CN115566684A - Control method of harmonic compensation circuit - Google Patents

Control method of harmonic compensation circuit Download PDF

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Publication number
CN115566684A
CN115566684A CN202211390460.0A CN202211390460A CN115566684A CN 115566684 A CN115566684 A CN 115566684A CN 202211390460 A CN202211390460 A CN 202211390460A CN 115566684 A CN115566684 A CN 115566684A
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current
voltage
controller
harmonic
circuit
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刘雪山
王春涛
张荣飞
谭志浩
奉榆杰
王一帆
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Sichuan University
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Sichuan University
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/01—Arrangements for reducing harmonics or ripples
    • 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
    • H02M1/143—Arrangements for reducing ripples from dc input or output using compensating arrangements
    • 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
    • H02M1/42—Circuits or arrangements for compensating for or adjusting power factor in converters or inverters
    • 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
    • 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
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
    • Y02E40/20—Active power filtering [APF]

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Supply And Distribution Of Alternating Current (AREA)

Abstract

The invention discloses a control method of a harmonic compensation circuit, which comprises a power circuit part and a control method part, wherein the power circuit part is a Boost type power factor correction circuit and consists of a rectifier bridge, an n-shaped filter circuit, a Boost circuit and an output filter link; the control method part comprises a voltage and current double closed-loop control loop and a reference current generation module containing harmonic compensation signals, wherein the current controller is designed to be formed by combining an embedded repetitive controller and a single zero-single pole compensator, and the reference current generation module comprises a band-pass filter with the center frequency of 50Hz and a repetitive controller. According to the invention, on the premise of not adding an additional sampling circuit, by sampling the input voltage, the converter realizes a power factor correction function, and simultaneously compensates the harmonic current flowing into the power grid from the public coupling point, and the reference current signal can be generated in a self-adaptive manner for different power grid impedances, so that the harmonic current flowing into the power grid is reduced.

Description

Control method of harmonic compensation circuit
Technical Field
The invention belongs to the technical field of power converters, and particularly relates to a control method of a harmonic compensation circuit.
Background
With the large number of applications of power electronic devices, harmonic pollution caused by nonlinear loads in commercial or residential power distribution networks is characterized by wide-area and decentralized application. Harmonic waves with complex and variable components threaten the safe and stable operation of a power grid, and can cause a series of hazards such as heating of a power transformer and a cable, increase of the loss of a power grid line, unstable operation of a sensitive load and the like.
In order to realize the harmonic wave treatment of the local distribution network, various harmonic wave treatment modes are continuously proposed. As a main harmonic suppression method, a control strategy, a topological structure, and the like of a parallel active power filter have been studied in a large amount. The topology of a three-phase active power filter is shown in fig. 1, whereS 1 ~S 6 Is a switching tube of each bridge arm,C o is a voltage-stabilizing capacitor at the direct-current side,L a ，L b ，L c is the input inductance. By active power filters by collecting input current to non-linear loadi na ，i nb ，i nc And outputting corresponding harmonic compensation current according to the collected harmonic informationi ca ，i cb ，i cc Reducing the grid currenti ga ，i gb ，i gc The purpose of harmonic compensation is achieved.
However, the parallel active power filters are connected to the power distribution network, additional equipment cost needs to be added, and the parallel active power filters mostly adopt a mode of centralized harmonic control, so that the control effect on scattered harmonic sources in the power distribution network is limited. Now, in order to reduce the cost of equipment access, attempts have been made to provide harmonic compensation functions for equipment that is inherently present in the power distribution network. With the development of new energy technology, the number of distributed power generation systems such as photovoltaic power generation systems and wind power generation systems in power distribution networks increases year by year, and many scholars at home and abroad propose to control dispersed harmonic sources by using the distributed power generation systems, however, in practical application, the compensation capacity and the installation place of the distributed power generation systems are greatly influenced by natural factors such as illumination, wind speed and geographical position.
Nowadays, PFC converters are widely applied to the fields of variable frequency air conditioners, automobile charging piles, LED lighting and the like, and in recent years, development strategies of safety, high quality and sustainable electric power are advocated in China, and the proportion of PFC type loads in a power grid is also increased year by year. At present, research on the PFC converter only considers that the converter is a resistive load for a power grid, and harmonic current flowing into the power grid from a public coupling point cannot be reduced. Because the PFC converter is widely distributed in a power grid, the output power is relatively stable along with the time conversion, and the input current of the PFC converter is controllable, the harmonic compensation current can be added into the input current to compensate the harmonic current flowing into the power grid at the public coupling point.
Disclosure of Invention
In order to solve the above problems, the present invention provides a method for controlling a harmonic compensation circuit.
The invention relates to a control method of a harmonic compensation circuit, which consists of a power circuit part and a control method part.
The power circuit part is a Boost type power factor correction circuit and comprises a rectifier bridge, a pi-shaped filter circuit, a Boost circuit and an output filter link. Wherein the rectifying link is composed of a diodeD 1 ~D 4 The formed rectifier bridge is used for converting input alternating voltage into direct voltage. The filter network adopts n-type filter network and comprises filter inductorL f Filter capacitorC f1 、C f2 Constructed to significantly reduce input currenti in In the input voltage and reduce the ripplev in Is fluctuating. Boost circuit is by inductance that steps upL m MOS transistorQ 1 Free wheeling diodeD 5 The boost function is realized. The output filtering link consists of 2 electrolytic capacitorsC o1 ，C o2 Is constructed to ensure output voltagev o The stability of (2) is improved,and reduce the output voltagev o The ripple of (3).
The power circuit part is specifically as follows: diode with a high-voltage sourceD 1 And a positive electrode ofD 3 The negative electrodes of the two electrodes are connected with each other,D 2 a positive electrode ofD 4 The negative electrodes of the two electrodes are connected with each other,D 1 and a negative electrode ofD 2 The negative electrodes of the two electrodes are connected with each other,D 3 and a positive electrode ofD 4 The positive electrodes of the two rectifier circuits are connected to form a rectifier bridge; filter capacitorC f1 One terminal of and filter inductorL f The connection is carried out in a connecting way,L f another terminal of (1) and a filter capacitorC f2 One end of the n-shaped filter circuit is connected to form an n-shaped filter circuit, and is connected with the output end of the rectifier bridge; pi-type filter circuit and MOS transistorQ 1 Excitation inductorL m Freewheel diodeD 5 The formed Boost circuits are connected; capacitor of two output filtering linksC o1 、C o2 Connected in parallel and connected with a Boost circuit; output load and output capacitorC o1 、C o2 Are connected in parallel.
The control method part comprises a voltage and current double closed loop control loop and a reference current generation module containing a harmonic compensation signal.
The voltage and current double closed loop control converter works in an average current mode, and specifically comprises the following steps: reference voltagev ref And the output voltagev o After comparison, the obtained voltage error signalv err As voltage controllersG v (s) Is controlled by a voltage controller to output a voltagev o The stability of (2). When the converter realizes the harmonic compensation function, the voltage after the sampling bridgev in Absolute value is removed through zero-crossing detection, and input voltage is obtained through reductionv in Then extracted by a harmonic detection unitv in Harmonic component ofv in-h Generating a signal containing harmonic compensationv z Internal command voltage signalv c . Voltage controllerG v (s) Output of (2)V e And voltagev c The multiplication is carried out by the following steps,the result is a reference currenti ref And the inductance currenti Lm Compared to obtain a current error signali err As a current controllerG c (s) The inductor current is controlled by a current controlleri Lm The waveform of (2). Due to filter capacitance in average current mode controlC f And a filter inductorL f Presence of (2), input currenti in Is an inductive currenti Lm Average value in the switching period, so that the current controllerG c (s) Can indirectly control the input currenti in To makei in Including harmonic compensation currentsi in-h And further realize the harmonic compensation function.
The reference current generation module comprises a band-pass filter with the center frequency of 50Hz and a repetitive controller, and adaptively generates reference current under the condition of different power grid impedances, and specifically comprises the following steps:G a (s) As a controller, it only contains internal model link and gain link of repetitive controllerK h ，G b (s) Is a band-pass filter with a center frequency of 50 Hz; input voltagev in By sampling the voltage after the bridgev in Absolute value is removed through a program to obtain I; input voltagev in Through a band-pass filter G b (s) Then, an input voltage is obtainedv in Harmonic component ofv in-h Harmonic components ofv in_h As input to a repetitive controller, its outputv RC Andv in_h added and multiplied by a gainK h Obtaining a harmonic compensation signalv z ，v z Re-mixing with the fundamental componentv in_f Adding the sum to obtain absolute value, and outputting with voltage loopv e Multiplying to obtain a reference currenti ref . The purpose of this design is to reduce harmonic componentsv in_h As an error signal, the input voltage is converted into a voltagev in And fundamental component thereofv in_f Respectively as controlled object and reference signal, and combined with controllerG a (s) Implementing controlled objectsv in Following the upper reference signalv in_f . Under the condition of not knowing the impedance magnitude and the phase of the power grid, the controllerG a (s) To reducev in_h For the purpose of, according tov in_h Adaptively generating a harmonic compensation signalv z 。
In which the output voltage is guaranteedv o Is stabilized, the voltage controllerG v (s) Designed as a conventional proportional-integral controller. For ensuring control objects of current loopsi Lm Can quickly and accurately track the upper reference currenti ref Current controllerG c (s) The structure of (2) needs to be specially designed. Current controllerG c (s) The system is formed by combining an embedded repetitive controller and a single zero-single pole compensator, and specifically comprises the following steps:
by means of current through pair of inductorsi Lm Sampling and comparing with current reference signali ref Comparing to obtain a current error signali err And as an embedded repetitive controllerG RC (s) The input of (2); the embedded repetitive controller comprises an internal model link and a compensation link, whereinQ(s) In the form of a low-pass filter,G f (s) For the lead link, N =f s /f n ，f s In order to be able to sample the frequency,f n for the frequency of the power grid,T s in order to be the sampling period of time,k f is a constant; repeating the output of the controller and the error signali err After addition, the single zero point-single pole point compensator is usedG i (s) Finally, the single zero-single pole compensator outputs a duty ratio signald(ii) a Thus, the inductive current can be ensuredi Lm Can quickly and accurately track the reference current containing fundamental wave and each subharmonici ref The current loop of the converter has good dynamic characteristics and small enough steady-state error.
The beneficial technical effects of the invention are as follows:
1. according to the invention, by designing a new harmonic compensation circuit, on the premise of not adding an additional sampling circuit, the harmonic compensation current flowing into a power grid from a public coupling point is compensated by sampling the voltage of the public coupling point, namely the input voltage, and generating a corresponding reference signal containing the harmonic compensation signal according to the harmonic component information in the input voltage.
2. The invention improves the voltage and current double closed-loop control based on the Boost power factor correction converter topology, designs the current controller in a form of combining an embedded repetitive controller and a single zero-single pole compensator, can ensure that the inductive current can quickly and accurately track the reference current containing fundamental waves and each subharmonic, and ensures that the current loop of the converter has good dynamic characteristics and small steady-state error.
3. The invention designs a reference current generating module, adds a repetitive controller and a band-pass filter in the module, takes the harmonic component of the input voltage as an error signal, and takes the input voltage and the fundamental component thereof as a controlled object and a reference signal respectively, and can generate a harmonic compensation signal in a self-adaptive manner according to the change condition of the harmonic component by taking the harmonic component as the purpose of reducing the harmonic component under the condition of not knowing the impedance magnitude and the phase of a power grid.
Drawings
Fig. 1 is a topology of a three-phase active power filter.
Fig. 2 is a Boost type power factor correction circuit.
Fig. 3 is a voltage-current dual closed loop control loop.
Fig. 4 is a reference current generation module with harmonic compensation signals.
Fig. 5 is a control block diagram of the current controller.
Fig. 6 is a control block diagram of reference current generation.
Fig. 7 is a control program flow block diagram.
Fig. 8 is a schematic diagram of the implementation of harmonic compensation.
FIG. 9 is a diagram of the main current-voltage waveforms of the present invention.
FIG. 10 is an uncontrolled rectifier circuit.
Fig. 11 is an experimental waveform diagram in the conventional power factor correction mode.
Fig. 12 is an experimental waveform diagram in the harmonic compensation mode.
Fig. 13 is a key waveform diagram of a pfc converter.
Fig. 14 is a histogram of the harmonics of the grid current.
Fig. 15 is an experimental waveform diagram when the grid impedance is formed by connecting a resistor of 3.3 Ω and an inductor of 1mH in series.
Fig. 16 is an experimental waveform diagram when the grid impedance is made up of a resistance of 5 Ω.
Fig. 17 is an experimental waveform diagram when the grid impedance is connected in series by a resistance of 5 Ω and an inductance of 2 mH.
Detailed Description
The invention is described in further detail below with reference to the figures and the detailed description.
The invention relates to a control method of a harmonic compensation circuit, which consists of a power circuit part and a control method part.
The power circuit part is a Boost type power factor correction circuit and comprises a rectifier bridge, a pi-type filter circuit, a Boost circuit and an output filter link. Wherein the rectifying link is composed of a diodeD 1 ~D 4 The formed rectifier bridge is used for converting input alternating voltage into direct voltage. The filter network adopts n-type filter network and comprises filter inductorL f Filter capacitorC f1 、C f2 Constructed to significantly reduce input currenti in In the input voltage and reduce the ripplev in Is measured. Boost circuit is by inductance that steps upL m MOS transistorQ 1 Freewheeling diodeD 5 The boost function is realized. The output filtering link consists of 2 electrolytic capacitorsC o1 ，C o2 Is constructed to secure an output voltagev o And reduce the output voltagev o The ripple of (3).
As shown in fig. 2, the power circuit part specifically includes: diode with a high-voltage sourceD 1 And a positive electrode ofD 3 The negative electrodes of the two electrodes are connected with each other,D 2 and a positive electrode ofD 4 The negative electrodes of the two electrodes are connected with each other,D 1 and a negative electrodeD 2 Is connected with the negative electrode of the anode,D 3 a positive electrode ofD 4 The positive electrodes of the two rectifier circuits are connected to form a rectifier bridge; filter capacitorC f1 One terminal of (1) and filter inductorL f The connection is carried out by connecting the two parts,L f the other end of (2) and a filter capacitorC f2 One end of the n-shaped filter circuit is connected to form an n-shaped filter circuit and is connected with the output end of the rectifier bridge; pi-type filter circuit and MOS transistorQ 1 Excitation inductorL m Freewheel diodeD 5 The formed Boost circuits are connected; capacitor of two output filtering linksC o1 、C o2 Connected in parallel and connected with a Boost circuit; output load and output capacitorC o1 、C o2 Are connected in parallel.
The control method part comprises a voltage and current double closed loop control loop and a reference current generation module containing a harmonic compensation signal, which are respectively shown in fig. 3 and fig. 4. Voltage and current double closed loop control loop routing voltage controllerG v (s) Current controllerG c (s) Adder and multiplier. The reference current generation module containing harmonic compensation signal comprises a zero-crossing detection module, a harmonic detection module and a repetitive controllerG a (s) The adder and the absolute value operation.
The control method part comprises the following steps:
as can be seen from the control program flow diagram shown in fig. 7, when the control program starts to execute, it needs to be initialized. After initialization, the voltage after bridge is sampled once in each sampling periodv in | until |v in If | is not equal to 0, the harmonic compensation control routine is started. Each sampling period can count the voltage after the bridgev in L, inductive currenti Lm And an output voltagev o Sampling is carried out, the sampling value is compared with a protection fixed value, and when the sampling value is not in a normal operation range, a protection program is triggered. The protection program will signal the duty cycleThe number is forced to be 0, so that the MOS tubeQ 1 Normally closed, and the protection program can be exited only by manually resetting and initializing the protection program again. When the sampling value is in the normal operation range, the preset reference voltage is usedv ref Subtracting the sampled output voltagev o To obtain an error voltagev err Passing through a voltage controllerG v (s) That is, after the proportional-integral link, the output value of the voltage ring can be obtainedV e As shown in fig. 3.
Then, a program of a reference current generation module including a harmonic compensation signal is executed, and a control block diagram thereof is shown in fig. 6. First, the voltage after bridge is cut offv in Absolute value of | detecting non woven ray through zero-crossing detection programv in Zero point of | turning the waveform in half power frequency period every other half power frequency period, i.e. eliminating the non-woven clothv in Absolute value of | obtaining input voltagev in . Will be provided withv in As input to a second order band-pass filter, the band-pass filter outputv in Fundamental component ofv in-f By usingv in Subtracting the fundamental componentv in-f Obtaining harmonic componentsv in-h . The bandpass filter is of the form:
Figure DEST_PATH_IMAGE002
(1)
in the formula (I), the compound is shown in the specification,Q b in order to be the quality factor of the image,ω o for the center frequency angular frequency, 2 π × 50Hz was taken. Harmonic componentv in-h As an input to the repetitive controller, the repetitive controller outputs a signalv RC ，v RC And harmonic componentsv in-h After addition, multiplying by a gain factorK h Obtaining a harmonic compensation signalv z Then will bev z And fundamental componentv in-f After addition, the voltage ring output is multipliedV e Then obtaining a current reference signali ref . From the above, it can be seen thatG a (s) Is expressed as follows：
Figure DEST_PATH_IMAGE004
(2)
In the formula (I), the compound is shown in the specification,Qand(s) is a second-order low-pass filter, and the cut-off frequency is 4kHz to ensure the effect of harmonic compensation.K h Is a constant with admittance dimension.
When the input voltage isv in When the harmonic wave is contained, the input voltage can be accurately obtained after the filter of the band-pass filter is supposedv in Fundamental component ofv in_f Harmonic componentsv in_h Harmonic components can be combinedv in_h As an error signal, willv in Andv in_f respectively as controlled object and reference signal, and combined with controllerG a (s) Implementing controlled objectsv in Following the upper reference signalv in_f . Under the condition of not knowing the impedance magnitude and the phase of the power grid, the controllerG a (s) To reduce harmonic componentsv in_h For the purpose of, according tov in_h Adaptively generating harmonic compensation signalsv z . And due to the controllerG a (s) Comprises a repetitive controller whenv in_h When eventually reduced to close to 0, the output of the controller is repeatedv RC The signal is a periodic signal and does not change, and meanwhile, the repetitive controller can achieve a good tracking effect on the periodic signal.
From FIG. 7, a current reference signal is obtainedi ref Then, a current loop operation program is executed, and a control block diagram of a current loop is shown in fig. 5.i ref Subtracting the inductor currenti Lm To obtain an error currenti err ，i err As a repetitive controllerG RC (s) After the internal model link and the lead compensation link of the repetitive controller, the output of the repetitive controller is compared with the input of the controlleri err Added as a single zero-monopole compensatorG i (s) Is finally inputted byG i (s) Output duty ratio signald. Wherein the repetitive controllerG RC (s) The expression of (a) is as follows:
Figure DEST_PATH_IMAGE006
(3)
in the formula (I), the compound is shown in the specification,Q(s) In the form of a low-pass filter,k r in order to repeat the gain of the controller,G f (s) = the lead compensation link is a lead compensation link,min order to advance the number of beats,T s for the sampling period, N =f s /f n ，f s In order to be able to sample the frequency,f n is the grid frequency.
The principle of the invention for realizing harmonic compensation is explained with reference to fig. 8. Harmonic compensation of a distribution network with a PFC converter As shown in FIG. 8, the input voltage of the converterv in I.e. the pcc voltage. Due to the impedance of the networkZ g Existence of, grid currenti g Flows throughZ g Will generate a pressure drop, can be calculatedv in Comprises the following steps:
Figure DEST_PATH_IMAGE008
(4)
whereinv g For the network voltage, assuming sinusoidal voltage containing fundamental wave only, the harmonic wave generated by all nonlinear loads in the distribution network is equivalent to a harmonic currenti h Then grid currenti g Includedi h And input current of PFC converteri in ，i in Decomposable into fundamental componentsi in-f Harmonic componentsi in-h 。v in Harmonic component of (2)v in-h Mainly composed ofi h Andi in-h impedance of current flowing through the gridZ g And generating voltage drop, namely harmonic voltage. At the same time, the user can select the desired position,i in-f will also be produced on the fundamental componentA certain pressure drop occurs. Thus, can obtainv in Fundamental component ofv in-f And harmonic componentsv in-h Respectively as follows:
Figure DEST_PATH_IMAGE010
(5)
Figure DEST_PATH_IMAGE012
(6)
according to the formula (6), wheni in-h For is toi h When the compensation function is available, the compensation function is realized,v in-h will be reduced, andv in-h andi h are in an opposite relationship. Therefore, can extractv in Harmonic component of (2)v in-h By means of a controllerG a (s) Amplifying it in a certain proportion to generate harmonic compensation signalv z . To ensure that the PFC converter still has a high power factor, the power factor of the PFC converter is increasedv z Andv in-f adding and taking the absolute value to obtain a command voltage signalv c 。v c And withV e After being multiplied together, obtaini ref So that the input current of the converteri in Therein containi h Harmonic compensation current ofi in-h And the harmonic wave flowing into the power distribution network is compensated. The main current voltage waveform diagram is shown in fig. 9, where,i in contains ini h The harmonic compensation currents in opposite phases are,i in is composed ofi Lm Average value over the switching period.
The power circuit parameters of the embodiments of the present invention are shown in table 1.
TABLE 1 Power Circuit parameters
Figure DEST_PATH_IMAGE014
FIG. 10 shows the results of experimentsUncontrolled rectifying circuit, in which the capacitorC r =220 μ F and resistanceR r =1200 Ω and comprising a rectifier bridgeD b . Experiments were carried out with the connection shown in fig. 3, in which the network impedance consists of a 5 Ω resistor and a 1mH inductor connected in series. FIG. 11 is a waveform diagram of an experiment of a converter operating in a conventional PFC mode, which results in a grid current due to the non-linear load being connectedi g Greater distortion occurs when THD =12.453% wheni g Impedance of current flowing through the gridZ g When it comes tov in Also generates distortion whenv in THD =1.104%. Fig. 12 is a waveform diagram illustrating an experiment in which the converter operates in a harmonic compensation mode, since the PFC converter begins to perform a harmonic compensation function,i in including harmonic compensation current, so thati g Has a significant reduction in the distortion of (1.886%) and a THD reduction ofv in The THD of (a) is also reduced to 0.147%. The PF of the converter is 0.976 at this time, and the converter still has a higher PF value. FIG. 13 is a key waveform diagram of a PFC converter, in whichi ref And the DA chip is output after being scaled down. Visible inductor currenti Lm Better tracking the reference currenti ref And when operating in the harmonic compensation mode, the output voltage of the PFCv o The average value of the voltage ripple is 402V, no obvious distortion exists, the ripple size is 20V through measurement, the ripple rate of the output voltage is 4.975%, and therefore when the converter works in a harmonic compensation mode, the energy supply to the load is not affected. FIG. 14 is a grid currenti g Histogram of the harmonics of (1). Therefore, the reference current generation method based on the repetitive control can reducei g The harmonic content of (1).
Fig. 15, fig. 16 and fig. 17 are experimental waveform diagrams under different grid impedances. A 3.3 Ω resistor and a 1mH inductor are connected in series as the grid impedance of fig. 15, while the grid impedance of fig. 16, 17) is formed by connecting a 5 Ω resistor, a 5 Ω resistor and a 2mH inductor in series, respectively. Measured, the grid current under the three grid impedance conditionsi g Each of THD of (1)987%,1.913%,2.075%, the PFs of the PFC converters are 0.976,0.977, respectively. Compared with the experimental result shown in fig. 12, it can be shown that the control method provided by the present invention can adapt to the change of the grid impedance, and improve the current THD value flowing into the grid from the public coupling point.
The invention provides a control method of a harmonic compensation circuit, which utilizes the characteristic that the input current of a power factor correction converter is controllable to enable the power factor correction converter to generate harmonic compensation current to compensate the harmonic current flowing into a power grid from a public coupling point. In order to realize the compensation of the Boost type power factor correction converter to the harmonic current, the invention designs the input current controller containing an embedded repetitive control link and single zero-single pole compensation, ensures that the input current of the converter accurately tracks the upper reference current, and adds the repetitive controller in the reference current signal generation link, so that the input impedance of the converter under each subharmonic frequency is reduced, and the converter is ensured to have good compensation effect on the harmonic current.

Claims (2)

1. A control method of a harmonic compensation circuit is characterized by comprising a power circuit part and a control method part;
the power circuit part is a Boost type power factor correction circuit, and consists of a rectifier bridge, a pi-shaped filter circuit, a Boost circuit and an output filter link, and the power circuit part specifically comprises the following steps:
diode with a high-voltage sourceD 1 A positive electrode ofD 3 The negative electrodes of the two electrodes are connected with each other,D 2 and a positive electrode ofD 4 The negative electrodes of the two electrodes are connected with each other,D 1 and a negative electrode ofD 2 The negative electrodes of the two electrodes are connected with each other,D 3 and a positive electrode ofD 4 The positive electrodes of the two rectifier circuits are connected to form a rectifier bridge; filter capacitorC f1 One terminal of and filter inductorL f The connection is carried out in a connecting way,L f another terminal of (1) and a filter capacitorC f2 One end of the n-shaped filter circuit is connected to form an n-shaped filter circuit, and is connected with the output end of the rectifier bridge; pi-type filter circuit and MOS transistorQ 1 Excitation inductorL m Freewheel diodeD 5 The formed Boost circuit phaseConnecting; capacitor of two output filtering linksC o1 、C o2 Connected in parallel and connected with a Boost circuit; output load and output capacitorC o1 、C o2 Are connected in parallel;
the control method part consists of a voltage and current double closed loop control loop and a reference current generation module containing a harmonic compensation signal;
the voltage-current double closed-loop control converter works in an average current mode, and specifically comprises the following steps: reference voltagev ref And the output voltagev o After comparison, the obtained voltage error signalv err As voltage controllersG v (s) The input of (1); when the converter realizes the harmonic compensation function, the voltage after the sampling bridge is no longer incidentv in Absolute value is removed through zero-crossing detection, and input voltage is obtained through reductionv in Then extracted by a harmonic detection unitv in Harmonic component ofv in-h Generating a signal including harmonic compensationv z Internal command voltage signalv c (ii) a Voltage controllerG v (s) Output of (2)V e And voltagev c Multiplication with the result of the reference currenti ref And the inductance currenti Lm Compared to obtain a current error signali err As a current controllerG c (s) Is controlled by a current controlleri Lm The waveform of (a); due to filter capacitance in average current mode controlC f And a filter inductorL f Presence of input currenti in Is an inductive currenti Lm Average value over a switching period, so that the current controllerG c (s) Can indirectly control the input currenti in To makei in Including harmonic compensation currentsi in-h Thereby realizing the harmonic compensation function;
the reference current generation module comprises a band-pass filter with the center frequency of 50Hz and a repetitive controller, and self-adaptively generates under the condition of different power grid impedancesThe reference current specifically comprises:G a (s) As a controller, it only contains the internal model link and the gain link of the repetitive controllerK h ，G b (s) Is a band-pass filter with a center frequency of 50 Hz; input voltagev in Voltage after sampling bridgev in Absolute value is removed through a program to obtain the absolute value; input voltagev in Through a band-pass filter G b (s) Then, an input voltage is obtainedv in Harmonic component of (2)v in-h Harmonic components ofv in_h As input to a repetitive controller, its outputv RC And withv in_h Adding and multiplying by a gainK h To obtain a harmonic compensation signalv z ，v z Re-and fundamental componentv in_f Adding the sum to obtain an absolute value, and outputting the absolute value and a voltage loopv e Multiplying to obtain a reference currenti ref 。
2. The method of claim 1, wherein the inductor current of the converter is controlled by the harmonic compensation circuiti Lm The controller is controlled by a current controller, the controller is formed by combining an embedded repetitive controller and a single zero-single pole compensator, and the method specifically comprises the following steps:
by applying current to the inductori Lm Sampling and comparing with a current reference signali ref Comparing to obtain a current error signali err And as an embedded repetitive controllerG RC (s) The input of (1); the embedded repetitive controller comprises an internal model link and a compensation link, whereinQ(s) In the form of a low-pass filter,G f (s) For the lead link, N =f s /f n ，f s In order to be able to sample the frequency,f n for the frequency of the power grid,T s in order to be the sampling period of time,k f is a constant; repeating the output of the controller and the error signali err After addition, the single zero point-single pole point compensator is usedG i (s) Finally from a single zero-monopoleOutput duty ratio signal of point compensatord(ii) a Thus ensuring the inductive currenti Lm Can quickly and accurately track the reference current containing fundamental waves and various harmonicsi ref 。
CN202211390460.0A 2022-11-08 2022-11-08 Control method of harmonic compensation circuit Pending CN115566684A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117791837A (en) * 2024-02-27 2024-03-29 苏州元脑智能科技有限公司 Control method, device and equipment for backup battery unit and storage medium
CN117791837B (en) * 2024-02-27 2024-05-14 苏州元脑智能科技有限公司 Control method, device and equipment for backup battery unit and storage medium

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117791837A (en) * 2024-02-27 2024-03-29 苏州元脑智能科技有限公司 Control method, device and equipment for backup battery unit and storage medium
CN117791837B (en) * 2024-02-27 2024-05-14 苏州元脑智能科技有限公司 Control method, device and equipment for backup battery unit and storage medium

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