Unidirectional DC switch and operating method therefor

Abstract

The present disclosure relates to a unidirectional DC switch and an operating method therefor. According to one embodiment of the present disclosure, provided is a unidirectional DC current interruption device comprising a mechanical main switch, first and second switches, a capacitor, and first and second resistors. When the main switch is turned off, the second switch is turned on so that a reverse current is supplied to the main switch by a discharge current of the capacitor, thereby forming a current zero point and extinguishing an arc. In addition, by adjusting the resistance value of a capacitor charging circuit and the time constant of an inductor, the magnitude of the reverse current and the interruption time can be controlled, thereby stably and quickly interrupting the DC current.

Description

Unidirectional DC Switch and Method of Operation

[0001] The present disclosure relates to a unidirectional DC switch and a method of operating the same.

[0002] The following description merely provides background information related to the present embodiment and does not constitute prior art.

[0003] A direct current (DC) switch is an electrical device used to connect or disconnect a direct current power source. DC switches are used in various electronic devices, battery systems, solar power generation, electric vehicle charging infrastructure, and High Voltage Direct Current (HVDC) transmission networks.

[0004] In alternating current (AC) networks, switching and interruption are easy because the current periodically passes through a zero point. However, in direct current networks, there is no natural current zero point, and an electric arc is generated between the contacts separated by the switch. This causes the contacts to degrade, which adversely affects the dielectric strength and shortens the lifespan of the switch.

[0005] Accordingly, DC circuit breakers or switches capable of generating an artificial zero current point have been developed and are being used.

[0006] This technology, classified as an Active Current Injection method, discharges a charged capacitor through various switching switches (e.g., mechanical switches, spark gaps, thyristors, semiconductor switches, etc.) to block DC. In this process, an LC resonant current is injected in the opposite direction to the DC to block the DC.

[0007] For DC switches, a bidirectional method is preferred for DC circuit breakers, while a unidirectional method is generally used for DC load switches. To use the bidirectional method, a circuit for reversing the polarity of the capacitor is required. Capacitor charging can be configured using the system voltage or a separate charging circuit.

[0008] Conventional technology using a separate capacitor charging circuit makes it difficult to control the magnitude of the LC resonant current due to the physical size issues of the inductor (L) and capacitor (C). In addition, if the reverse current is too large when the load current is cut off, there is a problem in that the remaining reverse current flows to the load side even after the DC is cut off.

[0009] Conventional technology for charging a capacitor using system voltage has a limitation in that the capacitor cannot be used as a unidirectional DC switch because it generates an LC resonant current in the same direction as the DC.

[0010] The present disclosure aims to provide a unidirectional DC current blocking device and a method of operation thereof that charges a capacitor with a system voltage and controls the magnitude of a reverse current to generate a current zero point through an RLC circuit.

[0011] The problems that the present invention aims to solve are not limited to those mentioned above, and other unmentioned problems will be clearly understood by a person skilled in the art from the description below.

[0012] According to one embodiment of the present disclosure, a unidirectional DC current blocking device is provided, comprising: a mechanical main switch for blocking a DC current; a first switch for blocking a residual current of a system in response to the completion of the blocking operation of the main switch; a capacitor charged with the DC current; a second switch for generating a reverse current; a first resistor; and a second resistor, wherein one end of the first switch is connected to a circuit on one side, the other end of the first switch is connected to one end of the main switch and one end of the second switch, the other end of the main switch is connected to one end of the capacitor and one end of the capacitor, the other end of the second switch is connected to one end of the first resistor, and the other end of the first resistor is connected to one end of the capacitor and one end of the second resistor, and the second switch is turned on in response to the main switch being turned off, thereby discharging the capacitor and generating a reverse current in the opposite direction to the DC current, and supplying the reverse current to the main switch.

[0013] In the above-mentioned unidirectional DC current blocking device, the second switch, the first resistor, and the capacitor constitute a reverse current generating circuit.

[0014] In the above-mentioned unidirectional DC current blocking device, the capacitor and the second resistor form a charging circuit.

[0015] Due to the above reverse current, the current in the main switch becomes zero, and the arc generated by the turning off of the main switch can be extinguished.

[0016] The above unidirectional DC current blocking device further includes a second resistor installed between the capacitor and ground, and can adjust the time required to charge the capacitor and the magnitude of the charging current based on the resistance value of the second resistor.

[0017] The above unidirectional DC current blocking device further includes an inductor between the second switch and the first resistor, and can adjust the completion time of the DC current blocking based on the time constant of the inductor and the first resistor.

[0018] The above unidirectional DC current blocking device may further include a non-linear resistor element connected in parallel to the main switch to suppress the inrush voltage generated when the main switch is turned off or to absorb residual energy.

[0019] The second switch mentioned above may be a mechanical switch, a semiconductor switch, or a hybrid switch.

[0020] According to another embodiment of the present disclosure, a method performed by a unidirectional DC current blocking device comprises: a process of charging a capacitor using a DC current; a process of turning off a main switch according to a control signal for blocking the DC current; a process of turning on a second switch to generate a reverse current in response to the main switch being turned off; and a process of turning off a first switch in response to the generation of a current zero point in the main switch by the generated reverse current.

[0021] According to an embodiment of the present disclosure, the design of a DC current interruption device can be simplified and the configuration cost reduced.

[0022] According to an embodiment of the present disclosure, fault current and load current can be stably and quickly cut off.

[0023] The effects of the present disclosure are not limited to those mentioned above, and other unmentioned effects will be clearly understood by a person skilled in the art from the description below.

[0024] FIG. 1 is a diagram showing the configuration of a unidirectional DC current blocking device according to one embodiment of the present disclosure.

[0025] FIG. 2 is a diagram showing the configuration of a unidirectional DC current blocking device according to another embodiment of the present disclosure.

[0026] FIG. 3 is a diagram showing the current flow during capacitor charging according to one embodiment of the present disclosure.

[0027] FIG. 4 is a diagram showing the current flow after the capacitor charging is completed according to one embodiment of the present disclosure.

[0028] FIGS. 5a to 5d are drawings for explaining a DC current interruption process according to one embodiment of the present disclosure.

[0029] FIG. 6 is a flowchart of a method performed by a unidirectional DC current blocking device according to one embodiment of the present disclosure.

[0030] FIG. 7 is a diagram showing changes in main current, reverse current, and voltage across the main switch during the operation of a unidirectional DC current blocking device according to one embodiment of the present disclosure.

[0031] Some embodiments of the present disclosure are described in detail below with reference to exemplary drawings. It should be noted that in assigning reference numerals to the components of each drawing, the same components are given the same reference numeral whenever possible, even if they are shown in different drawings. Furthermore, in describing the present disclosure, if it is determined that a detailed description of related known components or functions could obscure the essence of the present disclosure, such detailed description is omitted.

[0032] In describing the components of the embodiments according to the present disclosure, symbols such as first, second, i), ii), a), b), etc., may be used. These symbols are intended only to distinguish the components from other components, and the essence, order, or sequence of the components is not limited by the symbols. When a part in the specification is described as 'comprising' or 'having' a component, this means that, unless explicitly stated otherwise, it does not exclude other components but may include additional components. Furthermore, terms such as 'part' or 'module' described in the specification refer to a unit that processes at least one function or operation, and this may be implemented in hardware, software, or a combination of hardware and software.

[0033] The detailed description set forth below, together with the accompanying drawings, is intended to describe exemplary embodiments of the present disclosure and is not intended to represent the only embodiment in which the present disclosure may be practiced.

[0034] The present disclosure relates to a unidirectional DC current interruption device and a method of operation thereof. Specifically, it provides a unidirectional DC current interruption technology that charges a capacitor with a system voltage and controls the magnitude of a reverse current to generate a current zero point through an RLC circuit.

[0035] FIG. 1 is a diagram showing the configuration of a unidirectional DC current blocking device according to one embodiment of the present disclosure.

[0036] In this specification, the term 'turn-on' may be used interchangeably with 'closed' or 'closed pole', and the term 'turn-off' may be used interchangeably with 'open' or 'open pole'.

[0037] In this specification, if one end of a specific element or circuit is the right end of the specific element or circuit, the other end of the specific element or circuit may be the left end of the specific element or circuit. If one end of a specific element or circuit is the left end of the specific element or circuit, the other end of the specific element or circuit may be the right end of the specific element or circuit.

[0038] In this specification, the term "one side" refers to the power source side in a DC system, and the term "other side" refers to the load side. However, this is for the convenience of explanation and the present disclosure is not limited thereto.

[0039] Referring to FIG. 1, a unidirectional DC current blocking device (100) according to one embodiment of the present disclosure includes a first switch (110), a main switch (120), a second switch (130), a capacitor (140), a first resistor (150), and a second resistor (160). The unidirectional DC current blocking device (100) may further include a control unit (not shown) that controls the overall operation of the components. For example, the control unit may generate a signal to control the operation of the first switch, the main switch, and / or the second switch.

[0040] The first switch (110) is a residual current cutoff switch that cuts off the residual current of the system after the cutoff operation of the main switch (120) is completed. The first switch (110) is installed between the power supply side circuit and the main switch (120). One end of the first switch (110) is connected to the power supply side circuit, and the other end is connected to one end of the main switch (120). The first switch (110) can be turned on when DC current is applied, and can be turned off when the DC current cutoff operation is completed.

[0041] The main switch (120) acts as a break switch to cut off the current when a fault occurs on either side of the DC line, or to safely cut off the current under load conditions. The main switch (120) is installed between the first switch (110) and the load-side circuit. One end of the main switch (120) is connected to the other end of the first switch (110), and the other end is connected to one end of the capacitor (140) and the load-side circuit.

[0042] The main switch (120) is a mechanical switch that remains in a turned-on state in a normal state and can be turned off according to a control signal to cut off a fault current or load current. When the main switch (120) is turned off, an arc may occur. Due to the arc generated in the main switch (120), the DC current may not be cut off and may continue to flow.

[0043] The capacitor (140) can be charged with DC current. The DC current supplied to the DC line can be supplied to the capacitor (140) through the main switch (120), and the capacitor (140) can be charged by the DC current. The capacitor (140) is installed between the contact connecting the main switch (120) and the load-side circuit and the second resistor (160). One end of the capacitor (140) is connected to the other end of the main switch (120) and the load-side circuit, and the other end is connected to the second resistor (160).

[0044] At this time, the capacitor (140) and the second resistor (160) form a capacitor charging circuit, and the time required for charging and the magnitude of the charging current are adjusted by the second resistor (160).

[0045] Additionally, the capacitor (140), the second switch (130), and the first resistor (150) form a reverse current generating circuit and generate a reverse current to create a current zero point during the DC current blocking process through discharge.

[0046] The second switch (130) acts as a making switch to supply reverse current to the main switch (120). The second switch (130) remains in a turned-off state in normal conditions and can be turned on according to a control signal to cut off the DC current. The second switch (130) is installed between the contact point connecting the first switch (110) and the main switch (120) and the first resistor (150). One end of the second switch (130) is connected to the other end of the first switch (110) and one end of the main switch (120), and the other end is connected to one end of the first resistor (150). When the second switch (130) is turned on, reverse current is generated by the discharge of the capacitor (140) and supplied to the main switch (120). The second switch (130) may include various forms such as a mechanical switch, a semiconductor switch, or a hybrid switch, but is not limited thereto.

[0047] The first resistor (150) is installed between the contact point where the capacitor (140) and the second resistor (160) are connected and the second switch (130). One end of the first resistor (150) is connected to the other end of the second switch (130), and the other end is connected to the other end of the capacitor (140) and one end of the second resistor (160).

[0048] The second resistor (160) serves to adjust the time required to charge the capacitor (140) and the magnitude of the charging current. The second resistor (160) may be configured as a variable resistor. The second resistor (160) is installed between the capacitor (140) and ground. One end of the second resistor (160) is connected to the other end of the capacitor (140), and the other end is grounded.

[0049] Meanwhile, when the switching surge voltage of the main switch (120) is large and the residual energy of the system is large after the DC current is cut off, it is necessary to absorb the residual energy. In addition, depending on the requirements, it may be necessary to secure a faster cutoff time.

[0050] FIG. 2 is a diagram showing the configuration of a unidirectional DC current blocking device according to another embodiment of the present disclosure.

[0051] Referring to FIG. 2, a unidirectional DC current blocking device (100) according to another embodiment of the present disclosure includes a first switch (110), a main switch (120), a second switch (130), a capacitor (140), a first resistor (150), a second resistor (160), an inductor (170), and a non-linear resistor element (180). That is, a unidirectional DC current blocking device (100) according to another embodiment of the present disclosure includes all the same components as FIG. 1 and further includes an inductor (170) and a non-linear resistor element (180).

[0052] The first switch (110), main switch (120), second switch (130), capacitor (140), first resistor (150), and second resistor (160) shown in FIG. 2 are identical to the components shown in FIG. 1.

[0053] An inductor (170) is installed between the second switch (130) and the first resistor (150). One end of the inductor (170) is connected to the other end of the second switch (130), and the other end is connected to one end of the first resistor (150). The inductor (170) may be installed between the first resistor (150) and the capacitor (140). By configuring a reverse current generation circuit including the inductor (170), an RLC resonant current is generated, and a faster cutoff time can be secured by adjusting the RL time constant. That is, the characteristics of the reverse current are controlled through the inductor (170), and the RL time constant is optimized to shorten the DC cutoff time and increase the responsiveness of the circuit. For example, by using RLC to adjust the magnitude of the reverse current to be similar to the magnitude of the DC cutoff current, the residual reverse current that can flow to the load side can be minimized. Here, the time constant defines the time characteristic of the current increasing or decreasing, and the RL time constant is determined by the combination of the inductance of the inductor (170) and the resistance value of the first resistor (150). The inductor (170) and the first resistor (150) can each be configured as a variable inductor and a variable resistor.

[0054] A non-linear resistor element (180) is connected in parallel to the main switch (120) and serves to protect the system from the transient inrush voltage (TIV) that occurs when the main switch (120) is turned off and to absorb residual energy. The non-linear resistor element (180) may include a Metal Oxide Surge Arrester (MOSA) or a Metal Oxide Varistor (MOV). When the absorption of residual energy of the system through the non-linear resistor element (180) is completed, the first switch (110) is turned off to separate the power side and the load side circuit.

[0055] Meanwhile, the unidirectional DC current blocking device (100) according to various embodiments of the present disclosure may or may not use a non-linear resistance element (180) depending on the size of the residual energy of the system. For example, in one embodiment shown in FIG. 1, if the residual energy of the system is large, a non-linear resistance element (180) may be further included. For example, in another embodiment shown in FIG. 2, if the residual energy of the system is small, the non-linear resistance element (180) may be omitted.

[0056] According to embodiments of the present invention, a unidirectional DC current blocking device (100) can supply a reverse current in the opposite direction with a magnitude similar to the DC current to extinguish an arc generated in the main switch (120) and quickly block a fault current or load current.

[0057] The operation process of a unidirectional DC current blocking device according to embodiments of the present disclosure is described.

[0058] First, a capacitor (140) charging process is required to generate reverse current.

[0059] FIGS. 3 and FIGS. 4 are drawings showing the current flow during capacitor charging and after charging is completed, respectively, according to one embodiment of the present disclosure.

[0060] Referring to FIG. 3, the capacitor (140) is charged with the DC current (Imain) while the DC current (Imain) flows normally through the DC line. At this time, the first switch (110) and the main switch (120) are turned on, and the second switch (130) is turned off. The time required for charging and the magnitude of the charging current (IC) are adjusted by the second resistor (160).

[0061] Referring to FIG. 4, the capacitor (140) is fully charged and the charging current (IC) no longer flows. That is, the magnitude of the charging current (IC) is 0.

[0062] After the unidirectional DC current blocking device, the capacitor (140) is fully charged, the DC current can be cut off.

[0063] FIGS. 5a to 5d are drawings for explaining a DC current interruption process according to one embodiment of the present disclosure.

[0064] Referring to FIG. 5a, the main switch (120) is turned off to cut off the fault current or load current. When the main switch (120) is turned off, an arc is generated. Due to the arc generated in the main switch (120), the DC current (Imain) is not cut off and can continue to flow.

[0065] Referring to FIG. 5b, the second switch (130) is turned on to generate a reverse current. When the second switch (130) is turned on, a reverse current (ID) in the opposite direction to the DC current (Imain) is generated by the discharge of the capacitor (140) and supplied to the main switch (120).

[0066] Referring to FIG. 5c, a current zero point is created as a reverse current (ID) is supplied to the main switch (120). Due to the creation of the current zero point, the DC current (Imain) no longer flows, and only the residual reverse current (Irem) flows to the load side.

[0067] Referring to FIG. 5d, the first switch (110) is turned off to separate the power side and the load side circuit, and the DC current cutoff operation is completed.

[0068] FIG. 6 is a flowchart of a method performed by a unidirectional DC current blocking device according to one embodiment of the present disclosure.

[0069] Referring to FIG. 6, the capacitor (140) is charged through the DC current (Imain) while the DC current (Imain) flows normally through the DC line (S610).

[0070] According to a control signal to cut off the DC current, the main switch (120) is turned off (S620). When the main switch (120) is turned off, an arc occurs, and as a result, the DC current (Imain) is not cut off and continues to flow.

[0071] The second switch (130) is turned on to generate a reverse current (S630). As the second switch (130) is turned on, a reverse current (ID) in the opposite direction to the DC current (Imain) is generated through the discharge of the capacitor (140), and a current zero point is created in the main switch (120).

[0072] The first switch (110) is turned off to separate the power side and the load side circuit (S640). The residual reverse current (Irem) becomes 0, and the DC current cutoff operation is completed.

[0073] FIG. 7 is a diagram showing changes in main current, reverse current, and voltage across the main switch during the operation of a unidirectional DC current blocking device according to one embodiment of the present disclosure.

[0074] Referring to FIG. 7, it can be seen that the reverse current generated during the blocking process cancels out the main current, quickly creating a zero current point, and the voltage (Vcb) across the main switch (120) is maintained at a stable level.

[0075] Each component of the device or method according to the present invention may be implemented in hardware or software, or in a combination of hardware and software. Additionally, the function of each component may be implemented in software, and a microprocessor may be implemented to execute the function of the software corresponding to each component.

[0076] Various embodiments of the systems and techniques described herein may be realized as digital electronic circuits, integrated circuits, field programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), computer hardware, firmware, software, and / or combinations thereof. These various embodiments may include being implemented as one or more computer programs executable on a programmable system. A programmable system comprises a storage system, at least one input device, and at least one programmable processor (which may be a special-purpose processor or a general-purpose processor) coupled to receive data and instructions from at least one output device and to transmit data and instructions to them. Computer programs (which are also known as programs, software, software applications, or code) include instructions for the programmable processor and are stored on a "computer-readable recording medium."

[0077] Computer-readable recording media include all types of recording devices in which data that can be read by a computer system is stored. Such computer-readable recording media may be non-volatile or non-transitory media such as ROM, CD-ROM, magnetic tape, floppy disk, memory card, hard disk, magneto-optical disk, and storage device, and may also include transitory media such as data transmission media. Additionally, computer-readable recording media may be distributed across networked computer systems, and computer-readable code may be stored and executed in a distributed manner.

[0078] Although the flowcharts in this specification describe each process as being executed sequentially, this is merely an illustrative explanation of the technical concept of one embodiment of the present disclosure. In other words, a person skilled in the art to which one embodiment of the present disclosure belongs may modify and adapt the flowcharts in this specification in various ways, such as by changing the order described therein or executing one or more of the processes in parallel, without departing from the essential characteristics of one embodiment of the present disclosure; therefore, the flowcharts in this specification are not limited to a chronological order.

[0079] The above description is merely an illustrative explanation of the technical concept of the present embodiment, and a person skilled in the art to which the present embodiment belongs would be able to make various modifications and variations within the scope of the essential characteristics of the present embodiment. Accordingly, the present embodiments are intended to explain, not limit, the technical concept of the present embodiment, and the scope of the technical concept of the present embodiment is not limited by these embodiments. The scope of protection of the present embodiment shall be interpreted by the claims below, and all technical concepts within an equivalent scope shall be interpreted as being included within the scope of rights of the present embodiment.

[0080] (Explanation of symbols)

[0081] 110: First switch

[0082] 120: Main Switch

[0083] 130: Second switch

[0084] 140: Capacitor

[0085] 150: First resistor

[0086] 160: Second resistor

[0087] 170: Inductor

[0088] 180: Non-linear resistive element

[0089] Statements regarding sponsored research or development

[0090] This invention is the result of research conducted in 2024 with funding from the Ministry of Trade, Industry and Energy and support from the Korea Institute of Energy Technology Evaluation and Planning (Project No.: 2410000203, Project Name: Development of High-Reliability DC Protection Device Technology).

[0091] CROSS-REFERENCE TO RELATED APPLICATION

[0092] This patent application claims priority to Korean patent application No. 10-2024-0160805 filed on November 13, 2024, the entire contents of which are incorporated into this patent application by reference.

Claims

1. Mechanical main switch for interrupting DC current; A first switch for cutting off the residual current of the system in response to the completion of the cutoff operation of the main switch above; A capacitor charged by the above DC current; A second switch for generating reverse current; First resistance; and Includes a second resistor, One end of the first switch is connected to one side circuit, and the other end of the first switch is connected to one end of the main switch and one end of the second switch, and The other end of the main switch is connected to the other circuit and one end of the capacitor, and The other end of the second switch is connected to one end of the first resistor, and The other end of the first resistor is connected to the other end of the capacitor and one end of the second resistor, and A unidirectional DC current blocking device in which, in response to the main switch being turned off, the second switch is turned on, thereby discharging the capacitor, generating a reverse current in the opposite direction to the DC current, and supplying the reverse current to the main switch.

2. In Paragraph 1, A unidirectional DC current blocking device in which the current in the main switch becomes zero due to the reverse current, thereby extinguishing the arc generated by the turn-off of the main switch.

3. In Paragraph 1, A unidirectional DC current blocking device that adjusts the time required to charge the capacitor and the magnitude of the charging current based on the resistance value of the second resistor.

4. In Paragraph 1, The inductor is further included between the second switch and the first resistor, A unidirectional DC current blocking device that generates an RLC resonant current with the above reverse current.

5. In Paragraph 4, A unidirectional DC current blocking device that controls the completion time of the DC current blocking based on the time constant of the inductor and the first resistor.

6. In Paragraph 1, A unidirectional DC current blocking device further comprising a non-linear resistor element connected in parallel to the main switch and configured to suppress inrush voltage occurring when the main switch is turned off or to absorb residual energy.

7. In Paragraph 1, The above second switch is a unidirectional DC current blocking device that is a mechanical switch, a semiconductor switch, or a hybrid switch.

8. A method performed by a unidirectional DC current interruption device, The process of charging a capacitor using DC current; The process of turning off the main switch according to a control signal to cut off the DC current; A process of turning on a second switch to generate a reverse current in response to the main switch being turned off; and A method comprising the process of turning off a first switch in response to the generation of a current zero point in the main switch by the generated reverse current.

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