CN110380637A - A kind of hybrid modulation stratgy and its control program of the full-bridge inverter based on critical current mode - Google Patents
A kind of hybrid modulation stratgy and its control program of the full-bridge inverter based on critical current mode Download PDFInfo
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- CN110380637A CN110380637A CN201910254999.5A CN201910254999A CN110380637A CN 110380637 A CN110380637 A CN 110380637A CN 201910254999 A CN201910254999 A CN 201910254999A CN 110380637 A CN110380637 A CN 110380637A
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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
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- H02J3/383—
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/42—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
- H02M7/53871—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 with automatic control of output voltage or current
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/0048—Circuits or arrangements for reducing losses
- H02M1/0054—Transistor switching losses
- H02M1/0058—Transistor switching losses by employing soft switching techniques, i.e. commutation of transistors when applied voltage is zero or when current flow is zero
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
- Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
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- 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
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- 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
- Y02E40/40—Arrangements for reducing harmonics
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Abstract
Critical current mode, which works in critical continuous mode state by control inductive current, can realize the Sofe Switch of inverter switch device, but there are some defects under traditional unipolarity and bipolar modulation strategy: inverter passes over the resonant frequency point of LCL filter at voltage zero-crossing point of power grid since switching frequency is too low under unipolarity modulation strategy influences output current quality so as to cause serious current oscillation；Bipolar modulation strategy lower switch frequency is higher and all equal high frequency mos of switching tube cause efficiency to be difficult to further be promoted.The present invention is by realizing freely regulating and controlling for inverter switching frequency using unipolarity and two kinds of modulation strategies of bipolarity simultaneously in a switch periods, and give a kind of Novel control scheme of single-phase full-bridge inverter based on critical current mode, guarantee to improve output current quality while inverter high-efficiency operation, and has widened the function of the idle output of inverter under critical current mode.
Description
Technical field
The invention discloses the modulation strategies and its control program of a kind of full-bridge inverter based on critical current mode, belong to
In converters technical field.
Background technique
Photovoltaic combining inverter is as device most crucial in photovoltaic generating system, in generation of electricity by new energy and transformation of electrical energy etc.
Occasion has a wide range of applications.High efficiency, high power density, high reliability, low cost, it is multi-functional be the development of current inverter
Main target.Improving switching frequency can reduce the volume of passive device, and then the power density of gird-connected inverter can be improved.
However, improving switching frequency not only will increase switching loss, biggish electromagnetic interference can be also brought.
The application of soft switch technique will be greatly reduced switching loss, can effectively improve switching frequency, reduce inverter volume
With cost, guarantees the efficient operation of inverter and and reduce EMI interference.The soft switch technique in inverter mainly includes nothing at present
Source soft switch technology and active soft switching technology, but require to increase additional device and realize that this not only increases with auxiliary circuit
The volume and cost for having added inverter, also increase control complexity, reduce the reliability of inverter work.
In recent years, scholar proposes the critical current mode continuous control on inverter suitable for middle low power grade
Strategy works in critical current mode by controlling inductive current, on the basis for not increasing any additional devices and auxiliary circuit
The ZVS of upper achievable switching tube is open-minded, and attached drawing 1 (a) is applied main power topology-full bridge inverter, attached drawing 1 (b)
For inductive current i under the control strategyLfOverall schematic, inductive current iLfTwo-way flow works in critical current mode
(BCM), pass through reverse current IBThe charge and discharge of the junction capacity of switching tube are completed in dead time to realize that the ZVS of switching tube is opened
It is logical.
It is similar with SPWM, unipolarity and bipolar modulation strategy, two kinds of conventional modulated plans are also classified under critical current mode
Theoretical service time t under slightlyonWith turn-off time toffAnd switching frequency fsExpression formula such as (1), shown in (2), L in formulafFor
Inverter side inductance value, VDCFor DC input voitage value, VgFor network voltage virtual value, iupWith ilowRespectively inductive current iLf's
Up and down reset limit (as in attached drawing 1 (b) mark envelope).
Unipolarity modulation strategy:
Bipolar modulation strategy:
Inverter switching frequency situation of change such as 2 institute of attached drawing in half of power frequency period can be drawn out according to formula (1), formula (2)
Show, nearby switching frequency levels off to zero to voltage zero-crossing point of power grid under unipolarity modulation strategy as can be seen from Figure, when switch frequency
Rate will lead to inductive current and seriously vibrate with output electric current when being lower than the resonant frequency point of LCL filter, deteriorate output electric current matter
Amount, though selection near zero-crossing point be forced shutdown driving still can not alleviate the problem, simulation waveform as shown in figure 3,
It is unable to satisfy the technical standard requirement of gird-connected inverter output electric current THD < 5%, and also due to the reason unipolarity is modulated
Inverter can not export idle under strategy, and application receives corresponding limitation；And bipolar modulation plan under same circuit parameter
Switching frequency under slightly is much higher than unipolarity modulation strategy, while the equal high frequency mo of all switching tubes, causes turn-off power loss serious,
Efficiency is difficult to be promoted, and may be selected by increasing inverter side inductance LfInductance value reduce switching frequency, but this will lead to inversion again
Body product increases, power density decline, and application value is limited.
Summary of the invention
The present invention is directed to the single-phase grid-connected inverter zero crossing electric current of existing unipolarity modulation strategy lower critical current-mode
The problem of distortion, proposing a kind of hybrid modulation stratgy based on critical current mode realizes freely regulating and controlling for switching frequency,
And combined on this basis with unipolarity modulation strategy, propose a kind of new improvement control suitable for single-phase full-bridge inverter
Scheme processed guarantees to improve output current quality while inverter high-efficiency operation, and realizes critical current mode subinverse
Become the function of the idle output of device.
The purpose of the method for the present invention is achieved through the following technical solutions:
Unipolarity modulation plan is solved based on the hybrid modulation stratgy of the full-bridge inverter of critical current mode using a kind of
The problem of slightly descending current oscillation at voltage zero-crossing point of power grid.The modulation strategy passes through continued flow switch pipe in the inductive current decline stage
Alternating realize the switchings of two kinds of modulation strategies, bipolar modulation strategy is switched to by unipolarity modulation strategy, and pass through control
Make the regulation of the ratio between action time of two kinds of modulation strategies progress switching frequency.Network voltage cross null range (| sin (ω t) |
≤ a, 0 a≤0.1 <) use this modulation strategy to ensure that switching frequency is not less than LCL filter resonant frequency point and causes electricity
Stream oscillation promotes output current quality, it is non-cross null range (| sin (ω t) | > 0.1) guaranteed using unipolarity modulation strategy it is inverse
Become device efficient operation.Attached drawing 4 gives the electricity for mentioning the full-bridge inverter based on critical current mode after improving control program
Inducing current iLfWaveform diagram.
The present invention has the following technical effect that
1. continuously realizing full-bridge by controlling critical current mode under conditions of not increasing additional devices and auxiliary circuit
The ZVS of inverter switching device pipe is open-minded, improves the working efficiency of inverter；
2. crossing null range using hybrid modulation stratgy in network voltage, solves existing electric current under unipolarity modulation strategy
Aberration problems, non-null range of crossing still use unipolarity modulation strategy, ensure that the high efficiency of inverter in entire power frequency period
Output electric current THD is reduced while operation, improves output current quality；
3. realizing the idle output function of inverter under critical current mode, critical current mode inverter device has been widened
Application range；
Detailed description of the invention
Attached drawing 1 is the electricity of the full-bridge inverter of main circuit topology and traditional monopole modulation strategy lower critical current-mode
Inducing current iLfSchematic diagram；
Attached drawing 2 be under critical current mode traditional monopole modulation strategy and bipolar modulation strategy inverter in half of work
The situation of change schematic diagram of switching frequency in the frequency period；
Attached drawing 3 is the grid-connected simulation waveform schematic diagram of the full-bridge inverter of unipolarity modulation strategy lower critical current-mode；
Attached drawing 4 is the inductance electricity of the full-bridge inverter based on critical current mode under control program proposed by the invention
Flow iLfWaveform diagram；
The inductive current of 5 traditional monopole modulation strategy of attached drawing and bipolar modulation strategy lower critical current-mode inverter
iLfWaveform expanded schematic diagram；
6 hybrid modulation stratgy lower critical current-mode inverter inductance current i of attached drawingLfWaveform expanded schematic diagram；
Inductive current i in 7 hybrid modulation stratgy of attached drawing under two kinds of different transfer sequencesLfWaveform and driver' s timing are illustrated
Figure；
Attached drawing 8 is that the present invention mentions the implementation schematic diagram and inversion for improving that used digital-to-analogue combines under control program
Device entirety control block diagram；
Attached drawing 9 is that the present invention mentions inverter switching frequency variation schematic diagram under improvement control program；
Network voltage and output current diagram when attached drawing 10 is inverter idle output；
Inductive current i different under different operating region when attached drawing 11 is inverter idle outputLfIllustrate with driver' s timing
Figure；
Attached drawing 12 is inductive current i when the present invention proposes the idle output of inverter under improvement control programLfOverall schematic；
Attached drawing 13 is that the present invention proposes the simulation run waveform diagram for improving inverter under control program；
Attached drawing 14 is that the present invention proposes the experiment operation waveform diagram for improving inverter under control program；
Attached drawing 15 is that the present invention mentions the efficiency curve and THD curve synoptic diagram for improving inverter under control program；
Specific embodiment
The method of the present invention is described in detail with reference to the accompanying drawing.
Shown in attached drawing 1 (a), for main circuit topology figure, using full-bridge inverter and LCL filter, attached drawing 1 (b) is critical
Inductive current i under current-modeLfSchematic diagram controls iLfTwo-way flow is open-minded to realize the ZVS of switching tube, while every to guarantee
Inductive current average value is consistently equal to export current reference i in a switch periodsoref, inductive current i need to be setLfReset up and down
Limit iup, ilowMeet following formula:
Since positive and negative half period operating status is symmetrical in inverter power frequency period, analyzed by taking positive half period as an example here critical
The operation logic of inverter under current-mode.For unipolarity modulation strategy, switching tube Q1、Q3High frequency mo, Q2、Q4Power frequency is dynamic
Make, positive half period Q4It is normally opened, Q2Chang Guan, Q1、Q4When opening, inductive current iLfIn forward voltage VDC-Vg* under sin (ω t) effect
It ramps, works as iLfRise to setting upper limit value iupAfterwards, Q is turned off1, open Q2, i at this timeLfIt will be in backward voltage-Vg*sin(ω
T) straight line decline is until be lower than preset lower limit i under the action oflowCycle reset afterwards starts next circulation, such as indigo plant in attached drawing 5
Shown in color dotted line, and near network voltage zero passage, due to-Vg* sin (ω t) levels off to zero, leads to inductive current i at this timeLf's
Fall off rate is extremely slow, this is also the basic reason for causing current oscillation problem under unipolarity modulation strategy；For bipolar modulation
Strategy, four equal high frequency mos of switching tube are same to pipe to open with pass, Q1、Q4When opening, inductive current iLfIn forward voltage VDC-Vg*
It is ramped under sin (ω t) effect, and it is completely the same under unipolarity modulation strategy, work as iLfRise to setting upper limit value iupAfterwards,
Turn off Q1、Q4, open Q2、Q3, i at this timeLfIt will be in backward voltage-VDC-Vg* straight line declines until being lower than under the action of sin (ω t)
Preset lower limit ilowCycle reset afterwards, as shown in dotted line red in attached drawing 5, therefore even if near network voltage zero passage, due to
Direct current inputs VDCIt is larger, inductive current iLfStill can rapid decrease, but excessively high switching frequency will lead to high turn-off power loss again,
And it is more demanding to driving chip.Therefore it is contemplated by the invention that whether inductive current i can be madeLfAlong yellow solid line in such as attached drawing 5
Shown decline, between two kinds of modulation strategy decline curves of unipolarity and bipolarity, so that switching frequency will not be too low and be drawn
Electric current oscillation problem is played, unnecessary excess loss excessively high will not be caused.Based on the thought, the present invention is proposed in inductive current
Decline stage is by the switching of two kinds of modulation strategies come equivalent implementation, as shown in Fig. 6, iLfFirst in backward voltage-Vg*sin(ω
T) a certain moment switching continued flow switch pipe is dropped under acting on, and turns off Q4, open Q3, iLfSwitch in backward voltage-VDC-Vg*
Continue to decline under the action of sin (ω t), can equivalent simulation go out decline curve shown in yellow line in attached drawing 6, and can be by cutting
The adjustment for changing the moment can be achieved with freely regulating and controlling for inverter switching frequency.
Two kinds of situations can be divided into again according to two kinds of the different of modulation strategy transfer sequence, as shown in Fig. 7, respectively by list
Polarity switching switches to unipolarity (attached drawing 7 (b)) to bipolarity (attached drawing 7 (a)) and by bipolarity, two kinds of transfer sequence lower switch
The equivalent switch number and switch periods of pipe are completely the same, but the timing and inductive current i drivenLfWaveform completely not
Together.Keep sinusoidal simultaneously in order to make to export electric current, it is necessary to assure inductive current iLfAverage value in each switch periods is always etc.
In current reference ioref, but since the switching of two kinds of modulation strategies will lead to inductive current iLfBecome under broken line from straight line decline
Drop, average value can deviate current reference IorefAs shown in dash area in attached drawing 7, if processing is not compensated to the part
It is no longer sinusoidal to will cause inverter output current, deviates output current reference.
It can be by the upper lower limit value i of change inductive current for this current value being partially away fromupOr ilowTo compensate.
For convenience of calculating and compensating, the present invention is using holding lower limit value ilow=IBIt is constant, to inductive current upper limit value iupIt compensates.
It is clear that for bipolarity (Fig. 7 (a)) this transfer sequence after first unipolarity, to guarantee inductance electricity under hybrid modulation stratgy
Levelling mean value is still equal to current reference, needs to reduce inductive current upper limit value iupWith the deviation of cancellation current, and another kind switches
Sequentially (Fig. 7 (b)) then needs to increase iup.For inverter, inductive current upper limit value iupReduction be conducive to reduce switching tube
Current stress and reduce the conduction loss and di/dt of switching tube, raising efficiency, thus the present invention select it is double after first unipolarity
Control program of the transfer sequence of polarity (Fig. 7 (a)) as inverter.
As shown in attached drawing 7 (a), the turn-off time under enabling unipolarity modulation strategy act on is toff1, bipolar modulation strategy
Turn-off time under effect is toff2, set the ratio between two kinds of modulation strategy time effect time m:
M=toff1/toff2 (4)
It can realize that the split logical turn-off time is modulated by adjusting the size of m, and then realize the tune to switching frequency
Control.Turn-on time and turn-off time expression formula under hybrid modulation stratgy are as follows:
I in formulaupperIt is that can be established an equation and be asked according to inverter operation mode point by compensated new inductive current upper limit value
It solves and obtains, expression formula are as follows:
It can be to inductive current i based on above-mentioned expression formulaLfIt realizes accurate control, sampling feeding is carried out to network voltage first
DSP carries out phaselocked loop operation and obtains real-time electric network voltage phase information ω t, if | sin (ω t) | position if > a (0 a≤0.1 <)
Null range is crossed in non-, inverter uses unipolarity modulation strategy in the region, opens and the expression formula of turn-off time such as formula (1)
It is shown；If | sin (ω t) | it was located at null range if≤a, inverter is open-minded using mixing polar modulation strategy in the region
Shown in expression formula such as formula (5) with the turn-off time.To guarantee inductive current iLfControl effect, the present invention selection use digital-to-analogue knot
The implementation of conjunction, as shown in Fig. 8, i.e. service time tonWith turn-off time toff1It is calculated and is sent to PWM mould by dsp software
Block, cycle reset are then realized by hardware comparator, as inductive current iLfDrop to setting lower limit-IBAfterwards, comparator output electricity
Flat overturning triggering PWM module cycle reset, carries out next switch periods.The implementation can using software prediction control come
Flexibly and easily adjustment service time go forward side by side line delay compensation, while hardware reset control accuracy also ensured with rapidity
The accurate control of inductive current.
Attached drawing 4 is inductive current i under improvement control program proposed by the inventionLfSchematic diagram, attached drawing 9 be the controlling party
Under case in half of power frequency period different load-carrying lower switch frequencies situation of change, can freely adjust power grid by adjusting the value of m
Switching frequency size in voltage zero-cross region (| sin (ω t) |≤a, 0 a≤0.1 <), m value is 15 in legend.
Attached drawing 10 is inverter network voltage and output current phase relation schematic diagram in idle output, according to power grid electricity
Power frequency period is divided into four regions by pressure and the relativeness of output electric current, driver' s timing and inductive current i under different zonesLf
It is idle to export to be both needed to accordingly change, is respectively as follows:
Region I: network voltage ugWith output electric current ioIt is in positive half cycle, i.e. sin (ω t) > 0,(For
Network voltage ugWith output electric current ioAngle), inductive current and switching tube driving are as shown in Figure 11 (c).Q1With Q4It opens simultaneously
It is logical, inductive current iLfIn forward voltage Vdc-ugUnder the action of ramp；Reaching upper limit iupperWhen Q1Shutdown, Q2It is open-minded, electricity
Inducing current iLfIn backward voltage-ugUnder the action of decline；Q4Then until inductive current iLfDrop to switching point electric current imidShi Caihui
It turns off, later Q3It is open-minded, inductive current iLfIn backward voltage-(VDC+ug) continue to decline under effect, until dropping to lower limit ilow
Cycle reset is carried out, next cycle is continued；Q1With Q4Service time be respectively as follows:
Region II: network voltage ugIn negative half period, electric current i is exportedoIn positive half cycle, i.e. sin (ω t) < 0,Inductive current and switching tube driving are as shown in Figure 11 (b).Q1With Q4Open-minded, inductive current i simultaneouslyLfIn forward direction
Voltage Vdc-ugUnder the action of ramp；Unlike the I of region, in inductive current iLfRise to switching point electric current imidWhen Q4
Rate is first turned off, Q3It is open-minded, inductive current iLfIn forward voltage-ugUnder the action of continue to rise；Q1Then until inductive current iLfIt reaches
To upper limit iupperShi Caihui is turned off, later Q2It is open-minded, inductive current iLfIn backward voltage-(VDC+ug) lower straight line decline is acted on, directly
To dropping to lower limit ilowCycle reset is carried out, next cycle is continued；Q1With Q4Service time be respectively as follows:
Region III: network voltage ugWith output electric current ioIt is in negative half period, i.e. sin (ω t) < 0,Electricity
Inducing current and switching tube driving are as shown in Figure 11 (c).Q2With Q3Open-minded, inductive current i simultaneouslyLfIn backward voltage-(VDC+ug) make
Declined with lower straight line；Reach upper limit iupperWhen Q2Shutdown, Q1It is open-minded, inductive current iLfIn forward voltage-ugUnder the action of rise；
Q3Then until inductive current iLfDrop to switching point electric current imidShi Caihui is turned off, later Q4It is open-minded, inductive current iLfIn positive electricity
Press VDC-ugContinue to rise under effect, until rising to lower limit ilowCycle reset is carried out, next cycle is continued；Q2With Q3Open
The logical time is similar with region I, is respectively as follows:
Region IV: network voltage ugIn positive half cycle, electric current i is exportedoIn negative half period, i.e. sin (ω t) > 0,Inductive current and switching tube driving are as shown in Figure 11 (d).Q2With Q3Open-minded, inductive current i simultaneouslyLfReversed
Voltage-(Vdc+ug) under the action of straight line decline；Unlike the II of region, in inductive current iLfReach switching point electric current imidWhen
Q3Rate is first turned off, Q4It is open-minded, inductive current iLfIn backward voltage-ugUnder the action of continue to decline；Q2Then until inductive current iLfIt reaches
To upper limit iupperShi Caihui is turned off, later Q1It is open-minded, inductive current iLfIn forward voltage VDC-ugIt is ramped under effect, until
Rise to lower limit ilowCycle reset is carried out, next cycle is continued；Q2With Q3Service time and region Group III seemingly, be respectively as follows:
It is similar in the case where being 1 with power factor, it is same only voltage zero-crossing point of power grid near zone (sin (ω t)≤
0.1) place leads to current distortion problem using hybrid modulation stratgy to avoid switching frequency is too low, remaining working region still uses
Unipolarity modulation strategy is improved efficiency with reducing switching loss.Its overall inductance current diagram is as shown in figure 12.
Attached drawing 13 gives using improving the inverter simulation waveform after control program, respectively off-grid operation, grid-connected
Operation (network voltage and output current in phase position), be incorporated into the power networks (network voltage lag output electric current), be incorporated into the power networks (power grid electricity
The advanced output electric current of pressure) when simulation waveform, compared under the unipolarity modulation strategy provided in attached drawing 3 and network simulation wave
Shape, it can be seen that output current quality has apparent improvement.
Attached drawing 14 gives using the inverter experimental waveform figure after improvement control program, is not off-grid operation, grid-connected fortune
It goes (network voltage and output current in phase position), be incorporated into the power networks (network voltage lag output electric current), be incorporated into the power networks (network voltage
Advanced output electric current) when simulation waveform, it can be seen that experimental waveform matches with theory analysis and simulation waveform.
Attached drawing 15 is provided respectively using the efficiency curve and THD curve for improving the inverter after control program, by can in figure
To find out, the present invention mention improvement control program under inverter while high-efficiency operation, also can outputting high quality it is grid-connected
Electric current demonstrates the correctness and validity of the control program.
Above content is only illustrations made for the present invention described in this specification.Technology belonging to the present invention
The technical staff in field can do various modifications or supplement or is substituted in a similar manner to described specific embodiment, only
It should belong to guarantor of the invention without departing from the content or beyond the scope defined by this claim of description of the invention
Protect range.
Claims (5)
1. a kind of hybrid modulation stratgy of the full-bridge inverter based on critical current mode, it is characterised in that:
Main circuit topology uses full bridge inverter and LCL filter, including direct current input source (VDC), four switching tube (Q1、Q2、
Q3、Q4), inverter side inductance (Lf), net side inductance (Lo), output capacitance (Co) and power grid/load (Vg)；Control inductive current work
Make in critical continuous mode state, passes through two continued flow switch pipe Q of control in the inductive current decline stage2、Q4The ratio between service time,
Realize the regulation of switching frequency, current distortion problem when improving network voltage zero passage under unipolarity modulation strategy.
2. a kind of hybrid modulation stratgy of the full-bridge inverter based on critical current mode according to claim 1, feature
It is, in network voltage positive half period, the Q when period starts1、Q4It is open-minded, inductive current iLfLinearly rise, rises to inductive current
Upper limit value iupperRate is first turned off Q afterwards1Open Q3, by toff1Q is turned off after time again4Open Q2, inductive current iLfWhole is in broken line
Decline, is down to inductive current lower limit value ilowAfter carry out cycle reset；In network voltage negative half-cycle, the Q when period starts2、Q3It opens
It is logical, inductive current iLfLinearly decline, is down to inductive current upper limit value iupperRate is first turned off Q afterwards3Open Q1, by toff1Time
Turn off Q again afterwards2Open Q4, inductive current iLfIt is whole to rise in broken line, rise to inductive current lower limit value ilowIt is multiple that the period is carried out afterwards
Position.Wherein toff1Expression formula are as follows:
V in formulaDCFor DC input voitage value, VgFor network voltage virtual value, ω t is electric network voltage phase, iupperFor inductance electricity
Flow upper limit value, IBFor resetting current value, m be the service time of different continued flow switch pipes the ratio between.
3. a kind of according to claim 1,2 hybrid modulation stratgy of the full-bridge inverter based on critical current mode, special
Sign is, resetting current IBRemain constant, by adjusting inductive current upper limit iupIt carries out to inductive current iLfDeviate part
Compensation, to guarantee inductive current i in each switch periodsLfAverage value is consistently equal to export current reference ioref, according to inversion
Device operation mode obtains compensated revised inductive current upper limit value iupperExpression formula are as follows:
V in formulaDCFor DC input voitage value, VgFor network voltage virtual value, ω t is electric network voltage phase, iorefExport electric current base
Standard, IBFor resetting current value, m be the service time of different continued flow switch pipes the ratio between.
4. the new improvement controlling party based on a kind of full-bridge inverter on hybrid modulation stratgy described in claim 1,2,3
Case, it is characterised in that: electric network voltage phase exists | sin (ω t) | when crossing in null range of≤a (0≤a≤0.1) is adjusted using mixing
System strategy is to solve the problems, such as existing zero crossing output current oscillations under unipolarity modulation strategy；And | sin (ω t) | > a
It is non-cross null range use unipolarity modulation strategy still to guarantee inverter high-efficiency operation.
5. novel full-bridge inverter control program according to claim 4, which is characterized in that according to network voltage with it is defeated
Entire power frequency period is divided into four regions by the phase relation of electric current out, and inductive current and driver' s timing need phase under different zones
The idle output function to realize inverter, specific manifestation should be adjusted are as follows: when network voltage and output electric current are respectively positioned on positive half cycle
When the phase, inductive current is in the form of first ramping, rear broken line declines, driver' s timing Q1、Q4It is first open-minded, Q is turned off afterwards1, it is open-minded
Q3, turn off Q again later4, open Q2Until cycle reset；When network voltage is located at negative half-cycle, output electric current is located at positive half period
When, inductive current rises in first broken line, in the form of the decline of rear straight line, driver' s timing Q1、Q4It is first open-minded, Q is turned off afterwards4, it is open-minded
Q2, turn off Q again later1, open Q3Until cycle reset；When network voltage and output electric current are respectively positioned on negative half-cycle, inductance electricity
Stream is in the form of first straight line decline, rear broken line rise, driver' s timing Q2、Q3It is first open-minded, Q is turned off afterwards3, open Q1, close again later
Disconnected Q2, open Q4Until cycle reset；When network voltage is located at positive half period, and output electric current is located at negative half-cycle, inductive current
In first broken line decline, after ramp in the form of, driver' s timing Q2、Q3It is first open-minded, Q is turned off afterwards2, open Q4, turn off again later
Q3, open Q1Until cycle reset.
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| CN111952975A (en) * | 2020-07-24 | 2020-11-17 | 易事特集团股份有限公司 | Power grid zero-crossing compensation method |
| CN112928921A (en) * | 2021-01-29 | 2021-06-08 | 哈尔滨工业大学 | Low-output fluctuation soft switching modulation method for wireless power transmission system |
| CN114172404A (en) * | 2022-01-29 | 2022-03-11 | 杭州禾迈电力电子股份有限公司 | Inverter topology circuit and inverter |
| CN114244171A (en) * | 2021-11-30 | 2022-03-25 | 河北工业大学 | Modulation method of unipolar and intermittent bipolar hybrid system of grid-connected inverter |
| CN114759822A (en) * | 2022-05-18 | 2022-07-15 | 三一智慧(广州)科技有限公司 | Single-phase inverter control system of single-polarity and double-polarity hybrid BCM control mode |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN111952975A (en) * | 2020-07-24 | 2020-11-17 | 易事特集团股份有限公司 | Power grid zero-crossing compensation method |
| CN112928921A (en) * | 2021-01-29 | 2021-06-08 | 哈尔滨工业大学 | Low-output fluctuation soft switching modulation method for wireless power transmission system |
| CN112928921B (en) * | 2021-01-29 | 2022-02-11 | 哈尔滨工业大学 | Low-output fluctuation soft switching modulation method for wireless power transmission system |
| CN114244171A (en) * | 2021-11-30 | 2022-03-25 | 河北工业大学 | Modulation method of unipolar and intermittent bipolar hybrid system of grid-connected inverter |
| CN114172404A (en) * | 2022-01-29 | 2022-03-11 | 杭州禾迈电力电子股份有限公司 | Inverter topology circuit and inverter |
| CN114172404B (en) * | 2022-01-29 | 2022-05-17 | 杭州禾迈电力电子股份有限公司 | Inverter topology circuit and inverter |
| CN114759822A (en) * | 2022-05-18 | 2022-07-15 | 三一智慧(广州)科技有限公司 | Single-phase inverter control system of single-polarity and double-polarity hybrid BCM control mode |
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