Operation mode control method for switching power supply, 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 to 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 a method, circuit and switching power supply for controlling the operation mode of a switching power supply with a wide output range. [Background technology]

[0003] Switching power supplies are widely used due to their simple circuit structure and their ability to provide multiple DC outputs with high efficiency. The operating modes of switching power supplies include CCM (Continuous Conduction Mode), DCM (Discontinuous Conduction Mode), and QR (Quasi-Resonant Mode). In conventional technology, when the load connected to the rear end of the switching power supply is heavy and the input line voltage is high, the switching power supply is controlled to operate in QR mode. However, when there is a wide output voltage demand for the switching power supply, for example, when there is a low output voltage demand, the operating frequency of the switching power supply is limited due to the characteristics of the QR mode itself, which increases the stress on the transformer in the switching power supply, making it more likely to cause problems such as saturation of the magnetic elements and damage to the switching power supply. Summary of the Invention

[0004] The objective of the present invention is to provide an operation mode control method, circuit and 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 an output voltage of the switching power supply is less than a first predetermined voltage threshold; if so, control the switching power supply to enter a CCM or DCM operation mode when the load of the switching power supply meets a predetermined heavy load condition; if not, then controlling the switching power supply to enter a CCM, DCM, or QR operating mode based on an input line voltage of the switching power supply when the load of the switching power supply meets the predetermined heavy load condition.

[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 so, controlling the switching power supply to enter a DCM operating mode when the load of the switching power supply meets a predetermined light load condition.

[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, controlling the switching power supply to enter a DCM operating mode when the load of the switching power supply meets a predetermined light load condition.

[0009] Preferably, controlling the switching power supply to enter a CCM, DCM, or QR operating mode based on an input line voltage of the switching power supply comprises: If 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 an input line voltage of the switching power supply comprises: Controlling the switching power supply to enter the QR mode of operation within a full 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 is used to generate a first clock signal when the output voltage of a switching power supply is smaller 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 according to an input line voltage of the switching power supply when the output voltage is not below the first predetermined voltage threshold and the load meets the predetermined heavy load condition; Controlling the state of a 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. and a power switch control module used to control the switching power supply to enter a CCM, DCM, or QR operation mode by controlling the state of the power switch based on the second clock signal.

[0012] Preferably, the mode control module includes a clock output selector, a first clock module, and a second clock module; an output end of the first clock module and an output end of the second clock module are respectively connected to a first clock input end and a second clock input end of the clock output selector, and an output end of the clock output selector is an output end 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 a 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 having a frequency that 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 a 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 a 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; The output terminal of the second clock sub-module and the output terminal of the valley lock 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 sub-module is used to generate a second clock sub-signal when a valley number of a primary resonant waveform of the switching power supply is greater than a predetermined valley number threshold, and a frequency of the second clock sub-signal and a valley number of the primary resonant waveform are negatively correlated, and a valley number of the primary resonant waveform and a magnitude of the load are negatively correlated, The valley lock module is used to control the primary resonant waveform to develop in a valley portion of the valley number when the valley number of the primary resonant waveform does not exceed the predetermined valley number threshold, and the primary resonant waveform developed in the valley portion of the valley number is a second clock valley signal; The second clock output selector is used to output a 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 a 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; 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 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; The drive circuit is used to control the state of the power switch by amplifying the signal output by 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 switching power supply to enter a DCM operation mode by controlling a state of the power switch according to the third clock signal.

[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 a state of the power switch according to the fourth clock signal.

[0017] Preferably, the mode control module is specifically used for generating 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; generating 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; generating 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 a second predetermined voltage threshold; Specifically, the power switch control module is used to control the switching power supply to enter a CCM or DCM operating mode by 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 a QR operating mode by controlling the state of the power switch based on the fifth clock signal, and to control the switching power supply to enter a CCM or DCM operating mode by controlling the state of the power switch based on the sixth clock signal.

[0018] Preferably, the mode control module is specifically used for generating 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 for generating 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; The power switch control module is specifically used to control the switching power supply to enter a CCM or DCM operating mode by controlling the state of the power switch based on the first clock signal, and to control the switching power supply to enter a QR operating mode by controlling the state of the power switch based on the second clock signal.

[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, further comprising: a rectifying and filtering module for converting an input AC current to a DC current and outputting the filtered DC current to a primary side of a transformer; The transformer; An output module is 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 are 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 operation mode of a switching power supply, and comprehensively controls the switching power supply to enter different operation modes according to 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 that the operating frequency of the switching power supply is reduced and easily damaged due to the limitation of QR mode when there is a demand for a low output voltage of 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 according to the input line voltage to operate in one of CCM, DCM or QR modes, thereby ensuring the operation efficiency of the switching power supply and also being applicable to a switching power supply application system 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 provides a brief introduction to 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 those skilled in the art can obtain other drawings based on these drawings on the premise that they do not perform creative work. [Brief description of the drawings]

[0022] [Figure 1] FIG. 1 is a flow chart of the operation mode control method of a switching power supply provided in the present invention. [Diagram 2] FIG. 2 is a schematic diagram of a first control mode in the operation mode control method of a switching power supply provided in the present invention. [Diagram 3] FIG. 3 is a schematic diagram of a second control mode in the operation mode control method of a switching power supply provided in 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. [Diagram 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 a 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 PREFERRED EMBODIMENTS

[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 make the objectives, technical methods and advantages of the embodiments of the present invention clearer, the technical methods of the embodiments of the present invention are described below in detail and completely in conjunction with the drawings in the embodiments of the present invention, but it is clear that the described embodiments are only some of the embodiments of the present invention, and are not all of the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without performing creative labor, fall within the scope of protection of the present invention.

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

[0026] S1: judge whether the output voltage of the switching power supply is less than a 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 a 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 can provide multiple output voltages with different voltage values, which can be used in chargers, etc., and have a wide range of applications. Currently, there are three operating modes commonly used in switching power supplies: discontinuous current mode (DCM), continuous current mode (CCM), and quasi-resonant mode (QR). Each operating mode has its own characteristics. DCM has the advantages of small switching loss and good stability, but at the same time, it has the disadvantages of a relatively low operating frequency and relatively low efficiency. CCM has the advantage of a relatively high operating frequency, but is prone to problems in terms of stability. QR mode has a higher operating frequency and efficiency than DCM, but the power amplifier tube conducts when approaching the valley of resonance, and the spectrum is relatively concentrated, so EMI is relatively poor.

[0028] When controlling a switching power supply, the above several operating modes are usually combined to meet the demands of various situations. In the conventional technology, the only conditions for selecting different operating modes are whether the input line voltage of the switching power supply is a high line voltage or a low line voltage, and whether the load connected to the switching power supply is a light load, a heavy load, or a full load. Therefore, in practical applications, the optimum operating mode cannot be selected for a switching power supply with a relatively wide output voltage range, that is, when there is a demand for different output voltages. For example, in the conventional technology, when the load is a heavy load and the input voltage is a high line voltage, the switching power supply is controlled to operate in QR mode, and when the input voltage is a low line voltage, the switching power supply is controlled to operate in CCM. However, when the load is a heavy load and the input voltage is a high line voltage, if the switching power supply is required to output a low output voltage and a large current (for example, in the case of multiple outputs), the operating characteristics of the QR mode itself often cause the system frequency to drop in a full load situation, which increases the stress of the transformer in the switching power supply, making it easier for the magnetic element to saturate, causing power supply damage.

[0029] Therefore, in this application, the output voltage, load and input line voltage of the switching power supply are the selection basis for simultaneously controlling the switching power supply to enter different operation 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 made by determining whether the output voltage of the switching power supply is smaller than a first predetermined voltage threshold. In the situation where the output voltage is smaller than the first predetermined voltage threshold, i.e., low output voltage, and the load is heavy, the switching power supply is controlled to operate in the CCM or DCM operation mode, so that the frequency of the switching power supply can be increased and the volume of the switching power supply can be reduced, and at the same time, the problems of the system frequency being significantly reduced, the stress of the transformer being large, the magnetic element being easily saturated, and the power supply being damaged, which are caused by controlling the switching power supply to operate in the QR mode under the above situation in the prior art, can be avoided.

[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 be generally set to 7.5 V. The present application does not particularly limit the predetermined heavy load condition, and the full load situation can be included in the predetermined heavy load condition.

[0031] In the present application, there is no particular limitation on the specific operating mode of the switching power supply under the condition that the output voltage is high and the load is heavy. Based on the difference in the 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 method for controlling a switching power supply, which comprehensively controls the switching power supply to enter different operating modes according to 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 that the operating frequency of the switching power supply is reduced and easily damaged due to the limitation of QR mode when there is a demand for a low output voltage of 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 according to the input line voltage to operate in one of CCM, DCM or QR modes, 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 a first predetermined voltage threshold, further comprising: If so, controlling the switching power supply to enter a DCM operating mode when the load of the switching power supply meets a predetermined light load condition.

[0034] In addition, in order to ensure that the switching power supply can select the optimal operation mode under various conditions, this embodiment also provides an operation mode of the switching power supply when it is lightly loaded. Referring to FIG. 2, FIG. 2 is a schematic diagram of a first control method of the operation mode control method of the switching power supply provided by the present invention, in which the horizontal axis in FIG. 2 is the load, the vertical axis is the input line voltage, Vo is the output voltage, and Vref is the first predetermined voltage threshold. Specifically, it is necessary to first continue to determine whether the switching power supply has a low output voltage or a high output voltage based on the output voltage of the switching power supply. In this embodiment, when the output voltage is lower than the first predetermined voltage threshold, that is, the output voltage is low, and the load is no load, the switching power supply is controlled to operate in DCM, so that the volume of the transformer can be reduced while the system efficiency can be taken into consideration.

[0035] In the present application, there is no particular limitation on the predetermined light load condition 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 condition.

[0036] As described above, in this embodiment, in practical applications, in a situation where reducing the volume of the switching power supply is given priority while the efficiency of the switching power supply must also be considered, when the switching power supply simultaneously satisfies the conditions of no load and low output voltage, 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 a first predetermined voltage threshold, further comprising: If not, controlling the switching power supply to enter a DCM operating mode when the load of the switching power supply meets a predetermined light load condition.

[0038] In addition, in order to ensure that the switching power supply can select the optimal operation mode under various conditions, this embodiment also provides an operation mode for the switching power supply when it is lightly loaded. Specifically, it is necessary to first continue to determine whether the switching power supply has a low output voltage or a high output voltage based on the output voltage of the switching power supply. In this embodiment, when the output voltage is not below the first predetermined voltage threshold, that is, when the output voltage is a high output voltage, and when the load is no load, the switching power supply is controlled to operate in DCM, so that the stability of the system can be ensured and the switching loss can be reduced.

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

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

[0041] In order to further ensure that the switching power supply can select the optimal operation 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 operation modes are further selected according to the difference of input line voltage. Specifically, when the load is heavy load and the input line voltage is greater than the second predetermined voltage threshold, i.e., high line voltage, the switching power supply is controlled to enter the QR operation mode, thereby improving system efficiency; when the load is heavy load and the input line voltage is not greater than the second predetermined voltage threshold, i.e., low line voltage, the switching power supply is controlled to enter the CCM or DCM operation mode, thereby further improving system efficiency and ensuring 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 method of the operation mode control method of a switching power supply provided by the present invention, in which the horizontal axis in FIG. 3 is the load, the vertical axis is the input line voltage, Vo is the output voltage, Vref is the first predetermined voltage threshold, and VL1 is 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, when 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 a switching power supply to enter a CCM, DCM, or QR mode of operation based on an input line voltage of the switching power supply includes: 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 in FIG. 4 is the load, the vertical axis is the input line voltage, Vo is the output voltage, and Vref is the first predetermined voltage threshold.

[0046] In order to further ensure that the switching power supply can select the optimal operation mode under various conditions, in this embodiment, when the load at the rear end of the switching power supply is heavy, regardless of whether the input line voltage is low line voltage or high line voltage, the switching power supply is controlled to always operate in the QR operation mode, that is, in the entire range of the input line voltage, the switching power supply is controlled to always operate in the QR operation mode, thereby maximizing the efficiency of the switching power supply and improving the performance of the switching power supply. Therefore, on the premise of prioritizing the improvement of system efficiency, in the situation where the switching power supply is heavy loaded and the output voltage is high, the control means in this embodiment can be selected.

[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, 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 smaller 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 operation mode, and 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 operation mode.

[0048] In this application, the output voltage, load and input line voltage of the switching power supply are used as the selection basis for simultaneously controlling the switching power supply to enter different operation 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 smaller than a first predetermined voltage threshold. When the output voltage is smaller than the first predetermined voltage threshold, that is, the low output voltage situation, and the load is heavy, the mode control module 1 generates a first clock signal, and after the power switch control module 2 receives the first clock signal, the switching power supply is controlled to operate in the CCM or DCM operation mode according to the first clock signal, so that the frequency of the switching power supply can be increased and the volume of the switching power supply can be reduced, and at the same time, the problems of the system frequency being significantly reduced, the stress of the transformer being large, the magnetic element being easily saturated, and the power supply being damaged, which are caused by controlling the switching power supply to operate in the QR mode in the prior art under the above situation, can be avoided.

[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 be set to 7.5 V in general. The present application does not particularly limit the predetermined heavy load condition, and can be set based on the actual situation.

[0050] In the present application, the specific operation mode of the switching power supply under the condition that the output voltage is high and the load is heavy is not particularly limited, and 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 line voltage, and to operate in CCM or DCM mode when the input line voltage is low line voltage according to the difference of the input line voltage. Specifically, when the output voltage does not fall below a first predetermined voltage threshold, that is, when the output voltage is high and the load is heavy, a second clock signal is generated, and the second clock signal is associated with the input line voltage of the switching power supply. The power switch control module 2 controls the switching power supply to enter the operation mode of CCM, DCM, or QR according to the second clock signal.

[0051] As described above, the present invention discloses an operation mode control circuit of a switching power supply, which includes a mode control module 1 and a power switch control module 2. The mode control module 1 comprehensively generates a clock signal that controls the switching power supply to enter different operation modes according to 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 lower than a first predetermined voltage threshold and the load is heavy, thereby avoiding the problem that the operating frequency of the switching power supply is low and easily damaged due to the limitation of QR mode when there is a demand for low output voltage of 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 enters CCM, DCM or QR mode, thereby ensuring the operation 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 according to 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 having a frequency and a load magnitude that 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 below 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, so that the switching power supply enters the operation mode of CCM. 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, so that the switching power supply enters the operation mode of DCM. Enter the production mode.

[0054] Since the QR operation mode is conductive at the valley portion of the primary resonant waveform that has a preset valley number threshold, and the DCM operation mode is conductive at any timing of the primary resonant waveform, the second clock module causes the switching power supply to enter the QR operation 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 a predetermined valley number threshold, and causes the switching power supply to enter the DCM operation 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 valley number when the valley number of the primary resonant waveform does not exceed a predetermined valley number threshold, and the primary resonant waveform that develops in the valley portion of the valley number is 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 a predetermined valley number threshold.

[0056] Referring to Fig. 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 by the present invention. In Fig. 6, clock selection 1 is a clock output selector 011, frequency control 1 and clock 1 jointly constitute a first clock module 012, frequency control 2 and clock 2 jointly constitute a second clock module 013, clock selection 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 that exhibits 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 for finally controlling the power switch. In addition, the Slope signal in Fig. 6 is used to suppress harmonic oscillation by realizing 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 a first clock signal and a second clock signal is provided, and the clock output selector 011 can select whether to output the first clock signal generated by the first clock module 012 or the second clock signal generated by the second clock 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 to make the switching power supply enter the operation mode of CCM. When the load decreases, the frequency of the first clock signal also decreases accordingly, and at this time, the power switch control module 2 uses the first clock signal to control the state of the power switch to make the switching power supply enter the operation mode of DCM.

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

[0060] As described above, the mode control module 1 provided in this embodiment can generate clock signals for putting 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 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 provided by the output 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 operation mode control circuit of the switching power supply provided in the present invention, in which COMP in Figure 5 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 them 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 to 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 according to the first clock signal and the second clock signal, and has a simple circuit structure and is easy to implement.

[0065] In one preferred embodiment, the mode control module 1 is further used for generating 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 switching power supply to enter the working mode of DCM by controlling the state of the power switch according to the third clock signal.

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

[0067] In one preferred embodiment, the mode control module 1 is further used for generating 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 for controlling the switching power supply to enter the working mode of DCM by controlling the state of the power switch according to the fourth clock signal.

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

[0069] In one preferred embodiment, the mode control module 1 is specifically used for generating a first clock signal when the output voltage of the switching power supply is smaller 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 smaller than the first predetermined voltage threshold and the load meets a predetermined heavy load condition and the input line voltage is greater than a second predetermined voltage threshold; and generating a sixth clock signal when the output voltage is not smaller than the first predetermined voltage threshold and the load meets a predetermined heavy load condition and the input line voltage is not greater than the second predetermined voltage threshold; The power switch control module 2 is specifically used to control the switching power supply to enter a CCM or DCM operating mode by controlling 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 QR operating mode by controlling the state of the power switch based on a fifth clock signal, and to control the switching power supply to enter a CCM or DCM operating mode by controlling the state of the power switch based on a sixth clock signal.

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

[0071] In one preferred embodiment, the mode control module 1 is specifically used for generating 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 for generating 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 switching power supply to enter a CCM or DCM operating mode by controlling the state of the power switch based on a first clock signal, and to control the switching power supply to enter a QR operating mode by controlling the state of the power switch based on a second clock signal.

[0072] For the introduction related to this embodiment, one may refer to the embodiment corresponding to the operation mode control method of the switching power supply, and thus 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, further comprising: a rectification and filtering module for converting an input AC current to a DC current and outputting the filtered DC current to a primary side of a transformer; A transformer; An output module is installed between the secondary side of the transformer and a load, and is used to generate a voltage according to a voltage on the secondary side of the transformer, and two voltage values ​​of each output voltage are 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.

[0074] The switching power supply of the present application may be a switching power supply with a relatively wide voltage output range, which can select the most suitable operation mode according to the demands of different output voltages. Referring to Fig. 7, Fig. 7 is a circuit diagram of the switching power supply provided by the present invention. The switching power supply in Fig. 7 is a flyback type switching power supply, and the switching power supply is operated in different operation modes by controlling the conduction state of the power switch by the control device of the switching power supply, so that the operation performance of the switching power supply is guaranteed. For an introduction of the switching power supply provided by the present application, please refer to the embodiment of the control method of the switching power supply described above, and not much will be described here.

[0075] Each embodiment of this specification is described in a stepwise manner, but the key points of each embodiment are different from other embodiments, and the same or similar parts between the embodiments can be referred to each other. The apparatus disclosed in the embodiments corresponds to the method disclosed in the embodiments and is described relatively simply, so that the relevant parts can be referred to the method part description.

[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 entity or operation, and do not necessarily require or imply any substantial relationship or sequence between the entities or operations. Also, the terms "comprise", "comprises", or any other variation thereof cover non-exclusive inclusions, such that a process, method, article, or equipment that includes a set of elements includes not only those elements, but also other elements not expressly listed or inherent to that type of process, method, article, or equipment. Unless more restrictive, an element defined by the phrase "comprises a..." does not exclude the presence of additional identical elements in the process, method, article, or equipment that includes the said element.

[0077] The above description of the disclosed embodiments enables one skilled in the art to realize 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 limited to these embodiments shown herein, but should be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. 1. A method for controlling an operation mode of 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 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, 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. A method for controlling the operating mode of a switching power supply.

2. After determining whether the output voltage of the switching power supply is less than a first predetermined voltage threshold, If the load of the switching power supply meets a predetermined light load condition, the method further comprises controlling the switching power supply to enter a DCM operation mode.

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

3. After determining whether the output voltage of the switching power supply is less than a first predetermined voltage threshold, If not, 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.

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

4. Controlling the switching power supply to enter a CCM, DCM, or QR operating mode based on an input line voltage of the switching power supply; If the input line voltage is greater than a second predetermined voltage threshold, controlling the switching power supply to enter the QR mode of operation; and controlling the switching power supply to enter the CCM or DCM operation mode when the input line voltage is below the second predetermined voltage threshold.

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

5. Controlling the switching power supply to enter a CCM, DCM, or QR operating mode based on an input line voltage of the switching power supply; and controlling the switching power supply to enter the QR operation mode within a full voltage range of the input line voltage.

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

6. a mode control module for generating a first clock signal when an 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, and for generating a second clock signal based on an input line voltage of the switching power supply when the output voltage is not less than the first predetermined voltage threshold and the load meets the predetermined heavy load condition; and a power switch control module for controlling the state of a 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, and for controlling the state of the power switch based on the second clock signal to control the switching power supply to enter a CCM, DCM, or QR operation mode. The operating mode control circuit of a switching power supply.

7. the mode control module includes a clock output selector, a first clock module, and a second clock module; an output end of the first clock module and an output end of the second clock module are respectively connected to a first clock input end and a second clock input end of the clock output selector, and an output end of the clock output selector is an output end 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 a primary resonant waveform of the switching power supply when the number of bottoms of the primary resonant waveform is below a predetermined bottom number threshold, and to generate a second clock signal whose frequency is positively correlated with the magnitude of the load when the number of bottoms of the primary resonant waveform is greater than a predetermined bottom 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 lower than the first predetermined voltage threshold and the load meets the predetermined heavy load condition, and to output a 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.

7. The operating mode control circuit of a switching power supply according to claim 6.

8. the second clock module includes a second clock sub-module, a bottom clock module, and a second clock output selector; an output end of the second clock sub-module and an output end of the bottom clock module are respectively connected to a first input end and a second input end of the second clock output selector, and an output end of the second clock output selector is connected to a second clock input end of the clock output selector; The second clock sub-module is used to generate a second clock sub-signal when the number of bottoms of the primary resonant waveform of the switching power supply is greater than a predetermined bottom number threshold, the frequency of the second clock sub-signal and the number of bottoms of the primary resonant waveform are negatively correlated, and the number of bottoms of the primary resonant waveform and the magnitude of the load are negatively correlated; The bottom lock module is used to control the primary resonant waveform to develop in a bottom portion of the number of bottoms when the number of bottoms of the primary resonant waveform does not exceed the predetermined bottom number threshold, and the primary resonant waveform developed in the bottom portion of the number of bottoms is a second clock bottom signal; the second clock output selector is used to output the second clock bottom signal generated by the bottom lock module to the clock output selector as the second clock signal when the bottom number of the primary resonant waveform is greater than the predetermined bottom 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 bottom number of the primary resonant waveform does not exceed the predetermined bottom number threshold.

8. The operating mode control circuit of a switching power supply according to claim 7.

9. 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 a second input terminal of the AND gate, an output terminal of the AND gate is connected to an input terminal of the driving circuit, and an output terminal of the driving circuit is connected to a control terminal of the power switch as an 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.

7. The operating mode control circuit of a switching power supply according to claim 6.

10. 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 to control the switching power supply to enter a DCM operation mode.

7. The operating mode control circuit of a switching power supply according to claim 6.

11. 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 state of the power switch according to the fourth clock signal to control the switching power supply to enter a DCM operation mode.

7. The operating mode control circuit of a switching power supply according to claim 6.

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

12. The operation mode control circuit of the switching power supply according to claim 6.

13. The mode control module is specifically used for generating 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 for generating the second clock signal when the output voltage is not less than the first predetermined voltage threshold, 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 switching power supply to enter a CCM or DCM operation mode by controlling the state of the power switch based on the first clock signal, and to control the switching power supply to enter a QR operation mode by controlling the state of the power switch based on the second clock signal.

12. The operation mode control circuit of the switching power supply according to claim 6.

14. The switching power supply includes an operation mode control circuit according to any one of claims 6 to 13, and further includes: a rectifying and filtering module for converting an input AC current to 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 a voltage on the secondary side of the transformer, and two voltage values ​​of each of the output voltages are different from each other; a power switch having a control end connected to an output end of the control device of the switching power supply; Switching power supply.

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