Shunt resistor, monitoring device of shunt resistor, and monitoring program of shunt resistor

Abstract

To provide a technique capable of monitoring abnormality in a conductive jointing section of a shunt resistor.SOLUTION: A shunt resistor 100 includes: a plate-like resistor 130; first and second electrodes 110, 120 connected to both the sides of the resistor in a first direction along a plate surface of the resistor; and a board 140 that is disposed while being overlapped with them, and has a pair of voltage detection points provided in each electrode side. The resistor and the respective electrodes, and the respective electrodes and the board are joined by conductive jointing sections 111, 121, 114, 124 along a second direction orthogonal to the first direction. As a pair of voltage detection points, first detection points 116h, 126h, and second detection points 117h, 127h positioned in edge sides in the second direction of the respective electrodes relative to the first detection points are provided. A monitoring device 20 for measuring voltage across the respective electrodes in the resistor by a detection voltage in the pair of voltage detection points has a malfunction determination section 21 for determining jointing abnormality of the conductive jointing sections on the basis of detection voltages of the first and second detection points.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a shunt resistor, a monitoring device for a shunt resistor, and a monitoring program for a shunt resistor. [Background technology]

[0002] The shunt resistor described in Patent Document 1 includes a resistor, a first electrode and a second electrode connected to both sides of the resistor, and a substrate laminated on the upper surface thereof. The substrate is provided with a first through-hole located above the first electrode and a second through-hole located above the second electrode. The first through-hole and the second through-hole are filled with solder, and the substrate is joined to the first electrode and the second electrode via the solder. The solder filled in the first through-hole and the second through-hole is used as a voltage detection terminal to detect the voltage across the resistor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2021-182579 A Summary of the Invention [Problem to be solved by the invention]

[0004] Thermal history such as heat generation caused by current flowing through a shunt resistor can cause joint abnormalities in conductive joints such as solder. When the electrical conduction between the substrate and the first and second electrodes is via solder as in Patent Document 1, the conductive area decreases due to solder joint abnormalities, and the detection accuracy of the voltage across the resistor decreases.

[0005] In view of the above, an object of the present invention is to provide a technique capable of monitoring an abnormality in a conductive joint of a shunt resistor. [Means for solving the problem]

[0006] The present invention provides a shunt resistor monitoring device that is applied to a shunt resistor comprising a plate-shaped resistor, a first electrode and a second electrode connected to both sides of the resistor in a first direction along the plate surface of the resistor, and a substrate arranged to overlap the resistor and the electrodes and having a pair of voltage detection points provided on the first electrode side and the second electrode side, respectively, in which the resistor and the electrodes and the electrodes and the substrate are joined by conductive joints along a second direction perpendicular to the first direction, and measures a voltage between both ends of the resistor between the first electrode side and the second electrode side based on detection voltages at the pair of voltage detection points. The substrate is provided with a first detection point and a second detection point located closer to the end of each electrode than the first detection point in the second direction as the pair of voltage detection points. The monitoring device includes a fault determination unit that determines a connection abnormality of the conductive joints based on the detection voltages at the first detection point and the second detection point.

[0007] According to the present invention, the resistor and each electrode of the shunt resistor are joined by a conductive joint, and a current flows through the conductive joint in the order of the first electrode, resistor, and second electrode, or in the reverse order, generally along the first direction. The current flowing between each electrode and resistor has a lower current density toward the center of each electrode in the second direction, and a higher current density toward the end. Each electrode of the shunt resistor is joined to the substrate by a conductive joint, and a current flows between the first detection point provided on the substrate and the first electrode through the conductive joint, and a current flows between the second detection point provided on the substrate and the second electrode through the conductive joint. In the shunt resistor according to the present invention, the second detection point is located on the substrate closer to the end of each electrode than the first detection point in the second direction. That is, the second detection point is located on the end side where the current density of the current flowing between each electrode and resistor is higher than that of the first detection point. Therefore, when there is no connection abnormality in the conductive joint, the detected voltage at the first detection point differs from the detected voltage at the second detection point. When a connection abnormality occurs in the conductive joint, the difference between the detected voltage at the first detection point and the detected voltage at the second detection point changes. The monitoring device according to the present invention includes a fault determination unit that determines a connection abnormality in the conductive joint based on the detected voltages at the first detection point and the second detection point, and can determine an abnormality in the conductive joint, for example, by monitoring the difference between the detected voltage at the first detection point and the detected voltage at the second detection point.

[0008] The present invention can also provide a shunt resistor capable of suitably determining a connection abnormality in a conductive joint. The shunt resistor includes a plate-shaped resistor, a first electrode and a second electrode connected to both sides of the resistor in a first direction along the plate surface of the resistor, and a substrate arranged to overlap the resistor and each electrode and having a pair of voltage detection points provided on the first electrode side and the second electrode side, respectively. The resistor and each electrode, and each electrode and the substrate are joined by a conductive joint along a second direction perpendicular to the first direction. The substrate is provided with the pair of voltage detection points, a first detection point and a second detection point located closer to the end of each electrode than the first detection point in the second direction.

[0009] The present invention can also be provided as a monitoring program for the shunt resistor, which causes a computer to execute a detection step of measuring a voltage between the first electrode side and the second electrode side of the resistor based on detected voltages at the pair of voltage detection points, and a fault determination step of determining a connection abnormality of the conductive junction based on the detected voltages at the first detection point and the second detection point. [Brief description of the drawings]

[0010] [Figure 1] 1 is a power supply system including a shunt resistor and a shunt resistor monitoring device according to a first embodiment. [Diagram 2] FIG. 2 is an exploded view of the shunt resistor according to the first embodiment. [Diagram 3] FIG. 2 is a top view of the shunt resistor according to the first embodiment. [Figure 4] Cross-sectional view taken along line IV-IV in Figure 3. [Diagram 5] Cross-sectional view of line VV in Figure 3. [Figure 6] FIG. 4 is a current density distribution diagram of the current flowing between each electrode and the resistor of the shunt resistor according to the first embodiment. [Figure 7] FIG. 4 is a diagram showing detected voltage values ​​at a first detection point and a second detection point. [Figure 8] 5 is a flowchart showing a monitoring process for a shunt resistor according to the first embodiment. [Figure 9] 10 is a flowchart showing a method for monitoring a shunt resistor according to a modified example. [Figure 10] FIG. 11 is a top view of a shunt resistor according to a second embodiment. [Figure 11] FIG. 11 is a top view showing a resistor and each electrode of a shunt resistor according to a second embodiment. [Figure 12] Cross-sectional view taken along line IIX-IIX in Figure 11. [Figure 13] FIG. 11 is a top view of a shunt resistor according to a third embodiment. [Figure 14] FIG. 13 is a top view of a shunt resistor according to a fourth embodiment. [Figure 15] 13 is a flowchart showing a monitoring process of a shunt resistor according to a fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] (First embodiment) FIG. 1 shows a power supply system 10 including a monitoring device 20 for a resistor 13 according to an embodiment. The power supply system 10 includes a storage battery 11, a resistor 13, a detection circuit 15, a monitoring device 20, a first relay RL1, and a second relay RL2. As shown in FIG. 1, the resistor 13 is connected to the high potential side of the storage battery 11, the first relay RL1 is connected to the high potential side of the resistor 13, and the second relay RL2 is connected to the low potential side of the storage battery 11, but the connection order is not limited thereto. For example, the storage battery 11 may be connected between the first relay RL1 and the resistor 13. The power supply system 10 is connected to a load 30. The power supply system 10 is mounted on a vehicle, and the load 30 represents various electric loads mounted on the vehicle.

[0012] The detection circuit 15 includes a first AD converter ADC1 and a second AD converter ADC2 connected in parallel to the resistor 13. When the first relay RL1 and the second relay RL2 are in a closed state, the resistor 13 is in a conducting state. The monitoring device 20 acquires a voltage across the resistor 13 from the detection circuit 15. The monitoring device 20 acquires a first voltage V1 as a detected voltage value from the first AD converter ADC1, and acquires a second voltage V2 as a detected voltage value from the second AD converter ADC2. The resistor 13 is a shunt resistor, and the monitoring device 20 detects a current flowing through the storage battery 11 by detecting the voltage across the resistor 13.

[0013] Figures 2 to 5 show a shunt resistor 100 used as the resistor 13 shown in Figure 1. Figure 2 is an exploded perspective view of the shunt resistor 100, Figure 3 is a top view of the shunt resistor 100, and Figures 4 and 5 are cross-sectional views of the shunt resistor 100.

[0014] The shunt resistor 100 includes a plate-like first electrode 110 and a plate-like second electrode 120 , a plate-like resistor 130 , and a substrate 140 .

[0015] Examples of the material of the resistor 130 include, but are not limited to, nickel-chromium alloys, copper-nickel alloys, copper-manganese alloys, and copper-manganese-nickel alloys. Examples of the first electrode 110 and the second electrode 120 include, but are not limited to, bus bars made of, for example, copper. The first electrode 110 and the second electrode 120 are provided with a first through hole 113 and a second through hole 123, respectively. The substrate 140 is a printed circuit board, and may be a rigid substrate made of glass or the like impregnated with epoxy resin or the like, or a flexible substrate made of polyimide resin or the like. A wiring pattern is provided on the upper surface (the surface on the positive side of the z-axis) and the lower surface (the surface on the negative side of the z-axis) of the substrate 140.

[0016] The first electrode 110 and the second electrode 120 are connected to both sides of the resistor 130 in a first direction (x-axis direction shown in FIG. 2) along the plate surface of the resistor 130. The surface of the first electrode 110 in the positive direction of the x-axis is joined to the surface of the resistor 130 in the negative direction of the x-axis, and the surface of the second electrode 120 in the negative direction of the x-axis is joined to the surface of the resistor 130 in the positive direction of the x-axis. In a second direction (y-axis direction shown in FIG. 2) perpendicular to the first direction, the lengths of the first electrode 110, the second electrode 120, and the resistor 130 are approximately the same. The first electrode 110, the second electrode 120, and the resistor 130 are flat and approximately parallel to the xy plane shown in FIG. 2. The first electrode 110 and the second electrode 120 have approximately the same thickness in a third direction (z-axis direction shown in FIG. 2) perpendicular to the first and second directions. The thickness of the resistor 130 in the third direction is smaller than the thicknesses of the first electrode 110 and the second electrode 120 .

[0017] The first electrode 110, the second electrode 120, and the resistor 130 are aligned in the positive and negative directions of the y-axis and in the negative direction of the z-axis, and are joined by welding. The first electrode 110 and the resistor 130 are joined to each other via a first welded portion 111, and the second electrode 120 and the resistor 130 are joined to each other via a second welded portion 121. The first welded portion 111 and the second welded portion 121 correspond to a conductive joint. The first electrode 110 and the resistor 130 are joined to each other and electrically connected to each other via the first welded portion 111. The second electrode 120 and the resistor 130 are joined to each other and electrically connected to each other via the second welded portion 121.

[0018] A pair of first upper surface wirings 116, 126 and a pair of second upper surface wirings 117, 127 are provided on the upper surface of the substrate 140. A first bonding wiring 115 and a second bonding wiring 125 are provided on the lower surface of the substrate 140.

[0019] A pair of first detection points 116h, 126h and a pair of second detection points 117h, 127h are provided on the upper and lower surfaces of the substrate 140. The first detection points 116h, 126h and the second detection points 117h, 127h are formed by wiring provided on the periphery and inner surface of a via hole that penetrates the substrate 140 in the vertical direction.

[0020] On the upper surface of the substrate 140, the first detection points 116h, 126h are connected to the first upper surface wirings 116, 126, respectively, and the second detection points 117h, 127h are connected to the second upper surface wirings 117, 127, respectively. The first upper surface wirings 116, 126 are connected to the first AD converter ADC1 of the detection circuit 15, and the second upper surface wirings 117, 127 are connected to the second AD converter ADC2 of the detection circuit 15.

[0021] On the underside of the substrate 140, the first detection point 116h and the second detection point 117h are connected to the first joining wiring 115 via the first underside wiring 116a and the second underside wiring 117a, respectively, and the first detection point 126h and the second detection point 127h are connected to the second joining wiring 125 via the first underside wiring 126a and the second underside wiring 127a, respectively.

[0022] The first detection point 116h and the second detection point 117h are provided on the first electrode 110 side, and the first detection point 126h and the second detection point 127h are provided on the second electrode 120 side. The first detection points 116h, 126h are located approximately in the center of the first electrode 110 and the second electrode 120 in the y-axis direction. The second detection points 117h, 127h are located on the end side of the first electrode 110 and the second electrode 120 in the positive direction of the y-axis direction. The second detection points 117h, 127h are located closer to the end side of the first electrode 110 and the second electrode 120 in the y-axis direction than the first detection points 116h, 126h. The first upper surface wirings 116, 126 extend from the end of the substrate 140 in the negative direction of the y-axis along the positive direction of the y-axis, and have a shape bent toward the first detection points 116h, 126h, respectively. The second upper surface wirings 117, 127 extend along the positive direction of the y axis from the end of the substrate 140 in the negative direction of the y axis between the first upper surface wirings 116, 126, and are bent toward the second detection points 117h, 127h, respectively.

[0023] The substrate 140 is joined to the first electrode 110 via the first solder portion 114, and is joined to the second electrode 120 via the second solder portion 124. The first solder portion 114 is provided at a first solder position 112 on the upper surface of the first electrode 110, and is solder-joined such that a first bonding wire 115 of the substrate 140 is located on the upper surface of the first solder portion 114. The second solder portion 124 is provided at a second solder position 122 on the upper surface of the second electrode 120, and is solder-joined such that a second bonding wire 125 of the substrate 140 is located on the upper surface of the second solder portion 124. The thickness of the resistor 130 in the z direction is thinner than the thicknesses of the first electrode 110 and the second electrode 120, and they are aligned so that their faces in the negative direction of the z axis are aligned. Therefore, as shown in Fig. 5, the distance between the upper surface of the resistor 130 and the substrate 140 is wider than the distance between the upper surfaces of the first electrode 110 and the second electrode 120 and the substrate 140. The pair of first detection points 116h, 126h and the pair of second detection points 117h, 127h are provided at positions above the resistor 130.

[0024] The first solder section 114 and the second solder section 124 correspond to conductive joints. The first electrode 110 and the substrate 140 are joined to each other via the first solder section 114. The first electrode 110 and the first joint wiring 115 of the substrate 140 are electrically connected to each other via the first solder section 114. The second electrode 120 and the substrate 140 are joined to each other via the second solder section 124. The second electrode 120 and the second joint wiring 125 of the substrate 140 are electrically connected to each other via the second solder section 124.

[0025] The shunt resistor 100 can be manufactured, for example, by the following procedure. First, the first electrode 110, the second electrode 120, and the resistor 130 are prepared and welded together. Next, the first solder portion 114 is formed at the first solder position 112, and the second solder portion 124 is formed at the second solder position 122. Next, the substrate 140 on which a wiring pattern is formed is prepared, and the substrate 140 is aligned and soldered so that the first bonding wire 115 is located on the upper surface of the first solder portion 114, and the second bonding wire 125 is located on the upper surface of the second solder portion 124. In this manner, the shunt resistor 100 can be manufactured.

[0026] The first AD converter ADC1 is connected to the first top-surface wiring 116 and the first top-surface wiring 126, and detects the voltage across the first electrode 110 and the second electrode 120 of the resistor 130 as a first voltage V1. The current path (first current path) from the first top surface wiring 116 to the first top surface wiring 126 is in the following order: first top surface wiring 116, first detection point 116h (more specifically, from the top side to the bottom side of the first detection point 116h), first bottom surface wiring 116a, first joining wiring 115, first solder portion 114, first electrode 110, first welding portion 111, resistor 130, second welding portion 121, second electrode 120, second solder portion 124, second joining wiring 125, first bottom surface wiring 126a, first detection point 126h (more specifically, from the bottom side to the top side of the first detection point 126h), and first top surface wiring 126. Since the first detection points 116h and 126h are located approximately in the center of the first electrode 110 and the second electrode 120 in the y-axis direction, the first current path passes through approximately the center of the resistor 130 in the y-axis direction.

[0027] The second AD converter ADC2 is connected to the second top surface wiring 117 and the second top surface wiring 127, and detects the voltage across the first electrode 110 and the second electrode 120 of the resistor 130 as a second voltage V2. The current path (second current path) from the second upper surface wiring 117 to the second upper surface wiring 127 is in the following order: second upper surface wiring 117, second detection point 117h (more specifically, from the upper surface side to the lower surface side of the second detection point 117h), second lower surface wiring 117a, first joining wiring 115, first solder portion 114, first electrode 110, first welding portion 111, resistor 130, second welding portion 121, second electrode 120, second solder portion 124, second joining wiring 125, second lower surface wiring 127a, second detection point 127h (more specifically, from the lower surface side to the upper surface side of the second detection point 127h), and second upper surface wiring 127. Since the second detection points 117h, 127h are located at the positive end side of the first electrode 110 and the second electrode 120 in the y-axis direction, the second current path is a path that passes through the positive end side of the resistor 130 in the y-axis direction.

[0028] The monitoring device 20 includes a fault determination unit 21, a correction unit 22, and a control unit 23. The monitoring device 20 is mainly configured with a well-known microcomputer (microcomputer) including a CPU, a ROM, a RAM, a flash memory, and the like. For example, the CPU executes a power conversion program installed in the ROM to realize functions such as a switching control unit 41 and a switching unit 42 included in the control device 40. The functions provided by the microcomputer may be provided by software recorded in a substantial memory device and a computer that executes the software, only the software, only the hardware, or a combination of these. For example, when the microcomputer is provided by an electronic circuit that is hardware, it can be provided by a digital circuit including a large number of logic circuits, or an analog circuit. For example, the microcomputer executes a program stored in a non-transitional substantial recording medium as a storage unit included in the microcomputer. The program includes, for example, a program for a battery control process described later. When the program is executed, a method corresponding to the program is executed. The storage unit is, for example, a non-volatile memory. Note that the program stored in the storage unit can be updated, for example, via a network such as the Internet.

[0029] The fault determination unit 21 determines a joint abnormality of the conductive joints, that is, the first welded portion 111, the second welded portion 121, the first solder portion 114, and the second solder portion 124, based on the detected voltages of the first detection points 116h, 126h and the second detection points 117h, 127h.

[0030] FIG. 6 is a diagram showing the current density distribution of the current flowing between the first and second electrodes 110, 120 and the resistor 130 in the shunt resistor 100. The vertical axis indicates the current density J, and the horizontal axis indicates the position in the y-axis direction of the first and second electrodes 110, 120. In FIG. 6, w is the length of the first and second electrodes 110, 120 in the y-axis direction, y=0 indicates the center position of the first and second electrodes 110, 120, y=-w / 2 indicates the end position in the negative direction of the y-axis of the first and second electrodes 110, 120, and y=w / 2 indicates the end position in the positive direction of the y-axis of the first and second electrodes 110, 120. As shown in FIG. 6, the current density of the positive current flowing through the shunt resistor 100 is distributed in a downwardly convex curved shape that is lower toward the center of the first and second electrodes 110, 120 and higher toward the ends.

[0031] 6, the first detection points 116h, 126h are located at y=y1, which is approximately the center of the first electrode 110 and the second electrode 120 in the y-axis direction, and the current density at this position is J1. The second detection points 117h, 127h are located at y=y2, which is the end side in the positive direction of the y-axis direction of the first electrode 110 and the second electrode 120, and the current density at this position is J2. Since J1 is lower than J2, even if the current flowing between the first and second electrodes 110, 120 and the resistor 130 is the same, the first voltage V1 detected by the first AD converter ADC1 is lower than the second voltage V2 detected by the second AD converter ADC2.

[0032] 7 is a diagram showing, on the horizontal axis, the energizing current flowing between the first and second electrodes 110, 120 and the resistor 130, and on the vertical axis, the detection values ​​of the voltages detected by the first and second AD converters ADC1, ADC2. Even if the energizing current flowing between the first and second electrodes 110, 120 and the resistor 130 is the same, the absolute value of the first voltage V1 detected by the first AD converter ADC1 is smaller than the absolute value of the second voltage V2 detected by the second AD converter ADC2.

[0033] When there is no junction abnormality in each conductive joint, as shown in FIG. 7, the first voltage V1 and the second voltage V2 differ by a predetermined voltage difference for a certain current flow. However, due to thermal history such as heat generation caused by the current flowing through the shunt resistor 100, junction abnormality may occur in each conductive joint. Junction abnormality is more likely to occur at a position with high current density than at a position with low current density for the same current flow. That is, junction abnormality is more likely to occur in each conductive joint at both ends of the first electrode 110 and the second electrode 120 in the y-axis direction, where the current density is high, than at the center of the first electrode 110 and the second electrode 120 in the y-axis direction, where the current density is low. Junction abnormality that occurs at both ends of the first electrode 110 and the second electrode 120 in the y-axis direction gradually spreads toward the center.

[0034] When a junction abnormality occurs in any of the conductive junctions at the ends of the first electrode 110 and the second electrode 120 in the positive y-axis direction and the junction abnormality gradually progresses toward the center, the second current path including the second detection points 117h and 127h approaches the first current path including the first detection points 116h and 126h in the resistor 130. As a result, the value of the second voltage V2 gradually approaches the first voltage V1, and the difference between them becomes smaller.

[0035] For this reason, the failure determination unit 21 is configured to determine that a junction abnormality has occurred in any of the conductive junctions of the shunt resistor 100 when there is a change in the difference between the first voltage V1 and the second voltage V2. For example, the failure determination unit 21 is configured to determine that there is a junction abnormality when abs(V1-V2), which is the absolute value of the difference between the first voltage V1 and the second voltage V2, becomes equal to or less than a predetermined threshold voltage difference Vth (when abs(V1-V2)≦Vth). The threshold voltage difference Vth can be set to 0≦Vth≦Vr by, for example, measuring or calculating Vr, which is the absolute value of the difference between the first voltage V1 and the second voltage V2 when there is no junction abnormality in each conductive junction of the shunt resistor 100. The value of Vr may be theoretically calculated based on the design value of the shunt resistor 100, or may be calculated using the first voltage V1 and the second voltage V2 measured using the shunt resistor 100 in an initial state.

[0036] The correction unit 22 corrects at least one of the first voltage V1 and the second voltage V2 so that the first voltage V1 and the second voltage V2 are substantially the same. The correction unit 22 can correct the first voltage V1 and the second voltage V2 so that they are substantially the same, for example, by using a difference or ratio between the second voltage V2 and the first voltage V1. The correction unit 22 may correct the first voltage V1, but it is more preferable to correct the second voltage V2 because the second voltage V2 is a value that changes when a joint abnormality occurs in each conductive joint, whereas the first voltage V1 is a value that is unlikely to change even when a joint abnormality occurs in each conductive joint.

[0037] The correction unit 22 may be configured to correct the first voltage V1 and the second voltage V2 to be substantially the same when the failure determination unit 21 determines that a connection abnormality has occurred. By comparing the first voltage V1 and the second voltage V2 in a corrected state, it is possible to determine, for example, a failure in the first and second AD converters ADC1 and ADC2. The failure determination unit 21 may also be configured to be able to determine a failure in the first and second AD converters ADC1 and ADC2.

[0038] Alternatively, the correction unit 22 may correct the first voltage V1 and the second voltage V2 to be substantially the same, and then the fault determination unit 21 may compare the first voltage V1 and the second voltage V2 in the corrected state to determine that there is a junction abnormality. For example, when the second voltage V2 is corrected to a correction value V2a, the fault determination unit 21 may be configured to determine that there is a junction abnormality when abs(V1-V2a), which is the absolute value of the difference between the first voltage V1 and the correction value V2a, becomes equal to or greater than a predetermined threshold voltage difference Vtha (when abs(V1-V2a)≧Vtha).

[0039] The control unit 23 executes opening and closing control of the first relay RL1 and the second relay RL2 based on at least one of the first voltage V1 and the second voltage V2 acquired from the detection circuit 15. When the fault determination unit 21 determines that a joint abnormality has occurred, the control unit 23 executes control to cut off the current flowing through the shunt resistor 100. For example, when the fault determination unit 21 determines that a fault such as a joint abnormality has occurred in the shunt resistor 100, the control unit 23 controls the first relay RL1 and the second relay RL2 to an open state, thereby cutting off the current flowing through the shunt resistor 100. Note that, when the power supply system 10 has a configuration capable of limiting the current flowing through the shunt resistor 100, the control unit 23 may be configured to determine whether to limit or cut off the current flowing through the shunt resistor 100 and execute either control when the fault determination unit 21 determines that a joint abnormality has occurred.

[0040] Fig. 8 is a flowchart of the monitoring process of the shunt resistor 100 executed by the monitoring device 20. The process shown in the flowchart of Fig. 8 is realized by the CPU constituting the monitoring device 20 executing a monitoring program installed in the ROM, and is repeatedly executed at predetermined intervals when the storage battery 11 is charged or discharged.

[0041] In step S101, the first voltage V1 and the second voltage V2 are acquired, and the process proceeds to step S102. In step S102, if abs(V1-V2), which is the absolute value of the difference between the first voltage V1 and the second voltage V2, is equal to or less than a predetermined threshold voltage difference Vth (if abs(V1-V2)≦Vth), it is determined that there is a junction abnormality, and the process proceeds to step S103. If abs(V1-V2)>Vth, it is determined that there is no junction abnormality, and the process proceeds to step S105.

[0042] In step S103, it is determined that there is a fault in the shunt resistor 100, and the process proceeds to step S104, where the energizing current is limited or cut off. As a result, the monitoring device 20 controls the first relay RL1 and the second relay RL2 to an open state, and ends the process.

[0043] In step S105, it is determined that there is no failure in the shunt resistor 100, and the process proceeds to step S106, where the second voltage V2 is corrected, and the process ends.

[0044] As described above, according to the shunt resistor 100 of this embodiment, the second detection points 117h, 127h are located on the end side of each electrode in the second direction relative to the first detection points 116h, 126h on the substrate 140. That is, the second detection points 117h, 127h are located on the end side where the current density of the current flowing between the first and second electrodes 110, 120 and the resistor 130 is higher than the first detection points 116h, 126h. Therefore, when there is no connection abnormality in the conductive joint in the shunt resistor 100, the first voltage V1, which is the detection voltage at the first detection points 116h, 126h acquired by the monitoring device 20, differs from the second voltage V2, which is the detection voltage at the second detection points 117h, 127h. When a connection abnormality occurs in the conductive joint in the shunt resistor 100, the difference between the first voltage V1 and the second voltage V2 becomes smaller. The monitoring device 20 executes the failure determination steps shown in steps S102, S103, and S105, and determines that there is a connection abnormality in the conductive joint in the shunt resistor 100 when abs(V1-V2)≦Vth is satisfied based on abs(V1-V2), which is the absolute value of the difference between the first voltage V1 and the second voltage V2. The failure determination step makes it possible to monitor the conductive joint of the shunt resistor of the shunt resistor 100 for abnormality. Furthermore, if the failure determination step determines that there is no failure in the shunt resistor 100, a correction step shown in step S106 is executed to correct the second voltage V2 to a correction value V2a that is substantially the same as the first voltage V1. Although not shown, by comparing the first voltage V1 with the correction value V2a, it is possible to determine, for example, failures in the first and second AD converters ADC1 and ADC2.

[0045] (Modification) The monitoring device 20 may be configured to execute a flowchart shown in Fig. 9 as a monitoring process for the shunt resistor 100. The process shown in the flowchart in Fig. 9 is realized by a CPU constituting the monitoring device 20 executing a monitoring program installed in a ROM, and is repeatedly executed at predetermined intervals when the storage battery 11 is charged or discharged.

[0046] In step S201, the first voltage V1 and the second voltage V2 are acquired, and the process proceeds to step S102. In step S202, the second voltage V2 acquired in step S201 is corrected to a correction value V2a, and the process proceeds to step S203. In step S203, it is determined whether abs(V1-V2a)≦Vtha. If abs(V1-V2a)≦Vtha, it is determined that there is a junction abnormality, and the process proceeds to step S204. If abs(V1-V2a)>Vtha, it is determined that there is no junction abnormality, and the process proceeds to step S205.

[0047] In step S204, it is determined that the shunt resistor 100 has a fault, and the process proceeds to step S205, where the current flow is limited or cut off. As a result, the monitoring device 20 controls the first relay RL1 and the second relay RL2 to an open state, and ends the process. In step S206, it is determined that the shunt resistor 100 has no fault, and ends the process.

[0048] Second embodiment Fig. 10 shows a shunt resistor 200 according to the second embodiment. As in the first embodiment, the shunt resistor 200 is used as the resistor 13 shown in Fig. 1. The shunt resistor 200 differs from the shunt resistor 100 shown in Fig. 2 etc. in the form of the resistor 230. In the shunt resistor 200, the same reference numbers are used for configurations similar to those of the shunt resistor 100.

[0049] Fig. 11 shows the shunt resistor 200 with the substrate 140 and the first and second solder portions 114, 124 removed. The first and second electrodes 110, 120 are connected to both sides of the resistor 230 by welding. Fig. 12 is a cross-sectional view of the resistor 230 shown in Fig. 11. As shown in FIGS. 10 and 11, the length of the resistor 230 in the y-axis direction is shorter than the length of the first and second electrodes 110 and 120 in the y-axis direction. The resistor 230 and the first and second electrodes 110 and 120 are connected so that their ends on the negative side of the y-axis are aligned, and a non-existence portion 250 where the resistor 230 is not present is provided between the first and second electrodes 110 and 120 at the end on the positive side of the y-axis. Also, as shown in FIG. 12, the resistor 230 is locally thinned at the end on the positive side of the y-axis. The cross-sectional area perpendicular to the x-axis of this thinned portion is reduced compared to the cross-sectional area perpendicular to the x-axis of the non-thinned portion, and is therefore referred to as a reduced portion 231.

[0050] The resistor 230 has a reduced section 231 in which the cross-sectional area perpendicular to the x-axis is reduced at the end side in the positive direction of the y-axis by reducing the length in the y-axis direction and the length (thickness) in the z-axis direction at the end side in the negative direction of the y-axis. Since the x-axis direction is the direction of the current flowing between the first and second electrodes 110 and 120 and the resistor 230, the current density at the reduced section 231 provided at the end side in the positive direction of the y-axis is higher than the current density at the end side in the negative direction of the y-axis in the resistor 230 by reducing the cross-sectional area perpendicular to the x-axis. For this reason, the joint abnormality of each conductive joint provided in the shunt resistor 200 is likely to occur from the reduced section 231 side where the current density is higher. In the shunt resistor 200, the second detection points 117h, 127h are provided on the substrate 140 located on the upper surface of the end side in the positive direction of the y axis where the reduced portion 231 is provided in the resistor 230, while the second detection points are not provided on the substrate 140 located on the upper surface of the end side in the negative direction of the y axis where no reduced portion is provided. By providing the second detection points 117h, 127h only on the upper surface side of the reduced portion 231 where the connection abnormality of each conductive joint provided in the shunt resistor 200 is most likely to occur, it is possible to both reduce the number of voltage detection points and ensure that the connection abnormality of each conductive joint provided in the shunt resistor 200 can be detected reliably.

[0051] Third embodiment Fig. 13 shows a shunt resistor 300 according to the third embodiment. As in the first embodiment, the shunt resistor 300 is used as the resistor 13 shown in Fig. 1. The shunt resistor 300 differs from the shunt resistor 100 shown in Fig. 2 etc. in the form of the wiring pattern provided on the substrate 340. In the shunt resistor 300, the same reference numbers are used for components similar to those of the shunt resistor 100.

[0052] A pair of first detection points 316h, 326h and a pair of second detection points 317h, 327h are provided on the upper and lower surfaces of the substrate 340. The first detection points 316h, 326h and the second detection points 317h, 327h are formed by wiring provided on the periphery and inner surface of a via hole that penetrates the substrate 340 in the vertical direction.

[0053] The first detection points 316h, 326h are provided at the same positions as the first detection points 116h, 126h in the shunt resistor 100. The second detection point 327h is provided at the same position as the second detection point 127h in the shunt resistor 100, while the second detection point 317h is provided on the negative side of the y-axis with respect to the first detection point 316h, unlike the second detection point 117h in the shunt resistor 100. The first upper surface wirings 316, 326 are connected to the first detection points 316h, 326h, respectively, and the second upper surface wirings 117, 127 are connected to the second detection points 317h, 327h, respectively.

[0054] The second detection points 317h, 327h are arranged such that the second detection point 317h, which is one of the voltage detection points, is a detection point near a first end, which is an end in the positive direction of the y-axis on the first electrode 110 side, and the second detection point 327h, which is the other voltage detection point, is a detection point near a second end, which is an end in the negative direction of the y-axis on the opposite side to the first end on the second electrode 120 side. The first detection points 316h, 326h are arranged linearly along the x-axis direction, whereas the second detection points 317h, 327h are arranged substantially diagonally with respect to the resistor 230. Since the second detection points 317h, 327h are provided on the first end side and the second end side, respectively, even if a junction abnormality of each conductive junction included in the shunt resistor 300 occurs from the first end side or the second end side, the value of the second voltage V2 gradually approaches the first voltage V1, and the difference between them becomes small, so that the occurrence of a junction abnormality can be detected. According to the shunt resistor 300, it is possible to reduce the number of voltage detection points and to reliably detect a connection abnormality in each conductive connection portion of the shunt resistor 300.

[0055] (Fourth embodiment) Fig. 14 shows a shunt resistor 400 according to the fourth embodiment. The shunt resistor 400 differs from the shunt resistor 100 shown in Fig. 2 etc. in the form of a wiring pattern provided on a substrate 440. In the shunt resistor 400, the same reference numerals are used for configurations similar to those of the shunt resistor 100.

[0056] A pair of first detection points 416h, 426h, a pair of second detection points 417h, 427h, and a pair of second detection points 418h, 428h are provided on the upper and lower surfaces of the substrate 440. The first detection points 416h, 426h, the second detection points 417h, 427h, and the second detection points 418h, 428h are formed by wiring provided on the periphery and inner side surface of a via hole that penetrates the substrate 440 in the vertical direction.

[0057] The first detection points 416h, 426h are provided at the same positions as the first detection points 116h, 126h in the shunt resistor 100. The first detection points 116h, 126h in the shunt resistor 100. The second detection points 417h, 427h are provided at the same positions as the second detection points 117h, 127h in the shunt resistor 100. The second detection points 418h, 428h are located at the ends of the first electrode 110 and the second electrode 120 in the negative direction in the y-axis direction. The distance between the second detection points 418h, 428h and the ends of the first electrode 110 and the second electrode 120 in the negative direction in the y-axis direction is approximately the same as the distance between the second detection points 117h, 127h and the ends of the first electrode 110 and the second electrode 120 in the positive direction in the y-axis direction. The first upper surface wiring 416, 426 is connected to the first detection points 416h, 426h, respectively, the second upper surface wiring 417, 427 is connected to the second detection points 417h, 427h, respectively, and the second upper surface wiring 418, 428 is connected to the second detection points 418h, 428h, respectively.

[0058] 1, as in the first embodiment. When the shunt resistor 400 is used as the resistor 13, the detection circuit 15 further includes a third AD converter ADC3. The third AD converter ADC3 is connected to the first top surface wiring 418 and the first top surface wiring 428, and detects the voltage across the first electrode 110 and the second electrode 120 of the resistive body 130 of the shunt resistor 400 as a third voltage V3.

[0059] Fig. 15 is a flowchart of the monitoring process of the shunt resistor 400 executed by the monitoring device 20. The process shown in the flowchart of Fig. 15 is realized by the CPU constituting the monitoring device 20 executing a monitoring program installed in the ROM, and is repeatedly executed at predetermined intervals when the storage battery 11 is charged or discharged.

[0060] In step S301, the first voltage V1, the second voltage V2, and the third voltage V3 are acquired, and the process proceeds to step S302. In step S302, if abs(V1-V2)≦Vth2 or abs(V1-V3)≦Vth3 holds for the predetermined threshold voltage differences Vth2 and Vth3, it is determined that there is a junction abnormality, and the process proceeds to step S303. If abs(V1-V2)>Vth2 and abs(V1-V3)>Vth3 hold, it is determined that there is no junction abnormality, and the process proceeds to step S305. The threshold voltage differences Vth2 and Vth3 can be set by the same method as the threshold voltage difference Vth according to the first embodiment.

[0061] In step S303, it is determined that there is a fault in the shunt resistor 400, and the process proceeds to step S404, where the energizing current is limited or cut off. As a result, the monitoring device 20 controls the first relay RL1 and the second relay RL2 to an open state, and ends the process.

[0062] In step S305, it is determined that there is no failure in the shunt resistor 400, and the process proceeds to step S406, where the second voltage V2 and the third voltage V3 are corrected, and the process ends.

[0063] In the shunt resistor 400, the second detection points 417h and 427h are provided on the end sides of the first electrode 110 and the second electrode 120 in the positive direction in the y-axis direction, and the second detection points 418h and 428h are provided on the end sides of the first electrode 110 and the second electrode 120 in the negative direction in the y-axis direction. Therefore, when a connection abnormality occurs at the end side in the positive direction in the y-axis direction of each conductive junction of the shunt resistor 400, the value of the second voltage V2 gradually approaches the first voltage V1, and the difference between them becomes small, so that the occurrence of the connection abnormality can be detected. When a connection abnormality occurs at the end side in the negative direction in the y-axis direction of each conductive junction of the shunt resistor 400, the value of the third voltage V3 gradually approaches the first voltage V1, and the difference between them becomes small, so that the occurrence of the connection abnormality can be detected.

[0064] The resistor included in the shunt resistor 400 may be configured to have the same structure as the reduced portion 231 according to the third embodiment. The reduced portion 231 may be provided on the end sides of the first electrode 110 and the second electrode 120 in the positive and negative directions of the y axis. By providing the reduced portion 231 to increase the current density, it is possible to detect a change in the detection voltage at the second detection point located on the upper surface thereof with good sensitivity.

[0065] In the above-described embodiments, the first and second solder parts 114, 124 extend continuously from one end side to the other end side of the first and second electrodes 110, 120 in the y-axis direction, respectively, but may be divided into several parts. When the solder parts are divided into several parts, it is preferable to configure the first and second solder parts 114, 124 so that the solder parts are provided at the ends in the positive and negative directions of the y-axis. Furthermore, if the first through hole 113 is provided at approximately the center of the first electrode 110 in the y-axis direction and the second through hole 123 is provided in the second electrode 120 at approximately the center of the second electrode 120 in the y-axis direction, the current density at the second detection point becomes high, so that the change in the detection voltage at the second detection point can be detected with higher sensitivity, but the first through hole 113 and the second through hole 123 do not have to be provided. In addition, when the fault determination unit 21 determines that there is a connection abnormality in each conductive joint included in the shunt resistor 400, the control unit 23 determines to limit or cut off the current passing through the shunt resistor, but this is not limiting. When the fault determination unit 21 determines that there is a connection abnormality in each conductive joint included in the shunt resistor 400, the control unit 23 may be configured to immediately cut off the current passing through the shunt resistor without relying on software for determination.

[0066] The control unit and the method described in the present disclosure may be realized by a special-purpose computer provided by configuring a processor and a memory programmed to execute one or more functions embodied in a computer program. Alternatively, the control unit and the method described in the present disclosure may be realized by a special-purpose computer provided by configuring a processor with one or more dedicated hardware logic circuits. Alternatively, the control unit and the method described in the present disclosure may be realized by one or more special-purpose computers configured by a combination of a processor and a memory programmed to execute one or more functions and a processor configured with one or more hardware logic circuits. In addition, the computer program may be stored in a computer-readable non-transitory tangible recording medium as instructions executed by a computer.

[0067] Characteristic configurations extracted from each of the above-described embodiments will be described below. [Configuration 1] A plate-shaped resistor (130, 230), a first electrode (110) and a second electrode (120) connected to both sides of the resistor in a first direction along a plate surface of the resistor; a substrate (140, 340, 440) having a pair of voltage detection points (116h, 126h, 117h, 127h, 316h, 326h, 317h, 327h, 416h, 426h, 417h, 427h, 418h, 428h) disposed on the resistor and each of the electrodes and provided on the first electrode side and the second electrode side, respectively; The present invention is applied to a shunt resistor (100, 200, 300, 400) in which the resistor and each of the electrodes, and each of the electrodes and the substrate are joined by conductive joints (111, 121, 114, 124) along a second direction perpendicular to the first direction, A monitoring device (20) for a shunt resistor that measures a voltage between the first electrode side and the second electrode side of the resistor based on detection voltages at the pair of voltage detection points, the substrate is provided with first detection points (116h, 126h, 316h, 326h, 416h, 426h) and second detection points (117h, 127h, 317h, 327h, 417h, 427h, 418h, 428h) located closer to the ends of the electrodes than the first detection points in the second direction, as the pair of voltage detection points; A monitoring device for a shunt resistor comprising: a fault determination unit (21) that determines a connection abnormality of the conductive joint based on the detected voltages at the first detection point and the second detection point. [Configuration 2] In the shunt resistor, a reduced portion (231) is provided at an end in the second direction, where the resistor is not present between the first electrode and the second electrode, or where the resistor is locally thinned, 2. The shunt resistor monitoring device according to claim 1, wherein the second detection point is provided on the substrate near the reduced portion. [Configuration 3] The shunt resistor has the reduced portion only at one end side of both ends in the second direction, The shunt resistor monitoring device according to configuration 2, wherein the second detection point is provided on the substrate only near the end on the reduced portion side of both ends in the second direction. [Configuration 4] The second detection point is a detection point of the pair of voltage detection points, one of which is a detection point near a first end in the second direction on the first electrode side, and the other voltage detection point is a detection point near a second end on the opposite side to the first end in the second direction. [Configuration 5] 3. The shunt resistor monitoring device according to configuration 1 or 2, wherein the second detection points are provided on the substrate on both sides of the first detection point in the second direction. [Configuration 6] The shunt resistor monitoring device according to any one of configurations 1 to 5, further comprising a correction unit (22) that corrects at least one of the detection voltage at the first detection point and the detection voltage at the second detection point so that the detection voltage at the first detection point and the detection voltage at the second detection point are substantially identical. [Configuration 7] A plate-shaped resistor (130, 230), a first electrode (110) and a second electrode (120) connected to both sides of the resistor in a first direction along a plate surface of the resistor; a substrate (140, 340, 440) having a pair of voltage detection points (116h, 126h, 117h, 127h, 316h, 326h, 317h, 327h, 416h, 426h, 417h, 427h, 418h, 428h) disposed on the resistor and each of the electrodes and provided on the first electrode side and the second electrode side, respectively; The resistor and each of the electrodes, and each of the electrodes and the substrate are joined by conductive joints (111, 121, 114, 124) along a second direction perpendicular to the first direction, a monitoring program for a shunt resistor (100, 200, 300, 400) in which first detection points (116h, 126h, 316h, 326h, 416h, 426h) and second detection points (117h, 127h, 317h, 327h, 417h, 427h, 418h, 428h) positioned closer to the ends of the electrodes than the first detection points in the second direction are provided on the board as the pair of voltage detection points, On the computer, a detection step of measuring a voltage between the first electrode side and the second electrode side of the resistor based on detected voltages at the pair of voltage detection points; and a fault determination step of determining whether or not the conductive joint is abnormal based on the detected voltages at the first detection point and the second detection point. [Configuration 8] A plate-shaped resistor (130, 230), a first electrode (110) and a second electrode (120) connected to both sides of the resistor in a first direction along a plate surface of the resistor; a substrate (140, 340, 440) having a pair of voltage detection points (116h, 126h, 117h, 127h, 316h, 326h, 317h, 327h, 416h, 426h, 417h, 427h, 418h, 428h) disposed on the resistor and each of the electrodes and provided on the first electrode side and the second electrode side, respectively; The resistor and each of the electrodes, and each of the electrodes and the substrate are joined by conductive joints (111, 121, 114, 124) along a second direction perpendicular to the first direction, The substrate is provided with a shunt resistor (100, 200, 300, 400) having a pair of voltage detection points, including first detection points (116h, 126h, 316h, 326h, 416h, 426h) and second detection points (117h, 127h, 317h, 327h, 417h, 427h, 418h, 428h) located closer to the ends of the electrodes than the first detection points in the second direction. [Explanation of symbols]

[0068] 20...monitoring device, 21...fault determination unit, 100, 200, 300, 400...shunt resistor, 110...first electrode, 120...second electrode, 111, 121...first and second welded parts, 114, 124...first and second soldered parts, 130, 230...resistor, 116h, 126h, 316h, 326h, 416h, 426h...first detection point, 117h, 127h, 317h, 327h, 417h, 427h, 418h, 428h...second detection point

Claims

1. A plate-shaped resistor (130, 230), a first electrode (110) and a second electrode (120) connected to both sides of the resistor in a first direction along a plate surface of the resistor; a substrate (140, 340, 440) disposed on top of the resistor and each of the electrodes and having a pair of voltage detection points provided on the first electrode side and the second electrode side, The present invention is applied to a shunt resistor (100, 200, 300, 400) in which the resistor and each of the electrodes, and the electrodes and the substrate are joined by conductive joints (111, 121, 114, 124) along a second direction perpendicular to the first direction, A monitoring device (20) for a shunt resistor, which measures a voltage between the first electrode side and the second electrode side of the resistor based on detection voltages at the pair of voltage detection points, the substrate is provided with a first detection point and a second detection point located closer to an end of each of the electrodes than the first detection point in the second direction, as the pair of voltage detection points; A monitoring device for a shunt resistor comprising: a fault determination unit (21) that determines a connection abnormality of the conductive joint based on the detected voltages of the first detection point and the second detection point.

2. In the shunt resistor, a reduced portion (231) is provided at an end in the second direction, where the resistor is not present between the first electrode and the second electrode, or where the resistor is locally thinned, 2. The shunt resistor monitoring device according to claim 1, wherein the second detection point is provided on the substrate near the reduced portion.

3. The shunt resistor is provided with the reduced portion only at one end side of both ends in the second direction, The shunt resistor monitoring device according to claim 2 , wherein the second detection points are provided on the substrate only near the end on the reduced portion side of both ends in the second direction.

4. The second detection point is a detection point of the pair of voltage detection points, one of which is a detection point near a first end in the second direction on the first electrode side, and the other voltage detection point is a detection point near a second end on the opposite side to the first end in the second direction.

5. The shunt resistor monitoring device according to claim 1 , wherein the second detection points are provided on the substrate on both sides of the first detection point in the second direction.

6. A shunt resistor monitoring device as described in any one of claims 1 to 3, further comprising a correction unit (22) that corrects at least one of the detection voltage at the first detection point and the detection voltage at the second detection point so that the detection voltage at the first detection point and the detection voltage at the second detection point are approximately identical.

7. A plate-shaped resistor (130, 230), a first electrode (110) and a second electrode (120) connected to both sides of the resistor in a first direction along a plate surface of the resistor; a substrate (140, 340, 440) disposed on top of the resistor and each of the electrodes and having a pair of voltage detection points provided on the first electrode side and the second electrode side, The resistor and each electrode, and the electrodes and the substrate are joined by conductive joints (111, 121, 114, 124) along a second direction perpendicular to the first direction, a monitoring program for a shunt resistor (100, 200, 300, 400) in which a first detection point and a second detection point located closer to an end of each electrode than the first detection point in the second direction are provided on the board as the pair of voltage detection points, On the computer, a detection step of measuring a voltage between the first electrode side and the second electrode side of the resistor based on detected voltages at the pair of voltage detection points; and a fault determination step of determining whether or not the conductive joint is abnormal based on the detected voltages at the first detection point and the second detection point.

8. A plate-shaped resistor (130, 230), a first electrode (110) and a second electrode (120) connected to both sides of the resistor in a first direction along a plate surface of the resistor; a substrate (140, 340, 440) disposed on top of the resistor and each of the electrodes and having a pair of voltage detection points provided on the first electrode side and the second electrode side, The resistor and each electrode, and the electrodes and the substrate are joined by conductive joints (111, 121, 114, 124) along a second direction perpendicular to the first direction, The substrate is provided with a shunt resistor (100, 200, 300, 400) having a pair of voltage detection points, a first detection point and a second detection point located closer to the end of each electrode than the first detection point in the second direction.

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