CN116455210A - Control method of BUCK circuit, voltage conversion device and energy storage equipment - Google Patents

Control method of BUCK circuit, voltage conversion device and energy storage equipment Download PDF

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Publication number
CN116455210A
CN116455210A CN202310315098.9A CN202310315098A CN116455210A CN 116455210 A CN116455210 A CN 116455210A CN 202310315098 A CN202310315098 A CN 202310315098A CN 116455210 A CN116455210 A CN 116455210A
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CN
China
Prior art keywords
notch
voltage
frequency
buck circuit
output voltage
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Pending
Application number
CN202310315098.9A
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Chinese (zh)
Inventor
秦维
吴东
陈熙
王雷
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Ecoflow Technology Ltd
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Ecoflow Technology Ltd
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Priority to CN202310315098.9A priority Critical patent/CN116455210A/en
Publication of CN116455210A publication Critical patent/CN116455210A/en
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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
    • 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
    • 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
    • H02M1/0038—Circuits or arrangements for suppressing, e.g. by masking incorrect turn-on or turn-off signals, e.g. due to current spikes in current mode control
    • 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
    • H02M3/01—Resonant DC/DC 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
    • 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
    • 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 application provides a control method of a BUCK circuit, a voltage conversion device and energy storage equipment, wherein the control method of the BUCK circuit comprises the following steps: acquiring the current input voltage, the current output voltage, the target output voltage and the resonance frequency of the BUCK circuit; calculating according to the target output voltage and the current output voltage to obtain voltage deviation; carrying out notch processing on the voltage deviation to obtain a target duty ratio; the preset notch frequency during notch processing is determined according to the resonance frequency of the BUCK circuit; generating a PWM signal to the BUCK circuit according to the target duty cycle; the PWM signal is used for controlling the BUCK circuit to convert the input voltage and then output the target output voltage. According to the method and the device, the preset notch frequency is determined according to the resonance frequency, so that the gain of the BUCK circuit is quickly attenuated at the resonance frequency point, the resonance peak of the BUCK circuit is effectively restrained, and the dynamic performance of the circuit is improved.

Description

Control method of BUCK circuit, voltage conversion device and energy storage equipment
Technical Field
The application relates to the field of harmonic analysis, in particular to a control method of a BUCK circuit, a voltage conversion device and energy storage equipment.
Background
The voltage conversion circuit is a power electronic topology circuit, such as a buck circuit, that can implement voltage conversion. As shown in fig. 1, mathematical modeling of the buck circuit can result in an input-to-output transfer function:
thereby obtaining a transfer function G from the duty ratio to the output voltage buck (s)：
Where s is the complex frequency. To facilitate analysis of the performance of the system, let l=30uh, c=680uf, r=2.4Ω, vin=50v. And carrying out frequency domain and time domain analysis on the system to obtain a Bode diagram and a step response of the system, as shown in figure 2. It can be seen that the system is inThere is a distinct resonance peak where the amplitude-frequency gain is large, and if the bandwidth of the system is lower than the L1C1 resonance frequency, the occurrence of this resonance peak will cause the system to experience a second pass.
Disclosure of Invention
In order to solve the problems in the prior art, the application provides a control method of a BUCK circuit, a voltage conversion device and energy storage equipment, and resonance peak suppression of the BUCK circuit can be achieved.
The application provides a control method of a BUCK circuit, which comprises the following steps:
acquiring the current input voltage, the current output voltage, the target output voltage and the resonance frequency of the BUCK circuit;
calculating according to the target output voltage and the current output voltage to obtain voltage deviation;
carrying out notch processing on the voltage deviation based on a preset notch frequency to obtain a target duty ratio; the preset notch frequency is determined according to the resonance frequency of the BUCK circuit.
Generating a PWM signal to the BUCK circuit according to the target duty cycle; the PWM signal is used for controlling the BUCK circuit to convert the input voltage and then output the target output voltage.
In an embodiment, the calculating the voltage deviation according to the target output voltage and the current output voltage includes:
subtracting the current output voltage from the target output voltage to obtain the voltage deviation.
In one embodiment of the present invention, in one embodiment,
the step of performing notch processing on the voltage deviation to obtain a target duty ratio includes:
acquiring the working frequency of the BUCK circuit;
when the working frequency is smaller than the resonant frequency, controlling the gain in the notch processing to attenuate at a first attenuation rate, wherein the first attenuation rate is inversely related to the working frequency; carrying out notch processing after gain attenuation on the voltage deviation to obtain a target duty ratio;
when the working frequency is larger than the resonant frequency, controlling the gain in the notch processing to attenuate at a second attenuation rate, wherein the second attenuation rate is inversely related to the working frequency; and carrying out notch processing after gain attenuation on the voltage deviation to obtain a target duty ratio.
In an embodiment, the notching the voltage deviation based on a preset notch frequency includes:
the voltage deviation is input into a notch controller for notch processing.
In an embodiment, the transfer function of the notch controller is:
wherein G is ctrl (s) is the target gain, k is the gain coefficient, ε is the damping coefficient, ω n For presetting notch frequency, s and omega n Is a pair of conjugate zero points,pole zero, p 1 Is a notch coefficient>Is p 1 Is a pole of (c).
In an embodiment, the predetermined notch frequency is equal to the resonant frequency.
The application also provides a voltage conversion device which comprises a BUCK circuit, a sampling circuit and a voltage loop control circuit; the voltage loop control circuit comprises a subtracter, a notch controller and a PWM signal generator;
the sampling circuit is used for collecting the current input voltage and the current output voltage of the BUCK circuit;
the subtracter is used for receiving the current output voltage output by the sampling circuit, receiving a target output voltage and calculating to obtain voltage deviation according to the target output voltage and the current output voltage;
the notch controller is used for receiving the voltage deviation and carrying out notch processing on the voltage deviation to obtain a target duty ratio; the preset notch frequency of the notch controller is determined according to the resonance frequency of the BUCK circuit;
the PWM signal generator is used for receiving the target duty ratio and generating a PWM signal to the BUCK circuit according to the target duty ratio;
the BUCK circuit is used for working under the control of the PWM signal so as to convert the input voltage and then output the target output voltage.
In an embodiment, when the operating frequency is less than the resonant frequency, the gain of the notch controller decays at a first decay rate as the operating frequency increases;
when the working frequency is larger than the resonant frequency, the gain of the notch controller is attenuated at a second attenuation rate along with the increase of the working frequency;
wherein the second decay rate is greater than the first decay rate.
In an embodiment, the transfer function of the notch controller is:
wherein G is ctrl (s) is the target gain, k is the gain coefficient, ε is the damping coefficient, ω n For presetting notch frequency, s and omega n Is a pair of conjugate zero points,pole zero, p 1 Is a notch coefficient>Is p 1 Is a pole of (c).
The application also provides energy storage equipment, the energy storage equipment comprises the voltage conversion device.
According to the method, the current input voltage, the current output voltage, the target output voltage and the resonance frequency of the BUCK circuit are obtained, the voltage deviation is determined by calculating the target output voltage and the current output voltage of the BUCK circuit, the notch processing is carried out according to the voltage deviation to obtain the target duty ratio, and the BUCK circuit is controlled to correspondingly convert the input voltage and then output the target output voltage. According to the method and the device, the preset notch frequency is determined according to the resonant frequency, the target duty ratio for removing the influence of the resonant frequency is obtained based on the preset notch frequency, the BUCK circuit is controlled to perform voltage conversion based on the target duty ratio, the gain of the BUCK circuit is enabled to be attenuated rapidly at the resonant frequency point, the resonant peak of the BUCK circuit is effectively restrained, and the dynamic performance of the circuit is improved.
Drawings
FIG. 1 is a schematic diagram of a BUCK circuit according to an embodiment of the present application.
Fig. 2 is a bode diagram of a BUCK circuit of the present application.
FIG. 3 is a flow chart illustrating an embodiment of a control method of the BUCK circuit.
Fig. 4 is a schematic diagram of a subdivision flow of step S2 in the control method of the BUCK circuit of the present application.
FIG. 5 is a bird diagram of the BUCK circuit and notch controller of the present application.
Fig. 6 is a schematic structural diagram of an embodiment of a voltage conversion device of the present application.
Description of the main reference signs
BUCK circuit 100 sampling circuit 200
Voltage loop control circuit 300 subtractor 310
Notch controller 320 PWM signal generator 330
First capacitor C1 first inductance L1
First switching tube Q1 voltage conversion device 10
The following detailed description will further illustrate the application in conjunction with the above-described figures.
Detailed Description
The following description will refer to the accompanying drawings in order to more fully describe the present application. Exemplary embodiments of the present application are illustrated in the accompanying drawings. This application may, however, be embodied in many different forms and should not be construed as limited to the exemplary embodiments set forth herein. These exemplary embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the application to those skilled in the art. Like reference numerals designate identical or similar components.
The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. Furthermore, as used herein, "comprising" and/or "including" and/or "having", steps, operations, but do not exclude the presence or addition of one or more other features, steps, operations.
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Furthermore, unless the context clearly defines otherwise, terms such as those defined in a general dictionary should be construed to have meanings consistent with their meanings in the relevant art and the present application, and should not be construed as idealized or overly formal meanings.
The following description of exemplary embodiments will be provided with reference to the accompanying drawings. It is noted that the components depicted in the referenced figures are not necessarily shown to scale; and the same or similar components will be given the same or similar reference numerals or similar technical terms.
The present application proposes a control method of the BUCK circuit 100. Referring to fig. 1, the buck circuit 100 includes a first capacitor C1, a first inductor L1, and a first switching transistor Q1. Where Vin is the current input voltage of the BUCK circuit 100, and Vout is the current output voltage formed by the BUCK circuit 100 after converting the current input voltage. The target output voltage of the BUCK circuit 100 may be set according to the actual application scenario. For example, the load operating voltage to which the output terminal of the BUCK circuit 100 is connected is 10V, and the target output voltage may be set to 10V. The resonant frequency of BUCK circuit 100 can be calculated according to the formulaDetermining, wherein f c Is the resonant frequency of the BUCK circuit 100. Alternatively, the resonant frequency may be determined by testing with a test device, and other parameters are not changed, but only the frequency is changed, and the frequency when the response of the BUCK circuit 100 is maximum is the resonant frequency.
Referring to fig. 3, the present application proposes a control method of a BUCK circuit 100, including:
s1: the current input voltage, the current output voltage, the target output voltage and the resonance frequency of the BUCK circuit are obtained.
In this embodiment, the current input voltage and the current output voltage of the BUCK circuit 100 can be detected and determined by the sampling circuit 200 in fig. 6.
S2: and calculating according to the target output voltage and the current output voltage to obtain voltage deviation.
The voltage deviation can be calculated by the following formula: v (V) err ＝V ref -V out Wherein V is err For voltage deviation, V ref For the target output voltage V out Is the current output voltage. For example, the voltage deviation may be obtained by calculating a difference between the target output voltage and the current output voltage by the subtractor 310 shown in fig. 6.
S3: carrying out notch processing on the voltage deviation based on a preset notch frequency to obtain a target duty ratio; the preset notch frequency is determined according to the resonance frequency of the BUCK circuit.
In the embodiment of the present application, the voltage deviation is input to the notch controller 320 shown in fig. 6, and the notch controller 320 may filter the voltage deviation based on a preset notch frequency to obtain the target duty ratio with the resonant frequency influence removed. The preset notch frequency may be determined according to the resonance frequency of the BUCK circuit 100, for example, the preset notch frequency may be set to be equal to the resonance frequency, or the preset notch frequency may be set to be within a certain range (for example, a central value ±100 Hz) determined centering on the resonance frequency, and the voltage deviation is processed according to the preset notch frequency, so that the resonance frequency may be effectively suppressed.
S4: generating a PWM signal to the BUCK circuit according to the target duty cycle; the PWM signal is used for controlling the BUCK circuit to convert the input voltage and then output the target output voltage.
As shown in fig. 1, a PWM signal is generated according to a target duty ratio to drive a switching transistor (e.g., a first switching transistor Q1) of the BUCK circuit 100, so that the switching transistor of the BUCK circuit 100 converts an input voltage and outputs a target output voltage so as to suppress a resonance frequency. This controls the BUCK circuit 100 to perform voltage conversion of the input voltage while suppressing resonance generated during the notch processing, thereby improving the dynamic performance of the BUCK circuit 100.
The present application determines a voltage deviation by acquiring a current input voltage, a current output voltage, a target output voltage, and a resonance frequency of the BUCK circuit 100, and calculating the target output voltage and the current output voltage of the BUCK circuit 100, the notch processing is performed according to the voltage deviation to obtain a target duty ratio, so as to control the BUCK circuit 100 to correspondingly convert the input voltage and output a target output voltage. According to the method and the device, the preset notch frequency is determined according to the resonant frequency, the target duty ratio for removing the influence of the resonant frequency is obtained based on the preset notch frequency, the BUCK circuit is controlled to perform voltage conversion based on the target duty ratio, the gain of the BUCK circuit 100 is enabled to be attenuated rapidly at the resonant frequency point, the resonant peak of the BUCK circuit 100 is effectively restrained, and the dynamic performance of the circuit is improved.
Referring to fig. 4, in one embodiment, notching the voltage deviation to obtain a target duty cycle includes:
s21: the operating frequency of the BUCK circuit is obtained.
In the control system of the BUCK circuit 100, a low frequency high gain, high frequency fast decay is typically required to ensure the dynamic performance of the BUCK circuit 100. Thus, at different operating frequencies, the control gain is required to attenuate at different attenuation rates.
S22: when the working frequency is smaller than the resonance frequency, the gain in the notch processing is controlled to attenuate at a first attenuation rate, and the first attenuation rate is inversely related to the working frequency; and carrying out notch processing after gain attenuation on the voltage deviation to obtain a target duty ratio.
S23: when the working frequency is greater than the resonant frequency, the gain in the notch processing is controlled to attenuate at a second attenuation rate, and the second attenuation rate is inversely related to the working frequency; and carrying out notch processing after gain attenuation on the voltage deviation to obtain a target duty ratio.
The second decay rate is greater than the first decay rate. The smaller first decay rate is set at the low frequency band less than the resonant frequency to ensure high gain at the low frequency band. The resonance frequency is a point at which the notch controller 320 shown in fig. 6 rapidly decays, and the preset notch frequency may be set to be the same as or near the resonance frequency of the BUCK circuit 100 to effectively suppress the resonance peak in the loop.
Due to the characteristics of the notch controller 320, the amplitude-frequency characteristic may be tilted upward in the high frequency band of the notch controller 320. The second larger attenuation rate can be set in the high frequency band larger than the resonance frequency to increase the attenuation rate of the high frequency band and inhibit the amplitude-frequency characteristic of the high frequency band.
In one embodiment, the transfer function of notch controller 320 may be:
wherein G is ctrl (s) is the target gain, k is the gain coefficient, ε is the damping coefficient, ω n For presetting notch frequency, s and omega n Is a pair of conjugate zero points,pole zero, p 1 Is a notch coefficient>Is p 1 Is a pole of (c).
As shown in fig. 5, (1) is a bode diagram of the notch controller 320, (2) is a bode diagram of the controlled object (i.e., the BUCK circuit 100) (corresponding to fig. 2), and (3) is a bode diagram of the closed loop system (i.e., a loop bode diagram after being controlled by the notch controller 320).
The numerator of the transfer function of notch controller 320 includes a pair of conjugate zeros s and omega n . k is used to control the initial gain of the trap, i.e. the height of point a in control (1), the larger k the higher point a. And the sum of the initial gain of the notch controller 320 and the initial gain of the controlled object is the initial gain of the closed loop system, that is, the sum of the point a value in (1) and the point B value in (2) is equal to the point C value in (3). To stabilize the controlled loop, the C point value needs to be set to be greater than a predetermined gain (e.g., 40 dB).
The transfer function also comprises damping coefficient epsilon in the molecule, and epsilon can be in the range of 0-1. By setting a suitable value of epsilon (e.g., epsilon=0.14), the damping of the control system of BUCK circuit 100 can be increased, and the bandwidth of notch controller 320 can be increased, as shown in fig. 5.
Due to the characteristics of the notch controller 320, the amplitude characteristic of the high frequency band (i.e., the second half of fig. 5) above the resonance frequency is tilted upward, and in order to increase the gain attenuation coefficient of this part of the high frequency band, a zero pole (i.e., 1/s) and a p are introduced into the denominator 1 Is a function of the pole of (i.e.,) So that the gain of notch controller 320 begins to attenuate the loop at an initial attenuation rate, at p, at a frequency of 0 1 The point is attenuated at a first attenuation rate before p 1 The decay is started at a second decay rate, and the second decay rate at this time is higher than the initial decay rate and the first decay rate.
Wherein p is 1 The point may be set and adjusted according to the resonant frequency to cooperate with the pole-zero so that the gain of notch controller 320 may begin to decay rapidly at that point, increasing the attenuation coefficient of notch controller 320 at the high frequency band. In this manner, notch controller 320 may calculate a target duty cycle that suppresses the high-band amplitude-frequency characteristic from the transfer function.
Referring to fig. 6, the present application further proposes a voltage conversion device 10, including a BUCK circuit 100, a sampling circuit 200, and a voltage loop control circuit 300; the voltage loop control circuit 300 includes a subtractor 310, a notch controller 320, and a PWM signal generator 330;
the sampling circuit 200 is used for collecting the current input voltage and the current output voltage of the BUCK circuit 100;
the subtractor 310 is configured to receive the current output voltage output by the sampling circuit 200, receive a target output voltage, and calculate a voltage deviation according to the target output voltage and the current output voltage;
the notch controller 320 is configured to receive the voltage deviation, and notch the voltage deviation to obtain a target duty cycle; the preset notch frequency of the notch controller 320 is determined according to the resonance frequency of the BUCK circuit 100;
the PWM signal generator 330 is configured to receive the target duty cycle, and generate a PWM signal to the BUCK circuit 100 according to the target duty cycle;
the BUCK circuit 100 is configured to operate under control of the PWM signal to convert an input voltage and output a target output voltage.
In this embodiment, the target output voltage of the BUCK circuit 100 may be set according to the actual application scenario. For example, the load operating voltage to which the output terminal of the BUCK circuit 100 is connected is 10V, and the target output voltage may be set to 10V. The resonant frequency can be according to the formulaDetermining, wherein f c For the resonant frequency of the BUCK circuit 100, L1 is the first inductance of the BUCK circuit 100, and C1 is the first capacitance of the BUCK circuit 100. Alternatively, the resonant frequency may be determined by testing with a test device, and other parameters are not changed, but only the frequency is changed, and the frequency when the response of the BUCK circuit 100 is maximum is the resonant frequency.
In this embodiment, the subtractor 310 may calculate the voltage deviation according to the following formula: v (V) err ＝V ref -V out Wherein V is err For voltage deviation, V ref For the target output voltage V out Is the current output voltage.
In the embodiment of the present application, the voltage deviation is input to the notch controller 320 shown in fig. 6, and the notch controller 320 may filter the voltage deviation based on a preset notch frequency to obtain the target duty ratio with the resonant frequency influence removed. The preset notch frequency may be determined according to the resonance frequency of the BUCK circuit 100, for example, the preset notch frequency may be set to be equal to the resonance frequency, or the preset notch frequency may be set to be within a certain range (for example, a central value ±100 Hz) determined centering on the resonance frequency, so as to notch the voltage deviation according to the preset notch frequency, thereby effectively suppressing the resonance frequency.
The PWM signal generator 330 generates a PWM signal according to a target duty ratio to drive the switching transistor of the BUCK circuit 100, and causes the switching transistor of the BUCK circuit 100 to convert the input voltage and output a target output voltage in such a manner that the resonant frequency is suppressed. This controls the BUCK circuit 100 to perform power conversion of the input voltage while suppressing resonance generated during the notch processing, thereby improving dynamic performance of the BUCK circuit 100.
The current input voltage and the current output voltage of the BUCK circuit 100 are acquired through the sampling circuit 200, the voltage deviation is determined through the subtracter 310 to calculate the target output voltage and the current output voltage of the BUCK circuit 100, the notch controller 320 performs notch processing according to the voltage deviation to obtain a target duty ratio, and the PWM signal generator 330 generates a PWM signal according to the target duty ratio to drive the BUCK circuit 100 to work and output the target output voltage. According to the method and the device, the preset notch frequency is determined according to the resonant frequency, and the notch controller 320 obtains the target duty ratio for removing the influence of the resonant frequency based on the preset notch frequency, so that the gain of the BUCK circuit 100 is quickly attenuated at the resonant frequency point, the resonant peak of the BUCK circuit 100 is effectively restrained, and the dynamic performance of the circuit is improved.
In one embodiment, when the operating frequency is less than the resonant frequency, the gain of notch controller 320 decays at a first decay rate as the operating frequency increases;
when the operating frequency is greater than the resonant frequency, the gain of notch controller 320 decays at a second decay rate as the operating frequency increases;
wherein the second decay rate is greater than the first decay rate.
In this embodiment, in the control system of the BUCK circuit 100, a low frequency high gain and a high frequency fast attenuation are generally required to ensure the dynamic performance of the BUCK circuit 100. Thus, at different operating frequencies, the control gain is required to attenuate at different attenuation rates. For example, a smaller first decay rate is set at a low frequency band less than the resonance frequency to ensure a high gain at the low frequency band. The resonance frequency is a point at which the notch controller 320 rapidly decays, and the preset notch frequency may be set to be the same as or near the resonance frequency of the BUCK circuit 100 to effectively suppress the resonance peak in the loop.
Due to the characteristics of the notch controller 320, the amplitude-frequency characteristic may be tilted upward in the high frequency band of the notch controller 320. The second larger attenuation rate can be set in the high frequency band larger than the resonance frequency to increase the attenuation rate of the high frequency band and inhibit the amplitude-frequency characteristic of the high frequency band.
In one embodiment, the transfer function of notch controller 320 is:
wherein G is ctrl (s) is the target gain, k is the gain coefficient, ε is the damping coefficient, ω n For presetting notch frequency, s and omega n Is a pair of conjugate zero points,pole zero, p 1 Is a notch coefficient>Is p 1 Is a pole of (c).
As shown in fig. 3, (1) is a bode diagram of the notch controller 320, (2) is a bode diagram of the controlled object (i.e., the BUCK circuit 100) (corresponding to fig. 2), and (3) is a bode diagram of the closed loop system (i.e., a loop bode diagram after being controlled by the notch controller 320).
The numerator of the transfer function of notch controller 320 includes a pair of conjugate zeros s and omega n . k is used to control the initial gain of the trap, i.e. the height of point a in control (1), the larger k the higher point a. And the sum of the initial gain of the notch controller 320 and the initial gain of the controlled object is the initial gain of the closed loop system, that is, the sum of the point a value in (1) and the point B value in (2) is equal to the point C value in (3). To stabilize the controlled loop, the C point value needs to be set to be greater than a predetermined gain (e.g., 40 dB).
The transfer function also comprises damping coefficient epsilon in the molecule, and epsilon can be in the range of 0-1. By setting a suitable value of epsilon (e.g., epsilon=0.14), the damping of the control system of BUCK circuit 100 can be increased, and the bandwidth of notch controller 320 can be increased, as shown in fig. 5.
Due to the characteristics of the notch controller 320, the amplitude-frequency characteristic at the high frequency band (i.e., the second half of fig. 3) higher than the resonance frequency is raised to increaseAdding the gain attenuation coefficient of the high frequency band of the part, introducing a zero pole (i.e. 1/s) and a p in the denominator 1 Is a function of the pole of (i.e.,) So that the gain of notch controller 320 begins to attenuate the loop at an initial attenuation rate, at p, at a frequency of 0 1 The point is attenuated at a first attenuation rate before p 1 The decay is started at a second decay rate, and the second decay rate at this time is higher than the initial decay rate and the first decay rate.
Wherein p is 1 The point may be set and adjusted according to the resonant frequency to cooperate with the pole-zero so that the gain of notch controller 320 may begin to decay rapidly at that point, increasing the attenuation coefficient of notch controller 320 at the high frequency band.
The application also proposes an energy storage device comprising the voltage conversion device 10 described above.
The detailed structure of the voltage conversion device 10 can refer to the above embodiment, and will not be described herein; it can be understood that, because the above-mentioned voltage conversion device 10 is used in the energy storage device of the present application, the embodiments of the energy storage device of the present application include all the technical solutions of all the embodiments of the above-mentioned voltage conversion device 10, and the achieved technical effects are also identical, and are not described herein again.
Hereinabove, the specific embodiments of the present application are described with reference to the accompanying drawings. However, those of ordinary skill in the art will understand that various changes and substitutions can be made in the specific embodiments of the present application without departing from the spirit and scope of the present application. Such modifications and substitutions are intended to be within the scope of the present application.

Claims (10)

1. A control method of a BUCK circuit, the method comprising:
acquiring the current input voltage, the current output voltage, the target output voltage and the resonance frequency of the BUCK circuit;
calculating according to the target output voltage and the current output voltage to obtain voltage deviation;
carrying out notch processing on the voltage deviation to obtain a target duty ratio; the notch processing is based on a preset notch frequency, and the preset notch frequency is determined according to the resonance frequency of the BUCK circuit;
generating a PWM signal according to the target duty ratio and outputting the PWM signal to the BUCK circuit; the PWM signal is used for controlling the BUCK circuit to convert the current input voltage and then output the target output voltage.
2. The method of claim 1, wherein said calculating a voltage deviation from said target output voltage and said current output voltage comprises:
subtracting the current output voltage from the target output voltage to obtain the voltage deviation.
3. The method of claim 1, wherein the notching the voltage deviation to a target duty cycle comprises:
acquiring the working frequency of the BUCK circuit;
when the working frequency is smaller than the resonant frequency, controlling the gain in the notch processing to attenuate at a first attenuation rate, wherein the first attenuation rate is inversely related to the working frequency; carrying out notch processing after gain attenuation on the voltage deviation to obtain a target duty ratio;
when the working frequency is larger than the resonant frequency, controlling the gain in the notch processing to attenuate at a second attenuation rate, wherein the second attenuation rate is inversely related to the working frequency; carrying out notch processing after gain attenuation on the voltage deviation to obtain a target duty ratio;
wherein the second decay rate is greater than the first decay rate.
4. A method according to claim 3, wherein the notching the voltage deviation based on a preset notch frequency comprises:
and inputting the voltage deviation into a notch controller based on a preset notch frequency to perform notch processing.
5. The method of claim 4, wherein the transfer function of the notch controller is:
wherein G is ctrl (s) is the target gain, k is the gain coefficient, ε is the damping coefficient, ω n For presetting notch frequency, s and omega n Is a pair of conjugate zero points,pole zero, p 1 Is a notch coefficient>Is p 1 Is a pole of (c).
6. The method of claim 1, wherein the predetermined notch frequency is equal to the resonant frequency.
7. The voltage conversion device is characterized by comprising a BUCK circuit, a sampling circuit and a voltage loop control circuit; the voltage loop control circuit comprises a subtracter, a notch controller and a PWM signal generator;
the sampling circuit is used for collecting the current input voltage and the current output voltage of the BUCK circuit;
the subtracter is used for receiving the current output voltage output by the sampling circuit, receiving a target output voltage and calculating to obtain voltage deviation according to the target output voltage and the current output voltage;
the notch controller is used for receiving the voltage deviation and carrying out notch processing on the voltage deviation to obtain a target duty ratio; the preset notch frequency of the notch controller is determined according to the resonance frequency of the BUCK circuit;
the PWM signal generator is used for receiving the target duty ratio and generating a PWM signal to the BUCK circuit according to the target duty ratio;
the BUCK circuit is used for working under the control of the PWM signal so as to convert the input voltage and then output the target output voltage.
8. The voltage conversion device according to claim 7, wherein,
when the working frequency is smaller than the resonant frequency, the gain of the notch controller is attenuated at a first attenuation rate along with the increase of the working frequency;
when the working frequency is larger than the resonant frequency, the gain of the notch controller is attenuated at a second attenuation rate along with the increase of the working frequency;
wherein the second decay rate is greater than the first decay rate.
9. The voltage conversion device according to claim 8, wherein the transfer function of the notch controller is:
wherein G is ctrl (s) is the target gain, k is the gain coefficient, ε is the damping coefficient, ω n For presetting notch frequency, s and omega n Is a pair of conjugate zero points,pole zero, p 1 Is a notch coefficient>Is p 1 Is a pole of (c).
10. An energy storage device, characterized in that it comprises a voltage conversion device according to any one of claims 7-9.
CN202310315098.9A 2023-03-27 2023-03-27 Control method of BUCK circuit, voltage conversion device and energy storage equipment Pending CN116455210A (en)

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