CN105958526A - Single-phase non-isolated photovoltaic grid connected inverter - Google Patents

Single-phase non-isolated photovoltaic grid connected inverter Download PDF

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Publication number
CN105958526A
CN105958526A CN201610047357.4A CN201610047357A CN105958526A CN 105958526 A CN105958526 A CN 105958526A CN 201610047357 A CN201610047357 A CN 201610047357A CN 105958526 A CN105958526 A CN 105958526A
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CN
China
Prior art keywords
fly
wheel diode
inverter
circuit
switching tube
Prior art date
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Pending
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CN201610047357.4A
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Chinese (zh)
Inventor
康家玉
王旭
周猛
刘甲琛
曹志威
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Shaanxi University of Science and Technology
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Shaanxi University of Science and Technology
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Priority to CN201610047357.4A priority Critical patent/CN105958526A/en
Publication of CN105958526A publication Critical patent/CN105958526A/en
Pending legal-status Critical Current

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    • H02J3/383—
    • 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
    • H02M1/00—Details of apparatus for conversion
    • H02M1/12—Arrangements for reducing harmonics from ac input or output
    • 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
    • H02M1/00—Details of apparatus for conversion
    • H02M1/12—Arrangements for reducing harmonics from ac input or output
    • H02M1/123—Suppression of common mode voltage or current
    • 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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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Inverter Devices (AREA)

Abstract

The present invention provides a single-phase non-isolated photovoltaic grid connected inverter. The inverter constructs a dual-direction freewheeling path composed of one power switch and four rapid-recovering diodes at the alternating current output side of a traditional full-bridge inverter to allow the large power grid to disconnect with a photovoltaic assembly in the freewheeling process of the load of the inverter so as to ensure the constant mode voltages of two ends of the alternating current output sides of the inverter and effectively inhibit the generation of the mode leakage current. The conversion efficiency is high, the investment is small, the size is small, the weight is light, and the mode leakage current is small.

Description

A kind of single-phase non-isolated photovoltaic grid-connected inverter
Technical field
Type of the present invention relates to solar energy power generating field, specifically effectively suppressing a kind of single-phase non-isolated photovoltaic grid-connected inverter of common mode leakage current.
Background technology
Photovoltaic power generation grid-connecting technology is just paid attention in China, single-phase non-isolated photovoltaic grid-connected inverter is with its low cost, the outstanding advantages such as lightweight, volume is little, conversion efficiency is high, become the focus of Recent study, be commonly applied to the photovoltaic power generation grid-connecting system of middle low power grade.But, this inverter structure does not contains high frequency or low-frequency transformer so that had electrical connection between photovoltaic module and electrical network, if do not suppressed, common mode leakage current may be made to be significantly increased, on the one hand reducing conversion efficiency, and bring electromagnetic interference problem, on the other hand can bring potential safety hazard.Therefore, suppression or the elimination problem of common mode current is the key issue that non-isolated photovoltaic grid-connected inverter have to solve.Suppression or the elimination of common mode current may have a plurality of approach, use suitable topological structure and suitable modulation technique so that common-mode voltage is constant so that it is common mode leakage current is substantially zeroed.Conventional full bridge inverter uses bipolar SPWM modulation system that common mode leakage current can be made substantially zeroed, but shortcoming limits its application such as it exists conversion efficiency is low, switching frequency is high, output voltage excursion causes greatly current ripples is big.Contrary unipolarity modulation system conversion efficiency is high, switching frequency is relatively low, the little current ripples caused of output voltage excursion is the least, simply conventional full bridge inverter uses Unipolar SPWM modulation system common-mode voltage can not keep constant, the common mode leakage current produced by its excitation but can be much larger than grid-connected standard, thus significantly limit its use.Therefore, how on the basis of keeping unipolarity modulation advantage, effectively to suppress common mode leakage current, be the focus of current academia research.
Summary of the invention
It is an object of the invention to invent a kind of single-phase non-isolated photovoltaic grid-connected inverter so that it is keep every advantage of unipolarity modulation, and common-mode voltage can be kept to reach effectively to suppress the purpose of common mode leakage current constant.
For solving the problems referred to above, the scheme of type of the present invention is:
A kind of individual event non-isolated photovoltaic grid-connected inverter, including the filter capacitor being connected to photovoltaic module two ends in turn, single-phase photovoltaic inverter circuit, alternating current filter and bulk power grid, it is characterized in that: described individual event photovoltaic inverter circuit includes full-bridge topology circuit and freewheeling path circuit, freewheeling path circuit drains with full-bridge topology circuit the first switching tube S1, second switch pipe S2 source electrode connects as the output terminals A being connected with alternating current filter, freewheeling path circuit drains with full-bridge topology circuit the 3rd switching tube S3, 4th switching tube S4 source electrode connects as the outfan B being connected with alternating current filter, freewheeling path circuit includes four fly-wheel diodes and a switching tube；
First fly-wheel diode VD1Positive pole and the 3rd fly-wheel diode VD3Negative pole connects the output terminals A as freewheeling path circuit, the second fly-wheel diode VD2Positive pole and the 4th fly-wheel diode VD4Negative pole connects the outfan B as freewheeling path circuit；
First fly-wheel diode VD1Through switching tube S5 and the 4th fly-wheel diode VD4Connect, the first fly-wheel diode VD1With the 4th fly-wheel diode VD4Polar orientation is identical；
Second fly-wheel diode VD2 is through switching tube S5 and the 3rd fly-wheel diode VD3Connect, the second fly-wheel diode VD2 and the 3rd fly-wheel diode VD3Polar orientation is identical.
Fly-wheel diode is fast recovery diode.
Beneficial effect:
Compared with prior art, the advantage of type of the present invention is:
1. during afterflow, the value of common-mode voltage is equal with photovoltaic module common-mode voltage value when bulk power grid is powered, even if the common-mode voltage that inverter circuit is in whole work process keeps constant, fundamentally inhibits the generation of common mode leakage current.
2., during afterflow, electric current is not passed through the body diode that reverse-recovery problems is serious, but flows through from special fast recovery diode, beneficially the raising of efficiency.
3. photovoltaic module is in bulk power grid power supply process, and the device that electric current flows through is few, and the switching frequency of device is relatively low, and conversion efficiency improves further.
4. ac output end change in voltage is little, the least by the networking current ripples caused by voltage pulsation.
Accompanying drawing illustrates:
The present invention is further detailed explanation with detailed description of the invention below in conjunction with the accompanying drawings:
Accompanying drawing is the structure chart of type of the present invention.
In figure, 1 is photovoltaic module, and 2 is filter capacitor, and 3 is single-phase photovoltaic inverter circuit, and 4 is alternating current filter, and 5 is electrical network, and 6 is freewheeling path circuit.
Detailed description of the invention:
Being described in further detail type of the present invention below in conjunction with the accompanying drawings and by embodiment, following example are the explanation to type of the present invention and the invention is not limited in following example.
In the present invention, a kind of single-phase non-isolated photovoltaic grid-connected inverter, including inverter circuit 3, two-way freewheeling path 6.This inverter circuit has 3 kinds of working methods: 1) S1And S4Guan Bi, S2、S3、S5Disconnect, output voltage u0=Udc, common-mode voltage uCM=Udc/2；2) S2And S3Guan Bi, S1、S4、S5Disconnect, output voltage u0=-Udc, common-mode voltage uCM=Udc/2；3) S2、S3、S1、S4All disconnection, S5Guan Bi, no matter the direction of freewheel current is to flow to B from A or flow to A from B, all has output voltage u0=0, common-mode voltage uCM=Udc/2；Therefore in all of several operation modes, common-mode voltage all keeps uCM=Udc/ 2 is constant, thus common mode leakage current is substantially zeroed.
It is described in more detail below:
Concrete control is as follows: use unipolarity modulation system, with unipolarity isosceles triangle wave as carrier wave (uC).At signal wave (ur) positive half cycle, S2、S3Disconnect always, work as ur>uCTime, S5Disconnecting, S1 and S4 closes, u0=Udc.Work as ur<uCTime, S1 and S4 disconnects, S5Guan Bi, u0=0.At signal wave (ur) negative half period, S1、S4Disconnect always, work as ur<uCTime, S5Disconnect, S2And S3Guan Bi, u0=-Udc.Work as ur>uCTime, S2And S3Disconnect, S5Guan Bi, u0=0。
The SPWM voltage waveform of this inverter ac outlet side is identical with during tradition inverter bridge unipolarity modulation system, and the positive half cycle at signal wave only has UdcWith 0 two kinds of level, the negative half period at signal wave only has-UdcWith 0 two kinds of level, and common-mode voltage is always maintained at Udc/ 2 is constant, substantially eliminates the generation of common mode leakage current.
Present disclosure is not limited to cited by embodiment, and the conversion of any equivalence that technical solution of the present invention is taked by those of ordinary skill in the art by reading description of the invention, the claim being the present invention is contained.

Claims (2)

1. an individual event non-isolated photovoltaic grid-connected inverter, including the filter capacitor (2) being connected to photovoltaic module (1) two ends in turn, single-phase photovoltaic inverter circuit (3), alternating current filter (4) and electrical network (5), it is characterized in that: described individual event photovoltaic inverter circuit includes full-bridge topology circuit and freewheeling path circuit (6), freewheeling path circuit (6) drains with full-bridge topology circuit the first switching tube S1, second switch pipe S2 source electrode connects as the output terminals A being connected with alternating current filter (4), freewheeling path circuit (6) drains with full-bridge topology circuit the 3rd switching tube S3, 4th switching tube S4 source electrode connects as the outfan B being connected with alternating current filter (4), freewheeling path circuit (6) includes four fly-wheel diodes and a switching tube；
First fly-wheel diode VD1Positive pole and the 3rd fly-wheel diode VD3Negative pole connects the output terminals A as freewheeling path circuit (6), the second fly-wheel diode VD2Positive pole and the 4th fly-wheel diode VD4Negative pole connects the outfan B as freewheeling path circuit (6)；
First fly-wheel diode VD1Through switching tube S5 and the 4th fly-wheel diode VD4Connect, the first fly-wheel diode VD1With the 4th fly-wheel diode VD4Polar orientation is identical；
Second fly-wheel diode VD2 is through switching tube S5 and the 3rd fly-wheel diode VD3Connect, the second fly-wheel diode VD2 and the 3rd fly-wheel diode VD3Polar orientation is identical.
2. according to a kind of individual event non-isolated photovoltaic grid-connected inverter described in right 1, it is characterised in that: described fly-wheel diode is fast recovery diode.
CN201610047357.4A 2016-01-25 2016-01-25 Single-phase non-isolated photovoltaic grid connected inverter Pending CN105958526A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2021103842A1 (en) * 2019-11-26 2021-06-03 湖南大学 Gating unit and efficient non-isolated three-level grid-connected inverter

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101262171A (en) * 2007-05-08 2008-09-10 韩腊生 Voltage adjusting circuit for cycle time division control power
CN102983765A (en) * 2011-09-07 2013-03-20 艾伏新能源科技(上海)股份有限公司 Efficient no-transformer single phase photovoltaic grid-connected inverter
CN202957614U (en) * 2012-12-14 2013-05-29 艾伏新能源科技(上海)股份有限公司 High-efficiency transformer-free single-phase photovoltaic grid-connected inverter

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101262171A (en) * 2007-05-08 2008-09-10 韩腊生 Voltage adjusting circuit for cycle time division control power
CN102983765A (en) * 2011-09-07 2013-03-20 艾伏新能源科技(上海)股份有限公司 Efficient no-transformer single phase photovoltaic grid-connected inverter
CN202957614U (en) * 2012-12-14 2013-05-29 艾伏新能源科技(上海)股份有限公司 High-efficiency transformer-free single-phase photovoltaic grid-connected inverter

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2021103842A1 (en) * 2019-11-26 2021-06-03 湖南大学 Gating unit and efficient non-isolated three-level grid-connected inverter

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