CN104539180A - Single-phase transformer-free inverter capable of reducing system leak current - Google Patents

Single-phase transformer-free inverter capable of reducing system leak current Download PDF

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Publication number
CN104539180A
CN104539180A CN201410742616.6A CN201410742616A CN104539180A CN 104539180 A CN104539180 A CN 104539180A CN 201410742616 A CN201410742616 A CN 201410742616A CN 104539180 A CN104539180 A CN 104539180A
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CN
China
Prior art keywords
auxiliary
switching tube
main switch
current
drain electrode
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN201410742616.6A
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Chinese (zh)
Inventor
王生东
郭倩
廖志凌
游雪
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Jiangsu University
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Jiangsu University
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Publication date
Application filed by Jiangsu University filed Critical Jiangsu University
Priority to CN201410742616.6A priority Critical patent/CN104539180A/en
Publication of CN104539180A publication Critical patent/CN104539180A/en
Pending legal-status Critical Current

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Classifications

    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02MAPPARATUS 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
    • H02M7/00Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48Conversion 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
    • H02M7/53Conversion 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
    • H02M7/537Conversion 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
    • H02M7/5387Conversion 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
    • H02M7/53871Conversion 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
    • H02M7/53873Conversion 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
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02JCIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/381Dispersed generators
    • H02J3/382Dispersed generators the generators exploiting renewable energy
    • H02J3/383Solar energy, e.g. photovoltaic energy
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02MAPPARATUS 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
    • H02M1/00Details of apparatus for conversion
    • H02M1/32Means for protecting converters other than automatic disconnection
    • H02M1/34Snubber circuits
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02MAPPARATUS 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
    • H02M1/00Details of apparatus for conversion
    • H02M1/32Means for protecting converters other than automatic disconnection
    • H02M1/34Snubber circuits
    • H02M1/344Active dissipative snubbers
    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00Energy generation through renewable energy sources
    • Y02E10/50Photovoltaic [PV] energy
    • Y02E10/56Power conversion systems, e.g. maximum power point trackers

Abstract

The invention discloses a single-phase transformer-free inverter capable of reducing system leak current. A main circuit of the single-phase transformer-free inverter comprises a photovoltaic array PV, a voltage stabilization capacitor C, a main switching tube S1, a main switching tube S2, a main switching tube S3, a main switching tube S4, an auxiliary switching tube S5, an auxiliary switching tube S6, an auxiliary diode D1, an auxiliary diode D2, an output filter inductor L1, an output filter inductor L2 and a power grid vg. An auxiliary circuit composed of the auxiliary switching tube S5, the auxiliary switching tube S6, the auxiliary diode D1 and the auxiliary diode D2 is added on the basis of a single-phase full-bridge structure and used for providing a follow current channel so that the flow current stage direct-current side can be disconnected from the power grid, the changes of the common-mode voltage are restrained, and the leak current of a system is reduced; meanwhile, the output voltage waveform is the same as that of the unipolar modulation, the pulsation of output current is reduced, the size and loss of filter inductance are reduced, and the grid-connected current quality and the efficiency of the system are improved.

Description

A kind of single-phase transless structure inverter reducing system leakage current
Technical field
The present invention relates to a kind of single-phase transless photovoltaic merging inverter structure reducing system leakage current, belong to non-isolation type photovoltaic grid-connected inverting system drain current suppressing field.
Background technology
Day by day serious along with environmental pollution and problem of energy crisis, solar photovoltaic grid-connection generation technology is subject to people and more and more pays close attention to.Low cost, high efficiency, safe and reliable be the main target of photovoltaic generating system.Traditional grid-connected photovoltaic system usually adds power frequency isolation transformer at inverter and grid side and carries out electrical isolation, decrease the common mode current (being commonly referred to leakage current in photovoltaic system) between grid-connected system and ground, and transformer can also carry out the coupling of grid-connected voltage and the suppression to network access DC component, but because transformer is operated in power frequency state, so the volume of system, weight and cost increase, and efficiency reduces.
Transless combining inverter has the advantage that volume is little, cost is low, efficiency is high, but inverter and electrical network have direct electrical connection, can produce higher leakage current, thus increases the electromagnetic interference of system and the harmonic content of power network current, brings potential safety hazard.
The size of leakage current and harmonic content depend primarily on inverter topological structure and by the photovoltaic cell resonant circuit that formed of parasitic capacitance over the ground.In order to reduce the leakage current of system, some novel transless combining inverter structures are suggested, current existing mainly comprise H5 structure, band dc bypass inverter structure, band alternating current bypass inverter structure etc., the common feature of these circuit is that freewheeling period photovoltaic cell and AC network disconnect, and inhibits the generation of system common-mode leakage current.According to prior art, when adopting unipolarity modulation, electric current is only by a switching tube and an anti-paralleled diode afterflow, has that system loss is little, grid-connected current quality and a high advantage of system effectiveness, but can not suppress the generation of common mode leakage current; Bipolar modulation can suppress the generation of common mode leakage current, but each change of current of bipolar modulation has two groups of switching tubes to participate in, and add the switching loss of system, grid-connected current is of poor quality, system effectiveness is low.
Summary of the invention
For the problems referred to above, the present invention proposes a kind of transless inverter topology that can reduce system leakage current, and it improves on the basis of single-phase full-bridge inverter structure.
Concrete scheme of the present invention is as follows:
Reduce a single-phase transless structure inverter for system leakage current, comprise single-phase full-bridge inverter, also add one by auxiliary switch S 5, S 6with booster diode D 1, D 2the auxiliary circuit of composition.
Further, described single-phase full-bridge inverter comprises: photovoltaic array PV, electric capacity of voltage regulation C, main switch S 1-S 4, output inductor L 1, L 2, electrical network v g.
Further, described electric capacity of voltage regulation C is connected in parallel on photovoltaic array PV two ends, and the positive level of electric capacity of voltage regulation C meets main switch S 1, S 3drain electrode, the negative pole of electric capacity C meets main switch S 2, S 4source electrode; Auxiliary switch S 5drain electrode connect main switch S 1source class, S 5source electrode connect main switch S 2drain electrode; Auxiliary switch S 6drain electrode connect main switch S 3source class, S 6source electrode connect main switch S 4drain electrode; Booster diode D 1anode connect auxiliary switch S 5source electrode, D 1negative electrode and auxiliary switch S 6drain electrode be connected; Booster diode D 2anode connect auxiliary switch S 6source class, D 2negative electrode and auxiliary switch S 5drain electrode be connected; Output inductor L 1one end connect main switch S 1source class, the other end is connected with electrical network; Output inductor L 2one end connect main switch S 3source class, the other end is connected with electrical network.
The invention has the beneficial effects as follows: on the basis of single-phase full bridge structure, add one by auxiliary switch S 5, S 6with booster diode D 1, D 2the auxiliary circuit of composition, be used to provide afterflow passage, freewheeling period DC side and electrical network are disconnected, inhibit the change of common-mode voltage, reduce the leakage current of system, output voltage waveforms is identical with unipolarity modulation simultaneously, reduces the pulsation of output current, reduce volume and the loss of filter inductance, improve the efficiency of grid-connected current quality and system.
Accompanying drawing explanation
Fig. 1 is the single-phase transless inverter structure schematic diagram that the present invention reduces system leakage current.
Fig. 2 is the 4 kind operation modes of single-phase transless inverter in a grid cycle that the present invention reduces system leakage current, wherein:
(a) electrical network positive half period, main switch S 1, S 4operation mode during conducting;
(b) electrical network positive half period, main switch S 1, S 4operation mode during shutoff;
(c) electrical network negative half-cycle, main switch S 2, S 3operation mode during conducting;
(d) electrical network negative half-cycle, main switch S 2, S 3operation mode during shutoff.
Embodiment
Below in conjunction with accompanying drawing, the present invention is further described:
Fig. 1 is the single-phase transless inverter structure schematic diagram that the present invention reduces system leakage current.
A transless inverter topology for system leakage current can be reduced, comprising: photovoltaic array PV, electric capacity of voltage regulation C, main switch S 1-S 4, auxiliary switch S 5, S 6, booster diode D 1, D 2, output inductor L 1, L 2, electrical network v g.
Wherein, electric capacity of voltage regulation C is connected in parallel on photovoltaic array PV two ends, and the positive level of electric capacity C meets main switch S 1, S 3drain electrode, the negative pole of electric capacity C meets main switch S 2, S 4source electrode.Auxiliary switch S 5drain electrode connect main switch S 1source class, S 5source electrode connect main switch S 2drain electrode; Auxiliary switch S 6drain electrode connect main switch S 3source class, S 6source electrode connect main switch S 4drain electrode.Booster diode D 1anode connect auxiliary switch S 5source electrode, D 1negative electrode and auxiliary switch S 6drain electrode be connected; Booster diode D 2anode connect auxiliary switch S 6source class, D 2negative electrode and auxiliary switch S 5drain electrode be connected.Output inductor L 1one end connect main switch S 1source class, the other end is connected with electrical network; Output inductor L 2one end connect main switch S 3source class, the other end is connected with electrical network.
Fig. 2 is the 4 kind operation modes of single-phase transless inverter in a grid cycle that the present invention reduces system leakage current, at electrical network positive half period auxiliary switch S 6all the time open-minded, main switch S 1and S 4with the modulation of identical high-frequency pulse signal, work as S 1, S 4when opening, electric current flows to electrical network, as shown in Fig. 2 (a) from photovoltaic array PV; Work as S 1, S 4during shutoff, electric current is by auxiliary switch S 6with booster diode D 2afterflow, as shown in Fig. 2 (b).At electrical network negative half-cycle auxiliary switch S 5all the time open-minded, main switch S 2and S 3with the modulation of identical high-frequency pulse signal, work as S 2, S 3when opening, electric current flows to electrical network, as shown in Fig. 2 (c) from photovoltaic array PV; Work as S 2, S 3during shutoff, electric current is by auxiliary switch S 5with booster diode D 1afterflow, as shown in Fig. 2 (d).
The present invention adds one by switching tube S on the basis of single-phase full bridge structure 5, S 6with diode D 1, D 2the auxiliary circuit of composition, is used to provide afterflow passage, freewheeling period DC side and electrical network is disconnected, inhibits the change of common-mode voltage, reduce the leakage current of system.

Claims (3)

1. reduce a single-phase transless structure inverter for system leakage current, comprise single-phase full-bridge inverter, it is characterized in that: also add one by auxiliary switch S 5, S 6with booster diode D 1, D 2the auxiliary circuit of composition.
2. the single-phase transless structure inverter of reduction system leakage current according to claim 1, it is characterized in that, described single-phase full-bridge inverter comprises: photovoltaic array PV, electric capacity of voltage regulation C, main switch S 1-S 4, output inductor L 1, L 2, electrical network v g.
3. the single-phase transless structure inverter of the reduction system leakage current according to claim 1-2, it is characterized in that: described electric capacity of voltage regulation C is connected in parallel on photovoltaic array PV two ends, the positive level of electric capacity of voltage regulation C meets main switch S 1, S 3drain electrode, the negative pole of electric capacity C meets main switch S 2, S 4source electrode; Auxiliary switch S 5drain electrode connect main switch S 1source class, S 5source electrode connect main switch S 2drain electrode; Auxiliary switch S 6drain electrode connect main switch S 3source class, S 6source electrode connect main switch S 4drain electrode; Booster diode D 1anode connect auxiliary switch S 5source electrode, D 1negative electrode and auxiliary switch S 6drain electrode be connected; Booster diode D 2anode connect auxiliary switch S 6source class, D 2negative electrode and auxiliary switch S 5drain electrode be connected; Output inductor L 1one end connect main switch S 1source class, the other end is connected with electrical network; Output inductor L 2one end connect main switch S 3source class, the other end is connected with electrical network.
CN201410742616.6A 2014-12-08 2014-12-08 Single-phase transformer-free inverter capable of reducing system leak current Pending CN104539180A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN201410742616.6A CN104539180A (en) 2014-12-08 2014-12-08 Single-phase transformer-free inverter capable of reducing system leak current

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN201410742616.6A CN104539180A (en) 2014-12-08 2014-12-08 Single-phase transformer-free inverter capable of reducing system leak current

Publications (1)

Publication Number Publication Date
CN104539180A true CN104539180A (en) 2015-04-22

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107204719A (en) * 2017-04-11 2017-09-26 江苏大学 It is used for the inverter topology circuit and its control method for suppressing leakage current in photovoltaic parallel in system
CN109088560A (en) * 2018-09-30 2018-12-25 华南理工大学 A kind of single-phase active clamper non-isolated grid-connected inverter
CN109120178A (en) * 2018-09-30 2019-01-01 华南理工大学 A kind of novel single-phase non-isolated MOSFET gird-connected inverter

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107204719A (en) * 2017-04-11 2017-09-26 江苏大学 It is used for the inverter topology circuit and its control method for suppressing leakage current in photovoltaic parallel in system
CN107204719B (en) * 2017-04-11 2019-10-01 江苏大学 For inhibiting the inverter topology circuit and its control method of leakage current in photovoltaic parallel in system
CN109088560A (en) * 2018-09-30 2018-12-25 华南理工大学 A kind of single-phase active clamper non-isolated grid-connected inverter
CN109120178A (en) * 2018-09-30 2019-01-01 华南理工大学 A kind of novel single-phase non-isolated MOSFET gird-connected inverter

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Application publication date: 20150422