Processing unit

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 apparatus. [Background Art]

[0002] Patent Document 1 discloses a disconnecting device for a DC system including a power semiconductor element. [Prior Art Literature] [Patent Documents]

[0003] [Patent Document 1] Japanese National Publication of International Patent Application No. 2022-511891 [Summary of the Invention] [Problems to be Solved by the Invention]

[0004] Vehicles such as automobiles are equipped with a large number of electrical loads supplied with electric power from an on-board power source. The power from the power source is supplied via different electric wires for each load. Each electric wire is provided with a semiconductor switch capable of cutting off the power supply from the power source to the electric wire, and a current detection unit that detects a current flowing through the electric wire. When a current value of a certain electric wire is equal to or higher than a cut-off threshold, the microcontroller controls the corresponding semiconductor switch to a non-conductive state, and protects the electric wire from overcurrent.

[0005] The wire diameter is designed based on the current consumption of the connected load. The smoke emission characteristics of an electric wire vary depending on the wire diameter, and the cut-off threshold increases as the wire diameter increases. Therefore, using microcontroller software, a cut-off threshold corresponding to the wire diameter is set for each of a plurality of electric wires.

[0006] For products having different wire diameters depending on the vehicle type and load, the cut-off threshold set in the software also needs to be different. As a result, the number of product variations of microcontrollers increases, making it necessary to use different manufacturing factories. In addition, the number of verification man-hours due to changes in software setting values also increases, leading to an increase in labor required for development.

[0007] The objective of the present invention is to provide a technology that can automatically determine the current interruption threshold appropriate for an electric wire. [Means for solving the problem]

[0008] To solve the above problems, a processing apparatus according to one aspect of the present invention comprises an acquisition unit that acquires the value of the current flowing through an electric wire provided in a vehicle, and a determination unit that determines a current interruption threshold for the electric wire based on the current value acquired by the acquisition unit. With the vehicle load connected to the aforementioned electric wire replaced with a measuring resistor of a reference resistance value, the acquisition unit acquires the current value flowing from the electric wire to the measuring resistor. The electric wire has a reference length. The determination unit determines a break threshold value for the electric wire based on the current value acquired by the acquisition unit, the reference length, and the reference resistance value. [Effects of the Invention]

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

[0010] [Figure 1] This diagram schematically shows the configuration of the power supply system in the embodiment. [Figure 2] This diagram shows the relationship between the current value of the vehicle load, the cross-sectional area of ​​the wire conductor, and the tripping threshold. [Figure 3] Figures 3(a) to 3(d) illustrate the method for obtaining the current value in the first determination process of the cutoff threshold. [Figure 4] This is a flowchart showing the first determination process for the cutoff threshold. [Figure 5] This diagram shows the configuration during the execution of the second determination process for the cutoff threshold in the power supply system of the embodiment. [Figure 6] Figures 6(a) and 6(b) illustrate the method for obtaining the current value in the second determination process of the cutoff threshold. [Modes for carrying out the invention]

[0011] Figure 1 schematically shows the configuration of the power supply system 1 of the 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 the driving force source, or it may be an electric vehicle that uses an electric motor as the driving force source. Examples of electric vehicles include electric vehicles (BEV: Battery Electric Vehicle), hybrid vehicles (HEV: Hybrid Electric Vehicle), plug-in hybrid vehicles (PHEV: Plug-in Hybrid Electric Vehicle), or fuel cell vehicles (FCEV: Fuel Cell Electric Vehicle). The vehicle may be a vehicle driven by a driver, or it may be an autonomous vehicle.

[0012] As shown in Figure 1, the power supply system 1 comprises a power supply unit 10, an ECU (Electronic Control Unit) 12, a first wire 14a, a second wire 14b, a first on-board load 16a, and a second on-board load 16b. The ECU 12 comprises a switch unit 20 and a processing unit 22. The ECU 12 can also be called a switch device.

[0013] Figure 1 shows the first wire 14a, the second wire 14b, the first vehicle load 16a, and the second vehicle load 16b, but the power supply system 1 has more wires and vehicle loads than shown. Hereafter, the multiple wires including the first wire 14a and the second wire 14b will be collectively referred to as wire 14. The multiple vehicle loads including the first vehicle load 16a and the second vehicle load 16b will be collectively referred to as vehicle load 16.

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

[0015] The switch unit 20 is individually capable of controlling whether power is supplied from the power feeding unit 10 to each of the plurality of vehicle-mounted loads 16. The switch unit 20 includes 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 includes more semiconductor switches and current detection units than those illustrated. Hereinafter, the plurality of semiconductor switches including the first semiconductor switch 30a and the second semiconductor switch 30b are collectively referred to as semiconductor switches 30 as appropriate. Further, the plurality of current detection units including the first current detection unit 32a and the second current detection unit 32b are collectively referred to as current detection units 32 as appropriate. The same number of vehicle-mounted loads 16, electric wires 14, semiconductor switches 30, and current detection units 32 may be provided.

[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 feeding unit 10 is supplied, the other end electrically connected to one end of a corresponding current detection unit 32, and a control terminal to which a control signal is supplied from the processing unit 22. The semiconductor switch 30 can also be referred to as a semiconductor fuse.

[0017] For example, the first semiconductor switch 30a has one end to which output power from the power feeding 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 plurality of 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 the corresponding vehicle-mounted load 16. Each of the plurality of current detection units 32 detects a current flowing from the power feeding unit 10 to the corresponding vehicle-mounted load 16 via the corresponding electric wire 14, and supplies information of 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 on-vehicle load 16a. The first current detection unit 32a detects a current flowing from the power supply unit 10 to the first on-vehicle 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 on-vehicle load 16b. The second current detection unit 32b detects a current flowing from the power supply unit 10 to the second on-vehicle load 16b via the second electric wire 14b, and supplies information on the detected current value to the processing unit 22.

[0021] The plurality of on-vehicle loads 16 are electrical loads provided in a vehicle. The plurality of on-vehicle loads 16 may include, for example, headlamps, navigation devices, audio devices, air conditioners, various ECUs, and the like. The on-vehicle loads 16 operate using electric power supplied from the power supply unit 10.

[0022] The processing unit 22 controls the switch unit 20. The processing unit 22 includes a holding unit 40, an acquisition unit 42, a determination unit 44, and a control unit 46. In terms of hardware, the configuration of the processing unit 22 can be implemented by a CPU, a memory, or other LSI of any computer, and in terms of software, it can be implemented by a program loaded into a memory, etc. Here, functional blocks implemented by the cooperation of these components are illustrated. Therefore, it is understood by those skilled in the art that these functional blocks can be implemented in various forms by only hardware, only software, or a combination thereof. The processing unit 22 can be configured by a microcomputer, for example. The processing unit 22 can also be referred to as a processing device.

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

[0024] The control unit 46 controls the switch unit 20 to cut off the current flowing from the power supply unit 10 to the corresponding onboard load 16 when a predetermined first time has elapsed while the current flowing through the wire 14 detected by the current detection unit 32 is equal to or greater than the corresponding cutoff threshold. The first time may be, for example, a few seconds or less, and can be appropriately determined by experiment or simulation. This protects the wire 14 from the current exceeding the cutoff threshold.

[0025] For example, if the current flowing through the first wire 14a detected by the first current detection unit 32a is greater than or equal to the first interruption threshold for a first time, the control unit 46 controls the first semiconductor switch 30a to interrupt the current flowing from the power supply unit 10 to the first on-board 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, so that no current flows through the first semiconductor switch 30a.

[0026] The interruption threshold is determined for each wire 14. The larger the cross-sectional area of ​​the conductor of the wire 14, that is, the thicker the conductor of the wire 14, the higher the interruption threshold is set. The interruption threshold is set to a value that can suppress smoke emission from the wire 14.

[0027] As described below, multiple tripping thresholds for multiple power lines 14 are automatically determined by the ECU 12 at the vehicle manufacturing plant or dealership before the vehicle is sold to the 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 the processing unit 22 receives an instruction to determine a cutoff threshold from the terminal device operated by the worker, it starts the first cutoff threshold determination process shown below.

[0029] The holding unit 40 has in advance stored information in a table that shows the correspondence between the current value of the vehicle load 16 and the cutoff threshold.

[0030] Figure 2 shows the correspondence between the current value of the vehicle load 16, the cross-sectional area of ​​the conductor of the wire 14, and the tripping threshold. This correspondence is created in advance based on the characteristics of the wire 14. Figure 2 includes numerical examples to facilitate understanding of the explanation, but the values ​​are not limited to these examples.

[0031] In the example shown in Figure 2, when the current value of the vehicle load 16 is 1(A) or more and less than 3(A), the cross-sectional area of ​​the conductor of the wire 14 is 0.5(sq), and the tripping threshold is 10(A).

[0032] When the current value is 3(A) or more and less than 7(A), the cross-sectional area of ​​the conductor of wire 14 is 1(sq), and the breaking threshold is 20(A).

[0033] When the current value is 7(A) or more and less than 15(A), the cross-sectional area of ​​the conductor of wire 14 is 2(sq), and the breaking threshold is 30(A).

[0034] When the current value is 15(A) or more and less than 25(A), the cross-sectional area of ​​the conductor of the wire 14 is 3(sq), and the breaking threshold is 40(A).

[0035] Note that the correspondence does not necessarily have to include information on the cross-sectional area of ​​the conductor of the electric wire 14. Also, since the resistance value of the electric wire 14 changes with temperature, the holding unit 40 may hold information on the correspondence for each temperature. Also, since the current value changes with the voltage output from the power supply unit 10, the holding unit 40 may hold information on the correspondence for each voltage.

[0036] For each of the multiple electric wires 14, the cross-sectional area of ​​the conductor is predetermined to match the current value flowing through the vehicle load 16 connected to that electric wire 14. In other words, an electric wire 14 with a cross-sectional area that matches the current value flowing through the vehicle load 16 is connected to the vehicle load 16.

[0037] For example, if the current flowing through the first on-board load 16a is 6(A), then, according to the above correspondence, the cross-sectional area of ​​the conductor of the first wire 14a is 1(sq).

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

[0039] Before the process of determining the interruption threshold is initiated, the initial value of each of the multiple interruption thresholds is pre-set to the smallest value corresponding to the smallest conductor cross-sectional area of ​​the electric wire 14. In the example in Figure 2, the initial value of the interruption threshold is set to 10(A).

[0040] When the processing unit 22 receives an instruction to start the cutoff threshold determination process, the control unit 46 controls each of the multiple semiconductor switches 30 to a conductive state for a predetermined second time, thereby energizing each of the multiple on-board loads 16. The control unit 46 may energize the on-board loads 16 one by one, or it may energize several on-board loads 16 together.

[0041] The acquisition unit 42 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 the acquired current value information to the determination unit 44.

[0042] Figures 3(a) to 3(d) illustrate the method for obtaining the current value in the first determination process of the cutoff threshold. Figure 3(a) shows an example of the relationship between the control voltage applied to the control terminal of the semiconductor switch 30 and time. Figure 3(b) shows an example of the relationship between the current flowing through the wire 14 and time, corresponding to Figure 3(a).

[0043] As shown in Figures 3(a) and 3(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 causing current to begin flowing between the vehicle load 16 and the 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 nearly constant level. The acquisition unit 42 acquires the current value, for example, at a time between time t2 and time t3, after a predetermined third time has elapsed from time t1. This makes it possible to acquire a stable current value even in the on-board load 16 where an inrush current temporarily occurs. The third time can be appropriately determined by experiment or simulation.

[0045] At time t4, two hours after time t1, the control unit 46 stops applying the control voltage to the control terminal of the semiconductor switch 30, the semiconductor switch 30 becomes non-conductive, the onboard load 16 turns off, and the current is cut off.

[0046] The second time period, from time t1 to time t4, is shorter than the first time period. This prevents the semiconductor switch 30 from being shut off before the current value is acquired, even if the current value is greater than the initial value of the cutoff threshold.

[0047] Furthermore, since the vehicle load 16 is energized only during the second period, power consumption can be suppressed, and heat generation in the power lines 14 and the vehicle load 16 can also be suppressed. The second period can be determined as appropriate through experimentation or simulation.

[0048] The determination unit 44 determines a tripping 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 corresponding relationship held in the holding unit 40. The determination unit 44 supplies the determined tripping threshold for each of the multiple electric wires 14 to the control unit 46.

[0049] For example, if the current value of the first wire 14a acquired by the acquisition unit 42 is 6(A), the corresponding tripping threshold for values ​​between 3(A) and 7(A) is 20(A). Therefore, the determination unit 44 determines the first tripping threshold for the first wire 14a to be 20(A).

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

[0051] Furthermore, if the holding unit 40 holds information on the correspondence between temperatures, the determination unit 44 may determine the cutoff threshold based on the correspondence corresponding to the temperature detected by a temperature sensor (not shown). Also, if the holding unit 40 holds information on the correspondence between voltages, the determination unit 44 may determine the cutoff threshold based on the correspondence corresponding to the output voltage of the power supply unit 10 detected by a voltage sensor (not shown). These methods can improve the accuracy of determining the cutoff threshold. These methods may be combined.

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

[0053] After the completion of the process for determining the cutoff threshold, the acquisition unit 42 periodically acquires the current values ​​flowing through each of the multiple electric wires 14 detected by each of the multiple current detection units 32, and supplies the acquired current value information to the control unit 46. For each of the multiple electric wires 14, if the current value of the electric wire 14 acquired by the acquisition unit 42 is equal to or greater than the held cutoff threshold for that electric wire 14 for a first time, the control unit 46 controls the switch unit 20 to cut off the current flowing through that electric wire 14.

[0054] In this way, the tripping threshold is determined based on the current flowing through the wire 14 and its corresponding relationship, so the tripping threshold appropriate for the wire 14 can be automatically determined. Therefore, the effort of developers and others can be reduced. Since it is only necessary to energize the vehicle load 16 and detect the current flowing through the vehicle load 16, the tripping threshold can be set easily and in a relatively short time.

[0055] Furthermore, during development, developers do not need to change the cutoff threshold set in the software for products where the cross-sectional area of ​​the conductor of the electric wire 14 differs depending on the vehicle type and onboard load 16. Therefore, there is no need to increase the product variations of the microcontroller, and product management becomes easier. In addition, the increase in verification man-hours due to changes in software settings can be suppressed, and the effort required for development can be reduced.

[0056] Furthermore, since the current can be detected using the existing current detection unit 32, there is no need to add any additional configurations for current detection to the existing power supply system. In addition, by performing the cutoff threshold determination process at the vehicle manufacturing plant or dealership, the system can be made less susceptible to changes in the environment, such as temperature.

[0057] Here, after the vehicle is sold to the user, a certain onboard load 16 may be replaced with one that consumes a larger current due to a hardware update at the vehicle dealership or other location, and accordingly, the corresponding wire 14 may also be replaced with one that has a larger cross-sectional area conductor. In this case, the multiple tripping thresholds are automatically reset as follows.

[0058] When a terminal device is connected to the ECU12 at a vehicle manufacturing plant or dealership, and the terminal device provides an instruction to determine the cutoff threshold, the processing unit 22 restarts the cutoff threshold determination process described above.

[0059] For example, if we assume that the first on-board load 16a is changed to one with a larger current consumption and the first wire 14a is changed to one with a larger cross-sectional area conductor, the first tripping threshold will be changed to a larger value through the tripping threshold determination process.

[0060] In this way, even if the vehicle load 16 and the wire 14 are changed, there is no need to replace the ECU 12, thus reducing the effort and cost required for hardware updates.

[0061] Note that the current value may be obtained using a method other than those shown in Figures 3(a) and (b). In the following explanation, we will assume an on-board load 16 in which no inrush current flows.

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

[0063] As shown in Figures 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 period from time t11 to time t12. The fourth period can be appropriately determined by experiment or simulation. The period during which the semiconductor switch 30 is conductive is shorter than the first period. The acquisition unit 42 acquires current values ​​at multiple timings between time t11 and time t12, averages the acquired current values, and obtains an average current value I1. In this acquisition method, the average current value is also used for the current value of the vehicle load 16 in the corresponding relationship. According to this acquisition method, power consumption can be suppressed even for a vehicle load 16 with relatively high current consumption.

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

[0065] When a command to determine the tripping threshold is received at a vehicle manufacturing plant or the like, the control unit 46 energizes the vehicle load 16 (S14), the acquisition unit 42 acquires the current value of the wire 14 (S16), and the determination unit 44 determines the tripping threshold based on the acquired current value and its correspondence (S18), and the process is completed. Processes S14 to S18 are performed for each of the multiple vehicle loads 16. When a command to determine the tripping threshold is received again, such as when the vehicle load 16 or the wire 14 is changed, processes S14 to S18 are performed again for each of the multiple vehicle loads 16.

[0066] In the above explanation, the cross-sectional area of ​​the conductor of the electric wire 14 is predetermined to match the current flowing through the vehicle load 16 connected to the electric wire 14, but this is not limited to this. The cross-sectional area of ​​the conductor of the electric wire 14 may be set to be larger than the cross-sectional area that matches the current flowing through the connected vehicle load 16. For example, if 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 may be set to 1(sq) instead of 0.5(sq). If the current flowing through another vehicle load 16 is 2(A), the cross-sectional area of ​​the conductor of the electric wire 14 connected to this vehicle load 16 may be set to 2(sq) instead of 0.5(sq). In this example, since there are multiple tripping thresholds for a certain range of current values, the first decision process described above cannot set an appropriate tripping threshold. Therefore, the second decision process, which will be explained below, is executed. The following explanation will focus on the differences from the first decision process.

[0067] Figure 5 shows the configuration during the execution of the second determination process for the cutoff threshold in the power supply system 1 of the embodiment. As shown in Figure 5, when the second determination process is executed at a vehicle manufacturing plant or dealership, the first on-board load 16a is removed from the first wire 14a by an operator beforehand, and the first measuring load 70a is connected to the first wire 14a instead. The second on-board load 16b is removed from the second wire 14b, and the second measuring load 70b is connected to the second wire 14b instead. For each of the multiple wires 14, a measuring load 70 is connected in place of the on-board load 16. The wires 14 and the on-board load 16, and the wires 14 and the measuring load 70 can be connected and disconnected, for example, by connectors.

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

[0069] The correspondence between the current value, the cross-sectional area of ​​the conductor of the wire 14, and the break threshold value, which are held in the holding unit 40, is predetermined based on the output voltage of the power supply unit 10, the characteristics of the wire 14, the reference length L1, and the reference resistance value. Specifically, the correspondence is determined based on the current flowing from the reference wire of reference length L1 to the reference resistor of 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 wire.

[0070] A constant voltage is applied to a series circuit consisting of a reference wire of standard length L1 and a reference resistor with a standard resistance value. Therefore, the current value depends on the cross-sectional area of ​​the conductor of the reference wire. Consequently, for each of the cross-sectional areas of the conductors of multiple reference wires, a current value determined by the cross-sectional area of ​​that reference wire is associated with the corresponding tripping threshold value for that reference wire.

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

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

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

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

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

[0076] When the terminal device receives an instruction to determine the cutoff threshold, the processing unit 22 starts the second determination process shown below.

[0077] The control unit 46 controls each of the multiple semiconductor switches 30 to a conductive state for a second time, and energizes each of the multiple measuring loads 70.

[0078] The acquisition unit 42 acquires the current value flowing from each of the multiple electric wires 14 to the measuring resistor 72, with respect to the state in which the vehicle load 16 connected to the electric wire 14 has been replaced with the measuring resistor 72, and supplies the acquired current value information to the determination unit 44.

[0079] Figures 6(a) and 6(b) illustrate the method for obtaining the current value in the second determination process of the cutoff threshold. Figure 6(a) shows an example of the relationship between the control voltage applied to the control terminal of the semiconductor switch 30 and time. Figure 6(b) shows an example of the relationship between the current flowing through the wire 14 and time, corresponding to Figure 6(a).

[0080] As shown in Figures 6(a) and (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 conduct and current to flow through the measuring load 70 and the wire 14.

[0081] At time t22, two hours after time t21, the control unit 46 terminates the application of the control voltage to the control terminal of the semiconductor switch 30, causing the semiconductor switch 30 to become non-conductive and interrupting the current.

[0082] Since the measuring 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 period in the examples of Figures 3(a) and (b).

[0083] The determination unit 44 determines a tripping 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 corresponding relationship held in the holding unit 40. This process corresponds to the determination unit 44 determining a tripping 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, a reference length L1, and a reference resistance value.

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

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

[0086] Similar to the first decision process, the holding unit 40 may hold information on the correspondence between temperatures, or information on the correspondence between voltages, or a combination of these. In this case, similar to the first decision 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] Once the second decision process is complete, the operator connects the original vehicle load 16 to each of the multiple wires 14 in place of the measuring load 70. For example, the first measuring load 70a is removed from the first wire 14a, and the first vehicle load 16a is connected to the first wire 14a instead.

[0088] Thus, according to the second determination process, the wire 14 is short-circuited to earth via the reference resistance measuring resistor 72, so only the effect of the difference in the cross-sectional area of ​​the conductor of the wire 14 appears in the current value of the wire 14. Therefore, even when a wire 14 with a cross-sectional area larger than the cross-sectional area of ​​the conductor suitable for the current flowing through the vehicle load 16 is connected, the tripping threshold corresponding to the cross-sectional area of ​​the conductor of the wire 14 can be automatically determined.

[0089] Similar to the first decision process, if, after the vehicle has been sold to a user, a vehicle dealership or similar facility replaces a vehicle-mounted load 16 with one that consumes a larger current, and the corresponding wire 14 is also replaced with one that has a larger cross-sectional area conductor, the multiple tripping thresholds are reset according to the instruction to determine the tripping threshold. In the case of resetting, as described above, the worker has previously connected a measuring load 70 in place of the vehicle-mounted load 16 for each of the multiple wires 14.

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

[0091] Furthermore, in the second decision process, similar to the examples shown in Figures 3(c) and 3(d), the semiconductor switch 30 may be alternately switched between a conductive state and a non-conductive state to obtain the average current value.

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

[0093] For example, in the first decision process, the decision 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 corresponding relationship held in the holding unit 40, and then determine the interruption threshold based on the estimated cross-sectional area of ​​the conductor and the corresponding relationship. This modified example improves 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...Decision 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 the value of the current flowing through the power lines installed on the vehicle, A determination unit determines a current interruption threshold for the electric wire based on the current value acquired by the acquisition unit, Equipped with, With the vehicle load connected to the aforementioned electric wire replaced with a measuring resistor of a reference resistance value, the acquisition unit acquires the current value flowing from the electric wire to the measuring resistor. The aforementioned electric wire has a standard length, The determination unit determines the break threshold value for the electric wire based on the current value obtained by the acquisition unit, the reference length, and the reference resistance value. A processing apparatus characterized by the following:

2. The determination unit determines the tripping threshold for the electric wire based on the current value acquired by the acquisition unit and the correspondence between the current value and the tripping threshold. The aforementioned correspondence is established based on the current flowing from the reference wire of the specified length to the reference resistor of the specified resistance value, and the cross-sectional area of ​​the conductor of the said reference wire. The apparatus according to claim 1.

3. When the decision unit receives a decision instruction from the terminal device operated by the worker, it determines the cutoff threshold, The aforementioned processing apparatus is The control unit further comprises a control unit that holds the cutoff threshold determined by the determination unit and cuts off the current flowing through the electric wire if the current value of the electric wire acquired by the acquisition unit is equal to or greater than the held cutoff threshold. The apparatus according to claim 1 or 2.

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