A DC power supply

Abstract

This utility model discloses a DC power supply, comprising: an input reactor unit, a power module array, and an output reactor unit. The power module array includes three power module groups, each power module group comprising several power modules for power conversion. The input sides of the power modules are cascaded to form the AC input terminal of the power module group. Each power module group has N DC output terminals, each DC output terminal being formed by cascading the output sides of at least two power modules. The AC input terminals of the three power module groups are respectively connected to the power grid through the input reactor unit, and the DC output terminals of the three power module groups are respectively connected in parallel through the output reactor units and then connected to the load. This utility model enables direct connection of the DC power supply to the power grid, reduces the size of the power supply, and meets the requirements for high-voltage, high-current DC power supply.

Description

Technical Field

[0001] This utility model relates to the field of power supply technology, and in particular to a DC power supply. Background Technology

[0002] With the rapid development of artificial intelligence technology and tokamak nuclear fusion power generation technology, traditional thyristor rectification power supply technology can no longer meet the requirements of high voltage and high current DC power supply for relevant application scenarios. In addition, it is necessary to add a power frequency inverter to the DC power supply for isolation and voltage reduction, resulting in a large DC power supply size. Utility Model Content

[0003] The technical problem to be solved by this utility model is to provide a DC power supply that can meet the requirements of high voltage and high current DC power supply and has a small size.

[0004] To solve the above-mentioned technical problems, this utility model provides a DC power supply, comprising: an input reactor unit, a power module array, and an output reactor unit, wherein... The power module array includes three power module groups, each power module group includes several power modules, and the input sides of the several power modules are cascaded to form the AC input terminal of the power module group. The power module group has N DC output terminals, each DC output terminal is formed by cascading the output sides of at least two power modules. The AC input terminals of the three power module groups are respectively connected to the power grid through the input reactor unit, and the DC output terminals of the three power module groups are respectively connected in parallel through the output reactor unit and then connected to the load, where N is an integer not less than 1.

[0005] A further technical solution is as follows: the DC power supply also includes a soft-start unit, which is connected between the input reactor unit and the power grid.

[0006] The further technical solution is as follows: the soft start unit includes three soft start circuits connected in parallel between the three-phase output of the power grid and the input reactor unit. Each soft start circuit includes a first switch, a second switch and a current-limiting resistor; wherein, the first switch and the current-limiting resistor are connected in series and then connected in parallel with the second switch between the input reactor unit and the power grid.

[0007] The further technical solution is as follows: the power module includes a first H-bridge converter, a second H-bridge converter, and an isolated DC / DC converter connected between the first H-bridge converter and the second H-bridge converter; wherein, the first H-bridge converters in a plurality of power modules of each power module group are cascaded to form the AC input terminal of each power module group; the second H-bridge converters in at least two power modules of each power module group are cascaded to form one set of DC output terminals of each power module group.

[0008] A further technical solution is as follows: the isolated DC / DC converter includes a third H-bridge converter, a transformer, and a fourth H-bridge converter connected in sequence; wherein, the primary winding and secondary winding of the transformer are respectively connected to the AC side of the third H-bridge converter and the fourth H-bridge converter, and the DC input side of the third H-bridge converter and the DC output side of the fourth H-bridge converter are respectively connected to the first H-bridge converter and the second H-bridge converter.

[0009] The further technical solution is as follows: The third H-bridge converter includes four third switching transistors and a first bus capacitor. Every two third switching transistors are connected in series to form a bridge arm. After two bridge arms are connected in parallel, their two ends serve as the DC input side of the third H-bridge converter, and the midpoint of the two bridge arms serves as the AC side of the third H-bridge converter. The first bus capacitor is connected between the DC input sides of the third H-bridge converter. The fourth H-bridge converter includes four fourth switching transistors and a second bus capacitor. Every two fourth switching transistors are connected in series to form a bridge arm. After two bridge arms are connected in parallel, their two ends serve as the DC output side of the fourth H-bridge converter, and the midpoint of the two bridge arms serves as the AC side of the fourth H-bridge converter. The second bus capacitor is connected between the DC output sides of the fourth H-bridge converter.

[0010] The further technical solution is as follows: the isolated DC / DC converter includes a first half-bridge converter, a resonant circuit, a transformer, and a second half-bridge converter connected in sequence; wherein, the DC input side of the first half-bridge converter is connected to the first H-bridge converter, the AC side of the first half-bridge converter is connected to the primary winding of the transformer via the resonant circuit, the secondary winding of the transformer is connected to the AC side of the second half-bridge converter, and the DC output side of the second half-bridge converter is connected to the second H-bridge converter.

[0011] The further technical solution is as follows: The first half-bridge converter includes two first switching transistors and a third bus capacitor, wherein the two first switching transistors are connected in series to form a bridge arm, the two ends of the bridge arm serve as the DC input side of the first half-bridge converter, the midpoint of the bridge arm serves as the AC side of the first half-bridge converter, and the third bus capacitor is connected between the two ends of the bridge arm; the second half-bridge converter includes two second switching transistors and a fourth bus capacitor, wherein the two second switching transistors are connected in series to form a bridge arm, the two ends of the bridge arm serve as the DC output side of the second half-bridge converter, the midpoint of the bridge arm serves as the AC side of the second half-bridge converter, and the fourth bus capacitor is connected between the two ends of the bridge arm.

[0012] A further technical solution is as follows: a bypass circuit is connected in parallel to the DC output terminal of the DC power supply, the bypass circuit including a resistor and a thyristor connected in series; and / or, an output capacitor is connected in parallel to the DC output terminal of the DC power supply.

[0013] The further technical solution is as follows: each power module group includes three power modules, the input sides of the three power modules are cascaded to form the AC input terminal of the power module group, and the output sides of the three power modules are cascaded to form a set of DC output terminals of the power module group. The AC input terminals of the three power module groups are respectively connected to the power grid through the input reactor unit, and the DC output terminals of the three power module groups are connected to the load after being connected in parallel through the output reactor unit.

[0014] Compared with the prior art, the DC power supply of this utility model includes a power module array comprising three power module groups. Within each power module group, the input sides of several power modules are cascaded to form the AC input terminal of that power module group. Each power module group has N DC output terminals, each consisting of at least two cascaded power module output sides. The AC input terminals of the three power module groups constitute the three-phase AC input terminals of the power module array, which are connected to the three phases of the power grid via input reactor units. The DC output terminals of the three power module groups constitute multiple DC output terminals of the power module array. The terminals are connected in parallel through the output reactor units and connected to the load. It can be seen that by cascading the input and output sides of the power modules in the power module array, the DC power supply can be directly connected to the power grid without the need for a power frequency inverter for isolation and voltage reduction, thus reducing the size of the power supply. Furthermore, electrical isolation can be further achieved through an isolated DC / DC converter, and voltage transformation can be realized. Combined with the cascading and parallel connection of the output sides of the power modules in the power module array, a combination of high voltage and high current output can also be achieved to meet the requirements of high voltage and high current DC power supply. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of the DC power supply of this utility model.

[0016] Figure 2 This is a schematic diagram of the structure of the first embodiment of the DC power supply of this utility model.

[0017] Figure 3 yes Figure 2 The diagram shows the specific structure of the power module in the DC power supply.

[0018] Figure 4 This is a structural schematic diagram of the second embodiment of the DC power supply of this utility model.

[0019] Figure 5 This is a structural schematic diagram of the third embodiment of the DC power supply of this utility model.

[0020] Figure 6 This is a structural schematic diagram of the fourth embodiment of the DC power supply of this utility model.

[0021] Figure 7 yes Figure 6 The diagram shows the specific structure of the power module in the DC power supply.

[0022] Figure 8 This is a structural schematic diagram of the fifth embodiment of the DC power supply of this utility model.

[0023] Figure 9 This is a schematic diagram of the sixth embodiment of the DC power supply of this utility model. Detailed Implementation

[0024] To better understand the technical content of this utility model, the technical solution of this utility model will be further introduced and explained below with reference to the schematic diagram, but it is not limited thereto.

[0025] Reference Figure 1 , Figure 1This is a schematic diagram of the structure of the DC power supply of this utility model. In the embodiment shown in the figure, the DC power supply of this utility model includes an input reactor unit 10, a power module array 20, and an output reactor unit 30. The power module array 20 includes three power module groups 21. Each power module group 21 includes several power modules for realizing power conversion. The input sides of the power modules are cascaded to form the AC input terminal of the power module group 21. The power module group 21 has N (N is an integer not less than 1) DC output terminals. Each DC output terminal is formed by cascading the output sides of at least two power modules. The AC input terminals of the three power module groups 21 are respectively connected to the power grid through the input reactor unit 10. The DC output terminals of the three power module groups 21 are respectively connected in parallel through the output reactor unit 30 and connected to the load. In this invention, the input reactor unit 10 includes three first reactors L1, and the output reactor unit 30 includes multiple second reactors L2, i.e., the number of second reactors L2 is set according to the number of power modules; while the load can be the TF coil or PF coil of the magnetic confinement device in the tokamak device. Based on the above design, in the DC power supply of this utility model, the input sides of several power modules in each power module group 21 are cascaded to form the AC input terminal of the power module group 21. The AC input terminals of the three power module groups 21 constitute the three-phase AC input terminal of the power module array 20, which are connected to the power grid through three first reactors L1 respectively. The power module group 21 has N sets of DC output terminals, each set of DC output terminals is formed by cascading the output sides of at least two power modules. The DC output terminals of the three power module groups 21 constitute multiple sets of DC output terminals of the power module array 20, which are connected in parallel through multiple second reactors L2 respectively, and connected to the load. That is, the power module group 21 in the power module array 20 can be directly connected to the power grid without the need for a power frequency inverter for isolation and voltage reduction, which can reduce the size of the power supply. Moreover, the output side of the power module array 20 is a cascaded + parallel connection method, which can also realize the combined output of high voltage and high current, meeting the requirements of high voltage and high current DC power supply.

[0026] Preferably, in some embodiments, the DC power supply may further include a soft-start unit 40 for buffering current, the soft-start unit 40 being connected between the input reactor unit 10 and the power grid. Specifically, the soft-start unit 40 includes three soft-start circuits connected in parallel between the three-phase output of the power grid and the input reactor unit 10. Each soft-start circuit includes a first switch S1, a second switch S2, and a current-limiting resistor R; wherein the first switch S1 and the current-limiting resistor R are connected in series, and then connected in parallel with the second switch S2 between the input reactor unit 10 and the power grid. Based on this design, the soft-start unit 40 can reduce the impact of the starting current, protecting the safe operation of the power grid and electrical equipment.

[0027] Reference Figures 2 to 3 , Figures 2 to 3 The first embodiment of the DC power supply of this utility model is shown. In the embodiment shown in the figures, each power module group 21 includes three power modules: power module 211A, power module 211B, and power module 211C. The input sides of the three power modules are cascaded to form the AC input terminal of the power module group 21, and the output sides of the three power modules are cascaded to form a set of DC output terminals of the power module group 21. The AC input terminals of the three power module groups 21 are respectively connected to the power grid through three first reactors L1, and the DC output terminals of the three power module groups 21 are respectively connected in parallel through three second reactors L2 and connected to the load.

[0028] Specifically, such as Figure 2 and Figure 3 As shown, each power module includes a first H-bridge converter 2111 for converting AC voltage to DC voltage, a second H-bridge converter 2113 for adjusting the DC voltage to a target voltage, and an isolated DC / DC converter 2112 connected between the first H-bridge converter 2111 and the second H-bridge converter 2113; wherein, the first H-bridge converters 2111 in the three power modules of each power module group 21 are cascaded to form the AC input terminal of each power module group 21; the second H-bridge converters 2113 in the three power modules of each power module group 21 are cascaded to form the DC output terminal of each power module group 21.

[0029] Combination Figure 2Taking one power module group 21 as an example, the specific connection of the first H-bridge converter 2111 and the second H-bridge converter 2113 in the power module is described. Specifically, the midpoints of the two arms of the first H-bridge converter 2111 in power module 211B are respectively connected to the midpoints of one arm of the first H-bridge converter 2111 in power module 211A and the midpoints of one arm of the first H-bridge converter 2111 in power module 211C, realizing a cascaded connection. The midpoint of the other arm of the first H-bridge converter 2111 in power module 211A serves as the AC input terminal of the power module group 21 and is connected to the first reactor L1. The midpoint of the other arm of the first H-bridge converter 2111 in power module 211C is connected to the arm of the first H-bridge converter 2111 in the power modules of the other two power module groups 21. The midpoints of the two arms of the second H-bridge converter 2113 in power module 211B are respectively connected to the midpoints of one arm of the second H-bridge converter 2113 in power module 211A and one arm of the second H-bridge converter 2113 in power module 211C, thus achieving a cascaded connection. The midpoint of the other arm of the second H-bridge converter 2113 in power module 211A serves as the DC output terminal of the power module group 21 and is connected to the second reactor L2. The midpoint of the other arm of the second H-bridge converter 2113 in power module 211C is connected to the arm of the second H-bridge converter 2113 in the power module 211C of the other two power module groups 21 and is connected to the load.

[0030] In some embodiments, the isolated DC / DC converter 2112 includes a third H-bridge converter, a transformer T, and a fourth H-bridge converter connected in sequence; wherein the primary winding and secondary winding of the transformer T are respectively connected to the AC side of the third H-bridge converter and the fourth H-bridge converter, and the DC input side of the third H-bridge converter and the DC output side of the fourth H-bridge converter are respectively connected to the first H-bridge converter 2111 and the second H-bridge converter 2113.

[0031] In this embodiment, the third H-bridge converter includes four third switching transistors Q3 and a first bus capacitor C1. Every two third switching transistors Q3 are connected in series to form a bridge arm. Two bridge arms are connected in parallel, with their two ends serving as the DC input side of the third H-bridge converter, and the midpoint of the two bridge arms serving as the AC side. The first bus capacitor C1 is connected between the DC input sides of the third H-bridge converter. The fourth H-bridge converter includes four fourth switching transistors Q4 and a second bus capacitor C2. Every two fourth switching transistors Q4 are connected in series to form a bridge arm. Two bridge arms are connected in parallel, with their two ends serving as the DC output side of the fourth H-bridge converter, and the midpoint of the two bridge arms serving as the AC side. The second bus capacitor C2 is connected between the DC output sides of the fourth H-bridge converter. Preferably, the second bus capacitor C2 may include a thin-film capacitor or a supercapacitor. In this embodiment, the third H-bridge converter converts the DC voltage into a high-frequency AC square wave or quasi-sine wave, and achieves electrical isolation and voltage transformation through the transformer T. Then, the fourth H-bridge converter efficiently converts the high-frequency AC power from the secondary side of the transformer T back to DC power through synchronous rectification technology. The two H-bridges work together with the transformer T to achieve bidirectional operation and have electrical isolation function.

[0032] As described above, in this embodiment, the first H-bridge converters 2111 of the three power modules in each power module group 21 of the DC power supply are cascaded to form the AC input terminal of the power module group 21. The AC input terminals of the three power module groups 21 constitute the three-phase AC input terminal of the power module array 20. Furthermore, the second H-bridge converters 2113 of the three power modules in each power module group 21 are cascaded to form a set of DC output terminals of the power module group 21. The DC output terminals of the three power module groups 21 constitute the three sets of DC output terminals of the power module array 20, which are respectively connected through… Three second reactors L2 are connected in parallel and connected to the load. It can be seen that the input and output sides of the power modules in the power module array 20 are cascaded, which can realize the direct connection between the DC power supply and the power grid without the need for a power frequency inverter for isolation and voltage reduction, thus reducing the size of the power supply. Furthermore, electrical isolation can be further achieved through the isolated DC / DC converter 2112, and voltage transformation can also be realized. Combined with the cascaded and parallel connection of the output side of the power modules in the power module array 20, high voltage and high current combined output can also be realized to meet the requirements of high voltage and high current DC power supply.

[0033] Reference Figure 4 , Figure 4This is a schematic diagram of the specific structure of the second embodiment of the DC power supply of this utility model. The difference between this embodiment and the first embodiment is that the DC output terminal of the DC power supply in this embodiment is also connected in parallel with a bypass circuit 50, and the load is the TF coil of the magnetic confinement device in the tokamak apparatus. The rest of the structure is the same or similar. In this embodiment, the bypass circuit 50 includes a resistor R1 and a thyristor D connected in series. In the event of an abnormal situation, the rapid conduction of the thyristor D, combined with the energy dissipation effect of the resistor R1, enables rapid demagnetization of the TF coil, ensuring the safe operation of the power supply.

[0034] Reference Figure 5 , Figure 5 This is a schematic diagram of the specific structure of the third embodiment of the DC power supply of this utility model. The difference between this embodiment and the second embodiment is that each power module group 21 in this embodiment contains six power modules, N=2, while the rest of the structure is the same or similar. In this embodiment, each power module group 21 includes six power modules. The input sides of the six power modules are cascaded to form the AC input terminal of the power module group 21. The output sides of every three power modules are cascaded to form one set of DC output terminals of the power module group 21. Therefore, the power module group 21 has two sets of DC output terminals. The AC input terminals of the three power module groups 21 are respectively connected to the power grid through three first reactors L1. The six sets of DC output terminals of the three power module groups 21 are respectively connected in parallel through six second reactors L2 and connected to the load. This embodiment can also achieve direct connection between the DC power supply and the power grid, reducing the size of the power supply, and can achieve a combination of high voltage and high current output, meeting the requirements of high voltage and high current DC power supply.

[0035] Reference Figure 6 and Figure 7 , Figure 6 and Figure 7This paper presents a fourth embodiment of the DC power supply of this utility model. The difference between this embodiment and the first embodiment lies in the specific circuit structure of the isolated DC / DC converter 2112; the remaining structures are the same or similar. In this embodiment, the isolated DC / DC converter 2112 includes a first half-bridge converter, a resonant circuit 2112B, a transformer T, and a second half-bridge converter connected in sequence. The DC input side of the first half-bridge converter is connected to the first H-bridge converter 2111, the AC side of the first half-bridge converter is connected to the primary winding of the transformer T via the resonant circuit 2112B, the secondary winding of the transformer T is connected to the AC side of the second half-bridge converter, and the DC output side of the second half-bridge converter is connected to the second H-bridge converter 2113. Specifically, the resonant circuit 2112B is an LC resonant circuit. The first half-bridge converter includes two first switching transistors Q1 and a third bus capacitor C3. The two first switching transistors Q1 are connected in series to form a bridge arm. The two ends of the bridge arm serve as the DC input side of the first half-bridge converter, and the midpoint of the bridge arm serves as the AC side of the first half-bridge converter. The third bus capacitor C3 is connected between the two ends of the bridge arm. The second half-bridge converter includes two second switching transistors Q2 and a fourth bus capacitor C4. The two second switching transistors Q2 are connected in series to form a bridge arm. The two ends of the bridge arm serve as the DC output side of the second half-bridge converter, and the midpoint of the bridge arm serves as the AC side of the second half-bridge converter. The fourth bus capacitor C4 is connected between the two ends of the bridge arm. This embodiment can also realize the direct connection between the DC power supply and the power grid, reduce the size of the power supply, and realize the combined output of high voltage and high current, meeting the requirements of high voltage and high current DC power supply.

[0036] Reference Figure 8 , Figure 8 This is a schematic diagram of the specific structure of the fifth embodiment of the DC power supply of this utility model. The difference between this embodiment and the fourth embodiment is that the DC output terminal of the DC power supply in this embodiment is further connected in parallel with a bypass circuit 50, and the load is the TF coil of the magnetic confinement device in the tokamak apparatus. The remaining structures are the same or similar. In this embodiment, the bypass circuit 50 includes a resistor R1 and a thyristor D connected in series. In the event of an abnormal situation, the rapid conduction of the thyristor D, combined with the energy dissipation effect of the resistor R1, enables rapid demagnetization of the TF coil, ensuring the safe operation of the power supply.

[0037] Reference Figure 9 , Figure 9This is a schematic diagram of the specific structure of the sixth embodiment of the DC power supply of this utility model. The difference between this embodiment and the fourth embodiment is that the DC output terminal of the DC power supply in this embodiment is also connected in parallel with an output capacitor C, and each power module group 21 contains six power modules, N=2, with the remaining structures being the same or similar. In this embodiment, each power module group 21 includes six power modules. The input sides of the six power modules are cascaded to form the AC input terminal of the power module group 21, and the output sides of every three power modules are cascaded to form a set of DC output terminals of the power module group 21. Therefore, the power module group 21 has two sets of DC output terminals. The AC input terminals of the three power module groups 21 are respectively connected to the power grid through three first reactors L1, and the six sets of DC output terminals of the three power module groups 21 are respectively connected in parallel through six second reactors L2 and connected to the load. In this embodiment, the direct connection between the DC power supply and the power grid can also be achieved, reducing the size of the power supply, and enabling a combination of high voltage and high current output to meet the requirements of high voltage and high current DC power supply.

[0038] The above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this utility model, and should all be included within the protection scope of this utility model.

Claims

1. A DC power supply, characterized in that, The DC power supply includes: an input reactor unit, a power module array, and an output reactor unit, wherein... The power module array includes three power module groups, each power module group includes several power modules, and the input sides of the several power modules are cascaded to form the AC input terminal of the power module group. The power module group has N DC output terminals, each DC output terminal is formed by cascading the output sides of at least two power modules. The AC input terminals of the three power module groups are respectively connected to the power grid through the input reactor unit, and the DC output terminals of the three power module groups are connected to the load after being connected in parallel through the output reactor unit, where N is an integer not less than 1.

2. The DC power supply as described in claim 1, characterized in that, The DC power supply also includes a soft-start unit, which is connected between the input reactor unit and the power grid.

3. The DC power supply as described in claim 2, characterized in that, The soft-start unit includes three soft-start circuits connected in parallel between the three-phase output of the power grid and the input reactor unit. Each soft-start circuit includes a first switch, a second switch, and a current-limiting resistor. The first switch and the current-limiting resistor are connected in series and then connected in parallel with the second switch between the input reactor unit and the power grid.

4. The DC power supply as described in claim 1 or 2, characterized in that, The power module includes a first H-bridge converter, a second H-bridge converter, and an isolated DC / DC converter connected between the first H-bridge converter and the second H-bridge converter; wherein, the first H-bridge converters in a plurality of power modules of each power module group are cascaded to form the AC input terminal of each power module group; and the second H-bridge converters in at least two power modules of each power module group are cascaded to form one set of DC output terminals of each power module group.

5. The DC power supply as described in claim 4, characterized in that, The isolated DC / DC converter includes a third H-bridge converter, a transformer, and a fourth H-bridge converter connected in sequence; wherein the primary winding and secondary winding of the transformer are respectively connected to the AC side of the third H-bridge converter and the fourth H-bridge converter, and the DC input side of the third H-bridge converter and the DC output side of the fourth H-bridge converter are respectively connected to the first H-bridge converter and the second H-bridge converter.

6. The DC power supply as described in claim 5, characterized in that, The third H-bridge converter includes four third switches and a first bus capacitor. Every two third switches are connected in series to form a bridge arm. After two bridge arms are connected in parallel, their two ends serve as the DC input side of the third H-bridge converter, and the midpoint of the two bridge arms serves as the AC side of the third H-bridge converter. The first bus capacitor is connected between the DC input sides of the third H-bridge converter. The fourth H-bridge converter includes four fourth switches and a second bus capacitor. Every two fourth switches are connected in series to form a bridge arm. After two bridge arms are connected in parallel, their two ends serve as the DC output side of the fourth H-bridge converter, and the midpoint of the two bridge arms serves as the AC side of the fourth H-bridge converter. The second bus capacitor is connected between the DC output sides of the fourth H-bridge converter.

7. The DC power supply as described in claim 4, characterized in that, The isolated DC / DC converter includes a first half-bridge converter, a resonant circuit, a transformer, and a second half-bridge converter connected in sequence; wherein, the DC input side of the first half-bridge converter is connected to the first H-bridge converter, the AC side of the first half-bridge converter is connected to the primary winding of the transformer via the resonant circuit, the secondary winding of the transformer is connected to the AC side of the second half-bridge converter, and the DC output side of the second half-bridge converter is connected to the second H-bridge converter.

8. The DC power supply as described in claim 7, characterized in that, The first half-bridge converter includes two first switching transistors and a third bus capacitor. The two first switching transistors are connected in series to form a bridge arm. The two ends of the bridge arm serve as the DC input side of the first half-bridge converter, and the midpoint of the bridge arm serves as the AC side of the first half-bridge converter. The third bus capacitor is connected between the two ends of the bridge arm. The second half-bridge converter includes two second switching transistors and a fourth bus capacitor. The two second switching transistors are connected in series to form a bridge arm. The two ends of the bridge arm serve as the DC output side of the second half-bridge converter, and the midpoint of the bridge arm serves as the AC side of the second half-bridge converter. The fourth bus capacitor is connected between the two ends of the bridge arm.

9. The DC power supply as described in claim 1 or 2, characterized in that, The DC output terminal of the DC power supply is also connected in parallel with a bypass circuit, which includes a resistor and a thyristor connected in series; and / or, the DC output terminal of the DC power supply is also connected in parallel with an output capacitor.

10. The DC power supply as claimed in claim 1, characterized in that, Each power module group includes three power modules. The input sides of the three power modules are cascaded to form the AC input terminal of the power module group, and the output sides of the three power modules are cascaded to form a set of DC output terminals of the power module group. The AC input terminals of the three power module groups are respectively connected to the power grid through the input reactor unit, and the DC output terminals of the three power module groups are connected to the load after being connected in parallel through the output reactor unit.

Images