Control device, control program, recording medium, DC interrupter, and control method

Abstract

To provide a controller capable of reducing a possibility that an in-rush current is cut off.SOLUTION: A DC cutoff device comprises a semiconductor switch (20) located on a first line (11) connecting the positive electrode of a power supply and a load, and a capacitor (30) connected to a second line (12) connecting between the semiconductor switch on the first line and the load, and between the negative electrode of the power supply and the load, and a controller (40) comprises a current cutoff part (41) which opens the semiconductor switch according to the direction of a current flowing to the capacitor.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a control device for a DC interruption device that interrupts DC current, etc.

Background Art

[0002] Patent Document 1 discloses a DC circuit breaker that interrupts DC current flowing through a DC line. The DC circuit breaker includes an accident current interruption unit and a control circuit. The accident current interruption unit performs an opening operation according to a command input from the control circuit when an accident occurs in the DC line. The control circuit determines that an accident has occurred when the value of the DC current flowing through the DC line exceeds a threshold value, and outputs a command for an opening operation to the accident current interruption unit.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, the DC circuit breaker disclosed in Patent Document 1 has a problem that it may erroneously recognize the inrush current to the load as an accident current and interrupt it.

[0005] One aspect of the present invention aims to realize a control device or the like that can reduce the possibility of erroneously interrupting the inrush current.

Means for Solving the Problems

[0006] To solve the above problems, a control device according to one aspect of the present invention is a control device for controlling the opening and closing of a semiconductor switch in a DC interruption device comprising a first line connecting the positive terminal of a power supply and a load, a second line connecting the negative terminal of the power supply and the load, a semiconductor switch located between the power supply and the load on the first line, and a capacitor having its first end connected between the semiconductor switch and the load on the first line and its second end connected to the second line, the control device comprising a current interruption unit that opens the semiconductor switch according to the direction of the current flowing through the capacitor.

[0007] Furthermore, a DC interruption device according to one aspect of the present invention comprises a first line connecting the positive terminal of a power supply and a load, a second line connecting the negative terminal of the power supply and the load, a semiconductor switch located between the power supply and the load on the first line, a capacitor having its first end connected between the semiconductor switch and the load on the first line and its second end connected to the second line, and a current interruption unit that opens the semiconductor switch according to the direction of the current flowing through the capacitor.

[0008] Furthermore, a control method according to one aspect of the present invention is a control method for controlling the opening and closing of a semiconductor switch in a DC circuit breaker comprising a first line connecting the positive terminal of a power supply and a load, a second line connecting the negative terminal of the power supply and the load, a semiconductor switch located between the power supply and the load on the first line, and a capacitor having its first end connected between the semiconductor switch and the load on the first line and its second end connected to the second line, the method comprising a current detection step for detecting the direction of the current flowing through the capacitor, and a current interruption step for opening the semiconductor switch according to the direction of the current flowing through the capacitor.

[0009] Each aspect of the present invention may be implemented by a computer, in which case a control program for the control device that enables the computer to implement the control device by operating the computer as each part (software element) of the control device, and a computer-readable recording medium on which the program is recorded, also fall within the scope of the present invention. [Effects of the Invention]

[0010] According to one aspect of the present invention, the control device and the like can reduce the possibility of accidentally interrupting the inrush current. [Brief explanation of the drawing]

[0011] [Figure 1] This is a circuit diagram showing the configuration of a DC circuit breaker according to an embodiment of the present invention. [Figure 2] This diagram shows the state of the DC circuit breaker during startup. [Figure 3] This diagram shows the state of the DC circuit breaker in the event of a fault due to a load. [Figure 4] This diagram shows the state of the DC circuit breaker when a capacitor load is added. [Figure 5] This flowchart shows an example of a control method for a DC circuit breaker using a current interruption unit. [Modes for carrying out the invention]

[0012] One embodiment of the present invention will be described in detail below.

[0013] (Configuration of DC circuit breaker 1) Figure 1 is a circuit diagram showing the configuration of the DC circuit breaker 1 according to this embodiment. As shown in Figure 1, the DC circuit breaker 1 comprises a first wire 11, a second wire 12, a semiconductor switch 20, a capacitor 30, and a control device 40.

[0014] The first wire 11 connects the positive terminal of the power supply (not shown) to the load (not shown). The second wire 12 connects the negative terminal of the power supply to the load. The power supply is a DC power supply. The load is a capacitor load.

[0015] The semiconductor switch 20 is located between the power supply and the load in the first line 11. The opening and closing of the semiconductor switch 20 is controlled by a control signal from the control device 40. Any known semiconductor switch can be used as the semiconductor switch 20 without any particular limitations. Specific examples of the semiconductor switch 20 include IGBTs (Insulated Gate Bipolar Transistors), FETs (Field Effect Transistors), and other transistors.

[0016] Capacitor 30 is a capacitor having a first terminal 31 and a second terminal 32. The first terminal 31 is connected between the semiconductor switch 20 and the load on the first line 11. The second terminal 32 is connected to the second line 12. The capacitance of capacitor 30 may be a small capacitance capacitor with a capacitance of 10% or less of the capacitance of the capacitor load that is expected to be connected to the DC circuit breaker 1.

[0017] The control device 40 controls the operation of the DC circuit breaker 1. For example, the control device 40 controls the opening and closing of the semiconductor switch 20. In this embodiment, the control device 40 is described as being part of the DC circuit breaker 1. However, the control device 40 may be a separate device from the DC circuit breaker 1. The control device 40 includes a current interruption unit 41, an inrush current control unit 42, and a storage unit 45.

[0018] The current interruption unit 41 opens the semiconductor switch 20 according to the direction of the current Ico flowing through the capacitor 30. When the current Id in the first line 11 increases, it is difficult to determine from the magnitude of the current Id whether the increased current is a fault current caused by a fault in the load or an inrush current caused by the new connection of a capacitor load. However, the direction of the current Ico flowing through the capacitor 30 behaves differently depending on whether a fault has occurred or a capacitor load has been connected. Therefore, the control device 40 reduces the possibility of mistakenly interrupting an inrush current by operating the current interruption unit 41 as described above.

[0019] Specifically, when the current Ico flows from the first terminal 31 to the first line 11 and then becomes zero, the current interruption unit 41 opens the semiconductor switch 20. The current interruption unit 41 acquires a signal indicating the direction and magnitude of the current Ico from a first current transformer 51, which will be described later.

[0020] As described later, when a short-circuit accident or a ground-fault accident occurs in the load, the current Ico flows from the first terminal 31 to the first line 11 and then becomes zero. On the other hand, when a capacitor load is added and an inrush current flows through the first line 11, the current Ico flows from the first terminal 31 to the first line 11, then from the first line 11 to the first terminal 31, and then becomes zero.

[0021] Strictly speaking, when an inrush current flows through the first line 11, after the current Ico flows from the first terminal 31 to the first line 11 and before the current Ico flows from the first line 11 to the first terminal 31, the current Ico temporarily becomes zero. The time from when the current Ico becomes zero until the current Ico flows from the first line 11 to the first terminal 31 depends on the capacitance of the capacitor load and the power supply voltage.

[0022] For example, consider the following example. · Capacitance of capacitor load: 4000 μF (equivalent to a 100 kW converter) · Capacitance of capacitor 30: 200 μF (5% of the capacitance of the capacitor load) · DC resistivity of the first line 11: 0.5 Ω / km In this example, when the length of the first line 11 is 500 m, the wiring resistance is 0.5 Ω / km × 500 m = 0.25 Ω. In this case, the time from when the current Ico becomes zero until the current Ico flows from the first line 11 to the first terminal 31 is 0.25 Ω (wiring resistance) × 200 μF (capacitance of capacitor 30) = 50 μs.

[0023] Therefore, in this example, if the current Ico becomes 0 and that state continues for 50 μs or more, it is highly likely that a short-circuit or ground fault has occurred in the load. As the current interruption unit 41 operates as described above, the control device 40 can open the semiconductor switch 20 in a short time in response to the fault current.

[0024] Generally, charging a capacitor is performed with a large current when the power supply voltage is high, and with a small current when the power supply voltage is low. Therefore, the time it takes for current Ico to flow from the first line 11 to the first terminal 31 after current Ico becomes 0 does not depend on the power supply voltage.

[0025] In the above determination, the current interruption unit 41 does not need to determine whether the current Ico has dropped completely to 0, but only needs to determine whether it has dropped to a threshold below which it can be considered to have become substantially 0. The threshold below which the current Ico can be considered to have become substantially 0 can be set appropriately by the designer or user of the control device 40 according to the expected output of the power supply. For example, if the expected output of the power supply is 100kW and the power supply voltage is 600V, the current from the power supply will be 167A. In this case, the threshold below which the current Ico can be considered to have become substantially 0 may be 10% (16.7A) or less of the current from the power supply, for example, 15A.

[0026] Furthermore, the current interruption unit 41 may open the semiconductor switch 20 depending on the direction of the current Ico flowing through the capacitor 30 and the magnitude of the voltage Vco across the capacitor 30. The magnitude of the voltage Vco also behaves differently when a fault occurs and when a capacitor load is newly connected. Therefore, by opening the semiconductor switch 20 in accordance with the magnitude of the voltage Vco in addition to the direction of the current Ico, the current interruption unit 41 can open the semiconductor switch 20 in response to the fault current with higher precision.

[0027] Specifically, the current interruption unit 41 opens the semiconductor switch 20 when the voltage Vco falls below a threshold while current Ico is flowing from the first terminal 31 to the first line 11, and then the voltage Vco remains below the threshold while current Ico is 0. The current interruption unit 41 obtains a signal indicating the magnitude of the voltage Vco from the first voltage sensor 53, which will be described later.

[0028] As described later, if a short-circuit or ground fault occurs in the load, the capacitor 30 discharges the power it had stored. As a result, a current Ico flows from the first terminal 31 to the first line 11, and the voltage Vco drops below the threshold. Since the capacitor 30 is not charged thereafter, the voltage Vco remains below the threshold until the time elapsed from when the current Ico becomes 0 until the fault is determined to have occurred. In this state, the voltage Vco is close to 0. On the other hand, as described later, if a capacitor load is added and an inrush current occurs, the capacitor 30 discharges for only a short time and then recharges. As a result, even if the voltage Vco temporarily drops below the threshold, it rises again to a value higher than the threshold before the time elapsed from when the current Ico becomes 0 until the fault is determined to have occurred. Therefore, the current interruption unit 41 operates as described above, allowing the semiconductor switch 20 to open with higher precision in response to the fault current.

[0029] The threshold voltage Vco at which the current interruption unit 41 opens the semiconductor switch 20 can be appropriately set by the designer or user of the control device 40 to a value greater than 0 and less than the power supply voltage Vin input from the power supply to the DC interruption device 1. The threshold voltage Vco at which the current interruption unit 41 opens the semiconductor switch 20 may be a constant, or it may be a value that references the power supply voltage Vin. If the threshold voltage Vco at which the current interruption unit 41 opens the semiconductor switch 20 is a value that references the power supply voltage Vin, the current interruption unit 41 obtains a signal indicating the magnitude of the power supply voltage Vin from the second voltage sensor 54, which will be described later. In this case, the threshold may be, for example, half the value of the power supply voltage Vin.

[0030] Furthermore, the current interruption unit 41 may open the semiconductor switch 20 according to the magnitude of the current Id in the first line 11, in addition to the direction of the current Ico or the combination of the direction of the current Ico and the magnitude of the voltage Vco described above. The current interruption unit 41 obtains a signal indicating the magnitude of the current Id from the second current transformer 52, which will be described later.

[0031] The current interruption unit 41 may include the condition that the current Id is above a predetermined threshold as a condition for opening the semiconductor switch 20. This allows the current interruption unit 41 to open the semiconductor switch 20 in response to a fault current with higher precision. The threshold current Id at which the current interruption unit 41 opens the semiconductor switch 20 should be set by the designer or user of the control device 40 to a value sufficiently higher than the current Id in the steady state of the DC interruption device 1. The threshold current Id at which the current interruption unit 41 opens the semiconductor switch 20 may be set, for example, to twice the current Id in the steady state of the DC interruption device 1.

[0032] Generally, from the viewpoint of power efficiency, it is preferable for semiconductor devices to be operated with a steady-state current of about half of their rated current. When the semiconductor switch 20 is operated in this manner, twice the steady-state current Id of the DC circuit breaker 1 is the rated current of the semiconductor switch 20.

[0033] The inrush current control unit 42 controls the first switch 61 and the second switch 62 to reduce the inrush current when the DC circuit breaker 1 is started up. The details of the control performed by the inrush current control unit 42 will be described later.

[0034] The memory unit 45 is a storage device that stores information necessary for control by the control device 40. The memory unit 45 stores, for example, a threshold value that can be considered to indicate that the current Ico has become substantially zero. However, the control device 40 does not necessarily need to have a memory unit 45; it may be connected to an external storage device that stores information necessary for control by the control device 40 in a communicative manner.

[0035] The DC circuit breaker 1 further includes an overvoltage suppression circuit 25. The overvoltage suppression circuit 25 is connected in parallel with the semiconductor switch 20 to the first line 11. When the semiconductor switch 20 is closed, the current flows through the semiconductor switch 20, and therefore almost no current flows to the overvoltage suppression circuit 25. On the other hand, when the semiconductor switch 20 is open, the positive terminal of the power supply and the load are connected only through the overvoltage suppression circuit 25, so current flows to the overvoltage suppression circuit 25. Examples of the overvoltage suppression circuit 25 include an LC resonant circuit, an RC snubber circuit, and a surge absorber.

[0036] The DC circuit breaker 1 further comprises a first current transformer 51 and a second current transformer 52. The first current transformer 51 is a current transformer for detecting the direction and magnitude of the current Ico flowing through the capacitor 30. The first current transformer 51 outputs a signal indicating the direction and magnitude of the current Ico to the current circuit breaker 41. The first current transformer 51 may also output a signal indicating the direction and magnitude of the current Ico to the inrush current control unit 42. The first current transformer 51 is installed between the first terminal 31 of the capacitor 30 and the first wire 11.

[0037] The second current transformer 52 is a current transformer for detecting the magnitude of the current Id flowing between the semiconductor switch 20 and the load in the first line 11. The second current transformer 52 outputs a signal indicating the magnitude of the current Id to the current interruption unit 41. The second current transformer 52 is installed in the first line 11.

[0038] The DC interrupter 1 further includes a first voltage sensor 53 and a second voltage sensor 54. The first voltage sensor 53 is a sensor for detecting the magnitude of the voltage Vco in the capacitor 30. The first voltage sensor 53 outputs a signal indicating the magnitude of the voltage Vco to the current interruption unit 41. The first voltage sensor 53 may also output a signal indicating the magnitude of the voltage Vco to the inrush current control unit 42. One end of the first voltage sensor 53 is connected to the power supply side of the first line 11, beyond the semiconductor switch 20. The other end of the first voltage sensor 53 is connected to the second line 12.

[0039] The second voltage sensor 54 is a sensor for detecting the magnitude of the power supply voltage Vin. The second voltage sensor 54 outputs a signal indicating the magnitude of the power supply voltage Vin to the current interruption unit 41. The second voltage sensor 54 is provided in parallel with the capacitor 30.

[0040] The first voltage sensor 53, the second voltage sensor 54, and the second current transformer 52 are not essential components of the DC circuit breaker 1. If the current interruption unit 41 does not perform the determination using the voltage Vco described above, the first voltage sensor 53 and the second voltage sensor 54 may be omitted. Also, if the current interruption unit 41 does not perform the determination using the current Id described above, the second current transformer 52 may be omitted.

[0041] The DC circuit breaker 1 further comprises a first switch 61 and a second switch 62. The first switch 61 and the second switch 62 are switches controlled by the control device 40. The first switch 61 and the second switch 62 may be either semiconductor switches or mechanical switches. The first switch 61 is located on the first line 11 between the positive terminal of the power supply and the semiconductor switch 20. The second switch 62 is connected to the first line 11 in parallel with the first switch 61.

[0042] Furthermore, the DC circuit breaker 1 is further equipped with an inrush current suppression resistor 64. The inrush current suppression resistor 64 is a resistor connected to the first line 11 in parallel with the first switch 61 and in series with the second switch 62. The second switch 62 and the inrush current suppression resistor 64 constitute an inrush current suppression circuit that suppresses the inrush current when the DC circuit breaker 1 is started up. The resistance value of the inrush current suppression resistor 64 should be appropriately determined by the designer of the DC circuit breaker 1 according to the expected output of the power supply and the capacity of the load.

[0043] Furthermore, the DC circuit breaker 1 further comprises a third switch 63. The third switch 63 is located on the second line 12. The third switch 63 is a switch that switches the operation and shutdown of the entire system, including the DC circuit breaker 1, the power supply, and the load. The third switch 63 is a switch controlled by the control device 40. The third switch 63 may be either a semiconductor switch or a mechanical switch.

[0044] The first switch 61, the second switch 62, the inrush current suppression resistor 64, and the inrush current control unit 42 are not essential components of the DC circuit breaker 1. These components may be omitted if there is no need to reduce the inrush current when the DC circuit breaker 1 is started up.

[0045] The third switch 63 is not an essential component of the DC circuit breaker 1. In a system including the DC circuit breaker 1, a power supply, and a load, the operation and shutdown of the entire system may be switched, for example, by switching the supply and shutdown of power from the power supply. In that case, the third switch 63 controlled by the control device 40 may be omitted.

[0046] (Operation of DC circuit breaker 1 when it is started up) Figure 2 shows the state of the DC circuit breaker 1 when it is started up. In Figure 2, reference numeral 201 indicates the state before the capacitor 30 is fully charged, and reference numeral 202 indicates the state after the capacitor 30 is fully charged. For simplicity, the first current transformer 51, the second current transformer 52, the first voltage sensor 53, and the second voltage sensor 54 are omitted in Figure 2.

[0047] When the DC circuit breaker 1 is started up, the current interruption unit 41 closes the semiconductor switch 20. The inrush current control unit 42 opens the first switch 61, closes the second switch 62, and closes the third switch 63. At this time, as indicated by arrow 91 in reference numeral 201, the current from the positive terminal of the power supply flows to the load via the second switch 62, the inrush current suppression resistor 64, and the semiconductor switch 20. Therefore, the inrush current when the DC circuit breaker 1 is started up is suppressed more than if it did not pass through the inrush current suppression resistor 64. Also, as indicated by arrow 92, a portion of the current from the positive terminal of the power supply flows to the capacitor 30 and charges the capacitor 30.

[0048] When the charging of the capacitor 30 is complete, the inrush current control unit 42 closes the first switch 61 and opens the second switch 62. At this time, as indicated by the arrow 93 in reference numeral 202, the current from the positive terminal of the power supply flows to the load via the first switch 61 and without passing through the inrush current suppression resistor 64. The inrush current control unit 42 may, for example, obtain a signal indicating the magnitude of the current Ico from the first current transformer 51 and determine that the charging of the capacitor 30 is complete when the magnitude of the current Ico becomes 0. Alternatively, the inrush current control unit 42 may, for example, obtain a signal indicating the magnitude of the voltage Vco from the first voltage sensor 53 and obtain a signal indicating the magnitude of the power supply voltage Vin from the second voltage sensor 54. The inrush current control unit 42 may determine that the charging of the capacitor 30 is complete when the magnitude of the voltage Vco becomes equal to the magnitude of the power supply voltage Vin.

[0049] (Operation in the event of an accident due to load) Figure 3 shows the state of the DC circuit breaker 1 when a fault occurs in the load. In Figure 3, reference numeral 301 indicates the state before the current interruption unit 41 opens the semiconductor switch 20, and reference numeral 302 indicates the state after the current interruption unit 41 opens the semiconductor switch 20. For simplicity, the first current transformer 51, the second current transformer 52, the first voltage sensor 53, and the second voltage sensor 54 are omitted in Figure 3.

[0050] If a short-circuit or ground fault occurs in the load, a short-circuit current or ground fault current flows, as indicated by arrow 94. At this time, a discharge current flows from the first terminal 31 of the capacitor 30 to the load via the first line 11, as indicated by arrow 95 in reference numeral 301. Once the discharge of the capacitor 30 is complete, the current flowing from the capacitor 30 to the first line 11 becomes zero.

[0051] The current interruption unit 41 opens the semiconductor switch 20 according to the direction of the current Ico. At this time, as indicated by the arrow 96 in reference numeral 302, the current from the positive terminal of the power supply flows to the load via the overvoltage suppression circuit 25. The overvoltage suppression circuit 25 suppresses the rapid increase in the current flowing from the positive terminal of the power supply to the load, suppresses the overvoltage generated by the energy used to interrupt the fault current, and extinguishes the current, resulting in zero fault current.

[0052] (Operation when a capacitor load is added) Figure 4 shows the state of the DC circuit breaker 1 when a capacitor load is added. In Figure 4, reference numeral 401 indicates a state where the voltage across the capacitor load is lower than the voltage across the capacitor 30, and reference numeral 402 indicates a state where the voltage across the capacitor load is equal to or greater than the voltage across the capacitor 30. For simplicity, the first current transformer 51, the second current transformer 52, the first voltage sensor 53, and the second voltage sensor 54 are omitted in Figure 4.

[0053] When a capacitor load is additionally connected to the DC circuit breaker 1, the added capacitor load is charged as indicated by arrow 97. When the voltage across the capacitor load is lower than the voltage across the capacitor 30, the capacitor 30 discharges into the capacitor load as indicated by arrow 98 in reference numeral 401. When the voltage across the capacitor load becomes equal to or greater than the voltage across the capacitor 30, the capacitor 30 is recharged as indicated by arrow 99 in reference numeral 402.

[0054] (Control method of DC circuit breaker 1 by current interruption unit 41) Figure 5 is a flowchart illustrating an example of a control method for the DC interruption device 1 by the current interruption unit 41. The current interruption unit 41 obtains a signal indicating the direction of the current Ico flowing through the capacitor 30 from the first current transformer 51 (S1, current detection step). However, the current interruption unit 41 may obtain a signal indicating the direction of the current Ico from the first current transformer 51 not only in step S1, but also, for example, before steps S4 and S5 described later. The current interruption unit 41 may also obtain a signal indicating the voltage Vco at the capacitor 30 from the first voltage sensor 53, for example, before steps S3 and S6 described later. Furthermore, the current interruption unit 41 may also obtain a signal indicating the power supply voltage Vin from the second voltage sensor 54, for example, before steps S3 and S6 described later.

[0055] The current interruption unit 41 determines whether or not current Ico has flowed from the first terminal 31 to the first line 11 (S2). If current Ico has flowed from the first terminal 31 to the first line 11 (YES in S2), the current interruption unit 41 determines whether or not the voltage Vco has fallen below a threshold (S3).

[0056] If the voltage Vco falls below a threshold (YES in S3), the current interruption unit 41 determines whether the current Ico has become 0 (S4). If the current Ico has become 0 (YES in S4), the current interruption unit 41 determines whether the state of current Ico being 0 has continued for a predetermined time (S5). If the state of current Ico being 0 has continued for a predetermined time (YES in S5), the current interruption unit 41 determines whether the voltage Vco remains below a threshold (S6).

[0057] If the voltage Vco remains below the threshold (YES in S6), the current interruption unit 41 opens the semiconductor switch 20 (S7, current interruption step). The execution of step S7 presupposes that the direction of the current Ico is determined to be YES in each of steps S2, S4, and S5. Therefore, step S7 can be described as a step in which the semiconductor switch 20 is opened according to the direction of the current Ico flowing through the capacitor 30. On the other hand, if the current interruption unit 41 determines NO in any of steps S2 to S6, the current interruption unit 41 terminates the process without executing step S7.

[0058] If the current interruption unit 41 determines YES in all of steps S2 to S6, there is a high probability that a fault has occurred in the load. Therefore, the current interruption unit 41 can interrupt the fault current by executing step S7. On the other hand, if the current interruption unit 41 determines NO in any of steps S2 to S6, there is a low probability that a fault has occurred in the load. Therefore, in this case, the current interruption unit 41 does not execute step S7 and does not interrupt the current flowing through the first line 11, thereby reducing the possibility of interrupting currents other than the fault current.

[0059] Steps S3 and S6 are steps that allow the current interruption unit 41 to determine with higher accuracy whether a fault has occurred. However, steps S3 and S6 are not essential for determining whether a fault has occurred. For this reason, the current interruption unit 41 may omit steps S3 and S6. Alternatively, the current interruption unit 41 may perform a step before step S7 in which it obtains a signal indicating the magnitude of the current Id in the first line 11 from the second current transformer 52 and determines the magnitude of the current Id.

[0060] [Examples of implementation using software] The function of the control device 40 (hereinafter referred to as "device") is a program for causing the device to function as a computer, and can be realized by a control program for causing the device to function as a control block (current interruption unit 41) of the device.

[0061] In this case, the device includes a computer having at least one control device (e.g., a processor) and at least one storage device (e.g., memory) as hardware for executing the control program. By executing the control program using this control device and storage device, each of the functions described in each of the embodiments is realized.

[0062] The control program described above may be recorded on one or more computer-readable recording media, not temporary ones. These recording media may or may not be provided by the device. In the latter case, the program may be supplied to the device via any wired or wireless transmission medium.

[0063] Furthermore, some or all of the functions of each of the above control blocks can also be realized by logic circuits. For example, an integrated circuit in which logic circuits functioning as each of the above control blocks are formed is also included in the scope of the present invention. In addition, it is also possible to realize the functions of each of the above control blocks by, for example, a quantum computer.

[0064] Furthermore, each process described in the above embodiments may be performed by AI (Artificial Intelligence). In this case, the AI ​​may operate on the control device described above, or it may operate on other devices (for example, an edge computer or a cloud server).

[0065] 〔summary〕 A control device according to embodiment 1 of the present invention is a control device for controlling the opening and closing of a semiconductor switch in a DC interruption device comprising a first line connecting the positive terminal of a power supply and a load, a second line connecting the negative terminal of the power supply and the load, a semiconductor switch located between the power supply and the load on the first line, and a capacitor having its first end connected between the semiconductor switch and the load on the first line and its second end connected to the second line, the control device comprising a current interruption unit that opens the semiconductor switch according to the direction of the current flowing through the capacitor.

[0066] According to the above configuration, the current interruption unit opens the semiconductor switch according to the direction of the current flowing through the capacitor provided in the DC interruption device. The first end of the capacitor is connected between the semiconductor switch and the load on the first line. The second end of the capacitor is connected to the second line. The current flowing through the capacitor behaves differently depending on whether the current flowing through the first line is a fault current or an inrush current. Therefore, by opening the semiconductor switch as described above, the control device can reduce the possibility of mistakenly interrupting the inrush current.

[0067] Furthermore, in the control device according to embodiment 2 of the present invention, in embodiment 1, the current interruption unit may open the semiconductor switch when the current flowing through the capacitor becomes 0 after current has flowed from the first end to the first line.

[0068] According to the above configuration, the control device can open the semiconductor switch in a short time in response to a fault current, based on the behavior indicated by the direction of the current flowing through the capacitor when a fault current flows through the first line.

[0069] Furthermore, in the control device according to embodiment 3 of the present invention, in embodiment 1 or 2, the current interruption unit may open the semiconductor switch according to the direction of the current flowing through the capacitor and the magnitude of the voltage in the capacitor.

[0070] According to the above configuration, the current interruption unit opens the semiconductor switch according to the magnitude of the voltage across the capacitor, in addition to the direction of the current flowing through the capacitor. The magnitude of the voltage across the capacitor also behaves differently depending on whether the current flowing through the first line is a fault current or an inrush current. Therefore, the control device can open the semiconductor switch in response to a fault current with higher precision.

[0071] Furthermore, in the control device according to embodiment 4 of the present invention, in embodiment 3, the current interruption unit may open the semiconductor switch when the voltage across the capacitor is below a threshold value while current is flowing from the first end to the first line, and when the voltage across the capacitor remains below the threshold value while the current flowing through the capacitor is subsequently zero.

[0072] According to the above configuration, the control device can open the semiconductor switch in response to a fault current based on the behavior of the direction of the current flowing through the capacitor and the behavior of the voltage in the capacitor when a fault current flows through the first line.

[0073] Furthermore, the control program according to aspect 5 of the present invention is a control program for causing a computer to function as the control device of aspect 1, and causes the computer to function as the current interruption unit.

[0074] Furthermore, the recording medium according to embodiment 6 of the present invention is a computer-readable recording medium on which the control program of embodiment 5 is recorded.

[0075] Furthermore, the DC interruption device according to embodiment 7 of the present invention comprises a first line connecting the positive terminal of a power supply and a load, a second line connecting the negative terminal of the power supply and the load, a semiconductor switch located between the power supply and the load on the first line, a capacitor having its first end connected between the semiconductor switch and the load on the first line and its second end connected to the second line, and a current interruption unit that opens the semiconductor switch according to the direction of the current flowing through the capacitor.

[0076] Furthermore, an embodiment 8 of the present invention relates to a control method for controlling the opening and closing of a semiconductor switch in a DC interruption device comprising: a first line connecting the positive terminal of a power supply and a load; a second line connecting the negative terminal of the power supply and the load; a semiconductor switch located between the power supply and the load on the first line; and a capacitor having its first end connected between the semiconductor switch and the load on the first line and its second end connected to the second line, the method comprising: a current detection step for detecting the direction of the current flowing through the capacitor; and a current interruption step for opening the semiconductor switch according to the direction of the current flowing through the capacitor.

[0077] According to the configurations of embodiments 5 to 8, the same effects as those of embodiment 1 are achieved.

[0078] The present invention is not limited to the embodiments described above, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. [Explanation of Symbols]

[0079] 1. DC circuit breaker 11. First Line 12. Second line 20 Semiconductor switches 30 Capacitors 31 1st end 32 2nd end 40 Control device 41 Current interruption section

Claims

1. The first line connects the positive terminal of the power supply to the load, A second wire connecting the negative terminal of the power supply and the load, A semiconductor switch located between the power supply and the load in the first line, A control device for controlling the opening and closing of a semiconductor switch in a DC circuit breaker comprising a capacitor whose first end is connected between the semiconductor switch and the load on the first line and whose second end is connected to the second line, The capacitor is equipped with a current interruption unit that opens the semiconductor switch according to the direction of the current flowing through it. The current interruption unit is a control device that, after determining that current has flowed from the first end to the first line, determines that the current flowing through the capacitor has become zero, and then opens the semiconductor switch.

2. The control device according to claim 1, wherein the current interruption unit opens the semiconductor switch according to the direction of the current flowing through the capacitor and the magnitude of the voltage in the capacitor.

3. The control device according to claim 2, wherein the current interruption unit opens the semiconductor switch when the voltage across the capacitor falls below a threshold while current is flowing from the first end to the first line, and thereafter the voltage across the capacitor remains below the threshold while the current flowing through the capacitor becomes zero.

4. A control program for causing a computer to function as a control device according to claim 1, wherein the control program is for causing the computer to function as the current interruption unit.

5. A computer-readable recording medium that stores the control program described in claim 4.

6. The first line connects the positive terminal of the power supply to the load, A second wire connecting the negative terminal of the power supply and the load, A semiconductor switch located between the power supply and the load in the first line, A capacitor whose first end is connected between the semiconductor switch and the load on the first line, and whose second end is connected to the second line, The system includes a current interruption unit that opens the semiconductor switch according to the direction of the current flowing through the capacitor, The current interruption unit is a DC interruption device that, after determining that current has flowed from the first end to the first line, determines that the current flowing through the capacitor has become zero, and then opens the semiconductor switch.

7. The first line connects the positive terminal of the power supply to the load, A second wire connecting the negative terminal of the power supply and the load, A semiconductor switch located between the power supply and the load in the first line, A control method for controlling the opening and closing of a semiconductor switch in a DC circuit breaker comprising a capacitor whose first end is connected between the semiconductor switch and the load on the first line and whose second end is connected to the second line, A current detection step for detecting the direction of the current flowing through the capacitor, The step includes a current interruption step of opening the semiconductor switch according to the direction of the current flowing through the capacitor, A control method in which, in the current interruption step, after determining that current has flowed from the first end to the first line, the semiconductor switch is opened when it is determined that the current flowing through the capacitor has become zero.

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