Feedback control circuit, control method and switching power supply using feedback control circuit

Abstract

According to the feedback control circuit, the control method and the switching power supply applying the feedback control circuit, a secondary side controller serves as a main controller, and a current generation and mirror image module and a control signal generation module are arranged in the secondary side controller; the current generation and mirroring module generates a first current based on the output voltage or the signal representing the output voltage and the first voltage signal, and mirrors the first current into a second current; the control signal generation module generates a control signal based on the second current; and the secondary side controller realizes feedback control of the loop based on the control signal. Through the arrangement, an optocoupler is not needed, the current mirror image module can be compatible with an existing peripheral circuit structure, the structure is simple, and the transmission delay of the current mirror image module is far smaller than that of the optocoupler, so that unnecessary poles can be reduced, and a corresponding compensation network structure can be simplified; and the current mirror image module has better current and temperature stability and smaller temperature excursion, so that the light attenuation effect of an optocoupler can be avoided, and the service life of the current mirror image module is longer.

Description

Technical Field

[0001] The present invention relates to the technical field of power electronics, and in particular to a feedback control circuit, a control method and a switching power supply using the same. Background Art

[0002] Figure 1 The figure shows an isolated switching power supply in the prior art, in which the main controller is arranged on the primary side, that is, the primary side controller is used as the main controller, and an error amplifier is arranged on the secondary side. The error amplifier generates an error signal Vopto based on the feedback signal Vfb of the output voltage. The error signal is transmitted to the primary side controller through the photoelectric coupling module U1, and a control signal Vctrl is generated on the primary side. Based on the control signal, corresponding feedback control is implemented. Figure 1 As shown in , the error amplifier can use the commonly used voltage regulator TL431, such as Figure 2 FIG. 1 is a schematic diagram of using TL431 as an error amplifier; when the switching power supply is used in an adapter or a charger, the error amplifier can also be integrated in a protocol chip (wherein a pin can be provided in the protocol chip to receive the output voltage of the switching power supply, such as Figure 1 Of course, other types of error amplifiers can also be used. Figure 1 As shown in , a first compensation network Z1 and a second compensation network Z2 are also provided, and the corresponding compensation networks are provided to improve the performance of the system loop operation. However, due to the nonlinear characteristics of the current transfer ratio CTR of the optocoupler, which will decay with temperature, working time, etc., for example, when a high power density power supply works in a high temperature environment for a long time, the decay of the current transfer ratio will affect the stability of the system, so that sufficient derating design margin needs to be considered in the early setting; in addition, the forward current of the optocoupler must be within a very good linear range, and the current transfer ratio CTR is a relatively stable value, that is, the optocoupler gain changes with the change of the DC operating point, and its change is large; and the transmission characteristics of the optocoupler are also relatively slow. Compared with the closed-loop system, it is similar to a pole network, which will cause the loop response to slow down further, and reduce the transient response of the system. Therefore, it is necessary to propose a new solution to solve the problems existing in the prior art. Summary of the invention

[0003] In order to solve the above technical problems, the present invention provides a feedback control circuit, a control method and a switching power supply using the same.

[0004] According to a first aspect of the present invention, a feedback control circuit is provided, which is applied to a switching power supply, wherein the switching power supply comprises a secondary controller arranged in a secondary winding, and is characterized in that the feedback control circuit comprises:

[0005] An error amplifier, which obtains an error signal according to a feedback signal of the output voltage of the switching power supply;

[0006] a current generation and mirroring module, generating a first current according to the output voltage and a first voltage signal, or generating a first current according to a signal representing the output voltage and the first voltage signal, and mirroring the first current into a second current; the first voltage signal is obtained from the error signal;

[0007] a control signal generating module, generating a control signal according to the second current;

[0008] Wherein, the current generation and mirror module and the control signal generation module are arranged in the secondary side controller; and the secondary side controller implements feedback control of the loop according to the control signal.

[0009] Optionally, the first current is related to the magnitude of the output voltage and the first voltage signal, or is related to the magnitude of the signal characterizing the output voltage and the first voltage signal. When the difference between the output voltage and the first voltage signal is larger, or the difference between the signal characterizing the output voltage and the first voltage signal is larger, the first current is larger.

[0010] Optionally, the control signal is negatively correlated with the second current, and the larger the second current is, the smaller the control signal is.

[0011] Optionally, the current generation and mirroring module includes a first resistor, a second resistor, an operational amplifier unit, and a first transistor; the first ends of the first resistor and the second resistor are connected to the output voltage or a signal representing the output voltage, and the second end of the first resistor is connected to the first input end of the operational amplifier unit; the second end of the second resistor is connected to the first voltage signal and the second input end of the operational amplifier unit; the output end of the operational amplifier unit is connected to the control end of the first transistor;

[0012] The first resistor and the second resistor are matched so that the current flowing through the first resistor is equal to the current flowing through the second resistor; the current flowing through the first transistor is the first current, and is equal to the current flowing through the first resistor.

[0013] Optionally, the control signal generating module includes a pull-up resistor, and the control signal is a difference between a power supply voltage and a voltage applied to the pull-up resistor by the second current; the power supply voltage is generated by an internal circuit of the secondary-side controller.

[0014] Optionally, the error amplifier has a first input terminal and a first output terminal, the first input terminal is used to receive a feedback signal of the output voltage, and the error signal is output at the first output terminal.

[0015] Optionally, a second compensation network is provided between the first input terminal and the first output terminal.

[0016] Optionally, the error signal outputs a first voltage signal after passing through a first compensation network, and the first resistor and the second resistor are configured to be much smaller than an impedance of the first compensation network.

[0017] Optionally, the feedback control circuit further includes a voltage divider network, which is used to sample the output voltage to obtain a feedback signal of the output voltage.

[0018] Optionally, at least one of the error amplifier, the second compensation network and the voltage divider network is integrated into the secondary-side controller.

[0019] Optionally, the error signal outputs a first voltage signal after passing through a first compensation network, or the first voltage signal is the error signal.

[0020] The present invention also provides a switching power supply, which includes a transformer, a primary switch tube, a synchronous rectifier, a primary controller, and a secondary controller; the primary controller controls the on or off of the primary switch tube; the secondary controller controls the on or off of the synchronous rectifier; and the switching power supply also includes the feedback control circuit described above.

[0021] The present invention further provides a feedback control method, which is applied to a switching power supply, wherein the switching power supply includes a secondary controller arranged in a secondary winding, and is characterized in that the feedback control method includes:

[0022] Obtaining an error signal according to a feedback signal of the output voltage of the switching power supply;

[0023] generating a first current according to the output voltage and a first voltage signal, or generating a first current according to a signal representing the output voltage and the first voltage signal, and mirroring the first current into a second current; the first voltage signal is obtained from the error signal;

[0024] generating a control signal according to the second current;

[0025] The module for generating the first current and the second current and the module for generating the control signal are arranged in the secondary side controller; and the secondary side controller implements feedback control of the loop according to the control signal.

[0026] Optionally, the error signal is output by an error amplifier, the error amplifier has a first input terminal and a first output terminal, the first input terminal is used to receive a feedback signal of the output voltage, and the error signal is output at the first output terminal;

[0027] A second compensation network is provided between the first input terminal and the first output terminal.

[0028] Optionally, the feedback control circuit further includes a voltage divider network, which is used to sample the output voltage to obtain a feedback signal of the output voltage;

[0029] At least one of the error amplifier, the second compensation network and the voltage divider network is integrated in the secondary-side controller.

[0030] Optionally, the error signal outputs a first voltage signal after passing through a first compensation network, or the first voltage signal is the error signal.

[0031] The beneficial effects of the present invention include at least:

[0032] The present invention provides a feedback control circuit, a control method and a switching power supply using the same, wherein a secondary controller is used as a main controller, and a current generation and mirroring module and a control signal generation module are provided in the secondary controller; the current generation and mirroring module generates a first current based on an output voltage and a first voltage signal, or generates a first current based on a signal representing the output voltage and a first voltage signal, and mirrors the first current into a second current; the control signal generation module generates a control signal based on the second current; and the secondary controller implements feedback control of the loop based on the control signal. Through the above-mentioned setting, the present invention can eliminate the need for a photoelectric coupler, and can be compatible with the peripheral circuit structure in the prior art, the structure is simple and easy to implement, and relative to the setting of the photoelectric coupler, the current mirroring module used in the present invention has a transmission delay much smaller than the transmission delay of the photoelectric coupler, therefore, unnecessary poles can be reduced, and the corresponding compensation network structure can be simplified; and the current mirroring module has better current stability and temperature stability, smaller temperature drift, can avoid the light decay effect of the photoelectric coupler, and has a longer service life.

[0033] It should be noted that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 A schematic diagram of an isolated switching power supply in the prior art is shown;

[0035] Figure 2 A schematic diagram using TL431 as an error amplifier is shown;

[0036] Figure 3 A schematic diagram of a feedback control circuit provided by the present invention is shown;

[0037] Figure 4 A specific schematic diagram of the current generation and mirror module and the control signal generation module provided by the present invention is shown;

[0038] Figure 5 A schematic diagram of a switching power supply provided by the present invention is shown;

[0039] Figure 6 A schematic diagram of another switching power supply provided by the present invention is shown;

[0040] Figure 7 A schematic diagram of another switching power supply provided by the present invention is shown;

[0041] Figure 8 A schematic diagram of another switching power supply provided by the present invention is shown. DETAILED DESCRIPTION

[0042] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present invention are shown in the drawings. However, the present invention can be implemented in different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0043] This article provides a feedback control circuit, which is applied to a switching power supply, the switching power supply includes a transformer, a primary switch tube, a synchronous rectifier, a primary controller, and a secondary controller; the primary controller controls the on or off of the primary switch tube; the secondary controller controls the on or off of the synchronous rectifier. Figure 1 The difference is that in the switching power supply provided in this article, a secondary side controller is used as the main controller, and feedback control of the loop can be achieved without an optocoupler. Specifically, the feedback control circuit includes an error amplifier, a current generation and mirroring module, and a control signal generating module. The error amplifier is used to obtain an error signal according to a feedback signal of the output voltage of the switching power supply. The current generation and mirroring module is used to generate a first current according to the output voltage and a first voltage signal, or to generate a first current according to a signal representing the output voltage and a first voltage signal, and mirror the first current to a second current; wherein the first voltage signal is obtained from the error signal. The control signal generating module is used to generate a control signal according to the second current. Among them, the current generation and mirroring module and the control signal generating module are arranged in the secondary side controller; the secondary side controller implements corresponding feedback control (for example, for controlling the operating frequency of the system, etc.) according to the control signal.

[0044] The following is a further introduction to this article with the help of a specific circuit diagram. Figure 3 A schematic diagram of a feedback control circuit provided by the present invention, in which a voltage divider network is used to sample the output voltage to obtain a feedback signal Vfb of the output voltage. Figure 3 The peripheral circuits in the prior art can be Figure 1 , Figure 2 The voltage divider network and error amplifier can be the same as Figure 1 , Figure 2 The method in the embodiment is, of course, not limited to this, and other forms may also be used; in this embodiment, the current generation and mirroring module 10 generates a first current I1 based on the output voltage Vout and the first voltage signal Vcomp, and generates a second current I2 by current mirroring. The ratio of the first current I1 to the second current I2 is 1:K, where the value of K can be set according to the actual application. The control signal generating module 20 includes a pull-up resistor Rpull, one end of which is connected to the power supply voltage VA, and the power supply voltage VA is generated by the internal circuit of the secondary side controller. The second current I2 acts on the pull-up resistor Rpull, and the control signal Vctrl is the difference between the power supply voltage VA and the voltage of the second current I2 acting on the pull-up resistor Rpull. Figure 3 In the embodiment, a capacitor C1 is also provided at the node outputting the control signal Vctrl, which has a filtering function; of course, whether to provide the capacitor C1 can be set according to the actual application. Figure 3 It can be seen that the magnitude of the control signal Vctrl is related to the magnitude of the second current, the second current is obtained by mirroring the first current, and the magnitude of the first current is related to the output voltage Vout and the first voltage signal Vcomp, that is, the magnitude of the control signal Vctrl is related to the output voltage Vout and the first voltage signal Vcomp.

[0045] Further, Figure 4The figure shows a specific schematic diagram of the current generation and mirror module and the control signal generation module. The current generation and mirror module 10 includes a first resistor Rcomp1, a second resistor Rcomp2, an operational amplifier unit U2, and a first transistor M1. The first ends of the first resistor Rcomp1 and the second resistor Rcomp2 are connected to the output voltage Vout, and the second end of the first resistor Rcomp1 is connected to the first input end of the operational amplifier unit U2. The second end of the second resistor Rcomp2 is connected to the first voltage signal Vcomp and the second input end of the operational amplifier unit U2. The output end of the operational amplifier unit U2 is connected to the control end of the first transistor M1. The first resistor Rcomp1 and the second resistor Rcomp2 match, that is, the two resistors use the same type of resistors and have the same resistance value. Therefore, according to the working characteristics of the operational amplifier, it can be seen that the current flowing through the first resistor Rcomp1 is equal to the current flowing through the second resistor Rcomp2 (which can be regarded as the first current). The magnitude of the current value depends on the magnitude of the output voltage Vout and the first voltage signal Vcomp. At the same time, the current flowing through the first transistor M1 is also equal to the current flowing through the first resistor (that is, the first current). Afterwards, through the action of the current mirror, Figure 4 In the embodiment, the second transistor M2 and the second transistor M3 form a current mirror structure, which is used to mirror the first current into the second current, that is, the current flowing through the third transistor M3 is the second current, and the ratio of the two currents is determined by the parameters of the second transistor M2 and the second transistor M3; then the control signal Vctrl is the difference between the power supply voltage VA and the voltage on the pull-up resistor Rpull (that is, Vctrl = VA-I2*Rpull = VA-I1*K*Rpull). Since the magnitude of the first current I1 is related to the output voltage Vout and the first voltage signal Vcomp, the control signal Vctrl is also related to the output voltage Vout and the first voltage signal Vcomp, and the magnitude of Vctrl is determined by these two signals; the internal circuit module in the secondary side controller performs corresponding feedback control on the loop based on the control signal Vctrl; that is, the entire feedback control can be completed on the secondary side, and compared with the prior art, it is not necessary to set up modules such as optocouplers to transmit the corresponding feedback signal to the primary side controller to realize the feedback control of the loop.

[0046] Further, based on Figure 3 , Figure 4 The structure of Figure 3 The peripheral circuits in the Figure 2 For the same structure, the transfer function of Vctrl / Vout can be derived as: Vctrl / Vout=(K*Rpull*(RA+Z2)) / ((Z1+Rcomp)*RA); where Rcomp=Rcomp1=Rcomp2. Figure 2In the structure, the transfer function of Vctrl / Vout can be derived as: Vctrl / Vout = (CTR*Rpull*(RA+Z2)) / (Z1*RA); therefore, by comparing the two formulas, it can be seen that the resistance value of Rcomp can be set much smaller than the impedance of the first impedance network Z1, so that the two transfer functions have basically the same form, and thus can have the same loop working performance. Of course, the present invention is not limited to this. When the loop has other design requirements, the value of Rcomp can also be set accordingly according to the actual application situation.

[0047] It should be noted that Figure 3 and Figure 4 The medium current generation and mirror module and the control signal generation module are only examples of the present invention, and the present invention is not limited thereto, and corresponding modifications may be made thereto to achieve the same function.

[0048] Therefore, through the above-mentioned setting of this article, the present invention uses the secondary side controller as the main controller, and the secondary side controller realizes the feedback control of the loop based on the output voltage and the first voltage signal, and can eliminate the need for a photoelectric coupler, and can be compatible with the peripheral circuit structure in the prior art, and has a simple structure. Compared with the setting of the photoelectric coupler, the technical solution in the present invention can reduce unnecessary poles, and it is unnecessary to add additional compensation zeros, so that the structure of the first compensation network Z1 can be simplified, and it is even unnecessary to set the first compensation network Z1 (in Figure 3 In the figure, the first compensation network Z1 is indicated by a dotted box); in addition, the current mirror circuit has better current stability signal and temperature stability, smaller temperature drift, and no light decay effect of the optocoupler, which can improve the working life of the system.

[0049] Further, Figure 5The schematic diagram of a switching power supply provided by the present invention includes the feedback control circuit described above. In this embodiment, the error amplifier, the voltage divider network, the first compensation network Z1 and the second compensation network Z2 are all arranged outside the secondary controller, which is the same as the peripheral circuit in the prior art. The secondary controller is provided with a first pin and a second pin, the first pin is used to receive the output voltage Vout of the switching power supply, and the second pin is used to receive the first voltage signal Vcomp; the current generation and mirror module 10 and the control signal generation module 20 are arranged in the secondary controller; the current generation and mirror module 10 receives the output voltage Vout and the first voltage signal Vcomp, and generates the first current I1 according to these two signals, and mirrors the first current into the second current I2; the control signal generation module 20 generates the control signal Vctrl according to the second current I2; other circuits (not shown in the figure) are also arranged inside the secondary controller for realizing corresponding feedback control according to the control signal Vctrl. The first voltage signal Vcomp is generated based on the error signal Vopto generated by the error amplifier, and the error amplifier can be used Figure 1 The structure shown in the figure, that is, TL431 can be used as the error amplifier, or the error amplifier can be set in the protocol chip, or the error amplifier can be set in other ways according to the actual application. Similarly, the present invention can also set a first compensation network Z1 and a second compensation network Z2 to improve the performance of the loop operation; the error amplifier has a first input terminal and a first output terminal; the first input terminal is used to receive the feedback signal Vfb of the output voltage, and output the error signal Vopto at the first output terminal; a second compensation network Z2 is set between the first input terminal and the first output terminal; the error signal Vopto can output the first voltage signal Vcomp after passing through the first compensation network Z1, or as mentioned above, the first compensation network Z1 can be simplified or not set, and the error signal Vopto can be directly used as the first voltage signal Vcomp.

[0050] Of course, except Figure 5 In addition to the structure shown in FIG, at least one of the error amplifier, the voltage divider network, the first compensation network Z1 (the first compensation network may not be provided) and the second compensation network Z2 may be provided inside the secondary side controller. Specifically, Figure 6 A schematic diagram of another switching power supply provided by the present invention, the switching power supply also includes the feedback control circuit described above, and Figure 5The difference is that the error amplifier is set inside the secondary controller, and the voltage divider network, the first compensation network Z1 and the second compensation network Z2 are set outside the secondary controller, which can also achieve the functions described above. The specific working principle can be found in the above description and will not be repeated here. In this embodiment, of course, the first compensation network Z1 may not be set, in which case the number of peripheral pins of the secondary controller can be reduced.

[0051] Further, Figure 7 Schematic diagram of another switching power supply provided by the present invention. In this embodiment, the error amplifier, the first compensation network Z1 and the second compensation network Z2 are all arranged inside the secondary side controller, and the voltage divider network is arranged outside the secondary side controller. Figure 6 The settings in can reduce the number of peripheral pins of the secondary side controller.

[0052] Further, Figure 8 This is a schematic diagram of another switching power supply provided by the present invention. In this embodiment, the error amplifier, the voltage divider network, the first compensation network Z1 and the second compensation network Z2 are all arranged inside the secondary side controller, that is, all are integrated in the secondary side controller. At this time, the number of peripheral pins of the secondary side controller can be relatively smaller.

[0053] It should be noted that Figure 5-Figure 8 This is only a part of the embodiments of this article, and it is also within the scope of this article to make corresponding modifications to achieve the same function. In addition, in the above-mentioned embodiment, the first current I1 is generated based on the output voltage Vout and the first voltage signal Vcomp. In other embodiments, it can also be generated based on the signal representing the output voltage Vout and the first voltage signal Vcomp.

[0054] This article also provides a feedback control method, which is applied to the switching power supply described above, and the switching power supply includes a secondary controller arranged in the secondary winding. The feedback control method includes obtaining an error signal according to a feedback signal of the output voltage of the switching power supply; generating a first current according to the output voltage and a first voltage signal, or generating a first current according to a signal representing the output voltage and the first voltage signal, and mirroring the first current into a second current; the first voltage signal is obtained from the error signal; a control signal is generated according to the second current; wherein a module for generating the first current and the second current and a module for generating the control signal are arranged in the secondary controller; and the secondary controller implements feedback control of the loop according to the control signal.

[0055] Furthermore, the feedback control method includes the functions of the above feedback control circuit, which can be found above for details and will not be repeated here.

[0056] In summary, the feedback control circuit, control method and switching power supply using the same provided in this article use the secondary controller as the main controller, and a current generation and mirroring module and a control signal generating module are provided in the secondary controller; the current generation and mirroring module generates a first current based on the output voltage and the first voltage signal, or generates a first current based on the signal representing the output voltage and the first voltage signal, and mirrors the first current into a second current; the control signal generating module generates a control signal based on the second current; the secondary controller implements feedback control of the loop based on the control signal. Through the above-mentioned setting, the present invention can eliminate the need for a photoelectric coupler, and can be compatible with the peripheral circuit structure in the prior art, the structure is simple and easy to implement, and relative to the setting of the photoelectric coupler, the current mirroring module used in the present invention has a transmission delay much smaller than the transmission delay of the photoelectric coupler, therefore, it can reduce unnecessary poles, and further simplify the corresponding compensation network structure; and the current mirroring module has better current stability and temperature stability, smaller temperature drift, can avoid the light decay effect of the photoelectric coupler, and has a longer service life.

[0057] Finally, it should be noted that: Obviously, the above embodiments are only examples for clearly explaining the present invention, and are not intended to limit the implementation methods. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from this are still within the scope of protection of the present invention.

Claims

1. A feedback control circuit, applied to a switching power supply, wherein the switching power supply comprises a secondary controller arranged in a secondary winding, characterized in that: The feedback control circuit comprises: An error amplifier, which obtains an error signal according to a feedback signal of the output voltage of the switching power supply; a current generation and mirroring module, generating a first current according to the output voltage and a first voltage signal, or generating a first current according to a signal representing the output voltage and the first voltage signal, and mirroring the first current into a second current; the first voltage signal is obtained from the error signal; a control signal generating module, generating a control signal according to the second current; Wherein, the current generation and mirror module and the control signal generation module are arranged in the secondary side controller; and the secondary side controller implements feedback control of the loop according to the control signal.

2. The feedback control circuit according to claim 1, characterized in that: The first current is related to the magnitude of the output voltage and the first voltage signal, or is related to the magnitude of the signal representing the output voltage and the first voltage signal. When the difference between the output voltage and the first voltage signal is larger, or the difference between the signal representing the output voltage and the first voltage signal is larger, the first current is larger.

3. The feedback control circuit according to claim 2, characterized in that: The control signal is negatively correlated with the second current. When the second current is larger, the control signal is smaller.

4. The feedback control circuit according to claim 1, characterized in that: The current generation and mirroring module includes a first resistor, a second resistor, an operational amplifier unit, and a first transistor; the first ends of the first resistor and the second resistor are connected to the output voltage or a signal representing the output voltage, and the second end of the first resistor is connected to the first input end of the operational amplifier unit; the second end of the second resistor is connected to the first voltage signal and the second input end of the operational amplifier unit; the output end of the operational amplifier unit is connected to the control end of the first transistor; The first resistor and the second resistor are matched so that the current flowing through the first resistor is equal to the current flowing through the second resistor; the current flowing through the first transistor is the first current, and is equal to the current flowing through the first resistor.

5. The feedback control circuit according to claim 4, characterized in that: The control signal generating module includes a pull-up resistor, and the control signal is the difference between a power supply voltage and a voltage applied to the pull-up resistor by the second current; the power supply voltage is generated by an internal circuit of the secondary side controller.

6. The feedback control circuit according to claim 5, characterized in that: The error amplifier has a first input terminal and a first output terminal, the first input terminal is used to receive a feedback signal of the output voltage, and the error signal is output at the first output terminal.

7. The feedback control circuit according to claim 6, characterized in that: A second compensation network is provided between the first input terminal and the first output terminal.

8. The feedback control circuit according to claim 7, characterized in that: The error signal outputs a first voltage signal after passing through a first compensation network, and the first resistor and the second resistor are configured to be much smaller than the impedance of the first compensation network.

9. The feedback control circuit according to claim 7, characterized in that: The feedback control circuit further includes a voltage divider network, which is used to sample the output voltage to obtain a feedback signal of the output voltage.

10. The feedback control circuit according to claim 9, characterized in that: At least one of the error amplifier, the second compensation network and the voltage divider network is integrated in the secondary-side controller.

11. The feedback control circuit according to any one of claims 1 to 10, characterized in that: The error signal outputs a first voltage signal after passing through a first compensation network, or the first voltage signal is the error signal.

12. A switching power supply, comprising a transformer, a primary switch tube, a synchronous rectifier, a primary controller, and a secondary controller; the primary controller controls the on or off of the primary switch tube; the secondary controller controls the on or off of the synchronous rectifier; characterized in that: The switching power supply further comprises a feedback control circuit as claimed in any one of claims 1 to 11.

13. A feedback control method, applied to a switching power supply, wherein the switching power supply comprises a secondary controller arranged in a secondary winding, characterized in that: The feedback control method comprises: Obtaining an error signal according to a feedback signal of the output voltage of the switching power supply; generating a first current according to the output voltage and a first voltage signal, or generating a first current according to a signal representing the output voltage and the first voltage signal, and mirroring the first current into a second current; the first voltage signal is obtained from the error signal; generating a control signal according to the second current; Wherein, the module for generating the first current and the second current and the module for generating the control signal are arranged in the secondary side controller; The secondary-side controller implements feedback control of the loop according to the control signal.

14. The feedback control method according to claim 13, characterized in that: The error signal is output by an error amplifier, the error amplifier having a first input terminal and a first output terminal, the first input terminal being used to receive a feedback signal of the output voltage, and the error signal being output at the first output terminal; A second compensation network is provided between the first input terminal and the first output terminal.

15. The feedback control method according to claim 14, characterized in that: The feedback control circuit further comprises a voltage divider network, which is used to sample the output voltage to obtain a feedback signal of the output voltage; At least one of the error amplifier, the second compensation network and the voltage divider network is integrated in the secondary-side controller.

16. The feedback control method according to any one of claims 13 to 15, characterized in that: The error signal outputs a first voltage signal after passing through a first compensation network, or the first voltage signal is the error signal.

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