Capacitive voltage division-based direct-current solid-state circuit breaker self-powered circuit and control method thereof

Abstract

The invention provides a direct-current solid-state circuit breaker self-powered circuit based on capacitive voltage division and a control method thereof. The circuit comprises a self-powered unit, a control circuit, a driving circuit and a direct-current solid-state circuit breaker, the self-powered unit comprises a power switch, a capacitance voltage division circuit and a DC / DC converter; the direct-current solid-state circuit breaker is connected to a direct-current bus in series, the first end of the power switch is connected with the driving circuit, the second end of the power switch is connected with the direct-current bus, the third end of the power switch is connected with the capacitance voltage division circuit, and the capacitance voltage division circuit is connected with the control circuit and the DC / DC converter. And the driving circuit is connected with the DC / DC converter, the control circuit and the direct-current solid-state circuit breaker. A capacitor is used for carrying out voltage division and reduction on a direct-current bus, stable power supply voltage is provided after isolation and voltage transformation are carried out through a DC / DC converter, and it is guaranteed that the direct-current solid-state circuit breaker can be controlled and monitored in real time no matter in a normal state or a fault removal state.

Description

Technical Field

[0001] The present application belongs to the technical field of direct current distribution system protection, and in particular, relates to a direct current solid-state circuit breaker self-power supply circuit based on capacitor voltage division and a control method thereof. Background Art

[0002] Compared with AC power systems, DC power systems have more advantages in reducing energy loss and being compatible with new energy and DC loads. However, the low impedance and low inertia of DC power grid systems result in a high rate of rise and large amplitude of fault current, which places strict requirements on the fault response speed of DC solid state circuit breakers (SSCBs). In addition, since the DC short-circuit fault current does not have a natural zero crossing, arc management during fault clearing becomes more challenging, making the isolation of DC faults more difficult than AC faults. As an important part of the DC power system, DC solid state circuit breakers play a key role in achieving fault isolation, preventing further spread of DC faults, and ensuring 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 lifespan is short, and it is difficult to meet the requirements of intelligent control and fast fault removal.

[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 shutdown speed and difficult arc extinguishing. However, power devices represented by silicon carbide (SiC) require external power supply to work properly due to the existence of control and drive circuits, and the existence of auxiliary power supply lines not only increases the cost of circuit breakers, but also increases the complexity of equipment. Even in some occasions, such as the seabed observation network, there is no auxiliary power supply line. Therefore, realizing self-power supply of DC solid-state circuit breakers can improve the reliability of power system operation and reduce operating costs. In the existing methods, there is a method of obtaining electric energy by using the voltage drop generated by the short-circuit current flowing through the power semiconductor device when a fault occurs. The voltage drop on the power semiconductor device is used as a trigger voltage to cut off the fault current in the event of a short-circuit fault. This method of obtaining power is simple and easy. However, when the DC system is operating normally, the DC solid-state circuit breaker is in a power-off state and cannot be controlled and monitored in real time. Therefore, it is necessary to propose a reasonable self-power supply method for the circuit breaker to ensure the power supply stability of the circuit breaker, and to perform real-time control and monitoring regardless of whether the circuit breaker is in a normal state or a fault removal state. Summary of the invention

[0004] The main purpose of the embodiments of the present invention is to provide a DC solid-state circuit breaker self-powered circuit based on capacitor voltage division and a control method thereof, which can use capacitors to divide and reduce the voltage of the DC bus, and provide a stable power supply voltage after isolation and transformation through a DC / DC converter, thereby ensuring that the DC solid-state circuit breaker can be controlled and monitored in real time regardless of whether it is in a normal state or a fault clearing state.

[0005] In a first aspect, a self-powered circuit of a DC solid-state circuit breaker based on capacitor voltage division is provided, comprising: a self-powered unit, a control circuit, a drive circuit, and a DC solid-state circuit breaker; the self-powered unit comprises a power switch, a capacitor voltage division circuit, and a DC / DC converter; the DC solid-state circuit breaker is connected in series to a DC bus, a first end of the power switch is connected to the drive circuit, a second end of the power switch is connected to the DC bus, a third end of the power switch is connected to the capacitor voltage division circuit, the capacitor 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 one possible implementation, the capacitor voltage divider 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, and 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 divider circuit further includes a second resistor, one end of the second resistor is connected to an end of the first resistor away from the first capacitor, and the other end of the second resistor 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 the capacitance value 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 then output a stable supply voltage to supply power to subsequent control circuits, drive circuits and DC solid-state circuit breakers.

[0010] In another possible implementation, 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.

[0011] In a second aspect, a control method for the aforementioned capacitor-based DC solid-state circuit breaker self-powered circuit is provided, the control method comprising: dividing the DC bus voltage through a capacitor voltage divider circuit and inputting the voltage into a DC / DC converter; collecting a sampled voltage input into the DC / DC converter through a control circuit; comparing the sampled voltage with a preset high threshold and a low threshold respectively through the control circuit, and outputting a control signal to a drive circuit according to the comparison result; and outputting a first drive signal through the drive circuit 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.

[0012] In another possible implementation, a control signal is output to a driving circuit based on a comparison result, including: if the sampling voltage is less than or equal to a preset low threshold, the control circuit outputs a high-level control signal; if the sampling voltage is greater than a preset high threshold, the control circuit outputs a low-level control signal; if the sampling 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.

[0013] In another possible implementation, 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, including: if the control circuit outputs a high-level control signal, the driving circuit outputs an on-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 a low threshold; if the control circuit outputs a low-level control signal, the driving circuit outputs a cut-off signal according to the control signal to control the power switch to be turned 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 a high threshold. BRIEF 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 use in describing the embodiments of the present application are briefly introduced below.

[0015] Figure 1 A schematic diagram of a DC solid-state circuit breaker self-powered circuit based on capacitor voltage division provided by an embodiment of the present invention; Figure 2 A timing diagram of a DC solid-state circuit breaker self-power supply circuit based on capacitor voltage division provided in an embodiment of the present invention; Figure 3 A schematic diagram of a simulation circuit of a DC solid-state circuit breaker self-power supply circuit based on capacitor voltage division provided in an embodiment of the present invention; Figure 4A schematic diagram of simulation results of a DC solid-state circuit breaker self-powered circuit based on capacitor voltage division provided in an embodiment of the present invention; Figure 5 A flow chart of a method for controlling a self-powered circuit of a DC solid-state circuit breaker based on capacitor voltage division is provided as an embodiment of the present invention. DETAILED DESCRIPTION

[0016] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar modules or modules with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be interpreted as limiting the present invention.

[0017] It will be understood by those skilled in the art that, unless expressly stated, the singular forms "a", "an", "said" and "the" used herein may also include plural forms. It should be further understood that the term "comprising" used in the specification of the present application refers to the presence of the 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 refer to a module as being "connected" or "coupled" to another module, it may be directly connected or coupled to the other modules, or there may be intermediate modules. In addition, the "connection" or "coupling" used herein may include wireless connection or wireless coupling. The term "and / or" used herein includes all or any modules and all combinations of one or more associated listed items.

[0018] In order to make the objectives, technical solutions and advantages of the present application clearer, the implementation method of the present application will be further described in detail below with reference to the accompanying drawings.

[0019] The technical solution of the present application and how to solve the above-mentioned technical problems are described in detail below with specific embodiments. The following specific embodiments 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 in conjunction with the accompanying drawings.

[0020] Figure 1 A DC solid-state circuit breaker self-powered circuit based on capacitor voltage division is provided in an embodiment of the present invention. Figure 1As shown, the self-powered circuit of the DC solid-state circuit breaker 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 J1, 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 J1 is connected to the drive circuit, the second end of the power switch J1 is connected to the DC bus, the third end of the power switch J1 is connected to the capacitor voltage division circuit, the capacitor 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.

[0021] The capacitor voltage divider 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, and the third end of the power switch J1 is connected to the first resistor R1. in The first end of the first capacitor C1 is connected to the control circuit and the DC / DC converter, and the second capacitor C in The second end of is grounded and connected to the control circuit and the DC / DC converter. The capacitor voltage divider circuit also includes a second resistor R2, one end of which is connected to the end of the first resistor R1 away from the first capacitor C1, and the other end is connected to the second capacitor C in The capacitance value of the first capacitor C1 is greater than that of the second capacitor C in The power switch J1 is a silicon carbide junction field effect transistor SiC JFET, the first end is the gate, the second end is the drain, and the third end is the source. The first resistor R1 is a charging current limiting resistor, and the second resistor R2 is a discharge resistor. The embodiment of the present invention utilizes two capacitors of different capacitance values ​​connected in series to achieve voltage division and voltage reduction of the DC bus voltage, and the bus voltage is divided and reduced by using capacitors in series, so that real-time control and monitoring can be performed regardless of whether the circuit breaker is in a normal state or a fault removal state.

[0022] 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, drive circuit and DC solid-state circuit breaker. The voltage on the low-voltage capacitor is converted into a low-voltage power supply voltage through the DC / DC converter, thereby ensuring the stable self-power supply of the SSCB control system.

[0023] In the embodiment of the present invention, the self-power supply unit is composed of a power switch J1, a charging current limiting resistor R1, a discharge resistor R2 and a series voltage-dividing and voltage-reducing capacitor C1, C in J1 is used as a power switch device to control capacitors C1 and C in When the power switch J1 is turned on, the bus voltage is supplied to the first capacitor C1 and the second capacitor C inIn terms of parameter selection, the first capacitor C1 should be a small capacitor with high withstand voltage, and the second capacitor C in Choose a capacitor with a large capacitance value. Then, the first capacitor C1 can bear a larger bus voltage, and the second capacitor C in The first capacitor C1 is discharged through the second resistor R2 and the first resistor R1, and the second capacitor C in The charge on the capacitor C is consumed by the DC / DC converter. The DC / DC converter acts as a step-down isolation conversion device. in The voltage on the power supply is reduced and isolated to supply power to the subsequent control circuit and drive circuit. The control circuit controls the high and low level waves of the drive circuit to realize the opening and closing of the power switch J1 and the DC solid-state circuit breaker. The drive circuit receives the control circuit signal and realizes the opening and closing of the power switch J1 and the DC solid-state circuit breaker through the PWM signal.

[0024] The principle of the control circuit in the embodiment of the present invention is as follows: for the second capacitor C in The voltage on the high threshold V H and low threshold V L , the second capacitor C in The sampled voltage v in Compare with the two to control the PWM output of the driving circuit. H The maximum input voltage of the DC / DC converter, the low threshold V L It is the minimum input voltage of the DC / DC converter.

[0025] The following is a detailed analysis of the implementation process of the capacitor voltage divider SSCB self-powered circuit to provide a theoretical basis for the selection of equipment parameters.

[0026] In the embodiment of the present invention, the capacitor voltage divider circuit is composed of a first resistor R1, a first capacitor C1, and a second capacitor C in The bus voltage is divided, and the control circuit collects the second capacitor C in The sampling voltage v at both ends in , the sample voltage v in With high threshold V H and low threshold V L Compare.

[0027] if , the control circuit outputs a high level, and the drive circuit outputs a conduction signal to control the power switch J1 to conduct. At this time, the bus voltage is connected to the first capacitor C1 and the second capacitor C through the first resistor R1. in Charging, the second capacitor C in The voltage at both ends rises to ensure that the sampling voltage vin Higher than the minimum input voltage V of the DC / DC converter L .

[0028] if , 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 drops. in The voltage at both ends is consumed by the DC / DC converter to ensure the sampling voltage v in Lower than the maximum input voltage V of the DC / DC converter H .

[0029] 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.

[0030] This ensures that the second capacitor C in The sampling voltage v at both ends in The minimum input voltage V of the DC / DC converter L With the maximum input voltage V H Thus, the DC / DC converter can provide a stable power supply voltage.

[0031] Assume that the first capacitor C1 and the second capacitor C in The voltage in the initial state is 0, the output voltage of the DC / DC converter is 12V, the control signal of the control circuit is 5V, and the DC system operates normally. The timing analysis of the implementation process of the DC solid-state circuit breaker self-powered circuit based on capacitor voltage division in the embodiment of the present invention is as follows. For specific timing, see Figure 2 .

[0032] Phase I (0-t0): Due to the first capacitor C1 and the second capacitor C in The voltage of the initial state is 0, and the second capacitor C in The sampling voltage v at both ends in =0 <V L The control circuit outputs a high level, and the drive circuit outputs a conduction signal to control the power switch J1 to conduct. The line voltage is connected to the first capacitor C1 and the second capacitor C through the first resistor R1. in Charging, the second capacitor C in The sampling voltage v at both ends in rise.

[0033] Phase II (t0-t1): When v in >V L When the sampling voltage v inHigher than the minimum input voltage V of the DC / DC converter L , the DC / DC converter starts to work normally, outputs a stable supply voltage, and ensures the normal operation of the control circuit and the drive circuit. And because the SiC JFET device itself is a normally-on device, it remains on in the absence of a drive voltage and can be regarded as a conductor. Therefore, before the DC / DC converter outputs stably, the second capacitor C in It can be charged normally. The control circuit logic remains unchanged at this stage.

[0034] Phase III (t1-t2): When v in >V H When 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 C1 discharges through the second resistor R2 and the first resistor R1, and the second capacitor C in The voltage across the two ends is consumed by the DC / DC converter, and the voltage v in Start to descend.

[0035] Stage IV (t2-t3): After a certain period of discharge, , the control circuit outputs a high level, the second capacitor C in Recharge, v in Rise, cycle, maintain , thus ensuring the stable output of the DC / DC converter. And because the self-power supply unit is connected in parallel to the DC bus side and is charged by the bus voltage, even if the circuit breaker disconnects the subsequent circuit, the self-power supply unit can still ensure normal operation and make the DC / DC converter output a stable supply voltage.

[0036] The DC solid-state circuit breaker self-powered circuit based on capacitor voltage division in the embodiment of the present invention divides and reduces the voltage of the DC bus by capacitors during the normal operation of the SSCB, and provides a stable power supply voltage for the control circuit and the drive circuit after isolation and voltage transformation by the DC / DC converter. And after the SSCB removes the fault and disconnects the subsequent circuit, it can still provide a stable power supply voltage, ensuring that the SSCB can be controlled and monitored in real time regardless of whether it is in a normal state or a fault removal state.

[0037] In order to verify the effectiveness of the DC solid-state circuit breaker self-powered circuit based on capacitor voltage division according to the embodiment of the present invention, the feasibility of the topology can be verified by PSpice simulation. Figure 3 As shown, the DC solid-state circuit breaker self-powered circuit based on capacitor voltage division of the embodiment of the present invention is connected to the simulation circuit, and the DC solid-state circuit breaker is driven to open and close through VPULSE. Figure 1 VPULSE is the VPULSE pulse voltage source inside PSpice, and DC uses the built-in DC voltage source V in PSpice.DC , load R L It is a pure resistive load of 10Ω.

[0038] The device parameters in the simulation circuit are shown in Table 1. The simulation model of SiC JFET comes from UnitedSiC, USA. The bus voltage is set to 1000V. The driving voltage of J1 in the self-powered unit is provided by the driver chip UCC21530. in By connecting in parallel to C in The resistors at both ends divide the voltage and input the comparator TLV3501 to control the drive signal of the driver chip UCC21530. The DC / DC converter is replaced by a simple buck circuit. Observe the capacitor C in The voltage waveform at both ends, the output voltage waveform of the buck circuit, and the waveforms of the two after the DC solid-state circuit breaker is turned off can test the implementation effect of the DC solid-state circuit breaker self-powered circuit based on capacitor voltage division in the simulation circuit, and verify the feasibility of the DC solid-state circuit breaker self-powered circuit based on capacitor voltage division.

[0039] Table 1 Device parameters of DC solid-state circuit breaker self-powered circuit based on capacitor voltage division The simulation results of the DC solid-state circuit breaker self-powered circuit based on capacitor voltage division are shown in Figure 4 As shown, the self-powered circuit and the load R L When the circuit is connected at 100us, the load current rises rapidly to 100A because the bus voltage is 1000V. in The initial voltage state of both ends is 0, so TLV3501 outputs 5V high level, controls the driver chip UCC21530 to output the conduction signal, the power switch J1 is turned on, and the second capacitor C in Start charging, sample voltage v in The buck circuit starts to work at 5ms. The buck circuit output voltage stabilizes at 10V at 10ms. At 12ms, the buck circuit output voltage stabilizes at 10V. in Reaching the high threshold V H , TLV3501 outputs 0V low level, controls the driver chip UCC21530 to output a cut-off signal, the power switch J1 is turned off, and the second capacitor C in The charge on the buck circuit is consumed, v in Falling, 31ms v in Reaching the low threshold V L , TLV3501 outputs 5V high level again, and the cycle continues to ensure v inAlways within the input range of the DC / DC converter, the supply voltage can be output stably. At 60ms, VPLUSE outputs a shutdown signal, the DC solid-state circuit breaker is turned off, the fault removal after the simulated line fault is simulated, 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.

[0040] In summary, the self-powered circuit of a DC solid-state circuit breaker based on capacitor voltage division in an 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 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 division circuit, the capacitor 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, the DC bus is divided and reduced by a capacitor, and a stable power supply voltage is provided after isolation and transformation by a DC / DC converter, to ensure that the DC solid-state circuit breaker can be controlled and monitored in real time regardless of whether it is in a normal state or a fault removal state.

[0041] like Figure 5 The flowchart of a control method of a DC solid-state circuit breaker self-powered circuit based on capacitor voltage division provided by an embodiment of the present invention is shown. The control method includes: Step S11, dividing the DC bus voltage through a capacitor voltage divider circuit and inputting the divided voltage into a DC / DC converter.

[0042] In the embodiment of the present invention, the capacitor voltage divider circuit is composed of a first resistor R1, a first capacitor C1, and a second capacitor C in The bus voltage is divided. The second capacitor C obtained by voltage division in The voltage at both ends is input into the DC / DC converter as the input voltage of the DC / DC converter.

[0043] Step S12: collecting a sample voltage input to the DC / DC converter through a control circuit.

[0044] The second capacitor C is collected by the control circuit in The voltage across the two ends is the sampling voltage of the input DC / DC converter.

[0045] In step S13, the control circuit compares the sampled voltage with a preset high threshold and a preset low threshold, and outputs a control signal to the drive circuit according to the comparison result.

[0046] Optionally, if the sampled voltage is less than or equal to a preset low threshold, the control circuit outputs a high-level control signal. If the sampled voltage is greater than a preset high threshold, the control circuit outputs a low-level control signal. 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.

[0047] Step S14: 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.

[0048] 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 conduct, 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, that is, to ensure that the second capacitor C in The sampling voltage v at both ends in Higher than the minimum input voltage V of the DC / DC converter L .

[0049] 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, 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, that is, to ensure that the second capacitor C in The sampling voltage v at both ends in Lower than the maximum input voltage V of the DC / DC converter H .

[0050] Through the above control, the second capacitor C in The sampling voltage v at both ends in The minimum input voltage V of the DC / DC converter L With the maximum input voltage V H Thus, the DC / DC converter can provide a stable power supply voltage.

[0051] 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.

[0052] In the embodiment of the present invention, two capacitors with different capacitances are connected in series to realize the voltage division and voltage reduction 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 is connected in series with the DC to divide and reduce the bus voltage, real-time control and monitoring can be performed regardless of whether the circuit breaker is in a normal state or a fault clearing state.

[0053] It should be understood that, although the steps in the flowchart of the accompanying drawings are displayed in sequence as indicated by the arrows, these steps are not necessarily executed in sequence in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order restriction on the execution of these steps, 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, and 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 in turn or alternately with other steps or at least a part of the sub-steps or stages of other steps.

[0054] The above is only a partial implementation 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 principles of the present invention. These improvements and modifications should also be regarded as the scope of protection 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.

2. The DC solid-state circuit breaker self-powered circuit based on capacitor voltage division according to claim 1, characterized in that: The capacitor voltage divider 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, and the second end of the second capacitor is grounded, and is also connected to the control circuit and the DC / DC converter.

3. The DC solid-state circuit breaker self-powered circuit based on capacitor voltage division according to claim 2, characterized in that: The capacitive voltage divider circuit further includes a second resistor, one end of the second resistor is connected to an end of the first resistor away from the first capacitor, and the other end of the second resistor is connected to the first end of the second capacitor.

4. The DC solid-state circuit breaker self-powered circuit based on capacitor voltage division according to claim 2, characterized in that: The capacitance value of the first capacitor is greater than the capacitance value of the second capacitor.

5. The DC solid-state circuit breaker self-powered circuit based on capacitor voltage division according to claim 2, 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.

6. 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.

7. 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 6, 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.

8. The control method according to claim 7, characterized in that: The step of outputting a control signal to the driving circuit according to the comparison result comprises: If the sampling voltage is less than or equal to a preset low threshold, the control circuit outputs a high-level control signal; If the sampling voltage is greater than a preset high threshold, the control circuit outputs a low level control signal; If the sampled voltage is greater than the lower threshold and less than or equal to the upper threshold, the control circuit maintains the control signal of the previous state.

9. The control method according to claim 7, 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 be turned 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.

10. The control method according to claim 7, 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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