Measuring circuit with a resistor arrangement and method for producing a ribbon-shaped material composite for the resistor arrangement

Abstract

Measuring circuit comprising a resistor arrangement (8) which includes: a first electrically conductive connection element (10) and a second electrically conductive connection element (11), a first resistance element (12) which is electrically connected to the first terminal element (10), a second resistance element (13) which is electrically connected to the second terminal element (11), an electrically conductive intermediate element (14) that is arranged between the first resistive element (12) and the second resistive element (13) and is electrically connected to these resistive elements (12, 13), wherein the connecting elements (10, 11), the resistive elements (12), (13) and the intermediate element (14) are arranged next to each other in a row, and wherein the connecting elements (10, 11) and the intermediate element (14) on the one hand and the resistive elements (12, 13) on the other hand are made of different materials, the material of the first resistive element (12) being different from the material of the second resistive element (13), characterized in that the measuring circuit further comprises: a first voltage tap for measuring a first electrical voltage that drops across the first resistive element (12), a second voltage tap for measuring a second electrical voltage, which includes at least the electrical voltage drop across the second resistive element (13), and at least one electronic component for determining the first electrical voltage and the second electrical voltage, wherein a comparator is provided for comparing the measured first electrical voltage and the measured second electrical voltage.

Description

[0001] The invention relates to a measuring circuit comprising a resistor arrangement which includes: a first electrically conductive terminal element and a second electrically conductive terminal element, a first resistive element electrically connected to the first terminal element, a second resistive element electrically connected to the second terminal element, an electrically conductive intermediate element arranged between the first and second resistive elements and electrically connected to these resistive elements, wherein the terminal elements, the resistive elements and the intermediate element are arranged side by side in a row.The connecting elements and the intermediate element on the one hand and the resistive elements on the other hand consist of different materials, the material of the first resistive element being different from the material of the second resistive element, further comprising: a first voltage tap for measuring a first electrical voltage that drops across the first resistive element. The invention relates to a second voltage tap for measuring a second electrical voltage, which comprises at least the electrical voltage drop across the second resistive element, and at least one electronic component for determining the first electrical voltage and the second electrical voltage, wherein a comparator is provided for comparing the measured first electrical voltage and the measured second electrical voltage. The invention further relates to a method for producing a ribbon-shaped material composite for the resistive arrangement.

[0002] Current measurement in electronic circuits uses shunt resistors connected in series with the component being monitored. The current can then be determined from the voltage drop across the shunt resistor. Accurate and reliable current measurement is particularly important, for example, in the battery management system of a hybrid or electric vehicle, or for monitoring a fuel cell device.

[0003] Such a low-resistance shunt resistor with a resistance of approximately 10–50 µΩ can be manufactured from a longitudinally welded composite material strip. This is known, for example, from EP 0 605 800 A1. The composite material is produced from three material strips by joining the individual metal strips together via a longitudinal seam using an electron beam or laser welding process.

[0004] The demands on accurate and reliable current measurement in today's hybrid and electric vehicles, which sometimes operate at very high continuous currents, are constantly increasing. Monitoring safety-relevant components at such currents is of paramount importance. Lithium-ion batteries, with their high energy density, must be monitored very closely to ensure they remain in a safe operating state at all times. Current measurement within the battery is therefore essential for monitoring specific operating parameters such as the state of charge (SOC), state of health (SOH), and state of function (SOF). With safety levels in this application reaching up to ASIL C and D (ISO 26262), it is necessary to protect the relevant measuring instruments with redundant functionality to achieve these safety levels.

[0005] The redundancy of the current measurement, necessary to achieve safety level ASIL C, can be achieved by combining different sensors, i.e., by simultaneously acquiring two completely different measurement signals. For example, this could be done by measuring the voltage across a shunt resistor of known value and by measuring the Hall voltage across a current-carrying conductor in a magnetic field. This setup is relatively expensive, partly because the integration is limited and many components with a correspondingly large footprint are required.

[0006] Redundancy in data acquisition can also be achieved by connecting a second shunt resistor in series with the first shunt resistor instead of using the Hall effect voltage measurement. Independent voltage measurements are then performed across each of the two shunt resistors of this double shunt to determine the current. By comparing the two measurements, it can be determined whether the measurements are plausible or if an error has occurred. The double shunt thus enables the diagnosis of single-point faults, namely drift, resistance changes, and disconnections of individual measurement points. Furthermore, it offers improved diagnostic capabilities for the shunt electronics by allowing for plausibility checks of the measurement using two shunt elements integrated into a single component. Current measurement using a double shunt is simpler and more cost-effective in terms of its design than current measurement using a single shunt and the Hall effect.The possibility of manufacturing a multiple shunt is known from US 9,343,208 B2.

[0007] However, with such a double shunt, there is a possibility that both measurements are subject to the same error, for example due to a parallel drift of the two resistors.

[0008] DE 694 09 614 T2 and KR 10 2018 0 003 505 A disclose a precision resistor according to the preamble of claim 1, comprising three terminals and two resistors made of different materials, wherein the terminals and the resistors are connected in series. A disadvantage here is the high material cost and the complex construction of the resistors.

[0009] DE 10 2014 103 343 A1 describes a multi-current sensor device with two resistors electrically connected via a common connecting element. The resistors and the connecting element are not arranged side-by-side in a row, nor are they made of different materials. Furthermore, a method for producing a ribbon-like composite material is described, wherein three ribbons of a material with high electrical conductivity and two ribbons of a resistive material are provided and longitudinally welded together to form a ribbon composite.

[0010] The invention is therefore based on the objective of providing a measuring circuit and a method for producing a ribbon-shaped composite material that enables a reduction in the amount of material to be used and a reduction in costs.

[0011] This problem is solved by a measuring circuit with the features of claim 1 and by a method with the features of claim 10. Advantageous embodiments with expedient further developments of the invention are specified in the dependent claims.

[0012] The measuring circuit then comprises a resistor arrangement as described above, a first voltage tap for measuring a first electrical voltage that drops across the first resistive element, a second voltage tap for measuring a second electrical voltage that includes at least the electrical voltage dropping across the second resistive element, and at least one electronic component for determining the first electrical voltage and the second electrical voltage.

[0013] The reliability of the measured values ​​can be assessed by using a comparator to compare the measured first electrical voltage and the measured second electrical voltage.

[0014] Preferably, the electronic component is set up so that the measurement of the first electrical voltage and the measurement of the second electrical voltage can be carried out independently of each other, so that a failure of one of the two measuring chains can be detected by comparing the two measurements.

[0015] The resistance measuring arrangement of the type described above is characterized by the fact that the two resistance elements are specifically manufactured from different materials, in particular from different alloys, which may have different chemical compositions. Examples of resistance alloys include CuMn10Ni4, CuMn12Ni2, CuMn14Ni2, and CuZn15Mn15Al. The resistance measuring arrangement then comprises material pairings of these alloys, for example, CuMn10Ni4 for the first resistance element and CuMn14Ni2 for the second resistance element.

[0016] This ensures, in particular, that the two resistor elements originate from different production batches. Undetected defects in one batch, which could, for example, lead to drift, cannot thus occur simultaneously and in the same way in both resistor elements. This offers the advantage of improved measurement redundancy. Furthermore, the resistor arrangement is characterized by the fact that only the first and second terminal elements have connectors for integration into a circuit, while the intermediate element cannot be connected to a circuit.

[0017] It is further proposed that the two connection elements be plate-shaped and the intermediate element be strip-shaped, and that the intermediate element be narrower than either of the two connection elements. This allows for material and space savings, since the intermediate element only serves to accommodate connections for voltage measurement, not for connection to a circuit. The resistor elements can also be strip-shaped.

[0018] The thickness of the resistor elements is less than both the thickness of the connection elements and the thickness of the intermediate element, which offers advantages when mounting, for example, on a PCB (printed circuit board) and also allows soldering.

[0019] The design is such that the first resistive element has a thickness that differs from the thickness of the second resistive element. This allows for a better match between the resistance values ​​of the two resistive elements.

[0020] It is further preferred if a first pair of measuring terminals is provided for measuring the electrical voltage drop across the first resistive element and a second pair of measuring terminals is provided for measuring the voltage drop across the second resistive element, and if a first measuring terminal from the first pair of measuring terminals and a second measuring terminal from the second pair of measuring terminals are assigned to the intermediate element.

[0021] Alternatively or additionally, it is possible to provide one pair of measuring terminals for measuring the electrical voltage drop across the first resistive element and a third pair of measuring terminals for measuring the cumulative voltage drop across the first resistive element and the second resistive element.

[0022] If the resistance value of the first resistive element is smaller than the resistance value of the second resistive element, and especially if it differs so significantly that the two voltages must be measured with different measuring ranges, the independence of the measured values ​​is improved.

[0023] A process for producing a ribbon-shaped composite material comprises the following steps: a. Providing at least one first tape, one second tape and one third tape made of a material with high electrical conductivity, b. Providing at least one fourth band and one fifth band, each made of a resistance material, wherein the material of the fourth band and the material of the fifth band differ, c. Longitudinal seam welding of the strips, so that a composite of strips is formed in which the two strips made of resistance material each border on one of the strips made of the material with high electrical conductivity at their two longitudinal edges.

[0024] In step c), it is possible that first a first partial composite, consisting of the first and fourth bands, and a second partial composite, consisting of the second and third bands as well as the fifth band arranged between these two bands, are each formed by longitudinal seam welding, and then the first partial composite and the second partial composite are joined by longitudinal seam welding.

[0025] It is further provided that between process step b) and process step c), the strips are arranged such that the fourth and fifth strips are each located between two strips made of a material with high electrical conductivity, and that one of the strips made of material with high electrical conductivity is located between the two strips made of resistance material. With this aforementioned process and its variants with respect to step c) and the realization of the arrangement of the strips between process steps b) and c), a strip-shaped composite material is provided in which, by the step of cutting the strip-shaped composite material transversely to the longitudinal direction of the strip, a resistance arrangement of the type described above is produced and provided.

[0026] It is also possible that the connecting means for connecting the resistor arrangement to a circuit are incorporated into the two connection elements.

[0027] Furthermore, at least one of the resistance elements can be trimmed to set the desired resistance value. Trimming is achieved by shortening that single resistance element, thereby reducing its cross-sectional area.

[0028] Further advantages, features, and details of the invention will become apparent from the claims, the following description of preferred embodiments, and the drawings. These show: Fig. 1. A perspective, schematic representation of a resistance arrangement, Fig. 2 one of the Fig. 1 corresponding representation with the connected first and second measuring connection pair, and Fig. 3 one of the Fig. 1 corresponding representation with the connected first and third measuring connection pair.

[0029] In Fig. Figure 1 shows a resistance arrangement which is advantageously provided by a method for producing a ribbon-shaped composite material, wherein the method comprises the following steps: a) Providing at least one first band 1, one second band 2 and one third band 3 made of a material with high electrical conductivity, b) Providing at least one fourth volume 4 and one fifth volume 5, each made of a resistance material, wherein the material of the fourth volume 4 and the material of the fifth volume 5 differ, c) Longitudinal seam welding of the strips 1, 2, 3, 4, 5, so that a composite of strips 1, 2, 3, 4, 5 is formed, in which the two strips made of resistance material each border on their two longitudinal edges one of the strips 1, 2, 3 made of the material with high electrical conductivity.

[0030] In this step c), it is possible that first a first partial assembly 6, consisting of the first band 1 and the fourth band 4, and a second partial assembly 7, consisting of the second band 2 and third band 3 as well as the fifth band 5 arranged between these two bands 2, 3, are each formed by longitudinal seam welding, and then the first partial assembly 6 and the second partial assembly 7 are joined by longitudinal seam welding.

[0031] Alternatively, the process can also be modified so that between process step b) and process step c) the strips are arranged such that the fourth strip 4 and the fifth strip 5 are each located between two strips made of a material with high electrical conductivity, and that one of the strips 2 made of material with high electrical conductivity is located between the two strips 4, 5 made of resistance material.

[0032] When the ribbon-shaped material composite is then cut perpendicular to the longitudinal direction of the ribbon, a resistance arrangement 8 is produced which is characterized by the following structure: a first electrically conductive terminal element 10 and a second electrically conductive terminal element 11, a first resistive element 12 which is electrically conductively connected to the first terminal element 10, a second resistive element 13 which is electrically conductively connected to the second terminal element 11, an electrically conductive intermediate element 14 which is arranged between the first resistive element 12 and the second resistive element 13 and is electrically conductively connected to these resistive elements 12, 13, wherein the terminal elements 10, 11, the resistive elements 12, 13 and the intermediate element 14 are arranged side by side in a row, and wherein the terminal elements 10, 11 and the intermediate element 14 on the one hand and the resistive elements 12, 13 on the other hand are made of different materials.The essential point is that the material of the first resistance element 12 differs from the material of the second resistance element 13, so that a “parallel drift” of the two resistance elements 12, 13 or similar effects can be more reliably excluded than if both resistance elements 12, 13 were made of the same material or even from the same batch of material.

[0033] The intermediate element 14 is formed in a strip shape and is narrower than each of the two plate-shaped connecting elements 10, 11.

[0034] The Fig. Figure 1 shows that only the first connection element 10 and the second connection element 11 have connecting means 15 for integration into a circuit, i.e. the intermediate element 14 cannot be connected to a circuit.

[0035] The thickness of the resistive elements 12, 13 is each less than the thickness of both the terminal elements 10, 11 and the intermediate element 14. This allows, in particular, the resistive elements 12, 13 to be spaced away from a circuit board when the resistor assembly 8 is mounted on this board. It also makes it easier to trim at least one of the resistive elements 12, 13 during the manufacture of the resistor assembly 8.

[0036] Furthermore, the first resistive element 12 has a thickness that differs from the thickness of the second resistive element 13, thus enabling a better matching of the resistance values ​​of the two resistive elements 12, 13, particularly with regard to the fact that the resistance value of the first resistive element 12 is smaller, and in particular significantly smaller, than the resistance value of the second resistive element 13, in order to enforce different measuring ranges and improve the independence of the measured values.

[0037] Fig. Figure 2 shows that a first measuring connection pair 9 is provided for measuring the electrical voltage drop across the first resistive element 12 and a second measuring connection pair 16 is provided for measuring the voltage drop across the second resistive element 13, wherein a first measuring connection from the first measuring connection pair 9 and a second measuring connection from the second measuring connection pair are assigned to the intermediate element 14.

[0038] However, it is also possible that the first pair of measuring terminals 9 are provided for measuring the electrical voltage drop across the first resistive element 12 and a further pair of measuring terminals 19 for measuring the cumulative voltage drop across the first resistive element 12 and the second resistive element 13, as shown in Fig. 3 is shown.

[0039] This measuring arrangement can be integrated into a measuring circuit which, in addition to the resistor arrangement 8, comprises a first voltage tap for measuring a first electrical voltage that drops across the first resistive element 12, a second voltage tap for measuring a second electrical voltage that includes at least the electrical voltage dropping across the second resistive element 13, and at least one electronic component for determining the first electrical voltage and the second electrical voltage, wherein a comparator is provided for comparing the measured first electrical voltage and the measured second electrical voltage, with which the reliability of the measured values ​​can be assessed.

[0040] The electronic component is designed in such a way that the measurement of the first electrical voltage and the measurement of the second electrical voltage can be carried out independently of each other. LIST OF REFERENCE SYMBOLS: 1 first volume 2 second volume 3 third volume 4 fourth volume 5 fifth volume 6 first sub-group 7 second sub-unit 8. Resistor arrangement 9 first measuring connection pair 10 first connection element 11 second connection element 12 first resistance element 13 second resistance element 14 Intermediate element 15 fasteners 16 second measuring connection pair 17 first measuring connection 18 second measuring connection 19 additional measuring connection pairs

Claims

[1] Measuring circuit comprising a resistor arrangement (8) comprising: a first electrically conductive connection element (10) and a second electrically conductive connection element (11), a first resistance element (12) which is electrically connected to the first connection element (10), a second resistance element (13) which is electrically connected to the second connection element (11), an electrically conductive intermediate element (14) arranged between the first resistance element (12) and the second resistance element (13) and electrically conductively connected to these resistance elements (12, 13), wherein the connection elements (10, 11), the resistance elements (12), (13) and the intermediate element (14) are arranged next to one another in a row, and wherein the connection elements (10, 11) and the intermediate element (14) on the one hand and the resistance elements (12, 13) on the other hand are made of different materials, wherein the material of the first resistance element (12) differs from the material of the second resistance element (13), characterized by that the measuring circuit further comprises: a first voltage tap for measuring a first electrical voltage dropped across the first resistance element (12), a second voltage tap for measuring a second electrical voltage, which comprises at least the electrical voltage drop across the second resistance element (13), and at least one electronic component for determining the first electrical voltage and the second electrical voltage, wherein a comparator is provided for comparing the measured first electrical voltage and the measured second electrical voltage. [2] Measuring circuit according to claim 1, characterized by that the electronic component is designed so that the measurement of the first electrical voltage and the measurement of the second electrical voltage can be carried out independently of one another. [3] Measuring circuit according to claim 1 or 2, characterized by that in the resistor arrangement (8) the two connecting elements (10, 11) are plate-shaped and the intermediate element (14) is strip-shaped and that the intermediate element (14) is narrower than each of the two connecting elements (10, 11). [4] Measuring circuit according to one of claims 1 to 3, characterized by that in the resistor arrangement (8) only the first connection element (10) and the second connection element (11) have connecting means (15) for integration into an electrical circuit. [5] Measuring circuit according to one of claims 1 to 4, characterized bythat in the resistor arrangement the thickness of the resistor elements (12, 13) is each smaller than both the thickness of the connecting elements (10, 11) and the thickness of the intermediate element (14). [6] Measuring circuit according to one of claims 1 to 5, characterized by that in the resistor arrangement (8) the first resistor element (12) has a thickness which differs from the thickness of the second resistor element (13). [7] Measuring circuit according to one of claims 1 to 6, characterized bythat in the resistor arrangement (8) a first measuring connection pair (9) for measuring the electrical voltage drop across the first resistance element (12) and a second measuring connection pair (16) for measuring the voltage drop across the second resistance element (13) are provided and that a first measuring connection (17) from the first measuring connection pair (9) and a second measuring connection (18) from the second measuring connection pair (16) are assigned to the intermediate element (14). [8] Measuring circuit according to one of claims 1 to 7, characterized by that in the resistor arrangement (8) a first pair of measuring connections (9) for measuring the electrical voltage drop across the first resistance element (12) and a further pair of measuring connections (19) for measuring the cumulative voltage drop across the first resistance element (12) and the second resistance element (13) are provided. [9] Measuring circuit according to claim 8, characterized bythat in the resistance arrangement (8) the resistance value of one of the resistance elements (12, 13) is smaller than the resistance value of the other resistance element (13, 12). [10] A method for producing a band-shaped material composite, the method comprising the following steps: a) providing at least a first band (1), a second band (2) and a third band (3) made of a material with high electrical conductivity, b) providing at least one fourth band (4) and one fifth band (5) each made of a resistance material, wherein the material of the fourth band (4) and the material of the fifth band (5) differ, c) longitudinal seam welding of the strips (1, 2, 3, 4, 5) so that a composite of strips (1, 2, 3, 4, 5) is formed, in which the two strips (4, 5) of resistance material each border on one of the strips (1, 2, 3) of the material with high electrical conductivity at their two longitudinal edges. [11] Method according to claim 10, characterized by that in step c) first a first partial composite (6), which consists of the first band (1) and the fourth band (4), and a second partial composite (7), which consists of the second band (2) and third band (3) as well as the fifth band (5) arranged between these two bands (2, 3), are each formed by longitudinal seam welding and then the first partial composite (6) and the second partial composite (7) are joined by longitudinal seam welding. [12] Method according to claim 10, characterized bythat between process step b) and process step c) the bands are arranged in such a way that the fourth band (4) and the fifth band (5) are each located between two bands made of a material with high electrical conductivity, and that one of the bands (2) made of material with high electrical conductivity is located between the two bands made of resistance material (4, 5). [13] Method according to one of claims 10 to 12, comprising the step of severing the band-shaped material composite transversely to the band longitudinal direction, for producing a resistor arrangement (8) according to one of claims 1 to 9. [14] Method according to claim 13, characterized by that the connecting means (15) for connecting the resistor arrangement (8) to an electrical circuit are introduced into the two connecting elements (10, 11). [15] Method according to claim 13 or 14, characterized bythat at least one of the resistance elements (12, 13) is trimmed.

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