CN104270022B - Photovoltaic grid connected inversion circuit, switch control circuit and control method - Google Patents
Photovoltaic grid connected inversion circuit, switch control circuit and control method Download PDFInfo
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- CN104270022B CN104270022B CN201410523189.2A CN201410523189A CN104270022B CN 104270022 B CN104270022 B CN 104270022B CN 201410523189 A CN201410523189 A CN 201410523189A CN 104270022 B CN104270022 B CN 104270022B
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Classifications
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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
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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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Abstract
The invention discloses a photovoltaic grid connected inversion circuit, a switch control circuit and a control method and belongs to the technical field of photovoltaic power generation. When the output voltage of a photovoltaic battery pack is larger than the alternating current output voltage of a power grid, a chopped wave switching tube SWc is not switched on, the current flows to an inferior full-bridge inversion unit through a bypass diode Db, and the full-bridge inversion unit works in an SPWM mode; when the output voltage of the photovoltaic battery pack is smaller than or equal to the alternating current output voltage of the power grid, the chopped wave switching tube SWc works in a high-frequency PWM mode, and the full-bridge inversion unit works at the power frequency. Only one level of a converter unit works at the high frequency at any moment so that the efficiency of a whole machine can be improved; due to the fact that a high-capacity electrolysis direct current capacitor set is not used, a solar photovoltaic power generation system which is small in size, light in weight and low in cost can be obtained.
Description
Technical field
The present invention relates to technical field of photovoltaic power generation, more particularly, it relates to a kind of photovoltaic grid-connected inversion circuit, switch control
Circuit processed and control method.
Background technology
From the viewpoint of environmental protection, application on residential electric power for the small-scale distributed solar energy photovoltaic generating system is more next
More welcome.For solar photovoltaic generation system, non-isolated single-phase sinewave inverter topological structure is in cost, size
There is advantage with efficiency aspect, this makes non-isolated grid-connected structure have good development prospect.Non-isolated sine wave is inverse
Become device main circuit and mainly include two working portions：One is the boosting part for lifting from photovoltaic module array low-voltage；
Two is to be connected to electrical network or the Converting Unit of directly load-carrying high-frequency PWM modulation for exchange.
The prime of traditional two-stage type combining inverter typically to lift input voltage, rear class using Boost boosting unit
Inverter is directly converted to alternating current.Prime boosting unit is constantly in high-frequency PWM modulation condition, later stage inversion unit then with
SPWM (sinusoidal pulse width modulation) mode high frequency modulated, so prime boosting part and rear class Converting Unit are operated in high frequency shape simultaneously
State, the switching loss of switching tube is very big, is unfavorable for the raising of overall efficiency.In addition, in order to keep boost after voltage be
Constant, the electrolysis condenser group being connected in dc bus needs sufficiently high electric capacity.Therefore electrolysis condenser packet size is big, and
There is the ripple current of higher frequency, due to the presence of equivalent series resistance, power attenuation can be caused, and electrolysis direct current electric capacity
Device group is heavy, high to temperature requirement, short life.
Through retrieval, Chinese Patent Application No. 201110353854.4, the applying date is on November 10th, 2011, innovation and creation name
Referred to as：Photovoltaic combining inverter inversion of direct current busbar voltage control method and control system, the photovoltaic DC-to-AC converter of this application case increases
One bypass diode is in parallel with Boost circuit, and in photovoltaic cell outlet side bulky capacitor in parallel.This application case
Voltage control method comprises the following steps：Collection line voltage Vac and input direct voltage Vpv；Whether judge Vpv >=1.6Vac
Set up；As being judged as YES, close Boost circuit；As being judged as NO, open Boost circuit；Input direct voltage Vpv is carried out
Inversion.This application case passes through real-time adjustment busbar voltage, to reduce the working time of Boost circuit, reduces electromagnetic interference, one
Determine to improve system effectiveness in degree.But the Boost circuit part of this application case photovoltaic DC-to-AC converter includes two bulky capacitor, above
Analysis because the photovoltaic DC-to-AC converter volume being introduced using bulky capacitor big, heavy, be also easy to produce altofrequency ripple current and power and damage
Not only the problems such as consume big is not eased but more serious, photovoltaic DC-to-AC converter manufacturing cost is high and stability is bad；Additionally, should
The Converting Unit of application case still always works at high frequency state, and switching loss is big, and overall efficiency is low.
Content of the invention
1. invent technical problem to be solved
It is an object of the invention to solving what conventional photovoltaic inverter existed：1) switching loss is big, overall efficiency is low；2) by
In leading to, using big capacity electrolyte capacitor device group, the problems such as photovoltaic DC-to-AC converter volume is big, heavy, and power attenuation is big；Provide one kind
Photovoltaic grid-connected inversion circuit, ON-OFF control circuit and control method.The technical scheme being provided using the present invention, according to input voltage
To determine the mode of operation of 2 stage converter unit with the magnitude relationship of line voltage, so that any time only has one-level becoming
Exchange unit high-frequency work, is conducive to the raising of overall efficiency；Further, since not using Large Copacity electrolysis direct current capacitor bank,
Little, the lightweight and inexpensive solar photovoltaic generation system of size can be realized.
2. technical scheme
For reaching above-mentioned purpose, the technical scheme that the present invention provides is：
A kind of photovoltaic grid-connected inversion circuit of the present invention, including DC boosting unit, full-bridge inverting unit, filter unit,
Photovoltaic cell group and electrical network, wherein：
Described full-bridge inverting unit is connected with DC boosting unit, and this full-bridge inverting unit is by full-bridge inverting switching tube
SW1、SW2、SW3、SW4The inverter bridge of composition；
Described filter unit includes filter inductance LfWith filter capacitor Cf, filter inductance LfFirst end and described full-bridge
Inverse switch pipe SW1、SW2The intermediate point of composition brachium pontis connects, this filter inductance LfThe second end respectively with filter capacitor Cf?
One end, one end connection, the other end of electrical network and the filter capacitor C of electrical networkfSecond end connect；Filter capacitor CfThe second end also
With full-bridge inverting switching tube SW3、SW4The intermediate point of composition brachium pontis connects；
Described DC boosting unit includes bypass diode Db, boost inductance Lb, diode Dc, chopping switching tube SWc and
Intermediate capacitance Cc, the positive pole of photovoltaic cell group respectively with bypass diode DbPositive pole, boost inductance LbFirst end connect, other
Road diode DbNegative pole respectively with diode DcNegative pole, intermediate capacitance Cc first end connect, boost inductance LbThe second end
It is connected with the positive pole of diode Dc, the colelctor electrode of chopping switching tube SWc respectively；The negative pole of described photovoltaic cell group respectively with cut
The emitter stage of ripple switching tube SWc, the second end of intermediate capacitance Cc connect.
Further, described intermediate capacitance Cc is low capacity thin-film capacitor.
A kind of ON-OFF control circuit of photovoltaic grid-connected inversion circuit of the present invention, including chopping switching tube SWc control circuit
With full-bridge inverting switching tube SW1、SW2、SW3、SW4Control circuit, wherein：
In described chopping switching tube SWc control circuit, the signal output part of sine-wave generator I is through I point of full wave rectifier
Be not connected with the in-phase input end of comparator I, the input of DSP microprocessor, the signal output part of signal picker respectively with
The inverting input of comparator I, the input of DSP microprocessor connect, and comparator I, the signal output part of DSP microprocessor divide
It is not connected with the input of multiplier I, the output signal of multiplier I is as the drive signal of SWc；
Described full-bridge inverting switching tube SW1、SW2、SW3、SW4The signal output of sine-wave generator II in control circuit
End is connected with the in-phase input end of comparator II through full wave rectifier II, the signal output part of triangular-wave generator and comparator II
Inverting input connect；The signal output part of sine-wave generator III is connected with the in-phase input end of comparator III, comparator
III inverting input is connected with no-voltage；The signal output part of sine-wave generator IV is connected with the inverting input of comparator IV
Connect, the in-phase input end of comparator IV is connected with no-voltage；Comparator II, the signal output part of comparator III and multiplier II
Input is connected, and the output signal of multiplier II is as SW1Drive signal, multiplier II connect phase inverter I output signal make
For SW2Drive signal；Comparator II, the signal output part of comparator IV are connected with the input of multiplier III, multiplier III
Output signal as SW3Drive signal, multiplier III connects the output signal of phase inverter II as SW4Drive signal.
A kind of control method of photovoltaic grid-connected inversion circuit of the present invention, its step is：
Step one, judge photovoltaic cell group output voltage VinWhether it is more than electrical network ac output voltage absolute value | Vout|；
Step 2, by step one judged result control chopping switching tube SWc break-make, if Vin＞ | Vout|, then control
SWc turns off；If Vin≤|Vout|, then control SWc to be operated in high-frequency PWM state；
Step 3, the break-make control full-bridge inverting switching tube SW according to SWc1、SW2、SW3、SW4Break-make, if SWcTurn off,
Then control SW1、SW2、SW3、SW4It is operated in SPWM modulating mode, if SWcIt is operated in high-frequency PWM state, then control SW1、SW2、
SW3、SW4With the work of power frequency modulation system.
Further, the detailed process of step 2 control chopping switching tube SWc break-make is：Sine-wave generator I produces
Standard AC sine wave, after full wave rectifier I rectification, the in-phase input end of input comparator I and DSP microprocessor is defeated
Enter end, signal picker gathers the output voltage V of photovoltaic cell groupinThe inverting input of input comparator I and DSP microprocessor
The input of device, compares, through comparator I, the pulse train obtaining and the signal through DSP microprocessor processes passes through multiplier I
It is multiplied, the pulse train of multiplier I output controls SWcBreak-make.
Further, step 3 controls full-bridge inverting switching tube SW1、SW2、SW3、SW4The detailed process of break-make is：Just
String wave producer II generation standard AC sine wave, the in-phase input end of input comparator II after full wave rectifier II rectification,
It is V that triangular-wave generator produces amplitudeinTriangular wave input comparator II inverting input；Sine-wave generator III produces mark
The in-phase input end of quasi- AC sine wave input comparator III, is compared through comparator III with no-voltage；Sine-wave generator IV
Produce the inverting input of standard AC sine wave input comparator IV, compare through comparator IV with no-voltage；Comparator II, ratio
It is multiplied by multiplier II compared with the output signal of device III, the output signal of multiplier II controls SW1Break-make, multiplier II is reversed
The output signal of phase device I controls SW2Break-make；Comparator II, the output signal of comparator IV are multiplied by multiplier III, multiplication
The output signal of device III controls SW3Break-make, multiplier III connect phase inverter II output signal control SW4Break-make.
Further, the output signal of described DSP microprocessor is pulse regulation dutycycle
3. beneficial effect
The technical scheme being provided using the present invention, compared with existing known technology, has following remarkable result：
(1) a kind of photovoltaic grid-connected inversion circuit of the present invention, boost inductance L in its DC boosting unitbWith diode Dc
Series arm on be parallel with a bypass diode Db, when photovoltaic cell group output voltage is higher than line voltage, chopping switch
Pipe SWc is not turned on, and electric current passes through bypass diode DbFlow to full-bridge inverting unit, full-bridge inverting unit High ireguency SPWM works；When
When photovoltaic cell group output voltage is less than line voltage, chopping switching tube SWc high frequency modulated, full-bridge inverting unit power frequency works；
Magnitude relationship according to input voltage and line voltage is determining the mode of operation of 2 stage converter unit, so that boosting is cut
Ripple and full-bridge inverting are operated under high frequency mode in synchronization only stage circuit, reduce total on-off times, are conducive to
The raising of overall efficiency；
(2) control method of a kind of photovoltaic grid-connected inversion circuit of the present invention, it controls prime DC boosting cell operation
In PWM mode, provide sinusoidal half-wave voltage for rear class full-bridge inverting unit, rear class full-bridge inverting unit only needs power frequency switching work
Work can complete sinusoidal current injection electrical network；When prime DC boosting unit leads directly to, rear class full-bridge inverting cell operation is in SPWM
Mode；This kind of mode of operation, keeps constant voltage, available low capacity, the thin film capacitor of small size without intermediate DC link
Replace jumbo electrolysis condenser it is achieved that the miniaturization of inverter system and lightness, the job stability of inverter
It is improved；Additionally, when full-bridge inverting cell S PWM mode works, input current is through bypass diode Db, and do not flow
Cross boost inductance LbWith diode Dc, the conduction loss of booster circuit greatly reduces.
Brief description
Fig. 1 is the structure chart of the photovoltaic grid-connected inversion circuit of the present invention；
(a) in Fig. 2 is the fundamental diagram of the boost chopper part of the present invention；(b) in Fig. 2 is the full-bridge of the present invention
The fundamental diagram of Converting Unit；
Fig. 3 is the switching pulse sequence chart of the present invention
(a) in Fig. 4 is for driving the circuit structure diagram of chopping switching tube SWc in the ON-OFF control circuit of the present invention；In Fig. 4
(b) be the present invention ON-OFF control circuit in drive full-bridge inverting switching tube SW1、SW2、SW3、SW4Circuit structure diagram；
Fig. 5 is intermediate capacitance C in the present inventioncVoltage oscillogram；
Fig. 6 is filter unit input side voltage oscillogram in the present invention；
Fig. 7 is the control flow block diagram of the photovoltaic grid-connected inversion circuit of the present invention.
Label declaration in schematic diagram：
1- DC boosting unit；2- full-bridge inverting unit；3- filter unit；4- photovoltaic cell group；5- electrical network；Db- bypass
Diode；Lb- boost inductance；Dc- diode；SWc- chopping switching tube；Cc- intermediate capacitance；SW1、SW2、SW3、SW4- full-bridge is inverse
Become switching tube；Lf- filter inductance；Cf- filter capacitor.
Specific embodiment
For further appreciating that present disclosure, the present invention is described in detail in conjunction with the accompanying drawings and embodiments.
Embodiment 1
In conjunction with Fig. 1, a kind of photovoltaic grid-connected inversion circuit of the present embodiment, including DC boosting unit 1, full-bridge inverting unit
2nd, filter unit 3, photovoltaic cell group 4 and electrical network 5, wherein：
Described DC boosting unit 1 includes bypass diode Db, boost inductance Lb, diode Dc, chopping switching tube SWc
With intermediate capacitance Cc, the positive pole of photovoltaic cell group 4 respectively with bypass diode DbPositive pole, boost inductance LbFirst end connect,
Bypass diode DbNegative pole respectively with diode DcNegative pole, intermediate capacitance Cc first end connect, boost inductance LbSecond
End is connected with the positive pole of diode Dc, the colelctor electrode of chopping switching tube SWc respectively；The negative pole of described photovoltaic cell group 4 is respectively
It is connected with the emitter stage of chopping switching tube SWc, the second end of intermediate capacitance Cc.
Described full-bridge inverting unit 2 is by full-bridge inverting switching tube SW1、SW2、SW3、SW4The inverter bridge of composition, inversion
The first end of bridge and intermediate capacitance CcSecond end connect, inverter bridge the second end be connected with the negative pole of photovoltaic cell group 4.
Described filter unit 3 includes filter inductance LfWith filter capacitor Cf, filter inductance LfFirst end and described full-bridge
Inverse switch pipe SW1、SW2The intermediate point of composition brachium pontis connects, this filter inductance LfThe second end respectively with filter capacitor Cf?
One end, one end connection, the other end of electrical network 5 and the filter capacitor C of electrical network 5fSecond end connect；Filter capacitor CfThe second end
Also with full-bridge inverting switching tube SW3、SW4The intermediate point of composition brachium pontis connects.
Photovoltaic cell group 4 exports the direct current input side that unidirectional current first accesses DC boosting unit 1, and DC boosting unit 1 enters
Row boosting inverter, the unidirectional current after boosting accesses the direct current input side of full-bridge inverting unit 2 again, and full-bridge inverting unit 2 is by direct current
Electricity is changed into alternating current, by accessing electrical network 5 or load after filter unit 3.
Referring to (a) and (b) in Fig. 4, a kind of ON-OFF control circuit of photovoltaic grid-connected inversion circuit of the present embodiment, including
Chopping switching tube SWc control circuit and full-bridge inverting switching tube SW1、SW2、SW3、SW4Control circuit, wherein：
In described chopping switching tube SWc control circuit, the signal output part of sine-wave generator I is through I point of full wave rectifier
Be not connected with the in-phase input end of comparator I, the input of DSP microprocessor, the signal output part of signal picker respectively with
The inverting input of comparator I, the input of DSP microprocessor connect, and comparator I, the signal output part of DSP microprocessor divide
It is not connected with the input of multiplier I, the output signal of multiplier I is as the drive signal of SWc.
Described full-bridge inverting switching tube SW1、SW2、SW3、SW4The signal output of sine-wave generator II in control circuit
End is connected with the in-phase input end of comparator II through full wave rectifier II, the signal output part of triangular-wave generator and comparator II
Inverting input connect；The signal output part of sine-wave generator III is connected with the in-phase input end of comparator III, comparator
III inverting input is connected with no-voltage；The signal output part of sine-wave generator IV is connected with the inverting input of comparator IV
Connect, the in-phase input end of comparator IV is connected with no-voltage；Comparator II, the signal output part of comparator III and multiplier II
Input is connected, and the output signal of multiplier II is as SW1Drive signal, multiplier II connect phase inverter I output signal make
For SW2Drive signal；Comparator II, the signal output part of comparator IV are connected with the input of multiplier III, multiplier III
Output signal as SW3Drive signal, multiplier III connects the output signal of phase inverter II as SW4Drive signal.
Fig. 2 describes the present embodiment and utilizes described ON-OFF control circuit to control the operation principle of photovoltaic grid-connected inversion circuit,
(a) in Fig. 2 is the operation principle of boost chopper part；(b) in Fig. 2 is the operation principle of full-bridge inverting part；Work as photovoltaic
Set of cells 4 output voltage VinThan electrical network 5 ac output voltage absolute value | Vout| when big, chopping switching tube SWc is off shape
State, input current flows through bypass diode Db, and it is not passed through boost inductance LbWith diode Dc, the output electricity of DC boosting unit 1
Pressure is equal to input direct voltage Vin, in such cases, full-bridge inverting switching tube SW1、SW2、SW3、SW4It is operated in SPWM modulation mould
Formula；As photovoltaic cell group 4 output voltage VinLess than or equal to electrical network 5 ac output voltage absolute value | Vout| when, chopping switching tube
SWc is operated in high-frequency PWM pattern, intermediate capacitance CcUsing low capacity thin-film capacitor so that the output voltage of DC boosting unit 1
Produce quasi sine amplitude modulation waveform.Now, full-bridge inverting switching tube (SW1～SW4) with the work of power frequency modulation system, make output
Voltage is synchronous with electrical network 5 polarity.Due under this kind of mode of operation, keep constant voltage without intermediate DC link, with low capacity,
The thin film capacitor of small size replaces jumbo electrolysis condenser, and the thin film capacitor that the present embodiment adopts is metallization
Poly- second membrane of lipoprotein capacitor MEF (CL21) is it is achieved that the miniaturization of inverter system and lightness, the job stability of inverter
Also it is improved.The present embodiment determines the work of 2 stage converter unit according to the magnitude relationship of input voltage and line voltage
Operation mode, so that boost chopper and full-bridge inverting are operated under high frequency mode in synchronization only stage circuit, reduces
Total on-off times, are conducive to the raising of overall efficiency.
Referring to Fig. 7, the concrete control process of the present embodiment is：
Step one, judge photovoltaic cell group 4 output voltage VinWhether it is more than electrical network 5 ac output voltage absolute value | Vout|.
Step 2, by step one judged result control chopping switching tube SWc break-make, if Vin＞ | Vout|, then control
SWc turns off；If Vin≤|Vout|, then control SWc to be operated in high-frequency PWM state；Control the concrete mistake of chopping switching tube SWc break-make
Cheng Wei：Sine-wave generator I produces standard AC sine wave, the homophase input of input comparator I after full wave rectifier I rectification
End and the input of DSP F2812 microprocessor, signal picker gathers the output voltage V of photovoltaic cell group 4inInput is compared
The inverting input of device I and the input of DSP F2812 microprocessor, through comparator I compare the pulse train obtaining and
The pulse regulation dutycycle of output after DSP microprocessor processesSignal is multiplied by multiplier I, multiplication
The pulse train of device I output controls SWcBreak-make.
Step 3, the break-make control full-bridge inverting switching tube SW according to SWc1、SW2、SW3、SW4Break-make, if SWcTurn off,
Then control SW1、SW2、SW3、SW4It is operated in SPWM modulating mode, if SWcIt is operated in high-frequency PWM state, then control SW1、SW2、
SW3、SW4With the work of power frequency modulation system.Control full-bridge inverting switching tube SW1、SW2、SW3、SW4The detailed process of break-make is：Just
String wave producer II generation standard AC sine wave, the in-phase input end of input comparator II after full wave rectifier II rectification,
It is V that triangular-wave generator produces amplitudeinTriangular wave input comparator II inverting input；Sine-wave generator III produces mark
The in-phase input end of quasi- AC sine wave input comparator III, is compared through comparator III with no-voltage；Sine-wave generator IV
Produce the inverting input of standard AC sine wave input comparator IV, compare through comparator IV with no-voltage；Comparator II, ratio
It is multiplied by multiplier II compared with the output signal of device III, the output signal of multiplier II controls SW1Break-make, multiplier II is reversed
The output signal of phase device I controls SW2Break-make；Comparator II, the output signal of comparator IV are multiplied by multiplier III, multiplication
The output signal of device III controls SW3Break-make, multiplier III connect phase inverter II output signal control SW4Break-make.
Fig. 3 describes the pulse train of each switching tube of the present embodiment, in the positive half period of AC sine output voltage, SW3
It is not turned on, SW4Straight-through, when photovoltaic cell group 4 output voltage is more than AC sine output voltage, chopping switching tube SWc does not lead
Logical, full-bridge inverting switching tube SW1、SW2Modulate conducting through SPWM；When photovoltaic cell group 4 output voltage is less than or equal to AC sine
During output voltage, chopping switching tube SWcAccording to dutycycleHigh frequency modulated, SW1Straight-through, SW2It is not turned on.Handing over
The negative half-cycle of stream sine output voltage, SW1It is not turned on, SW2Straight-through, when the negative value of photovoltaic cell group 4 output voltage is less than exchange
During sine output voltage, chopping switching tube SWcIt is not turned on, full-bridge inverting switching tube SW3、SW4Modulate conducting through SPWM；Work as light
When the negative value of volt set of cells 4 output voltage is more than AC sine output voltage, chopping switching tube SWcAccording to dutycycleHigh frequency modulated, full-bridge inverting switching tube SW3Straight-through, SW4It is not turned on.
Fig. 5 and 6 is the concrete simulation waveform of the present embodiment, and wherein, Fig. 5 is intermediate capacitance CcVoltage oscillogram, Fig. 6
For filter unit 3 input side voltage oscillogram.Photovoltaic cell group 4 voltage 160V in the present embodiment, electrical network 5 voltage 220Vrms, electricity
Net 5 frequency fgrid=50Hz, boost inductance Lb=0.9mH, intermediate capacitance Cc=2.2uF, filter inductance Lf=1mH, filter capacitor
Cf=10uF, switching frequency f=50kHz.
A kind of photovoltaic grid-connected inversion circuit described in embodiment 1, ON-OFF control circuit and control method, control prime direct current
When boosting unit 1 is operated in PWM mode, provide sinusoidal half-wave voltage, rear class full-bridge inverting unit 2 for rear class full-bridge inverting unit
Only need power frequency switch operating can complete sinusoidal current injection electrical network；When prime DC boosting unit 1 leads directly to, rear class full-bridge inverting
Unit 2 works in SPWM mode, and any time only has one-stage transfor-mation device unit high-frequency work；This kind of mode of operation, need not be middle
DC link keeps constant voltage, and available low capacity, the thin film capacitor of small size replace jumbo electrolysis condenser, realize
The miniaturization of inverter system and lightness, the job stability of inverter is also improved；Additionally, working as full-bridge inverting list
During first SPWM pattern work, input current is through bypass diode Db, and without flow through boost inductance LbWith diode Dc, rise piezoelectricity
The conduction loss on road greatly reduces.
Below schematically the present invention and embodiments thereof are described, this description does not have restricted, institute in accompanying drawing
Show is also one of embodiments of the present invention, and actual structure is not limited thereto.So, if the common skill of this area
Art personnel enlightened by it, in the case of without departing from the invention objective, designs and this technical scheme without creative
Similar frame mode and embodiment, all should belong to protection scope of the present invention.
Claims (7)
1. a kind of photovoltaic grid-connected inversion circuit, including DC boosting unit (1), full-bridge inverting unit (2), filter unit (3), light
Volt set of cells (4), electrical network (5), chopping switching tube SWc control circuit and full-bridge inverting switching tube SW1、SW2、SW3、SW4Control electricity
Road, wherein：
Described full-bridge inverting unit (2) is connected with DC boosting unit (1), and this full-bridge inverting unit (2) is by full-bridge inverting
Switching tube SW1、SW2、SW3、SW4The inverter bridge of composition；
Described filter unit (3) includes filter inductance LfWith filter capacitor Cf, filter inductance LfFirst end inverse with described full-bridge
Become switching tube SW1、SW2The intermediate point of composition brachium pontis connects, this filter inductance LfThe second end respectively with filter capacitor CfFirst
End, one end connection, the other end of electrical network (5) and the filter capacitor C of electrical network (5)fSecond end connect；Filter capacitor CfSecond
End also with full-bridge inverting switching tube SW3、SW4The intermediate point of composition brachium pontis connects；It is characterized in that：
Described DC boosting unit (1) includes bypass diode Db, boost inductance Lb, diode Dc, chopping switching tube SWc and
Intermediate capacitance Cc, the positive pole of photovoltaic cell group (4) respectively with bypass diode DbPositive pole, boost inductance LbFirst end connect,
Bypass diode DbNegative pole respectively with diode DcNegative pole, intermediate capacitance Cc first end connect, boost inductance LbSecond
End is connected with the positive pole of diode Dc, the colelctor electrode of chopping switching tube SWc respectively；The negative pole of described photovoltaic cell group (4) divides
It is not connected with the emitter stage of chopping switching tube SWc, the second end of intermediate capacitance Cc；
In described chopping switching tube SWc control circuit the signal output part of sine-wave generator I through full wave rectifier I respectively with
The in-phase input end of comparator I, the input of DSP microprocessor connect, the signal output part of signal picker respectively with compare
The inverting input of device I, DSP microprocessor input connect, comparator I, DSP microprocessor signal output part respectively with
The input of multiplier I is connected, and the output signal of multiplier I is as the drive signal of SWc；
Described full-bridge inverting switching tube SW1、SW2、SW3、SW4In control circuit, the signal output part of sine-wave generator II is through complete
Ripple commutator II is connected with the in-phase input end of comparator II, and the signal output part of triangular-wave generator is anti-phase with comparator II
Input connects；The signal output part of sine-wave generator III is connected with the in-phase input end of comparator III, comparator III anti-
Phase input is connected with no-voltage；The signal output part of sine-wave generator IV is connected with the inverting input of comparator IV, than
It is connected with no-voltage compared with the in-phase input end of device IV；The input of comparator II, the signal output part of comparator III and multiplier II
End is connected, and the output signal of multiplier II is as SW1Drive signal, multiplier II connects the output signal of phase inverter I as SW2
Drive signal；Comparator II, the signal output part of comparator IV are connected with the input of multiplier III, the output of multiplier III
Signal is as SW3Drive signal, multiplier III connects the output signal of phase inverter II as SW4Drive signal.
2. a kind of photovoltaic grid-connected inversion circuit according to claim 1 it is characterised in that：Described intermediate capacitance Cc is little
Capacity thin-film capacitor.
3. a kind of ON-OFF control circuit of photovoltaic grid-connected inversion circuit it is characterised in that：Including chopping switching tube SWc control circuit
With full-bridge inverting switching tube SW1、SW2、SW3、SW4Control circuit, wherein：
In described chopping switching tube SWc control circuit the signal output part of sine-wave generator I through full wave rectifier I respectively with
The in-phase input end of comparator I, the input of DSP microprocessor connect, the signal output part of signal picker respectively with compare
The inverting input of device I, DSP microprocessor input connect, comparator I, DSP microprocessor signal output part respectively with
The input of multiplier I is connected, and the output signal of multiplier I is as the drive signal of SWc；
Described full-bridge inverting switching tube SW1、SW2、SW3、SW4In control circuit, the signal output part of sine-wave generator II is through complete
Ripple commutator II is connected with the in-phase input end of comparator II, and the signal output part of triangular-wave generator is anti-phase with comparator II
Input connects；The signal output part of sine-wave generator III is connected with the in-phase input end of comparator III, comparator III anti-
Phase input is connected with no-voltage；The signal output part of sine-wave generator IV is connected with the inverting input of comparator IV, than
It is connected with no-voltage compared with the in-phase input end of device IV；The input of comparator II, the signal output part of comparator III and multiplier II
End is connected, and the output signal of multiplier II is as SW1Drive signal, multiplier II connects the output signal of phase inverter I as SW2
Drive signal；Comparator II, the signal output part of comparator IV are connected with the input of multiplier III, the output of multiplier III
Signal is as SW3Drive signal, multiplier III connects the output signal of phase inverter II as SW4Drive signal.
4. the control method of a kind of photovoltaic grid-connected inversion circuit according to claim 1, its step is：
Step one, judge photovoltaic cell group (4) output voltage VinWhether it is more than electrical network (5) ac output voltage absolute value | Vout|；
Step 2, by step one judged result control chopping switching tube SWc break-make, if Vin＞ | Vout|, then control SWc to close
Disconnected；If Vin≤|Vout|, then control SWc to be operated in high-frequency PWM state；
Step 3, the break-make control full-bridge inverting switching tube SW according to SWc1、SW2、SW3、SW4Break-make, if SWcTurn off, then control
SW processed1、SW2、SW3、SW4It is operated in SPWM modulating mode, if SWcIt is operated in high-frequency PWM state, then control SW1、SW2、SW3、SW4
With the work of power frequency modulation system.
5. a kind of photovoltaic grid-connected inversion circuit according to claim 4 control method it is characterised in that：Step 2 controls
The detailed process of chopping switching tube SWc break-make is：Sine-wave generator I produces standard AC sine wave, whole through full wave rectifier I
The input of the in-phase input end of input comparator I and DSP microprocessor after stream, signal picker gathers photovoltaic cell group
(4) output voltage VinThe inverting input of input comparator I and the input of DSP microprocessor, compare through comparator I
To pulse train and the signal through DSP microprocessor processes be multiplied by multiplier I, multiplier I output pulse train
Control SWcBreak-make.
6. a kind of photovoltaic grid-connected inversion circuit according to claim 5 control method it is characterised in that：Step 3 controls
Full-bridge inverting switching tube SW1、SW2、SW3、SW4The detailed process of break-make is：It is sinusoidal that sine-wave generator II produces standard AC
Ripple, the in-phase input end of input comparator II after full wave rectifier II rectification, it is V that triangular-wave generator produces amplitudeinThree
The inverting input of angle ripple input comparator II；Sine-wave generator III produces the same of standard AC sine wave input comparator III
Phase input, is compared through comparator III with no-voltage；Sine-wave generator IV also produces standard AC sine wave input comparator
IV inverting input, is compared through comparator IV with no-voltage；Comparator II, the output signal of comparator III pass through multiplier II
It is multiplied, the output signal of multiplier II controls SW1Break-make, multiplier II connect phase inverter I output signal control SW2Break-make；
Comparator II, the output signal of comparator IV are multiplied by multiplier III, and the output signal of multiplier III controls SW3Break-make,
The output signal that multiplier III connects phase inverter II controls SW4Break-make.
7. a kind of photovoltaic grid-connected inversion circuit according to claim 5 or 6 control method it is characterised in that：Described
The output signal of DSP microprocessor is pulse regulation dutycycle
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| CN105337520A (en) * | 2015-12-11 | 2016-02-17 | 珠海格力电器股份有限公司 | Photovoltaic grid-connected converter, photovoltaic power supply system and electric appliance |
| CN107070215B (en) * | 2017-04-12 | 2023-05-16 | 特变电工西安电气科技有限公司 | Three-level boost common-ground system and control method thereof |
| CN107645246A (en) * | 2017-11-08 | 2018-01-30 | 胡炎申 | A kind of two-stage type single-phase inverter |
| CN107706946A (en) * | 2017-12-06 | 2018-02-16 | 中山市柏顺照明电器有限公司 | Single-phase solar photovoltaic power generation grid-connecting electricity generation system |
| CN108418416A (en) * | 2018-03-19 | 2018-08-17 | 盐城工学院 | A kind of cooperative control method of Partial Power processing boosting unit and gird-connected inverter |
| CN111934578B (en) * | 2020-08-02 | 2022-04-05 | 国网湖北省电力有限公司武汉供电公司 | Dual-mode photovoltaic inverter circuit system based on hybrid control |
| CN113300627B (en) * | 2021-05-18 | 2022-06-07 | 西南交通大学 | Discrete control method and device of single-phase full-bridge inverter |
| CN113507230A (en) * | 2021-07-06 | 2021-10-15 | 国网福建省电力有限公司检修分公司 | Combined boosting inversion system based on switch capacitance-sensing network and control method thereof |
| CN115441695B (en) * | 2022-06-09 | 2024-02-20 | 湖南工程学院 | Inverter modulation method for improving power density of low-voltage input and high-voltage output |
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