Abnormality detection device

Abstract

Provided is an abnormality detection device capable of appropriately detecting abnormality in characteristics of resistive elements while suppressing cost, the abnormality detection device being provided with: a plurality of first resistive elements, one ends of which are electrically connected to each other, and the other ends of which are each connected to a load; a second resistive element, one end of which is connected to a power source and the other end of which is electrically connected to a connection node formed by electrically connecting one ends of the first resistive elements to each other; and a control device. The control device has: one or more processors; and one or more memories connected to the processor, the processor executing a process including: a step of deriving a first current value of a current flowing through at least one of the plurality of first resistive elements; a step of deriving a second current value of the current flowing through the second resistive element; and a step for determining whether or not there is a characteristic abnormality in the plurality of first resistive elements on the basis of the comparison result of the first current value and the second current value.

Description

TECHNICAL FIELD

[0001] The present application relates to an abnormality detection device. BACKGROUND

[0002] For example, in Patent Literature 1, a technology of determining abnormality of resistance values of shunt resistors in a current detection circuit is disclosed. In the Patent Literature 1, a plurality of shunt resistors are provided in a circuit, and in a case where there is a current value in the plurality of current values of the shunt resistors whose ratio to an average current value is greater than an abnormality threshold value, it is determined that the resistance value of the shunt resistor corresponding to the current value is abnormal.

[0003] PRIOR ART DOCUMENTS PATENT LITERATURE Patent Literature 1: Japanese Patent Application Publication No. 2021-148511 SUMMARY

[0004] PROBLEMS TO BE SOLVED BY THE INVENTION If a characteristic abnormality occurs in a resistance element functioning as a current sensor, control based on a current value detected by the resistance element cannot be properly performed, and for example, there is a risk that an overcurrent flows in a load connected to the resistance element. Therefore, it is desirable to detect a characteristic abnormality of the resistance element.

[0005] As a method of detecting a characteristic abnormality of a resistance element, for example, it can be listed that, for each first resistance element functioning as a current sensor, an abnormality detection resistance element is connected in series with the first resistance element, and current values of the respective resistance elements are compared. However, in this example, as the number of first resistance elements increases, the same number of abnormality detection resistance elements as the first resistance elements, and an amplification circuit required to derive a current value from a voltage drop of a resistance element are also required. Therefore, in this example, as the number of first resistance elements increases, the cost of the current sensor increases.

[0006] Therefore, an object of the present application is to provide an abnormality detection device capable of suppressing costs and properly detecting a characteristic abnormality of a resistance element.

[0007] TECHNICAL SOLUTION In order to solve the above problem, an abnormality detection device of one embodiment of the present application includes: a plurality of first resistance elements whose one ends are electrically connected to each other and whose other ends are respectively connected to a load; a second resistance element whose one end is connected to a power supply and whose other end is electrically connected to a connection node formed by the one ends of the plurality of first resistance elements being electrically connected to each other; and a control device, the control device has: One or more processors; and One or more memories, which are connected to the processor, The processor performs a process including the following steps: The step of deriving a first current value of the current flowing in at least one of the plurality of first resistive elements; The step of deriving a second current value for the current flowing in the second resistive element; and The step of determining whether the plurality of first resistive elements have abnormal characteristics based on the comparison result of the first current value and the second current value.

[0008] Technical effect According to the present invention, it is possible to suppress costs and to properly detect abnormalities in the characteristics of resistive elements. Attached Figure Description

[0009] Figure 1 This is a schematic diagram showing the configuration of the power supply system including the anomaly detection device of this embodiment.

[0010] Figure 2 This is a flowchart illustrating the operation of the anomaly detection unit.

[0011] Figure 3 This is a flowchart illustrating the operation of the abnormal detection unit in a modified example of actively controlling the switch.

[0012] Symbol Explanation 1. Anomaly Detection Device 18 Load 40 Switches 42 First Resistor Element 44 Second Resistor Element 52 Control device 54 Connecting Nodes 60 processors 62 Memory Detailed Implementation

[0013] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Specific dimensions, materials, values, etc., shown in these embodiments are merely examples to facilitate understanding of the invention and are not intended to limit the invention unless otherwise stated. It should be noted that in this specification and the accompanying drawings, elements having substantially the same function or structure are omitted from repeated description by using the same symbols. Furthermore, elements not directly related to the present invention are omitted from illustration.

[0014] Figure 1is a schematic diagram showing a configuration of a power supply system 2 including the abnormality detection device 1 of the present embodiment. The abnormality detection device 1 and the power supply system 2 are applied to, for example, a vehicle 3. The vehicle 3 is, for example, an electric vehicle equipped with a motor generator as a drive source. Note that the vehicle 3 can also be a hybrid electric vehicle equipped with a motor generator and an engine as drive sources, or an engine vehicle equipped with an engine as a drive source.

[0015] The power supply system 2 is equipped with a battery 10, a fuse box 12, a central unit 14, a plurality of zone units 16a, 16b, a plurality of loads 18a, 18b, 18c, a plurality of downstream electric lines 20a, 20b, 20c, and a notification device 22.

[0016] Hereinafter, for convenience of explanation, the plurality of zone units 16a, 16b will be sometimes collectively referred to as zone units 16. The plurality of loads 18a, 18b, 18c will be sometimes collectively referred to as loads 18. The plurality of downstream electric lines 20a, 20b, 20c will be sometimes collectively referred to as downstream electric lines 20.

[0017] The battery 10 is, for example, a lead storage battery or the like, and is a secondary battery capable of discharging and charging. The battery 10 functions as a power supply that supplies electric power to various auxiliary machines, electronic devices, and the like mounted on the vehicle 3.

[0018] The fuse box 12 houses a plurality of fuses 30a, 30b, 30c. Hereinafter, for convenience of explanation, the plurality of fuses 30a, 30b, 30c will be sometimes collectively referred to as fuses 30.

[0019] A first terminal of two terminals of the fuse 30a is connected to the battery 10. A second terminal of the fuse 30a is connected to the central unit 14. The central unit 14 is electrically connected to the battery 10 through the fuse 30a.

[0020] A first terminal of two terminals of the fuse 30b is connected to the battery 10. A second terminal of the fuse 30b is connected to the zone unit 16a. A first terminal of two terminals of the fuse 30c is connected to the battery 10. A second terminal of the fuse 30c is connected to the zone unit 16b. The zone units 16a, 16b are each electrically connected to the battery 10 through the fuses 30b, 30c.

[0021] In the Figure 1 , two zone units 16a, 16b are exemplified, but the number of zone units 16 is not limited to two, and can be one or more than three. Also, in the Figure 1 , three fuses 30a, 30b, 30c are exemplified, but the number of fuses 30 is not limited to three, and can be more than the total number of central units 14 and zone units 16.

[0022] The central unit 14 is, for example, an electronic control unit (ECU) that centrally controls various devices and electronic control units (ECUs) mounted on the vehicle 3. Although not illustrated, the central unit 14 includes a processor and a memory, and controls each part of the vehicle 3 by causing the processor to execute a program. In addition, the central unit 14 becomes a configuration capable of establishing communication with each of the regional units 16.

[0023] The regional unit 16 is, for example, an electronic control unit (ECU) that is lower in the hierarchy than the central unit 14 in the network architecture. In the present embodiment, the configurations of the plurality of regional units 16 are made the same. In Figure 1 In the present embodiment, the configuration of the regional unit 16a among the plurality of regional units 16 is exemplified for simplicity, and the description of the configurations of the other regional units 16 is omitted.

[0024] The regional unit 16 has a plurality of power supply output ports 32a, 32b, 32c. Hereafter, the power supply output ports 32a, 32b, 32c will sometimes be collectively referred to as power supply output ports 32. In Figure 1 In the present embodiment, an example is shown in which the regional unit 16 has three power supply output ports 32a, 32b, 32c, but the number of power supply output ports 32 is not limited to three, and can be two or more than four as long as it is a plurality.

[0025] The load 18a is electrically connected to the power supply output port 32a of the regional unit 16a through the downstream electric wire 20a. The load 18b is electrically connected to the power supply output port 32b of the regional unit 16a through the downstream electric wire 20b. The load 18c is electrically connected to the power supply output port 32c of the regional unit 16a through the downstream electric wire 20c.

[0026] The load 18 can be, for example, an arbitrary electrical device such as an actuator. In addition, the load 18 can be, for example, an arbitrary electronic device such as an electronic control unit (ECU) that is lower in the hierarchy than the central unit 14 and the regional unit 16 in the network architecture. The loads 18 connected to the regional unit 16 can each be the same kind of device, or can be different kinds of devices. Note that although not illustrated, other loads 18 can be connected to the other regional units 16 through other downstream electric wires 20 in addition to the regional unit 16a.

[0027] The downstream electric wire 20 is an electric wire that electrically connects a predetermined load 18 to the regional unit 16. For example, the downstream electric wire 20 can be an electric wire for electrical installation of the vehicle 3 that has a high heat resistance temperature. The kind and the cross-sectional area of the electric wire of the plurality of downstream electric wires 20 can differ depending on the magnitude of the current required in the load 18 connected to the downstream electric wire 20.

[0028] The notification device 22 is, for example, a warning light of an instrument panel or the like, and is configured to be capable of notifying a rider of the vehicle 3 of a predetermined content.

[0029] The regional unit 16 has, in addition to the power supply output port 32, a plurality of switches 40a, 40b, 40c, a plurality of first resistance elements 42a, 42b, 42c, a second resistance element 44, a plurality of amplification circuits 46a, 46b, 46c, 46d, a communication device 48, a storage device 50, and a control device 52.

[0030] Hereinafter, the plurality of switches 40a, 40b, 40c will be sometimes collectively referred to as the switches 40. The plurality of first resistance elements 42a, 42b, 42c will be sometimes collectively referred to as the first resistance elements 42. The plurality of amplification circuits 46a, 46b, 46c, 46d will be sometimes collectively referred to as the amplification circuits 46. The first resistance elements 42 and the second resistance element 44 will be sometimes simply collectively referred to as the resistance elements.

[0031] In the Figure 1 , three switches 40a, 40b, 40c are exemplified, but the number of the switches 40 is not limited to three, and can be one, two, or more than four. Also, in the Figure 1 , three first resistance elements 42a, 42b, 42c are exemplified, but the number of the first resistance elements 42 is not limited to three, and can be two or more than four, as long as it is plural. The switches 40 are provided in the same number as that of the first resistance elements 42, and in the same number as that of the power supply output ports 32.

[0032] The switches 40 are, for example, semiconductor switches such as MOSFETs (Metal Oxide Semiconductor Field Effect Transistors). The switches 40 are configured to be able to switch between electrical connection and disconnection between two contacts of the switches 40. As will be described later, the control device 52 is able to control the opening and closing of the switches 40.

[0033] A first contact of two contacts of the switch 40a, a first contact of two contacts of the switch 40b, and a first contact of two contacts of the switch 40c are connected to each other.

[0034] The second contact of the two contacts of the switch 40a is connected to the first terminal of the two terminals of the first resistance element 42a. The second terminal of the two terminals of the first resistance element 42a is connected to the power supply output port 32a. The second contact of the two contacts of the switch 40b is connected to the first terminal of the two terminals of the first resistance element 42b. The second terminal of the two terminals of the first resistance element 42b is connected to the power supply output port 32b. The second contact of the two contacts of the switch 40c is connected to the first terminal of the two terminals of the first resistance element 42c. The second terminal of the two terminals of the first resistance element 42c is connected to the power supply output port 32c.

[0035] Thus, each of the plurality of switches 40 corresponds to each of the plurality of first resistance elements 42 one-to-one, and is connected in series with each of the plurality of first resistance elements 42, respectively.

[0036] In the region unit 16, the first contact of the switch 40a, the first contact of the switch 40b, and the first contact of the switch 40c are connected to each other, thereby forming a connection node 54. Thus, one end of each of the plurality of first resistance elements 42 is electrically connected to each other at the connection node 54 via the switches 40. In other words, the connection node 54 is formed by the one end of each of the plurality of first resistance elements 42 being electrically connected to each other via the switches 40.

[0037] The other end of each of the plurality of first resistance elements 42 is connected to the load 18 via the power supply output port 32 and the downstream electric wire 20, respectively.

[0038] The first resistance element 42 is, for example, a shunt resistance. The first resistance element 42 functions as a current sensor that detects a current that flows in the first resistance element 42, in other words, a current that flows in the switch 40, the downstream electric wire 20, and the load 18 connected to the first resistance element 42. The first resistance element 42 detects the current using a voltage drop based on the resistance value of the first resistance element 42. Note that the voltage drop of the first resistance element 42 refers to a voltage between both ends of the first resistance element 42.

[0039] The first terminal of the two terminals of the second resistance element 44 is electrically connected to the battery 10 that functions as a power supply via the fuse 30b. The second terminal of the two terminals of the second resistance element 44 is electrically connected to the connection node 54.

[0040] The second resistance element 44 is, for example, a shunt resistance. The second resistance element 44 functions as a current sensor that detects a current that flows in the second resistance element 44. The second resistance element 44 detects the current using a voltage drop based on the resistance value of the second resistance element 44. Note that the voltage drop of the second resistance element 44 refers to a voltage between both ends of the second resistance element 44.

[0041] Hereinafter, the current value of the current flowing through the first resistance element 42, in other words, the current value detected by the first resistance element 42, will be referred to as a first current value. The current value of the current flowing through the second resistance element 44, in other words, the current value detected by the second resistance element 44, will be referred to as a second current value.

[0042] The resistance values of the first resistance elements 42 and the resistance value of the second resistance element 44 are set to relatively small values so that the supply of current to the load 18 downstream is not hindered as much as possible. Therefore, the amount of change in the voltage drop of the first resistance elements 42 and the second resistance element 44 corresponding to the current flowing therethrough is very small.

[0043] The amplification circuits 46 amplify the voltage drops of the resistance elements to values that can be processed by the control device 52 and output them to the control device 52. More specifically, the amplification circuit 46a amplifies the voltage drop of the first resistance element 42a and outputs it to the control device 52. The amplification circuit 46b amplifies the voltage drop of the first resistance element 42b and outputs it to the control device 52. The amplification circuit 46c amplifies the voltage drop of the first resistance element 42c and outputs it to the control device 52. The amplification circuit 46d amplifies the voltage drop of the second resistance element 44 and outputs it to the control device 52.

[0044] The resistance values of the resistance elements are set in consideration of the range of the current value that is expected to be detected by the resistance elements and the range of the voltage value that can be input to the control device 52. The resistance values of the resistance elements can be set to predetermined values in the range of several mΩ to several hundred mΩ, for example.

[0045] As one example, assume that the range of the current value that is expected to be detected by the resistance elements is 0 A to 300 A and the range of the voltage value that can be input to the control device 52 is 0 V to 5 V. In this example, the resistance value of the resistance elements can be set to 16.7 mΩ (5 V / 300 A = 16.7 mΩ). Also, for example, in the case where the range of the current value that is expected to be detected by the resistance elements is 0 A to 900 A and the range of the voltage value that can be input to the control device 52 is 0 V to 5 V, the resistance value of the resistance elements can be set to 5.6 mΩ (5 V / 900 A ≈ 5.6 mΩ). Based on these cases, as the maximum value of the range of the current value that is expected to be detected by the resistance elements becomes larger, the resistance value of the resistance elements is set to a smaller value.

[0046] Hereinafter, for ease of explanation, the range of the current value that is expected to be detected will be referred to as a detection range and the maximum value of the range of the current value that is expected to be detected will be referred to as a detection maximum value.

[0047] In the region unit 16, for example, the detection range of the first resistance element 42 is set to be the same among the plurality of first resistance elements 42. That is, the resistance value of each of the plurality of first resistance elements 42 is set to be substantially the same value.

[0048] Note that in the region unit 16, the use of the power supply output port 32 can also be distinguished, for example, into large power use, small power use, and the like, in accordance with the size of the current supplied to the load 18 connected downstream of the power supply output port 32. In this example, the detection range of the first resistance element 42, the setting of the resistance value of the first resistance element 42 can also differ among the plurality of first resistance elements 42 depending on the use or power of the power supply output port 32. For example, the resistance value of the first resistance element 42 connected to the power supply output port 32 for large power use can be set to a value smaller than the resistance value of the first resistance element 42 connected to the power supply output port 32 for small power use.

[0049] The second resistance element 44 is electrically connected to each of the plurality of first resistance elements 42 via the connection node 54. Therefore, the current flowing through the second resistance element 44 is branched to each of the plurality of first resistance elements 42 via the connection node 54.

[0050] A current flowing through the second resistance element 44 is a current having a value larger than the current value of the current flowing through each of the plurality of first resistance elements 42. Therefore, the resistance value of the second resistance element 44 is set to be at least a value smaller than the resistance value of each of the plurality of first resistance elements 42.

[0051] More specifically, the resistance value of the second resistance element 44 can also be set to satisfy the following equation (1). Note that in the equation (1), Xa, Xb, Xc represent the resistance value of each of the first resistance elements 42a, 42b, 42c, and Y represents the resistance value of the second resistance element 44.

[0052] 1 / Y = 1 / Xa + 1 / Xb + 1 / Xc ··· (1) That is, the resistance value of the second resistance element 44 can be set so that the sum (1 / Xa + 1 / Xb + 1 / Xc) of the reciprocals of the resistance values of the plurality of first resistance elements 42 obtained by summing the reciprocals of the resistance values of the plurality of first resistance elements 42 becomes the reciprocal (1 / Y) of the resistance value of the second resistance element 44.

[0053] For example, the detection maximum of the first resistance elements 42a, 42b, 42c is set to 300 A respectively. Since the current flowing through the second resistance element 44 is shunted to each of the first resistance elements 42, the detection maximum of the second resistance element 44 becomes 900 A which is the sum of the detection maximum of the first resistance elements 42 divided by the number of the first resistance elements 42. Further, the maximum of the range of the voltage value which can be input to the control device 52 is set to 5 V.

[0054] In this example, the detection maximum of the first resistance element 42a is equal to the value obtained by dividing 5 V by the resistance value Xa of the first resistance element 42a (300 A = 5 V / Xa). The detection maximum of the first resistance element 42b is equal to the value obtained by dividing 5 V by the resistance value Xb of the first resistance element 42b (300 A = 5 V / Xb). The detection maximum of the first resistance element 42c is equal to the value obtained by dividing 5 V by the resistance value Xc of the first resistance element 42c (300 A = 5 V / Xc). The detection maximum of the second resistance element 44 is equal to the value obtained by dividing 5 V by the resistance value Y of the second resistance element 44 (900 A = 5 V / Y). The detection maximum of the second resistance element 44 is equal to the value obtained by summing the detection maximum of the first resistance element 42a, the detection maximum of the first resistance element 42b, and the detection maximum of the first resistance element 42c (900 A = 300 A + 300 A + 300 A, i.e., 5 V / Y = 5 V / Xa + 5 V / Xb + 5 V / Xc). Then, if both sides are divided by 5 V, the above-described equation (1) is derived. In this case, since the detection maximum of the first resistance elements 42a, 42b, 42c is 300 A, if the resistance values Xa, Xb, Xc of the first resistance elements 42a, 42b, 42c are set to be the same (Xa = Xb = Xc), the resistance value Y of the second resistance element 44 is one third of the resistance value Xa of the first resistance element 42a (Y = Xa / 3). For example, if the resistance values Xa, Xb, Xc are 16.7 mΩ respectively (5 V / 300 A = 16.7 mΩ), the resistance value Y can be 5.6 mΩ (16.7 mΩ / 3 = 5.6 mΩ).

[0055] In the power supply system 2, by setting the resistance value of the second resistance element 44 based on the above-described equation (1), the first current value of the first resistance elements 42 can be acquired with an appropriate resolution, and the second current value of the second resistance element 44 can be acquired with an appropriate resolution.

[0056] The communication device 48 constitutes a communication network such as a controller area network (CAN) or the like with communication devices of other electronic control units mounted on the vehicle 3. The zone unit 16 can communicate with the central unit 14 through the communication device 48.

[0057] The storage device 50 is constituted by a nonvolatile storage element capable of electrical writing. In the storage device 50, various data such as data showing characteristics of the downstream electric wire 20 are stored, for example.

[0058] The control device 52 is, for example, a microcomputer, but is not limited to a microcomputer, and can be a non-microcomputer structure based on an ASIC (Application Specific Integrated Circuit) or the like, for example. The control device 52 has one or plural processors 60, and one or plural memories 62 connected to the processors 60. The memories 62 include a ROM in which a program or the like is stored, and a RAM as a work area. The processors 60 control the zone unit 16 in cooperation with the program included in the memories 62. The processors 60 function as a switch control section 64 and an abnormality detection section 66, for example, by executing the program.

[0059] The switch control section 64 controls opening and closing of the switches 40a, 40b, 40c. For example, if the switch control section 64 receives an instruction from the central unit 14 indicating opening and closing of each switch 40, the switch control section 64 opens and closes each switch 40 in accordance with the instruction.

[0060] In addition, the switch control section 64 can cause the switches 40 to function as fuses. In more detail, the switch control section 64 acquires a voltage drop of the first resistance element 42 through the amplification circuit 46. The switch control section 64 derives a current value of a current flowing in the first resistance element 42 from the acquired voltage drop. The switch control section 64 estimates a temperature of the switch 40 corresponding to the first resistance element 42 on the basis of the derived current value. In a case where the estimated temperature exceeds a predetermined temperature, the switch 40 is brought into a closed state, and the load 18 downstream of the switch 40 is electrically cut off.

[0061] The switch control section 64 can also store an open state or a closed state of each switch 40 after control to the memories 62 when controlling opening and closing of each switch 40.

[0062] Here, if the first resistance element 42 rusts or the like due to deterioration over time, the resistance value of the first resistance element 42 sometimes deviates from an appropriate value. In addition, for example, in a manufacturing process of the zone unit 16, there is a possibility that a problem of the first resistance element 42 having a resistance value different from an appropriate resistance value is installed. In this way, if the resistance value of the first resistance element 42 deviates from an appropriate range, a current value derived from a voltage drop of the first resistance element 42 deviates from an appropriate value, and each switch 40 sometimes cannot be properly cut off, for example.

[0063] Therefore, the abnormality detection section 66 determines whether or not the plurality of first resistance elements 42 have a characteristic abnormality. The characteristic abnormality includes an abnormality of the resistance value of the first resistance element 42.

[0064] Figure 2 is a flowchart illustrating a flow of an operation of the abnormality detection section 66. The abnormality detection section 66 repeatedly executes a series of processes illustrated in FIG. 8, for example, every time a predetermined interrupt timing that comes at a predetermined period of several hundreds of ms or the like arrives. Figure 2

[0065] If the predetermined interrupt timing arrives, the abnormality detection section 66 confirms the state of the switch 40 (S10). For example, the abnormality detection section 66 can also confirm the state of the switch 40 by reading the current state of the switch 40 stored in the memory 62.

[0066] The abnormality detection section 66 determines one or more first resistance elements 42 in which the switch 40 is in the on state among the plurality of first resistance elements 42, and acquires the voltage drop of the determined first resistance element 42 via the amplification circuit 46 (S11).

[0067] The abnormality detection section 66 derives the first current value of the first resistance element 42 determined in step S11 on the basis of the voltage drop acquired in step S11 (S12).

[0068] The abnormality detection section 66 derives a total value obtained by totaling the first current values of one or more first resistance elements 42 (the first resistance element 42 determined in step S11) corresponding to the switch 40 in the on state (S13).

[0069] For example, in a case where the switches 40a, 40b, 40c are in the on state, the abnormality detection section 66 adds the first current value of the first resistance element 42a, the first current value of the first resistance element 42b, and the first current value of the first resistance element 42c to derive the total value. Also, for example, in a case where the switches 40a, 40b are in the on state and the switch 40c is in the off state, the first current value of the first resistance element 42a and the first current value of the first resistance element 42b are added to derive the total value. Note that, in a case where the switch 40 in the on state is one, the first current value of one first resistance element 42 corresponding to the one switch 40 in the on state is set as the total value.

[0070] The abnormality detection section 66 acquires the voltage drop of the second resistance element 44 via the amplification circuit 46 (S14).

[0071] The abnormality detection section 66 derives the second current value of the second resistance element 44 on the basis of the voltage drop acquired in step S14 (S15).

[0072] ​The abnormality detection section 66 performs a determination (S16) of whether the total value derived in step S13 substantially coincides with the second current value derived in step S15. In other words, the abnormality detection section 66 determines whether the total value derived in step S13 converges within a predetermined range including the second current value derived in step S15. The predetermined range here is set to a degree that the total value and the second current value are considered to coincide within an allowable error. That is, the predetermined range including the second current value is a range that only amplifies an error amount with the second current value as a reference.

[0073] In a case where it is determined that the total value coincides with the second current value, in other words, in a case where it is determined that the total value converges within the predetermined range including the second current value (Yes in S16), the abnormality detection section 66 determines that the first resistance element 42 corresponding to the switch 40 in the on state among the plurality of first resistance elements 42 has no characteristic abnormality (S17), and ends the series of processing.

[0074] On the other hand, in a case where it is determined that the total value does not coincide with the second current value, in other words, in a case where it is determined that the total value deviates from the predetermined range including the second current value (No in S16), the abnormality detection section 66 determines that the first resistance element 42 corresponding to the switch 40 in the on state among the plurality of first resistance elements 42 has a characteristic abnormality (S18).

[0075] As described above, the resistance value of the first resistance element 42 is set to a relatively small value so that the supply of current to the load 18 downstream is as little hindered as possible. Thus, even if the characteristic abnormality occurs in the first resistance element 42 and the resistance value of the first resistance element 42 changes, it is assumed that the changed resistance value is very small with respect to the load 18. Therefore, even if the characteristic abnormality occurs in the first resistance element 42, the current value of the actual current supplied to the load 18 hardly changes before the characteristic abnormality occurs in the first resistance element 42, and hardly has an impact on the actual current supplied to the load 18.

[0076] However, the control device 52 derives the current value by amplifying the voltage drop based on the small resistance value of the first resistance element 42 with the amplification circuit 46. Therefore, if the resistance value of the first resistance element 42 changes, the value of the calculated current value changes. In this way, the value of the total value of the calculated first current values of the plurality of first resistance elements 42 also changes.

[0077] Therefore, in a case where the resistance value of the first resistance element 42 has changed, although the total value of the actual current values of the plurality of first resistance elements 42 should be equal to the actual current value of the second resistance element 44, the total value of the calculated first current values of the plurality of first resistance elements 42 and the calculated second current value of the second resistance element 44 do not substantially coincide. The abnormality detection section 66 determines the characteristic abnormality of the first resistance element 42 using such a case where the calculated current values do not coincide.

[0078] Note that, in a case where a plurality of switches 40 are in the on state, the abnormality detection section 66 can determine that at least any one of the plurality of first resistance elements 42 corresponding to the switches 40 in the on state has a characteristic abnormality. In this case, it is not possible to determine which one of the plurality of first resistance elements 42 corresponding to the switches 40 in the on state has a characteristic abnormality. However, since the first resistance elements 42 are soldered to the substrate within the region unit 16, if any one of the first resistance elements 42 has a characteristic abnormality, the region unit 16 is replaced for repair. Therefore, it is not necessary to determine which one of the plurality of first resistance elements 42 has a characteristic abnormality, as long as it is possible to determine that any one of the plurality of first resistance elements 42 has a characteristic abnormality.

[0079] After determining that there is a characteristic abnormality, the abnormality detection section 66 causes the notification device 22 to notify that there is a characteristic abnormality in the first resistance element 42 (S19), and ends the series of processes. Note that the notification device 22 is not limited to a manner of notifying that there is a characteristic abnormality in the first resistance element 42, and can also notify that there is an abnormality in the region unit 16 including the first resistance element 42 determined to have a characteristic abnormality.

[0080] If the occupant of the vehicle 3 confirms the characteristic abnormality of the first resistance element 42 through the notification device 22, the vehicle 3 can be taken to a repair shop. In the repair of the vehicle 3, the region unit 16 including the first resistance element 42 having a characteristic abnormality is replaced.

[0081] Note that the order of the process of deriving the first current value by obtaining the voltage drop of the first resistance element 42 and the process of deriving the second current value by obtaining the voltage drop of the second resistance element 44 can be either one of the processes can be performed first, or the processes can be performed in parallel.

[0082] In addition, the abnormality detection unit 66 can acquire the voltage drop of all the first resistance elements 42 regardless of the state of the switch 40. In this case, the abnormality detection unit 66 can also derive the current value for each of the acquired voltage drops and derive a total value. If the switch 40 is in the off state, there is substantially no voltage drop, and the first current value of the first resistance element 42 corresponding to the switch 40 in the off state should be zero. However, for example, in a case where the first current value of the first resistance element 42 corresponding to the switch 40 in the off state is not zero and it is determined that the total value of the first current value and the second current value are substantially inconsistent, the abnormality detection unit 66 can determine that there is a characteristic abnormality in the first resistance element 42.

[0083] Thus, the abnormality detection device 1 of the present embodiment includes a plurality of first resistance elements 42, a second resistance element 44, and a control device 52. One end of each of the plurality of first resistance elements 42 is electrically connected to each other, and the other end of each of the plurality of first resistance elements 42 is connected to a load. One end of the second resistance element 44 is connected to a power supply, and the other end of the second resistance element 44 is electrically connected to a connection node 54. The connection node 54 is formed by the one end of each of the plurality of first resistance elements 42 being electrically connected to each other. In the abnormality detection device 1 of the present embodiment, the abnormality detection unit 66 of the control device 52 derives a first current value of a current flowing in at least one or more of the plurality of first resistance elements 42. The abnormality detection unit 66 derives a second current value of a current flowing in the second resistance element 44. The abnormality detection unit 66 determines whether there is a characteristic abnormality in the plurality of first resistance elements 42 based on a comparison result of the first current value and the second current value.

[0084] More specifically, in the abnormality detection device 1 of the present embodiment, the abnormality detection unit 66 derives a first current value of a current flowing in one or more of the plurality of first resistance elements 42 in which the corresponding switch 40 is in the on state. The abnormality detection unit 66 derives a second current value of a current flowing in the second resistance element 44. In a case where a total value obtained by totaling the first current values of the first resistance elements 42 in which the corresponding switch 40 is in the on state deviates from a predetermined range including the second current value, the abnormality detection unit 66 determines that there is a characteristic abnormality in the first resistance elements 42 in which the corresponding switch 40 is in the on state among the plurality of first resistance elements 42.

[0085] Thus, in the abnormality detection device 1 of the present embodiment, even if a plurality of first resistance elements 42 are provided, it is possible to determine the characteristic abnormality of the first resistance elements 42 by providing only one second resistance element 44 for abnormality detection. Therefore, in the abnormality detection device 1 of the present embodiment, even if the number of first resistance elements 42 increases, it is possible to suppress the increase in cost of the current sensor, compared to a method in which a resistance element for abnormality detection is provided for each first resistance element 42.

[0086] Thus, according to the abnormality detection device 1 of the present embodiment, it is possible to suppress the cost and to appropriately detect the characteristic abnormality of the resistance element.

[0087] Note that, in the above-described embodiment, the switches 40 are provided in one-to-one correspondence with the first resistance elements 42. However, it is also possible to omit the switches 40 and to directly electrically connect the plurality of first resistance elements 42 to the second resistance element 44.

[0088] In this method, the abnormality detection section 66 derives first current values of the currents that respectively flow through the plurality of first resistance elements 42. The abnormality detection section 66 derives a second current value of the current that flows through the second resistance element 44. In a case where it is determined that a total value obtained by totaling the first current values of the plurality of first resistance elements 42 deviates from a predetermined range including the second current value, the abnormality detection section 66 can determine that at least any one of the plurality of first resistance elements 42 has a characteristic abnormality.

[0089] In this configuration, even if the number of first resistance elements 42 increases, it is possible to suppress the increase in cost of the current sensor, thereby making it possible to suppress the cost and to appropriately detect the characteristic abnormality of the resistance element.

[0090] In addition, in the above-described embodiment, when the determination of the characteristic abnormality of the first resistance elements 42 is performed, the on-off states of the plurality of switches 40 are varied among the plurality of switches 40. This is because, depending on the state, situation, or the like of the vehicle 3, the loads 18 that need to be supplied with electric power among the plurality of loads 18 are varied.

[0091] However, under certain conditions, the abnormality detection section 66 can actively control the on-off of the switches 40 in order to perform the determination of the characteristic abnormality of the first resistance elements 42. The certain conditions are set to be when it is assumed that the influence of supplying electric power to or cutting off electric power from the plurality of loads 18 connected to the zone unit 16 is small. For example, the certain conditions can be set to be when a predetermined inspection such as a vehicle inspection or an inspection at the time of shipment of the vehicle 3 is performed.

[0092] Figure 3is a flowchart illustrating a flow of the operation of the abnormality detection section 66 of the modified example that actively controls the switch 40. The abnormality detection section 66 of this modified example executes a series of processes of Figure 3

[0093] First, the abnormality detection section 66 sets one of the plurality of switches 40 corresponding to the first resistance element 42 for which the check of the characteristic abnormality is expected to be performed to an on state, and sets the other switches 40 to off states (S30).

[0094] The abnormality detection section 66 acquires the voltage drop of the first resistance element 42 corresponding to the switch 40 set to the on state via the amplification circuit 46 (S31).

[0095] The abnormality detection section 66 derives the first current value of the first resistance element 42 corresponding to the switch 40 set to the on state on the basis of the voltage drop acquired in step S31 (S32).

[0096] The abnormality detection section 66 acquires the voltage drop of the second resistance element 44 via the amplification circuit 46 (S33).

[0097] The abnormality detection section 66 derives the second current value of the second resistance element 44 on the basis of the voltage drop acquired in step S33 (S34).

[0098] The abnormality detection section 66 performs a determination as to whether the first current value derived in step S32 and the second current value derived in step S34 substantially coincide with each other (S35). In other words, the abnormality detection section 66 determines whether the first current value derived in step S32 converges within a predetermined range including the second current value derived in step S34. The predetermined range here is set to a degree at which the first current value and the second current value are considered to coincide within a range of an allowable error. That is, the predetermined range including the second current value is a range in which the second current value is taken as a reference and only an error amount is amplified.

[0099] In a case where it is determined that the first current value and the second current value coincide with each other, in other words, in a case where it is determined that the first current value converges within the predetermined range including the second current value (Yes in S35), the abnormality detection section 66 determines that the first resistance element 42 corresponding to the switch 40 set to the on state does not have a characteristic abnormality (S36), and ends the series of processes. It should be noted that the abnormality detection section 66 can also return to step S30, change the switch 40 set to the on state, and perform the processes after step S31 again.

[0100] ​On the other hand, in a case where it is determined that the first current value and the second current value are not consistent, in other words, in a case where it is determined that the first current value deviates from a predetermined range including the second current value (NO in S35), the abnormality detection section 66 determines that the first resistance element 42 corresponding to the switch 40 set to the on state has a characteristic abnormality (S37).

[0101] After determining that there is a characteristic abnormality, the abnormality detection section 66 causes the notification device 22 to notify that the first resistance element 42 corresponding to the switch 40 set to the on state has a characteristic abnormality (S38), and ends the series of processing. Note that the abnormality detection section 66 can also return to step S30, change the switch 40 set to the on state, and perform the processing after step S31 again.

[0102] Thus, the abnormality detection section 66 of the abnormality detection device 1 of one modification example sets any one of the plurality of switches 40 to the on state. The abnormality detection section 66 derives the first current value of the current flowing in the first resistance element 42 corresponding to the switch 40 set to the on state among the plurality of first resistance elements 42. The abnormality detection section 66 derives the second current value of the current flowing in the second resistance element 44. In a case where the first current value of the first resistance element 42 corresponding to the switch 40 set to the on state deviates from a predetermined range including the second current value, the abnormality detection section 66 determines that the first resistance element 42 corresponding to the switch 40 set to the on state has a characteristic abnormality.

[0103] Thus, in this modification example, even if the number of first resistance elements 42 increases, it is possible to suppress an increase in cost of the current sensor, it is possible to suppress the cost and appropriately detect a characteristic abnormality of a resistance element.

[0104] In addition, in this modification example, it is possible to determine which one of the plurality of first resistance elements 42 has a characteristic abnormality.

[0105] The above-described embodiment of the present application has been described with reference to the drawings, but the present application is of course not limited to this embodiment. Various modifications or changes can be conceivable to those skilled in the art within the scope of the claims, and it should be understood that such modifications or changes naturally fall within the technical scope of the present application.

[0106] Note that each of the processes shown in the present specification does not necessarily need to be performed in chronological order according to the order shown in the flowchart, and can include parallel processing or processing based on subroutines.

Claims

1. An abnormality detection device characterized by comprising: Possessing: a plurality of first resistance elements, each one end of which is electrically connected to each other, and each other end of which is connected to a load, respectively; a second resistance element, one end of which is connected to a power supply, and the other end of which is electrically connected to a connection node formed by each one end of the plurality of first resistance elements being electrically connected to each other; and a control device, the control device has: one or more processors; and one or more memories connected to the processor, the processor executes processing including: a step of deriving a first current value of a current flowing in at least one or more of the plurality of first resistance elements; a step of deriving a second current value of a current flowing in the second resistance element; and a step of determining whether or not there is a characteristic abnormality in the plurality of first resistance elements based on a comparison result of the first current value and the second current value.

2. The abnormality detection device according to claim 1, wherein the processor executes processing including: a step of deriving a first current value of a current flowing in each of the plurality of first resistance elements, respectively; a step of deriving a second current value of a current flowing in the second resistance element; and a step of determining that there is a characteristic abnormality in at least any one of the plurality of first resistance elements when it is determined that a total value obtained by totaling the first current value of each of the plurality of first resistance elements deviates from a predetermined range including the second current value.

3. The abnormality detection device according to claim 1, wherein the abnormality detection device further has a plurality of switches, each of the plurality of switches corresponds to each of the plurality of first resistance elements one-to-one, and is connected in series to each of the plurality of first resistance elements, respectively, the processor executes processing including: a step of deriving a first current value of a current flowing in one or more of the plurality of first resistance elements in which the corresponding switch is in an on state; a step of deriving a second current value of a current flowing in the second resistance element; and a step of determining that there is a characteristic abnormality in the first resistance element corresponding to the switch in the on state among the plurality of first resistance elements when it is determined that a total value obtained by totaling the first current value of the first resistance element corresponding to the switch in the on state deviates from a predetermined range including the second current value.

4. The abnormality detection device according to claim 1, wherein the abnormality detection device further has a plurality of switches, each of the plurality of switches corresponds to each of the plurality of first resistance elements one-to-one, and is connected in series to each of the plurality of first resistance elements, respectively, the processor executes processing including: a step of setting only any one of the plurality of switches to an on state; a step of deriving a first current value of a current flowing in the first resistance element corresponding to the switch set to the on state among the plurality of first resistance elements; a step of deriving a second current value of a current flowing in the second resistance element; and ​ ​ ​ ​ ​ and determining that the first current value of the first resistance element corresponding to the switch set to the on state is abnormal when the first current value of the first resistance element corresponding to the switch set to the on state deviates from a predetermined range including the second current value.

5. The abnormality detection device according to claim 1, characterized in that the resistance value of the second resistance element is set such that a total value obtained by adding up the reciprocals of the resistance values of the plurality of first resistance elements in the plurality of first resistance elements becomes the reciprocal of the resistance value of the second resistance element.

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