CN106300430A - A kind of miniature photovoltaic grid-connected inverter and grid-connected control method thereof - Google Patents
A kind of miniature photovoltaic grid-connected inverter and grid-connected control method thereof Download PDFInfo
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Classifications
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- H02J3/385—
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
- H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
- H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
- H02M7/5387—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration
- H02M7/53871—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration with automatic control of output voltage or current
- H02M7/53873—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration with automatic control of output voltage or current with digital control
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02S—GENERATION OF ELECTRIC POWER BY CONVERSION OF INFRARED RADIATION, VISIBLE LIGHT OR ULTRAVIOLET LIGHT, e.g. USING PHOTOVOLTAIC [PV] MODULES
- H02S40/00—Components or accessories in combination with PV modules, not provided for in groups H02S10/00 - H02S30/00
- H02S40/30—Electrical components
- H02S40/32—Electrical components comprising DC/AC inverter means associated with the PV module itself, e.g. AC modules
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
- Y02E10/56—Power conversion systems, e.g. maximum power point trackers
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- Inverter Devices (AREA)
Abstract
The invention discloses a kind of miniature photovoltaic grid-connected inverter and grid-connected control method thereof, inverter includes the interleaving inverse excitation circuit of band active clamp, full-bridge circuit, EMI circuit, testing circuit and main control chip, the DC voltage of external solar plate output is input to interleaving inverse excitation circuit, interleaving inverse excitation circuit includes two circuit of reversed excitation and two active clamp circuits, the 180 degree of alternations of two circuit of reversed excitation phase, the outfan of interleaving inverse excitation circuit is connected with the input of full-bridge circuit；Full-bridge circuit includes that gate drive transformer, upper brachium pontis, lower brachium pontis, upper brachium pontis and lower brachium pontis are driven by gate drive transformer, and full-bridge circuit is connected with electrical network by EMI circuit；Main control chip carries out data communication by testing circuit with interleaving inverse excitation circuit and full-bridge circuit.Method includes the grid-connected algorithm of dead beat based on electric current control and MPPT algorithm based on current disturbing etc..It is low that the present invention has grid-connected harmonic wave rate, and maximal power tracing efficiency is high, the advantage that anti-shade ability is strong.
Description
Technical field
The present invention relates to inverter research field, particularly to a kind of miniature photovoltaic grid-connected inverter and cutting-in control side thereof
Method.
Background technology
From the point of view of total quantity consumed, China is an energy big country, but owing to environmental issue is increasingly serious, and traditional energy
Exhaustion, photovoltaic generation has obtained increasing concern by the advantage of its uniqueness.
Photovoltaic generation is broadly divided into centralized, group string data and Miniature inverter.Centralized, group string inverter output
Greatly, but every piece of photovoltaic panel can not be carried out maximal power tracing, anti-shade ability.Traditional inverter control, simply basis
The peak power that photovoltaic panel can reach is tracked, and have ignored inverter workable peak power size itself.If light
Volt plate works under the peak power that can reach and likely can exceed the peak power of inverter work itself, ultimately results in inversion
Device damages.
Summary of the invention
It is an object of the present invention to the shortcoming overcoming prior art with not enough, it is provided that a kind of miniature photovoltaic grid-connected inversion
Device, it is low that this inverter has grid-connected harmonic wave rate, and maximal power tracing efficiency is high, the advantage that anti-shade ability is strong.
Further object is that the shortcoming overcoming prior art is with not enough, it is provided that a kind of based on above-mentioned Miniature optical
The grid-connected control method of volt combining inverter, the method can realize power decoupled, two-way flyback load balance, real-time parameter prison
Survey, maximal power tracing, the grid-connected and function of power deratng.
The purpose of the present invention is realized by following technical scheme: a kind of miniature photovoltaic grid-connected inverter, active including carrying
The interleaving inverse excitation circuit of clamper, full-bridge circuit, EMI circuit, testing circuit and main control chip, it is straight that external solar plate exports
Stream voltage is input to interleaving inverse excitation circuit, and interleaving inverse excitation circuit includes two circuit of reversed excitation and corresponding two active clamps
Circuit, the 180 degree of alternations of said two circuit of reversed excitation phase, active clamp circuit is with the switching tube in circuit of reversed excitation also
Connection, the outfan of interleaving inverse excitation circuit is connected with the input of full-bridge circuit；Full-bridge circuit includes gate drive transformer, Shang Qiao
Arm, lower brachium pontis, upper brachium pontis and lower brachium pontis are driven by gate drive transformer, and full-bridge circuit is connected with electrical network by EMI circuit；Main
Control chip carries out data communication by testing circuit with interleaving inverse excitation circuit and full-bridge circuit.
Preferably, described active clamp circuit is made up of P-MOS pipe and clamp capacitor.The P-MOS pipe of active clamp circuit
Open in the moment that circuit of reversed excitation switching tube turns off, utilize the clamp capacitor in clamp circuit to absorb leakage inductance spike.
Preferably, described full-bridge circuit uses the full-bridge circuit that unfolding bridge-type drives, and wherein goes up brachium pontis and uses SCR pipe,
Lower brachium pontis uses traditional metal-oxide-semiconductor.Owing to the upper brachium pontis performance requirement of full-bridge is higher, use SCR pipe can bear big electric current.
Further, full-bridge circuit is connected between PWM outfan and the gate drive transformer of metal-oxide-semiconductor driving chip
There is ceramic condenser.Thus prevent gate drive transformer saturated.
Further, in described full-bridge circuit use frequency be 228kHZ, dutycycle be fixed as 50% PWM drive letter
Number.
Further, gate drive transformer is provided with the low pass for high-frequency driving signal is converted to direct current signal
Wave filter.For driving full-bridge with 2 times of power frequencies.
Preferably, EMI circuit includes one for the High-frequency Interference filtered in output electric current the LCL suppressing common-mode signal
Circuit, LCL circuit is made up of common mode choke induction and safety electric capacity, is arranged on the outfan of full-bridge circuit.
Further, connect respectively on the zero line at safety electric capacity two ends and live wire in LCL circuit an electric fuse.This guarantor
Danger silk is used for preventing temporary over-current from causing main circuit to burn out.
Further, being provided with a low-pass filter circuit after each electric fuse, this low-pass filter circuit is by a safety electric capacity
Forming with resistance, resistance receives ground wire.For eliminating High-frequency Interference, reduce harmonic wave rate.
Further, the outfan of each electric fuse is provided with a differential mode filter, this differential mode filter by an inductance and
Safety electric capacity forms, and this safety electric capacity receives ground wire.There is the effect preventing the such as lightning protection of electrical network moment peak.
Further, ground wire is also received through varistor in the inductance two ends in differential mode filter.For Additional Protection,
Prevent transient voltage spike.
Preferably, described inverter includes that power decoupling circuit, power decoupling circuit include several alminium electrolytic condensers, aluminum
Electrochemical capacitor is arranged on the positive and negative end of solar panels output.Owing to the input power of solar panels must keep constant ability
The energy acquisition making cell panel maximizes, and therefore can there is instantaneous power between input power and output and not mate, pass through
Above-mentioned electric capacity can balance the power of different moment.
A kind of grid-connected control method based on above-mentioned miniature photovoltaic grid-connected inverter, described interleaving inverse excitation circuit use based on
The dead beat grid-connected control method that electric current controls, including step:
(1) by sample circuit, PV voltage, flyback output electric current, flyback output voltage, line voltage, output electric current are turned
Turn to 0-3.3V voltage, and be input to the AD conversion passage of main control chip, and in the PWM cycle of a circuit of reversed excitation, perform
Sampling routine, is converted into digital quantity by above analog quantity；
(2) determined frequency and the phase place of electrical network by phase-locked loop pll, then obtain exporting the ginseng of electric current I according to sine table
Examine value；In software, each ADC interrupts line voltage of sampling, all can check the polarity of line voltage during sampling every time, as
Really line voltage polarity changes, and arranges a zero passage detection mark, and the ADC number of interruptions between each zero crossing determines
Periodic quantity；Then periodic quantity is used to determine the phase angle increment of sine table reference；Wherein, sine table have recorded amplitude and arrives according to 0
The output current reference value of 90 degree of sinusoidal variations；
(3) according to PV voltage Vin, line voltage Vo, export electric current Io, reference current Iref, and MPPT factor k, obtain
By electric current loop feedback and the control algolithm of Voltage loop feedforward:
Kpwm=Vo/ (N*Vin+Vo)+PI (k*Iref-Io)；
In formula, N represents the turn ratio of flyback transformer, and PI represents output electric current I is carried out PI computing, thus obtains wherein
The pwm signal of one main metal-oxide-semiconductor of circuit of reversed excitation, the pwm signal of the main metal-oxide-semiconductor of another circuit of reversed excitation and the PWM of this circuit of reversed excitation
Signal width is equal, delayed phase half period.Thus realizing circuit of reversed excitation output electric current is that twice mains frequency is unipolar
Sine wave, in circuit of reversed excitation, the pwm signal of the pwm signal of the P-MOS pipe of clamp circuit then metal-oxide-semiconductor main with circuit of reversed excitation is alternately
Conducting, is used for absorbing the leakage inductance of circuit of reversed excitation switching tube Guan Bi moment.
Preferably, described grid-connected control method includes CMP interrupt step, for occurring flyback output overvoltage or flyback defeated
Interrupted when entering stream.
The same due to the dutycycle of two circuit of reversed excitation switching tubes in theory, input current also should equally, but due to
The transducer that any two is actual, even if designing identical, its parameter also will necessarily be variant.Parameter differences can be at parasitic antenna
In observe, such as primary and secondary resistance, diode drop, Rdson and core loss etc..This type of parameter differences may cause it
In transducer overload, thus reduce efficiency and reliability.In the worst cases, the unbalance transducer that can also result in overload goes out
Existing thermal runaway phenomenon.Therefore, add load Sharing compensator and become extremely important, to guarantee that equality shares injection current.This
Bright described grid-connected control method includes load balancing steps, in this step: in grid-connected stage continuous service one load balance program,
The input current value of two circuit of reversed excitation of detection, it is poor to carry out two input current value, if current differential holds more than setting
Bear value, just the circuit of reversed excitation switching tube pwm signal that cutting-in control algorithm is tried to achieve the most every time is carried out manual compensation one constant
Value.
Preferably, described grid-connected control method includes power deratng step, including:
The peak value inverter output current that acquisition system exports under maximum/minimum output voltage；
Graph of a relation according to peak point current and input voltage obtains any input voltage, draws maximum according to input voltage
Peak value inverter current.
Preferably, described grid-connected control method uses disturbance observational method to realize MPPT tracking.Operation principle is: according to measurement
Input power regular increasing or decreasing reference current.If given disturbance causes PV module output to increase (reduction), then
Subsequent perturbations can be produced on identical (instead) direction.Every three ac cycles perform a MPPT program.Average input voltage and
Average current input is the parameter being delivered to MPPT program.The change of Mean Input Power and input voltage is calculated herein.
It is incremented by or the mpptFactor that successively decreases (reference current) is based on input power and the change of input voltage.
Preferably, in grid-connected control method, in real time photovoltaic panel voltage, flyback output electric current, output electric current, temperature are entered
Row detection, the number of times then flashed by LED if there is mistake carries out showing fault.
The present invention compared with prior art, has the advantage that and beneficial effect:
(1) present invention uses with active clamped interleaving inverse excitation circuit and full-bridge circuit as main circuit topology.First will too
The DC voltage of sun energy plate input changes into unipolar sine wave by interleaving inverse excitation circuit, then will by full bridge inverter
Unipolar sine wave changes into sine wave.Active clamp circuit can effectively reduce the former limit spike electricity when switching tube turns off
Stream.
(2) present invention is by arranging power decoupling circuit, can avoid not mating between input power and output leading
Cause the instability of main circuit.
(3) present invention employs the technology of load balance, the electric current input condition to two-way circuit of reversed excitation every 5 cycles
It is adjusted, solves interleaving inverse excitation circuit due to laod unbalance and cause the problem that transformator is saturated
(4) present invention employs power deratng technology, devise one and adjust maximum output according to photovoltaic input voltage
The program clamper of electric current.Ensure that inverter will not export excessive power in the case of low-voltage inputs.
(5) present invention employs the grid-connected algorithm of dead beat controlled based on electric current and MPPT algorithm based on current disturbing.
Owing to the relation of circuit of reversed excitation output voltage with the dutycycle controlling switching tube is non-linear, so cannot use based on voltage
Control method.Use current control method, make electric current with line voltage with frequency homophase, and by change electric current carry out maximum
Power tracking.Use dead-beat grid-connected algorithm, it is ensured that with frequency homophase and maximal power tracing between output waveform and electrical network.Right
Miniature photovoltaic grid-connected inverter in single-plate grade can carry out MPPT maximum power point tracking to every piece of photovoltaic panel, with traditional group string data phase
Ratio, hence it is evident that improve anti-shade ability.
(6) photovoltaic panel voltage, flyback output electric current, output electric current, temperature etc. can be detected by the present invention in real time, if
Occur that mistake can carry out showing fault by the number of times that LED flashes, and there is isolated island defencive function.
Accompanying drawing explanation
Fig. 1 is the present embodiment main circuit topology figure.
Fig. 2 is the interleaving inverse excitation circuit diagram of the present embodiment band active clamp.
Fig. 3 is the present embodiment circuit of reversed excitation working waveform figure.
Fig. 4 is the present embodiment EMI circuit diagram.
Fig. 5 is the present embodiment current regulator.
Fig. 6 is MPPT program flow diagram.
Detailed description of the invention
Below in conjunction with embodiment and accompanying drawing, the present invention is described in further detail, but embodiments of the present invention do not limit
In this.
Embodiment 1
Fig. 1 is the present embodiment one miniature photovoltaic grid-connected inverter main circuit topology figure.Miniature photovoltaic grid-connected inverter bag
Include power decoupling circuit, the interleaving inverse excitation circuit of band active clamp, full-bridge circuit, EMI circuit, testing circuit and DSP master control
Chip, the DC voltage of external solar plate output is input to interleaving inverse excitation circuit, the outfan of interleaving inverse excitation circuit and full-bridge
The input of circuit is connected, and full-bridge circuit is connected with electrical network by EMI circuit, and main control chip passes through testing circuit and interleaving inverse excitation
Circuit and full-bridge circuit carry out data communication.
In the present embodiment, power decoupling circuit is mainly arranged on 5 of the positive and negative end of solar panels output
The alminium electrolytic condenser of 2200uF.Owing to the input power of solar panels must keep the constant energy acquisition that just can make cell panel
, therefore can there is instantaneous power between input power and output and not mate, difference can be balanced by above-mentioned electric capacity in bigization
The power of moment.
Fig. 2 is the interleaving inverse excitation circuit diagram of the present embodiment band active clamp.Interleaving inverse excitation circuit includes two circuit of reversed excitation
(FLYBACK1, FLYBACK2) and corresponding two active clamp circuits, said two circuit of reversed excitation phase 180 degree
Alternation, thus improve operating frequency, reduce ripple size.And it comprises active clamp circuit, active clamp circuit
It is made up of P-MOS pipe and clamp capacitor, it is possible to effectively reduce switching tube shutdown moment, the due to voltage spikes at its drain-source two ends, and make
Leakage inductance energy is utilized.Interleaving inverse excitation circuit function is that the DC voltage of photovoltaic cell is being changed into twice mains frequency just
String half-wave current.As a example by Flyback1, for analyzing its operation principle, see working waveform figure as shown in Figure 3, Ug1, Ug2
For the driving signal of V11, V21, ip, is are the current waveforms of transformer primary side, secondary, and ig1, ig2 are the electric current of output.Work as guarantor
When card circuit is in continuous operation mode, during switching tube Guan Bi, primary current ip is linearly increasing, transformator T1 energy storage；Work as switch
When pipe disconnects, secondary current is linearly reduces, and electric capacity Csn has clamping action, absorbs leakage inductance, and transformator discharges energy to secondary simultaneously
Amount, is linearly reduces.Utilize and control dutycycle, thus realize exporting half-sinusoid.For realizing the input of photovoltaic panel 25-40V, output
200W power, switching tube maximum duty cycle 75%.Therefore the flyback transformer parameter of design is as follows: primary and secondary turn ratio is 12:1,
Primary inductance 27.6uH, secondary inductance 0.087uH.According to circuit of reversed excitation design criteria, switching tube maximum bears voltage value
For 400V, maximum is by electric current 12A.
In the present embodiment, full-bridge circuit uses the full-bridge circuit that unfolding formula drives, including gate drive transformer, Shang Qiao
Arm, lower brachium pontis, upper brachium pontis and lower brachium pontis are driven by gate drive transformer.Upper brachium pontis uses SCR pipe, and lower brachium pontis uses traditional
Metal-oxide-semiconductor.Gate drive transformer is provided with low pass filter, it is achieved that 225KHZ high-frequency driving signal is converted to direct current signal,
For driving full-bridge with 2 times of power frequencies.Full-bridge circuit use frequency be 228kHZ, dutycycle be fixed as 50% PWM drive signal.
Full-bridge circuit is in series with ceramic condenser between PWM outfan and the gate drive transformer of metal-oxide-semiconductor driving chip.
Fig. 4 is the present embodiment EMI circuit diagram.Employ DKFPC22C2N3L and 4mH common mode choke induction and 6 peaces in parallel
Rule electric capacity, the electric fuse composition of varistor S14 K320,2A.Common mode choke induction and a safety electric capacity composition LCL circuit,
For filtering the High-frequency Interference exported in electric current and suppressing common-mode signal.The zero line at safety electric capacity two ends and fire in LCL circuit
Connect on line electric fuse F1, a F2 respectively.Being provided with a low-pass filter circuit after each electric fuse, this low-pass filter circuit is by two
Safety electric capacity C49, C53 form, and resistance receives ground wire.The outfan of each electric fuse is provided with common-mode filter L4, a L7, is followed by
To differential mode filter, this differential mode filter is made up of an inductance L6 and safety electric capacity C48, C52, and this safety electric capacity receives ground wire.
The present embodiment grid-connected control method based on above-mentioned miniature photovoltaic grid-connected inverter, described interleaving inverse excitation circuit uses
The dead beat grid-connected control method controlled based on electric current, sees Fig. 5, including step:
(1) by sample circuit, PV voltage, flyback output electric current, flyback output voltage, line voltage, output electric current are turned
Turn to 0-3.3V voltage, and be input to the AD conversion passage of main control chip, and in the PWM cycle of a circuit of reversed excitation, perform
Sampling routine, is converted into digital quantity by above analog quantity；
(2) determined frequency and the phase place of electrical network by phase-locked loop pll, then obtain exporting the ginseng of electric current I according to sine table
Examine value；In software, each ADC interrupts line voltage of sampling, all can check the polarity of line voltage during sampling every time, as
Really line voltage polarity changes, and arranges a zero passage detection mark, and the ADC number of interruptions between each zero crossing determines
Periodic quantity；Then periodic quantity is used to determine the phase angle increment of sine table reference；Wherein, sine table have recorded amplitude and arrives according to 0
The output current reference value of 90 degree of sinusoidal variations；
(3) according to PV voltage Vin, line voltage Vo, export electric current Io, reference current Iref, and MPPT factor k, obtain
By electric current loop feedback and the control algolithm of Voltage loop feedforward:
Kpwm=Vo/ (N*Vin+Vo)+PI (k*Iref-Io)；
In formula, N represents the turn ratio of flyback transformer, and PI represents output electric current I is carried out PI computing, thus obtains wherein
The pwm signal of one main metal-oxide-semiconductor of circuit of reversed excitation, the pwm signal of the main metal-oxide-semiconductor of another circuit of reversed excitation and the PWM of this circuit of reversed excitation
Signal width is equal, delayed phase half period.Thus realizing circuit of reversed excitation output electric current is that twice mains frequency is unipolar
Sine wave, in circuit of reversed excitation, the pwm signal of the pwm signal of the P-MOS pipe of clamp circuit then metal-oxide-semiconductor main with circuit of reversed excitation is alternately
Conducting, is used for absorbing the leakage inductance of circuit of reversed excitation switching tube Guan Bi moment.
Although load balance be primarily directed to two circuit of reversed excitation design parameters be the same, switching tube dutycycle too,
It is likely that due in device error produce two circuit of reversed excitation be operated under discrepant state, long-term work is likely to result in
Magnetic core of transformer is saturated and burns out switching tube.So difference is more than certain model between the input current two circuit of reversed excitation being detected
Enclose, then the circuit of reversed excitation switching tube pwm signal that cutting-in control algorithm is tried to achieve the most every time is carried out one steady state value of manual compensation.
Owing to Miniature inverter is to be operated under nominal voltage (25-45V) support Maximum Power Output to be not more than 300W.Merit
Rate fall volume step is contemplated to guarantee that Miniature inverter will not be operated in more than under the power of 300W.In order to realize power deratng,
According to the peak AC pressure measured, devise a software clamper for maximum allowable output electric current.More than realizing
Function, we first have to draw, the peak value inverter output current that system exports under maximum/minimum output voltage.The most permissible
Use peak point current and the graph of a relation of input voltage, determine any input voltage, draw the peak value inverter current of maximum.
State machine program is that every 100us performs once, main faulty detection, MPPT tracking, the function of load balance.As
Fig. 6 is MPPT trace flow figure based on current disturbing, by changing current reference value Iref, makes power change, thus chases after
Track maximum power point.Operation principle is: according to the input power regular increasing or decreasing reference current measured.If given disturbance
Cause PV module output to increase (reduction), then can produce subsequent perturbations on identical (instead) direction.Every three ac cycles
Perform a MPPT program.Average input voltage and average current input are the parameters being delivered to MPPT program.Calculate herein
Mean Input Power and the change of input voltage.It is incremented by or the mpptFactor that successively decreases (reference current) is based on input power
Change with input voltage.
Overall software mainly includes initialization program, interrupt routine and three parts of state machine program.
The program that wherein initializes includes that system clock, PWM, AD sampling, SPI communication, CMP comparator, I/O mouth initialize journey
Sequence.
Interrupt routine includes AD Sampling interrupt program, CMP interrupt routine.AD Sampling interrupt program sampled before this PV voltage,
Flyback input current, flyback output voltage, line voltage, output electric current etc., then pass through such as the feedback control of Fig. 5, under obtaining
One moment circuit of reversed excitation dutycycle, so that current waveforms becomes standard sine wave.Idiographic flow is that to first pass through phase-locked loop pll true
Determine frequency and the phase place of electrical network, then obtain exporting the reference value of electric current I according to sine table.Re-use the reference value and reality obtained
The current value that border detects subtracts each other and is then passed through PI feedback regulation, finally obtains accurate sine wave.CMP interrupt routine is actual
On set to prevent flyback output overvoltage or flyback from inputting stream, once flyback input current is crossed stream and will be allowed system
Enter gross error pattern, forbid PWM simultaneously.
Above-described embodiment is the present invention preferably embodiment, but embodiments of the present invention are not by above-described embodiment
Limit, the change made under other any spirit without departing from the present invention and principle, modify, substitute, combine, simplify,
All should be the substitute mode of equivalence, within being included in protection scope of the present invention.
Claims (10)
1. a miniature photovoltaic grid-connected inverter, it is characterised in that include the interleaving inverse excitation circuit of band active clamp, full-bridge electricity
Road, EMI circuit, testing circuit and main control chip, the DC voltage of external solar plate output is input to interleaving inverse excitation circuit,
Interleaving inverse excitation circuit includes two circuit of reversed excitation and corresponding two active clamp circuits, said two circuit of reversed excitation phase place
Differ 180 degree of alternations, active clamp circuit and the paralleled power switches in circuit of reversed excitation, the outfan of interleaving inverse excitation circuit with
The input of full-bridge circuit is connected；Full-bridge circuit includes gate drive transformer, upper brachium pontis, lower brachium pontis, upper brachium pontis and lower brachium pontis
Being driven by gate drive transformer, full-bridge circuit is connected with electrical network by EMI circuit；Main control chip is by testing circuit and interlocks
Circuit of reversed excitation and full-bridge circuit carry out data communication.
Miniature photovoltaic grid-connected inverter the most according to claim 1, it is characterised in that described active clamp circuit is by P-
Metal-oxide-semiconductor and clamp capacitor composition.
Miniature photovoltaic grid-connected inverter the most according to claim 1, it is characterised in that described full-bridge circuit uses unfolding
The full-bridge circuit that bridge-type drives, wherein goes up brachium pontis and uses SCR pipe, and lower brachium pontis uses traditional metal-oxide-semiconductor；
Full-bridge circuit is in series with ceramic condenser between PWM outfan and the gate drive transformer of metal-oxide-semiconductor driving chip；
In described full-bridge circuit use frequency be 228kHZ, dutycycle be fixed as 50% PWM drive signal；
Gate drive transformer is provided with the low pass filter for high-frequency driving signal is converted to direct current signal.
Miniature photovoltaic grid-connected inverter the most according to claim 1, it is characterised in that EMI circuit includes one for filtering
Except the High-frequency Interference exported in electric current the LCL circuit suppressing common-mode signal, LCL circuit is by common mode choke induction and safety electric capacity
Composition, is arranged on the outfan of full-bridge circuit.
Miniature photovoltaic grid-connected inverter the most according to claim 4, it is characterised in that safety electric capacity two in LCL circuit
Connect respectively an electric fuse on the zero line of end and live wire；
Being provided with a low-pass filter circuit after each electric fuse, this low-pass filter circuit is made up of a safety electric capacity and resistance, resistance
Receive ground wire；
The outfan of each electric fuse is provided with a differential mode filter, and this differential mode filter is made up of an inductance and safety electric capacity, should
Safety electric capacity receives ground wire；
Ground wire is also received through varistor in inductance two ends in differential mode filter.
Miniature photovoltaic grid-connected inverter the most according to claim 1, it is characterised in that described inverter includes power decoupled
Circuit, power decoupling circuit includes several alminium electrolytic condensers, and alminium electrolytic condenser is arranged on the both positive and negative polarity two of solar panels output
End.
7., based on a grid-connected control method for miniature photovoltaic grid-connected inverter described in any one of claim 1-6, its feature exists
In, use the dead beat grid-connected control method controlled based on electric current, including step:
(1) by sample circuit, PV voltage, flyback output electric current, flyback output voltage, line voltage, output electric current are converted into
0-3.3V voltage, and it is input to the AD conversion passage of main control chip, and in the PWM cycle of a circuit of reversed excitation, perform once
Sampling routine, is converted into digital quantity by above analog quantity；
(2) determined frequency and the phase place of electrical network by phase-locked loop pll, then obtain exporting the reference value of electric current I according to sine table；
In software, each ADC interrupts line voltage of sampling, all can check the polarity of line voltage during sampling every time, if electric
Net polarity of voltage changes, and arranges a zero passage detection mark, and the ADC number of interruptions between each zero crossing determines the cycle
Value；Then periodic quantity is used to determine the phase angle increment of sine table reference；Wherein, sine table have recorded amplitude according to 0 to 90 degree
The output current reference value of sinusoidal variations；
(3) according to PV voltage Vin, line voltage Vo, export electric current Io, reference current Iref, and MPPT factor k, obtain by electricity
Stream ring feedback and the control algolithm of Voltage loop feedforward:
Kpwm=Vo/ (N*Vin+Vo)+PI (k*Iref-Io)；
In formula, N represents the turn ratio of flyback transformer, and PI represents output electric current I is carried out PI computing, thus obtains one of them
The pwm signal of the main metal-oxide-semiconductor of circuit of reversed excitation, the pwm signal of the main metal-oxide-semiconductor of another circuit of reversed excitation and the pwm signal of this circuit of reversed excitation
Width is equal, delayed phase half period.
Grid-connected control method the most according to claim 7, it is characterised in that described grid-connected control method includes load balance
Step, in this step: in grid-connected stage continuous service one load balance program, detect the input current value of two circuit of reversed excitation,
It is poor to carry out two input current value, if current differential is more than setting tolerance value, just to cutting-in control algorithm the most every time
The circuit of reversed excitation switching tube pwm signal tried to achieve carries out one steady state value of manual compensation.
Grid-connected control method the most according to claim 7, it is characterised in that described grid-connected control method includes power deratng
Step, including:
The peak value inverter output current that acquisition system exports under maximum/minimum output voltage；
Graph of a relation according to peak point current and input voltage obtains any input voltage, draws the peak value of maximum according to input voltage
Inverter current.
Grid-connected control method the most according to claim 7, it is characterised in that
Described grid-connected control method includes CMP interrupt step, for entering when inputting stream at generation flyback output overvoltage or flyback
Row interrupts；
Described grid-connected control method uses disturbance observational method to realize MPPT and follows the tracks of；
In grid-connected control method, in real time photovoltaic panel voltage, flyback output electric current, output electric current, temperature are detected, if
Occur that the number of times that mistake is then flashed by LED carries out showing fault.
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| CN106787911A (en) * | 2017-02-14 | 2017-05-31 | 苏州大学 | A kind of miniature photovoltaic grid-connected inverter and control method |
| CN107706945A (en) * | 2017-12-04 | 2018-02-16 | 河南城建学院 | A kind of system for suppressing inverter parallel system disturbance |
| CN108152561A (en) * | 2018-03-14 | 2018-06-12 | 广东海明晖电子科技有限公司 | Igh-speed wire-rod production line circuit |
| CN111200312A (en) * | 2020-01-02 | 2020-05-26 | 北京机械设备研究所 | MPPT controlling means under multiple input full environment |
| CN111917302A (en) * | 2020-06-23 | 2020-11-10 | 广州金升阳科技有限公司 | Control method and circuit for instantaneous power boost |
| CN114665732A (en) * | 2022-03-23 | 2022-06-24 | 重庆大学 | LCL single-phase grid-connected inverter control method based on circuit energy state |
| CN115133804A (en) * | 2022-08-26 | 2022-09-30 | 广州市迪士普信息科技有限公司 | AC output switch power supply |
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