Current detection device

Abstract

Provided is a technique for detecting a wide range of current with high accuracy. A current detection device 100 according to the present disclosure comprises: a shunt resistor 10 having a resistive element and a pair of electrodes connected to opposite sides of the resistive element; a current detection substrate 20 electrically connected to the shunt resistor 10; and a temperature sensor 40 for measuring the temperature of the current detection substrate 20. A microcontroller 25 is characterized by correcting, on the basis of temperature characteristics of a detection circuit acquired in advance and the temperature measured by the temperature sensor 40, a value that is used when the value of current is calculated by processing a signal from the shunt resistor 10.

Description

Current detection device

[0001] The present disclosure relates to a current detection device.

[0002] A known method for detecting current is to use a shunt resistor. Specifically, a shunt resistor is connected in series to a path through which a current to be measured flows, and the voltage across the shunt resistor is detected to calculate the current value. A current detection device using this method includes a shunt resistor and a current detection circuit, which includes, for example, an amplifier, an A / D converter, a microcontroller, etc.

[0003] Current detection devices equipped with shunt resistors are used in a variety of applications, such as inverter devices, converter devices, 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. The current detection device affects the battery capacity design required for the entire system and determines system costs. Therefore, current detection devices are required to have high measurement accuracy over a wide range of currents.

[0004] When measuring current using a shunt resistor, it is known that the resistance value of the shunt resistor changes with temperature changes. When a large current is passed through the shunt resistor, the shunt resistor heats up, and the resistance value changes due to the temperature characteristics (resistance temperature coefficient) of the shunt resistor. This reduces the accuracy of current measurement. Changes in ambient temperature also affect the resistance value.

[0005] As a countermeasure, a method is known in which the temperature characteristics (relationship between temperature and resistance value) of the shunt resistor are grasped in advance, the temperature of the shunt resistor is measured, and the resistance value is corrected based on the temperature characteristics to calculate the current. Patent Document 1 discloses a technology that "by correcting the detected current value including the temperature characteristic value of the shunt resistor, it is possible to realize accurate current detection even when the shunt resistor becomes hot, and it is possible to provide an inverter drive device that can perform more accurate control" (see the abstract of Patent Document 1).

[0006] JP 2011-125130 A

[0007] One way to deal with temperature changes is to use a shunt resistor made of a resistive material with a small temperature coefficient of resistance. However, there are limitations to what can be achieved because the resistive material used in high-current shunt resistors must have a lower resistivity, and the lower the resistivity, the larger the temperature coefficient of resistance tends to be.

[0008] In current detection devices, the temperature characteristics of the detection circuit have a smaller impact on detection accuracy than the temperature characteristics of the shunt resistor. Therefore, the temperature characteristics of the detection circuit have traditionally been ignored or addressed by frequent calibration in the device's system configuration. However, in recent years, there has been a demand for more accurate detection of large currents. To build such current detection devices, it is no longer possible to achieve high-precision detection simply by correcting the temperature characteristics of the shunt resistor, and the temperature characteristics of the detection circuit can no longer be ignored.

[0009] The ambient temperature range required for current detection devices is, for example, 20°C to 70°C for industrial applications (machine tools, etc.), and -40°C to 125°C for automotive equipment. However, it is difficult to continuously measure a wide range of currents (e.g., 20 A to 400 A) with high accuracy across the entire range of ambient temperatures in which the current detection device is installed. Therefore, correction is required according to the temperature characteristics of the detection circuit.

[0010] Therefore, the present disclosure provides a technique for detecting a wide range of current with high accuracy.

[0011] In order to solve the above problem, the current detection device disclosed herein comprises a shunt resistor having a resistor and a pair of electrodes connected to both sides of the resistor, a current detection unit electrically connected to the shunt resistor, and a first temperature sensor that measures the temperature of the current detection unit, and is characterized in that the current detection unit processes the signal from the shunt resistor and corrects the value used to calculate the current value based on the temperature characteristics of the current detection unit that have been acquired in advance and the temperature measured by the first temperature sensor.

[0012] Further features related to the present disclosure will become apparent from the description of this specification and the accompanying drawings. Also, aspects of the present disclosure are achieved and realized by the elements and combinations of various elements and the aspects of the following detailed description and the appended claims. The description of this specification is merely exemplary and does not limit the scope or application of the claims of the present disclosure in any way.

[0013] According to the technology of the present disclosure, it is possible to detect a wide range of current with high accuracy. Problems, configurations, and effects other than those described above will become apparent from the following description of the embodiments.

[0014] 12 is a perspective view of a shunt resistor included in the current detection device according to the first embodiment. FIG. 13 is a perspective view of the current detection device according to the first embodiment. FIG. 14 is a view taken along the arrow A in FIG. 2 of the current detection device according to the first embodiment. FIG. 15 is an enlarged cross-sectional view of the vicinity of the temperature sensor (B-B' in FIG. 2). FIG. 16 is an enlarged cross-sectional view showing another example of the configuration of the vicinity of the temperature sensor (B-B' in FIG. 2). FIG. 17 is a graph showing an example of the resistance-temperature characteristics of a shunt resistor. FIG. 18 is a graph showing an example of the temperature characteristics of an A / D converted value (offset AD value) of a signal when no current is applied. FIG. 19 is a graph showing an example of the temperature characteristics of the amplification factor of an amplifier circuit. FIG. 19 is a circuit block diagram of the current detection device according to the first embodiment. FIG. 19 is a flowchart showing a current detection method according to the first embodiment. FIG. 19 is a perspective view of the current detection device according to the second embodiment. FIG. 19 is a perspective view of the current detection device according to the third embodiment. FIG. 19 is a cross-sectional view taken along the line CC' in FIG.

[0015] 1 is a perspective view of a shunt resistor 10 included in a current detection device according to Embodiment 1. The shunt resistor 10 includes a resistive element 11, electrodes 12 and 13, voltage detection terminals 14 and 15, and busbar mounting holes 16 and 17.

[0016] The resistor 11 is formed in the shape of a rectangular plate having a predetermined thickness and width. Examples of materials for the resistor 11 include alloys such as copper-nickel alloys, copper-manganese alloys, iron-chromium alloys, and nickel-chromium alloys. The pair of electrodes 12 and 13 are connected to both sides of the resistor 11 by, for example, welding. Examples of welding methods include electron beam welding, laser beam welding, and brazing. The electrodes 12 and 13 are plate-shaped and made of a highly conductive metal such as copper. The voltage detection terminal 14 is provided near the resistor 11 so as to protrude from the top surface of the electrode 12. The voltage detection terminal 15 is provided near the resistor 11 so as to protrude from the top surface of the electrode 13. The busbar mounting hole 16 is provided in the electrode 12. The busbar mounting hole 17 is provided in the electrode 13.

[0017] 2 is a perspective view of the current detection device 100 according to the first embodiment. The current detection device 100 includes a shunt resistor 10 and a detection circuit board 20. The detection circuit board 20 is disposed on top of the shunt resistor 10, and the voltage detection terminals 14 and 15 are inserted into through holes formed in the detection circuit board 20, and the shunt resistor 10 and the detection circuit board 20 are electrically connected by soldering or the like. The detection circuit board 20 includes an amplifier circuit 23, an A / D converter 24, a microcontroller 25, a connector 26, and temperature sensors 30 and 40.

[0018] The potentials of the electrodes 12 and 13 at the positions of the voltage detection terminals 14 and 15 of the shunt resistor 10 are input to the amplifier circuit 23. The amplifier circuit 23 has an amplifier, amplifies the difference (voltage) between the input potentials, and outputs it as a voltage signal. The output voltage signal is input to the A / D converter 24. The A / D converter 24 A / D converts the input voltage signal and outputs a digital signal. The output digital signal is input to the microcontroller 25. The microcontroller 25 processes the digital signal to calculate a voltage value, and calculates a current value (measured current value) based on the voltage value and the resistance value of the shunt resistor 10.

[0019] The temperature sensors 30 and 40 may be, for example, thermistors. The temperature sensor 30 is provided in a position where it can measure the temperature of the resistor 11 of the shunt resistor 10. The temperature sensor 40 is provided near the amplifier circuit 23, A / D converter 24, microcontroller 25, and connector 26 (hereinafter, these may be simply referred to as the "detection circuit") on the detection circuit board 20. In this way, the temperatures of the shunt resistor 10 and the detection circuit board 20 are measured by separate sensors. This method is particularly effective the farther the distance between the shunt resistor 10 and the detection circuit board 20 (such as the amplifier circuit 23 and A / D converter 24) is, and since the correlation between their respective temperatures becomes weaker, it is important to measure the temperatures separately using separate temperature sensors.

[0020] The measurement signals (voltage signals from thermistors) of the temperature sensors 30 and 40 are amplified by an amplifier circuit 23 as necessary, converted into digital signals by an A / D converter 24, and then input to the microcontroller 25, where they are converted into temperatures. As will be described later, in this embodiment, the microcontroller 25 corrects the digital value, voltage value, or current value based on the measurement values ​​of the temperature sensors 30 and 40 when calculating the current measurement values.

[0021] Fig. 3 is a view of the current detection device 100 according to the first embodiment as viewed from the arrow A in Fig. 2. As shown in Fig. 3, the temperature sensor 30 is disposed on the upper surface of the detection circuit board 20 so as to be located above (in the vicinity of) the resistor 11.

[0022] 4 is an enlarged cross-sectional view (B-B' in FIG. 2) of the vicinity of the temperature sensor 30. As shown in FIG. 4, a thermally conductive member such as a copper inlay 27 can be provided on the detection circuit board 20 below the temperature sensor 30. This allows the heat of the shunt resistor 10 to be effectively transferred to the temperature sensor 30, enabling accurate temperature measurement.

[0023] 5 is an enlarged cross-sectional view showing another example of the configuration near the temperature sensor 30 (B-B' in FIG. 2). Instead of the copper inlay 27 shown in FIG. 4, a copper wiring pattern 28 can be provided on the inner layer of the detection circuit board 20 below the temperature sensor 30.

[0024] <Regarding correction based on temperature characteristics> In the current detection device 100 of this embodiment, current measurement tests are performed in advance under multiple temperature environments to obtain the temperature characteristics of the shunt resistor 10 and the temperature characteristics of the detection circuit. The previously obtained temperature characteristics of the shunt resistor 10 and the temperature characteristics of the detection circuit are then recorded in the microcontroller 25 or an external memory and used when calculating the voltage value or current value.

[0025] The temperature characteristics of the shunt resistor 10 vary depending on the material (alloy composition) of the resistor 11, the materials of the electrodes 12 and 13, and the positions of the voltage detection terminals 14 and 15. In the detection circuit, the gain of the amplifier circuit 23 and the measured value when no current is applied (0 A) have temperature characteristics. Regarding the temperature characteristics of the detection circuit, it is particularly important to measure the temperature of the semiconductor chip (the amplifier circuit 23, A / D converter 24, and microcontroller 25, or an analog front-end IC that integrates these) used to detect the output voltage of the shunt resistor 10.

[0026] Figure 6 is a graph showing an example of the temperature characteristics of the resistance value of the shunt resistor 10 when a copper-manganese alloy is used for the resistive element 11. The horizontal axis represents temperature, and the vertical axis represents resistance value. As shown in Figure 6, it can be seen that the resistance value of the shunt resistor 10 varies depending on the ambient temperature. For example, at 25°C, the resistance value is Rs (Ω).

[0027] 7 is a graph showing an example of the temperature characteristics of the A / D converted value (offset AD value) of the signal from the shunt resistor 10 when no current is applied. The horizontal axis represents temperature, and the vertical axis represents the offset AD value. For example, at 25°C, the A / D converted value (offset AD value) of the signal at 0 A (when no current is applied) is Vd0. The temperature characteristics of such a 0 A measured value are particularly affected by the temperature characteristics of the amplifier circuit 23 and the A / D converter 24.

[0028] FIG. 8 is a graph showing an example of the temperature characteristic of the gain of the amplifier circuit 23. The horizontal axis represents temperature, and the vertical axis represents gain. As shown in FIG. 8, in the amplifier circuit 23, the gain varies with temperature; for example, at 25° C., the gain is X times. It can also be seen that the gain has a nonlinear temperature characteristic. The temperature characteristic of the amplifier has the greatest effect on the temperature characteristic of the amplifier.

[0029] The temperature characteristics previously acquired as shown in Figures 6 to 8 are each recorded in the microcontroller 25 as, for example, an approximate curve (function). The microcontroller 25 calculates the current resistance value of the shunt resistor 10 from the measurement value of the temperature sensor 30 for the shunt resistor 10 and the previously recorded temperature characteristics of the shunt resistor 10, and uses this to calculate the current value. The microcontroller 25 also calculates current circuit parameters (offset AD value, amplification factor of the amplifier circuit 23) from the measurement value of the temperature sensor 40 for the detection circuit and the previously recorded temperature characteristics of the detection circuit, and uses this to calculate the current value.

[0030] FIG. 9 is a circuit block diagram of the current detection device 100 according to the first embodiment. As shown in FIG. 9 , the microcontroller 25 has circuit parameter adjustment and temperature compensation functions. The voltage signal from the shunt resistor 10 is amplified by the amplifier circuit 23, converted into a digital signal by the A / D converter 24, and input to the microcontroller 25. The measurement values ​​of the temperature sensor 30 for the shunt resistor 10 and the temperature sensor 40 for the detection circuit board 20 are each amplified by the amplifier circuit 23 as necessary, converted into a digital signal by the A / D converter 24, and input to the microcontroller 25. The microcontroller 25 acquires current circuit parameters (the resistance value of the shunt resistor 10, the offset AD value, and the amplification factor of the amplifier circuit 23) based on the input information and previously acquired and recorded temperature characteristics. The microcontroller 25 then calculates a voltage value using the current circuit parameters, and calculates a current value (measured current value) from the voltage value and the resistance value of the shunt resistor 10. The microcontroller 25 outputs the calculated current value to a predetermined device or the like via the connector 26 .

[0031] <Current Detection Method> FIG. 10 is a flowchart showing a current detection method according to the first embodiment.

[0032] In step S1, a signal corresponding to the voltage applied to the shunt resistor 10 (the voltage between the voltage detection terminals 14 and 15) is amplified by the amplifier circuit 23, converted into a digital signal (Vd1) by the A / D converter 24, and input to the microcontroller 25.

[0033] In step S2, the microcontroller 25 obtains the temperature (T1) of the shunt resistor 10 from the measurement value of the temperature sensor 30. Specifically, the measurement value of the temperature sensor 30 (thermistor voltage value) is amplified by the amplifier circuit 23, converted into a digital signal by the A / D converter 24, and then converted into the temperature (T1) by the microcontroller 25.

[0034] In step S3, the microcontroller 25 acquires the temperature (T2) of the detection circuit board 20 from the measurement value of the temperature sensor 40. Specifically, the measurement value of the temperature sensor 40 (thermistor voltage value) is amplified by the amplifier circuit 23, converted into a digital signal by the A / D converter 24, and then converted into the temperature (T2) by the microcontroller 25.

[0035] In step S4, the microcontroller 25 obtains the current offset AD value from the temperature T2 calculated in step S3 and the temperature characteristics of the offset AD value recorded in advance (FIG. 7). For example, when the temperature T2 is 25° C., the offset AD value is Vd0.

[0036] In step S5, the microcontroller 25 obtains the current amplification factor from the temperature T2 obtained in step S3 and the pre-recorded temperature characteristics (FIG. 8) of the amplification factor of the amplifier circuit 23. For example, when the temperature T2 is 25° C., the amplification factor is X times.

[0037] In step S6, the microcontroller 25 obtains the current resistance value from the temperature T1 obtained in step S2 and the pre-recorded temperature characteristics (FIG. 6) of the resistance value of the shunt resistor 10. For example, when the temperature T1 is 25° C., the resistance value is Rs (Ω).

[0038] In step S7, the microcontroller 25 calculates the current value. Specifically, first, the offset AD value acquired in step S4 is subtracted from the digital value Vd1 acquired in step S1 to calculate a value (Vd2) corrected for the 0 A error. The calculation formula at this time is as follows: Vd1 - Vd0 = Vd2

[0039] Next, the microcontroller 25 converts the value Vd2 into a shunt output voltage (Vd3) based on the amplification factor obtained in step S5, using the following calculation formula: Vd2÷X=Vd3

[0040] Next, the microcontroller 25 performs a predetermined conversion process on the shunt output voltage Vd3 to calculate the voltage Vr.

[0041] Next, the microcontroller 25 calculates the current value (I) from the voltage Vr and the resistance value acquired in step S6. The calculation formula at this time is as follows. The calculated current value is output to various electrical devices (not shown) via a data bus or the like: I = Vr ÷ Rs

[0042] <Modification of Current Detection Method> The above describes a method in which the digital value of the voltage signal from the shunt resistor 10 is corrected using circuit parameters corresponding to the current temperature, a voltage value is calculated from the corrected digital value, and a current value is calculated from the voltage value and a resistance value corresponding to the current temperature. This calculation method, in which the digital value is corrected as is and then converted to a voltage, simplifies the calculation compared to converting the acquired digital values ​​to voltages and then correcting them. Of course, the current value may also be calculated using the first modification method described below, in which the acquired digital values ​​are converted to voltages and then corrected. Below, only the differences from the first embodiment will be described.

[0043] In the first modified example, the temperature characteristic of the offset current value, rather than the offset AD value, is stored in advance in the microcontroller 25 as the temperature characteristic of the measurement value when no current is applied. Then, in step S1 of the first modified example, the microcontroller 25 acquires a voltage value (Vr) from the digital value of the acquired signal. Steps S2 and S3 are the same as in the first embodiment. Next, in step S4, the microcontroller 25 acquires the current offset current value from the temperature T2 calculated in step S3 and the temperature characteristic of the offset current value recorded in advance. For example, when the temperature T2 is 25°C, the offset current value is Io (A). Steps S5 and S6 are also the same as in the first embodiment.

[0044] In step S7 of this modified example, the microcontroller 25 converts the voltage value (Vr) acquired in step S1 and the amplification factor acquired in step S5 into a voltage applied to the shunt resistor 10. The calculation formula at this time is as follows: Vr÷X

[0045] Next, the microcontroller 25 calculates the current value before the offset from the resistance value acquired in step S6 using the following formula: Vr÷X÷Rs

[0046] Next, the microcontroller 25 calculates the measured current value I from the offset current value acquired in step S4 using the following calculation formula: I=(Vr÷X÷Rs)−Io

[0047] As described above, in the modification of the first embodiment, the voltage value of the voltage applied to the shunt resistor 10 is processed according to the temperature characteristics, and an offset current value according to the temperature characteristics is subtracted from the current value calculated from the corrected voltage value. In this way, in the first embodiment, the correction may be performed on the A / D converted value (digital value) of the signal, the voltage value, or the current value.

[0048] In the first embodiment and the first modification, a current detection method using the temperature sensor 30 that measures the temperature of the shunt resistor 10 and the temperature sensor 40 that measures the temperature of the detection circuit board 20 has been described. As a second modification, only the temperature sensor 40 that measures the temperature of the detection circuit board 20 and the temperature characteristics of the detection circuit that have been acquired in advance may be used. In this case, step S2 above is omitted, and the resistance value of the shunt resistor 10 acquired in step S6 is a set value.

[0049] Summary of First Embodiment The current detection device 100 according to the first embodiment includes a shunt resistor 10 having a resistor 11 and a pair of electrodes 12 and 13 arranged on both sides of the resistor 11, a detection circuit board 20 (current detection unit), and a temperature sensor 40 that measures the temperature of the detection circuit board 20. The microcontroller 25 (current detection unit) corrects (adjusts) values ​​used in the current value calculation process based on previously acquired temperature characteristics of the detection circuit and the temperature measured by the temperature sensor 40. Specifically, in the current value calculation process, the A / D conversion value, voltage value, or current value of the signal from the shunt resistor 10 is corrected using circuit parameters adjusted according to the temperature characteristics. This enables high-accuracy current detection even in a current detection device that measures large currents (100 A or more). The current detection device 100 also includes a temperature sensor 30 that measures the temperature of the shunt resistor 10. The microcontroller 25 (current detection unit) calculates the measured current value by further correcting (adjusting) the resistance value of the shunt resistor 10 used in the process of calculating the measured current value based on the temperature characteristics of the shunt resistor 10 acquired in advance and the temperature measured by the temperature sensor 30.

[0050] Second Embodiment In the first embodiment, it has been described that the temperature characteristics of the detection circuit are affected by the temperature characteristics of the amplifier circuit 23 and the A / D converter 24. Therefore, in the second embodiment, a configuration of a current detection device will be described in which the position of the temperature sensor 40 is changed to the vicinity of the amplifier circuit 23 and the A / D converter 24.

[0051] Fig. 11 is a perspective view of a current detection device 200 according to the second embodiment. As shown in Fig. 11, in the current detection device 200 according to the second embodiment, the temperature sensor 40 is disposed between the amplifier circuit 23 and the A / D converter 24. A plurality of temperature sensors 40 may be provided, in which case each temperature sensor 40 can be disposed near the amplifier circuit 23 and the A / D converter 24.

[0052] An analog front-end IC that integrates the amplifier circuit 23, the A / D converter 24, etc. may be used instead of the amplifier circuit 23 and the A / D converter 24. In this case, the temperature sensor 40 may be disposed near the analog front-end IC.

[0053] Third Embodiment In the first embodiment, the current detection device 100 is described, in which the shunt resistor 10 and the detection circuit board 20 are in contact with each other. In such a case, heat generated by the shunt resistor 10 may be transferred to the detection circuit board 20, narrowing the operating temperature range. Therefore, in the third embodiment, a current detection device is proposed, in which a heat insulating layer is provided to separate the shunt resistor 10 and the detection circuit board 20.

[0054] Fig. 12 is a perspective view of a current detection device 300 according to the third embodiment. As shown in Fig. 12, in the current detection device 300 according to the third embodiment, a heat insulating layer 50 is provided between the shunt resistor 10 and the detection circuit board 20. By providing the heat insulating layer 50, the operating temperature range can be widened.

[0055] The material of the heat insulating layer 50 can be, for example, a heat-resistant resin or a fiber-reinforced resin. More specifically, examples include 30% PBT glass (polybutylene terephthalate, 30% glass fiber), polyvinyl chloride, 50% polyamide glass, 40% PPS glass, polypropylene, etc. Depending on the application, polycarbonate, PEEK material, acrylic resin, etc. can also be used for the heat insulating layer 50.

[0056] The thicker the heat insulating layer 50, the higher the heat insulating effect, but a thicker layer may deteriorate the frequency characteristics. From this viewpoint, the thickness of the heat insulating layer 50 may be set to, for example, 0.3 mm or more and 2 mm or less.

[0057] As described above, the greater the distance between the shunt resistor 10 and the detection circuit board 20, the less the correlation between their respective temperatures becomes, making it important to measure their temperatures individually. Therefore, the temperature sensor 30 can be effectively measured by directly mounting it on the shunt resistor 10. For this purpose, a notch 29 is provided in the detection circuit board 20 (and the heat insulating layer 50), and the temperature sensor 30 is mounted in the exposed portion.

[0058] Figure 13 is a cross-sectional view taken along the line CC' in Figure 12. As shown in Figure 13, the temperature sensor 30 is adhered to the shunt resistor 10 with an adhesive 60. A resin-based adhesive with high insulating properties and high thermal conductivity can be used as the adhesive 60. The temperature sensor 30 and the detection circuit board 20 are electrically connected by wiring using electric wires, wire bonding, or the like.

[0059] [Modifications] The present disclosure is not limited to the above-described embodiments and includes various modifications. For example, the above-described embodiments have been described in detail to clearly explain the present disclosure, and it is not necessary to include all of the described configurations. Furthermore, a part of one embodiment can be replaced with a configuration of another embodiment. Furthermore, a configuration of another embodiment can be added to a configuration of one embodiment. Furthermore, a part of the configuration of each embodiment can be added to, deleted from, or substituted for a part of the configuration of another embodiment.

[0060] [Contribution to the Environment] According to the present disclosure, a current detection device capable of measuring large currents (100 A or more) enables high-precision current detection over a wide range, improving the current measurement accuracy of the equipment used. This contributes to improving the power consumption efficiency and safety of the equipment used. Therefore, the present disclosure can contribute to the achievement of Goal 3 "Good Health and Well-Being," Goal 7 "Affordable and Clean Energy," and Goal 9 "Industry, Innovation and Infrastructure" of the United Nations' Sustainable Development Goals (SDGs).

[0061] DESCRIPTION OF SYMBOLS 100, 200, 300...Current detection device 10...Shunt resistor 11...Resistor 12, 13...Electrodes 14, 15...Voltage detection terminals 16, 17...Bus bar mounting holes 20...Detection circuit board 23...Amplifier circuit 24...A / D converter 25...Microcontroller 26...Connector 27...Copper inlay 28...Copper wiring pattern 29...Notch 30...Temperature sensor (second temperature sensor) 40...Temperature sensor (first temperature sensor) 50...Heat insulating layer 60...Adhesive

Claims

1. A current detection device comprising: a shunt resistor having a resistor and a pair of electrodes connected to both sides of the resistor; a current detection unit electrically connected to the shunt resistor; and a first temperature sensor that measures the temperature of the current detection unit, wherein the current detection unit processes a signal from the shunt resistor and corrects a value used to calculate a current value based on the temperature characteristics of the current detection unit that have been acquired in advance and the temperature measured by the first temperature sensor.

2. The current detection device according to claim 1, wherein the current detection unit has an amplifier circuit and an A / D converter, and the first temperature sensor is positioned so as to be able to measure at least one of the temperature of the amplifier circuit, the temperature of the A / D converter, or the ambient temperature thereof.

3. The current detection device according to claim 2, wherein the temperature characteristics of the current detection section include at least one of the temperature characteristics of the amplification factor of the amplifier circuit and the temperature characteristics of the measured value when no current is applied.

4. A current detection device as described in any one of claims 1 to 3, further comprising a second temperature sensor that measures the temperature of the shunt resistor, and the current detection unit calculates the current value by correcting the value in the processing based on the temperature characteristics of the shunt resistor that have been acquired in advance and the temperature measured by the second temperature sensor.

5. The current detection device according to any one of claims 1 to 3, further comprising a heat insulating layer disposed between the shunt resistor and the current detection portion.

6. The current detection device according to claim 5, further comprising a second temperature sensor for measuring the temperature of the shunt resistor, wherein the current detection section and the heat insulating layer have a cutout portion, and the second temperature sensor is disposed in the cutout portion.

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