Power supply control device, power supply control method, and computer program

Abstract

To provide a power feeding control device, a power feeding control method, and a computer program that make it possible to use a compact switch as a first switch.SOLUTION: In a power feeding control device 11, a microcontroller 24 shifts the state of each of a plurality of second switches B1, B2, ..., Bn, into which a current is input from a first switch 20 into an off state, or into a flowing state, in which current flow is enabled. The microcontroller 24 adjusts the average value of current flowing per unit time for at least one second switch in accordance with one or a plurality of second switches in a state of current flow.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a power supply control device, a power supply control method, and a computer program. [Background technology]

[0002] Patent Document 1 discloses a power supply control device for a vehicle that controls power supply from a DC power source to multiple loads. In this power supply control device, a current is input from a DC power source to one end of a first switch. The current output from the other end of the first switch is divided into multiple currents. Each of the multiple currents is input to one end of multiple second switches. Each of the multiple currents output from the other ends of the multiple second switches flows through multiple loads.

[0003] When the first switch is in an on state, the control unit switches the states of the multiple second switches to an on state or an off state. This controls the power supply to each of the multiple loads. The control unit can stop the power supply to all the loads by switching the state of the first switch to an off state. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-167882 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the power supply control device described in Patent Document 1, when the states of the first switch and all the second switches are fixed to the on state, the average value of the current flowing per unit time through the first switch is the largest. This value must be tolerated by the first switch. Therefore, a large switch having a large tolerance for the average value of the current flowing per unit time is used as the first switch. The space in which the power supply control device is arranged inside a vehicle is limited. For this reason, it is preferable that the first switch of the power supply control device is a small switch.

[0006] The present disclosure has been made in consideration of the above circumstances, and an object of the present disclosure is to provide a power supply control device, a power supply control method, and a computer program that enable a small switch to be used as the first switch. [Means for solving the problem]

[0007] A power supply control device according to one embodiment of the present disclosure includes a first switch and a processing unit that executes processing, and the processing unit transitions the state of each of a plurality of second switches to which current is input from the first switch to an off state or a flow state in which current can flow, and the processing unit adjusts an average value of current flowing per unit time for at least one second switch in accordance with the one or more second switches that are in the flow state.

[0008] In a power supply control method according to one aspect of the present disclosure, a computer executes the steps of transitioning the state of each of a plurality of second switches to which current is input from a first switch to an off state or a flow state in which current is flowing, and adjusting an average value of a current flowing per unit time for at least one second switch in accordance with the one or more second switches in the flow state.

[0009] A computer program according to one embodiment of the present disclosure causes a computer to execute steps of transitioning the state of each of a plurality of second switches to which current is input from a first switch to an off state or a flow state in which current is flowing, and adjusting an average value of current flowing per unit time for at least one second switch in accordance with the one or more second switches in the flow state.

[0010] The present disclosure can be realized not only as a power supply control device having such a characteristic processing unit, but also as a power supply control method having such characteristic processing steps, or as a computer program for causing a computer to execute such steps. Furthermore, the present disclosure can be realized as a semiconductor integrated circuit that realizes part or all of the power supply control device, or as a power supply system including the power supply control device. Effect of the Invention

[0011] According to the above aspect, a small switch can be used as the first switch. [Brief description of the drawings]

[0012] [Figure 1] 1 is a block diagram showing a configuration of a main part of a power supply system according to a first embodiment. [Diagram 2] FIG. 11 is an explanatory diagram of switching of a second switch. [Diagram 3] FIG. 2 is a circuit diagram of a switch device. [Figure 4] 6 is an explanatory diagram of the relationship between the voltage values ​​across the second switch and the state. FIG. [Diagram 5] 13 is a diagram illustrating a method for detecting a failure of a second switch. [Figure 6] FIG. 2 is a block diagram showing a main configuration of a microcomputer; [Figure 7] 11 is a diagram showing the contents of a state table. [Figure 8] 11 is a diagram showing the contents of a duty table. [Figure 9] 5 is a flowchart showing a procedure of a power supply control process for a load. [Figure 10] 5 is a flowchart showing a procedure of a power supply control process for a load. [Figure 11] 11 is a flowchart showing a procedure of a switching process of the first switch. [Figure 12] FIG. 11 is a circuit diagram of a switch device according to a second embodiment. [Figure 13] 6 is a diagram illustrating the relationship between a second switch current value and a state of the second switch. FIG. [Figure 14] 13 is a diagram illustrating a method for detecting a failure of a second switch. [Figure 15] 5 is a flowchart showing a procedure of a power supply control process for a load. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] [Description of the embodiments of the present disclosure] First, the embodiments of the present disclosure will be listed and described. At least a part of the embodiments described below may be arbitrarily combined.

[0014] (1) A power supply control device according to one embodiment of the present disclosure includes a first switch and a processing unit that executes processing, wherein the processing unit transitions the state of each of a plurality of second switches to which a current is input from the first switch to an off state or a flow state in which current can flow, and the processing unit adjusts an average value of a current flowing per unit time for at least one second switch in accordance with the one or more second switches that are in the flow state.

[0015] (2) In a power supply control device according to one embodiment of the present disclosure, an average value of a current flowing per unit time through the first switch is less than a value of a current flowing through the first switch when the states of the first switch and all of the second switches are fixed to the on state.

[0016] (3) In a power supply control device according to one embodiment of the present disclosure, when the state of the second switch is fixed to an on state or when PWM control of the second switch is performed, the state of the second switch transitions to the conductive state.

[0017] (4) A power supply control device according to one embodiment of the present disclosure includes a switching circuit that switches the state of the first switch between an on state and an off state, and the switching circuit switches the state of the first switch to the off state when a value of a current flowing through the first switch becomes equal to or greater than a current threshold value.

[0018] (5) In a power supply control device according to one embodiment of the present disclosure, the processing unit instructs the second switch to be switched to an off state, and when the switching of the second switch to an off state is instructed, when a period during which a voltage value between both ends of the second switch is maintained within a predetermined range becomes equal to or longer than a predetermined period, instructs the first switch to be switched to an off state.

[0019] (6) In a power supply control device according to one embodiment of the present disclosure, the processing unit instructs the second switch to be switched to an off state, and when the switching of the second switch to the off state is instructed, when the period during which the current value flowing through the second switch is maintained within a second predetermined range becomes a value equal to or greater than a second predetermined period, the processing unit instructs the first switch to be switched to an off state.

[0020] (7) In a power supply control device according to one embodiment of the present disclosure, the processing unit instructs the second switch to be switched to an off state, and when the switching of the second switch to the off state is instructed, when a voltage value between both ends of the second switch is less than a predetermined voltage value, the processing unit instructs the first switch to be switched to an off state.

[0021] (8) In a power supply control device according to one embodiment of the present disclosure, when an instruction to switch the second switch to an off state is given, the processing unit instructs the first switch to be switched to an off state when a voltage value between both ends of a specific switch that is predetermined among the plurality of second switches is less than the predetermined voltage value.

[0022] (9) In a power supply control device according to one embodiment of the present disclosure, when an instruction is given to switch the second switch to an off state and a voltage value across both ends of the second switch different from the specific switch is less than the predetermined voltage value, the processing unit reduces an average value of a current flowing per unit time through the second switch different from the second switch whose voltage value across both ends is less than the predetermined voltage value.

[0023] (10) In a power supply control device according to one embodiment of the present disclosure, the processing unit instructs the second switch to be switched to an off state, and when the second switch is instructed to be switched to an off state and a current value flowing through the second switch exceeds a predetermined current value, the processing unit instructs the first switch to be switched to an off state.

[0024] (11) In a power supply control device according to one embodiment of the present disclosure, when an instruction to switch the second switch to an off state is given and a current value flowing through a predetermined specific switch among the plurality of second switches exceeds the predetermined current value, the processing unit instructs the first switch to be switched to an off state.

[0025] (12) In a power supply control device according to one embodiment of the present disclosure, when an instruction is given to switch the second switch to an off state and a current value flowing through a second switch other than the specific switch exceeds the predetermined current value, the processing unit reduces an average value of a current flowing per unit time through the second switch other than the second switch through which a current whose value exceeds the predetermined current value flows.

[0026] (13) In a power supply control method according to one aspect of the present disclosure, a computer executes the steps of transitioning the state of each second switch to which a current is input from the first switch to an off state or a flow state in which current is flowing, and adjusting an average value of a current flowing per unit time for at least one second switch in accordance with one or more second switches in the flow state.

[0027] (14) A computer program according to one embodiment of the present disclosure causes a computer to execute the steps of transitioning the state of each second switch to which current is input from the first switch to an off state or a flowing state in which current is flowing, and adjusting an average value of a current flowing per unit time for at least one second switch in accordance with one or more second switches in the flowing state.

[0028] In the power supply control device, the power supply control method, and the computer program according to the above aspect, the average value of the current flowing per unit time for at least one second switch is adjusted according to one or more second switches in a conducting state. Therefore, the maximum value of the average value of the current flowing per unit time through the first switch is small. As a result, a small switch with a small tolerance for the average value of the current can be used as the first switch.

[0029] In the power supply control device according to the above aspect, the states of all the second switches are not fixed to the on state, and therefore the average value of the current flowing through the first switch per unit time is less than the value of the current flowing through the first switch when the states of the first switch and all the second switches are fixed to the on state.

[0030] In the power supply control device according to the above aspect, when the first switch is in an on state, the second switch is fixed in an on state or the second switch is PWM-controlled, thereby starting the flow of current through the second switch.

[0031] In the power supply control device according to the above aspect, the switching circuit switches the state of the first switch to the off state when the value of the current flowing through the first switch rises to a value equal to or greater than the current threshold, thereby preventing the current whose value is equal to or greater than the current threshold from continuing to flow through the first switch.

[0032] In the power supply control device according to the above aspect, when the second switch is a semiconductor switch, a half-on failure may occur in the second switch. When a half-on failure occurs in the second switch, even when an instruction is given to switch the second switch to an off state, the resistance value across the second switch does not increase to a sufficiently large value. Therefore, a current flows through the second switch, and the voltage value across the second switch is maintained within a predetermined range.

[0033] When the second switch is instructed to be switched to the OFF state and the period during which the voltage across the second switch is within a predetermined range exceeds the predetermined period, the processor determines that a half-ON fault has occurred in the second switch and instructs the first switch to be switched to the OFF state, thereby switching the state of the first switch to the OFF state and stopping the flow of current through the second switch.

[0034] In the power supply control device according to the above aspect, when a half-on fault occurs in the second switch and an instruction is given to switch the second switch to an off state, the value of the current flowing through the second switch is maintained at a value within a second predetermined range. When an instruction is given to switch the second switch to an off state and the period during which the value of the current flowing through the second switch is within the second predetermined range becomes equal to or longer than the second predetermined period, the processing unit determines that a half-on fault occurs in the second switch and instructs the processing unit to switch the first switch to an off state.

[0035] In the power supply control device according to the above aspect, a short-circuit fault may occur in the second switch. When a short-circuit fault occurs in the second switch, the state of the second switch is maintained in the on state even when an instruction to switch the second switch to the off state is given. When the state of the second switch is in the on state, the voltage value across the second switch is less than a predetermined voltage value. When an instruction to switch the second switch to the off state is given and the voltage value across the second switch is less than the predetermined voltage value, it is determined that a short-circuit fault has occurred in the first switch, and an instruction to switch the first switch to the off state is given.

[0036] In the power supply control device according to the above aspect, when a short-circuit fault occurs in the specific switch, the processing unit instructs switching the first switch to the off state.

[0037] In the power supply control device according to the above aspect, when a short-circuit fault occurs in a second switch different from the specific switch, power supply via the second switch in which the short-circuit fault occurs is permitted. In order to prevent a large current from continuing to flow through the first switch, the average value of the current flowing per unit time is reduced via the second switch different from the second switch in which the short-circuit fault occurs.

[0038] In the power supply control device according to the above aspect, when a short-circuit fault occurs in the second switch, the state of the second switch is maintained in the on state even when an instruction to switch the second switch to the off state is given. When the state of the second switch is the on state and the state of the first switch is the on state, the value of the current flowing through the second switch exceeds a predetermined current value. When an instruction to switch the second switch to the off state is given and the value of the current flowing through the second switch exceeds the predetermined current value, it is determined that a short-circuit fault occurs in the second switch, and the processing unit instructs to switch the first switch to the off state.

[0039] In the power supply control device according to the above aspect, when a short-circuit fault occurs in the specific switch, the processing unit instructs switching the first switch to the off state.

[0040] In the power supply control device according to the above aspect, when a short-circuit fault occurs in a second switch different from the specific switch, power supply via the second switch in which the short-circuit fault occurs is permitted. In order to prevent a large current from continuing to flow through the first switch, the average value of the current flowing per unit time is reduced via the second switch different from the second switch in which the short-circuit fault occurs.

[0041] [Details of the embodiment of the present disclosure] Specific examples of power supply systems according to embodiments of the present disclosure will be described below with reference to the drawings. Note that the present invention is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope of the claims.

[0042] (Embodiment 1) <Power supply system configuration> FIG. 1 is a block diagram showing a configuration of a main part of a power supply system 1 in the first embodiment. The power supply system 1 is mounted on a vehicle M. The power supply system 1 includes a DC power supply 10, a power supply control device 11, n switch devices A1, A2, . . . , An, and n loads E1, E2, . . . , En. Here, n is an integer equal to or greater than 2. In the following, an arbitrary natural number equal to or less than n is represented by i. The natural number i may be any of 1, 2, . . . , n. The DC power supply 10 is, for example, a battery. The power supply control device 11 has a first switch 20. The switch device Ai has a second switch Bi. Each of the first switch 20 and the second switch Bi is an N-channel type field effect transistor (FET), and is a semiconductor switch.

[0043] The negative electrode of the DC power supply 10 is grounded. The grounding is achieved, for example, by connection to the body of the vehicle M. The body is conductive. The positive electrode of the DC power supply 10 is connected to the drain of a first switch 20 of the power supply control device 11. The source of the first switch 20 is connected to the drains of second switches B1, B2, ..., Bn. The source of the second switch Bi is connected to one end of a load Ei. The other end of the load Ei is grounded. The power supply control device 11 is connected to n switch devices A1, A2, ..., An, respectively.

[0044] The switch device Ai and the load Ei may be provided in a common ECU (Electronic Control Unit). This ECU is called an electromechanical integrated ECU. When the switch device Ai and the load Ei are provided in a common ECU, n ECUs are installed in the vehicle M. A first example of the load Ei is an electrical device related to a seat, a door, or a wiper. A second example of the load Ei is a light. The type of the load Ei may be the same as or different from the type of the other loads. An ECU in which electrical devices related to a seat are provided is disposed, for example, inside or under the driver's seat, passenger seat, or rear seat of the vehicle M.

[0045] The power supply control device 11 switches the first switch 20 to an on state or an off state. The switch device Ai switches the second switch Bi to an on state or an off state. When the first switch 20 and the second switch Bi are in an on state, the resistance between the drain and the source is sufficiently small, and a current can flow through the drain and the source. When the first switch 20 and the second switch Bi are in an off state, the resistance between the drain and the source is sufficiently large, and no current flows through the drain and the source.

[0046] The power supply control device 11 further transitions the state of the second switch Bi to a conductive state or an off state. When the power supply control device 11 fixes the state of the second switch Bi to an on state or performs PWM control of the second switch Bi, the state of the second switch Bi transitions to a conductive state. PWM stands for Pulse Width In PWM control of the second switch Bi, the second switch Bi is alternately switched between the on state and the off state at short intervals. Therefore, when the second switch Bi is in a conducting state, a current can flow through the drain and source of the second switch Bi.

[0047] The power supply control device 11 outputs an ON signal to each of the n switch devices A1, A2, ..., An. When an ON signal is input to the switch device Ai, the switch device Ai fixes the state of the second switch Bi to the ON state. The power supply control device 11 outputs a PWM signal to each of the n switch devices A1, A2, ..., An. The switch device Ai switches the state of the second switch Bi to the ON state or the OFF state in accordance with the input PWM signal.

[0048] FIG. 2 is an explanatory diagram of switching of the second switch Bi. FIG. 2 shows the transition of the voltage indicated by the PWM signal and the transition of the state of the second switch Bi. The horizontal axis of these transitions shows time. In FIG. 2, high-level voltage and low-level voltage are indicated by "H" and "L", respectively. As shown in FIG. 2, the voltage indicated by the PWM signal periodically switches from a low-level voltage to a high-level voltage. The ratio of the period during which the PWM signal indicates a high-level voltage to one period is the duty of the PWM signal. The power supply control device 11 adjusts the duty of the PWM signal by adjusting the timing at which the voltage indicated by the PWM signal switches from a high-level voltage to a low-level voltage.

[0049] When the power supply control device 11 outputs a PWM signal to the switch device Ai, the second switch Bi is PWM controlled. When the voltage indicated by the PWM signal is switched from a low-level voltage to a high-level voltage, the switch device Ai switches the state of the second switch Bi from an off state to an on state. When the voltage indicated by the PWM signal is switched from a high-level voltage to a low-level voltage, the switch device Ai switches the state of the second switch Bi from an on state to an off state.

[0050] Therefore, the state of the second switch Bi is periodically switched from an off state to an on state. When the timing at which the voltage indicated by the PWM signal is switched from a high-level voltage to a low-level voltage is adjusted, the timing at which the state of the second switch Bi is switched from an on state to an off state is adjusted. The proportion of the period during which the state of the second switch Bi is in the on state in one period is the duty of the PWM control of the second switch Bi. The duty of the second switch Bi is the same as the duty of the PWM signal. The power supply control device 11 adjusts the duty of the second switch Bi by adjusting the duty of the PWM signal.

[0051] The power supply control device 11 may periodically switch the voltage indicated by the PWM signal from a high-level voltage to a low-level voltage. In this case, the power supply control device 11 adjusts the duty of the PWM signal by adjusting the timing at which the voltage indicated by the PWM signal is switched from a low-level voltage to a high-level voltage. In the PWM control of the second switch Bi, the switch device Ai periodically switches the state of the second switch Bi from an on state to an off state. The switch device Ai adjusts the duty of the PWM control of the second switch Bi by adjusting the timing at which the state of the second switch Bi is switched from an off state to an on state.

[0052] The voltage of the ON signal is fixed to a high-level voltage. The power supply control device 11 transitions the state of the second switch Bi to a conductive state by outputting an ON signal or a PWM signal to the switch device Ai. When the first switch 20 is in an ON state and the second switch Bi is in a conductive state, a current flows from the positive electrode of the DC power source 10 through the first switch 20 and the second switch Bi to the load Ei. As a result, power is supplied to the load Ei. When power is supplied to the load Ei, the load Ei operates. When a current flows through the first switch 20 and the second switch Bi, a current is input from the source of the first switch 20 to the drain of the second switch Bi.

[0053] When the first switch 20 is in the on state and the power supply control device 11 is outputting a PWM signal to the switch device Ai, the power supply control device 11 adjusts the duty of the PWM signal to adjust the average value of the current flowing per unit time through the second switch Bi. The duty of the PWM signal is represented by D. The current value flowing through the second switch Bi when the first switch 20 and the second switch Bi are in the on state is referred to as the on current value. The on current value is represented by Ion. The average value of the current flowing per unit time through the second switch Bi is (D·Ion / 100) [A]. "·" represents the product. The higher the duty of the PWM signal (PWM control), the higher the average value of the current. The duty D is greater than 0 [%] and less than 100 [%].

[0054] When the state of the second switch Bi is fixed to the on state, the average value of the current is the on-current value Ion. When the state of the second switch Bi is fixed to the off state, the average value of the current is 0 [A]. When the power supply control device 11 outputs a PWM signal to the switch device Ai, the average value of the current exceeds 0 [A] and is less than the on-current value Ion.

[0055] The larger the current value flowing through the second switch Bi, the larger the power supplied to the load Ei. The performance of the load Ei varies depending on the power supplied to the load Ei. For example, if the load Ei is a motor, the larger the power supplied to the load Ei, the higher the rotation speed of the load Ei.

[0056] The power supply control device 11 outputs an off signal to each of the n switch devices A1, A2, ..., An. The voltage of the off signal is fixed to a low level voltage. When the off signal is input, the switch device Ai fixes the state of the second switch Bi to the off state. The power supply control device 11 outputs the off signal to the switch device Ai, thereby transitioning the state of the second switch Bi to the off state. When the state of the second switch Bi transitions from the conductive state to the off state, the flow of current through the second switch Bi stops. As a result, power supply to the load Ei through the second switch Bi stops, and the load Ei stops operating.

[0057] When the first switch 20 is in an on state, the power supply control device 11 controls power supply to the load Ei by transitioning the state of the second switch Bi to a conducting state or an off state. The power supply control device 11 adjusts the duty of the PWM signal to adjust the power supplied to the load Ei. When the power supply control device 11 transitions the state of the first switch 20 from an on state to an off state, the flow of current through the n second switches B1, B2, ..., Bn is stopped regardless of the states of the n second switches B1, B2, ..., Bn.

[0058] <Configuration of power supply control device 11> As shown in Fig. 1, the power supply control device 11 has a current output circuit 21, a first resistor 22, a first drive circuit 23, and a microcomputer (hereinafter referred to as a microcomputer) 24 in addition to a first switch 20. A drain of the first switch 20 is connected to the current output circuit 21. The current output circuit 21 is further connected to one end of a first resistor 22. The other end of the first resistor 22 is grounded. A gate of the first switch 20 is connected to the first drive circuit 23. The first drive circuit 23 is further connected to a connection node between the current output circuit 21 and the first resistor 22 and to the microcomputer 24. The microcomputer 24 is connected to each of the n switch devices A1, A2,..., An.

[0059] The current output circuit 21 draws in a current from the drain of the first switch 20 and outputs the drawn current to the first resistor 22. The current value flowing through the first switch 20 is referred to as a first switch current value. The current value drawn by the current output circuit 21 is expressed as (first switch current value) / (predetermined number). The predetermined number is, for example, 1000. All the current drawn by the current output circuit 21 flows through the first resistor 22. Therefore, the voltage value between both ends of the first resistor 22 is expressed as (first switch current value)·(resistance value of the first resistor 22) / (predetermined number). The resistance value of the first resistor 22 and the predetermined number are constant values. Therefore, the voltage value between both ends of the first resistor 22 indicates the first switch current value. The voltage value between both ends of the first resistor 22 is output to the first drive circuit 23 as analog current value information representing the first switch current value.

[0060] In the first switch 20, when the voltage value of the gate, whose reference potential is the potential of the source, becomes equal to or greater than a certain voltage value, the state of the first switch 20 switches from the OFF state to the ON state. In the first switch 20, when the voltage value of the gate, whose reference potential is the potential of the source, becomes less than a certain voltage value, the state of the first switch 20 switches from the ON state to the OFF state.

[0061] The microcomputer 24 outputs a high-level voltage or a low-level voltage to the first drive circuit 23. When the first switch current value indicated by the current value information is less than the current threshold value, and the microcomputer 24 switches the voltage output to the first drive circuit 23 from a low-level voltage to a high-level voltage, the first drive circuit 23 increases the gate voltage value, the reference potential of which is the ground potential, for the first switch 20. As a result, the gate voltage value, the reference potential of which is the source potential, for the first switch 20 increases to a value equal to or greater than a certain voltage value, and the state of the first switch 20 is switched to the on state.

[0062] When the first switch current value indicated by the current value information is less than the current threshold value, and the microcomputer 24 switches the voltage output to the first drive circuit 23 from a high-level voltage to a low-level voltage, the first drive circuit 23 reduces the gate voltage value whose reference potential is the ground potential for the first switch 20. As a result, the gate voltage value whose reference potential is the source potential for the first switch 20 decreases to a value less than a certain voltage value, and the state of the first switch 20 is switched to the off state.

[0063] As described above, the first drive circuit 23 switches the state of the first switch 20 to an on state or an off state. The first drive circuit 23 functions as a switching circuit. The microcomputer 24 instructs the first switch 20 to be switched to the on state by switching the voltage output to the first drive circuit 23 from a low-level voltage to a high-level voltage. In a similar case, the microcomputer 24 instructs the first switch 20 to be switched to the off state by switching the voltage output to the first drive circuit 23 from a high-level voltage to a low-level voltage.

[0064] When the first switch current value indicated by the current value information becomes equal to or greater than the current threshold, the first drive circuit 23 switches the state of the first switch 20 to the OFF state, regardless of the voltage output from the microcomputer 24 to the first drive circuit 23. This prevents a current whose value is equal to or greater than the current threshold from continuing to flow through the first switch 20.

[0065] The microcomputer 24 outputs an ON signal, an OFF signal, and a PWM signal to the switch device Ai. The microcomputer 24 adjusts the duty of the PWM signal.

[0066] <Configuration of switch device Ai> 3 is a circuit diagram of the switch device Ai. In addition to the second switch Bi, the switch device Ai has a second drive circuit Fi and a differential amplifier Gi. The differential amplifier Gi has a positive terminal, a negative terminal, and an output terminal. The gate of the second switch Bi is connected to the second drive circuit Fi. The second drive circuit Fi is further connected to the microcomputer 24. The drain and source of the second switch Bi are respectively connected to the positive terminal and the negative terminal of the differential amplifier Gi. The output terminal of the differential amplifier Gi is connected to the microcomputer 24.

[0067] In the second switch Bi, when the voltage value of the gate, whose reference potential is the potential of the source, becomes equal to or greater than a certain voltage value, the state of the second switch Bi changes from an off state to an on state. In the second switch Bi, when the voltage value of the gate, whose reference potential is the potential of the source, becomes less than a certain voltage value, the state of the second switch Bi changes from an on state to an off state.

[0068] The second drive circuit Fi switches the state of the second switch Bi to the on state by increasing the voltage value of the gate whose reference potential is the ground potential for the second switch Bi. When the voltage value of the gate whose reference potential is the ground potential for the second switch Bi increases, the voltage value of the gate whose reference potential is the source potential increases. When the voltage value of the gate whose reference potential is the source potential for the second switch Bi increases to a value equal to or greater than a certain voltage value, the state of the second switch Bi switches to the on state.

[0069] The second drive circuit Fi switches the state of the second switch Bi to an off state by lowering the voltage value of the gate whose reference potential is the ground potential for the second switch Bi. When the voltage value of the gate whose reference potential is the ground potential for the second switch Bi drops, the voltage value of the gate whose reference potential is the source potential drops. When the voltage value of the gate whose reference potential is the source potential for the second switch Bi drops to a value less than a certain voltage value for the second switch Bi, the state of the second switch Bi switches to an off state.

[0070] The microcomputer 24 outputs an on signal, an off signal, and a PWM signal to the second drive circuit Fi. When the microcomputer 24 outputs an on signal to the second drive circuit Fi, the second drive circuit Fi fixes the state of the second switch Bi to the on state. When the microcomputer 24 outputs an off signal to the second drive circuit Fi, the second drive circuit Fi fixes the state of the second switch Bi to the off state. Therefore, the microcomputer 24 outputs an on signal to the second drive circuit Fi to instruct the second drive circuit Fi to switch the second switch Bi to the on state. The microcomputer 24 outputs an off signal to the second drive circuit Fi to instruct the second drive circuit Fi to switch the second switch Bi to the off state.

[0071] When the microcomputer 24 outputs a PWM signal to the second drive circuit Fi, the second drive circuit Fi switches the state of the second switch Bi from OFF to ON when the voltage indicated by the PWM signal switches from a low level voltage to a high level voltage. Similarly, when the voltage indicated by the PWM signal switches from a high level voltage to a low level voltage, the second drive circuit Fi switches the state of the second switch Bi from ON to OFF.

[0072] The voltage value between the drain and source of the second switch Bi is referred to as the voltage value across the second switch Bi. The differential amplifier Gi amplifies the voltage between the drain and source of the second switch Bi and outputs the amplified voltage to the microcontroller 24. The voltage value output by the differential amplifier Gi to the microcontroller 24 is expressed as (voltage value across the second switch Bi)·(amplification factor). The amplification factor is a constant value. Therefore, the voltage value output by the differential amplifier Gi to the microcontroller 24 functions as analog voltage value information indicating the voltage value across the second switch Bi.

[0073] The microcomputer 24 identifies the state of the second switch Bi based on the voltage value across the second switch Bi indicated by the voltage value information. FIG. 4 is an explanatory diagram of the relationship between the voltage value across the second switch Bi and the state. FIG. 4 shows the voltage value across the second switch Bi when the first switch 20 is in the on state. Hereinafter, the voltage value across the DC power supply 10 will be referred to as the power supply voltage value. In FIG. 4, the power supply voltage value is represented by Vb.

[0074] When the second switch Bi is in the off state, no current flows through the drain and source of the second switch Bi. Therefore, no current flows through the load Ei, and no voltage drop occurs in the load Ei. As a result, the voltage value across the second switch Bi is substantially equal to the power supply voltage value Vb.

[0075] When the second switch Bi is in the on state, a current flows from the positive pole of the DC power supply 10 to the first switch 20, the second switch Bi, and the load Ei in that order. When the second switch Bi is in the on state, the resistance between the drain and source of the second switch Bi is sufficiently small. Therefore, the voltage across the second switch Bi is close to 0 V.

[0076] There is a possibility that a half-on fault occurs in the second switch Bi. When a half-on fault occurs in the second switch Bi, even when the second drive circuit Fi is instructed to switch the second switch Bi to the off state, the resistance value between the drain and source of the second switch Bi does not increase to a sufficiently large value. Therefore, a current continues to flow through the drain and source of the second switch Bi, and the voltage value across the second switch Bi is maintained within a certain voltage range. In FIG. 4, the upper limit voltage value and lower limit The voltage values ​​are indicated by V1 and V2, respectively. The upper limit voltage value V1 is less than the power supply voltage value Vb. The lower limit voltage value V2 exceeds the voltage value across the second switch Bi when the second switch Bi is in the on state. Values ​​within the voltage value range are less than the upper limit voltage value V1 and greater than or equal to the lower limit voltage value V2. The voltage value range corresponds to a predetermined range. The upper limit voltage value V1 and the lower limit voltage value V2 are determined in advance.

[0077] There is a possibility that a short-circuit fault occurs in the second switch Bi. When a short-circuit fault occurs in the second switch Bi, the state of the second switch Bi is maintained in the ON state even when the microcomputer 24 instructs the second drive circuit Fi to switch the second switch Bi to the OFF state. When the second switch Bi is in the ON state, the voltage value across the second switch Bi is less than the lower limit voltage value V2.

[0078] FIG. 5 is a table for explaining a method for detecting a failure of the second switch Bi. When the first switch 20 is in an on state, the microcomputer 24 acquires voltage value information when instructing to switch the second switch Bi to an off state. When the voltage value across the second switch Bi indicated by the acquired voltage value information is a value within the voltage value range, the microcomputer 24 acquires voltage value information again. A period during which the voltage value across the second switch Bi is maintained within the voltage value range is referred to as an unstable period of the second switch Bi. When the unstable period of the second switch Bi is equal to or longer than a predetermined period, the microcomputer 24 detects a half-on failure of the second switch Bi. When the voltage value across the second switch Bi indicated by the acquired voltage value information is less than a lower limit voltage value V2, the microcomputer 24 detects a short-circuit failure of the second switch Bi.

[0079] The microcomputer 24 outputs an on signal, an off signal, and a PWM signal to the second drive circuit Fi to transition the state of the second switch Bi to an off state or a conducting state. The microcomputer 24 adjusts the average value of the current flowing per unit time through one or more second switches in a conducting state among the n second switches B1, B2, ..., Bn so that the average value of the current flowing per unit time through the first switch 20 is less than a predetermined current value. The predetermined current value is equal to or less than the current threshold value described above.

[0080] When the microcomputer 24 detects a half-on failure in at least one of the n second switches B1, B2, ...Bn, it instructs the first drive circuit 23 to switch the first switch 20 to the OFF state. One or more specific switches are included in the n second switches B1, B2, ...Bn. The one or more specific switches are determined in advance. When the microcomputer 24 detects a short-circuit failure in at least one specific switch, it instructs the first drive circuit 23 to switch the first switch 20 to the OFF state.

[0081] When the microcomputer 24 detects a short-circuit failure in a second switch other than one or more specific switches among the n second switches B1, B2, ..., Bn, the microcomputer 24 does not instruct the first drive circuit 23 to switch the first switch 20 to the off state. The microcomputer 24 reduces the average value of the current flowing per unit time through the second switch in a conducting state other than the short-circuit failed second switch so that the average value of the current flowing per unit time through the first switch 20 is less than a predetermined current value.

[0082] <Microcomputer 24 Configuration> 6 is a block diagram showing the main configuration of the microcomputer 24. The microcomputer 24 has a first output unit 30, a storage unit 31, a control unit 32, n second output units H1, H2, . . . , Hn, and n A / D conversion units J1, J2, . . . , Jn. These are connected to an internal bus 33. The first output unit 30 is further connected to a first drive circuit 23. The second output unit Hi is further connected to a second drive circuit Fi. The A / D conversion unit Ji is further connected to the output terminal of a differential amplifier Gi.

[0083] The first output section 30 outputs a high-level voltage or a low-level voltage to the first drive circuit 23. The control section 32 instructs the first output section 30 to switch the voltage output to the first drive circuit 23 to a high-level voltage or a low-level voltage.

[0084] The control unit 32 instructs the second output unit Hi to output an on signal, an off signal, or a PWM signal to the second drive circuit Fi. The duty of the PWM signal is stored in the second output unit Hi. The control unit 32 changes the duty of the PWM signal stored in the second output unit Hi. When the second output unit Hi outputs a PWM signal, the second output unit Hi adjusts the duty of the PWM signal to the duty stored in the second output unit Hi.

[0085] The differential amplifier Gi of the switch device Ai outputs analog voltage value information to the A / D conversion unit Ji. The A / D conversion unit Ji converts the analog voltage value information input from the differential amplifier Gi into digital voltage value information. The control unit 32 acquires the digital voltage value information converted by the A / D conversion unit Ji.

[0086] The storage unit 31 is composed of, for example, a volatile memory and a non-volatile memory. A computer program P is stored in the storage unit 31. The control unit 32 has a processing element that executes processing, and functions as a processing unit. The processing element is, for example, a CPU (Central Processing Unit). The processing element (computer) of the control unit 32 executes the computer program P to execute power supply control processing of the loads E1, E2, . . . , En and switching processing of the first switch 20 in parallel. The power supply control processing of the load Ei is processing to control power supply to the load Ei. The switching processing of the first switch 20 is processing to switch the state of the first switch 20 to an on state or an off state.

[0087] The computer program P may be provided to the microcomputer 24 using a non-transitory storage medium Q that readably stores the computer program P. The storage medium Q is, for example, a portable memory. Examples of the portable memory include a CD-ROM, a Universal Serial Bus (USB) memory, an SD card, a micro SD card, and a Compact Flash (registered trademark). When the storage medium Q is a portable memory, the processing element of the control unit 32 may read the computer program P from the storage medium Q using a reading device (not shown). The read computer program P is written to the storage unit 31. Furthermore, the computer program P may be provided to the microcomputer 24 by a communication unit (not shown) of the microcomputer 24 communicating with an external device. In this case, the processing element of the control unit 32 acquires the computer program P through the communication unit. The acquired computer program P is written to the storage unit 31.

[0088] Furthermore, the number of processing elements included in the control unit 32 is not limited to 1 and may be 2 or more. When the control unit 32 has a plurality of processing elements, the plurality of processing elements may cooperate to execute the power supply control process of the loads E1, E2,...,En and the switching process of the first switch 20, etc.

[0089] A state table T1 and a duty table T2 are stored in the storage unit 31. The state table T1 indicates states of the n second switches B1, B2,...,Bn. The duty table T2 indicates the relationship between the states of the n second switches B1, B2,...,Bn and the duties of the PWM control of the n second switches B1, B2,...,Bn.

[0090] <Description of state table T1> 7 is a diagram showing the contents of the state table T1. As described above, the state table T1 shows the states of the n second switches B1, B2, . . . , Bn. As the state of the second switch Bi, one of a conductive state, an off state, a short circuit fault, and a half-on fault is shown. The state of the second switch Bi shown in the state table T1 is changed by the control unit 32.

[0091] <Description of Duty Table T2> FIG. 8 is a diagram showing the contents of the duty table T2. In the duty table T2, n duties corresponding to the states of the second switches B1, B2, . . . , Bn are shown. The duties in the duty table T2 are the duties of the PWM control of the second switch Bi. In FIG. 8, "-" indicates the off state.

[0092] As described above, the duty of the PWM control is greater than 0% and less than 100%. In the duty table T2, a duty of 100% indicates that the second switch Bi is fixed to the on state. A duty of 0% indicates that the second switch Bi is fixed to the off state. A duty of (100) indicates that the second switch Bi is fixed to the on state due to a short circuit fault.

[0093] 8 shows an example of a duty table T2 in which the integer n is 3. When no half-on fault or short circuit fault occurs, and one of the three second switches B1, B2, B3 is in a conducting state, the state is fixed to the on state. When two of the three second switches B1, B2, B3 are in a conducting state, PWM control is performed on each of the second switches in the conducting state. When the three second switches B1, B2, B3 are in a conducting state, PWM control is performed on each of the three second switches B1, B2, B3.

[0094] When no half-on fault or short circuit fault occurs, the duty of the PWM control of each of the second switches B1, B2, B3 decreases as the number of second switches in a conducting state increases. For example, when the number of second switches in a conducting state is two, the duty of the PWM control of the second switch B1 is 80% or 70%. When the number of second switches in a conducting state is three, the duty of the PWM control of the second switch B1 is 50%.

[0095] When a short circuit fault occurs in the second switch B1, current is allowed to flow through the second switches B2 and B3. When one or both of the second switches B2 and B3 are in a conducting state, PWM control of the second switch in the conducting state is performed.

[0096] Assume that the states of multiple second switches among the three second switches B1, B2, and B3 are in a conducting state when a half-on fault or short circuit fault does not occur. In this case, when the state of one second switch transitions from a conducting state to a short circuit fault, the duty of the PWM control of the second switch in the conducting state decreases. In the example of FIG. 8, when the two second switches B1 and B2 are in a conducting state when a half-on fault or short circuit fault does not occur, the duty of the PWM control of the second switch B2 is 70%. When the state of the second switch B1 transitions from a conducting state to a short circuit fault, the duty of the PWM control of the second switch B2 decreases from 70% to 40%.

[0097] When no half-on fault or short circuit fault occurs and the three second switches B1, B2, and B3 are in a conducting state, the duty of the PWM control of each of the second switches B2 and B3 is 50%. When the state of the second switch B1 transitions from a conducting state to a short circuit fault, the duty of the PWM control of each of the second switches B2 and B3 decreases from 50% to 20%.

[0098] In the example of Fig. 8, when a short circuit fault occurs in one of the second switches B2, B3, the state of the first switch 20 is switched from the on state to the off state. Therefore, three duties in the case where at least one of the second switches B2, B3 is in the short circuit fault state are not shown. In the example of Fig. 8, each of the second switches B2, B3 is a specific switch.

[0099] <Power supply control process for load E1> The power supply control process for each of the loads E1, E2,...,En is executed by the control unit 32 when the state of the first switch 20 is in the on state. In the power supply control process for the load Ei, the control unit 32 changes the state of the second switch Bi in the state table T1. Therefore, during the execution of the power supply control process for the load E1, the state of one of the second switches B2, B3,...,Bn may be changed.

[0100] 9 and 10 are flowcharts showing the procedure of the power supply control process for the load E1. In the power supply control process for the load E1, the control unit 32 first determines whether or not to operate the load E1 (step S1). When the control unit 32 determines not to operate the load E1 (S1: NO), it executes step S1 again. The control unit 32 waits until the timing to operate the load E1 arrives.

[0101] When the control unit 32 determines that the load E1 is to be operated (S1: YES), the control unit 32 changes the state of the second switch B1 from the OFF state to the conducting state in the state table T1 (step S2). Next, the control unit 32 determines whether or not to fix the state of the second switch B1 to the ON state based on the state table T1 and the duty table T2 (step S3).

[0102] 8 is used, when the second switches B2 and B3 are in the OFF state in the state table T1, the control unit 32 determines in step S3 that the state of the second switch B1 is to be fixed to the ON state. In a similar case, when at least one of the second switches B2 and B3 is in the conducting state in the state table T1, the control unit 32 determines in step S3 that the state of the second switch B1 is not to be fixed to the ON state.

[0103] When the control unit 32 determines that the state of the second switch B1 is to be fixed to the ON state (S3: YES), it instructs the second output unit H1 to output an ON signal to the second drive circuit F1 (step S4). As a result, the second drive circuit F1 fixes the state of the second switch B1 to the ON state.

[0104] When the control unit 32 determines not to fix the state of the second switch B1 to the on state (S3: NO), the control unit 32 changes the duty stored in the first output unit 30 based on the state table T1 and the duty table T2 (step S5). In the case where the duty table T2 shown in Fig. 8 is used, for example, when the states of the second switches B2 and B3 are the conductive state and the off state in the state table T1, in step S5, the control unit 32 changes the duty to 80[%].

[0105] After executing step S5, the control unit 32 instructs the second output unit H1 to output a PWM signal to the second drive circuit F1 (step S6). As a result, the second drive circuit F1 performs PWM control of the second switch B1 according to the PWM signal input from the second output unit H1. The duty of the PWM control is the duty changed in step S5, i.e., the duty shown in the duty table T2. When the second switch B1 is in a conducting state, power is supplied to the load E1, and the load E1 operates.

[0106] After executing one of steps S4 and S6, the control unit 32 determines whether or not to stop the operation of the load E1 (step S7). If the control unit 32 determines not to stop the operation of the load E1 (S7: NO), it determines whether or not the contents of the state table have been changed (step S8). If the control unit 32 determines that the contents of the state table have not been changed (S8: NO), it executes step S7. The control unit 32 waits until the timing to stop the operation of the load E1 arrives or the contents of the state table are changed.

[0107] When the control unit 32 determines that the contents of the state table have been changed (S8: YES), it determines whether the state of the first switch 20 is in the OFF state based on the changed state table (step S9). As described above, when a half-ON failure is detected in at least one of the n second switches B1, B2, ... Bn, the state of the first switch 20 is switched to the OFF state. Furthermore, when a short-circuit failure is detected in at least one specific switch, the state of the first switch 20 is switched to the OFF state.

[0108] Therefore, if the state of at least one of the second switches B2, B3, ..., Bn in the state table indicates a half-on fault, in step S9, the control unit 32 determines that the state of the first switch 20 is the off state. Furthermore, if the state of at least one specific switch in the state table indicates a short-circuit fault, in step S9, the control unit 32 determines that the state of the first switch 20 is the off state.

[0109] When the control unit 32 determines that the first switch 20 is not in the OFF state (S9: NO), the control unit 32 executes step S3 again. The second output unit H1 outputs an ON signal or a PWM signal to the second drive circuit F1 according to the state table T1 and the duty table T2.

[0110] It is assumed that the states of the second switches B2 and B3 are a conducting state and an off state in the state table T1 when the duty table T2 shown in FIG. 8 is used. When the state of the second switch B2 is changed to an off state in the state table T1, the control unit 32 executes step S4, and the second output unit H1 outputs an on signal. It is also assumed that the states of the second switches B2 and B3 are an off state in the state table T1 when the duty table T2 shown in FIG. 8 is used. When the state of the second switch B3 is changed to a conducting state in the state table T1, the control unit 32 executes steps S5 and S6, and the second output unit H1 outputs a PWM signal with a duty of 70%.

[0111] When the control unit 32 determines that the first switch 20 is in the OFF state (S9: YES), it instructs the second output unit H1 to output an OFF signal to the second drive circuit F1 (step S10). This fixes the state of the second switch B1 to the OFF state. After executing step S10, the control unit 32 ends the power supply control process for the load E1. In this case, the control unit 32 does not execute the power supply control process for the load E1 again.

[0112] When the control unit 32 determines that the operation of the load E1 is to be stopped (S7: YES), it instructs the second output unit H1 to output an OFF signal to the second driving circuit F1 (step S11). By executing step S11, the control unit 32 instructs the second driving circuit F1 to switch the second switch B1 to the OFF state. After executing step S11, the control unit 32 acquires voltage value information from the A / D conversion unit J1 (step S12).

[0113] Next, the control unit 32 judges whether or not the voltage value across the second switch B1 indicated by the voltage value information acquired in step S12 exceeds the upper limit voltage value of the voltage value range (step S13). As shown in FIG. 4, when the state of the second switch B1 is fixed to the OFF state, the voltage value across the second switch B1 exceeds the upper limit voltage value V1. When the control unit 32 judges that the voltage value across the second switch B1 exceeds the upper limit voltage value (S13: YES), it changes the state of the second switch B1 to the OFF state in the state table T1 (step S14) and ends the power supply control process of the load E1. In this case, when the state of the first switch 20 is the ON state, the control unit 32 executes the power supply control process of the load E1 again.

[0114] When the control unit 32 determines that the voltage value across the second switch B1 is equal to or lower than the upper limit voltage value (S13: NO), it determines whether or not the voltage value across the second switch B1 indicated by the voltage value information acquired in step S12 is lower than the lower limit voltage value of the voltage value range (step S15). As described in the description of FIG. 5, when the voltage value across the second switch B1 is lower than the lower limit voltage value, a short-circuit fault occurs in the second switch B1. When the control unit 32 determines that the voltage value across the second switch B1 is lower than the lower limit voltage value (S15: YES), it changes the state of the second switch B1 to short-circuit fault in the state table T1 (step S16).

[0115] When the control unit 32 determines that the voltage value across the second switch B1 is equal to or greater than the lower limit voltage value (S15: NO), it determines whether the unstable period of the second switch B1 is equal to or greater than a predetermined period (step S17). As described above, the unstable period of the second switch B1 is a period during which the voltage value across the second switch B1 is maintained within a voltage value range. The unstable period is measured, for example, by a timer (not shown). The start point of the unstable period is, for example, the time when step S11 is executed. As described in the description of FIG. 5, when the unstable period of the second switch B1 is equal to or greater than the predetermined period, a half-on fault occurs in the second switch B1.

[0116] When the control unit 32 determines that the unstable period is less than the predetermined period (S17: NO), it executes step S12 again. The control unit 32 determines again whether or not the voltage value across the second switch B1 indicated by the newly acquired voltage value information is within the voltage value range. When the control unit 32 determines that the unstable period is equal to or longer than the predetermined period (S17: YES), it changes the state of the second switch B1 to half-on failure in the state table T1 (step S18). When the control unit 32 executes one of steps S16 and S18, it ends the power supply control process for the load E1. In this case, the control unit 32 does not execute the power supply control process for the load E1 again.

[0117] <Power supply control process for loads E2, E3, . . . , En> The power supply control process of each of the loads E2, E3,...,En is executed by the control unit 32 in the same manner as the power supply control process of the load E1. An arbitrary integer equal to or greater than 2 and equal to or less than n is denoted as k. The integer k may be any of 2, 3,...,n. The load E1, the second switch B1, the second drive circuit F1, and the second output unit H1 described in the description of the power supply control process of the load E1 correspond to the load Ek, the second switch Bk, the second drive circuit Fk, and the second output unit Hk in the description of the power supply control process of the load Ek, respectively.

[0118] In the case where the duty table T2 shown in Fig. 8 is used, when the state of the second switch B1 changes to a short-circuit fault in the state table T1, the state of the first switch 20 does not switch to the off state. Therefore, for example, in the power supply control process of the load E2, the state of the second switch B2 is maintained in a conductive state. When the state of the second switch B1 changes from a conductive state to a short-circuit fault in the state table T1, the control unit 32 reduces the duty of the PWM control of the second switch B2 from 70[%] to 40[%] as shown in Fig. 8.

[0119] <Effect of power supply control processing of loads E1, E2,...,En> When the power supply control process for the loads E1, E2, ..., En is executed, the control unit 32 adjusts the average value of the current flowing per unit time through the second switch Bi in accordance with one or more second switches in a conducting state. Therefore, the maximum value of the average value of the current flowing per unit time through the first switch 20 is small. As a result, a small switch with a small tolerance for the average value of the current can be used as the first switch 20.

[0120] As described above, the control unit 32 adjusts the average value of the current flowing per unit time through the second switch Bi. Therefore, all of the n second switches B1, B2, ..., Bn are not fixed to the on state. As a result, the maximum value of the average value of the current flowing per unit time through the first switch 20 is less than the value of the current flowing through the first switch 20 when the states of the first switch 20 and the n second switches B1, B2, ..., Bn are fixed to the on state.

[0121] The control unit 32 also instructs the second output unit Hi to output an OFF signal to the second drive circuit Fi, thereby transitioning the second switch Bi to an OFF state. The control unit 32 instructs the second output unit Hi to output an ON signal or a PWM signal to the second drive circuit Fi, thereby transitioning the state of the second switch Bi to a conducting state. When the second output unit Hi outputs an ON signal to the second drive circuit Fi, the state of the second switch Bi is fixed to an ON state. When the second output unit Hi outputs a PWM signal to the second drive circuit Fi, PWM control of the second switch Bi is performed. When the state of the first switch 20 is an ON state, if the state of the second switch Bi is fixed to an ON state or PWM control of the second switch Bi is performed, current starts flowing through the second switch Bi.

[0122] <Switching Process of First Switch 20> 11 is a flowchart showing a procedure of the switching process of the first switch 20. In the switching process of the first switch 20, the control unit 32 determines whether or not to switch the state of the first switch 20 from the OFF state to the ON state (step S21). The microcomputer 24 may have a signal input unit to which a signal is input from outside the power supply control device 11. In step S21, for example, when a signal indicating switching of the first switch 20 to the ON state is input to the signal input unit, the control unit 32 determines to switch the state of the first switch 20 to the ON state.

[0123] When the control unit 32 determines not to switch the state of the first switch 20 to the on state (S21: NO), it executes step S21 again. The control unit 32 waits until the timing to switch the state of the first switch 20 to the on state arrives. When the control unit 32 determines to switch the state of the first switch 20 to the on state (S21: YES), it instructs the first drive circuit 23 to switch the first switch 20 to the on state (step S22). Specifically, the control unit 32 instructs the first output unit 30 to switch the voltage output to the first drive circuit 23 to a high-level voltage.

[0124] After executing step S22, the control unit 32 determines whether or not a half-on fault has occurred in at least one of the n second switches B1, B2, ..., Bn based on the state table T1 (step S23). If the control unit 32 determines that a half-on fault has not occurred (S23: NO), it determines whether or not a short-circuit fault has occurred in at least one of the one or more specific switches based on the state table T1 (step S24). When the duty table T2 shown in Fig. 8 is used, the second switches B2 and B3 are the specific switches.

[0125] The specific switch is, for example, a second switch that is connected to a load that, if continued to be activated, may interfere with the operation of the vehicle M. A second switch that is different from the specific switch is, for example, connected to a load such as a headlight or wiper motor that does not interfere with the operation of the vehicle M even if continued to be activated.

[0126] When the control unit 32 determines that no short-circuit fault has occurred in any of the specific switches (S24: NO), it determines whether or not to switch the state of the first switch 20 to the OFF state (step S25). In step S25, for example, when the n second switches B1, B2, ..., Bn are in the OFF state, the control unit 32 determines to switch the state of the first switch 20 to the ON state when an OFF signal indicating switching the first switch 20 to the OFF state is input to the signal input unit.

[0127] When the control unit 32 determines not to switch the state of the first switch 20 to the OFF state (S25: NO), it executes step S23 again. When the control unit 32 determines that a half-ON fault has occurred (S23: YES), when it determines that a short-circuit fault has occurred in at least one of the one or more specific switches (S24: YES), or when it determines that the state of the first switch 20 is to be switched to the ON state (S25: YES), it instructs the first drive circuit 23 to switch the first switch 20 to the OFF state (step S26). Specifically, the control unit 32 instructs the first output unit 30 to switch the voltage output to the first drive circuit 23 to a low-level voltage.

[0128] After executing step S26, the control unit 32 ends the switching process of the first switch 20. If the control unit 32 ends the switching process of the first switch 20 after determining in step S23 that a half-on fault has occurred or after determining in step S24 that a short-circuit fault has occurred, the control unit 32 does not execute the switching process of the first switch 20 again. If the control unit 32 ends the switching process of the first switch 20 after determining in step S25 that the state of the first switch 20 is to be switched to the OFF state, the control unit 32 executes the switching process of the first switch 20 again.

[0129] As described above, in the power supply control process for the load Ei, when the control unit 32 instructs the second drive circuit Fi to switch the second switch Bi to the OFF state, if the unstable period of the second switch Bi becomes equal to or longer than a predetermined period, the control unit 32 changes the state of the second switch Bi to a half-ON failure in the state table T1. In the switching process for the first switch 20, when the state of at least one of the n second switches B1, B2, ..., Bn is changed to a half-ON failure in the state table T1, the control unit 32 instructs the first drive circuit 23 to switch the first switch to the OFF state. As a result, the state of the first switch 20 is switched to the OFF state, and the flow of current through the second switches B1, B2, ..., Bn is stopped.

[0130] When a current flows through the second switch in which a half-on fault occurs, the amount of heat generated is large. Therefore, if a current continues to flow through the second switch in which a half-on fault occurs, the temperature of the second switch in which a half-on fault occurs may rise to an abnormal temperature. As described above, when a half-on fault occurs in the second switch Bi, the flow of current through the second switch Bi stops. Therefore, the temperature of the second switch Bi is prevented from rising to an abnormal temperature.

[0131] In the power supply control process for the load Ei, when the control unit 32 instructs the second drive circuit Fi to switch the second switch Bi to the off state and the voltage value across the second switch Bi is less than the lower limit voltage value, the control unit 32 changes the state of the second switch Bi to a short-circuit fault in the state table T1. In the switching process for the first switch 20, when the state of a specific switch is changed to a short-circuit fault in the state table T1, the control unit 32 instructs the first drive circuit 23 to switch the first switch to the off state. The lower limit voltage value corresponds to a predetermined voltage value.

[0132] When the state of the second switch different from the specific switch in the state table T1 is changed to a short-circuit fault, the control unit 32 reduces the average value of the current flowing per unit time through the second switch in a conducting state different from the specific switch. When a short-circuit fault occurs in the second switch different from the specific switch, power supply through the second switch in which the short-circuit fault occurs is permitted. In order to prevent a large current from continuing to flow through the first switch 20, the average value of the current flowing per unit time through the second switch in a conducting state is reduced.

[0133] (Embodiment 2) In the first embodiment, the voltage value across the second switch Bi is used to detect a failure of the second switch Bi. However, the parameter used to detect a failure of the second switch Bi is not limited to the voltage value across the second switch Bi. As described in the first embodiment, i is any natural number equal to or less than n. The following describes the differences between embodiment 2 and embodiment 1. Since the configurations other than those described below are common to embodiment 1, the components common to embodiment 1 are given the same reference numerals as embodiment 1 and descriptions thereof will be omitted.

[0134] <Configuration of switch device Ai> 12 is a circuit diagram of a switch device Ai in the second embodiment. The switch device Ai in the second embodiment has a second switch Bi and a second drive circuit Fi, similar to the first embodiment. The switch device Ai in the second embodiment further has a second current output circuit Ui and a second resistor Ri instead of the differential amplifier Gi. The drain of the second switch Bi is connected to the second current output circuit Ui. The second current output circuit Ui is further connected to one end of the second resistor Ri. The other end of the second resistor Ri is grounded. The connection node between the second current output circuit Ui and the second resistor Ri is connected to the A / D conversion unit Ji of the microcomputer 24.

[0135] The second current output circuit Ui draws in a current from the drain of the second switch Bi and outputs the drawn current to the second resistor Ri. The current value flowing through the second switch Bi is referred to as the second switch current value. The current value drawn by the second current output circuit Ui is expressed as (second switch current value) / (second predetermined number). The second predetermined number is, for example, 1000. All the current drawn by the second current output circuit Ui flows through the second resistor Ri. Therefore, the voltage value between both ends of the second resistor Ri is expressed as (second switch current value)·(resistance value of the second resistor Ri) / (second predetermined number). The resistance value of the second resistor Ri and the second predetermined number are constant values. Therefore, the voltage value between both ends of the second resistor Ri indicates the second switch current value. The voltage value between both ends of the second resistor Ri is output to the A / D conversion unit Ji of the microcomputer 24 as analog second current value information representing the second switch current value.

[0136] The A / D conversion unit Ji converts the analog second current value information input from the connection node between the second current output circuit Ui and the second resistor Ri into digital second current value information. The control unit 32 of the microcomputer 24 acquires the digital second current value information converted by the A / D conversion unit Ji.

[0137] The control unit 32 of the microcomputer 24 identifies the state of the second switch Bi based on the second switch current value indicated by the second current value information. Fig. 13 is an explanatory diagram of the relationship between the second switch current value and the state of the second switch Bi. Fig. 13 shows the second switch current value of the second switch Bi when the state of the first switch 20 is the on state.

[0138] When the second switch Bi is in the off state, the second switch current value is 0 [A]. As described in the description of the first embodiment, when the first switch 20 and the second switch Bi are in the on state, the second switch current value is the on current value. The on current value is sufficiently large. The on current value is represented by Ion. The resistance value between the drain and source of the first switch 20 in the on state is referred to as the first on resistance value. The resistance value between the drain and source of the second switch Bi in the on state is referred to as the second on resistance value. The resistance value of the load Ei is referred to as the load resistance value. The on current value Ion is represented by (power supply voltage value) / ((first on resistance value)+(second on resistance value)+(load resistance value)).

[0139] As described in the description of the first embodiment, when a half-on failure occurs in the second switch Bi, even when the second drive circuit Fi is instructed to switch the second switch Bi to the off state, the resistance value between the drain and source of the second switch Bi does not increase to a sufficiently large value, so that a current continues to flow through the drain and source of the second switch Bi.

[0140] In FIG. 13, the upper limit current value and lower limit The current values ​​are indicated by I1 and I2, respectively. The current value range corresponds to a second predetermined range. The upper limit current value I1 is less than the on current value Ion. The lower limit current value I2 is greater than 0 [A]. Values ​​within the current value range are less than the upper limit current value I1 and greater than or equal to the lower limit current value I2. The upper limit current value I1 and the lower limit current value I2 are determined in advance. When a half-on fault occurs in the second switch Bi and an instruction is given to switch the second switch Bi to the off state, the current value flowing through the second switch Bi is maintained at a value within the second predetermined range.

[0141] As described in the description of the first embodiment, when a short-circuit fault occurs in the second switch Bi, the state of the second switch Bi is maintained in the on state even when the microcomputer 24 instructs the second drive circuit Fi to switch the second switch Bi to the off state. When the second switch Bi is in the on state, the second switch current value is the on current value Ion, which exceeds the upper limit current value I1.

[0142] 14 is a table for explaining a method for detecting a failure of the second switch Bi. When the first switch 20 is in an on state, the control unit 32 of the microcomputer 24 acquires current value information from the A / D conversion unit Ji when instructing to switch the second switch Bi to an off state. When the second switch current value indicated by the acquired current value information is within the current value range, the control unit 32 acquires the current value information again.

[0143] In the second embodiment, the unstable period of the second switch Bi is a period during which the second switch current value of the second switch Bi is maintained within a current value range. Period of instability When the second switch current value indicated by the acquired current value information exceeds the upper limit current value I1, the control unit 32 detects a short-circuit fault of the second switch Bi.

[0144] <Power supply control process for load E1> As described in the description of the first embodiment, the power supply control process for each of the loads E1, E2, ..., En is executed by the control unit 32 when the first switch 20 is in the on state. Fig. 15 is a flowchart showing the procedure of the power supply control process for the load E1. In the second embodiment, some steps executed in the power supply control process for the load E1 are executed in the same manner as in the first embodiment. Descriptions of steps S1 to S11, S14, S16, and S18 executed in the same manner as in the first embodiment will be omitted.

[0145] As described in the description of the first embodiment, in the power supply control process for the load E1, the control unit 32 executes step S11 to instruct the second drive circuit F1 to switch the second switch B1 to the off state. After executing step S11, the control unit 32 acquires second current value information from the A / D conversion unit J1 (step S31). Next, the control unit 32 determines whether the second switch current value indicated by the second current value information acquired in step S31 is less than the lower limit current value (step S32).

[0146] When the control unit 32 determines that the second switch current value is less than the lower limit current value (S32: YES), the control unit 32 executes step S14. After executing step S14, the control unit 32 ends the power supply control process for the load E1. In this case, when the first switch 20 is in the on state, the control unit 32 executes the power supply control process for the load E1 again.

[0147] When the control unit 32 determines that the second switch current value is equal to or greater than the lower limit current value (S32: NO), it determines whether or not the second switch current value indicated by the second current value information acquired in step S31 exceeds the upper limit current value (step S33). When the control unit 32 determines that the second switch current value exceeds the upper limit current value (S33: YES), it executes step S16. When the control unit 32 determines that the second switch current value is equal to or less than the upper limit current value (S33: NO), it determines whether or not the unstable period of the second switch B1 is equal to or greater than a second predetermined period that is determined in advance (step S34).

[0148] As described above, the unstable period of the second switch B1 is a period during which the second switch current value of the second switch B1 is within the current value range. As described in the description of the first embodiment, the unstable period is measured, for example, by a timer. The start point of the unstable period is, for example, the time point when step S11 is executed. As described in the description of FIG. 14, when the unstable period of the second switch B1 is equal to or longer than the second predetermined period, a half-on fault occurs in the second switch B1.

[0149] When the control unit 32 determines that the unstable period is less than the second predetermined period (S34: NO), it executes step S31 again. The control unit 32 determines again whether or not the second switch current value of the second switch B1 indicated by the newly acquired current value information is within the current value range. When the control unit 32 determines that the unstable period is equal to or greater than the second predetermined period (S34: YES), it executes step S18. When one of steps S16 and S18 has been executed, the power supply control process of the load E1 is terminated. In this case, the control unit 32 does not execute the power supply control process of the load E1 again.

[0150] <Power supply control process for loads E2, E3, . . . , En> The power supply control process of each of the loads E2, E3, ..., En is executed by the control unit 32 in the same manner as the power supply control process of the load E1. The load E1, the second switch B1, the second drive circuit F1, and the second output unit H1 described in the description of the power supply control process of the load E1 correspond to the load Ek, the second switch Bk, the second drive circuit Fk, and the second output unit Hk in the description of the power supply control process of the load Ek. As described in the description of the first embodiment, k is any integer equal to or greater than 2 and equal to or less than n.

[0151] As described above, in the power supply control process for the load Ei, when the control unit 32 instructs the second drive circuit Fi to switch the second switch Bi to the OFF state, if the unstable period of the second switch Bi becomes equal to or longer than the second predetermined period, the control unit 32 changes the state of the second switch Bi to a half-ON failure in the state table T1. In the switching process for the first switch 20, when the state of at least one of the n second switches B1, B2, ..., Bn is changed to a half-ON failure in the state table T1, the control unit 32 instructs the first drive circuit 23 to switch the first switch to the OFF state. As a result, the state of the first switch 20 is switched to the OFF state, and the flow of current through the second switches B1, B2, ..., Bn is stopped.

[0152] In the power supply control process for the load Ei, when the control unit 32 instructs the second drive circuit Fi to switch the second switch Bi to the off state and the second switch current value of the second switch Bi exceeds the upper limit current value, the control unit 32 changes the state of the second switch Bi to a short-circuit fault in the state table T1. In the switching process for the first switch 20, when the state of a specific switch is changed to a short-circuit fault in the state table T1, the control unit 32 instructs the first drive circuit 23 to switch the first switch to off. The upper limit current value corresponds to a predetermined current value.

[0153] When the state of the second switch different from the specific switch in the state table T1 is changed to a short-circuit fault, the control unit 32 reduces the average value of the current flowing per unit time through the second switch in a conducting state different from the specific switch. When a short-circuit fault occurs in the second switch different from the specific switch, power supply through the second switch in which the short-circuit fault occurs is permitted. By reducing the average value of the current, a large current is prevented from continuing to flow through the first switch 20.

[0154] <Modifications of the First and Second Embodiments> In the first and second embodiments, the configuration for detecting the first switch current value is not limited to the configuration using the current output circuit 21 and the first resistor 22. For example, in the power supply control device 11, a shunt resistor may be disposed in a path of a current flowing through the drain and source of the first switch 20. In this case, the voltage across the shunt resistor is amplified by, for example, a differential amplifier.

[0155] The differential amplifier outputs the amplified voltage to the first drive circuit 23. The voltage value output by the differential amplifier functions as analog current value information. Since the resistance value of the shunt resistor is a constant value, the voltage value between both ends of the shunt resistor is proportional to the first switch current value. Furthermore, since the amplification factor of the differential amplifier is a constant value, the voltage value output by the differential amplifier is also proportional to the first switch current value. Therefore, the voltage value output by the differential amplifier indicates the first switch current value.

[0156] The method of reducing the average value of the current flowing per unit time through the second switch Bi is not limited to the method of PWM control of the second switch Bi. A variable resistor may be connected between the source of the second switch Bi and one end of the load E1. The average value of the current flowing per unit time through the second switch Bi may be reduced by adjusting the resistance value of the variable resistor.

[0157] The first switch 20 is not limited to an N-channel FET, and may be a P-channel FET, a bipolar transistor, a relay contact, or the like. Therefore, the first switch 20 may be different from a semiconductor switch. When the first switch 20 is a relay contact, for example, a first switch current value is detected using a shunt resistor and a differential amplifier. Moreover, the second switch Bi is not limited to an N-channel FET, and may be a P-channel FET or a bipolar transistor, or the like. Furthermore, the second switch Bi may be included in the power supply control device 11.

[0158] The control unit 32 may not adjust the average value of the current flowing per unit time for all of the n second switches B1, B2, ..., Bn in accordance with one or more second switches in a conducting state. For some second switches, the duty when the state is changed to a conducting state may be fixed. Furthermore, when the control unit 32 detects a short-circuit failure of the second switch Bi, it may instruct the first switch 20 to be switched to the off state, regardless of whether the second switch Bi is a specific switch or not.

[0159] In the first embodiment, the control unit 32 may detect a short-circuit failure of the second switch Bi based on a second switch current value of the second switch Bi, similar to the second embodiment. Also, in the second embodiment, the control unit 32 may detect a short-circuit failure of the second switch Bi based on a voltage value across the second switch Bi, similar to the first embodiment.

[0160] In the second embodiment, the configuration for detecting the second switch current value of the second switch Bi is not limited to the configuration using the second current output circuit Ui and the second resistor Ri. For example, a second shunt resistor may be disposed in the path of the current flowing through the drain and source of the second switch Bi. In this case, the voltage between both ends of the second shunt resistor is amplified by, for example, a second differential amplifier. The second differential amplifier outputs the amplified voltage to the A / D conversion unit Ji. The voltage value output by the second differential amplifier functions as analog second current value information. Since the resistance value of the second shunt resistor is a constant value, the voltage value between both ends of the second shunt resistor is proportional to the second switch current value. In addition, since the amplification factor of the second differential amplifier is a constant value, the voltage value output by the second differential amplifier is also proportional to the first switch current value. Therefore, the voltage value output by the second differential amplifier indicates the first switch current value.

[0161] The disclosed embodiments 1 and 2 are illustrative in all respects and should not be considered as limiting. The scope of the present invention is defined by the claims, not by the above meaning, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0162] 1 Power System 10 DC power supply 11 Power supply control device 20 First Switch 21 Current output circuit 22 1st resistor 23 First drive circuit (switching circuit) 24 Microcomputer 30 First output section 31 Storage section 32 Control section (processing section) 33 Internal Bus A1, A2,..., An Switching device B1, B2, , Bn Second switch E1,E2,...,En load F1, F2, , Fn Second drive circuit G1, G2, . . . , Gn Differential amplifier H1,H2,...,Hn 2nd output section J1, J2, . . . , Jn A / D conversion section M Vehicle P Computer Program Q storage medium R1,R2,...,Rn 2nd resistor T1 State Table T2 Duty Table U1, U2, , Un Second current output circuit

Claims

1. A first switch; A processing unit for executing processing; Equipped with the processing unit transitions a state of each of a plurality of second switches to which a current is input from the first switch to an off state or a current-passing state in which a current can pass; The processing unit adjusts an average value of a current flowing per unit time for at least one second switch in accordance with the one or more second switches in the conducting state, thereby making the average value of a current flowing per unit time through the first switch less than a current value flowing through the first switch when the states of the first switch and all the second switches are fixed to an on state. Power supply control device.

2. A first switch; A processing unit for executing processing; Equipped with the processing unit transitions a state of each of a plurality of second switches to which a current is input from the first switch to an off state or a current-passing state in which a current can pass; The processing unit adjusts an average value of a current flowing per unit time for at least one second switch in accordance with the one or more second switches in the conducting state; a switching circuit that switches a state of the first switch between an on state and an off state; the switching circuit switches the state of the first switch to an off state when a value of a current flowing through the first switch becomes equal to or greater than a current threshold; The switching circuit is connected to the processing unit and a current output circuit that detects a value of a current flowing through the first switch. Power supply control device.

3. A first switch; A processing unit for executing processing; Equipped with the processing unit transitions a state of each of a plurality of second switches to which a current is input from the first switch to an off state or a current-passing state in which a current can pass; The processing unit adjusts an average value of a current flowing per unit time for at least one second switch in accordance with the one or more second switches in the conducting state; Instruct the second switch to be switched to an off state; instructing to switch the first switch to the off state when a voltage value between both ends of a specific switch, which is determined in advance among the plurality of second switches, is less than the predetermined voltage value in a case where a command has been issued to switch the second switch to the off state; The specific switch is a second switch connected to a load that may cause a disruption to the operation of a vehicle in which the first switch is installed. Power supply control device.

4. A first switch; A processing unit for executing processing; Equipped with the processing unit transitions a state of each of a plurality of second switches to which a current is input from the first switch to an off state or a current-passing state in which a current can pass; The processing unit adjusts an average value of a current flowing per unit time for at least one second switch in accordance with the one or more second switches in the conducting state; Instruct the second switch to be switched to an off state; instructing to switch the first switch to the off state when a current value flowing through a specific switch, which is predetermined among the plurality of second switches, exceeds the predetermined current value in a case where a command to switch the second switch to the off state has been issued; The specific switch is a second switch connected to a load that may cause a disruption to the operation of a vehicle in which the first switch is installed. Power supply control device.

5. The average value of the current flowing through the first switch per unit time is and when the states of all the second switches are fixed to the on state, through the first switch The current flow is less than the value The power supply control device according to any one of claims 1 to 4.

6. The state of the second switch is fixed to an on state, or the PWM of the second switch is When the control is performed, the state of the second switch transitions to the conducting state. The power supply control device according to any one of claims 1 to 5.

7. a switching circuit that switches a state of the first switch between an on state and an off state; The switching circuit is configured to switch a current flowing through the first switch when the current flowing through the first switch reaches a current threshold value or more. If so, the state of the first switch is switched to the off state. The power supply control device according to any one of claims 1 to 6.

8. The processing unit includes: Instruct the second switch to be switched to an off state; When an instruction to switch the second switch to an off state is issued, The period during which the voltage between both ends of the When the first switch is turned off, the first switch is turned off. The power supply control device according to any one of claims 1 to 7.

9. The processing unit includes: Instruct the second switch to be switched to an off state; When an instruction to switch the second switch to an off state is issued, The period during which the value of the current flowing through the When the value becomes higher than the threshold, the first switch is switched to the off state. The power supply control device according to any one of claims 1 to 8.

10. The processing unit includes: Instruct the second switch to be switched to an off state; When an instruction to switch the second switch to an off state is issued, When a voltage value between both ends of the first switch is less than a predetermined voltage value, the first switch is switched to an off state. Instruct to change The power supply control device according to any one of claims 1 to 9.

11. When an instruction to switch the second switch to an off state is given, the processing unit A voltage value between both ends of a specific switch that is determined in advance among the plurality of second switches is When the voltage is less than the predetermined voltage value, the first switch is instructed to be switched to an off state. The power supply control device according to claim 10.

12. When an instruction to switch the second switch to an off state is given, the processing unit a voltage value between both ends of a second switch different from the specific switch is less than the predetermined voltage value; When the voltage value between both ends of the second switch is less than the predetermined voltage value, This reduces the average current flowing per unit time. The power supply control device according to claim 11.

13. The processing unit includes: Instruct the second switch to be switched to an off state; When an instruction to switch the second switch to an off state is issued, When the current flowing through the first switch exceeds a predetermined current value, the first switch is turned off. Instruct to switch The power supply control device according to any one of claims 1 to 9.

14. When an instruction to switch the second switch to an off state is given, the processing unit A current value flowing through a predetermined specific switch among the plurality of second switches is When the predetermined current value is exceeded, the first switch is instructed to be switched to an off state. The power supply control device according to claim 13.

15. When an instruction to switch the second switch to an off state is given, the processing unit When the current value flowing through the second switch, which is different from the specific switch, exceeds the predetermined current value, When the current exceeds the predetermined current value, a second switch different from the second switch through which the current exceeds the predetermined current value flows is selected. Reduce the average current flowing per unit time through the switch. The power supply control device according to claim 14.

16. The states of the second switches to which the current is input from the first switch are defined as an off state, or a step of transitioning to a flow-through state in which flow is being performed; adjusting an average value of a current flowing per unit time for at least one second switch in response to the one or more second switches in the conducting state, so that an average value of a current flowing per unit time through the first switch is made less than a current value flowing through the first switch when the states of the first switch and all the second switches are fixed to an on state; The computer executes the power supply control method.

17. The state of each of the plurality of second switches to which a current is input from the first switch is an off state, or a step of transitioning to a flow-through state in which flow is being performed; adjusting an average value of a current flowing per unit time for at least one second switch in response to the one or more second switches in a conducting state; a step of switching the state of the first switch to an off state by a switching circuit which switches the state of the first switch to an on state or an off state, when a value of a current flowing through the first switch becomes equal to or greater than a current threshold value; The computer executes The switching circuit is connected to a current output circuit that detects a value of a current flowing through the first switch. Power supply control method.

18. The state of each of the plurality of second switches to which a current is input from the first switch is an off state, or a step of transitioning to a flow-through state in which flow is being performed; adjusting an average value of a current flowing per unit time for at least one second switch in response to the one or more second switches in a conducting state; instructing the second switch to be switched to an off state; instructing to switch the first switch to the off state when a voltage value between both ends of a specific switch, which is determined in advance among the plurality of second switches, is less than the predetermined voltage value when an instruction to switch the second switch to the off state has been issued; The computer executes The specific switch is a second switch connected to a load that may cause a disruption to the operation of a vehicle in which the first switch is installed. Power supply control method.

19. The state of each of the plurality of second switches to which a current is input from the first switch is an off state, or a step of transitioning to a flow-through state in which flow is being performed; adjusting an average value of a current flowing per unit time for at least one second switch in response to the one or more second switches in a conducting state; instructing the second switch to be switched to an off state; instructing to switch the first switch to the off state when a current value flowing through a specific switch, which is predetermined among the plurality of second switches, exceeds the predetermined current value in a case where a command to switch the second switch to the off state has been issued; The computer executes The specific switch is a second switch connected to a load that may cause a disruption to the operation of a vehicle in which the first switch is installed. Power supply control method.

20. The states of the second switches to which the current is input from the first switch are defined as an off state, or a step of transitioning to a flow-through state in which flow is being performed; For at least one second switch, an average value of a current flowing per unit time is calculated based on the average value of the current flowing per unit time. adjusting the current flowing through the first switch per unit time in response to the one or more second switches being in a conducting state, so as to make the average value of the current flowing through the first switch less than the value of the current flowing through the first switch when the states of the first switch and all the second switches are fixed to an on state; A computer program for causing a computer to execute the above.

21. The state of each of the plurality of second switches to which a current is input from the first switch is an off state, or a step of transitioning to a flow-through state in which flow is being performed; For at least one second switch, an average value of a current flowing per unit time is calculated based on the average value of the current flowing per unit time. adjusting in response to the one or more second switches being in a conducting state; a step of switching the state of the first switch to an off state by a switching circuit which switches the state of the first switch to an on state or an off state, when a value of a current flowing through the first switch becomes equal to or greater than a current threshold value; A computer program for causing a computer to execute the following: The switching circuit is connected to a current output circuit that detects a value of a current flowing through the first switch. Computer program.

22. The state of each of the plurality of second switches to which a current is input from the first switch is an off state, or a step of transitioning to a flow-through state in which flow is being performed; For at least one second switch, an average value of a current flowing per unit time is calculated based on the average value of the current flowing per unit time. adjusting in response to the one or more second switches being in a conducting state; instructing the second switch to be switched to an off state; instructing to switch the first switch to the off state when a voltage value between both ends of a specific switch, which is determined in advance among the plurality of second switches, is less than the predetermined voltage value when an instruction to switch the second switch to the off state has been issued; A computer program for causing a computer to execute the following: The specific switch is a second switch connected to a load that may cause a disruption to the operation of a vehicle in which the first switch is installed. Computer program.

23. The state of each of the plurality of second switches to which a current is input from the first switch is an off state, or a step of transitioning to a flow-through state in which flow is being performed; For at least one second switch, an average value of a current flowing per unit time is calculated based on the average value of the current flowing per unit time. adjusting in response to the one or more second switches being in a conducting state; instructing the second switch to be switched to an off state; instructing to switch the first switch to the off state when a current value flowing through a specific switch, which is predetermined among the plurality of second switches, exceeds the predetermined current value in a case where a command to switch the second switch to the off state has been issued; A computer program for causing a computer to execute the following: The specific switch is a second switch connected to a load that may cause a disruption to the operation of a vehicle in which the first switch is installed. Computer program.

Images