Processing device

Abstract

To provide a technique capable of automatically determining a current cutoff threshold value suitable for an electric wire.SOLUTION: A processing device according to the present invention includes: an acquisition unit 42 configured to acquire a value of a current flowing through an electric wire provided in a vehicle; and a determination unit 44 configured to determine a cutoff threshold value of the current related to the electric wire based on the current value acquired by the acquisition unit 42.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a processing device. [Background technology]

[0002] Patent Document 1 discloses a DC system breaker equipped with a power semiconductor element. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2022-511891 Summary of the Invention [Problem to be solved by the invention]

[0004] Vehicles such as automobiles are equipped with numerous electrical loads that receive power from an onboard power supply. The power from the power supply is supplied to each load via a different electric wire. Each electric wire is equipped with a semiconductor switch that can cut off the power supply to the wire, and a current detection unit that detects the current flowing through the wire. When the current value of a certain electric wire is equal to or greater than the cutoff threshold, a microcomputer controls the corresponding semiconductor switch to a non-conducting state, thereby protecting the wire from overcurrent.

[0005] The wire diameter is designed based on the current consumption of the connected load. The smoke generation characteristics of the wire vary depending on the wire diameter, and the larger the wire diameter, the higher the cutoff threshold. Therefore, the microcomputer software is used to set the cutoff threshold for each of the multiple wires according to their wire diameter.

[0006] For products with different wire diameters depending on the vehicle model and load, the cutoff thresholds set in the software must also be different. This increases the number of microcontroller product variations and the need to use different manufacturing factories. In addition, changing software settings increases the number of verification steps, increasing the amount of work required for development.

[0007] An object of the present invention is to provide a technique that can automatically determine a current interruption threshold suitable for an electric wire. [Means for solving the problem]

[0008] In order to solve the above problem, a processing device of one embodiment of the present invention includes an acquisition unit that acquires the value of the current flowing in an electric wire installed in a vehicle, and a determination unit that determines the current interruption threshold for the electric wire based on the current value acquired by the acquisition unit. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a technique that can automatically determine a current interruption threshold suitable for an electric wire. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a diagram illustrating a schematic configuration of a power supply system according to an embodiment. [Figure 2] 10 is a diagram showing the correspondence relationship between the current value of an in-vehicle load, the cross-sectional area of a conductor of an electric wire, and the interruption threshold value. FIG. [Figure 3] 3(a) to 3(d) are diagrams for explaining a method for obtaining a current value in the first determination process of the cut-off threshold value. [Figure 4] 10 is a flowchart showing a first process for determining a cut-off threshold value. [Figure 5] FIG. 10 is a diagram illustrating a configuration during execution of a second process for determining a shutdown threshold in the power supply system according to the embodiment. [Figure 6] 6(a) and 6(b) are diagrams for explaining a method of acquiring a current value in the second determination process of the cut-off threshold value. DETAILED DESCRIPTION OF THE INVENTION

[0011] FIG. 1 shows a schematic configuration of a power supply system 1 according to an embodiment. The power supply system 1 is mounted on a vehicle (not shown) and supplies power to various electrical loads. The vehicle may be a vehicle that uses only an internal combustion engine as a driving force source, or may be an electrically powered vehicle that uses an electric motor as a driving force source. Examples of electrically powered vehicles include battery electric vehicles (BEVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and fuel cell electric vehicles (FCEVs). The vehicle may be a vehicle driven by a driver or an autonomous vehicle.

[0012] 1, the power supply system 1 includes a power supply unit 10, an ECU (Electronic Control Unit) 12, a first electric wire 14a, a second electric wire 14b, a first vehicle load 16a, and a second vehicle load 16b. The ECU 12 includes a switch unit 20 and a processing unit 22. The ECU 12 can also be called a switch device.

[0013] 1 shows the first electric wire 14a, the second electric wire 14b, the first vehicle-mounted load 16a, and the second vehicle-mounted load 16b, but the power supply system 1 includes many more electric wires and vehicle-mounted loads that are not shown. Hereinafter, where appropriate, the plurality of electric wires including the first electric wire 14a and the second electric wire 14b will be collectively referred to as electric wires 14. Where appropriate, the plurality of vehicle-mounted loads including the first vehicle-mounted load 16a and the second vehicle-mounted load 16b will be collectively referred to as vehicle load 16.

[0014] The power supply unit 10 supplies power to a plurality of on-vehicle loads 16 via a switch unit 20 and a plurality of electric wires 14. The power supply unit 10 includes, for example, an auxiliary battery (not shown) that is a rechargeable secondary battery. The power supply unit 10 can output power stored in the auxiliary battery. Various known configurations can be used for the power supply unit 10.

[0015] The switch unit 20 can individually control whether or not to supply power from the power supply unit 10 to each of the multiple vehicle loads 16. The switch unit 20 has a first semiconductor switch 30a, a second semiconductor switch 30b, a first current detection unit 32a, and a second current detection unit 32b. The switch unit 20 has more semiconductor switches and current detection units (not shown). Hereinafter, the multiple semiconductor switches including the first semiconductor switch 30a and the second semiconductor switch 30b will be collectively referred to as semiconductor switches 30, as appropriate. Furthermore, the multiple current detection units including the first current detection unit 32a and the second current detection unit 32b will be collectively referred to as current detection units 32, as appropriate. The vehicle loads 16, electric wires 14, semiconductor switches 30, and current detection units 32 may be provided in equal numbers.

[0016] Each of the plurality of semiconductor switches 30 is, for example, a MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor), and has one end to which output power from the power supply unit 10 is supplied, the other end electrically connected to one end of the corresponding current detection unit 32, and a control terminal to which a control signal is supplied from the processing unit 22. The semiconductor switches 30 can also be called semiconductor fuses.

[0017] For example, the first semiconductor switch 30a has one end to which the output power of the power supply unit 10 is supplied, the other end electrically connected to one end of the corresponding first current detection unit 32a, and a control terminal to which a control signal is supplied from the processing unit 22.

[0018] The current detection unit 32 is a current sensor. The other end of each of the multiple current detection units 32 is electrically connected to one end of a corresponding electric wire 14. The other end of the electric wire 14 is electrically connected to a corresponding in-vehicle load 16. Each of the multiple current detection units 32 detects a current flowing from the power supply unit 10 to the corresponding in-vehicle load 16 via the corresponding electric wire 14, and supplies information on the detected current value to the processing unit 22.

[0019] For example, the other end of the first current detection unit 32a is electrically connected to one end of the first electric wire 14a. The other end of the first electric wire 14a is electrically connected to the first vehicle-mounted load 16a. The first current detection unit 32a detects the current flowing from the power supply unit 10 to the first vehicle-mounted load 16a via the first electric wire 14a, and supplies information on the detected current value to the processing unit 22.

[0020] The other end of the second current detection unit 32b is electrically connected to one end of the second electric wire 14b. The other end of the second electric wire 14b is electrically connected to the second vehicle load 16b. The second current detection unit 32b detects the current flowing from the power supply unit 10 to the second vehicle load 16b via the second electric wire 14b, and supplies information on the detected current value to the processing unit 22.

[0021] The multiple on-vehicle loads 16 are electrical loads provided in the vehicle. The multiple on-vehicle loads 16 may include, for example, headlamps, a navigation system, an audio system, an air conditioner, various ECUs, etc. The on-vehicle loads 16 operate using power supplied from the power supply unit 10.

[0022] The processing unit 22 controls the switch unit 20. The processing unit 22 has a storage unit 40, an acquisition unit 42, a decision unit 44, and a control unit 46. The configuration of the processing unit 22 can be realized in hardware by the CPU, memory, or other LSI of any computer, and in software by a program loaded into memory, but here, functional blocks realized by the cooperation of these are depicted. Therefore, those skilled in the art will understand that these functional blocks can be realized in various forms by hardware alone, software alone, or a combination of both. The processing unit 22 can be configured, for example, by a microcomputer. The processing unit 22 can also be called a processing device.

[0023] In response to a power supply instruction from another ECU (not shown) or the like, the control unit 46 switches the semiconductor switch 30 corresponding to the vehicle load 16 specified in the power supply instruction from a non-conductive state to a conductive state, and supplies power from the power supply unit 10 to the vehicle load 16.

[0024] When a predetermined first time period has elapsed while the current flowing through the electric wire 14 detected by the current detection unit 32 is equal to or greater than the corresponding cutoff threshold, the control unit 46 controls the switch unit 20 to cut off the current flowing from the power supply unit 10 to the corresponding on-board load 16. The first time period may be, for example, a few seconds or less, and can be determined appropriately through experiments or simulations. This makes it possible to protect the electric wire 14 through which a current equal to or greater than the cutoff threshold flows.

[0025] For example, when a first time period has elapsed while the current flowing through the first electric wire 14a detected by the first current detection unit 32a is equal to or greater than the first cut-off threshold, the control unit 46 controls the first semiconductor switch 30a to cut off the current flowing from the power supply unit 10 to the first in-vehicle load 16a. In this case, the control unit 46 controls the control voltage supplied to the control terminal of the first semiconductor switch 30a to switch the first semiconductor switch 30a from a conductive state to a non-conductive state, thereby preventing current from flowing through the first semiconductor switch 30a.

[0026] The interruption threshold is determined for each electric wire 14. The larger the cross-sectional area of the conductor of the electric wire 14, i.e., the thicker the conductor of the electric wire 14, the larger the interruption threshold is determined. The interruption threshold is determined to a value that can suppress smoking of the electric wire 14.

[0027] As will be explained below, the plurality of interruption thresholds for the plurality of electric wires 14 are automatically determined by the ECU 12 at the vehicle manufacturing plant or dealership before the vehicle is sold to a user, and are stored in the control unit 46.

[0028] At a vehicle manufacturing plant or dealership, an external terminal device such as a personal computer (not shown) is connected to the ECU 12. When an instruction to determine the cutoff threshold is received from the terminal device operated by an operator, the processing unit 22 starts a first process for determining the cutoff threshold, which will be described below.

[0029] The storage unit 40 stores information indicating the correspondence between the current value of the vehicle load 16 and the interruption threshold value in advance as a table.

[0030] 2 shows the correspondence relationship between the current value of the vehicle load 16, the cross-sectional area of the conductor of the electric wire 14, and the interruption threshold value. This correspondence relationship is created in advance based on the characteristics of the electric wire 14. Although FIG. 2 shows an example of numerical values to facilitate understanding of the explanation, the numerical values are not limited to these examples.

[0031] In the example of FIG. 2, when the current value of the vehicle load 16 is equal to or greater than 1 (A) and less than 3 (A), the cross-sectional area of the conductor of the electric wire 14 is 0.5 (sq) and the interruption threshold is 10 (A).

[0032] When the current value is equal to or greater than 3 (A) and less than 7 (A), the cross-sectional area of the conductor of the electric wire 14 is 1 (sq), and the interruption threshold is 20 (A).

[0033] When the current value is equal to or greater than 7 (A) and less than 15 (A), the cross-sectional area of the conductor of the electric wire 14 is 2 (sq), and the interruption threshold is 30 (A).

[0034] When the current value is equal to or greater than 15 (A) and less than 25 (A), the cross-sectional area of the conductor of the electric wire 14 is 3 (sq), and the interruption threshold is 40 (A).

[0035] The correspondence relationship does not have to include information about the cross-sectional area of the conductor of the electric wire 14. Furthermore, since the resistance value of the electric wire 14 changes depending on the temperature, the holding unit 40 may hold information about the correspondence relationship for each temperature. Furthermore, since the current value changes depending on the voltage output from the power supply unit 10, the holding unit 40 may hold information about the correspondence relationship for each voltage.

[0036] The cross-sectional area of the conductor of each of the multiple electric wires 14 is predetermined according to the value of the current flowing through the vehicle-mounted load 16 connected to the electric wire 14. In other words, the electric wire 14 having a cross-sectional area of the conductor that matches the value of the current flowing through the vehicle-mounted load 16 is connected to the vehicle-mounted load 16.

[0037] For example, when the current flowing through the first vehicle load 16a is 6 (A), the cross-sectional area of the conductor of the first electric wire 14a is 1 (sq) according to the above correspondence relationship.

[0038] Furthermore, when the current flowing through the second vehicle load 16b is 2 (A), the cross-sectional area of the conductor of the second electric wire 14b is 0.5 (sq) according to the above correspondence relationship.

[0039] Before the process of determining the shutoff thresholds is started, the initial values of the respective shutoff thresholds are preset to, for example, the minimum values corresponding to the smallest cross-sectional areas of the conductors of the electric wires 14. In the example of FIG. 2, the initial value of the shutoff threshold is set to 10 (A).

[0040] When the processing unit 22 receives an instruction to start the process of determining the shut-off threshold, the control unit 46 controls each of the semiconductor switches 30 to a conductive state for a predetermined second time period, thereby energizing each of the vehicle loads 16. The control unit 46 may energize the vehicle loads 16 one by one, or may energize several vehicle loads 16 at a time.

[0041] The acquisition unit 42 acquires the value of the current flowing through each of the plurality of electric wires 14 detected by each of the plurality of current detection units 32, and supplies information on the acquired current value to the determination unit 44.

[0042] 3(a) to 3(d) are diagrams for explaining a method for acquiring a current value in the first determination process of the shutoff threshold. Fig. 3(a) shows an example of the relationship between time and the control voltage applied to the control terminal of the semiconductor switch 30. Fig. 3(b) shows an example of the relationship between time and the current flowing through the electric wire 14, corresponding to Fig. 3(a).

[0043] As shown in Figures 3(a) and (b), at time t1, the control unit 46 applies a control voltage to the control terminal of the semiconductor switch 30, causing the semiconductor switch 30 to conduct, turning on the vehicle load 16, and starting current flow through the vehicle load 16 and the electric wire 14.

[0044] After time t1, an inrush current flows, and then the acquisition unit 42 acquires the current value between time t2 and time t3, when the current stabilizes to a substantially constant value. The acquisition unit 42 acquires the current value, for example, between time t2 and time t3, at a time when a predetermined third time has elapsed since time t1. This allows a stable current value to be acquired even in the in-vehicle load 16 in which an inrush current temporarily occurs. The third time can be determined as appropriate through experiments or simulations.

[0045] At time t4, a second time period after time t1, the control unit 46 stops applying the control voltage to the control terminal of the semiconductor switch 30, causing the semiconductor switch 30 to become non-conductive, turning off the vehicle load 16, and cutting off the current.

[0046] The second time period from time t1 to time t4 is shorter than the first time period, which prevents the semiconductor switch 30 from being turned off before the current value is acquired when the current value is greater than the initial value of the turn-off threshold.

[0047] Moreover, since the power is supplied to the in-vehicle load 16 only during the second time period, it is possible to reduce power consumption and also reduce heat generation in the electric wire 14 and the in-vehicle load 16. The second time period can be determined appropriately through experiments or simulations.

[0048] The determination unit 44 determines a shutoff threshold for each of the plurality of electric wires 14 based on the current value of the electric wire 14 acquired by the acquisition unit 42 and the correspondence relationship stored in the storage unit 40. The determination unit 44 supplies the determined shutoff threshold for each of the plurality of electric wires 14 to the control unit 46.

[0049] For example, if the current value of the first electric wire 14a acquired by the acquisition unit 42 is 6 (A), the shutoff threshold value associated with 3 (A) or more and less than 7 (A) in the correspondence relationship is 20 (A), so the determination unit 44 determines the first shutoff threshold value for the first electric wire 14a to be 20 (A).

[0050] Furthermore, when the current of the second electric wire 14b acquired by the acquisition unit 42 is 2 (A), the shutoff threshold associated with 1 (A) or more and less than 3 (A) is 10 (A), so the determination unit 44 determines the second shutoff threshold for the second electric wire 14b to be 10 (A).

[0051] If the storage unit 40 stores information on the correspondence relationship for each temperature, the determination unit 44 may determine the cutoff threshold based on the correspondence relationship corresponding to the temperature detected by a temperature sensor (not shown). If the storage unit 40 stores information on the correspondence relationship for each voltage, the determination unit 44 may determine the cutoff threshold based on the correspondence relationship corresponding to the output voltage of the power supply unit 10 detected by a voltage sensor (not shown). This improves the accuracy of determining the cutoff threshold. These methods may also be combined.

[0052] The control unit 46 holds the interruption threshold value for each of the plurality of electric wires 14 determined by the determination unit 44. This completes the process of determining the interruption threshold value.

[0053] After the process of determining the cut-off threshold is completed, the acquisition unit 42 periodically acquires the value of the current flowing through each of the multiple electric wires 14 detected by each of the multiple current detection units 32, and supplies information on the acquired current value to the control unit 46. When a first time period has elapsed while the current value of each of the multiple electric wires 14 acquired by the acquisition unit 42 is equal to or greater than the held cut-off threshold for that electric wire 14, the control unit 46 controls the switch unit 20 to cut off the current flowing through that electric wire 14.

[0054] In this way, since the tripping threshold is determined based on the current flowing through the electric wire 14 and the corresponding relationship, the tripping threshold suitable for the electric wire 14 can be automatically determined, thereby reducing the labor required of developers, etc. Since it is only necessary to energize the on-board load 16 and detect the current flowing through the on-board load 16, the tripping threshold can be set easily in a relatively short time.

[0055] Furthermore, during development, developers do not need to change the interruption threshold set in the software for products in which the cross-sectional area of the conductor of the electric wire 14 varies depending on the vehicle model and the on-board load 16. This eliminates the need to increase the product variations of the microcontroller, making product management easier. It also reduces the amount of verification work required due to changes in software settings, reducing the amount of effort required for development.

[0056] In addition, there is no need to add a component for detecting current to the existing power supply system, since the current can be detected using the existing current detection unit 32. Furthermore, by executing the process for determining the cutoff threshold at the vehicle manufacturing factory or dealer, it is possible to make the system less susceptible to environmental changes such as temperature.

[0057] After the vehicle is sold to a user, a vehicle dealer or the like may replace one of the on-board loads 16 with one that consumes a larger current due to a hardware update or the like, and accordingly, the corresponding electric wire 14 may also be replaced with one having a conductor with a larger cross-sectional area. In this case, the multiple interruption thresholds are automatically reset as follows.

[0058] At a vehicle manufacturing factory or dealership, a terminal device is connected to the ECU 12, and when an instruction to determine the cutoff threshold is received from the terminal device, the processing unit 22 starts the above-described process of determining the cutoff threshold again.

[0059] For example, if the first vehicle load 16a is changed to one with a larger current consumption and the first electric wire 14a is changed to one with a conductor having a larger cross-sectional area, the first tripping threshold is changed to a larger value by the tripping threshold determination process.

[0060] In this way, even if the in-vehicle load 16 and the electric wire 14 are changed, there is no need to replace the ECU 12, so the effort and cost required for updating the hardware can be reduced.

[0061] The current value may be obtained by a method other than that shown in Figures 3(a) and 3(b). In the following description, it is assumed that the vehicle load 16 does not have an inrush current.

[0062] Fig. 3(c) shows another example of the relationship between time and the control voltage applied to the control terminal of the semiconductor switch 30. Fig. 3(d) shows an example of the relationship between time and the current flowing through the electric wire 14, corresponding to Fig. 3(c).

[0063] As shown in FIGS. 3(c) and 3(d), the control unit 46 alternately switches the semiconductor switch 30 between a conductive state and a non-conductive state at a predetermined cycle during a predetermined fourth time period from time t11 to time t12. The fourth time period can be determined as appropriate through experimentation or simulation. The period during which the semiconductor switch 30 is in a conductive state is shorter than the first time period. The acquisition unit 42 acquires current values at multiple times between time t11 and time t12, averages the acquired current values, and acquires an average current value I1. In this acquisition method, the average current value is also used as the current value of the in-vehicle load 16 in the correspondence relationship. This acquisition method can reduce power consumption even for in-vehicle loads 16 with relatively large current consumption.

[0064] 4 is a flowchart showing a first process for determining the interruption threshold value. The storage unit 40 stores information indicating the correspondence between a given current value and the interruption threshold value (S10), and the control unit 46 stores an initial value of the interruption threshold value corresponding to the given electric wire 14 having the smallest cross-sectional area conductor (S12).

[0065] When an instruction to determine the tripping threshold is received at a vehicle manufacturing plant or the like, the control unit 46 energizes the in-vehicle loads 16 (S14), the acquisition unit 42 acquires the current value of the electric wire 14 (S16), the determination unit 44 determines the tripping threshold based on the acquired current value and the correspondence relationship (S18), and the process ends. The processes from S14 to S18 are executed for each of the multiple in-vehicle loads 16. When the instruction to determine the tripping threshold is received again, for example, when the in-vehicle loads 16 or the electric wire 14 is changed, the processes from S14 to S18 are executed again for each of the multiple in-vehicle loads 16.

[0066] In the above description, the cross-sectional area of the conductor of the electric wire 14 is predetermined according to the current flowing through the vehicle-mounted load 16 connected to the electric wire 14. However, this is not limiting. The cross-sectional area of the conductor of the electric wire 14 may be set larger than the cross-sectional area according to the current flowing through the connected vehicle-mounted load 16. For example, if the current flowing through the second vehicle-mounted load 16b is 2 (A), the cross-sectional area of the conductor of the second electric wire 14b may be set to 1 (sq) instead of 0.5 (sq). If the current flowing through another vehicle-mounted load 16 is 2 (A), the cross-sectional area of the conductor of the electric wire 14 connected to this vehicle-mounted load 16 may be set to 2 (sq), instead of 0.5 (sq). In this example, since multiple tripping thresholds exist for a certain range of current values, the first determination process described above cannot set an appropriate tripping threshold. Therefore, the second determination process described below is executed. The following description will focus on differences from the first determination process.

[0067] 5 shows a configuration of the power supply system 1 according to the embodiment during execution of the second determination process of the shutoff threshold. As shown in FIG. 5, when the second determination process is executed at a vehicle manufacturing plant or dealership, an operator detaches the first vehicle-mounted load 16a from the first electric wire 14a and connects the first measurement load 70a to the first electric wire 14a in place of the first vehicle-mounted load 16a. The second vehicle-mounted load 16b is detached from the second electric wire 14b and connects the second measurement load 70b to the second electric wire 14b in place of the first vehicle-mounted load 16b. A measurement load 70 is connected to each of the multiple electric wires 14 in place of the vehicle-mounted load 16. The electric wires 14 and the vehicle-mounted loads 16, and the electric wires 14 and the measurement loads 70 can be attached and detached using, for example, connectors.

[0068] Each of the multiple measurement loads 70 has a measurement resistor 72 with one end grounded. The measurement resistor 72 has a reference resistance value. The first measurement load 70a has a first measurement resistor 72a. The second measurement load 70b has a second measurement resistor 72b. Each of the multiple electric wires 14 has a reference length L1.

[0069] The correspondence relationship between the current value, the cross-sectional area of the conductor of the electric wire 14, and the interruption threshold value, which is held in the holding unit 40, is created in advance based on the output voltage of the power supply unit 10, the characteristics of the electric wire 14, the reference length L1, and the reference resistance value. Specifically, the correspondence relationship is created based on the current that flows from the reference electric wire of the reference length L1 to the reference resistor of the reference resistance value when the output voltage of the power supply unit 10 is applied, and the cross-sectional area of the conductor of the reference electric wire.

[0070] Since a constant voltage is applied to a series circuit consisting of a reference wire of a reference length L1 and a reference resistor of a reference resistance value, the current value is determined depending on the cross-sectional area of the conductor of the reference wire. Therefore, for each cross-sectional area of the conductors of multiple reference wires, a current value determined by the cross-sectional area of the conductor of the reference wire and a breaking threshold value corresponding to that reference wire are associated.

[0071] For example, in the correspondence relationship, when the current value is i1 (A), the cross-sectional area of the conductor of the electric wire 14 is 0.5 (sq), and the interruption threshold value is 10 (A).

[0072] When the current value is i2 (A), the cross-sectional area of the conductor of the electric wire 14 is 1 (sq), and the interruption threshold is 20 (A).

[0073] When the current value is i3 (A), the cross-sectional area of the conductor of the electric wire 14 is 2 (sq), and the interruption threshold is 30 (A).

[0074] When the current value is i4 (A), the cross-sectional area of the conductor of the electric wire 14 is 3 (sq), and the interruption threshold is 40 (A).

[0075] i1 to i4 are determined depending on the output voltage of power supply unit 10 and the like, and may have a certain range. Note that the correspondence relationship does not necessarily include information about the cross-sectional area of the conductor of electric wire 14.

[0076] When receiving an instruction to determine the cut-off threshold from the terminal device, the processing unit 22 starts the second determination process described below.

[0077] The control unit 46 controls each of the semiconductor switches 30 to be in a conductive state for a second time period, thereby energizing each of the measurement loads 70.

[0078] The acquisition unit 42 acquires, for each of the multiple electric wires 14, the current value flowing from the electric wire 14 to the measurement resistor 72 when the vehicle load 16 connected to the electric wire 14 is replaced with the measurement resistor 72, and supplies information on the acquired current value to the determination unit 44.

[0079] 6(a) and 6(b) are diagrams for explaining a method for acquiring a current value in the second determination process of the shutoff threshold. Fig. 6(a) shows an example of the relationship between time and the control voltage applied to the control terminal of the semiconductor switch 30. Fig. 6(b) shows an example of the relationship between time and the current flowing through the electric wire 14, corresponding to Fig. 6(a).

[0080] As shown in FIGS. 6(a) and 6(b), at time t21, the control unit 46 applies a control voltage to the control terminal of the semiconductor switch 30, causing the semiconductor switch 30 to become conductive and current to flow through the measurement load 70 and the electric wire 14.

[0081] At time t22, when the second time period has elapsed since time t21, control unit 46 stops applying the control voltage to the control terminal of semiconductor switch 30, causing semiconductor switch 30 to become non-conductive and cutting off the current.

[0082] Since the measurement load 70 is a resistor and no inrush current flows, the acquisition unit 42 acquires the current value at a predetermined timing during the second time period from time t21 to time t22. The second time period may be shorter than the second time periods in the examples of FIGS. 3(a) and 3(b).

[0083] The determination unit 44 determines the interruption threshold for each of the multiple electric wires 14 based on the current value of the electric wire 14 acquired by the acquisition unit 42 and the correspondence relationship stored in the storage unit 40. This processing corresponds to the determination unit 44 determining the interruption threshold for each of the multiple electric wires 14 based on the current value of the electric wire 14 acquired by the acquisition unit 42, the reference length L1, and the reference resistance value.

[0084] For example, when the current of the first electric wire 14a acquired by the acquisition unit 42 is i2 (A), the interruption threshold value associated with i2 (A) in the correspondence relationship is 20 (A), and therefore the determination unit 44 determines the first interruption threshold value for the first electric wire 14a to be 20 (A). In this case, it is estimated that the cross-sectional area of the conductor of the first electric wire 14a is 1 (sq).

[0085] Furthermore, when the current of the second electric wire 14b acquired by the acquisition unit 42 is i4 (A), the interruption threshold value associated with i4 (A) is 40 (A), and therefore the determination unit 44 determines the second interruption threshold value for the second electric wire 14b to be 40 (A). In this case, it is estimated that the cross-sectional area of the conductor of the second electric wire 14b is 3 (sq).

[0086] As in the first determination process, the storage unit 40 may store information on the correspondence relationship for each temperature, or may store information on the correspondence relationship for each voltage, or these may be combined. In this case, as in the first determination process, the cutoff threshold may be determined using at least one of the temperature detected by the temperature sensor and the output voltage of the power supply unit 10 detected by the voltage sensor.

[0087] When the second determination process is completed, the worker connects the original in-vehicle load 16 in place of the measurement load 70 to each of the multiple electric wires 14. For example, the first measurement load 70a is removed from the first electric wire 14a, and the first in-vehicle load 16a is connected to the first electric wire 14a instead.

[0088] In this way, according to the second determination process, the electric wire 14 is short-circuited to ground via the measurement resistor 72 having the reference resistance value, so that only the influence of differences in the cross-sectional area of the conductor of the electric wire 14 appears in the current value of the electric wire 14. Therefore, even when the electric wire 14 has a cross-sectional area larger than the cross-sectional area of the conductor that matches the current flowing through the on-vehicle load 16, the interruption threshold value can be automatically determined according to the cross-sectional area of the conductor of the electric wire 14.

[0089] As in the first determination process, after a vehicle is sold to a user, if a certain on-board load 16 is replaced with one having a larger current consumption and the corresponding electric wire 14 is also replaced with one having a larger cross-sectional area conductor at a vehicle dealer or the like, the plurality of interruption thresholds are reset in accordance with the instruction to determine the interruption thresholds. In the case of resetting, as described above, an operator connects a measurement load 70 in place of the on-board load 16 to each of the plurality of electric wires 14 in advance.

[0090] In the second determination process, the correspondence relationship may be a correspondence relationship between the cross-sectional area of the conductor of the electric wire 14 and the interruption threshold value. In this case, the determination unit 44 may calculate, for each of the multiple electric wires 14, the cross-sectional area of the conductor of the electric wire 14 based on the current value of the electric wire 14, the resistivity of the conductor of the electric wire 14, the reference length L1, the reference resistance value, and the output voltage of the power supply unit 10, all of which are acquired by the acquisition unit 42. The determination unit 44 may determine, for each of the multiple electric wires 14, the interruption threshold value based on the calculated cross-sectional area of the conductor of the electric wire 14 and the correspondence relationship.

[0091] Also in the second determination process, similarly to the examples shown in FIGS. 3(c) and 3(d), the semiconductor switch 30 may be alternately switched between the conductive state and the non-conductive state to acquire the average current value.

[0092] The present invention has been described above based on the embodiments. However, the embodiments are merely examples, and it will be understood by those skilled in the art that various modifications are possible in the combination of each component and each treatment process, and that such modifications are also within the scope of the present invention.

[0093] For example, in the first determination process, the determination unit 44 may estimate the cross-sectional area of the conductor of each of the multiple electric wires 14 based on the current value of the electric wire 14 and the correspondence relationship stored in the storage unit 40, and determine the interruption threshold value based on the estimated cross-sectional area of the conductor and the correspondence relationship. This modification can improve the degree of freedom in the configuration of the processing unit 22. [Explanation of symbols]

[0094] 1...power supply system, 10...power supply unit, 12...ECU, 14...electric wire, 14a...first electric wire, 14b...second electric wire, 16...vehicle load, 16a...first vehicle load, 16b...second vehicle load, 22...processing unit, 40...holding unit, 42...acquisition unit, 44...determination unit, 46...control unit, 70...measurement load, 70a...first measurement load, 70b...second measurement load, 72...measurement resistor, 72a...first measurement resistor, 72b...second measurement resistor.

Claims

1. an acquisition unit that acquires a value of a current flowing through an electric wire provided in the vehicle; a determination unit that determines a current interruption threshold value for the electric wire based on the current value acquired by the acquisition unit; A processing device comprising:

2. the electric wire is connected to an on-vehicle load, the acquisition unit acquires a value of a current flowing from the electric wire to the vehicle-mounted load; a cross-sectional area of the conductor of the electric wire is predetermined according to a value of a current flowing through the on-vehicle load, the determination unit determines a cutoff threshold value for the electric wire based on the current value acquired by the acquisition unit and a correspondence relationship between the current value and the cutoff threshold value.

2. The processing device according to claim 1.

3. the acquiring unit acquires a value of a current flowing from the electric wire to the measuring resistor in a state where the in-vehicle load connected to the electric wire is replaced with a measuring resistor having a reference resistance value; The wire has a nominal length; the determination unit determines an interruption threshold value for the electric wire based on the current value acquired by the acquisition unit, the reference length, and the reference resistance value.

2. The processing device according to claim 1.

4. the determination unit determines an interruption threshold value for the electric wire based on the current value acquired by the acquisition unit and a correspondence relationship between the current value and an interruption threshold value; The correspondence relationship is created based on a current flowing from a reference electric wire having the reference length to a reference resistor having the reference resistance value and a cross-sectional area of a conductor of the reference electric wire.

4. The processing device according to claim 3.

5. When a determination instruction is received from a terminal device operated by an operator, the determination unit determines a cutoff threshold value; The processing device includes: a control unit that stores the cutoff threshold determined by the determination unit and cuts off the current flowing through the electric wire when the current value of the electric wire acquired by the acquisition unit is equal to or greater than the cutoff threshold; 5. The processing apparatus according to claim 1, wherein the processing apparatus is a processing apparatus for processing a substrate.

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