CN116566232A - Level conversion circuit, inverter and energy storage system thereof - Google Patents

Level conversion circuit, inverter and energy storage system thereof Download PDF

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Publication number
CN116566232A
CN116566232A CN202310762412.8A CN202310762412A CN116566232A CN 116566232 A CN116566232 A CN 116566232A CN 202310762412 A CN202310762412 A CN 202310762412A CN 116566232 A CN116566232 A CN 116566232A
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CN
China
Prior art keywords
voltage
switching tube
energy storage
module
direct
Prior art date
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Pending
Application number
CN202310762412.8A
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Chinese (zh)
Inventor
舒泳皓
刘强
王硕宇
郗子琛
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Shenzhen Sofarsolar Co Ltd
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Shenzhen Sofarsolar Co Ltd
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Priority to CN202310762412.8A priority Critical patent/CN116566232A/en
Publication of CN116566232A publication Critical patent/CN116566232A/en
Pending legal-status Critical Current

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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
    • H02M7/53—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
    • H02M7/5387—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 in a bridge configuration
    • 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
    • H02J3/28—Arrangements for balancing of the load in a network by storage of energy
    • H02J3/32—Arrangements for balancing of the load in a network by storage of energy using batteries with converting means
    • 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
    • H02M1/08—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
    • H02J2300/26—The renewable source being solar energy of photovoltaic origin involving maximum power point tracking control for photovoltaic sources
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy
    • Y02E10/56—Power conversion systems, e.g. maximum power point trackers

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Inverter Devices (AREA)

Abstract

The embodiment of the invention discloses a level conversion circuit, an inverter and an energy storage system thereof. The level conversion circuit includes: the N direct current sides are connected with the controlled driving units of the direct current side voltage sources, and the controlled driving units are configured to respond to the direct current side voltage and correspondingly output first voltage, second voltage or third voltage under the control of the control unit; the N voltage ratios are in equal proportion increasing trend; the alternating current side of the controlled driving unit is connected with the primary side of the corresponding transformer, the secondary sides of the N transformers are connected in series and then output a modulating voltage with 3Nn levels, and the modulating voltage is equivalent to the alternating current voltage under the control of the control unit; the ratio of the voltages of the N transformers is equal to N. By combining the control unit and the mixed cascade modulation, the embodiment of the invention can reduce the temperature rise of the switching tubes under the condition of the same number of switching tubes and avoid the reliability problem caused by the parallel connection of the switching tubes.

Description

Level conversion circuit, inverter and energy storage system thereof
Technical Field
The embodiment of the invention relates to the field of inverters, in particular to a level conversion circuit, an inverter and an energy storage system thereof.
Background
In general, a traditional high-voltage grid-connected inverter adopts a full-bridge or half-bridge inversion mode to charge and discharge, and when the power is too high, the problems caused by the traditional IGBT technology and temperature rise are considered, and the power expansion is carried out by adopting a multi-tube parallel or combined IGBT module structure, so that a plurality of challenges are brought to the actual LAYOUT LAYOUT and software control.
The invention provides the possibility that the renewable energy power generation can be stably and reliably developed in a large power section by combining a mixed cascading inversion mode and CPLD control; the mixed cascade level modulation technology is adopted to realize the pursuit of the grid-connected converter on high voltage, high power, high electric energy quality and low cost.
Disclosure of Invention
In order to solve the technical problems, one technical scheme adopted by the embodiment of the invention is as follows: there is provided a level conversion circuit including: the N direct current sides are connected with the controlled driving units of the direct current side voltage sources, and the controlled driving units are configured to respond to the direct current side voltage and correspondingly output first voltage, second voltage or third voltage under the control of the control unit; the voltage ratio of the N transformers is in an equal ratio increasing trend; the alternating current side of the controlled driving unit is connected with the primary side of the corresponding transformer, the secondary sides of the N transformers are connected in series and then output a modulating voltage with 3Nn levels, and the modulating voltage is equivalent to the alternating current voltage under the control of the control unit; the equal ratio of the voltage ratios of the N transformers is N, the first voltage is the inverse of the third voltage, and the second voltage is 0.
In some embodiments, the controlled driving unit includes a first switching tube, a second switching tube, a third switching tube, and a fourth switching tube, wherein the controlled end of the first switching tube, the controlled end of the second switching tube, the controlled end of the third switching tube, and the controlled end of the fourth switching tube are all connected to the control unit; the first end of the first switching tube is connected with the positive electrode of the direct-current side voltage source, the second end of the first switching tube is connected with the first end of the second switching tube and the first end of the primary side of the corresponding transformer, and the second end of the second switching tube is connected with the negative electrode of the direct-current side voltage source; the first end of the third switching tube is connected with the first end of the first switching tube, the second end of the third switching tube is connected with the first end of the fourth switching tube and the second end of the primary side of the corresponding transformer, and the second end of the fourth switching tube is connected with the negative pole of the direct current side voltage source.
In some embodiments, the types of the first, second, third, and fourth switching transistors include IGBT transistors, MOS transistors, and triode transistors.
In some embodiments, the control unit is a complex programmable logic.
In some embodiments, the equivalence ratio is 3.
In order to solve the technical problems, another technical scheme adopted by the embodiment of the invention is as follows: provided is an inverter including: the level shift circuit as above.
In order to solve the technical problems, another technical scheme adopted by the embodiment of the invention is as follows: there is provided an energy storage system comprising: the photovoltaic module power generation module, the battery module energy storage module, the bus capacitor module and the inverter, wherein the battery module energy storage module is used for storing electric energy and providing direct-current side voltage to the bus capacitor module; the photovoltaic module power generation module is used for converting solar energy into electric energy and providing direct-current side voltage to the bus capacitor module; the bus capacitor module is used for filtering the direct-current side voltage and outputting the direct-current side voltage to the inverter; the inverter outputs a modulated voltage to the grid and to the load in response to the dc side voltage.
In some embodiments, the battery assembly energy storage module includes N energy storage batteries and N bidirectional DC/DC conversion devices, wherein one side of each of the N bidirectional DC/DC conversion devices is connected to both ends of the bus capacitor module, and the other side of each of the N bidirectional DC/DC conversion devices is connected to a corresponding energy storage battery.
In some embodiments, the photovoltaic assembly power generation module includes N photovoltaic power generation assemblies and N DC/DC conversion devices, wherein output sides of the N DC/DC conversion devices are connected to both ends of the bus capacitor module, and input sides of the N DC/DC conversion devices are connected to the respective photovoltaic power generation assemblies.
In some embodiments, the bus capacitor module comprises a plurality of electrolytic capacitors connected in series and parallel, and a thin film capacitor connected in parallel with the plurality of electrolytic capacitors connected in series and parallel.
The beneficial effects of the embodiment of the invention are as follows: compared with the prior art, the embodiment of the invention combines the control unit and the level conversion circuit for modulating the alternating voltage in a mixed cascade manner, so that the temperature rise of the switching tubes can be reduced under the condition of the same number of switching tubes, the reliability problem caused by parallel connection of the switching tubes is avoided, the pursuit of the grid-connected converter on high voltage, high power quality and low cost is realized, and the requirements of different power sections can be adapted; in addition, in the high-power application occasion, the software calculation amount and the LAYOUT LAYOUT workload can be reduced.
Drawings
Fig. 1 is a schematic diagram of a level conversion circuit according to an embodiment of the present invention;
fig. 2 is a circuit configuration diagram of a controlled driving unit according to an embodiment of the present invention;
fig. 3 is a circuit configuration diagram of a level conversion circuit according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of an energy storage system according to an embodiment of the present invention;
fig. 5 is a schematic structural view of a battery pack energy storage module according to an embodiment of the present invention;
fig. 6 is a schematic structural diagram of a photovoltaic module according to an embodiment of the present invention;
fig. 7 is a circuit configuration diagram of an energy storage system according to an embodiment of the present invention.
Detailed Description
In order to facilitate an understanding of the present application, the present application will be described in more detail below with reference to the accompanying drawings and specific examples. It will be understood that when an element is referred to as being "fixed" to another element, it can be directly on the other element or one or more intervening elements may be present therebetween. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or one or more intervening elements may be present therebetween. The terms "upper," "lower," "inner," "outer," "bottom," and the like as used in this specification are used in an orientation or positional relationship based on that shown in the drawings, merely to facilitate the description of the present application and to simplify the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore should not be construed as limiting the present application. Furthermore, the terms "first," "second," "third," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description of the present application in this description is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and/or" as used in this specification includes any and all combinations of one or more of the associated listed items.
In addition, the technical features described below in the different embodiments of the present application may be combined with each other as long as they do not collide with each other.
In some embodiments of the present application, a level conversion circuit is provided, and a schematic structure thereof is shown in fig. 1, and the level conversion circuit includes N controlled driving units 200, N transformers, and a control unit 100.
The signal output ends of the control unit 100 are respectively connected to the controlled ends of the N controlled driving units 200, the N controlled driving units 200 are all connected to a dc side voltage source, the dc side voltage source supplies power to the controlled driving units 200, and the controlled driving units 200 are configured to output a first voltage, a second voltage or a third voltage under the control of the control unit 100 in response to the dc side voltage. I.e. under the supply of the dc side voltage, the first voltage, the second voltage or the third voltage is output in response to different control signals output by the control unit 100, respectively.
The N transformers include a transformer T1, transformers T2, … …, and a transformer TN, and it should be noted that the voltage ratio of the N transformers has an increasing trend in an equal ratio. In the present embodiment, the equal ratio value between the voltage ratios of the transformers is set to n.
The voltage ratio, i.e. the turns ratio of the transformer, i.e. the turns ratio of the primary and secondary windings, is generally referred to as the transformation ratio of the transformer. The transformer is a device for changing AC voltage by using electromagnetic induction principle, and its main components are primary coil, secondary coil and iron core.
For example, the voltage ratio of transformer T1 is 1:M, then the voltage ratio of transformer T2 is 1:nM, and the voltage ratio of transformer T3 is 1: n is n 2 M, … …, the voltage ratio of the transformer TN is 1: n is n N-1 M。
The alternating current side of the controlled driving unit is connected with the primary side of the corresponding transformer, and the secondary sides of the N transformers are connected in series to output a modulating voltage with 3Nn levels. Since the output level of the transformer includes the first voltage, the second voltage, and the third voltage, the level number of the modulation voltage is equal to 3, the number of transformers N, and the ratio N.
In this embodiment, the first voltage is an inverse value of the third voltage, and the second voltage is 0.
Since the secondary sides of the transformers are connected in series, the modulation voltage is the sum of the output voltages of the respective transformers. Under the control of the control unit 100, the modulation voltage is equivalent to an alternating voltage. For example, the control unit 100 controls each controlled driving unit 200 according to the time sequence, and if the first voltage V1 is positive and the third voltage V3 is negative, each controlled driving unit 200 outputs the first voltage V1 at the first moment, and under the action of the corresponding transformer of the controlled driving unit 200, if the voltage output by the transformer T1 is V1 x M, the voltage output by the transformer T2 is V1 x 3*M, and the voltage output by the transformer T2 is V1 x 3 2 * M, … …, transformer TNThe output voltage is V1 x 3 N-1 * M, the total output voltage at the first instant, i.e. the modulation voltage VT1 at the first instant, is V1 (1+3+3) 2 +……+3 N-1 ）*M。
At the second moment, the control unit 100 controls the controlled driving units 200 connected to the transformer T1 to output the second voltage, and the other controlled driving units 200 still output the first voltage V1, and since the second voltage is 0, the modulation voltage VT2 at the second moment is V1 (3+3 2 +……+3 N-1 ) M is reduced by one V1 compared to the modulation voltage VT1 at the first moment.
At a third time, the control unit 100 controls the controlled driving units 200 connected to the transformer T1 to output a third voltage V3, and the other controlled driving units 200 still output the first voltage V1, and since the third voltage V3 is the opposite number of the first voltage V1, the modulation voltage VT3 at the third time is V1 (3+3 2 +……+3 N-1 -1) M, the modulation voltage VT2 is reduced by one V1 compared to the second instant. It can be seen that the level conversion circuit can make the waveform of the output modulation voltage sinusoidal, i.e., make the modulation signal equivalent to the ac signal, under the timing control of the control unit 100.
In some embodiments of the present application, a controlled driving unit 200 is provided, which includes a first switching tube, a second switching tube, a third switching tube, and a fourth switching tube, wherein the controlled ends of the first switching tube, the second switching tube, the third switching tube, and the fourth switching tube are all connected to the control unit 100.
The first end of the first switching tube is connected with the positive electrode of the direct-current side voltage source, the second end of the first switching tube is connected with the first end of the second switching tube and the first end of the primary side of the corresponding transformer, and the second end of the second switching tube is connected with the negative electrode of the direct-current side voltage source.
The first end of the third switching tube is connected with the first end of the first switching tube, the second end of the third switching tube is connected with the first end of the fourth switching tube and the second end of the primary side of the corresponding transformer, and the second end of the fourth switching tube is connected with the negative pole of the direct current side voltage source.
The first switching tube, the second switching tube, the third switching tube and the fourth switching tube form an H bridge circuit, and the H bridge is an electronic circuit and can invert the voltage/current at two ends of a load or an output end connected with the H bridge circuit. The H-bridge is a typical direct current motor control circuit, and can be built in the form of discrete components or integrated on an integrated circuit. The name "H-bridge" originates from its circuit, two parallel branches and one load access/circuit output branch, which appear to constitute a circuit structure shaped like an "H" letter.
The types of the first switching tube, the second switching tube, the third switching tube and the fourth switching tube include an IGBT tube, an MOS tube and a triode.
In some embodiments of the present application, a controlled driving unit 200 constructed with IGBT tubes is provided, a circuit structure diagram of which is shown in fig. 2, and the controlled driving unit 200 includes a first IGBT tube Q1, a second IGBT tube Q2, a third IGBT tube Q3, and a fourth IGBT tube Q4, wherein a base of the first IGBT tube Q1, a base of the second IGBT tube Q2, a base of the third IGBT tube Q3, and a base of the fourth IGBT tube Q4 are all connected to the control unit 100.
The collector of the first IGBT tube Q1 is connected with the positive pole of the direct current side voltage source, the emitter of the first IGBT tube Q1 is connected with the collector of the second IGBT tube Q2 and the first end of the primary side of the corresponding transformer, and the emitter of the second IGBT tube Q2 is connected with the negative pole of the direct current side voltage source.
The collector of the third IGBT tube Q3 is connected with the collector of the first IGBT tube Q1, the emitter of the third IGBT tube Q3 is connected with the collector of the fourth IGBT tube Q4 and the second end of the primary side of the corresponding transformer, and the emitter of the fourth IGBT tube Q4 is connected with the negative pole of the direct current side voltage source.
Based on the above-described controlled driving unit 200, an embodiment of the present invention provides a level conversion circuit, a circuit configuration of which is shown in fig. 3. The level conversion circuit includes a control unit 100, a transformer T1, a transformer T2, a transformer T3, and a corresponding controlled driving unit 200, and the circuit structure of the controlled driving unit 200 is described in the above embodiments, which is not described herein.
The collectors of the first IGBT tubes Q1 of the respective controlled driving units 200 are each connected to the positive electrode of the direct-current side voltage source, and the emitters of the second IGBT tubes Q2 are each connected to the negative electrode of the direct-current side voltage source to introduce the direct-current side voltage Udc. The first end of the secondary side of the transformer T1 is used as the output end of the modulation voltage Vout, the second end of the secondary side of the transformer T1 is connected with the first end of the secondary side of the transformer T2, the second end of the secondary side of the transformer T2 is connected with the first end of the secondary side of the transformer T3, and the second end of the secondary side of the transformer T3 is grounded.
In the embodiment of the present invention, the equal ratio between the voltage ratios of the transformers is 3, that is, if the voltage ratio of the transformer T1 is 1: m, the voltage ratio of the transformer T2 is 1:3M, the voltage ratio of transformer T3 is 1:9M.
The signal output terminals of the control unit 100 are respectively connected to the base of the first IGBT tube Q1, the base of the second IGBT tube Q2, the base of the third IGBT tube Q3, and the base of the fourth IGBT tube Q4 of each controlled driving unit 200.
In the embodiment of the present invention, the control unit 100 is a complex programmable logic device (Complex Programmable Logic Device, CPLD), which is a device developed from PAL and GAL devices, which is relatively large-scale and has a complex structure, and belongs to the scope of large-scale integrated circuits. The method is suitable for the design of a control-intensive digital system, has convenient time delay control, and is one of the fastest-developing devices in the integrated circuit at present. The programmable logic device is composed of a logic array block, a macro unit, an extended product item, a programmable wire array and an I/O control block.
It should be noted that, in this embodiment, 3 transformers and corresponding controlled driving units are taken as an example for illustration, and in practical application, the transformers and corresponding controlled driving units may be increased or decreased according to the requirements. It is emphasized that the minimum number of transformers and corresponding controlled drive units is 2.
The beneficial effects of the embodiment of the invention are as follows: compared with the prior art, the embodiment of the invention combines the control unit and the level conversion circuit for modulating the alternating voltage in a mixed cascade manner, so that the temperature rise of the switching tubes can be reduced under the condition of the same number of switching tubes, and the reliability problem caused by the parallel connection of the switching tubes is avoided.
Based on the level conversion circuit described above, an embodiment of the present invention provides an inverter including the level conversion circuit described in the above-described embodiment.
Based on the inverter described above, the embodiment of the present invention provides an energy storage system, the structure of which is schematically shown in fig. 4, and the energy storage system includes a photovoltaic module power generation module 30, a battery module energy storage module 40, a bus capacitor module 20, and the inverter 10 described above.
The battery pack energy storage module 40 is connected to the bus capacitor module 20, the battery pack energy storage module 40 is used for storing electric energy and providing direct-current side voltage to the bus capacitor module 20, and the battery pack energy storage module 40 realizes Peak Cut and valley fill (Peak Cut) of energy. Peak clipping and valley filling are one measure of adjusting the power load. And according to the electricity utilization rules of different users, reasonably and programmatically arranging and organizing the electricity utilization time of various users. So as to reduce load peak and fill load valley. And the peak-valley difference of the power grid load is reduced, so that the power generation and the power consumption tend to be balanced.
The photovoltaic module 30 is connected to the bus capacitor module 20, and the photovoltaic module 30 is configured to convert solar energy into electric energy and provide a dc side voltage to the bus capacitor module 20; the photovoltaic module power generation module 30 comprises a DC/DC conversion device with multiple MPPT outputs, so that the maximum power point tracking of the photovoltaic power generation module and the energy supply of the system are realized.
Maximum power point tracking (Maximum Power Point Tracking, abbreviated as MPPT) is a core technology in a photovoltaic power generation system, and is to adjust the output power of a photovoltaic array according to different external environment temperatures, illumination intensities and other characteristics, so that the photovoltaic array always outputs the maximum power.
The bus capacitor module 20 is connected to the inverter 10, and the bus capacitor module 20 is used for filtering the direct-current side voltage and outputting the filtered direct-current side voltage to the inverter; the bus capacitor module 20 includes a plurality of electrolytic capacitors connected in series and parallel, and a thin film capacitor connected in parallel with the plurality of electrolytic capacitors connected in series and parallel. The bus capacitor module 20 is used to achieve bus voltage support and power decoupling of ac and dc voltages.
The inverter 10 is connected to the power grid 60 and the load 70, and the inverter 10 outputs a modulated voltage to the power grid 60 and the load 70 in response to the direct-current side voltage.
In some embodiments of the present invention, a battery pack energy storage module 40 is provided, and a schematic structure thereof is shown in fig. 5, where the battery pack energy storage module 40 includes N energy storage batteries 410 and N bidirectional DC/DC conversion devices 420.
Wherein, one sides of the N bidirectional DC/DC conversion devices 420 are connected to two ends of the bus capacitor module 20, an anode port of one side of the bidirectional DC/DC conversion device 420 is connected to an anode of the bus capacitor module 20, and a cathode port of one side of the bidirectional DC/DC conversion device 420 is connected to a cathode of the bus capacitor module 20; the other sides of the N bidirectional DC/DC conversion devices 420 are connected to the corresponding energy storage batteries 410, the positive electrode ports of the other sides of the bidirectional DC/DC conversion devices 420 are connected to the positive electrodes of the corresponding energy storage batteries 410, and the negative electrode ports of the other sides of the bidirectional DC/DC conversion devices 420 are connected to the negative electrodes of the corresponding energy storage batteries 410.
In some embodiments of the present invention, a photovoltaic module 30 is provided, and a schematic structural diagram of the photovoltaic module 30 is shown in fig. 6, where the photovoltaic module 30 includes N photovoltaic modules 310 and N DC/DC converters 320.
Wherein, the output sides of the N DC/DC conversion devices 320 are connected to two ends of the bus capacitor module 20, the positive electrode port of one side of the DC/DC conversion device 320 is connected to the positive electrode of the bus capacitor module 20, and the negative electrode port of one side of the DC/DC conversion device 320 is connected to the negative electrode of the bus capacitor module 20; the input sides of the N DC/DC conversion devices 320 are connected to the corresponding photovoltaic power generation modules 310, the positive electrode ports of the other sides of the DC/DC conversion devices 320 are connected to the positive electrodes of the corresponding photovoltaic power generation modules 310, and the negative electrode ports of the other sides of the DC/DC conversion devices 320 are connected to the negative electrodes of the corresponding photovoltaic power generation modules 310.
The DC/DC converter 320 in this embodiment is a DC/DC converter including an MPPT device, and the MPPT device continuously detects a current-voltage change of the photovoltaic power generation module 310 and adjusts the PWM driving signal duty ratio of the DC/DC converter according to the change.
Based on the above-mentioned photovoltaic module power generation module 30 and battery module energy storage module 40, the embodiment of the present invention provides an energy storage system, the circuit structure diagram of which is shown in fig. 7, in this embodiment, the electrolytic capacitors of the bus capacitor module 20 connected in series and parallel, and the thin film capacitors connected in parallel with the electrolytic capacitors connected in series and parallel are equivalent to a capacitor C1, and the energy storage system includes a control unit 100, a transformer T1, a transformer T2, a transformer T3, 3 controlled driving units 200, a capacitor C1, 3 photovoltaic power generation modules 310, 3 DC/DC conversion devices 320, 3 energy storage batteries 410, and 3 bidirectional DC/DC conversion devices 420.
In this embodiment, the transformer T1, the transformer T2 and the transformer T3 are all low-voltage transformers.
Wherein, the positive electrode ports of one side of the 3 bidirectional DC/DC conversion devices 420 are all connected to the positive electrode of the capacitor C1, and the negative electrode ports of one side of the 3 bidirectional DC/DC conversion devices 420 are all connected to the negative electrode of the capacitor C1; the positive electrode ports of the other sides of the 3 bidirectional DC/DC conversion devices 420 are connected to the positive electrodes of the corresponding energy storage batteries 410, and the negative electrode ports of the other sides of the 3 bidirectional DC/DC conversion devices 420 are connected to the negative electrodes of the corresponding energy storage batteries 410.
The positive electrode ports of one side of the 3 DC/DC conversion devices 320 are all connected to the positive electrode of the capacitor C1, and the negative electrode ports of one side of the 3 DC/DC conversion devices 320 are all connected to the negative electrode of the capacitor C1; the positive electrode ports of the other sides of the 3 DC/DC conversion devices 320 are connected to the positive electrodes of the corresponding photovoltaic power generation modules 310, and the negative electrode ports of the other sides of the 3 DC/DC conversion devices 320 are connected to the negative electrodes of the corresponding photovoltaic power generation modules 310.
The signal output terminals of the control unit 100 are respectively connected to the base of the first IGBT tube Q1, the base of the second IGBT tube Q2, the base of the third IGBT tube Q3, and the base of the fourth IGBT tube Q4 of each controlled driving unit 200.
The collectors of the first IGBT tubes Q1 of the respective controlled driving units 200 are each connected to the positive electrode of the capacitor C1, and the emitters of the second IGBT tubes Q2 are each connected to the negative electrode of the capacitor C1 to introduce the direct-current side voltage Udc.
The primary side of the transformer T1, the primary side of the transformer T2 and the primary side of the transformer T3 are connected to the respective controlled driving units 200, the first end of the secondary side of the transformer T1 is connected to the grid 60 and the load 70 as an output for the modulated voltage Vout, the second end of the secondary side of the transformer T1 is connected to the first end of the secondary side of the transformer T2, the second end of the secondary side of the transformer T2 is connected to the first end of the secondary side of the transformer T3, and the second end of the secondary side of the transformer T3 is grounded.
In this example, in the embodiment of the present invention, the equal ratio between the voltage ratios of the transformers is 3, that is, if the voltage ratio of the transformer T1 is 1:2, the voltage ratio of the transformer T2 is 1:3*2 the voltage ratio of transformer T3 is 1:9*2.
As can be seen in the above-described embodiments, the level conversion circuit constituted by the control unit 100, the transformer T1, the transformer T2, the transformer T3, and the 3 controlled driving units 200 can output a signal having 3Nn levels, i.e. 3 x 3, 27 levels. Assuming that the voltage of the actual power grid 60 is 800V, the secondary side of the transformer T1 can correspondingly generate three levels of 84V, 0 and 84V, and the first voltage output by the controlled driving unit 200 is 42V, the second voltage is 0, and the third voltage is-42V. Therefore, the secondary side of the transformer T2 can correspondingly generate three levels of 252V, 0 and 252V, and the secondary side of the transformer T3 can correspondingly generate three levels of 756V, 0 and 756V, so that the peak-to-peak value of the modulation voltage is 1092V, the waveform of the modulation voltage is close to a sine wave with the effective voltage value of 800V, the output voltage waveform of the corresponding controlled driving unit 200 is obtained, and the switching time sequences of 4 IGBT tubes in each controlled driving unit 200 are further reversely pushed, so that the control effect is achieved.
It should be noted that the number of the energy storage battery, the DC/DC conversion device, the photovoltaic power generation module, the bidirectional DC/DC conversion device, the transformer and the corresponding controlled driving units may be increased or decreased according to practical applications, and the present embodiment is merely illustrative, and the number of the energy storage battery, the DC/DC conversion device, the photovoltaic power generation module, the bidirectional DC/DC conversion device, the transformer and the corresponding controlled driving units is not limited.
Compared with the prior art, the embodiment of the invention combines the control unit and the level conversion circuit for modulating the alternating voltage in a mixed cascade manner, so that the temperature rise of the switching tubes can be reduced under the condition of the same number of switching tubes, the reliability problem caused by parallel connection of the switching tubes is avoided, the pursuit of the grid-connected converter on high voltage, high power, high electric energy quality and low cost is realized, and the requirements of different power sections can be adapted; in addition, in the high-power application occasion, the software calculation amount and the LAYOUT LAYOUT workload can be reduced.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present application, and are not limiting thereof; the technical features of the above embodiments or in the different embodiments may also be combined under the idea of the present application, the steps may be implemented in any order, and there are many other variations of the different aspects of the present application as above, which are not provided in details for the sake of brevity; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims (10)

1. A level shift circuit, comprising:
the N direct current sides are connected with the controlled driving units of the direct current side voltage sources, and the controlled driving units are configured to respond to the direct current side voltage and correspondingly output first voltage, second voltage or third voltage under the control of the control unit;
the voltage ratio of the N transformers is in an equal ratio increasing trend;
the alternating current side of the controlled driving unit is connected with the primary side of the corresponding transformer, the secondary sides of the N transformers are connected in series and then output a modulating voltage with 3Nn levels, and the modulating voltage is equivalent to the alternating current voltage under the control of the control unit;
the equal ratio value between the voltage ratios of the N transformers is N, the first voltage is the inverse value of the third voltage, and the second voltage is 0.
2. The circuit of claim 1, wherein the controlled drive unit comprises a first switching tube, a second switching tube, a third switching tube, and a fourth switching tube, wherein,
the controlled end of the first switching tube, the controlled end of the second switching tube, the controlled end of the third switching tube and the controlled end of the fourth switching tube are all connected to the control unit;
the first end of the first switching tube is connected with the positive electrode of the direct-current side voltage source, the second end of the first switching tube is connected with the first end of the second switching tube and the first end of the primary side of the corresponding transformer, and the second end of the second switching tube is connected with the negative electrode of the direct-current side voltage source;
the first end of the third switching tube is connected with the first end of the first switching tube, the second end of the third switching tube is connected with the first end of the fourth switching tube and the second end of the primary side of the corresponding transformer, and the second end of the fourth switching tube is connected with the negative electrode of the direct-current side voltage source.
3. The circuit of claim 2, wherein the types of the first, second, third, and fourth switching transistors comprise IGBT transistors, MOS transistors, and triode transistors.
4. The circuit of claim 1, wherein the control unit is a complex programmable logic.
5. The circuit of any of claims 1-4, wherein the ratio of equal ratios is 3.
6. An inverter, comprising:
a level shifting circuit as claimed in any one of claims 1 to 5.
7. An energy storage system, comprising: a photovoltaic module power generation module, a battery module energy storage module, a bus capacitor module, and the inverter of claim 6, wherein,
the battery assembly energy storage module is used for storing electric energy and providing direct-current side voltage to the bus capacitor module;
the photovoltaic module power generation module is used for converting solar energy into electric energy and providing direct-current side voltage to the bus capacitor module;
the bus capacitor is used for filtering the direct-current side voltage and outputting the direct-current side voltage to the inverter;
the inverter outputs a modulated voltage to a grid and a load in response to the dc side voltage.
8. The energy storage system of claim 7, wherein the battery pack energy storage module comprises N energy storage cells and N bi-directional DC/DC conversion devices, wherein,
one side of each of the N bidirectional DC/DC conversion devices is connected to two ends of the bus capacitor module, and the other side of each of the N bidirectional DC/DC conversion devices is connected to a corresponding energy storage battery.
9. The energy storage system of claim 7, wherein the photovoltaic module power generation module comprises N photovoltaic modules and N DC/DC conversion devices, wherein,
the output sides of the N DC/DC conversion devices are connected to two ends of the bus capacitor module, and the input sides of the N DC/DC conversion devices are connected to corresponding photovoltaic power generation assemblies.
10. The energy storage system of any of claims 7-9, wherein the bus capacitor module comprises a plurality of electrolytic capacitors connected in series-parallel, and a thin film capacitor connected in parallel with the plurality of electrolytic capacitors connected in series-parallel.
CN202310762412.8A 2023-06-27 2023-06-27 Level conversion circuit, inverter and energy storage system thereof Pending CN116566232A (en)

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CN106253735A (en) * 2016-09-21 2016-12-21 陈钢 Charging and the step inverter of brake energy recovery is driven for electric automobile
CN106416043A (en) * 2014-05-26 2017-02-15 西门子公司 Modular converter system for an electric supply network
CN210405078U (en) * 2019-09-30 2020-04-24 深圳古瑞瓦特新能源股份有限公司 Three-phase multiple power frequency isolation type photovoltaic grid-connected inverter

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20160204688A1 (en) * 2011-07-11 2016-07-14 Chilicon Power, LLC Systems and Methods for Increasing Output Current Quality, Output Power, and Reliability of Grid-Interactive Inverters
CN103457479A (en) * 2012-06-01 2013-12-18 安奕极电源系统有限责任公司 Power supply assembly with an inverter for creating n-phase alternating current
CN102820797A (en) * 2012-07-10 2012-12-12 东营爱特机电技术有限责任公司 Inverter device adopting multi-winding transformer and multi-H-bridge structure and voltage output method thereof
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