Switching power supply operation mode control method, circuit, and switching power supply

Abstract

To provide an operation mode control method for a switching power supply, a circuit, and a switching power supply that perform overall control of a switching power supply to enter a different operation mode, on the basis of an output voltage, a load, and an input line voltage.SOLUTION: In a method, in a case where an output voltage is lower than a first predetermined voltage threshold and a load is heavy, a switching power supply is controlled to operate in a CCM (a continuous conduction mode) or a DCM (a discontinuous conduction mode), and thereby, when the switching power supply has a low-output voltage demand, such a problem that an operation frequency of the switching power supply becomes low due to restriction of a QR (a pseudo resonance mode), which causes the switching power supply to be likely to be damaged, can be avoided. In a case where the output voltage is not lower than the first predetermined voltage threshold and the load is heavy, such control that the switching power supply is operated in any one mode of the CCM, the DCM, and the QR is performed on the basis of an input line voltage to ensure operation efficiency of the switching power supply.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This application claims priority from a Chinese patent application with application number 202211253657.X, entitled "Method, circuit and switching power supply for controlling the operation mode of a switching power supply," filed with the China Patent Office on October 13, 2022, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to the field of switching power supply control, and more particularly to an operation mode control method, circuit, and switching power supply for a wide output range switching power supply. [Background technology]

[0003] Switching power supplies are widely used due to their simple circuit structure and ability to provide multiple DC outputs with high efficiency. Switching power supply operating modes include continuous conduction mode (CCM), discontinuous conduction mode (DCM), and quasi-resonant mode (QR). Conventional technology operates in QR mode when the load connected to the output of the switching power supply is heavy and the input line voltage is high. However, when a wide output voltage range is required, such as a low output voltage, the operating frequency of the switching power supply is limited due to the characteristics of QR mode itself, which increases the stress on the transformer inside the switching power supply, leading to problems such as saturation of the magnetic components and damage to the switching power supply. Summary of the Invention

[0004] The objective of the present invention is to provide a method, circuit and switching power supply for controlling the operation mode of a switching power supply, which can comprehensively control the switching power supply to enter different operation modes according to the output voltage of the switching power supply, the load and the input line voltage of the switching power supply.

[0005] To solve the above technical problems, the present invention provides an operation mode control method for a switching power supply, which includes:

[0006] determining whether the output voltage of the switching power supply is less than a first predetermined voltage threshold; If it is smaller, when the load of the switching power supply meets a predetermined heavy load condition, control the switching power supply to enter a CCM or DCM operation mode; If not, when the load of the switching power supply meets the predetermined heavy load condition, control the switching power supply to enter CCM, DCM, or QR operation mode based on the input line voltage of the switching power supply.

[0007] Preferably, after determining whether the output voltage of the switching power supply is less than a first predetermined voltage threshold, the method further comprises: If it is smaller, when the load of the switching power supply meets a predetermined light load condition, the method includes controlling the switching power supply to enter a DCM operation mode.

[0008] Preferably, after determining whether the output voltage of the switching power supply is less than a first predetermined voltage threshold, the method further comprises: If not, when the load of the switching power supply meets a predetermined light load condition, the method includes controlling the switching power supply to enter a DCM operation mode.

[0009] Preferably, controlling the switching power supply to enter a CCM, DCM, or QR operation mode based on the input line voltage of the switching power supply includes: When the input line voltage is greater than a second predetermined voltage threshold, controlling the switching power supply to enter the QR operating mode; If the input line voltage does not exceed the second predetermined voltage threshold, controlling the switching power supply to enter the CCM or DCM operating mode.

[0010] Preferably, controlling the switching power supply to enter a CCM, DCM, or QR operating mode based on the input line voltage of the switching power supply includes: and controlling the switching power supply to enter the QR operating mode within the entire voltage range of the input line voltage.

[0011] In order to solve the above technical problems, the present application further provides an operation mode control circuit for a switching power supply, a mode control module used to generate a first clock signal when the output voltage of a switching power supply is lower than a first predetermined voltage threshold and the load of the switching power supply meets a predetermined heavy load 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 lower than the first predetermined voltage threshold and the load meets the predetermined heavy load condition; The state of the power switch of the switching power supply is controlled based on the first clock signal, so that the switching power supply enters a CCM or DCM operation mode. and a power switch control module used to control the state of the power switch based on the second clock signal, thereby controlling the switching power supply to enter a CCM, DCM, or QR operation mode.

[0012] Preferably, the mode control module includes a clock output selector, a first clock module, and a second clock module; an output terminal of the first clock module and an output terminal of the second clock module are respectively connected to a first clock input terminal and a second clock input terminal of the clock output selector, and an output terminal of the clock output selector is an 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 magnitude of the load; the second clock module is used to generate a second clock signal based on the primary resonant waveform of the switching power supply when the valley number of the primary resonant waveform is below a predetermined valley number threshold, and to generate a second clock signal whose frequency and the magnitude of the load are positively correlated when the valley number of the primary resonant waveform is greater than the predetermined valley number threshold; The clock output selector is used to output the first clock signal generated by the first clock module when the output voltage is smaller than a first predetermined voltage threshold and the load meets the predetermined heavy load condition, and to output the second clock signal output by the second clock output selector when the output voltage is not smaller than the first predetermined voltage threshold and the load meets the predetermined heavy load condition.

[0013] Preferably, the second clock module includes a second clock sub-module, a valley lock module, and a second clock output selector; an output terminal of the second clock sub-module and an output terminal of the valley lock module are respectively connected to a first input terminal and a second input terminal of the second clock output selector, and an output terminal of the second clock output selector is connected to a second clock input terminal of the clock output selector; the second clock sub-module is used to generate a second clock sub-signal when the valley number of the primary resonant waveform of the switching power supply is greater than a predetermined valley number threshold, the frequency of the second clock sub-signal and the valley number of the primary resonant waveform exhibit a negative correlation, and the valley number of the primary resonant waveform and the magnitude of the load exhibit a negative correlation; The valley lock module is used to control the primary resonant waveform to develop in valley portions of the number of valleys when the number of valleys of the primary resonant waveform does not exceed the predetermined valley number threshold, and the primary resonant waveform developed in valley portions of the number of valleys is used as a second clock valley signal; The second clock output selector is used to output the second clock valley signal generated by the valley lock module to the clock output selector as the second clock signal when the valley number of the primary resonant waveform is greater than the predetermined valley number threshold, and to output the second clock sub-signal generated by the second clock sub-module to the clock output selector as the second clock signal when the valley number of the primary resonant waveform does not exceed the predetermined valley number threshold.

[0014] Preferably, the power switch control module includes an AND gate, a D flip-flop, and a driver circuit; a first input terminal of the AND gate and a clock signal input terminal of the D flip-flop are both connected to the output terminal of the mode control module, a positive phase output terminal of the D flip-flop is connected to the second input terminal of the AND gate, an output terminal of the AND gate is connected to the input terminal of the driving circuit, and an output terminal of the driving circuit is connected to the control terminal of the power switch as the output terminal of the power switch control module; The drive circuit is used to control the state of the power switch by amplifying the signal output from the output terminal of the AND gate.

[0015] Preferably, the mode control module is further adapted to generate a third clock signal when the output voltage of the switching power supply is less than the first predetermined voltage threshold and the load meets a predetermined light load condition; The power switch control module is further used for controlling the state of the power switch according to the third clock signal, thereby controlling the switching power supply to enter a DCM operation mode.

[0016] Preferably, the mode control module is further adapted to generate a fourth clock signal when the output voltage of the switching power supply does not fall below the first predetermined voltage threshold and the load meets a predetermined light load condition; The power switch control module is further used for controlling the switching power supply to enter a DCM operation mode by controlling the state of the power switch according to the fourth clock signal.

[0017] 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 predetermined voltage threshold and the load of the switching power supply meets a predetermined heavy load condition; generate a fifth clock signal when the output voltage is not less than the first predetermined voltage threshold and the load meets the predetermined heavy load condition and the input line voltage is greater than a second predetermined voltage threshold; and generate a sixth clock signal when the output voltage is not less than the first predetermined voltage threshold and the load meets the predetermined heavy load condition and the input line voltage is not greater than the second predetermined voltage threshold; Specifically, the power switch control module is used to control the state of the power switch of the switching power supply based on the first clock signal to control the switching power supply to enter a CCM or DCM operating mode, to control the state of the power switch based on the fifth clock signal to control the switching power supply to enter a QR operating mode, and to control the state of the power switch based on the sixth clock signal to control the switching power supply to enter a CCM or DCM operating mode.

[0018] 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 predetermined voltage threshold and the load of the switching power supply meets a predetermined heavy load condition, and to generate the second clock signal when the output voltage is not less than the first predetermined voltage threshold and the load meets the predetermined heavy load condition, and the input line voltage is within a full voltage range; Specifically, the power switch control module is used to control the state of the power switch based on the first clock signal to control the switching power supply to enter a CCM or DCM operating mode, and to control the state of the power switch based on the second clock signal to control the switching power supply to enter a QR operating mode.

[0019] In order to solve the above technical problems, the present application further provides a switching power supply including the above-mentioned operation mode control circuit for the switching power supply, and further comprising: a rectifying and filtering module for converting an input AC current into a DC current and outputting the filtered DC current to a primary side of a transformer; the transformer; an output module installed between the secondary side of the transformer and a load, the output module being used to generate a voltage based on the voltage of the secondary side of the transformer, and two voltage values ​​of each of the output voltages being different from each other; a power switch having a control end connected to the output end of the control device of the switching power supply;

[0020] As described above, the present invention provides a method, circuit, and switching power supply for controlling the operating mode of 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 of the switching power supply. When the output voltage is below a first predetermined voltage threshold and the load is heavy, the switching power supply is controlled to operate in CCM or DCM mode, thereby avoiding the problem of the switching power supply's operating frequency being reduced and prone to damage due to the QR mode restriction when a low output voltage is required for the switching power supply. When the output voltage is not below the first predetermined voltage threshold and the load is heavy, the switching power supply is controlled to operate in CCM, DCM, or QR mode based on the input line voltage, thereby ensuring the operating efficiency of the switching power supply and making it applicable to switching power supply application systems with a relatively wide output voltage / current range.

[0021] In order to more clearly explain the technical methods in the embodiments of the present invention, the following briefly introduces the prior art and drawings that need to be used in the embodiments. However, the drawings in the following description are only some embodiments of the present invention, and it is obvious that a person skilled in the art can obtain other drawings based on these drawings without performing any creative work. [Brief explanation of the drawings]

[0022] [Figure 1] FIG. 1 is a flowchart of the operation mode control method of a switching power supply provided in the present invention. [Figure 2] FIG. 2 is a schematic diagram of a first control mode in the operation mode control method of a switching power supply provided by the present invention. [Figure 3] FIG. 3 is a schematic diagram of a second control mode in the operation mode control method for a switching power supply provided by the present invention. [Figure 4] FIG. 4 is a schematic diagram of a third control mode in the operation mode control method of a switching power supply provided in the present invention. [Figure 5] FIG. 5 is a structural schematic diagram of the operation mode control circuit of the switching power supply provided in the present invention. [Figure 6] FIG. 6 is a structural schematic diagram of a mode control module in the operation mode control circuit of the switching power supply provided in the present invention. [Figure 7] FIG. 7 is a circuit diagram of a switching power supply provided by the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0023] The gist of the present invention is to provide a method, circuit and switching power supply for controlling the operation mode of a switching power supply, which can comprehensively control the switching power supply to enter different operation modes according to the output voltage of the switching power supply, the load and the input line voltage of the switching power supply.

[0024] In order to clarify the objectives, technical solutions and advantages of the embodiments of the present invention, the following clearly and completely describes the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention, but it is clear that the described embodiments are only some embodiments of the present invention and do not represent all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without performing creative work fall within the protection scope of the present invention.

[0025] Referring to FIG. 1, FIG. 1 is a flowchart of the operation mode control method for a switching power supply provided in the present invention, which includes:

[0026] S1: Determine whether the output voltage of the switching power supply is less than the first predetermined voltage threshold, if it is less, proceed to S2, if it is not less, proceed to S3; S2: When the load of the switching power supply meets the predetermined heavy load condition, control the switching power supply to enter CCM or DCM operation mode; S3: When the load of the switching power supply meets a predetermined heavy load condition, control the switching power supply to enter CCM, DCM, or QR operation mode according to the input line voltage of the switching power supply.

[0027] Switching power supplies have a wide range of applications, providing multiple output voltages with different voltage levels, such as those used in chargers. Currently, there are three commonly used operating modes for switching power supplies: discontinuous conduction mode (DCM), continuous conduction mode (CCM), and quasi-resonant mode (QR). Each operating mode has its own characteristics. DCM has the advantages of low switching loss and good stability, but also the disadvantages of a relatively low operating frequency and low efficiency. CCM has the advantage of a relatively high operating frequency, but is prone to stability issues. QR mode has a higher operating frequency and higher efficiency than DCM, but the power amplifier tube conducts when approaching the valley of resonance, resulting in a more concentrated spectrum and therefore poorer EMI.

[0028] While switching power supplies typically utilize a combination of several of the above operating modes to meet various needs, conventional technologies typically only consider whether the input line voltage of the switching power supply is high or low, and whether the load connected to the switching power supply is light, heavy, or full load, making it difficult to select the optimal operating mode for a switching power supply with a relatively wide output voltage range. For example, conventional technologies control a switching power supply to operate in QR mode when the load is heavy and the input voltage is high, and to operate in CCM when the input voltage is low. However, when the load is heavy and the input voltage is high, and the switching power supply requires a low output voltage and a high current (e.g., in the case of a multi-output power supply), the operating characteristics of QR mode itself often result in a drop in system frequency under full load conditions, which increases stress on the transformer in the switching power supply and increases the likelihood of magnetic component saturation, leading to power supply damage.

[0029] Therefore, in this application, the output voltage, load, and input line voltage of a switching power supply are simultaneously used as the basis for selecting whether the switching power supply enters different operating modes. Specifically, the switching power supply is first classified into two situations, low output voltage and high output voltage, based on the output voltage. Specifically, the classification is performed by determining whether the output voltage of the switching power supply is lower than a first predetermined voltage threshold. When the output voltage is lower than the first predetermined voltage threshold, i.e., a low output voltage situation, and the load is heavy, the switching power supply is controlled to operate in CCM or DCM operating mode, which can increase the frequency of the switching power supply and reduce its volume. At the same time, it also avoids the problems of the prior art, which control the switching power supply to operate in QR mode under such circumstances, such as a significant drop in system frequency, increased stress on the transformer, easy saturation of magnetic components, and power supply damage.

[0030] It should be noted that the specific value of the first predetermined voltage threshold can also be set based on the actual situation, and can usually be set to 7.5 V. The present application does not particularly limit the predetermined heavy load condition, and a full load situation can be included in the predetermined heavy load condition.

[0031] In this application, the specific operating mode of the switching power supply under the condition of a high output voltage and a heavy load is not particularly limited, and based on the difference in input line voltage, the switching power supply can select whether to always operate in QR mode, or to operate in QR mode when the input line voltage is a high line voltage, and to operate in CCM or DCM mode when the input line voltage is a low line voltage.

[0032] As described above, the present 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 of the switching power supply. When the output voltage is lower than a first predetermined voltage threshold and the load is heavy, the switching power supply is controlled to operate in CCM or DCM mode, thereby avoiding the problem of the switching power supply's operating frequency being reduced and prone to damage due to the QR mode restriction when a low output voltage is required for the switching power supply. When the output voltage is not lower than the first predetermined voltage threshold and the load is heavy, the switching power supply is controlled to operate in CCM, DCM, or QR mode based on the input line voltage, thereby ensuring the operating efficiency of the switching power supply.

[0033] Based on the above example, In one preferred embodiment, after determining whether the output voltage of the switching power supply is less than the first predetermined voltage threshold, further: If it is smaller, when the load of the switching power supply meets a predetermined light load condition, the method includes controlling the switching power supply to enter a DCM operation mode.

[0034] To ensure that the switching power supply can select the optimal operating mode under various conditions, this embodiment also provides a light-load operating mode for the switching power supply. Referring to Figure 2, this is a schematic diagram of a first control scheme of the operating mode control method for a switching power supply provided by the present invention, where the horizontal axis represents the load, the vertical axis represents the input line voltage, Vo represents the output voltage, and Vref represents the first predetermined voltage threshold. Specifically, it is necessary to first determine whether the switching power supply is operating at a low output voltage or a high output voltage based on the output voltage of the switching power supply. In this embodiment, if the output voltage is lower than the first predetermined voltage threshold, i.e., the output voltage is low, and there is no load, the switching power supply is controlled to operate in DCM, thereby reducing the transformer volume while also taking system efficiency into consideration.

[0035] In the present application, there are no particular limitations on the predetermined light load conditions that are required when the load is determined to be a light load, and no load can be included in the range of the predetermined light load conditions.

[0036] As described above, in this embodiment, in practical applications, priority is given to reducing the volume of the switching power supply, and at the same time, the efficiency of the switching power supply must also be considered. When the switching power supply is under no load and the output voltage is low, the switching power supply is controlled to enter the DCM operation mode.

[0037] In one preferred embodiment, after determining whether the output voltage of the switching power supply is less than the first predetermined voltage threshold, further: If not, when the load of the switching power supply meets a predetermined light load condition, the method includes controlling the switching power supply to enter a DCM operation mode.

[0038] To ensure that the switching power supply can select the optimal operating mode under various conditions, this embodiment also provides a light-load operating mode for the switching power supply. Specifically, it is necessary to first determine whether the switching power supply is operating at a low output voltage or a high output voltage based on the output voltage of the switching power supply. In this embodiment, if the output voltage is not below the first predetermined voltage threshold, i.e., the output voltage is high, and there is no load, the switching power supply is controlled to operate in DCM, thereby ensuring system stability and reducing switching loss.

[0039] Referring to FIG. 3, FIG. 3 is a schematic diagram of a second control mode of the operation mode control method of the switching power supply provided by the present invention, in which the horizontal axis in FIG. 3 represents the load, the vertical axis represents the input line voltage, Vo represents the output voltage, and Vref represents the first predetermined voltage threshold.

[0040] In one preferred embodiment, controlling the switching power supply to enter a CCM, DCM, or QR operating mode based on the input line voltage of the switching power supply comprises: When the input line voltage is greater than a second predetermined voltage threshold, controlling the switching power supply to enter a QR operating mode; If the input line voltage does not exceed a second predetermined voltage threshold, controlling the switching power supply to enter a CCM or DCM mode of operation.

[0041] To further ensure that the switching power supply can select the optimal operating mode under various conditions, in this embodiment, when the load at the rear end of the switching power supply is heavy load or full load, different operating modes are further selected according to the difference in input line voltage. Specifically, when the load is heavy load and the input line voltage is greater than a second predetermined voltage threshold, i.e., a high line voltage, the switching power supply is controlled to enter a QR operating mode to improve system efficiency; when the load is heavy load and the input line voltage is not greater than the second predetermined voltage threshold, i.e., a low line voltage, the switching power supply is controlled to enter a CCM or DCM operating mode to further improve system efficiency and ensure that the volume of the switching power supply is relatively small.

[0042] Referring to FIG. 3, FIG. 3 is a schematic diagram of a second control mode of the operation mode control method of the switching power supply provided by the present invention, in which the horizontal axis in FIG. 3 represents the load, the vertical axis represents the input line voltage, Vo represents the output voltage, Vref represents the first predetermined voltage threshold, and VL1 represents the second predetermined voltage threshold.

[0043] In the present application, the specific numerical value of the second predetermined voltage threshold is not particularly limited. For example, if the output voltage range of the switching power supply is between 3.3V and 20V, or between 5V and 20V, the first predetermined voltage threshold may be 7.5V and the second predetermined voltage threshold may be 180V.

[0044] In one preferred embodiment, controlling the switching power supply to enter a CCM, DCM, or QR operating mode based on the input line voltage of the switching power supply comprises: This includes controlling the switching power supply to enter a QR operating mode within the entire voltage range of the input line voltage.

[0045] Referring to FIG. 4, FIG. 4 is a schematic diagram of the third control mode of the operation mode control method of the switching power supply provided by the present invention, in which the horizontal axis represents the load, the vertical axis represents the input line voltage, Vo represents the output voltage, and Vref represents the first predetermined voltage threshold.

[0046] In order to further ensure that the switching power supply can select the optimal operating mode under various conditions, in this embodiment, when the load at the rear end of the switching power supply is heavy, the switching power supply is controlled to always operate in the QR operating mode regardless of whether the input line voltage is low or high, that is, by controlling the switching power supply to always operate in the QR operating mode over the entire range of input line voltage, the efficiency of the switching power supply can be maximized and the performance of the switching power supply can be improved. Therefore, on the premise that improving system efficiency is given priority, the control means in this embodiment can be selected when the switching power supply is under heavy load and the output voltage is high.

[0047] Referring to FIG. 5, FIG. 5 is a structural schematic diagram of the operation mode control circuit of the switching power supply provided in the present invention, and the control circuit includes: a mode control module 1 for generating a first clock signal when the output voltage of the switching power supply is lower than a first predetermined voltage threshold and the load of the switching power supply meets a predetermined heavy load condition, and for generating a second clock signal according to the input line voltage of the switching power supply when the output voltage is not lower than the first predetermined voltage threshold and the load meets a predetermined heavy load condition; and a power switch control module 2 that controls the state of the power switch of the switching power supply based on a first clock signal to control the switching power supply to enter a CCM or DCM operating mode, and that controls the state of the power switch based on a second clock signal to control the switching power supply to enter a CCM, DCM, or QR operating mode.

[0048] In this application, the output voltage, load, and input line voltage of the switching power supply are used as the basis for simultaneously selecting whether the switching power supply enters different operating modes. Specifically, the switching power supply is first divided into two situations, low output voltage and high output voltage, based on the output voltage. Specifically, the division is performed by determining whether the output voltage of the switching power supply is lower than a first predetermined voltage threshold. When the output voltage is lower than the first predetermined voltage threshold, i.e., the low output voltage situation, and the load is heavy, the mode control module 1 generates a first clock signal. After the power switch control module 2 receives the first clock signal, the switching power supply is controlled to operate in CCM or DCM operating mode based on the first clock signal. This increases the frequency of the switching power supply and reduces its volume. At the same time, it also avoids the problems of the prior art, which control the switching power supply to operate in QR mode under such circumstances, such as significantly lowering the system frequency, increasing stress on the transformer, easily causing saturation of magnetic components, and causing power supply damage.

[0049] It should be noted that the specific value of the first predetermined voltage threshold can be set based on the actual situation, and can usually be set to 7.5 V. The present application does not particularly limit the predetermined heavy load condition, and can be set based on the actual situation.

[0050] The present application does not specifically limit the specific operating mode of the switching power supply when the output voltage is high and the load is heavy. Instead, the switching power supply can select whether to always operate in QR mode or to operate in QR mode when the input line voltage is high and to operate in CCM or DCM mode when the input line voltage is low based on the difference in input line voltage. Specifically, when the output voltage does not fall below a first predetermined voltage threshold, i.e., when the output voltage is high and the load is heavy, a second clock signal is generated and correlated with 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.

[0051] As described above, the present invention discloses an operating mode control circuit for a switching power supply, including a mode control module 1 and a power switch control module 2. The mode control module 1 comprehensively generates a clock signal that controls 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 below a first predetermined voltage threshold and the load is heavy, thereby avoiding the problem of the switching power supply's operating frequency being reduced and prone to damage due to the QR mode restriction when a low output voltage is required for the switching power supply. When the output voltage is not below the first predetermined voltage threshold and the load is heavy, the switching power supply enters CCM, DCM, or QR mode, ensuring the operating efficiency of the switching power supply.

[0052] Based on the above example, In one 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 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, and the output terminal of the clock output selector 011 is the output terminal of the mode control module 1. can be, 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 magnitude of the load; The second clock module 013 is used to generate a second clock signal based on the primary resonant waveform of the switching power supply when the valley number of the primary resonant waveform does not exceed a predetermined valley number threshold, and to generate a second clock signal whose frequency and load magnitude are positively correlated when the valley number of the primary resonant waveform is greater than the predetermined valley number threshold; 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 smaller than a first predetermined voltage threshold and the load meets a predetermined heavy load condition, and to output the second clock signal output by the second clock output selector 133 when the output voltage is not smaller than the first predetermined voltage threshold and the load meets a predetermined heavy load condition.

[0053] In this embodiment, the first clock module itself can generate the first clock signal, and the frequency of the first clock signal is positively correlated with the magnitude of the load. Therefore, when the load is heavy, the frequency of the first clock signal is relatively high. At this time, the power switch control module 2 uses the first clock signal to control the state of the power switch, causing the switching power supply to enter the CCM operation mode. When the load decreases, the frequency of the first clock signal also decreases accordingly. At this time, the power switch control module 2 uses the first clock signal to control the state of the power switch, causing the switching power supply to enter the DCM operation mode. Enter the production mode.

[0054] Since the QR operating mode is conductive at the valley portion of the primary resonant waveform that is equal to a predetermined valley number threshold, and the DCM operating mode is conductive at any timing of the primary resonant waveform, the second clock module causes the switching power supply to enter the QR operating mode by generating a second clock signal based on the primary resonant waveform when the valley number of the primary resonant waveform does not exceed the predetermined valley number threshold, and causes the switching power supply to enter the DCM operating mode by generating a second clock signal whose frequency and load magnitude are positively correlated when the valley number of the primary resonant waveform is greater than the predetermined valley number threshold.

[0055] In one preferred embodiment, the second clock module 013 includes a second clock sub-module 131, a valley lock module 132, and a second clock output selector 133; The output terminal of the second clock sub-module 131 and the output terminal of the valley lock module 132 are respectively connected to the first input terminal and the second input terminal of the second clock output selector 133, and the output terminal of the second clock output selector 133 is connected to the second clock input terminal of the clock output selector 011; The second clock sub-module 131 is used to generate a second clock sub-signal when the valley number of the primary resonant waveform of the switching power supply is greater than a predetermined valley number threshold, and the frequency of the second clock sub-signal and the valley number of the primary resonant waveform are negatively correlated, and the valley number of the primary resonant waveform and the magnitude of the load are negatively correlated; The valley lock module 132 is used to control the primary resonant waveform to develop in a valley portion of the number of valleys when the number of valleys of the primary resonant waveform does not exceed a predetermined valley number threshold, and the primary resonant waveform that develops in a valley portion of the number of valleys is used as a second clock valley signal; The second clock output selector 133 is used to output the second clock valley signal generated by the valley lock module 132 to the clock output selector 011 as the second clock signal when the valley number of the primary resonant waveform is greater than a predetermined valley number threshold, and to 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 valley number of the primary resonant waveform does not exceed the predetermined valley number threshold.

[0056] Referring to Figure 6, Figure 6 is a structural schematic diagram of a mode control module in the operating mode control circuit of a switching power supply provided by the present invention. In Figure 6, Clock Select 1 is a clock output selector 011, Frequency Control 1 and Clock 1 together form a first clock module 012, Frequency Control 2 and Clock 2 together form a second clock module 013, Clock Select 2 is a second clock output selector 133, n is the valley number of the primary resonant waveform, N is a predetermined valley number threshold, COMP is a parameter exhibiting a positive correlation with the load, Valley is the primary 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 clock signal ultimately controlling the power switch. The Slope signal in Figure 6 is used to suppress harmonic oscillation by implementing slope compensation in the CCM mode of the switching power supply.

[0057] In this embodiment, a specific structure of the mode control module 1 for generating the first clock signal and the second clock signal is provided. 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 lock module 132, and the second clock output selector 133 according to the output voltage of the switching power supply.

[0058] Specifically, the first clock module itself can generate the first clock signal, and the frequency of the first clock signal is positively correlated with the magnitude of the load, so that when the load is heavy, the frequency of the first clock signal is relatively high, and at this time, the power switch control module 2 uses the first clock signal to control the state of the power switch, causing the switching power supply to enter the CCM operation mode.When the load decreases, the frequency of the first clock signal also decreases, and at this time, the power switch control module 2 uses the first clock signal to control the state of the power switch, causing the switching power supply to enter the DCM operation mode.

[0059] Because the valley count of the primary resonant waveform is negatively correlated with the load magnitude, when the load is heavy, the valley count of the primary resonant waveform is less than the predetermined valley count threshold. Therefore, the valley-lock module 132 expands the valley portion of the primary resonant waveform by the valley count to generate a new clock signal, i.e., the second clock valley signal, as the second clock signal. The power switch control module 2 uses this signal to control the state of the power switch, causing the switching power supply to enter the QR operating mode. As the load gradually decreases, the valley count of the primary resonant waveform gradually increases until it exceeds the predetermined valley count threshold. Therefore, the second clock sub-module 131 itself generates the second clock sub-signal. Because the frequency of the second clock sub-signal is positively correlated with the load magnitude, the power switch control module 2 uses the second clock sub-signal to control the state of the power switch, causing the switching power supply to enter the DCM operating mode.

[0060] As described above, the mode control module 1 provided in this embodiment can generate clock signals to put the switching power supply into various operating modes, and 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 put it into various operating modes under different conditions, and moreover, the circuit structure is simple and easy to implement.

[0061] In one preferred embodiment, the power switch control module 2 includes an AND gate, a D flip-flop, and a driving 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 1, the positive phase 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 driving circuit, and the output terminal of the driving circuit is connected to the control terminal of the power switch as the output terminal of the power switch control module 2; The driver circuit is used to amplify the signal output by the output terminal of the AND gate so as to facilitate control of the state of the power switch.

[0062] Referring to Figure 5, Figure 5 is a structural schematic diagram of the operating mode control circuit of the switching power supply provided by the present invention, in which COMP is a signal reflecting the magnitude of the load, Valley is the primary resonant wave, Line is the input line voltage, Vout is the output voltage, CLK is a clock signal for controlling the power switch, Gate is a signal received by the control end of the power switch, and the Slope signal is used to suppress harmonic oscillation by realizing slope compensation in the CCM mode of the switching power supply.

[0063] 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 combines the clock signal output by the mode control module 11 and the signal output by the D flip-flop and transmits the combined signal to the driving circuit. The driving circuit amplifies the signal output by the AND gate into a signal for controlling the power switch, and inputs it into the control terminal of the power switch to control the state of the power switch, thereby realizing control of the operating mode of the switching power supply.

[0064] As described above, 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.

[0065] In one preferred embodiment, the mode control module 1 is further adapted to generate a third clock signal when the output voltage of the switching power supply is less than a first predetermined voltage threshold and the load meets a predetermined light load condition; The power switch control module 2 is further used for controlling the state of the power switch according to the third clock signal, thereby controlling the switching power supply to enter the operation mode of DCM.

[0066] For the introduction related to this embodiment, please refer to the embodiment corresponding to the operation mode control method of the switching power supply, and the description will not be repeated in this application.

[0067] In one preferred embodiment, the mode control module 1 is further adapted to generate a fourth clock signal when the output voltage of the switching power supply is less than a first predetermined voltage threshold and the load meets a predetermined light load condition; The power switch control module 2 is further used to control the state of the power switch according to the fourth clock signal, thereby controlling the switching power supply to enter the operation mode of DCM.

[0068] For the introduction related to this embodiment, please refer to the embodiment corresponding to the operation mode control method of the switching power supply, and the description will not be repeated in this application.

[0069] In one 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 lower than a first predetermined voltage threshold and the load of the switching power supply meets a predetermined heavy load condition; generate a fifth clock signal when the output voltage is not lower than the first predetermined voltage threshold and the load meets a predetermined heavy load condition and the input line voltage is higher than a second predetermined voltage threshold; and generate a sixth clock signal when the output voltage is not lower than the first predetermined voltage threshold and the load meets a predetermined heavy load condition and the input line voltage is not higher than the second predetermined voltage threshold; The power switch control module 2 is specifically used to control the state of the power switch in the switching power supply based on a first clock signal to control the switching power supply to enter a CCM or DCM operating mode, to control the state of the power switch based on a fifth clock signal to control the switching power supply to enter a QR operating mode, and to control the state of the power switch based on a sixth clock signal to control the switching power supply to enter a CCM or DCM operating mode.

[0070] For the introduction related to this embodiment, please refer to the embodiment corresponding to the operation mode control method of the switching power supply, and the description will not be repeated in this application.

[0071] In one 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 predetermined voltage threshold and the load of the switching power supply meets a predetermined heavy load condition, and to generate a second clock signal when the output voltage is not less than the first predetermined voltage threshold, the load meets a predetermined heavy load condition, and the input line voltage is within a full voltage range; The power switch control module 2 is specifically used to control the state of the power switch based on a first clock signal to control the switching power supply to enter a CCM or DCM operating mode, and to control the state of the power switch based on a second clock signal to control the switching power supply to enter a QR operating mode.

[0072] For the introduction related to this embodiment, please refer to the embodiment corresponding to the operation mode control method of the switching power supply, and the description will not be repeated in this application.

[0073] In order to solve the above technical problems, the present application further provides a switching power supply including the above-mentioned operation mode control circuit for the switching power supply, and further comprising: a rectifying and filtering module for converting input AC to DC and outputting the filtered DC to the primary side of a transformer; A transformer and An output module is installed between the secondary side of the transformer and the load, and is used to generate a voltage based on the voltage of the secondary side of the transformer, and two voltage values ​​of each output voltage are different from each other; and a power switch having a control end connected to the output end of the control device of the switching power supply.

[0074] The switching power supply of the present application may be a switching power supply with a relatively wide output voltage range, capable of selecting the optimal operating mode according to different output voltage requirements. Referring to Figure 7, Figure 7 is a circuit diagram of the switching power supply provided by the present invention. The switching power supply in Figure 7 is a flyback type switching power supply, and the switching power supply controller controls the conduction state of the power switch to operate the switching power supply in different operating modes, thereby ensuring the operating performance of the switching power supply. For an introduction to the switching power supply provided by the present application, please refer to the above-mentioned embodiment of the control method for the switching power supply, and therefore, a detailed description will not be provided here.

[0075] Each embodiment of this specification is described in a stepwise manner, and the key points of each embodiment are different from the other embodiments, and the same or similar parts between the embodiments can be mutually referenced. The devices disclosed in the embodiments correspond to the methods disclosed in the embodiments and are relatively simply described, so for relevant parts, please refer to the method section.

[0076] It should also be explained that relational terms such as "first," "second," etc. are used herein only to distinguish one entity or operation from another and do not necessarily require or imply any substantial relationship or order between those entities or operations. Furthermore, the terms "comprise," "comprise," or any other variation thereof, cover non-exclusive inclusions, such that a process, method, article, or facility that includes a set of elements includes not only those elements but also other elements not expressly listed or inherent in that type of process, method, article, or facility. Unless more restrictive, an element defined by the phrase "comprising a..." does not exclude the presence of additional identical elements within the process, method, article, or facility that includes the element.

[0077] The above description of the disclosed embodiments will enable those skilled in the art to make or use the present invention. Various modifications to these embodiments will be 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 present 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

1. 1. An operation mode control method for a switching power supply, comprising: determining whether the output voltage of the switching power supply is less than a first predetermined voltage threshold; If it's small, When the load of the switching power supply meets a predetermined heavy load condition, control the switching power supply to enter one operation mode selected from the operation modes of CCM and DCM; or When the load of the switching power supply meets a predetermined light load condition, the switching power supply is controlled to enter a DCM operation mode; If it's not small, When the load of the switching power supply meets the predetermined heavy load condition, When the input line voltage of the switching power supply is greater than a second predetermined voltage threshold, controlling the switching power supply to enter a QR operating mode; or If the input line voltage of the switching power supply does not exceed the second predetermined voltage threshold, controlling the switching power supply to enter one of the operation modes selected from CCM, DCM, or QR operation modes; When the load of the switching power supply meets the predetermined light load condition, the switching power supply is controlled to enter a DCM operation mode. characterized in that it comprises A method for controlling the operating mode of a switching power supply.

2. and controlling the switching power supply to enter the QR operating mode within the entire voltage range of the input line voltage when the output voltage of the switching power supply is not lower than the first predetermined voltage threshold and the load of the switching power supply meets the predetermined heavy load condition.

2. The method for controlling the operation mode of a switching power supply according to claim 1.

3. a mode control module for generating a first clock signal when the output voltage of a switching power supply is less than a first predetermined voltage threshold and a load of the switching power supply meets a predetermined heavy load condition, generating a second clock signal when the output voltage is not less than the first predetermined voltage threshold and the load meets the predetermined heavy load condition, generating a third clock signal when the output voltage is less than the first predetermined voltage threshold and the load meets a predetermined light load condition, and generating a fourth clock signal when the output voltage is not less than the first predetermined voltage threshold and the load meets a predetermined light load condition; a power switch control module for controlling the state of the power switch of the switching power supply based on the first clock signal to control the switching power supply to enter one operation mode selected from CCM or DCM operation modes, and for controlling the state of the power switch based on the second clock signal to control the switching power supply to enter one operation mode selected from CCM, DCM, or QR operation modes. Operating mode control circuit of a switching power supply.

4. the mode control module includes a clock output selector, a first clock module, and a second clock module; an output terminal of the first clock module and an output terminal of the second clock module are respectively connected to a first clock input terminal and a second clock input terminal of the clock output selector, and an output terminal of the clock output selector is an 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 magnitude of the load; The second clock module is used to generate a second clock signal based on the primary resonant waveform of the switching power supply when the valley number of the primary resonant waveform is below a predetermined valley number threshold, and to generate a second clock signal whose frequency is positively correlated with the magnitude of the load when the valley number of the primary resonant waveform is greater than the predetermined valley number threshold; the clock output selector is used to output the first clock signal generated by the first clock module when the output voltage is lower than the first predetermined voltage threshold and the load meets the predetermined heavy load condition, and to output the second clock signal output by the second clock output selector when the output voltage is not lower than the first predetermined voltage threshold and the load meets the predetermined heavy load condition.

4. The operation mode control circuit of a switching power supply according to claim 3.

5. the second clock module includes a second clock sub-module, a valley lock module, and the second clock output selector; an output terminal of the second clock sub-module and an output terminal of the valley lock module are respectively connected to a first input terminal and a second input terminal of the second clock output selector, and an output terminal of the second clock output selector is connected to a second clock input terminal of the clock output selector; the second clock sub-module is used to generate a second clock sub-signal when the valley number of the primary resonant waveform of the switching power supply is greater than a predetermined valley number threshold, the frequency of the second clock sub-signal and the valley number of the primary resonant waveform exhibit a negative correlation, and the valley number of the primary resonant waveform and the magnitude of the load exhibit a negative correlation; the valley lock module generates a second clock valley signal when the valley count of the primary resonant waveform does not exceed the predetermined valley count threshold; the second clock output selector is used to output the second clock valley signal generated by the valley lock module to the clock output selector as the second clock signal when the valley number of the primary resonant waveform is greater than the predetermined valley number threshold, and to output the second clock sub-signal generated by the second clock sub-module to the clock output selector as the second clock signal when the valley number of the primary resonant waveform does not exceed the predetermined valley number threshold.

5. The operating mode control circuit of a switching power supply according to claim 4.

6. The power switch control module includes an AND gate, a D flip-flop, and a driving circuit; a first input terminal of the AND gate and a clock signal input terminal of the D flip-flop are both connected to the output terminal of the mode control module, a positive phase output terminal of the D flip-flop is connected to the second input terminal of the AND gate, an output terminal of the AND gate is connected to the input terminal of the driving circuit, and an output terminal of the driving circuit is connected to the control terminal of the power switch as the output terminal of the power switch control module; The driving circuit amplifies a signal output from the output terminal of the AND gate and is used to control the state of the power switch.

4. The operation mode control circuit of a switching power supply according to claim 3.

7. the power switch control module is further used to control the state of the power switch based on the third clock signal, thereby controlling the switching power supply to enter a DCM operation mode.

4. The operation mode control circuit of a switching power supply according to claim 3.

8. the power switch control module is further used to control the state of the power switch based on the fourth clock signal, thereby controlling the switching power supply to enter a DCM operation mode.

4. The operation mode control circuit of a switching power supply according to claim 3.

9. The mode control module is specifically used for generating the first clock signal when the output voltage of the switching power supply is lower than a first predetermined voltage threshold and the load of the switching power supply meets a predetermined heavy load condition; generating a fifth clock signal when the output voltage is not lower than the first predetermined voltage threshold, the load meets the predetermined heavy load condition, and the input line voltage of the switching power supply is higher than a second predetermined voltage threshold; and generating a sixth clock signal when the output voltage is not lower than the first predetermined voltage threshold, the load meets the predetermined heavy load condition, and the input line voltage is not higher than a second predetermined voltage threshold; Specifically, the power switch control module is used to control the state of the power switch of the switching power supply based on the first clock signal to control the switching power supply to enter a CCM or DCM operation mode, to control the state of the power switch based on the fifth clock signal to control the switching power supply to enter a QR operation mode, and to control the state of the power switch based on the sixth clock signal to control the switching power supply to enter a CCM or DCM operation mode.

9. The operation mode control circuit of the switching power supply according to claim 3.

10. The mode control module is specifically used to generate the first clock signal when the output voltage of the switching power supply is lower than the first predetermined voltage threshold and the load of the switching power supply meets a predetermined heavy load condition, and to generate the second clock signal when the output voltage is not lower than the first predetermined voltage threshold, the load meets the predetermined heavy load condition, and the input line voltage of the switching power supply is within a full voltage range; Specifically, the power switch control module is used to control the state of the power switch based on the first clock signal to control the switching power supply to enter a CCM or DCM operation mode, and to control the state of the power switch based on the second clock signal to control the switching power supply to enter a QR operation mode.

9. The operation mode control circuit of the switching power supply according to claim 3.

11. The switching power supply includes an operation mode control circuit according to any one of claims 3 to 8, and further includes: a rectifying and filtering module for converting an input AC current into a DC current and outputting the filtered DC current to a primary side of a transformer; the transformer; an output module disposed between the secondary side of the transformer and a load, the output module being used to generate a voltage based on the voltage of the secondary side of the transformer; a power switch whose control end is connected to the output end of the control device of the switching power supply, Switching power supply.

12. When the output voltage of the switching power supply is not lower than the first predetermined voltage threshold, if the load of the switching power supply meets the predetermined heavy load condition, and if the input line voltage of the switching power supply does not exceed the second predetermined voltage threshold, the switching power supply is controlled to enter a DCM operation mode.

2. The method for controlling the operation mode of a switching power supply according to claim 1.

13. The state of the power switch is controlled based on the sixth clock signal, so that the switching power supply enters a DCM operation mode.

10. The operating mode control circuit of a switching power supply according to claim 9.

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