Shutdown device and shutdown method

Abstract

To realize a circuit breaker that can prevent unnecessary circuit breaker operations. [Solution] The circuit breaker (1) includes a control unit (20) that controls switching between a conductive state and a cut-off state of a DC bus (50). The control unit includes a Joule calculation unit (22) that calculates the energy consumption of a switch (12) during the period in which an overcurrent state continues, and a circuit breaker unit (25) that switches the DC bus to a cut-off state using the switch when the energy consumption of the switch exceeds a threshold value.

Description

Technical Field

[0001] The present disclosure relates to a cutoff device and a cutoff method for cutting off a direct current.

Background Art

[0002] Patent Document 1 discloses a cutoff circuit that does not use a snubber circuit, a waveform generation circuit, etc. The cutoff circuit includes a semiconductor cutoff device that starts cutting off the current flowing through the power supply line when the current value of the current flowing through the power supply line reaches a predetermined current value. Further, when the semiconductor cutoff device cuts off the current, the cutoff circuit further includes a switch switching control unit that controls the gate voltage of the semiconductor cutoff device by switching the electrical connection state of a voltage dividing circuit of a gate voltage adjustment unit that controls the gate voltage of the semiconductor cutoff device to a plurality of states.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, even when the current value of the current flowing through the power supply line temporarily reaches a predetermined current value, there may be cases where current cutoff is unnecessary. In the cutoff circuit disclosed in Patent Document 1, there is a possibility that an unnecessary cutoff operation may occur for a temporary overcurrent.

[0005] One aspect of the present disclosure aims to realize a cutoff device and the like that can prevent unnecessary cutoff operations.

Means for Solving the Problems

[0006] To solve the above problems, a cutoff device according to one aspect of the present disclosure includes a current detection unit that detects a current flowing through a DC bus, a switch that switches between a conduction state and a cutoff state of the DC bus, a voltage detection unit that detects a voltage applied to the switch, and a control unit that controls the switching between the conduction state and the cutoff state of the DC bus by the switch. The control unit includes an overcurrent determination unit that determines whether or not a current flowing through the DC bus is in an overcurrent state exceeding a predetermined rated current, a joule calculation unit that calculates, based on detection results of the current detection unit and the voltage detection unit, energy consumption of the switch during a period in which the overcurrent state continues when the current flowing through the DC bus is in the overcurrent state, a cutoff determination unit that determines whether or not the energy consumption exceeds a predetermined energy consumption threshold value, and a cutoff unit that switches the DC bus to the cutoff state by the switch when the energy consumption exceeds the energy consumption threshold value.

[0007] Further, a cutoff device according to one aspect of the present disclosure includes a current detection unit that detects a current flowing through a DC bus, a switch that switches between a conduction state and a cutoff state of the DC bus, and a control unit that controls the switching between the conduction state and the cutoff state of the DC bus by the switch. The control unit includes an overcurrent determination unit that determines whether or not a current flowing through the DC bus is in an overcurrent state exceeding a predetermined rated current, and when the current flowing through the DC bus is in the overcurrent state, an It integration value that is a time integration value of the square value of the current flowing through the DC bus during a period in which the overcurrent state continues, based on the detection result of the current detection unit. 2 t integration calculation unit 2 The It 2 t integration value, a cutoff determination unit that determines whether or not the It 2 t integration value exceeds a predetermined It 2 t threshold value, and when the It 2 t integration value exceeds the It

[0008] Also, a cutoff method according to an aspect of the present disclosure is a cutoff method by a cutoff device including a current detection unit that detects a current flowing through a DC bus, a switch that switches between a conduction state and a cutoff state of the DC bus, and a voltage detection unit that detects a voltage applied to the switch. The method includes an overcurrent determination step of determining whether the current flowing through the DC bus is in an overcurrent state exceeding a predetermined rated current, a joule calculation step of calculating energy consumption of the switch during a period in which the overcurrent state continues based on detection results of the current detection unit and the voltage detection unit when the current flowing through the DC bus is in the overcurrent state, a cutoff determination step of determining whether the energy consumption exceeds a predetermined energy consumption threshold value, and a cutoff step of switching the DC bus to the cutoff state by the switch when the energy consumption exceeds the energy consumption threshold value.

[0009] The cutoff device according to each aspect of the present disclosure may be implemented by a computer. In this case, a control program for implementing the cutoff device by operating the computer as each part (software element) included in the cutoff device, and a computer-readable recording medium storing the program also fall within the scope of the present disclosure.

Advantages of the Invention

[0010] According to an aspect of the present disclosure, it is possible to realize a cutoff device or the like that can prevent unnecessary cutoff operations.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Mode for Carrying Out the Invention

[0012] 〔Embodiment 1〕 Hereinafter, an embodiment of the present disclosure will be described in detail.

[0013] (Configuration of Cutoff Device) FIG. 1 is a block diagram illustrating the configuration of the main part of the cutoff device 1 according to Embodiment 1. The cutoff device 1 is arranged on a DC bus 50 that connects a DC power supply (not shown) and a load (not shown), and cuts off the DC current flowing through the DC bus 50 as necessary. As shown in FIG. 1, the cutoff device 1 includes a current detection unit 11, a switch 12, a voltage detection unit 13, a control unit 20, and a storage unit 30.

[0014] The current detection unit 11 is an ammeter that detects the current Iin flowing through the DC bus 50. The switch 12 is a switch that switches between the conductive state and the cutoff state of the DC bus 50. The switch 12 is a switch that can respond sufficiently quickly to the control by the control unit 20, and is, for example, a semiconductor switch. The voltage detection unit 13 is a voltmeter that detects the voltage Vsw applied to the switch 12.

[0015] The DC bus 50 has a main line 51 and a return line 52. In the example shown in FIG. 1, both the current detection unit 11 and the switch 12 are arranged on the main line 51. However, in the cutoff device 1, either one or both of the current detection unit 11 and the switch 12 may be arranged on the return line 52.

[0016] The control unit 20 controls the switching between the conductive state and the cutoff state of the DC bus 50 by the switch 12. The control unit 20 includes an overcurrent determination unit 21, a joule calculation unit 22, an 2 It calculation unit 23, a cutoff determination unit 24, a cutoff unit 25, and an initialization unit 26.

[0017] The overcurrent determination unit 21 determines whether Iin is in an overcurrent state. The overcurrent state is a state where Iin > In, where In is the rated current of the cutoff device 1. In is a value determined in advance at the time of designing the cutoff device 1 in consideration of the characteristics of the DC power supply and load that are assumed to be connected to the cutoff device 1. In other words, In is not a value that varies according to the characteristics of the DC power supply and load actually connected to the cutoff device 1. The specific value of In may be determined in the same manner as the threshold value in a conventional cutoff device that cuts off the current based on whether the current value in the DC bus is equal to or greater than the threshold value.

[0018] When Iin is in an overcurrent state, the joule calculation unit 22 calculates an integrated value of the joule values in the switch 12 during the period in which the overcurrent state continues, based on the detection results of the current detection unit 11 and the voltage detection unit 13. The integrated value of the joule values is the energy consumed by the switch 12.

[0019] A method for the joule calculation unit 22 to calculate the integrated value of the joule values will be described below. First, the joule calculation unit 22 calculates a minute joule value ΔJ in the period for each predetermined sampling period Δt described later by the following formula (1). ΔJ = Iin × Vsw × Δt (1) Furthermore, the joule calculation unit 22 calculates an integrated value of the joule values Jnew by the following formula (2). Jnew = Jold + ΔJ (2) In formula (2), Jold is the integrated value of the joule values up to the previous time. Therefore, Jnew calculated in a certain calculation becomes Jold in the next calculation.

[0020] I 2 When Iin is in an overcurrent state, the I 2Calculate the integral value of \(I^{2}t\). The time integral value of the square of the current is a value indicating the load on the element due to rapid fluctuations in the current, and is used, for example, as a criterion for interrupting the current by a fuse.

[0021] I 2 The \(I^{2}t\) calculation unit 23 calculates the 2 method for calculating the \(I^{2}t\) integral value will be described below. First, the 2 \(I^{2}t\) calculation unit 23 calculates, for each predetermined sampling period \(\Delta t\) described later, the minute \(I^{2}t\) 2 value \(\Delta I^{2}t\) 2 in that period by the following formula (3). \(\Delta I^{2}t\) 2 \(= I_{in}\times I_{in}\times\Delta t\) (3) Furthermore, the 2 \(I^{2}t\) calculation unit 23 calculates the 2 \(I^{2}t\) integral value \(I^{2}t_{new}\) 2 by the following formula (4). \(I^{2}t\) 2 \(t_{new}=I^{2}t\) 2 \(_{old}+\Delta I^{2}t\) 2 (4) In formula (4), \(I^{2}t\) 2 \(_{old}\) is the \(I^{2}t\) 2 integral value up to the previous time. Therefore, the \(I^{2}t\) 2 \(t_{new}\) calculated in a certain calculation becomes the 2 \(I^{2}t\) \(_{old}\) in the next calculation.

[0022] The operations by the Joule calculation unit 22 and the 2 \(I^{2}t\) calculation unit 23 are executed at a cycle of about several tens of MHz. That is, the value of \(\Delta t\) in formulas (1) and (3) is about 10 ns or more and 100 ns or less.

[0023] The cutoff determination unit 24 determines whether \(J_{new}\) exceeds a predetermined energy consumption threshold \(J_{set}\). \(J_{set}\) is a threshold for the energy consumption in the switch 12 for determining whether to cut off the current flowing through the DC bus 50. Also, the cutoff determination unit 24 determines whether 2 \(I^{2}t\) \(_{new}\) exceeds a predetermined 2 \(I^{2}t\) threshold \(I^{2}t\) 2Determine whether it exceeds tset. I 2 tset is for determining whether to cut off the current flowing through the DC bus 50. I 2 It is a threshold value for the t integration value.

[0024] Jset and I 2 tset has a margin to the limit value at which the switch 12 stops functioning when excessive joules or I 2 t is applied.

[0025] When Jnew exceeds Jset, the cutoff unit 25 switches the DC bus 50 to the cutoff state by the switch 12. Also, the cutoff unit 25, I 2 when tnew is I 2 exceeds tset, it also switches the DC bus 50 to the cutoff state by the switch 12. That is, according to the cutoff device 1, Jnew > Jset or I 2 tnew > I 2 when it becomes tset, the current flowing through the DC bus 50 is cut off.

[0026] The initialization unit 26 initializes Jnew and I 2 tnew. In the operation of the cutoff device 1, after Iin enters the overcurrent state, Jnew > Jset and I 2 tnew > I 2 before either of tset is satisfied, Iin may stop being in the overcurrent state. In this case, the initialization unit 26 initializes the values of Jnew and I 2 tnew to 0. Therefore, the values of Jnew and I 2 tnew when Iin stops being in the overcurrent state do not affect the determination of whether to cut off the current flowing through the DC bus 50 when Iin enters the overcurrent state again. <>

[0027] The storage unit 30 stores information necessary for the control of the cutoff device 1 by the control unit 20. The storage unit 30 stores, for example, In, Jset and I 2Remember the tset. The storage unit 30 also stores the above-described formulas (1) to (4). Note that the cutoff device 1 does not necessarily have to include the storage unit 30, and it may be communicably connected to an external storage device that stores information necessary for controlling the cutoff device 1 by the control unit 20.

[0028] (Operating Characteristics) FIG. 2 is a graph illustrating the operating characteristics of the cutoff device 1. In FIG. 2, the horizontal axis represents Iin, and the vertical axis represents the operating time. The operating time is the time during which the product of J and I in the cutoff device 1 continues to be integrated. In other words, the operating time is the time during which the overcurrent state of the current in the DC bus 50 continues. 2 The operating time is the time during which the product of J and I in the cutoff device 1 continues to be integrated. In other words, the operating time is the time during which the overcurrent state of the current in the DC bus 50 continues.

[0029] In FIG. 2, reference numeral 201 is a graph showing the operating time until Jnew reaches Jset. Reference numeral 202 is a graph showing the operating time until I 2 tnew reaches I 2 tset. The values of Jset and I 2 tset are constant. Also, the increasing speed of Jset and I 2 tset becomes faster as Iin increases. Therefore, the operating time until Jnew > Jset is satisfied, and I 2 tnew > I 2 tset are both shorter as Iin increases.

[0030] In FIG. 2, the graph showing the operating characteristics of the cutoff device 1 is indicated by a solid line. The operating characteristics of the cutoff device 1 are divided into a constant conduction region IR1, I 2 t cutoff region IR2, and a joule cutoff region IR3 according to the current Iin.

[0031] The constant conduction region IR1 is a region where the current Iin is less than or equal to the rated current In. In the constant conduction region IR1, Iin is not in an overcurrent state. Therefore, the DC bus 50 is not cut off by the cutoff device 1 and is always in a conductive state.

[0032] I 2The cut-off region IR2 is a region where the current Iin is greater than the rated current In and less than or equal to the boundary current Ib. The boundary current Ib is the value of Iin at which the operating time until Jnew reaches Jset is equal to the operating time until I 2 tnew reaches I 2 tset. In the I 2 t cut-off region IR2, I 2 tnew reaches I 2 tset in a shorter operating time than the operating time until Jnew reaches Jset. Therefore, in the I 2 t cut-off region IR2, the cutoff device 1 cuts off the current flowing through the DC bus 50 when I 2 tnew > I 2 tset is satisfied. For this reason, the graph showing the operating characteristics of the cutoff device 1 in the I 2 t cut-off region IR2 coincides with the graph showing the operating time until I 2 tnew reaches I 2 tset.

[0033] The joule cut-off region IR3 is a region where the current Iin is greater than the boundary current Ib. In the joule cut-off region IR3, the operating time until Jnew reaches Jset is shorter than the operating time until I 2 tnew reaches I 2 tset. Therefore, in the joule cut-off region IR3, the cutoff device 1 cuts off the current flowing through the DC bus 50 when Jnew > Jset is satisfied. For this reason, the graph showing the operating characteristics of the cutoff device 1 in the joule cut-off region IR3 coincides with the graph showing the operating time until Jnew reaches Jset.

[0034] (Cut-off method) FIG. 3 is a flowchart illustrating a cutoff method by the cutoff device 1. In the example shown in FIG. 3, the overcurrent determination unit 21 determines whether Iin > In (S1, overcurrent determination step). When Iin > In (YES in S1), the joule calculation unit 22 calculates ΔJ based on the detection results of the current detection unit 11 and the voltage detection unit 13 (S2), and further calculates Jnew (S3, joule calculation step). Also, in parallel with steps S2 and S3, the I 2 t calculation unit 23 calculates ΔI 2 t based on the detection result of the current detection unit 11 (S4), and further calculates I 2 tnew (S5). Note that steps S2 and S3 and steps S4 and S5 do not necessarily have to be executed in parallel, and may be executed sequentially.

[0035] The cutoff determination unit 24 determines whether Jnew > Jset or I 2 tnew > I 2 tset is satisfied (S6, cutoff determination step). When Jnew > Jset or I 2 tnew > I 2 tset is satisfied (YES in S6), the cutoff unit 25 sets the DC bus 50 in a cutoff state (S7, cutoff step). Thereafter, the control unit 20 ends the process. On the other hand, when neither Jnew > Jset nor I 2 tnew > I 2 tset is satisfied (NO in S6), the control unit 20 repeats the process from step S1.

[0036] Also, when Iin > In is not satisfied in step S1 (NO in S1), the initialization unit 26 initializes Jnew and I 2 tnew (S8). Thereafter, the control unit 20 repeats the process from step S1.

[0037] (Effect) When the current Iin flowing through the DC bus 50 is in an overcurrent state, the cutoff device 1 does not immediately cut off the DC bus 50. The cutoff device 1 calculates the integrated value Jnew of the joule value and the I 2 t integrated value I 2 tnew during the period in which the overcurrent state of Iin continues. When Jnew exceeds a preset Jset, or when I 2 tnew exceeds a preset I 2 tset, the cutoff device 1 cuts off the DC bus 50. In other words, after Iin becomes in an overcurrent state, if neither Jnew > Jset nor I 2 tnew > I 2 tset is satisfied and the overcurrent state of Iin is resolved, the cutoff device 1 maintains the DC bus 50 in a conductive state. Thereby, unnecessary operations due to temporary overcurrents, etc. can be prevented as compared with the case where the DC bus 50 is immediately cut off when Iin is in an overcurrent state, for example.

[0038] 〔Embodiment 2〕 Other embodiments of the present disclosure will be described below. For convenience of explanation, members having the same functions as the members described in the above embodiment are denoted by the same reference numerals, and the description thereof will not be repeated.

[0039] FIG. 4 is a block diagram illustrating the configuration of the main part of the cutoff device 1A according to Embodiment 2. As shown in FIG. 4, the cutoff device 1A is different from the cutoff device 1 in that it includes a control unit 20A instead of the control unit 20. The control unit 20A is different from the control unit 20 in that it does not include an I 2 t calculation unit 23, and in that it includes a cutoff determination unit 24A, a cutoff unit 25A, and an initialization unit 26A instead of the cutoff determination unit 24, the cutoff unit 25, and the initialization unit 26.

[0040] I 2 In the control unit 20A that does not include the I 2tnew is not calculated, and only Jnew is calculated. The cutoff determination unit 24A determines whether Jnew > Jset. The cutoff unit 25A sets the DC bus 50 to the cutoff state when Jnew > Jset. The initialization unit 26A initializes Jnew. Such a cutoff device 1A can also prevent unnecessary operations caused by temporary overcurrents and the like, just like the cutoff device 1.

[0041] 〔Embodiment 3〕 Still other embodiments of the present disclosure will be described below.

[0042] FIG. 5 is a block diagram illustrating the configuration of the main part of the cutoff device 1B according to Embodiment 3. As shown in FIG. 5, the cutoff device 1B is different from the cutoff device 1 in that it does not include the voltage detection unit 13 and includes a control unit 20B instead of the control unit 20. The control unit 20B is different from the control unit 2 in that it does not include the joule calculation unit 22 and includes a cutoff determination unit 24B, a cutoff unit 25B, and an initialization unit 26B instead of the cutoff determination unit 24, the cutoff unit 25, and the initialization unit 26.

[0043] Without the joule calculation unit 22 and with the 2 I 2 t calculation unit 23, in the control unit 20B, Jnew is not calculated, and only I

[0044] The cutoff determination unit 24B determines whether I 2 tnew > I 2 tset. The cutoff unit 25B sets the DC bus 50 to the cutoff state when I 2 tnew > I 2 tset. The initialization unit 26B initializes I 2 tnew. Such a cutoff device 1B can also prevent unnecessary operations caused by temporary overcurrents and the like, just like the cutoff device 1 and the like.

[0045] 〔Example of implementation by software〕 The functions of the blocking devices 1, 1A, and 1B (hereinafter referred to as "devices") are programs for causing a computer to function as the device, and can be realized by programs for causing a computer to function as each control block of the device (especially each part included in the control units 20, 20A, and 20B).

[0046] In this case, the above device includes a computer having at least one control device (e.g., a processor) and at least one storage device (e.g., a memory) as hardware for executing the above program. By executing the above program with this control device and storage device, each function described in each of the above embodiments is realized.

[0047] The above program may be recorded on one or more computer-readable recording media, not temporarily. This recording medium may or may not be provided in the above device. In the latter case, the above program may be supplied to the above device via any wired or wireless transmission medium.

[0048] Also, part or all of the functions of each of the above control blocks can also be realized by a logic circuit. For example, an integrated circuit in which a logic circuit functioning as each of the above control blocks is formed is also included in the scope of the present disclosure. In addition to this, for example, it is also possible to realize the functions of each of the above control blocks by a quantum computer.

[0049] Also, each process described in each of the above embodiments may be executed by AI (Artificial Intelligence). In this case, the AI may operate in the above control device, or may operate in another device (e.g., an edge computer or a cloud server, etc.).

[0050] The present disclosure is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present disclosure.

Description of Symbols

[0051] 1, 1A, 1B Shut-off Devices 11 Current Detection Unit 12 Switch 13 Voltage Detection Unit 20, 20A, 20B Control Units 21 Overcurrent Judgment Unit 22 Joule Calculation Unit 23 I 2 t Calculation Unit 24, 24A, 24B Shut-off Judgment Units 25, 25A, 25B Shut-off Units

Claims

1. a current detection unit that detects a current flowing through a DC bus; a switch for switching between a conductive state and a cut-off state of the DC bus; a voltage detection unit that detects a voltage applied to the switch; a control unit that controls switching between a conductive state and a cut-off state of the DC bus by the switch, The control unit an overcurrent determination unit that determines whether or not the current flowing through the DC bus exceeds a predetermined rated current; a Joule calculation unit that calculates, when the current flowing through the DC bus is in the overcurrent state, energy consumption of the switch during a period in which the overcurrent state continues, based on detection results of the current detection unit and the voltage detection unit; and a shutdown determination unit that determines whether the consumed energy exceeds a predetermined consumed energy threshold; a breaker that switches the DC bus to the break state by the switch when the consumed energy exceeds the consumed energy threshold; A shutoff device comprising:

2. When the current flowing through the DC bus is in the overcurrent state, the control unit calculates, based on the detection result of the current detection unit, I, which is a time integral value of the square value of the current flowing through the DC bus during a period in which the overcurrent state continues. ２ t Calculate the integral value I ２ further comprising a t calculation unit, The interruption determination unit ２ t integral is given by I ２ Further determining whether a threshold value is exceeded; The interrupter is ２ t integral value is ２ The circuit breaker according to claim 1 , wherein the switch switches the DC bus to the interrupted state even when the t threshold is exceeded.

3. a current detection unit that detects a current flowing through a DC bus; a switch for switching between a conductive state and a cut-off state of the DC bus; a control unit that controls switching between a conductive state and a cut-off state of the DC bus by the switch, The control unit an overcurrent determination unit that determines whether or not the current flowing through the DC bus exceeds a predetermined rated current; When the current flowing through the DC bus is in the overcurrent state, I is a time integral value of the square value of the current flowing through the DC bus during the period in which the overcurrent state continues, based on the detection result of the current detection unit. ２ t Calculate the integral value I ２ a t calculation unit; I ２ t integral is given by I ２ a blocking determination unit that determines whether or not a threshold value is exceeded; I ２ t integral value is ２ a cutoff unit that switches the DC bus to the cutoff state by the switch when the t threshold value is exceeded; A shutoff device comprising:

4. a current detection unit that detects a current flowing through a DC bus; a switch for switching between a conductive state and a cut-off state of the DC bus; A breaking method using a breaking device including a voltage detection unit that detects a voltage applied to the switch, an overcurrent determination step of determining whether or not the current flowing through the DC bus exceeds a predetermined rated current; a Joule calculation step of calculating, when the current flowing through the DC bus is in the overcurrent state, energy consumption of the switch during a period in which the overcurrent state continues, based on detection results of the current detection unit and the voltage detection unit; a shut-off determination step of determining whether the consumed energy exceeds a predetermined consumed energy threshold; a disconnecting step of switching the DC bus to the disconnected state by the switch when the consumed energy exceeds the consumed energy threshold; A blocking method including:

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