[introduction] MPPT (Maximum Power Point Tracking) it is the crucial part that system of inverter of smooth hot season implements the oldest rate to use solar energy, different MPPT develop attacks have respective characteristic. The circuit of 3 kinds of MPPT with article comparative and common general, restrict to the switch mode of double Boost (Dual Boost) did former rational analysis, intuitionistic explained Dual Boost cannot make wrong switch in MPPT. Be aimed at different voltage and voltaic grade, the program of type selecting of referenced parts of an apparatus that the article offerred Ying Feiling to attack in the light of all sorts of develop, offer advantage to design efficient and reliable MPPT.

MPPT (Maximum Power Point Tracking) it is the crucial part that system of inverter of smooth hot season implements the oldest rate to use solar energy, different MPPT develop attacks have respective characteristic. The circuit of 3 kinds of MPPT with article comparative and common general, restrict to the switch mode of double Boost (Dual Boost) did former rational analysis, intuitionistic explained Dual Boost cannot make wrong switch in MPPT. Be aimed at different voltage and voltaic grade, the program of type selecting of referenced parts of an apparatus that the article offerred Ying Feiling to attack in the light of all sorts of develop, offer advantage to design efficient and reliable MPPT.

MPPT fundamental and commonly used develop attack

How solar energy electric energy of translate into of the oldest rate, besides the development of technology of oneself of cell panel of smooth hot season, most high-power dogs MPPT also is to compress the important segment of solar energy utilization rate. Usually, illumination strength is greater, the power that cell panel of smooth hot season can output is greater also. The output character curve that next graphs are the cell panel below certain illumination intensity, the output power that can discover existence a certain a little bit is the greatest (MPP, maximum Power Point) .

The model that this phenomenon can simplify with will explain, pursue as follows. The power that laden resistor receives is:

When output resistor Ro adjustment arrives to be the same as with photograph of Rint of power source internal resistance when, load can be received most high-power. The MPPT circuit in system of smooth hot season rose to adjust the input impedance of laden end, in order to obtain most the purpose of high-power.

MPPT chooses blame segregation commonly model DC/DC circuit, buck, Boost and Buck-Boost circuit have appropriate applied situation. Just Buck and Buck-Boost are general and multi-purpose in system of smooth hot season of Yu Xiaogong rate, allude again in lieutenant general of the following article this one part, here does not make the introduction more. The MPPT of high-power is Boost circuit reachs his to derive circuit commonly in, attack besides develop of Boost circuit itself simple beyond, inversion side also makes step up circuit more welcome to the demand of high-pressured dc generatrix.

Above is the commonly used Boost circuit in MPPT reachs his to derive the develop of circuit to attack, the structure of Single Boost circuit of two n is simple, but somes the voltage stress of parts of an apparatus will be greater; Dual Boost and Flying Capacitor Boost belong to the develop of 3 n to attack, consequently the voltage stress halve of parts of an apparatus, but these two kinds of develop attack to still have in application of MPPT of smooth hot season very big different.

Dual Boost is restricted in the switch mode in MPPT

As a result of in all the problem of modular leakage current [1] , two of Dual Boost active canals cannot crisscross, can synchro switch, cannot remove times frequency to reduce the effect of inductance. Graph 6 it is cell panel of consideration smooth hot season of right parasitism capacitance simplify system, cpv+ and Cpv- are batteries array respectively losing bus to be allowed to terrestrial electricity, LP, LN is Boost input inductance, LA, LB and LC are the output inductance of inverter. Terrestrial electricity flows namely in all if modular leakage current crosses old saying, cannot satisfy safe level on one hand, the life to itself of cell panel of smooth hot season is influential also on the other hand. Graph 7 it is to will pursue 6 after undertaking communicating equivalent simplify circuit, the difference of oversight parts of an apparatus, hypothesis LP=LN=L, cpv+=Cpv-=Cpv/2, LA=LB=LC=Lf, when Dual Boost takes different control kind, in all Ic can have modular leakage current different expression.

When Dual Boost switch, can draw up conveniently through super position theorem equivalent the expression of IC:

Hypothesis three-phase voltage is balanced, so the vector of VAN, VBN, VCN and for 0, IC can simplify again for:

From here we can see after eliminating difference of yuan of parts of an apparatus, same develop attacks in all the Yu Zheng of value direct ratio of modular leakage current loses bus in all modular voltage size. To facilitate everybody’s more intuitionistic understanding, here undertakes complex Fourier is decomposed no longer, use two pieces of graphs to contrast however. Graph 8 with the graph 9 it is different job mode falls, VP+vN and dc output the ratio of voltage. From this the contrast of two graphs can see, final Fourier discloses a result also is to differ δ of function of a pulse (ω ) . When using switch of Dual Boost crisscross accordingly when modular leakage current can compare synchro switch, should get greatly in all much, exceed VDE very easily or the value of the standard such as GB/T.

Here also can carry Single Boost incidentally, from the graph 10 can see of bus in all modular noise source is lost bus bypass, do not produce pair of ground in all modular leakage current.

The characteristic of FC Boost

The method of use above, can push derive FC Boost is nonexistent in all the problem of modular leakage current, two active canals can make wrong switch, carry the switch frequency of advanced effect, accordingly same voltaic ripple and switch frequency fall, inductance value can be original in part. But FC Boost develop attacks relatively as complex as control, still need to introduce fly to those who cross capacitance to charge beforehand circuit, and still have a few patent camp [2] , bring about the threshold that uses this develop to attack taller.

Solution of module of MPPT circuit Ying Feiling

Attack in the light of different develop with power demand, ying Feiling has efficient and credible solution. Some closer year of development as technology of itself of batteries of smooth hot season, veneer electric current is bigger and bigger, the requirement of power station of smooth hot season to only made of baked clay cost makes again of the system hand in volts d.c. taller and taller. Heal in the light of this kind of voltage tall electric current heals big trend, ying Feiling needed design of innovation of sue for peace to develop all sorts of module products according to the client’s application.

Module product is based on Ying Feiling’s Easy to enclose, having buy of agile Pin card clothing and dinky stray inductance, a chip and develop can be developed to attack on the oldest rate the advantage of itself. Graph 11 it is main a few program, express the 1 material information that is the applicable module plan below 1500V system. Among them DF4-19MR20W3M1HF_H94 is used precede inside course of study technology of 2kV SiC chip, every module has 4 Boost, attack through simple develop the 40A above MPPT that can realize 1500VDC system to fall, switch frequency can be pushed come high 30kHz above reduces inductance size further.

Sheet of flying approach of MPPT circuit flower provides a solution

The IGBT as high-pressured big electric current and product of SiC sheet canal are increasing, plan of more and more schism parts of an apparatus also appear in system of smooth hot season in order to reduce integral cost. The TRENCHSTOP of Ying Feiling 1200V? Give attention to two or morethings of IGBT7 H7 product guide a loss and switch loss, suit the application of Boost MPPT very much. Expressing sheet of 2 MPPT IGBT to provide a solution is when be aimed at different electric current, switch frequency 16kHz leaves commendatory IGBT specification. If use SiC in order to acquire more exceedingly good property, the switch frequency that twice promotes (32kHz) also can make filter wave inductance is reduced greatly, commendatory program sees a table 3.

With the batteries of smooth hot season of 40A the input is exemple, input 520V, output 800V, consider the voltaic ripple circumstance of 40% to fall, the loss of IGBT plan and SiC plan and knot lukewarm copy are as follows as a result really.

Can see using commendatory program, IGBT works at 16kHz, siC works at 32kHz, in the model be fully loaded with operating mode to fall, the loss of single pipe and knot are lukewarm have adequate abundant amount. Because this is OK also,the attempt mentions switch frequency taller, with promoting power density further. If use the parts of an apparatus of ability of bigger electric current to reduce paralell connection,also be possible, specific the design convention that watchs him everybody even.

Above is MPPT fundamental and Ying Feiling solution, everybody can be based on this to make reference when doing plan type selecting. But differ as a result of limits of the voltage of cell panel of different smooth hot season, electric current, different design is used to medium voltaic ripple to also differ, particular case still needs to combine specific operating mode to do evaluate in detail.

Bibliographical reference

[1]  Terrestrial electricity of inverter of smooth hot season flows analysis and restrain. Su Na. Doctor’s degree paper

[2]  DC/DC Power Conversion Apparatus. T. Okuda. US Patent

(Author: Spend article quick origin: Semiconductor of Ying Feiling industrySemiconductor of Ying Feiling industry

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