CN113794388A - Power conversion circuit and converter - Google Patents

Power conversion circuit and converter Download PDF

Info

Publication number
CN113794388A
CN113794388A CN202110937758.8A CN202110937758A CN113794388A CN 113794388 A CN113794388 A CN 113794388A CN 202110937758 A CN202110937758 A CN 202110937758A CN 113794388 A CN113794388 A CN 113794388A
Authority
CN
China
Prior art keywords
power conversion
external terminal
series
conversion module
energy storage
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
CN202110937758.8A
Other languages
Chinese (zh)
Other versions
CN113794388B (en
Inventor
何竞松
彭光强
武霁阳
王越杨
毛炽祖
陈礼昕
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Maintenance and Test Center of Extra High Voltage Power Transmission Co
Original Assignee
Maintenance and Test Center of Extra High Voltage Power Transmission Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Maintenance and Test Center of Extra High Voltage Power Transmission Co filed Critical Maintenance and Test Center of Extra High Voltage Power Transmission Co
Priority to CN202110937758.8A priority Critical patent/CN113794388B/en
Publication of CN113794388A publication Critical patent/CN113794388A/en
Application granted granted Critical
Publication of CN113794388B publication Critical patent/CN113794388B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/02—Conversion of ac power input into dc power output without possibility of reversal
    • H02M7/04—Conversion of ac power input into dc power output without possibility of reversal by static converters
    • H02M7/12—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/21—Conversion of ac power input into dc 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
    • H02M7/217—Conversion of ac power input into dc 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
    • 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
    • H02J3/36—Arrangements for transfer of electric power between ac networks via a high-tension dc link
    • 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
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/02—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries for charging batteries from ac mains by converters
    • H02J7/04—Regulation of charging current or voltage
    • H02J7/06—Regulation of charging current or voltage using discharge tubes or 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
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/34—Parallel operation in networks using both storage and other dc sources, e.g. providing buffering
    • H02J7/345—Parallel operation in networks using both storage and other dc sources, e.g. providing buffering using capacitors as storage or buffering devices
    • 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
    • H02M1/32—Means for protecting converters other than automatic disconnection
    • 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
    • H02M7/66—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal
    • H02M7/68—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal by static converters
    • H02M7/72—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/79—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with 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
    • H02M7/797—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with 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
    • 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
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/60—Arrangements for transfer of electric power between AC networks or generators via a high voltage DC link [HVCD]

Landscapes

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

Abstract

The utility model relates to a power conversion circuit and transverter, the power conversion module in the transverter that contains power conversion circuit includes first energy memory element, second energy memory element, charging circuit, when the external input alternating current power supply of power conversion module, during alternating current power supply's positive half cycle, alternating current power supply passes through charging circuit charges to second energy memory element, during alternating current power supply's negative half cycle, alternating current power supply and second energy memory element pass through jointly charging circuit charges to first energy memory element to the realization is the input alternating voltage at the bottom of the meeting an emergency and passes through each energy memory element and transform into higher direct current voltage output, therefore can reduce the insulating performance's of each equipment in the transmission system of transverter place influence.

Description

Power conversion circuit and converter
Technical Field
The present invention relates to the field of power electronics technologies, and in particular, to a power conversion circuit and a converter.
Background
Power conversion circuits are used to convert one type of current or voltage to another type of current or voltage output, such as ac-to-dc power converters, dc-to-ac power converters, and dc-to-dc or ac-to-ac power converters. In a dc power transmission system, conversion between ac and dc voltages needs to be performed by an inverter. Therefore, the power conversion circuit is focused on as a core circuit of the inverter.
The current converter in the direct current transmission project generally adopts a controllable thyristor commutation technology (conventional direct current) or a controllable submodule switching multi-level commutation technology (flexible direct current) to construct a power conversion circuit of the converter. The controllable thyristor commutation technology controls the conduction of thyristors of 6 bridge arms according to time sequence, and directly connects a three-phase alternating current bus to a direct current bus according to the time sequence to realize the commutation of alternating current and direct current voltage and current. The controllable submodule switching-on/off multilevel commutation technology controls the voltage submodules of 6 bridge arms to switch on/off according to requirements, forms required sine waves on a three-phase alternating current bus, and forms required direct current voltage on a direct current bus to realize the conversion of alternating current and direct current voltage and current.
However, when the power conversion circuits implemented by the two technologies are applied to a high-voltage direct-current power transmission system, a high alternating-current voltage is generally required to be connected to an input end of the power conversion circuit, so that the requirement on the insulation performance of power transmission equipment is high, and the power conversion circuits implemented by the two technologies cannot be basically expanded as required after being built, so that the application of the power conversion circuits is lack of flexibility.
Disclosure of Invention
Accordingly, there is a need for a power conversion circuit capable of converting ac voltage to ac voltage and further expanding capacity as required, and a converter including the power conversion circuit. The application aims to be achieved through the following technical scheme.
In one aspect, the present application provides a power conversion circuit, including:
a power conversion module;
the power conversion module comprises a first energy storage element, a charging circuit and a second energy storage element, wherein the charging circuit is respectively connected with the first energy storage element and the second energy storage element;
when the power conversion module inputs an alternating current power supply, the alternating current power supply charges the second energy storage element through the charging circuit during the positive half cycle of the alternating current power supply, the voltage of the alternating current power supply and the voltage on the second energy storage element form a series voltage during the negative half cycle of the alternating current power supply, and the series voltage charges the first energy storage element through the charging circuit.
In some embodiments, the power conversion module further includes a first external terminal, a second external terminal, a third external terminal, and a fourth external terminal;
the first external terminal and the negative end of the first energy storage element belong to the same electrical node, and the third external terminal and the positive end of the first energy storage element belong to the same electrical node;
the second external terminal and the negative end of the second energy storage element belong to the same electrical node, and the fourth external terminal and the positive end of the second energy storage element belong to the same electrical node.
In some embodiments, the number of the power conversion modules is two or more, and the power conversion modules are connected in series to form a series unit;
in the series unit, the third external terminal of the previous power conversion module is connected with the first external terminal of the next adjacent power conversion module, and the fourth external terminal of the previous power conversion module is connected with the second external terminal of the next adjacent power conversion module.
In some embodiments, the power conversion module further includes a fifth external terminal and a sixth external terminal;
the fifth external terminal and the negative end of the first energy storage element belong to the same electrical node;
the sixth external terminal and the positive terminal of the first energy storage element belong to the same electrical node.
In some embodiments, two or more of the power conversion modules are connected in parallel to form a parallel unit;
in the parallel unit, the fifth external terminals of the power conversion modules all belong to the same electrical node, and the sixth external terminals of the power conversion modules all belong to the same electrical node.
In some embodiments, the power conversion modules corresponding to each of the series units are connected in parallel to form the parallel unit; each of the series units has the same power conversion module as at least one of the parallel units.
In some embodiments, the power conversion modules corresponding to each of the parallel units are connected in series to form the series unit; each of the parallel units has the same power conversion module as at least one of the series units.
In some embodiments, the charging circuit comprises a first diode, a second diode and a switching tube;
the first diode and the switch tube are sequentially connected in series between the positive ends of the two energy storage elements and the positive end of the first energy storage element;
the second diode and the switch tube are sequentially connected in series between the first external terminal and the positive terminal of the second energy storage element.
In some embodiments, the switch tube is a bidirectional conductive switch tube.
In another aspect, the present application further provides a converter including the power conversion circuit described in any one of the above.
The power conversion circuit and the converter provided by the application can convert low alternating current input voltage into high direct current voltage output through each energy storage element, so that the requirement on the insulativity of equipment of a power transmission system where the power conversion circuit and the converter are located is low, a centralized large-capacity transformer does not need to be configured, and the construction cost is greatly reduced. Furthermore, the direct-current voltage is improved by expanding the power conversion modules in the series units as required, and the capacity of the converter is increased by expanding the power conversion modules in the parallel units as required, so that the project staging construction or the existing project capacity expansion is facilitated, and the project construction flexibility is high.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments or the conventional technologies of the present application, the drawings used in the descriptions of the embodiments or the conventional technologies will be briefly introduced below, it is obvious that the drawings in the following descriptions are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a schematic diagram of a power conversion circuit according to a first embodiment of the present application;
FIG. 2 is a schematic diagram of a power conversion circuit according to a second embodiment of the present application;
FIG. 3 is a schematic diagram of a power conversion circuit according to a third embodiment of the present application;
FIG. 4 is a schematic diagram of a power conversion circuit according to a fourth embodiment of the present application;
fig. 5 is a schematic diagram of a power conversion circuit according to a fifth embodiment of the present application.
Detailed Description
To facilitate an understanding of the present application, the present application will now be described more fully with reference to the accompanying drawings. Embodiments of the present application are set forth in the accompanying drawings. This application may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
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 herein in the description of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.
It will be understood that, as used herein, the terms "first," "second," and the like may be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one element from another. For example, a first resistance may be referred to as a second resistance, and similarly, a second resistance may be referred to as a first resistance, without departing from the scope of the present application. The first resistance and the second resistance are both resistances, but they are not the same resistance.
It is to be understood that "connection" in the following embodiments is to be understood as "electrical connection", "communication connection", and the like if the connected circuits, modules, units, and the like have communication of electrical signals or data with each other.
As used herein, the singular forms "a", "an" and "the" may include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises/comprising," "includes" or "including," etc., specify the presence of stated features, integers, steps, operations, components, parts, or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof.
In order to solve the above problems in the prior art, the present application provides a power conversion circuit, as shown in fig. 1, which is a schematic structural diagram of the power conversion circuit provided in the first embodiment of the present application. The power conversion circuit 100 includes a power conversion module M, and the power conversion module M further includes a first energy storage element 1, a second energy storage element 2, a charging circuit 3, a first external terminal P1, and a second external terminal P2. When the AC power source AC is connected between the first external terminal P1 and the second external terminal P2, during the positive half cycle (positive voltage) of the AC power source AC, the AC power source AC charges the second energy storage element 2 through the charging circuit 3, so that the voltage difference between the two ends of the second energy storage element is equal to the peak value of the AC power source AC, and during the negative half cycle (negative voltage) of the AC power source AC, the voltage of the AC power source AC and the voltage on the second energy storage element 2 form a series voltage, and the series voltage charges the first energy storage element 1 through the charging circuit 3, so that the voltage difference between the two ends of the first energy storage element is equal to twice the peak value of the AC power source AC. Obviously, there are two charging paths in the charging circuit 3, one is a first charging path for charging the first energy storage element 1, and the other is a second charging path for charging the second energy storage element 2, where the first charging path and the second charging path may share components or may be two charging paths arranged in parallel.
Obviously, the power conversion circuit provided in the first embodiment of the present application can implement voltage boosting of an ac voltage into a dc voltage output, and when the power conversion circuit is applied to a dc power transmission system, can implement voltage boosting of a lower ac input voltage into a higher dc voltage output, so that a requirement for insulation performance of equipment in the dc power transmission system can be reduced, that is, a construction cost of the dc power transmission system is reduced.
With continued reference to fig. 1, the power conversion module M further includes a third external terminal P3 and a fourth external terminal P4,
the first external terminal P1 and the negative terminal of the first energy storage element 1 belong to the same electrical node, the third external terminal P3 and the positive terminal of the first energy storage element 1 belong to the same electrical node, the second external terminal P2 and the negative terminal of the second energy storage element 4 belong to the same electrical node, and the fourth external terminal P4 and the positive terminal of the second energy storage element 2 belong to the same electrical node. In the present application, the fact that the connection terminals (including the external connection terminal and the connection node inside the power conversion module) belong to the same electrical node means that the voltages between the connection terminals are the same, that is, the connection terminals are connected to the same node.
Because the first external terminal P1 and the third external terminal P3 are respectively connected to two ends of the second energy storage element 1, the second external terminal P2 and the fourth external terminal P4 are respectively connected to two ends of the second energy storage element 2, and the plurality of power conversion modules M can be connected in series through the first external terminal P1, the second external terminal P2, the third external terminal P3 and the fourth external terminal P4, so that the series expansion of the power conversion circuit can be realized, and the application flexibility of the power conversion circuit is improved.
As shown in fig. 1, in the power conversion circuit 100, the first energy storage element 1 includes a first capacitor C1, the second energy storage element 2 includes a second capacitor C2, and the charging circuit 3 includes a first diode D1, a second diode D2, and a switch Q. Wherein the content of the first and second substances,
the switch Q and the first diode D1 are sequentially connected in series between the positive terminal of the second capacitor C2 (the positive terminal of the capacitor is one terminal of the current input or output, and the negative terminal is the other terminal opposite to the positive terminal) and the positive terminal of the first capacitor C2 to form the first charging path. The second diode D2 and the switching tube Q are sequentially connected in series between the first external terminal P1 and the second capacitor C2 to form the second charging path. Specifically, the second diode D2 and the switch Q are connected to a node J, and one end of the first diode D1 is connected to the node J. The node at which the switch Q is connected to the second capacitor C2 is at the same electrical node as the fourth external terminal P4. In the second embodiment, the switch Q is a bidirectional conducting switch, for example, the switch Q includes two inverse parallel IGBTs, a first IGBT of the two IGBTs is an element through which the first charging path passes, and a second IGBT of the two IGBTs is an element through which the second charging circuit passes. When the input power is charged to the second capacitor C2 through the second diode D2 and the turned-on second IGBT in the switch Q, the second capacitor C2 charges the first capacitor C1 through the turned-on first IGBT in the switch Q and the first diode D1. In addition, the bidirectional conductive switch Q may further include an IGBT and a third diode connected in parallel across the IGBT in other embodiments, which belong to the elements on the first charging path and the second charging path, respectively. The input power supplies charge the second capacitor C2 through the second diode D2 and the third diode, and the second capacitor C2 charges the first capacitor C1 through the turned-on IGBT in the switching tube Q and the first diode D1. In some embodiments, the third diode may be a body diode of an IGBT in the switching tube, that is, the third diode is a part of the IGBT itself as the switching tube, and the first charging path and the second charging path share the IGBT switching tube with the body diode. The specific configuration of the bidirectional conductive switch Q in this application is not limited, and in each drawing of the specification of this application, the switch with no current flow direction is only used to schematically correspond to the schematic switch Q.
In the power conversion circuit 100, the third diode D3 is connected in parallel with the switch tube Q, and the third diode D3 may be a body diode of the switch tube Q, that is, the switch tube Q is actually connected between the second diode D2 and the positive terminal of the second capacitor C2, and no additional diode is connected in parallel at two ends of the switch tube Q. Of course, in other embodiments, the third diode D3 may also be an additional diode connected in parallel across the switching tube Q and in series with the second diode D2. In the second embodiment, the first external terminal P1 is led out from the anode terminal of the second diode D2. In other embodiments, the first charging circuit 3 and the second charging circuit 4 are not limited to the structure shown in the first embodiment.
The conventional direct current in the existing direct current transmission project needs to adopt a transformer to carry out conversion between A, B, C three phases of an alternating current input power supply, and the flexible direct current in the existing direct current transmission project needs to adopt the transformer to realize electrical connection with an alternating current power grid. Therefore, in the hvdc transmission system, the conventional dc converter or the flexible dc converter needs a centralized large-capacity transformer to withstand large voltage and current. The power conversion circuit provided in the present application charges the first energy storage element 1 only through the second charging circuit 4, the second energy storage element 2, and the first charging circuit 3, so as to convert the voltage of the input power into the output voltage through the second energy storage element 1, and therefore, the power conversion circuit provided in the present application does not need to use a centralized large-capacity transformer when the input ac voltage is converted into the output dc voltage, that is, the power conversion circuit provided in the present application may not include a transformer, and thus the manufacturing cost of the power conversion circuit may be reduced.
Referring to fig. 2, which is a schematic circuit diagram of a power conversion circuit 200 according to a second embodiment of the present application, the power conversion circuit 200 includes 2 power conversion modules M in the first embodiment, and two power conversion modules M are connected in series to form a series unit Us. For clarity of description, the two power conversion modules in the series unit Us are named power conversion module M1 and power conversion module M2, respectively. An alternating current power supply AC is connected between the first external terminal P1 and the second external terminal P2 of the power conversion module M1, the third external terminal P3 of the power conversion module M1 is connected with the first external terminal P1 of the power conversion module M2, the fourth external terminal P4 of the power conversion module M1 is connected with the second external terminal P2 of the power conversion module M2, and therefore the series connection of the power conversion modules M1 and M2 is achieved. In the second embodiment, the input power source of the foremost one (the one into which current first flows) of the power conversion modules M1 in the series unit Us is the input power source of the series unit Us, which is the alternating-current input power source AC. In other embodiments, the input power is not limited to ac input power.
The principle of the conversion process of the power conversion circuit 200 to convert a lower ac input voltage into a higher dc voltage output is described in detail below with reference to fig. 2, so as to explain the power conversion circuit provided in the present application more clearly.
As shown in fig. 2, the AC power supply AC is a single-phase AC power supply, for example, a three-phase AC power supply, in which a phase UA is 10Kvd of AC voltage, and the switching tube Q is turned on by default in the following description of the operation process of the power conversion circuit 200.
In the first positive half cycle (positive voltage) of the a-phase alternating voltage of the alternating current power supply AC, the a-phase alternating voltage is charged to the second capacitor C2 through the power conversion module M1, the second diode D2 and the switching tube Q, and according to the charging loop of the second capacitor C2 in the power conversion module M1, the voltage difference between the two ends of the second capacitor C2 is equal to the peak value of the a-phase alternating voltage, that is, the voltage difference U12 on the second capacitor C in the power conversion module M1 is equal to 10 kV.
In the second half cycle (negative voltage) of the a-phase alternating voltage of the alternating current power supply AC, the a-phase alternating voltage is charged to the first capacitor C1 through the second capacitor C2, the switching tube Q and the first diode D1 of the power conversion circuit M1, and the charge of the second capacitor C2 cannot flow back to the alternating current power supply AC according to the charging loop of the first capacitor C1 in the power conversion module M1 and the one-way conduction characteristic of the second diode D2, so that the voltage difference U11 across the first capacitor C1 in the power conversion module M1 is UA + U12 is 20 kV.
In the third half cycle (positive voltage) of the a-phase alternating current voltage of the alternating current power supply AC, the a-phase alternating current voltage is charged to the second capacitor C2 of the power conversion module M2 through the first capacitor C1 and the second capacitor C2 of the power conversion module M1, the second diode D2 of the power conversion module M2 and the switching tube Q, and the voltage difference U22 between the two ends of the second capacitor C2 of the power conversion module M2 is UA + U11-U12 kV according to the charging loop of the second capacitor C2 in the power conversion module M2 and the unidirectional conduction characteristic of the second diode D2 of the power conversion module M1.
In the fourth half cycle (negative voltage) of the a-phase alternating current voltage of the alternating current power supply AC, the a-phase alternating current voltage passes through the first capacitor C1 and the second capacitor C2 of the power conversion module M1, and the first capacitor C2, the switch Q, the first diode D1 of the power conversion module M2, the first capacitor C1 of the power conversion module M2, the charging circuit is charged according to the first capacitor C1 of the power conversion module M2, and the unidirectional conduction characteristic of the second diode D2 of the power conversion module M1, and the unidirectional conduction of the second diode D2 of the power conversion module M2 prevents the charges of the second capacitor C2 of the power conversion module M2 from flowing back to the alternating current power supply, so that the voltage difference U21 across the first capacitor C1 of the power conversion module M2 is UA + U12+ U22-U11, which is 20 kV.
As can be seen from the above, after two complete cycles of the a-phase alternating voltage of the alternating-current power source AC, since the first capacitors in the power conversion modules are sequentially connected in series in the series unit Us, the voltage at the output end of the series unit Us in the second embodiment is the sum of the voltage difference 20kV of the first capacitor C1 in the power conversion module M1 and the voltage difference 20kV of the first capacitor C1 in the power conversion module M2, i.e., the direct current 40 kV. In addition, because each capacitor in the power conversion module cannot release charges to the alternating current power supply due to the unidirectional conduction characteristic of the diode (namely, the capacitors are all charged unidirectionally), the voltage of each capacitor cannot be reduced. Therefore, when one power conversion module M is added to the series unit Us for series connection, the dc voltage finally output by the series unit Us can be increased by 2 UA. Therefore, the function of converting a lower alternating voltage into a higher direct voltage and outputting the higher direct voltage can be realized by connecting a plurality of power conversion modules M in series, and the requirement of the insulation performance of system equipment can be reduced when the power conversion circuit is applied to a high-voltage direct-current transmission system. For example, fig. 3 shows a power conversion circuit 300 according to a third embodiment of the present application. In the power conversion circuit 300, the N power conversion modules M are named as power conversion modules M1, M2, and … MN, respectively, for the sake of convenience in distinguishing different power conversion modules M. A series unit Us composed of N power conversion modules M1, M2, and … MN connected in series in this order, and the first capacitors of the power conversion modules in the power conversion circuit 300 are connected in series. It should be noted that the power conversion modules M1, M2, … MN are all the power conversion modules M in the first embodiment, and at least the fifth external node P5 and the sixth external node P6 are selectively provided in each power conversion module of the power conversion circuit 300. The first external terminal P1 and the second external terminal P2 of the first power conversion module M1 in the series unit Us serve as power input terminals of the series unit Us, the third external terminal P3 of the previous power conversion module in each power conversion module in the series unit Us is connected to the first external terminal P1 of the adjacent next power conversion module, and the fourth external terminal P4 of the previous power conversion module is connected to the second external terminal P2 of the adjacent next power conversion module. According to the above operation and principle, in the series unit Us in the power conversion circuit 300, the first capacitors of the power conversion modules are connected in series, that is, the final output voltage is the superimposed voltage of the voltage difference on the first capacitors, so that the final output dc voltage of the power conversion circuit can be increased by 2 NUA. In practical application, the value of N can be flexibly configured according to requirements, so that each series unit in the power conversion circuit can be expanded as required, and the capacity expansion function of the power conversion circuit is realized. When the power conversion circuit provided by the application is applied to a current converter, the parallel-connected series units can be added according to needs to improve the capacity of the current conversion, so that the staged construction of a power transmission project or the capacity expansion of the existing project is facilitated, and the flexibility of the project construction is high.
In order to facilitate the sampling of the output voltage of the power conversion modules, in the third embodiment, the negative terminal of the first capacitor of each power conversion module is grounded, and the voltage difference across each first capacitor is the voltage across the positive terminal of each first capacitor.
Further, in the first embodiment, in order to realize a parallel circuit between the respective power conversion modules M, the power conversion modules M also have the fifth external terminal P5 and the sixth external terminal P6. The fifth external terminal P5 and the negative terminal of the first energy storage element 1 belong to the same electrical node, and the sixth external terminal P6 and the positive terminal of the first energy storage element 1 belong to the same electrical node. In the power conversion circuit according to other embodiments of the present application, it includes a parallel unit Up formed by connecting M power conversion circuits in parallel, in the parallel unit Up, the fifth external terminal P5 of each power conversion module M belongs to the same electrical node, and the sixth external terminal P6 of each power conversion module M belongs to the same electrical node. Here, the third connection external terminal P3, the fourth external terminal P4, the fifth external terminal P5, and the sixth external terminal P6 are not terminals that the power conversion module M must have, and may be set in consideration of practical use of the power conversion module M, and for example, when parallel connection of a plurality of modules is required for the power conversion module M, the third external terminal P3 and the fourth external terminal P4 must be provided for the power conversion module M, and for example, when series connection of a plurality of modules is required for the power conversion module M, the fifth external terminal P5 and the sixth external terminal P6 must be provided for the power conversion module M.
In other embodiments, the power conversion circuit provided by the present application includes N parallel units Up1, Up2, … UpN, corresponding power conversion modules between the parallel units are connected in series to form a series unit, and each parallel unit has at least the same power conversion module as one series unit. The first capacitances of the N parallel cells Up1, Up2, … UpN are connected in parallel to each other.
For example, as shown in fig. 4, which is a schematic structural diagram of a power conversion circuit 400 according to a fourth embodiment of the present application, the power conversion circuit 400 includes two parallel units Up1 and Up 2. The parallel unit Up1 includes power conversion modules M11 and M21 connected in parallel, the parallel unit Up2 includes power conversion modules M12 and M22 connected in parallel, and then the parallel unit Up2 and the parallel unit Up2 are connected in series: in the fifth embodiment, the power conversion module M11 in the parallel unit Up1 and the corresponding power conversion module M12 in the parallel unit Up2 are connected in series to form a series unit Us1, and the power conversion module M21 in the parallel unit Up1 and the corresponding power conversion module M22 in the parallel unit Up2 are connected in series to form a series unit Us2, so that the parallel unit Up1 and the series unit Us1 have the same power conversion module M11, and the parallel unit Up1 and the series unit Us2 have the same power conversion module M21. In the plurality of series-connected parallel units, an input power supply is connected between the first external terminal P1 and the second external terminal P2 of each power conversion module of the foremost (into which current first flows) parallel unit, and each input power supply may be, for example, each unidirectional voltage source in the multiphase ac power supply. Note that, in the plurality of series-connected parallel units, not all the power conversion modules in each parallel unit have corresponding power conversion modules connected in series, and for example, in fig. 4, the power conversion module M12 may be eliminated, and the parallel unit Up1 has only the power conversion module M11 in common with the series unit Us 1.
In addition, as shown in fig. 5, a power conversion circuit 500 according to a fifth embodiment of the present application is provided. The power conversion circuit 500 comprises M parallel series units Us1, Us2, … UsM, corresponding power conversion modules in each series unit are connected in parallel to form a parallel unit, and each series unit and at least one parallel unit have the same power conversion module. In the power conversion circuit 500, an input power source, which may be one phase of an ac input power source, is connected between the first external terminal P1 and the second external terminal P2 of the foremost (current flows first) power conversion module in each series unit to serve as the input power source of the series unit.
The power conversion circuit 500 shown in fig. 5 is further understood by taking the power conversion circuit 400 in fig. 4 as an example of a specific implementation of the power conversion circuit 500 in fig. 5. The power conversion circuit 400 includes two series units Us1, Us 2. The series unit Us1 comprises series connected power conversion modules M11, M12, the series unit Us2 comprises series connected power conversion modules M21, M22, then the parallel connection of the series unit Us1 and the series unit Us2 is performed in the following way: in the power conversion circuit 400, the power conversion module M11 in the series unit Us1 and the corresponding power conversion module M21 in the series unit Us2 are connected in parallel to form a parallel unit Up1, the power conversion module M12 in the series unit Us1 and the corresponding power conversion module M22 in the series unit Us2 are connected in parallel to form a parallel unit Up2, and then the series unit Us1 and the parallel unit Up1 have the same power conversion module M11, and the series unit Us1 and the parallel unit Up2 have the same power conversion module M21. In the plurality of parallel-connected series-parallel units, the first external connection terminals P1 of the corresponding power conversion modules are connected, and the fifth connection terminals of the corresponding power conversion modules are connected. The input power supply of each series unit in each parallel series unit is a single-direction voltage source in the multi-phase alternating current power supply. Note that, in a plurality of parallel-connected series units, not all the power conversion modules in each series unit have corresponding power conversion modules connected in parallel thereto, and for example, in fig. 4, the power conversion module M22 may be eliminated, and the series unit Us1 has only the power conversion module M11 in common with the parallel unit Up 1. Here, the illustration of grounding the negative terminal of each first capacitor C1 is omitted in both fig. 2 and fig. 4.
Obviously, in the power conversion circuit provided by the application, after any one power conversion module fails and is taken out of service, other power conversion modules can normally operate without stopping working. The power conversion circuit provided according to the present application can operate with a fault. In addition, the power conversion circuit provided by the application has low cost, and the power conversion modules can be connected in series and in parallel as required, so that a plurality of power conversion modules can be arranged in the power conversion circuit, and the power conversion modules can be switched into the power conversion circuit to be used by switching on the switching tubes Q or can be switched off to realize the bypass of the corresponding power conversion module, namely, the corresponding power conversion module is taken out of the power conversion circuit to be used. Obviously, the power conversion circuit according to the present application may configure a plurality of standby power conversion modules by connecting a plurality of power conversion modules in series and/or in parallel, thereby improving redundancy of the power conversion circuit, i.e., improving fault tolerance of the power conversion circuit.
In addition, when each series unit in the plurality of parallel series units of the power conversion circuit provided by the invention converts an input power supply into an output voltage and a current, the series units are mutually isolated and do not influence each other. Therefore, when the power conversion circuit provided by the application is applied to the inverter for converting multi-phase alternating voltage into direct voltage and outputting the direct voltage, the inverter can run in a phase-lacking mode. For example, if the power conversion circuit includes three series units connected in parallel, the input voltages of the three series units are A, B, C three-phase voltages of the three-phase ac power supply, but when the series unit corresponding to the a-phase voltage is not used, the series unit corresponding to the B, C two-phase voltage can still operate normally to convert the B, C two-phase voltage into the dc voltage, and output the dc voltage.
In addition, according to the power conversion circuit provided by the application, the switching-on and the switching-off of the switching tube Q in each power conversion module can be controlled to control the switching-on and the switching-off of the corresponding power conversion module, so that the output voltage of the power conversion circuit can be adjusted and controlled. The control process and principle of this control will be explained in detail below with reference to the power conversion circuit 200 provided in fig. 2 as an example.
When the switching tube Q of the power conversion unit M1 is controlled to be turned off in the direction of the charging loop of the first capacitor, in the first half cycle (positive voltage) of the a-phase alternating-current voltage of the alternating-current power supply AC, the a-phase alternating-current voltage is charged to the second capacitor C2 of the power conversion module M2 through the first diode D1, the second diode D2, the switching tube Q of the power conversion module M1, the second diode D2 and the switching tube Q of the power conversion module M2, and the first capacitor C1 of the power conversion module M1 is short-circuited by the first diode D1 and the second diode D2 of the power conversion module M1 and cannot be charged, during which the second capacitor C2 of the power conversion module M1 and the second capacitor C2 of the power conversion module M2 commonly bear the peak value of the a-phase alternating-current voltage, that is U12 ═ U22 ═ 0.5 × UA ═ 5 kV.
When the switching tube Q of the power conversion unit M1 is controlled to be disconnected in the direction of the charging loop of the first capacitor, in the second half cycle (negative voltage) of the a-phase alternating-current voltage of the alternating-current power supply AC, the a-phase alternating-current voltage is charged through the second capacitor C2 of the power conversion module M1 and the second capacitor C2, the switching tube Q and the first diode D1 of the power conversion module M2 to the first capacitor C1 of the power conversion module M1 and the first capacitor C1 of the power conversion module M2, during which the second diode D2 of the power conversion module M2 is unidirectionally turned on so that the charges of the second capacitor C2 in the power conversion module M2 cannot flow back to the alternating-current power supply, the first capacitor C1 of the power conversion module M1 and the first capacitor C1 of the power conversion module M2 commonly bear the loop voltage, that is U11 ═ U5 (UA + U12+ U22) and U4610 kV.
As can be seen from the above, after an AC full cycle, the voltage at the output terminal of the series unit Us is 20kV dc, which is reduced by half compared to the 40kV dc voltage output by the power conversion circuit 200 when the switching tube Q of the power conversion unit M1 is turned on. Obviously, after the switching tube Q of the power conversion module is controlled to be turned off, the corresponding first capacitor is not charged during the period when the AC is negative voltage, so that the output voltage of the power conversion circuit 200 can be reduced.
Therefore, the power conversion circuit provided by the application can realize the input or bypass of the corresponding power conversion module by controlling the on or off of the switching tube Q in each power conversion module, thereby increasing or decreasing the output voltage of the corresponding series unit and realizing the regulation and control of the output voltage of the power conversion circuit. Compared with a corresponding conventional direct current or flexible direct current power conversion circuit, when the power conversion circuit is applied to a converter, a control system of the power conversion circuit is relatively simple, and high requirements on triggering precision and speed of the converter are not needed.
In addition, according to the circuit structure and the operating principle of the power conversion circuit provided by the application, it can be known that the power conversion circuit provided by the application has low waveform sensitivity to the input alternating-current voltage compared with a corresponding conventional direct-current or flexible direct-current power conversion circuit, so that the problem of unsuccessful phase conversion caused by waveform deformity of the input alternating-current voltage can be avoided.
The present application further provides a converter including the power conversion circuit provided according to any one of the embodiments of the present application. For example, when the inverter includes a power conversion circuit as shown in fig. 5, a multiphase ac input voltage of the inverter is converted into a dc voltage by the power conversion circuit and is output, and each phase of the multiphase input voltage is used as an input voltage of each of the plurality of series-connected cells. For example, if the multiphase input voltage is a three-phase ac input voltage, the power conversion circuit includes three series units Us1, Us2, and Us3 connected in parallel. An input voltage AC1 of the series unit Us1 is an a-phase voltage of the three-phase alternating voltages, an input voltage AC2 of the series unit Us2 is a B-phase voltage of the three-phase alternating voltages, and an input voltage AC3 of the series unit Us3 is a C-phase voltage of the three-phase alternating voltages.
As can be seen from the above analysis and description, the converter provided in the present application has the following advantages compared to the converter in the existing power transmission system:
1) high alternating current input voltage is not needed, the requirement on the insulativity of equipment of a power transmission system is low, a centralized high-capacity transformer is not needed, and the construction cost is greatly reduced;
2) the direct-current voltage is improved by expanding the power conversion modules in the series units as required, and the capacity of the converter is increased by expanding the power conversion modules in the parallel units as required, so that the project staging construction or the existing project capacity expansion is facilitated, and the project construction flexibility is high;
3) the control process is simple and reliable, the process of converting AC into DC can be naturally realized without intervention, and the on-off of the switching tubes in each power conversion module is simply controlled only according to the requirement (without continuously sending control signals), the control on the output voltage can be realized, and the requirements on the control precision and speed of a control system are low;
4) the inverter is insensitive to alternating voltage waveform distortion, each series unit independently operates to convert, phase-lacking operation can be achieved, the fault of a single power conversion module can be integrally disconnected from the electrical connection with the inverter main body without influencing the operating inverter, high fault tolerance is achieved, and operation with the fault can be achieved.
In the description herein, references to the description of "some embodiments," "other embodiments," "desired embodiments," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, a schematic description of the above terminology may not necessarily refer to the same embodiment or example.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims (10)

1. A power conversion circuit comprising:
a power conversion module;
the power conversion module comprises a first energy storage element, a charging circuit and a second energy storage element, wherein the charging circuit is respectively connected with the first energy storage element and the second energy storage element;
when the power conversion module inputs an alternating current power supply, the alternating current power supply charges the second energy storage element through the charging circuit during the positive half cycle of the alternating current power supply, the voltage of the alternating current power supply and the voltage on the second energy storage element form a series voltage during the negative half cycle of the alternating current power supply, and the series voltage charges the first energy storage element through the charging circuit.
2. The power conversion circuit according to claim 1, wherein the power conversion module further includes a first external terminal, a second external terminal, a third external terminal, and a fourth external terminal;
the first external terminal and the negative end of the first energy storage element belong to the same electrical node, and the third external terminal and the positive end of the first energy storage element belong to the same electrical node;
the second external terminal and the negative end of the second energy storage element belong to the same electrical node, and the fourth external terminal and the positive end of the second energy storage element belong to the same electrical node.
3. The power conversion circuit according to claim 2, wherein the number of the power conversion modules is two or more, and the power conversion modules are connected in series to form a series unit;
in the series unit, the third external terminal of the previous power conversion module is connected with the first external terminal of the next adjacent power conversion module, and the fourth external terminal of the previous power conversion module is connected with the second external terminal of the next adjacent power conversion module.
4. The power conversion circuit according to any one of claims 1 to 3, wherein the power conversion module further includes a fifth external terminal and a sixth external terminal;
the fifth external terminal and the negative end of the first energy storage element belong to the same electrical node;
the sixth external terminal and the positive terminal of the first energy storage element belong to the same electrical node.
5. The power conversion circuit according to claim 4, wherein two or more of the power conversion modules are connected in parallel to form a parallel unit;
in the parallel unit, the fifth external terminals of the power conversion modules all belong to the same electrical node, and the sixth external terminals of the power conversion modules all belong to the same electrical node.
6. The power conversion circuit according to claim 5, wherein the power conversion modules corresponding to the respective series units are connected in parallel to form the parallel unit; each of the series units has the same power conversion module as at least one of the parallel units.
7. The power conversion circuit according to claim 5, wherein the power conversion modules corresponding to the respective parallel units are connected in series to form the series unit;
each of the parallel units has the same power conversion module as at least one of the series units.
8. The power conversion circuit of claim 1, wherein the charging circuit comprises a first diode, a second diode, and a switching tube;
the first diode and the switch tube are sequentially connected in series between the positive ends of the two energy storage elements and the positive end of the first energy storage element;
the second diode and the switch tube are sequentially connected in series between the first external terminal and the positive terminal of the second energy storage element.
9. The power conversion circuit of claim 8, wherein the switching tube is a bidirectional conducting switching tube.
10. A converter comprising a power conversion circuit as claimed in any one of claims 1 to 9.
CN202110937758.8A 2021-08-16 2021-08-16 Power conversion circuit and converter Active CN113794388B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202110937758.8A CN113794388B (en) 2021-08-16 2021-08-16 Power conversion circuit and converter

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202110937758.8A CN113794388B (en) 2021-08-16 2021-08-16 Power conversion circuit and converter

Publications (2)

Publication Number Publication Date
CN113794388A true CN113794388A (en) 2021-12-14
CN113794388B CN113794388B (en) 2024-04-02

Family

ID=78876001

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202110937758.8A Active CN113794388B (en) 2021-08-16 2021-08-16 Power conversion circuit and converter

Country Status (1)

Country Link
CN (1) CN113794388B (en)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN201063536Y (en) * 2007-07-09 2008-05-21 肖卫华 Power converter with active power factor emendation
CN109742780A (en) * 2019-01-25 2019-05-10 北京交通大学 The formula energy-storage system that distributes alternately based on Modular multilevel converter
CN110460241A (en) * 2019-09-03 2019-11-15 湖南大学 A kind of modularization tandem type DC converter of High voltage output
CN110677060A (en) * 2018-07-02 2020-01-10 台达电子工业股份有限公司 Power conversion system and pre-charging method of direct current bus capacitor therein
CN112886620A (en) * 2021-02-02 2021-06-01 南京大全电子科技有限公司 Power energy module and power converter based on energy storage element

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN201063536Y (en) * 2007-07-09 2008-05-21 肖卫华 Power converter with active power factor emendation
CN110677060A (en) * 2018-07-02 2020-01-10 台达电子工业股份有限公司 Power conversion system and pre-charging method of direct current bus capacitor therein
CN109742780A (en) * 2019-01-25 2019-05-10 北京交通大学 The formula energy-storage system that distributes alternately based on Modular multilevel converter
CN110460241A (en) * 2019-09-03 2019-11-15 湖南大学 A kind of modularization tandem type DC converter of High voltage output
CN112886620A (en) * 2021-02-02 2021-06-01 南京大全电子科技有限公司 Power energy module and power converter based on energy storage element

Also Published As

Publication number Publication date
CN113794388B (en) 2024-04-02

Similar Documents

Publication Publication Date Title
EP2770624B1 (en) Method and apparatus for producing three-phase current
US6058032A (en) Multiplex pulse-width modulation power converter
CN101657946B (en) 3-phase high power ups
EP3557751A1 (en) Modular power supply system
US20130003424A1 (en) Multi-phase interleaved bidirectional dc-dc converter with high voltage conversion ratio
KR100970566B1 (en) H-bridge type multi-level converter with power regeneration capability
JPH1075580A (en) Photovolatic power converter
WO2017144693A1 (en) Dual submodule for a modular multilevel converter and modular multilevel converter including the same
CN113746361A (en) AC-DC power conversion system with high voltage gain
US11233463B2 (en) Modular multilevel converter
CN113474986B (en) Converter unit for MMC, MMC and control method thereof
CN107482892B (en) Energy buffer circuit and converter
CN113794388B (en) Power conversion circuit and converter
CN114223127B (en) Power supply system
WO2018157010A1 (en) Capacitive-based power transformation
CN110729896B (en) Bidirectional direct current converter based on MMC and control system thereof
CN109728720B (en) Bipolar DC/DC converter for flexible direct current transmission and control method thereof
EP3806303A1 (en) Alternating capacitor step-down dc/dc converter
EP3790181A1 (en) Modular multilevel converter
Ismail et al. A review of recent HVDC tapping topologies
Sandeep et al. Switched-capacitor-based three-phase five-level inverter topology with reduced components
CN113922682B (en) Direct cascade type modular multilevel converter of three-phase bridge circuit
CA2200573A1 (en) Pwm converters for three phase ac power control and ac to dc conversion, and special purpose devices using the same
CN111244961B (en) High-efficiency power supply system and method
CN113364333B (en) Combined current converter, direct current transformer and control method

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant