WO2020228701A1 - 一种光伏逆变器及其光伏发电系统 - Google Patents

一种光伏逆变器及其光伏发电系统 Download PDF

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Publication number
WO2020228701A1
WO2020228701A1 PCT/CN2020/089804 CN2020089804W WO2020228701A1 WO 2020228701 A1 WO2020228701 A1 WO 2020228701A1 CN 2020089804 W CN2020089804 W CN 2020089804W WO 2020228701 A1 WO2020228701 A1 WO 2020228701A1
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Prior art keywords
circuit
bus
electrically connected
bypass circuit
bypass
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PCT/CN2020/089804
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English (en)
French (fr)
Inventor
高拥兵
钱彬
周贺
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华为技术有限公司
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Application filed by 华为技术有限公司 filed Critical 华为技术有限公司
Priority to EP20804798.5A priority Critical patent/EP3893349B1/en
Publication of WO2020228701A1 publication Critical patent/WO2020228701A1/zh

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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
    • H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
    • H02H7/268—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured for dc systems
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
    • H02H3/02—Details
    • H02H3/021—Details concerning the disconnection itself, e.g. at a particular instant, particularly at zero value of current, disconnection in a predetermined order
    • H02H3/023—Details concerning the disconnection itself, e.g. at a particular instant, particularly at zero value of current, disconnection in a predetermined order by short-circuiting
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
    • H02H3/08—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess current
    • H02H3/087—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess current for dc applications
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
    • H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
    • H02H7/28—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured for meshed systems
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/001—Methods to deal with contingencies, e.g. abnormalities, faults or failures
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/381—Dispersed generators
    • H02J3/383—
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
    • H02J2300/20—The dispersed energy generation being of renewable origin
    • H02J2300/22—The renewable source being solar energy
    • H02J2300/24—The renewable source being solar energy of photovoltaic origin
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy
    • Y02E10/56—Power conversion systems, e.g. maximum power point trackers

Definitions

  • This application relates to the technical field of photovoltaic power generation, and in particular to a photovoltaic inverter and a photovoltaic power generation system thereof.
  • Photovoltaic inverters are important equipment in photovoltaic power generation systems. There are two basic structures: single-stage and two-stage.
  • the schematic diagram of a single-stage photovoltaic inverter is shown in Figure 1.
  • the one-stage DC/AC (direct current/alternating current) converter realizes the functions of maximum power point tracking and grid-connected inverter, with high system efficiency and light volume.
  • the schematic diagram of the two-stage photovoltaic inverter is shown in Figure 2 and Figure 3.
  • the front stage is a DC/DC boost circuit, and the latter stage is a DC/AC converter.
  • the front-end DC/DC boost circuit is usually composed of a BOOST boost circuit (boost converter or step-up converter, boost chopper circuit) and a bypass diode.
  • the schematic diagram is shown in Figure 4, and the BOOST boost circuit ( Figure 4 The circuit indicated by the dashed box) can help the photovoltaic inverter obtain a wider input voltage range and MPPT (Maximum Power Point Tracking) voltage
  • the DC/AC converter in the photovoltaic inverter is electrically connected to the photovoltaic components through the positive DC bus and the negative DC bus.
  • BUS bus
  • the positive DC bus and the negative DC bus fail, for example, the positive DC bus and the negative DC bus have a short-circuit fault, the positive DC bus and the negative DC bus have an overvoltage fault, and the positive DC bus and the negative DC bus have voltage imbalance faults.
  • the photovoltaic module cannot be disconnected from the photovoltaic inverter, and the energy generated by the photovoltaic module will continue to be injected into the fault point, which may cause the fault to spread further.
  • the embodiments of the present application provide a photovoltaic inverter, which can reduce the risk of further spreading of faults in the photovoltaic inverter and can reduce the cost.
  • An embodiment of the first aspect of the present application provides a photovoltaic inverter, including a DC/AC converter, a positive DC bus, a negative DC bus, a drive control circuit, and at least one first unit.
  • the first end of the positive DC bus And the first end of the negative DC bus is electrically connected to the DC/AC converter, and the first unit includes a first bypass circuit and an isolation circuit, wherein: when the first end of the isolation circuit is connected to the When the second end of the positive DC bus is electrically connected, the second end of the isolation circuit is used to electrically connect to the positive output end of the first photovoltaic module, and the second end of the negative DC bus is used to connect to the first photovoltaic module.
  • the negative output end of the photovoltaic module is electrically connected; the first end of the first bypass circuit is electrically connected to the second end of the isolation circuit, and the second end of the first bypass circuit is electrically connected to the negative DC bus The second end is electrically connected; the first end of the drive control circuit is electrically connected to the third end of the isolation circuit, and the second end of the drive control circuit is electrically connected to the third end of the first bypass circuit
  • the drive control circuit is used to control the conduction of the first terminal and the second terminal of the first bypass circuit after detecting that the positive DC bus and the negative DC bus are faulty, And it is used to control the disconnection of the first terminal and the second terminal of the isolation circuit to disconnect the first photovoltaic module from the positive DC bus, and the disconnection time of the isolation circuit is later than the first The time point when a bypass circuit is turned on; or when the first end of the isolation circuit is electrically connected to the second end of the negative DC bus, the second end of the isolation circuit is used to connect to the first photovoltaic
  • the photovoltaic inverter provided by the embodiment of the present application is provided with a drive control circuit and an isolation circuit.
  • the drive control circuit detects that the positive DC bus and the negative DC bus are faulty, the drive control circuit controls the first of the isolation circuit at this time.
  • the terminal and the second terminal are disconnected to disconnect the first photovoltaic module from the positive DC bus or the negative DC bus, so that the first photovoltaic module cannot continue to deliver energy to the fault point, which can prevent the fault point from spreading further and reduce photovoltaic inversion There is a risk of failure to spread.
  • the drive control circuit is used to detect the failure of the positive DC bus and the negative DC bus, and the drive control circuit controls the first bypass circuit to conduct so that the current flowing through the isolation circuit is less than Or equal to the preset current, and the first end and the second end of the control isolation circuit are disconnected to disconnect the first photovoltaic module from the positive DC bus, and the isolation circuit is disconnected later than the first bypass circuit is turned on Point in time.
  • the advantage of this setting is that when the first and second ends of the isolation circuit are disconnected, the current flowing through the isolation circuit is relatively low, which provides conditions for the low current disconnection of the first and second ends of the isolation circuit and avoids the isolation circuit.
  • the first bypass circuit is a normally open switch
  • the isolation circuit is a normally open breaker
  • the drive control circuit is used to control the first bypass circuit
  • the first terminal and the second terminal of the isolation circuit are controlled to conduct so that the first photovoltaic module is connected to the
  • the flow bus is connected to the negative DC bus; after the isolation circuit is turned on, the drive control circuit is also used to control the disconnection of the first end and the second end of the first bypass circuit to complete the photovoltaic inverter start up.
  • the drive control circuit inputs a pulse width modulation signal to the first bypass circuit to make the first bypass circuit intermittently conduct, so that the voltage difference between the first terminal and the second terminal of the isolation circuit is less than or equal to a preset Voltage. Thereby, it is possible to prevent a large current from appearing at the moment when the isolation circuit is directly turned on, and to prevent damage to components and lines such as PV capacitors and BUS capacitors.
  • the first unit further includes at least one second unit, and the second unit includes a second bypass circuit; when the first end of the isolation circuit is electrically connected to the second end of the positive DC bus , The first end of the second bypass circuit is electrically connected to the second end of the isolation circuit and is used to be electrically connected to the first end of the second photovoltaic module, and the second end of the second bypass circuit is electrically connected to The second end of the negative DC bus is electrically connected to the second end of the second photovoltaic module, and the second end of the drive control circuit is electrically connected to the third end of the second bypass circuit,
  • the drive control circuit is used to control the conduction of the first terminal and the second terminal of the second bypass circuit after detecting the failure of the positive DC bus and the negative DC bus, and Used to control the disconnection of the first terminal and the second terminal of the isolation circuit to disconnect the second photovoltaic module from the positive DC bus, and the disconnection of the isolation circuit is later than the second The time point when the bypass circuit is turned on; or when the first end of
  • the second end of the component is electrically connected, the second end of the drive control circuit is electrically connected to the third end of the second bypass circuit, and the drive control circuit is used to detect the positive DC bus and the negative DC After the busbar fails, the drive control circuit is used to control the first terminal and the second terminal of the second bypass circuit to conduct, and to control the first terminal and the second terminal of the isolation circuit to be disconnected.
  • the second photovoltaic module is disconnected from the negative DC bus, and the time point when the isolation circuit is disconnected is later than the time point when the second bypass circuit is turned on.
  • the first unit further includes at least one second unit
  • the second units are all used for electrically connecting with the second photovoltaic assembly, so that the photovoltaic inverter can generate relatively large power, which improves the application range of the photovoltaic inverter.
  • the second bypass circuit and the first bypass circuit are commonly connected to the same isolation circuit, so that the number of isolation circuits can be reduced, which is beneficial to reducing costs.
  • the photovoltaic inverter further includes a bus capacitor, both ends of the bus capacitor are electrically connected to the positive DC bus and the negative DC bus, and the first unit further includes a first backflow prevention switch;
  • the first end of the isolation circuit is electrically connected to the second end of the positive DC bus
  • the first end of the first backflow prevention switch is electrically connected to the second end of the positive DC bus
  • the first anti- The second end of the backflow switch is electrically connected to the first end of the isolation circuit, or the first end of the first backflow prevention switch is electrically connected to the second end of the isolation circuit and the first backflow prevention switch
  • the second end of the first bypass circuit is electrically connected to the first end of the first bypass circuit, or the first end of the first backflow prevention switch is electrically connected to the second end of the first bypass circuit and the first The second end of a backflow prevention switch is electrically connected to the second end of the negative DC bus.
  • the first backflow prevention switch is used to prevent the bus capacitor from passing through the first bypass circuit.
  • a bypass circuit is discharged; or when the first end of the isolation circuit is electrically connected to the second end of the negative DC bus, the first end of the first backflow prevention switch is connected to the second end of the positive DC bus Terminal is electrically connected and the second terminal of the first backflow prevention switch is electrically connected to the first terminal of the first bypass circuit, or the first terminal of the first backflow prevention switch is electrically connected to the first bypass circuit
  • the second end of the circuit is electrically connected and the second end of the first backflow prevention switch is electrically connected to the second end of the isolation circuit, or the first end of the first backflow prevention switch is electrically connected to the second end of the isolation circuit.
  • the first end is electrically connected and the second end of the first backflow prevention switch is electrically connected to the second end of the negative DC bus; after the first bypass circuit is turned on, the first backflow prevention switch is used Preventing the bus capacitor from discharging via the first bypass circuit.
  • the first backflow prevention switch is a diode, the first end of the first backflow prevention switch is the cathode of the diode, and the second end of the first backflow prevention switch is the anode of the diode.
  • the BUS capacitor can be prevented from discharging through the first bypass circuit; moreover, when the photovoltaic inverter includes multiple third units, when the first bypass circuit is turned on, the first backflow prevention switch It can also prevent the third photovoltaic component electrically connected to the third unit from forming a loop through the first bypass circuit, thereby preventing the risk of damage to the photovoltaic inverter due to excessive current.
  • the photovoltaic inverter further includes a bus capacitor, both ends of the bus capacitor are electrically connected to the positive DC bus and the negative DC bus, and the first unit further includes a first backflow prevention switch;
  • the first end of the isolation circuit is electrically connected to the second end of the positive DC bus
  • the first end of the first backflow prevention switch is respectively connected to the second end of the isolation circuit and the second end of the second bypass circuit.
  • One end is electrically connected and the second end of the first backflow prevention switch is electrically connected to the first end of the first bypass circuit, or the first end of the first backflow prevention switch is electrically connected to the first bypass circuit.
  • the second end of the circuit circuit is electrically connected, and the second end of the first backflow prevention switch is electrically connected to the second end of the negative DC bus and the second end of the second bypass circuit, respectively.
  • the first backflow prevention switch is used to prevent the bus capacitor and the second photovoltaic module from discharging through the first bypass circuit; or when the first end of the isolation circuit is connected to the negative
  • the first end of the first backflow prevention switch is electrically connected to the second end of the positive DC bus and the first end of the second bypass circuit
  • the first The second end of the backflow switch is electrically connected to the first end of the first bypass circuit, or the first end of the first backflow preventer is electrically connected to the second end of the first bypass circuit and the The second end of the first backflow prevention switch is electrically connected to the second end of the isolation circuit and the second end of the second bypass circuit; after the first bypass circuit is turned on, the first backflow prevention switch is used To prevent the bus capacitor and the second photo
  • the first backflow prevention switch is a diode, the first end of the first backflow prevention switch is the cathode of the diode, and the second end of the first backflow prevention switch is the anode of the diode.
  • the first backflow prevention switch can prevent the BUS capacitor from discharging through the first bypass circuit.
  • the first backflow prevention switch can also prevent the second photovoltaic module from passing through.
  • the second unit and the first bypass circuit form a current loop, resulting in excessive current and the risk of damage to the first bypass circuit.
  • the photovoltaic inverter further includes a bus capacitor, both ends of the bus capacitor are electrically connected to the positive DC bus and the negative DC bus, and the second unit further includes a second backflow prevention switch;
  • the first end of the isolation circuit is electrically connected to the second end of the positive DC bus
  • the first end of the second backflow prevention switch is respectively connected to the second end of the isolation circuit and the second end of the first bypass circuit.
  • One end is electrically connected and the second end of the second backflow prevention switch is electrically connected to the first end of the second bypass circuit, or the first end of the second backflow prevention switch is electrically connected to the second bypass circuit.
  • the second end of the circuit circuit is electrically connected, and the second end of the second backflow prevention switch is electrically connected to the second end of the negative DC bus and the second end of the first bypass circuit, respectively.
  • the second backflow prevention switch is used to prevent the bus capacitor and the first photovoltaic module from discharging through the second bypass circuit; or when the first end of the isolation circuit is connected to the negative
  • the first end of the second backflow prevention switch is electrically connected to the second end of the positive DC bus and the first end of the first bypass circuit
  • the second The second end of the backflow switch is electrically connected to the first end of the second bypass circuit, or the first end of the second backflow preventer is electrically connected to the second end of the second bypass circuit and the The second end of the second backflow preventer is electrically connected to the second end of the isolation circuit and the second end of the first bypass circuit, respectively; after the second bypass circuit is turned on, the second backflow preventer The switch is used to prevent the bus
  • the second backflow prevention switch is a diode, the first end of the second backflow prevention switch is the cathode of the diode, and the second end of the second backflow prevention switch is the anode of the diode.
  • the second backflow prevention switch can prevent the BUS capacitor from discharging through the second bypass circuit.
  • the second backflow prevention switch can also prevent the first photovoltaic module, Other second photovoltaic components, etc. form a current loop through the second bypass circuit, causing the risk of damage to the second bypass circuit due to excessive current.
  • the first bypass circuit is a switch with three terminals, and the switch is a relay, a contactor, a switch with a shunt trip winding, or a controllable semiconductor breaking device.
  • the isolation circuit is a three-terminal breaker, and the breaker is a relay, a contactor, a switch with a shunt trip winding, or a controllable semiconductor breaking device.
  • the photovoltaic inverter further includes an auxiliary source providing unit electrically connected to the drive control circuit, and the auxiliary source providing unit is used to supply power to the drive control circuit.
  • An embodiment of the second aspect of the present application provides a photovoltaic power generation system, including the above photovoltaic inverter, the photovoltaic power generation system further includes a first photovoltaic component, and the first photovoltaic component is electrically connected to the photovoltaic inverter .
  • Figure 1 is a schematic diagram of a single-stage photovoltaic inverter in the prior art
  • Figure 2 is a schematic diagram of a two-stage photovoltaic inverter in the prior art
  • Fig. 3 is a schematic diagram of another two-stage photovoltaic inverter in the prior art
  • FIG. 4 is a specific circuit diagram of the DC/DC boost circuit in Figures 2 and 3;
  • Fig. 5 is a schematic diagram of modules of a photovoltaic inverter according to the first embodiment of the present application.
  • Fig. 6 is a partial circuit diagram of the photovoltaic inverter according to the first embodiment of the present application.
  • Fig. 7 is a schematic diagram of a photovoltaic inverter according to a second embodiment of the present application.
  • Fig. 8 is a schematic diagram of a photovoltaic inverter according to a third embodiment of the present application.
  • Fig. 9 is a schematic diagram of a photovoltaic inverter according to a fourth embodiment of the present application.
  • FIG. 10 is a schematic diagram of the auxiliary source providing unit in FIG. 9;
  • Fig. 11 is a schematic diagram of a photovoltaic inverter according to a fifth embodiment of the present application.
  • Fig. 12 is a schematic diagram of a photovoltaic inverter according to a sixth embodiment of the present application.
  • Fig. 13 is a schematic diagram of a photovoltaic inverter according to a seventh embodiment of the present application.
  • Fig. 14 is a schematic diagram of a photovoltaic inverter according to an eighth embodiment of the present application.
  • FIG. 15 is a schematic diagram of a photovoltaic inverter according to a ninth embodiment of the present application.
  • Fig. 16 is a schematic diagram of one of the first units in Fig. 15;
  • Fig. 17 is a schematic diagram of a photovoltaic inverter according to a tenth embodiment of the present application.
  • Figure 18 is a schematic diagram of one of the first units in Figure 17;
  • Fig. 19 is a schematic diagram of a photovoltaic inverter according to an eleventh embodiment of the present application.
  • 110-DC/AC converter 120-positive DC bus; 121-first terminal; 122-second terminal; 130-negative DC bus; 131-first terminal; 132-second terminal; 140-drive control circuit; 141-first terminal; 142-second terminal; Cbus-bus capacitor; Dub1-first terminal; Dub2-second terminal; Cpv-PV capacitor; Dup1-first terminal; Dup2-second terminal; 150-first DC/DC boost circuit; 160-auxiliary source supply unit; 161-voltage holding circuit; 162-voltage conversion unit; 1621-positive input terminal; 1622-negative input terminal; 1623-positive output terminal; 1624-negative output terminal; Dvcc-auxiliary source diode; Cvcc-auxiliary source capacitor; Duv1-first terminal; Duv2-second terminal;
  • 200-first unit 210-first bypass circuit; 211-first terminal; 212-second terminal; 213-third terminal; 220-isolation circuit; 221-first terminal; 222-second terminal; 223 -Third terminal; 230-first photovoltaic module; 231-positive output terminal; 232-negative output terminal; 240-first backflow prevention switch; 241-first terminal; 24-second terminal;
  • 500-second unit 510-second bypass circuit; 511-first terminal; 512-second terminal; 513-third terminal; 530-second photovoltaic module; 531-positive output terminal; 532-negative output terminal ; 540-Second backflow prevention switch; 541-First terminal; 542-Second terminal.
  • the embodiment of the present application provides a photovoltaic inverter, which is applied to a photovoltaic power generation system.
  • the photovoltaic power generation system includes a first photovoltaic component and a photovoltaic inverter.
  • the first photovoltaic component includes a positive output terminal and a negative output terminal.
  • the positive output terminal and the negative output terminal of the first photovoltaic component are electrically connected to the photovoltaic inverter and connected to the photovoltaic inverter.
  • the number of the first photovoltaic module electrically connected to the inverter can be one or more.
  • the first photovoltaic module converts solar energy into direct current, and then converts direct current into alternating current through the photovoltaic inverter, and then the alternating current can be incorporated into it.
  • the power grid may be provided to the load.
  • the photovoltaic inverter is a single-stage photovoltaic inverter.
  • the photovoltaic inverter includes a DC/AC converter 110, a positive DC bus 120, a negative DC bus 130, a drive control circuit 140, and a first unit 200 .
  • the number of the first unit 200 may also be more than one, for example, two, three, four or more.
  • the right end of the two free ends of the positive DC bus 120 is the first end 121, and the left end is the second end 122. Of the two free ends of the negative DC bus 130, the right end is the first end 131, and the left end is the second end 132.
  • the first end 121 of the flow bus 120 and the first end 131 of the negative DC bus 130 are respectively electrically connected to the DC/AC converter 110, where the first end 121 of the positive DC bus 120 and the first end 131 of the negative DC bus 130 It is directly electrically connected to the DC/AC converter 110.
  • the length of the positive DC bus 120 and the length of the negative DC bus 130 may be equal or different.
  • the first unit 200 includes a first bypass circuit 210 and an isolation circuit 220.
  • the isolation circuit 220 has at least three terminals: a first terminal 221, a second terminal 222, and a third terminal 223.
  • the first bypass circuit 210 has at least three terminals: a first terminal 211, a second terminal 212, and a third terminal 213.
  • the control circuit 140 has at least two ends: a first end 141 and a second end 142.
  • the isolation circuit 220 and the third terminal 213 of the first bypass circuit 210 are control terminals, and the third terminal 223 of the isolation circuit 220 is used to control whether the first terminal 221 and the second terminal 222 of the isolation circuit 220 are conductive.
  • the third terminal 213 of the first bypass circuit 210 is used to control whether the first terminal 211 and the second terminal 212 of the first bypass circuit 210 are conductive.
  • the first end 221 of the isolation circuit 220 is electrically connected to the second end 122 of the positive DC bus 120.
  • the first end 221 of the isolation circuit 220 may be directly connected to the first end of the positive DC bus 120.
  • the two ends 122 are electrically connected, and can also be indirectly electrically connected to the second end 122 of the positive DC bus 120 through other wires;
  • the second end 222 of the isolation circuit 220 is used to electrically connect to the positive output end 231 of the first photovoltaic module 230, specifically
  • the second end 222 of the isolation circuit 220 is electrically connected to the positive output end 231 of the first photovoltaic component 230 through a wire;
  • the second end 132 of the negative DC bus 130 is used to electrically connect to the negative output end 232 of the first photovoltaic component 230,
  • the second end 132 of the negative DC bus 130 is electrically connected to the negative output end 232 of the first photovoltaic module 230 through a wire.
  • the first end 211 of the first bypass circuit 210 is electrically connected to the second end 222 of the isolation circuit 220, and the second end 212 of the first bypass circuit 210 is connected to the second end 132 of the negative DC bus 130. Electric connection.
  • the first end 141 of the drive control circuit 140 is electrically connected to the third end 223 of the isolation circuit 220, and the second end 142 of the drive control circuit 140 is electrically connected to the third end 213 of the first bypass circuit 210.
  • the drive control circuit 140 outputs signals through its first terminal 141 and second terminal 142 to control whether the first terminal 221 and the second terminal 222 of the isolation circuit 220 are turned on, and the first terminal 211 of the first bypass circuit 210 And the second terminal 212 are connected.
  • the drive control circuit 140 is used to detect whether the positive DC bus 120 and the negative DC bus 130 are faulty.
  • the DC/AC (direct current/alternating current) converter 110, the bus capacitor Cbus (see the description below) and other components fail to cause the positive DC
  • the bus 120 and the negative DC bus 130 have a fault, for example, the positive DC bus 120 and the negative DC bus 130 have a short circuit fault, the positive DC bus 120 and the negative DC bus 130 have an overvoltage fault, the positive DC bus 120 and the negative DC A voltage imbalance fault occurs on the bus 130.
  • the drive control circuit 140 is used to detect whether the positive DC bus 120 and the negative DC bus 130 are faulty. It is a conventional technology.
  • the drive control circuit 140 is connected to the positive DC bus 120 and the negative DC bus 130 to detect voltage and current. Wait for the signal to determine whether the positive DC bus 120 and the negative DC bus 130 are faulty, which will not be repeated here.
  • the drive control circuit 140 When the drive control circuit 140 detects that the positive DC bus 120 and the negative DC bus 130 are faulty, the drive control circuit 140 is used to control the first terminal 211 and the second terminal 212 of the first bypass circuit 210 to conduct.
  • the photovoltaic module 230 and the first bypass circuit 210 form an electrical loop to shunt the original current, so that the current flowing through the isolation circuit 220 is less than or equal to the preset current, which is determined by the staff according to the actual circuit conditions.
  • the preset current is 0A, 1A, 2A, 3A, etc.
  • the preset current is generally equal to 0A or relatively close to 0A.
  • the drive control circuit 140 is also used to control the first terminal 221 and the second terminal 222 of the isolation circuit 220 to be disconnected, so that the first photovoltaic module 230 electrically connected to the second terminal 222 of the isolation circuit 220 and the isolation circuit 220 The positive connection bus electrically connected to the first end 221 is disconnected. Moreover, the time point when the isolation circuit 220 is turned off is later than the time point when the first bypass circuit 210 is turned on. Due to the different response times of different components, in this embodiment, the drive control circuit 140 can simultaneously send signals to the third terminal 213 of the first bypass circuit 210 and the isolation circuit 220 through the second terminal 142 and the first terminal 141, respectively.
  • the drive control circuit 140 can also send a signal to the first bypass circuit 210 first, and then send the signal to the isolation circuit 220, or vice versa. However, regardless of the time point of signal transmission, ensure that the isolation circuit 220 The time point at which the first terminal 221 and the second terminal 222 are disconnected is later than the time point at which the first terminal 211 and the second terminal 212 of the first bypass circuit 210 are turned on.
  • the second end 222 of the isolation circuit 220 is The positive output terminal 231 of the photovoltaic module 230 is electrically connected.
  • the drive control circuit 140 When the drive control circuit 140 is used to detect that the positive DC bus 120 and the negative DC bus 130 are faulty, the drive control circuit 140 controls the first terminal 221 and the second terminal 222 of the isolation circuit 220 to be disconnected so that the first photovoltaic module 230 is connected to The positive DC bus 120 is disconnected, so that the first photovoltaic module 230 electrically connected to the second end 222 of the isolation circuit 220 cannot continue to deliver energy to the failure point, which can prevent the failure point from spreading further.
  • the drive control circuit 140 is used to detect the failure of the positive DC bus 120 and the negative DC bus 130, and the drive control circuit 140 controls the first terminals 211 and 211 of the first bypass circuit 210.
  • the second terminal 212 is turned on so that the current flowing through the first terminal 221 and the second terminal 222 of the isolation circuit 220 is less than or equal to the preset current, and the first terminal 221 and the second terminal 222 of the control isolation circuit 220 are disconnected So that the first photovoltaic module 230 is disconnected from the positive DC bus 120, and the time point when the isolation circuit 220 is disconnected is later than the time point when the first bypass circuit 210 is turned on.
  • the advantage of this arrangement is that when the first terminal 221 and the second terminal 222 of the isolation circuit 220 are disconnected, the current flowing through the isolation circuit 220 is relatively low, which is the lower of the first terminal 221 and the second terminal 222 of the isolation circuit 220.
  • Current disconnection provides conditions to avoid voltage shock or arcing when the first terminal 221 and the second terminal 222 of the isolation circuit 220 are directly disconnected; moreover, it can prevent the isolation circuit 220 from generating high voltage and damaging the isolation circuit 220 when the isolation circuit 220 is directly disconnected;
  • the first bypass circuit 210 and the isolation circuit 220 are provided. When the isolation circuit 220 is disconnected, the current flowing therethrough is relatively low, and the isolation circuit 220 has a lower requirement for large current disconnection capability and lower cost.
  • the first bypass circuit 210 is a three-terminal switch M.
  • the switch M is a normally open switch, that is, when it is not powered on.
  • the first terminal 211 and the second terminal 212 of the switch M are open.
  • the switch M may also be a normally closed switch, that is, the first terminal 211 and the second terminal 212 of the switch M are turned on and closed when the power is not applied.
  • the switch M is, for example, a relay or a contactor or a switch with a shunt trip winding or a controllable semiconductor breaking device.
  • the controllable semiconductor breaking device is, for example, a MOS tube (metal oxide semiconductor, metal oxide semiconductor field effect transistor), an IGBT (Insulated Gate Bipolar Transistor, insulated gate bipolar transistor), IGCT (Integrated Gate Commutated Thyristors, integrated gate commutated thyristors), etc.
  • MOS tube metal oxide semiconductor, metal oxide semiconductor field effect transistor
  • IGBT Insulated Gate Bipolar Transistor, insulated gate bipolar transistor
  • IGCT Integrated Gate Commutated Thyristors, integrated gate commutated thyristors
  • the isolation circuit 220 is a three-terminal breaker K, where the breaker K is a normally open breaker, that is, the first end 221 and the second end of the isolation circuit 220 are not energized. Terminal 222 is open.
  • the present application is not limited to this.
  • the breaker K may also be a normally closed breaker.
  • the breaker K is, for example, a relay, a contactor, a switch with a shunt trip winding or a controllable semiconductor breaking device.
  • the controllable semiconductor breaking device is, for example, a MOS tube, IGBT, IGCT, etc., in Figure 6, the breaker K is a relay , The relay can achieve better breaking function, lower cost, and stable breaking.
  • the third terminal 223 of the breaker K is the control terminal.
  • the photovoltaic inverter further includes a BUS (bus bar) capacitor Cbus and a PV capacitor Cpv (photovoltaic capacitor).
  • PV photovoltaics
  • the first terminal Dup1 of the PV capacitor Cpv is electrically connected to the positive output terminal 231 of the first photovoltaic module 230, the first terminal 211 of the first bypass circuit 210, and the second terminal 222 of the first isolation circuit 220, respectively.
  • the second terminal Dup2 is electrically connected to the negative output terminal 232 of the first photovoltaic component 230, the second terminal 212 of the first bypass circuit 210, and the second terminal 132 of the negative DC bus 130, respectively.
  • the first end Dub1 and the second end Dub2 of the bus capacitor Cbus are electrically connected to the positive DC bus 120 and the negative DC bus 130, respectively.
  • the first unit 200 further includes a first backflow prevention switch 240.
  • the first end 241 of the first backflow prevention switch 240 is electrically connected to the second end 222 of the isolation circuit 220, and the second end 242 of the first backflow prevention switch 240 is connected to the first end 211 of the first bypass circuit 210.
  • the electrical connection, that is, the first backflow prevention switch 240 is located between the isolation circuit 220 and the first bypass circuit 210.
  • the present application is not limited to this.
  • the first end 241 of the first backflow prevention switch 240 is electrically connected to the second end 122 of the positive DC bus 120, and the second end of the first backflow prevention switch 240 242 is electrically connected to the first end 221 of the isolation circuit 220.
  • the first end 241 of the first backflow prevention switch 240 is electrically connected to the second end 212 of the first bypass circuit 210, and the second end 242 of the first backflow prevention switch 240 is connected to the negative DC bus.
  • the second end 132 of 130 is electrically connected.
  • the first backflow prevention switch 240 prevents the bus capacitor Cbus from discharging through the first bypass circuit 210.
  • the first backflow preventer 240 is a diode
  • the first end 241 of the first backflow preventer 240 is the cathode of the diode
  • the second end 242 of the first backflow preventer 240 is the anode of the diode. Therefore, when the first bypass circuit 210 is turned on, the first backflow prevention switch 240 can prevent the bus capacitor Cbus from discharging through the first bypass circuit 210.
  • the drive control circuit 140 is, for example, a microprocessor, a control chip, etc., which will not be repeated here.
  • the positive DC bus 120 and the negative DC bus 130 are composed of wires.
  • the drive control circuit 140 controls the first terminal 211 and the second terminal 212 of the first bypass circuit 210 to conduct, and controls the isolation circuit 220 After the first terminal 221 and the second terminal 222 are disconnected to disconnect the first photovoltaic module 230 from the positive DC bus 120, the drive control circuit 140 can then further control the first terminal 211 and the second terminal of the first bypass circuit 210 212 is disconnected, so that the first photovoltaic module 230 will no longer form a loop through the first bypass circuit 210, and will no longer deliver energy to the photovoltaic inverter.
  • the drive control circuit 140 may also ignore the first bypass circuit 210, so that the drive control circuit 140 continues to control the conduction of the first terminal 211 and the second terminal 212 of the first bypass circuit 210. However, after a period of time when the drive control circuit 140 is not powered, since the first bypass circuit 210 is a normally open switch, the first bypass circuit 210 will be automatically disconnected.
  • the drive control circuit 140 when the drive control circuit 140 is continuously powered, the drive control circuit 140 can continue to control the first bypass circuit 210 to conduct, because the energy of the first photovoltaic component 230 will not be delivered to the positive DC On the bus 120 and the negative DC bus 130, the first bypass circuit 210 is still acceptable even if it is continuously turned on, and will not spread the fault at the fault point, and has a limited impact on the entire photovoltaic inverter.
  • the isolation circuit 220 is a normally open breaker, the DC/AC converter 110 will not be powered by the first photovoltaic component 230 at first.
  • the time drive control circuit 140 controls the first bypass circuit 210 so that the voltage difference between the two ends of the isolation circuit 220 is less than or equal to a preset voltage, which is set by the staff according to the actual circuit conditions, for example, the preset voltage is 40V , 30V, 20V, 10V, 0V, etc.
  • the switch M is turned on intermittently, that is, the first terminal 211 of the switch M and The second terminal 212 is turned on and off for a while.
  • PMW Pulse Width Modulation
  • the voltage of the second terminal 222 of the isolation circuit 220 can be reduced to a certain voltage value, and the photovoltaic inverter is isolated when it is just powered on.
  • the voltage of the first terminal 221 of the circuit 220 is relatively stable, for example, 0V or a certain voltage value, so that the driving control circuit 140 controls the first bypass circuit 210 to make the voltage difference between the two ends of the isolation circuit 220 less than or equal to the preset voltage .
  • the drive control circuit 140 also controls the first terminal 221 and the second terminal 222 of the isolation circuit 220 to be turned on so that the first photovoltaic module 230 is connected to the positive DC bus 120 and the negative DC bus 130, respectively, and the isolation circuit 220 is turned on.
  • the time point is later than the time point when the voltage difference between the first terminal 221 and the second terminal 222 of the isolation circuit 220 is less than or equal to the preset voltage.
  • the drive control circuit 140 controls the first bypass circuit 210
  • the first terminal 211 and the second terminal 212 are disconnected to complete the startup of the photovoltaic inverter, so that the first photovoltaic component 230 supplies power to the DC/AC converter 110.
  • This method is a soft start of the photovoltaic inverter. By setting it in this way, the problem of direct conduction of the isolation circuit 220 can be avoided. These problems are: if the first bypass circuit 210 is not provided or the first bypass circuit 210 is not controlled , And the isolation circuit 220 is directly turned on, the PV capacitor Cpv and the bus capacitor Cbus will be directly connected.
  • the PV capacitor Cpv Since the PV capacitor Cpv is generally fully charged, and the bus capacitor Cbus is not charged, a large current will be generated when the isolation circuit 220 is turned on. Since the line between the bus capacitor Cbus and the PV capacitor Cpv, the PV capacitor Cpv or the bus capacitor Cbus itself has an upper limit of withstand current, these lines or components may be damaged. However, through the soft start of the present application, the above-mentioned problem of direct conduction of the isolation circuit 220 can be solved, and components and lines such as the PV capacitor Cpv and the bus capacitor Cbus will not be damaged when the photovoltaic inverter is normally turned on.
  • the drive control circuit 140 controls the first bypass circuit 210 to turn off, so that the first photovoltaic module 230 forms a loop through the isolation circuit 220, the DC/AC converter 110 and other components to drive the control circuit 140 can control the first bypass circuit 210 to smoothly and safely disconnect.
  • FIG. 7 is a schematic diagram of a second embodiment of the present application.
  • the schematic diagram of FIG. 7 is similar to the schematic diagram of FIG. 6.
  • the main difference between this embodiment and the second embodiment is the location of the isolation circuit 220.
  • the first end 121 of the positive DC bus 120 and the first end 131 of the negative DC bus 130 are electrically connected to the DC/AC converter 110 respectively.
  • the first end 221 of the isolation circuit 220 is electrically connected to the second end 132 of the negative DC bus 130, where the first end 221 of the isolation circuit 220 may be directly electrically connected to the second end 132 of the negative DC bus 130 , It can also be indirectly electrically connected to the second end 132 of the negative DC bus 130 through other wires; the second end 222 of the isolation circuit 220 is used to electrically connect to the negative output end 232 of the first photovoltaic module 230, specifically the isolation circuit 220 The second terminal 222 is electrically connected to the negative output terminal 232 of the first photovoltaic module 230 through a wire; the second terminal 122 of the positive DC bus 120 is used to electrically connect to the positive output terminal 231 of the first photovoltaic module 230, where the positive DC The second end 122 of the bus bar 120 is electrically connected to the positive output end 231 of the first photovoltaic module 230 through a wire.
  • the first terminal 211 of the first bypass circuit 210 is electrically connected to the second terminal 122 of the positive DC bus 120, and the second terminal 212 of the first bypass circuit 210 is electrically connected to the second terminal 222 of the isolation circuit 220. Electric connection.
  • the first end 141 of the drive control circuit 140 is electrically connected to the third end 223 of the isolation circuit 220, and the second end 142 of the drive control circuit 140 is electrically connected to the third end 213 of the first bypass circuit 210.
  • the drive control circuit 140 outputs signals through its first terminal 141 and second terminal 142 to control whether the first terminal 221 and the second terminal 222 of the isolation circuit 220 are turned on, and the first terminal 211 of the first bypass circuit 210 And the second terminal 212 are connected.
  • the drive control circuit 140 detects whether the positive DC bus 120 and the negative DC bus 130 are faulty.
  • the DC/AC (direct current/alternating current) converter 110, the bus capacitor Cbus and other components fail to cause the positive DC bus 120 and the negative DC bus 130 to occur.
  • Fault such as: a short circuit fault on the positive DC bus 120 and the negative DC bus 130, an overvoltage fault on the positive DC bus 120 and the negative DC bus 130, and a voltage imbalance fault on the positive DC bus 120 and the negative DC bus 130 Wait.
  • the drive control circuit 140 When the drive control circuit 140 detects that the positive DC bus 120 and the negative DC bus 130 are faulty, the drive control circuit 140 is used to control the conduction of the first bypass circuit 210. At this time, the first photovoltaic module 230 and the first bypass circuit 210 An electrical loop is formed to promote the current flowing through the isolation circuit 220 to be less than or equal to the preset current. Further, the drive control circuit 140 is also used to control the first terminal 221 and the second terminal 222 of the isolation circuit 220 to be disconnected, so that the first photovoltaic module 230 electrically connected to the second terminal 222 of the isolation circuit 220 and the isolation circuit 220 The negative connection bus bar electrically connected to the first end is disconnected. Moreover, the time point when the isolation circuit 220 is turned off is later than the time point when the first bypass circuit 210 is turned on.
  • the second end 222 of the isolation circuit 220 is The negative output of the photovoltaic module 230 is electrically connected.
  • the drive control circuit 140 detects that the positive DC bus 120 and the negative DC bus 130 are faulty, the drive control circuit 140 controls the isolation circuit 220 to disconnect to disconnect the first photovoltaic module 230 from the negative DC bus 130, thereby isolating it from The first photovoltaic module 230 electrically connected to the second end 222 of the circuit 220 cannot continue to deliver energy to the failure point, which can prevent the failure point from spreading further.
  • the drive control circuit 140 is used to detect that the positive DC bus 120 and the negative DC bus 130 are faulty, and the drive control circuit 140 controls the first bypass circuit 210 to conduct, so that the flow The current of the isolation circuit 220 is less than or equal to the preset current, and the isolation circuit 220 is controlled to be disconnected to disconnect the first photovoltaic module 230 from the negative DC bus 130, and the time point when the isolation circuit 220 is disconnected is later than the first bypass The time point when the circuit 210 is turned on.
  • the advantage of this setting is that when the first terminal 221 and the second terminal 222 of the isolation circuit 220 are disconnected, the current flowing through the isolation circuit 220 is relatively low, which provides conditions for the low current disconnection of the isolation circuit 220 to avoid isolation.
  • a voltage shock or arc is generated; moreover, it can prevent the isolation circuit 220 from generating high voltage and damaging the isolation circuit 220 when the isolation circuit 220 is directly disconnected; this application provides the first bypass circuit 210 and the isolation circuit 220, and the isolation circuit 220
  • the current flowing through it during disconnection is relatively low, and the high-current disconnection capability of the isolation circuit 220 is relatively low, and the cost is relatively low.
  • the photovoltaic inverter further includes a BUS (bus bar) capacitor and a PV capacitor Cpv (photovoltaic capacitor). Please refer to the first embodiment for the specific connection method.
  • the first unit 200 further includes a first backflow prevention switch 240.
  • the first end 241 of the first backflow prevention switch 240 and the second end 122 of the positive DC bus 120 The second end 242 of the first backflow prevention switch 240 is electrically connected to the first end 211 of the first bypass circuit 210, that is, the first backflow prevention switch 240 is located between the bus capacitor Cbus and the first bypass circuit 210 .
  • the present application is not limited to this. In other embodiments of the present application, the first end 241 of the first backflow prevention switch 240 is electrically connected to the second end 212 of the first bypass circuit 210, and the second end of the first backflow prevention switch 240 is electrically connected.
  • the two terminals 242 are electrically connected to the second terminal 222 of the isolation circuit 220.
  • the first end 241 of the first backflow prevention switch 240 is electrically connected to the first end 221 of the isolation circuit 220, and the second end 242 of the first backflow prevention switch 240 is connected to the first end of the negative DC bus 130.
  • the two ends 132 are electrically connected. Furthermore, after the first bypass circuit 210 is turned on, the first backflow prevention switch 240 prevents the bus capacitor Cbus from discharging through the first bypass circuit 210.
  • the first backflow preventer 240 is a diode
  • the first end 241 of the first backflow preventer 240 is the cathode of the diode
  • the second end 242 of the first backflow preventer 240 is the anode of the diode. Therefore, when the first bypass circuit 210 is turned on, the first backflow prevention switch 240 can prevent the bus capacitor Cbus from discharging through the first bypass circuit 210.
  • FIG. 8 is a schematic diagram of a third embodiment of the present application.
  • the schematic diagram of FIG. 8 is similar to the schematic diagram of FIG. 6.
  • the main difference between this embodiment and the first embodiment is that the first unit 200 also includes a first DC/DC (direct current/ DC) boost circuit.
  • the photovoltaic inverter is a two-stage photovoltaic inverter.
  • the first unit also includes a first DC/DC boost circuit 150.
  • the first DC/DC boost circuit 150 By providing the first DC/DC boost circuit 150, it can help photovoltaic inverters.
  • the converter obtains a wider voltage range and MPPT voltage range.
  • the first DC/DC boost circuit 150 is a boost boost circuit, but the application is not limited to this. In other embodiments of the application, the first DC/DC boost circuit 150 may also be another boost circuit. Voltage circuit.
  • Figure 8 shows a schematic diagram of a partial implementation of a boost circuit. However, the application is not limited to this, and in other embodiments of the application, the boost circuit may also have other circuit implementation forms.
  • the first DC/DC boost circuit 150 includes a switch M, that is, the first bypass circuit 210 and the first DC/DC boost circuit 150 share the switch M in this embodiment. Since the first DC/DC boost circuit 150 is a commonly used component in a photovoltaic inverter, the embodiment of the present application provides the first bypass circuit 210 without adding a switch M, which can reduce the cost.
  • the first DC/DC boost circuit 150 further includes an inductor L. One end of the inductor L is used to electrically connect to the positive output terminal 231 of the first photovoltaic component 230.
  • the first DC/DC boost circuit 150 further includes a diode.
  • the first backflow prevention switch 240 and the first DC/DC boost circuit 150 share a diode, and no additional diode is needed.
  • the first bypass circuit 210 since the first bypass circuit 210 and the first DC/DC boost circuit 150 share the switch M, the first bypass circuit 210 does not need to add a switch M, so that a wider voltage range can be obtained. At the same time, costs can be reduced. Moreover, in this embodiment, due to the existence of the inductance L, by making the isolation circuit 220 turn off later than the first bypass circuit 210 turns on, the inductance L can be avoided when the isolation circuit 220 is directly turned off. The problem of damage to other components due to high voltage, such as breakdown of the isolation circuit 220.
  • the problem of high voltage generated by the inductance when the isolation circuit 220 is disconnected does not occur, and the requirement for the withstand voltage of the isolation circuit 220 is not high, and the cost Lower.
  • FIG. 9 is a schematic diagram of a fourth embodiment of the present application.
  • the schematic diagram of FIG. 9 is similar to the schematic diagram of FIG. 8.
  • the main difference between this embodiment and the third embodiment is that the photovoltaic inverter further includes an auxiliary source providing unit 160.
  • the photovoltaic inverter further includes an auxiliary source providing unit 160, which is electrically connected to the driving control circuit 140, and the auxiliary source providing unit 160 is used to supply power to the driving control circuit 140 so that the driving control circuit 140 normal work.
  • the auxiliary source providing unit 160 includes a voltage holding circuit 161 and a voltage conversion unit 162.
  • the voltage conversion unit 162 is located between the voltage holding circuit 161 and the driving control circuit 140.
  • the voltage holding circuit 161 is electrically connected to the positive DC bus 120 and the negative DC bus 130
  • the voltage conversion unit 162 is electrically connected to the voltage holding circuit 161
  • the drive control circuit 140 is electrically connected to the voltage conversion unit 162. connection.
  • the voltage holding circuit 161 may also be electrically connected to the positive output terminal 231 and the negative output terminal 232 of the first photovoltaic module 230 directly or in other indirect manners.
  • the voltage transmitted from the positive DC bus 120 and the negative DC bus 130 passes through the voltage holding circuit 161 to the voltage conversion unit 162, and the voltage conversion unit 162 converts to a predetermined
  • the power supply voltage is then provided to the drive control circuit 140; when the positive DC bus 120 and the negative DC bus 130 fail and the first photovoltaic module 230 cannot supply power to the voltage holding circuit 161, the voltage holding circuit 161 itself can continue to supply power for a period of time. It is transmitted to the voltage conversion unit 162, and the voltage conversion unit 162 is converted into a predetermined power supply voltage and then provided to the driving control circuit 140.
  • the voltage holding circuit 161 includes an auxiliary source diode Dvcc and an auxiliary source capacitor Cvcc.
  • the anode of the auxiliary source diode Dvcc is electrically connected to the positive DC bus 120
  • the cathode of the auxiliary source diode Dvcc is electrically connected to the first terminal Duv1 of the auxiliary source capacitor Cvcc and the positive input terminal 1621 of the voltage conversion unit 162
  • the auxiliary source capacitor Cvcc The second terminal Duv2 is electrically connected to the negative DC bus 130 and the negative input terminal 1622 of the voltage conversion unit 162, respectively.
  • the anode of the auxiliary source diode Dvcc may not be electrically connected to the positive DC bus 120, but to the first end 221 or the second end of the isolation circuit 220 or the first photovoltaic module 230.
  • the positive output terminal 231 is electrically connected
  • the second terminal Duv2 of the auxiliary source capacitor Cvcc is electrically connected to the second terminal 212 of the first bypass circuit 210 or the negative output terminal 232 of the first photovoltaic module 230
  • the second terminal Duv2 of the auxiliary source capacitor Cvcc The terminal Duv2 is also electrically connected to the negative input terminal 1622 of the voltage conversion unit 162.
  • the positive output terminal 1623 and the negative output terminal 1624 of the voltage conversion unit 162 are electrically connected to the drive control circuit 140, respectively.
  • the voltage conversion unit 162 is a conventional circuit capable of converting the magnitude of voltage, such as a BUCK circuit, a flyback circuit, etc., which will not be repeated here.
  • the auxiliary source providing unit 160 is electrically connected to the drive control circuit 140. Regardless of whether the positive DC bus 120 and the negative DC bus 130 are faulty, the auxiliary source providing unit 160 can supply power to The driving control circuit 140, the driving control circuit 140 can work normally, and the driving control circuit 140 can control the first bypass circuit 210 and the isolation circuit 220 normally.
  • the drive control circuit 140 when the drive control circuit 140 detects that the positive DC bus 120 and the negative DC bus 130 are faulty, even if the first photovoltaic component 230 cannot supply power to the voltage holding circuit 161, at this time, the fully charged auxiliary source capacitor Cvcc
  • the voltage conversion unit 162 can continue to be supplied with power, so that the drive control circuit 140 can continue to obtain power, and the drive control circuit 140 can control the first bypass circuit 210 to turn on so that the current flowing through the isolation circuit 220 is equal to or less than the preset current, And the isolation circuit 220 is controlled to be disconnected to disconnect the first photovoltaic component 230 from the positive DC bus 120, and the time point when the isolation circuit 220 is disconnected is later than the time point when the first bypass circuit 210 is turned on.
  • the drive control circuit 140 will no longer control the first bypass circuit 210 and the isolation circuit 220 because there is no power supply, because the first bypass circuit 210 is a three-terminal Normally open switch M, the isolation circuit 220 is a three-terminal normally open breaker K, so the first bypass circuit 210 will be automatically disconnected, the isolation circuit 220 will continue to remain in the disconnected state, and the first photovoltaic module 230 will not pass thereafter
  • the first bypass circuit 210 forms a loop, and this arrangement is beneficial to improve the safety of the photovoltaic inverter.
  • the auxiliary source providing unit 160 may also be a commonly used DC power source, such as a battery power source and other devices that can directly provide power.
  • the auxiliary source providing unit 160 does not need to be connected to the positive DC bus 120. It is electrically connected to the negative DC bus 130 or to the first photovoltaic component 230. At this time, the auxiliary source providing unit 160 is not powered by the first photovoltaic component 230.
  • FIG. 11 is a schematic diagram of a fifth embodiment of the present application.
  • the schematic diagram of FIG. 11 is similar to the schematic diagram of FIG. 6.
  • the main difference between this embodiment and the first embodiment is that the first unit further includes a second DC/DC boost circuit 350 .
  • the photovoltaic inverter is a two-stage photovoltaic inverter.
  • the photovoltaic inverter also includes a second DC/DC boost circuit 350.
  • the second DC/DC boost circuit 350 can help photovoltaic reverse The converter obtains a wider voltage range and MPPT voltage range.
  • the positive input terminal 351 of the second DC/DC boost circuit 350 is electrically connected to the first terminal 241 of the first backflow prevention switch 240, and the negative input terminal 352 of the second DC/DC boost circuit 350 is electrically connected to The second terminal 212 of the first bypass circuit 210 is electrically connected, the positive output terminal 353 of the second DC/DC boost circuit 350 is electrically connected to the second terminal 122 of the positive DC bus 120, and the second DC/DC boost circuit 350 The negative output terminal 354 is electrically connected to the second terminal 132 of the negative DC bus 130.
  • the second DC/DC boost circuit 350 is a conventional boost circuit, such as a boost boost circuit, etc., which will not be repeated here.
  • the second DC/DC boost circuit 350 and the first bypass circuit 210 do not share a switch, that is, the first bypass circuit 210 requires an additional switch M.
  • FIG. 12 is a schematic diagram of a sixth embodiment of the present application.
  • the schematic diagram of FIG. 12 is similar to the schematic diagram of FIG. 6.
  • the main difference between this embodiment and the first embodiment is that the first unit further includes a second DC/DC boost circuit 350 .
  • the photovoltaic inverter is a two-stage photovoltaic inverter.
  • the photovoltaic inverter also includes a second DC/DC boost circuit 350.
  • the second DC/DC boost circuit 350 can help photovoltaic reverse The converter obtains a wider voltage range and MPPT voltage range.
  • the positive input terminal 351 of the second DC/DC boost circuit 350 is used to electrically connect with the positive output terminal 231 of the first photovoltaic module 230, and the negative input terminal 352 of the second DC/DC boost circuit 350
  • the positive output terminal 353 of the second DC/DC boost circuit 350 is respectively connected with the first terminal 211 of the first bypass circuit 210 and the first backflow prevention switch 240
  • the second terminal 242 of the second DC/DC boost circuit 350 is electrically connected to the negative output terminal 354 of the first bypass circuit 210 and the second terminal 132 of the negative DC bus 130 respectively.
  • the second DC/DC boost circuit 350 is a conventional boost circuit, such as a boost boost circuit, etc., which will not be repeated here.
  • the second DC/DC boost circuit 350 and the first bypass circuit 210 do not share a switch, that is, the first bypass circuit 210 requires an additional switch M.
  • FIG. 13 is a schematic diagram of a seventh embodiment of the present application.
  • the schematic diagram of FIG. 13 is similar to the schematic diagram of FIG. 9.
  • the main difference between this embodiment and the fourth embodiment is that the photovoltaic inverter includes a plurality of first units 200.
  • the photovoltaic inverter includes a plurality of first units 200, and the number of the first units 200 is, for example, 2, 3, 4, 5, or more.
  • Each first unit 200 is used for electrical connection with the first photovoltaic module 230, wherein the first photovoltaic module 230 connected to different first units 200 is different, and each first unit 200 is also connected to the first photovoltaic module of the same positive DC bus 120.
  • the two ends 122 and the second end 132 of the same negative DC bus 130 are electrically connected, and the first end 121 of the positive DC bus 120 and the first end 131 of the negative DC bus 130 are electrically connected to the DC/AC converter 110 respectively.
  • each first unit 200 includes a first bypass circuit 210 and an isolation circuit 220.
  • first bypass circuit 210 and the isolation circuit 220 For specific connection modes of the first bypass circuit 210 and the isolation circuit 220, please refer to the first embodiment and the second embodiment. , I won’t repeat it here.
  • the first end 141 of the drive control circuit 140 is electrically connected to the third end 223 of all the isolation circuits 220, and the second end 142 of the drive control circuit 140 is electrically connected to the third end 213 of all the first bypass circuits 210. Electric connection.
  • the drive control circuit 140 is used to detect that the positive DC bus 120 and the negative DC bus 130 are faulty, the drive control circuit 140 controls all the first bypass circuits 210 to be turned on, so as to make the isolation circuit 220
  • the current is less than or equal to the preset current, and the isolation circuit 220 is controlled to disconnect so that the first photovoltaic module 230 is disconnected from the positive DC bus 120 or the negative DC bus 130, and the isolation circuit 220 is disconnected in the same first unit 200
  • the time point is later than the time point when the first bypass circuit 210 is turned on.
  • the photovoltaic inverter further includes at least one third unit 400, and the number of the third unit 400 may be 1, 2, 3, or more, for example.
  • the third unit 400 includes a photovoltaic capacitor Cpv.
  • the first terminal Dup1 of the photovoltaic capacitor Cpv is electrically connected to the second terminal 122 of the positive DC bus 120, and is also used to connect to the positive output of the third photovoltaic component 430.
  • the terminal 431 is electrically connected, and the second terminal Dup2 of the photovoltaic capacitor Cpv is electrically connected to the second terminal 132 of the negative DC bus 130 and is also used to electrically connect to the negative output terminal 432 of the third photovoltaic component 430.
  • the third unit 400 further includes a second DC/DC boost circuit 350.
  • the positive input terminal 351 of the second DC/DC boost circuit 350 is electrically connected to the first terminal Dup1 of the photovoltaic capacitor Cpv, and further Used for electrical connection with the positive output terminal 431 of the third photovoltaic assembly 430, and the negative input terminal 352 of the second DC/DC boost circuit 350 is electrically connected with the second terminal Dup2 of the photovoltaic capacitor Cpv, and is also used for electrical connection with the third photovoltaic module 430.
  • the negative output terminal 432 of the component 430 is electrically connected, the positive output terminal 353 of the second DC/DC boost circuit 350 is electrically connected to the second terminal 122 of the positive DC bus 120, and the negative output terminal of the second DC/DC boost circuit 350 354 is electrically connected to the second end 132 of the negative DC bus 130.
  • the specific circuit structure of the second DC/DC boost circuit 350 can be referred to the first DC/DC boost circuit, which will not be repeated here.
  • each first unit 200 includes a first bypass circuit 210 and an isolation circuit 220, so that when the drive control circuit 140 detects a positive DC bus When 120 and the negative DC bus 130 fail, the drive control circuit 140 controls all isolation circuits 220 to disconnect so that the first photovoltaic module 230 is disconnected from the positive DC bus 120 or the negative DC bus 130, thereby connecting to the first unit 200
  • the first photovoltaic module 230 cannot continue to deliver energy to the failure point, which reduces the energy delivered to the failure point and can prevent the failure point from spreading further.
  • the isolation circuit 220 disconnects the first photovoltaic module 230 from the positive DC bus 120 or the negative DC bus 130.
  • the advantage of this arrangement is to provide conditions for the low current disconnection of the isolation circuit 220 and avoid the isolation circuit.
  • the photovoltaic inverter includes a plurality of first units 200 and a plurality of third units 400, the first unit 200 is used for electrical connection with the first photovoltaic assembly 230, and the third unit 400 is used for The third photovoltaic component 430 is electrically connected, so that the photovoltaic inverter can generate relatively large power, which improves the application range of the photovoltaic inverter.
  • FIG. 14 is a schematic diagram of an eighth embodiment of the present application.
  • the schematic diagram of FIG. 14 is similar to the schematic diagram of FIG. 13.
  • the main difference between this embodiment and the seventh embodiment is that the photovoltaic inverter does not include the third unit 400.
  • the photovoltaic inverter in the seventh embodiment that includes multiple first units 200 and multiple third units 400
  • the photovoltaic inverter only includes multiple first units 200, The third unit 400 is not included.
  • the drive control circuit 140 when the drive control circuit 140 detects that the positive DC bus 120 and the negative DC bus 130 are faulty, the drive control circuit 140 controls all isolation circuits 220 to turn off.
  • the first photovoltaic module 230 is disconnected from the positive DC bus 120 or the negative DC bus 130, so that all the paths for the first photovoltaic module 230 to deliver energy to the fault point are cut off, and the fault point does not continue to input energy and the fault will not expand.
  • FIG. 15 is a schematic diagram of a ninth embodiment of the present application.
  • the schematic diagram of FIG. 15 is similar to the schematic diagram of FIG. 13.
  • the main difference between this embodiment and the seventh embodiment is that the first unit 200 further includes at least one second unit 500.
  • each first unit 200 includes at least one second unit 500.
  • the first unit 200 includes the number of second units 500. It is 1, 2, 3 or more.
  • the second unit 500 includes a second bypass circuit 510.
  • the first terminal 511 of the second bypass circuit 510 is electrically connected to the second terminal 222 of the isolation circuit 220 and is used to connect to the positive terminal of the second photovoltaic module 530.
  • the output terminal 531 is electrically connected, that is, the first terminal 211 of the first bypass circuit 210 and the first terminal 511 of the second bypass circuit 510 are both electrically connected to the second terminal 222 of the isolation circuit 220, and the second bypass circuit 510
  • the second end 512 of the drive control circuit 140 is electrically connected to the second end 132 of the negative DC bus 130 and is used to electrically connect to the negative output end 532 of the second photovoltaic module 530.
  • the second end 142 of the drive control circuit 140 is connected to all second bypass circuits.
  • the third end 513 of the 510 is electrically connected.
  • the drive control circuit 140 is used to control the first terminal 511 and the second terminal 511 of the first bypass circuit 210 and the second bypass circuit 510 after detecting the failure of the positive DC bus 120 and the negative DC bus 130.
  • the terminals are all turned on, and the first terminal 221 and the second terminal 222 of the isolation circuit 220 are controlled to be disconnected so that the first photovoltaic module 230, the second photovoltaic module 530 and the positive DC bus 120 are disconnected, and the same first
  • the time point when the isolation circuit 220 in the unit 200 is turned off is later than the time point when the first bypass circuit 210 and the second bypass circuit 510 are turned on.
  • the first bypass circuit 210 and the second bypass circuit 510 in the same first unit 200 are commonly connected to the same isolation circuit 220.
  • each second unit 500 includes a second bypass circuit 510, and all the second bypass circuits 510 and the first unit in the same first unit 200
  • a bypass circuit 210 is commonly connected to the same isolation circuit 220, so that the number of isolation circuits 220 can be reduced, which is beneficial to reduce costs.
  • the drive control circuit 140 when the drive control circuit 140 detects that the positive DC bus 120 and the negative DC bus 130 are faulty, the drive control circuit 140 controls the isolation circuit 220 to disconnect so that the first photovoltaic module 230, the second photovoltaic module 530 and the positive DC The bus bar 120 is disconnected, so that the first photovoltaic module 230 and the second photovoltaic module 530 cannot continue to deliver energy to the failure point, which reduces the energy delivered to the failure point and prevents the failure from spreading further.
  • the time point when the isolation circuit 220 is disconnected in the same first unit 200 is later than the time point when the second bypass circuit 510 and the first bypass circuit 210 are turned on. The advantage of this setting is the low current of the isolation circuit 220.
  • the disconnection provides conditions to avoid voltage shock or arcing when the isolation circuit 220 is disconnected, and it can prevent the isolation circuit 220 from generating high voltage when the isolation circuit 220 is directly disconnected, and damaging the isolation circuit 220.
  • This application has relatively low requirements for the voltage resistance of the isolation circuit 220.
  • the cost of the isolation circuit 220 is relatively low.
  • the second unit 500 is used to electrically connect with the second photovoltaic assembly 530, so that the photovoltaic inverter can generate relatively large power and improve The application range of photovoltaic inverters is improved.
  • the circuit structure of the second bypass circuit 510 is the same as the circuit structure of the first bypass circuit 210.
  • the circuit structure of the second bypass circuit 510 is the same as the circuit structure of the first bypass circuit 210.
  • the first end 241 of the first backflow prevention switch 240 is electrically connected to the second end 222 of the isolation circuit 220 and the first end 511 of the second bypass circuit 510, respectively, and the first backflow prevention switch 240
  • the second terminal 242 of the switch 240 is electrically connected to the first terminal 211 of the first bypass circuit 210.
  • the first end 241 of the first backflow prevention switch 240 is electrically connected to the second end 212 of the first bypass circuit 210, and the second end 242 of the first backflow prevention switch 240 is respectively connected to The second end 132 of the negative DC bus 130 and the second end 512 of the second bypass circuit 510 are electrically connected.
  • the first backflow prevention switch 240 can prevent the bus capacitor Cbus from discharging through the first bypass circuit 210, and when the first bypass circuit 210 is turned on, the first backflow prevention switch 240 can also prevent the second The photovoltaic module 530 forms a current loop through the second unit 500 and the first bypass circuit 210, causing the risk of damage to the first bypass circuit 210 due to excessive current.
  • the second unit 500 further includes a second backflow prevention switch 540.
  • the first terminal 541 of the second backflow preventer 540 is electrically connected to the second terminal 222 of the isolation circuit 220 and the first terminal 211 of the first bypass circuit 210, and the second terminal 542 of the second backflow preventer 540 is electrically connected to the second terminal 211 of the first bypass circuit 210.
  • the first end 511 of the bypass circuit 510 is electrically connected.
  • the first end 541 of the second backflow prevention switch 540 is electrically connected to the second end 512 of the second bypass circuit 510, and the second end 542 of the second backflow prevention switch 540 is respectively connected to The second end 132 of the negative DC bus 130 and the second end 212 of the first bypass circuit 210 are electrically connected.
  • the second backflow prevention switch 540 can prevent the bus capacitor Cbus from discharging via the second bypass circuit 510, and when the second bypass circuit 510 is turned on, the second backflow prevention switch 540 can also prevent the first The photovoltaic component 230 and the other second photovoltaic components 530 form a current loop through the second bypass circuit 510, causing the risk of damage to the second bypass circuit 510 due to excessive current.
  • the second backflow prevention switch 540 is the same as the first backflow prevention switch 240 and is also a diode.
  • the first end of the second backflow prevention switch 540 is the cathode of the diode, and the second end of the second backflow prevention switch 540 It is the anode of the diode.
  • the second unit 500 further includes a first DC/AC boost circuit 150.
  • FIG. 17 is a schematic diagram of a tenth embodiment of the present application.
  • the schematic diagram of FIG. 17 is similar to the schematic diagram of FIG. 15.
  • the main difference between this embodiment and the ninth embodiment is that the first terminal 221 of the isolation circuit 220 in the first unit 200 is The second end 132 of the negative DC bus 130 is electrically connected.
  • each first unit 200 includes at least one second unit 500, and the second unit 500 includes a second bypass circuit 510.
  • the first end 511 of the second bypass circuit 510 is electrically connected to the second end 122 of the positive DC bus 120 and is used to connect to the second photovoltaic module 530
  • the positive output terminal 531 is electrically connected
  • the second terminal 512 of the second bypass circuit 510 is electrically connected to the second terminal 222 of the isolation circuit 220 and is used to electrically connect to the negative output terminal 532 of the second photovoltaic module 530, that is, the first
  • the second end 212 of the bypass circuit 210 and the second end 512 of the second bypass circuit 510 are both electrically connected to the second end 222 of the isolation circuit 220, and the second end 142 of the drive control circuit 140 is electrically connected to the second bypass circuit 510.
  • the third terminal 513 is electrically connected.
  • the drive control circuit 140 is used to control the first terminal 511 and the second terminal 511 of the first bypass circuit 210 and the second bypass circuit 510 after detecting the failure of the positive DC bus 120 and the negative DC bus 130.
  • the terminals are both turned on, and the first terminal 221 and the second terminal 222 of the isolation circuit 220 are controlled to be disconnected so that the first photovoltaic module 230, the second photovoltaic module 530 and the negative DC bus 130 are disconnected, and the same first
  • the time point when the isolation circuit 220 in the unit 200 is turned off is later than the time point when the first bypass circuit 210 and the second bypass circuit 510 are turned on.
  • the first bypass circuit 210 and the second bypass circuit 510 in the same first unit 200 are commonly connected to the same isolation circuit 220.
  • each second unit 500 includes a second bypass circuit 510, and all the second bypass circuits 510 in the same first unit 200 are connected to each other.
  • the first bypass circuit 210 is commonly connected to the same isolation circuit 220, so that the number of isolation circuits 220 can be reduced, which is beneficial to reducing costs.
  • the drive control circuit 140 when the drive control circuit 140 detects that the positive DC bus 120 and the negative DC bus 130 are faulty, the drive control circuit 140 controls the isolation circuit 220 to disconnect so that the first photovoltaic component 230, the second photovoltaic component 530 and the negative DC
  • the bus bar 130 is disconnected, so that the first photovoltaic module 230 and the second photovoltaic module 530 cannot continue to deliver energy to the failure point, which reduces the energy transmitted to the failure point and prevents the failure from spreading further.
  • the time point when the isolation circuit 220 is disconnected in the same first unit 200 is later than the time point when the second bypass circuit 510 and the first bypass circuit 210 are turned on. The advantage of this setting is the low current of the isolation circuit 220.
  • the disconnection provides conditions to avoid voltage shock or arcing when the isolation circuit 220 is disconnected, and it can prevent the isolation circuit 220 from generating high voltage when the isolation circuit 220 is directly disconnected, and damaging the isolation circuit 220.
  • This application has relatively low requirements for the voltage resistance of the isolation circuit 220.
  • the cost of the isolation circuit 220 is relatively low.
  • the second unit 500 is used to electrically connect with the second photovoltaic assembly 530, so that the photovoltaic inverter can generate relatively large power and improve The application range of photovoltaic inverters is improved.
  • the first end 241 of the first backflow prevention switch 240 is electrically connected to the second end 122 of the positive DC bus 120 and the first end 511 of the second bypass circuit 510, respectively, and the first end The second terminal 242 of the return switch 240 is electrically connected to the first terminal 211 of the first bypass circuit 210.
  • the first end 241 of the first backflow prevention switch 240 is electrically connected to the second end 212 of the first bypass circuit 210, and the second end 242 of the first backflow prevention switch 240 is respectively connected to The second end 222 of the isolation circuit 220 and the second end 512 of the second bypass circuit 510 are electrically connected.
  • the first backflow prevention switch 240 can prevent the bus capacitor Cbus from discharging through the first bypass circuit 210, and when the first bypass circuit 210 is turned on, the first backflow prevention switch 240 can also prevent the second The photovoltaic module 530 forms a current loop through the second unit 500 and the first bypass circuit 210, causing the risk of damage to the first bypass circuit 210 due to excessive current.
  • the second unit 500 further includes a second backflow prevention switch 540.
  • the first end 541 of the second backflow prevention switch 540 is electrically connected to the second end 122 of the positive DC bus 120 and the first end 211 of the first bypass circuit 210, and the second end 542 of the second backflow prevention switch 540 is electrically connected to the first end 211 of the first bypass circuit 210.
  • the first ends 511 of the two bypass circuits 510 are electrically connected.
  • the first end 541 of the second backflow prevention switch 540 is electrically connected to the second end 512 of the second bypass circuit 510, and the second end 542 of the second backflow prevention switch 540 is respectively connected to The second terminal 222 of the isolation circuit 220 and the second terminal 212 of the first bypass circuit 210 are electrically connected.
  • the second backflow prevention switch 540 can prevent the bus capacitor Cbus from discharging via the second bypass circuit 510, and when the second bypass circuit 510 is turned on, the second backflow prevention switch 540 can also prevent the first The photovoltaic component 230 and the other second photovoltaic components 530 form a current loop through the second bypass circuit 510, causing the risk of damage to the second bypass circuit 510 due to excessive current.
  • the second backflow prevention switch 540 is the same as the first backflow prevention switch 240 and is also a diode.
  • the first end of the second backflow prevention switch 540 is the cathode of the diode, and the second end of the second backflow prevention switch 540 It is the anode of the diode.
  • FIG. 19 is a schematic diagram of an eleventh embodiment of the present application.
  • the schematic diagram of FIG. 19 is similar to the schematic diagram of FIG. 15.
  • the main difference between this embodiment and the ninth embodiment is that the third unit 400 is not included.
  • all photovoltaic inverters only include multiple first units 200. , Does not include the third unit 400.
  • the drive control circuit 140 when the drive control circuit 140 detects that the positive DC bus 120 and the negative DC bus 130 are faulty, the drive control circuit 140 controls all isolation circuits 220 to turn off.
  • the first photovoltaic module 230 is disconnected from the positive DC bus 120 or the negative DC bus 130, so that all the paths for the first photovoltaic module 230 to deliver energy to the fault point are cut off, and the fault point does not continue to input energy and the fault will not expand.

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Abstract

本申请提供一种光伏逆变器，包括DC/AC变换器、正直流母线、负直流母线、驱动控制电路和至少一个第一单元，所述正直流母线的第一端以及所述负直流母线的第一端分别与所述DC/AC变换器电连接，所述第一单元包括第一旁路电路、隔离电路，其中，所述驱动控制电路用于在检测到所述正直流母线和负直流母线出现故障后，所述驱动控制电路用于控制所述第一旁路电路的第一端和第二端导通，且用于控制所述隔离电路的第一端和第二端断开以使所述第一光伏组件与所述正直流母线或者负直流母线断开，且所述隔离电路断开的时间点晚于所述第一旁路电路导通的时间点。

Description

一种光伏逆变器及其光伏发电系统
本申请要求于2019年5月14日提交中国专利局、申请号为201910409600.6、申请名称为“一种光伏逆变器及其光伏发电系统”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及光伏发电技术领域，尤其涉及一种光伏逆变器及其光伏发电系统。
背景技术
光伏逆变器是光伏发电系统中的重要设备，其基本结构主要有两种：单级式和两级式。单级式光伏逆变器示意图如图1所示，由一级DC/AC(直流/交流)变换器实现最大功率点跟踪和并网逆变功能，系统效率高，体积重量轻。两级式光伏逆变器示意图如图2和图3所示，前级为DC/DC升压电路，后级为DC/AC变换器。前级DC/DC升压电路通常由BOOST升压电路(boost converter or step-up converter，升压斩波电路)和旁路二极管构成，原理图如图4所示，通过BOOST升压电路(图4中虚线框标示的电路)能够帮助光伏逆变器获得更宽的输入电压范围及MPPT(Maximum Power Point Tracking，最大功率点跟踪)电压范围。
光伏逆变器内的DC/AC变换器通过正直流母线、负直流母线与光伏组件电连接，当光伏逆变器中由于DC/AC变换器、BUS(母线)电容等元器件或者线路出现故障导致正直流母线、负直流母线发生故障时，例如正直流母线、负直流母线发生短路故障，正直流母线和负直流母线出现过压故障，正直流母线和负直流母线出现电压不均衡故障等，此时，光伏组件无法与光伏逆变器断开，光伏组件所产生的能量将持续注入故障点，进而可能导致故障进一步蔓延。
发明内容
本申请实施例提供一种光伏逆变器，可以降低光伏逆变器出现的故障进一步蔓延的风险，且可以降低成本。
本申请第一方面一实施例提供一种光伏逆变器，包括DC/AC变换器、正直流母线、负直流母线、驱动控制电路和至少一个第一单元，所述正直流母线的第一端以及所述负直流母线的第一端分别与所述DC/AC变换器电连接，所述第一单元包括第一旁路电路、隔离电路，其中：当所述隔离电路的第一端与所述正直流母线的第二端电连接时，所述隔离电路的第二端用于与第一光伏组件的正输出端电连接，所述负直流母线的第二端用于与所述第一光伏组件的负输出端电连接；所述第一旁路电路的第一端与所述隔离电路的第二端电连接，所述第一旁路电路的第二端与所述负直流母线的第二端电连接；所述驱动控制电路的第一端与所述隔离电路的第三端电连接，所述驱动控制电路的第二端与所述第一旁路电路的第三端电连接，所述驱动控制电路用于在检测到所述正直流母线和负直流母线出现故障后，所述驱动控制电路用于控制所述第一旁路电路的第一端和第二端导通，且用于控制所 述隔离电路的第一端和第二端断开以使所述第一光伏组件与所述正直流母线断开，且所述隔离电路断开的时间点晚于所述第一旁路电路导通的时间点；或当所述隔离电路的第一端与所述负直流母线的第二端电连接时，所述隔离电路的第二端用于与所述第一光伏组件的负输出端电连接，所述正直流母线的第二端用于与所述第一光伏组件的正输出端电连接；所述第一旁路电路的第一端与所述正直流母线的第二端电连接，所述第一旁路电路的第二端与所述隔离电路的第二端电连接；所述驱动控制电路的第一端与所述隔离电路的第三端电连接，所述驱动控制电路的第二端与所述第一旁路电路的第三端电连接，所述驱动控制电路用于在检测到所述正直流母线和负直流母线出现故障后，所述驱动控制电路用于控制所述第一旁路电路的第一端和第二端导通，且用于控制所述隔离电路的第一端和第二端断开以使所述第一光伏组件与所述负直流母线断开，且所述隔离电路断开的时间点晚于所述第一旁路电路导通的时间点。
本申请实施例提供的光伏逆变器，通过设置驱动控制电路和隔离电路，当驱动控制电路检测到正直流母线和负直流母线出现故障时，此时驱动控制电路控制所述隔离电路的第一端和第二端断开以使第一光伏组件与所述正直流母线或者负直流母线断开，从而第一光伏组件不能继续输送能量到故障点，可以防止故障点进一步蔓延，降低光伏逆变器出现故障扩散的风险。而且，通过还设置第一旁路电路，驱动控制电路用于检测到正直流母线和负直流母线出现故障后，驱动控制电路控制第一旁路电路导通，以使流过隔离电路的电流小于或等于预设电流，且控制隔离电路的第一端和第二端断开以使第一光伏组件与正直流母线断开，且隔离电路断开的时间点晚于第一旁路电路导通的时间点。这样设置的好处是：隔离电路的第一端和第二端断开时此时流过隔离电路的电流比较低，为隔离电路第一端和第二端的低电流断开提供条件，避免隔离电路的第一端和第二端直接断开时产生电压冲击或拉弧；而且，可以避免隔离电路直接断开时产生高压，损坏隔离电路；本申请通过设置第一旁路电路和隔离电路，隔离电路断开时流过其上的电流比较低，隔离电路的大电流分断能力要求较低，成本也比较低。
进一步的，所述第一旁路电路为常开开关，所述隔离电路为常开分断器，当所述光伏逆变器启动时，所述驱动控制电路用于控制所述第一旁路电路以使隔离电路第一端和第二端之间的压差小于或等于预设电压之后，控制所述隔离电路的第一端和第二端导通以使所述第一光伏组件分别与正直流母线和负直流母线连通；在所述隔离电路导通后，所述驱动控制电路还用于控制所述第一旁路电路的第一端和第二端断开以完成光伏逆变器的启动。所述驱动控制电路输入脉宽调制信号给所述第一旁路电路以使第一旁路电路间歇性导通，使隔离电路第一端和第二端之间的压差小于或等于预设电压。从而，可以防止隔离电路直接导通的瞬间出现大电流，可以防止PV电容、BUS电容等元器件和线路损坏。
进一步的，所述第一单元还包括至少一个第二单元，所述第二单元包括第二旁路电路；当所述隔离电路的第一端与所述正直流母线的第二端电连接时，所述第二旁路电路的第一端与所述隔离电路的第二端电连接且用于与第二光伏组件的第一端电连接，所述第二旁路电路的第二端与所述负直流母线的第二端电连接且用于与第二光伏组件的第二端电连接，所述驱动控制电路的第二端与所述第二旁路电路的第三端电连接，所述驱动控制电路用于在检测到所述正直流母线和负直流母线出现故障后，所述驱动控制电路用于控制所述第二 旁路电路的第一端和第二端导通，且用于控制所述隔离电路的第一端和第二端断开以使所述第二光伏组件与所述正直流母线断开，且所述隔离电路断开的时间点晚于所述第二旁路电路导通的时间点；或当所述隔离电路的第一端与所述负直流母线的第二端电连接时，所述第二旁路电路的第一端与所述正直流母线的第二端电连接且用于与第二光伏组件的第一端电连接，所述第二旁路电路的第二端与所述隔离电路的第二端电连接且用于与第二光伏组件的第二端电连接，所述驱动控制电路的第二端与所述第二旁路电路的第三端电连接，所述驱动控制电路用于在检测到所述正直流母线和负直流母线出现故障后，所述驱动控制电路用于控制所述第二旁路电路的第一端和第二端导通，且用于控制所述隔离电路的第一端和第二端断开以使所述第二光伏组件与所述负直流母线断开，且所述隔离电路断开的时间点晚于所述第二旁路电路导通的时间点。由于所述第一单元还包括至少一个第二单元，第二单元均用于与第二光伏组件电连接，这样光伏逆变器可以产生比较大的功率，提高了光伏逆变器的应用范围。而且，在一个第一单元中第二旁路电路与第一旁路电路共同连接同一个隔离电路，从而，可以减少隔离电路的数目，有利于降低成本。
进一步的，所述光伏逆变器还包括母线电容，所述母线电容的两端分别与所述正直流母线、负直流母线电连接，所述第一单元还包括第一防回流开关；当所述隔离电路的第一端与所述正直流母线的第二端电连接时，所述第一防回流开关的第一端与所述正直流母线的第二端电连接且所述第一防回流开关的第二端与所述隔离电路的第一端电连接，或者，所述第一防回流开关的第一端与所述隔离电路的第二端电连接且所述第一防回流开关的第二端与所述第一旁路电路的第一端电连接，或者，所述第一防回流开关的第一端与所述第一旁路电路的第二端电连接且所述第一防回流开关的第二端与所述负直流母线的第二端电连接，在所述第一旁路电路导通后所述第一防回流开关用于阻止所述母线电容经由所述第一旁路电路放电；或当所述隔离电路的第一端与所述负直流母线的第二端电连接时，所述第一防回流开关的第一端与所述正直流母线的第二端电连接且所述第一防回流开关的第二端与所述第一旁路电路的第一端电连接，或者，所述第一防回流开关的第一端与所述第一旁路电路的第二端电连接且所述第一防回流开关的第二端与所述隔离电路的第二端电连接，或者，所述第一防回流开关的第一端与所述隔离电路的第一端电连接且所述第一防回流开关的第二端与所述负直流母线的第二端电连接；在所述第一旁路电路导通后所述第一防回流开关用于阻止所述母线电容经由所述第一旁路电路放电。所述第一防回流开关为二极管，所述第一防回流开关的第一端为二极管的阴极，所述第一防回流开关的第二端为二极管的阳极。通过设置第一防回流开关，可以防止BUS电容经由第一旁路电路放电；而且，当光伏逆变器包括多个第三单元时，当第一旁路电路导通时，第一防回流开关还可以阻止与第三单元电连接第三光伏组件经由第一旁路电路形成回路，防止造成电流过大而出现光伏逆变器损坏的风险。
进一步的，所述光伏逆变器还包括母线电容，所述母线电容的两端分别与所述正直流母线、负直流母线电连接，所述第一单元还包括第一防回流开关；当所述隔离电路的第一端与所述正直流母线的第二端电连接时，所述第一防回流开关的第一端分别与所述隔离电路的第二端和第二旁路电路的第一端电连接且所述第一防回流开关的第二端与所述第一旁路电路的第一端电连接，或者，所述第一防回流开关的第一端与所述第一旁路电路的第二 端电连接且所述第一防回流开关的第二端分别与所述负直流母线的第二端和第二旁路电路的第二端电连接，在所述第一旁路电路导通后所述第一防回流开关用于阻止所述母线电容、所述第二光伏组件经由所述第一旁路电路放电；或当所述隔离电路的第一端与所述负直流母线的第二端电连接时，所述第一防回流开关的第一端分别与所述正直流母线的第二端和第二旁路电路的第一端电连接且所述第一防回流开关的第二端与所述第一旁路电路的第一端电连接，或者，所述第一防回流开关的第一端与所述第一旁路电路的第二端电连接且所述第一防回流开关的第二端分别与隔离电路的第二端和第二旁路电路的第二端电连接；在所述第一旁路电路导通后所述第一防回流开关用于阻止所述母线电容、所述第二光伏组件经由所述第一旁路电路放电。所述第一防回流开关为二极管，所述第一防回流开关的第一端为二极管的阴极，所述第一防回流开关的第二端为二极管的阳极。通过设置第一防回流开关，第一防回流开关除了可以防止BUS电容经由第一旁路电路放电外，当第一旁路电路导通时，第一防回流开关还可以阻止第二光伏组件经由第二单元、第一旁路电路形成电流回路，造成电流过大而出现第一旁路电路损坏的风险。
进一步的，所述光伏逆变器还包括母线电容，所述母线电容的两端分别与所述正直流母线、负直流母线电连接，所述第二单元还包括第二防回流开关；当所述隔离电路的第一端与所述正直流母线的第二端电连接时，所述第二防回流开关的第一端分别与所述隔离电路的第二端和第一旁路电路的第一端电连接且所述第二防回流开关的第二端与所述第二旁路电路的第一端电连接，或者，所述第二防回流开关的第一端与所述第二旁路电路的第二端电连接且所述第二防回流开关的第二端分别与所述负直流母线的第二端和第一旁路电路的第二端电连接，在所述第二旁路电路导通后所述第二防回流开关用于阻止所述母线电容、所述第一光伏组件经由所述第二旁路电路放电；或当所述隔离电路的第一端与所述负直流母线的第二端电连接时，所述第二防回流开关的第一端分别与所述正直流母线的第二端和第一旁路电路的第一端电连接且所述第二防回流开关的第二端与所述第二旁路电路的第一端电连接，或者，所述第二防回流开关的第一端与所述第二旁路电路的第二端电连接且所述第二防回流开关的第二端分别与所述隔离电路的第二端和第一旁路电路的第二端电连接；在所述第二旁路电路导通后所述第二防回流开关用于阻止所述母线电容、所述第一光伏组件经由所述第二旁路电路放电。所述第二防回流开关为二极管，所述第二防回流开关的第一端为二极管的阴极，所述第二防回流开关的第二端为二极管的阳极。通过设置第二防回流开关，第二防回流开关除了可以防止BUS电容经由第二旁路电路放电外，当第二旁路电路导通时，第二防回流开关还可以阻止第一光伏组件、其他第二光伏组件等经由第二旁路电路形成电流回路，造成电流过大而出现第二旁路电路损坏的风险。
进一步的，所述第一旁路电路为具有三端的开关，所述开关为继电器、接触器、带分励脱扣绕组的开关或者可控半导体分断器件。
进一步的，所述隔离电路为具有三端的分断器，所述分断器为继电器、接触器、带分励脱扣绕组的开关或者可控半导体分断器件。
进一步的，所述光伏逆变器还包括辅源提供单元，所述辅源提供单元与所述驱动控制电路电连接，所述辅源提供单元用于向所述驱动控制电路供电。
本申请第二方面一实施例提供一种光伏发电系统，包括上述的光伏逆变器，所述光伏 发电系统还包括第一光伏组件，所述第一光伏组件与所述光伏逆变器电连接。
附图说明
为了更清楚地说明本申请的技术方案，下面将对实施方式中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本申请的一些实施方式，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以如这些附图获得其他的附图。
图1是现有技术一种单级式光伏逆变器的示意图；
图2是现有技术一种两级式光伏逆变器的示意图；
图3是现有技术另外一种两级式光伏逆变器的示意图；
图4是图2和图3中DC/DC升压电路的具体电路图；
图5是本申请第一实施例光伏逆变器的模块示意图；
图6是本申请第一实施例光伏逆变器的部分电路图；
图7是本申请第二实施例光伏逆变器的示意图；
图8是本申请第三实施例光伏逆变器的示意图；
图9是本申请第四实施例光伏逆变器的示意图；
图10是图9中辅源提供单元的示意图；
图11是本申请第五实施例光伏逆变器的示意图；
图12是本申请第六实施例光伏逆变器的示意图；
图13是本申请第七实施例光伏逆变器的示意图；
图14是本申请第八实施例光伏逆变器的示意图；
图15是本申请第九实施例光伏逆变器的示意图；
图16是图15中其中一个第一单元的示意图；
图17是本申请第十实施例光伏逆变器的示意图；
图18是图17中其中一个第一单元的示意图；
图19是本申请第十一实施例光伏逆变器的示意图；
附图标号：
110-DC/AC变换器；120-正直流母线；121-第一端；122-第二端；130-负直流母线；131-第一端；132-第二端；140-驱动控制电路；141-第一端；142-第二端；Cbus-母线电容；Dub1-第一端；Dub2-第二端；Cpv-PV电容；Dup1-第一端；Dup2-第二端；150-第一DC/DC升压电路；160-辅源提供单元；161-电压保持电路；162-电压转换单元；1621-正输入端；1622-负输入端；1623-正输出端；1624-负输出端；Dvcc-辅源二极管；Cvcc-辅源电容；Duv1-第一端；Duv2-第二端；
200-第一单元；210-第一旁路电路；211-第一端；212-第二端；213-第三端；220-隔离电路；221-第一端；222-第二端；223-第三端；230-第一光伏组件；231-正输出端；232-负输出端；240-第一防回流开关；241-第一端；242-第二端；
350-第二DC/DC升压电路；351-正输入端；352-负输入端；353-正输出端；354-负输出端；
400-第三单元；430-第三光伏组件；431-正输出端；432-负输出端；
500-第二单元；510-第二旁路电路；511-第一端；512-第二端；513-第三端；530-第二光伏组件；531-正输出端；532-负输出端；540-第二防回流开关；541-第一端；542-第二端。
具体实施方式
下面将结合本申请实施例中的附图，对本申请实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例仅仅是本申请一部分实施例，而不是全部的实施例。基于本申请中的实施例，本领域普通技术人员在没有作出创造性劳动前提下所获得的所有其他实施例，都属于本申请保护的范围。
本申请实施例提供一种光伏逆变器，光伏逆变器应用到光伏发电系统中。光伏发电系统包括第一光伏组件和光伏逆变器，第一光伏组件包括正输出端和负输出端，第一光伏组件的正输出端、负输出端分别与光伏逆变器电连接，与光伏逆变器电连接的第一光伏组件的数目可以是一个，也可以是多个，第一光伏组件将太阳能转换为直流电，然后经由光伏逆变器将直流电转换为交流电，其后交流电可以并入电网或者提供给负载使用。
第一实施例
请参见图5，光伏逆变器为单级式光伏逆变器，光伏逆变器包括DC/AC变换器110、正直流母线120、负直流母线130、驱动控制电路140和一个第一单元200。另外，在本申请的其他实施例中，第一单元200的数目还可以是多个，例如2个、3个、4个或者更多个。在图5中正直流母线120的两自由端中右端为第一端121、左端为第二端122，负直流母线130的两自由端中右端为第一端131、左端为第二端132，正直流母线120的第一端121以及负直流母线130的第一端131分别与DC/AC变换器110电连接，在这里正直流母线120的第一端121以及负直流母线130的第一端131直接与DC/AC变换器110电连接。在本实施例中，正直流母线120的长度和负直流母线130的长度可以相等，也可以不相等。
在本实施例中，第一单元200包括第一旁路电路210和隔离电路220。隔离电路220具有至少三端：第一端221、第二端222和第三端223，第一旁路电路210具有至少三端：第一端211、第二端212和第三端213，驱动控制电路140具有至少两端：第一端141和第二端142。其中，隔离电路220和第一旁路电路210的第三端213为控制端，隔离电路220的第三端223用于控制隔离电路220的第一端221、第二端222之间是否导通，第一旁路电路210的第三端213用于控制第一旁路电路210的第一端211、第二端212之间是否导通。
可选的，在图5中，隔离电路220的第一端221与正直流母线120的第二端122电连接，在这里，隔离电路220的第一端221可以直接与正直流母线120的第二端122电连接，也可以通过其他导线间接与正直流母线120的第二端122电连接；隔离电路220的第二端222用于与第一光伏组件230的正输出端231电连接，具体为隔离电路220的第二端222通过导线与第一光伏组件230的正输出端231电连接；负直流母线130的第二端132用于与第一光伏组件230的负输出端232电连接，在这里，负直流母线130的第二端132通过导线与第一光伏组件230的负输出端232电连接。在本实施例中，第一旁路电路210的第一端211与隔离电路220的第二端222电连接，第一旁路电路210的第二端212与负直流母线130的第二端132电连接。
在本实施例中，驱动控制电路140的第一端141与隔离电路220的第三端223电连接，驱动控制电路140的第二端142与第一旁路电路210的第三端213电连接，驱动控制电路140通过其第一端141、第二端142分别输出信号用于控制隔离电路220的第一端221和第二端222是否导通、第一旁路电路210的第一端211和第二端212是否导通。驱动控制电路140用于检测正直流母线120和负直流母线130是否出现故障，例如DC/AC(直流/交流)变换器110、母线电容Cbus(请见后面描述)等元器件出现故障导致正直流母线120、负直流母线130发生故障，该故障例如为：正直流母线120、负直流母线130发生短路故障，正直流母线120和负直流母线130上出现过压故障，正直流母线120和负直流母线130上出现电压不均衡故障等。在本实施例中，驱动控制电路140用于检测正直流母线120和负直流母线130是否故障为常规的技术，例如驱动控制电路140与正直流母线120、负直流母线130连接以检测电压、电流等信号确定正直流母线120和负直流母线130是否出现故障，在此不再赘述。
当驱动控制电路140检测到正直流母线120和负直流母线130出现故障后，驱动控制电路140用于控制第一旁路电路210的第一端211和第二端212导通，此时第一光伏组件230、第一旁路电路210形成电性回路，对原先的电流进行分流，促使流过隔离电路220上的电流小于或等于预设电流，该预设电流由工作人员根据实际电路状况进行设定，例如该预设电流为0A、1A、2A、3A等，该预设电流一般等于0A或者比较接近0A。进一步的，驱动控制电路140还用于控制隔离电路220的第一端221和第二端222断开，从而与隔离电路220的第二端222电连接的第一光伏组件230和与隔离电路220第一端221电连接的正连接母线会断开。而且，隔离电路220断开的时间点晚于第一旁路电路210导通的时间点。由于不同元器件的响应时间不同，在本实施例中，驱动控制电路140可以同时通过第二端142和第一端141分别发送信号给第一旁路电路210的第三端213和隔离电路220的第三端223，驱动控制电路140也可以先发送信号给第一旁路电路210，然后再发送信号给隔离电路220，或者反过来，但不管信号发送的时间点如何，要确保隔离电路220的第一端221和第二端222断开的时间点晚于第一旁路电路210的第一端211和第二端212导通的时间点。
在本实施例中，通过设置驱动控制电路140和隔离电路220，且隔离电路220的第一端221与正直流母线120的第二端122电连接，隔离电路220的第二端222与第一光伏组件230的正输出端231电连接。当驱动控制电路140用于检测到正直流母线120和负直流母线130出现故障时，驱动控制电路140控制隔离电路220的第一端221和第二端222断开以使第一光伏组件230与正直流母线120断开，从而与隔离电路220的第二端222电连接的第一光伏组件230不能继续输送能量到故障点，可以防止故障点进一步蔓延。
进一步的，通过设置第一旁路电路210，驱动控制电路140用于检测到正直流母线120和负直流母线130出现故障后，驱动控制电路140控制第一旁路电路210的第一端211和第二端212导通，以使流过隔离电路220的第一端221和第二端222的电流小于或等于预设电流，且控制隔离电路220的第一端221和第二端222断开以使第一光伏组件230与正直流母线120断开，且隔离电路220断开的时间点晚于第一旁路电路210导通的时间点。这样设置的好处是：隔离电路220的第一端221和第二端222断开时此时流过隔离电路220 的电流比较低，为隔离电路220的第一端221和第二端222的低电流断开提供条件，避免隔离电路220的第一端221和第二端222直接断开时产生电压冲击或拉弧；而且，可以避免隔离电路220直接断开时产生高压，损坏隔离电路220；本申请通过设置第一旁路电路210和隔离电路220，隔离电路220断开时流过其上的电流比较低，隔离电路220的大电流断开能力要求较低，成本也比较低。
请结合参见图5和图6，可选的，在本实施例中，第一旁路电路210为具有三端的开关M，在本实施例中开关M为常开开关，也即在未通电时开关M的第一端211和第二端212是断开的。但本申请不限于此，在本申请的其他实施例中，开关M还可以为常闭开关，也即在未通电时开关M的第一端211和第二端212是导通闭合的。开关M例如为继电器或者接触器或者带分励脱扣绕组的开关或者可控半导体分断器件，可控半导体分断器件例如为MOS管(metal oxide semiconductor，金属氧化物半导体场效应晶体管)、IGBT(Insulated Gate Bipolar Transistor，绝缘栅双极型晶体管)、IGCT((Integrated Gate Commutated Thyristors，集成门极换流晶闸管)等。在图6中，开关M为IGBT，IGBT的成本比较低。开关M的第一端211为集电极，第二端212为发射级，第三端213为栅极。
可选的，在本实施例中，隔离电路220为具有三端的分断器K，在此处分断器K为常开分断器，也即在未通电时隔离电路220的第一端221和第二端222是断开的。但本申请不限于此，在本申请的其他实施例中，分断器K还可以为常闭分断器。分断器K例如为继电器、接触器、带分励脱扣绕组的开关或者可控半导体分断器件，可控半导体分断器件例如为MOS管、IGBT、IGCT等，在图6中，分断器K为继电器，继电器既可以实现较好的分断功能，成本又比较低，而且分断稳定。分断器K的第三端223为控制端。
在本实施例中，光伏逆变器还包括BUS(母线)电容Cbus、PV电容Cpv(光伏电容)。PV(photovoltaics)表示光伏。PV电容Cpv的第一端Dup1分别与第一光伏组件230的正输出端231、第一旁路电路210的第一端211、第一隔离电路220的第二端222电连接，PV电容Cpv的第二端Dup2分别与第一光伏组件230的负输出端232、第一旁路电路210的第二端212、负直流母线130的第二端132电连接。母线电容Cbus的第一端Dub1、第二端Dub2分别与正直流母线120和负直流母线130电连接。
请参见图6，可选的，第一单元200还包括第一防回流开关240。在此处，第一防回流开关240的第一端241与隔离电路220的第二端222电连接且第一防回流开关240的第二端242与第一旁路电路210的第一端211电连接，也即第一防回流开关240位于隔离电路220和第一旁路电路210之间。但本申请不限于此，在本申请的其他实施例中，第一防回流开关240的第一端241与正直流母线120的第二端122电连接且第一防回流开关240的第二端242与隔离电路220的第一端221电连接。在本申请的其他实施例中，第一防回流开关240的第一端241与第一旁路电路210的第二端212电连接且第一防回流开关240的第二端242与负直流母线130的第二端132电连接。而且，在第一旁路电路210导通后第一防回流开关240阻止母线电容Cbus经由第一旁路电路210放电。具体而言，在本实施例中，第一防回流开关240为二极管，第一防回流开关240的第一端241为二极管的阴极，第一防回流开关240的第二端242为二极管的阳极。从而，当第一旁路电路210导通时，第一防回流开关240可以阻止母线电容Cbus经由第一旁路电路210放电。
在本实施例中，驱动控制电路140例如为微处理器、控制芯片等，在此不再赘述。正直流母线120、负直流母线130由导线构成。
在本实施例中，当正直流母线120和负直流母线130出现故障后，驱动控制电路140控制第一旁路电路210的第一端211和第二端212导通，且控制隔离电路220的第一端221和第二端222断开以使第一光伏组件230与正直流母线120断开之后，此后驱动控制电路140可以进一步控制第一旁路电路210的第一端211和第二端212断开，这样设置第一光伏组件230不再通过第一旁路电路210形成回路，不再向光伏逆变器输送能量。另外，在本申请的其他实施例中，驱动控制电路140也可以不用管第一旁路电路210，这样驱动控制电路140继续控制第一旁路电路210的第一端211和第二端212导通，但可能过一段时间驱动控制电路140不被供电后，由于第一旁路电路210为常开开关，第一旁路电路210会自动断开。在本申请的其他实施例中，当驱动控制电路140被持续供电时，驱动控制电路140可以继续控制第一旁路电路210导通，由于第一光伏组件230的能量不会被输送到正直流母线120、负直流母线130上，第一旁路电路210即使持续导通仍然可以接受，不会使故障点的故障扩散开，对整个光伏逆变器的影响有限。
在本实施例中，当未出现故障，光伏逆变器正常上电启动时，由于隔离电路220为常开分断器，刚开始DC/AC变换器110不会被第一光伏组件230供电，此时驱动控制电路140控制第一旁路电路210以使隔离电路220两端的压差小于或等于预设电压，该预设电压由工作人员根据实际电路状况进行设定，例如该预设电压为40V、30V、20V、10V、0V等。具体而言，通过使第一旁路电路210间歇性导通，例如提供PMW(脉冲宽度调制)信号给开关M的控制端，开关M间歇性导通，也即开关M的第一端211和第二端212一会导通一会断开，通过调整PWM信号的占空比可以使隔离电路220的第二端222的电压降到某个电压值，而光伏逆变器刚上电时隔离电路220的第一端221的电压比较稳定，例如为0V或者某个电压值，从而，通过驱动控制电路140控制第一旁路电路210可以使隔离电路220两端的压差小于或等于预设电压。而且，驱动控制电路140还控制隔离电路220的第一端221和第二端222导通以使第一光伏组件230分别与正直流母线120和负直流母线130连通，且隔离电路220导通的时间点晚于隔离电路220第一端221和第二端222之间的压差小于或等于预设电压的时间点，在隔离电路220导通后驱动控制电路140控制第一旁路电路210的第一端211和第二端212断开以完成光伏逆变器的启动，实现第一光伏组件230向DC/AC变换器110供电。此种方式为光伏逆变器的软启动，通过如此设置，可以避免隔离电路220直接导通出现的问题，这些问题为：如果不设置第一旁路电路210或者不控制第一旁路电路210，而使隔离电路220直接导通，PV电容Cpv和母线电容Cbus会直接连通，由于PV电容Cpv一般会充满电，而母线电容Cbus没充电，隔离电路220导通的瞬间会有大电流产生，由于母线电容Cbus和PV电容Cpv之间的线路、PV电容Cpv或者母线电容Cbus本身有耐电流上限，可能会导致该些线路或者元器件损坏。而通过本申请的软启动，可以解决隔离电路220直接导通的上述问题，PV电容Cpv、母线电容Cbus等元器件和线路不会在光伏逆变器正常开启时出现损坏。而且，在隔离电路220导通后驱动控制电路140控制第一旁路电路210断开，由此第一光伏组件230通过隔离电路220、DC/AC变换器110等元器件形成回路，驱动控制电路140可以控制第一旁路电路210顺利 安全断开。
第二实施例
图7是本申请第二实施例的示意图，图7的示意图与图6的示意图相似，本实施例与第二实施例的主要不同点为隔离电路220的位置。
请参见图7，在本实施例中，正直流母线120的第一端121以及负直流母线130的第一端131分别与DC/AC变换器110电连接。
可选的，隔离电路220的第一端221与负直流母线130的第二端132电连接，在这里，隔离电路220的第一端221可以直接与负直流母线130的第二端132电连接，也可以通过其他导线间接与负直流母线130的第二端132电连接；隔离电路220的第二端222用于与第一光伏组件230的负输出端232电连接，具体为隔离电路220的第二端222通过导线与第一光伏组件230的负输出端232电连接；正直流母线120的第二端122用于与第一光伏组件230的正输出端231电连接，在这里，正直流母线120的第二端122通过导线与第一光伏组件230的正输出端231电连接。在本实施例中，第一旁路电路210的第一端211与正直流母线120的第二端122电连接，第一旁路电路210的第二端212与隔离电路220的第二端222电连接。
在本实施例中，驱动控制电路140的第一端141与隔离电路220的第三端223电连接，驱动控制电路140的第二端142与第一旁路电路210的第三端213电连接，驱动控制电路140通过其第一端141、第二端142分别输出信号用于控制隔离电路220的第一端221和第二端222是否导通、第一旁路电路210的第一端211和第二端212是否导通。驱动控制电路140检测正直流母线120和负直流母线130是否出现故障，例如DC/AC(直流/交流)变换器110、母线电容Cbus等元器件出现故障导致正直流母线120、负直流母线130发生故障，该故障例如为：正直流母线120、负直流母线130发生短路故障，正直流母线120和负直流母线130上出现过压故障，正直流母线120和负直流母线130上出现电压不均衡故障等。
当驱动控制电路140检测到正直流母线120和负直流母线130出现故障后，驱动控制电路140用于控制第一旁路电路210导通，此时第一光伏组件230、第一旁路电路210形成电性回路，促使流过隔离电路220上的电流小于或等于预设电流。进一步的，驱动控制电路140还用于控制隔离电路220的第一端221和第二端222断开，从而与隔离电路220的第二端222电连接的第一光伏组件230和与隔离电路220第一端电连接的负连接母线会断开。而且，隔离电路220断开的时间点晚于第一旁路电路210导通的时间点。
在本实施例中，通过设置驱动控制电路140和隔离电路220，且隔离电路220的第一端221与负直流母线130的第二端132电连接，隔离电路220的第二端222与第一光伏组件230的负输出电连接。当驱动控制电路140用于检测到正直流母线120和负直流母线130出现故障时，驱动控制电路140控制隔离电路220断开以使第一光伏组件230与负直流母线130断开，从而与隔离电路220的第二端222电连接的第一光伏组件230不能继续输送能量到故障点，可以防止故障点进一步蔓延。
进一步的，通过设置第一旁路电路210，驱动控制电路140用于检测到正直流母线120 和负直流母线130出现故障后，驱动控制电路140控制第一旁路电路210导通，以使流过隔离电路220的电流小于或等于预设电流，且控制隔离电路220断开以使第一光伏组件230与负直流母线130断开，且隔离电路220断开的时间点晚于第一旁路电路210导通的时间点。这样设置的好处是：隔离电路220的第一端221和第二端222断开时此时流过隔离电路220的电流比较低，也即为隔离电路220的低电流断开提供条件，避免隔离电路220直接断开时产生电压冲击或拉弧；而且，可以避免隔离电路220直接断开时产生高压，损坏隔离电路220；本申请通过设置第一旁路电路210和隔离电路220，隔离电路220断开时流过其上的电流比较低，隔离电路220的大电流断开能力要求较低，成本也比较低。
在本实施例中，光伏逆变器还包括BUS(母线)电容、PV电容Cpv(光伏电容)，具体连接方式请参见第一实施例。
请继续参见图7，在本实施例中，第一单元200还包括第一防回流开关240，在此处，第一防回流开关240的第一端241与正直流母线120的第二端122电连接且第一防回流开关240的第二端242与第一旁路电路210的第一端211电连接，也即第一防回流开关240位于母线电容Cbus和第一旁路电路210之间。但本申请不限于此，在本申请的其他实施例中，第一防回流开关240的第一端241与第一旁路电路210的第二端212电连接且第一防回流开关240的第二端242与隔离电路220的第二端222电连接。在本申请的其他实施例中，第一防回流开关240的第一端241与隔离电路220的第一端221电连接且第一防回流开关240的第二端242与负直流母线130的第二端132电连接。且，在第一旁路电路210导通后第一防回流开关240阻止母线电容Cbus经由第一旁路电路210放电。具体而言，在本实施例中，第一防回流开关240为二极管，第一防回流开关240的第一端241为二极管的阴极，第一防回流开关240的第二端242为二极管的阳极。从而，当第一旁路电路210导通时，第一防回流开关240可以阻止母线电容Cbus经由第一旁路电路210放电。
第三实施例
图8是本申请第三实施例的示意图，图8的示意图与图6的示意图相似，本实施例与第一实施例的主要不同点为第一单元200还包括第一DC/DC(直流/直流)升压电路。
请参见图8，光伏逆变器为两级式光伏逆变器，第一单元还包括第一DC/DC升压电路150，通过设置第一DC/DC升压电路150，能够帮助光伏逆变器获得更宽的电压范围及MPPT电压范围。在本实施例中第一DC/DC升压电路150为boost升压电路，但本申请不限于此，在本申请的其他实施例中，第一DC/DC升压电路150还可以为其他升压电路。图8示意了一种boost升压电路的部分实现电路示意图。但本申请不限于此，在本申请的其他实施例中，boost升压电路还可以有其他的电路实现形式。
在本实施例中，第一DC/DC升压电路150包括开关M，也即在本实施例中第一旁路电路210和第一DC/DC升压电路150共享开关M。由于第一DC/DC升压电路150为光伏逆变器中常用的元器件，从而，本申请实施例设置第一旁路电路210不用额外再增添开关M，可以降低成本。在本实施例中，第一DC/DC升压电路150还包括电感L，电感L的一端用于与第一光伏组件230的正输出端231子电连接，电感L与正输出端子之间还可以存在其他元器件，电感L的另外一端分别与第一旁路电路210的第一端211和隔离电路220的第 二端222电连接。在本实施例中，第一DC/DC升压电路150还包括二极管，在本实施例中第一防回流开关240与第一DC/DC升压电路150共享二极管，不用再额外增添二极管。二极管的阴极与隔离电路220的第二端222之间还可以存在其他元器件。
在本实施例中，由于第一旁路电路210与第一DC/DC升压电路150共享开关M，从而第一旁路电路210不需要额外再增设开关M，从而在获得更宽的电压范围的同时可以降低成本。而且，在本实施例中，由于电感L的存在，通过使隔离电路220断开的时间点晚于第一旁路电路210导通的时间点，可以避免隔离电路220直接断开时电感L产生很高的电压而损坏其他元器件的问题，例如击穿隔离电路220。本实施例通过第一旁路电路210和隔离电路220的搭配设计，不会出现隔离电路220断开时电感产生很高的电压的问题，对隔离电路220的耐压性要求不高，进而成本较低。
第四实施例
图9是本申请第四实施例的示意图，图9的示意图与图8的示意图相似，本实施例与第三实施例的主要不同点为光伏逆变器还包括辅源提供单元160。
请参见图9，光伏逆变器还包括辅源提供单元160，辅源提供单元160与驱动控制电路140电连接，辅源提供单元160用于向驱动控制电路140供电，以使驱动控制电路140正常工作。
请结合参见图9和图10，在本实施例中，辅源提供单元160包括电压保持电路161、电压转换单元162。电压转换单元162位于电压保持电路161与驱动控制电路140之间。具体而言，在本实施例中，电压保持电路161分别与正直流母线120、负直流母线130电连接，电压转换单元162与电压保持电路161电连接，驱动控制电路140与电压转换单元162电连接。另外，在本申请的其他实施例中，电压保持电路161还可以直接或者其他间接方式与第一光伏组件230的正输出端231、负输出端232电连接。本实施例中，当正直流母线120、负直流母线130正常供电时，正直流母线120、负直流母线130传输过来的电压经过电压保持电路161到达电压转换单元162，电压转换单元162转换为预定电源电压后提供给驱动控制电路140；当正直流母线120、负直流母线130出现故障导致第一光伏组件230不能供电给电压保持电路161时，此时电压保持电路161本身可以继续供电一段时间，并传输给电压转换单元162，电压转换单元162转换为预定电源电压后提供给驱动控制电路140。
具体而言，请参见图10，在本实施例中，电压保持电路161包括辅源二极管Dvcc和辅源电容Cvcc。其中，辅源二极管Dvcc的阳极与正直流母线120电连接，辅源二极管Dvcc的阴极分别与辅源电容Cvcc的第一端Duv1和电压转换单元162的正输入端1621电连接，辅源电容Cvcc的第二端Duv2分别与负直流母线130和电压转换单元162的负输入端1622电连接。另外，在本申请的其他实施例中，辅源二极管Dvcc的阳极还可以不与正直流母线120电连接，而是与隔离电路220的第一端221或者第二端或者第一光伏组件230的正输出端231电连接，辅源电容Cvcc的第二端Duv2与第一旁路电路210的第二端212或者第一光伏组件230的负输出端232电连接，且辅源电容Cvcc的第二端Duv2还与电压转换单元162的负输入端1622电连接。电压转换单元162的正输出端1623、负输出端1624分别 于驱动控制电路140电连接。当正直流母线120、负直流母线130出现故障导致第一光伏组件230不能供电给电压保持电路161时，此时可以通过被充满电的辅源电容Cvcc放电，由于辅源二极管Dvcc的存在，辅源电容Cvcc不会放电到正直流母线120、负直流母线130上，辅源电容Cvcc可以向电压转换单元162放电。在本实施例中，电压转换单元162为常规的能转换电压大小的电路，例如BUCK电路、反激电路等，在此就不再赘述。
在本实施例中，通过设置辅源提供单元160，辅源提供单元160与驱动控制电路140电连接，不管正直流母线120、负直流母线130是否出现故障，辅源提供单元160均可以供电给驱动控制电路140，驱动控制电路140可以正常工作，可以使驱动控制电路140正常对第一旁路电路210和隔离电路220进行控制。
在本实施例中，当驱动控制电路140检测到正直流母线120和负直流母线130出现故障时，即使第一光伏组件230不能向电压保持电路161供电，此时，充满电的辅源电容Cvcc可以继续向电压转换单元162供电，从而驱动控制电路140可以继续获得电力，驱动控制电路140可以控制第一旁路电路210导通，以使流过隔离电路220的电流等于或小于预设电流，且控制隔离电路220断开以使第一光伏组件230与正直流母线120断开，且隔离电路220断开的时间点晚于第一旁路电路210导通的时间点。当辅源电容Cvcc存储的电荷被释放完毕后，驱动控制电路140由于没有电力供应，不会再对第一旁路电路210和隔离电路220进行控制，由于第一旁路电路210为具有三端的常开开关M，隔离电路220为具有三端的常开分断器K，从而第一旁路电路210会自动断开，隔离电路220会继续保持为断开状态，第一光伏组件230此后不会通过第一旁路电路210形成回路，此种设置有利于提高光伏逆变器的安全。
另外，在本申请的其他实施例中，辅源提供单元160还可以是常用的直流电源，例如为电池电源等可以直接提供电源的装置，此时辅源提供单元160不需要与正直流母线120和负直流母线130、或者与第一光伏组件230电连接，此时辅源提供单元160不是通过第一光伏组件230供电。
第五实施例
图11是本申请第五实施例的示意图，图11的示意图与图6的示意图相似，本实施例与第一实施例的主要不同点为第一单元还包括第二DC/DC升压电路350。
请参见图11，光伏逆变器为两级式光伏逆变器，光伏逆变器还包括第二DC/DC升压电路350，通过设置第二DC/DC升压电路350，能够帮助光伏逆变器获得更宽的电压范围及MPPT电压范围。在本实施例中，第二DC/DC升压电路350的正输入端351与第一防回流开关240的第一端241电连接，第二DC/DC升压电路350的负输入端352与第一旁路电路210的第二端212电连接，第二DC/DC升压电路350的正输出端353与正直流母线120的第二端122电连接，第二DC/DC升压电路350的负输出端354与负直流母线130的第二端132电连接。第二DC/DC升压电路350为常规的升压电路，例如为boost升压电路等，在此不再赘述。在本实施例中，第二DC/DC升压电路350与第一旁路电路210不共享开关，也即第一旁路电路210需要额外设置开关M。
第六实施例
图12是本申请第六实施例的示意图，图12的示意图与图6的示意图相似，本实施例与第一实施例的主要不同点为第一单元还包括第二DC/DC升压电路350。
请参见图12，光伏逆变器为两级式光伏逆变器，光伏逆变器还包括第二DC/DC升压电路350，通过设置第二DC/DC升压电路350，能够帮助光伏逆变器获得更宽的电压范围及MPPT电压范围。在本实施例中，第二DC/DC升压电路350的正输入端351用于与第一光伏组件230的正输出端231电连接，第二DC/DC升压电路350的负输入端352用于与第一光伏组件230的负输出端232电连接，第二DC/DC升压电路350的正输出端353分别与第一旁路电路210的第一端211、第一防回流开关240的第二端242电连接，第二DC/DC升压电路350的负输出端354分别与第一旁路电路210的第二端212、负直流母线130的第二端132电连接。第二DC/DC升压电路350为常规的升压电路，例如为boost升压电路等，在此不再赘述。在本实施例中，第二DC/DC升压电路350与第一旁路电路210不共享开关，也即第一旁路电路210需要额外设置开关M。
第七实施例
图13是本申请第七实施例的示意图，图13的示意图与图9的示意图相似，本实施例与第四实施例的主要不同点为光伏逆变器包括多个第一单元200。
请参见图13，在本实施例中，光伏逆变器包括多个第一单元200，第一单元200的数目例如为2个、3个、4个、5个或者更多个。每个第一单元200用于与第一光伏组件230电连接，其中，不同第一单元200连接的第一光伏组件230不同，每个第一单元200还分别与同一条正直流母线120的第二端122、同一条负直流母线130的第二端132电连接，正直流母线120的第一端121、负直流母线130的第一端131分别与DC/AC变换器110电连接。
在本实施例中，每个第一单元200均包括第一旁路电路210、隔离电路220，第一旁路电路210、隔离电路220的具体连接方式请参见第一实施例、第二实施例，在此不再赘述。在本实施例中，驱动控制电路140的第一端141与所有隔离电路220的第三端223电连接，驱动控制电路140的第二端142与所有第一旁路电路210的第三端213电连接。
在本实施例中，驱动控制电路140用于检测到正直流母线120和负直流母线130出现故障后，驱动控制电路140控制所有第一旁路电路210导通，以使流过隔离电路220的电流小于或等于预设电流，且控制隔离电路220断开以使第一光伏组件230与正直流母线120或者负直流母线130断开，且在同一个第一单元200中隔离电路220断开的时间点晚于第一旁路电路210导通的时间点。
请继续参见图13，在本实施例中，光伏逆变器还包括至少一个第三单元400，第三单元400的数目例如可以为1个、2个、3个或者更多个。在本实施例中，第三单元400包括光伏电容Cpv，光伏电容Cpv的第一端Dup1分别与正直流母线120的第二端122电连接，且还用于与第三光伏组件430的正输出端431电连接，光伏电容Cpv的第二端Dup2与负直流母线130的第二端132电连接，且还用于与第三光伏组件430的负输出端432电连接。在本实施例中，第三单元400还包括第二DC/DC升压电路350，第二DC/DC升压电路350 的正输入端351与光伏电容Cpv的第一端Dup1电连接，且还用于与第三光伏组件430的正输出端431电连接，第二DC/DC升压电路350的负输入端352与光伏电容Cpv的第二端Dup2电连接，且还用于与第三光伏组件430的负输出端432电连接，第二DC/DC升压电路350的正输出端353与正直流母线120的第二端122电连接，第二DC/DC升压电路350的负输出端354与负直流母线130的第二端132电连接。第二DC/DC升压电路350的具体电路结构可以参考第一DC/DC升压电路，在此不再赘述。
在本实施例中，由于光伏逆变器包括多个第一单元200，每个第一单元200均包括第一旁路电路210和隔离电路220，从而，当驱动控制电路140检测到正直流母线120和负直流母线130出现故障时，此时驱动控制电路140控制所有隔离电路220断开以使第一光伏组件230与正直流母线120或者负直流母线130断开，从而与第一单元200连接的第一光伏组件230不能继续输送能量到故障点，减少了输往故障点的能量，可以防止故障点进一步蔓延。同样，通过与隔离电路220搭配设置第一旁路电路210，在同一个第一单元200中隔离电路220断开的时间点晚于第一旁路电路210导通的时间点，从而，在第一旁路电路210导通后隔离电路220将第一光伏组件230与正直流母线120或者负直流母线130断开，这样设置的好处是为隔离电路220的低电流断开提供条件，避免隔离电路220直接断开时产生电压冲击或拉弧；而且，可以避免隔离电路220直接断开时产生高压，损坏隔离电路220；本申请对隔离电路220的耐压性要求较低，隔离电路220的成本比较低。而且，在本实施例中，由于光伏逆变器包括多个第一单元200和多个第三单元400，第一单元200用于与第一光伏组件230电连接，第三单元400用于与第三光伏组件430电连接，这样光伏逆变器可以产生比较大的功率，提高了光伏逆变器的应用范围。
第八实施例
图14是本申请第八实施例的示意图，图14的示意图与图13的示意图相似，本实施例与第七实施例的主要不同点为光伏逆变器不包括第三单元400。
请参见图14，与第七实施例中光伏逆变器包括多个第一单元200和多个第三单元400不同，在本实施例中，光伏逆变器仅包括多个第一单元200，不包括第三单元400。
在本实施例中，由于光伏逆变器不包括第三单元400，从而，当驱动控制电路140检测到正直流母线120和负直流母线130出现故障时，驱动控制电路140控制所有隔离电路220断开以使第一光伏组件230与正直流母线120或者负直流母线130断开，从而所有第一光伏组件230向故障点输送能量的通路被隔断，故障点没有能量继续输入，故障不会扩大。
第九实施例
图15是本申请第九实施例的示意图，图15的示意图与图13的示意图相似，本实施例与第七实施例的主要不同点为第一单元200还包括至少一个第二单元500。
请参见图15和图16，在本实施例中，第一单元200的数目为多个，每个第一单元200包括至少一个第二单元500，例如第一单元200包括第二单元500的数目为1个、2个、3个或者更多个。在本实施例中，第二单元500包括第二旁路电路510。
具体而言，请参见图16，在一个第一单元200中，第二旁路电路510的第一端511与隔离电路220的第二端222电连接且用于与第二光伏组件530的正输出端531电连接，也即第一旁路电路210的第一端211和第二旁路电路510的第一端511均与隔离电路220的第二端222电连接，第二旁路电路510的第二端512与负直流母线130的第二端132电连接且用于与第二光伏组件530的负输出端532电连接，驱动控制电路140的第二端142与所有第二旁路电路510的第三端513电连接。驱动控制电路140用于在检测到正直流母线120和负直流母线130出现故障后，驱动控制电路140用于控制第一旁路电路210、第二旁路电路510的第一端511和第二端均导通，且用于控制隔离电路220的第一端221和第二端222断开以使第一光伏组件230、第二光伏组件530与正直流母线120断开，且同一个第一单元200中隔离电路220断开的时间点晚于第一旁路电路210、第二旁路电路510导通的时间点。在本实施例中，同一个第一单元200中的第一旁路电路210、第二旁路电路510共同连接同一个隔离电路220。
在本实施例中，由于第一单元200还包括至少一个第二单元500，每个第二单元500均包括第二旁路电路510，同一第一单元200中所有第二旁路电路510与第一旁路电路210共同连接同一个隔离电路220，从而，可以减少隔离电路220的数目，有利于降低成本。而且，当驱动控制电路140检测到正直流母线120和负直流母线130出现故障时，此时驱动控制电路140控制隔离电路220断开以使第一光伏组件230、第二光伏组件530与正直流母线120断开，从而第一光伏组件230、第二光伏组件530不能继续输送能量到故障点，减少了输往故障点的能量，可以防止故障进一步蔓延。同样，同一个第一单元200中隔离电路220断开的时间点晚于第二旁路电路510、第一旁路电路210导通的时间点，这样设置的好处是为隔离电路220的低电流分断提供条件，避免隔离电路220分断时产生电压冲击或拉弧，而且，可以避免隔离电路220直接断开时产生高压，损坏隔离电路220，本申请对隔离电路220的耐压性要求较低，隔离电路220的成本比较低。而且，在本实施例中，由于第一单元200还包括至少一个第二单元500，第二单元500用于与第二光伏组件530电连接，这样光伏逆变器可以产生比较大的功率，提高了光伏逆变器的应用范围。
在本实施例中，第二旁路电路510的电路结构和第一旁路电路210的电路结构相同，具体请参见第一实施例中，在此不再赘述。
可选的，在本实施例中，第一防回流开关240的第一端241分别与隔离电路220的第二端222和第二旁路电路510的第一端511电连接且第一防回流开关240的第二端242与第一旁路电路210的第一端211电连接。另外，在本申请的其他实施例中，第一防回流开关240的第一端241与第一旁路电路210的第二端212电连接且第一防回流开关240的第二端242分别与负直流母线130的第二端132和第二旁路电路510的第二端512电连接。在本实施例中，第一防回流开关240除了可以防止母线电容Cbus经由第一旁路电路210放电外，当第一旁路电路210导通时，第一防回流开关240还可以阻止第二光伏组件530经由第二单元500、第一旁路电路210形成电流回路，造成电流过大而出现第一旁路电路210损坏的风险。
可选的，在本实施例中，第二单元500还包括第二防回流开关540。第二防回流开关540的第一端541分别与隔离电路220的第二端222和第一旁路电路210的第一端211电连 接且第二防回流开关540的第二端542与第二旁路电路510的第一端511电连接。另外，在本申请的其他实施例中，第二防回流开关540的第一端541与第二旁路电路510的第二端512电连接且第二防回流开关540的第二端542分别与负直流母线130的第二端132和第一旁路电路210的第二端212电连接。在本实施例中，第二防回流开关540除了可以防止母线电容Cbus经由第二旁路电路510放电外，当第二旁路电路510导通时，第二防回流开关540还可以阻止第一光伏组件230、其他第二光伏组件530经由第二旁路电路510形成电流回路，造成电流过大而出现第二旁路电路510损坏的风险。在本实施例中，第二防回流开关540与第一防回流开关240一样，也为二极管，第二防回流开关540的第一端为二极管的阴极，第二防回流开关540的第二端为二极管的阳极。
在本实施例中，第二单元500还包括还包括第一DC/AC升压电路150。
第十实施例
图17是本申请第十实施例的示意图，图17的示意图与图15的示意图相似，本实施例与第九实施例的主要不同点为第一单元200中隔离电路220的第一端221与负直流母线130的第二端132电连接。
请参见图17和图18，在本实施例中，第一单元200的数目为多个，每个第一单元200的隔离电路220的第一端221与负直流母线130的第二端132电连接，隔离电路220的第二端222与第一旁路电路210的第二端212电连接且用于与第一光伏组件230的负输出端232电连接。在本实施例中，每个第一单元200包括至少一个第二单元500，第二单元500包括第二旁路电路510。
具体而言，请参见图18，在一个第一单元200中，第二旁路电路510的第一端511与正直流母线120的第二端122电连接且用于与第二光伏组件530的正输出端531电连接，第二旁路电路510的第二端512与隔离电路220的第二端222电连接且用于与第二光伏组件530的负输出端532电连接，也即第一旁路电路210的第二端212和第二旁路电路510的第二端512均与隔离电路220的第二端222电连接，驱动控制电路140的第二端142与第二旁路电路510的第三端513电连接。驱动控制电路140用于在检测到正直流母线120和负直流母线130出现故障后，驱动控制电路140用于控制第一旁路电路210、第二旁路电路510的第一端511和第二端均导通，且用于控制隔离电路220的第一端221和第二端222断开以使第一光伏组件230、第二光伏组件530与负直流母线130断开，且同一个第一单元200中隔离电路220断开的时间点晚于第一旁路电路210、第二旁路电路510导通的时间点。在本实施例中，同一个第一单元200中的第一旁路电路210、第二旁路电路510共同连接同一个隔离电路220。
在本实施例中，由于第一单元200还包括至少一个第二单元500，每个第二单元500均包括第二旁路电路510，同一个第一单元200中所有第二旁路电路510与第一旁路电路210共同连接同一个隔离电路220，从而，可以减少隔离电路220的数目，有利于降低成本。而且，当驱动控制电路140检测到正直流母线120和负直流母线130出现故障时，此时驱动控制电路140控制隔离电路220断开以使第一光伏组件230、第二光伏组件530与负直流母线130断开，从而第一光伏组件230、第二光伏组件530不能继续输送能量到故障点， 减少了输往故障点的能量，可以防止故障进一步蔓延。同样，同一个第一单元200中隔离电路220断开的时间点晚于第二旁路电路510、第一旁路电路210导通的时间点，这样设置的好处是为隔离电路220的低电流分断提供条件，避免隔离电路220分断时产生电压冲击或拉弧，而且，可以避免隔离电路220直接断开时产生高压，损坏隔离电路220，本申请对隔离电路220的耐压性要求较低，隔离电路220的成本比较低。而且，在本实施例中，由于第一单元200还包括至少一个第二单元500，第二单元500用于与第二光伏组件530电连接，这样光伏逆变器可以产生比较大的功率，提高了光伏逆变器的应用范围。
可选的，在本实施例中，第一防回流开关240的第一端241分别与正直流母线120的第二端122和第二旁路电路510的第一端511电连接且第一防回流开关240的第二端242与第一旁路电路210的第一端211电连接。另外，在本申请的其他实施例中，第一防回流开关240的第一端241与第一旁路电路210的第二端212电连接且第一防回流开关240的第二端242分别与隔离电路220的第二端222和第二旁路电路510的第二端512电连接。在本实施例中，第一防回流开关240除了可以防止母线电容Cbus经由第一旁路电路210放电外，当第一旁路电路210导通时，第一防回流开关240还可以阻止第二光伏组件530经由第二单元500、第一旁路电路210形成电流回路，造成电流过大而出现第一旁路电路210损坏的风险。
可选的，在本实施例中，第二单元500还包括第二防回流开关540。第二防回流开关540的第一端541分别与正直流母线120的第二端122和第一旁路电路210的第一端211电连接且第二防回流开关540的第二端542与第二旁路电路510的第一端511电连接。另外，在本申请的其他实施例中，第二防回流开关540的第一端541与第二旁路电路510的第二端512电连接且第二防回流开关540的第二端542分别与隔离电路220的第二端222和第一旁路电路210的第二端212电连接。在本实施例中，第二防回流开关540除了可以防止母线电容Cbus经由第二旁路电路510放电外，当第二旁路电路510导通时，第二防回流开关540还可以阻止第一光伏组件230、其他第二光伏组件530经由第二旁路电路510形成电流回路，造成电流过大而出现第二旁路电路510损坏的风险。在本实施例中，第二防回流开关540与第一防回流开关240一样，也为二极管，第二防回流开关540的第一端为二极管的阴极，第二防回流开关540的第二端为二极管的阳极。
第十一实施例
图19是本申请第十一实施例的示意图，图19的示意图与图15的示意图相似，本实施例与第九实施例的主要不同点为不包括第三单元400。
请参见图19，与第九实施例中光伏逆变器包括多个第一单元200和多个第三单元400不同，在本实施例中，所有光伏逆变器仅包括多个第一单元200，不包括第三单元400。
在本实施例中，由于光伏逆变器不包括第三单元400，从而，当驱动控制电路140检测到正直流母线120和负直流母线130出现故障时，驱动控制电路140控制所有隔离电路220断开以使第一光伏组件230与正直流母线120或者负直流母线130断开，从而所有第一光伏组件230向故障点输送能量的通路被隔断，故障点没有能量继续输入，故障不会扩大。
以上对本申请实施例进行了详细介绍，本文中应用了具体个例对本申请的原理及实施方式进行了阐述，以上实施例的说明只是用于帮助理解本申请的方法及其核心思想；同时，对于本领域的一般技术人员，依据本申请的思想，在具体实施方式及应用范围上均会有改变之处，综上所述，本说明书内容不应理解为对本申请的限制。

Claims (7)

  1. 一种光伏逆变器，其特征在于，包括DC/AC变换器、正直流母线、负直流母线、驱动控制电路和至少一个第一单元，所述正直流母线的第一端以及所述负直流母线的第一端分别与所述DC/AC变换器电连接，所述第一单元包括第一旁路电路、隔离电路，其中：
    当所述隔离电路的第一端与所述正直流母线的第二端电连接时，所述隔离电路的第二端用于与第一光伏组件的正输出端电连接，所述负直流母线的第二端用于与所述第一光伏组件的负输出端电连接；所述第一旁路电路的第一端与所述隔离电路的第二端电连接，所述第一旁路电路的第二端与所述负直流母线的第二端电连接；所述驱动控制电路的第一端与所述隔离电路的第三端电连接，所述驱动控制电路的第二端与所述第一旁路电路的第三端电连接，所述驱动控制电路用于在检测到所述正直流母线和负直流母线出现故障后，所述驱动控制电路用于控制所述第一旁路电路的第一端和第二端导通，且用于控制所述隔离电路的第一端和第二端断开以使所述第一光伏组件与所述正直流母线断开，且所述隔离电路断开的时间点晚于所述第一旁路电路导通的时间点；
    或
    当所述隔离电路的第一端与所述负直流母线的第二端电连接时，所述隔离电路的第二端用于与所述第一光伏组件的负输出端电连接，所述正直流母线的第二端用于与所述第一光伏组件的正输出端电连接；所述第一旁路电路的第一端与所述正直流母线的第二端电连接，所述第一旁路电路的第二端与所述隔离电路的第二端电连接；所述驱动控制电路的第一端与所述隔离电路的第三端电连接，所述驱动控制电路的第二端与所述第一旁路电路的第三端电连接，所述驱动控制电路用于在检测到所述正直流母线和负直流母线出现故障后，所述驱动控制电路用于控制所述第一旁路电路的第一端和第二端导通，且用于控制所述隔离电路的第一端和第二端断开以使所述第一光伏组件与所述负直流母线断开，且所述隔离电路断开的时间点晚于所述第一旁路电路导通的时间点。
  2. 如权利要求1所述的光伏逆变器，其特征在于，所述第一旁路电路为常开开关，所述隔离电路为常开分断器，当所述光伏逆变器启动时，所述驱动控制电路用于控制所述第一旁路电路以使隔离电路第一端和第二端之间的压差小于或等于预设电压之后，控制所述隔离电路的第一端和第二端导通以使所述第一光伏组件分别与正直流母线和负直流母线连通；在所述隔离电路导通后，所述驱动控制电路还用于控制所述第一旁路电路的第一端和第二端断开以完成光伏逆变器的启动。
  3. 如权利要求1所述的光伏逆变器，其特征在于，所述第一单元还包括至少一个第二单元，所述第二单元包括第二旁路电路；
    当所述隔离电路的第一端与所述正直流母线的第二端电连接时，所述第二旁路电路的第一端与所述隔离电路的第二端电连接且用于与第二光伏组件的第一端电连接，所述第二旁路电路的第二端与所述负直流母线的第二端电连接且用于与第二光伏组件的第二端电连接，所述驱动控制电路的第二端与所述第二旁路电路的第三端电连接，所述驱动控制电路 用于在检测到所述正直流母线和负直流母线出现故障后，所述驱动控制电路用于控制所述第二旁路电路的第一端和第二端导通，且用于控制所述隔离电路的第一端和第二端断开以使所述第二光伏组件与所述正直流母线断开，且所述隔离电路断开的时间点晚于所述第二旁路电路导通的时间点；
    或
    当所述隔离电路的第一端与所述负直流母线的第二端电连接时，所述第二旁路电路的第一端与所述正直流母线的第二端电连接且用于与第二光伏组件的第一端电连接，所述第二旁路电路的第二端与所述隔离电路的第二端电连接且用于与第二光伏组件的第二端电连接，所述驱动控制电路的第二端与所述第二旁路电路的第三端电连接，所述驱动控制电路用于在检测到所述正直流母线和负直流母线出现故障后，所述驱动控制电路用于控制所述第二旁路电路的第一端和第二端导通，且用于控制所述隔离电路的第一端和第二端断开以使所述第二光伏组件与所述负直流母线断开，且所述隔离电路断开的时间点晚于所述第二旁路电路导通的时间点。
  4. 如权利要求1所述的光伏逆变器，其特征在于，所述光伏逆变器还包括母线电容，所述母线电容的两端分别与所述正直流母线、负直流母线电连接，所述第一单元还包括第一防回流开关；
    当所述隔离电路的第一端与所述正直流母线的第二端电连接时，所述第一防回流开关的第一端与所述正直流母线的第二端电连接且所述第一防回流开关的第二端与所述隔离电路的第一端电连接，或者，所述第一防回流开关的第一端与所述隔离电路的第二端电连接且所述第一防回流开关的第二端与所述第一旁路电路的第一端电连接，或者，所述第一防回流开关的第一端与所述第一旁路电路的第二端电连接且所述第一防回流开关的第二端与所述负直流母线的第二端电连接，在所述第一旁路电路导通后所述第一防回流开关用于阻止所述母线电容经由所述第一旁路电路放电；
    或
    当所述隔离电路的第一端与所述负直流母线的第二端电连接时，所述第一防回流开关的第一端与所述正直流母线的第二端电连接且所述第一防回流开关的第二端与所述第一旁路电路的第一端电连接，或者，所述第一防回流开关的第一端与所述第一旁路电路的第二端电连接且所述第一防回流开关的第二端与所述隔离电路的第二端电连接，或者，所述第一防回流开关的第一端与所述隔离电路的第一端电连接且所述第一防回流开关的第二端与所述负直流母线的第二端电连接；在所述第一旁路电路导通后所述第一防回流开关用于阻止所述母线电容经由所述第一旁路电路放电。
  5. 如权利要求3所述的光伏逆变器，其特征在于，所述光伏逆变器还包括母线电容，所述母线电容的两端分别与所述正直流母线、负直流母线电连接，所述第一单元还包括第一防回流开关；
    当所述隔离电路的第一端与所述正直流母线的第二端电连接时，所述第一防回流开关的第一端分别与所述隔离电路的第二端和第二旁路电路的第一端电连接且所述第一防回流 开关的第二端与所述第一旁路电路的第一端电连接，或者，所述第一防回流开关的第一端与所述第一旁路电路的第二端电连接且所述第一防回流开关的第二端分别与所述负直流母线的第二端和第二旁路电路的第二端电连接，在所述第一旁路电路导通后所述第一防回流开关用于阻止所述母线电容、所述第二光伏组件经由所述第一旁路电路放电；
    或
    当所述隔离电路的第一端与所述负直流母线的第二端电连接时，所述第一防回流开关的第一端分别与所述正直流母线的第二端和第二旁路电路的第一端电连接且所述第一防回流开关的第二端与所述第一旁路电路的第一端电连接，或者，所述第一防回流开关的第一端与所述第一旁路电路的第二端电连接且所述第一防回流开关的第二端分别与隔离电路的第二端和第二旁路电路的第二端电连接；在所述第一旁路电路导通后所述第一防回流开关用于阻止所述母线电容、所述第二光伏组件经由所述第一旁路电路放电。
  6. 如权利要求3所述的光伏逆变器，其特征在于，所述光伏逆变器还包括母线电容，所述母线电容的两端分别与所述正直流母线、负直流母线电连接，所述第二单元还包括第二防回流开关；
    当所述隔离电路的第一端与所述正直流母线的第二端电连接时，所述第二防回流开关的第一端分别与所述隔离电路的第二端和第一旁路电路的第一端电连接且所述第二防回流开关的第二端与所述第二旁路电路的第一端电连接，或者，所述第二防回流开关的第一端与所述第二旁路电路的第二端电连接且所述第二防回流开关的第二端分别与所述负直流母线的第二端和第一旁路电路的第二端电连接，在所述第二旁路电路导通后所述第二防回流开关用于阻止所述母线电容、所述第一光伏组件经由所述第二旁路电路放电；
    或
    当所述隔离电路的第一端与所述负直流母线的第二端电连接时，所述第二防回流开关的第一端分别与所述正直流母线的第二端和第一旁路电路的第一端电连接且所述第二防回流开关的第二端与所述第二旁路电路的第一端电连接，或者，所述第二防回流开关的第一端与所述第二旁路电路的第二端电连接且所述第二防回流开关的第二端分别与所述隔离电路的第二端和第一旁路电路的第二端电连接；在所述第二旁路电路导通后所述第二防回流开关用于阻止所述母线电容、所述第一光伏组件经由所述第二旁路电路放电。
  7. 一种光伏发电系统，其特征在于，包括如权利要求1-6任意一项所述的光伏逆变器，所述光伏发电系统还包括第一光伏组件，所述第一光伏组件与所述光伏逆变器电连接。
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