CN203251237U - Three-phase four-wire type three-level photovoltaic grid-connected inverter - Google Patents

Three-phase four-wire type three-level photovoltaic grid-connected inverter Download PDF

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Publication number
CN203251237U
CN203251237U CN 201320105885 CN201320105885U CN203251237U CN 203251237 U CN203251237 U CN 203251237U CN 201320105885 CN201320105885 CN 201320105885 CN 201320105885 U CN201320105885 U CN 201320105885U CN 203251237 U CN203251237 U CN 203251237U
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CN
China
Prior art keywords
switching tube
phase
electric capacity
inverter
diode
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Expired - Fee Related
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CN 201320105885
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Chinese (zh)
Inventor
曾祥幼
宋斌
丁方亭
束林
陶国均
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ZHEJIANG WOLONG NEW ENERGY CO Ltd
Wolong Electric Drive Group Co Ltd
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ZHEJIANG WOLONG NEW ENERGY CO Ltd
Wolong Electric Group Co Ltd
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    • 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

A three-phase four-wire type three-level photovoltaic grid-connected inverter relates to an inverter. At present, the number of the elements of the inverter is large, the loss is lager relatively, and the cost is higher relatively. The three-phase four-wire type three-level photovoltaic grid-connected inverter of the utility model is characterized in that a three-level inverter circuit comprises a capacitive circuit and three phase bridge arms, three phase lines are led out from the midpoints of the three phase bridge arms respectively, and a neutral line is led out from the midpoint of the capacitive circuit; the three phase lines and the neutral line are accessed a three-phase power grid via a filtering circuit, and a first switching tube and a fourth switching tube are connected in series and then are in bridging at the two ends of a DC bus; a third switching tube and a second switching tube are arranged between the connection point of the first and fourth switching tubes and the connection point of a first capacitor and a second capacitor, and a diode of which the anode and cathode are connected, is in parallel connection between the source and the drain of each switching tube. According to the technical scheme of the utility model, the elements are few; two freewheeling diode devices are arranged on each bridge arm, so that the cost is low, the stability is good, and the efficiency is large; and the conduction loss of each bridge arm in a cycle is low.

Description

A kind of three-phase four-wire system three-level photovoltaic grid-connected inverter
Technical field
The utility model relates to a kind of circuit topological structure of inverter.
Background technology
Along with the raising of people's living standard and the technological progress of society, electric energy becomes the energy that must rely in people's daily life.Yet the primary energy such as coal, oil day by day reduces, and people also cause huge pollution to environment when using them.The basic way that solves energy problem is the regenerative resource of exploitation environment-friendly type, and wherein solar power generation is exactly wherein important developing direction.
Field of solar thermal power generation, photovoltaic combining inverter are nucleus equipments, and it realizes the direct current energy that solar panels send is reverse into during the AC energy consistent with electrical network be connected to the grid in system.It is generating equipment on the one hand, also is very important electricity consumption electric equipment in the electrical system simultaneously.For the purpose of safety, at present electric power system mostly is TN-S type electrical system, and requiring at the zero line of user's side and ground wire is two discrete lines, and the necessary reliable ground of the currentless parts such as electric equipment shell is avoided stealthy electric accident simultaneously.From the angle of electrical safety, inverter also needs to take the three-phase four-wire system mode of connection.
Three-phase inverter commonly used has two large classes on the whole at present: two level and many level (common with three level).And the two-level inversion device will realize that the three-phase four-wire system wiring has dual mode: one be three brachium pontis, draw the neutral line by bus capacitor voltage division; The 2nd, adopt the three-phase four-arm structure, multiplex two switching tubes make up the 4th brachium pontis, draw the neutral line by it, and the output of simulation neutral point voltage.First method is so that the DC bus-bar voltage utilance reduces, and multiplex two the switching tube costs of the second three level methods improve, but can improve the DC bus-bar voltage utilance and use more and more extensive.
Diode clamp formula voltage-type three-level inverter topology structure such as Fig. 1, it has following deficiency:
1. component number is more.Every phase brachium pontis has switching tube and 2 high-tension anti-paralleled diodes of 4 high power devices.Components and parts are more, and stability has much room for improvement.
2. loss is relatively large.Every have 4 switching tubes mutually, opens when turn-offing at every turn, has 2 switching tubes lossy.Each cycle internal loss stack can be larger.
3. cost is relatively high.Component number is more, and cost is larger.
The utility model content
The technical assignment of the technical problems to be solved in the utility model and proposition is that the prior art scheme is improved and improved, and provides a kind of three-phase four-wire system three-level photovoltaic grid-connected inverter, to reach the purpose that can take into account job stability, loss and cost.For this reason, the utility model is taked following technical scheme.
A kind of three-phase four-wire system three-level photovoltaic grid-connected inverter, comprise booster circuit, tri-level inversion circuit, filter circuit and controller, it is characterized in that: described tri-level inversion circuit comprises condenser network and the three-phase brachium pontis that is connected in parallel on the dc bus two ends, the mid point of every phase brachium pontis is drawn A, B, three phase lines of C, and the mid point of condenser network is drawn the neutral line; A, B, three phase lines of C and the neutral line access three phase network behind the wave circuit after filtration; Described condenser network comprises the first electric capacity, the second electric capacity, is connected across the dc bus two ends after the first electric capacity, the second capacitances in series; Described three-phase brachium pontis comprises the first switching tube, second switch pipe, the 3rd switching tube, the 4th switching tube, the first, be connected across the dc bus two ends after the series connection of the 4th switching tube, establish the 3rd switching tube, second switch pipe between the tie point of the tie point of the first switching tube and the 4th switching tube and the first electric capacity and the second electric capacity; The diode that a positive pole in parallel links to each other with drain electrode between the source electrode of each switching tube and the drain electrode.
As the further of technique scheme improved and replenish, the utility model also comprises following additional technical feature.
Described condenser network is comprised of the first electric capacity, the second electric capacity; Every phase brachium pontis of three-phase brachium pontis is by first, second, third, fourth switching tube and form with first, second, third, fourth diode of first, second, third, fourth paralleled power switches respectively; The source electrode of the first switching tube and the first capacitance cathode link to each other with dc bus is anodal, the source electrode of the source electrode of the drain electrode of the first switching tube, the 4th switching tube, the 3rd switching tube links to each other, the negative pole of the drain electrode of the 4th switching tube and the second electric capacity links to each other with the dc bus negative pole, the drain electrode of the 3rd switching tube links to each other with the drain electrode of second switch pipe, and the negative pole of the source electrode of second switch pipe, the first electric capacity, the positive pole of the second electric capacity link to each other.
Filter circuit comprises that four groups of filter branch link to each other with A, B, three phase lines of C and the neutral line respectively, and every group of filter branch comprises resistance, the inductance of connecting with resistance.
Described booster circuit comprises filter capacitor, filter inductance, the 5th switching tube, the 6th diode and the 5th diode, the two ends of filter capacitor are connected with the input source positive and negative electrode respectively, described filter inductance one end is connected with anodal, the other end is connected with the positive pole of the 6th diode, the source electrode of switching tube, the drain electrode of switching tube is connected with the input source negative pole, anodal the 5th diode that links to each other with drain electrode in parallel between the source electrode of switching tube and the drain electrode, the negative pole of the 6th diode connects the input of tri-level inversion circuit.
Beneficial effect: the technical program, components and parts are few, on each brachium pontis, establish 2 fly-wheel diode devices, and cost is low, good stability, efficient is large, and the conduction loss of each brachium pontis is low in one-period.
Description of drawings
Fig. 1 is existing inverter principle assumption diagram.
Fig. 2 is the utility model principle assumption diagram.
Fig. 3 is T-shaped topology and NPC topology efficient comparison diagram.
Among the figure: C 1The-the first electric capacity, C 2The-the second electric capacity, S 1The-the first switching tube, S 2-second switch pipe, S 3-Di three switching tubes, S 4-Di four switching tubes, S b-Di five switching tubes, D 1The-the first diode, D 2The-the second diode, D 3-Di three diodes, D 4-Di four diodes, D B0-Di five diodes, D b-Di six diodes, L b-filter inductance, C b-filter capacitor, R-resistance, L-filter inductance.
Embodiment
Below in conjunction with Figure of description the technical solution of the utility model is described in further detail.
The utility model comprises booster circuit, tri-level inversion circuit, filter circuit and controller, described tri-level inversion circuit comprises condenser network and the three-phase brachium pontis that is connected in parallel on the dc bus two ends, the mid point of every phase brachium pontis is drawn A, B, three phase lines of C, and the mid point of condenser network is drawn the neutral line; A, B, three phase lines of C and the neutral line access three phase network behind the wave circuit after filtration; Described condenser network comprises the first capacitor C 1, the second capacitor C 2, the first capacitor C 1, the second capacitor C 2Be connected across the dc bus two ends after the series connection; Described three-phase brachium pontis comprises the first switching tube S 1, second switch pipe S 2, the 3rd switching tube S 3, the 4th switching tube S 4, the first, the 4th switching tube S 1, S 4Be connected across the dc bus two ends after the series connection, the first switching tube S 1With the 4th switching tube S 4Tie point and the first capacitor C 1With the second electric capacity 4 C 2Tie point between establish the 3rd switching tube S 3, second switch pipe S 2The diode that a positive pole in parallel links to each other with drain electrode between the source electrode of each switching tube and the drain electrode.
Described condenser network is by the first capacitor C 1, the second capacitor C 2Form; Every phase brachium pontis of three-phase brachium pontis is by first, second, third, fourth switching tube S 1, S 2, S 3, S 4And respectively with first, second, third, fourth switching tube S 1, S 2, S 3, S 4First, second, third, fourth diode D in parallel 1, D 2, D 3, D 4Form; The first switching tube S 1Source electrode and the first capacitor C 1Positive pole links to each other the first switching tube S with dc bus is anodal 1Drain electrode, the 4th switching tube S 4Source electrode, the 3rd switching tube S 3Source electrode link to each other the 4th switching tube S 4Drain electrode and the second capacitor C 2Negative pole link to each other the 3rd switching tube S with the dc bus negative pole 3Drain electrode and second switch pipe S 2Drain electrode link to each other second switch pipe S 2Source electrode, the first capacitor C 1Negative pole, the second capacitor C 2Positive pole link to each other.Filter circuit comprises four groups of filter branch, and four groups of filter branch link to each other with A, B, three phase lines of C and the neutral line respectively, and every group of filter branch comprises resistance R, the inductance L of connecting with resistance R b
Described booster circuit comprises filter capacitor C b, filter inductance L b, the 5th switching tube S b, the 6th diode D bAnd the 5th diode D B0, filter capacitor C bTwo ends be connected respectively described filter inductance L with the input source positive and negative electrode bOne end is connected the other end and the 6th diode D with anodal bThe source electrode of positive pole, the 5th switching tube Sb connect the 5th switching tube S bDrain electrode be connected the 5th switching tube S with the input source negative pole bSource electrode and drain electrode between in parallel anodal and the 5th diode D that drain electrode links to each other B0, the 6th diode D bNegative pole connect the input of tri-level inversion circuit.
Controller is made of the TMS320F2812 dsp chip of TI company; be responsible for detecting solar panels both end voltage and output current; electrical network three-phase voltage and inverter output three-phase current; carry out the calculating of control algolithm and the realization of circuit protection function; generate BOOST and the pulse of Inverter drives and deliver to respectively the IGBT switching tube, the normal operation of control circuit.
Existing NPC topological structure (as shown in Figure 1) and T-shaped topological structure of the present utility model (as shown in Figure 2), take a phase brachium pontis as comparing unit, do following comparison:
1. component number
On each brachium pontis, T-shaped topology is lacked 2 fly-wheel diode device D than NPC is topological 5And D 6, each this diode cost is about 100 RMB, therefore the T-shaped cost that can economize 200 RMB than NPC.
2. loss
A. during positive Vbus power supply state,
The NPC circuital current by+Bus through S 1And S 2Power supply, its loss comprises Loss_S 1_ turnon﹠amp; Off, Loss_S 1_On and Loss_S 2_ On;
T-shaped topological circuit electric current is by+Bus warp S1Power supply, its loss comprises Loss_S 1_ turnon﹠amp; Off and Loss_S 1_ On.
Under this state, T-shapedly lack a S than NPC topology 2Conduction loss.
When b. bearing the Vbus power supply state,
The NPC circuital current is by filter inductance L bThrough S 3And S 4To-Bus, its loss comprises Loss_S 4_ turnon﹠amp; Off, Loss_S 3_ On and Loss_S 4_ On;
T-shaped topological circuit electric current is by filter inductance L bThrough S 4To-Bus, its loss comprises Loss_S 4_ turnon﹠amp; Off and Loss_S 4_ On.
Under this state, T-shapedly lack a S than NPC topology 3Conduction loss.
C. during positive Vbus afterflow state,
The NPC circuital current by filter inductance through D 1And D 2To+Bus, its loss comprises Loss_D 1_ turnon﹠amp; Turnoff﹠amp; On, Loss_D 2_ turnon﹠amp; Turnoff﹠amp; On;
T-shaped topological circuit electric current by filter inductance through D 1To+Bus, its loss comprises Loss_D 1_ turnon﹠amp; Turnoff﹠amp; On.
Under this state, T-shapedly lack a S than NPC topology 2Conduction loss.
When d. bearing Vbus afterflow state,
The NPC circuital current by-Bus through D 1And D 2To filter inductance, its loss comprises Loss_S 3_ turnon﹠amp; Turnoff﹠amp; On, Loss_S 4_ turnon﹠amp; Turnoff﹠amp; On;
T-shaped topological circuit electric current by-Bus through D 1To filter inductance, its loss comprises Loss_S 4_ turnon﹠amp; Turnoff﹠amp; On.
Under this state, T-shapedly lack a S than NPC topology 3Conduction loss.
The T-shaped topology of each brachium pontis is lacked 2 S than NPC is topological in relatively can the finding out of loss during by above-mentioned work, one-period 2And S 3Conduction loss.
3. experimental data
Two kinds of topological structure schemes are applied in respectively on the 17KT three-phase photovoltaic DC-to-AC converter, be input as the 600V direct current, Converting Unit switching tube frequency is 20KHz, output loads to 100% load from 20%, to the data of the experiment of specific efficiency as shown in Figure 3, when inverter full-load run, T-shaped topological efficient is 98%, and NPC topology efficient is 97.5%, the little nearly 90W of T-shaped topological loss ratio NPC in the time of can calculating full-load run so.
Above a kind of three-phase four-wire system three-level photovoltaic grid-connected inverter shown in Figure 2 is specific embodiment of the utility model; the utility model substantive distinguishing features and progress have been embodied; can be according to the use needs of reality; under enlightenment of the present utility model; it is carried out the equivalent modifications of the aspects such as shape, structure, all at the row of the protection range of this programme.

Claims (4)

1. three-phase four-wire system three-level photovoltaic grid-connected inverter, comprise booster circuit, tri-level inversion circuit, filter circuit and controller, it is characterized in that: described tri-level inversion circuit comprises condenser network and the three-phase brachium pontis that is connected in parallel on the dc bus two ends, the mid point of every phase brachium pontis is drawn A, B, three phase lines of C, and the mid point of condenser network is drawn the neutral line; A, B, three phase lines of C and the neutral line access three phase network behind the wave circuit after filtration; Described condenser network comprises the first electric capacity (C 1), the second electric capacity (C 2), the first electric capacity (C 1), the second electric capacity (C 2) be connected across the dc bus two ends after the series connection; Described three-phase brachium pontis comprises the first switching tube (S 1), second switch pipe (S 2), the 3rd switching tube (S 3), the 4th switching tube (S 4), the first, the 4th switching tube (S 1, S 4) be connected across the dc bus two ends, the first switching tube (S after the series connection 1) and the 4th switching tube (S 4) tie point and the first electric capacity (C 1) and the second electric capacity (C 2) tie point between establish the 3rd switching tube (S 3), second switch pipe (S 2); The diode that a positive pole in parallel links to each other with drain electrode between the source electrode of each switching tube and the drain electrode.
2. a kind of three-phase four-wire system three-level photovoltaic grid-connected inverter according to claim 1, it is characterized in that: described condenser network is by the first electric capacity (C 1), the second electric capacity (C 2) form; Every phase brachium pontis of three-phase brachium pontis is by first, second, third, fourth switching tube (S 1, S 2, S 3, S 4) and respectively with first, second, third, fourth switching tube (S 1, S 2, S 3, S 4) first, second, third, fourth diode (D in parallel 1, D 2, D 3, D 4) form; The first switching tube (S 1) source electrode and the first electric capacity (C 1) anodal link to each other the first switching tube (S with dc bus is anodal 1) drain electrode, the 4th switching tube (S 4) source electrode, the 3rd switching tube (S 3) source electrode link to each other the 4th switching tube (S 4) drain electrode and the second electric capacity (C 2) negative pole link to each other the 3rd switching tube (S with the dc bus negative pole 3) drain electrode and second switch pipe (S 2) drain electrode link to each other second switch pipe (S 2) source electrode, the negative pole of the first electric capacity (C1), the second electric capacity (C 2) positive pole link to each other.
3. a kind of three-phase four-wire system three-level photovoltaic grid-connected inverter according to claim 2, it is characterized in that: filter circuit comprises four groups of filter branch, four groups of filter branch link to each other with A, B, three phase lines of C and the neutral line respectively, and every group of filter branch comprises resistance (R), the inductance (L) of connecting with resistance (R).
4. a kind of three-phase four-wire system three-level photovoltaic grid-connected inverter according to claim 3, it is characterized in that: described booster circuit comprises filter capacitor (C b), filter inductance (L b), the 5th switching tube (S b), the 6th diode (D b) and the 5th diode (D B0), filter capacitor (C b) two ends be connected with the input source positive and negative electrode respectively; Described filter inductance (L b) end is connected the other end and the 6th diode (D with anodal b) positive pole, the 5th switching tube (S b) source electrode connect the 5th switching tube (S b) drain electrode be connected the 5th switching tube (S with the input source negative pole b) source electrode and drain electrode between in parallel anodal and the 5th diode (D that drain electrode links to each other B0), the 6th diode (D b) negative pole connect the input of tri-level inversion circuit.
CN 201320105885 2013-03-08 2013-03-08 Three-phase four-wire type three-level photovoltaic grid-connected inverter Expired - Fee Related CN203251237U (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103312210A (en) * 2013-03-08 2013-09-18 卧龙电气集团股份有限公司 Three-phase four-wire type three-level photovoltaic grid-connected inverter
CN106505894A (en) * 2016-11-01 2017-03-15 中国矿业大学 A kind of improved three level converter topologies and its modulator approach

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103312210A (en) * 2013-03-08 2013-09-18 卧龙电气集团股份有限公司 Three-phase four-wire type three-level photovoltaic grid-connected inverter
CN106505894A (en) * 2016-11-01 2017-03-15 中国矿业大学 A kind of improved three level converter topologies and its modulator approach

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Granted publication date: 20131023

Termination date: 20160308