Self-Powered Circuit of DC Solid-State Circuit Breaker Based on Capacitive Voltage Division and Its Control Method

Abstract

The present application provides a self-powered circuit for a DC solid-state circuit breaker based on capacitive voltage division and its control method. The circuit includes: a self-powered unit, a control circuit, a drive circuit, and a DC solid-state circuit breaker; the self-powered unit includes a power switch, a capacitive voltage division circuit, and a DC / DC converter; the DC solid-state circuit breaker is connected in series to the DC bus. The first terminal of the power switch is connected to the drive circuit, the second terminal of the power switch is connected to the DC bus, the third terminal of the power switch is connected to the capacitive voltage division circuit, the capacitive voltage division circuit is connected to the control circuit and the DC / DC converter, and the drive circuit is connected to the DC / DC converter, the control circuit, and the DC solid-state circuit breaker. The DC bus voltage is divided and stepped down by a capacitor, and a stable supply voltage is provided after isolation and transformation by the DC / DC converter, ensuring that the DC solid-state circuit breaker can be controlled and monitored in real time whether it is in a normal state or a fault removal state.

Description

Technical Field

[0001] This application belongs to the technical field of DC distribution system protection, and particularly relates to a self-powered circuit of a DC solid-state circuit breaker based on capacitive voltage division and its control method. Background Art

[0002] Compared with AC power systems, DC power systems have more advantages in reducing energy losses, accommodating new energy sources, and DC loads. However, the low impedance and low inertia of DC grid systems result in a high rate of rise and large amplitude of fault currents, which pose strict requirements on the fault response speed of DC solid-state circuit breakers (SSCBs). In addition, since DC short-circuit fault currents do not have natural zero-crossing points, arc management during fault clearing becomes more challenging, making the isolation of DC faults more difficult than AC faults. As an important part of DC power systems, DC solid-state circuit breakers play a key role in achieving fault isolation, preventing the further spread of DC faults, and ensuring the safe and reliable operation of DC systems. Traditional mechanical circuit breakers cannot meet the requirements of fast protection due to their slow breaking speed. Moreover, their short lifespan also makes it difficult to meet the requirements of intelligent control and fast fault clearing.

[0003] Fortunately, in recent years, solid-state circuit breakers based on wide-bandgap semiconductor devices have been proposed, which can solve problems such as slow turn-off speed and difficult arc extinction. However, power devices represented by silicon carbide (SiC) require an external power supply to operate normally due to the presence of control and drive circuits. The existence of auxiliary power supply lines not only increases the cost of the circuit breaker but also raises the complexity of the equipment. Even in some scenarios such as undersea observation networks, there are no auxiliary power supply lines. Therefore, realizing the self-power supply of DC solid-state circuit breakers can improve the operational reliability of power systems and reduce operating costs. In existing methods, electrical energy is obtained by using the voltage drop generated by the short-circuit current flowing through power semiconductor devices during a fault. The voltage drop across the power semiconductor device is used as the trigger voltage to cut off the fault current during a short-circuit fault. This method of obtaining power is simple and feasible. However, when the DC system is operating normally, the DC solid-state circuit breaker is in a de-energized state and cannot perform real-time control and monitoring. Therefore, a reasonable self-power supply method for the circuit breaker needs to be proposed to ensure the power supply stability of the circuit breaker and enable real-time control and monitoring whether the circuit breaker is in a normal state or a fault-clearing state. Summary of the Invention

[0004] The main objective of the embodiments of the present invention is to provide a self-powered circuit for a DC solid-state circuit breaker based on capacitive voltage division and its control method, which can use a capacitor to divide and step down the voltage of the DC bus, isolate and transform the voltage through a DC / DC converter, and provide a stable power supply voltage to ensure real-time control and monitoring of the DC solid-state circuit breaker whether it is in a normal state or a fault removal state.

[0005] In a first aspect, a self-powered circuit for a DC solid-state circuit breaker based on capacitive voltage division is provided, including: a self-powered unit, a control circuit, a drive circuit, and a DC solid-state circuit breaker; the self-powered unit includes a power switch, a capacitive voltage division circuit, and a DC / DC converter; the DC solid-state circuit breaker is connected in series to the DC bus, the first end of the power switch is connected to the drive circuit, the second end of the power switch is connected to the DC bus, the third end of the power switch is connected to the capacitive voltage division circuit, the capacitive voltage division circuit is connected to the control circuit and the DC / DC converter, and the drive circuit is connected to the DC / DC converter, the control circuit, and the DC solid-state circuit breaker.

[0006] In a possible implementation, the capacitive voltage division circuit includes: a first resistor, a first capacitor, and a second capacitor; the first resistor and the first capacitor are connected in series, and the third end of the power switch is connected to the first resistor, the first end of the second capacitor is connected to the first capacitor, and is also connected to the control circuit and the DC / DC converter, the second end of the second capacitor is grounded and is also connected to the control circuit and the DC / DC converter.

[0007] In a possible implementation, the capacitive voltage division circuit further includes a second resistor, one end of the second resistor is connected to the end of the first resistor away from the first capacitor, and the other end is connected to the first end of the second capacitor.

[0008] In another possible implementation, the capacitance value of the first capacitor is greater than that of the second capacitor.

[0009] In another possible implementation, the DC / DC converter is a step-down isolation conversion device, which is used to step down and isolate the sampled voltage on the second capacitor and output a stable power supply voltage to supply power to the subsequent control circuit, drive circuit, and DC solid-state circuit breaker.

[0010] In another possible implementation, the power switch is a silicon carbide junction field effect transistor, the first end is the gate, the second end is the drain, and the third end is the source.

[0011] In a second aspect, a control method for the self-powered circuit of a DC solid-state circuit breaker based on capacitive voltage division as described above is provided. The control method includes: dividing the DC bus voltage through a capacitive voltage division circuit and inputting it into a DC / DC converter; collecting the sampled voltage input into the DC / DC converter through a control circuit; comparing the sampled voltage with a preset high threshold and a preset low threshold respectively through the control circuit, and outputting a control signal to a drive circuit according to the comparison result; outputting a first drive signal through the drive circuit to control the on / off of a power switch according to the control signal, thereby controlling the DC / DC converter to output a stable power supply voltage.

[0012] In another possible implementation, outputting a control signal to the drive circuit according to the comparison result includes: if the sampled voltage is less than or equal to the preset low threshold, the control circuit outputs a control signal with a high level; if the sampled voltage is greater than the preset high threshold, the control circuit outputs a control signal with a low level; if the sampled voltage is greater than the low threshold and less than or equal to the high threshold, the control circuit maintains the control signal in the previous state.

[0013] In another possible implementation, outputting a first drive signal through the drive circuit to control the on / off of the power switch according to the control signal, thereby controlling the DC / DC converter to output a stable power supply voltage includes: if the control circuit outputs a control signal with a high level, the drive circuit outputs a conduction signal according to the control signal to control the power switch to conduct, the DC bus voltage charges the first capacitor and the second capacitor in the capacitive voltage division circuit, the voltage across the second capacitor rises, and the voltage across the second capacitor is controlled to be higher than the low threshold; if the control circuit outputs a control signal with a low level, the drive circuit outputs a cut-off signal according to the control signal to control the power switch to turn off, the first capacitor discharges through the first resistor and the second resistor, and the second capacitor consumes power through the DC / DC converter, and the voltage across the second capacitor is controlled to be lower than the high threshold. Description of the Drawings

[0014] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for describing the embodiments of the present application will be briefly introduced below.

[0015] Figure 1 A schematic diagram of a self-powered circuit of a DC solid-state circuit breaker based on capacitive voltage division provided by an embodiment of the present invention;

[0016] Figure 2 A timing schematic diagram of a self-powered circuit of a DC solid-state circuit breaker based on capacitive voltage division provided by an embodiment of the present invention;

[0017] Figure 3 A schematic diagram of a simulation circuit of a self-powered circuit of a DC solid-state circuit breaker based on capacitive voltage division provided by an embodiment of the present invention;

[0018] Figure 4 Schematic diagram of the simulation results of the self-powered circuit of a DC solid-state circuit breaker based on capacitive voltage division provided by an embodiment of the present invention;

[0019] Figure 5 Flowchart of a control method for a self-powered circuit of a DC solid-state circuit breaker based on capacitive voltage division provided by an embodiment of the present invention. Detailed implementation manners

[0020] The embodiments of the present application will be described in detail below. Examples of the embodiments are shown in the drawings, where the same or similar reference numerals denote the same or similar modules or modules with the same or similar functions throughout. The embodiments described below with reference to the drawings are exemplary and are only used to explain the present application and should not be construed as a limitation to the present invention.

[0021] Those skilled in the art of the present technology can understand that unless specifically stated otherwise, the singular forms "a", "an", "the" and "said" used herein may also include the plural forms. It should be further understood that the term "comprising" used in the specification of the present application means the presence of the described features, integers, steps, operations, modules and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, modules, components and / or groups thereof. It should be understood that when we say that a module is "connected" or "coupled" to another module, it can be directly connected or coupled to other modules, or there may also be intermediate modules. In addition, the "connection" or "coupling" used herein may include wireless connection or wireless coupling. The phrase "and / or" used herein includes all or any one of the associated listed items and all combinations.

[0022] To make the objectives, technical solutions and advantages of the present application clearer, the implementation manners of the present application will be further described in detail below with reference to the drawings.

[0023] The technical solutions of the present application and how the technical solutions of the present application solve the above technical problems will be described in detail below with specific embodiments. These several specific embodiments below can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments. The embodiments of the present application will be described below with reference to the drawings.

[0024] Figure 1 The self-powered circuit of a DC solid-state circuit breaker based on capacitive voltage division provided by an embodiment of the present invention. As Figure 1As shown in the figure, the self-powered circuit of the DC solid-state circuit breaker based on capacitive voltage division includes: a self-powered unit, a control circuit, a drive circuit, and a DC solid-state circuit breaker. The self-powered unit includes a power switch J1, a capacitive voltage division circuit, and a DC / DC converter. The DC solid-state circuit breaker is connected in series to the DC bus. The first terminal of the power switch J1 is connected to the drive circuit, the second terminal of the power switch J1 is connected to the DC bus, the third terminal of the power switch J1 is connected to the capacitive voltage division circuit, the capacitive voltage division circuit is connected to the control circuit and the DC / DC converter, and the drive circuit is connected to the DC / DC converter, the control circuit, and the DC solid-state circuit breaker.

[0025] The capacitive voltage division circuit includes: a first resistor R1, a first capacitor C1, and a second capacitor C in . The first resistor R1 and the first capacitor C1 are connected in series with each other, and the third terminal of the power switch J1 is connected to the first resistor R1. The first terminal of the second capacitor C in is connected to the first capacitor C1, and is simultaneously connected to the control circuit and the DC / DC converter. The second terminal of the second capacitor C in is grounded and is simultaneously connected to the control circuit and the DC / DC converter. The capacitive voltage division circuit further includes a second resistor R2. One end of the second resistor R2 is connected to the end of the first resistor R1 that is far from the first capacitor C1, and the other end is connected to the first terminal of the second capacitor C in . The capacitance value of the first capacitor C1 is greater than the capacitance value of the second capacitor C in . The power switch J1 is a silicon carbide junction field effect transistor SiC JFET. The first terminal is the gate, the second terminal is the drain, and the third terminal is the source. The first resistor R1 is a charging current limiting resistor, and the second resistor R2 is a discharging resistor. In the embodiment of the present invention, two capacitors with different capacitance values are connected in series to achieve voltage division and step-down of the DC bus voltage. Using capacitors in series to divide and step down the bus voltage enables real-time control and monitoring whether the circuit breaker is in a normal state or a fault removal state.

[0026] The DC / DC converter is a step-down isolation conversion device, which is used to step down and isolate the sampled voltage on the second capacitor and output a stable supply voltage to supply power to the subsequent control circuit, drive circuit, and DC solid-state circuit breaker. The DC / DC converter converts the voltage on the low-voltage capacitor into a low-voltage supply voltage, thereby ensuring stable self-power supply for the SSCB control system.

[0027] In the embodiment of the present invention, the self-powered unit consists of a power switch J1, a charging current limiting resistor R1, a discharging resistor R2, and series voltage dividing and step-down capacitors C1 and C in . J1, as a power switch device, controls the charging and discharging of the capacitors C1 and C in . When the power switch J1 is turned on, the bus voltage charges the first capacitor C1 and the second capacitor C through the first resistor R1 inCharging. In terms of parameter selection, the first capacitor C1 is selected as a capacitor with a small capacitance value and a high withstand voltage, and the second capacitor C in is selected as a capacitor with a large capacitance value. Thus, by using the voltage division of capacitors in series, the first capacitor C1 bears a larger bus voltage, and the second capacitor C in bears a smaller bus voltage and serves as the input of the DC / DC converter. When the power switch J1 is turned off, the first capacitor C1 discharges through the second resistor R2 and the first resistor R1, while the charge on the second capacitor C in is consumed through the DC / DC converter. The DC / DC converter, as a step-down isolation conversion device, steps down and isolates the voltage on the second capacitor C in and supplies power to the subsequent control circuit and drive circuit. The control circuit controls the high and low level wave generation of the drive circuit to achieve the on and off of the power switch J1 and the DC solid-state circuit breaker. The drive circuit receives the signal from the control circuit and realizes the switching of the power switch J1 and the DC solid-state circuit breaker through the PWM signal.

[0028] The principle of the control circuit in the embodiment of the present invention is as follows: For the voltage on the second capacitor C in , a high threshold V H and a low threshold V L are set. The sampled voltage v in on the second capacitor C in is compared with the two, so as to control the PWM output of the drive circuit. Among them, the high threshold V H is the highest input voltage of the DC / DC converter, and the low threshold V L is the lowest input voltage of the DC / DC converter.

[0029] The following conducts a detailed analysis on the implementation process of the capacitor voltage division type SSCB self-power supply circuit, providing a theoretical basis for the selection of equipment parameters.

[0030] In the embodiment of the present invention, the capacitor voltage division circuit divides the bus voltage through the series-connected first resistor R1, first capacitor C1, and second capacitor C in . The control circuit collects the sampled voltage v in across the second capacitor C in , and compares the sampled voltage v in with the high threshold V H and the low threshold V L .

[0031] If , the control circuit outputs a high level, and the drive circuit will output a conduction signal to control the conduction of the power switch J1. At this time, the bus voltage charges the first capacitor C1 and the second capacitor C in through the first resistor R1. The voltage across the second capacitor C in rises, ensuring that the sampled voltage vin higher than the minimum input voltage V of the DC / DC converter L .

[0032] If , the control circuit outputs a low level, and the drive circuit will output a cut-off signal to control the power switch J1 to turn off. At this time, the first capacitor C1 discharges through the second resistor R2 and the first resistor R1, and the voltage drops. The voltage across the second capacitor C in is consumed by the DC / DC converter, ensuring that the sampled voltage v in is lower than the maximum input voltage V of the DC / DC converter H .

[0033] If , the control circuit keeps the output level unchanged, that is, if the output level of the control circuit at the previous moment is high, the control circuit outputs a high level currently; if the output level of the control circuit at the previous moment is low, the control circuit outputs a low level currently.

[0034] In this way, it can be ensured that the sampled voltage v in across the second capacitor C in is between the minimum input voltage V L and the maximum input voltage V H of the DC / DC converter, so that a stable power supply voltage can be ensured for the DC / DC converter.

[0035] Assume that the voltages of the first capacitor C1 and the second capacitor C in in the initial state are 0, the output voltage of the DC / DC converter is 12V, the control signal of the control circuit is 5V, and the DC system is operating normally. The timing analysis of the implementation process of the self-powered circuit of the DC solid-state circuit breaker based on capacitive voltage division in the embodiment of the present invention is as follows. For the specific timing, see Figure 2 .

[0036] Stage I (0 - t 0 ): Since the voltages of the first capacitor C1 and the second capacitor C in in the initial state are 0, the sampled voltage v in across the second capacitor C in = 0 < V L , the control circuit outputs a high level, and the drive circuit will output a conduction signal to control the power switch J1 to conduct. The line voltage charges the first capacitor C1 and the second capacitor C in through the first resistor R1, and the sampled voltage v in across the second capacitor C in rises.

[0037] Stage II (t 0 - t 1 ): When vin >V L When the sampling voltage v in is higher than the minimum input voltage V of the DC / DC converter L , the DC / DC converter starts to work normally, stably outputs the supply voltage, and ensures the normal operation of the control circuit and the drive circuit. And since the SiC JFET device itself is a normally-on device and remains in the on-state without a drive voltage and can be regarded as a wire, the second capacitor C in can be normally charged before the DC / DC converter stably outputs. The logic of the control circuit remains unchanged during this stage.

[0038] Stage III (t 1 -t 2 ): When v in >V H , the control circuit outputs a low level, and the drive circuit outputs a cut-off signal to control the power switch J1 to turn off. At this time, the first capacitor C1 discharges through the second resistor R2 and the first resistor R1, and the voltage across the second capacitor C in is consumed by the DC / DC converter, and the voltage v in starts to drop.

[0039] Stage IV (t 2 -t 3 ): After discharging for a certain period of time, , the control circuit outputs a high level, and the second capacitor C in is charged again, v in rises, and so on in a cycle to maintain , thus ensuring the stable output of the DC / DC converter. And since the self-powered unit is connected in parallel on the DC bus side and is charged using the bus voltage, even if the circuit breaker disconnects the subsequent circuit, the self-powered unit can still ensure normal operation and enable the DC / DC converter to output a stable supply voltage.

[0040] The self-powered circuit of the DC solid-state circuit breaker based on capacitive voltage division in the embodiment of the present invention uses a capacitor to divide and step down the DC bus voltage during the normal operation of the SSCB, and provides a stable supply voltage for the control circuit and the drive circuit after isolation and transformation by the DC / DC converter. And after the SSCB removes the fault and disconnects the subsequent circuit, it can still provide a stable supply voltage, ensuring that the SSCB can perform real-time control and monitoring whether it is in a normal state or a fault removal state.

[0041] To verify the effectiveness of the self-powered circuit of the DC solid-state circuit breaker based on capacitive voltage division in the embodiment of the present invention, the feasibility of this topology can be verified through PSpice simulation. The simulation circuit is as Figure 3As shown, the self-powered circuit of the DC solid-state circuit breaker based on capacitive voltage division in the embodiment of the present invention is connected to the simulation circuit, and the DC solid-state circuit breaker is turned on and off by VPULSE drive. For the self-powered circuit, refer to Figure 1 , VPULSE is the VPULSE pulse voltage source inside PSpice, and DC uses the built-in DC voltage source V of PSpice DC , and the load R L is a 10Ω pure resistive load.

[0042] The device parameters in the simulation circuit are shown in Table 1. The simulation model of the SiC JFET comes from UnitedSiC Company in the United States. The bus voltage is set to 1000V. The driving voltage of J1 in the self-powered unit is provided by the driving chip UCC21530. v in After being divided by the resistor connected in parallel at both ends of C in , it is input to the comparator TLV3501 to control the driving signal of the driving chip UCC21530. The DC / DC converter is replaced by a simple buck circuit. By observing the voltage waveforms at both ends of the capacitor C in , the output voltage waveform of the buck circuit, and the waveforms of both after the DC solid-state circuit breaker is turned off, the implementation effect of the self-powered circuit of the DC solid-state circuit breaker based on capacitive voltage division in the simulation circuit can be verified, and the feasibility of the self-powered circuit of the DC solid-state circuit breaker based on capacitive voltage division can be verified.

[0043] Table 1 Device parameters of the self-powered circuit of the DC solid-state circuit breaker based on capacitive voltage division

[0044]

[0045] The simulation results of the self-powered circuit of the DC solid-state circuit breaker based on capacitive voltage division are as Figure 4 shown. The self-powered circuit and the load R L are connected to the circuit at the 100us moment. Since the bus voltage is 1000V, the load current rapidly rises to 100A. The initial voltage at both ends of the second capacitor C in is 0. Therefore, the TLV3501 outputs a 5V high level to control the driving chip UCC21530 to output a conduction signal, and the power switch J1 conducts. The second capacitor C in starts to charge, and the sampling voltage v in rises and reaches at 5ms. The buck circuit starts to work. At 10ms, the output voltage of the buck circuit stabilizes at 10V. At 12ms, v in reaches the high threshold V H , the TLV3501 outputs a 0V low level to control the driving chip UCC21530 to output a cut-off signal, and the power switch J1 turns off. The charge on the second capacitor C in is consumed by the buck circuit, and vin descends, v at 31 ms in reaches the low threshold V L , TLV3501 outputs a 5V high level again, and so on in a cycle to ensure that v in is always within the input range of the DC / DC converter, and can stably output the supply voltage. At 60 ms, VPLUSE outputs a turn-off signal, the DC solid-state circuit breaker turns off, simulating the fault removal after a line fault, and the load current drops to 0. Since the self-powered circuit is connected in parallel on the DC bus side, even if the subsequent circuit is disconnected, the DC / DC converter can still output a stable supply voltage to ensure the power supply stability of the SSCB.

[0046] In summary, the self-powered circuit of the DC solid-state circuit breaker based on capacitive voltage division according to the embodiment of the present invention includes: a self-powered unit, a control circuit, a drive circuit, and a DC solid-state circuit breaker; the self-powered unit includes a power switch, a capacitive voltage division circuit, and a DC / DC converter; the DC solid-state circuit breaker is connected in series on the DC bus, the first end of the power switch is connected to the drive circuit, the second end of the power switch is connected to the DC bus, the third end of the power switch is connected to the capacitive voltage division circuit, the capacitive voltage division circuit is connected to the control circuit and the DC / DC converter, the drive circuit is connected to the DC / DC converter, the control circuit, and the DC solid-state circuit breaker, uses a capacitor to divide and step down the DC bus voltage, and provides a stable supply voltage after isolation and transformation by the DC / DC converter, ensuring that the DC solid-state circuit breaker can perform real-time control and monitoring whether it is in a normal state or a fault removal state.

[0047] As Figure 5 shown is a flowchart of a control method for a self-powered circuit of a DC solid-state circuit breaker based on capacitive voltage division provided by an embodiment of the present invention. The control method includes:

[0048] Step S11, dividing the DC bus voltage through a capacitive voltage division circuit and inputting it into the DC / DC converter.

[0049] In the embodiment of the present invention, the capacitive voltage division circuit divides the bus voltage through the series-connected first resistor R1, first capacitor C1, and second capacitor C in . The voltage across the second capacitor C in after voltage division is input into the DC / DC converter as the input voltage of the DC / DC converter.

[0050] Step S12, collecting the sampled voltage input into the DC / DC converter through the control circuit.

[0051] Collect the voltage across the second capacitor C in through the control circuit, which is the sampled voltage input into the DC / DC converter.

[0052] Step S13: Compare the sampled voltage with a preset high threshold and a preset low threshold respectively through a control circuit, and output a control signal to a drive circuit according to the comparison result.

[0053] Optionally, if the sampled voltage is less than or equal to the preset low threshold, the control circuit outputs a control signal with a high level. If the sampled voltage is greater than the preset high threshold, the control circuit outputs a control signal with a low level. If the sampled voltage is greater than the low threshold and less than or equal to the high threshold, the control circuit maintains the control signal of the previous state.

[0054] Step S14: Output a first drive signal through the drive circuit according to the control signal to control the on / off of the power switch, thereby controlling the DC / DC converter to output a stable supply voltage.

[0055] If the control circuit outputs a control signal with a high level, the drive circuit outputs a conduction signal according to the control signal to control the power switch to conduct, and the DC bus voltage charges the first capacitor and the second capacitor in the capacitor voltage division circuit. The voltage across the second capacitor rises, and the voltage across the second capacitor is controlled to be higher than the low threshold, that is, it is ensured that the sampled voltage v in across the two ends of the second capacitor C in is higher than the minimum input voltage V L of the DC / DC converter.

[0056] If the control circuit outputs a control signal with a low level, the drive circuit outputs a cut-off signal according to the control signal to control the power switch to turn off. The first capacitor discharges through the first resistor and the second resistor, and the second capacitor consumes power through the DC / DC converter. The voltage across the second capacitor is controlled to be lower than the high threshold, that is, it is ensured that the sampled voltage v in across the two ends of the second capacitor C in is lower than the maximum input voltage V H of the DC / DC converter.

[0057] Through the above control, it is ensured that the sampled voltage v in across the two ends of the second capacitor C in is between the minimum input voltage V L and the maximum input voltage V H of the DC / DC converter, so as to ensure that the DC / DC converter can provide a stable supply voltage.

[0058] The drive circuit also outputs a second drive signal to the DC solid-state circuit breaker to control the on / off of the DC solid-state circuit breaker.

[0059] In the embodiment of the present invention, two capacitors with different capacitance values are connected in series to achieve voltage division and step-down of the DC bus voltage, and the voltage on the low-voltage capacitor is converted into a low-voltage power supply voltage through a DC / DC converter, thereby ensuring the stable self-power supply of the SSCB control system; since the capacitor in series DC divides and steps down the bus voltage, real-time control and monitoring can be carried out whether the circuit breaker is in a normal state or a fault cut-off state.

[0060] It should be understood that although the steps in the flowchart of the accompanying drawings are shown in sequence according to the indication of the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless there is a clear indication in this article, the execution of these steps has no strict order limit, and they can be executed in other orders. Moreover, at least a part of the steps in the flowchart of the accompanying drawings may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily executed at the same time, but can be executed at different times, and their execution order is not necessarily sequential, but can be executed alternately or alternately with at least a part of other steps or sub-steps or stages of other steps.

[0061] The above are only partial implementation manners of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A DC solid-state circuit breaker self-powered circuit based on capacitor voltage division, characterized in that: The DC solid-state circuit breaker self-powered circuit based on capacitor voltage division includes: a self-powered unit, a control circuit, a drive circuit, and a DC solid-state circuit breaker; the self-powered unit includes a power switch, a capacitor voltage division circuit, and a DC / DC converter; The DC solid-state circuit breaker is connected in series to the DC bus, the first end of the power switch is connected to the drive circuit, the second end of the power switch is connected to the DC bus, the third end of the power switch is connected to the capacitor voltage divider circuit, the capacitor voltage divider circuit is connected to the control circuit and the DC / DC converter, and the drive circuit is connected to the DC / DC converter, the control circuit and the DC solid-state circuit breaker; The capacitor voltage divider circuit includes: a first resistor, a second resistor, a first capacitor and a second capacitor; the first resistor and the first capacitor are connected in series, and the third end of the power switch is connected to the first resistor, the first end of the second capacitor is connected to the first capacitor, and is also connected to the control circuit and the DC / DC converter, the second end of the second capacitor is grounded, and is also connected to the control circuit and the DC / DC converter; one end of the second resistor is connected to an end of the first resistor away from the first capacitor, and the other end is connected to the first end of the second capacitor; The control circuit compares the sampling voltage vin on the second capacitor with the high threshold V H , low threshold V L Compare, if , the control circuit outputs a high level, the drive circuit outputs a conduction signal to control the power switch to conduct, and the bus voltage charges the first capacitor and the second capacitor through the first resistor; if , the control circuit outputs a low level, the drive circuit outputs a cut-off signal to control the power switch J1 to turn off, at this time the first capacitor discharges through the second resistor and the first resistor, the voltage drops, and the voltage across the second capacitor is consumed by the DC / DC converter; if , the control circuit keeps the output level unchanged, that is, if the output level of the control circuit at the previous moment is a high level, the control circuit currently outputs a high level, if the output level of the control circuit at the previous moment is a low level, the control circuit currently outputs a low level.

2. The DC solid-state circuit breaker self-powered circuit based on capacitor voltage division according to claim 1, characterized in that: The high threshold VH is the highest input voltage of the DC / DC converter, and the low threshold VL is the lowest input voltage of the DC / DC converter.

3. The DC solid-state circuit breaker self-powered circuit based on capacitor voltage division according to claim 1, characterized in that: The capacitance value of the first capacitor is greater than the capacitance value of the second capacitor.

4. The DC solid-state circuit breaker self-powered circuit based on capacitor voltage division according to claim 1, characterized in that: The DC / DC converter is a step-down isolation conversion device, which is used to step down and isolate the sampled voltage on the second capacitor and then output a stable power supply voltage to supply power to the subsequent control circuit, the drive circuit and the DC solid-state circuit breaker.

5. The DC solid-state circuit breaker self-powered circuit based on capacitor voltage division according to claim 1, characterized in that: The power switch is a silicon carbide junction field effect transistor, the first end is a gate, the second end is a drain, and the third end is a source.

6. A control method for a DC solid-state circuit breaker self-powered circuit based on capacitor voltage division according to any one of claims 1 to 5, characterized in that: The control method comprises: The DC bus voltage is divided by a capacitor voltage divider circuit and input into the DC / DC converter; Collecting a sample voltage input into the DC / DC converter through a control circuit; The control circuit compares the sampled voltage with a preset high threshold and a preset low threshold respectively, and outputs a control signal to the drive circuit according to the comparison result; The driving circuit outputs a first driving signal according to the control signal to control the on and off of the power switch, thereby controlling the DC / DC converter to output a stable power supply voltage; The capacitor voltage divider circuit includes: a first resistor, a second resistor, a first capacitor and a second capacitor; the first resistor and the first capacitor are connected in series, and the third end of the power switch is connected to the first resistor, the first end of the second capacitor is connected to the first capacitor, and is also connected to the control circuit and the DC / DC converter, the second end of the second capacitor is grounded, and is also connected to the control circuit and the DC / DC converter; one end of the second resistor is connected to an end of the first resistor away from the first capacitor, and the other end is connected to the first end of the second capacitor; The control circuit compares the sampling voltage vin on the second capacitor with the high threshold V H , low threshold V L Compare, if , the control circuit outputs a high level, the drive circuit outputs a conduction signal to control the power switch to conduct, and the bus voltage charges the first capacitor and the second capacitor through the first resistor; if , the control circuit outputs a low level, the drive circuit outputs a cut-off signal to control the power switch J1 to turn off, at this time the first capacitor discharges through the second resistor and the first resistor, the voltage drops, and the voltage across the second capacitor is consumed by the DC / DC converter; if , the control circuit keeps the output level unchanged, that is, if the output level of the control circuit at the previous moment is a high level, the control circuit currently outputs a high level, if the output level of the control circuit at the previous moment is a low level, the control circuit currently outputs a low level.

7. The control method according to claim 6, characterized in that: The step of outputting a first drive signal according to the control signal by the drive circuit to control the on and off of the power switch, thereby controlling the DC / DC converter to output a stable power supply voltage, comprises: If the control circuit outputs a high-level control signal, the drive circuit outputs a conduction signal according to the control signal to control the power switch to be turned on, the DC bus voltage charges the first capacitor and the second capacitor in the capacitor voltage divider circuit, the voltage across the second capacitor rises, and the voltage across the second capacitor is controlled to be higher than the low threshold; If the control circuit outputs a low-level control signal, the drive circuit outputs a cutoff signal according to the control signal to control the power switch to turn off, the first capacitor discharges through the first resistor and the second resistor, the second capacitor consumes power through the DC / DC converter, and the voltage across the second capacitor is controlled to be lower than the high threshold.

8. The control method according to claim 6, characterized in that: The driving circuit also outputs a second driving signal to the DC solid-state circuit breaker to control the on and off of the DC solid-state circuit breaker.

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