the problem that the switching power supply has a low working frequency and is easy to be damaged due to the limitation of the QR mode when the switching power supply has a low output voltage demand is avoided. When the output voltage is not less than the first preset voltage threshold and the load is heavy, the switching power supply is controlled to work in one of the CCM, DCM or QR mode according to the input line voltage, so that the working efficiency of the switching power supply is ensured.

Description

Technical Field

[0001] This invention relates to the field of switching power supply control, and in particular to a method, circuit, and switching power supply for controlling the operating mode of a switching power supply with a wide output range. Background Technology

[0002] Switching power supplies are widely used due to their simple circuit structure and ability to efficiently provide multiple DC outputs. The operating modes of switching power supplies include CCM (Continuous Conduction Mode), DCM (Discontinuous Conduction Mode), and QR (Quasi-Resonant Mode). In existing technologies, when the load connected to the downstream end of the switching power supply is heavy and the input line voltage is high, the power supply is controlled to operate in QR mode. However, when the switching power supply has a wider output voltage requirement, such as a lower output voltage requirement, the characteristics of QR mode itself limit the operating frequency of the switching power supply. This leads to increased stress on the transformer in the switching power supply, making it prone to saturation of magnetic components and damage to the switching power supply. Summary of the Invention

[0003] The purpose of this invention is to provide a method, circuit, and power supply for controlling the operating mode of a switching power supply, which can comprehensively control the switching power supply to enter different operating modes based on the output voltage, load, and input line voltage of the switching power supply.

[0004] To solve the above technical problems, the present invention provides a method for controlling the operating mode of a switching power supply, comprising:

[0005] Determine whether the output voltage of the switching power supply is less than a first preset voltage threshold;

[0006] If so, when the load of the switching power supply meets the preset heavy load conditions, the switching power supply is controlled to enter the CCM or DCM working mode.

[0007] If not, when the load of the switching power supply meets the preset heavy load condition, the switching power supply is controlled to enter CCM, DCM, or QR working mode according to the input line voltage of the switching power supply.

[0008] Preferably, after determining whether the output voltage of the switching power supply is less than a first preset voltage threshold, the method further includes:

[0009] If so, when the load of the switching power supply meets the preset light load conditions, the switching power supply is controlled to enter the DCM working mode.

[0010] Preferably, after determining whether the output voltage of the switching power supply is less than a first preset voltage threshold, the method further includes:

[0011] If not, when the load of the switching power supply meets the preset light load conditions, the switching power supply is controlled to enter the DCM working mode.

[0012] Preferably, the switching power supply is controlled to enter CCM, DCM, or QR operating mode based on the input line voltage of the switching power supply, including:

[0013] When the input line voltage is greater than the second preset voltage threshold, the switching power supply is controlled to enter the QR operating mode;

[0014] When the input line voltage is not greater than the second preset voltage threshold, the switching power supply is controlled to enter the CCM or DCM operating mode.

[0015] Preferably, controlling the switching power supply to enter CCM, DCM, or QR operating mode based on the input line voltage of the switching power supply includes:

[0016] Within the full voltage range of the input line voltage, the switching power supply is controlled to enter the QR operating mode.

[0017] To address the aforementioned technical problems, this application also provides a switching power supply operating mode control circuit, comprising:

[0018] The mode control module is used 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 overload condition, and to generate a second clock signal based on the input line voltage of the switching power supply when the output voltage is not less than the first preset voltage threshold and the load meets the preset overload condition.

[0019] The power switch control module is used to control the state of the power switch in the switching power supply according to the first clock signal so as to control the switching power supply to enter the CCM or DCM working mode, and to control 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.

[0020] Preferably, the mode control module includes a clock output selector, a first clock module, and a second clock module;

[0021] The output terminals of the first clock module and the second clock module are respectively connected to the first clock input terminal and the second clock input terminal of the clock output selector, and the output terminal of the clock output selector serves as the output terminal of the mode control module.

[0022] The first clock module is used to generate the first clock signal, and the frequency of the first clock signal is positively correlated with the size of the load;

[0023] The second clock module is used to generate a second clock signal based on the primary resonant waveform when the number of valleys in the primary resonant waveform of the switching power supply is not greater than a preset valley number threshold, and to generate a second clock signal whose frequency is positively correlated with the load size when the number of valleys in the primary resonant waveform is greater than the preset valley number threshold.

[0024] The clock output selector is used to output a first clock signal generated by the first clock module when the output voltage is less than the first preset voltage threshold and the load meets the preset overload condition, and to output a second clock signal output by the second clock output selector when the output voltage is not less than the first preset voltage threshold and the load meets the preset overload condition.

[0025] Preferably, the second clock module includes a second clock submodule, a valley locking module, and a second clock output selector;

[0026] The output terminal of the second clock submodule and the output terminal of the valley locking module are respectively connected to the first input terminal and the second input terminal of the second clock output selector, and the output terminal of the second clock output selector is connected to the second clock input terminal of the clock output selector.

[0027] The second clock submodule is used to generate a second clock sub-signal when the number of valleys in the primary-side resonant waveform of the switching power supply is greater than a preset valley number threshold. The frequency of the second clock sub-signal is negatively correlated with the number of valleys in the primary-side resonant waveform, and the number of valleys in the primary-side resonant waveform is negatively correlated with the size of the load.

[0028] The valley locking module is used to control the primary side resonant waveform to open at the number of valleys when the number of valleys of the primary side resonant waveform is not greater than the preset valley number threshold, and to use the primary side resonant waveform opened at the number of valleys as the second clock valley signal.

[0029] The second clock output selector is used to output the second clock valley signal generated by the valley locking module as the second clock signal to the clock output selector when the number of valleys in the primary side resonant waveform is greater than the preset valley number threshold, and to output the second clock sub-signal generated by the second clock sub-module as the second clock signal to the clock output selector when the number of valleys in the primary side resonant waveform is not greater than the preset valley number threshold.

[0030] Preferably, the power switch control module includes an AND gate, a D flip-flop, and a drive circuit;

[0031] The first input terminal of the AND gate and the clock signal input terminal of the D flip-flop are both connected to the output terminal of the mode control module. The non-inverting output terminal of the D flip-flop is connected to the second input terminal of the AND gate. The output terminal of the AND gate is connected to the input terminal of the drive circuit. The output terminal of the drive circuit serves as the output terminal of the power switch control module and is connected to the control terminal of the power switch.

[0032] The driving circuit is used to amplify the signal output from the AND gate in order to control the state of the power switch.

[0033] Preferably, 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 the preset light load condition.

[0034] The power switch control module is also used 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 working mode.

[0035] 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 the preset light load condition;

[0036] The power switch control module is also used 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 working mode.

[0037] 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 overload condition; generate a fifth clock signal when the output voltage is not less than the first preset voltage threshold, the load meets the preset overload condition, and the input line voltage is greater than a second preset voltage threshold; and generate a sixth clock signal when the output voltage is not less than the first preset voltage threshold, the load meets the preset overload condition, and the input line voltage is not greater than the second preset voltage threshold.

[0038] The power switch control module is specifically used to control the state of the power switch in the switching power supply according to the first clock signal so as to control the switching power supply to enter the CCM or DCM working mode; to control the state of the power switch according to the fifth clock signal so as to control the switching power supply to enter the QR working mode; and to control the state of the power switch according to the sixth clock signal so as to control the switching power supply to enter the CCM or DCM working mode.

[0039] Preferably, the mode control module is specifically used 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 overload condition, and to generate a second clock signal when the output voltage is not less than the first preset voltage threshold, the load meets the preset overload condition, and the input line voltage is within the full voltage range.

[0040] The power switch control module is specifically used 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 working mode, and to 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 working mode.

[0041] To solve the above-mentioned technical problems, this application also provides a switching power supply, including the above-mentioned switching power supply operating mode control circuit, and further including:

[0042] The rectifier and filter module is used to convert the input alternating current into direct current and output the filtered direct current to the primary side of the transformer;

[0043] The transformer;

[0044] An output module located between the secondary side of the transformer and the load is used to generate a voltage based on the voltage of the secondary side of the transformer, and the voltage values ​​of each output voltage are different from each other.

[0045] A power switch whose control terminal is connected to the output terminal of the control device of the switching power supply.

[0046] In summary, this invention provides a method, circuit, and power supply for controlling the operating mode of a switching power supply. It comprehensively controls the switching power supply to enter different operating modes based on the output voltage, load, and input line voltage. When the output voltage is less than a first preset voltage threshold and the load is heavy, the power supply is controlled to operate in CCM or DCM mode, avoiding the problem of low operating frequency and easy damage caused by the limitations of QR mode when the power supply requires low output voltage. When the output voltage is not less than the first preset voltage threshold and the load is heavy, the power supply is controlled to operate in CCM, DCM, or QR mode based on the input line voltage, ensuring the operating efficiency of the power supply. Simultaneously, it is applicable to switching power supply application systems with a relatively wide output voltage / current range. Attached Figure Description

[0047] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the prior art and embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0048] Figure 1 A flowchart illustrating a method for controlling the operating mode of a switching power supply provided by the present invention;

[0049] Figure 2 A schematic diagram of the first control method of a switching power supply operating mode control method provided by the present invention;

[0050] Figure 3 A schematic diagram of a second control method for a switching power supply operating mode control method provided by the present invention;

[0051] Figure 4 A schematic diagram of a third control mode of a switching power supply operating mode control method provided by the present invention;

[0052] Figure 5 A schematic diagram of the working mode control circuit of a switching power supply provided by the present invention;

[0053] Figure 6 A schematic diagram of the mode control module in the working mode control circuit of a switching power supply provided by the present invention;

[0054] Figure 7 A circuit diagram of a switching power supply provided by the present invention. Detailed Implementation

[0055] The core of this invention is to provide a method, circuit, and switching power supply for controlling the operating mode of a switching power supply, which can comprehensively control the switching power supply to enter different operating modes based on the output voltage, load, and input line voltage of the switching power supply.

[0056] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0057] Please refer to Figure 1 , Figure 1A flowchart illustrating a method for controlling the operating mode of a switching power supply provided by the present invention, the method comprising:

[0058] S1: Determine whether the output voltage of the switching power supply is less than the first preset voltage threshold; if yes, proceed to S2; if no, proceed to S3.

[0059] S2: When the load of the switching power supply meets the preset heavy load conditions, control the switching power supply to enter the CCM or DCM working mode.

[0060] S3: When the load of the switching power supply meets the preset heavy load conditions, the switching power supply is controlled to enter CCM, DCM, or QR working mode according to the input line voltage of the switching power supply.

[0061] Switching power supplies can provide multiple output voltages with different values ​​and are widely used as chargers. Currently, there are three common operating modes for switching power supplies: Discontinuous Mode (DCM), Continuous Mode (CCM), and Quasi-Resonant Mode (QR). Each mode has its own characteristics. DCM has the advantages of low switching losses and good stability, but also the disadvantages of relatively low operating frequency and efficiency. CCM has the advantage of relatively high operating frequency, but is prone to stability issues. QR mode has a higher operating frequency and efficiency than DCM, but because the power transistor turns on near the resonance trough, the spectrum is more concentrated, resulting in relatively poor EMI.

[0062] When controlling a switching power supply, the above-mentioned operating modes are usually combined to meet the needs of different situations. However, existing technologies generally only use the input line voltage (high or low line voltage) and the load (light, heavy, or full load) as conditions for selecting different operating modes. This makes it impossible to select the most suitable operating mode for switching power supplies with a wide output voltage range, i.e., different output voltage requirements, in practical applications. For example, in existing technologies, when the load is heavy and the input voltage is high line voltage, the switching power supply is controlled to operate in QR mode, and when the input voltage is low line voltage, it is controlled to operate in CCM. However, under the condition of heavy load and high line voltage, if the switching power supply has a low output voltage and high current output requirement (e.g., with multiple outputs), the operating characteristics of QR mode itself will cause the system frequency to drop significantly under full load, resulting in increased stress on the transformer in the switching power supply, which can easily lead to magnetic component saturation and power supply damage.

[0063] Therefore, in this application, the output voltage, load, and input line voltage of the switching power supply are simultaneously used as the selection criteria for controlling the switching power supply to enter different operating modes. Specifically, the switching power supply is first divided into two cases: low output voltage and high output voltage, based on the output voltage. This division is made by determining whether the output voltage of the switching power supply is less than a first preset voltage threshold. When the output voltage is less than the first preset voltage threshold, i.e., in the case of low output voltage, if the load is heavy, the switching power supply is controlled to operate in CCM or DCM mode. This can increase the frequency of the switching power supply and reduce its size. At the same time, it can avoid the problems caused by controlling the switching power supply to operate in QR mode in this case in the prior art, such as a significant reduction in system frequency, increased transformer stress, easy magnetic component saturation, and power supply damage.

[0064] It should be noted that the specific value of the first preset voltage threshold can also be set according to the actual situation, and it can usually be set to 7.5V. This application does not impose any special limitations on the preset heavy load conditions, and the full load situation can be included in the preset heavy load conditions.

[0065] The specific operating mode of the switching power supply under the conditions of high output voltage and heavy load is not particularly limited in this application. Depending on the input line voltage, the switching power supply can be selected to always operate in QR mode, or operate in QR mode when the input line voltage is high, and operate in CCM or DCM mode when the input line voltage is low.

[0066] In summary, this invention provides a control method for a switching power supply, which comprehensively controls the switching power supply to enter different operating modes based on the output voltage, load, and input line voltage. When the output voltage is less than a first preset voltage threshold and the load is heavy, the switching power supply is controlled to operate in CCM or DCM mode, avoiding the problem of low operating frequency and easy damage caused by the limitation of QR mode when the switching power supply has a low output voltage requirement. When the output voltage is not less than the first preset voltage threshold and the load is heavy, the switching power supply is controlled to operate in one of CCM, DCM, or QR modes based on the input line voltage, ensuring the working efficiency of the switching power supply.

[0067] Based on the above embodiments:

[0068] In a preferred embodiment, after determining whether the output voltage of the switching power supply is less than a first preset voltage threshold, the method further includes:

[0069] If so, when the load of the switching power supply meets the preset light load conditions, the switching power supply will be controlled to enter the DCM working mode.

[0070] To further ensure that the switching power supply can select the most suitable operating mode under various conditions, this embodiment further provides the operating mode of the switching power supply under light load. Please refer to... Figure 2 , Figure 2 This is a schematic diagram of the first control method of the operating mode control method for a switching power supply provided by the present invention. Figure 2 The horizontal axis represents the load, the vertical axis represents the input line voltage, Vo represents the output voltage, and Vref represents the first preset voltage threshold. Specifically, it is still necessary to first determine whether the switching power supply is operating at a low or high output voltage based on its output voltage. In this embodiment, when the output voltage is less than the first preset voltage threshold, i.e., a low output voltage, if the load is unloaded, the switching power supply is controlled to operate in DCM mode, which can reduce the transformer size while maintaining system efficiency.

[0071] This application does not impose any special limitation on the preset light load conditions required to determine that the load is light load, and no load may be included in the scope of preset light load conditions.

[0072] In summary, in this embodiment, if the priority in practical applications is to reduce the size of the switching power supply while also taking into account its efficiency, the switching power supply will be controlled to enter the DCM operating mode when the load is unloaded and the output voltage is low.

[0073] In a preferred embodiment, after determining whether the output voltage of the switching power supply is less than a first preset voltage threshold, the method further includes:

[0074] If not, when the load of the switching power supply meets the preset light load conditions, the switching power supply will be controlled to enter the DCM working mode.

[0075] To further ensure that the switching power supply can select the most suitable operating mode under various conditions, this embodiment further provides an operating mode for the switching power supply under light load. Specifically, it is still necessary to first determine whether the switching power supply is operating at a low or high output voltage based on its output voltage. In this embodiment, when the output voltage is not less than a first preset voltage threshold, i.e., a high output voltage, if the load is no-load, the switching power supply is controlled to operate in DCM mode, which can ensure system stability and reduce switching losses.

[0076] Please refer to Figure 3 , Figure 3 This is a schematic diagram of a second control method for a switching power supply operating mode control method provided by the present invention. Figure 3 The horizontal axis represents the load, the vertical axis represents the input line voltage, Vo represents the output voltage, and Vref represents the first preset voltage threshold.

[0077] As a preferred embodiment, the switching power supply is controlled to enter CCM, DCM, or QR operating mode based on the input line voltage of the switching power supply, including:

[0078] When the input line voltage is greater than the second preset voltage threshold, the control switch power supply enters the QR working mode;

[0079] When the input line voltage is not greater than the second preset voltage threshold, the control switching power supply enters the CCM or DCM working mode.

[0080] To further ensure that the switching power supply can select the most suitable operating mode under various conditions, in this embodiment, when the load at the downstream end of the switching power supply is heavy or full load, different operating modes are selected based on the different input line voltages. Specifically, when the load is heavy and the input line voltage is greater than the second preset voltage threshold (i.e., high line voltage), the switching power supply is controlled to enter the QR operating mode, thereby improving system efficiency; when the load is heavy and the input line voltage is not greater than the second preset voltage threshold (i.e., low line voltage), the switching power supply is controlled to enter the CCM or DCM operating mode, further improving system efficiency and ensuring a relatively small size of the switching power supply.

[0081] Please refer to Figure 3 , Figure 3 This is a schematic diagram of a second control method for a switching power supply operating mode control method provided by the present invention. Figure 3 The horizontal axis represents the load, the vertical axis represents the input line voltage, Vo represents the output voltage, Vref represents the first preset voltage threshold, and VL1 represents the second preset voltage threshold.

[0082] This application does not impose any specific value on the second preset voltage threshold. For example, when the output voltage of the switching power supply is in the range of 3.3V-20V or 5V-20V, the first preset voltage threshold can be 7.5V and the second preset voltage threshold can be 180V.

[0083] As a preferred embodiment, the switching power supply is controlled to enter CCM, DCM, or QR operating mode based on the input line voltage of the switching power supply, including:

[0084] Within the full voltage range of the input line voltage, the control switching power supply enters the QR operating mode.

[0085] Please refer to Figure 4 , Figure 4 This is a schematic diagram of a third control mode of the switching power supply operating mode control method provided by the present invention. Figure 4 The horizontal axis represents the load, the vertical axis represents the input line voltage, Vo represents the output voltage, and Vref represents the first preset voltage threshold.

[0086] To further ensure that the switching power supply can select the most suitable operating mode under various conditions, in this embodiment, when the load downstream of the switching power supply is heavy, the switching power supply is always controlled to operate in QR mode regardless of whether the input line voltage is low or high. That is, the switching power supply is controlled to operate in QR mode across the entire input line voltage range, which maximizes the efficiency and improves the performance of the switching power supply. Therefore, given the priority of improving system efficiency, the control strategy in this embodiment can be selected when the switching power supply is under heavy load and the output voltage is high.

[0087] Please refer to Figure 5 , Figure 5 This invention provides a schematic diagram of a switching power supply operating mode control circuit, which includes:

[0088] The mode control module 1 is used 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 overload condition, and to generate a second clock signal based on the input line voltage of the switching power supply when the output voltage is not less than the first preset voltage threshold and the load meets the preset overload condition.

[0089] The power switch control module 2 is used to control the state of the power switch in the switching power supply according to the first clock signal so as to control the switching power supply to enter the CCM or DCM working mode, and to control 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.

[0090] In this application, the output voltage, load, and input line voltage of the switching power supply are simultaneously used as the selection criteria for controlling the switching power supply to enter different operating modes. Specifically, the switching power supply is first divided into two cases: low output voltage and high output voltage, based on the output voltage. This division is determined by whether the output voltage of the switching power supply is less than a first preset voltage threshold. When the output voltage is less than the first preset voltage threshold, i.e., in the case of low output voltage, if the load is heavy, the mode control module 1 generates a first clock signal. After receiving the first clock signal, the power switching module controls the switching power supply to operate in CCM or DCM mode based on the first clock signal. This can increase the frequency of the switching power supply and reduce its size. At the same time, it can avoid the problems caused by controlling the switching power supply to operate in QR mode in this case in the prior art, such as a significant reduction in system frequency, increased transformer stress, easy magnetic component saturation, and power supply damage.

[0091] It should be noted that the specific value of the first preset voltage threshold can be set according to the actual situation, and it can usually be set to 7.5V. This application does not impose any special restrictions on the preset heavy load conditions, which can be set according to the actual situation.

[0092] This application does not specifically limit the specific operating mode of the switching power supply under the conditions of high output voltage and heavy load. Depending on the input line voltage, the switching power supply can be selected to always operate in QR mode, or operate in QR mode when the input line voltage is high, and in CCM or DCM mode when the input line voltage is low. Specifically, a second clock signal is generated when the output voltage is not less than a first preset voltage threshold, i.e., when the output voltage is high and the load is heavy. This 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 CCM, DCM, or QR operating mode based on the second clock signal.

[0093] In summary, this invention discloses a switching power supply operating mode control circuit, including a mode control module 1 and a power switch control module 2. The mode control module 1 generates clock signals to control the switching power supply to enter different operating modes based on the output voltage, load, and input line voltage of the switching power supply. The power switch control module 2 controls the switching power supply to enter CCM or DCM mode when the output voltage is less than a first preset voltage threshold and the load is heavy, thus avoiding the problem of low operating frequency and easy damage to the switching power supply due to the limitations of QR mode when the switching power supply has a low output voltage requirement. When the output voltage is not less than the first preset voltage threshold and the load is heavy, it enters CCM, DCM, or QR mode to ensure the operating efficiency of the switching power supply.

[0094] Based on the above embodiments:

[0095] In 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;

[0096] The output terminal of the first clock module 012 and the output terminal of the second clock module 013 are respectively connected to the first clock input terminal and the second clock input terminal of the clock output selector 011. The output terminal of the clock output selector 011 serves as the output terminal of the mode control module 1.

[0097] The first clock module 012 is used to generate a first clock signal, and the frequency of the first clock signal is positively correlated with the size of the load;

[0098] The second clock module 013 is used to generate a second clock signal based on the primary side resonant waveform when the number of valleys in the primary side resonant waveform of the switching power supply is not greater than a preset valley number threshold, and to generate a second clock signal whose frequency is positively correlated with the load when the number of valleys in the primary side resonant waveform is greater than the preset valley number threshold.

[0099] The clock output selector 011 is used 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 overload conditions, and to 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 overload conditions.

[0100] In this embodiment, the first clock module itself can generate a first clock signal, and the frequency of the first clock signal is positively correlated with the load size. Therefore, when the load is heavy, the frequency of the first clock signal is relatively high. At this time, when the power switch control module 2 uses the first clock signal to control the state of the power switch, it will cause the switching power supply to enter the CCM operating mode. When the load decreases, the frequency of the first clock signal also decreases. At this time, when the power switch control module 2 uses the first clock signal to control the state of the power switch, it will cause the switching power supply to enter the DCM operating mode.

[0101] In QR mode, the power supply is turned on at the first preset valley threshold of the primary resonant waveform. In DCM mode, the power supply is turned on at any time of the primary resonant waveform. Therefore, the second clock module generates a second clock signal based on the primary resonant waveform to enable the power supply to enter QR mode when the number of valleys in the primary resonant waveform is not greater than the preset valley threshold. When the number of valleys in the primary resonant waveform is greater than the preset valley threshold, a second clock signal with a frequency positively correlated with the load is generated to enable the power supply to enter DCM mode.

[0102] In a preferred embodiment, the second clock module 013 includes a second clock submodule 131, a valley locking module 132, and a second clock output selector 133;

[0103] The output of the second clock submodule 131 and the output of the valley locking module 132 are respectively connected to the first input and the second input of the second clock output selector 133, and the output of the second clock output selector 133 is connected to the second clock input of the clock output selector 011.

[0104] The second clock submodule 131 is used to generate a second clock sub-signal when the number of valleys in the primary side resonant waveform of the switching power supply is greater than a preset valley number threshold. The frequency of the second clock sub-signal is negatively correlated with the number of valleys in the primary side resonant waveform, and the number of valleys in the primary side resonant waveform is negatively correlated with the size of the load.

[0105] Valley locking module 132 is used to control the primary side resonant waveform to open at the number of valleys when the number of valleys of the primary side resonant waveform is not greater than a preset valley number threshold, and to use the primary side resonant waveform that opens at the number of valleys as the second clock valley signal.

[0106] The second clock output selector 133 is used to output the second clock valley signal generated by the valley locking module 132 as the second clock signal to the clock output selector 011 when the number of valleys in the primary side resonant waveform is greater than the preset valley number threshold, and to output the second clock sub-signal generated by the second clock sub-module 131 as the second clock signal to the clock output selector 011 when the number of valleys in the primary side resonant waveform is not greater than the preset valley number threshold.

[0107] Please refer to Figure 6 , Figure 6 This is a schematic diagram of the mode control module in a switching power supply operating mode control circuit provided by the present invention. Figure 6 Clock selection 1 is a clock output selector 011. Frequency control 1 and clock 1 together constitute the first clock module 012. Frequency control 2 and clock 2 together constitute the second clock module 013. Clock selection 2 is a second clock output selector 133. n is the number of valleys in the primary-side resonant waveform, N is the preset valley number threshold, COMP is a parameter positively correlated with the load, Valley is the primary-side resonant wave, Line is the input line voltage, Vout is the output voltage, CLK1 is the first clock signal, CLK2 is the second clock signal, and CLK is the final clock signal used to control the power switch. Furthermore, Figure 6 The Slope signal in the circuit is used to achieve slope compensation of the switching power supply in CCM mode, thereby suppressing harmonic oscillations.

[0108] This embodiment provides a specific structure of the mode control module 1 for generating the first clock signal and the second clock signal. 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 sub-module 131, the valley locking module 132 and the second clock output selector 133 based on the output voltage of the switching power supply.

[0109] Specifically, the first clock module itself can generate a first clock signal, and the frequency of the first clock signal is positively correlated with the load. Therefore, when the load is heavy, the frequency of the first clock signal is relatively high. At this time, when the power switch control module 2 uses the first clock signal to control the state of the power switch, it will cause the switching power supply to enter the CCM operating mode. When the load decreases, the frequency of the first clock signal also decreases. At this time, when the power switch control module 2 uses the first clock signal to control the state of the power switch, it will cause the switching power supply to enter the DCM operating mode.

[0110] Since the number of valleys in the primary-side resonant waveform is negatively correlated with the load size, when the load is heavy, the number of valleys in the primary-side resonant waveform is less than the preset valley number threshold. Therefore, the valley locking module 132 opens at the valleys and generates a new clock signal, namely the second clock valley signal, which is used as the second clock signal. When the power switch control module 2 uses this signal to control the state of the power switch, the switching power supply enters the QR operating mode. As the load gradually decreases, the number of valleys in the primary-side resonant waveform gradually increases until it is not less than the preset valley number threshold. Therefore, the second clock sub-module 131 generates a second clock sub-signal, and the frequency of the second clock sub-signal is positively correlated with the load size. Therefore, when the power switch control module 2 uses the second clock sub-signal to control the state of the power switch, the switching power supply enters the DCM operating mode.

[0111] In summary, the mode control module 1 provided in this embodiment can generate clock signals that enable the switching power supply to enter various working modes. Then, the clock output selector 011 in the mode control module 1 can select different clock signals under different conditions, thereby achieving the purpose of controlling the switching power supply to enter different working modes under different conditions. Moreover, the circuit structure is simple and easy to implement.

[0112] In a preferred embodiment, the power switch control module 2 includes an AND gate, a D flip-flop, and a drive circuit;

[0113] The first input terminal of the AND gate and the clock signal input terminal of the D flip-flop are both connected to the output terminal of the mode control module 1. The non-inverting output terminal of the D flip-flop is connected to the second input terminal of the AND gate. The output terminal of the AND gate is connected to the input terminal of the drive circuit. The output terminal of the drive circuit is connected to the control terminal of the power switch as the output terminal of the power switch control module 2.

[0114] The driver circuit is used to amplify the signal output from the AND gate in order to control the state of the power switch.

[0115] Please refer to Figure 5 , Figure 5 This is a schematic diagram of the operating mode control circuit of a switching power supply provided by the present invention. Figure 5 COMP is a signal reflecting the load size, Valley is the primary resonant wave, Line is the input line voltage, Vout is the output voltage, CLK is the clock signal used to control the power switch, Gate is the signal received by the control terminal of the power switch, and the Slope signal is used to realize slope compensation of the switching power supply in CCM mode to suppress harmonic oscillations.

[0116] The clock signal output by the mode control module 1 is connected to the clock signal input terminal of the D flip-flop in the power switch control module 2 and the first input terminal of the AND gate. The AND gate performs an AND operation between the clock signal output by the mode control module 11 and the signal output by the D flip-flop and transmits it to the drive circuit. The drive circuit amplifies the signal output by the AND gate to a signal that can be used to control the power switch and then inputs it to the control terminal of the power switch to control the state of the power switch, thereby realizing the control of the working mode of the switching power supply.

[0117] 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.

[0118] In 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.

[0119] The power switch control module 2 is also used to control the state of the power switch based on a third clock signal in order to control the switching power supply to enter the DCM operating mode.

[0120] For a detailed description of this embodiment, please refer to the embodiment corresponding to the working mode control method of the switching power supply; this application will not repeat the details here.

[0121] In 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 a first preset voltage threshold and the load meets the preset light load conditions.

[0122] The power switch control module 2 is also used to control the state of the power switch based on the fourth clock signal in order to control the switching power supply to enter the DCM operating mode.

[0123] For a detailed description of this embodiment, please refer to the embodiment corresponding to the working mode control method of the switching power supply; this application will not repeat the details here.

[0124] In a preferred embodiment, the mode control module 1 is specifically used 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 overload condition; generate a fifth clock signal when the output voltage is not less than the first preset voltage threshold, the load meets the preset overload condition, and the input line voltage is greater than a second preset voltage threshold; and generate a sixth clock signal when the output voltage is not less than the first preset voltage threshold, the load meets the preset overload condition, and the input line voltage is not greater than the second preset voltage threshold.

[0125] The power switch control module 2 is specifically used to control the state of the power switch in the switching power supply according to the first clock signal so as to control the switching power supply to enter the CCM or DCM working mode; to control the state of the power switch according to the fifth clock signal so as to control the switching power supply to enter the QR working mode; and to control the state of the power switch according to the sixth clock signal so as to control the switching power supply to enter the CCM or DCM working mode.

[0126] For a detailed description of this embodiment, please refer to the embodiment corresponding to the working mode control method of the switching power supply; this application will not repeat the details here.

[0127] In a preferred embodiment, the mode control module 1 is specifically used 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 overload condition, and to generate a second clock signal when the output voltage is not less than the first preset voltage threshold, the load meets the preset overload condition, and the input line voltage is within the full voltage range.

[0128] The power switch control module 2 is specifically used 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 working mode, and to 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 working mode.

[0129] For a detailed description of this embodiment, please refer to the embodiment corresponding to the working mode control method of the switching power supply; this application will not repeat the details here.

[0130] To solve the above-mentioned technical problems, this application also provides a switching power supply, including the above-mentioned switching power supply operating mode control circuit, and further including:

[0131] The rectifier and filter module is used to convert the input AC power into DC power and output the filtered DC power to the primary side of the transformer.

[0132] transformer;

[0133] The output module, located between the secondary side of the transformer and the load, is used to generate voltage based on the voltage of the secondary side of the transformer, and the voltage values ​​of each output voltage are different from each other.

[0134] The power switch is connected to the output terminal of the control device of the switching power supply.

[0135] The switching power supply in this application can be a switching power supply with a wide voltage output range, which can select the most suitable operating mode when facing different output voltage requirements. Please refer to... Figure 7 , Figure 7 A circuit diagram of a switching power supply provided by the present invention. Figure 7The switching power supply in this application is a flyback switching power supply. The switching power supply's control device controls the conduction of the power switch, enabling the switching power supply to operate in different working modes and ensuring its performance. For a detailed description of the switching power supply provided in this application, please refer to the embodiments of the switching power supply control method described above. This application will not elaborate further here.

[0136] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0137] It should also be noted that, in this specification, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0138] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not 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

1. A method for controlling the operating mode of a switching power supply, characterized in that, include: Determine whether the output voltage of the switching power supply is less than a first preset voltage threshold; If so, when the load of the switching power supply meets the preset heavy load conditions, the switching power supply is controlled to enter the CCM or DCM working mode. If not, when the load of the switching power supply meets the preset heavy load condition, the switching power supply is controlled to enter CCM or DCM or QR working mode according to the input line voltage of the switching power supply. After determining whether the output voltage of the switching power supply is less than a first preset voltage threshold, the method further includes: If so, when the load of the switching power supply meets the preset light load conditions, the switching power supply is controlled to enter the DCM working mode. After determining whether the output voltage of the switching power supply is less than a first preset voltage threshold, the method further includes: If not, when the load of the switching power supply meets the preset light load conditions, the switching power supply is controlled to enter the DCM working mode.

2. The operating mode control method for a switching power supply as described in claim 1, characterized in that, The switching power supply is controlled to enter CCM, DCM, or QR operating modes based on the input line voltage of the switching power supply, including: When the input line voltage is greater than the second preset voltage threshold, the switching power supply is controlled to enter the QR operating mode; When the input line voltage is not greater than the second preset voltage threshold, the switching power supply is controlled to enter the CCM or DCM operating mode.

3. The operating mode control method for a switching power supply as described in claim 1, characterized in that, The switching power supply is controlled to enter CCM, DCM, or QR operating modes based on the input line voltage of the switching power supply, including: Within the full voltage range of the input line voltage, the switching power supply is controlled to enter the QR operating mode.

4. A switching power supply operating mode control circuit, characterized in that, include: The mode control module is used 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 overload condition, and to generate a second clock signal based on the input line voltage of the switching power supply when the output voltage is not less than the first preset voltage threshold and the load meets the preset overload condition. A power switch control module is used to control the state of the power switch in the switching power supply according to the first clock signal so as to control the switching power supply to enter the CCM or DCM working mode, and to control 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. The mode control module is also used 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 the preset light load condition, and 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 the preset light load condition. The power switch control module is also used to control the state of the power switch based on the third clock signal in order to control the switching power supply to enter the DCM working mode, and to control the state of the power switch based on the fourth clock signal in order to control the switching power supply to enter the DCM working mode.

5. The operating mode control circuit of the switching power supply as described in claim 4, characterized in that, The mode control module includes a clock output selector, a first clock module, and a second clock module; The output terminals of the first clock module and the second clock module are respectively connected to the first clock input terminal and the second clock input terminal of the clock output selector, and the output terminal of the clock output selector serves as the output terminal of the mode control module. The first clock module is used to generate 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 to generate a second clock signal based on the primary resonant waveform when the number of valleys in the primary resonant waveform of the switching power supply is not greater than a preset valley number threshold, and to generate a second clock signal whose frequency is positively correlated with the load size when the number of valleys in the primary resonant waveform is greater than the preset valley number threshold. The clock output selector is used to output a first clock signal generated by the first clock module when the output voltage is less than the first preset voltage threshold and the load meets the preset overload condition, and to output a second clock signal output by the second clock output selector when the output voltage is not less than the first preset voltage threshold and the load meets the preset overload condition.

6. The operating mode control circuit of the switching power supply as described in claim 5, characterized in that, The second clock module includes a second clock submodule, a valley-locking module, and a second clock output selector; The output terminal of the second clock submodule and the output terminal of the valley locking module are respectively connected to the first input terminal and the second input terminal of the second clock output selector, and the output terminal of the second clock output selector is connected to the second clock input terminal of the clock output selector. The second clock submodule is used to generate a second clock sub-signal when the number of valleys in the primary-side resonant waveform of the switching power supply is greater than a preset valley number threshold. The frequency of the second clock sub-signal is negatively correlated with the number of valleys in the primary-side resonant waveform, and the number of valleys in the primary-side resonant waveform is negatively correlated with the size of the load. The valley locking module is used to control the primary side resonant waveform to open at the number of valleys when the number of valleys of the primary side resonant waveform is not greater than the preset valley number threshold, and to use the primary side resonant waveform opened at the number of valleys as the second clock valley signal. The second clock output selector is used to output the second clock valley signal generated by the valley locking module as the second clock signal to the clock output selector when the number of valleys in the primary side resonant waveform is greater than the preset valley number threshold, and to output the second clock sub-signal generated by the second clock sub-module as the second clock signal to the clock output selector when the number of valleys in the primary side resonant waveform is not greater than the preset valley number threshold.

7. The operating mode control circuit of the switching power supply as described in claim 4, characterized in that, The power switch control module includes an AND gate, a D flip-flop, and a drive circuit. The first input terminal of the AND gate and the clock signal input terminal of the D flip-flop are both connected to the output terminal of the mode control module. The non-inverting output terminal of the D flip-flop is connected to the second input terminal of the AND gate. The output terminal of the AND gate is connected to the input terminal of the drive circuit. The output terminal of the drive circuit serves as the output terminal of the power switch control module and is connected to the control terminal of the power switch. The driving circuit is used to amplify the signal output from the AND gate in order to control the state of the power switch.

8. The operating mode control circuit of the switching power supply as described in any one of claims 4 to 7, characterized in that, The mode control module is specifically used 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 overload condition; generate a fifth clock signal when the output voltage is not less than the first preset voltage threshold, the load meets the preset overload condition, and the input line voltage is greater than a second preset voltage threshold; and generate a sixth clock signal when the output voltage is not less than the first preset voltage threshold, the load meets the preset overload condition, and the input line voltage is not greater than the second preset voltage threshold. The power switch control module is specifically used to control the state of the power switch in the switching power supply according to the first clock signal so as to control the switching power supply to enter the CCM or DCM working mode; to control the state of the power switch according to the fifth clock signal so as to control the switching power supply to enter the QR working mode; and to control the state of the power switch according to the sixth clock signal so as to control the switching power supply to enter the CCM or DCM working mode.

9. The operating mode control circuit of the switching power supply as described in any one of claims 4 to 7, characterized in that, The mode control module is specifically used 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 overload condition, and to generate a second clock signal when the output voltage is not less than the first preset voltage threshold, the load meets the preset overload condition, and the input line voltage is within the full voltage range. The power switch control module is specifically used 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 working mode, and to 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 working mode.

10. A switching power supply, characterized in that, The power supply operating mode control circuit as described in any one of claims 4 to 9 further includes: The rectifier and filter module is used to convert the input alternating current into direct current and output the filtered direct current to the primary side of the transformer; The transformer; An output module located between the secondary side of the transformer and the load is used to generate a voltage based on the voltage of the secondary side of the transformer, and the voltage values ​​of each output voltage are different from each other. A power switch whose control terminal is connected to the output terminal of the control device of the switching power supply.

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