CN109217696B - Direct-current voltage closed-loop control method and system of single-phase converter - Google Patents

Direct-current voltage closed-loop control method and system of single-phase converter Download PDF

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CN109217696B
CN109217696B CN201710538728.3A CN201710538728A CN109217696B CN 109217696 B CN109217696 B CN 109217696B CN 201710538728 A CN201710538728 A CN 201710538728A CN 109217696 B CN109217696 B CN 109217696B
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voltage
loop
closed
phase converter
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CN109217696A (en
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许峻峰
张志学
王跃
罗文广
刘勇
胡景瑜
付刚
孙璐
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CRRC Zhuzhou Institute 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
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/02—Conversion of ac power input into dc power output without possibility of reversal
    • H02M7/04—Conversion of ac power input into dc power output without possibility of reversal by static converters
    • H02M7/12—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/21—Conversion of ac power input into dc power output without possibility of reversal 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
    • H02M7/217—Conversion of ac power input into dc power output without possibility of reversal 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
    • 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
    • H02M1/00—Details of apparatus for conversion
    • H02M1/0003—Details of control, feedback or regulation circuits

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Abstract

The invention discloses a direct current voltage closed-loop control method and a direct current voltage closed-loop control system of a single-phase converter, wherein voltage feedback signals of the direct current side of the single-phase converter passing through a moving average filter serving as a feedback link are acquired; performing closed-loop control according to the voltage feedback signal and a preset voltage based on a pre-established transmission model of the single-phase converter voltage outer ring closed-loop system; the transmission model comprises a feedback delay link, a PI controller, a current inner loop closed-loop system transmission model and a controlled object model; the integral time constant of the PI controller is greater than the integral time constant of the feedback delay link; the transfer model open loop cutoff frequency is a frequency set based on the current inner loop response speed being much greater than the voltage outer loop response speed. This application is through introducing the moving average filter as voltage loop feedback link, and effective secondary pulsation component of separation voltage signal avoids secondary pulsation component to enter the voltage loop, eliminates secondary pulsation's adverse effect and guarantees the control stability of system.

Description

Direct-current voltage closed-loop control method and system of single-phase converter
Technical Field
The invention relates to the field of power electronics and power transmission, in particular to a direct-current voltage closed-loop control method and a direct-current voltage closed-loop control system for a single-phase converter.
Background
Single-phase converters are used in a wide variety of applications, for example in particular for supplying power to trains. The train power supply traction converter network side part (also called a four-quadrant converter) mainly realizes that the electric energy of a railway power supply contact network is introduced into a train through a pantograph so as to provide the electric energy for the train.
The four-quadrant converter converts the single-phase alternating current input voltage which is subjected to voltage reduction by the main transformer into direct current voltage to supply to the middle direct current loop. For a single-phase alternating current system, secondary pulsation of input power of the four-quadrant converter can cause secondary pulsation of direct-current side voltage.
In order to eliminate the influence of the secondary pulsation of the direct-current voltage, the secondary pulsation component is generally filtered in engineering by adding a hardware RC low-pass filtering link in a sampling circuit, adding a digital wave trap or a low-pass filter in a control system and the like. However, the RC filtering step makes the sampling circuit complicated, and the filtering effect is greatly affected by the consistency of the components, the temperature drift, and the like; the digital wave trap has single trap frequency generally, and can not filter out harmonic waves except secondary pulsation; the digital second-order low-pass filter is easy to cause dynamic lag to reduce the system stability due to the narrow frequency band. In summary, how to effectively eliminate the adverse effect of the secondary pulsation on the dc side of the single-phase ac converter system and ensure the control stability of the system is an urgent problem to be solved in the art.
Disclosure of Invention
The invention aims to provide a direct-current voltage closed-loop control method and a direct-current voltage closed-loop control system for a single-phase converter, and aims to solve the problem that the prior art cannot effectively eliminate the adverse effect of secondary pulsation on the direct-current side of a single-phase alternating-current converter system.
In order to solve the above technical problem, the present invention provides a closed-loop control method for a dc voltage of a single-phase converter, the method comprising:
collecting voltage feedback signals of a direct current side of the single-phase converter passing through a moving average filter serving as a feedback link of a voltage outer loop closed-loop system of the single-phase converter;
based on a pre-established transmission model of the single-phase converter voltage outer ring closed-loop system, carrying out closed-loop control on the single-phase converter voltage outer ring closed-loop system according to the voltage feedback signal and a preset voltage;
the transmission model comprises a first-order equivalent inertia feedback delay link introduced by the moving average filter, a PI controller, a current inner loop closed-loop system transmission model and a transmission model of a controlled object model; the integral time constant of the PI controller is larger than that of the first-order equivalent inertia feedback delay link; the open-loop cutoff frequency of the transfer model is a frequency set based on the current inner loop response speed being much greater than the voltage outer loop response speed.
Optionally, the acquiring a voltage feedback signal on the dc side of the single-phase converter passing through a moving average filter as a feedback link of a voltage outer loop closed-loop system of the single-phase converter includes:
acquiring a preset sliding window time of the moving average filter;
collecting the voltage feedback signal according to the preset sliding window time;
wherein the preset sliding window time is 0.01s or 0.02 s.
Optionally, the first-order equivalent inertial feedback delay element is
Figure BDA0001341315850000021
Wherein the content of the first and second substances,
Figure BDA0001341315850000022
Twand the preset sliding window time is obtained.
Optionally, the transfer model is
Figure BDA0001341315850000023
Wherein, the PI controller is
Figure BDA0001341315850000024
The controlled object model is
Figure BDA0001341315850000025
UdcrefTo the preset voltage, UsIs the phase voltage amplitude, CdcThe total capacitance capacity of the direct current side.
Optionally, an integration time constant T of the PI controllerIFor integrating time constant T of the first-order equivalent inertia feedback delay elementFCalculated by multiplying a predetermined valueThe value range of the preset value is [2, 5 ]]。
In addition, the invention also provides a direct-current voltage closed-loop control system of the single-phase converter, which comprises the following components:
the voltage feedback signal acquisition module is used for acquiring a voltage feedback signal of the direct current side of the single-phase converter passing through a moving average filter serving as a feedback link of a voltage outer loop closed-loop system of the single-phase converter;
the control module is used for carrying out closed-loop control on the voltage outer ring closed-loop system of the single-phase converter according to the voltage feedback signal and preset voltage based on a pre-established transmission model of the voltage outer ring closed-loop system of the single-phase converter;
the transmission model comprises a first-order equivalent inertia feedback delay link introduced by the moving average filter, a PI controller, a current inner loop closed-loop system transmission model and a transmission model of a controlled object model; the integral time constant of the PI controller is larger than that of the first-order equivalent inertia feedback delay link; the open-loop cutoff frequency of the transfer model is a frequency set based on the current inner loop response speed being much greater than the voltage outer loop response speed.
Optionally, the voltage feedback signal acquisition module includes:
a preset sliding window time obtaining unit, configured to obtain a preset sliding window time of the moving average filter;
the acquisition unit is used for acquiring the voltage feedback signal according to the preset sliding window time;
wherein the preset sliding window time is 0.01s or 0.02 s.
Optionally, the first-order equivalent inertial feedback delay element is
Figure BDA0001341315850000031
Wherein the content of the first and second substances,
Figure BDA0001341315850000032
Twand the preset sliding window time is obtained.
Optionally, the transferringThe model is
Figure BDA0001341315850000033
Wherein, the PI controller is
Figure BDA0001341315850000034
The controlled object model is
Figure BDA0001341315850000035
UdcrefTo the preset voltage, UsIs the phase voltage amplitude, CdcThe total capacitance capacity of the direct current side.
Optionally, an integration time constant T of the PI controllerIFor integrating time constant T of the first-order equivalent inertia feedback delay elementFMultiplying a preset value to obtain a value, wherein the value range of the preset value is [2, 5 ]]。
According to the direct-current voltage closed-loop control method and system of the single-phase converter, voltage feedback signals of the direct-current side of the single-phase converter are acquired through a moving average filter serving as a feedback link of a voltage outer loop closed-loop system of the single-phase converter; based on a pre-established transmission model of the single-phase converter voltage outer ring closed-loop system, carrying out closed-loop control on the single-phase converter voltage outer ring closed-loop system according to the voltage feedback signal and the preset voltage; the transfer model comprises a first-order equivalent inertia feedback delay link introduced by a moving average filter, a PI controller, a current inner loop closed-loop system transfer model and a transfer model of a controlled object model; the integral time constant of the PI controller is larger than that of the first-order equivalent inertia feedback delay link; the open-loop cutoff frequency of the transfer model is a frequency set based on the current inner loop response speed being much greater than the voltage outer loop response speed. According to the voltage loop feedback method and device, the moving average filter is introduced to serve as a voltage loop feedback link, secondary pulsation components and other order ripples of the voltage signal are effectively separated, the secondary pulsation components are prevented from entering the voltage loop, and adverse effects of secondary pulsation are eliminated; and the influence of the introduction of a moving average filter on the stability of the system is avoided by setting the integral time constant of the PI controller and the open-loop cut-off frequency of the voltage loop, and the stability of the voltage closed-loop control is improved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.
Fig. 1 is a schematic flowchart of a specific implementation of a closed-loop control method for dc voltage of a single-phase converter according to an embodiment of the present invention;
fig. 2 is a block diagram of a voltage and current dual-loop control system of a train power supply four-quadrant converter according to an embodiment of the present invention;
fig. 3 is a graph showing the frequency characteristics of the moving average filter, the equivalent inertia element, and the trap according to the embodiment of the present invention;
FIG. 4 is a closed loop diagram of a voltage control outer loop of a four-quadrant converter of a train according to an embodiment of the present invention;
fig. 5 is a main circuit topology diagram of a single-phase train power supply converter provided by the embodiment of the invention;
FIG. 6 is a diagram illustrating the waveforms and harmonic content distributions of the DC side voltage with and without the filter network according to an embodiment of the present invention;
FIG. 7 is a diagram of a DC side total voltage waveform provided by an embodiment of the present invention;
fig. 8 is a block diagram of a dc voltage closed-loop control system of a single-phase converter according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 1, fig. 1 is a schematic flow chart of an embodiment of a closed-loop control method for dc voltage of a single-phase converter according to the present invention, the method includes the following steps:
step 101: and acquiring a voltage feedback signal of the direct current side of the single-phase converter through a moving average filter serving as a feedback link of a voltage outer loop closed-loop system of the single-phase converter.
It can be understood that the single-phase converter voltage outer ring closed loop system may specifically be a train power supply four-quadrant closed loop control system, and the control system is a double-loop control system including a voltage outer ring and a current inner ring, and specifically, refer to fig. 2, where fig. 2 is a block diagram of a train power supply four-quadrant converter voltage and current double-loop control system provided in an embodiment of the present invention.
As shown in FIG. 2, the control system includes an inner ring and an outer ring, the outer ring is a voltage ring, wherein udcFor feedback of DC side voltage, UdcrefIn order to track the voltage reference value, the output of the voltage loop PI controller is used as the amplitude I of the current inner loop reference values *Multiplying by a phase-locked loop P LL to obtain a grid voltage synchronous signal sin theta and obtaining a current reference instantaneous value is *Meanwhile, the current at the side of the feedback network is tracked by a proportional resonant PR controller; the output of the current inner loop and the feedforward power grid voltage are used as a converter voltage modulation instruction, and then a driving pulse is obtained through a proper modulation strategy to control the four-quadrant converter to normally operate according to an expected target. The difference value of the two capacitor voltages can be used as the input of a voltage balance single-proportion P regulator, and the output of the regulator is introduced into a current control loop to realize the balance of the midpoint voltage; maf (moving Average filter) is an introduced moving Average filter.
Of course, the single-phase converter voltage outer loop closed-loop system may be embodied as not only the single-phase train traction converter based on the diode-clamped three-level topology shown in fig. 2, but also a single-phase converter system based on other topologies, which is not limited herein.
In particular, the temporal model of the MAF may be embodied as
Figure BDA0001341315850000051
x (T), y (T) are input and output signals of the moving average filter, TwA single sliding window time for the moving average filter.
The s-domain model of the MAF can be obtained by performing Laplace change on the MAF time-domain model, specifically, the S-domain model is
Figure BDA0001341315850000052
The s-domain transfer function of MAF is obtained as
Figure BDA0001341315850000053
And a delay element exists in the MAF transfer function
Figure BDA0001341315850000054
The frequency characteristic of the system is difficult to be visually analyzed, so that the Pade approximation equation can be utilized
Figure BDA0001341315850000055
Performing equivalence to obtain an equivalent transfer function of
Figure BDA0001341315850000056
Wherein the content of the first and second substances,
Figure BDA0001341315850000057
the filtering performance of the moving average filter and the second-order wave trap on the secondary pulsation is basically the same, and the moving average filter and the equivalent link are basically overlapped in a low-frequency band, so that the delay influence of the moving average filter on the low-frequency band signal can be completely equivalent by the equivalent link.
In order to verify that the delay influence of the moving average filter on the low frequency band can be equivalent and inertial links, respective frequency characteristic curve graphs can be drawn respectively. Specifically, referring to fig. 3, fig. 3 is a graph illustrating frequency characteristics of the moving average filter, the equivalent inertia element and the wave trap according to the embodiment of the present invention.
FIG. 3 shows the frequency characteristic curve of MAF, HMAFThe frequency characteristic curve of the Notch and the frequency characteristic curve of the Notch respectively correspond to the frequency characteristic curve of the moving average filter, the frequency characteristic curve of the inertia link and the frequency characteristic curve of the second-order wave trap. The filtering performance of the moving average filter and the second-order wave trap to the second pulsation (100Hz) is basically the same, but the second-order wave trap only has a wave trapping effect at the frequency, the moving average filter still has strong filtering capability at other harmonic frequencies, and the moving average filter and the equivalent link are basically superposed at a low frequency band, so that the delay influence of the moving average filter to the low frequency band signal can be completely equivalent by the inertia link.
According to the MAF time domain model, a discrete domain model of the MAF can be obtained, in particular to
Figure BDA0001341315850000061
Wherein, the sliding window of the moving average filter includes N pieces of sampling point information, namely Tw＝N×Tsamp，TsampIs the system sampling period.
The sliding window time of the moving average filter can be controlled to filter out different components. Therefore, as a specific implementation manner, the process of acquiring the voltage feedback signal at the dc side of the single-phase converter passing through the moving average filter as the feedback link of the voltage outer loop closed-loop system of the single-phase converter specifically includes: acquiring a preset sliding window time of the moving average filter; collecting the voltage feedback signal according to the preset sliding window time; wherein the preset sliding window time is 0.01s or 0.02 s.
The repetition period of the secondary pulsation component on the direct current side is half of the power frequency period, so the sliding window time of the sliding average filter can be set to be half of the construction period, and the secondary pulsation of the direct current voltage and integral multiple ripple waves thereof, namely T, can be filteredw＝0.01s。
When the grid voltage generates fixed other-order ripple waves due to factors such as harmonic waves or load fluctuation and the like, the sliding average can be filteredThe duration of the smoothing window is set to the power frequency period, i.e. Tw0.02s to eliminate the harmonic components of each order.
It can be seen that by setting different sliding window times, corresponding components are filtered out, so that secondary pulsation or other order harmonic components do not exist in the acquired direct-current side voltage feedback signal, and adverse effects caused by the secondary pulsation components or other order harmonic components are avoided.
Step 102: based on a pre-established transmission model of the single-phase converter voltage outer ring closed-loop system, carrying out closed-loop control on the single-phase converter voltage outer ring closed-loop system according to the voltage feedback signal and a preset voltage;
the transmission model comprises a first-order equivalent inertia feedback delay link introduced by the moving average filter, a PI controller, a current inner loop closed-loop system transmission model and a transmission model of a controlled object model; the integral time constant of the PI controller is larger than that of the first-order equivalent inertia feedback delay link; the open-loop cutoff frequency of the transfer model is a frequency set based on the current inner loop response speed being much greater than the voltage outer loop response speed.
Based on the train power supply four-quadrant converter voltage and current double-loop control system in fig. 2, the train four-quadrant converter voltage control outer loop closed-loop block diagram in fig. 4 can be obtained.
From the system block diagram shown in FIG. 4, in particular, a closed loop transfer function of the voltage control outer loop can be derived as
Figure BDA0001341315850000071
Wherein the PI controller is
Figure BDA0001341315850000072
The controlled object model is
Figure BDA0001341315850000073
UdcrefTo a predetermined voltage, UsIs the phase voltage amplitude, CdcThe total capacitance capacity of the direct current side.
It can be understood thatThe voltage loop is prevented from interfering the current loop, and the response time of the current loop is much shorter than that of the voltage loop, so that it can be considered that G in fig. 4s(s) is equal to 1. Furthermore, the tracking object of the single-phase converter direct-current side voltage outer ring is a direct-current component, the control bandwidth does not need to be very high, and the cut-off frequency of the direct-current side voltage outer ring system can be set to 1/4 of the secondary pulsation, namely the cut-off frequency can be set to about 25 Hz.
Based on the transfer function, the necessary condition for stabilizing the voltage control outer loop control is calculated by using the Laus criterion, namely, the characteristic equation 2CdcUdcrefTITFs3+2CdcUdcrefTIs2+KpKIUss+KpUs2C of coefficient in characteristic equation ═ 0dcUdcrefTIKpKIUs-2CdcUdcrefTITFKpUs> 0, T can then be calculatedI＞TF。
From the above, it can be seen that the integration time constant T is only determined when the DC side voltage PI controllerIIs greater than the equivalent inertia element time constant T of the moving average filterFThe system is stable.
Preferably, the integral time constant T of the PI controller is set to be smaller than the integral time constant T of the PI controllerIThe integral time constant T of the first-order equivalent inertia feedback delay element is usedFMultiplying a preset value to obtain a value, wherein the value range of the preset value is [2, 5 ]]. I.e. engineering can be used to transform TISet to 2 to 5 times TF。
In order to verify the feasibility of the direct-current side voltage secondary pulsation moving average filtering and the correctness of the voltage closed loop stability control design method, Matlab/Simulink software is adopted to build a simulation model of the single-phase train power supply converter shown in FIG. 5. Wherein, the effective value of the single-phase power grid voltage is 1.5kV, the fundamental frequency is 50Hz, the total voltage reference value of the direct current side is 3000V, and the direct current side capacitor C1＝C210mF, the grid side resistance and inductance were 0.1 Ω and 2.0mF, respectively, the load resistance was 9 Ω (rated power 1000kW), and the triangle was triangularCarrier frequency 2.5kHz, system sampling and control frequency f samp10 kHz. The schematic diagrams shown in fig. 6 and 7 can be derived.
Fig. 6 shows the grid-side current waveform and the harmonic content distribution when the dc-side voltage is unfiltered and the moving average filtering is adopted, and it can be seen that the Total Harmonic Distortion (THD) of the current after the moving average filtering is reduced from 3.16% to 1.59%, wherein the harmonics of 3, 5 and 7 are reduced from 2.70%, 0.64% and 0.25% to 0.46%, 0.37% and 0.13%, respectively, and the harmonic optimization effect is obvious.
Fig. 7 shows the dc-side total voltage waveform when the moving average filter is used: in a time period of T-0-0.2 s, TIIs maintained at 2TFThe overall voltage of the direct current side is stable; at time T equal to 0.2s, T is setISwitch to 0.5TFThe voltage is kept constant, and the stability of the overall voltage at the direct current side is poor and has an oscillation trend; until time T is equal to 0.7s, and then T is addedISwitch back to 2TFAnd the voltage is kept unchanged, and the overall voltage of the direct current side gradually recovers to be stable.
The direct-current voltage closed-loop control method of the single-phase converter provided by the embodiment is characterized in that a voltage feedback signal of a direct-current side of the single-phase converter is acquired through a sliding average filter serving as a feedback link of a voltage outer loop closed-loop system of the single-phase converter; based on a pre-established transmission model of the single-phase converter voltage outer ring closed-loop system, carrying out closed-loop control on the single-phase converter voltage outer ring closed-loop system according to the voltage feedback signal and the preset voltage; the transfer model comprises a first-order equivalent inertia feedback delay link introduced by a moving average filter, a PI controller, a current inner loop closed-loop system transfer model and a transfer model of a controlled object model; the integral time constant of the PI controller is larger than that of the first-order equivalent inertia feedback delay link; the open-loop cutoff frequency of the transfer model is a frequency set based on the current inner loop response speed being much greater than the voltage outer loop response speed. According to the method, the moving average filter is introduced as a voltage loop feedback link, secondary pulsation components and other order ripples of a voltage signal are effectively separated, the secondary pulsation components are prevented from entering the voltage loop, and adverse effects of secondary pulsation are eliminated; and the influence of the introduction of a moving average filter on the stability of the system is avoided by setting the integral time constant of the PI controller and the open-loop cut-off frequency of the voltage loop, and the stability of the voltage closed-loop control is improved.
In the following, the dc voltage closed-loop control system of the single-phase converter according to the embodiments of the present invention is introduced, and the dc voltage closed-loop control system of the single-phase converter described below and the dc voltage closed-loop control method of the single-phase converter described above may be referred to correspondingly.
Referring to fig. 8, fig. 8 is a block diagram of a dc voltage closed-loop control system of a single-phase converter according to an embodiment of the present invention.
The voltage feedback signal acquisition module 81 is used for acquiring a voltage feedback signal of the direct current side of the single-phase converter passing through a moving average filter serving as a feedback link of a voltage outer loop closed-loop system of the single-phase converter;
the control module 82 is used for carrying out closed-loop control on the voltage outer ring closed-loop system of the single-phase converter according to the voltage feedback signal and the preset voltage based on a pre-established transmission model of the voltage outer ring closed-loop system of the single-phase converter;
the transfer model comprises a first-order equivalent inertia feedback delay link introduced by a moving average filter, a PI controller, a current inner loop closed-loop system transfer model and a transfer model of a controlled object model; the integral time constant of the PI controller is larger than that of the first-order equivalent inertia feedback delay link; the open-loop cutoff frequency of the transfer model is a frequency set based on the current inner loop response speed being much greater than the voltage outer loop response speed.
As a specific implementation manner, the voltage feedback signal acquisition module may include:
a preset sliding window time obtaining unit, configured to obtain a preset sliding window time of the moving average filter;
the acquisition unit is used for acquiring a voltage feedback signal according to preset sliding window time;
wherein the preset sliding window time is 0.01s or 0.02 s.
As a specific embodiment, first orderThe equivalent inertia feedback delay link is
Figure BDA0001341315850000091
Wherein the content of the first and second substances,
Figure BDA0001341315850000092
Twis a preset sliding window time.
As a specific embodiment, the transfer model is
Figure BDA0001341315850000093
Wherein the PI controller is
Figure BDA0001341315850000094
The controlled object model is
Figure BDA0001341315850000095
UdcrefTo a predetermined voltage, UsIs the phase voltage amplitude, CdcThe total capacitance capacity of the direct current side.
As a specific embodiment, the integral time constant T of the PI controllerIThe integral time constant T of a first-order equivalent inertia feedback delay elementFMultiplying the preset value to obtain a value, wherein the value range of the preset value is [2, 5 ]]。
According to the direct-current voltage closed-loop control system of the single-phase converter, the moving average filter is introduced to serve as a voltage loop feedback link, secondary pulsation components and other order ripples of a voltage signal are effectively separated, the secondary pulsation components are prevented from entering the voltage loop, and adverse effects of secondary pulsation are eliminated; and the influence of the introduction of a moving average filter on the stability of the system is avoided by setting the integral time constant of the PI controller and the open-loop cut-off frequency of the voltage loop, and the stability of the voltage closed-loop control is improved.
The embodiments are described in a progressive manner in the specification, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. The device disclosed by the embodiment corresponds to the method disclosed by the embodiment, so that the description is simple, and the relevant points can be referred to the method part for description.
Those of skill would further appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both, and that the various illustrative components and steps have been described above generally in terms of their functionality in order to clearly illustrate this interchangeability of hardware and software. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.
The steps of a method or algorithm described in connection with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in Random Access Memory (RAM), memory, Read Only Memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art.
The dc voltage closed-loop control method and system of the single-phase converter provided by the present invention are described in detail above. The principles and embodiments of the present invention are explained herein using specific examples, which are presented only to assist in understanding the method and its core concepts. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention.

Claims (10)

1. A direct-current voltage closed-loop control method of a single-phase converter is characterized by comprising the following steps:
collecting voltage feedback signals of a direct current side of the single-phase converter passing through a moving average filter serving as a feedback link of a voltage outer loop closed-loop system of the single-phase converter;
based on a pre-established transmission model of the single-phase converter voltage outer ring closed-loop system, carrying out closed-loop control on the single-phase converter voltage outer ring closed-loop system according to the voltage feedback signal and a preset voltage;
the transmission model comprises a first-order equivalent inertia feedback delay link introduced by the moving average filter, a PI controller, a current inner loop closed-loop system transmission model and a transmission model of a controlled object model; the integral time constant of the PI controller is larger than that of the first-order equivalent inertia feedback delay link; the open-loop cutoff frequency of the transfer model is a frequency set based on the current inner loop response speed being much greater than the voltage outer loop response speed.
2. The dc voltage closed-loop control method of claim 1, wherein the collecting the voltage feedback signal of the dc side of the single-phase converter passing through the moving average filter as the feedback element of the voltage outer loop closed-loop system of the single-phase converter comprises:
acquiring a preset sliding window time of the moving average filter;
collecting the voltage feedback signal according to the preset sliding window time;
wherein the preset sliding window time is 0.01s or 0.02 s.
3. The closed-loop control method of DC voltage according to claim 2, wherein the first-order equivalent inertia feedback delay element is
Figure FDA0002528494060000011
Wherein the content of the first and second substances,
Figure FDA0002528494060000012
TFis the integral time constant, T, of the first-order equivalent inertial feedback delay elementwAnd the preset sliding window time is obtained.
4. The DC voltage closed-loop control method according to claim 3, wherein the transfer model is
Figure FDA0002528494060000013
Wherein, the PI controller is
Figure FDA0002528494060000014
The controlled object model is
Figure FDA0002528494060000015
UdcrefTo the preset voltage, UsIs the phase voltage amplitude, CdcIs the total capacitance capacity, T, of the DC sideIIs the integration time constant in the PI controller.
5. The DC voltage closed-loop control method according to claim 4, wherein an integration time constant T of the PI controllerIFor integrating time constant T of the first-order equivalent inertia feedback delay elementFMultiplying a preset value to obtain a value, wherein the value range of the preset value is [2, 5 ]]。
6. A direct current voltage closed-loop control system of a single-phase converter is characterized by comprising the following components:
the voltage feedback signal acquisition module is used for acquiring a voltage feedback signal of the direct current side of the single-phase converter passing through a moving average filter serving as a feedback link of a voltage outer loop closed-loop system of the single-phase converter;
the control module is used for carrying out closed-loop control on the voltage outer ring closed-loop system of the single-phase converter according to the voltage feedback signal and preset voltage based on a pre-established transmission model of the voltage outer ring closed-loop system of the single-phase converter;
the transmission model comprises a first-order equivalent inertia feedback delay link introduced by the moving average filter, a PI controller, a current inner loop closed-loop system transmission model and a transmission model of a controlled object model; the integral time constant of the PI controller is larger than that of the first-order equivalent inertia feedback delay link; the open-loop cutoff frequency of the transfer model is a frequency set based on the current inner loop response speed being much greater than the voltage outer loop response speed.
7. The dc voltage closed-loop control system of claim 6, wherein the voltage feedback signal acquisition module comprises:
a preset sliding window time obtaining unit, configured to obtain a preset sliding window time of the moving average filter;
the acquisition unit is used for acquiring the voltage feedback signal according to the preset sliding window time;
wherein the preset sliding window time is 0.01s or 0.02 s.
8. The closed-loop control system for DC voltage according to claim 7, wherein the first-order equivalent inertia feedback delay element is
Figure FDA0002528494060000021
Wherein the content of the first and second substances,
Figure FDA0002528494060000022
TFis the integral time constant, T, of the first-order equivalent inertial feedback delay elementwAnd the preset sliding window time is obtained.
9. The DC voltage closed loop control system of claim 8, wherein the transfer model is
Figure FDA0002528494060000023
Wherein, the PI controller is
Figure FDA0002528494060000024
The controlled object model is
Figure FDA0002528494060000025
UdcrefTo the preset voltage, UsIs the phase voltage amplitude, CdcIs the total capacitance capacity, T, of the DC sideIIs the integration time constant in the PI controller.
10. The dc voltage closed-loop control system of claim 9, wherein the integral time constant T of the PI controllerIFor integrating time constant T of the first-order equivalent inertia feedback delay elementFMultiplying a preset value to obtain a value, wherein the value range of the preset value is [2, 5 ]]。
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