Current detection device

Abstract

To provide a shunt resistor and current sensing device, which allow for accurately measuring current flowing through the shunt resistor even if the temperature of the shunt resistor changes.SOLUTION: A current sensing unit 2 comprises voltage sensing terminals 8A, 8B provided at first characteristic points on electrodes 6, 7, where a resistance-temperature coefficient of a shunt resistor 1 is a first coefficient, and voltage sensing terminals 8C, 8D provided at second characteristic points on the electrodes 6, 7, where the resistance-temperature coefficient of the shunt resistor 1 is a second coefficient, the first coefficient having a numerical value different from that of the second coefficient.SELECTED DRAWING: Figure 9

Description

[Technical Field]

[0001] The present invention relates to a shunt resistor and a current detection device. [Background technology]

[0002] Shunt resistors are widely used for current detection. To enable current detection that is less affected by temperature fluctuations, shunt resistors are required to have a temperature coefficient of resistance (TCR) as close to 0 as possible. The temperature coefficient of resistance (TCR) is an index that indicates the rate of change in resistance value due to temperature change, and the closer the TCR is to 0, the smaller the change in resistance value becomes. To improve the TCR of shunt resistors, alloys with low TCR, such as Manganin (registered trademark), are sometimes used as the resistor material.

[0003] Current detection devices equipped with shunt resistors are used in a variety of applications, including inverters, converters, battery management systems (BMS) for electric vehicles, and battery storage systems (BSS) for power grids. In particular, for applications that monitor battery energy storage, initial measurement accuracy (factory adjustment accuracy), measurement accuracy with respect to temperature fluctuations, and measurement accuracy with respect to aging are considered more important than for other applications. Current detection devices affect the battery capacity design required for the entire system, which in turn determines system costs. Therefore, current detection devices are required to have high measurement accuracy over a wide range of currents. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2003-518763 Summary of the Invention [Problem to be solved by the invention]

[0005] The current detection board detects current by measuring the voltage drop at the voltage measurement point of the shunt resistor. However, the resistance value of the shunt resistor changes depending on temperature. In other words, even if the current flowing through the shunt resistor is constant, the detected voltage changes depending on temperature. As a result, the current measurement accuracy decreases.

[0006] Therefore, the present invention is capable of accurately detecting the current flowing through the shunt resistor even if the temperature of the shunt resistor changes. Ruden A flow detection device is provided. [Means for solving the problem]

[0007] In one embodiment, a shunt resistor is provided that has a resistor and a first electrode and a second electrode connected to both sides of the resistor, and that includes a first voltage detection terminal and a second voltage detection terminal provided at a first characteristic position of the first electrode and the second electrode where the resistance temperature coefficient of the shunt resistor is a first coefficient, and a third voltage detection terminal and a fourth voltage detection terminal provided at a second characteristic position of the first electrode and the second electrode where the resistance temperature coefficient of the shunt resistor is a second coefficient, and the first coefficient and the second coefficient are different numerical values. In one embodiment, the first coefficient is a negative number and the second coefficient is a positive number. In one embodiment, either the first voltage detection terminal and the third voltage detection terminal provided on the first electrode, or the second voltage detection terminal and the fourth voltage detection terminal provided on the second electrode, is a common voltage detection terminal.

[0008] In one embodiment, a shunt resistor having a resistor and a first electrode and a second electrode connected to both sides of the resistor, and a current detection unit electrically connected to the shunt resistor, wherein the current detection unit has first and second voltage detection contacts electrically connected to negative characteristic positions of the first and second electrodes where the temperature coefficient of resistance of the shunt resistor is negative, third and fourth voltage detection contacts electrically connected to positive characteristic positions of the first and second electrodes where the temperature coefficient of resistance of the shunt resistor is positive, and third and fourth voltage detection contacts electrically connected to the first, second, third and fourth voltage detection contacts, respectively. There is provided a current detection device comprising: a first voltage signal wiring, a second voltage signal wiring, a third voltage signal wiring, and a fourth voltage signal wiring; a resistor connected to at least one of the first voltage signal wiring, the second voltage signal wiring, the third voltage signal wiring, and the fourth voltage signal wiring; a first voltage signal merging wiring that merges voltage signals from the first voltage signal wiring and the third voltage signal wiring; and a second voltage signal merging wiring that merges voltage signals from the second voltage signal wiring and the fourth voltage signal wiring, wherein the resistor has a resistance value that makes the resistance temperature coefficient of the shunt resistor, calculated from the voltage signals from the first voltage signal merging wiring and the second voltage signal merging wiring, approach zero.

[0009] In one embodiment, a shunt resistor includes a resistor and a first electrode and a second electrode connected to both sides of the resistor, and a current detection unit electrically connected to the shunt resistor, the current detection unit including first and second voltage detection contacts electrically connected to negative characteristic positions of the first and second electrodes where the temperature coefficient of resistance of the shunt resistor is negative, third and fourth voltage detection contacts electrically connected to positive characteristic positions of the first and second electrodes where the temperature coefficient of resistance of the shunt resistor is positive, and a current calculator to which voltage signals from the first, second, third, and fourth voltage detection contacts are input, a current detection device configured to correct at least one of the negative characteristic side detection voltage between the first voltage detection contact and the second voltage detection contact and the positive characteristic side detection voltage between the third voltage detection contact and the fourth voltage detection contact, which are calculated from the voltage signal, by multiplying the negative characteristic side detection voltage between the first voltage detection contact and the second voltage detection contact and the positive characteristic side detection voltage between the third voltage detection contact and the fourth voltage detection contact by a correction coefficient, and to determine a current flowing through the shunt resistor based on a composite detection voltage calculated from the negative characteristic side detection voltage and the positive characteristic side detection voltage, at least one of which has been corrected, and the known resistance value of the shunt resistor, wherein the correction coefficient is a value that brings the resistance temperature coefficient of the shunt resistor, calculated from the composite detection voltage, closer to 0.

[0010] In one embodiment, a current detection device is provided, comprising: a shunt resistor having a resistor and a first electrode and a second electrode connected to either side of the resistor; and a current detection unit electrically connected to the shunt resistor, wherein the current detection unit comprises first and second voltage detection contacts electrically connected to first characteristic positions of the first and second electrodes where the resistance temperature coefficient of the shunt resistor is a first coefficient; third and fourth voltage detection contacts electrically connected to second characteristic positions of the first and second electrodes where the resistance temperature coefficient of the shunt resistor is a second coefficient; and a current calculator to which voltage signals from the first, second, third, and fourth voltage detection contacts are input, wherein the current calculator derives a current value flowing through the shunt resistor from a first characteristic side detection voltage between the first and second voltage detection contacts and a second characteristic side detection voltage between the third and fourth voltage detection contacts, which are calculated from the voltage signals.

[0011] In one aspect, the current calculator includes a current calculation formula for calculating a value of a current flowing through the shunt resistor from the first characteristic side detected voltage and the second characteristic side detected voltage. In one embodiment, the current calculator includes a data table of the relationship between the first characteristic side detected voltage, the second characteristic side detected voltage, and the value of the current flowing through the shunt resistor. In one embodiment, the current calculator has a function of deriving the temperature of the shunt resistor from the first characteristic side detected voltage and the second characteristic side detected voltage. [Effects of the Invention]

[0012] According to the present invention, by selecting the resistance value of the resistor, the temperature coefficient of resistance (TCR) of the shunt resistor can be made close to 0, thereby reducing the influence of the temperature of the shunt resistor and enabling the current flowing through the shunt resistor to be accurately determined. Furthermore, according to the present invention, by multiplying the detected voltage by a correction coefficient, the temperature coefficient of resistance (TCR) of the shunt resistor is brought closer to 0, thereby reducing the influence of the temperature of the shunt resistor and enabling the current flowing through the shunt resistor to be accurately determined. Furthermore, according to the present invention, the current flowing through the shunt resistor can be accurately determined from the first characteristic side detected voltage and the second characteristic side detected voltage. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a plan view schematically illustrating an embodiment of a shunt resistor. [Figure 2] FIG. 2 is a perspective view of the shunt resistor shown in FIG. [Figure 3] 10 is a graph showing the relationship between the voltage detection position and the voltage when the temperature of the shunt resistor is 20° C. [Figure 4] 10 is a graph showing the relationship between the voltage detection position and the voltage when the temperature of the shunt resistor is 150° C. [Figure 5] 10 is a graph showing the relationship between a temperature-dependent voltage change of a shunt resistor and a voltage detection position. [Figure 6] 6 is a graph showing the rate of change of the resistance value of the shunt resistor at the voltage detection positions P1, P2, and P3 shown in FIG. 5. [Figure 7] 2 is a perspective view showing an embodiment of a current detection device including the shunt resistor shown in FIG. 1 and a current detection portion disposed on the shunt resistor. FIG. [Figure 8] FIG. 8 is a plan view of the current detection device shown in FIG. [Figure 9] FIG. 10 is a plan view illustrating an embodiment of a current detector electrically connected to a shunt resistor. [Figure 10] FIG. 10 is a plan view schematically showing another embodiment of the shunt resistor. [Figure 11] FIG. 10 is a plan view schematically showing still another embodiment of the shunt resistor. [Figure 12] 1 is a graph showing an example of a temperature coefficient of resistance of a shunt resistor. [Figure 13]10 is a graph for explaining how the temperature coefficient of resistance of the shunt resistor is adjusted by the first resistor and the second resistor which are positive-side resistors. [Figure 14] 10 is a graph showing another example of the temperature coefficient of resistance of a shunt resistor. [Figure 15] 10 is a graph illustrating how the temperature coefficient of resistance of the shunt resistor is adjusted by the third resistor and the fourth resistor which are negative-side resistors. [Figure 16] FIG. 10 is a plan view showing another embodiment of the current measuring device. [Figure 17] 10 is a graph illustrating how the resistance temperature coefficient of a shunt resistor is corrected. [Figure 18] 10 is a graph showing the relationship between the voltage between the first voltage detection junction and the second voltage detection junction and the temperature of the shunt resistor. [Figure 19] 10 is a graph showing the relationship between the voltage between the third voltage detection junction and the fourth voltage detection junction and the temperature of the shunt resistor. [Figure 20] FIG. 10 is a plan view schematically showing another embodiment of the shunt resistor. [Figure 21] FIG. 10 is a plan view schematically showing still another embodiment of the shunt resistor. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a plan view schematically illustrating one embodiment of a shunt resistor, and FIG. 2 is a perspective view of the shunt resistor shown in FIG. 1. As shown in FIGS. 1 and 2, the shunt resistor 1 includes a resistive element 5 having a predetermined thickness and width, and a pair of first and second electrodes 6 and 7 made of a highly conductive metal connected to both sides 5a and 5b of the resistive element 5. Specifically, the first electrode 6 is connected to one side 5a of the resistive element 5, and the second electrode 7 is connected to the other side 5b of the resistive element 5. The configuration of the second electrode 7 is the same as that of the first electrode 6, and the first and second electrodes 6 and 7 are arranged symmetrically with respect to the resistive element 5. Hereinafter, the first and second electrodes 6 and 7 may be simply referred to as electrodes 6 and 7.

[0015] Examples of materials for the resistor 5 include alloys such as copper-nickel alloys, copper-manganese alloys, iron-chromium alloys, and nickel-chromium alloys. An example of a highly conductive metal that forms the electrodes 6 and 7 is copper (Cu). Both ends 5a and 5b of the resistor 5 are connected (joined) to the electrodes 6 and 7 by means of welding (e.g., electron beam welding, laser beam welding, or brazing) or the like.

[0016] In this embodiment, the thickness of the resistor 5 is smaller than the thickness of the electrodes 6 and 7, and the front side surface of the resistor 5 is lower than the front side surfaces of the electrodes 6 and 7. However, in one embodiment, the thickness of the resistor 5 may be the same as the thickness of the electrodes 6 and 7.

[0017] The electrodes 6 and 7 have slits 11 and 12, respectively. The slits 11 and 12 extend parallel to both ends 5a and 5b of the resistor 5. In this embodiment, the slits 11 and 12 are cutouts extending linearly. The slit 11 extends linearly from the side surface 6a of the electrode 6 toward the center of the electrode 6, and the slit 12 extends linearly from the side surface 7a of the electrode 7 toward the center of the electrode 7. The slits 11 and 12 are arranged symmetrically with respect to the resistor 5. In this embodiment, the slits 11 and 12 have the same width and length. The length of the slits 11 and 12 refers to the dimension of the slits 11 and 12 along both ends 5a and 5b of the resistor 5.

[0018] By forming slits 11 and 12 in the electrodes 6 and 7, the current flowing through the shunt resistor 1 avoids the slits 11 and 12. The current between the slits 11 and 12 flows around from the side opposite the slits, and the current density decreases closer to the side surfaces 6a and 7a. The state of the current flowing through the shunt resistor 1 is different from the state of the current flowing through a shunt resistor 1 without slits. In addition, the potential distribution of the shunt resistor 1 is different from the potential distribution of a shunt resistor 1 without slits. As a result, the temperature coefficient of resistance (TCR) of the shunt resistor 1 varies significantly depending on the position at which the voltage between the slits 11 and 12 is detected, and is different from the temperature coefficient of resistance (TCR) of the shunt resistor 1 when no slits are formed in the electrodes.

[0019] The shunt resistor 1 includes multiple pairs of voltage detection terminals 16A, 16B, 16C, and 16D fixed to a pair of electrodes 6 and 7. These voltage detection terminals 16A to 16D are pin terminals protruding from the electrodes 6 and 7. The voltage detection terminals 16A and 16C are fixed to the electrode 6, and the voltage detection terminals 16B and 16D are fixed to the electrode 7. The voltage detection terminals 16A to 16D are arranged along both sides 5a and 5b of the resistor 5. In this embodiment, two pairs of voltage detection terminals are provided. One pair of voltage detection terminals 16A and 16B is arranged on the slit side, and the other pair of voltage detection terminals 16C and 16D is arranged on the opposite side to the slit.

[0020] The temperature coefficient of resistance (TCR) of the shunt resistor 1 shown in Figures 1 and 2 varies depending on the voltage detection position on the electrodes 6 and 7. Figure 3 is a graph showing the relationship between the voltage detection position and the voltage at the voltage detection position when the temperature of the shunt resistor 1 is 20°C, and Figure 4 is a graph showing the relationship between the voltage detection position and the voltage when the temperature of the shunt resistor 1 is 150°C. The voltage detection position is the position in the width direction of the shunt resistor 1 along both ends 5a and 5b of the resistor 5. For example, the voltage detection positions are located on the dashed lines L1 and L2 in Figure 1, and Figures 3 and 4 are graphs showing the relationship between the voltage detection position and the voltage on the dashed lines L1 and L2. In Figures 3 and 4, the current flowing through the shunt resistor 1 is constant in the direction from electrode 7 to electrode 6.

[0021] The "resistance value of shunt resistor 1," "rate of change of the resistance value of shunt resistor 1," and "temperature coefficient of resistance of shunt resistor 1" are values ​​calculated based on Ohm's law from the current flowing through shunt resistor 1 and the detected voltage.

[0022] As can be seen from Figures 3 and 4, the detected voltage varies depending on the voltage detection position (widthwise position). In other words, the resistance value of the shunt resistor 1 varies depending on the voltage detection position (widthwise position). Furthermore, the way in which the detected voltage varies with temperature differs between the position on the slit side and the position on the anti-slit side. Specifically, as can be seen from comparing Figures 3 and 4, when the voltage detection position is on the slit side, the detected voltage decreases as the temperature of the shunt resistor 1 increases from 20°C to 150°C. On the other hand, when the voltage detection position is on the anti-slit side, the detected voltage increases as the temperature of the shunt resistor 1 increases from 20°C to 150°C.

[0023] Figure 5 is a graph showing the relationship between the temperature-dependent voltage change of the shunt resistor 1 and the voltage detection position. The temperature-dependent voltage change is the difference between the voltage at each voltage detection position when the temperature of the shunt resistor 1 is 150°C and the voltage at the same voltage detection position when the temperature of the shunt resistor 1 is 20°C. As can be seen from the graph in Figure 5, the detected voltage at voltage detection position P1 on the opposite side of the slit increases as the temperature of the shunt resistor 1 increases (i.e., the resistance value of the shunt resistor 1 increases). On the other hand, the detected voltage at voltage detection position P2 on the slit side decreases as the temperature of the shunt resistor 1 increases (i.e., the resistance value of the shunt resistor 1 decreases). Furthermore, there is a voltage detection position P3 where the detected voltage does not change regardless of the temperature change of the shunt resistor 1 (i.e., the resistance value of the shunt resistor 1 does not change).

[0024] FIG. 6 is a graph showing the rate of change in the resistance of the shunt resistor 1 calculated from the voltages detected at the voltage detection positions P1, P2, and P3 shown in FIG. 5. In FIG. 6, the vertical axis represents the rate of change in the resistance of the shunt resistor 1, and the horizontal axis represents the temperature of the shunt resistor 1. The slope of the graph of the rate of change in the resistance represents the temperature coefficient of resistance (TCR) of the shunt resistor 1. The TCR of the shunt resistor 1 calculated from the voltage detected at the voltage detection position P1 indicates that the resistance of the shunt resistor 1 increases with increasing temperature, while the TCR of the shunt resistor 1 calculated from the voltage detected at the voltage detection position P2 indicates that the resistance of the shunt resistor 1 decreases with increasing temperature. Furthermore, the TCR of the shunt resistor 1 calculated from the voltage detected at the voltage detection position P3 indicates that the resistance of the shunt resistor 1 does not change with increasing temperature.

[0025] In the following description, a resistance temperature coefficient indicating that the resistance value increases with increasing temperature is referred to as a positive resistance temperature coefficient, a resistance temperature coefficient indicating that the resistance value decreases with increasing temperature is referred to as a negative resistance temperature coefficient, and a resistance temperature coefficient indicating that the resistance value does not change with increasing temperature is referred to as a zero resistance temperature coefficient.

[0026] In the embodiment described below, two pairs of voltage detection terminals 16A to 16D are arranged at a position where a voltage is detected where the resistance temperature coefficient of the shunt resistor 1 is a positive value (hereinafter, this position is referred to as a positive characteristic position) and a position where a voltage is detected where the resistance temperature coefficient of the shunt resistor 1 is a negative value (hereinafter, this position is referred to as a negative characteristic position), and the detected voltage at the positive characteristic position and the detected voltage at the negative characteristic position are intentionally acquired.The detected voltage at the positive characteristic position and the detected voltage at the negative characteristic position are then corrected, and the corrected detected voltage at the positive characteristic position and the detected voltage at the negative characteristic position are further combined to approach a zero resistance temperature coefficient.

[0027] FIG. 7 is a perspective view showing one embodiment of a current detection device including the shunt resistor 1 shown in FIG. 1 and a current detection unit 2 arranged on the shunt resistor 1, and FIG. 8 is a plan view of the current detection device shown in FIG. 7. Current detection terminals 16A to 16D on a pair of electrodes 6, 7 are electrically connected to the current detection unit 2. The current detection unit 2 has a base plate 3 on which a current calculator 20 and other components are arranged. This base plate 3 is fixed to the current detection terminals 16A to 16D of the shunt resistor 1. An example of the base plate 3 is a printed circuit board made of a material such as glass epoxy.

[0028] The current detection unit 2 includes a first voltage detection contact 8A and a second voltage detection contact 8B electrically connected to a first current detection terminal 16A on the first electrode 6 and a second current detection terminal 16B on the second electrode 7, respectively, and a third voltage detection contact 8C and a fourth voltage detection contact 8D electrically connected to a third current detection terminal 16C on the first electrode 6 and a fourth current detection terminal 16D on the second electrode 7, respectively. In one embodiment, the current detection terminals 16A to 16D are inserted into holes formed in the base plate 3 and connected to the voltage detection contacts by a method such as soldering.

[0029] 9 is a plan view showing one embodiment of the current detection unit 2 electrically connected to the shunt resistor 1. The first voltage detection contact 8A and the second voltage detection contact 8B are connected via current detection terminals 16A and 16B to the negative characteristic positions of the first electrode 6 and the second electrode 7, where voltages are detected at which the temperature coefficient of resistance of the shunt resistor 1 becomes negative. At the negative characteristic positions, the detected voltage decreases as the temperature rises, and the resistance value of the shunt resistor 1 calculated from the detected voltage decreases.

[0030] The first voltage detection contact 8A and the first current detection terminal 16A are adjacent to the slit 11 of the first electrode 6, and the second voltage detection contact 8B and the second current detection terminal 16B are adjacent to the slit 12 of the second electrode 7. More specifically, the first voltage detection contact 8A and the first current detection terminal 16A are located between the slit 11 of the first electrode 6 and the resistor 5, and the second voltage detection contact 8B and the second current detection terminal 16B are located between the slit 12 of the second electrode 7 and the resistor 5.

[0031] The third voltage detection contact 8C and the fourth voltage detection contact 8D are connected via current detection terminals 16C and 16D to the positive characteristic positions of the first electrode 6 and the second electrode 7, where a voltage is detected at which the temperature coefficient of resistance of the shunt resistor 1 is positive. At the positive characteristic positions, the detected voltage increases with increasing temperature, and the resistance value of the shunt resistor 1 calculated from the detected voltage increases. The third voltage detection contact 8C, the fourth voltage detection contact 8D, the third current detection terminal 16C, and the fourth current detection terminal 16D are located away from the slits 11 and 12. More specifically, the third voltage detection contact 8C, the fourth voltage detection contact 8D, the third current detection terminal 16C, and the fourth current detection terminal 16D are located outside the area between the slits 11 and 12 and the resistor 5.

[0032] The negative characteristic position where the first voltage detection contact 8A and the second voltage detection contact 8B are connected via the current detection terminals 16A and 16B, and the positive characteristic position where the third voltage detection contact 8C and the fourth voltage detection contact 8D are connected via the current detection terminals 16C and 16D, can be determined based on the results of simulations or experiments to investigate the relationship between the voltage detection positions of the shunt resistor 1 and the temperature coefficient of resistance, as shown in Figures 3, 4, and 5.

[0033] In this embodiment, the first voltage detection contact 8A (first voltage detection terminal 16A) and the second voltage detection contact 8B (second voltage detection terminal 16B) form a pair that is arranged symmetrically with respect to the resistor 5, and the third voltage detection contact 8C (third voltage detection terminal 16C) and the fourth voltage detection contact 8D (fourth voltage detection terminal 16D) also form a pair that is arranged symmetrically with respect to the resistor 5. The first voltage detection contact 8A (first voltage detection terminal 16A), the second voltage detection contact 8B (second voltage detection terminal 16B), the third voltage detection contact 8C (third voltage detection terminal 16C), and the fourth voltage detection contact 8D (fourth voltage detection terminal 16D) are arranged along both sides 5a, 5b of the resistor 5 and adjacent to both sides 5a, 5b of the resistor 5.

[0034] The voltage detection contacts 8A to 8D (voltage detection terminals 16A to 16D) do not have to be arranged symmetrically with respect to the resistor 5, as long as they are positioned such that they exhibit a positive or negative temperature coefficient of resistance. In one embodiment, the voltage detection contacts 8A and 8C (voltage detection terminals 16A and 16C) may be common, as shown in FIG. 10, or the voltage detection contacts 8B and 8D (voltage detection terminals 16B and 16D) may be common, as shown in FIG. 11. For example, the common voltage detection contacts (voltage detection terminals) are arranged in positions where the potential does not fluctuate with temperature. In this embodiment, the first voltage detection contact 8A, the second voltage detection contact 8B, the third voltage detection contact 8C, and the fourth voltage detection contact 8D are formed as through-holes that penetrate from the back side to the front side of the base plate 3, and the current detection terminals 16A to 16D are inserted therethrough and electrically connected to the current detection terminals 16A to 16D by a method such as soldering. However, the electrical connection between the current detection position of the shunt resistor 1 and the voltage detection contact is not limited to the method of connecting by inserting the current detection terminal into the through hole, and other methods (for example, a method of surface-connecting the current detection position of the shunt resistor 1 and the voltage detection contact by soldering, etc.) may also be used.

[0035] The current detection unit 2 further includes a first voltage signal wire 9A, a second voltage signal wire 9B, a third voltage signal wire 9C, and a fourth voltage signal wire 9D connected to the first voltage detection contact 8A, the second voltage detection contact 8B, the third voltage detection contact 8C, and the fourth voltage signal wire 9D, respectively. These voltage signal wires 9A to 9D are arranged on the front side of the base plate 3.

[0036] The current detection unit 2 further includes a first resistor 10A, a second resistor 10B, a third resistor 10C, and a fourth resistor 10D connected to the first voltage signal wiring 9A, the second voltage signal wiring 9B, the third voltage signal wiring 9C, and the fourth voltage signal wiring 9D, respectively. These resistors 10A to 10D are also arranged on the front side of the base plate 3, similar to the voltage signal wirings 9A to 9D.

[0037] The current detection unit 2 includes a first voltage signal junction wiring 13 that junctions voltage signals transmitted through the first resistor 10A and the third resistor 10C, and a second voltage signal junction wiring 14 that junctions voltage signals transmitted through the second resistor 10B and the fourth resistor 10D. The first voltage signal junction wiring 13 is connected to the first voltage signal wiring 9A and the third voltage signal wiring 9C, and the second voltage signal junction wiring 14 is connected to the second voltage signal wiring 9B and the fourth voltage signal wiring 9D. A capacitor 19 is provided between the first voltage signal junction wiring 13 and the second voltage signal junction wiring 14. The voltage signal junction wirings 13 and 14 junction the voltage signal on the output side of the first resistor 10A and the voltage signal on the output side of the third resistor 10C, and junction the voltage signal on the output side of the second resistor 10B and the voltage signal on the output side of the fourth resistor 10D, thereby forming respective junction voltage signals.

[0038] The current detection unit 2 further includes a current calculator 20 connected to the first voltage signal junction wiring 13 and the second voltage signal junction wiring 14. The current calculator 20 is configured to determine the current flowing through the shunt resistor 1 from a composite detection voltage calculated from the composite voltage signal and the known resistance value of the shunt resistor 1. In one embodiment, an amplifier for amplifying the voltage signal may be provided between the resistors 10A to 10D and the current calculator 20.

[0039] The current calculator 20 includes a storage device 20a storing a program and a computing device 20b that executes calculations according to instructions included in the program. The current calculator 20 is composed of at least one small computer. The storage device 20a includes a main storage device such as a random access memory (RAM) and an auxiliary storage device such as a hard disk drive (HDD) or a solid-state drive (SSD). An example of the computing device 20b is a central processing unit (CPU). However, the specific configuration of the current calculator 20 is not limited to these examples. In one embodiment, the current calculator 20 may be provided separately from the base plate 3. Although not shown, the current detector 2 may include a connector connected to the output signal wiring of the current calculator 20, and the output signal may be output from the base plate 3 via the connector.

[0040] The composite detected voltage is calculated from the composite voltage signals from the voltage signal junction wirings 13 and 14. The composite voltage signal from the voltage signal junction wiring 13 can be adjusted by the resistance values ​​of the first resistor 10A and the third resistor 10C, and the composite voltage signal from the voltage signal junction wiring 14 can be adjusted by the second resistor 10B and the fourth resistor 10D. In other words, the composite detected voltage calculated from the composite voltage signals from the voltage signal junction wirings 13 and 14 can be adjusted by the resistance values ​​of the resistors 10A to 10D.

[0041] The first resistor 10A and the second resistor 10B are negative-side resistors electrically connected to the first voltage detection contact 8A and the second voltage detection contact 8B, and the third resistor 10C and the fourth resistor 10D are positive-side resistors electrically connected to the third voltage detection contact 8C and the fourth voltage detection contact 8D. The negative-side resistors (i.e., the first resistor 10A and the second resistor 10B) or the positive-side resistors (i.e., the third resistor 10C and the fourth resistor 10D) have resistance values ​​that make the resistance temperature coefficient of the shunt resistor 1 calculated from the voltage signals from the first voltage signal merging wiring 13 and the second voltage signal merging wiring 14 approach zero.

[0042] 12 is a graph showing an example of the resistance temperature coefficient of the shunt resistor 1, with 25°C as the reference temperature, when the first resistor 10A, the second resistor 10B, the third resistor 10C, and the fourth resistor 10D all have the same resistance value. The symbol TCR2 represents the resistance temperature coefficient of the shunt resistor 1 calculated from the negative characteristic side detection voltage between the first voltage detection junction 8A and the second voltage detection junction 8B. More specifically, the symbol TCR1 represents the resistance temperature coefficient of the shunt resistor 1 calculated from the positive characteristic side detection voltage between the third voltage detection junction 8C and the fourth voltage detection junction 8D. More specifically, the symbol TCR1 represents the resistance temperature coefficient of the shunt resistor 1 calculated from the voltage signal on the output side of the positive side resistors, the third resistor 10C and the fourth resistor 10D.

[0043] The symbol TCR3 represents the temperature coefficient of resistance of the shunt resistor 1 calculated from the composite detected voltage. More specifically, it represents the temperature coefficient of resistance of the shunt resistor 1 calculated from the composite voltage signal from the voltage signal merging wires 13 and 14. The voltage signal on the output side of the first resistor 10A and the voltage signal on the output side of the third resistor 10C are combined by the voltage signal merging wires 13 and 14, and the voltage signal on the output side of the second resistor 10B and the voltage signal on the output side of the fourth resistor 10D are combined to form respective composite voltage signals. If the first resistor 10A, the second resistor 10B, the third resistor 10C, and the fourth resistor 10D all have the same resistance value, the voltage signal on the input side of the first resistor 10A and the voltage signal on the input side of the third resistor 10C are combined at a 1:1 ratio, and the voltage signal on the input side of the second resistor 10B and the input signal on the input side of the fourth resistor 10D are combined at a 1:1 ratio to form respective composite voltage signals. The combined detected voltage is calculated from the combined voltage signal from the voltage signal merging wires 13 and 14 .

[0044] 12, the temperature coefficient of resistance TCR1 calculated from the positive characteristic side detection voltage between the third voltage detection junction 8C and the fourth voltage detection junction 8D is a positive temperature coefficient of resistance, where the resistance value of the shunt resistor 1 increases with increasing temperature. The temperature coefficient of resistance TCR2 calculated from the negative characteristic side detection voltage between the first voltage detection junction 8A and the second voltage detection junction 8B is a negative temperature coefficient of resistance, where the resistance value of the shunt resistor 1 decreases with increasing temperature. The temperature coefficient of resistance TCR3 calculated from the composite detection voltage is a positive temperature coefficient of resistance, where the resistance value increases with increasing temperature.

[0045] 13, the temperature coefficient of resistance TCR3 approaches 0 by changing the resistance value of at least one of the first resistor 10A, second resistor 10B, third resistor 10C, and fourth resistor 10D electrically connected to the voltage detection contacts 8A to 8D. In this embodiment, the first resistor 10A and the second resistor 10B, which are negative-side resistors, have the same resistance value, and the third resistor 10C and the fourth resistor 10D, which are positive-side resistors, have the same resistance value. By changing the resistance value of either or both of the negative-side resistor and the positive-side resistor so that the resistance value of the negative-side resistor and the resistance value of the positive-side resistor are not the same, the temperature coefficient of resistance TCR3 can be brought closer to 0.

[0046] The first resistor 10A, the second resistor 10B, the third resistor 10C, and the fourth resistor 10D may be resistors whose resistance values ​​can be adjusted after connection. In this case, it is desirable to adjust the resistance value of at least one of the first resistor 10A, the second resistor 10B, the third resistor 10C, and the fourth resistor 10D until the temperature coefficient of resistance TCR3 becomes zero (until the slope of the graph showing TCR3 becomes zero). However, depending on the characteristics of the material of the resistor 5, the graph showing TCR3 may be curved. Therefore, the resistance values ​​of the first resistor 10A, the second resistor 10B, the third resistor 10C, and the fourth resistor 10D are selected so that the temperature coefficient of resistance TCR3 falls within an allowable range. The allowable range is a preset range that includes zero.

[0047] By selecting the resistance values ​​of the first resistor 10A, the second resistor 10B, the third resistor 10C, and the fourth resistor 10D in this manner, the temperature coefficient of resistance TCR3 of the shunt resistor 1 approaches 0 (preferably, the temperature coefficient of resistance TCR3 becomes 0), so that the current calculator 20 can accurately determine the current without being affected by the temperature of the shunt resistor 1.

[0048] 14 is a graph showing another example of the temperature coefficient of resistance of the shunt resistor 1 when the first resistor 10A, the second resistor 10B, the third resistor 10C, and the fourth resistor 10D all have the same resistance value and the reference temperature is 25° C. In this example, the temperature coefficient of resistance TCR3 of the shunt resistor 1 calculated from the composite detection voltage is a negative temperature coefficient of resistance.

[0049] 15, the temperature coefficient of resistance TCR3 approaches 0 by changing the resistance value of at least one of first resistor 10A, second resistor 10B, third resistor 10C, and fourth resistor 10D electrically connected to voltage detection contacts 8A to 8D. In this embodiment, first resistor 10A and second resistor 10B, which are negative-side resistors, have the same resistance value, and first resistor 10C and second resistor 10D, which are positive-side resistors, have the same resistance value. By changing the resistance value of either or both of the negative-side resistor and the positive-side resistor so that the resistance value of the negative-side resistor and the resistance value of the positive-side resistor are not the same, the temperature coefficient of resistance TCR3 can be brought closer to 0.

[0050] The first resistor 10A, the second resistor 10B, the third resistor 10C, and the fourth resistor 10D may be resistors whose resistance values ​​can be adjusted after connection. In this case, it is desirable to adjust the resistance value of at least one of the first resistor 10A, the second resistor 10B, the third resistor 10C, and the fourth resistor 10D until the temperature coefficient of resistance TCR3 becomes 0 (until the slope of the graph showing TCR3 becomes 0). However, depending on the characteristics of the material of the resistor 5, the graph showing TCR3 may be curved. Therefore, the resistance values ​​of the first resistor 10A, the second resistor 10B, the third resistor 10C, and the fourth resistor 10D are selected so that the temperature coefficient of resistance TCR3 falls within an allowable range. The allowable range is a preset range that includes 0.

[0051] The resistance values ​​of resistors 10A-10D are determined in advance through simulations or other methods. However, by using resistors with adjustable resistance values, it is possible to further adjust the resistance values ​​after the current detection device is completed (before shipping). Specifically, while a predetermined current is passed through shunt resistor 1, the temperature of shunt resistor 1 is changed and the composite detection voltage is measured by current calculator 20. The resistance values ​​of first resistor 10A and second resistor 10B and / or the resistance values ​​of third resistor 10C and fourth resistor 10D are adjusted in a direction that reduces the change in the composite detection voltage (i.e., in a direction that approaches zero the temperature coefficient of resistance TCR3). By adjusting the resistance values ​​in this way, the temperature coefficient of resistance of shunt resistor 1 approaches zero, allowing the current detection device to accurately measure the current without being affected by the temperature of shunt resistor 1.

[0052] In one embodiment, the negative characteristic position and the positive characteristic position may be positions where the influence of the skin effect due to frequency is small. The negative characteristic position is a position where the temperature coefficient of resistance is negative and the influence of the skin effect due to frequency is small, and the positive characteristic position is a position where the temperature coefficient of resistance is positive and the influence of the skin effect due to frequency is small. This makes it possible to accurately measure the current without being influenced by the temperature of the shunt resistor 1 or the skin effect due to frequency.

[0053] Next, another embodiment of the current measuring device will be described with reference to Figures 16 and 17. The configuration and operation of this embodiment, which will not be specifically described, are the same as those of the embodiment described with reference to Figures 1 to 15, and therefore redundant description will be omitted. Figure 16 is a plan view showing another embodiment of the current measuring device.

[0054] The first resistor 10A, the second resistor 10B, the third resistor 10C, and the fourth resistor 10D shown in Fig. 16 are resistors having fixed resistance values. The first voltage signal junction wiring 13 and the second voltage signal junction wiring 14 shown in Fig. 9 are not provided. The first voltage signal wiring 9A, the second voltage signal wiring 9B, the third voltage signal wiring 9C, and the fourth voltage signal wiring 9D are connected to a current calculator 20.

[0055] First resistor 10A, second resistor 10B, third resistor 10C, and fourth resistor 10D are attached to first voltage signal wire 9A, second voltage signal wire 9B, third voltage signal wire 9C, and fourth voltage signal wire 9D, respectively. Current calculator 20 is connected to voltage detection contacts 8A-8D via voltage signal wires 9A-9D and resistors 10A-10D. In one embodiment, an amplifier for amplifying the voltage signal may be provided between resistors 10A-10D and current calculator 20.

[0056] The current calculator 20 converts the detected voltage of an analog signal calculated from the voltage signal transmitted through the voltage signal wiring 9A to 9D into a digital signal, reads it, and performs a correction process on the detected voltage of the digital signal, thereby performing the same operation as changing the resistance values ​​of the resistors 10A to 10D in the above-mentioned embodiment and adjusting the composite detected voltage.

[0057] More specifically, current calculator 20 calculates a corrected negative characteristic side detected voltage by multiplying the negative characteristic side detected voltage between first voltage detection contact 8A and second voltage detection contact 8B (i.e., the detected voltage at the negative characteristic position) calculated from the voltage signal by a negative side correction coefficient. Similarly, current calculator 20 calculates a corrected positive characteristic side detected voltage by multiplying the positive characteristic side detected voltage between third voltage detection contact 8C and fourth voltage detection contact 8D (i.e., the detected voltage at the positive characteristic position) calculated from the voltage signal by a positive side correction coefficient. The negative characteristic side detected voltage between first voltage detection contact 8A and second voltage detection contact 8B is calculated from the voltage signal transmitted through first voltage signal wire 9A and second voltage signal wire 9B, and the positive characteristic side detected voltage between third voltage detection contact 8C and fourth voltage detection contact 8D is calculated from the voltage signal transmitted through third voltage signal wire 9C and fourth voltage signal wire 9D.

[0058] The positive-side correction coefficient and negative-side correction coefficient are values ​​calculated by a simulation or the like to bring the resistance temperature coefficient of shunt resistor 1, calculated from the composite detected voltage, closer to 0. This composite detected voltage is calculated by combining the corrected negative characteristic side detected voltage and the corrected negative characteristic side detected voltage. Current calculator 20 determines the current flowing through shunt resistor 1 based on the composite detected voltage calculated by combining the corrected negative characteristic side detected voltage and the corrected positive characteristic side detected voltage, and the known resistance value of shunt resistor 1.

[0059] This internal processing of the current calculator 20 achieves the same results as the adjustment of the resistors 10A-10D described with reference to Figures 12 to 15. When the negative characteristic side detected voltage (detected voltage at the negative characteristic position) between the first voltage detection contact 8A and the second voltage detection contact 8B, calculated from the voltage signal, is multiplied by the negative side correction coefficient, the ratio of the negative characteristic side detected voltage to the positive characteristic side detected voltage in the composite detected voltage changes. Similarly, when the positive characteristic side detected voltage (detected voltage at the positive characteristic position) between the third voltage detection contact 8C and the fourth voltage detection contact 8D, calculated from the voltage signal, is multiplied by the positive side correction coefficient, the ratio of the positive characteristic side detected voltage to the negative characteristic side detected voltage in the composite detected voltage changes.

[0060] The temperature coefficient of resistance TCR3 is calculated from a composite detected voltage obtained by combining the corrected negative characteristic side detected voltage and the corrected positive characteristic side detected voltage. The current calculator 20 calculates a composite detected voltage by combining the corrected negative characteristic side detected voltage and the corrected positive characteristic side detected voltage, and calculates the current flowing through the shunt resistor 1 from this composite detected voltage and the known resistance value of the shunt resistor 1. According to this embodiment, as shown in FIG. 17, the temperature coefficient of resistance TCR3 of the shunt resistor 1 approaches 0, so the current calculator 20 can accurately determine the current without being affected by the temperature of the shunt resistor 1.

[0061] The negative and positive correction coefficients may be determined in advance by simulation or the like, or may be determined by inspection after the current detection device is completed (before shipping). Specifically, a predetermined current is passed through the shunt resistor 1, and the combined detected voltage is measured by the current calculator 20 while the temperature of the shunt resistor 1 is changed, and the negative and positive correction coefficients are determined so that the change in the combined detected voltage becomes small (i.e., the resistance temperature coefficient TCR3 approaches 0).

[0062] In one embodiment, the negative characteristic side detected voltage or the positive characteristic side detected voltage may be multiplied by either the negative side correction coefficient or the positive side correction coefficient to calculate the corrected negative characteristic side detected voltage or the corrected positive characteristic side detected voltage. Even in this case, the correction coefficient multiplied by the negative characteristic side detected voltage or the positive characteristic side detected voltage is a coefficient that can bring the temperature coefficient of resistance TCR3 closer to zero. Specifically, while a predetermined current is passed through the shunt resistor 1 and the temperature of the shunt resistor 1 is changed, the current calculator 20 measures the composite detected voltage, and a correction coefficient is determined that reduces the change in the composite detected voltage (i.e., brings the temperature coefficient of resistance TCR3 closer to zero).

[0063] Next, still another embodiment of the current measuring device will be described with reference to Figures 18 and 19. The configuration and operation of this embodiment, which will not be specifically described, are the same as those of the embodiment described with reference to Figures 16 and 17, and therefore redundant description will be omitted.

[0064] In this embodiment, a current calculation formula is used to directly calculate the current flowing through the shunt resistor 1. That is, the current calculator 20 includes a current calculation formula that calculates the current flowing through the shunt resistor 1 from the negative characteristic side detected voltage (detected voltage at the negative characteristic position) between the first and second voltage detection contacts 8A and 8B, which is calculated from the voltage signal, and the positive characteristic side detected voltage (detected voltage at the positive characteristic position) between the third and fourth voltage detection contacts 8C and 8D, which is calculated from the voltage signal. The current calculation formula is a function derived from a first function that indicates the relationship between the negative characteristic side detected voltage between the first and second voltage detection contacts 8A and 8B and the temperature of the shunt resistor 1, and a second function that indicates the relationship between the positive characteristic side detected voltage between the third and fourth voltage detection contacts 8C and 8D and the temperature of the shunt resistor 1.

[0065] Figure 18 is a graph showing the relationship between the negative characteristic side detected voltage between the first voltage detection contact 8A and the second voltage detection contact 8B and the temperature of the shunt resistor 1. While currents of 100 amperes, 99 amperes, 98 amperes, and 97 amperes were passed through the shunt resistor 1, the temperature of the shunt resistor 1 and the negative characteristic side detected voltage between the first voltage detection contact 8A and the second voltage detection contact 8B were measured, and the linear approximation graph shown in Figure 18 was created from the obtained temperature measurement data and voltage measurement data. The graph shown in Figure 18 is expressed by the following first function. Y1=a*I*t+b*I (1) Here, Y1 represents the negative characteristic side detection voltage [V] between the first voltage detection contact 8A and the second voltage detection contact 8B, a represents a coefficient (constant), t represents the temperature [°C] of the shunt resistor 1, b represents a coefficient (constant), and I represents the current [A] flowing through the shunt resistor 1. The coefficients a and b can be calculated from the temperature measurement data and voltage measurement data.

[0066] Figure 19 is a graph showing the relationship between the positive characteristic side detected voltage between the third voltage detection contact 8C and the fourth voltage detection contact 8D and the temperature of the shunt resistor 1. While currents of 100 amperes, 99 amperes, 98 amperes, and 97 amperes were passed through the shunt resistor 1, the temperature of the shunt resistor 1 and the positive characteristic side detected voltage between the third voltage detection contact 8C and the fourth voltage detection contact 8D were measured, and the linear approximation graph shown in Figure 19 was created from the obtained temperature measurement data and voltage measurement data. The graph shown in Figure 19 is expressed by the following second function. Y2=c*I*t+d*I (2) Here, Y2 represents the positive characteristic side detection voltage [V] between the third voltage detection contact 8C and the fourth voltage detection contact 8D, c represents a coefficient (constant), t represents the temperature [°C] of the shunt resistor 1, d represents a coefficient (constant), and I represents the current [A] flowing through the shunt resistor 1. The coefficients c and d can be calculated from the temperature measurement data and voltage measurement data.

[0067] From the first function (1) and the second function (2), the following current calculation formula and temperature calculation formula are derived. Current calculation formula I=((Y1×c)-(Y2×a)) / ((b×c)-(a×d)) (3) Temperature calculation formula t=((Y2×b)-(Y1×d)) / ((Y1×c)-(Y2×a)) (4) In the above current calculation formula and temperature calculation formula, the specific values ​​of a, b, c, and d are already determined, so once the negative characteristic side detection voltage Y1 and the positive characteristic side detection voltage Y2 are obtained, the current [A] flowing through shunt resistor 1 and the temperature [°C] of shunt resistor 1 can be calculated from the above current calculation formula and temperature calculation formula.

[0068] The current calculator 20 stores a current calculation formula and a temperature calculation formula in advance in its storage device 20a. The current calculator 20 calculates a negative characteristic side detection voltage Y1 (a voltage detected at the negative characteristic position) between the first voltage detection contact 8A and the second voltage detection contact 8B from a voltage signal acquired through the first voltage signal wire 9A and the second voltage signal wire 9B, and calculates a positive characteristic side detection voltage Y2 (a voltage detected at the positive characteristic position) between the third voltage detection contact 8C and the fourth voltage detection contact 8D from a voltage signal acquired through the third voltage signal wire 9C and the fourth voltage signal wire 9D. The current calculator 20 then inputs the negative characteristic side detection voltage Y1 and the positive characteristic side detection voltage Y2 into the current calculation formula to calculate the current [A] flowing through the shunt resistor 1. According to this embodiment, the current flowing through the shunt resistor can be directly calculated using the current calculation formula without correcting or combining the negative characteristic side detection voltage and the positive characteristic side detection voltage. Furthermore, the current calculator 20 can calculate the temperature [°C] of the shunt resistor 1 by inputting the negative characteristic side detected voltage Y1 and the positive characteristic side detected voltage Y2 into a temperature calculation formula.

[0069] In the above description, the current calculation formula and temperature calculation formula are derived from the relationship between the negative characteristic side detection voltage Y1 and the positive characteristic side detection voltage Y2 and temperature. However, if there is a difference between the first function and the second function, similar current calculation formulas and temperature calculation formulas can be derived. Therefore, the negative characteristic side detection voltage Y1 and the negative characteristic side detection voltage Y2 or the positive characteristic side detection voltage Y1 and the positive characteristic side detection voltage Y2 may be used. That is, the current calculation formula and temperature calculation formula are derived from the relationship between the first characteristic side detection voltage Y1 and the second characteristic side detection voltage Y2 and temperature. By inputting the first characteristic side detection voltage Y1 and the second characteristic side detection voltage Y2 into the current calculation formula, the current calculator 20 can calculate the current [A] flowing through the shunt resistor 1. Furthermore, by inputting the first characteristic side detection voltage Y1 and the second characteristic side detection voltage Y2 into the temperature calculation formula, the current calculator 20 can calculate the temperature [°C] of the shunt resistor 1.

[0070] The graphs in Figures 18 and 19 are created using linear approximation, but when showing curved data that is significantly curved, expressing it mathematically becomes complicated. Therefore, instead of using the current calculation formula and the temperature calculation formula, a data table can be stored in the memory device 20a, and the current [A] flowing through the shunt resistor 1 and the temperature [°C] of the shunt resistor 1 can be derived from the data table by referring to the negative characteristic side detection voltage Y1 and the positive characteristic side detection voltage Y2.

[0071] Although the shunt resistor 1 in each of the embodiments described so far has the slits 11 and 12 shown in FIGS. 1 and 2, other types of shunt resistors may also be used. For example, as shown in FIG. 20, the shunt resistor 1 may have a protrusion 25 that protrudes in its width direction. In this example, a portion of the resistor 5 and a portion of the pair of electrodes 6 and 7 form the protrusion 25. The protrusion 25 has a rectangular shape when viewed from above. Furthermore, as shown in FIG. 21, the shunt resistor 1 may have an L-shaped hole 27 in the pair of electrodes 6 and 7. The shape of the hole 27 is not limited to the shape shown in FIG. 21 and may have other shapes.

[0072] The above-described embodiments have been described for the purpose of enabling a person of ordinary skill in the art to practice the present invention. Various modifications of the above-described embodiments would be obvious to a person skilled in the art, and the technical concept of the present invention may be applied to other embodiments. Therefore, the present invention is not limited to the described embodiments, but is to be interpreted in the broadest scope in accordance with the technical concept defined by the claims. [Explanation of symbols]

[0073] 1 shunt resistor 2 Current detection section 3 Base Plate 5 Resistors 6,7 electrodes 8A~8D Voltage detection contacts 9A~9D Voltage signal wiring 11,12 Slit 13,14 Voltage signal merging wiring 16A~16D Voltage detection terminals 19 Capacitors 20 Current calculator 25 Protrusion 27 holes

Claims

1. a shunt resistor having a resistor and a first electrode and a second electrode connected to either side of the resistor; a current detection unit electrically connected to the shunt resistor; The current detection unit a first voltage detection contact and a second voltage detection contact electrically connected to negative characteristic positions of the first electrode and the second electrode where the temperature coefficient of resistance of the shunt resistor is a negative value; a third voltage detection contact and a fourth voltage detection contact electrically connected to positive characteristic positions of the first electrode and the second electrode where the temperature coefficient of resistance of the shunt resistor is a positive value; a first voltage signal wiring, a second voltage signal wiring, a third voltage signal wiring, and a fourth voltage signal wiring connected to the first voltage detection contact, the second voltage detection contact, the third voltage detection contact, and the fourth voltage detection contact, respectively; a resistor connected to at least one of the first voltage signal wiring, the second voltage signal wiring, the third voltage signal wiring, and the fourth voltage signal wiring; a first voltage signal merging wiring that merges voltage signals from the first voltage signal wiring and the third voltage signal wiring; a second voltage signal merging wiring that merges voltage signals from the second voltage signal wiring and the fourth voltage signal wiring, The resistor has a resistance value that brings the resistance temperature coefficient of the shunt resistor calculated from the voltage signals from the first voltage signal merging wiring and the second voltage signal merging wiring closer to zero.

2. a shunt resistor having a resistor and a first electrode and a second electrode connected to either side of the resistor; a current detection unit electrically connected to the shunt resistor; The current detection unit a first voltage detection contact and a second voltage detection contact electrically connected to negative characteristic positions of the first electrode and the second electrode where the temperature coefficient of resistance of the shunt resistor is a negative value; a third voltage detection contact and a fourth voltage detection contact electrically connected to positive characteristic positions of the first electrode and the second electrode where the temperature coefficient of resistance of the shunt resistor is a positive value; a current calculator to which voltage signals from the first voltage detection contact, the second voltage detection contact, the third voltage detection contact, and the fourth voltage detection contact are input; The current calculator multiplying at least one of a negative characteristic side detection voltage between the first voltage detection contact and the second voltage detection contact and a positive characteristic side detection voltage between the third voltage detection contact and the fourth voltage detection contact, which are calculated from the voltage signal, by a correction coefficient to correct at least one of the negative characteristic side detection voltage and the positive characteristic side detection voltage; a current flowing through the shunt resistor is determined based on a composite detection voltage calculated from the negative characteristic side detection voltage and the positive characteristic side detection voltage, at least one of which has been corrected, and a known resistance value of the shunt resistor; The correction coefficient is a value that brings the resistance temperature coefficient of the shunt resistor calculated from the composite detected voltage closer to zero.

3. a shunt resistor having a resistor and a first electrode and a second electrode connected to either side of the resistor; a current detection unit electrically connected to the shunt resistor; The current detection unit a first voltage detection contact and a second voltage detection contact electrically connected to first characteristic positions of the first electrode and the second electrode where the temperature coefficient of resistance of the shunt resistor is a first coefficient; a third voltage detection contact and a fourth voltage detection contact electrically connected to second characteristic positions of the first electrode and the second electrode where the temperature coefficient of resistance of the shunt resistor is a second coefficient; a current calculator to which voltage signals from the first voltage detection contact, the second voltage detection contact, the third voltage detection contact, and the fourth voltage detection contact are input; The current calculator derives the value of the current flowing through the shunt resistor from a first characteristic side detection voltage between the first voltage detection contact and the second voltage detection contact and a second characteristic side detection voltage between the third voltage detection contact and the fourth voltage detection contact, which are calculated from the voltage signal.

4. 4. The current detection device according to claim 3, wherein the current calculator includes a current calculation formula for calculating a value of a current flowing through the shunt resistor from the first characteristic side detected voltage and the second characteristic side detected voltage.

5. 5. The current detection device according to claim 3, wherein the current calculator includes a data table showing a relationship between the first characteristic side detected voltage and the second characteristic side detected voltage and a current value flowing through the shunt resistor.

6. 6. The current detection device according to claim 3, wherein the current calculator has a function of deriving the temperature of the shunt resistor from the first characteristic side detected voltage and the second characteristic side detected voltage.

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