CURRENT SENSOR

Description

[0001] The invention relates to a current sensor, in particular for a vehicle battery in a vehicle, comprising an electrical conductor having a first connection and a second connection for contacting a vehicle circuit, as well as a first current measuring device and a second current measuring device for detecting at least one measured value for the current flowing through the electrical conductor, and a first evaluation circuit which is connected to the first current measuring device and / or the second current measuring device and which can receive the measured values ​​of the first current measuring device and / or the second current measuring device and output at least one current measurement signal dependent on the measured values.

[0002] In vehicles with batteries, especially electric or hybrid vehicles where batteries are used to power the drive system, it is necessary to continuously monitor the batteries and their condition during operation. In particular, it is essential to continuously monitor the battery charge level. For this purpose, current sensors are used in the vehicles, positioned in the electrical circuit, to detect both the charging and discharging currents of the batteries.

[0003] To ensure the required reliability and accuracy of current measurement in the automotive sector, redundant current measurement is necessary. Examples of such redundant current measurement are shown in JP 2009 28 1773 A, DE 10 2014 216 419 A1, US 2014 212 714 A1, and KR 2016 0111166 A. Preferably, this redundant current measurement uses two independent physical measurement principles to avoid or minimize measurement errors due to systematic errors or errors inherent in one measurement principle. The use of different measurement principles is also referred to as asymmetric redundancy. Such a sensor is shown, for example, in EP2732295A1, EP 1 213 189 A1, and US 2017 / 261536 A1.

[0004] EP 1 213 189 A1 relates to a device for monitoring a vehicle's electrical system with a sensor, wherein a second sensor is provided for measuring the current in a connecting line, the measuring range of which is different from the measuring range of the first sensor and at least one of the two sensors is designed for a potential-free measurement of the current.

[0005] US 2017 261 536 A1 deals with a hybrid current sensor device comprising an electrical conductor, a Hall sensor module for detecting the current flow in the electrical conductor, and a shunt sensor module for detecting the current flow in the electrical conductor.

[0006] JP 2009 281 773 A describes a shunt resistance sensor which determines the current flow in an electrical conductor by means of a shunt resistor and a Hall sensor, wherein switching devices are provided for generating an offset value from the sensor signals and an offset removal device is provided which removes the offset from the sensor signals.

[0007] DE 10 2014 216 419 A1 discloses a method for checking at least one measuring device for measuring an electric current flowing through the current path, wherein a further computing device is provided for checking the proper control and / or regulation of the measurement of the at least one measuring device by its computing device, which communicates with this computing device of the at least one measuring device by means of question-and-answer communication.

[0008] US 2014 212 714 A1 deals with a battery management system wherein a first microcontroller is trained to evaluate measurement data acquired by a first measuring unit and a second microcontroller is trained to evaluate measurement data acquired by a second measuring unit independent of the first measuring unit.

[0009] KR 2016 111 166 A discloses a shunt sensor compensation device comprising a battery, a Hall sensor and a shunt sensor, wherein a control unit receives time-collected difference data of the current value from an integration unit and compensates the current value of the shunt sensor by accumulating or adding the collected sum data as a shunt sensor compensation value.

[0010] However, the design and manufacture of such sensors is very complex.

[0011] The object of the invention is to provide a current sensor with redundant current measurement that has high measurement accuracy and high reliability and is easy to manufacture.

[0012] To solve the problem, a current sensor, particularly for a vehicle battery in a vehicle, is provided, comprising an electrical conductor with a first terminal and a second terminal for connection to a vehicle's electrical circuit, as well as a first current measuring device and a second current measuring device for detecting at least one measured value of the current flowing through the electrical conductor. The second current measuring device is electrically connected in series with the first current measuring device. The current sensor further comprises a first evaluation circuit, which is connected to the first current measuring device and / or the second current measuring device and can receive the measured values ​​from the first current measuring device and / or the second current measuring device and output a current measurement signal dependent on the measured values. The first current measuring device includes a Hall sensor.The electrical conductor has a measuring section with a constriction of reduced cross-section in the area of ​​the first current measuring device, with the Hall sensor being arranged in this constriction. The current sensor has a first communication interface for outputting the measured values ​​of the first current measuring device and a second communication interface for outputting the current measurement signal of the second current measuring device.

[0013] A second evaluation circuit is provided, with a communication link between the first and second evaluation circuits. The first evaluation circuit can send a first test signal to the second evaluation circuit, and / or the second evaluation circuit can send a second test signal to the first evaluation circuit. The first evaluation circuit can check the second test signal, and / or the second evaluation circuit can check the first test signal. If the second test signal deviates from a second reference value, the first evaluation circuit can send a first correction signal, and the second evaluation circuit can send a second correction signal if the first test signal deviates from a first reference value.

[0014] This can have several advantages. Firstly, evaluating the measured values ​​outside the current sensor allows for additional verification of the current sensor's function, particularly the evaluation circuitry.

[0015] For example, the measured values ​​from the first current measuring device are not evaluated, but merely output so that they can be evaluated, for example, by a downstream vehicle control unit. The measured values ​​from the second current measuring device, on the other hand, are evaluated, and only a current measurement signal is output.

[0016] Typically, a Hall sensor with an iron core is used, which circumferentially surrounds the electrical conductor. The Hall sensor is positioned in a gap within the iron core. The electric current flowing through the conductor generates a magnetic field in the iron core, which can then be detected by the Hall sensor. However, the arrangement of such an iron core and the positioning of the Hall sensor are very complex. According to the invention, a so-called differential Hall sensor is used instead of a Hall sensor with an iron core. A recess is provided in the electrical conductor in which the Hall sensor is positioned. The magnetic field generated in this constriction or recess by the electric current is strong enough to be detected by the Hall sensor. Thus, an iron core for generating or amplifying the magnetic field can be dispensed with.The current sensor can therefore be made significantly more compact. Furthermore, the design is much simpler, as only the Hall sensor needs to be positioned and aligned within the recess. No additional alignment or positioning of the iron core or the Hall sensor on that core is required.

[0017] In particular, the constriction is arranged such that a magnetic field as strong as possible is provided within it, which can be detected by the Hall sensor. Specifically, the geometry of the constriction can be determined taking into account the geometric shape of the electrical conductor, the measuring range and dimensions of the Hall sensor, or a desired strength of the magnetic field to be measured.

[0018] For example, the constriction can be formed by at least one slot extending from at least one face and / or edge of the electrical conductor. Such a slot is easy to manufacture and allows for simple positioning of the Hall sensor within it.

[0019] The constriction can be symmetrical with respect to a central axis of the electrical conductor running in the direction of current flow, and in particular, it can be a mirror image with respect to a plane passing through the central axis. This results in an asymmetrical, and especially mirror-image, influence on the current lines or potential lines with respect to the central axis, so that a magnetic field that is as homogeneous as possible can be generated.

[0020] For example, the electrical conductor can be plate-shaped and the constriction is formed by two slots extending symmetrically into the electrical conductor from opposite edges of the conductor with respect to the central axis.

[0021] The second current measuring device preferably uses a different physical measuring principle than the first current measuring device. For example, the second current measuring device can have a measuring resistor and at least one first measuring contact for detecting a first voltage potential and at least one second measuring contact for detecting a second voltage potential, wherein the first measuring contact and the second measuring contact are arranged offset in the current direction. In particular, the first measuring contact can be arranged longitudinally along the electrical conductor upstream of the measuring resistor and the second measuring contact downstream of the measuring resistor. The voltage drop across the measuring resistor can be determined from the measured voltage potentials. From the known electrical resistance of the measuring resistor or a measuring path between the measuring contacts and the measured voltage drop, the current across the measuring resistor can be determined using Ohm's law.The current flowing along the measuring section, i.e., the electrical conductor, is calculated.

[0022] In particular, a symmetrical design of the constriction of the first current measuring device can also be advantageous for the second current measuring device, since this results in a symmetrical influence on the current lines or the potential lines.

[0023] For example, both current measuring devices are contacted with the first evaluation circuit, which processes the measured values ​​of both current measuring devices and generates a common current measurement signal or a current measurement signal for each of the current measuring devices.

[0024] The second evaluation circuit can function solely as a monitoring circuit and not perform any evaluation of the measured values ​​from the current measuring devices. Optionally, however, the second evaluation circuit can also receive and evaluate the measured values ​​from the current measuring devices.

[0025] The first and second evaluation circuits essentially monitor each other and, in the event of a malfunction in the other, initiate appropriate measures to correct the malfunction. If one evaluation circuit detects a malfunction in the other, a correction signal is sent, which then triggers a suitable measure for the other evaluation circuit.

[0026] The mutual verification of the evaluation circuits provides increased safety within the current sensor, as malfunctions within the current sensor can be detected and corrected.

[0027] The communication link is, for example, a bidirectional connection, where the test signals from both evaluation circuits are sent via this connection. However, the communication link can also have multiple lines, for example, a separate line for each test signal, in order to detect faults in the communication link.

[0028] For example, the first evaluation circuit can have a first correction circuit for receiving the first correction signal, and the second evaluation circuit can have a second correction circuit for receiving the second correction signal. The first correction circuit is designed to trigger a correction process for the first evaluation circuit, and the second correction circuit is designed to trigger a correction process for the second evaluation circuit. After being initiated by the other evaluation circuit with the correction signal, the measures to correct the malfunction are initiated by the respective evaluation circuit itself. Subsequently, the other evaluation circuit can verify whether the correction of the malfunction was successful by sending a test signal.

[0029] The correction process of the first and / or second evaluation circuit includes, for example, a restart and / or a reset of the evaluation circuit. In particular, the first and / or the second evaluation circuit may have a first or second correction circuit, respectively, which receives the correction signal and initiates corrective actions, especially a restart or a reset of the respective evaluation circuit. An additional correction circuit ensures that the triggering of the corrective actions is not prevented by a faulty evaluation circuit itself.

[0030] The test signal can contain various pieces of information that enable a diagnosis of the other evaluation circuit. For the information transmitted with the test signal, reference values ​​are preferably stored in the respective evaluation circuit, or these values ​​are received or determined by the respective evaluation circuit itself. In particular, threshold values ​​can be defined for the information, by which the information may deviate from the reference values.

[0031] In particular, the test signals are sent periodically, especially at regular intervals. This allows the absence of a test signal to be detected and identified as a malfunction of the respective evaluation circuit. Optionally, a request signal can also be sent, prompting the respective evaluation circuit to send the test signal.

[0032] For example, additional information about the request signal can also be requested in order to perform a more accurate diagnosis of the other evaluation circuit.

[0033] For example, the first test signal contains status information and / or operating information from the first evaluation circuit, and / or the second test signal contains status information and / or operating information from the second evaluation circuit. If this status information and / or operating information deviates from predefined parameters, a malfunction of the respective evaluation circuit must be assumed, requiring corrective action.

[0034] The first test signal can also include measured values ​​and / or a current measurement signal from the first evaluation circuit, and / or the second test signal can include measured values ​​and / or a current measurement signal from the second evaluation circuit. Comparing the measured values ​​and / or the current measurement signals allows verification not only of the functionality of each evaluation circuit, but also of its correct reception and evaluation of the measured values ​​from the respective current measuring device.

[0035] Furthermore, the first test signal and / or the second test signal may contain status information and / or operating information of the first current measuring device and / or the second current measuring device.

[0036] To improve the reliability of the current sensor and / or the functional test, the first and second evaluation circuits can have separate power supplies and / or separate outputs for a current measurement signal. Separate power supplies for the two evaluation circuits ensure that malfunctions due to a faulty power supply do not affect both circuits. This allows for more reliable detection of a malfunction in one of the two evaluation circuits. The separate outputs for the current measurement signal enable the signals to be output separately. This allows them, for example, to be transmitted via the communication link or made available separately to a higher-level vehicle control system.In particular, further processing of the current measurement signals can take place in a higher-level vehicle control system, for example an additional comparison of the measured values ​​or the current measurement signals of both evaluation circuits.

[0037] The measured values ​​and / or current measurement signals can be output either analogously or digitally. For example, the current measurement signals from the second current measuring device are output digitally, and the measured values ​​from the first current measuring device are output analogously, particularly without prior processing or evaluation.

[0038] Due to the high voltages and currents involved, it may be necessary to protect parts of the current sensor, particularly the evaluation circuitry, from the communication interfaces and a downstream vehicle control unit against voltage flashover, for example, by means of galvanic isolation. Specifically, in a second current measuring device with a measuring resistor, the measuring contacts are in direct contact with the electrical conductor and the evaluation circuitry, so the evaluation circuitry must be protected against voltage flashover to the vehicle control unit or other parts of the current sensor. A Hall sensor, on the other hand, operates without contact, so it may not be necessary to protect it against voltage flashover. Since the first current measuring device in this embodiment has a separate communication interface for outputting the measured values, no electrical connection to either of the evaluation circuits is required.Insulation or protection for areas that may come into contact with high voltage is therefore unnecessary. This allows for a significantly simpler design of the current sensor. In particular, it is not necessary to additionally protect the communication interface of the first current measuring device against voltage flashovers.

[0039] Regardless of the design, the first communication interface and / or the second communication interface may also have protective devices against positive and / or negative overvoltage and / or for potential separation.

[0040] Furthermore, the first evaluation circuit and / or the second evaluation circuit can have insulation, in particular galvanic isolation, by which the first evaluation circuit and / or the second evaluation circuit is isolated from other areas of the current sensor or other parts of a vehicle.

[0041] Further advantages and features will become apparent from the following description in conjunction with the attached drawings. These show Figure 1 shows a first embodiment of a current sensor according to the invention, and Figure 2 shows a second embodiment of a current sensor according to the invention.

[0042] In Figure 1Figure 10 shows a battery sensor 10 for a vehicle battery 12 in a vehicle. The battery sensor 10 is arranged in a circuit 14 in which the vehicle battery 12 and at least one load 16 are located. The battery sensor 10 is arranged such that all charging and discharging currents of the vehicle battery 12 flow through the battery sensor 10 and can thus be measured by it. A very precise determination of the state of charge of the vehicle battery 12 is possible based on the measured charging and discharging currents.

[0043] The battery sensor 10 has an electrical conductor 18, which is arranged in the circuit 14 and has a first terminal 20 and a second terminal 22. The terminals 20, 22 may, for example, have a bore 21, 23 for a screw connection to the circuit 14.

[0044] Furthermore, the battery sensor 10 has a first current measuring device 24 and a second current measuring device 25, which can determine the current flowing through the electrical conductor 18.

[0045] The first current measuring device 24 has a Hall sensor 26 with a first Hall cell 28 and a second Hall cell 30. The electrical conductor 18 has a constriction 32 in the area of ​​the Hall sensor 26, which is formed by two slots 34 extending from opposite edges of the electrical conductor.

[0046] The slots 34 are arranged symmetrically with respect to a central axis 36 extending in the longitudinal direction L of the electrical conductor. The slots 34 are arranged such that one of the Hall cells 28, 30 of the Hall sensor 26 is located in one of the slots 34 or is arranged in the immediate vicinity of it.

[0047] The current flowing through the electrical conductor 18 generates a magnetic field around the conductor 18 and in the constriction 32, which can be detected by the Hall sensor 26. The magnetic field changes with the current flowing through the conductor 18, so the current flowing through the conductor 18 can be determined from the strength of the magnetic field or its change. Typically, an iron core is arranged around the conductor 18 to provide a sufficiently strong magnetic field that can be detected by the Hall sensor 26. In In the embodiment shown here, a constriction 32 is used instead of an iron core, in which the Hall sensor 26 is arranged. The Hall sensor 26 is a so-called differential Hall sensor, which can detect the magnetic field generated by the current in the constriction 32. This eliminates the need for an additional iron core.

[0048] The Hall sensor 26 is connected to a first evaluation circuit 40 via a communication line 38. The evaluation circuit 40 can receive the measured values ​​from the Hall sensor 26 via the communication line 38, evaluate them, and generate a current measurement signal from them, which is, for example, proportional to the current flowing through the electrical conductor 18.

[0049] The evaluation circuit 40 includes a first analog-to-digital converter 42 and a first microcontroller 44. The current measurement signals generated by the microcontroller 44 can then be output via a first communication interface 46, for example to a downstream vehicle control unit.

[0050] The second current measuring device 25 has a measuring resistor 48 arranged in the current path. In Longitudinal direction L,Thus, in the direction of current flow, a first measuring contact 50 and a second measuring contact 52 are provided upstream and downstream of the measuring resistor 48, each capable of detecting a voltage potential on the electrical conductor 18. The measuring contacts 50 and 52 are connected to the first evaluation circuit 40 via communication lines 54 and 56. The evaluation circuit 40 includes a second analog-to-digital converter 58, which is connected to the microcontroller 44.

[0051] The analog-to-digital converter 58 and the microcontroller 44 can be used to measure the voltage drop across a defined measuring path between the measuring contacts 50 and 52, or across the measuring resistor 48, from the voltage potentials of the measuring contacts 50 and 52. From this voltage drop and the known resistance of the measuring path or the measuring resistor 48, the current flowing through the measuring path or the measuring resistor 48, i.e., the current flowing through the electrical conductor 18, can be calculated using Ohm's law.

[0052] The microcontroller 44 can output the current measurement signals determined from the measured values ​​of the first current measuring device 24 and the second current measuring device 25 individually or together to the communication interface 46, so that these can be output to a vehicle control system.

[0053] In addition, further adjustments to the measured values ​​and / or the current measurement signals can be made in the microcontroller 44, for example calibration or temperature compensation.

[0054] As particularly in Figure 1 As can be seen, a potential separation zone 60 is provided to prevent a voltage flashover between the areas of the current sensor 10 in contact with the electrical conductor 18 and the vehicle electronics or vehicle control system. The potential separation zone includes a protective device 62 to enable the transmission of the current measurement signals to the vehicle electronics or vehicle control system with a sufficiently high level of protection against voltage flashover. For example, the communication interface 46 can also be integrated into the protective device 62.

[0055] The first evaluation circuit 40 also includes a correction circuit 64, which can initiate appropriate measures to rectify a malfunction of the evaluation circuit 40. For example, the correction circuit 64 can cause a restart or a reset of the evaluation circuit 40.

[0056] Furthermore, a second evaluation circuit 66 is provided, which is connected to the first evaluation circuit 40 via a communication link 68. The communication link 68 is, for example, a bidirectional communication line through which information can be exchanged between the first evaluation circuit 40 and the second evaluation circuit 66.

[0057] Furthermore, the second evaluation circuit 66 has a second correction circuit 70 and at least one input 72 for operating information from the current sensor 10, for example, the microcontroller 44, the evaluation circuit 40, the first current measuring device 24, and / or the second current measuring device 25. Input 72 is connected to an analog-to-digital converter 74.

[0058] The first evaluation circuit 40 and the second evaluation circuit 66 can exchange information via the communication link 68 to check the proper operating status of the other evaluation circuit 66, 40. Preferably, the evaluation circuit 40, 66 each send a test signal with predefined information via the communication link 68, which is checked by the other evaluation circuit 66, 40. If the information contained in the test signal does not match the information stored in, received by, or determined by the evaluation circuit 66, 40, a correction signal is sent to the correction circuit 64, 70 of the other evaluation circuit 40, 66. For example, based on this correction signal, the respective evaluation circuit 40, 66 is restarted or reset.

[0059] For example, the test signals can contain operating information or status information of the first current measuring device 24, the second current measuring device 25 and / or the respective other evaluation circuit 40, 66.

[0060] If the test signal contains operating or status information from the first current measuring device 24 and / or the second current measuring device 25, this information can be received and processed or evaluated by both evaluation circuits 40 and 66. The processed or evaluated operating or status information can then be transmitted with the test signal via the communication link to the other evaluation circuit 40 or 66. This circuit can compare the information contained in the test signal with the information evaluated by its own evaluation circuit 40 or 66. If the evaluated information differs, it must be assumed that the evaluation in the evaluation circuit 40 or 66 is faulty and therefore the evaluation circuit 40 or 66 is not functioning correctly.If this is the case, a correction signal can then be generated by the other evaluation circuit 66, 40 and sent to the evaluation circuit 40, 66.

[0061] For example, the operating information or status information includes the operating voltages of the first current measuring device 24, the second current measuring device 25, and / or the evaluation circuit in 40, 66. For example, the operating voltages of the current measuring devices 24, 25 are provided by the first evaluation circuit 40, so that the method described above can also be used to verify whether the correct operating voltages are being provided. In particular, in this embodiment, the operating voltages of the current measuring devices 24, 25 can be sent directly to the second evaluation circuit 66 via an output 74 and to the input 72 of the second evaluation circuit 66, respectively, and verified by it.

[0062] Alternatively, the test signals can also contain measured values ​​and / or information derived from the measured values, for example, a current measurement signal. The measured values ​​received by both evaluation circuits 40 and 66 and / or the evaluated information can be compared. If these differ, a malfunction of the evaluation circuit 40 or 66 must be assumed.

[0063] For example, the test signals are sent periodically at predefined time intervals. The absence of a test signal or a delayed transmission of a test signal can therefore also be interpreted as a malfunction of the respective evaluation circuit 40, 66.

[0064] In particular, even after sending the correction signal and a subsequent restart or reset of the evaluation circuit 40, 66, a new test signal can be sent immediately to check whether the restart or reset of the evaluation circuit 40, 66 was successful and the malfunction has been rectified. For example, in such a case, a test signal can also be requested from the evaluation circuit 40, 66 via the communication link 68.

[0065] The in Figure 2The embodiment shown also has an electrical conductor 18 with a first current measuring device 24 and a second current measuring device 25. The operating principles of the current measuring devices 24 and 25 correspond to the embodiment shown in Figure 1. The first current measuring device 24 has a Hall sensor 26. The second current measuring device 25 has a measuring resistor 48 and two measuring contacts 50 and 52. Furthermore, a first evaluation circuit 40 is provided, which is connected to the measuring contacts 50 and 52 of the second current measuring device 25. The structure of the first evaluation circuit 40 essentially corresponds to that shown in Figure 1. Figure 1 shown first evaluation circuit 40.

[0066] In contrast to the one in Figure 1In the embodiment shown, the Hall sensor 26 has a separate power supply 76 as well as separate second communication interfaces 78, 80 for outputting the measured values ​​and / or an error signal, operating information and / or status information.

[0067] The communication interface 78 can output the measured values ​​from the Hall sensor 26 unchanged, for example to a vehicle control unit. In the vehicle control unit, the measured values ​​from the Hall sensor 26 can be evaluated and processed. The evaluated measured values ​​from the Hall sensor 26 can then be compared with the current measurement signals from the second current measuring device 25, which are output via the first communication interface 46.

[0068] As in Figure 2 As can be seen, the communication interfaces 78, 80 and the power supply 76 have protective devices 82, 84, 86 against a positive and / or negative overvoltage.

[0069] Furthermore, only the first evaluation circuit 40 is located within the potential separation zone 60. Since the measuring contacts 50 and 52 are in direct contact with the electrical conductor 18, it is also necessary in this embodiment to separate or isolate them from the other areas of the current sensor and from a vehicle control unit. Because the Hall sensor 26 measures without contact and is therefore not in conductive contact with the electrical conductor 18, it can be located outside the potential separation zone 60. The protective devices 82, 84, and 86 nevertheless provide additional protection against positive and / or negative overvoltage.

[0070] Furthermore, no communication connection 68 is provided in the embodiment shown here. In this embodiment, a comparison of the measured values, current measurement signals, operating information, and / or status information can be performed in the vehicle control unit. For this reason, information from which a test signal can be derived, such as error signals, operating information, or status information from the Hall sensor 26, is output via the communication interface 80. Additionally, the information from the first evaluation circuit 40 can be output unprocessed or as a test signal via the first communication interface 46.

Claims

1. A current sensor (10), in particular for a vehicle battery (12) in a vehicle, with an electrical conductor (18) which has a first port (20) and a second port (22) for contacting an electrical circuit (14) of a vehicle, and with a first current measuring device (24) and a second current measuring device (25) for the detection of at least one measured value for the current flowing over the electrical conductor (18), wherein the second current measuring device (25) is arranged electrically in series with the first current measuring device (24), and with a first evaluation circuit (40) which is connected to the first current measuring device (24) and the second current measuring device (25) and can receive the measured values of the first current measuring device (24) and the second current measuring device (25) and output a current measuring signal depending on the measured values, wherein the first current measuring device (24) has a Hall effect sensor (26) and the electrical conductor (18) has a measuring section with a constriction (32) with a reduced cross section in the region of the first current measuring device (24), wherein the Hall effect sensor (26) is arranged in this constriction (32), wherein the current sensor (10) has a first communication interface (46) for the output of the current measuring signal of the second current measuring device (25) and a second communication interface (78) for the output of the measured values of the first current measuring device (24), and wherein the current sensor is characterised in that a second evaluation circuit (66) is provided, wherein a communication link (68) is provided between the first evaluation circuit (40) and the second evaluation circuit (66), wherein the first evaluation circuit (40) is able to send a first test signal to the second evaluation circuit (66) and the second evaluation circuit (66) is able to send a second test signal to the first evaluation circuit (40), wherein the first evaluation circuit (40) is able to check the second test signal and send a first correction signal in case of a deviation of the second test signal from a second reference value and wherein the second evaluation circuit (66) is able to check the first test signal and send a second correction signal in case of a deviation of the first test signal from a first reference value.

2. The current sensor as claimed in claim 1, characterised in that the constriction (32) is formed by at least one slot (34) which extends from at least a surface and / or an edge of the electrical conductor (18).

3. The current sensor as claimed in any one of claims 1 and 2, characterised in that the constriction (32) is configured so that it is symmetrical with respect to a central axis (36) of the electrical conductor (18) which runs in the longitudinal direction (L) of the electrical conductor (18), in particular mirror-symmetrical with respect to a plane which runs through the central axis (36).

4. The current sensor as claimed in any one of the preceding claims, characterised in that the second current measuring device (25) has a measuring resistor (48) and at least one first measuring contact (50) for the detection of a first voltage potential and at least one second measuring contact (52) for the detection of a second voltage potential, wherein the first measuring contact (50) and the second measuring contact (52) are arranged offset in the longitudinal direction (L).

5. The current sensor as claimed in claim 1, characterised in that the first evaluation circuit (40) has a first correction circuit (64) for the receipt of the first correction signal and / or the second evaluation circuit (66) has a second correction circuit (70) for the receipt of the second correction signal, wherein the first correction circuit (64) is provided for triggering a correction procedure for the first evaluation circuit (40) and the second correction circuit (70) is provided for triggering a correction procedure for the second evaluation circuit (66).

6. The current sensor as claimed in claim 5, characterised in that the correction procedure of the first and / or the second correction circuit (40, 66) comprise / s a restart of the evaluation circuit (40, 66) and / or a reset of the evaluation circuit (40, 66).

7. The current sensor as claimed in any one of claims 1 to 6, characterised in that the first test signal includes status information and / or operating information of the first evaluation circuit (40) and / or the second test signal includes status information and / or operating information of the second evaluation circuit (66).

8. The current sensor as claimed in any one of claims 1 to 7, characterised in that the first test signal includes measured values and / or a current measuring signal of the first evaluation circuit (40) and / or the second test signal includes measured values and / or a current measuring signal of the second evaluation circuit (66).

9. The current sensor as claimed in any one of claims 1 to 8, characterised in that the first test signal and / or the second test signal include / s status information and / or operating information of the first current measuring device (24) and / or the second current measuring device (25).

10. The current sensor as claimed in any one of claims 1 to 9, characterised in that the first evaluation circuit (40) and the second evaluation circuit (66) have separate current supplies and / or separate outlets for a current measuring signal.

11. The current sensor as claimed in claim 1, characterised in that the first communication interface (46) and / or the second communication interface (78) have / has protection devices (62, 84) against a positive and / or negative overvoltage and / or for potential separation.

12. The current sensor as claimed in any one of the preceding claims, characterised in that the first evaluation circuit (40) and / or the second evaluation circuit (66) have / has an insulation, in particular a galvanic isolation.