CN217335099U - DC power supply system - Google Patents
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- CN217335099U CN217335099U CN202220405041.9U CN202220405041U CN217335099U CN 217335099 U CN217335099 U CN 217335099U CN 202220405041 U CN202220405041 U CN 202220405041U CN 217335099 U CN217335099 U CN 217335099U
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Abstract
The utility model provides a direct current power supply system, which comprises a one-way current type modularized multilevel converter and a DC/AC converter module, wherein the AC end of the one-way current type modularized multilevel converter is connected with an AC power grid, the DC end of the one-way current type modularized multilevel converter is connected with the DC input end of the DC/AC converter module, and the AC output end of the DC/AC converter module is connected with a load; each bridge arm of the unidirectional current type modularized multi-level converter comprises a plurality of sub-modules, the sub-modules comprise at least one unidirectional current type full-bridge sub-module and at least one clamping unidirectional current type sub-module, and the unidirectional current type full-bridge sub-modules and the clamping unidirectional current type sub-modules are connected in series in a mixed mode. According to the utility model discloses, when having solved the many level current converter of current modularization and being arranged in direct current power supply system, be difficult to realize the compactification of transverter and the problem of low cost.
Description
Technical Field
The utility model relates to a power electronic power conversion field especially relates to a DC power supply system.
Background
In many industrial applications, an ac power source is required to power a plurality of loads over a long distance. When the power is supplied through the alternating current cable, when the power supply distance is longer, the voltage of the load end under the heavy load condition is seriously reduced due to the action of reactive power flow of the load and line inductance, and the normal work of the load is seriously influenced. In addition, in the case of light loads, the capacitive effect of the cable to ground will also raise the line end voltage. Changing the ac power supply system to the dc power supply system is an effective method for solving this problem. In a DC power supply system, an AC/DC converter converts an AC power voltage into a DC voltage, and the DC voltage is transmitted to a load through a DC cable, and the DC/AC converter converts the DC voltage into an AC voltage to supply power to the load. When the capacity of a power supply system is large, the required voltage needs to reach a medium-high voltage level, high requirements are provided for the voltage level and the capacity of the AC/DC converter, and high requirements are provided for the harmonic performance, the efficiency, the power density, the cost and the like of the converter.
In the existing direct current power supply system, a technical scheme of a converter is a low-level number conversion topological scheme such as a conventional two-level converter and a conventional three-level converter. The voltage and capacity grade that two-level transverter and three-level transverter can realize is limited, need adopt switching device to establish ties when realizing great capacity and voltage grade, and the quiet dynamic voltage-sharing problem when switching device directly establishes ties is difficult to solve. In addition, the two-level converter and the three-level converter have the defects of large harmonic wave, high loss, large dv/dt and the like. Another class of solutions is modular multilevel converters. The modular multilevel converter has the advantages of high voltage and capacity level, good harmonic characteristics, low loss and the like, and is widely applied to the fields of direct current transmission and the like. However, the power fluctuation of each bridge arm of the modular multilevel converter cannot be mutually offset among three phases, and in order to limit the amplitude of the voltage fluctuation of the capacitor of the sub-module, the required sub-module has huge capacitance, so that the size and the cost of the modular multilevel converter are higher. When a conventional modular multilevel converter is used in a dc power supply system, it is difficult to achieve a compact and low-cost converter.
SUMMERY OF THE UTILITY MODEL
The utility model discloses aim at solving one of above-mentioned technical problem at least.
Therefore, a first object of the present invention is to provide a dc power supply system that can achieve a compact inverter and a low cost.
In order to achieve the above object, the present invention provides a dc power supply system, including:
the DC/AC converter module is connected with the DC/AC converter module, the AC end of the DC/AC converter module is connected with the DC input end of the DC/AC converter module, and the AC output end of the DC/AC converter module is connected with a load; each bridge arm of the unidirectional current type modularized multi-level converter comprises a plurality of sub-modules, the sub-modules comprise at least one unidirectional current type full bridge sub-module and at least one clamped unidirectional current type sub-module, and the unidirectional current type full bridge sub-modules and the clamped unidirectional current type sub-modules are mixed and connected in series;
the unidirectional current type modular multilevel converter is used for converting alternating current output by an alternating current power grid into direct current, and the DC/AC converter module is used for converting the direct current into the alternating current.
According to the utility model discloses the DC power supply system, adopt the many level current converter of one-way current type modularization, wherein the submodule piece of one-way current type modularization includes at least one-way current type full bridge submodule piece and at least one clamping one-way current type submodule piece, one-way current type full bridge submodule piece and the mixed series connection of clamping one-way current type submodule piece, because the voltage output effect of a clamping one-way current type submodule piece is equivalent to two one-way current type full bridge submodule pieces, under this condition, every bridge arm cascade module number can be descended by a wide margin, thereby make DC power supply system's volume and cost obtain reducing by a wide margin, when having solved current many level current converter of modularization and being used for among the DC power supply system, be difficult to realize the compactification of transverter and the problem of low cost.
The utility model discloses an in the embodiment, the one-way current type full-bridge submodule quantity of each bridge arm is the same, and the one-way current type submodule quantity of clamp of each bridge arm is the same.
In an embodiment of the present invention, the clamping unidirectional current type submodule includes a first switch unit, a second switch unit, a third switch unit, a first diode, a second diode, a third diode, a fourth diode, a fifth diode, a sixth diode, a seventh diode, a first energy storage capacitor and a second energy storage capacitor; the input ends of the first switch unit, the second switch unit and the third switch unit are respectively connected with the cathodes of the first diode, the second diode and the third diode, the output ends of the first switch unit, the second switch unit and the third switch unit are respectively connected with the anodes of the first diode, the second diode and the third diode, the input end of the first switch unit is sequentially connected with the input end of the second switch unit through the fifth diode and the seventh diode, the output end of the first switch unit is sequentially connected with the output end of the second switch unit through the sixth diode and the fourth diode, the anode of the seventh diode is simultaneously connected with the cathode of the fifth diode, the anode of the first energy storage capacitor and the input end of the third switch unit, the cathode of the seventh diode is connected with the anode of the second energy storage capacitor, the cathode of the sixth diode is simultaneously connected with the anode of the fourth diode, The cathode of the second energy storage capacitor and the output end of the third switching unit, and the anode of the sixth diode are connected with the cathode of the first energy storage capacitor.
In an embodiment of the present invention, the unidirectional current type full bridge submodule includes a third energy storage capacitor, a fifth switch unit, a sixth switch unit, an eighth diode, a ninth diode, a twelfth diode, and an eleventh diode; the input end of the fifth switch unit is simultaneously connected with the cathode of the eighth diode and the anode of the twelfth diode, the output end of the fifth switch unit is simultaneously connected with the anode of the eighth diode, the cathode of the third energy-storage capacitor and the anode of the eleventh diode, the input end of the sixth switch unit is simultaneously connected with the cathode of the ninth diode, the cathode of the twelfth diode and the anode of the third energy-storage capacitor, and the output end of the sixth switch unit is simultaneously connected with the anode of the ninth diode and the cathode of the eleventh diode.
In an embodiment of the present invention, each switch unit is an insulated gate bipolar transistor or an integrated gate commutated thyristor.
In one embodiment of the present invention, the modulation ratio of the unidirectional current mode modular multilevel converter is at least 1.33.
In an embodiment of the present invention, the DC/AC converter module is composed of a plurality of DC/AC converters connected in series, the positive DC terminal of the first DC/AC converter and the negative DC terminal of the last DC/AC converter form the DC input terminal of the DC/AC converter module, and the AC terminals of the DC/AC converters form the AC output terminal of the DC/AC converter module.
In an embodiment of the present invention, the DC/AC converter module is composed of a plurality of DC/AC converters connected in parallel, the positive DC terminal and the negative DC terminal of each DC/AC converter form the DC input terminal of the DC/AC converter module, and the AC terminal of each DC/AC converter forms the AC output terminal of the DC/AC converter module.
In an embodiment of the present invention, the unidirectional current-type modular multilevel converter is a unidirectional three-phase MMC structure.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Drawings
The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which,
fig. 1 is a schematic structural diagram of a dc power supply system according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram of a parallel connection mode of DC/AC converter modules of a DC power supply system according to an embodiment of the present invention;
fig. 3 is a schematic structural diagram of a series connection mode of DC/AC converter modules of a DC power supply system according to an embodiment of the present invention;
fig. 4 is a schematic structural diagram of a three-phase MMC structure according to an embodiment of the present invention;
fig. 5 is a schematic structural diagram of a unidirectional current type full bridge submodule according to an embodiment of the present invention;
fig. 6 is a schematic structural diagram of a clamping unidirectional current mode sub-module according to an embodiment of the present invention.
Detailed Description
Reference will now be made in detail to the exemplary embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, like numbers in different drawings represent the same or similar elements unless otherwise indicated. The implementations described in the following exemplary embodiments do not represent all implementations consistent with embodiments of the present invention. Rather, they are merely examples of apparatus and methods consistent with certain aspects of embodiments of the invention, as detailed in the appended claims.
In the description of the present specification, reference to the description of "one embodiment," "some embodiments," "an example," "a specific example," or "some examples" or the like means 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 present invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.
Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise. It should also be understood that the term "and/or" as used in this disclosure refers to and encompasses any and all possible combinations of one or more of the associated listed items.
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are exemplary and intended to be used for explaining the present invention, and should not be construed as limiting the present invention.
A dc power supply system according to an embodiment of the present invention is described below with reference to the drawings.
The conventional modular multilevel converter is used in the current direct current power supply system, and in order to limit the amplitude of voltage fluctuation of a sub-module capacitor, the required sub-module capacitance and the number of sub-modules are huge, so that the size and the cost of the modular multilevel converter are higher, and the conventional modular multilevel converter is difficult to realize the compactness and the low cost of the converter when being used in the direct current power supply system. Therefore, the utility model provides a direct current power supply system.
Fig. 1 is a schematic structural diagram of a dc power supply system according to an embodiment of the present invention.
As shown in fig. 1, the DC power supply system includes a unidirectional current mode modular multilevel converter and a DC/AC converter module. The alternating current end of the unidirectional current type modular multilevel converter is connected with an alternating current power grid, the direct current end of the unidirectional current type modular multilevel converter is connected with the direct current input end of the DC/AC converter module, and the alternating current output end of the DC/AC converter module is connected with a load. The unidirectional current type modular multilevel converter is used for converting alternating current output by an alternating current power grid into direct current, and the DC/AC converter module is used for converting the direct current into alternating current required by a load. The ac power supply system may be, for example, a three-phase ac power supply system.
In this embodiment, the DC/AC converter module may include a plurality of DC/AC converters, and the load may be multiple, and the AC terminal of each DC/AC converter may be connected to the corresponding load.
In some embodiments, the DC/AC converter module may be composed of a plurality of DC/AC converters connected in parallel. Fig. 2 is a schematic structural diagram of a parallel connection mode of DC/AC converter modules of a DC power supply system according to an embodiment of the present invention. As shown in fig. 2, the DC/AC converters in the DC/AC converter module are connected in parallel with each other. The direct current positive end of each DC/AC converter is connected with the direct current positive end of the unidirectional current type modular multilevel converter, the direct current negative end of each DC/AC converter is connected with the direct current negative end of the unidirectional current type modular multilevel converter, the direct current positive end and the direct current negative end of each DC/AC converter form the direct current input end of the DC/AC converter module, and the alternating current end of each DC/AC converter forms the alternating current output end of the DC/AC converter module.
In some embodiments, the DC/AC converter module may be composed of a plurality of DC/AC converters connected in series. Fig. 3 is a schematic structural diagram of a series connection mode of DC/AC converter modules of a DC power supply system according to an embodiment of the present invention. As shown in fig. 3, a plurality of DC/AC converters in the DC/AC converter module may be connected in series in sequence. The direct current positive end of the first DC/AC converter is connected with the direct current positive end of the unidirectional current type modular multilevel converter, the direct current negative end of the last DC/AC converter is connected with the direct current negative end of the unidirectional current type modular multilevel converter, and the direct current positive ends of the other DC/AC converters are connected with the direct current negative end of the previous DC/AC converter. The direct current positive end of the first DC/AC converter and the direct current negative end of the last DC/AC converter form the direct current input end of the DC/AC converter module, and the alternating current end of each DC/AC converter forms the alternating current output end of the DC/AC converter module.
In this embodiment, unidirectional current mode modular multilevel commutationEach phase of the device comprises an upper bridge arm and a lower bridge arm, each bridge arm of the unidirectional current type modularized multi-level current converter comprises a plurality of sub-modules, wherein the plurality of sub-modules can comprise at least one unidirectional current type full-bridge sub-module and at least one clamping unidirectional current type sub-module, and the unidirectional current type full-bridge sub-module and the clamping unidirectional current type sub-module are connected in series in a mixed mode. The number of the unidirectional current type full-bridge submodules of each bridge arm is the same, and the number of the clamping unidirectional current type submodules of each bridge arm is the same. For example, each leg comprises N submodules, N submodules comprising N i The number of the same one-way current type full-bridge sub-modules and N j One and the same clamped unidirectional current type submodule, i.e. N i +N j ＝N。N i The number of the one-way current type full-bridge sub-modules and N j And the clamping unidirectional current type submodules are mixed and connected in series.
In this embodiment, the manner of mixing the series is not limited. For example, the unidirectional current type full-bridge submodule and the clamping unidirectional current type submodule can be connected in series in a staggered mode; n is a radical of i A module formed by connecting the unidirectional current type full-bridge submodules in series is then connected with N j And modules formed by connecting the clamping unidirectional current type submodules in series are connected in series. In addition, the submodules among the bridge arms can be mixed and connected in series and can be the same or different.
In this embodiment, the unidirectional current type modular multilevel converter is a unidirectional three-phase MMC structure. Fig. 4 is a schematic structural diagram of a three-phase MMC structure according to an embodiment of the present invention. As shown in fig. 4, each phase of the three-phase MMC structure includes an upper bridge arm and a lower bridge arm, and each bridge arm is formed by cascading N sub-modules. The lower end of the upper bridge arm and the upper end of the lower bridge arm of each phase are connected together through an inductor L, the middle point of the inductor (namely the connection point of the two inductors L) becomes the alternating current input end of the phase (namely the alternating current bus of the phase), the three-phase alternating current input ends of the three-phase MMC structure respectively correspond to A, B, C three phases of a three-phase alternating current power grid, the upper ends of the upper bridge arms of all the phases are connected together to become a direct current positive end (namely a direct current positive bus), and the lower ends of the lower bridge arms of all the phases are connected together to become a direct current negative end (namely a direct current negative bus). The N sub-modules of each leg in FIG. 4 comprise N i All of the same unidirectional current modeBridge submodule number and N j The same clamping unidirectional current mode submodule.
In other embodiments, the number of unidirectional current mode full bridge sub-modules on different legs may be different. The number of clamping unidirectional current model sub-modules on different bridge arms can be different.
Fig. 5 is a schematic structural diagram of a unidirectional current type full bridge submodule according to an embodiment of the present invention; fig. 6 is a schematic structural diagram of a clamping unidirectional current mode sub-module according to an embodiment of the present invention.
In the present embodiment, as shown in fig. 6, the clamping unidirectional current type submodule includes three switch units, including a first switch unit S11, a second switch unit S12 and a third switch unit S13, seven diodes including a first diode D11, a second diode D12, a third diode D13, a fourth diode D14, a fifth diode D15, a sixth diode D16 and a seventh diode D17, and two energy storage capacitors including a first energy storage capacitor C11 and a second energy storage capacitor C12.
In the present embodiment, as shown in fig. 6, the input terminals of the first switching unit S11, the second switching unit S12, and the third switching unit S13 are connected to the cathodes of the first diode D11, the second diode D12, and the third diode D13, respectively. The output terminals of the first, second and third switching units S11, S12 and S13 are connected to the anodes of the first, second and third diodes D11, D12 and D13, respectively. An input terminal of the first switching unit S11 is connected to an input terminal of the second switching unit S12 through a fifth diode D15 and a seventh diode D17 in sequence, and an output terminal of the first switching unit S11 is connected to an output terminal of the second switching unit S12 through a sixth diode D16 and a fourth diode D14 in sequence.
In the present embodiment, as shown in fig. 6, the anode of the fifth diode D15 is connected to the input terminal of the first switching unit S11, and the anode of the seventh diode D17 is simultaneously connected to the cathode of the fifth diode D15, the anode of the first energy storage capacitor C11 and the input terminal of the third switching unit S13. The cathode of the seventh diode D17 is connected to the anode of the second energy-storing capacitor C12 and the input terminal of the second switching unit S12. The cathode of the sixth diode D16 is simultaneously connected to the anode of the fourth diode D14, the cathode of the second energy-storage capacitor C12, and the output terminal of the third switching unit S13. The anode of the sixth diode D16 is connected to the cathode of the first energy-storing capacitor C11 and the output terminal of the first switching unit S11.
In the present embodiment, as shown in fig. 5, the unidirectional current type full-bridge submodule includes two switching units including a fifth switching unit S21 and a sixth switching unit S22, four diodes including an eighth diode D21, a ninth diode D22, a twelfth diode D23 and an eleventh diode D24, and a third energy storage capacitor C21.
In the present embodiment, as shown in fig. 5, the input terminal of the fifth switching unit S21 is simultaneously connected to the cathode of the eighth diode D21 and the anode of the twelfth diode D23. An output terminal of the fifth switching unit S21 is simultaneously connected to an anode of the eighth diode D21, a cathode of the third energy storage capacitor C21, and an anode of the eleventh diode D24. The input terminal of the sixth switching unit S22 is simultaneously connected to the cathode of the ninth diode D22, the cathode of the twelfth diode D23 and the anode of the third energy-storing capacitor C21. An output terminal of the sixth switching unit S22 is connected to both an anode of the ninth diode D22 and a cathode of the eleventh diode D24.
In this embodiment, each switch unit in each sub-module further includes a control end, and the control end of each switch unit in each sub-module receives a control signal output from a controller in the unidirectional current type modular multilevel converter to realize the on/off of the switch unit, so that the unidirectional current type modular multilevel converter operates normally.
In this embodiment, each switch unit in the unidirectional current type full-bridge submodule and the clamped unidirectional current type submodule may be an Insulated Gate Bipolar Transistor (IGBT) or an Integrated Gate Commutated Thyristor (IGCT). When the switch unit is an IGBT, the input end of the switch unit is a collector (C) of the IGBT, the output end of the switch unit is an emitter (E) of the IGBT, and the control end of the switch unit is a grid (G) of the IGBT; when the switch unit is an IGCT, the input end of the switch unit is the anode (a) of the IGCT, the output end of the switch unit is the cathode (K) of the IGCT, and the control end of the switch unit is the gate (G) of the IGCT.
In the present embodiment, the modulation ratio of the unidirectional current type modular multilevel converter is obtained based on the ac phase voltage amplitude and the dc rated voltage. Specifically, the modulation ratio is equal to 2 times the amplitude of the ac phase voltage divided by the dc rated voltage. The modulation ratio of the unidirectional current mode modular multilevel converter of the embodiment is at least 1.33. In this case, since the modulation ratio of the conventional modular multilevel converter is generally about 0.85 and not higher than 1, the modulation ratio of the unidirectional current type modular multilevel converter is increased in the present embodiment. The modulation ratio is increased to a proper value, so that the bridge arm power fluctuation of the modular multilevel converter reaches an extremely low point, and the capacitance consumption of the modular multilevel converter is greatly reduced.
In this embodiment, the modulation ratio may be set by a controller in the unidirectional current mode modular multilevel converter. In addition, the modulation ratio is adjustable, and specifically, the modulation ratio of the unidirectional current type modular multilevel converter can be adjusted through a controller according to actual requirements.
According to the utility model discloses direct current supply system, the transverter at the alternating current network side adopts the many level transverter of one-way current type modularization. In this case, since the converter adopts a modular multilevel converter topology, the dc power supply system of the embodiment has the advantages of high voltage and capacity level, low harmonic, high efficiency, and the like. In addition, considering that the dc power supply system is a unidirectional power transmission occasion, the power only needs to be transmitted from the ac power source to the load, so the unidirectional current type sub-module is adopted in the modular multilevel converter of this embodiment, that is, the unidirectional current type modular multilevel converter is adopted in this embodiment, wherein the sub-module of the unidirectional current type modular multilevel converter includes at least one unidirectional current type full bridge sub-module and at least one clamping unidirectional current type sub-module, the unidirectional current type full bridge sub-module and the clamping unidirectional current type sub-module are mixed and connected in series, because the voltage output effect of one clamping unidirectional current type sub-module is equivalent to that of two unidirectional current type full bridge sub-modules, in this case, the number of cascaded modules of each bridge arm can be greatly reduced, thereby the volume and the cost of the dc power supply system can be greatly reduced, in addition, in this embodiment, considering that the unidirectional current type sub-module can output a negative level, the modulation ratio which can be realized by the modular multilevel converter is set, the set modulation ratio is higher than that of the prior modular multilevel converter, by increasing the modulation ratio to a proper value, the bridge arm power fluctuation of the modular multilevel converter can reach an extremely low point, the capacitance consumption of the modular multilevel converter is greatly reduced, therefore, the capacitance usage of the unidirectional current type modular multilevel converter in the embodiment is greatly reduced, and in summary, the capacitance usage and the number of sub-modules of the unidirectional current type modular multilevel converter in the embodiment are greatly reduced, so that the volume and the cost of a direct current power supply system are greatly reduced, and the problem that the existing modular multilevel converter is difficult to realize the compactness and the low cost of the converter when used in a direct current power supply system is solved. In addition, because the unidirectional current type modular multilevel converter has the capability of blocking the direct-current fault current, the direct-current power supply system of the embodiment can also realize the quick self-clearing of the short-circuit fault of the direct-current line.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," 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, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
While embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.
Claims (9)
1. A dc power supply system, comprising:
the DC/AC converter module is connected with the DC/AC converter module, the AC end of the DC/AC converter module is connected with the DC input end of the DC/AC converter module, and the AC output end of the DC/AC converter module is connected with a load; each bridge arm of the unidirectional current type modularized multi-level converter comprises a plurality of sub-modules, the sub-modules comprise at least one unidirectional current type full-bridge sub-module and at least one clamping unidirectional current type sub-module, and the unidirectional current type full-bridge sub-modules and the clamping unidirectional current type sub-modules are connected in series in a mixed mode;
the unidirectional current type modular multilevel converter is used for converting alternating current output by an alternating current power grid into direct current, and the DC/AC converter module is used for converting the direct current into the alternating current.
2. The dc power supply system of claim 1, wherein the number of unidirectional current full-bridge submodules of each bridge arm is the same, and the number of clamped unidirectional current full-bridge submodules of each bridge arm is the same.
3. The DC power supply system of claim 1, wherein the clamping unidirectional current type submodule comprises a first switch unit, a second switch unit, a third switch unit, a first diode, a second diode, a third diode, a fourth diode, a fifth diode, a sixth diode, a seventh diode, a first energy storage capacitor and a second energy storage capacitor;
the input ends of the first switch unit, the second switch unit and the third switch unit are respectively connected with the cathodes of the first diode, the second diode and the third diode, the output ends of the first switch unit, the second switch unit and the third switch unit are respectively connected with the anodes of the first diode, the second diode and the third diode, the input end of the first switch unit is sequentially connected with the input end of the second switch unit through the fifth diode and the seventh diode, the output end of the first switch unit is sequentially connected with the output end of the second switch unit through the sixth diode and the fourth diode, the anode of the seventh diode is simultaneously connected with the cathode of the fifth diode, the anode of the first energy storage capacitor and the input end of the third switch unit, the cathode of the seventh diode is connected with the anode of the second energy storage capacitor, the cathode of the sixth diode is simultaneously connected with the anode of the fourth diode, The cathode of the second energy storage capacitor and the output end of the third switching unit, and the anode of the sixth diode are connected with the cathode of the first energy storage capacitor.
4. The DC power supply system of claim 1, wherein the unidirectional current type full bridge submodule comprises a third energy storage capacitor, a fifth switch unit, a sixth switch unit, an eighth diode, a ninth diode, a twelfth diode and an eleventh diode;
the input end of the fifth switch unit is simultaneously connected with the cathode of the eighth diode and the anode of the twelfth diode, the output end of the fifth switch unit is simultaneously connected with the anode of the eighth diode, the cathode of the third energy-storage capacitor and the anode of the eleventh diode, the input end of the sixth switch unit is simultaneously connected with the cathode of the ninth diode, the cathode of the twelfth diode and the anode of the third energy-storage capacitor, and the output end of the sixth switch unit is simultaneously connected with the anode of the ninth diode and the cathode of the eleventh diode.
5. The DC power supply system according to claim 3 or 4, wherein each switch unit is an insulated gate bipolar transistor or an integrated gate commutated thyristor.
6. The dc power supply system of claim 1, wherein the modulation ratio of the unidirectional current mode modular multilevel converter is at least 1.33.
7. A DC power supply system according to claim 1, characterized in that the DC/AC converter module is composed of a plurality of DC/AC converters connected in series, the positive DC terminal of the first DC/AC converter and the negative DC terminal of the last DC/AC converter forming the DC input terminals of the DC/AC converter module, and the AC terminal of each DC/AC converter forming the AC output terminal of the DC/AC converter module.
8. A DC power supply system according to claim 1, wherein the DC/AC converter module is formed by a plurality of DC/AC converters connected in parallel, the positive DC terminal and the negative DC terminal of each DC/AC converter forming the DC input terminal of the DC/AC converter module, and the AC terminal of each DC/AC converter forming the AC output terminal of the DC/AC converter module.
9. The dc power supply system of claim 1, wherein the unidirectional current-mode modular multilevel converter is a unidirectional three-phase MMC structure.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202220405041.9U CN217335099U (en) | 2022-02-25 | 2022-02-25 | DC power supply system |
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