CN110995041A - Submodule circuit for modular multilevel converter - Google Patents
Submodule circuit for modular multilevel converter Download PDFInfo
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- CN110995041A CN110995041A CN201911298436.2A CN201911298436A CN110995041A CN 110995041 A CN110995041 A CN 110995041A CN 201911298436 A CN201911298436 A CN 201911298436A CN 110995041 A CN110995041 A CN 110995041A
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- Prior art keywords
- modular multilevel
- multilevel converter
- switch tube
- diode
- sub
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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
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
- H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
- H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/483—Converters with outputs that each can have more than two voltages levels
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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
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
- H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
- H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/483—Converters with outputs that each can have more than two voltages levels
- H02M7/4835—Converters with outputs that each can have more than two voltages levels comprising two or more cells, each including a switchable capacitor, the capacitors having a nominal charge voltage which corresponds to a given fraction of the input voltage, and the capacitors being selectively connected in series to determine the instantaneous output voltage
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
- H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
- H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Inverter Devices (AREA)
Abstract
The invention discloses a submodule circuit for a modular multilevel converter, which consists of 2 energy storage capacitors, 2 power diodes and 4 power switch tubes with reverse diodes; when the submodule circuit is used for replacing four half-bridge type submodules close to an alternating voltage output side in the modular multilevel converter, one end, connected with a collector electrode of a first switch tube, of a first capacitor of the submodule circuit is connected with a bridge arm inductor or other submodules of an upper bridge arm, an emitter electrode of a second switch tube is connected with a load, and one end, connected with an emitter electrode of a fourth switch tube, of the second capacitor is connected with the bridge arm inductor or other submodules of a lower bridge arm. Under the condition of keeping the original functions unchanged, the invention reduces the number of capacitors by 2, reduces the number of switching tubes by 4 and reduces the number of diodes by 2, thereby reducing the volume and the cost of the modular multilevel converter.
Description
Technical Field
The invention relates to the technical field of modular multilevel converters, in particular to a submodule circuit for a modular multilevel converter.
Background
In order to meet the requirements of large-capacity power transmission and enhancement of grid controllability, the flexible direct-current transmission technology has a rapidly developing potential. As a core technology of flexible direct current transmission engineering, a Modular Multilevel Converter (MMC) is widely used. The existing MMC converters, especially in the high voltage field, are mostly hybrid MMC converters containing various sub-modules. In the whole MMC converter, the half-bridge sub-modules form a large part. Although the modular multilevel converter has the advantages of modularization, low switching frequency, low switching loss, low voltage stress of a switching device and the like compared with the traditional rectifying and inverter, the modular multilevel converter also has a series of problems in the application process, wherein the most prominent problem is the capacitance problem. In principle, the modular multilevel converter needs to be provided with a large number of capacitors, the voltage stress of the capacitors is high, and the capacitance value is high in order to control the voltage ripple of the capacitors, and the capacitors account for 1/2 and cost 1/3 of the volume of the whole modular multilevel device. The prior art cannot effectively reduce the number of capacitors in the modular multilevel converter, and the capacitors become bottlenecks which restrict the technical development of the modular multilevel converter. Therefore, a new modular multilevel topology is desired to be proposed to significantly reduce the number of capacitors of the modular multilevel converter, thereby achieving the miniaturization and the manufacturing cost reduction of the modular multilevel converter.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a submodule circuit for a modular multilevel converter, which can be used for replacing four half-bridge type submodules (namely half-bridge type submodule groups) close to the output side of alternating voltage in the modular multilevel converter, and can reduce the number of capacitors by 2, reduce the number of power switching tubes by 4 and reduce the number of diodes by 2 under the condition of keeping the original functions unchanged, thereby reducing the volume and the cost of the modular multilevel converter.
In order to achieve the purpose, the technical scheme provided by the invention is as follows: a sub-module circuit for a modular multilevel converter comprises a first capacitor, a second capacitor, a first diode, a second diode, a first switch tube, a second switch tube, a third switch tube and a fourth switch tube; one end of the first capacitor is connected with a collector electrode of the first switching tube; the cathode of the first diode, the emitter of the first switch tube and the collector of the second switch tube are connected together; the emitter of the second switching tube is connected with the collector of the third switching tube; the other end of the first capacitor, one end of the second capacitor, the anode of the first diode and the cathode of the second diode are connected together; the anode of the second diode, the emitter of the third switching tube and the collector of the fourth switching tube are connected together; the other end of the second capacitor is connected with an emitting electrode of the fourth switching tube;
when the sub-module circuit is used for replacing four half-bridge sub-modules close to an alternating voltage output side in the modular multilevel converter, one end of a first capacitor connected with a collector of a first switch tube is connected with a bridge arm inductor in the modular multilevel converter or other sub-modules of an upper bridge arm, an emitter of a second switch tube is connected with a load of the modular multilevel converter, and one end of the second capacitor connected with an emitter of a fourth switch tube is connected with the bridge arm inductor in the modular multilevel converter or other sub-modules of a lower bridge arm.
Further, the first diode and the second diode are power diodes.
Furthermore, the first switch tube, the second switch tube, the third switch tube and the fourth switch tube are power switch tubes with backward diodes, and each power switch tube with a backward diode is composed of a power switch tube and a power diode.
Compared with the prior art, the invention has the following advantages and beneficial effects:
1. in terms of the number of components, four half-bridge type sub-modules (i.e., a half-bridge type sub-module group) of a conventional modular multilevel converter include 4 capacitors and 8 power switching tubes with backward diodes (each power switching tube with backward diodes is composed of one power switching tube and one power diode), so that the original four half-bridge type sub-modules include 4 capacitors, 8 power switching tubes and 8 power diodes. Under the condition of unchanging function, the sub-module circuit only comprises 2 capacitors, 4 power switch tubes with backward diodes (each power switch tube with backward diodes consists of a power switch tube and a power diode) and 2 diodes, and the total number of the 2 capacitors, the 4 switch tubes and the 6 diodes is 2, compared with the number of the capacitors of the original circuit, the number of the switch tubes is reduced by 4, and the number of the diodes is reduced by 2, so that the size and the cost of the converter can be greatly reduced by using the sub-module circuit.
2. In the submodule capacitor voltage ripple, the submodule circuit of the invention has the advantages that the capacitor voltage ripple does not contain fundamental wave component, the amplitude of the capacitor voltage ripple is small, and the submodule capacitor voltage ripple has wide application prospect.
Drawings
Fig. 1 is a schematic circuit diagram of a sub-module according to the present invention.
Fig. 2 is an overall topology diagram of a three-phase hybrid modular multilevel converter including the sub-module circuit of the present invention.
Fig. 3a to 3c are mode diagrams of the sub-module circuit of the present invention.
Fig. 4a to 4f are modal diagrams of four half-bridge model submodules (i.e., half-bridge model submodule groups) corresponding to fig. 3a to 3 c.
Fig. 5 is a graph of output line voltages for the three-phase hybrid modular multilevel converter of fig. 2.
Detailed Description
The present invention will be further described with reference to the following specific examples.
As shown in fig. 1, the sub-module circuit for the modular multilevel converter provided in this embodiment includes: 2 energy storage capacitors, each being a first capacitor C1A second capacitor C22 power diodes, respectively a first diode D1A second diode D 24 power switch tubes with reverse diodes, respectively a first switch tube T1A second switch tube T2A third switch tube T3And a fourth switching tube T4(ii) a The first capacitor C1And a first switching tube T1Is connected with the collector of the collector; the first diode D1Cathode and first switch tube T1Emitter and second switching tube T2Are connected together; the second switch tube T2Emitter and third switching tube T3Is connected with the collector of the collector; the first capacitor C1Another terminal of (1), a second capacitor C2One end of (1), a first diode D1And a second diode D2Are connected together; the second diode D2Anode and third switching tube T3Emitter and fourth switching tube T4Are connected together; the second capacitor C2And the other end of the fourth switch tube T4Is connected to the emitter.
When the sub-module circuit is used for replacing four half-bridge sub-modules close to the alternating-current voltage output side in the modular multilevel converter, the first capacitor C1Is connected with a first switch tube T1One end of the collector is connected with the bridge arm inductor in the modular multilevel converter or other sub-modules of the upper bridge arm, and the second switch tube T2Is connected to the load of the modular multilevel converter, said second capacitor C2Is connected with a fourth switching tube T4One end of the emitter is connected with the bridge arm inductor in the modular multilevel converter or other sub-modules of the lower bridge arm.
When the sub-module circuit of the invention is connected with the bridge arm inductor, the overall topology of the obtained three-phase hybrid modular multilevel converter is shown in figure 2.
When the circuit of the invention is used for a modular multilevel converter, the circuit comprises 3 modes, as shown in fig. 3a to 3c, and the corresponding original half-bridge model submodule group comprises 6 modes, as shown in fig. 4a to 4 f.
When the first switch tube T1A second switch tube T2And a second diode D2Turn-off, third switching tube T3A fourth switch tube T4And a first diode D1When conducting, the circuit of the present invention is in mode 1, as shown in fig. 3 a. At the moment, the converter outputs voltage u to the external upper bridge armnIs twice the capacitor voltage 2UCOutput voltage u of lower bridge armpThe mode number of the corresponding half-bridge model submodule group is 0, as shown in fig. 4 a.
When the first switch tube T1A second switch tube T2And a second diode D2Conducting, third switch tube T3A fourth switch tube T4And a first diode D1When switched off, the circuit of the invention is in mode 2, as shown in fig. 3 b. At the moment, the converter outputs voltage u to the external upper bridge arm n0, lower arm output voltage upIs twice the capacitor voltage 2UCThe mode of the corresponding half-bridge model submodule group is shown in fig. 4 b.
When the first switch tube T1A fourth switch tube T4Turn-off, second switch tube T2A third switch tube T3A first diode D1And a second diode D2When conducting, the circuit of the present invention is in mode 3, as shown in fig. 3 c. At the moment, the converter outputs voltage u to the external upper bridge armnOne time of capacitor voltage UCOutput voltage u of lower bridge armpOne time of capacitor voltage UCThe modes of the corresponding half-bridge model submodule groups are shown in fig. 4c to 4 f.
Through the analysis, the circuit provided by the invention can completely replace the original half-bridge model submodule group. Meanwhile, compared with the original half-bridge model submodule group, the circuit provided by the invention has fewer elements such as capacitors, switching tubes and diodes.
In order to further verify the correctness of the sub-module circuit of the present invention, the circuit shown in fig. 2 was verified by simulation (N is 1), and the PWM modulation method was used for the simulation. As can be seen from fig. 5, the voltage output of the three-phase hybrid modular multilevel converter after using the sub-module circuit of the invention is consistent with the output voltage of the common three-phase modular multilevel converter. Therefore, the submodule circuit can replace a half-bridge model submodule group, the number of elements is reduced, the function of the circuit is kept unchanged, and the submodule circuit has practical application value and is worthy of popularization.
The above-mentioned embodiments are merely preferred embodiments of the present invention, and the scope of the present invention is not limited thereto, so that the changes in the shape and principle of the present invention should be covered within the protection scope of the present invention.
Claims (3)
1. A sub-module circuit for a modular multilevel converter, comprising: the sub-module circuit comprises a first capacitance (C)1) A second capacitor (C)2) A first diode (D)1) A second diode (D)2) A first switch tube (T)1) A second switch tube (T)2) And a third switching tube (T)3) And a fourth switching tube (T)4) (ii) a The first capacitor (C)1) And a first switching tube (T)1) Is connected with the collector of the collector; the first diode (D)1) Cathode of (1), first switch tube (T)1) Emitter and second switching tube (T)2) Are connected together; the second switch tube (T)2) Emitter and third switching tube (T)3) Is connected with the collector of the collector; the first capacitor (C)1) Another terminal of (C), a second capacitance (C)2) One terminal of (D), the first diode (D)1) And a second diode (D)2) Are connected together; the second diode (D)2) Anode and third switching tube (T)3) Emitter and fourth switching tube (T)4) Are connected together; the second capacitance (C)2) And the other end of the fourth switchPipe (T)4) The emitter of (3) is connected;
the first capacitor (C) is used to replace four half-bridge sub-modules near the AC voltage output side of the modular multilevel converter1) Is connected with a first switch tube (T)1) One end of the collector is connected with the bridge arm inductor in the modular multilevel converter or other sub-modules of the upper bridge arm, and the second switching tube (T)2) Is connected to the load of the modular multilevel converter, said second capacitance (C)2) Is connected with a fourth switching tube (T)4) One end of the emitter is connected with the bridge arm inductor in the modular multilevel converter or other sub-modules of the lower bridge arm.
2. The sub-module circuit for a modular multilevel converter of claim 1, wherein: the first diode (D)1) A second diode (D)2) Is a power diode.
3. The sub-module circuit for a modular multilevel converter of claim 1, wherein: the first switch tube (T)1) A second switch tube (T)2) And a third switching tube (T)3) And a fourth switching tube (T)4) Each power switch tube with the backward diode consists of one power switch tube and one power diode.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911298436.2A CN110995041A (en) | 2019-12-17 | 2019-12-17 | Submodule circuit for modular multilevel converter |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911298436.2A CN110995041A (en) | 2019-12-17 | 2019-12-17 | Submodule circuit for modular multilevel converter |
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| CN110995041A true CN110995041A (en) | 2020-04-10 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN201911298436.2A Pending CN110995041A (en) | 2019-12-17 | 2019-12-17 | Submodule circuit for modular multilevel converter |
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104980054A (en) * | 2014-04-03 | 2015-10-14 | 施耐德东芝换流器欧洲公司 | Multi-level power converter |
| US20150333658A1 (en) * | 2014-05-13 | 2015-11-19 | Schneider Toshiba Inverter Europe Sas | Multi-level power converter |
| US20160049880A1 (en) * | 2013-08-29 | 2016-02-18 | Korea Electric Power Corporation | High-voltage direct current converter |
| CN105723607A (en) * | 2013-09-23 | 2016-06-29 | 西门子公司 | New four-level converter cell topology for cascaded modular multilevel converters |
-
2019
- 2019-12-17 CN CN201911298436.2A patent/CN110995041A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20160049880A1 (en) * | 2013-08-29 | 2016-02-18 | Korea Electric Power Corporation | High-voltage direct current converter |
| CN105723607A (en) * | 2013-09-23 | 2016-06-29 | 西门子公司 | New four-level converter cell topology for cascaded modular multilevel converters |
| CN104980054A (en) * | 2014-04-03 | 2015-10-14 | 施耐德东芝换流器欧洲公司 | Multi-level power converter |
| US20150333658A1 (en) * | 2014-05-13 | 2015-11-19 | Schneider Toshiba Inverter Europe Sas | Multi-level power converter |
Non-Patent Citations (1)
| Title |
|---|
| TENG LIU ET AL: "A Novel Capacitor Voltage Balancing Method for an Improved MMC Circuit with Three-level Middle Modules", 《2015 IEEE 2ND INTERNATIONAL FUTURE ENERGY ELECTRONICS CONFERENCE (IFEEC)》 * |
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Application publication date: 20200410 |