CN205647288U - Non - isolated form photovoltaic grid -connected inverter - Google Patents
Non - isolated form photovoltaic grid -connected inverter Download PDFInfo
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- CN205647288U CN205647288U CN201620384279.2U CN201620384279U CN205647288U CN 205647288 U CN205647288 U CN 205647288U CN 201620384279 U CN201620384279 U CN 201620384279U CN 205647288 U CN205647288 U CN 205647288U
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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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Abstract
The utility model provides a non - isolated form photovoltaic grid -connected inverter, includes DC power supply, a filter capacitance, contravariant module, exports filter module, a filter capacitance connects in parallel in DC power supply's both ends, the utility model provides a loss that non - isolated form photovoltaic grid -connected inverter has formed the electric isolation between the afterflow period between electric wire netting and the photovoltaic board, and electric current reduced the switch tube through the 5th switch tube S5 and a freewheeling diode D1 or the 6th switch tube S6 and the 2nd freewheeling diode D2 this moment. Additionally, the utility model provides a non - isolated form photovoltaic grid -connected inverter electricity leakage -free miscarries and gives birth to, has improved system security nature and reliability to the high -quality low -harmonic -wave electric current that is incorporated into the power networks has been obtained.
Description
Technical field
This utility model relates to photovoltaic combining inverter technical field, particularly a kind of non-isolated photovoltaic grid-connected inverter.
Background technology
In recent years, grid-connected photovoltaic system PV has obtained all over the world developing widely, particularly has that efficiency is high, volume is little, lightweight, the development of the little power single phase photovoltaic parallel in system of the inverter of low cost is the most notable.
Generally, photovoltaic combining inverter can be divided into two kinds: isolated form inverter and non-isolation type inverter.Isolated form inverter generally includes inverter and the inverter of band high frequency transformer of band Industrial Frequency Transformer.Transformator can provide the electrical isolation between electrical network and photovoltaic array, and the existence of transformator can eliminate the leakage current between photovoltaic panel and ground, it can also be ensured that personal security.But the inverter size with Industrial Frequency Transformer is big and Heavy Weight, and this makes whole system heavy, it is difficult to install.Inverter with high frequency transformer often has several power level, which increases the complexity of system, reduces the efficiency of system.Transformerless inverter is due to its low cost, lightweight, and efficiency height becomes the first-selection of commercial field.Owing to there is no electrical isolation between photovoltaic array and electrical network, it will form parasitic capacitance between photovoltaic array and ground, when voltage is not zero or is non-constant in parasitic capacitance, it will form leakage current between photovoltaic array, ground and electrical network.Life security presence can be threatened and serious electromagnetic interference problem when leakage current is excessive.
Many topological structure eliminating leakage current are had been proposed for, such as bipolar SPWM full-bridge inverter, three level neutral-point-clamped inverter NPC and Heric, H5, H6 etc. in transless photovoltaic merging system.Employing bipolar SPWM full-bridge inverter can ensure that one constant common-mode voltage of generation and leakage current, but owing to the output filter needed for the double level voltage of output is big, so this will be system loss increase and power density reduction.Three level neutral-point-clamped inverters can also eliminate leakage current, and output voltage improves compared with full-bridge inverter, efficiency improves, the volume of output filter reduces.Three level neutral-point-clamped inverters need a bigger direct current supply voltage, which has limited the operating voltage range of photovoltaic panel.Heric, H5, H6 inverter and full-bridge inverter need identical low DC bus-bar voltage under Unipolar SPWM modulation strategy, but system power dissipation is big, reduce the quality of grid-connected current.
Utility model content
Technical problem to be solved in the utility model is to provide a kind of non-isolated photovoltaic grid-connected inverter, it is ensured that leakage current produces and and Heric, the low dc voltage that the input of H5, H6 inverter is identical.
For solving above-mentioned technical problem, this utility model be the technical scheme is that a kind of non-isolated photovoltaic grid-connected inverter, including DC source, the first filter capacitor, inversion module, output filtration module, it is characterised in that: described first filter capacitor is parallel to the two ends of DC source；
Described inversion module includes the first brachium pontis, the second brachium pontis, upper auxiliary brachium pontis, lower auxiliary brachium pontis；Described first brachium pontis includes the first switching tube and second switch pipe, and the emitter stage of the first switching tube is connected in parallel on the two ends of DC source with the colelctor electrode of second switch pipe after connecting；Described second brachium pontis includes the 3rd switching tube and the 4th switching tube, is connected in parallel on the two ends of DC source after the emitter stage of the 3rd switching tube and the colelctor electrode series connection of the 4th switching tube；Described upper auxiliary brachium pontis includes the first fly-wheel diode and the 5th switching tube, the anode of the first fly-wheel diode and the emitter stage series connection of the 5th switching tube, the negative electrode of the first fly-wheel diode and the emitter stage of the first switching tube connect, and the colelctor electrode of the 5th switching tube and the emitter stage of the 3rd switching tube connect；Described lower auxiliary brachium pontis includes the second fly-wheel diode and the 6th switching tube, the emitter stage of the 6th switching tube and the series connection of the second fly-wheel diode anode, the colelctor electrode of the 6th switching tube is connected with the colelctor electrode of second switch pipe, and the negative electrode of the second fly-wheel diode and the colelctor electrode of the 4th switching tube connect；
Described output filtration module includes that the first inductance, the second inductance and the second filter capacitor, one end of the first inductance are connected with the emitter stage of the first switching tube on the first brachium pontis, and the other end is connected with AC；One end of second inductance is connected with the colelctor electrode of the 4th switching tube on the second brachium pontis, and the other end is connected with AC；Second filter capacitor is connected in parallel on the two ends of AC network.
Preferably, described first switching tube, second switch pipe, the 3rd switching tube, the 4th switching tube, the 5th switching tube, the 6th switching tube all use insulated gate bipolar transistor IGBT.
Preferably, described first switching tube, second switch pipe, the 3rd switching tube, the 4th switching tube, the 5th switching tube, the 6th switching tube are all in parallel with fly-wheel diode, and emitter stage is connected with the positive pole of fly-wheel diode, and colelctor electrode is connected with the negative pole of fly-wheel diode.
A kind of non-isolated photovoltaic grid-connected inverter that this utility model is proposed, defining electrical isolation during afterflow between electrical network and photovoltaic panel, now electric current only reduces the loss of switching tube through the 5th switching tube S5 and the first sustained diode 1 or the 6th switching tube S6 and the second sustained diode 2.It addition, a kind of non-isolated photovoltaic grid-connected inverter leakage current that this utility model is proposed produces, improve the safety and reliability of system, and obtained the low harmony wave grid-connected current of high-quality.
Accompanying drawing explanation
The utility model is described in further detail with embodiment below in conjunction with the accompanying drawings:
Fig. 1 is structural representation of the present utility model；
Fig. 2 is the schematic diagram of logic module of the present utility model；
Fig. 3 is this utility model first stage current loop schematic diagram；
Fig. 4 is this utility model second stage current loop schematic diagram；
Fig. 5 is this utility model phase III current loop schematic diagram；
Fig. 6 is this utility model fourth stage current loop schematic diagram；
Fig. 7 is the oscillogram of this utility model common-mode voltage；
Fig. 8 is the oscillogram of this utility model leakage current；
Fig. 9 is the oscillogram of this utility model output voltage；
Figure 10 is the waveform of this utility model grid-connected current；
Figure 11 is the rate of total harmonics of this utility model grid-connected current.
Detailed description of the invention
As it is shown in figure 1, a kind of non-isolated photovoltaic grid-connected inverter, including DC source VDC, the first filter capacitor C1, inversion module, output filtration module, it is characterised in that: described first filter capacitor C1 is parallel to the two ends of DC source VDC；
Described inversion module includes the first brachium pontis, the second brachium pontis, upper auxiliary brachium pontis, lower auxiliary brachium pontis；Described first brachium pontis includes the first switching tube S1 and second switch pipe S2, and the emitter stage of the first switching tube S1 is connected in parallel on the two ends of DC source VDC with the colelctor electrode of second switch pipe S2 after connecting；Described second brachium pontis is connected in parallel on the two ends of DC source VDC after including the emitter stage of the 3rd switching tube S3 and the 4th switching tube S4, the 3rd switching tube S3 and the colelctor electrode series connection of the 4th switching tube S4；Described upper auxiliary brachium pontis includes the first sustained diode 1 and the 5th switching tube S5, the anode of the first sustained diode 1 and the emitter stage series connection of the 5th switching tube S5, the negative electrode of the first sustained diode 1 and the emitter stage of the first switching tube S1 connect, and the colelctor electrode of the 5th switching tube S5 and the emitter stage of the 3rd switching tube S3 connect；Described lower auxiliary brachium pontis includes the second sustained diode 2 and the 6th switching tube S6, the emitter stage of the 6th switching tube S6 and the series connection of the second sustained diode 2 anode, the colelctor electrode of the 6th switching tube S6 is connected with the colelctor electrode of second switch pipe S2, and the negative electrode of the second sustained diode 2 and the colelctor electrode of the 4th switching tube S4 connect；
Described output filtration module includes that the first inductance L1, the second inductance L2 and the second filter capacitor C2, one end of the first inductance L1 are connected with the emitter stage of the first switching tube S1 on the first brachium pontis, and the other end is connected with AC；One end of second inductance L2 is connected with the colelctor electrode of the 4th switching tube S4 on the second brachium pontis, and the other end is connected with AC；Second filter capacitor C2 is connected in parallel on the two ends of AC network.
Preferably, described first switching tube S1, second switch pipe S2, the 3rd switching tube S3, the 4th switching tube S4, the 5th switching tube S5, the 6th switching tube S6 all use insulated gate bipolar transistor IGBT.
Preferably, described first switching tube S1, second switch pipe S2, the 3rd switching tube S3, the 4th switching tube S4, the 5th switching tube S5, the 6th switching tube S6 are all in parallel with fly-wheel diode, emitter stage is connected with the positive pole of fly-wheel diode, and colelctor electrode is connected with the negative pole of fly-wheel diode.
As shown in Figure 2, two-way Unipolar SPWM modulation strategy is used in non-isolation type photovoltaic DC-to-AC converter topological structure, drive circuit works mode is when the positive half cycle of AC voltage, 5th switching tube S5 turns on all the time, the grid of the first switching tube S1 and the 4th switching tube S4 inputs identical high-frequency driving signal, high frequency turns on and off, 6th switching tube S6 turns off when the first switching tube S1 and the 4th switching tube S4 opens, when the first switching tube S1 and the 4th S4 turn off open-minded, second switch pipe S2 and the 3rd switching tube S3 turns off all the time；When AC voltage negative half cycle, 6th switching tube S6 turns on all the time, the grid of second switch pipe S2 and the 3rd switching tube S3 inputs identical high-frequency driving signal, high frequency turns on and off, 5th switching tube S5 turns off when second switch pipe S2 and the 3rd switching tube S3 opens, when second switch pipe S2 and the 3rd switching tube S3 turn off open-minded, the first switching tube S1 and the 4th switching tube S4 turns off all the time.
This utility model inverter has four working stages in power frequency period:
As shown in Figure 3, initial shift: at power-frequency voltage positive half period, 5th switching tube S5 turns on all the time, the high-frequency driving signal that first switching tube S1 and the 4th switching tube S4 input is identical, 6th switching tube S6 turns off when the first switching tube S1 and the 4th switching tube S4 opens, when the first switching tube switching tube S1 and the 4th switching tube S4 turn off open-minded, second switch pipe S2 and the 3rd switching tube S3 turns off all the time.During the first switching tube switching tube S1 and the 4th switching tube S4 conducting, grid-connected current is powered to electrical network through the first switching tube S1, the first inductance L1, the second inductance L2, the 4th switching tube S4.VAN=VDC, VBN=0V, so VAB=VDC, common-mode voltage VCM are:
As shown in Figure 4, second working stage: the first switching tube S1 and the 4th switching tube S4,6th switching tube S6 conducting, second switch pipe S2 and the 3rd switching tube S3 turns off all the time, 5th switching tube S5 conducting, by the first inductance L1, AC network, the second inductance L2, the 5th switching tube S5, the first sustained diode 1 form free wheeling path makes photovoltaic panel isolate with AC network.VAN=VBN=VDC/2, so VAB=0V, common-mode voltage VCM are:
As shown in Figure 5,3rd working stage: at power-frequency voltage negative half-cycle, 6th switching tube S6 turns on all the time, the high-frequency driving signal that second switch pipe S2 and the 3rd switching tube S3 input is identical, 5th switching tube S5 turns off when second switch pipe S2 and the 3rd switching tube S3 opens, when second switch pipe S2 and the 3rd switching tube S3 turn off open-minded, the first switching tube S1 and the 4th switching tube S4 turns off all the time.During second switch pipe S2 and the 3rd switching tube S3 conducting, grid-connected current is powered to electrical network through the 3rd switching tube S3, the second inductance L2, the first inductance L1, second switch pipe S2.VAN=0V, VBN=VDC, so VAB=-VDC, common-mode voltage VCM are:
As shown in Figure 6,4th working stage: second switch pipe S2 and the 3rd switching tube S3 turns off, 5th switching tube S5 conducting, first switching tube S1 and the 4th switching tube S4 turns off all the time, 6th switching tube S6 conducting, by the 6th switching tube S6, second sustained diode the 2, second inductance L2, AC network, the first inductance L1 constitute free wheeling path makes photovoltaic panel isolate with AC network.VAN=VBN=VDC/2, so VAB=0V, common-mode voltage VCM are:
Common-mode voltage is understood constant, so contributing to eliminating leakage current by analysis above.
Under two-way Unipolar SPWM modulation strategy, the waveform of common-mode voltage VCM, leakage current, output voltage VAB and grid-connected current is as shown in Fig. 7,8,9,10.
Work mode voltage without dither, eliminates the impact of Dead Time when line voltage zero passage.Exporting grid-connected current quality under two-way unipolarity modulation strategy more to optimize, reduce the rate of total harmonics of grid-connected current, the rate of total harmonics of grid-connected current is as shown in figure 11.
The unidirectional combining inverter of a kind of non-isolation type of this utility model eliminates threat and the problem of electromagnetic interference that personal safety is existed by leakage current, improves the reliability of system, reduces current thd and reduce dead time effect.
The above embodiments are only optimal technical scheme of the present utility model; and it is not construed as restriction of the present utility model; the technical scheme that protection domain of the present utility model should be recorded with claim, is protection domain including the equivalents of technical characteristic in the technical scheme that claim is recorded.Equivalent the most in this range is improved, also within protection domain of the present utility model.
Claims (2)
1. a non-isolated photovoltaic grid-connected inverter, including DC source (VDC), the first filter capacitor (C1), inversion module, output filtration module, it is characterised in that: described first filter capacitor (C1) is parallel to the two ends of DC source (VDC)；
Described inversion module includes the first brachium pontis, the second brachium pontis, upper auxiliary brachium pontis, lower auxiliary brachium pontis；Described first brachium pontis includes the first switching tube (S1) and second switch pipe (S2), and the emitter stage of the first switching tube (S1) is connected in parallel on the two ends of DC source (VDC) with the colelctor electrode of second switch pipe (S2) after connecting；Described second brachium pontis includes the 3rd switching tube (S3) and the 4th switching tube (S4), is connected in parallel on the two ends of DC source (VDC) after the emitter stage of the 3rd switching tube (S3) and the colelctor electrode series connection of the 4th switching tube (S4)；Described upper auxiliary brachium pontis includes the first fly-wheel diode (D1) and the 5th switching tube (S5), the anode of the first fly-wheel diode (D1) and the emitter stage series connection of the 5th switching tube (S5), the negative electrode of the first fly-wheel diode (D1) and the emitter stage of the first switching tube (S1) connect, and the colelctor electrode of the 5th switching tube (S5) and the emitter stage of the 3rd switching tube (S3) connect；Described lower auxiliary brachium pontis includes the second fly-wheel diode (D2) and the 6th switching tube (S6), the emitter stage of the 6th switching tube (S6) and the series connection of the second fly-wheel diode (D2) anode, the colelctor electrode of the 6th switching tube (S6) is connected with the colelctor electrode of second switch pipe (S2), and the negative electrode of the second fly-wheel diode (D2) and the colelctor electrode of the 4th switching tube (S4) connect；
Described output filtration module includes the first inductance (L1), the second inductance (L2) and the second filter capacitor (C2), one end of first inductance (L1) is connected with the emitter stage of the first switching tube (S1) on the first brachium pontis, and the other end is connected with AC；One end of second inductance (L2) is connected with the colelctor electrode of the 4th switching tube (S4) on the second brachium pontis, and the other end is connected with AC；Second filter capacitor (C2) is connected in parallel on the two ends of AC network.
A kind of non-isolated photovoltaic grid-connected inverter, it is characterised in that: described first switching tube (S1), second switch pipe (S2), the 3rd switching tube (S3), the 4th switching tube (S4), the 5th switching tube (S5), the 6th switching tube (S6) all use insulated gate bipolar transistor IGBT.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201620384279.2U CN205647288U (en) | 2016-04-29 | 2016-04-29 | Non - isolated form photovoltaic grid -connected inverter |
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| CN201620384279.2U CN205647288U (en) | 2016-04-29 | 2016-04-29 | Non - isolated form photovoltaic grid -connected inverter |
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107888104A (en) * | 2017-11-21 | 2018-04-06 | 燕山大学 | A kind of non-isolated three-phase Cuk inverters of monopole |
| CN109327155A (en) * | 2017-07-31 | 2019-02-12 | 比亚迪股份有限公司 | DC voltage turns inverter, method and the inverter of alternating voltage |
| CN109361322A (en) * | 2018-11-02 | 2019-02-19 | 湖南大学 | Non-isolation type five-electrical level inverter and its leakage current resist strategy |
| CN111697867A (en) * | 2019-03-11 | 2020-09-22 | 比亚迪股份有限公司 | Photovoltaic power supply system, inverter device and control method of inverter device |
| CN112019082A (en) * | 2020-10-22 | 2020-12-01 | 浙江艾罗网络能源技术有限公司 | Single-phase bidirectional inversion control circuit and inversion control method thereof |
| CN112838778A (en) * | 2021-01-06 | 2021-05-25 | 宜宾职业技术学院 | Non-isolated current type grid-connected inverter without overlapping time and control method and system thereof |
-
2016
- 2016-04-29 CN CN201620384279.2U patent/CN205647288U/en not_active Expired - Fee Related
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109327155A (en) * | 2017-07-31 | 2019-02-12 | 比亚迪股份有限公司 | DC voltage turns inverter, method and the inverter of alternating voltage |
| CN107888104A (en) * | 2017-11-21 | 2018-04-06 | 燕山大学 | A kind of non-isolated three-phase Cuk inverters of monopole |
| CN109361322A (en) * | 2018-11-02 | 2019-02-19 | 湖南大学 | Non-isolation type five-electrical level inverter and its leakage current resist strategy |
| CN111697867A (en) * | 2019-03-11 | 2020-09-22 | 比亚迪股份有限公司 | Photovoltaic power supply system, inverter device and control method of inverter device |
| CN111697867B (en) * | 2019-03-11 | 2022-03-18 | 比亚迪股份有限公司 | Photovoltaic power supply system, inverter device and control method of inverter device |
| CN112019082A (en) * | 2020-10-22 | 2020-12-01 | 浙江艾罗网络能源技术有限公司 | Single-phase bidirectional inversion control circuit and inversion control method thereof |
| CN112838778A (en) * | 2021-01-06 | 2021-05-25 | 宜宾职业技术学院 | Non-isolated current type grid-connected inverter without overlapping time and control method and system thereof |
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Granted publication date: 20161012 Termination date: 20170429 |
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