Bidirectional DC circuit breaker

Abstract

The invention discloses a bidirectional direct current circuit breaker which comprises an electronic branch assembly, a voltage limiting branch assembly and an energy consumption branch assembly. The electronic branch assembly is used for transferring current; the voltage limiting branch assembly is electrically connected with the electronic branch assembly in parallel so as to reduce the turn-off overvoltage of the circuit breaker; and the energy consumption branch assembly is electrically connected with the electronic branch assembly in parallel so as to be used for absorbing the energy of the circuit. According to the hybrid DC circuit breaker, the current transfer function of the hybrid DC circuit breaker can be realized through the electronic branch assembly, the voltage limiting branch assembly and the energy consumption branch assembly. Compared with a bidirectional direct-current circuit breaker based on a power electronic device in the related technology, the bidirectional direct-current circuit breaker is compact in structure, low in connection inductance and high in universality, and functional units can be configured. The problems that in the related technology, connection is complex, redesign is needed under different working conditions, and functional units are inconvenient to adjust are solved.

Description

Technical Field

[0001] This invention relates to the field of circuit breaker technology, and more specifically to a bidirectional DC circuit breaker based on power electronic devices. Background Technology

[0002] With the rapid development of DC power systems such as rail transit, clean energy DC microgrids, and long-distance high-voltage DC transmission systems, DC circuit breakers, as devices capable of limiting and interrupting fault current and isolating faults in a short time, are crucial for the safe operation and protection of DC systems. Circuit breakers based on power electronic devices are divided into two types: solid-state circuit breakers and hybrid DC circuit breakers. Solid-state circuit breakers have no electric arc during interruption and a fast breaking speed, but they have high on-state losses. Hybrid DC circuit breakers combine the advantages of mechanical and solid-state types. During normal operation, the mechanical switch carries current for a long time with low on-state losses, while power electronic devices are used to achieve rapid shutdown during faults.

[0003] DC systems do not have a natural zero-crossing point for current and have low line impedance. When a short-circuit fault occurs, the current rise rate can reach thousands of amperes per millisecond. There is also a large amount of energy in the line inductance that needs to be released. This requires the circuit breaker to be able to turn off quickly and to have the ability to break up large currents and dissipate energy.

[0004] Currently, bidirectional DC circuit breakers based on power electronic devices in related technologies generally have complex structures, are directly connected using ordinary copper busbars, are difficult to configure with different functions, and often require structural redesign for different operating conditions. Therefore, there is a need to design a bidirectional DC circuit breaker that is compact, versatile, has configurable functional units, and low connection inductance. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a bidirectional DC circuit breaker that is compact, versatile, has configurable functional units, low connection inductance, and can interrupt large currents, in order to address the shortcomings of existing DC circuit breakers, such as complex structure, inability to configure functional units, and poor versatility.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0007] A bidirectional DC circuit breaker includes: an electronic branch assembly, a voltage limiting branch assembly, and an energy dissipation branch assembly; the electronic branch assembly is used to transfer current; the voltage limiting branch assembly is connected in parallel with the electronic branch assembly to reduce the circuit breaker's overvoltage during turn-off; the energy dissipation branch assembly is connected in parallel with the electronic branch assembly to absorb energy from the line.

[0008] As a further improvement of the present invention, the electronic branch assembly includes an electronic branch and a press-fit assembly disposed on the electronic branch; the press-fit assembly includes a plurality of press-fit IGBT devices and a plurality of diodes, as well as a press-fit structure for press-fitting and a copper busbar for leading out four electrical connection ports; the on / off state of the electronic branch is controlled by controlling the opening and closing of the press-fit IGBT devices.

[0009] As a further improvement of the present invention, the press-fit IGBT device and the diode adopt a diode bridge structure; the copper busbar, the press-fit IGBT device, and the diode are press-fitted together in the press-fit assembly for leading out the electrodes of the press-fit IGBT device and the diode.

[0010] As a further improvement of the present invention, it also includes a low-inductance busbar, which is electrically connected to the press-fit assembly, the pressure-limiting branch assembly, and the energy-consuming branch assembly.

[0011] As a further improvement of the present invention, the voltage limiting branch assembly includes a voltage limiting branch and an absorption capacitor, a first MOV, and an absorption resistor disposed on the voltage limiting branch; the absorption capacitor and the first MOV are connected in series through a low-inductance busbar to reduce the circuit breaker overvoltage during turn-off; the absorption resistor and the absorption capacitor are connected in parallel through a cable to release the voltage on the absorption capacitor.

[0012] As a further improvement of the present invention, the energy-consuming branch assembly includes an energy-consuming branch and a second MOV disposed on the energy-consuming branch, with multiple second MOVs connected in parallel.

[0013] As a further improvement of the present invention, the absorption capacitor, the first MOV and the second MOV all adopt a single-ended output structure and are connected by a low-inductance busbar. The internal busbar of the low-inductance busbar has a stacked structure, and each layer of busbar is separated by an insulating material.

[0014] As a further improvement of the present invention, the press-fit IGBT device adopts a common-electrode parallel structure.

[0015] As a further improvement of the present invention, an epoxy plate is used for the transition between the press-fit IGBT device and the diode.

[0016] As a further improvement of the present invention, the press-fit assembly adopts a single-string press-fit structure and has lead-out interfaces on all four sides to realize the free assembly of the required functional units.

[0017] Compared with the prior art, the advantages of the present invention are as follows:

[0018] The bidirectional DC circuit breaker of this invention achieves its current transfer function as a hybrid DC circuit breaker by connecting a voltage-limiting branch assembly and an electronic branch assembly in parallel. This is done by using the voltage-limiting branch assembly to reduce the circuit breaker's overvoltage during turn-off, and by connecting the energy-dissipating branch assembly and the electronic branch assembly in parallel, using the energy-dissipating branch assembly to absorb energy during short circuits. Compared to related bidirectional DC circuit breakers based on power electronic devices, the bidirectional DC circuit breaker of this invention has a compact structure, low connection inductance, high versatility, and configurable functional units, avoiding the problems of complex connections, the need for redesign under different operating conditions, and the inconvenience of adjusting functional units in related technologies. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the main structural principle of the bidirectional DC circuit breaker in a specific embodiment of the present invention;

[0020] Figure 2 This is a top view schematic diagram of the bidirectional DC circuit breaker in a specific embodiment of the present invention;

[0021] Figure 3 This is a schematic diagram of the left-side structure of a bidirectional DC circuit breaker in a specific embodiment of the present invention;

[0022] Figure 4 This is a schematic diagram of the three-dimensional structure of a bidirectional DC circuit breaker in a specific embodiment of the present invention;

[0023] Figure 5 This is a schematic diagram of the structural principle of the busbar in a specific embodiment of the present invention;

[0024] Figure 6 This is a diagram of the main circuit topology of a bidirectional DC circuit breaker in a specific embodiment of the present invention;

[0025] Legend: 1. Electronic branch assembly; 11. Electronic branch; 12. Press-fit assembly; 121. Press-fit IGBT device; 122. Diode; 123. Press-fit structural component; 124. Copper busbar; 2. Voltage limiting branch assembly; 21. Voltage limiting branch; 22. Absorption capacitor; 23. First MOV; 24. Absorption resistor; 3. Energy dissipation branch assembly; 31. Energy dissipation branch; 32. Second MOV; 4. Low inductance busbar. Detailed Implementation

[0026] The present invention will be further described below with reference to the accompanying drawings and specific preferred embodiments, but this does not limit the scope of protection of the present invention.

[0027] In the description of this invention, it should be understood that the terms "side", "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0028] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more unless otherwise explicitly specified.

[0029] Example

[0030] like Figures 1 to 6 As shown, the bidirectional DC circuit breaker of the present invention includes: an electronic branch assembly 1, a voltage-limiting branch assembly 2, and an energy-dissipating branch assembly 3. The electronic branch assembly 1 is used for current transfer; the voltage-limiting branch assembly 2 is connected in parallel with the electronic branch assembly 1 and is used to reduce the circuit breaker's overvoltage during turn-off; the energy-dissipating branch assembly 3 is connected in parallel with the electronic branch assembly 1 and is used to absorb energy during short circuits in the line. In this embodiment, the current transfer function of the hybrid DC circuit breaker can be achieved through the electronic branch assembly 1, the voltage-limiting branch assembly 2, and the energy-dissipating branch assembly 3. Compared with bidirectional DC circuit breakers based on power electronic devices in related technologies, the bidirectional DC circuit breaker of this embodiment has a compact structure, low connection inductance, high versatility, and configurable functional units, avoiding the problems of complex connections, the need for redesign under different operating conditions, and inconvenience in adjusting functional units in related technologies.

[0031] The bidirectional DC circuit breaker in this embodiment adopts a compact, modular design, with electronic branch assembly 1 as the main body. On two of the interfaces of this assembly, voltage limiting branch assembly 2 and energy dissipation branch assembly 3 are respectively connected. The third interface is used for internal electrical connection of electronic branch assembly 1. The whole is easy to install and maintain, has a high degree of design freedom and a compact structure.

[0032] like Figure 2 , Figure 3 , Figure 4 and Figure 6As shown, the electronic branch assembly 1 includes an electronic branch 11 and a press-fit assembly 12 disposed on the electronic branch 11. The press-fit assembly 12 includes multiple press-fit IGBT devices 121 and multiple diodes 122, as well as a press-fit structure 123 for press-fitting and a copper busbar 124 for leading out four electrical connection ports. The on / off state of the electronic branch 11 is controlled by controlling the opening and closing of the press-fit IGBT devices 121.

[0033] Furthermore, the press-fit IGBT device 121 and diode 122 adopt a diode bridge structure, with copper busbar 124 connecting each press-fit IGBT device 121. This busbar serves both to fix and lead out the electrodes, reducing the number of press-fit IGBT devices 121 and lowering costs. The copper busbar 124, along with the press-fit IGBT devices 121 and diodes 122, is pressed together in the press-fit assembly 12 for leading out the electrodes of the press-fit IGBT devices 121 and diodes 122. It is understood that in other embodiments, the press-fit IGBT devices 121 and diodes 122 can also use other circuit topologies, as long as they meet the requirements of the circuit breaker.

[0034] like Figure 5 As shown, this embodiment also includes a low-inductance busbar 4. The low-inductance busbar 4 is electrically connected to the press-fit assembly 12, the voltage limiting branch assembly 2, and the energy dissipation branch assembly 3 to ensure that the inductance on each transfer circuit is minimized and to reduce the overvoltage generated when the press-fit IGBT device 121 is disconnected.

[0035] like Figure 1 and Figure 6 As shown, the voltage limiting branch assembly 2 includes a voltage limiting branch 21 and an absorption capacitor 22, a first MOV 23, and an absorption resistor 24 disposed on the voltage limiting branch 21. The absorption capacitor 22 and the first MOV 23 are connected in series via a low-inductance busbar 4 to reduce the circuit breaker tripping overvoltage. The absorption resistor 24 is connected in parallel with the absorption capacitor 22 via a cable to release the voltage on the absorption capacitor 22.

[0036] like Figure 1 and Figure 6 As shown, the energy-consuming branch assembly 3 includes an energy-consuming branch 31 and a second MOV 32 disposed on the energy-consuming branch 31, with multiple second MOVs 32 connected in parallel. In this embodiment, by arranging the positions of the four second MOVs 32 with the electrode interfaces, the stray inductances of the four second MOVs 32 in the converter circuit are made to be basically consistent, which effectively ensures the current sharing.

[0037] In this embodiment, the absorption capacitor 22, the first MOV 23, and the second MOV 32 all adopt a single-ended outgoing line structure design and are connected using a low-inductance busbar 4. The internal busbars of the low-inductance busbar 4 have a stacked structure, and each layer of busbars is separated by insulating material, minimizing the connection loop area, thereby significantly reducing stray inductance in the circuit, and also reducing the turn-off overvoltage of the transfer branch.

[0038] Furthermore, the absorption capacitor 22 is directly opposite the first MOV 23 and connected in series through the low-inductance busbar 4. This structure makes full use of the height space of the press-fit assembly 12 and minimizes the distance between the press-fit assembly 1 and the voltage limiting branch assembly 2. Since the absorption resistor 24 does not need to consider stray inductance and is directly connected using a cable, the placement of the absorption resistor 24 has a high degree of freedom.

[0039] In this embodiment, the press-fit IGBT device 121 adopts a common-electrode parallel structure, with the electrode surfaces in direct contact, minimizing the difference in electrode inductance. This connection method has excellent current sharing and low drive voltage difference. The two collector-lead copper busbars 124 of the press-fit IGBT device 121 are specially designed as mirror-symmetrical structures to maintain consistent stray inductance. The mutual inductance is controlled by the remaining copper busbars and the current flow direction. The current sharing after parallel connection can reach over 99%. This embodiment uses a high-current-rated press-fit IGBT device 121, and by configuring the drive parameters, the turn-off current can reach tens of kiloamperes.

[0040] In this embodiment, a thick epoxy plate is used as a transition between the press-fit IGBT device 121 and the diode 122, so that the pressure on the press-fit IGBT device 121 is more uniform.

[0041] In this embodiment, the press-fit assembly 12 adopts a single-string press-fit structure. This structure has a small overall size and interfaces on all four sides, allowing for free assembly of required functional units. It meets different functional configurations while facilitating installation and maintenance. The distance between each functional unit and the press-fit assembly 12 is also minimized. The press-fit assembly 12 employs a highly compatible design, capable of accommodating different models of press-fit IGBT devices 121 and diodes 122 to meet various operating conditions, thus exhibiting high versatility. Furthermore, the press-fit structure 123 of the press-fit assembly 12 has threaded holes for installing lifting rings, facilitating handling.

[0042] In this embodiment, the external interface used is the positive terminal of the absorption capacitor 22 and the negative terminal of the second MOV32. In practice, there are many external interfaces that can be used, including the positive and negative terminals of the diode bridge in the press-fit assembly 12, the negative terminal of the first MOV23, etc. The position of the interface used can be adjusted according to actual needs.

[0043] In this embodiment, the bidirectional DC circuit breaker uses a diode bridge structure for the pressure-fit IGBT device 121 and diode 122 in the electronic branch assembly 1. This structure is used for the opening and closing of the line current, and it also has the advantages of bidirectional current carrying and low cost. The voltage limiting branch assembly 2 uses an absorption capacitor 22 with a capacitance value determined according to the line parameters and other parameters, and a first MOV 23 to limit the overvoltage of the branch to a safe range. The energy dissipation branch assembly 3 uses a second MOV 32 with sufficient energy to absorb the energy on the line, and it also has the function of limiting the overvoltage of the branch.

[0044] The working principle of this invention is as follows: After the press-fit IGBT device 121 in the electronic branch assembly 1 is turned on under control, the current on the circuit breaker flows through the electronic branch assembly 1. After the press-fit IGBT device 121 is turned off, an overvoltage will be generated on the branch. This overvoltage will first rise to the operating voltage of the first MOV23 in the voltage limiting branch assembly 2. The first MOV23 conducts, and the current is transferred to the voltage limiting branch assembly 2. At the same time, the overvoltage continues to rise until it reaches the operating voltage of the second MOV32 in the energy dissipation branch assembly 3. The second MOV32 conducts, and all the current is transferred to the energy dissipation branch assembly 3. The first MOV2 returns to the blocking state, and the second MOV32 begins to consume the energy in the line. After the energy consumption is completed, the second MOV32 returns to the blocking state, and the function of the entire circuit breaker is completed. The bidirectional DC circuit breaker of the present invention has the ability to interrupt large currents. It uses high voltage and current level press-fit IGBT devices 121. By configuring the drive parameters, only two devices connected in parallel can interrupt currents of tens of kiloamperes, avoiding multiple devices connected in series and parallel, effectively improving current sharing and reducing turn-off overvoltage.

[0045] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A bidirectional DC circuit breaker, characterized by It comprises: An electronic branch component (1), a voltage limiting branch component (2) and an energy consumption branch component (3); the electronic branch component (1) is used for diverting current; the voltage limiting branch component (2) is electrically connected in parallel with the electronic branch component (1) to reduce the circuit breaker closing overvoltage; and the energy consumption branch component (3) is electrically connected in parallel with the electronic branch component (1) to absorb the energy of the circuit.

2. The bidirectional DC circuit breaker according to claim 1, characterized in that The electronic branch component (1) comprises an electronic branch (11) and a press-pack component (12) arranged on the electronic branch (11); the press-pack component (12) comprises a plurality of press-pack IGBT devices (121) and a plurality of diodes (122), and a press-pack structure (123) for press-pack, and a copper bar (124) for leading out four-way electrical connection ports; the on-off of the electronic branch (11) is controlled by controlling the opening and closing of the press-pack IGBT devices (121).

3. The bidirectional DC circuit breaker according to claim 2, characterized in that The press-pack IGBT devices (121) and the diodes (122) adopt a diode bridge structure; the copper bar (124) is press-packaged with the press-pack IGBT devices (121) and the diodes (122) in the press-pack component (12) to lead out the electrodes of the press-pack IGBT devices (121) and the diodes (122).

4. The bidirectional DC circuit breaker according to claim 2, characterized in that It also comprises a low-inductance bus bar (4) electrically connected with the press-pack component (12), the voltage limiting branch component (2) and the energy consumption branch component (3).

5. The bidirectional DC circuit breaker according to claim 4, characterized in that The voltage limiting branch component (2) comprises a voltage limiting branch (21) and an absorption capacitor (22), a first MOV (23) and an absorption resistor (24) arranged on the voltage limiting branch (21); the absorption capacitor (22) and the first MOV (23) are connected in series through the low-inductance bus bar (4) to reduce the circuit breaker closing overvoltage; and the absorption resistor (24) and the absorption capacitor (22) are connected in parallel through a cable to release the voltage on the absorption capacitor (22).

6. The bidirectional DC circuit breaker according to claim 5, characterized in that The energy consumption branch component (3) comprises an energy consumption branch (31) and a plurality of second MOVs (32) arranged on the energy consumption branch (31).

7. The bidirectional DC circuit breaker according to claim 6, characterized in that The absorption capacitor (22), the first MOV (23) and the second MOV (32) all adopt a single-ended wire structure and are connected using a low-inductance bus bar (4); the internal bus bar of the low-inductance bus bar (4) is a laminated structure, and each layer of bus bar is separated by an insulating material.

8. The bidirectional DC circuit breaker according to any of claims 2 to 6, characterized in that The press-pack IGBT devices (121) adopt a common E pole parallel structure.

9. The bidirectional DC circuit breaker according to any of claims 2 to 6, characterized in that The press-pack IGBT devices (121) and the diodes (122) adopt an epoxy plate transition.

10. The bidirectional DC circuit breaker according to any of claims 2 to 6, characterized in that The press-pack component (12) adopts a single-string press-pack structure, and four sides are provided with leading-out interfaces to realize free assembly of required functional units.

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