CN108574403A - Non-isolation type photovoltaic DC-to-AC converter common mode resonance loop current and drain current suppressing method - Google Patents
Non-isolation type photovoltaic DC-to-AC converter common mode resonance loop current and drain current suppressing method Download PDFInfo
- Publication number
- CN108574403A CN108574403A CN201810371790.2A CN201810371790A CN108574403A CN 108574403 A CN108574403 A CN 108574403A CN 201810371790 A CN201810371790 A CN 201810371790A CN 108574403 A CN108574403 A CN 108574403A
- Authority
- CN
- China
- Prior art keywords
- common mode
- current
- circuit
- voltage
- phase
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Classifications
-
- 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
- H02M1/12—Arrangements for reducing harmonics from ac 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
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
- H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
- H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/483—Converters with outputs that each can have more than two voltages levels
-
- 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
- H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
- H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
- H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/53—Conversion of dc power input into ac 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
- H02M7/537—Conversion of dc power input into ac 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, e.g. single switched pulse inverters
- H02M7/5387—Conversion of dc power input into ac 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, e.g. single switched pulse inverters in a bridge configuration
-
- 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
- H02M1/00—Details of apparatus for conversion
- H02M1/12—Arrangements for reducing harmonics from ac input or output
- H02M1/123—Suppression of common mode voltage or current
-
- 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
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
- Y02E10/56—Power conversion systems, e.g. maximum power point trackers
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Inverter Devices (AREA)
Abstract
The invention discloses a kind of non-isolation type photovoltaic DC-to-AC converter common mode resonance loop current and drain current suppressing methods; including three-phase I fonts three-level inverter and modified LCL filter circuits; the capacitance common end of the modified LCL filter circuits is directly connected at the neutral point of DC side filter capacitor; change the common mode circuit of three-phase I font three-level inverters, suppression system leakage current.The present invention proposes the closed loop control algorithm in common mode circuit, increases PI controllers in common mode circuit, realizes the inhibition of common mode resonance loop current.The present invention can be cost-effective, improves system transfer efficiency, has very high practical value.
Description
Technical field
The present invention relates to a kind of non-isolation type photovoltaic DC-to-AC converter common mode resonance loop current and drain current suppressing methods.
Background technology
In recent years, the rapid growth of photovoltaic generation is that solution world energy sources shortage and problem of environmental pollution play huge work
With.Photovoltaic DC-to-AC converter is core component in photovoltaic generating system, and direct current is converted to alternating current by it.Three electricity of I fonts three-phase
Zero diopter volt inverter topology is widely used in mesohigh high-power photovoltaic system.I font three-level topologies have lower open
The advantage of pass loss, more preferably output waveform quality and higher energy density and efficiency, makes it be increasingly becoming the market mainstream, obtains
To the attention of various countries scientific research personnel and the extensive use of industrial quarters.
But the parasitic capacitance in the non-isolated photovoltaic inverter system in photovoltaic panel unavoidably generates leakage current.Leakage
Electric current can increase the electromagnetic interference of system, and output current wave is made to distort, and bring huge safety hidden to equipment and operating personnel
Suffer from.For this purpose, national standard is made that regulation to the size of leakage current, the electric leakage of the photovoltaic DC-to-AC converter of 10kW and following power grade
It flows big palpulus and is less than 300mA.
Mainly start at present from change inverter topology and in terms of changing modulation strategy two about the method for reducing leakage current.
On the one hand, in changing inverter topology and reducing the method for leakage current, by DC side or exchange side increase switching tube and
Diode changes the common-mode voltage that inverter system generates, and then inhibits leakage current.But this method needs to increase additionally auxiliary
Switching device is helped, this not only adds the costs of system to also increase control difficulty.On the other hand, changing modulation strategy reduction
In the method for leakage current, common method is to abandon partial switch vector (the larger common mode electricity of these switching vector selectors generation amplitude
Pressure), it is electric by reducing common mode such as reversed (APOD) modulator approach of carrier wave and LMZ (only using big or middle, zero vector) modulator approach
The amplitude of pressure realizes the purpose for inhibiting leakage current.But this method inhibits the ability of leakage current limited, simultaneously because only with
Segment vector carrys out synthesized reference voltage, and the total harmonic distortion factor (THD) of output voltage or current waveform increases.Based on this,
There is document to propose and the method for leakage current is reduced using a kind of improved LCL filter, the method is hardly increasing cost
Under the premise of controlling and modulating difficulty, leakage current is greatly reduced.But modified LCL filter, change inverter
The common mode leakage current circuit of system, common-mode voltage evoke common mode resonance loop current in improved common mode circuit.Common mode resonance
Loop current makes a series of problems, such as inverter side current oscillation, the increase of system leakage current, system power protection misoperation, this is broken
It is broken the stability of system.
Therefore, it is brought not for common mode resonance loop current in I font three-level photovoltaic inverter systems and leakage current
Profit influences, and it is significant to study a kind of simple and effective solution.
Invention content
The present invention is to solve the above-mentioned problems, it is proposed that a kind of non-isolation type photovoltaic DC-to-AC converter common mode resonance loop current and
LCL filter capacitance common end is connected to DC bus by drain current suppressing method, present invention modified LCL filter
Midpoint increases a low-impedance capacitive branch in common mode circuit, changes the circuit structure in common mode circuit, the common mode of high frequency
The high frequency common mode leakage current that voltage evokes flows back to the midpoint of DC bus by this increased low-impedance capacitive branch, to
Significantly reduce the leakage current for flowing into the earth.
To achieve the goals above, the present invention adopts the following technical scheme that：
The first object of the present invention is to provide a kind of photovoltaic DC-to-AC converter common mode resonance loop current and drain current suppressing system,
Including three-phase I fonts three-level inverter and modified LCL filter circuits, the capacitance of the modified LCL filter circuits is public
End is directly connected at the neutral point of DC side filter capacitor, changes the common mode circuit of three-phase I font three-level inverters, is inhibited
System leakage current.Modified LCL filter will not change the filtering in differential mode circuit there is no the differential mode circuit for changing system simultaneously
Effect.
Further, the three-phase I font three-level inverters include three-phase bridge arm, include upper and lower bridge arm per phase bridge arm,
The upper and lower bridge arm includes two pole of clamp that two concatenated switching tubes and two connect upper and lower bridge arm switching tube midpoint
Pipe, DC side include two concatenated identical filter capacitors, and a neutral point is formed among two capacitances, per phase bridge arm
The centre of two clamp diodes is connected with neutral point, and exchange bridge arm midpoint is made to generate zero potential.
Further, the conducting state of four switching tubes per phase bridge arm is different, the electricity that exchange bridge arm midpoint generates
Position is different, generation+Udc/2、-Udc/ 2,0 three kind of level, UdcFor DC side supply voltage.
Preferably, the switching tube is IGBT switching tubes.
Further, opening for the switching tube passes through modulate circuit and driving with shutdown by the controller in control system
Circuit directly controls.
Further, the control system includes protecting circuit, driving circuit, over-sampling modulate circuit and control circuit, and three
The signal of phase I font three-level inverters is connected to controller by over-sampling modulate circuit, and the controller and protection circuit are logical
Letter, realizes overcurrent and overvoltage protection, and controller connects driving circuit, the pwm signal of controller output through overdrive circuit every
From the control pole that amplification is sent to switching tube, opening and turning off for switching tube is controlled.
Further, the over-sampling modulate circuit acquisition and the capacitance voltage up and down, the three-phase bridge inverter side that improve DC side
Electric current, three-phase filter capacitor voltage and three-phase power grid voltage value.
Further, the common-mode circuit control method based on above system, by three-phase inverter side output current phase adduction
It is made the difference with reference value, difference passes through common mode loop resonance current controller, obtains for adjusting positive and negative small vector action time
Variable is controlled, realizes the real-time adjustment of the positive and negative small vector action time in seven segmentation modulation algorithms；By changing positive and negative small arrow
Measuring action time reduces amplitude of the common-mode voltage at common mode loop resonance frequency, realizes the inhibition of common mode resonance loop current.
Further, it in common mode circuit, realizes that the controller that common mode resonance loop current inhibits is PI controllers, realizes
The zero steady state error control of common mode resonance loop current.Due to it is expected that common mode resonance loop current is eliminated as possible, so common mode resonance ring
The reference value of road electric current is set as zero.
It is real by capacitance voltage feed-forward control algorithm based on the capacitance voltage feed forward control method in above system differential mode circuit
When adjust modulating wave, to change amplitude of the bridge arm output voltage at differential mode loop resonance frequency, realize to humorous in differential mode circuit
It shakes the inhibition of electric current.
Neutral-point voltage balance method based on above system acquires the difference of DC side or more capacitance voltage, utilizes
Mid-point voltage controller obtains the control variable for adjusting positive and negative small vector action time in real time according to the mathematic interpolation, changes
Positive and negative small vector action time controls neutral point voltage balance.
Specifically, when upside capacitance voltage is more than downside capacitance voltage, p-type small vector action time should be increased；Instantly
When lateral capacitance voltage is more than upside capacitance voltage, N-type small vector action time should be increased.
Compared with prior art, beneficial effects of the present invention are：
1, it is compared with using traditional LCL filter, modified LCL filter is by changing common mode loop structure, effectively
Inhibit leakage current.Reduce caused by leakage current that electromagnetic interference is big, system stability is poor, the low-quality unfavorable shadow of output waveform
It rings.
2, change main circuit topology by increasing auxiliary switch or diode with tradition and inhibit the comparison of leakage current method,
The method of the present invention is not necessarily to any auxiliary switch or diode, only need to increase a conducting wire.This greatly reduces system at
This, reduces system bulk, simplifies control algolithm and modulation algorithm.
3, the method for leakage current is inhibited to compare by changing modulation algorithm with tradition, the present invention does not abandon any vector,
So that the waveform quality of output voltage and electric current is more excellent, harmonic content is lower, is more advantageous to the volume for reducing filter, reduces system
System cost.
4, the method inhibited with no common mode resonance loop current compares, and the present invention proposes a kind of closed loop control in common mode circuit
Algorithm processed, can effective suppression common mode resonance loop electric current, so that inverter output current oscillation is effectively suppressed, output current wave
Shape better quality, the stability and anti-interference of system are stronger.
5, it is compared with the method using passive damping suppression common mode resonance loop electric current and differential mode loop resonance electric current, this hair
It is bright to realize that common mode and the resonance current in differential mode circuit inhibit by closed loop control algorithm.Increase PI controllers in common mode circuit,
Suppression common mode resonance loop electric current.Capacitance voltage feedforward control is used in differential mode circuit, inhibits differential mode loop resonance electric current.By
Damping resistance is eliminated in this method, so reducing the energy loss of system, this method has saved cost, improves and is
System transfer efficiency, has very high practical value.
Description of the drawings
The accompanying drawings which form a part of this application are used for providing further understanding of the present application, and the application's shows
Meaning property embodiment and its explanation do not constitute the improper restriction to the application for explaining the application.
Fig. 1 is the I font three-level photovoltaic inverter system construction drawings of modified LCL filter；
Fig. 2 is the common mode equivalent circuit figure of the I font three-level photovoltaic inverters of modified LCL filter；
Fig. 3 is that the bode of modified LCL filter common mode equivalent circuit schemes；
Fig. 4 is the control block diagram of common mode resonance loop current；
Fig. 5 is the differential mode equivalent circuit of the I font three-level photovoltaic inverters based on modified LCL filter；
Fig. 6 is that the bode of modified LCL filter differential mode equivalent circuit schemes；
Fig. 7 is system main-control block diagram；
Fig. 8 is 3 level space vector distribution map；
Fig. 9 is seven segmentation on off sequence figures；
Specific implementation mode：
The invention will be further described with embodiment below in conjunction with the accompanying drawings.
It is noted that following detailed description is all illustrative, it is intended to provide further instruction to the application.Unless another
It indicates, all technical and scientific terms used herein has usual with the application person of an ordinary skill in the technical field
The identical meanings of understanding.
It should be noted that term used herein above is merely to describe specific implementation mode, and be not intended to restricted root
According to the illustrative embodiments of the application.As used herein, unless the context clearly indicates otherwise, otherwise singulative
It is also intended to include plural form, additionally, it should be understood that, when in the present specification using term "comprising" and/or " packet
Include " when, indicate existing characteristics, step, operation, device, component and/or combination thereof.
In the present invention, term for example "upper", "lower", "left", "right", "front", "rear", "vertical", "horizontal", " side ",
The orientation or positional relationship of the instructions such as "bottom" is to be based on the orientation or positional relationship shown in the drawings, only to facilitate describing this hair
Bright each component or component structure relationship and the relative of determination, not refer in particular to either component or element in the present invention, cannot understand
For limitation of the present invention.
In the present invention, term such as " affixed ", " connected ", " connection " shall be understood in a broad sense, and indicate may be a fixed connection,
Can also be to be integrally connected or be detachably connected；It can be directly connected, it can also be indirectly connected through an intermediary.For
The related scientific research of this field or technical staff can determine the concrete meaning of above-mentioned term in the present invention as the case may be,
It is not considered as limiting the invention.
In order to effectively inhibit leakage current, the adverse effect of leakage current is reduced, the present invention uses modified LCL filter.It
LCL filter capacitance common end is connected to the midpoint of DC bus, increases a low-impedance capacitance branch in common mode circuit
Road changes the circuit structure in common mode circuit, and the high frequency common mode leakage current that the common-mode voltage of high frequency evokes is increased by this
Low-impedance capacitive branch flows back to the midpoint of DC bus, to significantly reduce the leakage current for flowing into the earth.
Although improved LCL filter can effectively reduce leakage current, common mode resonance loop current can be caused simultaneously, given
System brings adverse effect.In order to effectively inhibit the common mode resonance loop electricity that common-mode voltage evokes in modified LCL filter
Stream, the present invention propose a kind of common mode circuit Closed-loop Control Strategy, and common mode is realized by increasing PI controllers in common mode circuit
The inhibition of resonance loop electric current.The output of PI controllers changes the action time of positive and negative small vector in space vector modulation, reduces
Amplitude of the common-mode voltage at resonant frequency in common mode circuit, and then suppression common mode resonance loop electric current.
The present invention is under the premise of hardly increasing cost, not increasing control and modulation difficulty, the common mode resonance ring of realization
Effective inhibition of road electric current and leakage current.Present invention improves system output waveform quality, the safety of system and steady is improved
It is qualitative.
To achieve the above object, the present invention adopts the following technical scheme that：
Main circuit is three-phase I font three-level inverters, includes four IGBT switching tubes and two clamps two per phase bridge arm
Pole pipe.DC side is two identical filter capacitor series connection, a neutral point O is formed among two capacitances, per phase bridge arm
The centre of two clamp diodes is connected with neutral point O, and exchange bridge arm midpoint is made to generate zero potential.Obviously, it is opened up in this circuit
In flutterring, the conducting state of four pipes per phase is different, and the current potential that exchange bridge arm midpoint generates is also different, and this topology can produce
Raw+Udc/2、-Udc/ 2,0 three kind of level.
In the modified LCL filter circuits, capacitance common end is connected to DC side filter capacitor by a conducting wire
Neutral point O changes the common mode circuit of I font Three-Level Inverter Systems, effective suppression system leakage current.
Opening for switching tube is directly controlled by the controller in control system by modulate circuit and driving circuit with shutdown；
The modulation strategy and control algolithm of system are realized in controller DSP.
The control system includes protection circuit, driving circuit, over-sampling modulate circuit and control circuit composition.Main circuit
Signal is connected to DSP module by over-sampling modulate circuit, and the signal of main circuit is sent to the operation that DSP carries out control algolithm.DSP
Module and protection circuit communication, realize the overcurrent and overvoltage protection of system.DSP module connects driving circuit, the PWM of DSP outputs
Isolation amplification of the signal through overdrive circuit is sent to the gate pole of IGBT, controls opening and turning off for IGBT.
The over-sampling modulate circuit, capacitance voltage, three-phase bridge inverter side electric current, three-phase are filtered up and down with conditioning DC side for acquisition
Wave capacitance voltage, three-phase power grid voltage.
The modulation strategy is the seven segmentation dSPACE of SVPWM that positive and negative small vector action time can be changed
(SVPWM)。
The control algolithm of the three level I font inverter topologies based on modified LCL filter includes common-mode circuit
Closed loop control algorithm, differential mode circuit capacitance voltage feed-forward control algorithm and neutral point voltage balance algorithm control algolithm.
The control algolithm of I font three-level inverters based on above-mentioned modified LCL filter, specially：
Common mode circuit closed loop control algorithm realizes system due to the common mode resonance ring using the introducing of modified LCL filter
The inhibition of road electric current.Three-phase inverter side output current phase adduction is made the difference with reference value, difference is by common mode loop resonance electricity
Stream controller obtains the control variable for adjusting positive and negative small vector action time, realizes positive and negative in seven segmentation modulation algorithms
The real-time adjustment of small vector action time.Common-mode voltage is reduced in common mode loop resonance by changing positive and negative small vector action time
Amplitude at frequency realizes the inhibition of common mode resonance loop current.In common mode circuit, realize that common mode resonance loop current inhibits
Controller be PI controllers, for realizing the zero steady state error control of common mode resonance loop current, due to it is expected common mode resonance loop
Electric current is eliminated as possible, and reference value is set as zero.
The capacitance voltage feed-forward control algorithm in differential mode circuit, realizes the inhibition of differential mode loop resonance electric current.Due to using
Modified LCL filter, there are intrinsic resonance points, the pulse voltage of bridge arm output to generate at resonance point in differential mode circuit
Differential mode resonance current causes the unstable of system.Modulating wave is adjusted in real time by capacitance voltage feed-forward control algorithm, changes bridge arm
Amplitude of the output voltage at differential mode loop resonance frequency realizes the inhibition of resonance current in differential mode circuit.
Neutral-point voltage balance algorithm realizes the balance control of the DC side mid-point voltage of I font three-level inverters
System.The difference of capacitance voltage above and below DC side is obtained by mid-point voltage controller for adjusting positive and negative small vector effect in real time
The control variable of time changes positive and negative small vector action time, realizes the control of neutral point voltage balance.When upside, capacitance voltage is big
When the capacitance voltage of downside, p-type small vector action time should be increased；Instantly it when lateral capacitance voltage is more than upside capacitance voltage, answers
Increase N-type small vector action time.
As a kind of exemplary embodiments, as shown in Figure 1, using the three level photovoltaic inversion of I fonts of modified LCL filter
Device system construction drawing, main circuit are three-phase I font three-level inverters, totally 12 IGBT switching tubes and six clamp diodes；
Filter uses modified LCL filter, the capacitance common end of this filter to be connected in DC bus capacitor by a conducting wire
Point；DC side is two concatenated filter capacitors, and a neutral point O is formed among two capacitances, per two pincers of phase bridge arm
The centre of position diode is connected with neutral point O, and this topology can generate+Udc/2、-Udc/ 2,0 three kind of level.
Fig. 2 is the three level photovoltaic of I fonts of the modified LCL filter obtained according to kirchhoff circuit equation in Fig. 1
The common mode equivalent circuit figure of inverter.Compared with traditional LC L common mode equivalent circuits, this equivalent circuit increases in common mode circuit
One low-impedance capacitive branch, the branch provide access for the common mode current of high frequency, greatly reduce the electric leakage for flowing into the earth
Stream.Leakage current is to the transmission function of common-mode voltage：
It can be seen that the common mode circuit based on modified LCL filter is a fourth-order system, have more to high-frequency leakage current
Strong damping capacity, this greatly reduces the leakage currents for flowing into the earth.From Fig. 2 and leakage current to the transmission function of common-mode voltage
It can obtain, due to the design feature of Modified Filter system itself, there are intrinsic resonance points for filter itself, in resonance
It can lead to common mode resonance loop current at point.
Fig. 3 is that the bode of modified LCL filter common mode equivalent circuit schemes, and due to the introducing of low-impedance capacitor branch, is made
There are resonance points in common mode equivalent circuit, in practical applications, it will usually in fr1Common mode resonance loop current is generated at frequency,
Inverter output current is caused to vibrate, the current protection of system malfunctions, and system is unstable.Resonant frequency fr1For：
By resonant frequency fr1Expression formula can be seen that this resonant frequency by circuit parameter L and CfInfluence.Assuming that system
Leakage current can be suppressed to zero, so the mathematical model of common mode resonance loop current is：
It can be seen that ucmFor common mode resonance loop current icmzDriving source, for realize icmzEffective suppression of resonance loop electric current
System, can be by reducing ucmAmplitude at resonant frequency realizes the inhibition of common mode resonance loop current.The present invention passes through altogether
Increase Closed-loop Control Strategy in mould circuit, Closed-loop Control Strategy reduces amplitude of the common-mode voltage at resonant frequency, and then presses down
Common mode resonance loop current processed.
Fig. 4 is the control block diagram that common mode resonance loop current inhibits, and the controller in common mode circuit is PI controllers, in order to have
Suppression common mode resonance loop electric current is imitated, the given value of common mode resonance loop current is set as zero, and common mode resonance loop current is given
The difference of definite value and actual value is sent into PI controllers.The output of PI controllers passes through for adjusting positive and negative small vector action time
In real time pairs of positive and negative small vector action time in seven segmentation modulation strategies of adjustment, reduce common-mode voltage amplitude at resonant frequency,
And then realize effective inhibition of common mode resonance loop current.Control variable for adjusting positive and negative small vector action time in real time
For：
Fig. 5 is the differential mode equivalent circuit of the I font three-level photovoltaic inverters of modified LCL filter；It is filtered using LCL
Device under the premise of realizing identical filter effect, can substantially reduce the volume of filter, reduce system loss, raising system turn
Change efficiency, cost-effective.System bridge arm output current is to the transmission function of bridge arm output voltage：
But LCL filter itself is there are resonance point, can cause the resonance of system output current, differential mode resonant frequency to be：
Fig. 6 is the bode figures of the differential mode equivalent circuit of the I font three-level photovoltaic inverters of modified LCL filtering, due to
The reason of this body structure of filter so that there are resonance spikes for LCL filter, if resonance spikes cannot be effectively suppressed,
System is unstable, causes system oscillation, system crash.Use capacitance voltage feedforward control to realize differential mode loop current resonance here
Inhibition.
Fig. 7 is the whole control block diagram of the present invention, and control section is controlled by the PI inhibited for common mode resonance loop current
Device, the differential mode controller for the inhibition of differential mode loop resonance, the mid-point voltage for DC side neutral-point voltage balance control
Device is constituted.The controller action can effectively inhibit to leak electricity on the three-phase I font three-level inverters of modified LCL filter
Stream, common mode resonance loop current；Differential mode loop resonance；DC side mid-point voltage fluctuates.The algorithm is hardly increasing cost
Under the premise of realize the efficient, stable of system, reliability service.
Fig. 8 is 3 level space vector figure, and each phase bridge arm has tri- kinds of states of P, O, N, so three level of three-phase I fonts is opened up
27 switching vector selectors are flutterred, long according to the mould of vector, 27 vectors are divided into 4 groups, large, medium and small, zero vector.Wherein big vector point
Cloth outer hexagon apex, totally six；Middle vector is distributed in the midpoint on the side of outer hexagon, totally six；Small vector at
To appearance, it is divided into positive small vector and negative small vector, is distributed in the apex of interior hexagon, totally 12；Zero vector is distributed in six sides
The midpoint of shape, totally 3.
Fig. 9 is the on off sequence assumed when reference vector is located at 5 region of the big sectors I using seven segmentation modulation strategies, is led to
The action time for adjusting positive and negative small vector is spent, realizes different control targes.PI devices output in Fig. 4 is positive and negative small for adjusting
The action time of vector reduces amplitude of the common-mode voltage at resonant frequency, and then suppression common mode resonance loop electric current.At this time three
The phase separation time is adjusted to：
In order to ensure the stability of system, dzIt must satisfy following condition
Similarly, in Fig. 7 when effect of the output of DC side neutral-point voltage balance device for adjusting positive and negative small vector
Between, realize effective control of neutral point voltage balance.The action time of three-phase is adjusted to again at this time：
In order to ensure the stability of system, yzIt must satisfy following condition
Table 1 is seven segmentation switching vector selector tables, and seven section space vector modulation strategies are to bear small vector beginning and end.Using
The modulation of seven section space vectors can effectively improve output waveform quality.Reduce the volume of filter.
The corresponding switching sequence of 1 different sectors of table
The foregoing is merely the preferred embodiments of the application, are not intended to limit this application, for the skill of this field
For art personnel, the application can have various modifications and variations.Within the spirit and principles of this application, any made by repair
Change, equivalent replacement, improvement etc., should be included within the protection domain of the application.
Above-mentioned, although the foregoing specific embodiments of the present invention is described with reference to the accompanying drawings, not protects model to the present invention
The limitation enclosed, those skilled in the art should understand that, based on the technical solutions of the present invention, those skilled in the art are not
Need to make the creative labor the various modifications or changes that can be made still within protection scope of the present invention.
Claims (10)
1. a kind of photovoltaic DC-to-AC converter common mode resonance loop current and drain current suppressing system, it is characterized in that：Including three-phase I fonts three
Electrical level inverter and modified LCL filter circuit, the capacitance common end of the modified LCL filter circuits are directly connected to directly
The neutral point of side filter capacitor is flowed, the common mode circuit of three-phase I font three-level inverters, suppression system leakage current are changed.
2. a kind of photovoltaic DC-to-AC converter common mode resonance loop current as described in claim 1 and drain current suppressing system, feature
It is：The three-phase I font three-level inverters include three-phase bridge arm, include upper and lower bridge arm per phase bridge arm, the upper and lower bridge arm
Include the clamp diode that two concatenated switching tubes and two connect upper and lower bridge arm switching tube midpoint, DC side includes
Two concatenated identical filter capacitors form a neutral point among two capacitances, two two poles of clamp per phase bridge arm
The centre of pipe is connected with neutral point, and exchange bridge arm midpoint is made to generate zero potential.
3. a kind of photovoltaic DC-to-AC converter common mode resonance loop current as described in claim 1 and drain current suppressing system, feature
It is：The conducting state of four switching tubes per phase bridge arm is different, and the current potential that exchange bridge arm midpoint generates is different, generation+Udc/
2、-Udc/ 2,0 three kind of level, UdcFor supply voltage.
4. a kind of photovoltaic DC-to-AC converter common mode resonance loop current as described in claim 1 and drain current suppressing system, feature
It is：The control system includes that protection circuit, driving circuit, over-sampling modulate circuit and control circuit, three-phase I three level of font are inverse
The signal for becoming device is connected to controller, the controller and protection circuit communication by over-sampling modulate circuit, realizes overcurrent and mistake
Pressure protection, controller connect driving circuit, and isolation amplification of the pwm signal through overdrive circuit of controller output is sent to switching tube
Gate pole, control opening and turning off for switching tube.
5. a kind of photovoltaic DC-to-AC converter common mode resonance loop current as described in claim 1 and drain current suppressing system, feature
It is：The capacitance voltage up and down, three-phase bridge inverter side electric current, three-phase filtered electrical of the over-sampling modulate circuit acquisition and conditioning DC side
Hold voltage and three-phase power grid voltage value.
6. the common-mode circuit control method based on the system as described in any one of claim 1-5, it is characterized in that：By three contraries
Become device side output current phase adduction to make the difference with reference value, difference passes through common mode loop resonance current controller, obtains for adjusting
The control variable of positive and negative small vector action time realizes the real-time tune of the positive and negative small vector action time in seven segmentation modulation algorithms
It is whole；Amplitude of the common-mode voltage at common mode loop resonance frequency is reduced by changing positive and negative small vector action time, realizes common mode
The inhibition of resonance loop electric current.
7. common-mode circuit control method as claimed in claim 6, it is characterized in that：In common mode circuit, common mode resonance ring is realized
The controller that road electric current inhibits is PI controllers, realizes the zero steady state error control of common mode resonance loop current, common mode resonance loop electricity
The reference value of stream is set as zero.
8. the capacitance voltage feed forward control method based on the system as described in any one of claim 1-5, it is characterized in that：Pass through
Capacitance voltage feed-forward control algorithm adjusts modulating wave in real time, changes amplitude of the bridge arm output voltage at differential mode resonant frequency, with
Realize the inhibition to resonance current in differential mode circuit.
9. the neutral-point voltage balance method based on the system as described in any one of claim 1-5, it is characterized in that：Acquisition
The difference of DC side capacitance voltage up and down is obtained using mid-point voltage controller according to the mathematic interpolation positive and negative in real time adjusting
The control variable of small vector action time changes positive and negative small vector action time, realizes the control of neutral point voltage balance.
10. neutral-point voltage balance method as claimed in claim 9, it is characterized in that：When upside capacitance voltage is more than downside
When capacitance voltage, p-type small vector action time should be increased；Instantly when lateral capacitance voltage is more than upside capacitance voltage, N-type should be increased
Small vector action time.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810371790.2A CN108574403B (en) | 2018-04-24 | 2018-04-24 | Non-isolation type photovoltaic DC-to-AC converter common mode resonance loop current and drain current suppressing method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810371790.2A CN108574403B (en) | 2018-04-24 | 2018-04-24 | Non-isolation type photovoltaic DC-to-AC converter common mode resonance loop current and drain current suppressing method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN108574403A true CN108574403A (en) | 2018-09-25 |
| CN108574403B CN108574403B (en) | 2019-09-03 |
Family
ID=63574305
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201810371790.2A Active CN108574403B (en) | 2018-04-24 | 2018-04-24 | Non-isolation type photovoltaic DC-to-AC converter common mode resonance loop current and drain current suppressing method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN108574403B (en) |
Cited By (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109302094A (en) * | 2018-10-10 | 2019-02-01 | 山东大学 | Three level parallel inverter of non-isolation type modularization, control method and system |
| CN109995259A (en) * | 2019-05-17 | 2019-07-09 | 山东大学 | The common-mode voltage suppressing method and system of DC side imbalance NPC three-level inverter |
| CN110677067A (en) * | 2019-09-16 | 2020-01-10 | 河海大学 | Space vector modulation method for reducing common-mode voltage of non-isolated three-phase quasi-single-stage inverter |
| WO2020082762A1 (en) * | 2018-10-22 | 2020-04-30 | 山东大学 | Pwm method, modulator and system for three-level rectifier suppressing common mode voltage |
| CN112582997A (en) * | 2020-11-02 | 2021-03-30 | 武汉华中数控股份有限公司 | Leakage suppression circuit and control method thereof |
| CN112737388A (en) * | 2021-02-24 | 2021-04-30 | 山东大学 | Common-mode active damping resonant circulating current suppression system and method for inverter parallel system |
| CN112868175A (en) * | 2019-01-28 | 2021-05-28 | 华为技术有限公司 | Equipment, method and system for solving common-mode voltage interference |
| CN112996688A (en) * | 2020-07-14 | 2021-06-18 | 深圳欣锐科技股份有限公司 | Three-phase charging and single-phase charging mutual switching circuit and related device |
| CN113179035A (en) * | 2021-05-12 | 2021-07-27 | 太原理工大学 | Non-isolated converter capable of eliminating leakage current and common mode voltage and control method |
| CN113285583A (en) * | 2021-05-26 | 2021-08-20 | 山东大学 | Non-isolated photovoltaic inverter leakage current suppression method and system |
| CN114142715A (en) * | 2021-12-03 | 2022-03-04 | 山东大学 | Common-mode resonance circulating current suppression method and system for high-power parallel inverter |
| CN114244169A (en) * | 2021-12-16 | 2022-03-25 | 山东大学 | Fractional order-based multi-index cooperative control method and system for three-level inverter |
| CN115513993A (en) * | 2022-07-19 | 2022-12-23 | 四川大学 | Leakage current suppression double modulation wave modulation method based on non-isolated photovoltaic inverter |
| CN117318454A (en) * | 2023-11-28 | 2023-12-29 | 锦浪科技股份有限公司 | Low-frequency common-mode leakage current suppression method |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115133567A (en) | 2021-03-27 | 2022-09-30 | 华为数字能源技术有限公司 | Photovoltaic system and leakage current control method thereof |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102738826A (en) * | 2012-06-11 | 2012-10-17 | 合肥工业大学 | Leakage current restraining method for improved LCL (Lower Control Limit) filter and even balance control method |
| CN106532701A (en) * | 2016-11-16 | 2017-03-22 | 西安交通大学 | LCL-type active power filter and control method thereof |
-
2018
- 2018-04-24 CN CN201810371790.2A patent/CN108574403B/en active Active
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102738826A (en) * | 2012-06-11 | 2012-10-17 | 合肥工业大学 | Leakage current restraining method for improved LCL (Lower Control Limit) filter and even balance control method |
| CN106532701A (en) * | 2016-11-16 | 2017-03-22 | 西安交通大学 | LCL-type active power filter and control method thereof |
Non-Patent Citations (2)
| Title |
|---|
| 任康乐等: "非隔离型三电平并网逆变器的输出滤波器优化设计", 《电力系统自动化》 * |
| 章立: "T型三电平并网逆变器技术研究", 《中国优秀硕士学位论文全文数据库 工程科技Ⅱ辑》 * |
Cited By (21)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109302094A (en) * | 2018-10-10 | 2019-02-01 | 山东大学 | Three level parallel inverter of non-isolation type modularization, control method and system |
| WO2020082762A1 (en) * | 2018-10-22 | 2020-04-30 | 山东大学 | Pwm method, modulator and system for three-level rectifier suppressing common mode voltage |
| CN112868175A (en) * | 2019-01-28 | 2021-05-28 | 华为技术有限公司 | Equipment, method and system for solving common-mode voltage interference |
| US11791719B2 (en) | 2019-01-28 | 2023-10-17 | Huawei Digital Power Technologies Co., Ltd. | Device, method, and system for resolving common-mode voltage interference |
| CN109995259A (en) * | 2019-05-17 | 2019-07-09 | 山东大学 | The common-mode voltage suppressing method and system of DC side imbalance NPC three-level inverter |
| CN109995259B (en) * | 2019-05-17 | 2020-04-21 | 山东大学 | Common-mode voltage suppression method and system of NPC three-level inverter with unbalanced direct current side |
| CN110677067A (en) * | 2019-09-16 | 2020-01-10 | 河海大学 | Space vector modulation method for reducing common-mode voltage of non-isolated three-phase quasi-single-stage inverter |
| CN112996688A (en) * | 2020-07-14 | 2021-06-18 | 深圳欣锐科技股份有限公司 | Three-phase charging and single-phase charging mutual switching circuit and related device |
| CN112582997A (en) * | 2020-11-02 | 2021-03-30 | 武汉华中数控股份有限公司 | Leakage suppression circuit and control method thereof |
| CN112582997B (en) * | 2020-11-02 | 2023-03-10 | 武汉华中数控股份有限公司 | Electric leakage suppression circuit and control method thereof |
| CN112737388A (en) * | 2021-02-24 | 2021-04-30 | 山东大学 | Common-mode active damping resonant circulating current suppression system and method for inverter parallel system |
| CN112737388B (en) * | 2021-02-24 | 2022-04-29 | 山东大学 | Common-mode active damping resonant circulating current suppression system and method for inverter parallel system |
| CN113179035A (en) * | 2021-05-12 | 2021-07-27 | 太原理工大学 | Non-isolated converter capable of eliminating leakage current and common mode voltage and control method |
| CN113285583A (en) * | 2021-05-26 | 2021-08-20 | 山东大学 | Non-isolated photovoltaic inverter leakage current suppression method and system |
| CN113285583B (en) * | 2021-05-26 | 2022-06-03 | 山东大学 | Non-isolated photovoltaic inverter leakage current suppression method and system |
| CN114142715A (en) * | 2021-12-03 | 2022-03-04 | 山东大学 | Common-mode resonance circulating current suppression method and system for high-power parallel inverter |
| CN114244169A (en) * | 2021-12-16 | 2022-03-25 | 山东大学 | Fractional order-based multi-index cooperative control method and system for three-level inverter |
| CN115513993A (en) * | 2022-07-19 | 2022-12-23 | 四川大学 | Leakage current suppression double modulation wave modulation method based on non-isolated photovoltaic inverter |
| CN115513993B (en) * | 2022-07-19 | 2024-05-28 | 四川大学 | Leakage current-inhibiting dual-modulation wave modulation method based on non-isolated photovoltaic inverter |
| CN117318454A (en) * | 2023-11-28 | 2023-12-29 | 锦浪科技股份有限公司 | Low-frequency common-mode leakage current suppression method |
| CN117318454B (en) * | 2023-11-28 | 2024-02-02 | 锦浪科技股份有限公司 | Low-frequency common-mode leakage current suppression method |
Also Published As
| Publication number | Publication date |
|---|---|
| CN108574403B (en) | 2019-09-03 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN108574403B (en) | Non-isolation type photovoltaic DC-to-AC converter common mode resonance loop current and drain current suppressing method | |
| CN104967141B (en) | A kind of Hybrid HVDC system | |
| CN105071425B (en) | A kind of Hybrid HVDC system based on LCC and MMC | |
| CN109217701B (en) | Three-level rectifier common-mode voltage suppression PWM method, modulator and system | |
| CN106329979B (en) | A kind of MMC double loop suppressing method for high-speed permanent magnet motor system | |
| CN109302094A (en) | Three level parallel inverter of non-isolation type modularization, control method and system | |
| CN111697803B (en) | Midpoint common-mode injection single-phase inverter power decoupling control system and control method | |
| CN104811071A (en) | Photovoltaic inverter and passive decoupling restraining method based on non-isolated LCL filtering | |
| CN102545681A (en) | Step wave synthesis three-phase inverter capable of eliminating low frequency harmonic waves and control method | |
| CN112564121B (en) | Series-connection type power electronic equipment for topology reconstruction and function multiplexing and control method | |
| CN110247573A (en) | Modular multilevel topological structure and its control method based on the double down die mould submodule of coupling inductance | |
| CN107769599B (en) | Forward five-level inverter based on switched capacitor | |
| CN113078829A (en) | MMC topology with interconnected upper bridge arm sub-modules and high-frequency chain and control method | |
| Yuvaraja et al. | Performance and analysis of modular multilevel converter | |
| CN105207507A (en) | MMC sub-module for reducing capacitance volume | |
| Liu et al. | Control strategy for cascade multilevel inverter based STATCOM with optimal combination modulation | |
| CN108429481B (en) | SVPWM modulation method suitable for line voltage cascade type triple converter | |
| Liao et al. | Analysis on topology derivation of single-phase transformerless photovoltaic grid-connect inverters | |
| CN112072669B (en) | Variable ratio voltage regulation and current compensation autotransformer and method | |
| CN113224759A (en) | Unified power quality regulator based on wireless power transmission | |
| CN208226583U (en) | A kind of miniature photovoltaic grid-connected inverter | |
| CN111864794A (en) | Double-frequency transformer-free single-phase photovoltaic grid-connected inverter | |
| Yang et al. | Switched-capacitor-Based hybrid clamped converter for wide power factor applications | |
| CN205945092U (en) | Distributed generator circuit that is incorporated into power networks based on mix many level converter | |
| CN111224572A (en) | Gating unit and high-efficiency non-isolated three-level grid-connected inverter |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant | ||
| EE01 | Entry into force of recordation of patent licensing contract |
Application publication date: 20180925 Assignee: AOTAI ELECTRIC Co.,Ltd. Assignor: SHANDONG University Contract record no.: X2021980009598 Denomination of invention: Common mode resonant loop current and leakage current suppression method for non isolated photovoltaic inverter Granted publication date: 20190903 License type: Exclusive License Record date: 20210922 |
|
| EE01 | Entry into force of recordation of patent licensing contract |