Current control device

Abstract

This current control device is provided with an input terminal, an output terminal, a fuse, and a variable resistance unit. A power supply is connected to the input terminal. A load is connected to the output terminal. The fuse is disposed on a circuit that electrically connects the input terminal and the output terminal. The variable resistance part is electrically connected between the fuse and the input terminal on the circuit, and the resistance value of the variable resistance part increases according to the increase of the current flowing through the circuit.

Description

Technical Field

[0001] The present disclosure generally relates to current control devices. More particularly, the present disclosure relates to current control devices that reduce current from a power source to a load. Background Art

[0002] The protection device described in Patent Document 1 is provided between an input power supply that supplies DC power and a load device that receives operating power from the input power supply. The protection device includes a fuse, a surge voltage absorbing unit, a surge voltage suppressing unit, a backflow prevention unit, a current reducing unit, and a filter unit. The fuse is connected in series to the connection line between the input power supply and the load device. The surge voltage absorbing unit absorbs surge voltages flowing from the input power supply. The surge voltage suppressing unit suppresses surge voltages flowing from the input power supply. The backflow prevention unit blocks current from the load device side to the input power supply side. The current reducing unit reduces current from the input power supply to the load device. The filter unit reduces noise contained in the DC power supplied from the input power supply. The fuse, surge voltage absorbing unit, surge voltage suppressing unit, backflow prevention unit, current reducing unit, and filter unit are connected in sequence from the input power supply side to the load device side.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2020-167807 Summary of the Invention

[0006] In the protection device described in Patent Document 1, if the current reduction capability of the current reduction unit is set to sufficiently reduce abnormal currents such as short-circuit current and inrush current, the voltage drop across the current reduction unit during normal times, when a stable current flows, increases, potentially affecting the operation of the load device. Furthermore, if the current reduction capability of the current reduction unit is set to such that the voltage drop across the current reduction unit does not affect the operation of the load device during normal times, the abnormal current will not be sufficiently reduced in the current reduction unit, necessitating a fuse with a high current cutoff, potentially increasing costs. Therefore, in the protection device described in Patent Document 1, there is a desire to appropriately control the current reduction capability in response to current fluctuations.

[0007] A current control device according to one embodiment of the present invention comprises: an input terminal for connecting a power source; an output terminal for connecting a load; a fuse arranged on a circuit electrically connecting the input terminal and the output terminal; and a variable resistor portion electrically connected between the fuse and the input terminal on the circuit, wherein the resistance value increases in accordance with an increase in the current flowing through the circuit.

[0008] According to the present disclosure, the ability to reduce the current can be appropriately controlled according to changes in the current. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 This is a simulation block diagram of a current control device according to each embodiment of the present disclosure.

[0010] Figure 2 This is a circuit diagram of the current control device according to the first embodiment of the present disclosure.

[0011] Figure 3 Graphs showing changes in the resistance value of the variable resistor portion of the current control device according to each embodiment of the present disclosure.

[0012] Figure 4 This is a circuit diagram of a current control device according to a second embodiment of the present disclosure. DETAILED DESCRIPTION

[0013] A current control device 1 according to an embodiment of the present disclosure will be described in detail with reference to the accompanying drawings. The embodiment and variations described below are merely examples of the present disclosure and are not limited to these embodiments and variations. Various modifications, including design changes, are possible, other than these embodiments and variations, without departing from the scope of the technical concept of the present disclosure.

[0014] (Implementation Method 1)

[0015] (1) Summary

[0016] First, refer to Figure 1 The outline of the current controller 1 according to this embodiment will be described.

[0017] The current control device 1 is a device that controls the current flowing through the load L1 in order to protect the load L1 from abnormal currents such as short-circuit current and inrush current.

[0018] The current control device 1 is mounted on, for example, a vehicle-mounted backup power supply system. Alternatively, the current control device 1 may be mounted on a power supply system used in a multi-family house, a single-family house, an office building, a commercial building, a hotel, a factory, a store, or the like.

[0019] like Figure 1 As shown, the current control device 1 includes an input terminal 2 , an output terminal 3 , a fuse 4 , and a variable resistor 5 .

[0020] Connect power supply PS1 to input terminal 2.

[0021] A load L1 is connected to the output terminal 3 .

[0022] The fuse 4 is arranged in the electric path AL1 that electrically connects the input terminal 2 and the output terminal 3 .

[0023] The variable resistor 5 is electrically connected between the fuse 4 and the input terminal 2 , and its resistance value increases as the current flowing through the electric path AL1 increases, and decreases as the current decreases.

[0024] With the above configuration, the resistance value of variable resistor unit 5 increases as the current flowing through circuit AL1 increases, thereby appropriately controlling the current reduction capability in response to changes in the current flowing through circuit AL1. Specifically, in current control device 1, when an abnormal current flows through circuit AL1, the resistance value of variable resistor unit 5 increases, thereby enhancing the current reduction capability. Furthermore, when a stable current flows through circuit AL1, the possibility of a voltage drop across variable resistor unit 5 affecting the operation of load L1 can be minimized.

[0025] Furthermore, in the current control device 1, as described above, the variable resistor unit 5 can reduce the abnormal current, so the fuse 4 can be a small fuse with a low cutting current. This can prevent problems such as increased costs that would occur if the fuse 4 were a large fuse with a high cutting current, and problems such as poor matching of the fuse 4's melting characteristics with the load L1 (fuse 4 not melting when load L1 needs to be protected) from occurring.

[0026] (2) Details

[0027] Below, refer to Figures 1 to 3 The current controller 1 according to this embodiment will be described in detail.

[0028] (2.1) Overall structure

[0029] like Figure 1 As shown, the current control device 1 includes an input terminal 2 , an output terminal 3 , a fuse 4 , and a variable resistor 5 .

[0030] The input terminal 2 is connected to a high potential side terminal of a power supply PS1 as a DC power supply, for example. The power supply PS1 includes, for example, a DC / DC converter or a linear regulator.

[0031] The output terminal 3 is connected to a load L1 as a DC load, for example. Figure 2 As shown, the load L1 includes a load circuit C1 and a load switch SW2 , and the output terminal 3 is connected to the load switch SW2 .

[0032] The load circuit C1 includes various electronic components such as a resistor and a capacitor.

[0033] The load switch SW2 is, for example, an N-channel enhancement-mode MOSFET (Metal Oxide Semiconductor Field Effect Transistor). The gate electrode of the load switch SW2 is connected to a control unit (not shown) included in a device (such as an on-board backup power supply system) equipped with the current control device 1. The load switch SW2 is switched on and off by the gate voltage applied by the control unit of the device equipped with the current control device 1.

[0034] When the load switch SW2 is turned on, power is supplied from the power supply PS1 to the load circuit C1. The load switch SW2 is not limited to an N-channel enhancement-mode MOSFET, but may be another semiconductor switching element such as an IGBT (Insulated Gate Bipolar Transistor) or a bipolar transistor.

[0035] The fuse 4 is, for example, a glass tube fuse. Alternatively, the fuse 4 may be a ceramic fuse or the like. Alternatively, the fuse 4 may be a pattern fuse in which at least a portion of the wiring pattern of the printed wiring board is thinner than the other portions.

[0036] Fuse 4 is disposed in circuit AL1 electrically connecting input terminal 2 and output terminal 3. Fuse 4 melts when a current (abnormal current) exceeding a predetermined current value flows through circuit AL1, thereby blocking the abnormal current from flowing into load L1 and protecting load L1.

[0037] The variable resistor 5 is electrically connected between the fuse 4 and the input terminal 2 .

[0038] The variable resistor unit 5 includes a variable resistor element SW1 and a voltage control unit 6. Figure 2 As shown, the variable resistor unit 5 further includes voltage dividing resistors R1 and R2.

[0039] like Figure 2 As shown, the variable resistance element SW1 is, for example, a P-channel enhancement mode MOSFET.

[0040] The variable resistive element SW1 includes a first electrode E1 serving as a gate electrode, a second electrode E2 serving as a source electrode, and a third electrode E3 serving as a drain electrode. The second electrode E2 is connected to the input terminal 2 via a resistor R3 (described later). Furthermore, the third electrode E3 is connected to the output terminal 3 via a fuse 4. In other words, the current flowing through the circuit AL1 flows between the second electrode E2 and the third electrode E3.

[0041] The variable resistor element SW1 controls the resistance value Rds between the second electrode E2 and the third electrode E3 based on the potential difference (gate-source voltage) ΔV between the first voltage (gate voltage) V1 applied to the first electrode E1 and the second voltage (source voltage) V2 applied to the second electrode E2. The potential difference ΔV is the value obtained by subtracting the first voltage V1 from the second voltage V2. The variable resistor element SW1 is a P-channel enhancement-mode MOSFET. When the second electrode E2 has a higher potential than the first electrode E1, the resistance value Rds changes. Therefore, in the current control device 1 of this embodiment, the second voltage V2 is controlled to be greater than the first voltage V1.

[0042] like Figure 3 As shown, when the potential difference ΔV is within the predetermined range T1, the variable resistive element SW1 increases the resistance value Rds between the second electrode E2 and the third electrode E3 in accordance with the decrease in the potential difference ΔV. Figure 3 This is a graph in which the horizontal axis represents the potential difference ΔV and the vertical axis represents the resistance value Rds.

[0043] Here, the specified range T1 is the range of the potential difference ΔV that causes the MOSFET to operate in the so-called linear region. The linear region refers to the region where the resistance value Rds of the MOSFET changes according to the potential difference ΔV. If the potential difference ΔV is greater than the upper limit of the specified range T1, the MOSFET is saturated. If the potential difference ΔV is less than the lower limit of the specified range T1, the MOSFET is cut off and the resistance value Rds of the MOSFET does not change according to the potential difference ΔV. Figure 3 In the example, the specified range T1 is the range of the potential difference ΔV between Δv1 and Δv2. Within the specified range T1, as the potential difference ΔV approaches Δv1, the resistance value Rds diverges toward infinity. As the potential difference ΔV approaches Δv2, the resistance value Rds approaches a constant value.

[0044] The linear region is the region where increasing the potential difference Vds between the second electrode E2 and the third electrode E3 increases the current Id flowing from the second electrode E2 to the third electrode E3. Furthermore, when the MOSFET operates in the linear region, increasing the potential difference (gate-source voltage) ΔV increases the slope of the output characteristic (current Id - potential difference Vds characteristic). The slope of the output characteristic (current Id - potential difference Vds characteristic) is the inverse of the resistance Rds between the second electrode E2 and the third electrode E3. Therefore, within the specified range T1, the resistance Rds decreases as the potential difference ΔV increases, while the resistance Rds increases as the potential difference ΔV decreases.

[0045] like Figure 2 As shown, the voltage control unit 6 includes a resistor R3 electrically connected between the input terminal 2 and the variable resistance element SW1 .

[0046] like Figure 2 As shown, voltage-dividing resistors R1 and R2 are connected in series between input terminal 2 and resistor R3's connection point P1 on circuit AL1 and ground GND. More specifically, one terminal of voltage-dividing resistor R1 is connected to connection point P1, and the other terminal of voltage-dividing resistor R1 is connected to voltage-dividing resistor R2 at connection point P2. Furthermore, one terminal of voltage-dividing resistor R2 is connected to voltage-dividing resistor R1 at connection point P2, and the other terminal of voltage-dividing resistor R2 is connected to ground GND. Connection point P2 between voltage-dividing resistors R1 and R2 is connected to first electrode E1 of variable resistive element SW1.

[0047] Voltage-dividing resistors R1 and R2 divide the input voltage Vin from power supply PS1 to generate a first voltage (gate voltage) applied to first electrode E1. Here, if the resistance values ​​of voltage-dividing resistors R1 and R2 are r1 and r2, respectively, and the value of input voltage Vin is vin, then the value of first voltage V1 is vin·r1 / (r1+r2). In this way, first voltage V1 is divided to a value smaller than input voltage Vin.

[0048] (2.2) Setting the first voltage

[0049] Below, refer to Figure 3 The setting of the first voltage (gate voltage) V1 will be described.

[0050] As described above, the first voltage V1 is generated by dividing the input voltage Vin by the voltage-dividing resistors R1 and R2. That is, the value of the first voltage V1 can be set by selecting the resistance values ​​of the voltage-dividing resistors R1 and R2. As long as the input voltage Vin is constant, the first voltage V1 remains constant.

[0051] In this embodiment, the value of the first voltage V1 is set so that the potential difference ΔV is within a predetermined range T1 when the current value of the current flowing through the circuit AL1 is a predetermined current value i1 that is less than the rated current of the fuse 4. Here, the predetermined current value i1 that is less than the rated current of the fuse 4 is, for example, the current value of the stable current I1 flowing through the circuit AL1 when the load L1 is operating normally. That is, the potential difference ΔV when the stable current I1 flows through the circuit AL1 is ΔV(I1). Figure 3 As shown, it is within the specified range T1.

[0052] Here, if the resistance value of resistor R3 is r3, the voltage drop across resistor R3 when steady current I1 flows through load L1 is i1·r3. Furthermore, if the value of first voltage V1 is v1 and the value of input voltage Vin is vin, the potential difference ΔV1(I1) when steady current I1 flows through load L1 is vin-i1·r3-v1. That is, the value of first voltage V1 is set so that vin-i1·r3-v1 is between Δv1 and Δv2. Alternatively, the resistance value of resistor R3 may be set along with the value of first voltage V1 so that vin-i1·r3-v1 is between Δv1 and Δv2. Here, the value between Δv1 and Δv2 is, for example, a value greater than Δv1 and less than Δv2. Alternatively, the value between Δv1 and Δv2 may be, for example, a value greater than Δv1 and less than Δv2.

[0053] More specifically, the value v1 of the first voltage V1 is set so that when the current value of the current flowing through the circuit AL1 is a predetermined current value i1 that is less than the rated current of the fuse 4, the ratio of the absolute value of the change in the resistance value Rds to the absolute value of the change in the potential difference ΔV becomes a predetermined value. Here, the ratio of the absolute value of the change in the resistance value Rds to the absolute value of the change in the potential difference ΔV corresponds to Figure 3 The absolute value of the slope of the tangent line TL on the curve CV1 in FIG. Specifically, the value v1 of the first voltage V1 is set so that the absolute value of the slope of the tangent line TL to the curve CV1, i.e., the tangent line TL(ΔV1), when a steady current I1 flows through the circuit AL1 and the potential difference ΔV is the potential difference ΔV1(I1), reaches a predetermined value. When the unit of the resistance value Rds is [mΩ] and the unit of the potential difference ΔV is [V], the predetermined value is preferably in the range of 0.1 to 0.3.

[0054] like Figure 3 As shown, within the specified range T1, the greater the potential difference ΔV, the smaller the absolute value of the slope of the tangent line TL, and the smaller the potential difference ΔV, the larger the absolute value of the slope of the tangent line TL. Therefore, within the specified range T1, if the potential difference ΔV is less than the potential difference ΔV1 (I1), the absolute value of the slope of the tangent line TL exceeds the specified value, causing the resistance value Rds to rise sharply. Conversely, if the potential difference ΔV is greater than the potential difference ΔV1 (I1) within the specified range T1, the absolute value of the slope of the tangent line TL falls below the specified value, causing the resistance value Rds to decrease.

[0055] (2.3) Action example

[0056] Below, refer to Figure 2 and Figure 3 An operation example of the current control device 1 will be described. In the following description, it is assumed that the load switch SW2 is in the OFF state in the initial state.

[0057] First, when a control unit (not shown) included in a device (eg, a vehicle-mounted backup power supply system) equipped with the current control device 1 controls the load switch SW2 to be on, power is supplied from the power supply PS1 to the load circuit C1 .

[0058] At this time, when the load circuit C1 includes a capacitor including a capacitance component, an inrush current I2 flows from the power supply PS1 to the load circuit C1 .

[0059] The potential difference ΔV when inrush current I2 flows through circuit AL1, or the potential difference ΔV2 (I2), is vin - i2·r3 - v1. Here, the value i2 of inrush current I2 is greater than the specified current value i1 (the current value of steady-state current I1). That is, the voltage drop across resistor R3, i2·r3, is greater than the voltage drop across resistor R3 when steady-state current I1 flows through load L1, i1·r3. Therefore, the potential difference ΔV2 (I2) when inrush current I2 flows through circuit AL1, or vin - i2·r3 - v1, is smaller than the potential difference ΔV1 (I1) when steady-state current I1 flows through load L1, or vin - i1·r3 - v1. In other words, voltage control unit 6, including resistor R3, decreases potential difference ΔV as the current flowing through circuit AL1 increases.

[0060] like Figure 3 As shown, when the potential difference ΔV decreases from the potential difference ΔV1 ( I1 ) to the potential difference ΔV2 ( I2 ), the resistance value Rds between the second electrode E2 and the third electrode E3 increases sharply, thereby reducing the inrush current I2 .

[0061] Once the capacitor included in load circuit C1 has completed charging, the aforementioned steady current I1 begins to flow through circuit AL1. At this point, the potential difference ΔV changes from ΔV2 (I2) to ΔV1 (I1), causing the resistance value Rds to drop sharply. In other words, the voltage drop across variable resistor element SW1 decreases. This minimizes the effect of the voltage drop across variable resistor 5 on load L1 while steady current I1 flows through circuit AL1.

[0062] Similar to the case where the inrush current I2 flows through the circuit AL1, when a short-circuit current larger than the steady current I1 flows through the circuit AL1, the voltage control unit 6 also reduces the potential difference ΔV in accordance with the increase in the current flowing through the circuit AL1, thereby rapidly increasing the resistance value Rds and reducing the short-circuit current.

[0063] (Implementation Method 2)

[0064] Reference Figure 4A current controller 1A according to Embodiment 2 will be described. Components identical to those in Embodiment 1 are denoted by the same reference numerals, and description thereof will be omitted.

[0065] The current control device 1A of the present embodiment includes an input terminal 2 , an output terminal 3 , a fuse 4 , and a variable resistor unit 5A.

[0066] The variable resistor unit 5A is electrically connected between the fuse 4 and the input terminal 2. The variable resistor unit 5A includes a variable resistance element SW1 and a voltage control unit 6A.

[0067] The voltage control unit 6A includes a current monitoring unit 7 for detecting the current flowing through the electric path AL1 and a first voltage control unit 8 for controlling the first voltage V1 based on the detection result of the current monitoring unit 7. Figure 2 In the current control device 1 of the embodiment 1 shown, the first voltage V1 is constant, but Figure 4 In the current control device 1A according to the second embodiment shown, the first voltage V1 changes according to the current flow AL1 .

[0068] The current monitoring unit 7 is electrically connected between the input terminal 2 and the second electrode E2 of the variable resistor SW1. For example, the current monitoring unit 7 includes a shunt resistor electrically connected between the input terminal 2 and the variable resistor SW1. In this case, the current monitoring unit 7 outputs a voltage Vr across the shunt resistor, which is proportional to the current flowing through the circuit AL1, to an amplifier 9 included in the first voltage control unit 8, described later.

[0069] The first voltage control unit 8 includes a reference voltage generating unit 10 and an amplifier 9 .

[0070] The reference voltage generating unit 10 generates a reference voltage Vs. The reference voltage generating unit 10 outputs the generated reference voltage Vs to the amplifier 9 .

[0071] Amplifier 9 amplifies the difference between voltage Vr, which is proportional to the current detection result of current monitoring unit 7, and reference voltage Vs. Amplifier 9 is, for example, a differential amplifier, and outputs the voltage obtained by amplifying the difference (potential difference) between voltage Vr and reference voltage Vs at a predetermined amplification factor as a first voltage V1 to first electrode E1.

[0072] Here, as an example, the reference voltage Vs is set so that, when a steady current I1 (see Embodiment 1) flows through the circuit AL1, the potential difference ΔV between the first voltage V1 and the second voltage V2 becomes the potential difference ΔV1(I1). That is, when the steady current I1 flows through the circuit AL1, the amplifier 9 outputs the first voltage V1 to the first electrode E1 so that the potential difference ΔV becomes the potential difference ΔV1(I1).

[0073] If an abnormal current greater than the stable current I1 flows through the circuit AL1, the difference between the voltage Vr proportional to the current detection result of the current monitoring unit 7 and the reference voltage Vs increases. In other words, if an abnormal current greater than the stable current I1 flows through the circuit AL1, the value of the first voltage V1 output from the amplifier 9 increases. As a result, the potential difference ΔV decreases. Figure 3 As shown in FIG. 1 , when the potential difference ΔV decreases from the potential difference ΔV1 ( I1 ), the resistance value Rds between the second electrode E2 and the third electrode E3 increases sharply, thereby reducing the abnormal current.

[0074] (Variation)

[0075] The above embodiment is merely one of the various embodiments disclosed herein. As long as the above embodiment can achieve the objectives of this disclosure, various modifications can be made to the above embodiment according to design, etc. Below, examples of modifications to the above embodiment are listed. The modifications described below can be appropriately combined and applied.

[0076] In each of the above-described embodiments, the current control device 1 is configured not to include the power supply PS1 , but the present invention is not limited to this configuration, and the current control device 1 may include the power supply PS1 .

[0077] The variable resistance element SW1 in each of the above embodiments is not limited to a P-channel enhancement-mode MOSFET, and may be another semiconductor switching element such as an IGBT (Insulated Gate Bipolar Transistor) or a bipolar transistor.

[0078] The current monitoring unit 7 in the second embodiment is not limited to the shunt resistor, and may be an open-loop or closed-loop magnetic sensor or the like.

[0079] (Summarize)

[0080] As described above, the current control device (1) of the first embodiment comprises: an input terminal (2) connected to a power supply (PS1); an output terminal (3) connected to a load (L1); a fuse (4) arranged on a circuit (AL1) electrically connecting the input terminal (2) and the output terminal (3); and a variable resistor (5) electrically connected between the fuse (4) and the input terminal (2) on the circuit (AL1), wherein a resistance value (Rds) increases in accordance with an increase in a current flowing through the circuit (AL1).

[0081] According to this embodiment, the resistance value (Rds) of the variable resistor (5) increases in accordance with an increase in the current flowing through the circuit (AL1), thereby enabling the current reduction capability to be appropriately controlled in accordance with changes in the current flowing through the circuit (AL1).

[0082] In a current control device (1) of a second embodiment, in the first embodiment, the variable resistor unit (5) has a variable resistor element (SW1) and a voltage control unit (6). The variable resistor element (SW1) includes a first electrode (E1), a second electrode (E2), and a third electrode (E3). The variable resistor element (SW1) controls the resistance value (Rds) between the second electrode (E2) and the third electrode (E3) according to the potential difference (ΔV) between the first voltage (V1) applied to the first electrode (E1) and the second voltage (V2) applied to the second electrode (E2). When the potential difference (ΔV) is within a predetermined range (T1), the variable resistor element (SW1) increases the resistance value (Rds) between the second electrode (E2) and the third electrode (E3) according to the decrease in the potential difference (ΔV). The current flowing through the circuit (AL1) flows between the second electrode (E2) and the third electrode (E3). A voltage control unit (6) reduces a potential difference (ΔV) in response to an increase in a current flowing through a circuit (AL1).

[0083] According to this method, the resistance value (Rds) between the second electrode (E2) and the third electrode (E3) increases as the current flowing through the circuit (AL1) increases, thereby being able to appropriately control the current reduction capability according to changes in the current flowing through the circuit (AL1).

[0084] In a current control device (1) of a third embodiment, in the second embodiment, the value of the first voltage (V1) is set so that when the current value of the current flowing through the circuit (AL1) is a specified current value (i1) less than the rated current of the fuse (4), the potential difference (ΔV) is within a specified range (T1).

[0085] According to this embodiment, when an abnormal current greater than the rated current of the fuse (4) flows through the circuit (AL1), the potential difference (ΔV) is reduced, thereby increasing the resistance value (Rds).

[0086] In a current control device (1) of a fourth embodiment, in the third embodiment, the value of the first voltage (V1) is set so that when the current value of the current flowing through the circuit (AL1) is a specified current value (i1) less than the rated current of the fuse (4), the ratio of the absolute value of the change in the resistance value (Rds) to the absolute value of the change in the potential difference (ΔV) is a specified value.

[0087] According to this embodiment, when an abnormal current greater than the rated current of the fuse (4) flows through the circuit (AL1), the potential difference (ΔV) is reduced, thereby increasing the resistance value (Rds).

[0088] In a current control device (1) of a fifth embodiment, in any one of the second to fourth embodiments, the voltage control unit (6) includes a resistor (R3) electrically connected between the input terminal (2) and the variable resistance element (SW1).

[0089] According to this aspect, when an abnormal current flows through the circuit (AL1), the voltage drop across the resistor (R3) increases, thereby reducing the voltage difference (ΔV).

[0090] In a current control device (1) of the sixth embodiment, in the second embodiment, the voltage control unit (6) has a current monitoring unit (7) for detecting a current flowing through a circuit (AL1), and a first voltage control unit (8) for controlling a first voltage (V1) based on a detection result of the current monitoring unit (7).

[0091] According to this method, the resistance value (Rds) between the second electrode (E2) and the third electrode (E3) increases as the current flowing through the circuit (AL1) increases, thereby being able to appropriately control the current reduction capability according to changes in the current flowing through the circuit (AL1).

[0092] In a current control device (1) of a seventh embodiment, in the sixth embodiment, the first voltage control unit (8) includes an amplifier (9) that amplifies the difference between a voltage (Vr) proportional to a detection result of a current flowing through a circuit (AL1) of a current monitoring unit (7) and a reference voltage (Vs).

[0093] According to this method, the resistance value (Rds) between the second electrode (E2) and the third electrode (E3) increases as the current flowing through the circuit (AL1) increases, thereby being able to appropriately control the current reduction capability according to changes in the current flowing through the circuit (AL1).

[0094] In addition, the second to seventh modes are not essential structures of the current control device (1) and can be omitted as appropriate.

[0095] Description of Reference Numerals

[0096] 1. Current control device

[0097] 2 input terminals

[0098] 3 output terminals

[0099] 4 fuses

[0100] 5. Variable resistor unit

[0101] 6 Voltage control unit

[0102] 7Current monitoring unit

[0103] 81st voltage control unit

[0104] 9 amplifiers

[0105] AL1 circuit

[0106] E1 first electrode

[0107] E2 second electrode

[0108] E3 third electrode

[0109] i1 specifies the current value

[0110] L1 load

[0111] PS1 power supply

[0112] R3 resistor

[0113] Rds resistance value

[0114] SW1 variable resistor element

[0115] T1 Specified range

[0116] V1 1st voltage

[0117] V2 Second voltage

[0118] Vr voltage

[0119] Vs reference voltage

[0120] ΔV potential difference

Claims

1. A current control device, wherein: have: Input terminal, for power connection; Output terminals, for load connection; a fuse, disposed on a circuit electrically connecting the input terminal and the output terminal; as well as The variable resistor is electrically connected between the fuse and the input terminal in the circuit, and its resistance value increases in accordance with an increase in a current flowing through the circuit.

2. The current control device according to claim 1, wherein: The variable resistance unit includes a variable resistance element and a voltage control unit. The variable resistance element includes a first electrode, a second electrode, and a third electrode. The variable resistive element controls the resistance value between the second electrode and the third electrode according to a potential difference between a first voltage applied to the first electrode and a second voltage applied to the second electrode. When the potential difference is within a predetermined range, the variable resistive element increases the resistance value between the second electrode and the third electrode in response to a decrease in the potential difference. The current flows between the second electrode and the third electrode, The voltage control unit reduces the potential difference in response to an increase in the current.

3. The current control device according to claim 2, wherein: The value of the first voltage is set so that the potential difference is within the predetermined range when the current value of the current is a predetermined current value equal to or less than the rated current of the fuse.

4. The current control device according to claim 3, wherein: The value of the first voltage is set so that, when the current value of the current is the predetermined current value, the ratio of the absolute value of the change in the resistance value to the absolute value of the change in the potential difference is a predetermined value.

5. The current control device according to claim 2, wherein: The voltage control unit includes a resistor electrically connected between the input terminal and the variable resistance element.

6. The current control device according to claim 2, wherein: The voltage control unit includes a current monitoring unit that detects the current, and a first voltage control unit that controls the first voltage based on a detection result of the current monitoring unit.

7. The current control device according to claim 6, wherein: The first voltage control unit includes an amplifier that amplifies a difference between a voltage proportional to a detection result of the current by the current monitoring unit and a reference voltage.

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