Circuit breaker circuit based on graded energy consumption and voltage limiting and low-voltage solid-state direct-current circuit breaker

Abstract

The invention discloses a circuit breaker circuit and a low-voltage solid-state direct-current circuit breaker based on graded energy consumption and voltage limiting, and relates to the technical field of electronic circuits or other related fields, and the circuit breaker circuit comprises a main circuit switch which is used for controlling the on-off state of a main circuit in a target direct-current system; the primary energy consumption and voltage limiting branch is connected with the main path switch in parallel and is used for being switched on under the condition that the main path switch is switched off, consuming the electric energy of the system and being switched off under the condition that the main path current is reduced to a preset current threshold value; and the secondary energy-consumption voltage-limiting branch is connected in parallel with the primary energy-consumption voltage-limiting branch, and is used for being switched on under the condition that the primary energy-consumption voltage-limiting branch is switched from the switched-on state to the switched-off state, and is switched off under the condition that the electric energy of the system is consumed until the current of the main path is reduced to 0. The technical problem that a power electronic device used by a low-voltage direct-current solid-state circuit breaker in the prior art cannot cope with a voltage spike generated in the direct-current on-off process is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic circuits, and in particular to a circuit breaker circuit based on graded energy consumption and voltage limiting and a low-voltage solid-state DC circuit breaker. Background Art

[0002] The construction of new energy power generation can promote the clean and low-carbon transformation of energy, and the large-scale access of new energy to the power system has become one of the important development directions in the future. The DC grid has more advantages than the AC grid in the consumption and transmission of new energy, but due to the lack of current zero-crossing, the fault of the DC grid spreads very quickly and is difficult to disconnect. In order to ensure the safe and reliable operation of the DC system, DC circuit breakers with fault isolation and removal functions are indispensable.

[0003] In the prior art, low-voltage air-type mechanical DC circuit breakers based on arc extinguishing technology have problems such as long breaking time, arc erosion, and short life. Although low-voltage solid-state DC circuit breakers have the advantages of long life, no arcing, and fast shutdown, low-voltage solid-state DC circuit breakers are based on the breaking of power electronic devices. The ultra-high voltage spikes generated during the shutdown process have high requirements on the withstand voltage of power electronic devices, resulting in high cost of main switch devices and difficult selection.

[0004] To address the above-mentioned problems, no effective solution has been proposed yet. Summary of the invention

[0005] The embodiments of the present invention provide a circuit breaker circuit and a low-voltage solid-state DC circuit breaker based on graded energy consumption and voltage limiting, so as to at least solve the technical problem that the power electronic devices used in the low-voltage DC solid-state circuit breakers in the related art cannot cope with the voltage spikes generated during the DC breaking process.

[0006] According to one aspect of an embodiment of the present invention, a circuit breaker circuit based on hierarchical energy consumption and voltage limiting is provided, comprising: a main switch, used to control the on / off state of a main circuit in a target DC system; a primary energy consumption and voltage limiting branch, connected in parallel with the main switch, used to be turned on when the main switch is turned off, consuming system power until the main current drops to a preset current threshold, and then turned off; a secondary energy consumption and voltage limiting branch, connected in parallel with the primary energy consumption and voltage limiting branch, used to be turned on when the primary energy consumption and voltage limiting branch is switched from an on state to an off state, consuming system power until the main current drops to 0, and then turned off.

[0007] Furthermore, the circuit breaker circuit based on graded energy consumption and voltage limiting further includes: a first access end, wherein the first access end is configured as an incoming line end of the circuit breaker circuit.

[0008] Furthermore, the circuit breaker circuit based on graded energy consumption and voltage limiting further includes: a second access terminal, wherein the second access terminal is configured as an output terminal of the circuit breaker circuit.

[0009] Furthermore, the circuit breaker circuit based on graded energy consumption and voltage limiting also includes: a buffer branch connected in parallel with the main switch, which is used to absorb system electric energy generated by the switching action during the state switching of the main switch.

[0010] Furthermore, the buffer branch is configured as a series combination of a buffer resistor and a first buffer capacitor, wherein the first buffer capacitor is used to absorb the system power and provide a primary conduction voltage to the primary energy consumption and voltage limiting branch based on the system power.

[0011] Furthermore, the primary energy-consuming and voltage-limiting branch includes: a primary lightning arrester, wherein the primary lightning arrester is used to consume the system electric energy to reduce the main current when the main switch is turned off.

[0012] Furthermore, the primary energy consumption and voltage limiting branch also includes: a parallel combination of an auxiliary switch and a second buffer capacitor, wherein the second buffer capacitor is used to absorb system power in the primary energy consumption and voltage limiting branch, and provide a secondary conduction voltage to the secondary energy consumption and voltage limiting branch based on the system power.

[0013] Furthermore, the secondary energy-consuming and voltage-limiting branch includes: a secondary lightning arrester, wherein the secondary lightning arrester is used to consume the system electric energy to reduce the main current to 0 when the primary energy-consuming and voltage-limiting branch is switched from an on state to an off state.

[0014] Furthermore, the types of the secondary arrester include: metal oxide arrester, line type metal oxide arrester, gapless line type metal oxide arrester and fully insulated composite jacket metal oxide arrester.

[0015] According to another aspect of an embodiment of the present invention, a low-voltage solid-state DC circuit breaker is provided, comprising any one of the above-mentioned circuit breaker circuits based on graded energy consumption and voltage limiting.

[0016] The circuit breaker circuit based on hierarchical energy consumption and voltage limiting proposed in the present invention includes a primary energy consumption and voltage limiting branch and a secondary energy consumption and voltage limiting branch connected in parallel with the main switch. When the target DC system operates normally and stably, the two energy consumption and voltage limiting branches are kept in the cut-off state. If a fault occurs in the target DC system, after the main switch is cut off, the primary energy consumption and voltage limiting branch is turned on first, takes over the fault current and consumes system power until the fault current is initially reduced to a preset current threshold and then is turned off. The secondary energy consumption and voltage limiting branch that is turned on synchronously takes over the remaining fault current and further consumes system power until the fault current is reduced to 0, that is, the system fault is eliminated. Compared with the prior art, the present invention adopts a two-stage energy consumption and voltage limiting strategy. The primary energy consumption and voltage limiting branch first consumes energy under high current conditions to preliminarily reduce the fault current and complete the first disconnection. The secondary energy consumption and voltage limiting branch dissipates the residual energy caused by the fault under low current conditions until the fault is eliminated and the secondary disconnection is completed. The energy consumption time is extended as a whole, and the overvoltage in the two-stage energy consumption process is significantly reduced, thereby avoiding the influence of voltage spikes on power electronic devices, thereby solving the technical problem that the power electronic devices used in the low-voltage DC solid-state circuit breakers in the related technology cannot cope with the voltage spikes generated in the DC disconnection process. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0018] Figure 1 is a structural schematic diagram of an optional circuit breaker circuit based on hierarchical energy consumption and voltage limiting according to an embodiment of the present invention;

[0019] Figure 2 is a schematic diagram of circuit connection of a circuit breaker in an optional target DC system according to an embodiment of the present invention;

[0020] Figure 3 is a structural schematic diagram of another optional circuit breaker circuit based on hierarchical energy consumption and voltage limiting according to an embodiment of the present invention;

[0021] Figure 4 is a schematic structural diagram of an optional buffer branch according to an embodiment of the present invention;

[0022] Figure 5 is a schematic diagram of a topological structure of an optional energy consumption and voltage limiting module according to an embodiment of the present invention;

[0023] Figure 6 is a schematic diagram of an optional conventional solid-state circuit breaker circuit according to an embodiment of the present invention;

[0024] Figure 7is a schematic diagram of a current and voltage waveform of an optional breaking process based on a traditional solid-state circuit breaker circuit according to an embodiment of the present invention;

[0025] Figure 8 It is a schematic diagram of an optional low-voltage DC solid-state circuit breaker connected to a DC system based on hierarchical energy consumption and voltage limiting according to an embodiment of the present invention;

[0026] Fig. 9 is a schematic diagram of a current loop in an optional normal current flow scenario according to an embodiment of the present invention;

[0027] Fig.10 is a schematic diagram of a current loop in an optional short-circuit fault scenario according to an embodiment of the present invention;

[0028] Fig.11 is a schematic diagram of a current loop in another optional short-circuit fault scenario according to an embodiment of the present invention;

[0029] Fig.12 It is a schematic diagram of current and voltage waveforms during a breaking process of a low-voltage DC solid-state circuit breaker based on graded energy consumption and voltage limiting according to an embodiment of the present invention. DETAILED DESCRIPTION

[0030] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0031] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0032] The present invention is described in detail below in conjunction with various embodiments.

[0033] Embodiment 1

[0034] The present invention provides an embodiment of a circuit breaker circuit based on graded energy consumption and voltage limiting.

[0035] Figure 1 is a schematic structural diagram of an optional circuit breaker circuit based on hierarchical energy consumption and voltage limiting according to an embodiment of the present invention, such as Figure 1 As shown, the circuit breaker circuit includes:

[0036] The main circuit switch 101 is used to control the on / off state of the main circuit in the target DC system.

[0037] The primary energy-consuming voltage-limiting branch 102 is connected in parallel with the main switch 101 and is used to be turned on when the main switch 101 is turned off, consuming system power until the main current drops to a preset current threshold and then turned off.

[0038] The secondary energy consumption and voltage limiting branch 103 is connected in parallel with the primary energy consumption and voltage limiting branch 102, and is used to be turned on when the primary energy consumption and voltage limiting branch 102 switches from the on state to the off state, and consumes system power until the main current drops to 0, and then is turned off.

[0039] The circuit breaker circuit based on hierarchical energy consumption and voltage limiting proposed in the embodiment of the present invention includes a primary energy consumption and voltage limiting branch 102 and a secondary energy consumption and voltage limiting branch 103 connected in parallel with the main switch 101. When the target DC system operates normally and stably, the two energy consumption and voltage limiting branches are kept in an off state. If a fault occurs in the target DC system, after the main switch 101 is turned off, the primary energy consumption and voltage limiting branch 102 is turned on first, takes over the fault current and consumes system power until the fault current is initially reduced to a preset current threshold and then is turned off. The secondary energy consumption and voltage limiting branch 102 that is turned on synchronously takes over the remaining fault current and further consumes system power until the fault current is reduced to 0, that is, the system fault is eliminated.

[0040] Compared with the prior art, the present invention adopts a two-stage energy consumption and voltage limiting strategy. The primary energy consumption and voltage limiting branch first consumes energy under high current conditions to preliminarily reduce the fault current and complete the first disconnection. The secondary energy consumption and voltage limiting branch dissipates the residual energy caused by the fault under low current conditions until the fault is eliminated and the secondary disconnection is completed. The energy consumption time is extended as a whole, and the overvoltage in the two-stage energy consumption process is significantly reduced, thereby avoiding the influence of voltage spikes on power electronic devices, thereby solving the technical problem that the power electronic devices used in the low-voltage DC solid-state circuit breakers in the related technology cannot cope with the voltage spikes generated in the DC disconnection process.

[0041] In order to connect the circuit breaker circuit to the main circuit of the target DC system to achieve the effect of controlling the on and off of the main circuit, the circuit breaker circuit also includes: a first access end, wherein the first access end is configured as the incoming line end of the circuit breaker circuit; further, it also includes: a second access end, wherein the second access end is configured as the outgoing line end of the circuit breaker circuit.

[0042] Specifically, Figure 2 is a schematic diagram of a circuit breaker wiring in an optional target DC system according to an embodiment of the present invention, such as Figure 2 As shown, in Figure 1 On the basis shown, the circuit breaker circuit further includes: a first access terminal 201, configured as an incoming line terminal of the circuit breaker circuit; a second access terminal 202, configured as an outgoing line terminal of the circuit breaker circuit. The circuit breaker circuit based on hierarchical energy consumption and voltage limiting in the embodiment of the present invention can be connected to the main circuit of the target DC system through the first access terminal 201 and the second access terminal 202, and applied to main circuit breaking.

[0043] On the other hand, in order to protect and optimize the safety performance of the circuit breaker circuit and provide overcurrent protection, the circuit breaker circuit proposed in the embodiment of the present invention also includes: a buffer branch, which is connected in parallel with the main switch, that is, configured between the first access terminal and the second access terminal, and is used to absorb the system power generated by the switching action during the state switching of the main switch.

[0044] It should be noted that when the main switch is closed, the inductive load in the circuit may generate transient overcurrent, and the buffer branch can eliminate or reduce the overcurrent, thereby protecting the stability and long-term reliability of the entire circuit. In addition, an arc may also be generated during the opening of the main switch. The buffer branch can also help reduce the energy and duration of the arc, thereby reducing damage to the switch and other circuit components and improving safety. In some scenarios, the buffer branch can also reduce high-frequency noise interference and stabilize the voltage.

[0045] Specifically, Figure 3 is a schematic structural diagram of another optional circuit breaker circuit based on hierarchical energy consumption and voltage limiting according to an embodiment of the present invention, such as Figure 3 As shown, in Figure 1 On the basis of what is shown, the circuit breaker circuit further includes: a buffer branch 104 connected in parallel with the main switch 101 .

[0046] Optionally, the buffer branch can be configured as a series combination of a buffer resistor and a first buffer capacitor, wherein the first buffer capacitor is used to absorb system power and provide a primary conduction voltage to the primary energy consumption and voltage limiting branch based on the system power. Specifically, Figure 4 is a schematic diagram of the structure of an optional buffer branch according to an embodiment of the present invention, such as Figure 4 As shown, the buffer branch 104 includes a buffer resistor R s With the first buffer capacitor C s1 , R s With C s1 The connection method is series connection.

[0047] Another optional implementation manner is that the buffer branch may also include a PTC element (self-resetting fuse), an NTC element (thermistor) and an inductor. When the current exceeds the rated value, the PTC automatically increases its resistance. When the circuit temperature rises to a preset threshold, the NTC automatically increases its resistance, thereby limiting the overcurrent. The inductor can limit the instantaneous change of the current and store and release energy when the voltage changes, thereby effectively stabilizing the current and voltage.

[0048] Optionally, the buffer branch may also be configured as a series combination of a diode and a buffer capacitor, wherein the capacitor element may provide additional charge storage in a short period of time to maintain the operation of the circuit, and the diode may prevent the charge from flowing back.

[0049] On the other hand, in order to protect the components and equipment in the circuit that are sensitive to large currents, it is necessary to provide multi-level overcurrent protection for the target DC system. In the embodiment of the present invention, a graded energy consumption and voltage limiting strategy is adopted to set energy consumption and voltage limiting branches of different levels to provide protection for different current ranges respectively, accurately limit the current, ensure that the key parts and key equipment in the circuit are not damaged, prevent chain failures and ensure the system's rapid response and recovery capabilities.

[0050] Furthermore, the primary energy-consuming and voltage-limiting branch includes: a primary lightning arrester, wherein the primary lightning arrester is used to consume system electrical energy to reduce the main current when the main switch is cut off, and the types of primary lightning arresters include: metal oxide lightning arresters, line-type metal oxide lightning arresters, gapless line-type metal oxide lightning arresters and fully insulated composite sheathed metal oxide lightning arresters.

[0051] In the embodiment of the present invention, MOV (Metal Oxide Varistor) is used as a primary lightning arrester for example to protect the equipment from overvoltage damage in the circuit. The response time is at the nanosecond level, and the energy of the overvoltage is consumed or transferred by itself, limiting the voltage to the tolerable range of the equipment.

[0052] Furthermore, the primary energy consumption and voltage limiting branch also includes: a parallel combination of an auxiliary switch and a second buffer capacitor, wherein the second buffer capacitor is used to absorb system power in the primary energy consumption and voltage limiting branch and provide a secondary conduction voltage to the secondary energy consumption and voltage limiting branch based on the system power.

[0053] It should be noted that the auxiliary switch is used to control the on / off state of the second buffer capacitor, thereby controlling the timing of generating the secondary conduction voltage, that is, indirectly controlling the conduction timing of the secondary energy consumption branch.

[0054] Furthermore, the secondary energy-consuming and voltage-limiting branch includes: a secondary lightning arrester, wherein the secondary lightning arrester is used to consume system electric energy to reduce the main circuit current to 0 when the primary energy-consuming and voltage-limiting branch is switched from the on state to the off state.

[0055] Specifically, Figure 5 is a schematic diagram of a topological structure of an optional energy consumption and voltage limiting module according to an embodiment of the present invention, such as Figure 5 As shown, the energy consumption and voltage limiting module includes: a primary energy consumption and voltage limiting branch 102 and a secondary energy consumption and voltage limiting branch 103, wherein the primary energy consumption and voltage limiting branch includes: a primary lightning arrester MOV E , auxiliary switch Q2 and the second buffer capacitor C s2 , the secondary energy-consuming and voltage-limiting branch includes: secondary arrester MOV C .

[0056] It should be noted that when the main switch fails and is cut off, Q2 is initially in the on state, and the fault current is quickly transferred from the main circuit or buffer branch to the primary energy-consuming voltage-limiting branch. When the MOV is charged to the rated operating voltage, E The fault current gradually decreases, and then Q2 switches from the on state to the off state, cutting off the leakage current of the primary energy-consuming voltage-limiting branch. The remaining system energy is charged to C s2 Forming secondary conduction voltage; when the secondary conduction voltage reaches MOV C Rated operating voltage of MOV C action, dissipating the remaining energy and reducing the fault current to 0.

[0057] Another thing that needs to be explained is that, similar to the selection principle of the primary arrester, the types of secondary arresters may also include: metal oxide arresters, line type metal oxide arresters, gapless line type metal oxide arresters and fully insulated composite jacket metal oxide arresters.

[0058] Optionally, GDTs (Gas Discharge Tubes), avalanche diodes, TVS diodes (Transient Voltage Suppression Diodes) or solid-state relays can also be used as lightning arresters, wherein GDTs have a response speed and high energy handling capability similar to MOVs, avalanche diodes have high impedance at low voltages, but the impedance is greatly reduced after the voltage exceeds the rated value, and are suitable for circuit protection scenarios that require fast response, TVS diodes are specially designed to suppress transient voltages, can handle smaller voltage peaks, and have better transient protection effects for low energy, solid-state relays can also provide circuit protection functions, but are usually used in low-power or specific frequency applications. The embodiments of the present invention can select qualified components as lightning arresters according to specific implementation scenarios, and the specific selection criteria and selection process are not described in detail here.

[0059] In the embodiment of the present invention, a primary energy-consuming and voltage-limiting branch is set to take over the fault current and initially consume the system power when the main switch is cut off due to a fault, so as to achieve the technical effect of initially reducing the fault current. When the fault current is reduced to a preset current threshold, the secondary energy-consuming and voltage-limiting branch is mobilized to take over the remaining fault current to further consume the system power until the fault is eliminated. Overall, the technical effect of extending the energy consumption time, significantly reducing the overvoltage value during the energy consumption process, and avoiding the generation of voltage spikes that cause voltage shocks to power electronic devices can be achieved.

[0060] The present invention is described below in conjunction with another specific implementation manner.

[0061] Figure 6 is a schematic diagram of an optional conventional solid-state circuit breaker circuit according to an embodiment of the present invention, such as Figure 6 As shown, it includes a main switch device Q1, a buffer branch (buffer capacitor C s 、Diode D s , resistor R s ), voltage limiting energy dissipation component MOV, etc. Under normal working conditions, the main switch device Q1 is in the on state and is disconnected after a short circuit fault occurs.

[0062] Figure 7 is a schematic diagram of a current and voltage waveform of an optional breaking process based on a traditional solid-state circuit breaker circuit according to an embodiment of the present invention, such as Figure 7 As shown, I Q represents the current flowing through the main switch device Q1, I C Represents the current flowing through the buffer capacitor C s The current, I MOV Represents the current flowing through the MOV, U Q Represents the voltage across the device. The breaking process mainly includes 4 stages:

[0063] Stage 1, such as Figure 7 As shown in the time period t0 to t1, the system works normally before t0, Q1 is in the on state, and a short circuit occurs in the system at t0, and the fault current I Q Rapid rise;

[0064] Stage 2, such as Figure 7 As shown in the time period t1 to t2, after a fault occurs, the detection circuit identifies the fault, and at time t1 the control circuit sends a shutdown signal, Q1 is turned off, and I Q Rapidly decreases, the voltage U Q starts to rise, and at the same time the system supplies the buffer capacitor C s Charging, the capacitor voltage gradually rises;

[0065] Stage 3, such as Figure 7 As shown in the time period t3 to t4, the voltage U at both ends at time t3Q When the breakdown voltage of the MOV is reached, the MOV quickly changes from a high impedance state to a low impedance state, and the voltage flowing through the MOV gradually increases;

[0066] Stage 4, such as Figure 7 As shown in the time period t4 to t5, at t5, the MOV bears all the short-circuit current, and all the system energy caused by the short-circuit fault is absorbed by the MOV. The voltage across the two ends is U Q Gradually decreases and returns to the system bus voltage.

[0067] It can be seen that the energy dissipation time and voltage spike brought by the single-stage MOV voltage limiting energy dissipation solution are a contradiction. The larger the MOV's operating voltage, the larger the voltage spike and the shorter the dissipation time. Considering that high voltage spikes place too high demands on the withstand voltage performance of power electronic devices, which will greatly increase the period cost, in order to reduce the voltage spike, an MOV with a smaller operating voltage can be selected. The cost is that the energy dissipation time will be greatly extended, and the effect of fast response disconnection cannot be achieved.

[0068] The embodiment of the present invention proposes a solid-state DC circuit breaker topology solution based on graded energy consumption and voltage limiting, introduces a switch tube into the energy consumption branch, and adopts a two-stage energy consumption and voltage limiting strategy. The primary energy consumption and voltage limiting branch first adopts a lower clamping voltage to consume energy when the current is large, and the secondary energy consumption and voltage limiting branch consumes energy when the current is small. The voltage spike in the shutdown process can be greatly reduced at the expense of some energy consumption time, the withstand voltage requirement for the power electronic switch is reduced, and the device performance is reduced while ensuring a fast response speed.

[0069] Figure 8 is a schematic diagram of an optional low-voltage DC solid-state circuit breaker connected to a DC system based on hierarchical energy consumption and voltage limiting according to an embodiment of the present invention, such as Figure 8 As shown, the structure is as follows:

[0070] The main circuit of the system includes: a power supply, an inductor and a load connected in series;

[0071] The first access terminal ( Figure 8 ① is used as the schematic diagram in the figure), which is configured as the incoming line end of a low-voltage solid-state DC circuit breaker based on graded energy consumption and voltage limiting;

[0072] The second access terminal ( Figure 8 ② is used as the schematic diagram in the figure), which is configured as the outlet terminal of a low-voltage solid-state DC circuit breaker based on graded energy consumption and voltage limiting;

[0073] A main branch power electronic switch Q1 (i.e., the main switch of one of the above embodiments), which is connected between the first access terminal and the second access terminal;

[0074] The buffer branch is connected between the first access terminal and the second access terminal and is a buffer resistor R s With the first buffer capacitor Cs1 A series combination of

[0075] The primary energy consumption voltage limiting branch is connected between the first access terminal and the second access terminal in the following manner: the auxiliary power electronic switch Q2 and the second buffer capacitor C s2 In parallel, then the whole with the primary metal oxide arrester MOV E Series connection;

[0076] The secondary energy dissipation and voltage limiting branch is connected between the first access terminal and the second access terminal, and includes a secondary metal oxide arrester MOV C .

[0077] It should be noted that power electronic switches include a series of power chips and combinations such as MOS, IGBT or IGCT. The arresters of energy-consuming branches include metal oxide arresters, line-type metal oxide arresters, gapless line-type metal oxide arresters, fully insulated composite jacket metal oxide arresters and combinations. The metal oxide arresters MOV of the primary energy-consuming voltage-limiting branch E The action voltage is lower than the system voltage, and the clamping voltage is higher than the system voltage.

[0078] The working principle of the above-mentioned low-voltage DC solid-state circuit breaker based on graded energy consumption and voltage limiting is:

[0079] When the low-voltage solid-state DC circuit breaker based on graded energy consumption and voltage limiting is turned off, the main branch power electronic switch Q1 and the auxiliary power electronic switch Q2 of the primary energy consumption and voltage limiting branch are both in the off state. At this time, the MOV of the primary energy consumption and voltage limiting branch E And Q2 bear the system voltage at the same time;

[0080] When the low-voltage solid-state DC circuit breaker based on graded energy consumption and voltage limiting is normally flowing, the main branch power electronic switch Q1 and the auxiliary power electronic switch Q2 of the primary energy consumption and voltage limiting branch are both in the on state, and the main branch power electronic switch Q1 carries the load current of the main circuit;

[0081] When the main current needs to be disconnected, the main branch circuit electronic switch Q1 is turned off, the main current is quickly transferred to the buffer branch, and the charging voltage of the buffer branch reaches the primary metal oxide arrester MOV E After the action voltage reaches , the main current is transferred to the primary energy-consuming voltage-limiting branch, and the main current begins to decrease.

[0082] When the main current drops to a lower level, the auxiliary power electronic switch Q2 is turned off, and the primary energy-consuming voltage-limiting branch is charged to the secondary energy-consuming voltage-limiting branch MOV. C The operating voltage is increased, the main current is further reduced, the residual energy of the circuit is dissipated, the system current is reduced to zero, and the breaking is completed.

[0083] The following is an explanation with reference to a schematic diagram.

[0084] Fig. 9 is a schematic diagram of a current loop in a normal current flow scenario according to an optional embodiment of the present invention, such as Fig. 9 As shown, during normal flow, the main branch power electronic switch Q1 is turned on to carry the load current, and the auxiliary power electronic switch Q2 of the primary energy-consuming and voltage-limiting branch is turned on, but the system voltage does not reach the primary metal oxide arrester MOV. E The action voltage is therefore not flowing through the primary energy-consuming voltage-limiting branch, and no current flows through Q2.

[0085] Fig.10 is a schematic diagram of a current loop in an optional short circuit fault scenario according to an embodiment of the present invention, such as Fig.10 As shown in the figure, when a short circuit fault occurs, the main current rises rapidly, the main branch power electronic switch cuts off Q1, and the buffer branch takes over the fault current on the main line and supplies the first buffer capacitor C s1 Rapid charging reaches the action voltage of the primary energy consumption voltage limiting branch, making the MOV E It acts to dissipate the energy stored in the inductor in the main circuit, causing the main circuit current to gradually decrease.

[0086] Fig.11 is a schematic diagram of a current loop in another optional short circuit fault scenario according to an embodiment of the present invention, such as Fig.11 As shown, when the system energy consumption is about to end, the auxiliary power electronic switch Q2 is turned off, the leakage current of the primary energy consumption voltage limiting branch is cut off, and the second buffer capacitor C s2 Rapid charging reaches the action voltage of the secondary energy-consuming voltage-limiting branch, making the MOV C action, dissipating the remaining energy and reducing the system current to zero.

[0087] Fig.12 is a schematic diagram of current and voltage waveforms during a breaking process of a low-voltage DC solid-state circuit breaker based on graded energy consumption and voltage limiting according to an embodiment of the present invention, such as Fig.12 As shown, Figure 7 Compared with the waveform in , the graded energy consumption and voltage limiting method sacrifices the energy consumption time within the controllable range in exchange for a significant reduction in overvoltage in the primary energy consumption process and the secondary energy consumption process, alleviating the voltage spike phenomenon.

[0088] In an embodiment of the present invention, a grading strategy is used in the energy dissipation and voltage limiting branch, and a switching tube is introduced, so that the primary energy dissipation and voltage limiting branch uses a lower clamping voltage to dissipate energy when the current is large, reduces the current and establishes the voltage, and the secondary energy dissipation and voltage limiting branch further reduces the current when the current is small, thereby achieving the technical effect of reducing the voltage spike during the circuit breaker shutdown process.

[0089] Embodiment 2

[0090] An embodiment of the present invention provides a low-voltage solid-state DC circuit breaker, including the circuit breaker circuit based on hierarchical energy consumption and voltage limiting according to any one of the above-mentioned embodiments 1, and at least including:

[0091] A main circuit switch 101, used to control the on / off state of the main circuit in the target DC system;

[0092] The primary energy-consuming and voltage-limiting branch 102 is connected in parallel with the main switch 101, and is used to be turned on when the main switch 101 is turned off, consuming system power until the main current drops to a preset current threshold, and then turned off;

[0093] The secondary energy consumption and voltage limiting branch 103 is connected in parallel with the primary energy consumption and voltage limiting branch 102, and is used to be turned on when the primary energy consumption and voltage limiting branch 102 switches from the on state to the off state, and consumes system power until the main current drops to 0, and then is turned off.

[0094] The low-voltage solid-state DC circuit breaker proposed in the present invention comprises a primary energy-consuming and voltage-limiting branch 102 and a secondary energy-consuming and voltage-limiting branch 103 connected in parallel with a main switch 101. When the target DC system operates normally and stably, the two energy-consuming and voltage-limiting branches are kept in an off state. If a fault occurs in the target DC system, after the main switch 101 is turned off, the primary energy-consuming and voltage-limiting branch 102 is turned on first, takes over the fault current and consumes system power until the fault current is initially reduced to a preset current threshold and then is turned off. The secondary energy-consuming and voltage-limiting branch 102 that is turned on synchronously takes over the remaining fault current and further consumes system power until the fault current is reduced to 0, that is, the system fault is eliminated.

[0095] Compared with the prior art, the present invention adopts a two-stage energy consumption and voltage limiting strategy. The primary energy consumption and voltage limiting branch first consumes energy under high current conditions to preliminarily reduce the fault current and complete the first disconnection. The secondary energy consumption and voltage limiting branch dissipates the residual energy caused by the fault under low current conditions until the fault is eliminated and the secondary disconnection is completed. The energy consumption time is extended as a whole, and the overvoltage in the two-stage energy consumption process is significantly reduced, thereby avoiding the influence of voltage spikes on power electronic devices, thereby solving the technical problem that the power electronic devices used in the low-voltage DC solid-state circuit breakers in the related technology cannot cope with the voltage spikes generated in the DC disconnection process.

[0096] The serial numbers of the above embodiments of the present invention are only for description and do not represent the advantages or disadvantages of the embodiments.

[0097] In the above embodiments of the present invention, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0098] In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. Among them, the device embodiments described above are only schematic. For example, the division of the units can be a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of units or modules, which can be electrical or other forms.

[0099] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple units. Some or all of the units may be selected according to actual needs to achieve the purpose of the present embodiment.

[0100] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0101] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions for a computer device (which can be a personal computer, a server or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), mobile hard disk, magnetic disk or optical disk and other media that can store program codes.

[0102] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A circuit breaker circuit based on hierarchical energy consumption and voltage limiting, characterized in that: include: A main circuit switch, used to control the on / off state of the main circuit in the target DC system; A primary energy-consuming and voltage-limiting branch, connected in parallel with the main switch, is used to be turned on when the main switch is turned off, consumes system power until the main current drops to a preset current threshold, and then is turned off; The secondary energy-consuming and voltage-limiting branch is connected in parallel with the primary energy-consuming and voltage-limiting branch, and is used for being turned on when the primary energy-consuming and voltage-limiting branch is switched from an on state to an off state, consuming the system electric energy until the main circuit current is reduced to 0, and then being turned off.

2. The circuit breaker circuit based on hierarchical energy consumption and voltage limiting according to claim 1, characterized in that: Also includes: A first access terminal, wherein the first access terminal is configured as an incoming line terminal of the circuit breaker circuit.

3. The circuit breaker circuit based on hierarchical energy consumption and voltage limiting according to claim 1, characterized in that: Also includes: A second access terminal, wherein the second access terminal is configured as an outgoing terminal of the circuit breaker circuit.

4. The circuit breaker circuit based on hierarchical energy consumption and voltage limiting according to claim 1, characterized in that: Also includes: The buffer branch is connected in parallel with the main switch and is used to absorb system electric energy generated by the switching action during the state switching of the main switch.

5. The circuit breaker circuit based on hierarchical energy consumption and voltage limiting according to claim 4, characterized in that: The buffer branch is configured as a series combination of a buffer resistor and a first buffer capacitor, wherein the first buffer capacitor is used to absorb the system power and provide a primary conduction voltage to the primary energy consumption and voltage limiting branch based on the system power.

6. The circuit breaker circuit based on hierarchical energy consumption and voltage limiting according to claim 1, characterized in that: The primary energy-consuming and voltage-limiting branch includes a primary lightning arrester, wherein the primary lightning arrester is used to consume the system electric energy to reduce the main current when the main switch is turned off.

7. The circuit breaker circuit based on hierarchical energy consumption and voltage limiting according to claim 6, characterized in that: The primary energy consumption and voltage limiting branch further comprises: a parallel combination of an auxiliary switch and a second buffer capacitor, wherein the second buffer capacitor is used to absorb system power in the primary energy consumption and voltage limiting branch and provide a secondary conduction voltage to the secondary energy consumption and voltage limiting branch based on the system power.

8. The circuit breaker circuit based on hierarchical energy consumption and voltage limiting according to claim 1, characterized in that: The secondary energy-consuming and voltage-limiting branch includes a secondary lightning arrester, wherein the secondary lightning arrester is used to consume the system electric energy to reduce the main circuit current to 0 when the primary energy-consuming and voltage-limiting branch is switched from an on state to an off state.

9. The circuit breaker circuit based on hierarchical energy consumption and voltage limiting according to claim 8, characterized in that: The types of secondary arresters include: metal oxide arresters, line type metal oxide arresters, gapless line type metal oxide arresters and fully insulated composite jacket metal oxide arresters.

10. A low voltage solid state DC circuit breaker, characterized in that: It comprises a circuit breaker circuit based on graded energy consumption and voltage limiting as described in any one of claims 1 to 9.

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