Full-bridge negative pressure hybrid DC circuit breaker and control method thereof

Abstract

The present application discloses a full-bridge negative pressure hybrid DC circuit breaker and a control method thereof, which relate to the field of power electronics technology. The full-bridge negative pressure hybrid DC circuit breaker comprises a flow branch and a disconnecting branch; wherein the flow branch comprises at least one fast mechanical switch connected in series; the disconnecting branch comprises an active full-bridge negative pressure device and a solid-state power electronic switch connected in series with each other; the active full-bridge negative pressure device is used to transfer current from the flow branch to the disconnecting branch; the solid-state power electronic switch is used for current breaking and energy dissipation. Compared with the prior art, the present application can improve the overall integration, reliability and maintainability of the circuit breaker through modularized and redundant active full-bridge negative pressure sub-modules.

Description

Technical Field

[0001] The invention belongs to the technical field of power electronics, and in particular relates to a full-bridge negative-pressure hybrid DC circuit breaker and a control method thereof. Background Art

[0002] With the development of DC transmission technology, DC circuit breakers have received widespread attention as important system protection equipment. Compared with AC systems, the current in DC systems does not have a natural zero-crossing point, and the arc cannot be extinguished after the break is formed, so the realization of DC breaking is more difficult. The main problem facing the current research on DC circuit breakers is how to improve their breaking speed and reduce overall losses. Therefore, in order to take into account both rapidity and low losses, hybrid DC circuit breakers are currently the most effective technical approach for DC breaking in DC transmission systems.

[0003] Patents CN102687221B, CN103972855B, and CN103280763B respectively proposed hybrid DC circuit breakers based on auxiliary power electronic switches for current transfer. The long-term conduction of current by the auxiliary power electronic switches increases the operating losses of the DC circuit breakers and requires the installation of heat dissipation devices.

[0004] Patent CN105024369B proposes a current transfer device for a hybrid DC circuit breaker, which can realize reliable current transfer and has the advantage of low operating loss. However, the current device needs to be equipped with a high-voltage and high-power charging power supply and a large-capacity coupling transformer, and the overall integration is poor and the redundancy is low. Summary of the invention

[0005] The purpose of the present invention is to propose a full-bridge negative pressure hybrid DC circuit breaker, which achieves high overall integration, reliability and maintainability through modular and redundant active full-bridge negative pressure sub-modules, while also having the advantages of low loss, fast opening speed, and easy reclosing.

[0006] The structural features of the present invention and its advantages will become apparent from the following detailed description, or may be learned in part through the practice of the present invention.

[0007] According to one aspect of the present invention, a full-bridge negative pressure hybrid DC circuit breaker is proposed, comprising a through-current branch and a disconnecting branch. The through-current branch comprises at least one fast mechanical switch connected in series; the disconnecting branch comprises an active full-bridge negative pressure device and a solid-state power electronic switch connected in series with each other; the active full-bridge negative pressure device is used to transfer current from the through-current branch to the disconnecting branch; the solid-state power electronic switch is used for current interruption and energy dissipation.

[0008] According to some embodiments, the active full-bridge negative pressure device includes: at least one active full-bridge negative pressure submodule connected in series, the active full-bridge negative pressure submodule includes: a charging power supply, an energy storage capacitor, a resonant inductor, a freewheeling diode, a bypass switch, a first end, a second end and four power semiconductor switching devices, every two of the power semiconductor switching devices are connected in series in the same direction to form a first bridge arm and a second bridge arm, the first bridge arm and the second bridge arm are connected in parallel in the same direction to form a full-bridge structure, the charging power supply, the energy storage capacitor and the freewheeling diode are connected in parallel with each other, the cathode of the freewheeling diode points to the positive electrode of the charging power supply, one end of the resonant inductor is connected to the energy storage capacitor, the other end of the resonant inductor is connected to the top of the upper bridge arm of the first bridge arm, the negative electrode of the charging power supply is connected to the bottom of the lower bridge arm of the full-bridge structure, the midpoint of the first bridge arm is connected to the first end, the midpoint of the second bridge arm is connected to the second end, and the bypass switch is connected between the midpoint of the first bridge arm and the midpoint of the second bridge arm; or

[0009] At least one active full-bridge negative pressure submodule connected in series, the active full-bridge negative pressure submodule comprising: a charging power supply, an energy storage capacitor, a resonant inductor, a bypass switch, a first end, a second end and four power semiconductor switch devices, wherein every two of the power semiconductor switch devices are connected in series in the same direction to form a first bridge arm and a second bridge arm, the first bridge arm and the second bridge arm are connected in parallel in the same direction to form a full-bridge structure, the full-bridge structure, the charging power supply and the energy storage capacitor are connected in parallel with each other, the midpoint of the first bridge arm is connected to one end of the resonant inductor, the midpoint of the second bridge arm is connected to the second end, the other end of the resonant inductor is connected to the first end, and the bypass switch is connected between the midpoint of the second bridge arm and the first end; or

[0010] A resonant inductor and at least one active full-bridge negative pressure submodule connected in series, the resonant inductor and the active full-bridge negative pressure submodule connected in series are connected in series with each other, the active full-bridge negative pressure submodule comprises a charging power supply, an energy storage capacitor, a bypass switch, a first end, a second end and four power semiconductor switching devices, every two of the power semiconductor switching devices are connected in series in the same direction to form a first bridge arm and a second bridge arm, the first bridge arm, the second bridge arm, the charging power supply and the energy storage capacitor are connected in parallel with each other, the first bridge arm and the second bridge arm form a full-bridge structure, the midpoint of the first bridge arm is connected to the first end, the midpoint of the second bridge arm is connected to the second end, and the bypass switch is connected between the midpoint of the first bridge arm and the midpoint of the second bridge arm.

[0011] According to some embodiments, the solid-state power electronic switch includes: a bidirectional power electronic switch; a nonlinear resistor; and the bidirectional power electronic switch is connected in parallel with the nonlinear resistor.

[0012] According to some embodiments, the bidirectional power electronic switch comprises:

[0013] At least two power semiconductor switching devices connected in reverse series end to end; or

[0014] One or more full-bridge submodules connected in series; or

[0015] A first branch, a second branch and at least two power semiconductor switching devices, the first branch includes at least three diodes connected in reverse series in sequence, the second branch is connected in parallel with the first branch to form a first parallel end and a second parallel end, the second branch includes at least three diodes connected in reverse series in sequence, the first branch and the second branch have the same number of diodes and opposite polarities, and at least two power semiconductor switching devices, one end of which is connected to the connection point of two adjacent diodes in the first branch, and the other end of which is connected to the connection point of two corresponding adjacent diodes in the second branch.

[0016] According to some embodiments, the full-bridge submodule comprises:

[0017] Four power semiconductor switching devices, capacitors or nonlinear resistors, where every two of the power semiconductor switching devices are connected in series in the same direction to form two bridge arms respectively, the two bridge arms are connected in parallel to each other, the middle points of the two bridge arms are respectively used as connection ends, and the capacitors or nonlinear resistors are connected in parallel to the two bridge arms; or

[0018] Four power semiconductor switching devices, a capacitor and a diode, each two of the power semiconductor switching devices are connected in series to form two bridge arms, the two bridge arms are connected in parallel with each other in the same direction, the middle points of the two bridge arms are respectively used as connection ends, the capacitor and the diode are connected in series to form a branch, and the branch is connected in parallel with the two bridge arms; or

[0019] Four diodes and power semiconductor switching devices, where every two diodes are connected in series in the same direction to form two bridge arms respectively, the two bridge arms are connected in parallel with each other in the same direction, the middle points of the two bridge arms are respectively used as connection ends, and the power semiconductor switching device is connected in parallel with the two bridge arms; or

[0020] Two power semiconductor switching devices, a capacitor and two diodes, each of the diodes and the power semiconductor switching device are connected in series to form two identical bridge arms, the two identical bridge arms are connected in parallel with each other in the same direction, the midpoints of the two bridge arms are respectively used as connection ends, and the capacitor is connected in parallel with the two identical bridge arms; or

[0021] Two power semiconductor switching devices, a capacitor and two diodes, each of the diodes and the power semiconductor switching device are connected in reverse series to form two identical bridge arms, the two identical bridge arms are connected in reverse parallel to each other, the middle points of the two bridge arms are respectively used as connection ends, and the capacitor is connected in parallel to the two identical bridge arms; or

[0022] Four groups of diode series groups and one group of power semiconductor switch device series groups, each group of the diode series groups includes at least two diodes connected in series in the same direction, every two groups of the diode series groups are connected in series in the same direction to form two bridge arms respectively, the two bridge arms are connected in parallel with each other in the same direction, the middle points of the two bridge arms are respectively used as connection ends, the power semiconductor switch device series group is connected in parallel with the two bridge arms in the same direction, and the power semiconductor switch device series group includes at least two power semiconductor switch devices connected in series in the same direction.

[0023] According to some embodiments, the power semiconductor switch device includes one or more combinations of IGBT, IEGT, IGCT, and MOSFET.

[0024] According to some embodiments, the working state of the active full-bridge negative pressure device includes an on state, an engaged state, and a fault state;

[0025] In the on state, the upper bridge arms or the lower bridge arms of the full-bridge structure of the active full-bridge negative pressure submodule of the active full-bridge negative pressure device are turned on at the same time, and the bypass switch is in the off state;

[0026] In the input state, the bypass switch is in the disconnected state, the upper bridge arm of the first bridge arm of the active full-bridge negative pressure submodule of the active full-bridge negative pressure device is turned on, and the lower bridge arm of the second bridge arm is turned on; or

[0027] The upper bridge arm of the second bridge arm is turned on, and the lower bridge arm of the first bridge arm is turned on;

[0028] In the fault state, the upper bridge arm and the lower bridge arm of the full-bridge structure of the active full-bridge negative pressure submodule of the active full-bridge negative pressure device are both locked, and the bypass switch is in a closed state;

[0029] The active full-bridge negative pressure submodule in the conducting state and the input state automatically switches to the fault state after a fault occurs.

[0030] According to another aspect of the present invention, a control method for a full-bridge negative-voltage hybrid DC circuit breaker is proposed, the method comprising: the full-bridge negative-voltage hybrid DC circuit breaker as described in any one of the preceding items; and implementing an opening instruction and a closing instruction using the full-bridge negative-voltage hybrid DC circuit breaker.

[0031] When the full-bridge negative pressure hybrid DC circuit breaker is in the closed position, the fast mechanical switch of the current branch is in the on state, the solid-state power electronic switch is in the locked state, and the active full-bridge negative pressure device is in the on state. When receiving the opening command, the full-bridge negative pressure hybrid DC circuit breaker performs the following operations:

[0032] The first step is to open the fast mechanical switch of the current-passing branch and turn on the solid-state power electronic switch;

[0033] The second step is to select the number of active negative pressure full-bridge sub-modules in the active full-bridge negative pressure device that are switched from the on state to the put-in state and the conduction mode in the put-in state according to the current direction when the fast mechanical switch reaches the insulation break position;

[0034] The third step is to lock the solid-state power electronic switch when the current of the fast mechanical switch of the current-carrying branch passes through zero and is turned off, so that the current starts to flow into the nonlinear resistor and gradually decreases to zero;

[0035] The fourth step is to switch the active negative pressure full-bridge sub-module in the active full-bridge negative pressure device that is in the on state to the on state, and the opening is completed.

[0036] According to some embodiments, when the full-bridge negative pressure hybrid DC circuit breaker is in an open position, the fast mechanical switch of the current-carrying branch is in an open state, the solid-state power electronic switch is in a locked state, and the active full-bridge negative pressure device is in a conducting state. When receiving the closing command, the full-bridge negative pressure hybrid DC circuit breaker performs the following operations:

[0037] The first step is to turn on the solid-state power electronic switch;

[0038] The second step is to close the fast mechanical switch of the current-carrying branch if it is not closed due to a fault, and after the fast mechanical switch is closed, lock the solid-state power electronic switch, and the closing is completed;

[0039] If a fault occurs, the solid-state power electronic switch is immediately locked, and the current begins to flow into the nonlinear resistor and gradually decreases to zero.

[0040] The technical solution provided by the present invention has the following beneficial effects:

[0041] According to the exemplary embodiment, the full-bridge negative pressure hybrid DC circuit breaker adopts modularized and redundant active full-bridge negative pressure submodules to realize reliable current transfer, and has high overall machine integration, reliability and maintainability;

[0042] According to the exemplary embodiment, the current-carrying branch of the full-bridge negative-pressure hybrid DC circuit breaker has only a fast mechanical switch and does not require a cooling device, so the operation loss is low and the economy is better;

[0043] According to an exemplary embodiment, a full-bridge negative-pressure hybrid DC circuit breaker has the advantages of fast breaking speed, bidirectional current interruption, and fast reclosing.

[0044] It is to be understood that the foregoing general description and the following detailed description are exemplary only and are not restrictive of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] The above and other objects, features and advantages of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings.

[0046] Figure 1 An embodiment of a full-bridge negative-voltage hybrid DC circuit breaker according to an exemplary embodiment of the present invention is shown.

[0047] Figure 2 A first embodiment of a full-bridge negative pressure device in a full-bridge negative pressure hybrid DC circuit breaker according to an exemplary embodiment of the present invention is shown.

[0048] Figure 3 A second embodiment of a full-bridge negative pressure device in a full-bridge negative pressure hybrid DC circuit breaker according to an exemplary embodiment of the present invention is shown.

[0049] Figure 4 A third embodiment of a full-bridge negative pressure device in a full-bridge negative pressure hybrid DC circuit breaker according to an exemplary embodiment of the present invention is shown.

[0050] Figure 5 A structural diagram of a solid-state power electronic switch in a full-bridge negative-voltage hybrid DC circuit breaker according to an exemplary embodiment of the present invention is shown.

[0051] Figure 6 A first embodiment of a bidirectional power electronic switch of a solid-state power electronic switch in a full-bridge negative-voltage hybrid DC circuit breaker according to an exemplary embodiment of the present invention is shown.

[0052] Figure 7 A second embodiment of a bidirectional power electronic switch of a solid-state power electronic switch in a full-bridge negative-voltage hybrid DC circuit breaker according to an exemplary embodiment of the present invention is shown.

[0053] Figure 8 A third embodiment of a bidirectional power electronic switch of a solid-state power electronic switch in a full-bridge negative-voltage hybrid DC circuit breaker according to an exemplary embodiment of the present invention is shown.

[0054] Fig. 9 A fourth embodiment of a bidirectional power electronic switch of a solid-state power electronic switch in a full-bridge negative-voltage hybrid DC circuit breaker according to an exemplary embodiment of the present invention is shown.

[0055] Fig.10A fifth embodiment of a bidirectional power electronic switch of a solid-state power electronic switch in a full-bridge negative-voltage hybrid DC circuit breaker according to an exemplary embodiment of the present invention is shown.

[0056] Fig.11 A sixth embodiment of a bidirectional power electronic switch of a solid-state power electronic switch in a full-bridge negative-voltage hybrid DC circuit breaker according to an exemplary embodiment of the present invention is shown.

[0057] Fig.12 A seventh embodiment of a bidirectional power electronic switch of a solid-state power electronic switch in a full-bridge negative-voltage hybrid DC circuit breaker according to an exemplary embodiment of the present invention is shown.

[0058] Fig.13 An eighth embodiment of a bidirectional power electronic switch of a solid-state power electronic switch in a full-bridge negative-voltage hybrid DC circuit breaker according to an exemplary embodiment of the present invention is shown.

[0059] Fig.14a , Fig.14b A flow chart of a control method in a full-bridge negative-pressure hybrid DC circuit breaker according to an exemplary embodiment of the present invention is shown. DETAILED DESCRIPTION

[0060] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that the present invention will be comprehensive and complete and fully convey the concept of the example embodiments to those skilled in the art.

[0061] The terms "first", "second", etc. in the specification and claims of the present invention and the above drawings are used to distinguish different objects rather than to describe a specific order. All descriptions of positional relationships are circuit connection relationships described according to circuit diagram design, not physical positional relationships.

[0062] Structures with the same code can represent structures of the same model or structures of different models with the same function. Different codes for structures with the same circuit symbols only serve to distinguish the location distribution, and their models can be the same or different.

[0063] Some conventional circuit components such as capacitors and diodes are not referred to in this article. The capacitors and diodes mentioned here only represent the same type of products, and their specific models and parameters may be the same or different. The same direction and reverse direction mentioned in this article are defined according to the direction of the thyristor or diode. The same in this article refers to the same circuit structure, and the device models may be different.

[0064] The technical solution of the present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0065] Fast DC circuit breakers are one of the key devices to ensure the safe, stable and reliable operation of DC transmission and distribution systems and DC power grids. Unlike AC systems, the current in DC systems does not have a natural zero-crossing point, and the arc cannot be extinguished after the break is formed. The main problems currently faced by research on DC circuit breakers are how to improve their breaking speed and reduce overall losses. Traditional hybrid DC circuit breakers include main current branches, transfer current branches and energy absorption branches. The current branches often need to be equipped with heat dissipation auxiliary equipment, which has large operating losses and high costs; the transfer current branches need to be equipped with high-voltage and high-power charging power supplies and large-capacity coupling transformers, and the overall integration is poor and the redundancy is low.

[0066] Therefore, the present invention proposes a modular and redundant active full-bridge negative pressure submodule to achieve high whole machine integration, reliability and maintainability, while having the advantages of low loss, fast opening speed, and convenient reclosing. The use of multiple power semiconductor switch devices in the disconnecting branch can increase the withstand voltage value, expand its application range, reduce the current stress of each device, and extend the service life of each device.

[0067] Figure 1 An embodiment of a full-bridge negative-voltage hybrid DC circuit breaker according to an exemplary embodiment of the present invention is shown.

[0068] See also Figure 1 The full-bridge negative-pressure hybrid DC circuit breaker of the exemplary embodiment includes a current-carrying branch 110 and a disconnecting branch 120 .

[0069] like Figure 1 As shown, the flow branch 110 includes at least one fast mechanical switch 1101 connected in series; the disconnecting branch 120 includes an active full-bridge negative pressure device 1202 and a solid-state power electronic switch 1201 connected in series with each other; the active full-bridge negative pressure device 1202 is used to transfer current from the flow branch 110 to the disconnecting branch 120; the solid-state power electronic switch 1201 is used for current interruption and energy dissipation.

[0070] According to some embodiments, the full-bridge negative-pressure hybrid DC circuit breaker is a bidirectional current circuit breaker, which can break currents from different directions.

[0071] According to some embodiments, the positional relationship between the active full-bridge negative pressure device 1202 and the solid-state power electronic switch 1201 connected in series may be as shown in the illustrated embodiment, and the positions may also be interchanged.

[0072] According to some embodiments, multiple fast mechanical switches 1101 are set in series to divide the voltage, reducing the loss of each fast mechanical switch 1101. The fast mechanical switch 1101 used is a mechanical switch with a fast operating mechanism, which can realize fast opening and closing of the switch. The flow branch 110 of the present invention only has at least one fast mechanical switch 1101 without the cooling device required by the traditional circuit breaker, so the operation loss is low and the economy is better.

[0073] Figure 2 A schematic diagram of a first embodiment of a full-bridge negative pressure device of a full-bridge negative pressure hybrid DC circuit breaker according to an exemplary embodiment of the present invention is shown.

[0074] like Figure 2 As shown, the active full-bridge negative pressure device 1202 can be designed as: at least one active full-bridge negative pressure submodule 12021 connected in series, the active full-bridge negative pressure submodule 12021 includes: a charging power supply, a storage capacitor C, a resonant inductor L, a freewheeling diode D, a bypass switch K, a first end A, a second end B and four power semiconductor switch devices (Q1, Q2, Q3, Q4), each two of the power semiconductor switch devices (Q1, Q2, Q3, Q4) are connected in series in the same direction to form a first bridge arm 01 and a second bridge arm 02, the first bridge arm 01 and the second bridge arm 02 are connected in parallel in the same direction to form a full-bridge structure, The charging power supply, the energy storage capacitor C and the freewheeling diode D are connected in parallel with each other, the cathode of the freewheeling diode D points to the positive electrode of the charging power supply, one end of the resonant inductor L is connected to the energy storage capacitor C, the other end of the resonant inductor L is connected to the top of the upper bridge arm of the first bridge arm 01, the negative electrode of the charging power supply is connected to the bottom of the lower bridge arm of the full bridge structure, the middle point of the first bridge arm 01 is connected to the first end A, the middle point of the second bridge arm 02 is connected to the second end B, and the bypass switch K is connected between the middle point of the first bridge arm 01 and the middle point of the second bridge arm 02. The middle point is located between the two power semiconductor switch devices of the same bridge arm. The freewheeling diode is used to clamp the capacitor voltage to avoid the generation of oscillation.

[0075] According to some embodiments, the power semiconductor switch devices (Q1, Q2, Q3, Q4) include one or more combinations of IGBT, IEGT, IGCT, and MOSFET. The power semiconductor devices used all carry reverse parallel diodes. The power semiconductor switch devices (Q1, Q2, Q3, Q4) can be oriented as shown in the figure or in the opposite direction, provided that each bridge arm is connected in series in the same direction and the two bridge arms are connected in parallel in the same direction.

[0076] Figure 3 A second embodiment of a full-bridge negative pressure device in a full-bridge negative pressure hybrid DC circuit breaker according to an exemplary embodiment of the present invention is shown.

[0077] like Figure 3 As shown, the active full-bridge negative pressure device 1202 can also be designed as: at least one active full-bridge negative pressure submodule 12022 connected in series, the active full-bridge negative pressure submodule 12022 includes: a charging power supply, an energy storage capacitor C, a resonant inductor L, a bypass switch K, a first end A, a second end B and four power semiconductor switch devices (Q1, Q2, Q3, Q4), every two of the power semiconductor switch devices (Q1, Q2, Q3, Q4) are connected in series in the same direction to form a first bridge arm 01 and a second bridge arm 02, the first bridge arm 01 and the second bridge arm 02 are connected in parallel in the same direction to form a full-bridge structure, the full-bridge structure, the charging power supply and the energy storage capacitor C are connected in parallel to each other, the middle point of the first bridge arm 01 is connected to one end of the resonant inductor L, the middle point of the second bridge arm 02 is connected to the second end B, the other end of the resonant inductor L is connected to the first end A, and the bypass switch K is connected between the middle point of the second bridge arm 02 and the first end A. The middle point is located between two power semiconductor switch devices in the same bridge arm.

[0078] According to some embodiments, the power semiconductor switch devices (Q1, Q2, Q3, Q4) include one or more combinations of IGBT, IEGT, IGCT, and MOSFET. The power semiconductor devices used all carry reverse parallel diodes. The power semiconductor switch devices (Q1, Q2, Q3, Q4) can be oriented as shown in the figure or in the opposite direction, provided that each bridge arm is connected in series in the same direction and the two bridge arms are connected in parallel in the same direction.

[0079] Figure 4 A third embodiment of a full-bridge negative pressure device in a full-bridge negative pressure hybrid DC circuit breaker according to an exemplary embodiment of the present invention is shown.

[0080] like Figure 4As shown, the active full-bridge negative pressure device 1202 can also be designed as: including: a resonant inductor L and at least one active full-bridge negative pressure submodule 12023 connected in series, the resonant inductor L and the active full-bridge negative pressure submodule 12023 connected in series are connected in series with each other, the active full-bridge negative pressure submodule 12023 includes a charging power supply, an energy storage capacitor C, a bypass switch K, a first end A, a second end B and four power semiconductor switch devices (Q1, Q2, Q3, Q4), the power semiconductor switch devices (Q1, Q2, Q3, Q4) are connected in series in the same direction to form a first bridge arm 01 and a second bridge arm 02. The first bridge arm 01, the second bridge arm 02, the charging power supply and the energy storage capacitor C are connected in parallel with each other. The first bridge arm 01 and the second bridge arm 02 form a full bridge structure. The middle point of the first bridge arm 01 is connected to the first end A, the middle point of the second bridge arm 02 is connected to the second end B, and the bypass switch K is connected between the middle point of the first bridge arm 01 and the middle point of the second bridge arm 02. The middle point is located between two power semiconductor switch devices in the same bridge arm.

[0081] According to some embodiments, the resonant inductor L is a total inductance shared by each active full-bridge negative voltage sub-module 12023 , and thus the resonant inductor L may be disposed between each active full-bridge negative voltage sub-module 12023 .

[0082] According to some embodiments, the power semiconductor switch devices (Q1, Q2, Q3, Q4) include one or more combinations of IGBT, IEGT, IGCT, and MOSFET. The power semiconductor devices used all carry reverse parallel diodes. The power semiconductor switch devices (Q1, Q2, Q3, Q4) can be oriented as shown in the figure or in the opposite direction, provided that each bridge arm is connected in series in the same direction and the two bridge arms are connected in parallel in the same direction.

[0083] like Figure 2 , Figure 3 , Figure 4 As shown, according to some embodiments, the resonant inductor L and the energy storage capacitor C are used to form a resonant circuit to transfer the current from the flow branch 110 to the disconnect branch 120. The specific working process is described in the following description of the control method.

[0084] like Figure 2 , Figure 3 , Figure 4 As shown, according to some embodiments, multiple active full-bridge negative pressure sub-modules are provided, and a modular and redundant design mode is adopted to reduce the stress of each device inside each module.

[0085] According to some embodiments, the working state of the active full-bridge negative pressure device 1202 includes a conducting state, an input state, and a fault state;

[0086] In the on state, the upper bridge arms of the full-bridge structure of the active full-bridge negative pressure submodule of the active full-bridge negative pressure device 1202 are turned on at the same time (i.e., Q1 and Q3 are turned on at the same time) or the lower bridge arms are turned on at the same time (i.e., Q2 and Q4 are turned on at the same time), and the bypass switch K is in the off state;

[0087] In the input state, the bypass switch K is in the disconnected state, the upper bridge arm of the first bridge arm 01 of the active full-bridge negative pressure submodule of the active full-bridge negative pressure device 1202 is turned on (i.e., Q1 is turned on), and the lower bridge of the second bridge arm 02 is turned on (i.e., Q4 is turned on); or

[0088] The upper bridge arm of the second bridge arm 02 is turned on (i.e., Q3 is turned on), and the lower bridge arm of the first bridge arm 01 is turned on (i.e., Q2 is turned on);

[0089] In the fault state, the upper bridge arm and the lower bridge arm of the full-bridge structure of the active full-bridge negative pressure submodule of the active full-bridge negative pressure device 1202 are both locked (that is, Q1, Q2, Q3, and Q4 are all locked), and the bypass switch K is in a closed state;

[0090] The active full-bridge negative pressure submodule in the conducting state and the input state automatically switches to the fault state after a fault occurs.

[0091] According to some embodiments, in a fault state, the bypass switch K is closed so that the current flows directly through the faulty active full-bridge negative pressure sub-module without passing through it. Therefore, when a certain active full-bridge negative pressure sub-module fails, other active full-bridge negative pressure sub-modules can continue to work, reflecting the advantages of modular design.

[0092] Figure 5 A structural diagram of a solid-state power electronic switch in a full-bridge negative-voltage hybrid DC circuit breaker according to an exemplary embodiment of the present invention is shown.

[0093] like Figure 5 As shown, according to some embodiments, the solid-state power electronic switch 1201 includes: a bidirectional power electronic switch 1201A; a nonlinear resistor 1201B; the bidirectional power electronic switch 1201A is connected in parallel with the nonlinear resistor 1201B.

[0094] According to some embodiments, the nonlinear resistor 1201B may be an energy-consuming device such as a lightning arrester, which consumes current, and the number of the nonlinear resistor 1201B may be one or more. The nonlinear resistor 1201B may be connected in parallel with the bidirectional power electronic switch as a whole, or may be connected in parallel with the following full-bridge submodules.

[0095] Figure 6 A first embodiment of a bidirectional power electronic switch of a solid-state power electronic switch in a full-bridge negative-voltage hybrid DC circuit breaker according to an exemplary embodiment of the present invention is shown.

[0096] like Figure 6 As shown, the bidirectional power electronic switch includes: at least two power semiconductor switch devices Q connected in series in reverse order. That is, as shown in the embodiment of the figure, there are four power semiconductor switch devices Q connected in series, but the number is not limited to times. The number of power semiconductor switch devices Q connected in forward direction and the power semiconductor switch devices Q connected in reverse direction are equal and symmetrically distributed, which plays the role of conducting and blocking bidirectional current. The positions of the power semiconductor switch devices Q connected in forward direction and the power semiconductor switch devices Q connected in reverse direction can be as shown in the figure, or they can be swapped as a whole.

[0097] The power semiconductor switch device can be any one or more of IGBT, IGCT, IEGT, MOSFET, etc. or other structures that can realize the switching function. In addition, in order to suppress the overvoltage at both ends, a buffer circuit such as C, RC, RCD, lightning arrester, etc. can also be connected in parallel in engineering applications.

[0098] Figure 7 A second embodiment of a bidirectional power electronic switch of a solid-state power electronic switch in a full-bridge negative-voltage hybrid DC circuit breaker according to an exemplary embodiment of the present invention is shown.

[0099] Figure 8 A third embodiment of a bidirectional power electronic switch of a solid-state power electronic switch in a full-bridge negative-voltage hybrid DC circuit breaker according to an exemplary embodiment of the present invention is shown.

[0100] like Figure 7 , Figure 8 As shown, the bidirectional power electronic switch may also include one or more full-bridge submodules (12011, 12012) connected in series. The structure of the full-bridge submodule (12011, 12012) may be: four power semiconductor switch devices Q, capacitor C1 or nonlinear resistor R, each two of the power semiconductor switch devices Q are connected in series in the same direction to form two bridge arms respectively, the two bridge arms are connected in parallel to each other, the two bridge arms may be connected in parallel in the same direction or in reverse parallel, the middle points of the two bridge arms are respectively used as connection ends, and the middle points are located between the two devices of the same bridge arm. The capacitor C1 or nonlinear resistor R is connected in parallel to the two bridge arms. At least one full-bridge submodule (12011, 12012) is connected in series by connecting the connection ends to each other. The power semiconductor switch device Q may be oriented as shown in the legend or in the opposite direction, provided that the same bridge arm is connected in series in the same direction. The power semiconductor switch device may be one or more of IGBT, IGCT, IEGT, MOSFET, etc. The nonlinear resistor may be a lightning arrester as shown in the legend, but is not limited to it.

[0101] Fig. 9A fourth embodiment of a bidirectional power electronic switch of a solid-state power electronic switch in a full-bridge negative-voltage hybrid DC circuit breaker according to an exemplary embodiment of the present invention is shown.

[0102] like Fig. 9 As shown, the bidirectional power electronic switch may also include one or more full-bridge submodules (12013, 12014) connected in series. The structure of the full-bridge submodule (12013, 12014) may also be: four power semiconductor switch devices Q, capacitor C2 and diode D1, each two of the power semiconductor switch devices Q are connected in series to form two bridge arms respectively, the two bridge arms are connected in parallel in the same direction, the middle points of the two bridge arms are respectively used as connection ends, and the middle point is located between the two devices of the same bridge arm. The capacitor C2 and the diode D1 are connected in series to form a branch, and the branch is connected in parallel with the two bridge arms. The capacitor C2 and the diode D1 are connected in series in the same branch, but their position relationship and device installation direction can be set according to actual conditions. At least one full-bridge submodule (12013, 12014) is connected in series by connecting the connection ends. The power semiconductor switch device may be one or more of IGBT, IGCT, IEGT, MOSFET, etc. In actual engineering applications, parallel resistors may also be used at both ends of the diode and the capacitor to perform submodule static voltage balancing or discharge.

[0103] Fig.10 A fifth embodiment of a bidirectional power electronic switch of a solid-state power electronic switch in a full-bridge negative-voltage hybrid DC circuit breaker according to an exemplary embodiment of the present invention is shown.

[0104] like Fig.10 As shown, the bidirectional power electronic switch may also include one or more full-bridge submodules 12015 connected in series. The structure of the full-bridge submodule 12015 may also be: four diodes D2, a power semiconductor switch device Q, each two diodes D2 are connected in series in the same direction to form two bridge arms, and the direction of the diode D2 is the same as the direction of the anti-parallel diode of the power semiconductor switch device Q. The two bridge arms are connected in parallel with each other in the same direction, and the middle points of the two bridge arms are respectively used as connection ends, and the middle points are located between the two devices of the same bridge arm. The power semiconductor switch device Q is connected in parallel with the two bridge arms. At least one full-bridge submodule 12015 is connected in series by connecting the connection ends to each other. The power semiconductor switch device may be one or more of IGBT, IGCT, IEGT, MOSFET, etc. In order to suppress the overvoltage at both ends of the power semiconductor switch device, a buffer circuit such as C, RC, RCD, lightning arrester, etc. may also be connected in parallel. Under the premise of meeting the above conditions, the power semiconductor device Q and the diode D2 may be designed in reverse directions as shown in the figure.

[0105] Fig.11A sixth embodiment of a bidirectional power electronic switch of a solid-state power electronic switch in a full-bridge negative-voltage hybrid DC circuit breaker according to an exemplary embodiment of the present invention is shown.

[0106] like Fig.11 As shown, according to some embodiments, the bidirectional power electronic switch may further include one or more full-bridge submodules (12016, 12017) connected in series. The structure of the full-bridge submodule (12016, 12017) may also be: two power semiconductor switch devices Q, a capacitor C3 and two diodes D3, each of the diodes D3 and the power semiconductor switch device Q are connected in series to form two identical bridge arms, the two identical bridge arms are connected in parallel in the same direction, the middle points of the two bridge arms are respectively used as connection ends, and the middle points are located between the two devices of the same bridge arm. The capacitor C3 is connected in parallel with the two identical bridge arms. At least one full-bridge submodule (12016, 12017) is connected in series by connecting the connection ends to each other. The power semiconductor switch device may be one or more of IGBT, IGCT, IEGT, MOSFET, etc.

[0107] like Figure 7 , Figure 8 , Fig. 9 , Fig.11 As shown, according to some embodiments, the capacitor, nonlinear resistor, and capacitor diode branches connected in parallel with the two bridge arms act to form a buffer voltage-equalizing branch, which can reduce the large voltage impact of the fault current when passing through the switch unit, achieve soft shutdown of the switch unit, extend the service life of the switch, and improve the reliability of the circuit.

[0108] Fig.12 A seventh embodiment of a bidirectional power electronic switch of a solid-state power electronic switch in a full-bridge negative-voltage hybrid DC circuit breaker according to an exemplary embodiment of the present invention is shown.

[0109] like Fig.12As shown, the bidirectional power electronic switch may also include one or more full-bridge submodules 12019 connected in series. The structure of the full-bridge submodule 12019 may also be: four groups of diode series groups D4 and one group of power semiconductor switch device series group Q5, each group of the diode series group D4 includes at least two diodes connected in series in the same direction, and each two groups of the diode series groups D4 are connected in series in the same direction to form two bridge arms, respectively, and the two bridge arms are connected in parallel in the same direction, and the middle points of the two bridge arms are respectively used as connection ends, and the middle points are located between the two diode series groups D4 of the same bridge arm. The power semiconductor switch device series group Q5 is connected in parallel with the two bridge arms in the same direction, and the same direction parallel connection here means that the anti-parallel diode of the power semiconductor switch device is in the same direction as the diode connected in series with the bridge arm. The power semiconductor switch device series group Q5 includes at least two power semiconductor switch devices connected in series in the same direction. At least one full-bridge submodule 12019 is connected in series by connecting the connection ends to each other. The power semiconductor switch device may be one or more of IGBT, IGCT, IEGT, MOSFET, etc. In order to suppress overvoltage at both ends of the power semiconductor switch device, a buffer circuit such as C, RC, RCD, lightning arrester, etc. can also be connected in parallel. In order to suppress overvoltage at both ends of the diode, a buffer circuit such as C, RC, etc. can also be connected in parallel. Under the premise of meeting the above conditions, the power semiconductor device Q and the diode D2 can be designed in reverse direction as shown in the figure.

[0110] Fig.13 An eighth embodiment of a bidirectional power electronic switch of a solid-state power electronic switch in a full-bridge negative-voltage hybrid DC circuit breaker according to an exemplary embodiment of the present invention is shown.

[0111] like Fig.13 As shown, the bidirectional power electronic switch structure can also be: a first branch 001, a second branch 002 and at least two power semiconductor switching devices, the first branch 001 includes at least three diodes connected in reverse series in sequence, the second branch 002 is connected in parallel with the first branch 001 to form a first parallel terminal O1 and a second parallel terminal O2, the second branch 002 includes at least three diodes connected in reverse series in sequence, the first branch 001 and the second branch 002 have the same number of diodes and opposite polarities, and at least two power semiconductor switching devices, one end of which is connected to the connection point of two adjacent diodes in the first branch 001, and the other end is connected to the connection point of two corresponding adjacent diodes in the second branch 002.

[0112] For example, Fig.13As shown, from O1 to O2, the diodes in the first branch 001 are respectively recorded as A1, A2, Ai..., A5, and the diodes in the second branch 002 are respectively recorded as B1, B2, Bi...B5. The anode of A1 and the cathode of B1 are connected to O1, and the cathode of A5 and the anode of B5 are connected to O2. One end of the power semiconductor switch device is connected to the connection point of two adjacent diodes Ai and Ai+1 in the first branch 001, and the other end is connected to the connection point of two corresponding adjacent diodes Bi and Bi+1 in the second branch 002. Fig.13 As shown in , the direction of the power semiconductor switch device Q6 is from the cathode of the diode A1 in the first branch 001 to the anode of the diode B1 in the second branch 002; the direction of the power semiconductor switch device Q7 is from the cathode of the diode B2 in the second branch 002 to the anode of the diode A2 in the first branch 001. The direction of the power semiconductor switch device referred to here is the current flow direction of the transistor part, which enables the current to flow in the circuit in an S shape during operation, and the power semiconductor switch device Q8 and the power semiconductor switch device Q9 are connected by analogy. The power semiconductor switch device can be an IGBT, IGCT, IEGT, MOSFET, etc. In addition, in order to suppress the overvoltage at both ends of the power semiconductor switch device, a buffer circuit such as C, RC, RCD, lightning arrester, etc. can also be connected in parallel. The number of power semiconductor switch devices can be as shown in the legend, but is not limited to times.

[0113] According to some embodiments, multiple power semiconductor switch devices connected in series can increase the withstand voltage and expand the application range. Among them, the power semiconductor switch device can cut off several times of its own current and is suitable for large current segmentation occasions. It can also be replaced by other switch devices or switch device combinations with the same function.

[0114] According to some embodiments, the structural types of each full-bridge submodule connected in series may be the same or different, that is, several full-bridge submodules in the embodiments may be combined in series to form a bidirectional power electronic switch.

[0115] It should be noted that the illustrated embodiments only propose a part of the design possibilities, that is, the circuit structure is not limited thereto. The illustrated embodiments are only circuit structures designed according to the principles of various circuit components, and the parameters and models of the circuit components involved above are designed according to actual engineering conditions.

[0116] Fig.14a , Fig.14b A flow chart of a control method in a full-bridge negative-pressure hybrid DC circuit breaker according to an exemplary embodiment of the present invention is shown.

[0117] See also Fig.14a , Fig.14bThe control method of the full-bridge negative pressure hybrid DC circuit breaker is used to control the full-bridge negative pressure hybrid DC circuit breaker to realize the opening instruction and the closing instruction.

[0118] like Fig.14a As shown, in S11, when the full-bridge negative pressure hybrid DC circuit breaker is closed, the fast mechanical switch of the current branch is in the on state, the solid-state power electronic switch is in the locked state, and the active full-bridge negative pressure device is in the on state. When receiving the opening instruction, the full-bridge negative pressure hybrid DC circuit breaker performs the following operations:

[0119] In step S12, the first step is to open the fast mechanical switch of the current-passing branch and turn on the solid-state power electronic switch;

[0120] In step S13, when the fast mechanical switch reaches the insulation break position, the number of active negative pressure full-bridge sub-modules in the active full-bridge negative pressure device that are switched from the on state to the put-in state and the conduction mode in the put-in state are selected according to the current direction;

[0121] In step S14, the third step, when the current of the fast mechanical switch of the current-carrying branch passes through zero and is turned off, the solid-state power electronic switch is locked, and the current begins to flow into the nonlinear resistor and gradually decreases to zero;

[0122] In S15, the fourth step, the active negative pressure full-bridge sub-module in the active full-bridge negative pressure device that is in the on state is switched to the on state, and the opening is completed.

[0123] According to some embodiments, multiple single-stage circuit breaker modules can be selected and assembled in series according to the voltage level requirements of the system, so as to achieve the task of adapting to different voltage level requirements. The energy storage capacitor and the resonant inductor form an oscillation circuit, forcing the current to transfer to the on-off branch, and the energy storage capacitor C discharges. The direction of the discharge current is opposite to the direction of the current in the on-current branch, so that the current of the fast mechanical switch is rapidly reduced until the current passes through zero, thereby achieving the purpose of disconnection. Multiple active full-bridge negative pressure submodules work simultaneously, which can realize reliable current transfer and have high overall integration, reliability and maintainability.

[0124] The present invention adopts a modular design. During operation, multiple active full-bridge negative pressure sub-modules and multiple full-bridge sub-modules work simultaneously, which effectively reduces the loss of a single device while improving work efficiency and fast breaking speed.

[0125] like Fig.14bAs shown, in S21, when the full-bridge negative pressure hybrid DC circuit breaker is in the open position, the fast mechanical switch of the current branch is in the open state, the solid-state power electronic switch is in the locked state, and the active full-bridge negative pressure device is in the on state. When receiving the closing command, the full-bridge negative pressure hybrid DC circuit breaker performs the following operations:

[0126] In S22, in the first step, the solid-state power electronic switch is turned on;

[0127] In step S23, if the fault is not closed, the fast mechanical switch of the current-carrying branch is closed, and after the fast mechanical switch is closed, the solid-state power electronic switch is locked, and the closing is completed;

[0128] If a fault occurs, the solid-state power electronic switch is immediately locked, and the current begins to flow into the nonlinear resistor and gradually decreases to zero. The reclosing procedure is simple and safe, and fast reclosing can be achieved.

[0129] The above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Although technicians in this field make various modifications or changes with reference to the above embodiments after reading this application, these modifications or changes are all within the scope of protection claimed in the application for the present invention to be approved.

Claims

1. A full-bridge negative pressure hybrid DC circuit breaker, comprising a flow branch and a disconnecting branch, characterized in that: The through-current branch includes at least one fast mechanical switch connected in series; The disconnecting branch includes an active full-bridge negative pressure device and a solid-state power electronic switch connected in series with each other; The active full-bridge negative pressure device is used to transfer current from the current-carrying branch to the disconnecting branch; The solid-state power electronic switch is used for current interruption and energy dissipation; Wherein, the active full-bridge negative pressure device comprises: At least one active full-bridge negative pressure submodule connected in series, the active full-bridge negative pressure submodule comprising: a charging power supply, an energy storage capacitor, a resonant inductor, a freewheeling diode, a bypass switch, a first end, a second end and four power semiconductor switch devices, wherein every two of the power semiconductor switch devices are connected in series in the same direction to form a first bridge arm and a second bridge arm, the first bridge arm and the second bridge arm are connected in parallel in the same direction to form a full-bridge structure, the charging power supply, the energy storage capacitor and the freewheeling diode are connected in parallel with each other, the cathode of the freewheeling diode points to the positive electrode of the charging power supply, one end of the resonant inductor is connected to the energy storage capacitor, the other end of the resonant inductor is connected to the top of the upper bridge arm of the full-bridge structure, the negative electrode of the charging power supply is connected to the bottom of the lower bridge arm of the full-bridge structure, the middle point of the first bridge arm is connected to the first end, the middle point of the second bridge arm is connected to the second end, and the bypass switch is connected between the middle point of the first bridge arm and the middle point of the second bridge arm; or At least one active full-bridge negative pressure submodule connected in series, the active full-bridge negative pressure submodule comprising: a charging power supply, an energy storage capacitor, a resonant inductor, a bypass switch, a first end, a second end and four power semiconductor switch devices, wherein every two of the power semiconductor switch devices are connected in series in the same direction to form a first bridge arm and a second bridge arm, the first bridge arm and the second bridge arm are connected in parallel in the same direction to form a full-bridge structure, the full-bridge structure, the charging power supply and the energy storage capacitor are connected in parallel with each other, the midpoint of the first bridge arm is connected to one end of the resonant inductor, the midpoint of the second bridge arm is connected to the second end, the other end of the resonant inductor is connected to the first end, and the bypass switch is connected between the midpoint of the second bridge arm and the first end; or A resonant inductor and at least one active full-bridge negative pressure submodule connected in series, the resonant inductor and the active full-bridge negative pressure submodule connected in series are connected in series with each other, the active full-bridge negative pressure submodule comprises a charging power supply, an energy storage capacitor, a bypass switch, a first end, a second end and four power semiconductor switching devices, every two of the power semiconductor switching devices are connected in series in the same direction to form a first bridge arm and a second bridge arm, the first bridge arm, the second bridge arm, the charging power supply and the energy storage capacitor are connected in parallel with each other, the first bridge arm and the second bridge arm form a full-bridge structure, the midpoint of the first bridge arm is connected to the first end, the midpoint of the second bridge arm is connected to the second end, and the bypass switch is connected between the midpoint of the first bridge arm and the midpoint of the second bridge arm.

2. The full-bridge negative pressure hybrid DC circuit breaker according to claim 1, characterized in that: The solid-state power electronic switch comprises: Bidirectional power electronic switch; Non-linear resistor; The bidirectional power electronic switch is connected in parallel with the nonlinear resistor.

3. The full-bridge negative pressure hybrid DC circuit breaker according to claim 2, characterized in that: The bidirectional power electronic switch comprises: At least two power semiconductor switching devices connected in reverse series end to end; or One or more full-bridge submodules connected in series; or A first branch, a second branch and at least two power semiconductor switching devices, the first branch includes at least three diodes connected in reverse series in sequence, the second branch is connected in parallel with the first branch to form a first parallel end and a second parallel end, the second branch includes at least three diodes connected in reverse series in sequence, the first branch and the second branch have the same number of diodes and opposite polarities, and at least two power semiconductor switching devices, one end of which is connected to the connection point of two adjacent diodes in the first branch, and the other end of which is connected to the connection point of two corresponding adjacent diodes in the second branch.

4. The full-bridge negative pressure hybrid DC circuit breaker according to claim 3, characterized in that: The full-bridge submodule comprises: Four power semiconductor switching devices, capacitors or nonlinear resistors, where every two of the power semiconductor switching devices are connected in series in the same direction to form two bridge arms respectively, the two bridge arms are connected in parallel to each other, the middle points of the two bridge arms are respectively used as connection ends, and the capacitors or nonlinear resistors are connected in parallel to the two bridge arms; or Four power semiconductor switching devices, a capacitor and a diode, each two of the power semiconductor switching devices are connected in series to form two bridge arms, the two bridge arms are connected in parallel with each other in the same direction, the middle points of the two bridge arms are respectively used as connection ends, the capacitor and the diode are connected in series to form a branch, and the branch is connected in parallel with the two bridge arms; or Four diodes and power semiconductor switching devices, where every two diodes are connected in series in the same direction to form two bridge arms respectively, the two bridge arms are connected in parallel with each other in the same direction, the middle points of the two bridge arms are respectively used as connection ends, and the power semiconductor switching device is connected in parallel with the two bridge arms; or Two power semiconductor switching devices, a capacitor and two diodes, each of the diodes and the power semiconductor switching device are connected in series to form two identical bridge arms, the two identical bridge arms are connected in parallel with each other in the same direction, the midpoints of the two bridge arms are respectively used as connection ends, and the capacitor is connected in parallel with the two identical bridge arms; or Two power semiconductor switching devices, a capacitor and two diodes, each of the diodes and the power semiconductor switching device are connected in reverse series to form two identical bridge arms, the two identical bridge arms are connected in reverse parallel to each other, the middle points of the two bridge arms are respectively used as connection ends, and the capacitor is connected in parallel to the two identical bridge arms; or Four groups of diode series groups and one group of power semiconductor switch device series groups, each group of the diode series groups includes at least two diodes connected in series in the same direction, every two groups of the diode series groups are connected in series in the same direction to form two bridge arms respectively, the two bridge arms are connected in parallel with each other in the same direction, the middle points of the two bridge arms are respectively used as connection ends, the power semiconductor switch device series group is connected in parallel with the two bridge arms in the same direction, and the power semiconductor switch device series group includes at least two power semiconductor switch devices connected in series in the same direction.

5. The full-bridge negative pressure hybrid DC circuit breaker according to claim 4, characterized in that: The power semiconductor switch device includes one or more combinations of IGBT, IEGT, IGCT and MOSFET.

6. The full-bridge negative pressure hybrid DC circuit breaker according to claim 1, characterized in that: The working states of the active full-bridge negative pressure device include an on state, an engaged state and a fault state; In the on state, the upper bridge arms or the lower bridge arms of the full-bridge structure of the active full-bridge negative pressure submodule of the active full-bridge negative pressure device are turned on at the same time, and the bypass switch is in the off state; In the input state, the bypass switch is in the disconnected state, the upper bridge arm of the first bridge arm of the active full-bridge negative pressure submodule of the active full-bridge negative pressure device is turned on, and the lower bridge arm of the second bridge arm is turned on; or The upper bridge arm of the second bridge arm is turned on, and the lower bridge arm of the first bridge arm is turned on; In the fault state, the upper bridge arm and the lower bridge arm of the full-bridge structure of the active full-bridge negative pressure submodule of the active full-bridge negative pressure device are both locked, and the bypass switch is in a closed state; The active full-bridge negative pressure submodule in the conducting state and the input state automatically switches to the fault state after a fault occurs.

7. A control method for a full-bridge negative pressure hybrid DC circuit breaker, characterized in that: The method comprises: By the full-bridge negative pressure hybrid DC circuit breaker according to any one of claims 1-6; The full-bridge negative pressure hybrid DC circuit breaker is used to implement the opening command and the closing command; When the full-bridge negative pressure hybrid DC circuit breaker is in the closed position, the fast mechanical switch of the current branch is in the on state, the solid-state power electronic switch is in the locked state, and the active full-bridge negative pressure device is in the on state. When receiving the opening command, the full-bridge negative pressure hybrid DC circuit breaker performs the following operations: The first step is to open the fast mechanical switch of the current-passing branch and turn on the solid-state power electronic switch; The second step is to select the number of active negative pressure full-bridge sub-modules in the active full-bridge negative pressure device that are switched from the on state to the put-in state and the conduction mode in the put-in state according to the current direction when the fast mechanical switch reaches the insulation break position; The third step is to lock the solid-state power electronic switch when the current of the fast mechanical switch of the current-carrying branch passes through zero and is turned off, so that the current starts to flow into the nonlinear resistor and gradually decreases to zero; The fourth step is to switch the active negative pressure full-bridge sub-module in the active full-bridge negative pressure device that is in the on state to the on state, and the opening is completed.

8. The control method of the full-bridge negative pressure hybrid DC circuit breaker according to claim 7, characterized in that: When the full-bridge negative pressure hybrid DC circuit breaker is in an open position, the fast mechanical switch of the current branch is in an open state, the solid-state power electronic switch is in a locked state, and the active full-bridge negative pressure device is in a conducting state. When receiving the closing command, the full-bridge negative pressure hybrid DC circuit breaker performs the following operations: The first step is to turn on the solid-state power electronic switch; The second step is to close the fast mechanical switch of the current-carrying branch if it is not closed due to a fault, and after the fast mechanical switch is closed, lock the solid-state power electronic switch, and the closing is completed; If a fault occurs, the solid-state power electronic switch is immediately locked, and the current begins to flow into the nonlinear resistor and gradually decreases to zero.

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