Power supply control device, fusing method, and computer program

Abstract

In the power supply control device (10), the drive circuits (D1, D2) individually switch the FETs (31, 32) to be on or off, thereby controlling the power supply to the loads (E1, E2). The microcomputer (4) instructs the switching of the FET (31) to be off in a state where the connection object of the fuse element (F1) is the FET (31). Then, the microcomputer (4) determines whether or not current is flowing through the FET (31). The microcomputer (4) switches the connection object of the fuse element (F1) to the FETs (31, 32) and instructs the switching of the FET (32) to be on in a case where it is determined that current is flowing through the FET (31).

Description

Technical Field

[0001] This disclosure relates to power supply control devices, fuse methods, and computer programs.

[0002] This application claims priority based on Japanese Application No. 2020-085297, filed on May 14, 2020, and invokes all the contents of that Japanese application. Background Technology

[0003] Patent Document 1 includes a power supply control device for a vehicle that controls the supply of power from a power source to a load. In this power supply control device, a FET (Field Effect Transistor) that functions as a switch is arranged in the current path flowing from the power source to the load. The power supply to the load is controlled by switching the FET on or off.

[0004] Prior art literature

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2001-95140 Summary of the Invention

[0007] Summary of the invention

[0008] One aspect of the power supply control device disclosed herein controls power supply by switching a first FET and a second FET, respectively connected to a first load and a second load, to be on or off. The power supply control device includes: a fuse element that melts when a current exceeding a predetermined current flows; a switching unit that switches the connection object of one downstream end of the fuse element; and a processing unit that performs processing. The processing unit, when the connection object of the fuse element is the first FET, instructs the first FET to switch to off. After instructing the first FET to switch to off, the processing unit determines whether current flows through the first FET. If it determines that current flows through the first FET, the processing unit instructs the switching unit to switch the connection object of the fuse element to both the first FET and the second FET. The processing unit instructs the second FET to switch to on.

[0009] In one embodiment of the fuse-breaking method disclosed herein, a computer performs the following steps: when the connection object at one end of the fuse element is a first FET connected to a first load, instructing the first FET to switch to open, and the fuse element melts when a current exceeding a predetermined current flows; after instructing the switch of the first FET to open, determining whether current flows through the first FET; if it is determined that current flows through the first FET, instructing a switching unit to switch the connection object of the fuse element to the first FET and a second FET connected to a second load, the switching unit switching the connection object at one end of the fuse element; and instructing the second FET to switch to close.

[0010] One aspect of the computer program disclosed herein is used to cause a computer to perform the following steps: in a state where the connection object at one end of the downstream side of a fuse element is a first FET connected to a first load, instructing the first FET to switch to open, the fuse element melting when a current exceeding a predetermined current flows; after instructing the switch to open of the first FET, determining whether current flows through the first FET; if it is determined that current flows through the first FET, instructing a switching unit to switch the connection object of the fuse element to the first FET and a second FET connected to a second load, the switching unit switching the connection object at one end of the downstream side of the fuse element; and instructing the second FET to switch to close.

[0011] It should be noted that this disclosure can be implemented not only as a power supply control device with such a characteristic processing unit, but also as a fuse-breaking method that sets the above-mentioned characteristic processing as a step, or as a computer program for causing a computer to execute the above-mentioned steps. Furthermore, this disclosure can be implemented as a semiconductor integrated circuit that implements part or all of the power supply control device, or as a power supply system that includes the power supply control device. Attached Figure Description

[0012] Figure 1 This is a block diagram showing the main structural components of the power supply system in Implementation 1.

[0013] Figure 2 It is a circuit diagram for connecting circuits.

[0014] Figure 3 It is a block diagram showing the main structure of a microcomputer.

[0015] Figure 4 It is a flowchart showing the sequence of power supply control processes for the load.

[0016] Figure 5This is a flowchart showing the sequence of the fusing process for a fusible element.

[0017] Figure 6 This is a block diagram showing the main structural components of the power supply system in Embodiment 2.

[0018] Figure 7 It is a block diagram showing the main structure of a microcomputer.

[0019] Figure 8 This is a flowchart showing the sequence of the fusing process for a fusible element. Detailed Implementation

[0020] [The problem this disclosure aims to solve]

[0021] As a conventional power supply control device, there exists a device in which a fusible element, such as a fuse, is placed upstream of the FET in the current path from the power source through the FET to the load. In conventional power supply control devices, if the current flowing through the fuse and the FET exceeds a predetermined current, the fuse melts, and the current flow stops. This prevents overcurrent from flowing through the FET.

[0022] In conventional power supply control devices, it is assumed that even though the FET is switched to off, a turn-on fault can still occur, causing current to flow through the FET. The current flowing through the FET during a turn-on fault is less than the current flowing through the FET when it is on. Therefore, in the event of a turn-on fault in the FET, the fuse does not blow. As a result, there is a problem where current continues to flow through the FET despite the indication of a switch to off.

[0023] When a FET with a switching failure has a high resistance, it generates a lot of heat, and its temperature may rise to an abnormal level. Conversely, when a FET with a switching failure has a sufficiently low resistance, the current flowing through it is large, and the load may continue to operate.

[0024] Therefore, the objective is to provide a power supply control device, a fusing method, and a computer program for fusing a fusible element in the event of a turn-on failure in a FET.

[0025] [The Effects of This Disclosure]

[0026] According to this disclosure, a fusible element is blown in the event of a turn-on failure in a FET.

[0027] [Description of embodiments of this disclosure]

[0028] First, embodiments of this disclosure will be listed for explanation. At least some of the embodiments described below may be combined arbitrarily.

[0029] (1) One aspect of the power supply control device disclosed herein controls power supply by switching a first FET and a second FET, which are respectively connected to a first load and a second load, to be on or off, respectively. The power supply control device includes: a fuse element that melts when a current of more than a predetermined current flows; a switching unit that switches the connection object of one downstream end of the fuse element; and a processing unit that performs processing. When the connection object of the fuse element is the first FET, the processing unit instructs the first FET to switch to off. After instructing the first FET to switch to off, the processing unit determines whether current flows through the first FET. When the processing unit determines that current flows through the first FET, it instructs the switching unit to switch the connection object of the fuse element to both the first FET and the second FET. The processing unit instructs the second FET to switch to on.

[0030] (2) One aspect of the power supply control device of the present disclosure includes a second fuse element that melts when a current of more than a second predetermined current is flowing. The switching part switches the connection objects of one downstream end of the fuse element and the second fuse element respectively. The processing unit instructs the first FET to switch to disconnection when the connection objects of the fuse element and the second fuse element are the first FET and the second FET respectively.

[0031] (3) In one embodiment of the power supply control device disclosed herein, the processing unit instructs the switching unit to switch the connection object of the fuse element to the first FET and the second FET, and then determines whether the fuse element is blown. If the processing unit determines that the fuse element is blown, it instructs the switching unit to switch the connection object of the second fuse element to the second FET.

[0032] (4) In one embodiment of the power supply control device of the present disclosure, in a first current path of the current flowing through the first FET, the first load is disposed downstream of the first FET, and in a second current path of the current flowing through the second FET, the second load is disposed downstream of the second FET. The processing unit instructs the switching unit to switch the connection object of the fuse element to the first FET and the second FET. Then, based on the voltage at one end of the downstream side of the first FET or the second FET, it is determined whether the fuse element is blown.

[0033] (5) In one aspect of the power supply control device of the present disclosure, in the current path of the current flowing through the first FET, the first load is disposed on the downstream side of the first FET, and after the processing unit instructs the switching of the first FET to be turned off, it determines whether the current flows through the first FET based on the voltage at one end of the downstream side of the first FET.

[0034] (6) In one embodiment of the power supply control device disclosed herein, the number of the second FETs is two or more, and when the processing unit determines that current flows through the first FET, it instructs the switching unit to switch the connection object of the fuse element to the disconnected FET among the first FET and the plurality of second FETs, and the processing unit instructs the disconnected FET connected to the fuse element to switch to the on.

[0035] (7) In one embodiment of the fuse-breaking method disclosed herein, the computer performs the following steps: when the connection object at one end of the fuse element is a first FET connected to a first load, the computer instructs the first FET to switch to open, and the fuse element melts when a current of more than a specified current flows; after instructing the first FET to switch to open, the computer determines whether current flows through the first FET; if it is determined that current flows through the first FET, the computer instructs the switching unit to switch the connection object of the fuse element to the first FET and a second FET connected to a second load, and the switching unit switches the connection object at one end of the fuse element; and instructs the second FET to switch to close.

[0036] (8) A computer program of one aspect of the present disclosure is used to cause a computer to perform the following steps: in a state where the connection object at one end of the downstream side of the fuse element is a first FET connected to a first load, instructing the first FET to switch to open, the fuse element melting when a current flowing above a predetermined current flows; after instructing the switch to open of the first FET, determining whether current flows through the first FET; if it is determined that current flows through the first FET, instructing a switching unit to switch the connection object of the fuse element to the first FET and a second FET connected to a second load, the switching unit switching the connection object at one end of the downstream side of the fuse element; and instructing the second FET to switch to close.

[0037] In the aforementioned power supply control device, fusing method, and computer program, when the fuse element is connected to a first FET, current flows in sequence through the fuse element and the first FET. If current flows through the first FET even though a switch to disconnect is indicated, the fuse element connects the first FET and the second FET, and the second FET is switched on. As a result, the current flowing through the fuse element rises to a level exceeding a predetermined current, causing the fuse element to blow.

[0038] In the power supply control device of the above embodiment, current typically flows in the order of fuse, first FET, and first load, and also in the order of second fuse, second FET, and second load. In the event of a switching failure in the first FET, the second FET is connected to the fuse.

[0039] In one embodiment of the power supply control device described above, when the fuse element is connected to both the first FET and the second FET, after the fuse element blows, the connection of the second fuse element is changed back to the second FET. Thus, power can be supplied to the second load again via the second fuse element and the second FET.

[0040] In one embodiment of the power supply control device described above, for example, one downstream end of the first load and the second load is grounded. In this case, when the fuse blows, current does not flow through the first FET and the first load, so the downstream end of the first FET is substantially 0V. Similarly, when the fuse does not blow, current flows through the first FET and the first load, resulting in a voltage drop in the first load. Therefore, the voltage at the downstream end of the first FET exceeds 0V.

[0041] Similarly, when one end of the downstream side of the first load and the second load is grounded, when the fuse blows, current does not flow through the second FET and the second load; therefore, the downstream end of the second FET is essentially 0V. In the same case, when the fuse does not blow, current flows through the second FET and the second load, causing a voltage drop in the second load. Therefore, the voltage at the downstream end of the second FET exceeds 0V. Thus, based on the voltage at the downstream end of either the first FET or the second FET, it is possible to determine whether the fuse has blown.

[0042] In one embodiment of the power supply control device described above, for example, one downstream end of the first load and the second load is grounded. In this case, when current does not flow through the first FET, current does not flow through the first load, therefore the voltage at one downstream end of the first FET is substantially 0V. Similarly, when current flows through the first FET, current flows through the first load, resulting in a voltage drop in the first load. Therefore, the voltage at one downstream end of the first FET exceeds 0V. Therefore, based on the voltage at one downstream end of the first FET, it is possible to determine whether current flows through the first FET.

[0043] In the power supply control device described above, when the fuse blows, the disconnecting FET among the multiple second FETs is connected to the fuse, switching the disconnecting FET to on. Therefore, as long as not all the second FETs are disconnected, the power supply to the operating second load will not be interrupted.

[0044] [Details of the embodiments of this disclosure]

[0045] Hereinafter, specific examples of the power supply control device according to embodiments of the present disclosure will be described with reference to the accompanying drawings. It should be noted that the present invention is not limited to these examples, but is disclosed in the claims and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0046] (Implementation Method 1)

[0047] <Structure of Power Supply System>

[0048] Figure 1 This is a block diagram showing the main structure of the power system 1 in Embodiment 1. The power system 1 is mounted in a vehicle and includes a power supply control device 10, a DC power supply 11, and two loads E1 and E2. The DC power supply 11 is, for example, a battery. The power supply control device 10 is connected to the positive terminal of the DC power supply 11 and one end of the loads E1 and E2. The negative terminal of the DC power supply 11 and the other end of the loads E1 and E2 are grounded.

[0049] Hereinafter, k represents any natural number less than or equal to 2. The natural number k can also be either 1 or 2.

[0050] Load Ek is an electrical device. Load Ek operates when power is supplied to it. Load Ek stops operating when power supply to it is stopped. Load Ek is preferably an electrical device such as a headlight, interior light, or audio equipment that will not obstruct the driving of the vehicle.

[0051] The power supply control device 10 receives an operating signal indicating that one of the loads E1 and E2 is operating, and a stop signal indicating that one of the loads E1 and E2 is stopping operation. When the operating signal indicating load Ek is received, the power supply control device 10 electrically connects the DC power supply 11 and the load Ek. Thus, the DC power supply 11 supplies power to the load Ek, and the load Ek operates. When the stop signal indicating load Ek is received, the power supply control device 10 disconnects the electrical connection between the DC power supply 11 and the load Ek. Thus, the power supply to the load Ek stops, and the load Ek stops operating.

[0052] As described above, the power supply control device 10 controls the power supply to loads E1 and E2.

[0053] <Structure of Power Supply Control Device 10>

[0054] The power supply control device 10 includes a connection circuit 2, two N-channel FETs 31 and 32, a microcomputer (hereinafter referred to as a microcomputer) 4, two voltage detection units B1 and B2, two drive circuits D1 and D2, and two fuse elements F1 and F2. They can also be mounted on a common substrate.

[0055] The FET3k functions as a semiconductor switch. As mentioned earlier, k is any natural number less than 2. With the FET3k in the ON state, the resistance between the drain and source is sufficiently small, allowing current to flow through both the drain and source. With the FET3k in the OFF state, the resistance between the drain and source is sufficiently large, preventing current from flowing through either the drain or source.

[0056] One end of the fuse Fk is connected to the positive terminal of the DC power supply 11. The other end of the fuse Fk is connected to the connection circuit 2. The connection circuit 2 is connected to the drain of FET 3k. The source of FET 3k is connected to one end of the load Ek. The gate of FET 3k is connected to the drive circuit Dk. The source of FET 3k is also connected to the voltage detection unit Bk. The connection circuit 2, the two voltage detection units B1 and B2, and the two drive circuits D1 and D2 are respectively connected to the microcomputer 4.

[0057] Connection circuit 2 connects the fuse element Fk to at least one of the two FETs 31 and 32. Typically, connection circuit 2 connects fuse elements F1 and F2 to FETs 31 and 32 respectively. The connection of fuse element Fk is switched by microcomputer 4. Switching the connection of fuse element Fk is equivalent to switching the connection of FET 3k.

[0058] Current flows from the positive terminal of DC power supply 11 through fuse element Fk. When a current exceeding the reference current flows through fuse element Fk, fuse element Fk is melted. The two reference currents corresponding to fuse elements F1 and F2 can be the same or different. Fuse element Fk is a fuse or fuse wire, etc.

[0059] In FET3k, FET3k is turned on when the gate voltage (which is the source potential, with the reference potential) is above a certain turn-on voltage. FET3k is turned off when the gate voltage (which is the source potential, with the reference potential) is below a certain turn-off voltage. The turn-on voltage exceeds the turn-off voltage. The turn-off voltage is a positive voltage.

[0060] Microcomputer 4 outputs a high-level voltage or a low-level voltage to the drive circuit Dk. When microcomputer 4 switches the voltage output to drive circuit Dk from a low-level voltage to a high-level voltage, drive circuit Dk causes the gate voltage of FET3k, whose reference potential is ground, to rise. Therefore, in FET3k, the gate voltage, where the reference potential is the source potential, becomes a voltage above the turn-on voltage, and FET3k switches to turn-on.

[0061] When FET3k is switched on, DC power supply 11 and load Ek are electrically connected, and power is supplied from DC power supply 11 to load Ek via FET3k. At this time, current flows in the order of FET3k and load Ek. Therefore, in the current path flowing through FET3k, load Ek is positioned downstream of FET3k. In FET3k, current flows in the order of drain and source; therefore, the drain and source of FET3k are respectively one end on the upstream side and the other on the downstream side.

[0062] When the microcomputer 4 switches the voltage output to the drive circuit Dk from a high level to a low level, the drive circuit Dk causes the gate voltage of FET3k, whose reference potential is ground, to drop. As a result, the gate voltage of FET3k, whose reference potential is the source potential, becomes lower than the off-state voltage, and FET3k switches off. When FET3k is off, the electrical connection between the DC power supply 11 and the load Ek is broken, the current flow through FET3k stops, and the power supply to the load Ek via FET3k stops.

[0063] As described above, drive circuits D1 and D2 switch FETs 31 and 32 to be on or off according to the voltage input from microcomputer 4. This controls the power supply to loads E1 and E2, respectively.

[0064] Hereinafter, the voltage at the source of FET3k, with a reference potential of ground, will be recorded as the source voltage. The voltage detection unit Bk detects the source voltage of FET3k and outputs analog voltage information representing the detected source voltage to the microcomputer 4. The analog voltage information is, for example, an analog value representing the source voltage. The voltage representing the source voltage is, for example, a voltage obtained by dividing the source voltage using two resistors (not shown).

[0065] The microprocessor 4 receives both a working signal and a stop signal. When a working signal indicating the load Ek is input, the microprocessor 4 switches the voltage output to the drive circuit Dk from a low level to a high level. This causes the drive circuit Dk to turn on FET 3k, supplying power to the load Ek. When a stop signal indicating the load Ek is input, the microprocessor 4 switches the voltage output to the drive circuit Dk from a high level to a low level. This causes the drive circuit Dk to turn off FET 3k, stopping the power supply to the load Ek.

[0066] As mentioned earlier, fuses F1 and F2 are typically connected to FETs 31 and 32, respectively. Therefore, normally, when FET 3k is on, current flows from the positive terminal of DC power supply 11 in the order of fuse Fk, FET 3k, load Ek, and the negative terminal of DC power supply 11.

[0067] When the fuse element Fk is connected to FET3k, and the voltage output to the drive circuit Dk is switched from a high level to a low level, the microcomputer 4 determines whether a turn-on fault has occurred in FET3k based on the source voltage represented by the voltage information input from the voltage detection unit Bk. A turn-on fault is a fault in which current flows through FET3k even though the voltage output to the drive circuit Dk is a low level.

[0068] When the microcomputer 4 determines that a connection fault has occurred in FET3k, it switches the connection of the fuse element Fk from FET3k to FETs 31 and 32. Then, the microcomputer 4 instructs a different drive circuit than drive circuit Dk to switch the FETs different from FET3k to on. As a result, the current flowing to the fuse element Fk becomes a current above the reference current, and the fuse element Fk is melted.

[0069] The microcomputer 4 determines whether the fuse Fk has blown based on the source voltage represented by the voltage information input from the voltage detection unit B1 or the voltage detection unit B2. If the microcomputer 4 determines that the fuse Fk has blown, it instructs the drive circuit to return the state of the FET that is different from FET 3k to its original state. In addition, the microcomputer 4 returns the connection object of the FET that is different from FET 3k to the original fuse element.

[0070] <Structure of Connection Circuit 2>

[0071] Figure 2 This is the circuit diagram for connection circuit 2. Connection circuit 2 includes relays 21 and 22, resistors R1 and R2, and transistors T1 and T2. Relay 21 has a COM terminal 21a, an NC terminal 21b, a NO terminal 21c, a rod-shaped conductor 21d, and a coil 21e. Relay 22 has a COM terminal 22a, an NC terminal 22b, a NO terminal 22c, a rod-shaped conductor 22d, and a coil 22e. Regarding relay 2k, the end of conductor 2kd is connected to COM terminal 2ka. Conductor 2kd can rotate around COM terminal 2ka as a base point. As mentioned before, k is any natural number less than 2.

[0072] Transistor Tk is an NPN bipolar transistor. Transistor Tk functions as a switch. When transistor Tk is in the ON state, the resistance between its collector and emitter is sufficiently small, allowing current to flow through both electrodes. When transistor Tk is in the OFF state, the resistance between its collector and emitter is sufficiently large, preventing current from flowing through either electrode.

[0073] One downstream end of fuse F1 is connected to the NC terminal 21b of relay 21 and the NO terminal 22c of relay 22. One downstream end of fuse F2 is connected to the NO terminal 21c of relay 21 and the NC terminal 22b of relay 22. The COM terminal 2ka of relay 2k is connected to FET 3k. Regarding relay 2k, the NC terminal 2kb is also connected to one end of coil 2ke. The other end of coil 2ke is connected to one end of resistor Rk. The other end of resistor Rk is connected to the collector of transistor Tk. The emitter of transistor Tk is grounded. The base of transistor Tk is connected to microcomputer 4.

[0074] Regarding transistor Tk, transistor Tk is turned on when the base voltage (with the emitter potential as the reference potential) is above a certain voltage. Regarding transistor Tk, transistor Tk is turned off when the base voltage (with the emitter potential as the reference potential) is below a certain voltage. This certain voltage is a positive voltage.

[0075] Hereinafter, the voltage at the base of transistor Tk, whose reference potential is ground, will be recorded as the base voltage. Microcomputer 4 switches transistor Tk to be on or off by adjusting its base voltage. When transistor Tk is switched to be on, microcomputer 4 causes the base voltage of transistor Tk to rise. Thus, in transistor Tk, the voltage at the base, whose reference potential is the emitter potential, becomes a voltage above a certain value, and transistor Tk switches to be on.

[0076] When microcomputer 4 switches transistor Tk to off, it causes the base voltage of transistor Tk to drop. As a result, in transistor Tk, the base voltage, which is the reference potential of the emitter, becomes a voltage lower than a certain value, and transistor Tk switches to off.

[0077] When transistor Tk is turned on, current flows from the positive terminal of DC power supply 11 in the following order: fuse Fk, coil 2ke, resistor Rk, transistor Tk, and finally the negative terminal of DC power supply 11. When current flows into coil 2ke, coil 2ke functions as a magnet.

[0078] The conductor 2kd of relay 2k is magnetic. A force is applied to conductor 2kd toward the NC terminal 2kb via an elastic body (not shown), such as a spring. Therefore, when no current flows through coil 2ke, coil 2ke does not function as a magnet, and thus conductor 2kd contacts NC terminal 2kb, with COM terminal 2ka connected to NC terminal 2kb. At this time, FET 3k is connected to the fuse element Fk.

[0079] When current flows through coil 2ke, coil 2ke pulls conductor 2kd closer to the NO terminal 2kc, bringing conductor 2kd into contact with the NO terminal 2kc. COM terminal 2ka is then connected to the NO terminal 2kc. During the current flow through coil 2ke, COM terminal 2ka is connected to the NO terminal 2kc. At this time, FET 3k is connected to a different fuse element than the fuse element Fk.

[0080] Microcomputer 4 switches the connection of fuse element Fk by turning two transistors T1 and T2 on or off. Normally, transistors T1 and T2 are off. In this case, fuse elements F1 and F2 are connected to FETs 31 and 32, respectively. When transistors T1 and T2 are on and off respectively, fuse element F1 is connected to FETs 31 and 32, and one downstream end of fuse element F2 is open. When transistors T1 and T2 are on and off respectively, fuse element F2 is connected to FETs 31 and 32, and one downstream end of fuse element F1 is open.

[0081] When transistors T1 and T2 are off, microprocessor 4 determines whether a turn-on fault has occurred in FET 3k. If microprocessor 4 determines that a turn-on fault has occurred in FET 31, it switches transistor T2 to on, thus switching the connection of fuse F1 from FET 31 to both FET 31 and FET 32. As a result, the current flowing through fuse F1 becomes a current above the reference current, and fuse F1 is blown. If microprocessor 4 determines that a turn-on fault has occurred in FET 32, it switches transistor T1 to on, thus switching the connection of fuse F2 from FET 32 to both FET 31 and FET 32. As a result, the current flowing through fuse F2 becomes a current above the reference current, and fuse F2 is blown.

[0082] <Structure of Microcomputer 4>

[0083] Figure 3 This is a block diagram showing the main structure of the microcomputer 4. The microcomputer 4 has a switching unit 40, an input unit 41, a storage unit 42, a control unit 43, two output units G1 and G2, and two A / D conversion units M1 and M2. They are connected to the internal bus 44. The switching unit 40 is also connected to the bases of transistors T1 and T2 in the connection circuit 2. The output unit Gk is also connected to the drive circuit Dk. As mentioned earlier, k is any natural number less than 2. The A / D conversion unit Mk is also connected to the voltage detection unit Bk.

[0084] The switching unit 40 switches transistor Tk to on or off by adjusting the base voltage of transistor Tk, as described above. The switching unit 40 switches the connection object of one end of the downstream side of the fuse element Fk by switching the two transistors T1 and T2 to on or off respectively.

[0085] The control unit 43 instructs the switching unit 40 to switch the connection of the fuse element Fk to FETs 31 and 32. Furthermore, the control unit 43 instructs the switching unit 40 to switch the connection of the fuse element Fk to FET 3k. Following the instructions of the control unit 43, the switching unit 40 switches the two transistors T1 and T2 to either be on or off.

[0086] It should be noted that as long as transistors T1 and T2 function as switches, there is no problem. Therefore, transistors T1 and T2 are not limited to NPN bipolar transistors; for example, they can also be N-channel FETs.

[0087] The output unit Gk outputs a low-level voltage or a high-level voltage to the drive circuit Dk. The control unit 43 instructs the output unit Gk to switch FET3k on or off. When instructed to switch FET3k on, the output unit Gk switches the voltage output to the drive circuit Dk to a high-level voltage. Thus, FET3k is switched on. When instructed to switch FET3k off, the output unit Gk switches the voltage output to the drive circuit Dk to a low-level voltage. Thus, FET3k is switched off.

[0088] Analog voltage information is input from the voltage detection unit Bk to the A / D conversion unit Mk. Upon receiving the analog voltage information, the A / D conversion unit Mk converts the input analog voltage information into digital voltage information. The control unit 43 obtains the digital voltage information converted by the A / D conversion unit Mk. The source voltage of FET3k represented by the voltage information obtained by the control unit 43 is substantially consistent with the source voltage at the time of acquisition.

[0089] The input unit 41 receives a working signal and a stop signal. When a working signal or a stop signal is received, the input unit 41 notifies the control unit 43 of the received signal.

[0090] Storage unit 42 is a non-volatile memory. Computer program P is stored in storage unit 42. Control unit 43 has a processing element, such as a CPU (Central Processing Unit), which functions as a processing unit. The processing element of control unit 43 executes two power supply control processes, such as controlling the power supply to loads E1 and E2 respectively, in parallel by executing computer program P. In the power supply control process for load Ek, the fusing process of fuse element Fk is executed. In the fusing process of fuse element Fk, control unit 43 determines whether a connection fault has occurred in FET 3k. If control unit 43 determines that a connection fault has occurred in FET 3k, it blows fuse element Fk.

[0091] It should be noted that the computer program P can also be stored on the storage medium A in a manner readable by the processing element of the control unit 43. In this case, the computer program P read from the storage medium A by a reading device (not shown) is written to the storage unit 42. The storage medium A is an optical disc, floppy disk, magnetic disk, magneto-optical disk, or semiconductor memory, etc. The optical disc is a CD (Compact Disc)-ROM (Read Only Memory), DVD (Digital Versatile Disc)-ROM, or BD (Blu-ray Disc), etc. The magnetic disk is, for example, a hard disk. Furthermore, the computer program P can also be downloaded from a device (not shown) connected to a communication network (not shown), and the downloaded computer program P can be written to the storage unit 42.

[0092] The number of processing elements in the control unit 43 is not limited to one; it can be two or more. In this case, multiple processing elements may also cooperate to execute two power supply control processes, etc., in accordance with a computer program P.

[0093] <Power supply control processing for load Ei>

[0094] Figure 4 This is a flowchart representing the sequence of power supply control processing for load Ei. Here, i is any natural number less than 2. Therefore, the natural number i can also be either 1 or 2. j represents a natural number less than 2 that is different from the natural number i. When the natural number i is 1, the natural number j is 2. When the natural number i is 2, the natural number j is 1.

[0095] The control unit 43 performs power supply control processing for the load Ei while the fuse elements F1 and F2 are connected to FETs 31 and 32, respectively. In the power supply control processing of the load Ei, the control unit 43 first determines whether an operating signal representing the load Ei has been input to the input unit 41 (step S1).

[0096] If the control unit 43 determines that no working signal indicating load Ei has been input (S1: No), it determines whether a stop signal indicating load Ei has been input to the input unit 41 (step S2). If the control unit 43 determines that no stop signal indicating load Ei has been input (S2: No), it executes step S1 again and waits until a working signal or a stop signal indicating load Ei is input to the input unit 41.

[0097] When the control unit 43 determines that an operating signal representing the load Ei has been input (S1: Yes), it instructs the output unit Gi to switch FET3i to turn on (step S3). As a result, the output unit Gi switches the voltage output to the drive circuit Di from a low level voltage to a high level voltage, and the drive circuit Di switches FET3i to turn on.

[0098] When the control unit 43 determines that a stop signal representing the load Ei has been input (S2: Yes), it instructs the output unit Gi to switch FET3i to be off (step S4). If step S4 is performed while the power supply control device 10 is functioning normally, the output unit Gi switches the voltage output to the drive circuit Di from a high level to a low level, and the drive circuit Di switches FET3i to be off. After performing step S4, the control unit 43 performs the fuse-breaking process for the fuse element Fi (step S5).

[0099] After executing one of steps S3 and S5, the control unit 43 terminates the power supply control process for load Ei. After terminating the power supply control process for load Ei, the control unit 43 executes the power supply control process for load Ei again, waiting until a working signal or a stop signal indicating load Ei is input.

[0100] <Fusing process of fuse element Fi>

[0101] Figure 5 This is a flowchart showing the sequence of the fusing process for fuse element Fi. The control unit 43 performs the fusing process for fuse element Fi when fuse elements Fi and Fj are connected to FETs 3i and 3j respectively and are instructed to switch FET 3i to open. As mentioned earlier, when the natural number i is 1, the natural number j is 2. When the natural number i is 2, the natural number j is 1.

[0102] FET3i functions as the first FET. FET3j functions as the second FET. Load Ei functions as the first load. Load Ej functions as the second load. Fuse Fj functions as the second fuse. The reference current of fuse Fi is equivalent to the specified current. The reference current of fuse Fj is equivalent to the second specified current.

[0103] In the fuse-breaking process of the fuse element Fi, the control unit 43 first obtains voltage information from the A / D conversion unit Mi (step S11). The voltage information obtained in step S11 represents the source voltage of FET3i. Next, based on the source voltage of FET3i represented by the voltage information obtained in step S11, the control unit 43 determines whether current flows through FET3i (step S12).

[0104] When current does not flow through FET3i, it does not flow through the load Ei, therefore the source voltage of FET3i is 0V. Here, 0V is not strictly 0V; as long as it is substantially 0V, there is no problem. When current flows through FET3i, it flows through the load Ei, causing a voltage drop in the load Ei. Therefore, the source voltage of FET3i exceeds 0V. Therefore, the control unit 43 can determine whether current flows through FET3i based on the source voltage of FET3i.

[0105] In step S12, if the source voltage indicated by the voltage information obtained in step S11 is substantially 0V, the control unit 43 determines that current is not flowing through FET3i. If the source voltage indicated by the voltage information obtained in step S11 exceeds 0V, the control unit 43 determines that current is flowing through FET3i. At the time point when step S11 is executed, the control unit 43 instructs the switching of FET3i to off. Therefore, at the time point when step S11 is executed, current flowing through FET3i indicates that a turn-on fault has occurred in FET3i.

[0106] When the control unit 43 determines that current is flowing through FET3i (S12: Yes), it instructs the switching unit 40 to switch the connection of the fuse element Fi to FET3i and FET3j (step S13). In step S13, the switching unit 40 switches the transistor Tj in the connection circuit 2 to be turned on (see reference). Figure 2 Therefore, the connection objects of the fuse element Fi are switched to FET3i and 3j. As mentioned before, when the natural number i is 1, the natural number j is 2. When the natural number i is 2, the natural number j is 1.

[0107] Step S13 is executed regardless of the state of FET3j. When step S13 is executed with FET3j on, the current flows in the order of fuse element Fi and FET3i, and then in the order of fuse element Fi and FET3j. Therefore, the current flowing through fuse element Fi becomes a current greater than or equal to a reference current. The reference current of fuse element Fi exceeds the current flowing through FET3i when FET3i is on, and is less than or equal to the total current flowing through FET3i and FET3j when both FET3i and FET3j are on.

[0108] After executing step S13, control unit 43 determines whether FET3j is off (step S14). FET3j not being off means FET3j is on. If control unit 43 determines that FET3j is off (S14: Yes), it instructs output unit Gj to switch FET3j to be on (step S15).

[0109] Therefore, the output unit Gj switches the voltage output to the drive circuit Dj from a low level to a high level, and the drive circuit Dj switches FET3j to the on position. As a result, current flows in the order of fuse Fi and FET3i, and then in the order of fuse Fi and FET3j, with the current flowing through fuse Fi exceeding the reference current. Load Ej operates due to FET3j being switched on. This notifies the vehicle occupants of the occurrence of a connection failure.

[0110] If the control unit 43 determines that FET3j is not disconnected (S14: No), or after executing step S15, it obtains voltage information from the A / D conversion unit Mi (step S16). Based on the source voltage of FET3i represented by the voltage information obtained in step S16, the control unit 43 determines whether the fuse element Fi has been blown (step S17).

[0111] When the fuse Fi is blown, current does not flow through FET3i and the load Ei, therefore the source voltage of FET3i is 0V. Here, 0V is not strictly 0V; as long as it is practically achievable, it is acceptable. When the fuse Fi is not blown, current flows through FET3i and the load Ei, causing a voltage drop in the load Ei. Therefore, the source voltage of FET3i exceeds 0V.

[0112] Therefore, the control unit 43 can determine whether the fuse element Fi has blown based on the source voltage of FET3i. Specifically, in step S17, if the source voltage of FET3i, as indicated by the voltage information obtained in step S16, is substantially 0V, the control unit 43 determines that the fuse element Fi has blown. If the source voltage of FET3i, as indicated by the voltage information obtained in step S16, exceeds 0V, the control unit 43 determines that the fuse element Fi has not blown.

[0113] It should be noted that in step S17, the connection objects of the fuse element Fi are FETs 3i and 3j. Therefore, when the fuse element Fi blows, current will not flow through FET 3j and the load Ej, so the source voltage of FET 3j is essentially 0V. When the fuse element Fi does not blow, current flows through FET 3j and the load Ej, resulting in a voltage drop in the load Ej. Therefore, the source voltage of FET 3j exceeds 0V. Therefore, the control unit 43 can determine whether the fuse element Fi has blown based on the source voltage of FET 3j.

[0114] Based on the above, the control unit 43 can also obtain voltage information from the A / D conversion unit Mj through step S16. In this case, in step S17, the control unit 43 determines whether the fuse element Fi has blown based on the source voltage of FET3j represented by the voltage information obtained in step S16. This determination method is the same as the determination method based on the source voltage of FET3i.

[0115] If the control unit 43 determines that the fuse Fi has not blown (S17: No), it executes step S16 again and waits until the fuse Fi blows. If the control unit 43 determines that the fuse Fi has blown (S17: Yes), at the time point after executing step S13, it determines whether FET3j is turned on (step S18). FET3j not being turned on means that FET3j is turned off.

[0116] If the control unit 43 determines that FET3j is not turned on (S18: No), it instructs the output unit Gj to switch FET3j to be turned off (step S19). As a result, the output unit Gj switches the voltage output to the drive circuit Dj from a high level to a low level, and the drive circuit Dj switches FET3j to be off. If the control unit 43 determines that FET3j is turned on (S18: Yes), or after executing step S19, it instructs the switching unit 40 to switch the connection target of the fuse element Fj to FET3j (step S20). The switching unit 40 switches the connection target of the fuse element Fj to FET3j by switching the transistor Tj in the connection circuit 2 to be off.

[0117] If the control unit 43 determines that the current has not flowed through FET3i (S12: No), or after executing step S20, it ends the fuse breaking process of the fuse element Fi and ends the power supply control process of the load Ei.

[0118] <Effect of Power Supply Control Device 10>

[0119] Even though the control unit 43 instructs the output unit Gi to switch FET3i to off, if current still flows through FET3i, the switching unit 40 connects FET3i and FET3j at the fuse element Fi and switches FET3j to on. As a result, the current flowing through the fuse element Fi rises above the reference current, and the fuse element Fi blows. After the fuse element Fi blows, the switching unit 40 returns the connection of the fuse element Fj to FET3j. Thus, power can be supplied to the load Ej again through the fuse element Fj and FET3j.

[0120] (Implementation Method 2)

[0121] In Embodiment 1, the power supply control device 10 has two FETs. However, the power supply control device 10 may also have three or more FETs.

[0122] Hereinafter, regarding Embodiment 2, the differences from Embodiment 1 will be explained. Except for the structure described later, the structure is the same as in Embodiment 1. Therefore, for structural parts common to Embodiment 1, the same reference numerals as in Embodiment 1 will be used, and their descriptions will be omitted.

[0123] <Structure of Power System 1>

[0124] Figure 6 This is a block diagram showing the main structure of the power system 1 in Embodiment 2. The power system 1 replaces two loads E1 and E2, and has n loads E1, E2, ..., En. Here, n is an integer of 3 or more. In Embodiment 2, the natural number k represents any natural number less than or equal to n. The natural number k can also be any one of 1, 2, ..., n.

[0125] The power supply control device 10 is connected to one end of the load Ek. The other end of the load Ek is grounded. Similar to Embodiment 1, the load Ek is an electrical device. When power is supplied to the load Ek, the load Ek operates. When the power supply to the load Ek stops, the load Ek stops operating.

[0126] In embodiment 2, the operating signal represents the load that operates among loads E1, E2, ..., En. The stop signal represents the load that stops operating among loads E1, E2, ..., En. When the power supply control device 10 receives an operating signal representing load Ek, it electrically connects the DC power supply 11 to load Ek. Thus, the DC power supply 11 supplies power to load Ek, and load Ek operates. When the power supply control device 10 receives a stop signal representing load Ek, it disconnects the electrical connection between the DC power supply 11 and load Ek. Thus, the power supply to load Ek stops, and load Ek stops operating.

[0127] As described above, the power supply control device 10 controls the power supply to the loads E1, E2, ..., En.

[0128] <Structure of Power Supply Control Device 10>

[0129] When comparing the power supply control device 10 in Embodiment 2 with that in Embodiment 1, the power supply control device 10 has different numbers of FETs, voltage detection units, and drive circuits. In Embodiment 2, the power supply control device 10 has n N-channel FETs 31, 32, ..., 3n instead of two N-channel FETs 31, 32. The power supply control device 10 has n voltage detection units B1, B2, ..., Bn instead of two voltage detection units B1, B2. The power supply control device 10 has n drive circuits D1, D2, ..., Dn instead of two drive circuits D1, D2. The power supply control device 10 has n fuses F1, F2, ..., Fn instead of two fuses F1, F2.

[0130] FET3k, voltage detection unit Bk, drive circuit Dk and fuse element Fk are connected in the same way as in embodiment 1.

[0131] Connection circuit 2 connects the fuse element Fk to at least one of the n FETs 31, 32, ..., 3n. Typically, connection circuit 2 connects fuse elements F1, F2, ..., Fn to FETs 31, 32, ..., 3n respectively. The connection of fuse element Fk is switched by microcomputer 4. Switching the connection of fuse element Fk is equivalent to switching the connection of FET 3k.

[0132] The microcomputer 4 outputs a high-level voltage or a low-level voltage to the drive circuit Dk. FET3k, fuse Fk, drive circuit Dk, and voltage detection unit Bk function in the same way as in Embodiment 1. The drive circuit Dk switches FET3k to be on or off according to the voltage input from the microcomputer 4.

[0133] Similar to Implementation 1, when the microcomputer 4 switches the voltage output to the drive circuit Dk from a high level voltage to a low level voltage when the connection object of the fuse element Fk is FET3k, it determines whether a connection fault has occurred in FET3k.

[0134] When the microprocessor 4 determines that a connection failure has occurred in FET3k, it switches the connection target of the fuse element Fk from FET3k to a disconnected FET among FET3k and (n-1) different FETs. After switching the connection target of the fuse element Fk to FET3k and the disconnected FET, the microprocessor 4 instructs the drive circuit to switch the disconnected FET to on. As a result, the current flowing to the fuse element Fk becomes a current above the reference current, and the fuse element Fk melts.

[0135] The microprocessor 4 determines whether the fuse Fk is blown based on the source voltage represented by the voltage information input from the voltage detection unit Bk. If the microprocessor 4 determines that the fuse Fk is blown, it instructs the drive circuit to switch the disconnect FET to open. In addition, the microprocessor 4 reverts the connection of the disconnect FET back to the original fuse.

[0136] <Structure of Microcomputer 4>

[0137] Figure 7 This is a block diagram showing the main structural components of the microcomputer 4. When comparing the microcomputer 4 in Embodiment 2 with that in Embodiment 1, the number of output units and A / D conversion units differs. In Embodiment 2, the microcomputer 4 has n output units G1, G2, ..., Gn, replacing the two output units G1 and G2. The microcomputer 4 also has n A / D conversion units M1, M2, ..., Mn, replacing the two A / D conversion units M1 and M2.

[0138] The switching unit 40 is connected to the connection circuit 2. The output unit Gk and the A / D conversion unit Mk are connected in the same way as in Embodiment 1.

[0139] The connection circuit 2 has multiple switches (not shown). The switching unit 40 switches the connection object of one end of the downstream side of the fuse element Fk by switching the multiple switches of the connection circuit 2 to be on or off.

[0140] The control unit 43 instructs the switching unit 40 to switch the connection object of the fuse element Fk to FET3k and to disconnect the FET. Furthermore, the control unit 43 instructs the switching unit 40 to switch the connection object of the fuse element Fk to FET3k. Following the instructions of the control unit 43, the switching unit 40 switches the multiple switches in the connection circuit 2 to either be on or off.

[0141] The output unit Gk and the A / D conversion unit Mk function in the same way as in Embodiment 1.

[0142] The processing element of the control unit 43 executes n power supply control processes in parallel by executing the computer program P, which control the power supply of each of the loads E1, E2, ..., En. In the power supply control process of load Ek, the fuse-breaking process of fuse element Fk is executed.

[0143] <Power supply control processing for load Ei>

[0144] In Embodiment 2, the natural number i represents any natural number less than or equal to n. The natural number i can also be any one of 1, 2, ..., n. As mentioned above, n is an integer greater than or equal to 3. The control unit 43 performs the power supply control processing of the load Ei in the same manner as in Embodiment 1, with the fuse elements F1, F2, ..., Fn connected to FETs 31, 32, ..., 3n respectively.

[0145] <Fusing process of fuse element Fi>

[0146] Figure 8 This is a flowchart showing the sequence of fuse element Fi's fuse-breaking process. The control unit 43 performs the fuse-breaking process of fuse element Fi when fuse elements F1, F2, ..., Fn are respectively connected to FETs 31, 32, ..., 3n and the switching of FET 3i to open is indicated.

[0147] In Embodiment 2, FET3i functions as the first FET, similar to Embodiment 1. Among the n FETs 31, 32, ..., 3n, (n-1) FETs different from FET3i function as second FETs. As mentioned earlier, n is an integer of 3 or more, therefore the number of second FETs is 2 or more. The load Ei functions as the first load, similar to Embodiment 1. Among the n loads E1, E2, ..., En, (n-1) loads different from load Ei function as second loads. Among the n fuses F1, F2, ..., Fn, (n-1) fuses different from fuse Fi function as second fuses. The reference current of fuse Fi is equivalent to a specified current, similar to Embodiment 1. The reference current of each of the (n-1) fuses different from fuse Fi is equivalent to a second specified current.

[0148] In the fuse-breaking process of the fuse element Fi, the control unit 43 first obtains voltage information from the A / D conversion unit Mi (step S31). Based on the source voltage of FET3i represented by the obtained voltage information, it determines whether current flows through FET3i in the same way as step S12 of the fuse-breaking process in Embodiment 1 (step S32). At the end of the execution of step S31, current flowing through FET3i means that a switching fault has occurred in FET3i.

[0149] When the control unit 43 determines that current is flowing through FET 3i (S32: Yes), it selects a disconnecting FET from among the (n-1) FETs different from FET 3i (step S33). In step S33, the control unit 43 may also not select all disconnecting FETs from the (n-1) FETs different from FET 3i. In step S33, it is acceptable for the control unit 43 to select at least one disconnecting FET. The following describes an example where the control unit 43 selects one disconnecting FET.

[0150] Next, the control unit 43 instructs the switching unit 40 to switch the connection of the fuse element Fi to FET 3i and the disconnect FET selected in step S33 (step S34). After executing step S34, the control unit 43 instructs the output unit to switch the disconnect FET selected in step S33 to the on state (step S35). As a result, the output unit switches the voltage output to the drive circuit to a high level voltage, and the drive circuit switches the disconnect FET to the on state. As a result, the current flowing through the fuse element Fi becomes a current greater than or equal to a reference current. The reference current of the fuse element Fi exceeds the current flowing through FET 3i when FET 3i is on, and is less than or equal to the total value of the current flowing through FET 3i and the disconnect FET when they are on.

[0151] The output unit and drive circuit described here are the output unit and drive circuit corresponding to the disconnect FET selected in step S33. For example, if the disconnect FET selected in step S33 is FET3u, the control unit 43 instructs the output unit Gu to switch FET3u to the on state in step S35. The drive circuit Du switches FET3u to the on state. Here, u is a natural number n or less that is different from the natural number i. When FET3u is switched to the on state, the load Eu operates. As a result, the occupants of the vehicle are notified of the occurrence of a connection failure.

[0152] After executing step S35, the control unit 43 obtains voltage information from the A / D conversion unit Mi (step S36). Based on the source voltage of FET3i represented by the voltage information obtained in step S36, the control unit 43 determines whether the fuse element Fi has blown, similar to step S17 of the fuse-breaking process in Embodiment 1 (step S37).

[0153] It should be noted that in step S37, the connection objects of the fuse element Fi are FET3i and the disconnect FET. Therefore, the control unit 43 can determine whether the fuse element Fi is blown based on the source voltage of the disconnect FET. Based on the above, the control unit 43 can also obtain voltage information from the A / D converter corresponding to the disconnect FET in step S36. In this case, in step S37, the control unit 43 determines whether the fuse element Fi is blown based on the source voltage of the disconnect FET represented by the voltage information obtained in step S36.

[0154] If the control unit 43 determines that the fuse Fi has not blown (S37: No), it executes step S36 again and waits until the fuse Fi blows. If the control unit 43 determines that the fuse Fi has blown (S37: Yes), it instructs the output unit to switch the disconnect FET selected in step S33 to disconnect (step S38). As a result, the output unit switches the voltage output to the drive circuit to a low level, and the drive circuit switches the disconnect FET to disconnect. The output unit and drive circuit described here correspond to the output unit and drive circuit corresponding to the disconnect FET selected in step S33.

[0155] After executing step S38, control unit 43 instructs switching unit 40 to revert the connection target of the disconnected FET selected in step S33 back to the original fuse element (step S39). If the disconnected FET selected in step S33 is FET3u, in step S39, control unit 43 instructs switching unit 40 to switch the connection target of fuse element Fu to FET3u. As mentioned above, u is a natural number less than or equal to n, which is different from the natural number i.

[0156] If the control unit 43 determines that the current has not flowed through FET3i (S32: No), or after executing step S39, it ends the fuse breaking process of the fuse element Fi and ends the power supply control process of the load Ei.

[0157] It should be noted that in step S33, when (n-1) FETs different from FET3i are turned on, one of the (n-1) FETs different from FET3i is selected. In this case, in step S34, the control unit 43 instructs the switching unit 40 to switch the connection object of the fuse element Fi to FET3i and the FET selected in step S33. The control unit 43 omits the execution of steps S35 and S38.

[0158] <Effect of Power Supply Control Device 10>

[0159] When the fuse element Fi is blown, the disconnecting FETs among the (n-1) FETs different from FET3i that are off are connected to the fuse element Fi, switching the disconnecting FETs to on. Therefore, as long as all the FETs different from FET3i are not on at the time when current is determined to flow through FET3i, the power supply to the operating load will not be interrupted.

[0160] The power supply control device 10 in Embodiment 2 also performs the same effect as the power supply control device 10 in Embodiment 1.

[0161] <Variation Example>

[0162] In embodiments 1 and 2, regarding the FET that experiences a turn-on failure, the current when instructed to switch to turn-on may be greater than the current when instructed to switch to turn-off. Therefore, in the fuse-breaking process of embodiments 1 and 2, if the control unit 43 determines that current flows through FET3i even though the output unit Gi is instructed to switch FET3i to turn on, it can also instruct the output unit Gi to switch FET3i to turn on. As a result, the fuse element Fi can be reliably blown.

[0163] In embodiments 1 and 2, the method for determining whether current flows through FET3i is not limited to a method based on the source voltage of FET3i. Control unit 43 may also determine whether current flows through FET3i based on the current flowing through the drain and source of FET3i. If the current flowing through the drain and source of FET3i is substantially 0A, control unit 43 determines that current does not flow through FET3i. If the current flowing through the drain and source of FET3i exceeds 0A, control unit 43 determines that current flows through FET3i.

[0164] In embodiments 1 and 2, the method for determining whether the fuse element Fi has blown is not limited to a method based on the source voltage of the FET connected to the fuse element Fi. The control unit 43 may also determine whether the fuse element Fi has blown based on the current flowing through the drain and source of the FET connected to the fuse element Fi. The control unit 43 determines that the fuse element Fi has blown when the current flowing through the drain and source of the FET is substantially 0A. The control unit 43 determines that the fuse element Fi has not blown when the current flowing through the drain and source of the FET exceeds 0A.

[0165] In embodiments 1 and 2, the timing of the fuse-breaking operation performed by the control unit 43 is not limited to the moment when FET3i switches to the off position during power supply control processing. For example, the fuse-breaking operation can be performed immediately after the vehicle's ignition switch is switched on or just before the ignition switch is about to switch to the off position. In embodiments 1 and 2, there is no problem as long as FET3k functions as a semiconductor switch. Therefore, a P-channel FET or bipolar transistor can be used instead of FET3k.

[0166] It should be considered that the disclosed embodiments 1 and 2 are illustrative in all respects and not restrictive. The scope of the invention is defined not by the foregoing but by the claims and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0167] Label Explanation

[0168] 1 Power System

[0169] 2. Connecting the circuit

[0170] 4. Microcomputer

[0171] 10 Power supply control device

[0172] 11 DC Power Supply

[0173] 21, 22 Relays

[0174] 21a, 22a COM terminals

[0175] 21b, 22b NC terminals

[0176] 21c, 22c NO terminals

[0177] 21d and 22d conductors

[0178] 21e and 22e coils

[0179] 31, 32, ..., 3n FETs (first FET, second FET)

[0180] 40 Switching Unit

[0181] 41 Input Section

[0182] 42 Storage Section

[0183] 43. Control Department (Processing Department)

[0184] 44 Internal Bus

[0185] A storage medium

[0186] Voltage detection sections B1, B2, ..., Bn

[0187] D1, D2, ..., Dn drive circuits

[0188] E1, E2, ..., En load

[0189] F1, F2, ..., Fn are fuse elements (second fuse elements).

[0190] Output sections of G1, G2, ..., Gn

[0191] M1, M2, ..., Mn A / D conversion units

[0192] P Computer Program

[0193] resistors R1, R2, ..., Rn

[0194] T1 and T2 transistors.

Claims

1. A power supply control device, wherein power supply is controlled by switching a first FET and a second FET, respectively connected to a first load and a second load, to be on or off, wherein, The power supply control device includes: A fusible element that melts when a current exceeding a specified current is flowing through it. The switching unit switches the connection object at one end of the downstream side of the fuse element; and Processing Department, Execute Processing When the fuse element is connected to the first FET, the processing unit instructs the first FET to switch to disconnection. After instructing the first FET to switch to off, the processing unit determines whether current flows through the first FET. When the processing unit determines that current is flowing through the first FET, it instructs the switching unit to switch the connection of the fuse element to both the first FET and the second FET. The processing unit instructs the second FET to switch to on.

2. The power supply control device according to claim 1, wherein, The power supply control device includes a second fuse element that melts when a current exceeding a second predetermined current is flowing. The switching section switches the connection objects at one downstream end of the fuse element and the second fuse element respectively. When the connection objects of the first FET and the second FET are respectively the first FET and the second FET, the processing unit instructs the first FET to switch to disconnect.

3. The power supply control device according to claim 2, wherein, The processing unit instructs the switching unit to switch the connection objects of the fuse element to the first FET and the second FET, and then determines whether the fuse element has blown. When the processing unit determines that the fuse element has blown, it instructs the switching unit to switch the connection target of the second fuse element to the second FET.

4. The power supply control device according to claim 3, wherein, In the first current path of the current flowing through the first FET, the first load is positioned downstream of the first FET. In the second current path of the current flowing through the second FET, the second load is positioned downstream of the second FET. The processing unit instructs the switching unit to switch the connection of the fuse element to the first FET and the second FET. Then, based on the voltage at one end of the downstream side of the first FET or the second FET, it determines whether the fuse element has blown.

5. The power supply control device according to any one of claims 1 to 4, wherein, In the current path of the current flowing through the first FET, the first load is positioned downstream of the first FET. After instructing the first FET to switch to off, the processing unit determines whether current flows through the first FET based on the voltage at one end of the downstream side of the first FET.

6. The power supply control device according to any one of claims 1 to 4, wherein, The number of the second FET is 2 or more. When the processing unit determines that current is flowing through the first FET, it instructs the switching unit to switch the connection target of the fuse element to the disconnected FET among the first FET and the plurality of second FETs. The processing unit instructs the switching of the disconnected FET connected to the fuse element to the on state.

7. A circuit breaker method, wherein, The computer performs the following steps: When the connection object at one end of the downstream side of the fuse element is connected to the first FET of the first load, the switching of the first FET to disconnection is indicated, and the fuse element melts when a current flowing above a specified current flows. After indicating the switching of the first FET to off, it is determined whether current flows through the first FET; When it is determined that current flows through the first FET, the switching unit is instructed to switch the connection object of the fuse element to the first FET and the second FET connected to the second load. The switching unit switches the connection object of one end of the downstream side of the fuse element. and Indicates the switching of the second FET to on.

8. A computer program for causing a computer to perform the following steps: When the connection object at one end of the downstream side of the fuse element is connected to the first FET of the first load, the switching of the first FET to disconnection is indicated, and the fuse element melts when a current flowing above a specified current flows. After indicating the switching of the first FET to off, it is determined whether current flows through the first FET; When it is determined that current flows through the first FET, the switching unit is instructed to switch the connection object of the fuse element to the first FET and the second FET connected to the second load. The switching unit switches the connection object of one end of the downstream side of the fuse element. and Indicates the switching of the second FET to on.

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