Loop compensation circuit applied to two-stage LC switching power supply and switching power supply device

Abstract

The application belongs to the field of switching power supply, and provides a loop compensation circuit applied to a two-stage LC switching power supply. The loop compensation circuit comprises a first feedback module, a second feedback module, a sampling module and a feedback adjustment module. The first feedback module and the second feedback module generate a second feedback signal according to the output voltage of a two-stage filter module and a one-stage filter module. The sampling module samples the current at the output end of a switching module to obtain a sampling current signal. The feedback adjustment module is connected to the second feedback module and the sampling module, and is used to generate a pulse width modulation signal according to the sampling current signal and the second feedback signal to adjust the switching frequency of the switching module. In the application, the loop compensation circuit feeds back the output current of the switching module, the output voltage of the one-stage filter module and the output voltage of the two-stage filter module, thereby solving the problem that the loop compensation circuit cannot perform loop compensation on the one-stage filter module and the two-stage filter module.

Description

Technical Field

[0001] This application belongs to the field of switching power supplies, and particularly relates to a loop compensation circuit and switching power supply device applied to a two-stage LC switching power supply. Background Technology

[0002] Switching power supplies are the most fundamental components of modern electronic circuit systems. They transform a known DC input voltage into a DC output voltage required by the system or that is easy to use. When dealing with ripple-sensitive digital, analog, and RF applications, the use of a two-stage LC switching power supply to directly power the load improves system efficiency, making low-ripple performance of the output voltage crucial.

[0003] However, existing two-stage LC switching power supplies have the problem of not being able to simultaneously perform loop compensation for both the single-stage and two-stage LC filter circuits. Summary of the Invention

[0004] The purpose of this application is to provide a loop compensation circuit and switching power supply device for a two-stage LC switching power supply, which aims to solve the problem that existing two-stage LC switching power supplies cannot simultaneously perform loop compensation for a single-stage LC filter circuit and a two-stage LC filter circuit.

[0005] This application provides a loop compensation circuit for a two-stage LC switching power supply, wherein the two-stage LC switching power supply includes a switching module, a first-stage filtering module, and a second-stage filtering module connected in sequence, characterized in that the loop compensation circuit includes:

[0006] The first feedback module is connected to the second-level filter module and is used to sample the output voltage of the second-level filter module to obtain a first sampled voltage signal, and amplify the voltage difference between the first sampled voltage signal and the first reference voltage to generate a first feedback signal.

[0007] The second feedback module is connected to the first feedback module and the first-stage filter module. It is used to sample the output voltage of the first-stage filter module to obtain a second sampled voltage signal, and amplify the voltage difference between the second sampled voltage signal and the first feedback signal to generate a second feedback signal.

[0008] A sampling module, connected to the switching module, is used to sample the current at the output terminal of the switching module to obtain a sampling current signal;

[0009] The feedback adjustment module, connected to the second feedback module and the sampling module, is used to generate a pulse width modulation signal based on the sampled current signal, the second feedback signal, and the ramp compensation signal, so as to adjust the switching frequency of the switching module.

[0010] In one embodiment, the first feedback module includes a first voltage sampling unit and a first error amplification unit; wherein...

[0011] The first voltage sampling unit is connected to both ends of the second-stage filtering module, the first input terminal of the first error amplification unit is connected to the output terminal of the first voltage sampling unit, and the second input terminal of the first error amplification unit is connected to the sampling module.

[0012] In one embodiment, the first voltage sampling unit includes a first resistor and a second resistor; wherein...

[0013] The first end of the first resistor is connected to the first end of the secondary filter module, the second end of the first resistor is connected to the first end of the second resistor, the second end of the second resistor is connected to the second end of the secondary filter module, and the second end of the first resistor and the first end of the second resistor jointly output the first sampling voltage signal.

[0014] In one embodiment, the first error amplification unit includes a first error amplifier and a first capacitor; wherein...

[0015] The negative input of the first error amplifier is connected to the first voltage sampling unit, the positive input of the first error amplifier receives the reference voltage, and the output of the first error amplifier is connected to the second feedback module; the first end of the first capacitor is connected to the output of the first error amplifier, and the second end of the first capacitor is grounded.

[0016] In one embodiment, the second feedback module includes a second voltage sampling unit and a second error amplification unit; wherein...

[0017] The second voltage sampling unit is connected to both ends of the first-stage filtering module, the first input terminal of the second error amplification unit is connected to the output terminal of the second voltage sampling unit, the second input terminal of the second error amplification unit is connected to the first feedback module, and the output terminal of the second error amplification unit is connected to the feedback adjustment module.

[0018] In one embodiment, the second voltage sampling unit includes a third resistor and a fourth resistor; wherein...

[0019] The first end of the third resistor is connected to the first end of the first-stage filter module, the second end of the fourth resistor is connected to the first end of the third resistor, the second end of the fourth resistor is connected to the second end of the first-stage filter module, and the second end of the third resistor and the first end of the fourth resistor jointly output the second sampling voltage signal.

[0020] In one embodiment, the second error amplification unit includes a second error amplifier, a fifth resistor, and a second capacitor; wherein...

[0021] The negative input of the second error amplifier is connected to the second voltage sampling unit, the positive input of the second error amplifier is connected to the first feedback module, and the output of the second error amplifier is connected to the feedback adjustment module; the first end of the fifth resistor is connected to the output of the second error amplifier, and the second end of the fifth resistor is grounded; the first end of the second capacitor is connected to the output of the second error amplifier, and the second end of the second capacitor is grounded.

[0022] In one embodiment, the feedback adjustment module includes a pulse width modulation comparator. The negative phase input of the pulse width modulation comparator is connected to the sampling module and receives the sampled current signal. The positive phase input of the pulse width modulation comparator is connected to the second feedback module and receives the second feedback signal. The ramp receiving terminal of the pulse width modulation comparator receives a ramp compensation signal. The output terminal of the pulse width modulation comparator is connected to the switching module.

[0023] In one embodiment, the sampling module includes a current sampling unit, the input of which is connected to the output of the switching module, and the output of which is connected to the feedback adjustment module.

[0024] In another aspect, this application provides a switching power supply device, which includes the loop compensation circuit described in any of the above embodiments.

[0025] The loop compensation circuit includes a first feedback module, a second feedback module, a sampling module, and a feedback adjustment module. The first feedback module is connected to the second-stage filter module and samples the output voltage of the second-stage filter module to obtain a first sampled voltage signal. It then amplifies the voltage difference between the first sampled voltage signal and a first reference voltage to generate a first feedback signal. The second feedback module is connected to the first feedback module and the first-stage filter module. It samples the output voltage of the first-stage filter module to obtain a second sampled voltage signal and amplifies the voltage difference between the second sampled voltage signal and the first feedback signal to generate a second feedback signal. The sampling module is connected to the switching module and samples the current at the output of the switching module to obtain a sampled current signal. The feedback adjustment module is connected to the second feedback module and the sampling module and generates a pulse width modulation signal based on the sampled current signal, the second feedback signal, and the ramp compensation signal to adjust the switching frequency of the switching module. In this application, the first and second feedback modules sample the voltages of the second-stage and first-stage filter modules, respectively, and output the samples to the feedback adjustment module to modulate the voltage of the switching module. This solves the problem that a two-stage LC switching power supply cannot simultaneously perform loop compensation on both the first-stage and two-stage LC filter circuits. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 Functional block diagram of a two-stage LC switching power supply provided in the embodiments of this application;

[0028] Figure 2 A schematic diagram of the circuit principle of the first feedback module provided in the embodiments of this application;

[0029] Figure 3 A schematic diagram of the circuit principle of the second feedback module provided in the embodiments of this application;

[0030] Figure 4 A schematic diagram of the circuit principle of the feedback adjustment module provided in the embodiments of this application;

[0031] Figure 5 A schematic diagram of the circuit principle of a two-stage LC switching power supply provided in an embodiment of this application. Detailed Implementation

[0032] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0033] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0034] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0035] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0036] Switching power supplies convert external power signals into the power supply signals required by the load. In order to make the power supply signal output by the switching power supply more stable, it is usually necessary to add an LC filter circuit. This gives the switching power supply a two-stage LC filter circuit on the basis of the original LC filter circuit. In a switching power supply with a two-stage LC filter circuit, the improved stability of the switching power supply is conducive to outputting a stable power supply signal.

[0037] Existing two-stage LC switching power supplies have a compensation loop. This loop only samples the power supply signal output from the two-stage LC filter circuits and compares it with a reference voltage signal. When there is a difference between the power supply signal and the reference voltage signal, the compensation loop controls the final power conversion module of the switching power supply to output the power supply signal required by the load. However, this loop compensation circuit cannot compare the output signal of the power conversion module with the output signal of the first-stage LC filter circuit. As a result, the loop compensation circuit cannot simultaneously compensate for both the first-stage and two-stage LC filter circuits to increase the stability of the two-stage LC switching power supply.

[0038] To address the aforementioned problems, this application provides a loop compensation circuit for a two-stage LC switching power supply, see [link to relevant documentation]. Figure 1As shown, the loop compensation circuit includes a first feedback module 100, a second feedback module 200, a sampling module 300, and a feedback adjustment module 400. The first feedback module 100 is connected to the second-stage filter module 700 and samples the output voltage of the second-stage filter module 700 to obtain a first sampled voltage signal. The difference between the first sampled voltage signal and the first reference voltage generates a first feedback signal V1, which is then output to the second feedback module 200. The second feedback module 200 is connected to the first feedback module 100 and the first-stage filter module 600. After sampling the output voltage of the first-stage filter module 600 to generate a second sampled voltage signal, the first-stage filter module 600 also receives the first feedback signal V1 and generates a second feedback signal V2 based on the difference between the second sampled voltage signal and the first feedback signal V1. The second feedback signal V2 is then output to the feedback adjustment module 400. The sampling module 300 is connected to the output terminal of the switching module 500 and is used to sample the current at the output terminal of the switching module 500 to generate a sampling current signal V3, and output the sampling current signal V3 to the feedback adjustment module 400. The feedback adjustment module 400 is connected to the second feedback module 200 and the sampling module 300, and is used to receive the second feedback signal V2 and the sampling current signal V3, and adjust the switching frequency of the switching module 500 according to the second feedback signal V2 and the sampling current signal V3, thereby adjusting the voltage of the output electrical signal of the switching module 500.

[0039] For details, please refer to [link / reference]. Figure 1 As shown, the secondary filter module 700 outputs a power supply signal to the load to supply power to the load. The first feedback module 100 samples the voltage across the secondary filter module 700 (i.e., the output voltage of the secondary filter module 700) to obtain a first sampled voltage signal. When the first sampled voltage signal is obtained, the first feedback module 100 compares the first sampled voltage signal with a first reference voltage and generates a first feedback signal V1 from the voltage difference between the power supply signal and the first reference voltage, thereby performing remote loop compensation for the two-stage LC switching power supply.

[0040] The first-stage filter module 600 outputs a second sampled voltage signal. The second feedback module 200 samples the voltage across the first-stage filter module 600 (i.e., the output voltage of the first-stage filter module 600) to obtain the second sampled voltage signal. The second feedback module 200 compares the second sampled voltage signal with the first feedback signal V1 and generates a second feedback signal V2 based on the voltage difference between the second sampled voltage signal and the first feedback signal V1, thereby performing loop compensation on the switching power supply.

[0041] The sampling module 300 is connected to the output terminal of the switching module 500. It is used to sample the current output by the switching module to generate a sampling current signal and output the sampling current signal V3 to the feedback adjustment module 400 to control the feedback adjustment module 400 to output a pulse width modulation signal Vc, thereby controlling the switching frequency of the switching module.

[0042] When the feedback adjustment module 400 receives the sampling current signal V3 output by the sampling module, it adjusts the duty cycle of its output based on the peak value of the output current waveform, thereby controlling the voltage value output by the switching module 500. When the feedback adjustment module 400 receives the second feedback signal V2 output by the second feedback module 200, it compensates for the insufficient performance of the closed-loop system of the switching power supply under disturbances, thereby maintaining the stability of the closed-loop system.

[0043] In this embodiment, the loop compensation circuit adopts current-controlled loop compensation. It adjusts the power supply signal output by the switching power supply through the voltage feedback of the first-stage filter module 600, the voltage feedback of the second-stage filter module 700, and the current feedback of the switching module 500. This stabilizes the power supply signal output by the switching power supply circuit at the voltage value required by the load. At the same time, the loop compensation circuit can also work normally without using the second-stage filter module 700. The loop compensation circuit solves the loop compensation problem of the two-stage LC switching power supply.

[0044] In one embodiment, see Figure 2 As shown, the first feedback module 100 includes a first voltage sampling unit 110 and a first error amplification unit 120. The first voltage sampling unit 110 is connected to both ends of the second-stage filtering module 700, the first input terminal of the first error amplification unit 120 is connected to the output terminal of the first voltage sampling unit 110, and the second input terminal of the first error amplification unit 120 is connected to the sampling module 200.

[0045] Specifically, the first voltage sampling unit 110 includes a first resistor R1 and a second resistor R2. The first end of the first resistor R1 is connected to the first end of the secondary filter module 700, the second end of the first resistor R1 is connected to the first end of the second resistor R2, and the second end of the second resistor R2 is connected to the second end of the secondary filter module 700. The second end of the first resistor R1 and the first end of the second resistor R2 jointly output the first sampling voltage signal.

[0046] The first error amplification unit 120 includes a first error amplifier gm1 and a first capacitor C1. The negative input of the first error amplifier gm1 is connected to the first voltage sampling unit 110, the positive input of the first error amplifier gm1 receives the first reference voltage Vref, and the output of the first error amplifier gm1 is connected to the second feedback module 200. The first terminal of the first capacitor C1 is connected to the output of the first error amplifier gm1, and the second terminal of the first capacitor C2 is grounded to GND.

[0047] In this embodiment, the first resistor R1 and the second resistor R2 sample the voltage across the second filter module 700 (i.e., the output voltage of the second filter module 700) to generate a first sampled voltage signal. The common terminal of the first resistor R1 and the second resistor R2 serves as the output terminal of the first sampled voltage signal, which is then output to the negative input of the first error amplifier gm1. The positive input of the first error amplifier gm1 receives the first reference voltage Vref, compares the first sampled voltage signal with the reference voltage signal Vref, and amplifies and outputs the first feedback signal V1. This performs remote loop compensation for the two-stage LC switching power supply, with the compensation value being:

[0048] F R =K R / s=1 / C3s

[0049] The first voltage sampling unit 110 and the first error amplification unit 120 sample the power supply signal output by the secondary filter module 700, and generate a first feedback signal V1 that can compensate the two-stage LC switching power supply based on the power supply signal, thereby adjusting the power supply signal output by the two-stage LC switching power supply.

[0050] In one embodiment, see Figure 3 As shown, the second feedback module 200 includes a second voltage sampling unit 210 and a second error amplification unit 220. The second voltage sampling unit 210 is connected to both ends of the first-stage filter module 700. The first input terminal of the second error amplification unit 220 is connected to the output terminal of the second voltage sampling unit 110. The second input terminal of the second error amplification unit 220 is connected to the first feedback module 100, and the output terminal of the second error amplification unit 220 is connected to the feedback adjustment module 400.

[0051] For details, please refer to [link / reference]. Figure 3 As shown, the second voltage sampling unit 210 includes a third resistor R3 and a fourth resistor R4; wherein, the first end of the third resistor R3 is connected to the first end of the first-stage filter module 700, the second end of the fourth resistor R4 is connected to the first end of the third resistor R3, the second end of the fourth resistor R4 is connected to the second end of the first-stage filter module 700, and the second end of the third resistor R3 and the first end of the fourth resistor R4 jointly output the second sampling voltage signal.

[0052] The second error amplification unit 220 includes a second error amplifier gm2, a fifth resistor R5, and a second capacitor C2. The negative input of the second error amplifier gm2 is connected to the second voltage sampling unit 210, the positive input is connected to the first feedback module 100, and the output of the second error amplifier gm2 is connected to the feedback adjustment module 400. The first end of the fifth resistor R5 is connected to the output of the second error amplifier gm2, and the second end of the fifth resistor R5 is grounded (GND). The first end of the second capacitor C2 is connected to the output of the second error amplifier gm2, and the second end of the second capacitor C2 is grounded (GND).

[0053] In this embodiment, the third resistor R3 and the fourth resistor R4 sample the voltage across the first-stage filter module 700 (i.e., the output voltage of the second filter module 700) and generate a second sampled voltage signal. The common terminal of the third resistor R3 and the fourth resistor R4 serves as the output terminal of the second sampled voltage signal, which is then output to the negative input of the second error amplifier gm1. The positive input of the second error amplifier gm2 receives the first feedback signal V1, compares the first feedback signal V1 with the second sampled voltage signal, amplifies it, and outputs the second feedback signal, thereby performing loop compensation on the two-stage LC switching power supply. The compensation value is:

[0054] F L =K L / (1+s / ω PL )

[0055] Where, ω PL =R4*C5, where KL provides sufficient mid-frequency gain to maintain the loop's output performance at high frequencies.

[0056] In one embodiment, see Figure 4 As shown, the feedback adjustment module 400 includes a pulse width modulation comparator U1. The negative phase input of the pulse width modulation comparator U1 is connected to the sampling module 300 and receives the sampled current signal V3. The positive phase input of the pulse width modulation comparator U1 is connected to the second feedback module 200 and receives the second feedback signal V2. The ramp receiving terminal (i.e., the negative phase input of the pulse width modulation comparator U1) receives the ramp compensation signal Slope; the output terminal of the pulse width modulation comparator U1 is connected to the switching module 500.

[0057] Specifically, the pulse width modulation comparator U1 receives the sampled current signal V3, the second feedback signal V2, and the slope compensation signal Slop. Generally, when controlled by the sampled current signal V3, subharmonic oscillations will occur. The sampled current pulse width modulation comparator U1 superimposes a current signal with a fixed slope, i.e., the slope compensation signal Slop, onto the sampled current signal V3, thereby reducing the gain of the current loop at the 1 / 2 harmonic, thus suppressing subharmonic oscillations and making the pulse width modulation signal Vc output by the pulse width modulation comparator U1 from the loop compensation circuit more stable.

[0058] In this embodiment, the pulse width modulation comparator U1 compares the sampled current signal V3 with the second feedback signal V2, and simultaneously superimposes the comparison result with the slope compensation signal Slope to output the pulse width modulation signal Vc to adjust the switching frequency of the switching transistor in the switching module 500, thereby achieving the purpose of quickly adjusting the output signal of the switching module 500 and reducing the output ripple of the two-stage LC switching power supply.

[0059] In one embodiment, see Figure 5 As shown, the feedback adjustment module 300 includes a current sampling unit Ri. The input terminal of the current sampling unit Ri is connected to the output terminal of the switch module 500, and the output terminal of the current sampling unit Ri is connected to the feedback adjustment module 400.

[0060] In this embodiment, the current sampling unit Ri samples the current output by the switching module 500 (i.e., the current flowing through the first inductor LS1), and outputs the sampled current signal waveform to the feedback adjustment module 400, and superimposes it with the slope compensation signal Slope, thereby adjusting the duty cycle of the output waveform of the feedback adjustment module 400.

[0061] Figure 5 For a specific embodiment, see the circuit schematic of a two-stage LC switching power supply. Figure 5 As shown, the input power signal Vin obtains the power supply signal required by the load RL through the switching module 500. The third capacitor C3 filters the input power signal Vin. The first switch Q1 and the first diode D1 form a BUCK circuit; controlling the switching frequency of the first switch Q1 controls the voltage value of the electrical signal output by the switching module 500. The first inductor LS1, the fourth capacitor C4, and the seventh resistor R7 form a first-stage LC filter circuit to filter the electrical signal output by the switching module 500. The second inductor LS2, the fifth capacitor C5, and the sixth resistor R6 form a second-stage LC filter circuit to further filter the power supply signal to be output, thus ensuring a stable waveform power supply signal output by the two-stage LC switching power supply.

[0062] In this embodiment, the transfer function of the two-stage LC switching power supply is:

[0063]

[0064]

[0065]

[0066] in,

[0067]

[0068]

[0069]

[0070]

[0071]

[0072]

[0073]

[0074]

[0075] In this embodiment, the second feedback signal 200 output by the second feedback module 200 is a sine wave signal. The second feedback signal 200 can feed back the output signals of the first-level filter module 600 and the second-level filter module 700. The second feedback signal 200 is connected to the sampling module 300.

[0076] Finally, this application provides a switching power supply device, which includes the loop compensation circuit described in any of the above embodiments.

[0077] In this embodiment, the switching power supply is positioned between the load and the external power source. The switching power supply can convert the power signal provided by the external power source into the power supply signal required by the load.

[0078] The loop compensation circuit includes a first feedback module, a second feedback module, a sampling module, and a feedback adjustment module. The first feedback module is connected to the second-stage filter module and samples the output voltage of the second-stage filter module to obtain a first sampled voltage signal. It then amplifies the voltage difference between the first sampled voltage signal and a first reference voltage to generate a first feedback signal. The second feedback module is connected to the first feedback module and the first-stage filter module. It samples the output voltage of the first-stage filter module to obtain a second sampled voltage signal and amplifies the voltage difference between the second sampled voltage signal and the first feedback signal to generate a second feedback signal. The sampling module is connected to the switching module and samples the current at the output of the switching module to obtain a sampled current signal. The feedback adjustment module is connected to the second feedback module and the sampling module and generates a pulse width modulation signal based on the sampled current signal, the second feedback signal, and the ramp compensation signal to adjust the switching frequency of the switching module. In this application, the first and second feedback modules sample the voltages of the second-stage and first-stage filter modules, respectively, and output the samples to the feedback adjustment module to modulate the voltage of the switching module. This solves the problem that a two-stage LC switching power supply cannot simultaneously perform loop compensation on both the first-stage and two-stage LC filter circuits.

[0079] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0080] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A loop compensation circuit applied to a two-stage LC switching power supply, the two-stage LC switching power supply comprising a switching module, a first filter module and a second filter module connected in sequence, characterized in that, The loop compensation circuit comprises: A first feedback module is connected with the second filter module, configured to sample an output voltage of the second filter module to obtain a first sampling voltage signal, and amplify a difference voltage between the first sampling voltage signal and a first reference voltage to generate a first feedback signal; A second feedback module is connected with the first feedback module and the first filter module, configured to sample an output voltage of the first filter module to obtain a second sampling voltage signal, and amplify a difference voltage between the second sampling voltage signal and the first feedback signal to generate a second feedback signal; A sampling module is connected with the switch module, configured to sample a current at an output end of the switch module to obtain a sampling current signal; A feedback adjustment module is connected with the second feedback module and the sampling module, configured to generate a pulse width modulation signal according to the sampling current signal, the second feedback signal and a slope compensation signal, so as to adjust a switching frequency of the switch module; the switch module comprises a first switch tube and a first diode, the first switch tube and the first diode constitute a BUCK circuit, and the pulse width modulation signal is configured to control the frequency of turning on and off of the first switch tube.

2. The loop compensation circuit of claim 1, wherein, The first feedback module comprises a first voltage sampling unit and a first error amplifier unit; wherein, The first voltage sampling unit is connected at both ends of the second filter module, the first input end of the first error amplifier unit is connected with the output end of the first voltage sampling unit, and the second input end of the first error amplifier unit is connected with the sampling module.

3. The loop compensation circuit of claim 2, wherein, The first voltage sampling unit comprises a first resistor and a second resistor; wherein, The first end of the first resistor is connected with the first end of the second filter module, the second end of the first resistor is connected with the first end of the second resistor, the second end of the second resistor is connected with the second end of the second filter module, and the second end of the first resistor and the first end of the second resistor jointly output the first sampling voltage signal.

4. The loop compensation circuit of claim 2, wherein, The first error amplifier unit comprises a first error amplifier and a first capacitor; wherein, The negative phase end of the first error amplifier is connected with the first voltage sampling unit, the positive phase end of the first error amplifier receives a reference voltage, and the output end of the first error amplifier is connected with the second feedback module; the first end of the first capacitor is connected with the output end of the first error amplifier, and the second end of the first capacitor is grounded.

5. The loop compensation circuit of claim 1, wherein, The second feedback module comprises a second voltage sampling unit and a second error amplifier unit; wherein, The second voltage sampling unit is connected at both ends of the first filter module, the first input end of the second error amplifier unit is connected with the output end of the second voltage sampling unit, the second input end of the second error amplifier unit is connected with the first feedback module, and the output end of the second error amplifier unit is connected with the feedback adjustment module.

6. The loop compensation circuit of claim 5, wherein, The second voltage sampling unit comprises a third resistor and a fourth resistor; wherein, The first end of the third resistor is connected to the first end of the first filter module, the second end of the fourth resistor is connected to the first end of the third resistor, the second end of the fourth resistor is connected to the second end of the first filter module, and the second end of the third resistor and the first end of the fourth resistor jointly output a second sampling voltage signal.

7. The loop compensation circuit of claim 5, wherein, The second error amplifier, a fifth resistor and a second capacitor are included in the second error amplification unit. The negative phase end of the second error amplifier is connected to the second voltage sampling unit, the positive phase end of the second error amplifier is connected to the first feedback module, and the output end of the second error amplifier is connected to the feedback adjustment module; the first end of the fifth resistor is connected to the output end of the second error amplifier, and the second end of the fifth resistor is grounded; the first end of the second capacitor is connected to the output end of the second error amplifier, and the second end of the second capacitor is grounded.

8. The loop compensation circuit of claim 1, wherein, The feedback adjustment module includes a pulse width modulation comparator, the negative phase end of the pulse width modulation comparator is connected to the sampling module and receives the sampling current signal; the positive phase end of the pulse width modulation comparator is connected to the second feedback module and receives the second feedback signal; the slope of the pulse width modulation comparator receives a slope compensation signal; and the output end of the pulse width modulation comparator is connected to the switch module.

9. The loop compensation circuit of claim 1, wherein, The sampling module includes a current sampling unit, the input end of the current sampling unit is connected to the output end of the switch module, and the output end of the current sampling unit is connected to the feedback adjustment module.

10. A switching power supply device, characterized by comprising: The switching power supply device includes the loop compensation circuit according to any one of claims 1-9.

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