CN113271009A - DC/DC conversion unit and energy conversion system - Google Patents

DC/DC conversion unit and energy conversion system Download PDF

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Publication number
CN113271009A
CN113271009A CN202110719532.0A CN202110719532A CN113271009A CN 113271009 A CN113271009 A CN 113271009A CN 202110719532 A CN202110719532 A CN 202110719532A CN 113271009 A CN113271009 A CN 113271009A
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CN
China
Prior art keywords
conversion unit
output port
input
voltage
conversion
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Pending
Application number
CN202110719532.0A
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Chinese (zh)
Inventor
陈鹏
孙帅
丁杰
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Sungrow Power Supply Co Ltd
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Sungrow Power Supply Co Ltd
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Publication date
Application filed by Sungrow Power Supply Co Ltd filed Critical Sungrow Power Supply Co Ltd
Priority to CN202110719532.0A priority Critical patent/CN113271009A/en
Publication of CN113271009A publication Critical patent/CN113271009A/en
Priority to PCT/CN2021/137761 priority patent/WO2023273190A1/en
Pending legal-status Critical Current

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    • 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
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
    • H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
    • H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac 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
    • H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac 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
    • H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac 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 with automatic control of output voltage or current, e.g. switching regulators
    • 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
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
    • H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
    • H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac 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
    • H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac 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
    • H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac 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 with automatic control of output voltage or current, e.g. switching regulators
    • H02M3/158—Conversion of dc power input into dc power output without intermediate conversion into ac 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 with automatic control of output voltage or current, e.g. switching regulators including plural semiconductor devices as final control devices for a single load
    • H02M3/1582—Buck-boost converters
    • 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
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
    • H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
    • H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/33507—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of the output voltage or current, e.g. flyback converters
    • H02M3/33523—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of the output voltage or current, e.g. flyback converters with galvanic isolation between input and output of both the power stage and the feedback loop
    • 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
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
    • H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
    • H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/33569—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02S—GENERATION OF ELECTRIC POWER BY CONVERSION OF INFRARED RADIATION, VISIBLE LIGHT OR ULTRAVIOLET LIGHT, e.g. USING PHOTOVOLTAIC [PV] MODULES
    • H02S40/00—Components or accessories in combination with PV modules, not provided for in groups H02S10/00 - H02S30/00
    • H02S40/30—Electrical components
    • H02S40/32—Electrical components comprising DC/AC inverter means associated with the PV module itself, e.g. AC modules
    • 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
    • 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
    • H02J2300/28—The renewable source being wind energy
    • 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)
  • Dc-Dc Converters (AREA)
  • Inverter Devices (AREA)

Abstract

The application provides a DC/DC conversion unit and an energy conversion system, wherein the input end of a main circuit of the DC/DC conversion unit is provided with a first input port and a second input port, and the output end of the main circuit is provided with a first output port, a second output port and a third output port; wherein: the voltage of the first input port is greater than that of the second input port; the voltage of the first output port is positive, the voltage regulation target of the second output port is zero, and the voltage of the third output port is negative; and at least one output port is directly connected with the corresponding input port so as to connect the input end and the output end of the DC/DC conversion unit in series, thereby connecting the input voltage and the output voltage of the DC/DC conversion unit in series, improving the output voltage of the DC/DC conversion unit and greatly reducing the transmission current and line loss of the output end of the DC/DC conversion unit.

Description

DC/DC conversion unit and energy conversion system
Technical Field
The invention belongs to the technical field of power conversion, and particularly relates to a DC/DC conversion unit and an energy conversion system.
Background
At present, inverters in a photovoltaic power generation system mainly comprise three types, namely a group series type inverter, a centralized type inverter and a distributed type inverter. For both centralized and distributed inverters, the pv strings need to be converged by a combiner box, and connected to an inverter placed near the box transformer after being routed for a long distance, as shown in fig. 1.
In the prior art, in order to reduce the line loss, the line diameter of the bus cable is generally increased, but the cost of the cable is increased.
Disclosure of Invention
In view of the above, the present invention provides a DC/DC conversion unit and an energy conversion system, which are used to reduce line loss during power transmission, reduce the cost of the DC/DC conversion unit, and simplify the conversion.
The invention discloses a DC/DC conversion unit, wherein the input end of a main circuit is provided with a first input port and a second input port, and the output end of the main circuit is provided with a first output port, a second output port and a third output port; wherein:
the voltage of the first input port is greater than the voltage of the second input port;
the voltage of the first output port is a positive voltage, the voltage of the second output port is adjusted to zero, and the voltage of the third output port is a negative voltage;
and at least one output port is directly connected to a corresponding input port so that the input and output terminals of the DC/DC conversion unit are connected in series.
Optionally, the second output port is directly connected to the second input port.
Optionally, the voltage difference between the second output port and the third output port is obtained by converting the voltage received by the input end of the main circuit.
Optionally, the method includes: at least one of a non-isolated boost circuit, a buck-boost circuit, a buck circuit, and a dc conversion unit with an isolation transformer.
Optionally, the voltage of the first output port is greater than or equal to the voltage of the first input port.
Optionally, the voltage of the first output port and the voltage of the third output port are symmetrical about the second output port.
Optionally, the first output port is directly connected to the first input port, so that the voltage at the first output port is equal to the voltage at the first input port;
the first output port is indirectly connected to the first input port, so that the voltage of the first output port is greater than the voltage of the first input port.
Optionally, when the first output port is indirectly connected to the first input port, the main circuit includes: a first conversion circuit and a second conversion circuit;
the input end of the first conversion circuit and the input end of the second conversion circuit are connected to the input end of the main circuit in parallel;
the voltage difference between the second output port and the third output port is obtained by converting the voltage received by the input end of the first conversion circuit;
and the voltage difference between the first output port and the second output port is obtained after the second conversion circuit converts the voltage received by the input end of the second conversion circuit.
Optionally, the first converting circuit and the second converting circuit respectively include: at least one of a non-isolated boost circuit, a buck-boost circuit, a buck circuit, and a dc conversion unit with an isolation transformer.
Optionally, the main circuit includes: the buck-boost circuit;
the positive electrode of the input end of the buck-boost circuit is connected with the first input port;
the negative electrode of the input end of the buck-boost circuit is connected with the second input port;
the positive electrode of the output end of the buck-boost circuit is connected with the second output port;
and the negative electrode of the output end of the buck-boost circuit is connected with the third output port.
Optionally, the first converting circuit includes: the buck-boost circuit, the second transform circuit comprising: the boost circuit;
the positive electrode of the input end of the buck-boost circuit and the positive electrode of the input end of the boost circuit are both connected with the first input port;
the negative electrode of the input end of the buck-boost circuit and the negative electrode of the input end of the boost circuit are both connected with the second input port;
the positive electrode of the output end of the buck-boost circuit and the negative electrode of the output end of the boost circuit are connected with the second output port;
the negative electrode of the output end of the buck-boost circuit is connected with the third output port;
and the positive electrode of the output end of the boost circuit is connected with the first output port.
In a second aspect of the present invention, there is disclosed an energy conversion system comprising: at least one direct current input source, and at least one DC/DC conversion unit according to any one of the first aspect of the invention;
the input end of the DC/DC conversion unit is directly or indirectly connected with the corresponding direct current input source;
and the output end of the DC/DC conversion unit is directly or indirectly connected with the output end of the energy conversion system.
Optionally, the system further comprises at least one inverter;
the output end of the DC/DC conversion unit is connected with the direct current side of the inverter through a corresponding cable;
and the alternating current side of the inverter is connected with the output end of the energy conversion system.
Optionally, when the number of the inverters is 1:
a first output port of the DC/DC conversion unit is connected with a direct current side positive electrode of the inverter through a positive line;
and a third output port of the DC/DC conversion unit is connected with a direct current side negative electrode of the inverter through a negative line.
Optionally, the dc side of the inverter includes three ports or two ports;
when the direct current side of the inverter comprises two ports, the midpoint of the direct current side arranged in the inverter is grounded through a first grounding unit arranged in the inverter;
when the direct current side of the inverter comprises three ports, a midpoint of the direct current side arranged outside the inverter is grounded through a first grounding unit arranged outside the inverter, or a second output port of the DC/DC conversion unit is connected with the midpoint of the direct current side of the inverter through a zero line.
Optionally, when the number of the inverters is 2, and the inverters are respectively a first inverter and a second inverter:
a first output port of the DC/DC conversion unit is connected with a direct current side positive electrode of the first inverter through a positive line;
a second output port of the DC/DC conversion unit is respectively connected with the DC side cathode of the first inverter and the DC side anode of the second inverter through a zero line;
and a third output port of the DC/DC conversion unit is connected with a direct current side negative electrode of the second inverter through a negative line.
Optionally, a connection point between the negative electrode of the DC side of the first inverter and the positive electrode of the DC side of the second inverter is grounded through the first grounding unit, or is connected to the second output port of the DC/DC conversion unit through a zero line.
Optionally, the method further includes: a second grounding unit;
the second grounding unit is used for realizing the coupling connection or decoupling disconnection between the second output port of the DC/DC conversion unit and the equipotential of the ground.
Optionally, the second grounding unit includes: the switch power supply, the impedance unit, the third diode and the third capacitor;
the positive electrode of the input end of the switching power supply is connected with the first input port of the DC/DC conversion unit;
the negative electrode of the input end of the switching power supply is connected with the second input port;
the positive electrode of the output end of the switching power supply is connected with one end of the third capacitor, and a connection point is connected with the second output port of the DC/DC conversion unit through the impedance unit and the third diode in sequence;
and the negative electrode of the output end of the switching power supply is connected with the other end of the third capacitor, and the connection point is connected with the earth equipotential.
Optionally, the switching power supply includes: the energy storage element and the switching tube are connected in series.
Optionally, the second grounding unit includes: a controllable switch;
the second output port is connected with the earth equipotential through the controllable switch.
Optionally, the method further includes: at least one combiner box;
each combiner box is respectively arranged between the input end of the DC/DC conversion unit and the corresponding direct current input source.
Optionally, the combiner box further includes at least one DC/DC conversion module to implement a first-stage voltage conversion before the DC/DC conversion unit.
Optionally, the direct current input source is at least one of a photovoltaic power generation unit, an AC/DC conversion unit and an energy storage unit.
Optionally, the direct current input sources connected to the input terminals of the respective DC/DC conversion units are the same, or the direct current input sources connected to the input terminals of at least two DC/DC conversion units are different.
Optionally, the DC side of the AC/DC conversion unit is connected to the input terminal of the DC/DC conversion unit;
and the alternating current side of the AC/DC conversion unit is connected with a power grid or a wind power generation unit.
According to the technical scheme, the input end of the main circuit of the DC/DC conversion unit is provided with a first input port and a second input port, and the output end of the main circuit is provided with a first output port, a second output port and a third output port; wherein: the voltage of the first input port is greater than that of the second input port; the voltage of the first output port is positive, the voltage regulation target of the second output port is zero, and the voltage of the third output port is negative; and at least one output port is directly connected with a corresponding input port so as to connect the input end and the output end of the DC/DC conversion unit in series; therefore, the input voltage and the output voltage of the DC/DC conversion unit are connected in series, the output voltage of the DC/DC conversion unit is improved, and the transmission current and the line loss of the output end of the DC/DC conversion unit are greatly reduced. In addition, the DC/DC conversion unit is only used for generating the boosted voltage of the lower half part, and the power is close to half of the input power of the photovoltaic combiner box, so that the added equipment cost is low, and the conversion is simple.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.
FIG. 1 is a schematic diagram of a photovoltaic power generation system provided by the prior art;
fig. 2 is a schematic diagram of a DC/DC conversion unit and an energy conversion system according to an embodiment of the present invention;
fig. 3 is a schematic diagram of a DC/DC conversion unit according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of another DC/DC conversion unit provided by an embodiment of the present invention;
FIG. 5 is a schematic diagram of another DC/DC conversion unit provided by an embodiment of the present invention;
FIG. 6 is a schematic diagram of another energy conversion system provided by an embodiment of the present invention;
FIG. 7 is a schematic diagram of another energy conversion system provided by an embodiment of the present invention;
FIG. 8 is a schematic diagram of an inverter in the energy conversion system provided by an embodiment of the present invention;
fig. 9 is a schematic diagram of a second grounding unit according to an embodiment of the present invention;
fig. 10 is another schematic diagram of the second grounding unit according to the embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In this application, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
Embodiments of the present invention provide a DC/DC conversion unit, which is used to solve the problem of increasing cable cost caused by increasing the wire diameter of a bus cable in order to reduce wire loss in the prior art.
Referring to fig. 2, in the DC/DC conversion unit 10, an input end of a main circuit is provided with a first input port and a second input port, and an output end of the main circuit is provided with a first output port, a second output port, and a third output port; wherein:
the voltage of the first input port is greater than that of the second input port; the voltage of the first output port is a positive voltage, the voltage regulation target of the second output port is zero, and the voltage of the third output port is a negative voltage. That is, the DC/DC conversion unit includes three output ports and two input ports. The second output port serves as an output end zero point, the voltage of the second output port can actually fluctuate within a small range near zero, and the fluctuation range is not particularly limited.
And at least one output port is directly connected to a corresponding input port so that the input and output terminals of the DC/DC conversion unit are connected in series.
The DC/DC conversion unit 10 performs DC power conversion of voltages inputted from 2 ports to convert the voltages into 3 ports for output.
Specifically, the DC/DC conversion unit 10 DC/DC converts the voltage V1 between the first input terminal and the second input terminal to obtain a voltage V2. Moreover, since the input and output of the DC/DC conversion unit 10 are connected in series, the obtained voltage V2 at least includes the series value of the output voltage of the DC/DC conversion unit 10 and the voltage V1, and may be larger than the series value; that is, a higher output voltage is obtained by the series connection of at least V1 and V2, thereby greatly reducing the transmission current at the output terminal.
In this embodiment, the input voltage and the output voltage of the DC/DC conversion unit 10 are connected in series, so that the output voltage of the DC/DC conversion unit 10 is increased, and the transmission current and the line loss at the output terminal are greatly reduced.
In practical applications, the first input port of the DC/DC conversion unit 10 is directly connected to the second output port of the DC/DC conversion unit 10.
The voltage difference between the second output port of the DC/DC conversion unit 10 and the third output port of the DC/DC conversion unit 10 is obtained by converting the voltage received by the input terminal of the main circuit.
Specifically, the main circuit may perform voltage boost conversion and/or voltage buck conversion on the voltage received by its input terminal, which is not specifically limited herein, and is determined according to the actual situation, and is within the protection scope of the present application.
In practical applications, the DC/DC conversion unit 10 includes: at least one of a non-isolated boost circuit, a buck-boost circuit, a buck circuit, and a dc conversion unit with an isolation transformer.
That is, the DC/DC conversion unit 10 may have various structures, such as only one of a non-isolated boost circuit, a buck-boost circuit, a buck circuit, and a DC conversion unit with an isolation transformer; or any combination of four structures of a non-isolated boost circuit, a buck-boost circuit, a buck circuit and a direct current conversion unit with an isolation transformer. The type of the DC/DC conversion unit 10 is not specifically limited, and is within the protection scope of the present application.
At this time, since the DC/DC conversion unit 10 is used only for generating the boosted voltage of the lower half and the power is close to half of the input power of the photovoltaic combiner box 20, the increased equipment cost is low and the conversion is simple.
Optionally, the voltage at the first output port of the DC/DC conversion unit 10 is greater than or equal to the voltage at the first input port of the DC/DC conversion unit; that is, the voltage at the first output port of the DC/DC conversion unit 10 may be equal to the voltage at the first input port thereof, for example, the first output port of the DC/DC conversion unit 10 is directly connected to the first input port thereof; or, the first output port of the DC/DC conversion unit 10 is connected to the first input port of the DC/DC conversion unit 10 through a corresponding module, so that the voltage at the first output port of the DC/DC conversion unit 10 is greater than the voltage at the first input port of the DC/DC conversion unit.
When the first output port of the DC/DC conversion unit 10 is directly connected to the first input port of the main circuit, the main circuit is only used for converting the voltage received by the input port of the main circuit, so as to obtain a voltage difference between the second output port of the DC/DC conversion unit 10 and the third output port of the DC/DC conversion unit 10, as shown at 111 in fig. 3.
When the first output port of the DC/DC conversion unit 10 is indirectly connected to the first input port of the DC/DC conversion unit 10, the main circuit includes: a first transformation circuit (111 as shown in fig. 4) and a second transformation circuit (112 as shown in fig. 4).
The input end of the first conversion circuit and the input end of the second conversion circuit are connected to the input end of the main circuit in parallel.
The voltage difference between the second output port of the DC/DC conversion unit 10 and the third output port of the DC/DC conversion unit 10 is obtained by converting the voltage received by the input terminal of the first conversion circuit.
The voltage difference between the first output port of the DC/DC conversion unit 10 and the second output port of the DC/DC conversion unit 10 is obtained by converting the voltage received by the input terminal of the second conversion circuit.
In practical applications, the first converting circuit and the second converting circuit respectively include: at least one of a non-isolated boost circuit, a buck-boost circuit, a buck circuit, and a dc conversion unit with an isolation transformer.
In practical applications, the voltage at the first output port of the DC/DC conversion unit 10 and the voltage at the third output port may be symmetrical with respect to the second output port.
In this embodiment, the voltage at the first output port of the DC/DC conversion unit 10 is greater than or equal to the voltage at the first input port thereof, so that the voltage output by the DC/DC conversion unit 10 can be greater than or equal to V1+ V2, thereby ensuring that the output voltage thereof is increased.
As is apparent from the above description, the DC/DC conversion unit 10 includes: at least one of a boost circuit, a buck-boost circuit, a buck circuit and a dc conversion unit with a high frequency isolation transformer. The specific structure of the DC/DC conversion unit 10 is not described in detail here, and all that is required is that the DC/DC conversion unit can perform a boost conversion function on the input voltage, which is within the protection scope of the present application.
Specifically, the first input port of the DC/DC conversion unit 10 may not participate in conversion, and is directly connected to the corresponding output port, and 0, -V2 is obtained through power conversion, the circuit diagram of the DC/DC conversion unit 10 is shown in fig. 3 when only the buck-boost circuit 111 is included in the DC/DC conversion unit, the structure shown in fig. 3 is merely an example, and the other multi-level buck-boost circuit 111 may also be mainly used for completing the conversion of the-V2 voltage. The DC/DC conversion unit 10 may also be a non-isolated circuit, as shown in fig. 4; it can also be an isolation circuit, as shown in fig. 5, under these two structures, through power conversion, it can get + V2, 0, -V2.
The following explains three cases in which the DC/DC conversion unit 10 includes only the buck-boost circuit 111, the DC/DC conversion unit 10 includes the boost circuit 112 and the buck-boost circuit 111, and the DC/DC conversion unit 10 includes a direct-current conversion unit, respectively:
(1) as shown in fig. 3, when the DC/DC conversion unit 10 includes only the buck-boost circuit 111:
the positive pole of the input end of the buck-boost circuit 111 is connected with the first input port of the DC/DC conversion unit 10; the cathode of the input terminal of the buck-boost circuit 111 is connected to the second input port of the DC/DC conversion unit 10.
The positive electrode of the output end of the buck-boost circuit 111 is connected with the second output port of the DC/DC conversion unit 10; the negative electrode of the output end of the buck-boost circuit 111 is connected with the third output port of the DC/DC conversion unit 10; a first output port of the DC/DC conversion unit 10 is connected to the positive terminal of the input terminal of the buck-boost circuit 111.
In practical applications, the buck-boost circuit 111 includes: the first diode D1, the first inductor L1, the first capacitor C1 and the at least one first switch Q1 enable the buck-boost circuit 111 to perform the functions of boosting and reducing the input voltage.
Specifically, one end of the first switching tube Q1 is used as the positive electrode of the input end of the buck-boost circuit 111, and is simultaneously connected to the first output port of the DC/DC conversion unit 10 and the first input port of the DC/DC conversion unit 10; the other end of the first switch tube Q1 is connected to one end of a first inductor L1 and the cathode of a first diode D1; the anode of the first diode D1 is connected to one end of the first capacitor C1, and the connection point is used as the negative electrode of the output terminal of the buck-boost circuit 111 and is connected to the third output port of the DC/DC conversion unit 10; the other end of the first inductor L1 is connected to the other end of the first capacitor C1, and the connection points are used as the positive electrode of the output terminal and the negative electrode of the input terminal of the buck-boost circuit 111, and are respectively connected to the second output port and the second input port of the DC/DC conversion unit 10.
(2) As shown in fig. 4, when the DC/DC conversion unit 10 includes the boost circuit 112 and the buck-boost circuit 111:
the positive pole of the input end of the buck-boost circuit 111 and the positive pole of the input end of the boost circuit 112 are both connected with a first input port of the DC/DC conversion unit 10; the cathode of the input end of the buck-boost circuit 111 and the cathode of the input end of the boost circuit 112 are both connected with the second input port of the DC/DC conversion unit 10.
The positive electrode of the output end of the buck-boost circuit 111 and the negative electrode of the output end of the boost circuit 112 are both connected with the second output port of the DC/DC conversion unit 10; the negative electrode of the output end of the buck-boost circuit 111 is connected with the third output port of the DC/DC conversion unit 10; the output terminal anode of the boost circuit 112 is connected to the first output terminal of the DC/DC conversion unit 10.
In practical applications, the buck-boost circuit 111 includes: the first diode D1, the first inductor L1, the first capacitor C1 and the at least one first switch Q1, so that the buck-boost circuit 111 can perform the functions of boosting and reducing the input voltage; wherein: one end of the first switching tube Q1 is used as the positive electrode of the input end of the buck-boost circuit 111 and is connected with the first input port of the DC/DC conversion unit 10; the other end of the first switch tube Q1 is connected to one end of a first inductor L1 and the cathode of a first diode D1; the anode of the first diode D1 is connected to one end of the first capacitor C1, and the connection point is used as the negative electrode of the output terminal of the buck-boost circuit 111 and is connected to the third output port of the DC/DC conversion unit 10; the other end of the first inductor L1 is connected to the other end of the first capacitor C1, and the connection points are used as the positive electrode of the output terminal and the negative electrode of the input terminal of the buck-boost circuit 111, and are respectively connected to the second output port of the DC/DC conversion unit 10 and the second input port of the DC/DC conversion unit 10.
The boost circuit 112 includes: the second diode D2, the second inductor L2, the second capacitor C2 and the at least one second switch Q2, so that the boost circuit 112 can perform a step-down conversion function on the input voltage; wherein: one end of the second switch Q2 is connected to one end of the second capacitor C2, and the connection point is used as the negative terminal of the input terminal and the negative terminal of the output terminal of the boost circuit 112, and is connected to the second input port of the DC/DC conversion unit 10 and the second output port of the DC/DC conversion unit 10. The other end of the second switching tube Q2 is connected to the anode of the second diode D2 and one end of the second inductor L2, respectively; the other end of the second inductor L2 is used as the positive electrode of the input end of the boost circuit 112 and is connected with the first input port of the DC/DC conversion unit 10; the cathode of the second diode D2 is connected to the other end of the second capacitor C2, and the connection point is used as the anode of the output terminal of the boost circuit 112 and connected to the first output port of the DC/DC converter unit 10.
(3) As shown in fig. 5, the dc conversion unit includes: an input capacitor Cvin, an output capacitor Cout, a bridge circuit (including Q1, Q2, Q3 and Q4 shown in FIG. 5), an inductive reactance and a high-frequency transformer T; wherein:
the input capacitor Cvin, the output capacitor Cout, the bridge circuit (including Q1, Q2, Q3 and Q4 shown in fig. 5), the inductive reactance CL and the high-frequency transformer T are combined, so that the dc conversion unit realizes the function of boosting or reducing the input voltage.
Specifically, two ends of the input capacitor Cvin are respectively connected to the positive electrode and the negative electrode on the direct current side of the bridge circuit, the positive electrode on the direct current side of the bridge circuit is connected to the first input port of the DC/DC conversion unit 10, and the negative electrode on the direct current side of the bridge circuit is connected to the second input port of the DC/DC conversion unit 10; one end of the alternating current side of the bridge circuit is connected with one end of a primary winding in the high-frequency transformer T through an inductive reactance and capacitance device CL; the other end of the AC side of the bridge circuit is connected with the other end of the primary winding. The bridge circuit comprises 4 switching tubes; one end of a first switching tube Q1 is connected with one end of a third switching tube Q3, the connection point is used as the positive pole of the direct current side of the bridge circuit, the other end of the first switching tube Q1 is connected with one end of a second switching tube Q2, the connection point is used as one end of the alternating current side of the bridge circuit and is connected with one end of a primary winding in the high-frequency transformer T through an inductive reactance and capacitance device CL; the other end of the second switching tube Q2 is connected to one end of the fourth switching tube Q4, and the connection point is used as the dc side negative electrode of the bridge circuit, the other end of the third switching tube Q3 is connected to the other end of the fourth switching tube Q4, and the connection point is used as the ac side end of the bridge circuit and is connected to the other end of the primary winding in the high frequency transformer T.
Two ends of a secondary winding in the high-frequency transformer T are respectively connected with two ends of the output capacitor Cout, and connection points are respectively used as a third output port and a second output port of the DC/DC conversion unit 10.
A second output port of the DC/DC conversion unit 10 is connected to a second input port of the DC/DC conversion unit 10; a first output port of the DC/DC conversion unit 10 is connected to a first input port of the DC/DC conversion unit 10.
It should be noted that the specific structure of the DC/DC conversion unit 10 is not limited to the structures shown in fig. 3, fig. 4, and fig. 5, and other structures and connection relations thereof are not described herein again, and all that is required is that the DC/DC conversion unit 10 has 2 input ports and 3 output ports, and at least one direct connection exists between the input end and the corresponding output end of the DC/DC conversion unit 10, which is within the protection scope of the present application.
In the present embodiment, the DC/DC conversion unit 10 increases the working voltage after the current collection, so that the current is reduced under the same power, the cable loss is reduced, the cable diameter requirement is reduced, and the cost of the cable and the accessories is reduced. Compared with the structure shown in fig. 3 and 5, the structure shown in fig. 4 has the advantage that the voltage of the positive electrode of the output end is larger than that of the positive electrode of the input end, so that the transmission current and the line loss of the output end are further reduced.
Another embodiment of the present invention provides an energy conversion system, referring to fig. 2, including: at least one direct current input source 30 (shown in fig. 2 by way of example as a photovoltaic power generation unit) and at least one DC/DC conversion unit 10 as described in any of the above embodiments.
The input terminals of the DC/DC conversion unit 10 are directly or indirectly connected to the corresponding DC input source 30.
Specifically, the dc input source 30 is at least one of the photovoltaic power generation unit and the energy storage unit, and the kind of the dc input power 30 is not described herein any more, and is determined according to the actual situation, and is all within the protection scope of the present application.
The direct current input sources connected to the input terminals of the respective DC/DC conversion units 10 are the same; or, the direct current input sources connected to the input terminals of at least two DC/DC conversion units 10 are different, that is, the direct current input sources connected to the input terminals of the DC/DC conversion units 10 may be the same or different, and are not specifically limited herein, and all of them are within the protection scope of the present application, depending on the actual situation.
The output end of the DC/DC conversion unit 10 is directly or indirectly connected to the output end of the energy conversion system.
In practical applications, the energy conversion system may further include: at least one inverter 40.
The DC/DC conversion unit 10 is connected to the DC side of the inverter 40 via a corresponding cable; the ac side of the inverter 40 is connected to the output of the energy conversion system, which may be connected to the grid through a transformer or may be supplied to the electric vehicle through a charging gun. The connection relationship of the output ends of the energy conversion system is not specifically limited herein, and is within the protection scope of the present application as the case may be.
In practical applications, when the number of inverters is 1, see fig. 6 or fig. 7: a first output port of the DC/DC conversion unit 10 is connected to the DC-side positive electrode of the inverter 40 through a positive line; a third output port of the DC/DC conversion unit 10 is connected to the DC-side negative electrode of the inverter 40 via a negative line.
The dc side of the inverter 40 includes three ports or two ports; when the dc side of the inverter 40 includes two ports, a dc side midpoint provided in the inverter 40 is grounded via a first grounding means provided in the inverter 40 (not shown); when the DC side of the inverter 40 includes three ports, a DC side midpoint disposed outside thereof is grounded through a first grounding unit disposed outside thereof (as shown in fig. 7), or a second output port of the DC/DC conversion unit 10 is connected to the DC side midpoint of the inverter 40 through a zero line (as shown in fig. 6). In two cases where the number of the dc side ports of the inverter 40 is different, the two types of first grounding units may have the same function and structure, but are different in arrangement position, and this time is not particularly limited, and it is sufficient to connect the dc side midpoint of the inverter 40 to ground.
When the number of inverters is 2, respectively the first inverter 40 and the second inverter 40, see fig. 8: a first output port of the DC/DC conversion unit 10 is connected to the DC-side positive electrode of the first inverter 40 through a positive line; a DC-side negative electrode of the first inverter 40 is connected to a DC-side positive electrode of the second inverter 40, and a third output port of the DC/DC converter unit 10 is connected to a DC-side negative electrode of the second inverter 40 via a negative line; in this case, the inverter 40 is a two-port inverter.
A connection point between the DC negative electrode of the first inverter 40 and the DC positive electrode of the second inverter 40 is grounded via the first grounding means, or is connected to the second output port of the DC/DC conversion unit 10 via a zero line.
In practical applications, the energy conversion system further comprises: at least one combiner box 20; the combiner boxes 20 are respectively disposed between the input terminals of the DC/DC conversion units 10 and the corresponding DC input sources 30.
For details of a specific working process and principle of the DC/DC conversion unit 10, reference is made to the DC/DC conversion unit 10 provided in any embodiment, and details are not described here any more, and all of them are within the protection scope of the present application.
It should be noted that, according to the structure shown in fig. 1, the output voltage of the combiner box 20 can be increased, so that the output current can be reduced under the same power, one scheme is to increase the output voltage by adding a DC/DC unit in the combiner box 20, and the other scheme is to further increase the voltage by connecting a DC/DC unit in series on the basis of the DC/DC unit in the combiner box 20, but this greatly increases the cost of power conversion.
In the embodiment, the DC/DC conversion unit 10 is independent of the combiner boxes 20, and one DC/DC conversion unit 10 may correspond to a plurality of combiner boxes 20, so as to reduce the hardware cost of the energy conversion system, and meanwhile, the output end of the DC/DC conversion unit 10 is connected to the DC side of the inverter 40 through a corresponding cable, so as to implement low-cost and low-line-loss long-distance transmission.
In practical applications, the combiner box 20 may be a general combiner box that does not include a DC/DC conversion module. Of course, the combiner box 20 may further include at least one DC/DC conversion module to implement a first-stage voltage conversion for the corresponding DC input source 30 before the DC/DC conversion unit 10. The method is not particularly limited, and is within the scope of the present application as appropriate.
In practical applications, in order to reduce the voltage fluctuation of the second output port of the DC/DC conversion unit 10 and make it as stable as possible to zero, the present embodiment is based on any of the above embodiments, referring to fig. 6 or fig. 7, where the DC/DC conversion unit 10 may further include: a second grounding element 12.
The second grounding unit 12 is used for realizing coupling connection or decoupling disconnection between the second output port of the DC/DC conversion unit 10 and the equipotential of the ground; that is, the second grounding unit 12 is controlled so that the zero line of the DC/DC conversion unit 10 has the same potential as the ground.
In practical applications, the second grounding unit 12 may include a power transistor, an inductor, a transformer, a relay, a resistor, and the like, and the structure thereof has various structures, which are not described herein again, and the following two cases are exemplified:
(1) referring to fig. 9, the second grounding unit 12 includes: the circuit comprises a switching power supply E, an impedance Z unit, a third diode and a third capacitor.
The positive electrode of the input end of the switching power supply E is connected with a first input port of the DC/DC conversion unit 10; the negative electrode of the input end of the switching power supply E is connected with the second input port of the DC/DC conversion unit 10; the positive electrode of the output end of the switching power supply E is connected with one end of a third capacitor, and a connection point is connected with a second output port of the DC/DC conversion unit 10 through an impedance Z unit and a third diode in sequence; and the negative electrode of the output end of the switching power supply E is connected with the other end of the third capacitor, and the connecting point is connected with the earth and the same potential.
Optionally, the switching power supply E includes an energy storage element and a switching tube connected in series.
(2) Referring to fig. 10, the second grounding unit 12 includes: controllable switch S1. The second output port of the DC/DC conversion unit 10 is connected to ground through the controllable switch S1 to have equal potential. Specifically, one end of the controllable switch S1 is connected to the second output port of the DC/DC conversion unit 10, and the other end of the controllable switch S1 is connected to the earth equipotential.
The DC/DC conversion unit 10 performs power conversion on the input voltage V1 to boost voltage and output two symmetrical voltages V2, because the zero line potential is the same as the ground and V2 is lower than the system voltage, it can be ensured that the working voltage does not exceed the system voltage. After the voltage of V1 is boosted by DC/DC converter 10, the current output by the bus is greatly reduced for the same power. Through long-distance transmission, if the cable is not changed, the line loss can be greatly reduced; if the current-carrying capacity is not changed, the requirement of the wire diameter can be greatly reduced, and the cost is reduced. Because the zero line is guaranteed to be equipotential with the ground all the time, the insulation cost of the cable is not increased, and the maximum utilization is realized.
In the present embodiment, the second grounding unit 12 in the DC/DC conversion unit 10 makes the second output port of the DC/DC conversion unit 10 have the same potential as the ground, so that even when the differential voltage output by the bus bar increases, the voltage to ground of each output port is still within the system voltage range, and insulation safety is ensured.
In practical applications, the DC input source 30 may also be an AC/DC conversion unit. In this case, the output terminal of the DC/DC conversion unit 10 is directly or indirectly connected to the output terminal of the energy conversion system.
Specifically, the DC side of the AC/DC conversion unit is connected to the input of the DC/DC conversion unit 10; the AC side of the AC/DC conversion unit is connected with a power grid or a wind power generation unit.
When the alternating current side of the AC/DC conversion unit is connected to the power grid, the application scenario of the energy conversion system may be a charging pile, and at this time, the output end of the DC/DC conversion unit 10 may be directly used as the output end of the energy conversion system, that is, the application scenario is a direct current charging scenario; of course, the output of the DC/DC conversion unit 10 is connected to the output of the energy conversion system, such as an ac charging scenario, via the inverter 40.
When the AC/DC conversion unit is connected to the wind power generation unit, the application scenario of the energy conversion system may be a wind power generation system, and in this case, the output terminal of the DC/DC conversion unit 10 is connected to the output terminal of the energy conversion system through the inverter 40. The application scenario of the energy conversion system is not specifically limited herein, and may be determined according to the actual situation, which is within the protection scope of the present application.
Features described in the embodiments in the present specification may be replaced with or combined with each other, and the same and similar portions among the embodiments may be referred to each other, and each embodiment is described with emphasis on differences from other embodiments. In particular, the system or system embodiments are substantially similar to the method embodiments and therefore are described in a relatively simple manner, and reference may be made to some of the descriptions of the method embodiments for related points. The above-described system and system embodiments are only illustrative, wherein the units described as separate parts may or may not be physically separate, and the parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment. One of ordinary skill in the art can understand and implement it without inventive effort.
Those of skill would further appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both, and that the various illustrative components and steps have been described above generally in terms of their functionality in order to clearly illustrate this interchangeability of hardware and software. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (26)

1. A DC/DC conversion unit is characterized in that the input end of a main circuit is provided with a first input port and a second input port, and the output end of the main circuit is provided with a first output port, a second output port and a third output port; wherein:
the voltage of the first input port is greater than the voltage of the second input port;
the voltage of the first output port is a positive voltage, the voltage regulation target of the second output port is zero, and the voltage of the third output port is a negative voltage;
and at least one output port is directly connected to a corresponding input port so that the input and output terminals of the DC/DC conversion unit are connected in series.
2. The DC/DC conversion unit of claim 1, wherein the second output port is directly connected to the second input port.
3. The DC/DC conversion unit according to claim 2, wherein a voltage difference between the second output port and the third output port is obtained by converting a voltage received by the input terminal of the main circuit.
4. The DC/DC conversion unit according to claim 3, comprising: at least one of a non-isolated boost circuit, a buck-boost circuit, a buck circuit, and a dc conversion unit with an isolation transformer.
5. The DC/DC conversion unit according to any one of claims 1 to 4, wherein a voltage at the first output port is equal to or higher than a voltage at the first input port.
6. The DC/DC conversion unit of claim 5, wherein the voltage of the first output port and the voltage of the third output port are symmetrical about the second output port.
7. The DC/DC conversion unit according to claim 5, wherein the first output port is directly connected to the first input port such that a voltage of the first output port is equal to a voltage of the first input port;
the first output port is indirectly connected to the first input port, so that the voltage of the first output port is greater than the voltage of the first input port.
8. The DC/DC conversion unit according to claim 7, wherein when the first output port is indirectly connected to the first input port, the main circuit includes: a first conversion circuit and a second conversion circuit;
the input end of the first conversion circuit and the input end of the second conversion circuit are connected to the input end of the main circuit in parallel;
the voltage difference between the second output port and the third output port is obtained by converting the voltage received by the input end of the first conversion circuit;
and the voltage difference between the first output port and the second output port is obtained after the second conversion circuit converts the voltage received by the input end of the second conversion circuit.
9. The DC/DC conversion unit according to claim 8, wherein the first conversion circuit and the second conversion circuit respectively include: at least one of a non-isolated boost circuit, a buck-boost circuit, a buck circuit, and a dc conversion unit with an isolation transformer.
10. The DC/DC conversion unit according to claim 4, wherein the main circuit comprises: the buck-boost circuit;
the positive electrode of the input end of the buck-boost circuit is connected with the first input port;
the negative electrode of the input end of the buck-boost circuit is connected with the second input port;
the positive electrode of the output end of the buck-boost circuit is connected with the second output port;
and the negative electrode of the output end of the buck-boost circuit is connected with the third output port.
11. The DC/DC conversion unit according to claim 9, wherein the first conversion circuit comprises: the buck-boost circuit, the second transform circuit comprising: the boost circuit;
the positive electrode of the input end of the buck-boost circuit and the positive electrode of the input end of the boost circuit are both connected with the first input port;
the negative electrode of the input end of the buck-boost circuit and the negative electrode of the input end of the boost circuit are both connected with the second input port;
the positive electrode of the output end of the buck-boost circuit and the negative electrode of the output end of the boost circuit are connected with the second output port;
the negative electrode of the output end of the buck-boost circuit is connected with the third output port;
and the positive electrode of the output end of the boost circuit is connected with the first output port.
12. An energy conversion system, comprising: at least one direct current input source, and at least one DC/DC conversion unit according to any of claims 1-11;
the input end of the DC/DC conversion unit is directly or indirectly connected with the corresponding direct current input source;
and the output end of the DC/DC conversion unit is directly or indirectly connected with the output end of the energy conversion system.
13. The energy conversion system of claim 12, further comprising at least one inverter;
the output end of the DC/DC conversion unit is connected with the direct current side of the inverter through a corresponding cable;
and the alternating current side of the inverter is connected with the output end of the energy conversion system.
14. The energy conversion system according to claim 13, wherein when the number of inverters is 1:
a first output port of the DC/DC conversion unit is connected with a direct current side positive electrode of the inverter through a positive line;
and a third output port of the DC/DC conversion unit is connected with a direct current side negative electrode of the inverter through a negative line.
15. The energy conversion system of claim 14, wherein the dc side of the inverter comprises three ports or two ports;
when the direct current side of the inverter comprises two ports, the midpoint of the direct current side arranged in the inverter is grounded through a first grounding unit arranged in the inverter;
when the direct current side of the inverter comprises three ports, a midpoint of the direct current side arranged outside the inverter is grounded through a first grounding unit arranged outside the inverter, or a second output port of the DC/DC conversion unit is connected with the midpoint of the direct current side of the inverter through a zero line.
16. The energy conversion system according to claim 13, wherein when the number of inverters is 2, the first inverter and the second inverter are respectively:
a first output port of the DC/DC conversion unit is connected with a direct current side positive electrode of the first inverter through a positive line;
the direct-current side negative electrode of the first inverter is connected with the direct-current side positive electrode of the second inverter;
and a third output port of the DC/DC conversion unit is connected with a direct current side negative electrode of the second inverter through a negative line.
17. The energy conversion system according to claim 16, wherein a connection point between the DC-side negative electrode of the first inverter and the DC-side positive electrode of the second inverter is grounded via a first grounding unit, or a second output port of the DC/DC conversion unit is connected via a zero line.
18. The energy conversion system according to any one of claims 12-17, further comprising: a second grounding unit;
the second grounding unit is used for realizing the coupling connection or decoupling disconnection between the second output port of the DC/DC conversion unit and the equipotential of the ground.
19. The energy conversion system of claim 18, wherein the second grounding unit comprises: the switch power supply, the impedance unit, the third diode and the third capacitor;
the positive electrode of the input end of the switching power supply is connected with the first input port of the DC/DC conversion unit;
the negative electrode of the input end of the switching power supply is connected with the second input port;
the positive electrode of the output end of the switching power supply is connected with one end of the third capacitor, and a connection point is connected with the second output port of the DC/DC conversion unit through the impedance unit and the third diode in sequence;
and the negative electrode of the output end of the switching power supply is connected with the other end of the third capacitor, and the connection point is connected with the earth equipotential.
20. The energy conversion system of claim 19, wherein the switching power supply comprises: the energy storage element and the switching tube are connected in series.
21. The energy conversion system of claim 18, wherein the second grounding unit comprises: a controllable switch;
the second output port is connected with the earth equipotential through the controllable switch.
22. The energy conversion system according to any one of claims 12-17, further comprising: at least one combiner box;
each combiner box is respectively arranged between the input end of the DC/DC conversion unit and the corresponding direct current input source.
23. The energy conversion system of claim 22, further comprising at least one DC/DC conversion module in the combiner box to implement a first voltage conversion before the DC/DC conversion unit.
24. The energy conversion system according to any one of claims 12-17, wherein the direct current input source is at least one of a photovoltaic power generation unit, an AC/DC conversion unit, and an energy storage unit.
25. The energy conversion system according to claim 24, wherein the DC input sources to which the input terminals of the respective DC/DC conversion units are connected are the same, or there is a difference in the DC input sources to which the input terminals of at least two of the DC/DC conversion units are connected.
26. The energy conversion system of claim 24, wherein the DC side of the AC/DC conversion unit is connected to an input of the DC/DC conversion unit;
and the alternating current side of the AC/DC conversion unit is connected with a power grid or a wind power generation unit.
CN202110719532.0A 2021-06-28 2021-06-28 DC/DC conversion unit and energy conversion system Pending CN113271009A (en)

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WO2023273190A1 (en) * 2021-06-28 2023-01-05 阳光电源股份有限公司 Dc/dc conversion unit and energy conversion system

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