CN105048854A - Three-phase non-isolated grid connection converter and air-conditioning system - Google Patents
Three-phase non-isolated grid connection converter and air-conditioning system Download PDFInfo
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- CN105048854A CN105048854A CN201510431176.7A CN201510431176A CN105048854A CN 105048854 A CN105048854 A CN 105048854A CN 201510431176 A CN201510431176 A CN 201510431176A CN 105048854 A CN105048854 A CN 105048854A
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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
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- 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 invention discloses a three-phase non-isolated grid connection converter and an air-conditioning system. The three-phase non-isolated grid connection converter comprises a direct current terminal, a first alternating current terminal, a second alternating current terminal, a third alternating current terminal, a first capacitor, a second capacitor, a first inductor, a second inductor, a third inductor, a first switch and a second switch, wherein the first capacitor and the second capacitor are connected between the direct current terminal and the ground in series; the first ends of the first inductor, the second inductor and the third inductor are respectively connected to the first alternating current terminal, the second alternating current terminal and the third alternating current terminal; the second ends of the three inductors are respectively connected to a first intermediate node, a second intermediate node and a third intermediate node; the third intermediate node is the intermediate node between the first capacitor and the second capacitor; the first ends of the first switch and the first switch are respectively connected to a first node and a second node; the second ends of the switches are connected to the direct current terminal; the third ends of the switches are connected to the ground; the fourth ends of the switches are connected to a third node; and the first ends of the first switch and the second switch are selectively connected to one of the second ends, the third ends and the fourth ends. Electric energy from a power grid, solar energy and a storage battery is selectively adopted by the air-conditioning system for providing electricity to a compressor of an air conditioner.
Description
Technical field
The present invention relates to power circuit, more specifically, relate to three-phase non-isolated grid-connection converter and air-conditioning system.
Background technology
Solar energy is as a kind of important regenerative resource, and its aboundresources cleans, and is an important component part in human kind sustainable development energy strategy.Under being major premise background with environmental protection now, how the regenerative resources such as solar energy being used, being translated into electric energy or heat energy, is one of more popular research of current field of air conditioning.At present, restrict its development except improving except photoelectric conversion efficiency, develop efficient transformer configuration and utilization of power framework is feasible breach.
PV air-conditioner system utilizes photovoltaic cell to provide part or all electric energy needed for air-conditioning.Further, all right further grid-connected power supply of PV air-conditioner system, wherein adopts isolating transformer to realize the electrical energy transfer of photovoltaic cell to electrical network.Although the PV air-conditioner system of grid-connected work is the preferred version that the effective energy realizing photovoltaic cell utilizes, there is the shortcomings such as cost is high, Heavy Weight, volume are large, conversion efficiency is low in existing system.
Summary of the invention
Technical problem to be solved by this invention is to provide three-phase non-isolated grid-connection converter and air-conditioning system, adopts isolating transformer to cause the problem that system cost is high and conversion efficiency is low to solve in prior art.
According to an aspect of the present invention, provide a kind of three-phase non-isolated grid-connection converter, described converter has DC terminal and exchanges end with first to the 3rd, comprising: the first and second electric capacity, and described first and second capacitances in series are connected between described DC terminal and ground; First to the 3rd inductance, the first end of the described first to the 3rd inductance is connected to described first to the 3rd respectively and exchanges end, and the second end is connected to the first to the 3rd intermediate node respectively, and wherein the 3rd node is the intermediate node of described first and second electric capacity; And first and second switches, the first end of described first and second switches is connected to the first and second nodes respectively, second end is connected to described DC terminal, three-terminal link extremely describedly, 4th end is connected to described 3rd node, wherein, first end is optionally connected to one of second to the 4th end by described first and second switches.
Preferably, described first switch comprises: the first brachium pontis, comprises first to fourth switching tube be sequentially connected in series between described DC terminal and described ground, wherein the upper brachium pontis of the first and second switching tube compositions, the lower brachium pontis of the third and fourth switching tube composition, first and second diodes, described first and second Diode series connect, and the negative electrode of described first diode is connected to the intermediate node of described first switching tube and described second switch pipe, the anode of described second diode is connected between the intermediate node of described 3rd switching tube and described 4th switching tube, the intermediate node of described first and second diodes is connected to described 3rd node, described second switch comprises: the second brachium pontis, comprise the 5th to the 8th switching tube be sequentially connected in series between described DC terminal and described ground, the wherein upper brachium pontis of the 5th and the 6th switching tube composition, the lower brachium pontis of 7th and the 8th switching tube composition, third and fourth diode, described third and fourth Diode series connects, and the negative electrode of described 3rd diode is connected to the intermediate node of described 5th switching tube and described 6th switching tube, the anode of described 4th diode is connected between the intermediate node of described 7th switching tube and described 8th switching tube, and the intermediate node of described third and fourth diode is connected to described 3rd node.
Preferably, described first switch and described second switch are in one of following three kinds of level states in working order respectively: the first level state, the switching tube conducting of wherein said upper brachium pontis, and the switching tube of described lower brachium pontis disconnects; Second electrical level state, the switching tube of wherein said upper brachium pontis disconnects, and the switching tube conducting of described lower brachium pontis; And three level state, the switching tube conducting that wherein said upper brachium pontis is adjacent with described lower brachium pontis, rest switch pipe disconnects.
Preferably, described converter works in multiple mode of operation, and in different mode of operations, described first switch is different with the combination of the level state of described second switch.
Preferably, described converter adopts the electric energy of electrical network to provide DC bus-bar voltage in rectification mode, adopts described DC bus-bar voltage to be described electrical network feedback electric energy in inverter mode.
According to a further aspect in the invention, provide a kind of air-conditioning system, comprising: the compressor of air-conditioning, adopt DC bus-bar voltage to power, photovoltaic power supply device, converts solar energy to electric energy, to provide described DC bus-bar voltage; Battery charge and discharge device, adopts the electric energy of storage battery to provide described DC bus-bar voltage in discharge mode, adopts described DC bus-bar voltage to be described charge in batteries in charge mode; And above-mentioned converter, described compressor, described photovoltaic power supply device, described battery charge and discharge device and described converter are connected to public DC power supply terminal, and provide described DC bus-bar voltage at described DC power supply terminal, described air-conditioning system optionally adopts the electric energy from electrical network, solar energy and storage battery to be that the compressor of air-conditioning is powered.
Preferably, described air-conditioning system performs one of following flow of electrical power process: when electrical network is normal, and insufficient light, utilize solar energy and electrical network to be mixed into described compressor and described storage battery power supply; When electrical network is normal, and bright and clear or light running, solar energy is utilized to be that described compressor is powered and to described charge in batteries and feedback grid; When electrical network occurs abnormal, and insufficient light, utilize described storage battery and be solar unitedly combined into described compressor and power, or controlling described compressor and quit work; And when electrical network occurs abnormal, and bright and clear or light running, utilizes solar energy to be that described compressor is powered and is described charge in batteries, keeps the stable of described DC bus-bar voltage simultaneously.
Preferably, described photovoltaic power supply device comprises distributed multiple branch road, and each branch road comprises: photovoltaic cell component, produces the first direct voltage from solar energy; And switch DC booster circuit, the first direct voltage is increased to the second direct voltage, and carries out solar maximum power point tracking, as described DC bus-bar voltage, wherein, the output of described multiple branch road is connected to described DC power supply terminal jointly.
Preferably, the photovoltaic cell component of described multiple branch road is distributed in the diverse location of building.
Preferably, described battery charge and discharge device has the first DC terminal being connected to accumulator output end and the second DC terminal being connected to described DC power supply terminal, electric current is realized from the first DC terminal to the flowing of the second DC terminal in discharge mode, and the output voltage of storage battery is increased to described DC bus-bar voltage, in charge mode, realize electric current from the second DC terminal to the flowing of the first DC terminal, and described DC bus-bar voltage is reduced to the charging voltage of storage battery.
Preferably, described battery charge and discharge device comprises: inductance, and its first end is connected to described first DC terminal; First and second switching tubes, are connected in series between the second end of inductance and ground; Third and fourth switching tube, is connected in series between the second end of inductance and described second DC terminal; First electric capacity, is connected between described first DC terminal and ground; And second electric capacity, be connected between the intermediate node of described third and fourth switching tube and the intermediate node of described first and second switching tubes.
Preferably, described first switching tube and described second switch pipe interlock conducting and drive singal differs 180 ° of phase angles, described 3rd switching tube and described 4th switching tube interlock conducting and drive singal differs 180 ° of phase angles, simultaneously, described first switching tube and described 4th switch complementary conducting, described second switch pipe and the complementary conducting of described 3rd switching tube.
Preferably, by changing the duty ratio of described first to fourth switching tube drive singal, changing the sense of current of inductance, making described battery charge and discharge device work in one of discharge mode and charge mode.
Three-phase non-isolated grid-connection converter does not comprise transformer according to an embodiment of the invention, has that efficiency is high, volume is little, an advantage such as lightweight and cost is low.Because converter adopts three-level converter topology, thus in inverter mode, can reduce by the leakage current brought without isolating transformer and consequent network access DC component, thus the current quality of grid-connected power supply can be improved, AC harmonic voltages, electric current can be reduced in rectification mode, improve power factor and improve the dynamic response of converter.Further, bear that voltage is only DC bus-bar voltage 1/2nd of the switching tube in converter, thus the voltage stress of switching tube can be reduced, the voltage withstand class of whole converter can be improved.
Air-conditioning system comprises photovoltaic power supply device and battery charge and discharge device according to an embodiment of the invention.Described air-conditioning system optionally adopts the electric energy from electrical network, solar energy and storage battery to be that the compressor of air-conditioning is powered.Due to the use of battery charge and discharge device, this air-conditioning system can realize schedulable uninterrupted power supply, improves the dynamic response of converter, and expands power grade, greatly improves power system capacity.
In a preferred embodiment, described photovoltaic power supply device comprises distributed multiple branch road.Current photovoltaic system can be adapted to and build the various mounting meanss organically combined, also solar energy can be utilized to greatest extent, overcome the shortcoming of the system effectiveness reduction that the power mismatch between branch road causes, reduce the impact of system by single spur track fault to greatest extent simultaneously, improve stability and the flexibility of system.
In a preferred embodiment, described air-conditioning system performs different flow of electrical power processes according to system power coordination control strategy, thus efficient Dual Algorithm can be adopted to realize MPPT maximum power point tracking.
Accompanying drawing explanation
By referring to the description of accompanying drawing to the embodiment of the present invention, above-mentioned and other objects, features and advantages of the present invention will be more clear.
Fig. 1 illustrates the topology diagram of the PV air-conditioner system according to prior art.
Fig. 2 illustrates the schematic circuit of PV air-conditioner system according to an embodiment of the invention.
Fig. 3 illustrates the sequential chart of the switch controlled signal in battery charge and discharge device.
Fig. 4 illustrates the equivalent circuit diagram of the reversible transducer according to inventive embodiment.
Fig. 5 a to 5i illustrates the schematic diagram of the various mode of operations of the reversible transducer according to inventive embodiment.
Fig. 6 illustrates the common mode current path schematic diagram of non-isolation type transformer configuration.
Embodiment
In hereafter details of the present invention being described, detailedly describe some specific detail sections.Do not have the description of these detail sections can understand the present invention completely for a person skilled in the art yet.In order to avoid obscuring essence of the present invention, known method, process, flow process, element and circuit do not describe in detail.It should be understood by one skilled in the art that the accompanying drawing provided at this is all for illustrative purposes, and accompanying drawing is not necessarily drawn in proportion.Unless the context clearly requires otherwise, similar words such as " comprising ", " comprising " otherwise in whole specification and claims should be interpreted as the implication that comprises instead of exclusive or exhaustive implication; That is, be the implication of " including but not limited to ".
In describing the invention, it is to be appreciated that term " first ", " second " etc. are only for describing object, and instruction or hint relative importance can not be interpreted as.In addition, in describing the invention, except as otherwise noted, the implication of " multiple " is two or more.
Fig. 1 illustrates the topology diagram of the PV air-conditioner system according to prior art.This PV air-conditioner system comprises the compressor PMSM of air-conditioning, intelligent power module 1 and IPM2, photovoltaic cell component Upv, isolating transformer T, and the switch DC booster circuit 101 be made up of electric capacity C1, inductance L 1, diode D1 and switching tube S1.
Photovoltaic cell component Upv comprises multiple photovoltaic cells connected in series or in parallel.When wherein one piece of battery component is blocked or damages, whole photovoltaic system all can be affected, thus reduces the energy output of photovoltaic system.The electric energy that photovoltaic cell component Upv produces, after switch DC booster circuit 101 boosts, is provided to intelligent power module 1 and IPM2.
Intelligent power module 1 and IPM2 comprise the drive circuit and power switch component (such as insulated gate bipolar transistor IGBT) that integrate respectively.Intelligent power module 1 and IPM2 are used as converter within the system, convert the direct voltage of photovoltaic cell component Upv to three-phase alternating current.The alternating current that intelligent power module 1 produces is for driving the compressor PMSM of air-conditioning.The alternating current that intelligent power module 2 produces is provided to isolating transformer T, for grid-connected power supply.
Fig. 2 illustrates the schematic circuit of PV air-conditioner system according to an embodiment of the invention.This PV air-conditioner system comprises for the compressor PMSM of air-conditioning, intelligent power module, batteries Ubat, photovoltaic power supply device 201, reversible transducer 202 and battery charge and discharge device 203.
Batteries Ubat, photovoltaic power supply device 201, reversible transducer 202 and battery charge and discharge device 203 have public nodes X, provide DC bus-bar voltage.
The electric energy that solar energy produces by photovoltaic power supply device 201 is provided at least one in intelligent power module, reversible transducer 202 and battery charge and discharge device 203 with the form of direct voltage.
Intelligent power module comprises the drive circuit and power switch component (such as insulated gate bipolar transistor IGBT) that integrate.Within the system, intelligent power module is used as converter, converts the direct voltage of photovoltaic cell component to three-phase alternating current.The alternating current that intelligent power module produces is for driving the compressor PMSM of air-conditioning.
Photovoltaic power supply device 201 adopts distributed multiple branch circuit configuration mode.As shown in Figure 2, photovoltaic power supply device 201 comprises multiple photovoltaic cell component Upv1 to Upvn.Multiple photovoltaic cells that each photovoltaic cell component comprises series connection and/or is connected in parallel.Each photovoltaic cell component is connected with respective switch DC booster circuit, thus the first direct voltage of photovoltaic cell component is increased to the second direct voltage, and carries out solar maximum power point tracking while boosting.This second direct voltage is provided to nodes X, as DC bus-bar voltage.
Circuit structure and the control mode thereof of each branch road of photovoltaic power supply device 201 are identical, below only for the first branch road.
The switching current booster circuit of photovoltaic cell component Upv1 comprises electric capacity C1, inductance L 1, switching tube S1 and diode D1.Photovoltaic cell component Upv1 has output and ground, provides the first direct voltage at output.Electric capacity C1 is in parallel with photovoltaic cell component Upv1, between the output and ground being also namely connected to photovoltaic cell component Upv1.Switching tube S1 has the first current terminal, the second current terminal and control end.Such as, switching tube S1 is IGBT, and wherein the first current terminal is emitter, and the second current terminal is collector electrode, and control end is grid.The first current terminal ground connection of switching tube S1, the second current terminal is connected with the anode of diode D1.Inductance L 1 is connected between the output of photovoltaic cell component Upv1 and the second current terminal of switching tube.
At work, switching tube S1 alternate conduction and disconnection under the control of switching signal.At the turn-on cycle of switching tube S1, the electric energy charging that inductance L 1 utilizes photovoltaic cell component Upv1 to provide.At the break period of switching tube S1, inductance L 1 and photovoltaic cell component Upv1 are electric capacity Cdc1, Cdc2 and Cdc charging that hereafter will describe, and whole or one of them power supply to electrical network, storage battery and air-conditioning system.Diode D1 is used for afterflow, thus provides the second direct voltage at the cathode terminal of diode D1.
Multiple photovoltaic cell component Upv1 to Upvn of photovoltaic power supply device 201 can be distributed in the diverse location of building, such as roof, wall etc. towards sunlight side.Therefore, photovoltaic power supply device 201 can adapt to photovoltaic system and build the various mounting meanss organically combined.Each branch road of photovoltaic power supply device 201 independently carries out maximal power tracing, also solar energy can be utilized to greatest extent, overcome the shortcoming of the system effectiveness reduction that the power mismatch between branch road causes, reduce the impact of system by single spur track fault to greatest extent simultaneously, improve stability and the flexibility of system.
Reversible transducer 202 has a DC terminal and exchanges end with three.This DC terminal is to nodes X, and for providing or receiving DC bus-bar voltage, three exchange the three-phase alternating current that end is connected to electrical network.Reversible transducer 202 can convert the direct voltage of photovoltaic cell component to three-phase alternating current, for grid-connected power supply, and converts three-phase alternating current to direct voltage, for powering to air-conditioning.
Reversible transducer 202 comprises the first brachium pontis and the second brachium pontis.First brachium pontis comprises the switching tube Sa1 to Sa4 be sequentially connected in series between DC terminal and ground, and the second brachium pontis comprises the switching tube Sb1 to Sb4 be sequentially connected in series between DC terminal and ground.Switching tube Sa1 to Sa4 and Sb1 to Sb4 has the first current terminal, the second current terminal and control end respectively.Such as, all switching tubes are IGBT, and wherein the first current terminal is emitter, and the second current terminal is collector electrode, and control end is grid.
Reversible transducer 202 also comprises electric capacity Cdc1 and Cdc2, diode Da5, diode Da6, diode Db5, diode Db6 and inductance L a to Lc.Electric capacity Cdc1 and Cdc2 is connected in series between DC terminal and ground, and capacitance is identical.Diode Da5 and Da6 is connected in series between the intermediate node of switching tube Sa1 and Sa2 and the intermediate node of switching tube Sa3 and Sa4, and reverse bias.Diode Db5 and Db6 is connected in series between the intermediate node of switching tube Sb1 and Sb2 and the intermediate node of switching tube Sb3 and Sb4, and reverse bias.The intermediate node n of electric capacity Cdc1 and Cdc2 is connected to together with the intermediate node of diode Da5 with Da6 and the intermediate node of diode Db5 with Db6.The intermediate node a and first that inductance L a to Lc is connected to switching tube Sb2 and Sb3 exchanges between end, the intermediate node b and second of switching tube Sa2 and Sa3 exchanges between end and the intermediate node n of electric capacity Cdc1 and Cdc2 and the 3rd exchanges between end.
The upper brachium pontis of the first brachium pontis comprises switching tube Sa1 and Sa2 be connected between DC terminal and node b, and lower brachium pontis comprises switching tube Sa3 and Sa4 be connected between node b and ground.The upper brachium pontis of the second brachium pontis comprises switching tube Sb1 and Sb2 be connected between DC terminal and node a, and lower brachium pontis comprises switching tube Sb3 and Sb4 be connected between node a and ground.
At work, switching tube Sa1 to Sa4 and Sb1 to Sb4 is conducting and disconnection under the control of switching signal, thus can work in rectification state or inverter mode.At inverter mode, can the direct voltage of photovoltaic cell component be converted to three-phase alternating current, for grid-connected power supply.At rectification state, can the three-phase alternating current of electrical network be converted to direct voltage, for powering and batteries to store energy to air-conditioning.
Battery charge and discharge device 203 is connected with batteries Ubat, forms uninterrupted power supply (UPS).This uninterrupted power supply can also as the active power adjuster of electric network terminal, for the idle component that compensation network terminal lacks.
Batteries Ubat has output and ground.Battery charge and discharge device 203 has the first DC terminal be connected with batteries Ubat and the second DC terminal being connected to nodes X.Battery charge and discharge device 203 comprises electric capacity Cbat, Cdc and Cf, inductance L bat, switching tube Sbat1 to Sbat4.
Electric capacity Cbat is in parallel with batteries Ubat, is also namely connected between the first DC terminal and earth terminal.Inductance L bat and switching tube Sbat3, Sbat4 are sequentially connected in series between the first DC terminal and the second DC terminal.Between the intermediate node that switching tube Sbat1 and Sbat2 is connected in series in inductance L bat and switching tube Sbat3 and earth terminal.Electric capacity Cf is connected between the intermediate node of switching tube Sbat1 and Sbat2 and the intermediate node of switching tube Sbat3 and Sbat4.Electric capacity Cdc is connected between the second DC terminal and earth terminal.
Fig. 3 illustrates the sequential chart of the switch controlled signal in battery charge and discharge device.As shown in the figure, switching tube Sbat1 and Sbat2, Sbat3 and Sbat4 interlock conducting, and drive singal differs 180 ° of phase angles.Meanwhile, the complementary conducting of switching tube Sbat1 and Sbat4, Sbat2 and Sbat3.
By changing the duty ratio of switch controlled signal, the sense of current of inductance can be changed, make battery charge and discharge device 203 work in discharge mode and charge mode respectively.The charge and discharge pattern of storage battery corresponds to BUCK pattern and the BOOST pattern of two-way DC/DC converter.
At work, switching tube Sbat1 to Sbat4 conducting and disconnection under the control of switching signal.In discharge mode, the electric current in battery charge and discharge device 203 flows to the second DC terminal from the first DC terminal, and in charge mode, the electric current in battery charge and discharge device 203 flows to the first DC terminal from the second DC terminal.
The charge and discharge pattern of battery charge and discharge device 203 is changed according to system power coordination control strategy.This system power coordination control strategy steady state power model is:
P
pv+P
grid＝P
bt+P
load，
Wherein, P
pvfor the output power from photovoltaic cells, P
gridfor electrical network power output, P
btfor storage battery exports electric energy, P
loadfor the power of load consumption.Relating to load is herein air-conditioning system.
When electrical network provides electric energy, P
gridbe greater than zero, when electrical network receives electric energy, P
gridbe less than zero.In battery discharging mode, P
btbe less than zero, in battery charging mode, P
btbe greater than zero.
Flow of electrical power process is:
When electrical network is normal, and insufficient light, i.e. P
pv< P
bt+ P
load, i.e. P
grid> 0, now solar energy and electrical network are mixed into air-conditioning and storage battery power supply;
When electrical network is normal, and bright and clear or light running, i.e. P
pv> P
bt+ P
load, i.e. P
grid< 0, now system utilizes solar energy to be that described compressor is powered and to electrical network feedback electric energy;
When electrical network occurs abnormal, i.e. P
grid=0, work as insufficient light, i.e. P
pv< P
load, now P
bt< 0, namely air-conditioning system is powered by storage battery and solar association.In extreme circumstances, if be namely not enough to meet operation of air conditioner demand without storage battery electric energy while of solar energy, then air-conditioning system is shut down;
When electrical network occurs abnormal, i.e. P
grid=0, and bright and clear or light running, i.e. P
pv>P
load, now P
bt>0, system utilizes solar energy to be that described compressor is powered and for charge in batteries, keeps the stable of DC bus-bar voltage simultaneously.
Fig. 4 illustrates the equivalent circuit diagram of the reversible transducer according to inventive embodiment.First brachium pontis of reversible transducer 202 and diode Da5 and Da6 be connected thereof form the first interrupteur SW 1, second brachium pontis and diode Db5 and Db6 that be connected forms second switch SW2.
First interrupteur SW 1 and second switch SW2 are respectively SP3T switch, comprise the first end and the switchable second to the 4th end that are connected with respective interchange end respectively.
Circuit structure and the control mode thereof of the first interrupteur SW 1 and second switch SW2 are identical, below only for the first interrupteur SW 1.
At work, the switching tube of the first interrupteur SW 1 can be in different conducting states.Due to the clamping action of diode, the first interrupteur SW 1 can switch between the second to the 4th end.In two switching tube Sa1, Sa2 conductings of upper brachium pontis and another two switching tubes Sa3, Sa4 disconnect time, set condition is the 1, first switching over to the second end.In two switching tube Sa3, Sa4 conductings of lower brachium pontis and another two switching tubes Sa1, Sa2 disconnect time, set condition is that the-1, the first switching over is to the 3rd end.In switching tube Sa2, Sa3 conducting adjacent one another are of upper and lower brachium pontis and another two switching tubes Sa1, Sa4 disconnect time, set condition is that the 0, first switching over is to the 4th end.Two clamp diodes on first brachium pontis when middle two switching tube conductings for which providing current circuit.
Thus, the first interrupteur SW 1 of reversible transducer 202 and second switch SW2 have three level state respectively, i.e. state 1 ,-1 and 0.Different with it, traditional full-bridge inverting topology only has 1 and-1 two states, i.e. two level states.As mentioned below, this reversible transducer adopts three-level converter topology, can provide more mode of operation, thus realizes two-way inversion and improve transducer performance.
Fig. 5 a to 5i illustrates the schematic diagram of the various mode of operations of the reversible transducer according to inventive embodiment, wherein adopts heavy line that current circuit is shown.
As shown in Figure 5 a, in mode 1, the first interrupteur SW 1 switches to level state 1, and second switch SW2 switches to level state 1.Correspondingly, the upper brachium pontis conducting of the first brachium pontis and lower brachium pontis disconnect, and the upper brachium pontis conducting of the second brachium pontis and lower brachium pontis disconnect.Now, Van=Vbn=Udc/2, Vab=0, as shown in table 1.
As shown in Figure 5 b, in mode 2, the first interrupteur SW 1 switches to level state 0, and second switch SW2 switches to level state 1.Correspondingly, two switching tube conductings that the upper and lower brachium pontis of the first brachium pontis is adjacent and another two switching tubes disconnect, and the upper brachium pontis conducting of the second brachium pontis and lower brachium pontis disconnect.Now, Van=Vab=Udc/2, Vbn=0, as shown in table 1.
As shown in Figure 5 c, in mode 3, the first interrupteur SW 1 switches to level state-1, and second switch SW2 switches to level state 1.Correspondingly, the upper brachium pontis of the first brachium pontis disconnects and lower brachium pontis conducting, and the upper brachium pontis conducting of the second brachium pontis and lower brachium pontis disconnect.Now, Van=Udc/2, Vbn=-Udc/2, Vab=Udc, as shown in table 1.
As fig 5d, in pattern 4, the first interrupteur SW 1 switches to level state 1, and second switch SW2 switches to level state 0.Correspondingly, the upper brachium pontis conducting of the first brachium pontis and lower brachium pontis disconnect, and two switching tube conductings that the upper and lower brachium pontis of the second brachium pontis is adjacent and another two switching tubes disconnect.Now, Van=0, Vbn=Udc/2, Vbn=-Udc/2, as shown in table 1.
As depicted in fig. 5e, in mode 5, the controller, the first interrupteur SW 1 switches to level state 0, and second switch SW2 switches to level state 0.Correspondingly, two switching tube conductings that the upper and lower brachium pontis of the first brachium pontis is adjacent and another two switching tubes disconnect, and two switching tube conductings that the upper and lower brachium pontis of the second brachium pontis is adjacent and another two switching tubes disconnect.Now, Van=0, Vbn=0, Vab=0, as shown in table 1.
As shown in figure 5f, in pattern 6, the first interrupteur SW 1 switches to level state-1, and second switch SW2 switches to level state 0.Correspondingly, the upper brachium pontis of the first brachium pontis disconnects and lower brachium pontis conducting, and two switching tube conductings that the upper and lower brachium pontis of the second brachium pontis is adjacent and another two switching tubes disconnect.Now, Van=0, Vbn=-Udc/2, Vab=Udc/2, as shown in table 1.
As shown in fig. 5g, in mode 7, the first interrupteur SW 1 switches to level state 1, and second switch SW2 switches to level state-1.Correspondingly, the upper brachium pontis conducting of the first brachium pontis and lower brachium pontis disconnect, and the upper brachium pontis of the second brachium pontis disconnects and lower brachium pontis conducting.Now, Van=-Udc/2, Vbn=Udc/2, Vab=-Udc, as shown in table 1.
As shown in figure 5h, in pattern 8, the first interrupteur SW 1 switches to level state 0, and second switch SW2 switches to level state-1.Correspondingly, two switching tube conductings that the upper and lower brachium pontis of the first brachium pontis is adjacent and another two switching tubes disconnect, and the upper brachium pontis of the second brachium pontis disconnects and lower brachium pontis conducting.Now, Van=Vab=-Udc/2, Vbn=0, as shown in table 1.
As shown in figure 5i, in pattern 9, the first interrupteur SW 1 switches to level state-1, and second switch SW2 switches to level state-1.Correspondingly, the upper brachium pontis of the first brachium pontis disconnects and lower brachium pontis conducting, and the upper brachium pontis of the second brachium pontis disconnects and lower brachium pontis conducting.Now, Van=Vbn=-Udc/2, Vab=0, as shown in table 1.
The on off state of table 1 reversible transducer
By changing the duty ratio of switch controlled signal, the sense of current of inductance can be changed, make reversible transducer 202 work in rectification mode and inverter mode respectively.No matter at rectification mode or at inverter mode, the first interrupteur SW 1 of reversible transducer 202 and second switch SW2 have three level states (1,0 ,-1) respectively.Node n keeps dynamic electric voltage balance.Because the capacitance of electric capacity Cdc1 with Cdc2 is identical, electric capacity Cdc1 and Cdc2 bears Udc jointly, Vcd1=Vcd2=Udc/2.Van, Vbn have respectively 3 kinds of level Udc/2,0 ,-Udc/2, and Vab have 5 kinds of level-Udc/2 ,-Udc, 0, Udc, Udc/2.As shown in table 1, can find out that the withstand voltage of each switching tube is Udc/2, thus effectively reduce the voltage stress of each switching tube.
Non-isolation type reversible transducer structure is not containing transformer, and the advantage such as have that efficiency is high, volume is little, lightweight and cost is low is current study hotspot.
Be three-phase non-isolated reversible transducer according to the reversible transducer 202 of inventive embodiment.As shown in Figure 2, this reversible transducer 202 does not use the isolating transformer T shown in Fig. 1.Non-isolation type reversible transducer structure is not containing transformer, and the advantage such as have that efficiency is high, volume is little, lightweight and cost is low is current study hotspot.
Fig. 6 illustrates the common mode current path schematic diagram in non-isolation type transformer configuration.Non-isolation type transformer configuration comprises photovoltaic battery panel 211, converter 212 and electromagnetic interface filter 213.As shown in the figure, in inverter mode, converter 212 converts the direct voltage of photovoltaic battery panel 211 to three-phase alternating current, for grid-connected power supply.
As shown in Figure 6, non-isolation type transformer configuration causes there is electrical connection between photovoltaic battery panel 211 and electrical network.Due to the existence of photovoltaic battery panel 211 parasitic capacitance over the ground, when in non-isolation type transformer configuration, the switch motion of power device may produce high frequency, time variant voltage acts on parasitic capacitance.In the resonant tank be made up of photovoltaic battery panel 211 parasitic capacitance, straight/alternating current filter and electric network impedance etc., its impedance of consideration optimized for transducer effciency is very low, thus the common mode current i produced in this loop
cM, i.e. leakage current.
Different from the conventional transducers 212 shown in Fig. 6, adopt three-level converter topology at the reversible transducer 202 of air-conditioning system according to the present invention, thus can reduce by the leakage current i brought without isolating transformer
cMand consequent network access DC component.Meanwhile, reversible transducer 202 can realize differential output voltage as Unipolar SPWM full-bridge inverter and the advantage such as switching device voltage stress is low.The reversible transducer 202 that the present invention adopts makes up the deficiencies such as the complicated and power density of circuit structure in conventional topologies structure is low in grid-connected, rectification link.
Air-conditioning system according to an embodiment of the invention, adopt the schedulable formula grid-connected photovoltaic system comprising batteries, not only there is the effect (UPS) of uninterrupted power supply, but also the idle component of compensation network terminal shortage can be used for stable line voltage as the active power adjuster of electric network terminal, also can offset harmful higher harmonic components simultaneously, be of value to the raising quality of power supply.Adopt three-level converter topology in invention, realize Bidirectional charging-discharging and control, reduce switch tube voltage stress, reduce filter inductance, improve the dynamic response of converter.
The foregoing is only the preferred embodiments of the present invention, be not limited to the present invention, to those skilled in the art, the present invention can have various change and change.All do within spirit of the present invention and principle any amendment, equivalent replacement, improvement etc., all should be included within protection scope of the present invention.
Claims (13)
1. a three-phase non-isolated grid-connection converter, described converter has DC terminal and exchanges end with first to the 3rd, comprising:
First and second electric capacity, described first and second capacitances in series are connected between described DC terminal and ground;
First to the 3rd inductance, the first end of the described first to the 3rd inductance is connected to described first to the 3rd respectively and exchanges end, and the second end is connected to the first to the 3rd intermediate node respectively, and wherein the 3rd node is the intermediate node of described first and second electric capacity; And
First and second switches, the first end of described first and second switches is connected to the first and second nodes respectively, and the second end is connected to described DC terminal, and extremely describedly, the 4th end is connected to described 3rd node to three-terminal link,
Wherein, first end is optionally connected to one of second to the 4th end by described first and second switches.
2. converter according to claim 1, wherein, described first switch comprises:
First brachium pontis, comprises first to fourth switching tube be sequentially connected in series between described DC terminal and described ground, wherein the upper brachium pontis of the first and second switching tube compositions, the lower brachium pontis of the third and fourth switching tube composition;
First and second diodes, described first and second Diode series connect, and the negative electrode of described first diode is connected to the intermediate node of described first switching tube and described second switch pipe, the anode of described second diode is connected between the intermediate node of described 3rd switching tube and described 4th switching tube, the intermediate node of described first and second diodes is connected to described 3rd node
Described second switch comprises:
Second brachium pontis, comprises the 5th to the 8th switching tube be sequentially connected in series between described DC terminal and described ground, wherein the upper brachium pontis of the 5th and the 6th switching tube composition, the lower brachium pontis of the 7th and the 8th switching tube composition;
Third and fourth diode, described third and fourth Diode series connects, and the negative electrode of described 3rd diode is connected to the intermediate node of described 5th switching tube and described 6th switching tube, the anode of described 4th diode is connected between the intermediate node of described 7th switching tube and described 8th switching tube, and the intermediate node of described third and fourth diode is connected to described 3rd node.
3. converter according to claim 2, wherein, described first switch and described second switch are in one of following three kinds of level states in working order respectively:
First level state, the switching tube conducting of wherein said upper brachium pontis, and the switching tube of described lower brachium pontis disconnects;
Second electrical level state, the switching tube of wherein said upper brachium pontis disconnects, and the switching tube conducting of described lower brachium pontis; And
Three level state, the switching tube conducting that wherein said upper brachium pontis is adjacent with described lower brachium pontis, rest switch pipe disconnects.
4. converter according to claim 3, wherein, described converter works in multiple mode of operation, and in different mode of operations, described first switch is different with the combination of the level state of described second switch.
5. converter according to claim 1, wherein, described converter adopts the electric energy of electrical network to provide DC bus-bar voltage in rectification mode, adopts described DC bus-bar voltage to be described electrical network feedback electric energy in inverter mode.
6. an air-conditioning system, comprising:
The compressor of air-conditioning, adopts DC bus-bar voltage to power,
Photovoltaic power supply device, converts solar energy to electric energy, to provide described DC bus-bar voltage;
Battery charge and discharge device, adopts the electric energy of storage battery to provide described DC bus-bar voltage in discharge mode, adopts described DC bus-bar voltage to be described charge in batteries in charge mode; And
Converter according to any one of claim 1 to 5,
Wherein, described compressor, described photovoltaic power supply device, described battery charge and discharge device and described converter are connected to public DC power supply terminal, and provide described DC bus-bar voltage at described DC power supply terminal, described air-conditioning system optionally adopts the electric energy from electrical network, solar energy and storage battery to be that the compressor of air-conditioning is powered.
7. air-conditioning system according to claim 6, wherein, described air-conditioning system performs one of following flow of electrical power process:
When electrical network is normal, and insufficient light, utilize solar energy and electrical network to be mixed into described compressor and described storage battery power supply;
When electrical network is normal, and bright and clear or light running, solar energy is utilized to be that described compressor is powered and to described charge in batteries and feedback grid;
When electrical network occurs abnormal, and insufficient light, utilize described storage battery and be solar unitedly combined into described compressor and power, or controlling described compressor and quit work; And
When electrical network occurs abnormal, and bright and clear or light running, utilize solar energy to be that described compressor is powered and is described charge in batteries, keep the stable of described DC bus-bar voltage simultaneously.
8. air-conditioning system according to claim 6, wherein, described photovoltaic power supply device comprises distributed multiple branch road, and each branch road comprises:
Photovoltaic cell component, produces the first direct voltage from solar energy; And
Switch DC booster circuit, is increased to the second direct voltage by the first direct voltage, and carries out solar maximum power point tracking, as described DC bus-bar voltage,
Wherein, the output of described multiple branch road is connected to described DC power supply terminal jointly.
9. air-conditioning system according to claim 8, wherein, the photovoltaic cell component of described multiple branch road is distributed in the diverse location of building.
10. air-conditioning system according to claim 6, wherein, described battery charge and discharge device has the first DC terminal being connected to accumulator output end and the second DC terminal being connected to described DC power supply terminal,
Electric current is realized from the first DC terminal to the flowing of the second DC terminal in discharge mode, and the output voltage of storage battery is increased to described DC bus-bar voltage, in charge mode, realize electric current from the second DC terminal to the flowing of the first DC terminal, and described DC bus-bar voltage is reduced to the charging voltage of storage battery.
11. air-conditioning systems according to claim 10, wherein, described battery charge and discharge device comprises:
Inductance, its first end is connected to described first DC terminal;
First and second switching tubes, are connected in series between the second end of inductance and ground;
Third and fourth switching tube, is connected in series between the second end of inductance and described second DC terminal;
First electric capacity, is connected between described first DC terminal and ground; And
Second electric capacity, is connected between the intermediate node of described third and fourth switching tube and the intermediate node of described first and second switching tubes.
12. air-conditioning systems according to claim 11, wherein, described first switching tube and described second switch pipe interlock conducting and drive singal differs 180 ° of phase angles, described 3rd switching tube and described 4th switching tube interlock conducting and drive singal differs 180 ° of phase angles, simultaneously, described first switching tube and described 4th switch complementary conducting, described second switch pipe and the complementary conducting of described 3rd switching tube.
13. air-conditioning systems according to claim 12, wherein, by changing the duty ratio of described first to fourth switching tube drive singal, changing the sense of current of inductance, making described battery charge and discharge device work in one of discharge mode and charge mode.
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