WO2022110685A1 - 中点箝位逆变器及光伏供电系统 - Google Patents

中点箝位逆变器及光伏供电系统 Download PDF

Info

Publication number
WO2022110685A1
WO2022110685A1 PCT/CN2021/094124 CN2021094124W WO2022110685A1 WO 2022110685 A1 WO2022110685 A1 WO 2022110685A1 CN 2021094124 W CN2021094124 W CN 2021094124W WO 2022110685 A1 WO2022110685 A1 WO 2022110685A1
Authority
WO
WIPO (PCT)
Prior art keywords
switch
pole
unit
turned
switch unit
Prior art date
Application number
PCT/CN2021/094124
Other languages
English (en)
French (fr)
Inventor
王旭东
王朝辉
石磊
Original Assignee
华为数字能源技术有限公司
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 华为数字能源技术有限公司 filed Critical 华为数字能源技术有限公司
Priority to EP21896200.9A priority Critical patent/EP4250550A1/en
Publication of WO2022110685A1 publication Critical patent/WO2022110685A1/zh
Priority to US18/321,824 priority patent/US20230299690A1/en

Links

Images

Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/483—Converters with outputs that each can have more than two voltages levels
    • H02M7/487—Neutral point clamped inverters
    • 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
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/0048—Circuits or arrangements for reducing losses
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/0048—Circuits or arrangements for reducing losses
    • H02M1/0051—Diode reverse recovery losses
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/0048—Circuits or arrangements for reducing losses
    • H02M1/0054—Transistor switching losses
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
    • H02M1/088—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters for the simultaneous control of series or parallel connected semiconductor devices
    • 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
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/42—Circuits or arrangements for compensating for or adjusting power factor in converters or inverters
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/003—Constructional details, e.g. physical layout, assembly, wiring or busbar connections
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
    • H02M7/539—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters with automatic control of output wave form or frequency
    • H02M7/5395—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters with automatic control of output wave form or frequency by pulse-width modulation

Definitions

  • the present application relates to the field of electronic circuits, and in particular, to a midpoint clamp inverter and a photovoltaic power supply system.
  • a typical three-level NPC inverter may include external switch tubes. And the internal switch tube, usually through the fixed internal switch tube to bear the loss (such as switching loss or conduction loss) of the three-level NPC inverter running under different working conditions.
  • the loss such as switching loss or conduction loss
  • the internal switch tube will generate conduction loss, so it is suitable to choose a switching device with low conduction loss.
  • the internal switch tube will generate switching loss, so it is suitable to choose a switching device with low switching loss.
  • the switching loss of the switching device with low conduction loss is too large, it cannot meet the low switching loss and low conduction loss of the inner switch at the same time, that is, the high-efficiency operation of the three-level NPC inverter cannot be guaranteed under all operating conditions. , the loss is too large and the efficiency is low.
  • the present application provides a midpoint clamped inverter and a photovoltaic power supply system, which can flexibly select different switching units to bear the conduction loss or switching loss, thereby reducing the loss of the midpoint clamped inverter under all working conditions, and the efficiency High and strong applicability.
  • the present application provides a midpoint clamped inverter, which may include a power supply module, a switch module, and a control module.
  • the power supply module may include a power supply, and a first capacitor and a second capacitor connected in series and in parallel to both ends of the power supply.
  • the above-mentioned switch module may include a first switch unit, a second switch unit and a third switch unit.
  • the first connection end of the first switch unit is connected to the positive pole of the power supply
  • the second connection end of the first switch unit is connected to the first connection end of the third switch unit
  • the third connection end of the first switch unit is connected to the second switch unit
  • the first connection end of the second switch unit is connected to the load
  • the second connection end of the second switch unit is connected to the second connection end of the third switch unit
  • the third connection end of the second switch unit is connected to the negative pole of the power supply and the load
  • the third connection end of the third switch unit is connected to the negative pole of the power supply and the load.
  • the three connecting terminals are connected to the first capacitor and the second capacitor.
  • Any switch unit in the switch module herein may include at least one switch and/or diode.
  • the above-mentioned control module can be respectively connected to the first switch unit, the second switch unit and the third switch unit.
  • the control module can be used to control the switching on or off of each of the first switching unit, the second switching unit and the third switching unit, so as to select different switching units in the switching module to bear the conduction loss or switching loss.
  • the on or off of different switching units can be controlled by the control module, so that different switching units can be flexibly selected to bear the conduction loss or switching loss under different working conditions, In turn, the loss of the inverter under all operating conditions is reduced, the operating efficiency of the inverter is improved, and the flexibility and adaptability are stronger.
  • the neutral point clamped inverter may further include a filtering module.
  • the filter module may include an inductor and a third capacitor, one end of the inductor is respectively connected to the third connection end of the first switch unit and the first connection end of the second switch unit, the other end of the inductor is respectively connected to one end of the third capacitor and the load, the third The other end of the three capacitors is connected to the second connection end of the second switch unit and the load.
  • the ripple in the output voltage of the inverter can be filtered out by a filter module, so as to obtain an alternating current signal with better properties, high efficiency and stronger applicability.
  • the third switch unit may include a first switch, a first diode and a second diode.
  • the cathode of the first diode is connected to the first pole of the first switch as the first connection terminal of the third switch unit, and the anode of the second diode is connected to the second pole of the first switch as the third switch unit.
  • the anode of the first diode is connected to the cathode of the second diode as the third connection terminal of the third switch unit.
  • the first switch can be selected to bear the switching loss or conduction of the mid-point clamped inverter under different operating conditions (such as outputting active power or outputting reactive power). Therefore, the loss of the inverter under all operating conditions is reduced, the operating efficiency of the inverter is improved, and the adaptability is stronger.
  • the first switch unit may include a second switch and a third switch
  • the second switch unit may include a fourth switch and a fifth switch.
  • the first pole of the second switch is used as the first connection terminal of the first switch unit
  • the second pole of the second switch is connected to the first pole of the third switch as the second connection terminal of the first switch unit
  • the third switch The second pole of the fourth switch is used as the third connection terminal of the first switch unit
  • the first pole of the fourth switch is used as the first connection terminal of the second switch unit
  • the second pole of the fourth switch is connected to the first pole of the fifth switch as The second connection terminal of the second switch unit and the second pole of the fifth switch serve as the third connection terminal of the second switch unit.
  • the above-mentioned control module is respectively connected to the third poles of the switches in the first switch, the second switch, the third switch, the fourth switch and the fifth switch, so as to control the turn-on or turn-off of the switches.
  • the first electrode here may be the collector or drain of different types of switches
  • the second electrode may be the emitter or source of different types of switches
  • the third electrode may be the base or gate of different types of switches.
  • switches such as the first switch, the third switch or the fourth switch
  • different switches can be flexibly selected to bear the switching losses of the neutral point clamped inverter under different operating conditions Or conduction loss, thereby reducing the loss of the inverter under all operating conditions, improving the operating efficiency of the inverter, and being more flexible and adaptable.
  • control module is configured to control the switching of each of the first switch, the second switch, the third switch, the fourth switch and the fifth switch Turn on or off to select the first switch, the third switch and the fourth switch to bear the conduction loss based on the parallel current path when the neutral point clamped inverter outputs active power to the load;
  • the first switch is selected to bear the switching loss
  • the third switch or the fourth switch is selected to bear the conduction loss
  • the first switch is selected to bear the conduction loss
  • the third switch or the fourth switch is selected to bear the switching loss.
  • the first switch, the third switch and the fourth switch can be selected to independently undertake or jointly undertake the operation under different working conditions (such as outputting active power or outputting reactive power). Switching loss or conduction loss, thereby reducing the loss of the inverter under all operating conditions, improving the operating efficiency of the inverter, and making it more adaptable.
  • the first switch, the second switch, the third switch, the fourth switch or the The five switches can be insulated gate bipolar transistors (insulated gate bipolar transistors, which may be referred to as IGBTs for short), or metal-oxide-semiconductor field-effect transistors (metal-oxide-semiconductor field-effect transistors, which may be referred to as MOSFETs for short).
  • IGBT insulated gate bipolar transistors
  • MOSFETs metal-oxide-semiconductor field-effect transistors
  • the first switch, the second switch, the third switch, the fourth switch or the fifth switch can be set as switching devices with low conduction loss or low switching loss (such as IGBT or MOSFET), respectively, which can be selected flexibly Different types of switches (such as IGBT or MOSFET) are used to bear the conduction loss or switching loss of the neutral-point clamped inverter under different operating conditions, thereby reducing the loss of the inverter under all operating conditions and improving the inverter. The inverter operation efficiency, flexibility and applicability are stronger.
  • low conduction loss or low switching loss such as IGBT or MOSFET
  • the first switch, the second switch, the third switch, the fourth switch or the fifth switch may be made of silicon semiconductor material Si, or the first switch
  • the third-generation wide bandgap semiconductor material is made of silicon carbide SiC, or gallium nitride GaN, or diamond, or zinc oxide ZnO, or other materials.
  • the first switch may be a MOSFET
  • the second switch, the third The switch, the fourth switch and the fifth switch may be IGBTs.
  • the first pole, the second pole and the third pole of the first switch are the drain, source and gate of the first switch, respectively, and each of the switches in the second switch, the third switch, the fourth switch and the fifth switch
  • the first pole of each switch is the collector of each switch
  • the second pole of each switch is the emitter of each switch
  • the third pole of each switch is the base of each switch.
  • the MOSFET can be used as the first switch
  • the IGBT can be used as the second switch, the third switch, the fourth switch, and the fifth switch.
  • the midpoint clamp inverter outputs reactive power to the load, it can be
  • the first switch with low switching loss is selected to bear the switching loss
  • the third switch or the fourth switch with low conduction loss is selected to bear the conduction loss, thereby reducing the loss of the inverter under all operating conditions and improving the inverter performance. Operational efficiency, stronger adaptability.
  • the first switch, the second switch and the fifth switch may be The IGBT, the third switch and the fourth switch may be MOSFETs.
  • the first pole of each switch in the first switch, the second switch and the fifth switch is the collector of each switch
  • the second pole of each switch is the emitter of each switch
  • the third pole of each switch is the base of each switch
  • the first pole of the third switch and the fourth switch is the drain of the third switch and the fourth switch
  • the second pole of the third switch and the fourth switch is the source of the third switch and the fourth switch
  • the third switch and the fourth switch The third pole of the four switches is the gate of the third switch and the fourth switch.
  • the IGBT can be used as the first switch
  • the MOSFET can be used as the third switch and the fourth switch.
  • the first switch When the midpoint clamp inverter outputs active power to the load, the first switch can be selected.
  • the first switch, the third switch and the fourth switch bear the conduction loss based on the parallel current path.
  • the first switch with low conduction loss can be selected to bear the conduction loss.
  • the third switch or the fourth switch with low switching loss is selected to bear the switching loss, thereby reducing the loss of the inverter under all operating conditions, improving the operating efficiency of the inverter, and being more adaptable.
  • control module may be used to generate a control module for controlling the first switch, The control signal of each switch in the second switch, the third switch, the fourth switch and the fifth switch.
  • the control signal here is used to control the turn-on or turn-off of each switch, so as to realize turn-on or turn-off of each switch unit.
  • each switch can be controlled by the control signal generated by the control module, so that different switches can be flexibly selected to bear the switching loss or conduction loss under different working conditions independently or jointly, thereby reducing the It reduces the loss of the inverter under all working conditions, improves the operating efficiency of the inverter, and has stronger flexibility and adaptability.
  • control module may be configured to: control the first switch to be turned on, and control the fourth switch to be turned on after the first preset delay time , the first switch is controlled to be turned off after the second preset delay time after the fourth switch is controlled to be turned off; the first switch is controlled to be turned on, and the third switch is controlled to be turned on after the third preset delay time, and the The first switch is controlled to be turned off after a fourth preset delay time after the three switches are turned off.
  • the control module can control the turn-on or turn-off of the first switch, the third switch and the fourth switch based on different preset delay times, so that the first switch can be selected to clamp the inverter at the midpoint Under the condition that the device outputs reactive power to the load, it bears the switching loss, and the third switch or the fourth switch is selected to bear the conduction loss under different working conditions, because the first switch here is a switching device with low switching loss (such as MOSFET), and the third switch and the fourth switch are switching devices with low conduction loss (such as IGBT), thus reducing the loss of the inverter under all operating conditions, improving the operating efficiency of the inverter, and being more adaptable .
  • the first switch here is a switching device with low switching loss (such as MOSFET)
  • the third switch and the fourth switch are switching devices with low conduction loss (such as IGBT)
  • the control module may be configured to: control the fourth switch to be turned on, and control the first switch to be turned on after the first preset delay time turn on, control the fourth switch to turn off after the second preset delay time after controlling the first switch to turn off; control the third switch to turn on, and control the first switch to turn on after the third preset delay time, and control the The third switch is controlled to be turned off after a fourth preset delay time after the first switch is turned off.
  • the first switch, the third switch and the fourth switch can be turned on or off by the control module based on different preset delay times, so that the first switch, the third switch and the fourth switch can be selected.
  • the switches bear the conduction loss when outputting active power based on the parallel current path, while selecting the first switch to bear the conduction loss when outputting reactive power, and selecting the third switch or the fourth switch to bear the conduction loss when outputting reactive power.
  • Switching loss because the first switch here is a switching device with low conduction loss (such as IGBT), and the third switch and the fourth switch are switching devices with low switching loss (such as MOSFET), thus reducing the inverter in all
  • the loss under working conditions improves the operating efficiency of the inverter and makes it more adaptable.
  • the control module is configured to The device junction temperature corresponding to each of the switches, the fourth switch, and the fifth switch, and/or the load current flowing through the load, determine the first preset delay time, the second preset delay time, the third preset delay time, and The fourth preset delay time.
  • different preset delay times can be determined by the control module, and the first switch, the third switch and the fourth switch can be turned on or off based on the different preset delay times, so that the first switch, the third switch and the fourth switch can be selected.
  • the first switch, the third switch and the fourth switch independently or jointly undertake the switching loss or conduction loss under different working conditions, thereby reducing the loss of the inverter under all working conditions and improving the operating efficiency of the inverter , more adaptable.
  • the present application provides a photovoltaic power supply system.
  • the photovoltaic power supply system may include a photovoltaic array and any one of the above-mentioned first aspect to the twelfth possible implementation manner of the first aspect connected to the photovoltaic array. Supplied with a midpoint clamped inverter. It can be understood that the photovoltaic array here can be connected to the DC side of the neutral point clamp inverter to provide a DC input voltage for the neutral point clamp inverter, and the AC side of the neutral point clamp inverter can be connected to the load to Provide AC power to the load.
  • the photovoltaic array may include a plurality of photovoltaic components (also referred to as solar panels or photovoltaic panels) and/or other photovoltaic power supply devices.
  • the neutral-point clamped inverter can flexibly select different switching units based on the control module to bear the switching loss or conduction loss under different working conditions (such as outputting active power or outputting reactive power), thereby reducing the It reduces the loss of the inverter under all working conditions, improves the operating efficiency of the inverter, and has stronger flexibility and adaptability.
  • FIG. 1 is a schematic diagram of an application scenario of a neutral-point clamped inverter provided by the present application
  • FIG. 2 is a schematic circuit diagram of a neutral point clamped inverter provided by the present application
  • FIG. 3 is another schematic circuit diagram of the neutral point clamped inverter provided by the present application.
  • FIG. 4 is another schematic circuit diagram of the neutral point clamped inverter provided by the present application.
  • FIG. 5 is a schematic diagram of a switching sequence of the neutral point clamped inverter provided by the present application.
  • FIG. 6 is a schematic diagram of a commutation loop when the neutral point clamped inverter provided by the present application outputs active power
  • FIG. 7 is a schematic diagram of a commutation circuit when the neutral point clamp inverter provided by the present application outputs reactive power
  • FIG. 8 is another schematic circuit diagram of the neutral point clamped inverter provided by the present application.
  • FIG. 9 is another switching sequence diagram of the neutral point clamped inverter provided by the present application.
  • FIG. 10 is a schematic diagram of another commutation circuit when the midpoint clamped inverter provided by the present application outputs active power
  • 11 is a schematic diagram of another commutation circuit when the neutral point clamped inverter provided by the present application outputs reactive power;
  • FIG. 12 is another schematic circuit diagram of the neutral point clamped inverter provided by the present application.
  • Inverter is a converter that can convert direct current (such as batteries, storage batteries) into constant frequency and constant voltage or frequency modulation and voltage regulation alternating current.
  • Inverters (such as neutral point clamp inverters) can generally be composed of inverter bridge circuits, control logic circuits and filter circuits, and are widely used in electrical equipment (such as household equipment) and power grids.
  • the battery can be connected through the inverter.
  • Drive electrical equipment to work, or can also transmit high-power high-voltage alternating current to the grid through the inverter.
  • the midpoint clamped inverter provided in this application may also be referred to as an NPC inverter, a three-level midpoint clamped inverter or a three-level NPC inverter, and the midpoint clamped inverter is suitable for photovoltaic applications Power generation (such as supplying household equipment (such as refrigerators, air conditioners) or power grids), or wind power generation, or high-power converters (such as converting direct current into high-power high-voltage alternating current) and other application areas, the specific can be based on The actual application scenario is determined and is not limited here.
  • Power generation such as supplying household equipment (such as refrigerators, air conditioners) or power grids
  • wind power generation or high-power converters (such as converting direct current into high-power high-voltage alternating current) and other application areas
  • high-power converters such as converting direct current into high-power high-voltage alternating current
  • the neutral point clamped inverter may include a power module, a switch module and a control module.
  • the power supply module may include a power supply, and a first capacitor and a second capacitor connected in series and parallel to both ends of the power supply.
  • the above-mentioned switch module may include a first switch unit, a second switch unit and a third switch unit.
  • the above-mentioned control module can be respectively connected to the first switch unit, the second switch unit and the third switch unit.
  • the control module can be used to control the switching on or off of each of the first switching unit, the second switching unit and the third switching unit, so as to select different switching units in the switching module to bear the conduction loss or switching loss.
  • the neutral-point clamped inverter provided by this application can flexibly select different switching units based on the control module to bear the switching loss or conduction loss under different working conditions (such as outputting active power or outputting reactive power), thereby reducing the It reduces the loss of the inverter under all working conditions, improves the operating efficiency of the inverter, and has stronger flexibility and adaptability.
  • the neutral point clamp inverter provided in this application can be adapted to different application scenarios, for example, any application scenario that needs to convert DC power into AC power, such as solar power supply scenarios and wind power supply scenarios, etc. This application uses solar power to supply power. Scenario as an example.
  • FIG. 1 is a schematic diagram of an application scenario of the neutral point clamped inverter provided by the present application.
  • a photovoltaic power supply system (such as photovoltaic power supply system 10 ) may include a photovoltaic array (such as photovoltaic array 1 ) and a midpoint clamp inverter (such as a midpoint clamp inverter) connected to the photovoltaic array 2).
  • the photovoltaic array 1 may include a plurality of photovoltaic components (also referred to as solar cell panels or photovoltaic panels) and/or other photovoltaic power supply devices (such as photovoltaic junction boxes).
  • the photovoltaic array 1 here can be connected to the DC side of the neutral point clamping inverter 2 to provide a DC input voltage for the neutral point clamping inverter 2 .
  • the photovoltaic array 1 provides DC power to the neutral point clamped inverter 2 .
  • the voltage value of the DC input voltage may be 12V, 24V, 36V, 48V DC or other voltage values.
  • the AC side of the neutral point clamp inverter 2 can be directly or indirectly connected to a load (such as a household device 3 or a power grid 5 ), and the neutral point clamp inverter 2 can convert the direct current provided by the photovoltaic array 1 into alternating current (such as 220V, 50Hz sine wave alternating current or alternating current with other voltage values), and supply power to household equipment 3 (such as refrigerators, air conditioners, etc.).
  • a load such as a household device 3 or a power grid 5
  • the neutral point clamp inverter 2 can convert the direct current provided by the photovoltaic array 1 into alternating current (such as 220V, 50Hz sine wave alternating current or alternating current with other voltage values), and supply power to household equipment 3 (such as refrigerators, air conditioners, etc.).
  • the neutral point clamp inverter 2 can also input alternating current to the booster 4, and the booster 4 can boost the alternating current input from the neutral point clamp inverter 2 to high voltage (such as 32KV, 110KV).
  • the neutral-point clamped inverter in the present application can reduce losses under all operating conditions, improve the operating efficiency of the inverter, further improve the power supply efficiency, and has better applicability powerful.
  • FIG. 2 is a schematic circuit diagram of a neutral point clamped inverter provided by the present application.
  • the neutral point clamped inverter may include a power module 10 , a switch module 20 and a control module 30 .
  • the power supply module 10 may include a power supply, and a first capacitor C1 and a second capacitor C2 connected in series and in parallel to both ends of the power supply.
  • the power supply here is a DC input power supply
  • the power supply voltage may be V dc
  • the first capacitor C1 and the second capacitor C2 may be DC bus capacitors
  • the switch module 20 may include at least one switch unit, for example, may specifically include a first switch unit 201 , a second switch unit 202 and a third switch unit 203 .
  • the first connection end of the first switch unit 201 may be connected to the positive pole of the power supply, the second connection end of the first switch unit 201 may be connected to the first connection end of the third switch unit 203 , and the third connection end of the first switch unit 201
  • the terminal can be connected to the first connection terminal of the second switch unit 202 and the load, the second connection terminal of the second switch unit 202 can be connected to the second connection terminal of the third switch unit 203, and the third connection terminal of the second switch unit 202 can be
  • the negative terminal of the power supply is connected to the load, and the third connection terminal of the third switch unit 203 can be connected to the first capacitor C1 and the second capacitor C2.
  • any switch unit in the switch module 20 may include at least one switch and/or diode, or any switch unit may include at least one switch and/or diode and/or capacitance and/or inductance and/or other devices , which can be determined according to the actual application scenario, and is not limited here.
  • the control module 30 can be connected to the first switch unit 201 , the second switch unit 202 and the third switch unit 203 respectively, and the control module 30 can control each of the first switch unit 201 , the second switch unit 202 and the third switch unit 203 .
  • the switch unit is turned on or off to select any one of the first switch unit 201 , the second switch unit 202 and the third switch unit 203 to independently bear the conduction loss or switching loss, or to select the first switch unit 201 , any two switch units or three switch units in the second switch unit 202 and the third switch unit 203 jointly bear the conduction loss or switching loss, so that different switch units in the switch module 20 can be flexibly selected to directly bear or jointly bear Bearing the conduction loss or switching loss of the mid-point clamped inverter under different working conditions, it is more flexible and adaptable.
  • FIG. 3 is another schematic circuit diagram of the neutral point clamped inverter provided by the present application.
  • the midpoint clamped inverter shown in FIG. 2 may further include a filter module 40 , and the filter module 40 may include an inductor L and a third capacitor C3 , and one end of the inductor L is connected to the first The third connection end of the switch unit 201 and the first connection end of the second switch unit 202, the other end of the inductor L is respectively connected to one end of the third capacitor C3 and the load, and the other end of the third capacitor C3 is connected to the second switch unit 202.
  • the second connection terminal and the load Please refer to FIG. 4 together.
  • FIG. 4 Please refer to FIG. 4 together.
  • the first switch unit 201 shown in FIG. 3 may include a second switch S1 and a third switch S2, and the second switch unit 202 shown in FIG. 3 may include a fourth switch S3 and a third switch S2.
  • Five switches S4, the third switch unit 203 shown in FIG. 3 may include a first switch Q5, a first diode D5 and a second diode D6.
  • the second switch S1 may include a switching device Q1 and a freewheeling diode D1 connected in parallel to both ends of the switching device Q1
  • the third switch S2 may include a switching device Q2 and a freewheeling diode D2 connected in parallel to both ends of the switching device Q2
  • the fourth The switch S3 may include a switching device Q3 and a freewheeling diode D3 connected in parallel to both ends of the switching device Q3
  • the fifth switch S4 may include a switching device Q4 and a freewheeling diode D4 connected in parallel to both ends of the switching device Q4.
  • the first pole of the second switch S1 is used as the first connection terminal of the first switch unit 201, and the second pole of the second switch S1 is connected to the first pole of the third switch S2 as the first connection terminal
  • the second connection terminal of the switch unit 201 and the second pole of the third switch S2 serve as the third connection terminal of the first switch unit 201 .
  • the first pole of the fourth switch S3 serves as the first connection terminal of the second switch unit 202, and the second pole of the fourth switch S3 is connected to the first pole of the fifth switch S4 as the second pole
  • the second connection terminal of the switch unit 202 and the second pole of the fifth switch S4 serve as the third connection terminal of the second switch unit 202 .
  • the cathode of the first diode D5 is connected to the first pole of the first switch Q5 as the first connection terminal of the third switch unit 203, and the anode of the second diode D6 is connected to the first pole of the first switch Q5.
  • the second pole of the switch Q5 is connected as the second connection terminal of the third switch unit 203 , and the anode of the first diode D5 and the cathode of the second diode D6 are connected as the third connection terminal of the third switch unit 203 . As shown in FIG.
  • the control module 30 can be respectively connected to the third poles of the switches in the first switch Q5 , the second switch S1 , the third switch S2 , the fourth switch S3 and the fifth switch S4 , so as to control the on or off.
  • the first electrode may be the collector or drain of different types of switches
  • the second electrode may be the emitter or source of different types of switches
  • the third electrode may be the base or gate of different types of switches.
  • the first switch Q5, the second switch S1, the third switch S2, the fourth switch S3 or the fifth switch S4 may be made of silicon semiconductor material (silicon, Si), or the third-generation wide-gap Silicon carbide (SiC) with semiconductor material, or gallium nitride (GaN), or diamond (diamond), or zinc oxide (zinc oxide, ZnO), or MOSFET, IGBT or other materials made of
  • the diode can be specifically determined according to the actual application scenario, and is not limited here. For example, as shown in FIG.
  • the first switch Q5 may be a MOSFET, and the second switch S1 , the third switch S2 , the fourth switch S3 , and the fifth switch S4 may be IGBTs. It can be understood that the first electrode, the second electrode and the third electrode of the first switch Q5 are the drain electrode, the source electrode and the gate electrode of the first switch Q5, respectively.
  • the first pole of each switch in the second switch S1, the third switch S2, the fourth switch S3, and the fifth switch S4 may be each of the switches in the second switch S1, the third switch S2, the fourth switch S3, and the fifth switch S4.
  • the collector of each switch in the second switch S1, the third switch S2, the fourth switch S3, and the fifth switch S4 can be the second switch S1, the third switch S2, the fourth switch S3, and the fifth switch.
  • the emitter of each switch in S4, the third pole of each switch in the second switch S1, the third switch S2, the fourth switch S3, and the fifth switch S4 can be the second switch S1, the third switch S2, the fourth switch S3 , the base of each switch in the fifth switch S4.
  • the control module 30 may generate a control signal for controlling the first switch Q5, the second switch S1, the third switch S2, the fourth switch S3 and the fifth switch S4, for example, the control signal may be the first switch Q5, the second switch S1, the third switch S2, the fourth switch S3 and the fifth switch S4.
  • the pulse width modulation (pulse width modulation, PWM) signals of a switch Q5 , the second switch S1 , the third switch S2 , the fourth switch S3 and the fifth switch S4 may be referred to as PWM signals for short.
  • the control signal can also be understood as a PWM signal used to control the switching device Q1 , the switching device Q2 , the switching device Q3 , the switching device Q4 and the first switch Q5 .
  • the control signal here can be used to control each of the first switch Q5 , the second switch S1 , the third switch S2 , the fourth switch S3 and the fifth switch S4 to be turned on or off.
  • the control signal can be (0 1 1 0 1), which can control the second switch S1 to be turned off, the third switch S2 to be turned on, the fourth switch S3 to be turned on, the fifth switch S4 to be turned off, and the first switch Q5 to be turned on .
  • FIG. 5 is a schematic diagram of a switching sequence of the neutral point clamped inverter provided by the present application. As shown in FIG.
  • the third switch S2 when the output voltage V out of the neutral-point clamped inverter is in a positive half cycle (ie, a positive half cycle), the third switch S2 is kept on, and the fifth switch S4 is kept off (ie, off). state).
  • the second switch S1 , the fourth switch S3 and the first switch Q5 may operate in a PWM mode, and the second switch S1 and the first switch Q5 may be complementary switches.
  • the PWM mode is an effective mode in which the digital output signal of the microprocessor (such as the control module 30) is used to control the analog circuit
  • the complementary switch is a pair of push-pull switches. When one of the switches is closed, the other is closed.
  • the switch is turned off, for example, the second switch S1 is turned on and the first switch Q5 is turned off, or the second switch S1 is turned off and the first switch Q5 is turned on.
  • the second switch S1 and the first switch Q5 as complementary switches, in order to prevent the second switch S1 and the first switch Q5 from being turned on at the same time, a dead time needs to be added between the second switch S1 and the first switch Q5, For example, t d1 or t d2 , where t d1 may be the dead time from the moment when the second switch S1 is turned off to the moment when the first switch Q5 is turned on, and t d2 may be the time from the moment when the first switch Q5 is turned off to the moment when the first switch Q5 is turned off.
  • the fourth switch S3 is kept on, and the second switch S1 is kept off (ie, off).
  • the third switch S2, the fifth switch S4 and the first switch Q5 work in the PWM mode, and the fifth switch S4 and the first switch Q5 are complementary switches.
  • a dead time needs to be added between the fifth switch S4 and the first switch Q5,
  • t d3 or t d4 where t d3 may be the dead time from the moment when the fifth switch S4 is turned off to the moment when the first switch Q5 is turned on, and t d4 may be the time from the moment when the first switch Q5 is turned off to the moment when the first switch Q5 is turned off.
  • each of the first switch Q5 , the second switch S1 , the third switch S2 , the fourth switch S3 and the fifth switch S4 in the control module 30 are switches of different types (eg, IGBT or MOSFET).
  • different first preset time, second preset time, third preset time and fourth preset time can be set to control the conduction between the first switch Q5, the third switch S2 and the fourth switch S3 or shut down.
  • the control module 30 may control the first switch Q5 to be turned on, and control the fourth switch S3 to be turned on after the first preset delay time (eg, the preset delay time t delay1 ), and the second preset after the fourth switch S3 is controlled to be turned off After the delay time (eg, the preset delay time t delay2 ), the first switch Q5 is controlled to be turned off; or when the output voltage V out of the mid-point clamped inverter is in the negative half cycle, the control module 30 may also control the first switch Q5 to conduct turn on, and control the third switch S2 to turn on after a third preset delay time (such as a preset delay time t delay3 ), and control a fourth preset delay time (such as a preset delay time)
  • FIG. 6 is a schematic diagram of a commutation circuit when the neutral point clamped inverter provided by the present application outputs active power.
  • the neutral point clamp inverter when the output voltage V out of the neutral point clamp inverter is in the positive half cycle and the load current i 0 is greater than 0, the neutral point clamp inverter outputs active power to the load, in other words, the neutral point clamp inverter outputs active power to the load.
  • the inverter operates in the output active condition.
  • the second switch S1, the fourth switch S3 and the first switch Q5 work in the PWM mode.
  • the commutation circuits in which the switches are in different switching states can be shown as 6a in FIG. 6, where The switch state of the can guide either the on state or the off state (also referred to as the off state).
  • the switching device Q1 when the switching device Q1 is turned on, the current flows through the switching device Q1 and the switching device Q2; when the switching device Q1 is turned off and the first switch Q5 is turned on, two currents exist at the same time.
  • the paths are respectively the current path flowing through the first diode D5, the first switch Q5 and the freewheeling diode D3, and the current path flowing through the first diode D5 and the switching device Q2. Due to the conduction of the switching device Q2 The voltage drop is lower, so the current will flow through the first diode D5 and the switching device Q2; after the preset delay time t delay1 , the switching device Q3 is turned on, and the current still flows through the first diode D5 and the switching device Q2.
  • the switching device Q1 and the first diode D5 participate in the commutation, which will generate switching loss; the switching device Q2 is always on, which will generate conduction loss, and then it can be obtained that the third switch S2 will generate conduction loss; No current flows through Q3 and the first switch Q5, and no loss occurs.
  • the neutral point clamp inverter When the output voltage V out of the neutral point clamp inverter is in the negative half cycle and the load current i 0 is less than 0, the neutral point clamp inverter outputs active power to the load, in other words, the neutral point clamp inverter operates at under active output conditions. Under this condition, the third switch S2, the fifth switch S4 and the first switch Q5 work in the PWM mode. At this time, the commutation loops of the switches in different switching states can be shown as 6b in FIG. 6 .
  • the switching device Q4 When the switching device Q4 is turned on, the current will flow through the switching device Q3 and the switching device Q4; when the switching device Q4 is turned off and the first switch Q5 is turned on, there are two current paths at the same time, namely flowing through the freewheeling diode D2 , the current path of the first switch Q5 and the second diode D6, and the current path flowing through the switching device Q3 and the second diode D6, since the on-voltage drop of the switching device Q3 is lower, the current will flow through The switching device Q3 and the second diode D6; after the preset delay time t delay3 , the switching device Q2 is turned on, and the current still flows through the switching device Q3 and the second diode D6.
  • the switching device Q4 and the second diode D6 participate in the commutation, which will generate switching loss; the switching device Q3 is always on, which will generate conduction loss, and then it can be obtained that the fourth switch S3 will generate conduction loss; No current flows through Q2 and the first switch Q5, and no loss occurs.
  • FIG. 7 is a schematic diagram of a commutation circuit when the neutral point clamped inverter provided by the present application outputs reactive power.
  • the neutral point clamp inverter when the output voltage V out of the neutral point clamped inverter is in the positive half cycle and the load current i 0 is less than 0, the neutral point clamp inverter outputs reactive power to the load, in other words, the neutral point clamped inverter outputs reactive power to the load.
  • the clamped inverter operates under the output reactive power condition. Under this condition, the second switch S1, the fourth switch S3 and the first switch Q5 work in the PWM mode.
  • the commutation circuits in which the switches are in different switching states can be shown as 7a in FIG.
  • the second diode D6 after the preset delay time t delay1 , the switching device Q3 is turned on, and there are two current paths at the same time, that is, the freewheeling diode D2, the first switch Q5 and the second diode
  • the first switch Q5 and the freewheeling diode D1 participate in the commutation, which will generate switching loss; the freewheeling diode D2 will generate conduction loss; the switching device Q3 is in a zero-voltage switching state without switching loss, which will generate conduction loss, Further, it can be obtained that the fourth switch S3 will generate conduction loss, and the zero-voltage switching state here can be understood as the state when the voltage across the switch (eg, the switching device Q3 ) is 0 when it is turned on or off.
  • the neutral point clamp inverter When the output voltage V out of the neutral point clamp inverter is in the negative half cycle and the load current i 0 is greater than 0, the neutral point clamp inverter outputs reactive power to the load, in other words, the neutral point clamp inverter operates in the output reactive power condition. Under this condition, the third switch S2, the fifth switch S4 and the first switch Q5 work in the PWM mode. At this time, the commutation circuits of the switches in different switching states can be shown as 7b in FIG. 7 .
  • the switching device Q4 When the switching device Q4 is turned on, the current will flow through the freewheeling diode D4 and the freewheeling diode D3; when the switching device Q4 is turned off and the first switch Q5 is turned on, the current will flow through the first diode D5, the first switch Q5 and the freewheeling diode D3; after the preset delay time t delay3 , the switching device Q2 is turned on, and there are two current paths at the same time, that is, the first diode D5, the first switch Q5 and the freewheeling diode The current path of D3, as well as the current path through the first diode D5 and the switching device Q2, since the conduction voltage drop of the current path through the first diode D5 and the switching device Q2 is lower, the current will flow through the first diode D5 and the switching device Q2.
  • the first switch Q5 and the freewheeling diode D4 participate in the commutation, which will generate switching loss; the freewheeling diode D3 will generate conduction loss; the switching device Q2 is in a zero-voltage switching state without switching loss, which will generate conduction loss, Further, it can be obtained that the third switch S2 will generate conduction loss.
  • control module 30 can control each switch to be turned on or off to select The third switch S2 or the fourth switch S3 bears the conduction loss, and at the same time, the first switch Q5 is selected to bear the switching loss when the mid-point clamped inverter outputs reactive power to the load.
  • the third switch S2 and the fourth switch S3 are switching devices with low conduction loss, and the first switch Q5 is a switching device with low switching loss, the third switch S2 or the fourth switch S3 with low conduction loss can be used The conduction loss is borne by the first switch Q5 with low switching loss, thereby reducing the operating loss of the mid-point clamped inverter under all operating conditions, improving the operating efficiency of the inverter, and making it more adaptable.
  • FIG. 8 is another schematic circuit diagram of the neutral point clamped inverter provided by the present application.
  • the second switch S1 , the fourth switch S3 and the first switch Q5 may be IGBTs, and the third switch S2 and the fourth switch S3 may be MOSFETs.
  • first pole of each switch in the second switch S1, the fourth switch S3 and the first switch Q5 is the collector of each switch in the second switch S1, the fourth switch S3 and the first switch Q5, the second switch S1,
  • the second pole of each switch in the fourth switch S3 and the first switch Q5 is the emitter of each switch in the second switch S1, the fourth switch S3 and the first switch Q5, the second switch S1, the fourth switch S3 and the first switch
  • the third pole of each switch in Q5 is the base pole of each switch in the second switch S1, the fourth switch S3 and the first switch Q5.
  • the first pole of the third switch S2 and the fourth switch S3 is the drain of the third switch S2 and the fourth switch S3
  • the second pole of the third switch S2 and the fourth switch S3 is the source of the third switch S2 and the fourth switch S3 pole
  • the third pole of the third switch S2 and the third pole of the fourth switch S3 are gates of the third switch S2 and the fourth switch S3.
  • the control module 30 may generate control signals for controlling the first switch Q5 , the second switch S1 , the third switch S2 , the fourth switch S3 and the fifth switch S4 .
  • the control signal here can be used to control the turn-on or turn-off of the second switch S1 , the third switch S2 , the fourth switch S3 , the fifth switch S4 and the first switch Q5 .
  • FIG. 9 is another switching timing diagram of the neutral point clamped inverter provided by the present application. As shown in FIG.
  • the third switch S2 when the output voltage V out of the neutral point clamped inverter is in a positive half cycle, the third switch S2 is kept in an on state, and the fifth switch S4 is kept in an off state.
  • the second switch S1, the fourth switch S3 and the first switch Q5 may work in a PWM mode, and the second switch S1 and the fourth switch S3 may be complementary switches.
  • a dead time needs to be added between the second switch S1 and the fourth switch S3,
  • t d5 or t d6 where t d5 may be the dead time from the time when the second switch S1 is turned off to the time when the fourth switch S3 is turned on, and t d6 may be the time from when the fourth switch S3 is turned off to the time when the fourth switch S3 is turned off.
  • t d5 may be the dead time from the time when the second switch S1 is turned off to the time when the fourth switch S3 is turned on
  • t d6 may be the time from when the fourth switch S3 is turned off to the time when the fourth switch S3 is turned off.
  • the fourth switch S3 When the output voltage V out of the midpoint clamped inverter is in a negative half cycle, the fourth switch S3 is kept in an on state, and the second switch S1 is kept in an off state.
  • the third switch S2, the fifth switch S4 and the first switch Q5 work in the PWM mode, and the third switch S2 and the fifth switch S4 are complementary switches.
  • a dead time needs to be added between the third switch S2 and the fifth switch S4,
  • t d7 or t d8 may be the dead time from the time when the fifth switch S4 is turned off to the time when the third switch S2 is turned on
  • t d8 may be the time from when the third switch S2 is turned off to the time when the third switch S2 is turned off.
  • the control module 30 may control the fourth switch S3 to be turned on, and control the first switch Q5 to be turned on after the first preset delay time (eg, the preset delay time t delay5 ), and then control the first switch S3 to conduct.
  • the first preset delay time eg, the preset delay time t delay5
  • the fourth switch S3 is controlled to be turned off after the second preset delay time (eg, the preset delay time t delay6 ) after the Q5 is turned off; or when the output voltage V out of the mid-point clamped inverter is in the negative half cycle, the control module 30 may also control the third switch S2 to be turned on, and control the first switch Q5 to be turned on after a third preset delay time (eg, a preset delay time t delay7 ), and control the first switch Q5 to be turned off after a fourth preset delay time. After a delay time (eg, a preset delay time t delay8 ) is set, the third switch S2 is controlled to be turned off.
  • a delay time eg, a preset delay time t delay8
  • FIG. 10 is a schematic diagram of another commutation circuit when the neutral point clamped inverter provided by the present application outputs active power.
  • the neutral point clamp inverter when the output voltage V out of the neutral point clamp inverter is in the positive half cycle and the load current i 0 is greater than 0, the neutral point clamp inverter outputs active power to the load, in other words, the neutral point clamp inverter outputs active power to the load.
  • the inverter operates in the output active condition.
  • the second switch S1, the fourth switch S3 and the first switch Q5 work in the PWM mode.
  • the commutation loops of the switches in different switching states can be shown as 10a in FIG. 10 .
  • the switching device Q1 When the switching device Q1 is turned on, the current will flow through the switching device Q1 and the switching device Q2; when the switching device Q1 is turned off and the switching device Q3 is turned on, the current will flow through the first diode D5 and the switching device Q2; After the preset delay time t delay5 , the first switch Q5 is turned on, and there are two current paths at the same time, namely the current path flowing through the first diode D5, the switching device Q2 and the first diode D5, and the current path flowing through the first diode D5, the switching device Q2 and the first diode D5.
  • the conduction loss can be reduced through the two current paths that are conducted in parallel. It can be obtained that the switching device Q1 and the first diode D5 participate in the commutation, which will generate switching loss; the switching device Q2 is always on, which will generate conduction loss, and then it can be obtained that the third switch S2 will generate conduction loss; the first Switch Q5 only produces conduction losses, and freewheeling diode D3 produces conduction losses and reverse recovery losses.
  • the neutral point clamp inverter When the output voltage V out of the neutral point clamp inverter is in the negative half cycle and the load current i 0 is less than 0, the neutral point clamp inverter outputs active power to the load, in other words, the neutral point clamp inverter operates at under active output conditions. Under this condition, the third switch S2, the fifth switch S4 and the first switch Q5 work in the PWM mode. At this time, the commutation loops of the switches in different switching states can be shown as 10b in FIG. 10 .
  • the switching device Q4 When the switching device Q4 is turned on, the current will flow through the switching device Q3 and the switching device Q4; when the switching device Q4 is turned off and the switching device Q2 is turned on, the current will flow through the switching device Q3 and the second diode D6; After the preset delay time t delay7 , the first switch Q5 is turned on. At this time, there are two current paths at the same time, namely the current path flowing through the switching device Q3, the second diode D6 and the freewheeling diode D2, and the current path flowing through the second diode D6 and the freewheeling diode D2. A current path of the switch Q5 and the second diode D6, so that the conduction loss can be reduced through the two current paths that are conducted in parallel.
  • the switching device Q4 and the second diode D6 participate in the commutation, which will generate switching loss; the switching device Q3 is always on, which will generate conduction loss, and then it can be obtained that the fourth switch S3 will generate conduction loss; the first Switch Q5 has conduction losses, and freewheeling diode D2 has conduction losses and reverse recovery losses.
  • FIG. 11 is a schematic diagram of another commutation circuit when the neutral point clamped inverter provided by the present application outputs reactive power.
  • the neutral point clamp inverter when the output voltage V out of the neutral point clamped inverter is in the positive half cycle and the load current i 0 is less than 0, the neutral point clamp inverter outputs reactive power to the load, in other words, the neutral point clamped inverter outputs reactive power to the load.
  • the clamped inverter operates under the output reactive power condition. Under this condition, the second switch S1, the fourth switch S3 and the first switch Q5 work in the PWM mode.
  • the commutation circuits in which the switches are in different switching states can be shown as 11a in FIG. 11 .
  • the switching device Q1 When the switching device Q1 is turned on, the current will flow through the freewheeling diode D2 and the freewheeling diode D1; when the switching device Q1 is turned off and the switching device Q3 is turned on, the current will flow through the switching device Q3 and the second diode D6; After the preset delay time t delay5 , the first switch Q5 is turned on. At this time, two current paths exist at the same time, namely the current path flowing through the freewheeling diode D2, the first switch Q5 and the second diode D6, and the current path flowing through the freewheeling diode D2, the first switch Q5 and the second diode D6.
  • the conduction loss can be reduced through the two current paths that are conducted in parallel. It can be obtained that the switching device Q3 and the freewheeling diode D1 participate in the commutation, which will generate switching losses, and then it can be obtained that the fourth switch S3 will generate switching losses; the freewheeling diode D2 and the second diode D6 will generate conduction losses; A switch Q5 is in a zero-voltage switching state and has no switching loss, which will result in conduction loss.
  • the neutral point clamp inverter When the output voltage V out of the neutral point clamp inverter is in the negative half cycle and the load current i 0 is greater than 0, the neutral point clamp inverter outputs reactive power to the load, in other words, the neutral point clamp inverter operates in the output reactive power condition. Under this condition, the third switch S2, the fifth switch S4 and the first switch Q5 work in the PWM mode. At this time, the commutation circuits of the switches in different switching states can be shown as 11b in FIG. 11 .
  • the switching device Q4 When the switching device Q4 is turned on, the current will flow through the freewheeling diode D4 and the freewheeling diode D3; when the switching device Q4 is turned off and the switching device Q2 is turned on, the current will flow through the first diode D5 and the switching device Q2; After the preset delay time t delay7 , the first switch Q5 is turned on, and at this time there are two current paths, namely the current paths flowing through the first diode D5, the first switch Q5 and the freewheeling diode D3, and The current path flows through the first diode D5 and the switching device Q2, so that the conduction loss can be reduced through the two current paths that are conducted in parallel.
  • the switching device Q2 and the freewheeling diode D4 participate in the commutation, which will generate switching losses, and then it can be obtained that the third switch S2 will generate switching losses; the freewheeling diode D3 and the first diode D5 will generate conduction losses; A switch Q5 is in a zero-voltage switching state and has no switching loss, which will result in conduction loss.
  • the control module 30 can control each switch to be turned on or off to select the third switch S2,
  • the fourth switch S3 and the first switch Q5 are based on parallel conduction current paths to reduce conduction losses.
  • the control module 30 can control each switch to be turned on or off.
  • the first switch Q5 is selected to bear the conduction loss
  • the third switch S2 or the fourth switch S3 is selected to mainly bear the switching loss in the case of outputting reactive power.
  • the switching loss is mainly borne by the third switch S2 and the fourth switch S3 with low switching loss
  • the conduction loss is borne by the first switch Q5 with low conduction loss, thereby reducing the operating loss of the inverter under all operating conditions, improving the operating efficiency of the inverter, and being more adaptable.
  • FIG. 12 is another schematic circuit diagram of the neutral point clamped inverter provided by the present application.
  • the second switch S1 , the third switch S2 , the fourth switch S3 , the fifth switch S4 and the first switch Q5 may be controllable power switching devices, such as IGBT or MOSFET .
  • the third switch S2 is kept in an on state
  • the fifth switch S4 is kept in an off state.
  • the second switch S1, the fourth switch S3 and the first switch Q5 may work in a PWM mode, and the second switch S1 and the fourth switch S3 may be complementary switches.
  • the fourth switch S3 When the output voltage V out of the midpoint clamped inverter is in a positive half cycle, the fourth switch S3 is kept in an on state, and the second switch S1 is kept in an off state.
  • the third switch S2, the fifth switch S4 and the first switch Q5 work in the PWM mode, and the third switch S2 and the fifth switch S4 are complementary switches.
  • control module 30 may also use the device junction temperature corresponding to each of the first switch Q5 , the second switch S1 , the third switch S2 , the fourth switch S3 and the fifth switch S4 , and/or The load current i 0 flowing through the load determines the first preset delay time, the second preset delay time, the third preset delay time and the fourth preset delay time.
  • the device junction temperature of switch j in the second switch S1, the third switch S2, the fourth switch S3, the fifth switch S4 and the first switch Q5 can be represented as T j , where j is greater than 0 and less than or equal to the switch module A positive integer for the number of switches in 20 (eg 5).
  • the first preset delay time is the above-mentioned preset delay time t delay1
  • the second preset delay time is the above-mentioned preset delay time t delay2
  • the third preset delay time is the above-mentioned preset delay time t delay3
  • the fourth preset delay time is the above-mentioned preset delay time t delay3 .
  • the delay time is the above preset delay time t delay4
  • the switching sequence diagram of the midpoint clamped inverter can be as shown in Figure 5 above
  • the schematic diagram of the commutation loop of the midpoint clamped inverter can be as shown in the above Figure 6- shown in Figure 7.
  • the switching sequence diagram of the midpoint clamped inverter can be as shown in Figure 9 above, and the schematic diagram of the commutation loop of the midpoint clamped inverter can be as shown in the above Figure 10- Figure 11.
  • control module can adjust the first preset delay time, the second preset delay time, the third preset delay time and the fourth preset delay according to the device junction temperature T j and the load current i 0 of the switch j The size of the time, thus realizing the adaptive control of the inverter according to the working conditions, thereby reducing the loss of the inverter under all working conditions, improving the operating efficiency of the inverter, and having strong flexibility and adaptability.
  • the midpoint clamp inverter provided in this application can also be applied to a single-phase inverter circuit, a three-level circuit, a rectifier circuit, a three-phase circuit, or can also be applied to the midpoint circuit provided in this application.
  • the multi-level technology is used to increase the number of circuit levels or to realize the series-parallel circuit of the power device, which can be determined according to the actual application scenario, and is not limited here.
  • the mid-point clamped inverter provided by this application can flexibly select different switching units based on the control module to bear the switching loss or conduction loss under different working conditions (such as outputting active power or outputting reactive power), thereby It reduces the loss of the inverter under all working conditions, improves the operating efficiency of the inverter, and has stronger flexibility and adaptability.

Abstract

本申请提供一种中点箝位逆变器及光伏供电系统，该中点箝位逆变器可包括电源模块、开关模块以及控制模块。电源模块可包括电源、以及串联后并联于电源两端的第一电容和第二电容。开关模块可包括第一开关单元、第二开关单元以及第三开关单元。控制模块可分别连接第一开关单元、第二开关单元以及第三开关单元。控制模块可控制第一开关单元、第二开关单元以及第三开关单元中各开关单元的导通或者关断，以选择开关模块中的不同开关单元承担导通损耗或者开关损耗。基于本申请，可灵活选择不同开关单元承担导通损耗或者开关损耗，从而降低了中点箝位逆变器在所有工况下的损耗，效率高，适用性强。

Description

中点箝位逆变器及光伏供电系统
本申请要求于2020年11月25日提交中国专利局、申请号为202011341053.1、申请名称为“中点箝位逆变器及光伏供电系统”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
本申请涉及电子电路领域，尤其涉及一种中点箝位逆变器及光伏供电系统。
背景技术
目前，三电平中点箝位(neutral point clamped，NPC)逆变器被广泛应用于将直流电能转换为交流电能的供电系统中，典型的三电平NPC逆变器中可以包括外开关管和内开关管，通常会通过固定的内开关管承担三电平NPC逆变器运行在不同工况下的损耗(如开关损耗或者导通损耗)。一般来说，在三电平NPC逆变器运行在输出有功工况时，内开关管会产生导通损耗，适合选择低导通损耗的开关器件。然而，在三电平NPC逆变器运行在输出无功工况时，内开关管会产生开关损耗，适合选择低开关损耗的开关器件。由于低导通损耗的开关器件的开关损耗过大，因此无法同时满足内开关管的低开关损耗和低导通损耗，即不能保证三电平NPC逆变器在所有工况下的高效率运行，损耗过大且效率低。
发明内容
本申请提供一种中点箝位逆变器及光伏供电系统，可灵活选择不同开关单元承担导通损耗或者开关损耗，从而降低了中点箝位逆变器在所有工况下的损耗，效率高，适用性强。
第一方面，本申请提供了一种中点箝位逆变器，中点箝位逆变器可以包括电源模块、开关模块以及控制模块。其中，电源模块可以包括电源、以及串联后并联于电源两端的第一电容和第二电容。上述开关模块可以包括第一开关单元、第二开关单元以及第三开关单元。其中，第一开关单元的第一连接端连接电源的正极，第一开关单元的第二连接端连接第三开关单元的第一连接端，第一开关单元的第三连接端连接第二开关单元的第一连接端和负载，第二开关单元的第二连接端连接第三开关单元的第二连接端，第二开关单元的第三连接端连接电源的负极和负载，第三开关单元的第三连接端连接第一电容和第二电容。这里的开关模块中的任一开关单元可包括至少一个开关和/或二极管。上述控制模块可分别连接第一开关单元、第二开关单元以及第三开关单元。控制模块可以用于控制第一开关单元、第二开关单元以及第三开关单元中各开关单元的导通或者关断，以选择开关模块中的不同开关单元承担导通损耗或者开关损耗。在本申请提供的中点箝位逆变器中，可以通过控制模块控制不同开关单元的导通或关断，从而可以在不同工况下灵活选择不同的开关单元承担导通损耗或者开关损耗，进而降低了逆变器在所有工况下的损耗，提高了逆变器运行效率，灵活性强，适应性更强。
结合第一方面，在第一种可能的实施方式中，中点箝位逆变器还可以包括滤波模块。滤波模块可以包括电感和第三电容，电感的一端分别连接第一开关单元的第三连接端和第 二开关单元的第一连接端，电感的另一端分别连接第三电容的一端和负载，第三电容的另一端连接第二开关单元的第二连接端和负载。在本申请提供的中点箝位逆变器中，可以通过滤波模块滤去逆变器输出电压中的波纹，以得到性质更好的交流电信号，效率高，适用性更强。
结合第一方面或者第一方面第一种可能的实施方式，在第二种可能的实施方式中，第三开关单元可以包括第一开关、第一二极管和第二二极管。其中，第一二极管的阴极与第一开关的第一极连接作为第三开关单元的第一连接端，第二二极管的阳极与第一开关的第二极连接作为第三开关单元的第二连接端，第一二极管的阳极与第二二极管的阴极连接作为第三开关单元的第三连接端。在本申请提供的中点箝位逆变器中，可以选择第一开关承担中点箝位逆变器运行在不同工况(如输出有功功率或者输出无功功率)下的开关损耗或者导通损耗，从而降低了逆变器在所有工况下的损耗，提高了逆变器运行效率，适应性更强。
结合第一方面第二种可能的实施方式，在第三种可能的实施方式中，第一开关单元可以包括第二开关和第三开关，第二开关单元可以包括第四开关和第五开关。其中，第二开关的第一极作为第一开关单元的第一连接端，第二开关的第二极与第三开关的第一极连接作为第一开关单元的第二连接端，第三开关的第二极作为第一开关单元的第三连接端，第四开关的第一极作为第二开关单元的第一连接端，第四开关的第二极与第五开关的第一极连接作为第二开关单元的第二连接端，第五开关的第二极作为第二开关单元的第三连接端。上述控制模块分别连接第一开关、第二开关、第三开关、第四开关以及第五开关中各开关的第三极，以控制各开关的导通或者关断。可以理解，这里的第一极可以为不同类型开关的集电极或者漏极，第二极可以为不同类型开关的发射极或者源极，第三极可以为不同类型开关的基极或者栅极。在本申请提供的中点箝位逆变器中，可以灵活选择不同开关(如第一开关、第三开关或者第四开关)承担中点箝位逆变器运行在不同工况下的开关损耗或者导通损耗，从而降低了逆变器在所有工况下的损耗，提高了逆变器运行效率，灵活性更强，适应性更强。
结合第一方面第三种可能的实施方式，在第四种可能的实施方式中，控制模块用于控制第一开关、第二开关、第三开关、第四开关以及第五开关中各开关的导通或者关断，以在中点箝位逆变器向负载输出有功功率时选择第一开关、第三开关以及第四开关基于并联电流通路承担导通损耗；或者以在中点箝位逆变器向负载输出无功功率时选择第一开关承担开关损耗、第三开关或者第四开关承担导通损耗，或者选择第一开关承担导通损耗、第三开关或者第四开关承担开关损耗。在本申请提供的中点箝位逆变器中，可以选择第一开关、第三开关以及第四开关独立承担或者联合承担在不同的工况(如输出有功功率或者输出无功功率)下的开关损耗或者导通损耗，从而降低了逆变器在所有工况下的损耗，提高了逆变器运行效率，适应性更强。
结合第一方面第三种可能的实施方式或者第一方面第四种可能的实施方式，在第五种可能的实施方式中，第一开关、第二开关、第三开关、第四开关或者第五开关可以为绝缘栅双极性晶体管(insulated gate bipolar transistor，可以简称为IGBT)，或者金属氧化物半导体场效应晶体管(metal-oxide-semiconductor field-effect transistor，可以 简称为MOSFET)。这里的IGBT可以为低导通损耗的开关器件，MOSFET可以为低开关损耗的开关器件。在本申请中，可以将第一开关、第二开关、第三开关、第四开关或者第五开关分别设置为低导通损耗或者低开关损耗的开关器件(如IGBT或者MOSFET)，可以灵活选择不同类型的开关(如IGBT或者MOSFET)来承担中点箝位逆变器运行在不同工况下的导通损耗或者开关损耗，从而降低了逆变器在所有工况下的损耗，提高了逆变器运行效率，灵活性强，适用性更强。
结合第一方面第五种可能的实施方式，在第六种可能的实施方式中，第一开关、第二开关、第三开关、第四开关或者第五开关可以由硅半导体材料Si，或者第三代宽禁带半导体材料的碳化硅SiC，或者氮化镓GaN，或者金刚石，或者氧化锌ZnO，或者其它材料制成。
结合第一方面第三种可能的实施方式至第一方面第六种可能的实施方式中任一种，在第七种可能的实施方式中，第一开关可以为MOSFET，第二开关、第三开关、第四开关以及第五开关可以为IGBT。其中，第一开关的第一极、第二极以及第三极分别为第一开关的漏极、源极以及栅极，第二开关、第三开关、第四开关以及第五开关中各开关的第一极为各开关的集电极、各开关的第二极为各开关的发射极、各开关的第三极为各开关的基极。在本申请中，可以将MOSFET作为第一开关，并将IGBT作为第二开关、第三开关、第四开关以及第五开关，在中点箝位逆变器向负载输出无功功率时，可以选择低开关损耗的第一开关承担开关损耗，同时选择低导通损耗的第三开关或者第四开关承担导通损耗，从而降低了逆变器在所有工况下的损耗，提高了逆变器运行效率，适应性更强。
结合第一方面第三种可能的实施方式至第一方面第六种可能的实施方式中任一种，在第八种可能的实施方式中，第一开关、第二开关以及第五开关可以为IGBT，第三开关和第四开关可以为MOSFET。其中，第一开关、第二开关以及第五开关中各开关的第一极为各开关的集电极、各开关的第二极为各开关的发射极、各开关的第三极为各开关的基极，第三开关和第四开关的第一极为第三开关和第四开关的漏极、第三开关和第四开关的第二极为第三开关和第四开关的源极、第三开关和第四开关的第三极为第三开关和第四开关的栅极。在本申请中，可以将IGBT作为第一开关、第二开关以及第五开关，将MOSFET作为第三开关和第四开关，在中点箝位逆变器向负载输出有功功率时，可以选择第一开关、第三开关以及第四开关基于并联电流通路承担导通损耗，在中点箝位逆变器向负载输出无功功率时，可以选择低导通损耗的第一开关承担导通损耗，同时选择低开关损耗的第三开关或者第四开关承担开关损耗，从而降低了逆变器在所有工况下的损耗，提高了逆变器运行效率，适应性更强。
结合第一方面第三种可能的实施方式至第一方面第八种可能的实施方式中任一种，在第九种可能的实施方式中，控制模块可以用于生成用于控制第一开关、第二开关、第三开关、第四开关以及第五开关中各开关的控制信号。这里的控制信号用于控制各开关的导通或者关断，以实现各开关单元的导通或者关断。在本申请中，可通过控制模块生成的控制信号控制各开关的导通或者关断，从而可以灵活选择不同开关独立承担或者联合承担在不同的工况下的开关损耗或者导通损耗，从而降低了逆变器在所有工况下的损耗，提高了逆变器运行效率，灵活性更强，适应性更强。
结合第一方面第九种可能的实施方式，在第十种可能的实施方式中，控制模块可以用 于：控制第一开关导通，并在第一预设延迟时间之后控制第四开关导通，在控制第四开关关断之后的第二预设延迟时间后控制第一开关关断；控制第一开关导通，并在第三预设延迟时间之后控制第三开关导通，在控制第三开关关断之后的第四预设延迟时间后控制第一开关关断。在本申请中，可通过控制模块基于不同的预设延迟时间控制第一开关、第三开关以及第四开关之间的导通或者关断，从而可选择第一开关在中点箝位逆变器向负载输出无功功率的工况下承担开关损耗，且选择第三开关或者第四开关承担在不同工况下的导通损耗，由于这里的第一开关为低开关损耗的开关器件(如MOSFET)，且第三开关和第四开关为低导通损耗的开关器件(如IGBT)，因此降低了逆变器在所有工况下的损耗，提高了逆变器运行效率，适应性更强。
结合第一方面第九种可能的实施方式，在第十一种可能的实施方式中，控制模块可以用于：控制第四开关导通，并在第一预设延迟时间之后控制第一开关导通，在控制第一开关关断之后的第二预设延迟时间后控制第四开关关断；控制第三开关导通，并在第三预设延迟时间之后控制第一开关导通，在控制第一开关关断之后的第四预设延迟时间后控制第三开关关断。在本申请中，可通过控制模块基于不同的预设延迟时间控制第一开关、第三开关以及第四开关之间的导通或者关断，从而可选择第一开关、第三开关以及第四开关基于并联电流通路承担在输出有功功率时的导通损耗，同时选择第一开关承担在输出无功功率时的导通损耗，以及选择第三开关或者第四开关承担在输出无功功率时的开关损耗，由于这里的第一开关为低导通损耗的开关器件(如IGBT)，且第三开关和第四开关为低开关损耗的开关器件(如MOSFET)，因此降低了逆变器在所有工况下的损耗，提高了逆变器运行效率，适应性更强。
结合第一方面第十种可能的实施方式或者第一方面第十一种可能的实施方式，在第十二种可能的实施方式中，控制模块用于根据第一开关、第二开关、第三开关、第四开关以及第五开关中各开关对应的器件结温、和/或流经负载的负载电流，确定第一预设延迟时间、第二预设延迟时间、第三预设延迟时间以及第四预设延迟时间。在本申请中，可通过控制模块确定不同的预设延迟时间，并基于不同的预设延迟时间控制第一开关、第三开关以及第四开关之间的导通或者关断，从而可选择第一开关、第三开关以及第四开关独立承担或者联合承担在不同的工况下的开关损耗或者导通损耗，从而降低了逆变器在所有工况下的损耗，提高了逆变器运行效率，适应性更强。
第二方面，本申请提供了一种光伏供电系统，该光伏供电系统可以包括光伏阵列以及与该光伏阵列连接的如上述第一方面至第一方面第十二种可能的实施方式中任一种提供的中点箝位逆变器。可以理解，这里的光伏阵列可以连接该中点箝位逆变器的直流侧，为中点箝位逆变器提供直流输入电压，该中点箝位逆变器的交流侧可以连接负载，以对负载提供交流电能。其中，光伏阵列中可以包括多个光伏组件(也可以称为太阳能电池板或者光伏板)和/或其它光伏供电器件。
在本申请中，中点箝位逆变器可基于控制模块以灵活选择不同开关单元承担在不同的工况(如输出有功功率或者输出无功功率)下的开关损耗或者导通损耗，从而降低了逆变器在所有工况下的损耗，提高了逆变器运行效率，灵活性更强，适应性更强。
附图说明
图1是本申请提供的中点箝位逆变器的应用场景示意图；
图2是本申请提供的中点箝位逆变器的一电路示意图；
图3是本申请提供的中点箝位逆变器的另一电路示意图；
图4是本申请提供的中点箝位逆变器的另一电路示意图；
图5是本申请提供的中点箝位逆变器的一开关时序示意图；
图6是本申请提供的中点箝位逆变器输出有功功率时的一换流回路示意图；
图7是本申请提供的中点箝位逆变器输出无功功率时的一换流回路示意图；
图8是本申请提供的中点箝位逆变器的另一电路示意图；
图9是本申请提供的中点箝位逆变器的另一开关时序示意图；
图10是本申请提供的中点箝位逆变器输出有功功率时的另一换流回路示意图；
图11是本申请提供的中点箝位逆变器输出无功功率时的另一换流回路示意图；
图12是本申请提供的中点箝位逆变器的又一电路示意图。
具体实施方式
逆变器是一种可以把直流电(如电池、蓄电瓶)转变成定频定压或调频调压交流电的转换器。逆变器(如中点箝位逆变器)一般可以由逆变桥电路、控制逻辑电路以及滤波电路构成，广泛应用于电器设备(如家用设备)以及电网，如可以通过逆变器连接蓄电池带动电器设备工作，或者也可以通过逆变器将大功率的高压交流电传输到电网。本申请提供的中点箝位逆变器也可以称为NPC逆变器、三电平中点箝位逆变器或者三电平NPC逆变器，该中点箝位逆变器适用于光伏发电领域(如对家用设备(如冰箱、空调)或者电网供电)，或者风力发电领域，或者大功率变换器领域(如将直流电转换为大功率的高压交流电)等多种应用领域，具体可根据实际应用场景确定，在此不做限制。
本申请提供的中点箝位逆变器可以包括电源模块、开关模块以及控制模块。电源模块可以包括电源、以及串联后并联于电源两端的第一电容和第二电容。上述开关模块可以包括第一开关单元、第二开关单元以及第三开关单元。上述控制模块可分别连接第一开关单元、第二开关单元以及第三开关单元。控制模块可以用于控制第一开关单元、第二开关单元以及第三开关单元中各开关单元的导通或者关断，以选择开关模块中的不同开关单元承担导通损耗或者开关损耗。本申请提供的中点箝位逆变器，可基于控制模块以灵活选择不同开关单元承担在不同的工况(如输出有功功率或者输出无功功率)下的开关损耗或者导通损耗，从而降低了逆变器在所有工况下的损耗，提高了逆变器运行效率，灵活性更强，适应性更强。本申请提供的中点箝位逆变器可适配不同的应用场景，比如，需要将直流电转化为交流电的任意一种应用场景，比如，太阳能供电场景和风力供电场景等，本申请以太阳能供电场景为例进行说明。
参见图1，图1是本申请提供的中点箝位逆变器的应用场景示意图。如图1所示，光伏供电系统(如光伏供电系统10)中可以包括光伏阵列(如光伏阵列1)以及与该光伏阵列连接的中点箝位逆变器(如中点箝位逆变器2)。其中，光伏阵列1中可以包括多个光伏组件(也可以称为太阳能电池板或者光伏板)和/或者其它光伏供电器件(如光伏汇流盒)。 这里的光伏阵列1可以连接该中点箝位逆变器2的直流侧，为中点箝位逆变器2提供直流输入电压。换言之，光伏阵列1为中点箝位逆变器2提供直流电。其中，直流输入电压的电压值可以为12V、24V、36V、48V的直流电或者其它电压数值。该中点箝位逆变器2的交流侧可以直接连接或者间接连接负载(如家用设备3或者电网5)，中点箝位逆变器2可以将光伏阵列1提供的直流电转化为交流电(如220V，50Hz正弦波的交流电或者其它电压数值的交流电)，并对家用设备3(如冰箱、空调等)进行供电。可选的，中点箝位逆变器2也可以向升压器4输入交流电，升压器4可以将中点箝位逆变器2输入的交流电升压为高压电(如32KV、110KV、220KV或者其它电压数值的高压电)，并将升压后的高压电输入至高压电网(如电网5)，具体可根据实际应用场景确定，在此不作限制。本申请中的中点箝位逆变器(如上述中点箝位逆变器2)可以降低在所有工况下的损耗，提高了逆变器运行效率，进一步提高了供电效率，适用性更强。
下面将结合图2至图12对本申请提供的中点箝位逆变器及其工作原理进行示例说明。
参见图2，图2是本申请提供的中点箝位逆变器的一电路示意图。如图2所示，中点箝位逆变器可以包括电源模块10、开关模块20以及控制模块30。电源模块10中可以包括电源、以及串联后并联于电源两端的第一电容C1和第二电容C2。这里的电源为直流输入电源，电源电压可以为V dc，第一电容C1和第二电容C2可以为直流母线电容，第一电容C1两端的电压分别为正端电压BUS +(BUS +＝V dc/2)和零点电压BUSN，第二电容C2两端的电压分别为零点电压BUSN和负端电压BUS -(BUS -＝-V dc/2)。开关模块20中可包括至少一个开关单元，例如，具体可以包含第一开关单元201、第二开关单元202以及第三开关单元203。其中，第一开关单元201的第一连接端可以连接电源的正极，第一开关单元201的第二连接端可以连接第三开关单元203的第一连接端，第一开关单元201的第三连接端可以连接第二开关单元202的第一连接端和负载，第二开关单元202的第二连接端可以连接第三开关单元203的第二连接端，第二开关单元202的第三连接端可以连接电源的负极和负载，第三开关单元203的第三连接端可以连接第一电容C1和第二电容C2。其中，流经负载的电流可以表示为i 0，中点箝位逆变器的输出电压可以表示为V out。应当理解，开关模块20中的任一开关单元可以包括至少一个开关和/或二极管，或者任一开关单元中可以包括至少一个开关和/或二极管和/或电容和/或电感和/或其它器件，具体可根据实际应用场景确定，在此不作限制。上述控制模块30可分别连接第一开关单元201、第二开关单元202以及第三开关单元203，该控制模块30可以控制第一开关单元201、第二开关单元202以及第三开关单元203中各开关单元的导通或者关断，以选择第一开关单元201、第二开关单元202以及第三开关单元203中的任一开关单元独立承担导通损耗或者开关损耗，或者以选择第一开关单元201、第二开关单元202以及第三开关单元203中的任意两个开关单元或者三个开关单元联合承担导通损耗或者开关损耗，从而可灵活选择开关模块20中的不同开关单元直接承担或者联合承担中点箝位逆变器在不同工况下的导通损耗或者开关损耗，灵活性更强，适应性更强。
参见图3，图3是本申请提供的中点箝位逆变器的另一电路示意图。如图3所示，如上述图2所示的中点箝位逆变器中还可以包括滤波模块40，滤波模块40中可以包括电感L和第三电容C3，电感L的一端分别连接第一开关单元201的第三连接端和第二开关单元202 的第一连接端，电感L的另一端分别连接第三电容C3的一端和负载，第三电容C3的另一端连接第二开关单元202的第二连接端和负载。请一并参见图4，图4是本申请提供的中点箝位逆变器的另一电路示意图。如图4所示，如上述图3所示的第一开关单元201可以包括第二开关S1和第三开关S2，如上述图3所示的第二开关单元202可以包括第四开关S3和第五开关S4，如上述图3所示的第三开关单元203可以包括第一开关Q5、第一二极管D5以及第二二极管D6。其中，第二开关S1中可以包括开关器件Q1以及并联于开关器件Q1两端的续流二极管D1,第三开关S2中可以包括开关器件Q2以及并联于开关器件Q2两端的续流二极管D2,第四开关S3中可以包括开关器件Q3以及并联于开关器件Q3两端的续流二极管D3，第五开关S4中可以包括开关器件Q4以及并联于开关器件Q4两端的续流二极管D4。对于第一开关单元201而言，第二开关S1的第一极作为第一开关单元201的第一连接端，第二开关S1的第二极与第三开关S2的第一极连接作为第一开关单元201的第二连接端，第三开关S2的第二极作为第一开关单元201的第三连接端。对于第二开关单元202而言，第四开关S3的第一极作为第二开关单元202的第一连接端，第四开关S3的第二极与第五开关S4的第一极连接作为第二开关单元202的第二连接端，第五开关S4的第二极作为第二开关单元202的第三连接端。对于第三开关单元203而言，第一二极管D5的阴极与第一开关Q5的第一极连接作为第三开关单元203的第一连接端，第二二极管D6的阳极与第一开关Q5的第二极连接作为第三开关单元203的第二连接端，第一二极管D5的阳极与第二二极管D6的阴极连接作为第三开关单元203的第三连接端。如图4所示，上述控制模块30可分别连接第一开关Q5、第二开关S1、第三开关S2、第四开关S3以及第五开关S4中各开关的第三极，从而控制各开关的导通或者关断。可以理解，第一极可以为不同类型开关的集电极或者漏极，第二极可以为不同类型开关的发射极或者源极，第三极可以为不同类型开关的基极或者栅极。
在一些可行的实施方式中，第一开关Q5、第二开关S1、第三开关S2、第四开关S3或者第五开关S4可以是采用硅半导体材料(silicon，Si)，或者第三代宽禁带半导体材料的碳化硅(silicon carbide，SiC)，或者氮化镓(gallium nitride，GaN)，或者金刚石(diamond)，或者氧化锌(zinc oxide，ZnO)，或者其它材料制成的MOSFET、IGBT或者二极管，具体可根据实际应用场景确定，在此不做限制。例如，如图4所示，第一开关Q5可以为MOSFET，第二开关S1、第三开关S2、第四开关S3、第五开关S4可以为IGBT。可以理解，第一开关Q5的第一极、第二极以及第三极分别为第一开关Q5的漏极、源极以及栅极。第二开关S1、第三开关S2、第四开关S3、第五开关S4中各开关的第一极可以为第二开关S1、第三开关S2、第四开关S3、第五开关S4中各开关的集电极，第二开关S1、第三开关S2、第四开关S3、第五开关S4中各开关的第二极可以为第二开关S1、第三开关S2、第四开关S3、第五开关S4中各开关的发射极，第二开关S1、第三开关S2、第四开关S3、第五开关S4中各开关的第三极可以为第二开关S1、第三开关S2、第四开关S3、第五开关S4中各开关的基极。
在一些可行的实施方式中，控制模块30可以生成用于控制第一开关Q5、第二开关S1、第三开关S2、第四开关S3以及第五开关S4的控制信号，如控制信号可以为第一开关Q5、第二开关S1、第三开关S2、第四开关S3以及第五开关S4的脉冲宽度调制(pulse width  modulation，PWM)信号，可以简称为PWM信号。其中，控制信号也可以理解为用于控制开关器件Q1、开关器件Q2、开关器件Q3、开关器件Q4以及第一开关Q5的PWM信号。这里的控制信号可以用于控制第一开关Q5、第二开关S1、第三开关S2、第四开关S3以及第五开关S4中各开关的导通或者关断。例如，控制信号可以为(0 1 1 0 1)，可以控制第二开关S1关断、第三开关S2导通、第四开关S3导通、第五开关S4关断以及第一开关Q5导通。请一并参见图5，图5是本申请提供的中点箝位逆变器的一开关时序示意图。如图5所示，在中点箝位逆变器的输出电压V out处于正半周(即正半周期)时，第三开关S2保持导通状态，第五开关S4保持关断状态(即截止状态)。第二开关S1、第四开关S3以及第一开关Q5可以工作在PWM模式，第二开关S1和第一开关Q5可以为互补开关。可以理解，PWM模式是一种利用微处理器(如控制模块30)的数字输出信号对模拟电路进行控制的一种有效模式，互补开关为一对推拉式开关，当其中一个开关闭合时另外一个开关断开，如第二开关S1导通且第一开关Q5关断，或者第二开关S1关断且第一开关Q5导通。对于作为互补开关的第二开关S1和第一开关Q5而言，为了防止第二开关S1和第一开关Q5同时导通，需要在第二开关S1和第一开关Q5之间加入死区时间，如t d1或者t d2，其中，t d1可以为从第二开关S1关断时刻到第一开关Q5导通时刻之间的死区时间，t d2可以为从第一开关Q5关断时刻到第二开关S1导通时刻之间的死区时间。在中点箝位逆变器的输出电压V out处于负半周(即负半周期)时，第四开关S3保持导通状态，第二开关S1保持关断状态(即截止状态)。第三开关S2、第五开关S4以及第一开关Q5工作在PWM模式，第五开关S4和第一开关Q5为互补开关。对于作为互补开关的第五开关S4和第一开关Q5而言，为了防止第五开关S4和第一开关Q5同时导通，需要在第五开关S4和第一开关Q5之间加入死区时间，如t d3或者t d4，其中，t d3可以为从第五开关S4关断时刻到第一开关Q5导通时刻之间的死区时间，t d4可以为从第一开关Q5关断时刻到第五开关S4导通时刻之间的死区时间。
在一些可行的实施方式中，控制模块30在第一开关Q5、第二开关S1、第三开关S2、第四开关S3以及第五开关S4中各开关为不同类型的开关(如IGBT或者MOSFET)时，可以设置不同的第一预设时间、第二预设时间、第三预设时间以及第四预设时间来控制第一开关Q5、第三开关S2以及第四开关S3之间的导通或者关断。若第一开关Q5为MOSFET，第二开关S1、第三开关S2、第四开关S3、第五开关S4为IGBT，在中点箝位逆变器的输出电压V out处于正半周时，控制模块30可以控制第一开关Q5导通，并在第一预设延迟时间(如预设延迟时间t delay1)之后控制第四开关S3导通，在控制第四开关S3关断之后的第二预设延迟时间(如预设延迟时间t delay2)后控制第一开关Q5关断；或者在中点箝位逆变器的输出电压V out处于负半周时，控制模块30还可以控制第一开关Q5导通，并在第三预设延迟时间(如预设延迟时间t delay3)之后控制第三开关S2导通，在控制第三开关S2关断之后的第四预设延迟时间(如预设延迟时间t delay4)后控制第一开关Q5关断。
为方便描述，下面将结合图6至图7对本申请提供的中点箝位逆变器中的开关模块的 工作原理进行示例说明。请一并参见图6，图6是本申请提供的中点箝位逆变器输出有功功率时的一换流回路示意图。如图6所示，在中点箝位逆变器的输出电压V out处于正半周，且负载电流i 0大于0时，中点箝位逆变器向负载输出有功功率，换言之，中点箝位逆变器运行在输出有功工况下。在这种工况下，第二开关S1、第四开关S3以及第一开关Q5工作在PWM模式，此时各开关处于不同开关状态下的换流回路可以如图6中的6a所示，这里的开关状态可以指导通状态或者关断状态(也可以称为截止状态)。如图6中的6a所示，在开关器件Q1导通时，电流流经开关器件Q1和开关器件Q2；在开关器件Q1截止，且第一开关Q5导通时，此时同时存在两条电流通路，分别是流经第一二极管D5、第一开关Q5和续流二极管D3的电流通路，以及流经第一二极管D5和开关器件Q2的电流通路，由于开关器件Q2的导通压降更低，所以电流会流经第一二极管D5和开关器件Q2；在经过预设延迟时间t delay1后，开关器件Q3导通，电流仍然流经第一二极管D5和开关器件Q2。可以得到，开关器件Q1和第一二极管D5参与换流，会产生开关损耗；开关器件Q2始终导通，会产生导通损耗，进而可以得到第三开关S2会产生导通损耗；开关器件Q3和第一开关Q5上无电流流过，不产生损耗。
在中点箝位逆变器的输出电压V out处于负半周，且负载电流i 0小于0时，中点箝位逆变器向负载输出有功功率，换言之，中点箝位逆变器运行在输出有功工况下。在这种工况下，第三开关S2、第五开关S4以及第一开关Q5工作在PWM模式，此时各开关处于不同开关状态下的换流回路可以如图6中的6b所示，在开关器件Q4导通时，电流会流经开关器件Q3和开关器件Q4；在开关器件Q4截止，且第一开关Q5导通时，此时同时存在两条电流通路，即流经续流二极管D2、第一开关Q5和第二二极管D6的电流通路，以及流经开关器件Q3和第二二极管D6的电流通路，由于开关器件Q3的导通压降更低，所以电流会流经开关器件Q3和第二二极管D6；在经过预设延迟时间t delay3后，开关器件Q2导通，电流仍然流经开关器件Q3和第二二极管D6。可以得到，开关器件Q4和第二二极管D6参与换流，会产生开关损耗；开关器件Q3始终导通，会产生导通损耗，进而可以得到第四开关S3会产生导通损耗；开关器件Q2和第一开关Q5无电流流过，不产生损耗。
请一并参见图7，图7是本申请提供的中点箝位逆变器输出无功功率时的一换流回路示意图。如图7所示，在中点箝位逆变器的输出电压V out处于正半周，且负载电流i 0小于0时，中点箝位逆变器向负载输出无功功率，换言之，中点箝位逆变器运行在输出无功工况下。在这种工况下，第二开关S1、第四开关S3以及第一开关Q5工作在PWM模式，此时各开关处于不同开关状态下的换流回路可以如图7中的7a所示，在开关器件Q1导通时，电流会流经续流二极管D2和续流二极管D1；在开关器件Q1截止，且第一开关Q5导通时，电流会流经续流二极管D2、第一开关Q5以及第二二极管D6；在经过预设延迟时间t delay1后，开关器件Q3导通，此时同时存在两条电流通路，即流经续流二极管D2、第一开关Q5和第二二极管D6的电流通路，以及流经开关器件Q3和第二二极管D6的电流通路，由于流经开 关器件Q3和第二二极管D6的电流通路的导通压降更低，所以电流会流经开关器件Q3和第二二极管D6。可以得到，第一开关Q5和续流二极管D1参与换流，会产生开关损耗；续流二极管D2会产生导通损耗；开关器件Q3处于零电压开关状态，无开关损耗，会产生导通损耗，进而可以得到第四开关S3会产生导通损耗，这里的零电压开关状态可以理解为开关(如开关器件Q3)导通或者关断时其两端的电压为0时所处的状态。
在中点箝位逆变器的输出电压V out处于负半周，且负载电流i 0大于0时，中点箝位逆变器向负载输出无功功率，换言之，中点箝位逆变器运行在输出无功工况下。在这种工况下，第三开关S2、第五开关S4以及第一开关Q5工作在PWM模式，此时各开关处于不同开关状态下的换流回路可以如图7中的7b所示，在开关器件Q4导通时，电流会流经续流二极管D4和续流二极管D3；在开关器件Q4截止，且第一开关Q5导通时，电流会流经第一二极管D5、第一开关Q5以及续流二极管D3；在经过预设延迟时间t delay3后，开关器件Q2导通，此时同时存在两条电流通路，即流经第一二极管D5、第一开关Q5和续流二极管D3的电流通路，以及流经第一二极管D5和开关器件Q2的电流通路，由于流经第一二极管D5和开关器件Q2的电流通路的导通压降更低，所以电流会流经第一二极管D5和开关器件Q2。可以得到，第一开关Q5和续流二极管D4参与换流，会产生开关损耗；续流二极管D3会产生导通损耗；开关器件Q2处于零电压开关状态，无开关损耗，会产生导通损耗，进而可以得到第三开关S2会产生导通损耗。
结合上述图6至图7对实施例的描述可以得到，在中点箝位逆变器向负载输出有功功率或者输出无功功率时，控制模块30可控制各开关的导通或者关断以选择第三开关S2或者第四开关S3承担导通损耗，同时选择第一开关Q5承担在中点箝位逆变器向负载输出无功功率时的开关损耗。由于第三开关S2和第四开关S3均为低导通损耗的开关器件，且第一开关Q5为低开关损耗的开关器件，可通过低导通损耗的第三开关S2或者第四开关S3承担导通损耗，通过低开关损耗的第一开关Q5承担开关损耗，从而降低了中点箝位逆变器在所有工况下的运行损耗，提高了逆变器运行效率，适应性更强。
请参见图8，图8是本申请提供的中点箝位逆变器的另一电路示意图。如图8所示，在一些可行的实施方式中，第二开关S1、第四开关S3以及第一开关Q5可以为IGBT，第三开关S2和第四开关S3可以为MOSFET。可以理解，第二开关S1、第四开关S3以及第一开关Q5中各开关的第一极为第二开关S1、第四开关S3以及第一开关Q5中各开关的集电极，第二开关S1、第四开关S3以及第一开关Q5中各开关的第二极为第二开关S1、第四开关S3以及第一开关Q5中各开关的发射极，第二开关S1、第四开关S3以及第一开关Q5中各开关的第三极为第二开关S1、第四开关S3以及第一开关Q5中各开关的基极。第三开关S2和第四开关S3的第一极为第三开关S2和第四开关S3的漏极、第三开关S2和第四开关S3的第二极为第三开关S2和第四开关S3的源极、第三开关S2和第四开关S3的第三极为第三开关S2和第四开关S3的栅极。
如图8所示，控制模块30可以生成用于控制第一开关Q5、第二开关S1、第三开关S2、第四开关S3以及第五开关S4的控制信号。这里的控制信号可以用于控制第二开关S1、第 三开关S2、第四开关S3、第五开关S4以及第一开关Q5的导通或者关断。请一并参见图9，图9是本申请提供的中点箝位逆变器的另一开关时序示意图。如图9所示，在中点箝位逆变器的输出电压V out处于正半周时，第三开关S2保持导通状态，第五开关S4保持关断状态。第二开关S1、第四开关S3以及第一开关Q5可以工作在PWM模式，第二开关S1和第四开关S3可以为互补开关。对于作为互补开关的第二开关S1和第四开关S3而言，为了防止第二开关S1和第四开关S3同时导通，需要在第二开关S1和第四开关S3之间加入死区时间，如t d5或者t d6，其中，t d5可以为从第二开关S1关断时刻到第四开关S3导通时刻之间的死区时间，t d6可以为从第四开关S3关断时刻到第二开关S1导通时刻之间的死区时间。在中点箝位逆变器的输出电压V out处于负半周时，第四开关S3保持导通状态，第二开关S1保持关断状态。第三开关S2、第五开关S4以及第一开关Q5工作在PWM模式，第三开关S2和第五开关S4为互补开关。对于作为互补开关的第三开关S2和第五开关S4而言，为了防止第三开关S2和第五开关S4同时导通，需要在第三开关S2和第五开关S4之间加入死区时间，如t d7或者t d8，其中，t d7可以为从第五开关S4关断时刻到第三开关S2导通时刻之间的死区时间，t d8可以为从第三开关S2关断时刻到第五开关S4导通时刻之间的死区时间。
在一些可行的实施方式中，若第二开关S1、第四开关S3以及第一开关Q5为IGBT，且第三开关S2和第四开关S3为MOSFET，在中点箝位逆变器的输出电压V out处于正半周时，控制模块30可以控制第四开关S3导通，并在第一预设延迟时间(如预设延迟时间t delay5)之后控制第一开关Q5导通，在控制第一开关Q5关断之后的第二预设延迟时间(如预设延迟时间t delay6)后控制第四开关S3关断；或者在中点箝位逆变器的输出电压V out处于负半周时，控制模块30还可以控制第三开关S2导通，并在第三预设延迟时间(如预设延迟时间t delay7)之后控制第一开关Q5导通，在控制第一开关Q5关断之后的第四预设延迟时间(如预设延迟时间t delay8)后控制第三开关S2关断。
为方便描述，下面将结合图10至图11对本申请提供的中点箝位逆变器中的开关模块的工作原理进行示例说明。请一并参见图10，图10是本申请提供的中点箝位逆变器输出有功功率时的另一换流回路示意图。如图10所示，在中点箝位逆变器的输出电压V out处于正半周，且负载电流i 0大于0时，中点箝位逆变器向负载输出有功功率，换言之，中点箝位逆变器运行在输出有功工况下。在这种工况下，第二开关S1、第四开关S3以及第一开关Q5工作在PWM模式，此时各开关处于不同开关状态下的换流回路可以如图10中的10a所示，在开关器件Q1导通时，电流会流经开关器件Q1和开关器件Q2；在开关器件Q1截止，且开关器件Q3导通时，电流会流经第一二极管D5和开关器件Q2；在经过预设延迟时间t delay5后，第一开关Q5导通，此时同时存在两条电流通路，即流经第一二极管D5、开关器件Q2和第一二极管D5的电流通路,以及流经第一开关Q5和续流二极管D3的电流通路, 从而可以通过并联导通的两条电流通路降低导通损耗。可以得到，开关器件Q1和第一二极管D5参与换流，会产生开关损耗；开关器件Q2始终导通，会产生导通损耗，进而可以得到第三开关S2会产生导通损耗；第一开关Q5仅产生导通损耗，续流二极管D3会产生导通损耗和反向恢复损耗。
在中点箝位逆变器的输出电压V out处于负半周，且负载电流i 0小于0时，中点箝位逆变器向负载输出有功功率，换言之，中点箝位逆变器运行在输出有功工况下。在这种工况下，第三开关S2、第五开关S4以及第一开关Q5工作在PWM模式，此时各开关处于不同开关状态下的换流回路可以如图10中的10b所示，在开关器件Q4导通时，电流会流经开关器件Q3和开关器件Q4；在开关器件Q4截止，且开关器件Q2导通时，电流会流经开关器件Q3和第二二极管D6；在经过预设延迟时间t delay7后，第一开关Q5导通，此时同时存在两条电流通路，即流经开关器件Q3、第二二极管D6和续流二极管D2的电流通路,以及流经第一开关Q5和第二二极管D6的电流通路,从而可以通过并联导通的两条电流通路降低导通损耗。可以得到，开关器件Q4和第二二极管D6参与换流，会产生开关损耗；开关器件Q3始终导通，会产生导通损耗，进而可以得到第四开关S3会产生导通损耗；第一开关Q5会产生导通损耗，续流二极管D2会产生导通损耗和反向恢复损耗。
请一并参见图11，图11是本申请提供的中点箝位逆变器输出无功功率时的另一换流回路示意图。如图11所示，在中点箝位逆变器的输出电压V out处于正半周，且负载电流i 0小于0时，中点箝位逆变器向负载输出无功功率，换言之，中点箝位逆变器运行在输出无功工况下。在这种工况下，第二开关S1、第四开关S3以及第一开关Q5工作在PWM模式，此时各开关处于不同开关状态下的换流回路可以如图11中的11a所示，在开关器件Q1导通时，电流会流经续流二极管D2和续流二极管D1；在开关器件Q1截止，且开关器件Q3导通时，电流会流经开关器件Q3和第二二极管D6；在经过预设延迟时间t delay5，第一开关Q5导通，此时同时存在两条电流通路，即流经续流二极管D2、第一开关Q5和第二二极管D6的电流通路，以及流经开关器件Q3和第二二极管D6的电流通路，从而可以通过并联导通的两条电流通路降低导通损耗。可以得到，开关器件Q3和续流二极管D1参与换流，会产生开关损耗，进而可以得到第四开关S3会产生开关损耗；续流二极管D2和第二二极管D6会产生导通损耗；第一开关Q5处于零电压开关状态，无开关损耗，会产生导通损耗。
在中点箝位逆变器的输出电压V out处于负半周，且负载电流i 0大于0时，中点箝位逆变器向负载输出无功功率，换言之，中点箝位逆变器运行在输出无功工况下。在这种工况下，第三开关S2、第五开关S4以及第一开关Q5工作在PWM模式，此时各开关处于不同开关状态下的换流回路可以如图11中的11b所示，在开关器件Q4导通时，电流会流经续流二极管D4和续流二极管D3；在开关器件Q4截止，且开关器件Q2导通时，电流会流经第一二极管D5和开关器件Q2；在经过预设延迟时间t delay7后，第一开关Q5导通，此时同时存在两 条电流通路，即流经第一二极管D5、第一开关Q5和续流二极管D3的电流通路，以及流经第一二极管D5和开关器件Q2的电流通路，从而可以通过并联导通的两条电流通路降低导通损耗。可以得到，开关器件Q2和续流二极管D4参与换流，会产生开关损耗，进而可以得到第三开关S2会产生开关损耗；续流二极管D3和第一二极管D5会产生导通损耗；第一开关Q5处于零电压开关状态，无开关损耗，会产生导通损耗。
结合上述图10至图11对实施例的描述可以得到，在中点箝位逆变器向负载输出有功功率时，控制模块30可控制各开关的导通或者关断以选择第三开关S2、第四开关S3以及第一开关Q5基于并联导通电流通路来降低导通损耗，在中点箝位逆变器向负载输出无功功率时，控制模块30可控制各开关的导通或者关断以选择第一开关Q5承担导通损耗，同时选择第三开关S2或者第四开关S3主要承担在输出无功情况下的开关损耗。由于第三开关S2和第四开关S3为低开关损耗的开关器件，且第一开关Q5为低导通损耗的开关器件，主要通过低开关损耗的第三开关S2和第四开关S3承担开关损耗，并通过低导通损耗的第一开关Q5承担导通损耗，从而降低了逆变器在所有工况下的运行损耗，提高了逆变器运行效率，适应性更强。
请参见图12，图12是本申请提供的中点箝位逆变器的又一电路示意图。如图12所示，在一些可行的实施方式中，第二开关S1、第三开关S2、第四开关S3、第五开关S4以及第一开关Q5可以为可控功率开关器件，如IGBT或者MOSFET。在中点箝位逆变器的输出电压V out处于正半周时，第三开关S2保持导通状态，第五开关S4保持关断状态。第二开关S1、第四开关S3以及第一开关Q5可以工作在PWM模式，第二开关S1和第四开关S3可以为互补开关。在中点箝位逆变器的输出电压V out处于正半周时，第四开关S3保持导通状态，第二开关S1保持关断状态。第三开关S2、第五开关S4以及第一开关Q5工作在PWM模式，第三开关S2和第五开关S4为互补开关。
在一些可行的实施方式中，控制模块30还可以根据第一开关Q5、第二开关S1、第三开关S2、第四开关S3以及第五开关S4中各开关对应的器件结温、和/或流经负载的负载电流i 0，确定第一预设延迟时间、第二预设延迟时间、第三预设延迟时间以及第四预设延迟时间。其中，第二开关S1、第三开关S2、第四开关S3、第五开关S4以及第一开关Q5中开关j的器件结温可以表示为T j，j为大于0，且小于或者等于开关模块20中的开关数(如5)的正整数。假设第一预设延迟时间为上述预设延迟时间t delay1、第二预设延迟时间为上述预设延迟时间t delay2、第三预设延迟时间为上述预设延迟时间t delay3、以及第四预设延迟时间为上述预设延迟时间t delay4，则中点箝位逆变器的开关时序示意图可以如上述图5所示，中点箝位逆变器的换流回路示意图可以如上述图6-图7所示。假设第一预设延迟时间为上述预设延迟时间t delay5、第二预设延迟时间为上述预设延迟时间t delay6、第三预设延迟时 间为上述预设延迟时间t delay7、以及第四预设延迟时间为上述预设延迟时间t delay8，则中点箝位逆变器的开关时序示意图可以如上述图9所示，中点箝位逆变器的换流回路示意图可以如上述图10-图11所示。具体实现中，本申请提供的中点箝位逆变器所执行的更多操作可参见图2至图11所示的中点箝位逆变器及其工作原理中的中点箝位逆变器所执行的实现方式，在此不再赘述。由此可见，控制模块可以根据开关j的器件结温T j以及负载电流i 0，来调节第一预设延迟时间、第二预设延迟时间、第三预设延迟时间以及第四预设延迟时间的大小，从而实现了逆变器随工况的自适应控制，进而降低了逆变器在所有工况下的损耗，提高了逆变器运行效率，灵活性强，适应性更强。
需要说明的是，本申请提供的中点箝位逆变器还可以应用于单相逆变电路，三电平电路，整流电路，三相电路，或者还可以应用于在本申请提供的中点箝位逆变器的电路基础上，通过多电平技术提高电路电平数或者实现功率器件的串并联的电路，具体可根据实际应用场景确定，在此不作限制。
本申请所提供的中点箝位逆变器，可基于控制模块以灵活选择不同开关单元承担在不同的工况(如输出有功功率或者输出无功功率)下的开关损耗或者导通损耗，从而降低了逆变器在所有工况下的损耗，提高了逆变器运行效率，灵活性更强，适应性更强。
以上，仅为本发明的具体实施方式，但本发明的保护范围并不局限于此，任何熟悉本技术领域的技术人员在本发明揭露的技术范围内，可轻易想到变化或替换，都应涵盖在本发明的保护范围之内。因此，本发明的保护范围应以权利要求的保护范围为准。

Claims (14)

  1. 一种中点箝位逆变器，其特征在于，所述中点箝位逆变器包括电源模块、开关模块以及控制模块；
    所述电源模块包括电源、以及串联后并联于所述电源两端的第一电容和第二电容；
    所述开关模块包括第一开关单元、第二开关单元以及第三开关单元，所述第一开关单元的第一连接端连接所述电源的正极，所述第一开关单元的第二连接端连接所述第三开关单元的第一连接端，所述第一开关单元的第三连接端连接所述第二开关单元的第一连接端和负载，所述第二开关单元的第二连接端连接所述第三开关单元的第二连接端，所述第二开关单元的第三连接端连接所述电源的负极和负载，所述第三开关单元的第三连接端连接所述第一电容和所述第二电容；
    所述控制模块分别连接所述第一开关单元、所述第二开关单元以及所述第三开关单元，所述控制模块用于控制所述第一开关单元、所述第二开关单元以及所述第三开关单元中各开关单元的导通或者关断，以选择所述开关模块中的不同开关单元承担导通损耗或者开关损耗。
  2. 根据权利要求1所述的中点箝位逆变器，其特征在于，所述中点箝位逆变器还包括滤波模块；
    所述滤波模块包括电感和第三电容，所述电感的一端分别连接所述第一开关单元的第三连接端和所述第二开关单元的第一连接端，所述电感的另一端分别连接所述第三电容的一端和所述负载，所述第三电容的另一端连接所述第二开关单元的第二连接端和所述负载。
  3. 根据权利要求1或2所述的中点箝位逆变器，其特征在于，所述第三开关单元包括第一开关、第一二极管和第二二极管；
    其中，所述第一二极管的阴极与所述第一开关的第一极连接作为所述第三开关单元的第一连接端，所述第二二极管的阳极与所述第一开关的第二极连接作为所述第三开关单元的第二连接端，所述第一二极管的阳极与所述第二二极管的阴极连接作为所述第三开关单元的第三连接端。
  4. 根据权利要求3所述的中点箝位逆变器，其特征在于，所述第一开关单元包括第二开关和第三开关，所述第二开关单元包括第四开关和第五开关，其中，所述第二开关的第一极作为所述第一开关单元的第一连接端，所述第二开关的第二极与所述第三开关的第一极连接作为所述第一开关单元的第二连接端，所述第三开关的第二极作为所述第一开关单元的第三连接端，所述第四开关的第一极作为所述第二开关单元的第一连接端，所述第四开关的第二极与所述第五开关的第一极连接作为所述第二开关单元的第二连接端，所述第五开关的第二极作为所述第二开关单元的第三连接端；
    所述控制模块分别连接所述第一开关、所述第二开关、所述第三开关、所述第四开关以及所述第五开关中各开关的第三极。
  5. 根据权利要求4所述的中点箝位逆变器，其特征在于，所述控制模块用于控制第一开关、所述第二开关、所述第三开关、所述第四开关以及所述第五开关中各开关的导通或者关断，以选择所述第一开关、所述第三开关以及所述第四开关基于并联电流通路承担导通损耗，或者以选择所述第一开关承担所述开关损耗、所述第三开关或者所述第四开关承担所述导通损耗，或者以选择所述第一开关承担导通损耗、所述第三开关或者所述第四开关承担开关损耗。
  6. 根据权利要求4或5所述的中点箝位逆变器，其特征在于，所述第一开关、所述第二开关、所述第三开关、所述第四开关或者所述第五开关为绝缘栅双极性晶体管IGBT，或者金属氧化物半导体场效应晶体管MOSFET。
  7. 根据权利要求6所述的中点箝位逆变器，其特征在于，所述第一开关、所述第二开关、所述第三开关、所述第四开关或者所述第五开关由硅半导体材料Si，或者第三代宽禁带半导体材料的碳化硅SiC，或者氮化镓GaN制成。
  8. 根据权利要求4-7任一项所述的中点箝位逆变器，其特征在于，所述第一开关为MOSFET，所述第二开关、所述第三开关、所述第四开关以及所述第五开关为IGBT；
    所述第一开关的第一极、第二极以及第三极分别为所述第一开关的漏极、源极以及栅极，所述第二开关、所述第三开关、所述第四开关以及所述第五开关中各开关的第一极为所述各开关的集电极、所述各开关的第二极为所述各开关的发射极、所述各开关的第三极为所述各开关的基极。
  9. 根据权利要求4-7任一项所述的中点箝位逆变器，其特征在于，所述第一开关、所述第二开关以及所述第五开关为IGBT，所述第三开关和所述第四开关为MOSFET；
    所述第一开关、所述第二开关以及所述第五开关中各开关的第一极为所述各开关的集电极、所述各开关的第二极为所述各开关的发射极、所述各开关的第三极为所述各开关的基极，所述第三开关和所述第四开关的第一极为所述第三开关和所述第四开关的漏极、所述第三开关和所述第四开关的第二极为所述第三开关和所述第四开关的源极、所述第三开关和所述第四开关的第三极为所述第三开关和所述第四开关的栅极。
  10. 根据权利要求4-9任一项所述的中点箝位逆变器，其特征在于，所述控制模块还用于生成用于控制所述第一开关、所述第二开关、所述第三开关、所述第四开关以及所述第五开关中各开关的控制信号，所述控制信号用于控制所述各开关的导通或者关断。
  11. 根据权利要求10所述的中点箝位逆变器，其特征在于，所述控制模块用于：
    控制所述第一开关导通，并在第一预设延迟时间之后控制所述第四开关导通，在控制所述第四开关关断之后的第二预设延迟时间后控制所述第一开关关断；
    控制所述第一开关导通，并在第三预设延迟时间之后控制所述第三开关导通，在控制 所述第三开关关断之后的第四预设延迟时间后控制所述第一开关关断。
  12. 根据权利要求10所述的中点箝位逆变器，其特征在于，所述控制模块用于：
    控制所述第四开关导通，并在第一预设延迟时间之后控制所述第一开关导通，在控制所述第一开关关断之后的第二预设延迟时间后控制所述第四开关关断；
    控制所述第三开关导通，并在第三预设延迟时间之后控制所述第一开关导通，在控制所述第一开关关断之后的第四预设延迟时间后控制所述第三开关关断。
  13. 根据权利要求11或12所述的中点箝位逆变器，其特征在于，所述控制模块还用于根据所述第一开关、所述第二开关、所述第三开关、所述第四开关以及所述第五开关中各开关对应的器件结温、和/或流经所述负载的负载电流，确定所述第一预设延迟时间、所述第二预设延迟时间、所述第三预设延迟时间以及所述第四预设延迟时间。
  14. 一种光伏供电系统，其特征在于，所述光伏供电系统包括光伏阵列以及与所述光伏阵列连接的如权利要求1-13任一项所述的中点箝位逆变器。
PCT/CN2021/094124 2020-11-25 2021-05-17 中点箝位逆变器及光伏供电系统 WO2022110685A1 (zh)

Priority Applications (2)

Application Number Priority Date Filing Date Title
EP21896200.9A EP4250550A1 (en) 2020-11-25 2021-05-17 Neutral point clamped inverter and photovoltaic power supply system
US18/321,824 US20230299690A1 (en) 2020-11-25 2023-05-23 Neutral point clamped inverter and photovoltaic power supply system

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CN202011341053.1 2020-11-25
CN202011341053.1A CN114553039A (zh) 2020-11-25 2020-11-25 中点箝位逆变器及光伏供电系统

Related Child Applications (1)

Application Number Title Priority Date Filing Date
US18/321,824 Continuation US20230299690A1 (en) 2020-11-25 2023-05-23 Neutral point clamped inverter and photovoltaic power supply system

Publications (1)

Publication Number Publication Date
WO2022110685A1 true WO2022110685A1 (zh) 2022-06-02

Family

ID=81659896

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/CN2021/094124 WO2022110685A1 (zh) 2020-11-25 2021-05-17 中点箝位逆变器及光伏供电系统

Country Status (4)

Country Link
US (1) US20230299690A1 (zh)
EP (1) EP4250550A1 (zh)
CN (1) CN114553039A (zh)
WO (1) WO2022110685A1 (zh)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115296557A (zh) * 2022-08-30 2022-11-04 北京索英电气技术有限公司 一种有源中点钳位三电平变换器及控制方法

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104333250A (zh) * 2014-10-13 2015-02-04 华南理工大学 用三端开关网络的低电压应力二极管箝位型多电平逆变器
CN106655852A (zh) * 2017-03-20 2017-05-10 哈尔滨理工大学 一种三电平逆变器
CN109980970A (zh) * 2019-04-26 2019-07-05 湖南大学 倍频式三电平逆变器及其使用、封装方法
CN111030440A (zh) * 2019-12-13 2020-04-17 三峡大学 基于混合h桥的单相两管五电平整流器
CN111835221A (zh) * 2020-07-17 2020-10-27 特变电工西安电气科技有限公司 一种dc/ac电力变换装置

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104333250A (zh) * 2014-10-13 2015-02-04 华南理工大学 用三端开关网络的低电压应力二极管箝位型多电平逆变器
CN106655852A (zh) * 2017-03-20 2017-05-10 哈尔滨理工大学 一种三电平逆变器
CN109980970A (zh) * 2019-04-26 2019-07-05 湖南大学 倍频式三电平逆变器及其使用、封装方法
CN111030440A (zh) * 2019-12-13 2020-04-17 三峡大学 基于混合h桥的单相两管五电平整流器
CN111835221A (zh) * 2020-07-17 2020-10-27 特变电工西安电气科技有限公司 一种dc/ac电力变换装置

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115296557A (zh) * 2022-08-30 2022-11-04 北京索英电气技术有限公司 一种有源中点钳位三电平变换器及控制方法

Also Published As

Publication number Publication date
EP4250550A1 (en) 2023-09-27
US20230299690A1 (en) 2023-09-21
CN114553039A (zh) 2022-05-27

Similar Documents

Publication Publication Date Title
US10903656B2 (en) Multilevel inverter device and method
CN112970182A (zh) 具有高频中间交流和两个独立输出的交流-直流三电平转换系统
US9385628B2 (en) Multilevel inverter device and operating method
CN105874703B (zh) 具有软开关切换的逆变器和方法
TWI539737B (zh) 五電平變換裝置
CN113039712B (zh) 双向功率转换系统及控制方法
CN110086360A (zh) 一种五电平高效整流器
TWI539736B (zh) 五電平變換裝置
CN111628668A (zh) 一种采用不对称电压源的九电平逆变器
US20230299690A1 (en) Neutral point clamped inverter and photovoltaic power supply system
Huang et al. Single-phase dual-mode four-switch Buck-Boost Transformerless PV inverter with inherent leakage current elimination
CN111327222B (zh) 一种变流电路
US11088634B2 (en) Inverter with AC forward bridge and improved DC/DC topology
CN107546974B (zh) 具有级联二极管电路的升压电路和逆变器拓扑
CN209767411U (zh) 一种变流电路
Korkh et al. Comparison of soft switching methods of DC-AC full bridge high-frequency link converter
CN109075718B (zh) 功率调节和ups模块
Lou et al. An Improved Modulation Scheme for “Si&SiC” Hybrid 3L-Active NPC Rectifiers with Low Conduction Losses
US20240048070A1 (en) Power converter
CN217984871U (zh) 一种混合整流器
CN212518849U (zh) 一种电机驱动电路
CN211908679U (zh) T型嵌套中性点钳位混合多电平变换器及发电系统
Yin et al. Single-Phase Active Split-Source Inverter with High AC Gain
Guo et al. Novel Control of Dual-Grounded Soft-Switching Transformerless Single-Phase Inverter
CN112968651A (zh) 一种用于功率因数校正的电机驱动电路

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 21896200

Country of ref document: EP

Kind code of ref document: A1

ENP Entry into the national phase

Ref document number: 2021896200

Country of ref document: EP

Effective date: 20230621

NENP Non-entry into the national phase

Ref country code: DE