CN106058927A - Peak-current-based rapid algorithm for maximum power point of photovoltaic grid-connected micro inverter - Google Patents

Abstract

The invention relates to a peak-current-based rapid algorithm for a maximum power point of a photovoltaic grid-connected micro inverter. According to the invention, a peak current of a main switching tube of a photovoltaic grid-connected micro inverter is sample and a sum of peak currents is obtained; and then the sampled peak current is compared with a last maximum peak current and the sum of the peak currents is compared with a last sum of peak currents, thereby realizing maximum power point tracking of a photovoltaic assembly. With the algorithm, defects of complicated algorithm, low program operation efficiency, poor maximum power point tracking precision, and high hardware cost of the existing method can be overcome. Whether maximum power point tracking of the photovoltaic assembly is realized is determined by sampling peak currents in the switching tube, so that the sampling link of photovoltaic assembly voltages is saved and obtaining of an average input current of a photovoltaic assembly by a hardware/software filter link is avoided. Therefore, the hardware cost is lowered; the execution efficiency is high; resources of a digital control chip are saved; the anti-interference capability is improved effectively; and stability of system control is enhanced.

Description

Grid-connected micro-inverter maximum power point fast algorithm based on peak point current

Technical field

The invention belongs to power electronics and electrical technology field, particularly to grid-connected micro-inversion based on peak point current Device maximum power point fast algorithm.

Background technology

In grid-connected micro-inverter, control for realizing the MPPT maximum power point tracking of photovoltaic module, need to calculate photovoltaic The power of assembly, by comparing whether calculated power reaches maximum, judges that photovoltaic module has been operated in maximum the most Power points.

Common computational methods are the output voltage of photovoltaic module and output electric current to be done multiplying and obtain mean power. Need output voltage and the output electric current of sampled light photovoltaic assembly for this, traditional voltage detection method has difference sampling, resistance to divide Pressure sampling, the sampling of voltage Hall and linear optical coupling sampling；And the sampling of electric current mainly have inverter input circuit string resistance sampling, Current transformer and current Hall sampling.Based on voltage Hall and the method for sampling of current Hall, relatively costly.For flyback Grid-connected micro-inverter or the grid-connected micro-inverter of push-pull type High Frequency Link, owing to the input current of changer presents peak pulse shape, for Obtain the method that its average current generally requires hardware filtering and digital filtering combines, it is known that the most relatively costly, consume Program resource, and easily cause error, thus cause the tracking accuracy of maximum power point poor.

Before the present invention makes, the Demo plate of micro-core obtains flyback micro-inverter master by current transformer and has opened Closing the peak point current of pipe, the output voltage of the photovoltaic module obtained with sampling by this peak point current in a program is multiplied and obtains merit Rate, and then within some common frequency power network half periods, these performance numbers are added, and think that having obtained characterizing photovoltaic module puts down All linear numerical of output, by the size comparing this numerical value judge photovoltaic module whether realize maximum power point with Track controls.There is gross error in the most this computational methods, because under the conditions of fixing switching frequency, photovoltaic module is the most defeated Going out power with the peak point current in switching tube is relationships of increase function, and unrelated with the voltage of photovoltaic module, still more photovoltaic module Output voltage follow the tracks of during be real-time change, in general, photovoltaic module output electric current become big time, then photovoltaic group The voltage of part is on a declining curve, therefore the computational methods using the voltage of photovoltaic module to be multiplied with peak point current in switching tube judge The size of power, has bigger error, i.e. can not realize the accurate tracking of assembly peak power.

Thus be currently based on peak point current in switching tube be multiplied with photovoltaic module voltage the maximum power point obtaining power with Track computational methods, not only algorithm is complicated, and program operational efficiency is low, MPPT maximum power point tracking low precision, and hardware cost is higher, This is obviously difficult to the high-performance required by grid-connected micro-inverter, low cost.

Summary of the invention

Present invention aim to overcome that drawbacks described above, develop grid-connected micro-inverter peak power based on peak point current Point fast algorithm.

The technical scheme is that

Grid-connected micro-inverter maximum power point fast algorithm based on peak point current, it is mainly characterized by adopts The peak point current of the grid-connected micro-inverter main switch of sample, and the peak electricity will sampled within a common frequency power network half period Stream carries out size and compares, and obtains the peak inrush current in this common frequency power network half period；By described peak inrush current with upper The peak inrush current obtained in one common frequency power network half period compares size, if described peak inrush current has been maximum Value, the peak inrush current in the follow-up common frequency power network half period is all the least than described peak inrush current, then described Operating mode corresponding to peak inrush current is exactly the maximum power output of photovoltaic module, i.e. achieves the peak power of photovoltaic module Point is followed the tracks of.

The present invention another solution is that

Grid-connected micro-inverter maximum power point fast algorithm based on peak point current, it is mainly characterized by institute State the peak point current of grid-connected micro-inverter main switch of sampling, and the peak will sampled within a common frequency power network half period Value electric current does additive operation, thus obtains peak point current sum；By described peak point current sum and a upper common frequency power network half Peak point current sum in cycle compares size, if described peak point current sum reaches maximum, and follow-up common frequency power network half cycle Peak point current sum in phase is all the least than described peak point current sum, then the operating mode corresponding to described peak point current sum is just It is the maximum power output of photovoltaic module, i.e. achieves the MPPT maximum power point tracking of photovoltaic module.

The described peak inrush current in the common frequency power network half period, is the average input work of grid-connected micro-inverter Rate is the increasing function of peak inrush current in the common frequency power network half period, therefore can be according to the peak inrush current in the power frequency half period No reach maximum, judge that photovoltaic module has realized the tracking of maximum power point the most, if the maximum in the power frequency half period Peak point current is not reaching to maximum, then can be by the set-point of disturbance grid-connected current, until the maximum in the power frequency half period Peak point current is stable at maximum, thus realizes the MPPT maximum power point tracking of photovoltaic module.

The described peak inrush current in the common frequency power network half period and peak point current sum in the common frequency power network half period, also The peak inrush current obtained in being a common frequency power network half period is peak point current sum in this common frequency power network half period Increasing function, thus the Mean Input Power of grid-connected micro-inverter is also the increasing of peak point current sum in the common frequency power network half period Function, therefore whether can reach maximum according to the peak point current sum in the power frequency half period, judge that photovoltaic module is the most real The tracking of existing maximum power point.If the peak inrush current in the power frequency half period is not reaching to maximum, then can be by disturbing The set-point of dynamic grid-connected current, until the peak point current sum in the power frequency half period is stable at maximum, thus realizes photovoltaic group The MPPT maximum power point tracking of part.

The fast algorithm of the grid-connected micro-inverter maximum power point of the present invention, is had the advantage that and is only opened by sampling Close the size of peak point current in pipe, judge whether photovoltaic module realizes the tracking of maximum power point, photovoltaic module electricity can be saved The sampling element of pressure, and need not hardware or obtained the average current input of photovoltaic module by software filtering link.Thus can To reduce the hardware cost of grid-connected Miniature inverter；Judge whether photovoltaic module is operated in maximum power point, it is only necessary to warp Crossing logical operations and additive operation, without multiplying, therefore the execution efficiency of program is high, can save digital control chip Resource.If additionally by the method for the peak point current sum in the common frequency power network cycle, then capacity of resisting disturbance can be effectively improved, thus The stability that enhancing system controls.

Other advantages and the effect of the present invention will go on to say below.

The term related in the present invention: MPPT (Maximum Power Point Tracking), MPPT maximum power point tracking.

Accompanying drawing explanation

Fig. 1 principle of the invention explanation schematic diagram.

Fig. 2 application circuit of the present invention hardware constitutes schematic diagram.

Fig. 3 present invention realizes the control flow schematic diagram of MPPT by the size comparing peak value current maxima.

Fig. 4 present invention realizes the control flow schematic diagram of MPPT by the size comparing peak point current sum.

Fig. 5 present invention realizes the experimental waveform signal of MPPT maximum power point tracking based on peak point current sum algorithm Figure.

In figure, each label represents that corresponding component names is as follows:

Grid-connected micro-inverter master switch 1, current sample sensor 2, modulate circuit 3, program processing unit 4.

Designation in Fig. 1:

Designation in Fig. 2:

Designation in Fig. 3:

Designation in Fig. 4:

Detailed description of the invention

The technology major technique thinking of the present invention is:

Realize for current grid-connected micro-inverter that the algorithm of maximum power point is complicated, tracking accuracy is the highest, program Low and the relatively costly present situation of execution efficiency, it is proposed that grid-connected micro-inverter maximum power point based on peak point current is calculated quickly soon Method.

The present invention is specifically described below.

As shown in Figure 1 and Figure 2, the parts of the present invention are constituted:

Grid-connected micro-inverter master switch 1, current sample sensor 2, modulate circuit 3, program processing unit 4.Electric current Sampling sensor 2 is sampled the peak point current i in grid-connected micro-inverter master switch 1_s, after delivering to modulate circuit 3, it is then sent through number The program processing unit 4 of word control chip, within half common frequency power network cycle, electric current pressed by grid-connected micro-inverter master switch 1 During critical continuous mode work, obtain peak point current I successively_{pk_i}(i=1,2 ..., N).In program processing unit 4, by comparing I_{pk_i}Size can obtain peak inrush current I_{pk_max}；By to I_{pk_i}Summation can obtain the peak value in half power frequency period Electric current sum I_{pk_Sum}.In FIG, I_{p_max}It is peak inrush current I_{pk_max}The average current of place switch periods；I_{p_i}(i=1, 2 ..., N) it is peak point current I_{pk_i}The average current of place switch periods；I_{pk_sum}It is all peak values in half common frequency power network cycle Electric current I_{pk_i}Sum.

The present invention realizes the fast algorithm of grid-connected micro-inverter maximum power point, and sample grid-connected micro-inverter master The peak point current i of switching tube_sIf sampling number is n times within a common frequency power network half period, then obtains N number of peak point current and adopt I in sample value, i.e. corresponding program processing unit 4_{pk_i}, wherein i=1,2 ..., N.And by institute within a common frequency power network half period The peak point current I of sampling_{pk_i}Carry out size to compare, thus obtain the peak inrush current I in this common frequency power network half period_{pk_max}, By described peak inrush current I_{pk_max}Size is compared with the peak inrush current obtained in the upper common frequency power network half period, If described peak inrush current has been maximum, the peak inrush current in the follow-up common frequency power network half period is the most all than institute The peak inrush current I stated_{pk_max}Little, then described peak inrush current I_{pk_max}Corresponding operating mode is exactly photovoltaic module Maximum power output state, i.e. achieves the MPPT maximum power point tracking of photovoltaic module.

The N number of peak point current I that will be sampled within a common frequency power network half period_{pk_i}Do additive operation, thus obtain peak Value electric current sum I_{pk_Sum}, then by comparing this peak point current sum I_{pk_Sum}Whether reach maximum, if maximum, Then show to have been achieved with the MPPT maximum power point tracking of photovoltaic module, otherwise by the set-point of disturbance grid-connected current, until peak value Electric current sum reaches maximum, finally realizes the tracking of maximum power point.The concrete derivation of this conclusion is as follows:

The N number of peak point current I that will be sampled within a common frequency power network half period_{pk_i}Do additive operation, thus obtain peak Value electric current sum I_{pk_Sum}, by described peak point current sum I_{pk_Sum}With the peak point current in the upper common frequency power network half period it Compare with carrying out size, if described peak point current sum I_{pk_Sum}Reach maximum, the peak value in the follow-up common frequency power network half period Electric current sum is all the least than described peak point current sum, then the operating mode corresponding to described peak point current sum is exactly photovoltaic module Maximum power output, i.e. achieve the MPPT maximum power point tracking of photovoltaic module.

Theory analysis process is given below.As shown in the program processing unit 4 in Fig. 1: inverter exports the electricity of electrical network Stream waveform should be the sine wave Tong Bu with line voltage, it is clear that when sinusoidal wave crest and trough, output electric current reaches maximum, The peak point current now flow through in main switch is up to maximum I_{Pk_max}, the average current within the respective switch cycle is denoted as I_{p_max}.If the output voltage of photovoltaic module is U_i, the output electric current of photovoltaic module is I_i, then the average output power of photovoltaic module Can be calculated within a common frequency power network half period, such as formula (1):

$P_i=U_i\·I_i=\frac{2}{\mathrm{\π}}\·U_i\·I_{p\_\max }---\left(1\right)$

Switch periods T_SIn, if the ON time of switching tube is t_on, then peak point current I can be obtained_{pk_max}With Average current I in corresponding switch periods_{p_max}Relation such as formula (2):

$\frac{1}{2}\·t_{on}\·I_{pk\_max}=I_{p\_max}\·T_s---\left(2\right)$

If the inductance value of transformer primary side is L in circuit_m, the voltage U of photovoltaic module can be obtained_iWith peak point current I_{pk_max}Pass System, sees formula (3):

$\frac{U_i}{L_m}\·t_{on}=I_{pk\_\max }---\left(3\right)$

Formula (3) is deformed and obtains formula (4):

$t_{on}=I_{pk\_max}\·\frac{L_m}{U_i}---\left(4\right)$

Formula (1) is deformed and obtains formula (5):

$I_{p\_max}=\frac{\mathrm{\π}\·I_i}{2}---\left(5\right)$

Formula (4), (5) are brought in formula (2) to obtain formula (6):

$P_i=I_i\·U_i=\frac{L_m\·I_{pk\_max}^2}{\mathrm{\π}\·T_s}---\left(6\right)$

Ignoring loss, the output of photovoltaic module is exactly the input power of micro-inverter.Photovoltaic is can be seen that from formula (6) The output P of assembly_iWith I² _{pk_max}It is directly proportional, and works as I_{pk_i}During ＞ 0, the output P of photovoltaic module_iIt is I_{pk_max}Dullness Increasing function.Analyze based on above, when maximal power tracing controls, can be by judging I_{pk_max}Whether reach maximum real The tracking of existing maximum power point.

Specifically combining Fig. 3 explanation, Fig. 3 is the method for perturbation MPPT control flow judged based on peak point current maximum.I_gref Being the set-point of grid-connected current amplitude, its initial value is given in initialization program, Δ I_gDisturbance for grid-connected current amplitude walks Long.Program calls method of perturbation MPPT subprogram with the integral multiple time of common frequency power network half period, by current grid-connected current width Value set-point I_grefCommon frequency power network half period peak point current maximum I corresponding to (k)_{pk_max}K () and a upper peak point current are It is worth greatly I_{pk_max}(k-1) size is compared, if present peak value current maxima I_{pk_max}K () is more than I_{pk_max}(k-1), according to above-mentioned point Analysis is known, now the output of photovoltaic module increases, therefore corresponding I_grefShould continue to carry out disturbance, even by same direction I_grefK () is more than I_gref(k-1), then the amplitude of current grid-connected current is given should be modified to I_gref(k)=I_gref(k)+ΔI_g, otherwise Should be I_gref(k)=I_gref(k)-ΔI_g.If present peak value current maxima I_{pk_max}K () is less than I_{pk_max}(k-1), according to above-mentioned Analysis is known, now the output of photovoltaic module reduces, therefore corresponding I_grefDisturbance should be carried out in the opposite direction, even I_grefK () is more than I_gref(k-1), then the amplitude of current grid-connected current is given should be modified to I_gref(k)=I_gref(k)-ΔI_g, otherwise Should be I_gref(k)=I_gref(k)+ΔI_g.Work as I_{pk_max}(k) and I_{pk_max}(k-1) during approximately equal, then photovoltaic module work is shown Make at maximum power point, corresponding I_grefIt it is then grid-connected current benchmark during maximum power point.Fig. 3 gives with the grid-connected electricity of disturbance Stream amplitude judges a kind of method of perturbation MPPT that peak power point methods combines with heretofore described peak point current maximum Tracing control flow process.If combining with the present invention with the voltage of disturbance light photovoltaic assembly, as effect is also.

According to above-mentioned analysis, based on peak point current maximum I_{pk_max}Maximum power point fast algorithm, comprise two levels Logic size judge, be first to peak point current I within the common frequency power network half period_{pk_i}Carry out the ratio of n times peak current level Relatively, the peak point current maximum I in this common frequency power network half period is obtained_{pk_max}, followed by by the different common frequency power network half periods Peak point current maximum carries out the comparison of logic size, thus judges whether to realize the tracking of maximum power point.

In view of actual application, interference that the peak point current sampled is switched by HF switch unavoidably and occur Sampling error, this may result in the mistake that maximum power point judges.For the existence of interference, commonly used flat in digital control The method all filtered.By the N number of peak point current I in the common frequency power network half period in the present invention_{pk_i}Take and, i.e. transported by addition Calculate peak point current sum I obtaining in the common frequency power network half period_{pk_Sum}, such as formula (7).

$I_{pk\_sum}=\underset{i=1}{\overset{N}{\Σ}}{I}_{pk\_i}=k\·I_{pk\_\max }---\left(7\right)$

In formula, I_{pk_i}Being switching tube peak point current in each switch periods in the common frequency power network half period, N is power frequency electric The sampling number of peak point current in the net half period, k is constant.

By formula (7) it can be seen that work as I_{pk_i}During ＞ 0, peak point current sum I in the common frequency power network half period of inverter_{pk_sum} It is peak point current maximum I in this common frequency power network half period_{pk_max}Monotonic increasing function.Due to monotonic increasing function inverse function also It is monotonic increasing function, so the I in the identical common frequency power network half period_{pk_max}Also it is I_{pk_sum}Monotonic increasing function.Convolution (6) The conclusion arrived, it is recognised that work as I_{pk_i}During ＞ 0, output power of photovoltaic module P_iIt it is peak point current sum in the common frequency power network half period I_{pk_sum}Monotonic increasing function.Therefore the maximum power point of photovoltaic module can use peak point current sum in the common frequency power network half period I_{pk_sum}Size judge, the peak point current sum in the different common frequency power network half periods can be compared, if when certain work Frequently there is maximum in the peak point current sum in the electrical network half period, then this photovoltaic module voltage corresponding to common frequency power network half period Operating mode corresponding to set-point or grid-connected current set-point has realized the tracing control of maximum power point the most.The most just to photovoltaic group The voltage set-point of part or the set-point of grid-connected current carry out disturbance, until the peak point current sum in the common frequency power network half period goes out Existing maximum.

Propose based on peak point current sum I_{pk_sum}Maximum power point fast algorithm implementation MPPT tracing control, specifically In conjunction with Fig. 4 explanation.Fig. 4 is the method for perturbation MPPT control flow judged based on peak point current sum.I_grefIt it is grid-connected current amplitude Set-point, its initial value is given in initialization program, Δ I_gDisturbance step-length for grid-connected current amplitude.With power frequency in program The integral multiple time of electrical network half period calls method of perturbation MPPT subprogram, by current grid-connected current amplitude set-point I_gref(k) Corresponding common frequency power network half period peak point current sum I_{pk_sum}(k) and a upper peak point current maximum I_{pk_sum}(k-1) ratio Relatively size, if present peak value electric current sum I_{pk_sum}K () is more than I_{pk_sum}(k-1), know according to above-mentioned analysis, now photovoltaic module Output increase, therefore corresponding I_grefShould continue to carry out disturbance, even I by same direction_grefK () is more than I_gref(k- 1), then the amplitude of current grid-connected current is given should be modified to I_gref(k)=I_gref(k)+ΔI_g, otherwise should be I_gref(k)=I_gref (k)-ΔI_g.If present peak value electric current sum I_{pk_sum}K () is less than I_{pk_sum}(k-1), know according to above-mentioned analysis, now photovoltaic group The output of part reduces, therefore corresponding I_grefDisturbance, even I should be carried out in the opposite direction_grefK () is more than I_gref(k-1), Then the amplitude of current grid-connected current is given should be modified to I_gref(k)=I_gref(k)-ΔI_g, otherwise should be I_gref(k)=I_gref(k)+ ΔI_g.Work as I_{pk_max}(k) and I_{pk_max}(k-1) during approximately equal, then show that photovoltaic module has been operated in maximum power point, accordingly I_grefIt it is then grid-connected current benchmark during maximum power point.Fig. 4 gives with disturbance grid-connected current amplitude with heretofore described Peak point current sum judge a kind of method of perturbation MPPT tracing control flow process that peak power point methods combines.If with disturbance light The voltage of photovoltaic assembly combines with the present invention, as effect is also.

The present invention propose based on peak point current sum I_{pk_sum}Maximum power point fast algorithm, it is achieved maximum power point Judgement mainly include two levels.First is to obtain the peak point current sum in the common frequency power network half period, followed by by difference Peak point current sum in the common frequency power network half period carries out the logic of size and compares.This method relates to additive operation, and logic Relatively, therefore program operation speed is fast, and execution efficiency is high.With based on peak point current maximum I_{pk_max}Maximum power point calculate quickly soon Method is compared, due to watt level judge compared decision by the size of the peak point current sum in the common frequency power network half period, it is to avoid The impact that switch interference causes, thus can effectively improve capacity of resisting disturbance, strengthen the stability of system.

From upper analysis: according to maximum power point fast algorithm based on peak point current proposed by the invention, with Grid-connected current amplitude disturbance method realizes maximal power tracing control, it is not necessary to the voltage U of sampled light photovoltaic assembly_i, and need not input Voltage U_iWith input current I_iIt is multiplied and obtains concrete power P_i, it is possible to obtain maximum power point.Therefore the base proposed in the present invention In peak point current maximum I_{pk_max}Maximum power point fast algorithm, the speed of maximum power point algorithm can be improved and perform effect Rate, saves the resource of program；The sampling element of input voltage can be saved simultaneously, thus reduce cost.

Knowable to above-mentioned analysis: by regulating the given I of grid-connected current amplitude_grefSize, or regulation photovoltaic module Voltage set-point, after suitable control, if the peak point current maximum in the common frequency power network half period or peak point current sum It is in maximum, indicates that photovoltaic module has been operated in maximum power point.

It is as follows that of the present invention is embodied as example:

Based on peak point current for the present invention grid-connected micro-inverter maximum power point fast algorithm is applied 245W's In the grid-connected micro-inverter of flyback, as shown in Figure 2: the input voltage range of photovoltaic module: U_i=22V～50V, specified electricity Net voltage v_g=180～265V, specified mains frequency 50Hz/60Hz, mains frequency scope 47-51.5/57～60.5Hz.Flyback Main metal-oxide-semiconductor in circuit uses Infineon 190N15NS, and the model of flyback transformer secondary fly-wheel diode is Cree company C4D02120A, current sensor uses the B82801B305A125 of EPCOS company, and operational amplifier uses micro-core MCP6022-I, control chip uses the single-chip microcomputer MK10DX64VLF5 of Freescale.

Flyback micro-inverter main switch Q₁In electric current i_sBy current sensor TR₂Sampling, the turn ratio is 100: 1, sensing The secondary sampler resistance R of device₁Sample rate current is become current sampling signal, delivers to current regulating circuit, the fortune in modulate circuit Put MCP6022-I and current sampling signal is transformed into the receptible signal of single-chip microcomputer, send single-chip microcomputer Program processing unit to enter Row processes.In the program processing unit of single-chip microcomputer, obtain the peak value in the common frequency power network half period by simple additive operation Electric current sum I_{pk_sum}, then use the method for perturbation MPPT such as Fig. 4 to control, by comparing the size in the common frequency power network half period, look for Arrive corresponding grid-connected current set-point I_gref, grid-connected current ring uses PI to control, it is achieved thereby that the peak power of embodiment Point is followed the tracks of, and Fig. 5 show the experimental waveform of maximal power tracing, and MPPT tracking accuracy reaches 0.99.The side that the visible present invention proposes Method is effective.

Embodiment is provided without traditional power calculation and power compares the tracking and controlling method obtaining maximum power point, does not also have There is the input voltage of sampled light photovoltaic assembly, simply have employed the additive operation of peak point current summation, and use peak current level Logical algorithm relatively, therefore the arithmetic speed of corresponding program arithmetic element is very fast and execution efficiency is higher；Embodiment grid-connected micro- Inverter is owing to eliminating the voltage sampling circuit of photovoltaic module, and cost is relatively low.Invention based on peak point current maximum power point Fast algorithm is applicable not only to the grid-connected Miniature inverter of flyback, the grid-connected Miniature inverter of push-pull type High Frequency Link, and is applicable to Micro-inverter circuit topology of all peak value comparison method.

Knowable to above description, based on peak point current grid-connected micro-inverter maximum power point of invention is calculated quickly soon Method, has the advantage that

(1) need not voltage sampling circuit, reduce cost；

(2) fast algorithm invented has saved the resource of digital control chip, improves the speed of algorithm, improves program Execution efficiency；

(3) fast algorithm invented is widely used, and is not limited solely to grid-connected micro-inverter, be also used in photovoltaic from Net inverter；

(4) tracking of this fast algorithm implementation maximum power point can also be utilized in the wind-power electricity generation of middle low power.

The invention is not limited in above-described embodiment, on the basis of technical scheme disclosed by the invention, the skill of this area Art personnel are according to disclosed technology contents, it is not necessary to some of which technical characteristic just can be made one by performing creative labour A little replacements and deformation, these are replaced and deformation is the most within the scope of the present invention.

Claims (4)

1. grid-connected micro-inverter maximum power point fast algorithm based on peak point current, it is characterised in that sample grid-connected The peak point current of micro-inverter main switch, and within a common frequency power network half period, the peak point current sampled is carried out size Relatively, the peak inrush current in this common frequency power network half period is obtained；By described peak inrush current and a upper power frequency electric The peak inrush current obtained in the net half period compares size, if described peak inrush current has been maximum, follow-up Peak inrush current in the common frequency power network half period is all the least than described peak inrush current, then described peak-peak electricity Operating mode corresponding to stream is exactly the maximum power output of photovoltaic module, i.e. achieves the MPPT maximum power point tracking of photovoltaic module.

2. grid-connected micro-inverter maximum power point fast algorithm based on peak point current, it is characterised in that described sampling photovoltaic The peak point current of grid-connected micro-inverter main switch, and within a common frequency power network half period, the peak point current sampled is done and add Method computing, thus obtain peak point current sum；By described peak point current sum and the peak in the upper common frequency power network half period Value electric current sum compares size, if described peak point current sum reaches maximum, and the peak value in the follow-up common frequency power network half period Electric current sum is all the least than described peak point current sum, then the operating mode corresponding to described peak point current sum is exactly photovoltaic module Maximum power output, i.e. achieve the MPPT maximum power point tracking of photovoltaic module.

3. based on based on peak point current the grid-connected micro-inverter maximum power point fast algorithm described in claim 1, its Being characterised by the peak inrush current in described common frequency power network half period, the Mean Input Power of grid-connected micro-inverter is The increasing function of peak inrush current in the common frequency power network half period, therefore whether can reach according to the peak inrush current in the power frequency half period To maximum, judge that photovoltaic module has realized the tracking of maximum power point the most；If the peak-peak in the power frequency half period Electric current is not reaching to maximum, then can be by the set-point of disturbance grid-connected current, until the peak-peak in the power frequency half period Current stabilization is at maximum, thus realizes the MPPT maximum power point tracking of photovoltaic module.

4. quick based on based on peak point current the grid-connected micro-inverter maximum power point described in claim 1 or 2 or 3 Algorithm, it is characterised in that the described peak inrush current in the common frequency power network half period and peak point current in the common frequency power network half period Sum, the peak inrush current obtained in also residing in a common frequency power network half period is peak point current in this common frequency power network half period The increasing function of sum, thus the Mean Input Power of grid-connected micro-inverter be also in the common frequency power network half period peak point current it The increasing function of sum, therefore whether can reach maximum according to the peak point current sum in the common frequency power network half period, judge photovoltaic group Part has realized the tracking of maximum power point the most, if the peak inrush current in the power frequency half period is not reaching to maximum, then Can be by the set-point of disturbance grid-connected current, until the peak point current sum in the power frequency half period is stable at maximum, thus Realize the MPPT maximum power point tracking of photovoltaic module.