CN105048490B - The photovoltaic micro-inverter and its numerical control device of low current stress - Google Patents
The photovoltaic micro-inverter and its numerical control device of low current stress Download PDFInfo
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Abstract
The present invention discloses a kind of photovoltaic micro-inverter and its numerical control device of low current stress, and the main circuit of photovoltaic micro-inverter includes buck-boost converter, high frequency full-bridge inverter, continued flow switch, energy snubber inductance, transformer, rectifier, pseudo- DC link filter electric capacity, power frequency inverter, grid-connected filter inductance.Numerical control device is realized by DSP digitial controllers.The input of buck-boost converter, output voltage are in series the input power as high frequency bridge-type inverter, and in power frequency period, the output voltage of control buck-boost converter changes according to certain rule, it is ensured that the current stress reduction of device under equal-wattage；Continued flow switch can make energy buffer inductance electric current be in on-off state, it is ensured that the Sofe Switch of device, realize that highly efficient power is converted；Buck-boost converter shares two switching tubes with high frequency full-bridge inverter, on the basis of performance is not reduced, reduces the cost of micro- inverter.
Description
Technical field
The present invention relates to a kind of photovoltaic micro-inverter and its numerical control device of low current stress, belong to power electronics change
Parallel operation and its control technology field.
Background technology
Photovoltaic generation is more and more paid attention to as one of important way of renewable energy utilization, photovoltaic cell institute
Generating can handle and be divided into independent operating mode and synchronizing mode, wherein independent operating mode suitable for power network be difficult to reach it is remote
Area, system generally requires outfit battery；The photovoltaic generating system of synchronizing mode can not be equipped with the higher battery of cost,
Therefore it is widely studied.At present, the photovoltaic output electric energy processing under synchronizing mode has two ways, that is, focuses on and modularization
Power supply, wherein it is that photovoltaic cell is gone here and there and combined on a large scale to focus on, obtains rational voltage, using the change of concentration
Carried out after parallel operation progress energy conversion grid-connected；Modularization, which is powered, carries out monolithic photovoltaic battery panel with corresponding small-power converter
It is integrated, AC module is referred to as, small-power converter therein is exactly micro- inverter.Due to the output voltage of monolithic photovoltaic cell
It is relatively low, therefore the research of micro- inverter with high-frequency isolation transformer is wider, it is micro- according to converter intermediate link DC voltage type
Inverter can be divided into the micro- inverter of no DC link, have the micro- inverter of DC link and the micro- inverter of pseudo- DC link.Due to puppet
The Sine Modulated of the micro- inverter of DC link is carried out in prime DC/DC converters, the inverter power frequency work of grid side, greatly
Reduce switching loss, therefore be widely studied at present.
Although the more use circuit of reversed excitation of front stage converter of the micro- inverter of pseudo- DC link, circuit of reversed excitation device electricity
Stream, voltage stress are larger, there are problems that transformer leakage inductance, and as monolithic photovoltaic power is increasing, instead
The efficiency of excitation circuit processing is more and more lower.Although bridge circuit circuit structure is slightly complicated, its device voltage, current stress compared with
It is low, and can easily coordinate resonant element to realize the Sofe Switch of device, therefore bridge circuit is applied in micro- inverter had
Brighter prospect.
The micro- inverter of Full-Bridge Buck type, high frequency transformer prime uses active full-bridge, and transformer rear class uses diode structure
Into rectifying full bridge circuit, energy snubber use single inductance, design buffer inductance current work can be realized in discontinuous mode
The zero current turning-on and zero-current switching of device.But the micro- inverter of pseudo- DC link Full-Bridge Buck type has one and significantly lacked
Point：To ensure to realize that energy flows to output end by input during line voltage peak value, it is necessary to assure the step-up ratio of transformer is larger,
Thus the problem of bringing is that, when line voltage is relatively low, transformer preceding-stage inversion device is run with minimum modulation ratio, and is flowed to negative
The electric current for carrying side is equal, then it is very big that the switching device of transformer prime bears current effective value, causes loss higher.According to this
One problem, can be further added by one-level power conversion before transformer preceding-stage inversion device, realize the micro- inverter of Full-Bridge Buck type
Input voltage is with grid voltage change, but increased conversion stages reduce system effectiveness.
Therefore, a kind of input that can not increase power conversion series and realize the micro- inverter of Full-Bridge Buck type is set up
Voltage is with the circuit topology and control strategy of voltage ripple of power network, efficiency, the profit of raising photovoltaic cell to improving micro- inverter
There is positive meaning with rate, reduction system cost.
Therefore, finding does not increase conversion series, rational circuit structure and control strategy, ensures the micro- inversion of Full-Bridge Buck type
Device input voltage is with voltage ripple of power network, and the stable operation for controlling to realize whole system by digit chip is the master of the present invention
Want task.
The content of the invention
Goal of the invention：Device current during for the pseudo- micro- inverter of DC link Full-Bridge Buck type near line voltage zero passage
The problem of stress is excessive, propose increase buck-boost converter multiplexing bridge circuit in a bridge arm, buck-boost converter it is defeated
Go out and be in series with photovoltaic cell, control the output voltage of buck-boost converter with voltage ripple of power network, it is ensured that the high frequency of design becomes
Depressor boosting is smaller, so as to ensure device when the pseudo- micro- inverter of DC link Full-Bridge Buck type is near line voltage zero passage
Current stress is smaller.The current stress of device can be effectively reduced according to the program, and improve the conversion efficiency and photovoltaic of system
The utilization rate of battery.
Technical scheme：A kind of photovoltaic micro-inverter of low current stress, including buck-boost converter, high frequency full-bridge inverting
Device, continued flow switch, energy snubber inductance, transformer, rectifier, pseudo- DC link filter electric capacity, power frequency inverter, grid-connected filtering
Inductance.Wherein, buck-boost converter exports energy as input power using photovoltaic cell, and includes photovoltaic cell filter capacitor
CPV, lifting voltage inductance LBB, band is anti-and first switch pipe, second switch pipe, buck output filter capacitor C of diodeBB；The
The drain electrode connection of the source electrode and second switch pipe of one switching tube, the drain electrode of first switch pipe and buck output filter capacitor CBB's
Anode is connected, source electrode and the photovoltaic cell filter capacitor C of second switch pipePVNegative terminal and photovoltaic cell negative terminal connection, rise
Buck inductor LBBOne end be connected to the tie point that first switch pipe source electrode and second switch pipe drain, lifting voltage inductance LBB's
Anode, the photovoltaic cell filter capacitor C of the other end and photovoltaic cellPVAnode, buck output filter capacitor CBBNegative terminal connect
It is connected together；
The high frequency full-bridge inverter and the public first switch pipe of buck-boost converter, second switch pipe, and it is anti-comprising band
And the 3rd switching tube, the 4th switching tube of diode.The wherein drain electrode connection of the source electrode of the 3rd switching tube and the 4th switching tube, the
The drain electrode of three switching tubes and the drain electrode of first switch pipe and buck output filter capacitor CBBAnode connection, the 4th switching tube
Source electrode and second switch pipe source electrode, photovoltaic cell filter capacitor CPVNegative terminal, photovoltaic cell negative terminal connection；
The continued flow switch includes the 5th switching tube, the 6th switching tube of the anti-simultaneously diode of band；Wherein the 5th switching tube
Drain electrode is connected with the drain electrode of the 6th switching tube, the source electrode of the 5th switching tube and the source electrode of first switch pipe, the leakage of second switch pipe
Pole, lifting voltage inductance LBBThe other end, energy snubber inductance LROne end link together, the source electrode and the 3rd of the 6th switching tube
The source electrode of switching tube, the drain electrode of the 4th switching tube link together；
The rectifier includes the first diode, the second diode, the 3rd diode, the 4th diode.First diode
Anode be connected with the negative electrode of the second diode, the anode of the 3rd diode is connected with the negative electrode of the 4th diode, the one or two pole
The negative electrode of pipe is connected with the negative electrode of the 3rd diode, and the anode of the second diode is connected with the anode of the 4th diode；
The transformer includes primary side winding and vice-side winding, the wherein Same Name of Ends of primary side winding and energy snubber inductance LR
Other end connection, the different name end of primary side winding and the drain electrode of the 6th switching tube, the source electrode of the 3rd switching tube, the 4th switching tube
Drain electrode links together；The Same Name of Ends of transformer secondary winding is connected with the anode of the first diode, the negative electrode of the second diode,
The different name end of vice-side winding is connected with the anode of the 3rd diode, the negative electrode of the 4th diode；
The power frequency inverter includes the first IGCT, the second IGCT, the 3rd IGCT, the 4th IGCT, wherein the
The negative electrode of one IGCT, the anode of the second IGCT and grid-connected filter inductance LgOne end connection, the negative electrode of the 3rd IGCT, the
The anode of four IGCTs and the zero line of power network are connected；The anode of first IGCT, the anode of the 3rd IGCT, the first diode
Negative electrode, the negative electrode of the 3rd diode and pseudo- DC link filter electric capacity CgAnode link together；The negative electrode of second IGCT,
Negative electrode, the anode of the second diode, the anode of the 4th diode and the pseudo- DC link filter electric capacity C of 4th IGCTgIt is negative
End links together；Grid-connected filter inductance LgThe other end and power network live wire connect.
Buck-boost converter shares the bridge arm that two switching tubes are constituted with high frequency full-bridge inverter, is not reducing systematic function
On the premise of, reduce the cost of system；The output voltage of buck-boost converter is controlled to change with line voltage in certain rule,
And it can effectively be reduced into the current stress of switching device in whole system as the input power of high frequency full-bridge inverter,
Improve the efficiency of whole micro- inverter system.
A kind of numerical control device of the photovoltaic micro-inverter of low current stress, including first voltage sensor, the second electricity
Pressure sensor, tertiary voltage sensor, the first current sensor, the second current sensor, the 3rd current sensor and DSP numbers
Word controller, wherein DSP digitial controllers include phaselocked loop, the first subtracter, buck voltage regulator, the second subtracter,
Buck current regulator, the first signal modulator, MPPT maximum power point tracking module, multiplier, the modulation of high frequency full-bridge inverter
Than precalculation module, the 3rd subtracter, power network current adjuster, adder, secondary signal modulator and polarity recognizer；
The input of first voltage sensor is connected to buck output filter capacitor CBBTwo ends, second voltage sensor
Input be connected to the two ends of photovoltaic cell, tertiary voltage sensor is connected to the two ends of power network, the first current sensor with
Lift voltage inductance LBBIt is in series, the second current sensor is in series with photovoltaic cell, the 3rd current sensor and grid-connected filtered electrical
Feel LgIt is in series；
The input of phaselocked loop connects the output end of above-mentioned tertiary voltage sensor；First output termination first of phaselocked loop subtracts
The positive input terminal of musical instruments used in a Buddhist or Taoist mass, the negative input of the first subtracter terminates the output end of first voltage sensor, the output of the first subtracter
The input of buck voltage regulator is terminated, the output of buck voltage regulator terminates the positive input terminal of the second subtracter,
The negative input of second subtracter terminates the output end of the first current sensor, and the output termination buck electric current of the second subtracter is adjusted
Save the input of device, the input of output the first signal modulator of termination of buck current regulator, the first signal modulator
Output end output first switch pipe, the drive signal of second switch pipe；
First, second input of MPPT maximum power point tracking module connects the output end and second of the second current sensor respectively
The output end of voltage sensor；First, second input of multiplier connects the second output end and peak power of phaselocked loop respectively
The output end of point tracking module；First, second, third input of high frequency bridge-type inverter modulation ratio precalculation module connects respectively
The output end of the output end of multiplier, the output end of second voltage sensor and tertiary voltage sensor；
The positive input terminal of 3rd subtracter connects the output end and the 3rd current sensor of multiplier with negative input end respectively
Output end, the output end of the 3rd subtracter gets access to grid the input of current regulator；First addition end of adder adds with second
Method end gets access to grid the output end of output end and high frequency full-bridge inverter premodulated than computing module of current regulator respectively；Second
First, second input of signal modulator connects the output end of the first signal modulator and the output end of adder, second respectively
The output end of signal modulator export the 3rd switching tube, the 4th switching tube, the 5th switching tube, the 6th switching tube, drive signal；
The output end of the input termination tertiary voltage sensor of polarity recognizer, the output end output first of polarity recognizer
IGCT, the second IGCT, the 3rd IGCT, the drive signal of the 4th IGCT.
Beneficial effect：After such scheme, the present invention by buck-boost converter output voltage and photovoltaic cell it is defeated
Go out voltage to be in series, on the one hand increase input voltage size, on the other hand also achieves the input of the micro- inverter of Full-Bridge Buck type
Voltage is with voltage ripple of power network, it is ensured that switching device realizes high-quality grid-connected function with less current stress, improves micro-
The whole efficiency of inverter.
Brief description of the drawings
Fig. 1 is the photovoltaic micro-inverter and its numerical control device block diagram of the low current stress of the embodiment of the present invention；
Fig. 2 is main signal waveform diagram of the embodiment of the present invention in a power frequency period；
Fig. 3 be the embodiment of the present invention in line voltage positive half period, the main oscillogram in a power frequency period；
Fig. 4 be the embodiment of the present invention in line voltage positive half period, the equivalent circuit diagram of mode 1；
Fig. 5 be the embodiment of the present invention in line voltage positive half period, the equivalent circuit diagram of mode 2；
Fig. 6 be the embodiment of the present invention in line voltage positive half period, the equivalent circuit diagram of mode 3；
Fig. 7 be the embodiment of the present invention in line voltage positive half period, the equivalent circuit diagram of mode 4；
Fig. 8 be the embodiment of the present invention in line voltage positive half period, the equivalent circuit diagram of mode 5；
Fig. 9 be the embodiment of the present invention in line voltage positive half period, the equivalent circuit diagram of mode 6；
Figure 10 be the embodiment of the present invention in line voltage positive half period, the equivalent circuit diagram of mode 7；
Designation in figure：UPV--- photovoltaic cell output voltage；IPV--- photovoltaic cell output current；CPV--- light
Lie prostrate battery filter capacitor；UBB--- buck-boost converter output voltage；CBB--- buck output filter capacitor；iBB--- rise
Buck inductor electric current；S1-S6 --- the switching tubes of first switch Guan Zhi six；iS1-iS4--- flow through first switch Guan Zhi tetra- and open
Close the electric current of pipe；D1-D4 --- the first diode is to the 4th diode；LR--- energy snubber inductance；iR--- energy snubber electricity
Inducing current；T --- high frequency transformer；W1 --- high frequency transformer primary side winding；W2 --- high frequency transformer vice-side winding；
N --- high frequency transformer step-up ratio；iW2--- high frequency transformer secondary winding current；uAB--- high frequency full-bridge inverter is exported
Voltage；uCD--- high frequency transformer secondary voltage；UDC--- pseudo- DC link output voltage；CDC--- pseudo- DC link filter
Electric capacity；irec--- rectifier current output；iga--- power frequency input current of inverter；VT1-VT4 --- the first IGCT is to
Four IGCTs；Lg--- grid-connected current filter inductance；ig--- grid-connected current；ug--- line voltage；UBBf--- first voltage
Sensor output signal；iBBf--- the first current sensor output；UPVf--- second voltage sensor output signal；
IPVf--- the second current sensor output；ugf--- tertiary voltage sensor output signal；igf--- the 3rd electric current is passed
Sensor output signal；UBB* --- buck-boost converter output voltage reference signal；UBBe--- the first subtracter output signal；
iBB* --- buck-boost converter inductive current reference signal；iBBe--- the second subtracter output signal；UBBr--- lifting buckling
Parallel operation modulated signal；ige--- the 3rd subtracter output signal；ig* --- grid-connected current reference signal；Ig--- grid-connected current
Reference amplitude signal；ω t --- grid phase angle signal；dw--- grid-connected current duty cycle trimmer signal；dp--- grid-connected current
The presetting signal of dutycycle；igr--- grid-connected current duty cycle signals；uS1~uS6--- the drive of the switching tubes of first switch Guan Zhi six
Dynamic signal；uVT1~uVT4--- the drive signal of the first IGCT to the 4th IGCT.
Embodiment
With reference to specific embodiment, the present invention is furture elucidated, it should be understood that these embodiments are merely to illustrate the present invention
Rather than limitation the scope of the present invention, after the present invention has been read, various equivalences of the those skilled in the art to the present invention
The modification of form falls within the application appended claims limited range.
As shown in figure 1, the photovoltaic micro-inverter of low current stress, including it is buck-boost converter, high frequency full-bridge inverter, continuous
Stream switch, energy snubber inductance LR, transformer T, rectifier, pseudo- DC link filter electric capacity CDC, power frequency inverter, grid-connected filtering
Inductance.Wherein, buck-boost converter exports energy as input power using photovoltaic cell, and includes photovoltaic cell filter capacitor
CPV, lifting voltage inductance LBB, band is anti-and first switch pipe S1, second switch pipe S2, buck output filter capacitor of diode
CBB；The drain electrode connection of S1 source electrode and S2, S1 drain electrode and buck output filter capacitor CBBAnode connection, S2 source electrode
With photovoltaic cell filter capacitor CPVNegative terminal and photovoltaic cell negative terminal connection, lifting voltage inductance LBBOne end be connected to S1
The tie point that source electrode drains with S2, lifting voltage inductance LBBThe other end and photovoltaic cell anode, photovoltaic cell filter capacitor CPV
Anode, buck output filter capacitor CBBNegative terminal link together；
High frequency full-bridge inverter and buck-boost converter public S1, S2, and include the 3rd switching tube of the anti-simultaneously diode of band
S3, the 4th switching tube S4.Wherein S3 source electrode and S4 drain electrode connection, S3 drain electrode and S1 drain electrode and buck output are filtered
Ripple electric capacity CBBAnode connection, S4 source electrode and S2 source electrode, photovoltaic cell filter capacitor CPVNegative terminal, photovoltaic cell it is negative
End connection；
Continued flow switch includes the 5th switching tube S5, the 6th switching tube S6 of the anti-simultaneously diode of band；Wherein S5 drain electrode and S6
Drain electrode connection, S5 source electrode and S1 source electrode, S2 drain electrode, lifting voltage inductance LBBThe other end, energy snubber inductance LR's
One end links together, and S6 source electrode and S3 source electrode, S4 drain electrode link together；
Rectifier includes the first diode D1, the second diode D2, the 3rd diode D3, the 4th diode D4.D1 sun
Pole and D2 negative electrode connection, D3 anode and D4 negative electrode are connected, and D1 negative electrode and D3 negative electrode are connected, D2 anode and D4's
Anode is connected；
Transformer T includes primary side winding W1 and vice-side winding W2, wherein W1 Same Name of Ends and energy snubber inductance LRIt is another
One end is connected, and W1 different name end and S6 drain electrode, S3 source electrode, S4 drain electrode link together；W2 Same Name of Ends and D1 sun
Pole, D2 negative electrode connection, W2 different name end and D3 anode, D4 negative electrode are connected；
Power frequency inverter includes the first IGCT VT1, the second IGCT VT2, the 3rd IGCT VT3, the 4th IGCT
VT4, wherein VT1 negative electrode, VT2 anode and grid-connected filter inductance LgOne end connection, VT3, VT4 anode and the zero of power network
Line is connected；VT1 anode, VT3 anode, D1 negative electrode, D3 negative electrode and pseudo- DC link filter electric capacity CgAnode connection
Together；VT2 negative electrode, VT4 negative electrode, D2 anode, D4 anode and pseudo- DC link filter electric capacity CgNegative terminal connection
Together；Grid-connected filter inductance LgThe other end and power network live wire connect.
The numerical control device of the photovoltaic micro-inverter of low current stress, including first voltage sensor, second voltage are passed
Sensor, tertiary voltage sensor, the first current sensor, the second current sensor, the 3rd current sensor and DSP numeral controls
Device processed, wherein DSP digitial controllers include phaselocked loop, the first subtracter, buck voltage regulator, the second subtracter, lifting
Piezoelectricity throttle regulator, the first signal modulator, MPPT maximum power point tracking module, multiplier, high frequency full-bridge inverter modulation ratio are pre-
Computing module, the 3rd subtracter, power network current adjuster, adder, secondary signal modulator and polarity recognizer；
The input of first voltage sensor is connected to buck output filter capacitor CBBTwo ends, second voltage sensor
Input be connected to the two ends of photovoltaic cell, tertiary voltage sensor is connected to the two ends of power network, the first current sensor with
Lift voltage inductance LBBIt is in series, the second current sensor is in series with photovoltaic cell, the 3rd current sensor and grid-connected filtered electrical
Feel LgIt is in series；
The input of phaselocked loop connects the output end of above-mentioned tertiary voltage sensor；First output termination first of phaselocked loop subtracts
The positive input terminal of musical instruments used in a Buddhist or Taoist mass, the negative input of the first subtracter terminates the output end of first voltage sensor, the output of the first subtracter
The input of buck voltage regulator is terminated, the output of buck voltage regulator terminates the positive input terminal of the second subtracter,
The negative input of second subtracter terminates the output end of the first current sensor, and the output termination buck electric current of the second subtracter is adjusted
Save the input of device, the input of output the first signal modulator of termination of buck current regulator, the first signal modulator
Output end export S1, S2 drive signal；
First, second input of MPPT maximum power point tracking module connects the output end and second of the second current sensor respectively
The output end of voltage sensor；First, second input of multiplier connects the second output end and peak power of phaselocked loop respectively
The output end of point tracking module；First, second, third input of high frequency bridge-type inverter modulation ratio precalculation module connects respectively
The output end of the output end of multiplier, the output end of second voltage sensor and tertiary voltage sensor；
The positive input terminal of 3rd subtracter connects the output end and the 3rd current sensor of multiplier with negative input end respectively
Output end, the output end of the 3rd subtracter gets access to grid the input of current regulator；First addition end of adder adds with second
Method end gets access to grid the output end of output end and high frequency full-bridge inverter premodulated than computing module of current regulator respectively；Second
First, second input of signal modulator connects the output end of the first signal modulator and the output end of adder, second respectively
Signal modulator output end output S3, S4, S5, S6, drive signal；
The output end of the input termination tertiary voltage sensor of polarity recognizer, the output end output VT1 of polarity recognizer,
VT2, VT3, VT4 drive signal.
First input end, the second input, the letter of the 3rd input of high frequency full-bridge inverter modulation ratio precalculation module
Number it is i respectivelyg*、UPVf、ugf, then high frequency full-bridge inverter modulation ratio precalculation module dpFor：
Wherein, k1、k2、k3For the constant related to circuit.
Fig. 2 gives the present invention waveform modulated schematic diagram in a power frequency period, it can be seen that a power frequency week
In phase, the frequency modulating signal of buck-boost converter is twice of power frequency, it is hereby achieved that the output electricity of buck-boost converter
Periodically fluctuation is presented in pressure；The Sine Modulated of high frequency full-bridge inverter is controlled based on buck bridge arm switching tube S1, S2
Make another bridge arm switching tube S3, S4 to realize, can so obtain the output voltage u of high frequency full-bridge inverterABFor Sine Modulated
High-frequency alternating current；The design of energy snubber inductive current can be ensured into the Zero Current Switch of device in discontinuous conduct mode.Rectification
Device by the rectification of buffer inductance high-frequency ac current and obtains steamed bun ripple electric current through pseudo- DC link filter capacitor filtering, finally by damaging
The minimum power frequency inverter of consumption is realized grid-connected, obtains high-quality grid-connected current.
When Fig. 3 is line voltage positive half cycle, main waveform of micro- inverter in a switch periods, wherein lifting buckling
Two switching tubes S1, S2 complementation conducting of parallel operation, and two switching tubes of another bridge arm S3, S4 of full-bridge inverter are led to interlock
Lead to, and centre has while being not turned on the time, and this period is turned on by continued flow switch pipe S5, S6, and afterflow energy snubber inductance
Electric current.
Being known by Fig. 3 in a switch periods has 7 switch mode, and the correspondence time is t0-t7.Fig. 4 to Figure 10 is line voltage
During positive half cycle, equivalent circuit of micro- inverter in a switch periods is carried, the following detailed description of this 7 circuit mode.
Switch mode 1 [corresponding diagram 4]：
t0Before moment, switching tube S2 conductings, energy snubber inductive current iRNo current in=0, therefore rectifier, buck
Inductive current is more than 0.In t0Moment, switching tube S2 shut-offs, switching tube S1, S4 conducting.t0After moment, due to slope piezoelectricity
Inducing current iBBMore than electric current iR, therefore switching tube S1 and its anti-and diode have electric current to flow through；Buck inductive current iBBWill
It is gradually reduced, and energy snubber inductive current is then linearly increasing；In transformer secondary circuit, commutation diode D1, D4 conducting, work
Frequency inverter VT1, VT4 are turned on, and will convey grid side by the energy of transformer primary side.
Switch mode 2 [corresponding diagram 5]：
t1Moment, electric current iBBMore than electric current iR, the sense of current for flowing through switching tube S1 changed, and source is flowed to by its drain electrode
Pole, other states of circuit are consistent with switch mode 1.
Switch mode 3 [corresponding diagram 6]：
t2Moment, switching tube S4 shut-offs, continued flow switch pipe S5, S6 conducting；Electric current iBBContinue to decline, inductance storage energy turns
Move on to buck filter capacitor；Electric current iRAfterflow, electric current i are carried out by continued flow switch pipe S5, S6RIt is changed into linear from linear rise
Decline.
Switch mode 4 [corresponding diagram 7]：
t3Moment, electric current iRDrop to 0, then continued flow switch pipe S5, S6 are turned off naturally, also no electric current flows through in rectifier；
In this stage, it is micro- in addition to switching tube S1 in buck-boost converter and power frequency inverter IGCT VT1, VT4 have electric current and flowed through
Other all no electric currents of switching device flow through in inverter.
Switch mode 5 [corresponding diagram 8]：
t4At the moment, on-off switching tube S1, S5, S6 open switching tube S2, S3；High frequency full-bridge inverter output voltage uABBecome
For negative value, therefore buck inductive current iBBLinear rise, electric current i are changed into from linear declineRStart reverse linear increase, transformation
Device secondary output voltage uCDAlso it is changed into negative value.
Switch mode 6 [corresponding diagram 9]：
t5Moment, on-off switching tube S3 opens switching tube S5, S6；Due to the effect of continued flow switch, high frequency full-bridge inverter
Output voltage uABIt is changed into 0, thereafter, electric current iBBContinue linearly increasing, and energy snubber inductive current iRIt is continuous through continued flow switch S5, S6
Stream, current value starts to diminish.
Switch mode 7 [corresponding diagram 10]：
t6Moment, energy snubber inductive current iRDrop in 0, circuit except buck switching tube S2 and power frequency inverter
It is outer that IGCT VT1, VT4 have electric current to flow through, and other all no electric currents of switching device flow through in micro- inverter.
t7Moment, next switch periods start.
In summary, on the basis of the present invention carries low current stress photovoltaic micro-inverter for increase switching device, increase
Buck-boost converter, reduces system cost；By the output voltage phase of the output voltage of buck-boost converter and photovoltaic cell
Series connection, on the one hand increase input voltage size, on the other hand also achieves the input voltage of the micro- inverter of Full-Bridge Buck type with electricity
Net voltage pulsation, it is ensured that switching device realizes high-quality grid-connected function with less current stress, improves micro- inverter
Whole efficiency.
Claims (6)
1. a kind of photovoltaic micro-inverter of low current stress, it is characterised in that including buck-boost converter, high frequency full-bridge inverting
Device, continued flow switch, energy snubber inductance, transformer, rectifier, pseudo- DC link filter electric capacity, power frequency inverter, grid-connected filtering
Inductance；Wherein, buck-boost converter is using photovoltaic cell output voltage as input power, and includes photovoltaic cell filter capacitor
CPV, lifting voltage inductance LBB, band is anti-and first switch pipe, second switch pipe, buck output filter capacitor C of diodeBB；The
The drain electrode connection of the source electrode and second switch pipe of one switching tube, the drain electrode of first switch pipe and buck output filter capacitor CBB's
Anode is connected, source electrode and the photovoltaic cell filter capacitor C of second switch pipePVNegative terminal and photovoltaic cell negative terminal connection, rise
Buck inductor LBBFirst end be connected to the tie point that first switch pipe source electrode and second switch pipe drain, lifting voltage inductance LBB
The second end and photovoltaic cell anode, photovoltaic cell filter capacitor CPVAnode, buck output filter capacitor CBBNegative terminal
Link together.
2. the photovoltaic micro-inverter of low current stress as claimed in claim 1, it is characterised in that the high frequency full-bridge inverter
With the public first switch pipe of buck-boost converter, second switch pipe, and comprising band is anti-and the 3rd switching tube of diode, the 4th opens
Guan Guan；The wherein drain electrode connection of the source electrode of the 3rd switching tube and the 4th switching tube, drain electrode and the first switch pipe of the 3rd switching tube
Drain electrode and buck output filter capacitor CBBAnode connection, the source electrode of the 4th switching tube and the source electrode of second switch pipe,
Photovoltaic cell filter capacitor CPVNegative terminal, photovoltaic cell negative terminal connection.
3. the photovoltaic micro-inverter of low current stress as claimed in claim 1, it is characterised in that the continued flow switch includes band
The 5th switching tube, the 6th switching tube of anti-and diode；The source electrode of wherein the 5th switching tube is connected with the source electrode of the 6th switching tube,
The drain electrode of 5th switching tube and the source electrode of first switch pipe, the drain electrode of second switch pipe, lifting voltage inductance LBBFirst end, energy
Buffer inductance LROne end link together, drain electrode and the source electrode of the 3rd switching tube, the leakage of the 4th switching tube of the 6th switching tube
Pole links together；
The rectifier includes the first diode, the second diode, the 3rd diode, the 4th diode；The sun of first diode
Pole is connected with the negative electrode of the second diode, and the anode of the 3rd diode is connected with the negative electrode of the 4th diode, the first diode
Negative electrode is connected with the negative electrode of the 3rd diode, and the anode of the second diode is connected with the anode of the 4th diode；
The transformer includes primary side winding and vice-side winding, the wherein Same Name of Ends of primary side winding and energy snubber inductance LRIt is another
One end is connected, the different name end of primary side winding and drain electrode, the source electrode of the 3rd switching tube, the drain electrode of the 4th switching tube of the 6th switching tube
Link together；The Same Name of Ends of transformer secondary winding is connected with the anode of the first diode, the negative electrode of the second diode, secondary
The different name end of winding is connected with the anode of the 3rd diode, the negative electrode of the 4th diode.
4. the photovoltaic micro-inverter of low current stress as claimed in claim 1, it is characterised in that the power frequency inverter is included
First IGCT, the second IGCT, the 3rd IGCT, the 4th IGCT, wherein the negative electrode of the first IGCT, the second IGCT
Anode and grid-connected filter inductance LgOne end connection, the zero line of the negative electrode of the 3rd IGCT, the anode of the 4th IGCT and power network
Connection；The anode of first IGCT, the anode of the 3rd IGCT, the negative electrode of the first diode, the negative electrode of the 3rd diode and puppet
DC link filter electric capacity CgAnode link together；The negative electrode of second IGCT, the negative electrode of the 4th IGCT, the two or two pole
The anode of pipe, the anode of the 4th diode and pseudo- DC link filter electric capacity CgNegative terminal link together；Grid-connected filter inductance Lg
The other end and power network live wire connect.
5. the photovoltaic micro-inverter of low current stress as claimed in claim 1, it is characterised in that high frequency full-bridge inverter is modulated
First input end, the second input, the signal of the 3rd input than precalculation module are i respectivelyg *、UPVf、ugf, then high frequency is complete
Bridge inverter modulation ratio precalculation module dpFor：
Wherein, k1、k2、k3For the constant related to circuit, ig *Believe for grid-connected current benchmark
Number, UPVfFor second voltage sensor output signal, ugfFor tertiary voltage sensor output signal, dpFor grid-connected current dutycycle
Presetting signal.
6. a kind of numerical control device of the photovoltaic micro-inverter of low current stress as described in claim 1-5 any one,
It is characterized in that：Including first voltage sensor, second voltage sensor, tertiary voltage sensor, the first current sensor,
Two current sensors, the 3rd current sensor and DSP digitial controllers, wherein DSP digitial controllers include phaselocked loop, first
Subtracter, buck voltage regulator, the second subtracter, buck current regulator, the first signal modulator, maximum power point
Tracking module, multiplier, high frequency full-bridge inverter modulation ratio precalculation module, the 3rd subtracter, power network current adjuster, addition
Device, secondary signal modulator and polarity recognizer；
The input of first voltage sensor is connected to buck output filter capacitor CBBTwo ends, second voltage sensor it is defeated
Enter the two ends that end is connected to photovoltaic cell, tertiary voltage sensor is connected to the two ends of power network, the first current sensor and lifting
Voltage inductance LBBIt is in series, the second current sensor is in series with photovoltaic cell, the 3rd current sensor and grid-connected filter inductance Lg
It is in series；
The input of phaselocked loop connects the output end of above-mentioned tertiary voltage sensor；First output the first subtracter of termination of phaselocked loop
Positive input terminal, the negative input of the first subtracter terminates the output end of first voltage sensor, the output termination of the first subtracter
The input of buck voltage regulator, the positive input terminal of output the second subtracter of termination of buck voltage regulator, second
The negative input of subtracter terminates the output end of the first current sensor, the output termination buck current regulator of the second subtracter
Input, buck current regulator output termination the first signal modulator input, the first signal modulator it is defeated
Go out end output first switch pipe, the drive signal of second switch pipe；
First, second input of MPPT maximum power point tracking module connects the output end and second voltage of the second current sensor respectively
The output end of sensor；First, second input of multiplier connect respectively the second output end of phaselocked loop and maximum power point with
The output end of track module；First, second, third input of high frequency bridge-type inverter modulation ratio precalculation module connects multiplication respectively
The output end of the output end of device, the output end of second voltage sensor and tertiary voltage sensor；
The positive input terminal of 3rd subtracter connects the output end of multiplier and the output of the 3rd current sensor respectively with negative input end
End, the output end of the 3rd subtracter gets access to grid the input of current regulator；First addition end of adder and the second addition end
Get access to grid the output end of output end and high frequency full-bridge inverter premodulated than computing module of current regulator respectively；Secondary signal
First, second input of modulator connects the output end of the first signal modulator and the output end of adder, secondary signal respectively
The output end of modulator exports the 3rd switching tube, the 4th switching tube, the 5th switching tube, the drive signal of the 6th switching tube；
The output end of the input termination tertiary voltage sensor of polarity recognizer, the brilliant lock of output end output first of polarity recognizer
Pipe, the second IGCT, the 3rd IGCT, the drive signal of the 4th IGCT.
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| CN107681896A (en) * | 2017-09-28 | 2018-02-09 | 盐城工学院 | Double duty cycle control arrangements of current mode bridge-type photovoltaic converter |
| CN107612030B (en) * | 2017-09-28 | 2023-05-02 | 盐城工学院 | Photovoltaic converter with current quasi-critical continuous and device soft switch |
| CN108400647A (en) * | 2018-05-14 | 2018-08-14 | 北方工业大学 | Solar power supply based on Internet photocatalyst fresh air system |
| CN110707931A (en) * | 2019-09-06 | 2020-01-17 | 广州金升阳科技有限公司 | LLC resonant converter and control method |
| CN110620377B (en) * | 2019-09-16 | 2023-06-09 | 哈尔滨工程大学 | Three-port DC-DC converter for energy efficient transmission and control method thereof |
| CN111355397B (en) * | 2020-04-17 | 2021-05-14 | 南通大学 | Single-phase high-gain photovoltaic grid-connected inverter with continuous input current and control method |
| CN111510010B (en) * | 2020-05-20 | 2021-04-23 | 上海海事大学 | Non-isolated photovoltaic inverter and control method thereof |
| CN112636622B (en) * | 2020-12-16 | 2021-12-24 | 河海大学 | Soft switch control circuit of neutral point clamping type three-level inverter |
| CN114062743B (en) * | 2021-11-11 | 2023-08-15 | 青岛鼎信通讯股份有限公司 | Full-bridge switch characteristic current generating device applied to power industry |
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Inventor after: Ge Yuhua Inventor after: Han Jiarong Inventor after: Zhang Shouguo Inventor after: Wu Yunya Inventor after: Gu Chunlei Inventor after: Xie Shaojun Inventor after: Yang Chen Inventor after: Xu Jinming Inventor before: Han Jiarong Inventor before: Wu Yunya Inventor before: Gu Chunlei Inventor before: Xie Shaojun Inventor before: Yang Chen Inventor before: Xu Jinming |
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Denomination of invention: Low current stress photovoltaic micro inverter and its digital control device Effective date of registration: 20210705 Granted publication date: 20170725 Pledgee: Bank of Suzhou Co.,Ltd. Yancheng branch Pledgor: JIANGSU HASEN ELECTRIC Co.,Ltd. Registration number: Y2021320010236 |