CN107517020A - A kind of grid-connected micro- inverter of stage photovoltaic single and its control method - Google Patents
A kind of grid-connected micro- inverter of stage photovoltaic single and its control method Download PDFInfo
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- CN107517020A CN107517020A CN201710774313.6A CN201710774313A CN107517020A CN 107517020 A CN107517020 A CN 107517020A CN 201710774313 A CN201710774313 A CN 201710774313A CN 107517020 A CN107517020 A CN 107517020A
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- 238000000034 method Methods 0.000 title claims abstract description 16
- 238000001514 detection method Methods 0.000 claims abstract description 15
- 238000005070 sampling Methods 0.000 claims description 34
- 230000005611 electricity Effects 0.000 claims description 26
- 230000008859 change Effects 0.000 claims description 11
- 239000003990 capacitor Substances 0.000 claims description 8
- 238000003199 nucleic acid amplification method Methods 0.000 claims description 8
- 230000003321 amplification Effects 0.000 claims description 7
- 238000001914 filtration Methods 0.000 claims description 7
- 230000000630 rising effect Effects 0.000 claims description 5
- 230000008569 process Effects 0.000 claims description 4
- 230000009471 action Effects 0.000 claims description 3
- 230000009467 reduction Effects 0.000 claims description 2
- 230000005284 excitation Effects 0.000 abstract description 10
- 238000002955 isolation Methods 0.000 abstract description 8
- 230000002457 bidirectional effect Effects 0.000 abstract description 3
- 230000015572 biosynthetic process Effects 0.000 abstract description 2
- 238000004520 electroporation Methods 0.000 abstract description 2
- 208000032370 Secondary transmission Diseases 0.000 abstract 1
- 230000002459 sustained effect Effects 0.000 description 4
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- 101100489713 Saccharomyces cerevisiae (strain ATCC 204508 / S288c) GND1 gene Proteins 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 229920006395 saturated elastomer Polymers 0.000 description 2
- 101100489717 Saccharomyces cerevisiae (strain ATCC 204508 / S288c) GND2 gene Proteins 0.000 description 1
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- 230000000295 complement effect Effects 0.000 description 1
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Classifications
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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
-
- H02J3/383—
-
- 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
- H02M7/5375—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 with special starting equipment
-
- 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
- H02M7/5383—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 self-oscillating arrangement
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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
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/388—Islanding, i.e. disconnection of local power supply from the network
-
- 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
- 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
Abstract
The invention belongs to electroporation field, it is related to a kind of grid-connected micro- inverter of stage photovoltaic single and its control method, isolating transformer primary side only realizes transformer bidirectional excitation with a switching tube, and switching tube can not only realize that no-voltage was opened but also can realize zero voltage turn-off, can be to transformer secondary transmission energy during turning on and off；Transformer secondary uses two sets of high frequency full-wave rectifying circuits, it is allowed to be exported by power frequency and then reverse parallel connection by control, the pulse train changed with reference to the modulation formation of transformer primary side HF switch pipe by Sine Modulated rule, becoming after filtered can be with grid-connected industrial-frequency alternating current；Its circuit structure is simple, small volume, cost is low, efficiency high, reliability is high, in addition to can be dedicated for grid-connected micro- inverter, available for other small-sized combining inverters, in vehicle-mounted inverter, ups power, frequency converter, isolation boosting DC AC converters can be also promoted the use of after removing isolated island detection and lock phase program.
Description
Technical field：
The invention belongs to electroporation field, is related to a kind of grid-connected micro- inverter and its control method, particularly a kind of pin
To the grid-connected micro- inverter of novel high-efficiency single-stage formula and its control method of monolithic solar panel.
Background technology：
Traditional grid-connected micro- inverter typically has following three kinds of structure type：The first is non-isolation type two-stage type knot
Structure, i.e. prime are boosted with non-isolated Boost circuit, and rear class H bridge inversions, its advantage is that circuit is relatively easy, and shortcoming is micro- inverse
The output and cell panel for becoming device are not isolated, and can bring potential safety hazard, and its is less efficient.Second is isolated form two-stage type knot
Structure, i.e. prime isolation voltage or current mode half-bridge LLC circuits boost, and rear class H bridge inversions, its advantage is the defeated of micro- inverter
Go out realizes electrical isolation with cell panel, eliminates potential safety hazard, and its front stage circuits can realize Sofe Switch by resonance, preceding
Level circuit efficiency is relatively higher, and its shortcoming is that inverter volume is relatively large, and cost is higher, and prime is current mode half-bridge LLC
Circuit control is relative complex, and needs two inductance, adds the volume of inverter；Prime is voltage-fed half-bridge LLC circuit controls
Make relative complex, two switching tubes are easily straight-through and burn circuit up and down for bridge arm；The third is isolated form single stage type structure, at present
Transformer primary side typically uses work using flyback, interleaving inverse excitation type or interleaving inverse excitation active-clamp type circuit, transformer secondary
Frequency inversion, i.e., it can not only realize electrical isolation with stage circuit but also possibility of reversal is grid-connected, and rear class H-bridge inverter circuit eliminated, for anti-
Swash type or interleaving inverse excitation type circuit, its advantage is that circuit structure is simple, is easily controlled, and shortcoming is the unidirectional excitation of transformer, magnetic core
It is easily saturated, power is difficult to do greatly, and switching tube can not realize Sofe Switch, relatively inefficient；For interleaving inverse excitation active-clamp
Type circuit, the complementary conducting of switching tube and main switch in active-clamp branch road, makes two switching tubes all realize by resonance
Zero-voltage soft switch, and reduce the pressure-resistant of switching tube, it is relative to improve efficiency, but the unidirectional excitation of existing transformer,
Magnetic core is easily saturated, and power is difficult to do the complexity for greatly, adding control.
Three kinds of structure types of the comprehensive micro- inverter of conventional photovoltaic, declined inverter for isolation or non-isolated two-stage, its
Rear class typically uses H bridge inversions, is easily led directly to there is two switching tubes above and below bridge arm and burns out circuit, controls difficulty high, reliable
Property it is low, efficiency is low the shortcomings that, along with front and back stages cascade after cause the volume of micro- inverter increase, reliability reduction, efficiency
Further reduce, be progressively isolated type single stage type structure at present and substituted, but there is transformation jointly for isolated form single stage type structure
The problem of device unidirectional excitation.Therefore, low a circuit structure simple, small volume, cost, efficiency high are designed, transformer is two-way encourages
The grid-connected micro- inverter of novel high-efficiency single-stage formula and its control method of magnetic have very big practical value.
The content of the invention：
The defects of it is an object of the invention to overcome prior art to exist, design provide a kind of novel high-efficiency single-stage formula photovoltaic
Grid-connected micro- inverter and its control method, i.e. isolating transformer primary side only realize transformer bidirectional excitation with a switching tube, and
, can be to transformer pair during turning on and off and switching tube can not only realize that no-voltage was opened but also can realize zero voltage turn-off
Side transmission energy；Transformer secondary uses two sets of high frequency full-wave rectifying circuits, by control allow its exported by power frequency then reversely
Parallel connection, the pulse train of Sine Modulated rule change is pressed with reference to the modulation formation of transformer primary side HF switch pipe, after filtered
Becoming can be with grid-connected industrial-frequency alternating current.
To achieve these goals, the agent structure of the grid-connected micro- inverter of stage photovoltaic single of the present invention includes reversely cutting
Only diode, electric capacity, resonant capacitance, first switch pipe, fly-wheel diode, high frequency transformer, the first high frequency full-wave rectifying circuit,
Second high frequency full-wave rectifying circuit, second switch pipe, the 3rd switching tube, filter capacitor, filter inductance, first voltage sampling electricity
Road, the first current sampling circuit, second voltage sample circuit, the second current sampling circuit, line voltage sample circuit, the first electricity
Source, second source, control single chip computer, the first drive circuit, the second drive circuit and the 3rd drive circuit；Input voltage is by anti-
To hold-off diode and by the input after capacitor filtering as circuit below, wherein, input voltage is one piece of solar cell
The output voltage of plate, reverse hold-off diode are used to prevent reverse current from flowing to solar panel, and electric capacity is used to absorb high frequency
The energy of transformer primary side inductance feedback, while play filter action；The primary side inductance of high frequency transformer, resonant capacitance, first
Switching tube, fly-wheel diode electrical connection composition single tube resonance circuit, for by filtered DC inverter into high-frequency alternating current；
High frequency transformer is by primary side inductance, magnetic core, the first secondary inductance, the second secondary inductance, the 3rd secondary inductance, the 4th secondary inductance
Connection composition, wherein, magnetic core is the magnetic core with air gap, primary side inductance and the first secondary inductance, primary side inductance and the second secondary
The coefficient of coup between inductance, primary side inductance and the 3rd secondary inductance, primary side inductance and the 4th secondary inductance is 0.5-0.9,
First secondary inductance is identical with the coiling of the 3rd secondary inductance, and the coiling of the second secondary inductance and the 4th secondary inductance is complete
Identical, high-frequency alternating current is applied to high frequency transformer primary side inductance both ends, and positive and negative amplitude is induced not in high frequency transformer secondary
Symmetrical high-frequency ac voltage；Single tube resonance circuit and high frequency transformer are used to energy being delivered to secondary from primary side；First is high
Frequency full-wave rectifying circuit is by the first secondary inductance, the second secondary inductance, the first high-frequency rectification diode, the pole of the second high-frequency rectification two
Pipe electrical connection composition, for carrying out rectification to the high-frequency alternating current of transformer secondary；Second high frequency full-wave rectifying circuit is by the 3rd
Secondary inductance, the 4th secondary inductance, the 3rd high-frequency rectification diode, the 4th high-frequency rectification diode electrical connection composition, for pair
The high-frequency alternating current of transformer secondary carries out rectification；Second switch pipe and the 3rd switching tube alternate conduction, for realizing that power frequency is inverse
Become, wherein second switch pipe turns in power frequency positive half period, and the 3rd switching tube turns in power frequency negative half-cycle；Filter capacitor
Composition filter circuit is electrically connected with filter inductance, for the high-frequency ac after second switch pipe and the 3rd switching tube power frequency inversion
Electricity is filtered, and is filtered out high-frequency harmonic and is obtained industrial-frequency alternating current；First voltage sample circuit gathers the output of solar panel
Voltage signal simultaneously delivers to control single chip computer, and the output current signal of the first current sampling circuit collection solar panel delivers to control
Single-chip microcomputer processed, control single chip computer receives the output voltage for the solar panel that collection comes and output current signal carries out maximum
Power points tracking (Maximum Power Point Tracking, MPPT) control；Second voltage sample circuit collection first is opened
Close the voltage signal of pipe drain-source interpolar and deliver to control single chip computer, it is arrived in the current drive signal rising edge of first switch pipe
Before, whether the voltage of detection first switch pipe drain-source interpolar is zero to judge whether current first switch pipe realizes that no-voltage is opened
It is logical；Second current sampling circuit gathers the output current signal of micro- inverter and delivers to control single chip computer, line voltage sampling electricity
Road gathers mains voltage signal and delivers to control single chip computer, and control single chip computer receives the output current for micro- inverter that collection comes
Signal and mains voltage signal carry out feedback of voltage and current control, lock phase control and isolated island detection；First power supply is by solar-electricity
The output voltage of pond plate is down to+12V all the way and+5V is exported all the way, wherein the negative pole of+12V outputs and solar panel is negative
Pole electrically connects, and is powered for the first drive circuit driving side；The negative pole of+5V outputs electrically connects with the negative pole of solar panel, is
Control single chip computer, line voltage sample circuit outlet side, line voltage sample circuit direct current biasing, the first drive circuit control letter
Number side, the second drive circuit control signal side, the power supply of the 3rd drive circuit control signal side；Second source is by line voltage rectification
Mutually isolated+12V the outputs of two-way are down to after filtering, the negative pole of the first via+12V outputs electrically connects with second switch pipe source electrode,
Powered for the second drive circuit driving side；The negative pole of second tunnel+12V outputs electrically connects with the 3rd switching tube source electrode, is driven for the 3rd
Dynamic circuit drives side power supply；Control single chip computer receives first voltage sample circuit, the first current sampling circuit, second voltage and adopted
Sample circuit, the second current sampling circuit, line voltage sample circuit collection voltage and current signal, via MPPT control programs,
Sofe Switch determining program, feedback of voltage and current control program, isolated island detection and lock phase program and PWM+PFM control programs are given birth to jointly
Into first switch pipe, second switch pipe, the 3rd switching tube control signal, control signal delivers to the first drive circuit, respectively
Two drive circuits, the 3rd drive circuit；First drive circuit receives the first switch pipe control signal that control single chip computer is sent
First switch pipe is driven by amplification；After second drive circuit receives the second switch pipe control signal that control single chip computer is sent
Amplified driving second switch pipe；3rd drive circuit passes through after receiving the 3rd switch controlled signal that control single chip computer is sent
Amplification the 3rd switching tube of driving.
The present invention realizes that the grid-connected micro- inverter control process of stage photovoltaic single comprises the following steps：
(1) electric on circuit, SCM program initialization, first switch pipe uses pulse width modulation (Pulse Width
Modulation, PWM) mode that is combined with pulse frequency modulated (Pulse Frequency Modulation, PFM) is soft opens
The original switching frequency and initial turn-on time of dynamic, i.e. given first switch pipe, allow second switch pipe and the 3rd switching tube by work
Frequency alternate conduction, micro- inverter output voltage amplitude is set to reach setting voltage magnitude 311V；
(2) when soft start reaches the voltage magnitude 311V of setting, amplitude, the phase and frequency of line voltage are detected, is controlled
The line voltage and micro- inverter that single-chip microcomputer processed receives line voltage sample circuit and the second current sampling circuit collects are defeated
Go out current signal, according to the amplitude, phase and frequency information for obtaining line voltage adjust the modulated signal of first switch pipe and
The Continuity signal of second switch pipe, the 3rd switching tube, make the voltage and grid voltage amplitude, phase and frequency of micro- inverter output
Match, realize grid-connected；When electric network voltage phase changes, it is necessary to which the modulated signal for adjusting first switch pipe is allowed to and electricity
Net voltage-phase is consistent, at the same adjust second switch pipe, the ON time of the 3rd switching tube is realizing the power frequency of output voltage just
It is negative alternately to change；The sine wave modulation of micro- inverter output voltage is carried out according to area equivalent principle, when micro- inverter exports electricity
Pressure power frequency is in a period of time T equal before and after zero crossing0(in the case where micro- inverter circuit parameter is certain, T0Value by
The dutycycle of the switching frequency of first switch pipe and drive signal determines) it is interior when, each switch periods of fixed first switch pipe
The frequency and dutycycle of drive signal, cycle is connected with disconnecting the ratio of cycle to adjust the defeated of micro- inverter by changing
Go out, to reduce voltage distortion rate；When micro- inverter output power-frequency voltage is in other times section, it is combined by PFM, PWM
Mode control the frequency and dutycycle of first switch pipe drive signal, follow grid voltage change；And combine the control of next step
Rule processed is controlled, to realize that micro- inverter output voltage complete period follows the change of line voltage；
(3) when grid voltage amplitude changes, the drive signal of first switch pipe is controlled by PFM control,
The output voltage of micro- inverter is set to follow line voltage.Line voltage sample circuit, the second current sampling circuit gather micro- respectively
The output voltage of inverter, output current signal simultaneously deliver to control single chip computer, by the numeral of feedback of voltage and current control program
After PID compensation, PFM controls are carried out to the drive signal of first switch pipe, if grid voltage amplitude is constant, keep first switch
Set modulated signal is managed, if grid voltage amplitude becomes big, the signal for reducing first switch pipe switching frequency is sent, if power network
Voltage magnitude diminishes, then the signal of increase first switch pipe switching frequency is sent, so as to follow grid voltage amplitude；
(4) isolated island detection is interrupted by first to realize, the first priority interrupted is better than other all interruptions；Power network electricity
Pressure sample circuit, the second current sampling circuit collect line voltage, micro- inverter output current signal and deliver to control monolithic
Machine, judge whether island phenomenon occur by isolated island detection program, if there is isolated island, interrupted into first, block second switch
Pipe, the drive signal of the 3rd switching tube, until isolated island disappears, first interrupts return.
(5) whether the voltage of its drain-source interpolar is zero to judge that first switch pipe is before being opened by detecting first switch pipe
It is no to realize that no-voltage is open-minded, interrupted by second and control its driving pulse width to realize first switch with the method for PWM controls
The no-voltage of pipe is open-minded, and the second priority interrupted is interrupted inferior to first, better than other interruptions；Currently driven in first switch pipe
Before signal rising edge arrives, the voltage signal of second voltage sample circuit collection first switch pipe drain-source interpolar simultaneously delivers to control
Single-chip microcomputer, if Sofe Switch determining program judges that the voltage of first switch pipe drain-source interpolar is not zero, first switch pipe is without real
Existing no-voltage is open-minded, is interrupted into second, reduces the pulse width a reference value of first switch pipe control signal, keeps second switch
Pipe, the drive signal of the 3rd switching tube are constant, and second interrupts return, and wait detects next time；
(6) when the maximum power point of solar panel shifts, interrupted by the 3rd and control first switch management and control
The dutycycle of signal processed, it is equal with the equivalent internal resistance of solar panel to adjust the equiva lent impedance of micro- inverter and load, with
MPPT is realized, the 3rd priority interrupted is interrupted inferior to first and second interrupts；First voltage sample circuit, the first current sample
Circuit collects the output voltage of solar panel, output current signal and delivers to control single chip computer, enters once every the n seconds
3rd interrupts, n value by program setting, MPPT control programs it is upper once carry out MPPT controls when the characteristic information that records
On the basis of continue MPPT controls, until micro- inverter is operated in maximum power point, the 3rd interrupts and returns；
(7) judge whether micro- inverter needs to be stopped, if micro- inverter needs to be stopped, block output first
Switching tube, second switch pipe, the drive signal of the 3rd switching tube；If micro- inverter need not be stopped, detection is electric again
Net voltage, repeats the above steps, and realizes the control of micro- inverter.
It is of the invention compared with the grid-connected micro- inverter of existing stage photovoltaic single, transformer primary side only just can one with a switching tube
Level realizes photovoltaic inversion, and switching tube can realize that no-voltage is opened and can realize zero voltage turn-off, and become isolation
Depressor realizes bidirectional excitation, and volume of transformer is reduced under Same Efficieney；The controllable inverse switch plumber frequency of transformer secondary
Alternate conduction, in the absence of straight-through problem, two sets of high frequency full-wave rectifying circuits cause transformer secondary winding export asymmetry electricity
Pressure is utilized effectively, so that the whole efficiency and reliability of micro- inverter further improve；In parallel humorous of transformer primary side
Shake electric capacity and transformer primary side inductance carries out resonance and causes there is higher voltage gain between micro- inverter input/output, and
It can be adjusted by changing the switching frequency of primary side switch pipe, reduced so as to further reduce transformer turn ratio
The volume of transformer；Its circuit structure is simple, and small volume, cost is low, efficiency high, and reliability is high, except can be dedicated for photovoltaic simultaneously
Net outside micro- inverter, available for other small-sized combining inverters, can also be applicable after isolated island detection and lock phase program is removed
Into vehicle-mounted inverter, ups power, frequency converter, isolation boosting DC-AC converters.
Brief description of the drawings：
Fig. 1 is the agent structure circuit theory schematic diagram of the grid-connected micro- inverter of stage photovoltaic single of the present invention.
Fig. 2 is the control process chart of the grid-connected micro- inverter of stage photovoltaic single of the present invention.
Fig. 3 be the grid-connected micro- inverter of stage photovoltaic single of the present invention voltage modulated schematic diagram, wherein UoFor micro- inversion
The output voltage of device.
Fig. 4 be the grid-connected micro- inverter of stage photovoltaic single of the present invention working waveform figure, wherein Ugs1For first switch pipe
Q1Driving voltage, Uds1For first switch pipe Q1Voltage between hourglass source electrode, UPFor resonant capacitance CrThe voltage at both ends, IPFor original
Side inductance LPElectric current.
Embodiment：
Technical scheme is described in more detail with specific embodiment below in conjunction with the accompanying drawings.
Embodiment：
The agent structure of the grid-connected micro- inverter of stage photovoltaic single described in the present embodiment includes reverse hold-off diode D, electric capacity
Ci, resonant capacitance Cr, first switch pipe Q1, sustained diodeQ1, high frequency transformer 1, the first high frequency full-wave rectifying circuit 2, second
High frequency full-wave rectifying circuit 3, second switch pipe Q2, the 3rd switching tube Q3, filter capacitor Cf, filter inductance Lf, first voltage sampling
Circuit 4, the first current sampling circuit 5, second voltage sample circuit 6, the second current sampling circuit 7, line voltage sample circuit
8th, the first power supply 9, second source 16, control single chip computer 10, the first drive circuit 19, the second drive circuit 20 and the 3rd driving electricity
Road 21；Input voltage UiBy reverse hold-off diode D and by electric capacity CiInput after filtering as circuit below, wherein, it is defeated
Enter voltage UiFor the output voltage of one piece of solar panel, reverse hold-off diode D is used to prevent reverse current from flowing to the sun
Energy cell panel, electric capacity CiFor absorbing the primary inductor L of high frequency transformer 1PThe energy of feedback, while play filter action；High frequency becomes
The primary inductor L of depressor 1P, resonant capacitance Cr, first switch pipe Q1, sustained diodeQ1Electrical connection composition single tube resonance circuit,
For by filtered DC inverter into high-frequency alternating current；High frequency transformer 1 is by primary inductor LP, magnetic core T, the first secondary electricity
Feel LS1, the second secondary inductance LS2, the 3rd secondary inductance LS3, the 4th secondary inductance LS4Connection composition, wherein, magnetic core T is with gas
The magnetic core of gap, primary inductor LPWith the first secondary inductance LS1, primary inductor LPWith the second secondary inductance LS2, primary inductor LPWith
Three secondary inductance LS3, primary inductor LPWith the 4th secondary inductance LS4Between the coefficient of coup be 0.5-0.9, the first secondary inductance
LS1With the 3rd secondary inductance LS3Coiling it is identical, the second secondary inductance LS2With the 4th secondary inductance LS4The complete phase of coiling
Together, high-frequency alternating current is applied to the primary inductor L of high frequency transformer 1PBoth ends, positive and negative amplitude is induced in the secondary of high frequency transformer 1
Asymmetric high-frequency ac voltage；Single tube resonance circuit and high frequency transformer 1 are used to energy being delivered to secondary from primary side；First
High frequency full-wave rectifying circuit 2 is by the first secondary inductance LS1, the second secondary inductance LS2, the first high-frequency rectification diode D1, it is second high
Frequency commutation diode D2Electrical connection composition, for carrying out rectification to the high-frequency alternating current of transformer secondary；Second high frequency all-wave is whole
Current circuit 3 is by the 3rd secondary inductance LS3, the 4th secondary inductance LS4, the 3rd high-frequency rectification diode D3, the pole of the 4th high-frequency rectification two
Pipe D4Electrical connection composition, for carrying out rectification to the high-frequency alternating current of transformer secondary；Second switch pipe Q2With the 3rd switching tube Q3
Alternate conduction, for realizing power frequency inversion, second switch pipe Q2Turned in power frequency positive half period, the 3rd switching tube Q3In power frequency
Turned in negative half-cycle；Filter capacitor CfWith filter inductance LfElectrical connection composition filter circuit, for second switch pipe Q2With
Three switching tube Q3High-frequency alternating current after power frequency inversion is filtered, and is filtered out high-frequency harmonic and is obtained industrial-frequency alternating current；First voltage
Sample circuit 4 gathers the output voltage signal of solar panel and delivers to control single chip computer 10, and the first current sampling circuit 5 is adopted
The output current signal of collection solar panel delivers to control single chip computer 10, and control single chip computer 10 receives the solar energy that collection comes
The output voltage and output current signal of cell panel carry out MPPT controls；Second voltage sample circuit 6 gathers the leakage of first switch pipe
Voltage signal between source electrode simultaneously delivers to control single chip computer 10, in first switch pipe Q1Before current drive signal rising edge arrives,
Detect first switch pipe Q1Whether the voltage of drain-source interpolar is zero to judge current first switch pipe Q1Whether realize that no-voltage is opened
It is logical；Second current sampling circuit 7 gathers the output current signal of micro- inverter and delivers to control single chip computer 10, line voltage sampling
Circuit 8 gathers mains voltage signal and delivers to control single chip computer 10, and control single chip computer 10 receives micro- inverter that collection comes
Output current signal and mains voltage signal carry out feedback of voltage and current control, lock phase control and isolated island detection；First power supply 9 will
The output voltage of solar panel is down to+12V all the way and+5V is exported all the way, wherein the negative pole GND1 and the sun of+12V outputs
The negative pole electrical connection of energy cell panel, powers for the driving side of the first drive circuit 19；The negative pole GND1 and solar cell of+5V outputs
The negative pole electrical connection of plate, it is inclined for control single chip computer 10, the outlet side of line voltage sample circuit 8, the direct current of line voltage sample circuit 8
Put, the control signal side of the first drive circuit 19, the control signal side of the second drive circuit 20, the control signal side of the 3rd drive circuit 21
Power supply.Second source 16 will be down to the mutually isolated+12V of two-way and be exported after line voltage rectifying and wave-filtering, the first via+12V outputs
17 negative pole GND2 and second switch pipe Q2Source electrode electrically connects, and is powered for the driving side of the second drive circuit 20；Second tunnel+12V is defeated
Go out 18 negative pole GND3 and the 3rd switching tube Q3Source electrode electrically connects, and is powered for the driving side of the 3rd drive circuit 21.Control single chip computer
10 receive first voltage sample circuit 4, the first current sampling circuit 5, second voltage sample circuit 6, the second current sample electricity
Road 7, line voltage sample circuit 8 gather voltage and current signal, via MPPT control programs 11, Sofe Switch determining program 12,
Generation first is opened jointly for feedback of voltage and current control program 13, isolated island detection and lock phase program 14 and PWM+PFM control programs 15
Close pipe Q1, second switch pipe Q2, the 3rd switching tube Q3Control signal, control signal delivers to the first drive circuit 19, second respectively
Drive circuit 20, the 3rd drive circuit 21；First drive circuit 19 receives the first switch pipe Q that control single chip computer 10 is sent1
Through amplification driving first switch pipe Q after control signal1；Second drive circuit 20 receives second that control single chip computer 10 is sent and opened
Close pipe Q2Through amplification driving second switch pipe Q after control signal2；3rd drive circuit 21 receives what control single chip computer 10 was sent
3rd switching tube Q3After control signal the 3rd switching tube Q is driven through amplification3。
The present embodiment realizes that the process of the grid-connected micro- inverter control of stage photovoltaic single comprises the following steps：
(1) it is electric on circuit, SCM program initialization, first switch pipe Q1Open using PWM is soft by the way of PFM is combined
Dynamic, i.e. given first switch pipe Q1Original switching frequency and initial turn-on time, allow second switch pipe Q2With the 3rd switching tube Q3
By power frequency, micro- inverter output voltage amplitude is set to reach setting voltage magnitude 311V；
(2) when soft start reaches the voltage magnitude 311V of setting, detection grid voltage amplitude, phase and frequency, control
Single-chip microcomputer 10 receives line voltage and the micro- inverter that the current sampling circuit 7 of line voltage sample circuit 8 and second collects
Output current signal, first switch pipe Q is adjusted according to the amplitude, phase and frequency information for obtaining line voltage1Modulation letter
Number and second switch pipe Q2, the 3rd switching tube Q3Continuity signal, make micro- inverter output voltage and grid voltage amplitude, phase
Match with frequency, realize grid-connected；When electric network voltage phase changes, it is necessary to adjust first switch pipe Q1Modulated signal
It is allowed to consistent with electric network voltage phase, while adjusts second switch pipe Q2, the 3rd switching tube Q3ON time come realize output electricity
The power frequency of pressure is positive and negative alternately to be changed；The sine wave modulation of micro- inverter output voltage is carried out according to area equivalent principle, when micro- inverse
Become device output power-frequency voltage and be in a period of time T equal before and after zero crossing0(in the certain situation of micro- inverter circuit parameter
Under, T0Value by first switch pipe Q1Switching frequency and the dutycycle of drive signal determine) it is interior when, fixed first switch pipe
Q1The frequency and dutycycle of each switch periods drive signal, by change connect cycle with disconnect cycle ratio come
The output of micro- inverter is adjusted, to reduce voltage distortion rate；When micro- inverter output power-frequency voltage is in other times section, lead to
Cross the mode that PFM, PWM are combined and control first switch pipe Q1The frequency and dutycycle of drive signal, follow grid voltage change；
And the control law for combining next step is controlled, to realize that micro- inverter output voltage complete period follows the change of line voltage
Change；
(3) when grid voltage amplitude changes, first switch pipe Q is controlled by PFM control1Driving letter
Number, the output voltage of micro- inverter is followed line voltage；Line voltage sample circuit 8, the second current sampling circuit 7 are adopted respectively
Collect the output voltage of micro- inverter, output current signal and deliver to control single chip computer 10, by feedback of voltage and current control program
After 13 digital PID compensation, to first switch pipe Q1Drive signal carry out PFM controls, if grid voltage amplitude is constant, protect
Hold first switch pipe Q1Set modulated signal, if grid voltage amplitude becomes big, send and reduce first switch pipe Q1Switching frequency
Signal, if grid voltage amplitude diminishes, send increase first switch pipe Q1The signal of switching frequency, so as to follow power network electric
Pressure amplitude value；
(4) isolated island detection interrupts I to realize by first, and the first priority for interrupting I is better than other all interruptions, power network
Voltage sampling circuit 8, the second current sampling circuit 7 collect line voltage, micro- inverter output current signal and deliver to control
Single-chip microcomputer 10, judge whether island phenomenon occur by isolated island detection program, if there is isolated island, interrupt I into first, block the
Two switching tube Q2, the 3rd switching tube Q3Drive signal, until isolated island disappear, first interrupt I return；
(5) by detecting first switch pipe Q1Whether the voltage of its drain-source interpolar is zero to judge first switch pipe before opening
Q1Whether realize that no-voltage is open-minded, interrupt II by second controls its driving pulse width to realize the with the method for PWM controls
One switching tube Q1No-voltage it is open-minded, second interrupt II priority inferior to first interrupt I, better than other interruption；Opened first
Close pipe Q1Before current drive signal rising edge arrives, second voltage sample circuit 6 gathers first switch pipe Q1The electricity of drain-source interpolar
Press and deliver to control single chip computer 10, if Sofe Switch determining program judges first switch pipe Q1The voltage of drain-source interpolar is not zero, then
First switch pipe Q1It is open-minded to be not carried out no-voltage, interrupts II into second, reduces first switch pipe Q1The pulse of control signal is wide
A reference value is spent, keeps second switch pipe Q2, the 3rd switching tube Q3Drive signal it is constant, second interrupt II return, wait next time
Detection；
(6) when the maximum power point of solar panel shifts, III control first switch pipe is interrupted by the 3rd
Q1The dutycycle of control signal, to adjust the equiva lent impedance of micro- inverter and load and the equivalent internal resistance phase of solar panel
Deng to realize MPPT, the 3rd priority for interrupting III interrupts I and second inferior to first and interrupts II；First voltage sample circuit 4,
First current sampling circuit 5 collects the output voltage of solar panel, output current signal and delivers to control single chip computer 10,
The value for entering one time the 3rd III, n of interruption every the n seconds once carries out MPPT controls by program setting, MPPT control programs 11 upper
Continue MPPT controls on the basis of the characteristic information recorded when processed, until micro- inverter is operated in maximum power point, the 3rd
III is interrupted to return；
(7) judge whether micro- inverter needs to be stopped, if micro- inverter needs to be stopped, block output first
Switching tube Q1, second switch pipe Q2, the 3rd switching tube Q3Drive signal；If micro- inverter need not be stopped, examine again
Line voltage is surveyed, repeats the above steps, realizes the control of micro- inverter.
The course of work of the grid-connected micro- inverter of stage photovoltaic single described in the present embodiment was included with the next stage：
Per in power frequency half period, the control method combined with PFM, PWM modulates output voltage waveforms, the positive and negative half-wave of power frequency
Symmetrically and stagger 180 °, it can be below the course of work of each switch periods with grid-connected power frequency voltage waveform to be obtained after filtering：
t0-t1Period：In t0Moment, first switch pipe Q1Driving voltage Ugs1It is changed into high level, now primary inductor LP's
Electric current is negative, first switch pipe Q1It is not turned on, primary inductor LPPass through sustained diodeQ1With electric capacity CiAfterflow, first switch pipe
Q1The voltage of drain-source interpolar is 0, to t1Moment, primary inductor LPElectric current be changed into 0, first switch pipe Q1Conducting, first switch pipe
Q1Realize that no-voltage is open-minded, this period the first secondary inductance LS1With the first high-frequency rectification diode D1Work either the 3rd secondary
Inductance LS3With the 3rd high-frequency rectification diode D3Work；
t1-t2Period：Input voltage UiFor primary inductor LPCharging, primary inductor LPElectric current gradually increase, to t2Moment,
First switch pipe Q1Driving voltage Ugs1It is changed into low level, first switch pipe Q1Shut-off, this period the first secondary inductance LS1With
One high-frequency rectification diode D1Work either the 3rd secondary inductance LS3With the 3rd high-frequency rectification diode D3Work；
t2-t3Period：Resonant capacitance CrFor primary inductor LPCharging, primary inductor LPElectric current continue to increase, to t3Moment,
Resonant capacitance CrVoltage be reduced to 0, primary inductor LPElectric current increase to maximum, this period the first secondary inductance LS1It is high with first
Frequency commutation diode D1Work either the 3rd secondary inductance LS3With the 3rd high-frequency rectification diode D3Work, the first secondary inductance
LS1Or the 3rd secondary inductance LS3Both end voltage amplitude reduces；
t3-t4Period：Primary inductor LPIt is reversed resonant capacitance CrCharging, resonant capacitance CrVoltage reversal increase, to t4
Moment, primary inductor LPElectric current drop to 0, resonant capacitance CrVoltage reversal increase to maximum, this secondary inductance of period second
LS2With the second high-frequency rectification diode D2Work either the 4th secondary inductance LS4With the 4th high-frequency rectification diode D4Work, the
Two secondary inductance LS2Or the 4th secondary inductance LS4Both end voltage amplitude raises；
t4-t5Period：Resonant capacitance CrFor primary inductor LPReverse charging, to t5Moment, resonant capacitance CrVoltage be changed into
0, primary inductor LPElectric current reversely increase to maximum, this period the second secondary inductance LS2With the second high-frequency rectification diode D2Work
Make either the 4th secondary inductance LS4With the 4th high-frequency rectification diode D4Work, the second secondary inductance LS2Or the 4th secondary inductance
LS4Both end voltage amplitude reduces；
t5-t6Period：Primary inductor LPFor resonant capacitance CrReverse charging, resonant capacitance CrVoltage gradually increase, to t6
Moment, resonant capacitance CrVoltage increase to and electric capacity CiVoltage it is equal, first switch pipe Q1The voltage of drain-source interpolar is 0, this
Period the first secondary inductance LS1With the first high-frequency rectification diode D1Work either the 3rd secondary inductance LS3It is whole with the 3rd high frequency
Flow diode D3Work, the first secondary inductance LS1Or the 3rd secondary inductance LS3Both end voltage amplitude raises；
t6-t7Period：Primary inductor LPPass through sustained diodeQ1With electric capacity CiAfterflow, first switch pipe Q1Drain-source interpolar
Voltage be 0, to t7Moment, first switch pipe Q1Driving voltage Ugs1It is changed into high level, now primary inductor LPElectric current be
It is negative, first switch pipe Q1It is not turned on, this period the first secondary inductance LS1With the first high-frequency rectification diode D1Work either the
Three secondary inductance LS3With the 3rd high-frequency rectification diode D3Work.
Claims (2)
1. a kind of grid-connected micro- inverter of stage photovoltaic single, it is characterised in that agent structure includes reverse hold-off diode, electric capacity, humorous
Shake electric capacity, first switch pipe, fly-wheel diode, high frequency transformer, the first high frequency full-wave rectifying circuit, the second high frequency full-wave rectification
Circuit, second switch pipe, the 3rd switching tube, filter capacitor, filter inductance, first voltage sample circuit, the first current sample electricity
Road, second voltage sample circuit, the second current sampling circuit, line voltage sample circuit, the first power supply, second source, control
Single-chip microcomputer, the first drive circuit, the second drive circuit and the 3rd drive circuit；Input voltage by reverse hold-off diode and by
Input after capacitor filtering as circuit below, wherein, input voltage is the output voltage of one piece of solar panel, reversely
Hold-off diode is used to prevent reverse current from flowing to solar panel, and electric capacity is used to absorb high frequency transformer primary side inductance feedback
Energy, while play filter action；Primary side inductance, resonant capacitance, first switch pipe, the fly-wheel diode electricity of high frequency transformer
Connection composition single tube resonance circuit, for by filtered DC inverter into high-frequency alternating current；High frequency transformer is by primary side electricity
Sense, magnetic core, the first secondary inductance, the second secondary inductance, the 3rd secondary inductance, the 4th secondary inductance connection composition, wherein, magnetic core
For the magnetic core with air gap, primary side inductance and the first secondary inductance, primary side inductance and the second secondary inductance, primary side inductance and the 3rd
The coefficient of coup between secondary inductance, primary side inductance and the 4th secondary inductance is 0.5-0.9, the first secondary inductance and the 3rd pair
The coiling of side inductance is identical, and the second secondary inductance is identical with the coiling of the 4th secondary inductance, and high-frequency alternating current applies
At high frequency transformer primary side inductance both ends, the asymmetric high-frequency ac voltage of positive and negative amplitude is induced in high frequency transformer secondary；
Single tube resonance circuit and high frequency transformer are used to energy being delivered to secondary from primary side；First high frequency full-wave rectifying circuit is by first
Secondary inductance, the second secondary inductance, the first high-frequency rectification diode, the second high-frequency rectification diode electrical connection composition, for pair
The high-frequency alternating current of transformer secondary carries out rectification；Second high frequency full-wave rectifying circuit is by the 3rd secondary inductance, the 4th secondary electricity
Sense, the 3rd high-frequency rectification diode, the 4th high-frequency rectification diode electrical connection composition, for the high-frequency ac to transformer secondary
Electricity carries out rectification；Second switch pipe and the 3rd switching tube alternate conduction, for realizing power frequency inversion, wherein second switch Guan Gong
Turned in frequency positive half period, the 3rd switching tube turns in power frequency negative half-cycle；Filter capacitor and filter inductance electrical connection composition
Filter circuit, for being filtered to the high-frequency alternating current after second switch pipe and the 3rd switching tube power frequency inversion, filter out high frequency
Harmonic wave obtains industrial-frequency alternating current；The output voltage signal of first voltage sample circuit collection solar panel simultaneously delivers to control list
Piece machine, the output current signal of the first current sampling circuit collection solar panel deliver to control single chip computer, control single chip computer
The output voltage and output current signal for receiving the solar panel that collection comes carry out MPPT controls；Second voltage sampling electricity
The voltage signal of road collection first switch pipe drain-source interpolar simultaneously delivers to control single chip computer, on the current drive signal of first switch pipe
Rise along before arriving, whether the voltage for detecting first switch pipe drain-source interpolar is zero to judge whether current first switch pipe is realized
No-voltage is open-minded；Second current sampling circuit gathers the output current signal of micro- inverter and delivers to control single chip computer, power network electricity
Pressure sample circuit collection mains voltage signal simultaneously delivers to control single chip computer, and control single chip computer receives micro- inverter that collection comes
Output current signal and mains voltage signal carry out feedback of voltage and current control, lock phase control and isolated island detection；First power supply will
The output voltage of solar panel is down to+12V all the way and+5V is exported all the way, wherein the negative pole and solar-electricity of+12V outputs
The negative pole electrical connection of pond plate, powers for the first drive circuit driving side；The negative pole of+5V outputs and the negative electricity of solar panel
Connection, it is control single chip computer, line voltage sample circuit outlet side, line voltage sample circuit direct current biasing, the first driving electricity
Road control signal side, the second drive circuit control signal side, the power supply of the 3rd drive circuit control signal side；Second source is by power network
Mutually isolated+12V the outputs of two-way, the negative pole and second switch pipe source electrode of the first via+12V outputs are down to after voltage commutation filtering
Electrical connection, powered for the second drive circuit driving side；The negative pole of second tunnel+12V outputs electrically connects with the 3rd switching tube source electrode, is
3rd drive circuit driving side is powered；Control single chip computer receives first voltage sample circuit, the first current sampling circuit, second
Voltage sampling circuit, the second current sampling circuit, the voltage and current signal of line voltage sample circuit collection, are controlled via MPPT
Program, Sofe Switch determining program, feedback of voltage and current control program, isolated island detection and lock phase program and PWM+PFM control programs
Common generation first switch pipe, second switch pipe, the control signal of the 3rd switching tube, control signal deliver to the first driving electricity respectively
Road, the second drive circuit, the 3rd drive circuit；First drive circuit receives the first switch management and control system that control single chip computer is sent
After signal first switch pipe is driven through amplification；Second drive circuit receives the second switch management and control system letter that control single chip computer is sent
After number second switch pipe is driven through amplification；3rd drive circuit receives the 3rd switch controlled signal that control single chip computer is sent
The 3rd switching tube is driven by amplification.
A kind of 2. control method of the grid-connected micro- inverter of stage photovoltaic single as claimed in claim 1, it is characterised in that specific control
Process comprises the following steps：
(1) it is electric on circuit, SCM program initialization, first switch pipe soft start, i.e. by the way of PFM is combined using PWM
The original switching frequency and initial turn-on time of given first switch pipe, allow second switch pipe and the 3rd switching tube to replace by power frequency
Conducting, micro- inverter output voltage amplitude is set to reach setting voltage magnitude 311V；
(2) when soft start reaches the voltage magnitude 311V of setting, amplitude, the phase and frequency of line voltage are detected, control is single
The line voltage and micro- inverter output electricity that piece machine receives line voltage sample circuit and the second current sampling circuit collects
Signal is flowed, the modulated signal of first switch pipe and second are adjusted according to the amplitude, phase and frequency information for obtaining line voltage
The Continuity signal of switching tube, the 3rd switching tube, make the voltage and grid voltage amplitude, phase and frequency phase of micro- inverter output
Match somebody with somebody, realize grid-connected；When electric network voltage phase changes, it is necessary to which the modulated signal for adjusting first switch pipe is allowed to and power network electricity
Press phase consistent, at the same adjust second switch pipe, the ON time of the 3rd switching tube realizes the positive and negative friendship of the power frequency of output voltage
For change；The sine wave modulation of micro- inverter output voltage is carried out according to area equivalent principle, when micro- inverter output voltage work
When in the frequency time equal before and after zero crossing, the frequency of each switch periods drive signal of fixed first switch pipe is with accounting for
Empty ratio, cycle is connected with disconnecting the ratio of cycle to adjust the output of micro- inverter, to reduce voltage distortion by changing
Rate；When micro- inverter output power-frequency voltage is in other times section, first switch is controlled by way of PFM, PWM are combined
The frequency and dutycycle of pipe drive signal, follow grid voltage change；And the control law for combining next step is controlled, with reality
Existing micro- inverter output voltage complete period follows the change of line voltage；
(3) when grid voltage amplitude changes, the drive signal of first switch pipe is controlled by PFM control, is made micro-
The output voltage of inverter follows line voltage.Line voltage sample circuit, the second current sampling circuit gather micro- inversion respectively
The output voltage of device, output current signal simultaneously deliver to control single chip computer, and the digital PID by feedback of voltage and current control program is mended
After repaying, PFM controls are carried out to the drive signal of first switch pipe, if grid voltage amplitude is constant, had kept first switch pipe both
Fixed modulated signal, if grid voltage amplitude becomes big, the signal for reducing first switch pipe switching frequency is sent, if line voltage
Amplitude diminishes, then the signal of increase first switch pipe switching frequency is sent, so as to follow grid voltage amplitude；
(4) isolated island detection is interrupted by first to realize, the first priority interrupted is better than other all interruptions；Line voltage is adopted
Sample circuit, the second current sampling circuit collect line voltage, micro- inverter output current signal and deliver to control single chip computer, by
Isolated island detection program judges whether island phenomenon occur, if there is isolated island, is interrupted into first, block second switch pipe, the
The drive signal of three switching tubes, until isolated island disappears, first interrupts return.
(5) whether the voltage that its preceding drain-source interpolar is opened by detecting first switch pipe is zero to judge whether first switch pipe is real
Existing no-voltage is open-minded, is interrupted by second and controls its driving pulse width to realize first switch pipe with the method for PWM controls
No-voltage is open-minded, and the second priority interrupted is interrupted inferior to first, better than other interruptions；In the current drive signal of first switch pipe
Before rising edge arrives, the voltage signal of second voltage sample circuit collection first switch pipe drain-source interpolar simultaneously delivers to control monolithic
Machine, if Sofe Switch determining program judges that the voltage of first switch pipe drain-source interpolar is not zero, first switch pipe is not carried out zero
Voltage is open-minded, is interrupted into second, the pulse width a reference value of reduction first switch pipe control signal, holding second switch pipe,
The drive signal of 3rd switching tube is constant, and second interrupts return, and wait detects next time；
(6) when the maximum power point of solar panel shifts, interrupted by the 3rd and control first switch management and control system to believe
Number dutycycle, it is equal with the equivalent internal resistance of solar panel to adjust the equiva lent impedance of micro- inverter and load, with realize
MPPT, the 3rd priority interrupted is interrupted inferior to first and second interrupts；First voltage sample circuit, the first current sampling circuit
Collect the output voltage of solar panel, output current signal and deliver to control single chip computer, enter one time the 3rd every the n seconds
Interrupt, n value by program setting, MPPT control programs it is upper once carry out MPPT controls when the basis of characteristic information that records
On continue MPPT controls, until micro- inverter is operated in maximum power point, the 3rd interrupts and returns；
(7) judge whether micro- inverter needs to be stopped, if micro- inverter needs to be stopped, block output first switch
Pipe, second switch pipe, the drive signal of the 3rd switching tube；If micro- inverter need not be stopped, power network electricity is detected again
Pressure, repeats the above steps, realizes the control of micro- inverter.
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| CN112019062A (en) * | 2020-09-11 | 2020-12-01 | 南京力骏新能源储能研究院有限公司 | Sine wave high-frequency chain three-level lithium battery inverter capable of realizing energy feedback |
| CN113726194A (en) * | 2021-07-21 | 2021-11-30 | 广东电网有限责任公司广州供电局 | Power supply conversion circuit and low-voltage direct-current power supply |
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Application publication date: 20171226 |
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