Current interruption device

Abstract

To provide a current cutoff device that can suppress the occurrence of negative surges.SOLUTION: A current cutoff device includes: a switch group SW connected to an electric wiring 2, and having a plurality of switches SW1 to SWn connected in parallel to each other and dividing and passing a current flowing through the electric wiring 2; and a control circuit 20 that individually controls the on / off of the plurality of switches SW1 to SWn. When cutting off the current flowing through the electric wiring 2, the control circuit 20 repeatedly turns off some of the plurality of switches SW1 to SWn while turning on the remaining switches, gradually increases a combined resistance value of the plurality of switches SW1 to SWn, and finally cuts off the current by turning off all of the plurality of switches SW1 to SWn.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a current interrupting device for interrupting the supply of current in an electrical wiring, and is particularly suitable for application to a large current interrupting device that interrupts a large current in a current path for supplying a large current from a power source to a load.

Background Art

[0002] Conventionally, in Patent Document 1, a switch with an inrush current suppression device having a function of suppressing an inrush current when interrupting the supply of current in an electrical wiring has been proposed. This switch with an inrush current suppression device is provided in an electrical wiring through which current flows, and is configured such that a circuit in which a switch and a resistor are connected in series is connected in parallel to a circuit in which a main circuit breaker and a current transformer are connected in series.

[0003] In such a configuration, when turning on the switch to turn on the supply of current in the electrical wiring, the switch in which the resistor is inserted in series is first driven, and the main circuit breaker provided in the circuit in which no resistor is inserted is turned on and switched to the circuit on the main circuit breaker side. As a result, at the moment when the switch is turned on, a resistor is interposed in the current path to suppress the inrush current, and thereafter, current supply can be performed through the circuit in which no resistor is inserted.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the above-described switch with an inrush current suppression device cannot suppress the generation of a negative surge when switched off due to its configuration of inserting a resistor in the current path.

[0006] In view of the above points, this disclosure aims to provide a current interruption device that can suppress the generation of negative surges. [Means for solving the problem]

[0007] To achieve the above objective, the invention described in claim 1 is a current interruption device for interrupting the current flowing through an electrical wiring (2), comprising: a group of switches (SW) connected to the electrical wiring and connected in parallel to one another, having a plurality of switches (SW1 to SWn) that divide and distribute the current flowing through the electrical wiring; and a control circuit (20) that individually controls the on / off state of the plurality of switches, wherein when interrupting the current flowing through the electrical wiring, the control circuit repeatedly turns off some of the plurality of switches while turning on the remaining switches, gradually increasing the combined resistance value of the plurality of switches, and finally turns off all of the plurality of switches to interrupt the current.

[0008] In this way, by arranging the combination resistance of the switches that are turned on to increase in stages, the decrease in current when the switch is turned off becomes gentler, and the occurrence of negative surges can be suppressed.

[0009] For example, as in the invention described in claim 2, when interrupting power, the control circuit may sequentially turn off one or more of the multiple switches and turn on the remaining switches, and then repeat the operation of increasing the number of off switches among the multiple switches and turning off the remaining switches.

[0010] The invention described in claim 3 includes a current detection unit (40) for detecting the magnitude of the current flowing through the electrical wiring, and the control circuit performs at least one of the following: the larger the magnitude of the current, the fewer the number of off switches used when interrupting the circuit, or the fewer the number of off switches used to gradually increase the combined resistance value.

[0011] This allows for the suppression of negative surges while simultaneously adjusting the number of off-switches at the time of interruption and the subsequent increase in the number of off-switches according to the magnitude of the current flowing through the electrical wiring, thereby optimizing the time required for interruption.

[0012] The invention described in claim 4 includes temperature sensors (S1 to Sn) that detect the temperature of each of the multiple switches, and the control circuit, based on the detection results of the temperature sensors, preferentially turns off the switches with higher temperatures and turns on the switches with lower temperatures.

[0013] In this way, by switching on a switch that is not overheating among multiple switches, it is possible to avoid thermal damage to the switches due to high temperatures.

[0014] The reference numerals in parentheses attached to each component indicate an example of the correspondence between that component and the specific components described in the embodiments described later. [Brief explanation of the drawing]

[0015] [Figure 1] This is a circuit diagram of a current interruption device according to a first embodiment of the present disclosure. [Figure 2] This is a timing chart showing the operation of a current interruption device, presented as a comparative example. [Figure 3] This is a timing chart showing the operation of the current interruption device according to the first embodiment. [Figure 4] This is a circuit diagram of a current interruption device according to a second embodiment of the present disclosure. [Figure 5] This is a circuit diagram of a current interruption device according to a third embodiment of the present disclosure. [Modes for carrying out the invention]

[0016] The embodiments of the present invention will be described below with reference to the drawings. In the following embodiments, parts that are the same or equivalent to each other will be denoted by the same reference numerals.

[0017] (First Embodiment) FIG. 1 is a circuit diagram of a current interruption device 1 according to the first embodiment of the present disclosure. As shown in this figure, the current interruption device 1 is provided in an electrical wiring 2 that constitutes a current path through which current is supplied. In the present embodiment, a case where the current interruption device 1 is applied as a large current interruption device provided between a load 4 driven by a large current and a power supply 3 will be described as an example. However, the current interruption device 1 can be applied even if it is not for interrupting a large current.

[0018] Note that, for example, when the power supply 3 is a vehicle battery, it is a 12V power supply or the like. The load 4 is, for example, an in-vehicle electrical device or the like. When the load 4 is a large current load, when the load 4 is driven, a large current exceeding 100A, for example, a current of 120A, is supplied to the load 4 through the electrical wiring 2.

[0019] As shown in FIG. 1, the current interruption device 1 includes a mechanical switch 10, a control circuit 20, and a switch group SW.

[0020] The mechanical switch 10 is turned on and off by a user, and turns on and off the current path by the current interruption device 1, that is, conducts and interrupts the current. For example, it is composed of a toggle switch or the like. The operation state of the mechanical switch 10 is input to the control circuit 20 as an electrical signal.

[0021] The control circuit 20 controls the on and off of the current path by the current interruption device 1 by controlling the switch group SW according to the operation state of the mechanical switch 10. Specifically, when the mechanical switch 10 is changed from the off state to the on state, the control circuit 20 switches the switch group SW to the conductive state, and when the mechanical switch 10 is changed from the on state to the off state, the control circuit 20 switches the switch group SW to the interrupted state. The method of controlling the switch group SW by this control circuit 20 will be described later.

[0022] The switch group SW is composed of a plurality of switches SW1 to SWn connected in parallel with each other. The current flowing through the electrical wiring 2 is shunted by the plurality of switches SW1 to SWn.

[0023] More specifically, the plurality of switches SW1 to SWn are each connected to the electrical wiring 2 that constitutes the current path. The number of switches SW1 to SWn is arbitrary, and here it is illustrated as n for convenience, but n may be any natural number of 2 or more, for example, 100.

[0024] The switches SW1 to SWn can each be individually turned on and off based on a control signal from the control circuit 20. For example, each of the switches SW1 to SWn is composed of semiconductor switching elements formed on a semiconductor chip 30 of one chip. Here, an example in which an n-type MOSFET is applied as the semiconductor switching element is shown, but it may also be a p-type MOSFET, npn bipolar transistor, pnp bipolar transistor, etc., or it may be an IGBT, thyristor, etc.

[0025] The semiconductor switching element has an on-resistance determined by its element characteristics even when it is on. Therefore, the combined resistance value of the switch group SW changes according to the number of switches SW1 to SWn that are on. In this embodiment, each of the switches SW1 to SWn has the same on-resistance by having the same element structure. In this case, the combined resistance value of the switches SW1 to SWn decreases as the number of on switches increases, and increases as the number of on switches decreases. Note that the diodes D1 to Dn connected in parallel to each of the switches SW1 to SWn are freewheeling diodes. The diodes D1 to Dn may be mounted as separate components from the switches SW1 to SWn, but in the case of a MOSFET, etc., they may be built-in diodes.

[0026] Subsequently, the operation of the current cutoff device 1 configured as described above will be described while comparing it with a comparative example.

[0027] Figure 2 is a timing chart showing the operation of current interruption device 1 as a comparative example. Figure 3 is a timing chart showing the operation of current interruption device 1 according to this embodiment.

[0028] When switching the current supply from power source 3 to load 4 on and off, a typical switch would only switch between the ON state and the OFF state of the current supply. In this configuration, even when using the current interruption device 1 of this embodiment, as shown at time T1 in Figure 2, when turning on the current supply from power source 3 to load 4, all of the switches SW1 to SWn will be turned ON simultaneously. Similarly, as shown at time T2 in Figure 2, when turning off the current supply from power source 3 to load 4, all of the switches SW1 to SWn will be turned OFF simultaneously.

[0029] When switching on the current supply from power supply 3 to load 4, even if all switches SW1 to SWn are turned on simultaneously, no negative surge problem occurs.

[0030] However, if all switches SW1 to SWn are turned off simultaneously when switching off the current supply from power source 3 to load 4, a negative surge will be generated. This could potentially affect other in-vehicle ECUs (electronic control units), for example.

[0031] Therefore, in the current interruption device 1 of this embodiment, when turning on the current supply from the power supply 3 to the load 4, all of the switches SW1 to SWn are turned on simultaneously, but when turning off the current supply from the power supply 3 to the load 4, the switches SW1 to SWn are turned off in multiple stages.

[0032] Here, if all switches SW1 to SWn are in the ON position, and the voltage of power supply 3 is 12V and the current flowing through load 4 is 120A, then the combined resistance value between the current path via current interruption device 1 and load 4 will be 0.1Ω. Also, assume that the resistance value of switches SW1 to SWn inside the switch group SW is 0.1Ω, and that there are 100 switches SW1 to SWn (n=100).

[0033] As described above, when energizing load 4, all switches SW1 to SWn are turned ON. In this case, the combined resistance of switches SW1 to SWn is 1 mΩ, which is a sufficiently small resistance for load 4, so its effect on the current can be ignored. On the other hand, when interrupting the power supply to load 4, if all switches SW1 to SWn are turned OFF simultaneously, the current decrease gradient at the time of interruption becomes steep, and a negative surge is generated based on the inductance component of the wiring and the steeply decreasing current.

[0034] To prevent negative surges, when switching off the current supply from power supply 3 to load 4, multiple switches SW1 to SWn should be switched off in multiple stages, so that the combined resistance of the remaining switches increases gradually. In this way, the decrease in current at the time of interruption becomes gentler, and the occurrence of negative surges can be suppressed. To achieve this, the operation of switching off some of the multiple switches SW1 to SWn and keeping the rest on should be repeated, gradually increasing the number of switches that are switched off (hereinafter referred to as the number of off switches). However, if load 4 is a high-current load, the current flowing through the supply path will be large, and it is expected that switches SW1 to SWn will be thermally damaged. For this reason, it is preferable to switch the switches that are to be switched off at high speed to suppress overheating of the switches that remain on, thereby suppressing thermal damage to switches SW1 to SWn.

[0035] Figure 3 shows an example of its operation. As shown in this figure, after switching SW1 to SW2, the switches SW3 and SW4 are switched to SW1 to SWn one by one in sequence. When switching SW2 to SW2, switch SW1 is turned back to ON so that only one of the switches SW1 to SWn is switched off at a time. The duration for which each switch SW1 to SWn is switched off is short, for example, about 1 to a few microseconds.

[0036] However, since it is difficult to perfectly synchronize the timing of turning on switch SWm after turning off switch SWm, it is acceptable to allow a slight overlap between the period when switch SWm is off and the period when switch SWm+1 is off. Note that m used here is a natural number smaller than n.

[0037] In this way, during the period I1 between time point Ta and time point Tb, the combined resistance of the switch group SW increases by the amount that one of switches SW1 to SWn is in the OFF state, and the current supplied from power supply 3 to load 4 decreases.

[0038] After period I1, switches SW1 and SW2 are turned off simultaneously as a pair, and the remaining switches SW3 through SWn are turned on. Then, switches SW3 and SW4 are turned off as a pair, and the remaining switches SW1, SW2, and SW5 through SWn are turned on. After this, the operation of turning off two of the switches SW5 through SWn as a pair and turning on the rest is repeated.

[0039] In this way, during period I2, which is between time point Tb and time point Tc, the combined resistance of the switch group SW increases by the amount that two of switches SW1 to SWn are in the OFF state, and the current supplied from power supply 3 to load 4 decreases compared to period I1.

[0040] Following period I2, switches SW1-SW3 are turned off simultaneously as a set, and the remaining switches SW4-SWn are turned on. Then, switches SW4-SW6 are turned off as a set, and the remaining switches SW1-SW3 and SW7-SWn are turned on. After this, the operation of turning off three of switches SW7-SWn as a set and turning on the rest is repeated.

[0041] In this way, during period I3, which is between time point Tc, the combined resistance of the switch group SW increases by the amount that three of switches SW1 to SWn are in the OFF state, and the current supplied from power supply 3 to load 4 decreases compared to period I2.

[0042] After that, the process of turning off four switches at a time from SW1 to SWn, and turning on the remaining switches, is repeated in sequence, gradually increasing the number of switches that are turned off. Finally, all switches SW1 to SWn are turned off to completely shut off the current path.

[0043] Note that as the number of switches SW1 to SWn that need to be turned off simultaneously increases, the number of switches that can be turned off simultaneously in the last set may become insufficient. In that case, simply add the missing number of switches to the set, starting from SW1, and turn them off simultaneously. After that, you can repeat the process of turning off switches SW1 to SWn, starting with the switch after the one that was turned off to make up the numbers, in sets of more switches than the number of switches that were turned off simultaneously in the previous set.

[0044] As described above, it becomes possible to gradually reduce the current supplied to load 4, thereby suppressing the occurrence of negative surges that would occur if the current were to decrease abruptly. This prevents negative surges from affecting other in-vehicle ECUs and other components.

[0045] (Modified version of the first embodiment) As described above, in the first embodiment, when the current interruption device 1 interrupts the current path from the power supply 3 to the load 4, the switches SW1 to SWn are turned off one by one in sequence, and then two switches are turned off in sequence, increasing the number of switches turned off by one each time.

[0046] However, this is merely one example, and the number of off switches can be increased in stages, with both the initial number of off switches and the subsequent number of off switches being arbitrary. In other words, when the current interruption device 1 interrupts the current path from the power supply 3 to the load 4, the combined resistance value of the switches SW1 to SWn that are in the ON state should increase in stages.

[0047] For example, you could start by repeatedly turning off two switches SW1 to SWn as a set, then repeatedly turn off four switches SW1 to SWn as a set, and then gradually increase the number of switches turned off.

[0048] Furthermore, while the minimum number of switches to remain in the ON state is one, if only one switch is turned on, the current flowing through that switch may become too large. For this reason, a lower limit can be set for the number of switches to remain in the ON state, allowing for two or more switches.

[0049] (Second Embodiment) A second embodiment will now be described. Figure 4 is a circuit diagram of the current interruption device 1 according to this embodiment.

[0050] As shown in Figure 4, this embodiment includes a current detection unit 40 that detects the current flowing through the electrical wiring 2. The current detection unit 40 outputs a signal as a detection result corresponding to the magnitude of the current flowing through the electrical wiring 2. For example, the current detection unit 40 is composed of a shunt resistor or the like. The signal indicating the detection result from this current detection unit 40 is fed back to the control circuit 20. The control circuit 20 then adjusts the number of off switches when shutting off the current interruption device 1 based on the detection result from the current detection unit 40.

[0051] For example, the larger the current detected by the current detection unit 40, the smaller the initial number of off-switches when interrupting the circuit, or the smaller the number of off-switches that are subsequently increased.

[0052] The more off-switches initially used during interruption, and the more off-switches are added afterward, the steeper the current decrease gradient becomes during interruption. Furthermore, the larger the current flowing through electrical wiring 2, the steeper the current decrease gradient becomes, even if the initial number of off-switches and the subsequent number of off-switches added remain the same. Therefore, the larger the current flowing through electrical wiring 2, the smaller the initial number of off-switches used during interruption, and the smaller the number of off-switches added afterward, the gentler the current decrease gradient becomes during interruption. This allows for the suppression of negative surges while adjusting the number of off-switches used during interruption and the subsequent number of off-switches added according to the magnitude of the current flowing through electrical wiring 2, thereby optimizing the time required for interruption.

[0053] (Third embodiment) A third embodiment will now be described. Figure 5 is a circuit diagram of the current interruption device 1 according to this embodiment.

[0054] As shown in Figure 5, this embodiment includes temperature sensors TS1 to TSn that detect the temperature of each switch SW1 to SWn. The temperature sensors TS1 to TSn are constructed, for example, by fabricating temperature-sensitive diodes adjacent to each switch SW1 to SWn in a semiconductor chip having switches SW1 to SWn, and output a detection signal corresponding to the temperature of each switch SW1 to SWn. The signals indicating the detection results from these temperature sensors TS1 to TSn are fed back to the control circuit 20. The control circuit 20 can then determine, based on the detection results from the temperature sensors TS1 to TSn, which of the switches SW1 to SWn should be turned off when shutting off the current interruption device 1, in other words, which switches should be excluded from being left on. The control circuit 20 can also adjust the number of off switches based on the detection results from the temperature sensors TS1 to TSn.

[0055] If temperature sensors TS1 to TSn detect that any of switches SW1 to SWn are overheating, it is best to allow that switch to cool down by discharging power to avoid overheating damage. Therefore, switches SW1 to SWn are prioritized to be turned off, and switches with lower temperatures are turned on, thus excluding switches that are turned on when they are overheating.

[0056] Specifically, the system selects the number of switches to turn on in order from the lowest temperature among switches SW1 to SWn, or it selects the number of switches to turn on from the remaining switches after excluding those with high temperatures. For example, switches SW1 to SWn that have exceeded a threshold temperature according to temperature sensors TS1 to TSn are excluded from being turned on. In this way, by turning on switches SW1 to SWn that have not become hot, it is possible to avoid thermal damage to switches SW1 to SWn due to high temperatures.

[0057] (Other embodiments) This disclosure is written in accordance with the embodiments described above, but is not limited to those embodiments and includes various modifications and variations within the scope of equivalents. In addition, various combinations and forms, as well as other combinations and forms that include only one, more, or fewer of those elements, fall within the scope and concept of this disclosure.

[0058] For example, in each of the above embodiments, the mechanical switch 10 is shown as being located inside the current interruption device 1. However, this is just one example, and the mechanical switch 10 may be located outside the current interruption device 1, with only an electrical signal indicating the operating state of the mechanical switch 10 being input to the current interruption device 1.

[0059] Furthermore, although the above embodiments show an example of a structure in which the switch group SW is provided on a single semiconductor chip 30, the control circuit 20 may also be mounted on the same chip to form a single integrated circuit.

[0060] Furthermore, in the third embodiment described above, each switch SW1 to SWn is provided with a temperature sensor TS1 to TSn, but it is not necessarily required to provide a temperature sensor in a one-to-one ratio with each switch. For example, one temperature sensor may be provided for multiple switches.

[0061] Furthermore, in the above embodiment, when the current interruption device 1 interrupts the electrical wiring 2, the order in which switches SW1 to SWn are turned off is SW1, SW2, and the reference numeral order, but this order is arbitrary. Also, for sets of multiple switches that are turned off simultaneously, any number of switches from SW1 to SWn can be arbitrarily selected, and the reference numeral order is not required.

[0062] Furthermore, while the above embodiments assume that multiple switches SW1 to SWn are composed of semiconductor switching elements with the same on-resistance, the on-resistances of each switch SW1 to SWn may be different. For example, when the semiconductor switching elements are composed of MOSFETs or IGBTs, the on-resistance can be changed by varying the size of one of the element's components, such as by varying the gate length, or by changing the impurity concentration. Alternatively, a resistor may be added in series with the semiconductor switching element.

[0063] When the on-resistances are different in this way, when the current interruption device 1 interrupts the electrical wiring 2, for example, switches SW1 to SWn can be turned off in order from the one with the highest on-resistance. Of course, in this case as well, multiple switches SW1 to SWn can be turned off simultaneously as a set. Then, gradually, the combination of switches SW1 to SWn that are turned off is changed and the switches are turned off in order, so that the combined resistance value of the current interruption device 1 with only the switches SW1 to SWn that are on gradually increases.

[0064] Furthermore, the above embodiments are not unrelated to each other and can be combined as appropriate, except in cases where combination is clearly impossible. Also, it goes without saying that the elements constituting the embodiments are not necessarily essential, except when explicitly stated as particularly essential or when clearly considered essential in principle. Furthermore, when numerical values ​​such as the number, numerical values, quantities, or ranges of the constituent elements of the embodiments are mentioned, the embodiments are not limited to those specific numbers, except when explicitly stated as particularly essential or when clearly limited in principle to a specific number. Also, when the shapes, positional relationships, etc., of the constituent elements are mentioned in the above embodiments, the embodiments are not limited to those shapes, positional relationships, etc., except when explicitly stated or when clearly limited in principle to a specific shape, positional relationship, etc.

[0065] Furthermore, the control circuit 20 and its method described in this disclosure may be implemented by a dedicated computer provided by configuring a processor and memory programmed to perform one or more functions embodied by a computer program. Alternatively, the control unit 20 and its method described in this disclosure may be implemented by a dedicated computer provided by configuring a processor with one or more dedicated hardware logic circuits. Alternatively, the control unit 20 and its method described in this disclosure may be implemented by one or more dedicated computers configured by a combination of a processor and memory programmed to perform one or more functions and a processor configured with one or more hardware logic circuits. The computer program may also be stored as instructions executed by the computer on a computer-readable non-transitional tangible recording medium. [Explanation of Symbols]

[0066] 1...Current interruption device, 2...Electrical wiring, 3...Power supply, 4...Load, 10...Mechanical switch 20...Control circuit, 30...Semiconductor chip, 40...Current detection unit, D1...Diode SW...Group of switches, SW1~SWn...Switches, TS1~TSn...Temperature sensors

Claims

1. A current interruption device for interrupting the current flowing through electrical wiring (2), A group of switches (SW) having multiple switches (SW1 to SWn) connected to the aforementioned electrical wiring, connected in parallel to each other, and which divide and distribute the current flowing through the aforementioned electrical wiring, The system includes a control circuit (20) that individually controls the on / off state of the plurality of switches, The control circuit is a current interruption device that, when interrupting the current flowing through the electrical wiring, repeatedly turns off some of the multiple switches while turning on the remaining switches, thereby gradually increasing the combined resistance value of the multiple switches, and finally turns off all of the multiple switches to interrupt the current.

2. The current interruption device according to claim 1, wherein the control circuit, when interrupted, sequentially turns off one or more of the plurality of switches and turns on the remaining switches, and then repeats the operation of increasing the number of off switches among the plurality of switches and turning on the remaining switches.

3. It has a current detection unit (40) that detects the magnitude of the current flowing through the electrical wiring, The current interruption device according to claim 2, wherein the control circuit performs at least one of the following: the larger the magnitude of the current, the fewer the number of off switches used during interruption, or the fewer the number of off switches used to gradually increase the combined resistance value.

4. Each of the aforementioned switches has a temperature sensor (TS1 to TSn) that detects its temperature. The current interruption device according to any one of claims 1 to 3, wherein the control circuit, based on the detection result of the temperature sensor, preferentially turns off the switches with higher temperatures among the plurality of switches and turns on the switches with lower temperatures.

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