CN115208172A - Loop compensation circuit applied to two-stage LC switching power supply and switching power supply device - Google Patents

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

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Publication number
CN115208172A
CN115208172A CN202210737017.XA CN202210737017A CN115208172A CN 115208172 A CN115208172 A CN 115208172A CN 202210737017 A CN202210737017 A CN 202210737017A CN 115208172 A CN115208172 A CN 115208172A
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China
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module
feedback
sampling
signal
voltage
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Chinese (zh)
Inventor
何明星
赵鹏
谢伟杰
黄国鹏
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STMicroelectronics Shenzhen R&D Co Ltd
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STMicroelectronics Shenzhen R&D Co Ltd
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/0003—Details of control, feedback or regulation circuits
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/0003—Details of control, feedback or regulation circuits
    • H02M1/0009—Devices or circuits for detecting current in a converter
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/14—Arrangements for reducing ripples from dc input or output
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
    • H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
    • H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators
    • H02M3/157—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators with digital control
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
    • Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Dc-Dc Converters (AREA)

Abstract

The utility model belongs to the switching power supply field provides a be applied to loop compensation circuit of two-stage LC switching power supply, and loop compensation circuit includes first feedback module, second feedback module, sampling module and feedback adjustment module, and first feedback module and second feedback module generate the second feedback signal according to the output voltage of second grade filter module and first grade filter module, and sampling module samples the electric current of the output of switching module and obtains the sampling current signal, feedback adjustment module connect the second feedback module with sampling module for according to sampling current signal, second feedback signal generation pulse width modulation signal in order to adjust the switching frequency of switching module, loop compensation circuit feeds back to switching module output current, first grade filter module output voltage and second grade filter module output voltage in this application, has solved loop compensation circuit and can't carry out the problem of loop compensation to first grade filter module and second grade filter module.

Description

Loop compensation circuit applied to two-stage LC switching power supply and switching power supply device
Technical Field
The application belongs to the field of switching power supplies, and particularly relates to a loop compensation circuit applied to a two-stage LC switching power supply and a switching power supply device.
Background
Switching power supplies are the most basic building blocks in modern electronic circuitry. Which converts the known dc input voltage to a dc output voltage that is required by the system or is easy to use. When digital, analog and radio frequency applications sensitive to ripples are involved, a two-stage LC switching power supply is used to directly supply power to a load, so that the efficiency of the system is improved, and the low-ripple performance of the output voltage becomes very important.
However, the conventional two-stage LC switching power supply has a problem that loop compensation cannot be simultaneously performed on the one-stage LC filter circuit and the two-stage LC filter circuit.
Disclosure of Invention
An object of the application is to provide a loop compensation circuit and switching power supply device for two-stage LC switching power supply, aim at solving the problem that can't carry out loop compensation to one-level LC filter circuit and two-stage LC filter circuit simultaneously among the current two-stage LC switching power supply.
This application provides a loop compensation circuit for two-stage LC switching power supply in an aspect, two-stage LC switching power supply is including the switch module, one-level filter module and the second grade filter module that connect according to the preface, its characterized in that, loop compensation circuit includes:
the first feedback module is connected with the secondary filtering module and used for sampling the output voltage of the secondary filtering module to obtain a first sampling voltage signal and amplifying the difference voltage of the first sampling voltage signal and a first reference voltage to generate a first feedback signal;
the second feedback module is connected with the first feedback module and the primary filtering module and used for sampling the output voltage of the primary filtering module to obtain a second sampling voltage signal and amplifying the difference voltage of the second sampling voltage signal and the first feedback signal to generate a second feedback signal;
the sampling module is connected with the switch module and is used for sampling the current at the output end of the switch module to obtain a sampling current signal;
and the feedback adjusting module is connected with the second feedback module and the sampling module and used for generating a pulse width modulation signal according to the sampling current signal, the second feedback signal and the slope compensation signal so as to adjust the switching frequency of the switching module.
In one embodiment, the first feedback module includes a first voltage sampling unit and a first error amplifying unit; wherein the content of the first and second substances,
the first voltage sampling unit is connected to two ends of the second-stage filtering module, a first input end of the first error amplification unit is connected to an output end of the first voltage sampling unit, and a second input end of the first error amplification unit is connected to the sampling module.
In one embodiment, the first voltage sampling unit includes a first resistor and a second resistor; wherein the content of the first and second substances,
the first end of first resistance is connected the first end of second grade filtering module, the second end of first resistance is connected the first end of second resistance, the second end of second resistance is connected the second end of second grade filtering module, the second end of first resistance with the first end of second resistance exports first sampling voltage signal jointly.
In one embodiment, the first error amplifying unit includes a first error amplifier and a first capacitor; wherein the content of the first and second substances,
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.
In one embodiment, the second feedback module comprises a second voltage sampling unit and a second error amplifying unit; wherein the content of the first and second substances,
the second voltage sampling unit is connected to the two ends of the first-stage filtering module, the first input end of the second error amplification unit is connected to the output end of the second voltage sampling unit, the second input end of the second error amplification unit is connected to the first feedback module, and the output end of the second error amplification unit is connected to the feedback regulation module.
In one embodiment, the second voltage sampling unit includes a third resistor and a fourth resistor; wherein the content of the first and second substances,
the first end of third resistance is connected the first end of one-level filtering module, the second end of fourth resistance is connected the first end of third resistance, the second end of fourth resistance is connected the second end of one-level filtering module, the second end of third resistance with the first end of fourth resistance exports second sampled voltage signal jointly.
In one embodiment, the second error amplifying unit includes a second error amplifier, a fifth resistor, and a second capacitor; wherein, the first and the second end of the pipe are connected with each other,
the negative phase end of the second error amplifier is connected with the second voltage sampling unit, the positive phase end of the second error amplifier is connected with the first feedback module, and the output end of the second error amplifier is connected with the feedback regulation module; a first end of the fifth resistor is connected to the output end of the second error amplifier, and a second end of the fifth resistor is grounded; and the first end of the second capacitor is connected with the output end of the second error amplifier, and the second end of the second capacitor is grounded.
In one embodiment, the feedback regulation module comprises a pulse width modulation comparator, and the negative phase end of the pulse width modulation comparator is connected with the sampling module and receives the sampling current signal; the positive phase end of the pulse width modulation comparator is connected with the second feedback module and receives the second feedback signal; a ramp receiving end of the pulse width modulation comparator receives a ramp compensation signal; and the output end of the pulse width modulation comparator is connected with the switch module.
In one embodiment, the sampling module comprises a current sampling unit, an input end of the current sampling unit is connected with an output end of the switch module, and an output end of the current sampling unit is connected with the feedback regulation module.
The present application provides, in another aspect, a switching power supply apparatus including the loop compensation circuit described in any one of the above embodiments.
The loop compensation circuit comprises a first feedback module, a second feedback module, a sampling module and a feedback regulation module, wherein the first feedback module is connected with the second-stage filtering module and used for sampling the output voltage of the second-stage filtering module to obtain a first sampling voltage signal and amplifying the difference voltage of the first sampling voltage signal and a first reference voltage to generate a first feedback signal, the second feedback module is connected with the first feedback module and the first-stage filtering module and used for sampling the output voltage of the first-stage filtering module to obtain a second sampling voltage signal and amplifying the difference voltage of the second sampling voltage signal and the first feedback signal to generate a second feedback signal, the sampling module is connected with the switch module and used for sampling the current at the output end of the switch module to obtain a sampling current signal, and the feedback regulation module is connected with the second feedback module and the sampling module and used for generating a pulse width modulation signal according to the sampling current signal, the second feedback signal and the slope compensation signal to regulate the switching frequency of the switch module. In the application, the first feedback module and the second feedback module respectively carry out voltage sampling on the second-stage filter module and the first-stage filter module and output the voltage to the feedback adjusting module to modulate the voltage of the switch module, so that the problem that the two-stage LC switch power supply cannot carry out loop compensation on the first-stage LC filter circuit and the two-stage LC filter circuit at the same time is solved.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
Fig. 1 is a functional block diagram of a two-stage LC switching power supply provided in an embodiment of the present application;
fig. 2 is a schematic circuit diagram of a first feedback module according to an embodiment of the present disclosure;
fig. 3 is a schematic circuit diagram of a second feedback module according to an embodiment of the present disclosure;
FIG. 4 is a schematic circuit diagram of a feedback regulation module according to an embodiment of the present disclosure;
fig. 5 is a schematic circuit diagram of a two-stage LC switching power supply according to an embodiment of the present disclosure.
Detailed Description
In order to make the technical problems, technical solutions and advantageous effects to be solved by the present application clearer, the present application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of and not restrictive on the broad application.
It will be understood that when an element is referred to as being "secured to" or "disposed on" another element, it can be directly on the other element or be indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or be indirectly connected to the other element.
It will be understood that the terms "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like, refer to an orientation or positional relationship illustrated in the drawings for convenience in describing the present application and to simplify description, and do not indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and thus should not be construed as limiting the present application.
Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating 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 the present application, "a plurality" means two or more unless specifically limited otherwise.
In order to make the power supply signal output by the switching power supply more stable, an LC filter circuit is usually added, so that the switching power supply has two stages of LC filter circuits on the basis of the original LC filter circuit, and in the switching power supply having the two stages of LC filter circuits, the improvement of the stability of the switching power supply is beneficial to outputting the stable power supply signal.
The existing two-stage LC switch power supply has a compensation loop, the compensation loop only samples a power supply signal output by a two-stage LC filter circuit of the switch power supply and compares the power supply signal with a reference voltage signal, when the power supply signal is different from the reference voltage signal, the compensation loop controls a power conversion module at the end of the switch power supply so that the power conversion module outputs the power supply signal required by a load, but the loop compensation circuit cannot compare the output signal of the power conversion module of the switch power supply with the output signal of a one-stage LC filter circuit, so that the loop compensation circuit cannot simultaneously compensate the one-stage LC filter circuit and the two-stage LC filter circuit, and the stability of the two-stage LC switch power supply is improved.
In order to solve the above problem, the present application provides a loop compensation circuit applied to a two-stage LC switching power supply, and as shown in fig. 1, 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, where the first feedback module 100 is connected to a two-stage filtering module 700, and is configured to sample an output voltage of the two-stage filtering module 700 to obtain a first sampling voltage signal, and generate a first feedback signal V1 by using a differential voltage between the first sampling voltage signal and a first reference voltage, and output the first feedback signal V1 to the second feedback module 200. The second feedback module 200 is connected to the first feedback module 100 and the primary filtering module 600, and is configured to sample an output voltage of the primary filtering module 600 to generate a second sampling voltage signal, and then the primary filtering module 600 further receives the first feedback signal V1, generates a second feedback signal V2 according to a difference voltage between the second sampling voltage signal and the first feedback signal V1, and outputs the second feedback signal V2 to the feedback adjusting module 400. The sampling module 300 is connected to the output end of the switch module 500, and is configured to sample a current at the output end of the switch module 500 to generate a sampled current signal V3, and output the sampled current signal V3 to the feedback adjustment module 400. The feedback adjusting module 400 is connected to the second feedback module 200 and the sampling module 300, and configured to receive the second feedback signal V2 and the sampling current signal V3, and adjust the switching frequency of the switch module 500 according to the second feedback signal V2 and the sampling current signal V3, so as to adjust the voltage of the electrical signal output by the switch module 500.
Specifically, as shown in fig. 1, the second-stage filtering module 700 outputs a power supply signal to a load to supply power to the load, the first feedback module 100 samples voltages at two ends of the second-stage filtering module 700 (i.e., output voltages of the second-stage filtering module 700) to obtain a first sampling voltage signal, and when the first feedback module 100 obtains the first sampling voltage signal, the first feedback module 100 compares the first sampling voltage signal with a first reference voltage, and generates a first feedback signal V1 from a difference voltage between the power supply signal and the first reference voltage, so as to perform remote loop compensation on the two-stage LC switching power supply.
The first-stage filtering module 600 outputs a second sampling voltage signal, the second feedback module 200 samples voltages at two ends of the first-stage filtering module 600 (i.e., the output voltage of the first-stage filtering module 600) to obtain a second sampling voltage signal, the second feedback module 200 compares the second sampling voltage signal with the first feedback signal V1, and generates a second feedback signal V2 according to a difference voltage between the second sampling voltage signal and the first feedback signal V1, thereby performing loop compensation on the switching power supply.
The sampling module 300 is connected to the output end of the switch module 500, and is configured to sample the current output by the switch module to generate a sampled current signal and output the sampled current signal V3 to the feedback adjustment module 400, so as to control the feedback adjustment module 400 to output the pulse width modulation signal Vc, thereby controlling the switching frequency of the switch module.
When receiving the sampling current signal V3 output by the sampling module, the feedback regulation module 400 adjusts the duty ratio output by the feedback regulation module 400 according to the peak value of the waveform of the output current, thereby controlling the voltage value of the voltage output by the switching module 500. When the feedback adjusting module 400 receives the second feedback signal V2 output by the second feedback module 200, the feedback adjusting module 400 compensates for the insufficient performance of the closed-loop system of the switching power supply during disturbance through the second feedback signal V2, so as to maintain the stability of the closed-loop system.
In this embodiment, the loop compensation circuit adopts a current control type loop compensation, and 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 output by the switching module 500 of the two-stage LC power supply, so that the power supply signal output by the switching power supply circuit is stabilized at a voltage value required by a load, and meanwhile, the loop compensation circuit can also work normally without using the second-stage filter module 700, and the loop compensation circuit solves the problem of the loop compensation of the two-stage LC switching power supply.
In one embodiment, referring to fig. 2, the first feedback module 100 includes a first voltage sampling unit 110 and a first error amplifying unit 120. The first voltage sampling unit 110 is connected to two ends of the second-stage filtering module 700, a first input end of the first error amplifying unit 120 is connected to an output end of the first voltage sampling unit 110, and a second input end of the first error amplifying unit 120 is connected to the sampling module 200.
Specifically, the first voltage sampling unit 110 includes a first resistor R1 and a second resistor R2, a first end of the first resistor R1 is connected to a first end of the secondary filtering module 700, a second end of the first resistor R1 is connected to a first end of the second resistor R2, a second end of the second resistor R2 is connected to a second end of the secondary filtering module 700, and the second end of the first resistor R1 and the first end of the second resistor R2 output the first sampling voltage signal together.
The first error amplifying unit 120 includes a first error amplifier gm1 and a first capacitor C1. The negative phase terminal of the first error amplifier gm1 is connected to the first voltage sampling unit 110, the positive phase terminal of the first error amplifier gm1 receives the first reference voltage Vref, and the output terminal of the first error amplifier gm1 is connected to the second feedback module 200; a first end of the first capacitor C1 is connected to the output terminal of the first error amplifier gm1, and a second end of the first capacitor C2 is grounded GND.
In this embodiment, the first resistor R1 and the second resistor R2 sample a voltage across the second filtering module 700 (i.e., an output voltage of the second filtering module 700) to generate a first sampled voltage signal, a common end of the first resistor R1 and the second resistor R2 serves as an output end of the first sampled voltage signal, and outputs the first sampled voltage signal to a negative phase end of the first error amplifier gm1, and a positive phase end 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 then amplifies and outputs the first feedback signal V1. Therefore, remote loop compensation is carried out on the two-stage LC switching power supply, and the compensation value is as follows:
F R ＝K R /s＝1/C 3 s
the first voltage sampling unit 110 and the first error amplifying unit 120 sample the power supply signal output by the two-stage filtering module 700, and generate a first feedback signal V1 capable of generating signal compensation for the two-stage LC switching power supply according to the power supply signal, so as to adjust the power supply signal output by the two-stage LC switching power supply.
In one embodiment, referring to fig. 3, the second feedback module 200 includes a second voltage sampling unit 210 and a second error amplifying unit 220. The second voltage sampling unit 210 is connected to two ends of the first-stage filtering module 700, a first input end of the second error amplifying unit 220 is connected to an output end of the second voltage sampling unit 110, a second input end of the second error amplifying unit 120 is connected to the first feedback module 100, and an output end of the second error amplifying unit 220 is connected to the feedback adjusting module 400.
Specifically, with continued reference to fig. 3, the second voltage sampling unit 210 includes a third resistor R3 and a fourth resistor R4; a first end of the third resistor R3 is connected to a first end of the first-stage filtering module 700, a second end of the fourth resistor R4 is connected to a first end of the third resistor R3, a second end of the fourth resistor R4 is connected to a second end of the first-stage filtering module 700, and a second end of the third resistor R3 and the first end of the fourth resistor R4 output a second sampling voltage signal together.
The second error amplifying unit 220 includes a second error amplifier gm2, a fifth resistor R5, and a second capacitor C2. The negative phase end of the second error amplifier gm2 is connected to the second voltage sampling unit 210, the positive phase end of the second error amplifier gm2 is connected to the first feedback module 100, and the output end of the second error amplifier gm2 is connected to the feedback adjustment module 400; a first end of the fifth resistor R5 is connected to the output end of the second error amplifier gm2, and a second end of the fifth resistor R5 is grounded GND; a first terminal of the second capacitor C2 is connected to the output terminal of the second error amplifier gm2, and a second terminal of the second capacitor C2 is grounded GND.
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, a common end of the third resistor R3 and the fourth resistor R4 is used as an output end of the second sampled voltage signal, and outputs the second sampled voltage signal to a negative phase end of the second error amplifier gm1, a positive phase end of the second error amplifier gm2 receives the first feedback signal V1, and compares the first feedback signal V1 with the second sampled voltage signal and then amplifies the first feedback signal and outputs the second feedback signal, so as to perform loop compensation on the two-stage LC switching power supply, where the compensation value is:
F L ＝K L /(1+s/ω PL )
wherein, ω is PL ＝R 4 *C 5 The compensation value KL provides sufficient intermediate frequency gain to maintain the loop output effect at high frequencies.
In one embodiment, referring to fig. 4, the feedback regulation module 400 includes a pwm comparator U1, and a negative phase terminal of the pwm comparator U1 is connected to the sampling module 300 and receives the sampled current signal V3. The non-inverting terminal of the pwm comparator U1 is connected to the second feedback module 200 and receives the second feedback signal V2. A ramp receiving end of the pulse width modulation comparator U1 (namely, a negative phase end of the pulse width modulation comparator U1) receives a ramp compensation signal Slope; the output terminal of the pwm comparator U1 is connected to the switch module 500.
Specifically, the pwm comparator U1 receives the sampling current signal V3, the second feedback signal V2, and the slope compensation signal Slop, and generally, subharmonic oscillation occurs under the control of the sampling current signal V3, and the sampling current pwm comparator U1 superimposes a current signal of a fixed slope, that is, the slope compensation signal Slop, on the sampling current signal V3, so as to reduce the gain of the current loop at 1/2 harmonic, thereby suppressing the subharmonic oscillation, and making the pwm signal Vc output by the pwm comparator U1 and output by the loop compensation circuit more stable.
In this embodiment, the pwm comparator U1 compares the sampling current signal V3 with the second feedback signal V2, and superimposes the Slope compensation signal Slope on the comparison result to output the pwm signal Vc to adjust the switching frequency of the switching tube in the switching module 500, so as to achieve the purpose of rapidly adjusting the output signal of the switching module 500 and reducing the output ripple of the two-stage LC switching power supply.
In one embodiment, referring to fig. 5, the feedback regulation module 300 includes a current sampling unit Ri, an input terminal of the current sampling unit Ri is connected to an output terminal of the switch module 500, and an output terminal of the current sampling unit Ri is connected to the feedback regulation module 400.
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 LS 1), and outputs the sampled current signal waveform to the feedback regulating module 400, and superimposes the current signal waveform with the Slope compensation signal Slope, so as to adjust the duty ratio of the output waveform of the feedback regulating module 400.
Fig. 5 is a schematic circuit diagram of a two-stage LC switching power supply according to a specific embodiment, and referring to fig. 5, an input power signal Vin obtains a power supply signal required by a load RL through a switching module 500. The third capacitor C3 is used for filtering the input power signal Vin, the first switch tube Q1 and the first diode D1 form a BUCK circuit, and the frequency for controlling the on and off of the first switch tube Q1 can control the voltage value of the electrical signal output by the switch module 500. The first inductor LS1, the fourth capacitor C4 and the seventh resistor R7 form a first-stage LC filter circuit for performing filter processing on the electrical signal output by the switch module 500, and the second inductor LS2, the fifth capacitor C5 and the sixth resistor R6 form a second-stage LC filter circuit for performing secondary filter processing on the power supply signal to be output, so that the two-stage LC switch power supply outputs a power supply signal with a stable waveform.
In this embodiment, the transfer function of the two-stage LC switching power supply is:
Figure BDA0003715985900000101
Figure BDA0003715985900000111
Figure BDA0003715985900000112
wherein the content of the first and second substances,
Figure BDA0003715985900000113
Figure BDA0003715985900000114
Figure BDA0003715985900000115
Figure BDA0003715985900000116
Figure BDA0003715985900000117
Figure BDA0003715985900000118
Figure BDA0003715985900000119
Figure BDA00037159859000001110
in this embodiment, the second feedback signal 200 output by the second feedback module 200 is a sinusoidal signal, and the second feedback signal 200 can feed back the output signals of the first-stage filtering module 600 and the second-stage filtering module 700, the second feedback signal 200, and the sampling module 300.
The present application finally provides a switching power supply apparatus comprising the loop compensation circuit described in any one of the above embodiments.
In this embodiment, the switching power supply device is disposed between the load and the external power supply, and the switching power supply device can convert the power supply signal provided by the external power supply into the power supply signal required by the load,
the loop compensation circuit comprises a first feedback module, a second feedback module, a sampling module and a feedback regulation module, wherein the first feedback module is connected with the second-stage filtering module and used for sampling the output voltage of the second-stage filtering module to obtain a first sampling voltage signal and amplifying the difference voltage of the first sampling voltage signal and a first reference voltage to generate a first feedback signal, the second feedback module is connected with the first feedback module and the first-stage filtering module and used for sampling the output voltage of the first-stage filtering module to obtain a second sampling voltage signal and amplifying the difference voltage of the second sampling voltage signal and the first feedback signal to generate a second feedback signal, the sampling module is connected with the switch module and used for sampling the current at the output end of the switch module to obtain a sampling current signal, and the feedback regulation module is connected with the second feedback module and the sampling module and used for generating a pulse width modulation signal according to the sampling current signal, the second feedback signal and the slope compensation signal to regulate the switching frequency of the switch module. In the application, the first feedback module and the second feedback module respectively carry out voltage sampling on the second-stage filter module and the first-stage filter module and output the voltage to the feedback adjusting module to modulate the voltage of the switch module, so that the problem that the two-stage LC switch power supply cannot carry out loop compensation on the first-stage LC filter circuit and the two-stage LC filter circuit at the same time is solved.
In the above embodiments, the descriptions of the respective embodiments have respective emphasis, and reference may be made to the related descriptions of other embodiments for parts that are not described or illustrated in a certain embodiment.
The above-mentioned embodiments are only used for illustrating the technical solutions of the present application, and not for limiting the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not substantially depart from the spirit and scope of the embodiments of the present application and are intended to be included within the scope of the present application.

Claims (10)

1. Be applied to loop compensation circuit of two-stage LC switching power supply, two-stage LC switching power supply is including switch module, one-level filter module and the second grade filter module that connects gradually, its characterized in that, loop compensation circuit includes:
the first feedback module is connected with the secondary filtering module and used for sampling the output voltage of the secondary filtering module to obtain a first sampling voltage signal and amplifying the difference voltage of the first sampling voltage signal and a first reference voltage to generate a first feedback signal;
the second feedback module is connected with the first feedback module and the primary filtering module and used for sampling the output voltage of the primary filtering module to obtain a second sampling voltage signal and amplifying the difference voltage of the second sampling voltage signal and the first feedback signal to generate a second feedback signal;
the sampling module is connected with the switch module and used for sampling the current at the output end of the switch module to obtain a sampling current signal;
and the feedback adjusting module is connected with the second feedback module and the sampling module and used for generating a pulse width modulation signal according to the sampling current signal, the second feedback signal and the slope compensation signal so as to adjust the switching frequency of the switching module.
2. The loop compensation circuit of claim 1, wherein the first feedback module comprises a first voltage sampling unit and a first error amplifying unit; wherein the content of the first and second substances,
the first voltage sampling unit is connected to two ends of the second-stage filtering module, a first input end of the first error amplification unit is connected to an output end of the first voltage sampling unit, and a second input end of the first error amplification unit is connected to 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 and the second end of the pipe are connected with each other,
the first end of the first resistor is connected with the first end of the second-stage filtering 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-stage filtering module, and the second end of the first resistor and the first end of the second resistor output a first sampling voltage signal together.
4. The loop compensation circuit of claim 2, wherein the first error amplification unit includes a first error amplifier and a first capacitor; wherein the content of the first and second substances,
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 amplifying unit; wherein, the first and the second end of the pipe are connected with each other,
the second voltage sampling unit is connected to the two ends of the first-stage filtering module, the first input end of the second error amplifying unit is connected to the output end of the second voltage sampling unit, the second input end of the second error amplifying unit is connected to the first feedback module, and the output end of the second error amplifying unit is connected to the feedback adjusting 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 content of the first and second substances,
the first end of third resistance is connected the first end of one-level filtering module, the second end of fourth resistance is connected the first end of third resistance, the second end of fourth resistance is connected the second end of one-level filtering module, the second end of third resistance with the first end of fourth resistance exports second sampled voltage signal jointly.
7. The loop compensation circuit of claim 5, wherein the second error amplification unit comprises a second error amplifier, a fifth resistor, and a second capacitor; wherein the content of the first and second substances,
the negative phase end of the second error amplifier is connected with the second voltage sampling unit, the positive phase end of the second error amplifier is connected with the first feedback module, and the output end of the second error amplifier is connected with the feedback regulation module; a first end of the fifth resistor is connected to the output end of the second error amplifier, and a second end of the fifth resistor is grounded; and the first end of the second capacitor is connected with 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 regulation module comprises a pulse width modulated comparator having a negative terminal connected to the sampling module and receiving the sampled current signal; the positive phase end of the pulse width modulation comparator is connected with the second feedback module and receives the second feedback signal; a ramp receiving end of the pulse width modulation comparator receives a ramp compensation signal; and the output end of the pulse width modulation comparator is connected with the switch module.
9. The loop compensation circuit of claim 1, wherein the sampling module comprises a current sampling unit, an input terminal of the current sampling unit is connected to an output terminal of the switching module, and an output terminal of the current sampling unit is connected to the feedback regulation module.
10. A switching power supply unit, characterized in that it comprises a loop compensation circuit according to any of claims 1-9.
CN202210737017.XA 2022-06-27 2022-06-27 Loop compensation circuit applied to two-stage LC switching power supply and switching power supply device Pending CN115208172A (en)

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CN202210737017.XA CN115208172A (en) 2022-06-27 2022-06-27 Loop compensation circuit applied to two-stage LC switching power supply and switching power supply device

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Application Number Priority Date Filing Date Title
CN202210737017.XA CN115208172A (en) 2022-06-27 2022-06-27 Loop compensation circuit applied to two-stage LC switching power supply and switching power supply device

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