Battery sensor

Abstract

The invention relates to a battery sensor (10) for sensing at least one battery parameter, having at least two measuring units (16, 18), wherein the measuring units (16, 18) each comprise at least one sensing device (20, 22, 24, 26, 28, 30) for sensing at least one measured value, wherein the measuring units (16, 18) each have at least one evaluation circuit (38, 40) for determining at least one battery parameter from the at least one respectively sensed measured value, characterized in that at least one evaluation unit (58) is provided, which compares the battery parameters determined by the evaluation circuits (38, 40) and outputs an error signal when a defined difference between the battery parameters is exceeded.

Description

TECHNICAL FIELD

[0001] The present application relates to a battery sensor for sensing at least one battery parameter. BACKGROUND

[0002] Battery sensors are used in vehicles for sensing battery parameters, for example a battery current or a battery voltage of a vehicle battery. Such battery sensors comprise, for example, a measurement section which is arranged in a current path and along which measurement values are sensed, from which measurement values the battery parameter can be determined.

[0003] The battery sensor must have a high accuracy throughout the entire service life in order to be able to confirm the battery condition as accurately as possible. It must also be ensured that errors occurring in the determination of the battery parameters, in particular in the determination of the battery voltage or the battery current, are detected and / or prevented with a high degree of reliability.

[0004] It is known from the prior art, for example, to provide a fully redundant measurement of the battery parameters. However, this involves an extremely expensive design, since two completely separate measurement paths must be constructed, for example comprising two completely separate battery sensors. Such a construction also requires a very large amount of space. SUMMARY

[0005] It is an object of the present application to provide a battery sensor which can detect and / or prevent errors occurring in the measurement of the battery parameters with a very high degree of reliability and which has a very compact construction.

[0006] To achieve this object, a battery sensor for sensing at least one battery parameter is provided, which has at least two measurement units, wherein the measurement units each comprise at least one sensing device for sensing at least one measurement value. The measurement units each comprise at least one evaluation circuit for determining at least one battery parameter from the at least one measurement value sensed respectively. At least one evaluation unit is provided which compares the battery parameters determined by the evaluation circuits and outputs an error signal in the event of a defined difference between the battery parameters being exceeded.

[0007] The battery sensor thus has two measuring units which work independently of one another, each determining the same battery parameter(s). The battery parameters determined by the two measuring units are compared with one another, preferably inside the battery sensor. Since the same measurement values are sensed by the two measuring units, the determined battery parameters must match one another or can only differ from one another by a defined value. If this difference is exceeded, an error signal is output. At least two measuring sections are thus provided inside the battery sensor for one battery parameter, which can be compared with one another. The fact that these measuring sections relate to the same measurement values ensures that, in the case of correct operation, these measuring sections determine the same battery parameter or a battery parameter which only differs slightly from one another. The measuring units can also have shared contacts for sensing the measurement values, for example. This can reduce the number of contacts and also ensures that the measuring units sense the same measurement values. The difference in the determined battery parameters must thus be caused by an error within the measuring unit and the error source can thus be located.

[0008] In order to make the battery sensor as compact as possible, the evaluation unit can be integrated in at least one evaluation circuit, wherein these evaluation circuits are connected to one another by a signal line via which the battery parameters are transmitted to the evaluation unit. This means that no additional circuit is required in order to compare the battery parameters with one another. This is done in one of the measuring units. In order to further improve the accuracy, the evaluation unit can also be present in a plurality of measuring units, in which case the values of the plurality of measuring units can likewise be compared with one another.

[0009] The evaluation unit can also be provided in a higher-level controller, for example a vehicle controller, thus allowing a smaller design of the battery sensor.

[0010] In addition, a diagnostic unit can be provided in at least one measuring unit, which is used to carry out a self-test of the measuring unit and / or of the at least one sensing device. A specific measuring unit can thus be self-diagnosed or calibrated. This can further improve the reliability and / or the accuracy of the battery sensor. Furthermore, the self-diagnosis can detect errors inside a specific measuring unit, whereby an error detection can be carried out even if both measuring units have errors which can lead to the same or similar battery parameter outputs. In addition, by means of the calibration, the accuracy of a specific measuring unit can also be improved, so that the measurement accuracy of the entire battery sensor can additionally be improved.

[0011] The measurement units can differ in their construction and / or in the way the battery parameters are determined. Thereby, systematic errors that can apply to both measurement units can detect the same error in both measurement units, for example, with the same root cause. For example, each of the measurement units can comprise further elements for improving the accuracy or for calibrating the measurement unit.

[0012] For example, a filter for the measurement values can be connected in front of at least one sensing device of the measurement unit. In particular, a shared filter can also be provided for the corresponding sensing devices of the plurality of measurement units.

[0013] The measurement values can also depend on the temperature, for example. In order to improve the measurement accuracy, the measurement units can each comprise a temperature sensing circuit, in particular with a temperature sensor arranged inside the measurement unit, wherein the determined temperature is output to the evaluation circuit. The battery parameters are determined from the respectively sensed first measurement values, from the respectively sensed second measurement values and from the determined temperature. For example, the measurement section can comprise a resistive element along which the measurement unit senses a voltage drop. For example, the battery current can be determined from the sensed voltage drop and from the known resistance of the resistive element. Since the resistance of the resistive element can change depending on the temperature, the temperature has to be sensed in order to determine the exact resistance of the resistive element.

[0014] The at least one temperature sensing circuit can be connected to a temperature sensor arranged outside the measurement unit. This temperature sensing circuit can use the external temperature sensor to check the temperature sensing by the internal temperature sensor, so that the internal temperature sensor can be calibrated or a malfunction of the internal temperature sensor can be detected. For example, the external temperature sensor can be arranged on a shared circuit board of the battery sensor or completely outside the battery sensor.

[0015] In addition, at least one measurement unit can comprise a reference circuit for providing a reference signal. The reference signal has a known amplitude. It is also known which battery parameter is produced by the reference signal or which change of the battery parameter is produced by the reference signal. The associated measurement unit can be calibrated by the reference signal. Alternatively, the battery parameter of the associated measurement unit can additionally contain the reference signal. In the evaluation unit, the reference signal can be filtered out, for example, or the change of the battery parameter caused by the reference signal can be checked, whereby the battery parameters can also be compared with each other.

[0016] Preferably, the measurement units are arranged on a shared circuit board in order to make the battery sensor as compact as possible. In particular, the measurement units can be arranged on opposite sides of the circuit board in order to reduce the size of the circuit board.

[0017] The measuring units can also comprise a plurality of sensing devices, wherein the same battery parameter is sensed by each of the sensing devices.

[0018] The first sensing device can be a voltage sensing device for sensing a battery voltage, for example, wherein the first sensing device comprises a first contact for contacting a battery pole of the vehicle battery, in particular.

[0019] The second sensing device can be a current sensing device for sensing a battery current.

[0020] The current sensing device can comprise a measuring section, wherein the first measurement is sensed at a first contact at a first end of the measuring section and the second measurement is sensed at a second contact at a second end of the measuring section.

[0021] The measuring section comprises at least one measuring resistor with a defined resistance, for example, and the measurements are each a voltage. Thus, each of the measuring units in the battery sensor senses a voltage drop along the measuring section. Using the known resistance of the measuring resistor, the battery current flowing through the battery sensor can be determined from the respectively determined voltage drop. BRIEF DESCRIPTION OF DRAWINGS

[0022] Further advantages and features emerge from the following figures showing a schematic design of a battery sensor according to the application.

[0023] Figure 1 A battery sensor 10 for sensing a battery parameter of a vehicle battery 12 is shown, which is arranged in a circuit 14 in a motor vehicle. DETAILED DESCRIPTION

[0024] The battery sensor 10 comprises two measuring units 16, 18, which each comprise a plurality of sensing devices for sensing at least one battery parameter, wherein the two measuring units 16, 18 sense the same battery parameter. The first sensing devices of the measuring units are voltage sensing devices 20, 22 for sensing a battery voltage, respectively; the second sensing devices are current sensing devices 24, 26 for sensing a battery current, respectively. In addition, each of the measuring units 16, 18 comprises a temperature sensing device 28, 30.

[0025] The voltage sensing devices 20, 22 are connected to an input 34 of the battery sensor 10 by a shared filter 32. The input 34 is electrically connected to a battery pole 36, such that the voltage sensing devices 20, 22 receive and output the same measurement and an evaluation circuit 38, 40 determines a battery voltage of the vehicle battery 12 from this measurement.

[0026] The current sensing device 24, 26 comprises a shared measurement section 42 which is arranged in the load current path and is formed by a measurement resistor with a defined resistance. The measurement resistor can be formed by a plurality of resistance elements arranged in series and / or in parallel. A first measurement value is a voltage sensed at a first end of the measurement section; a second measurement value is a voltage sensed at a second end of the measurement section. In each evaluation circuit 38, 40, a voltage drop across the measurement section 42, i.e. across the measurement resistor, can be calculated from these voltages and can be used together with the known resistance of the measurement resistor for determining the current flowing through the measurement section, i.e. the battery current. The fact that both measurement units 16, 18 use a shared measurement section ensures that both measurement units receive the same measurement values 42 and thus (in case of correct operation of the measurement units 16, 18) necessarily output the same battery parameters. A shared filter 48 is also provided in front of the current sensing device 24, 26.

[0027] The temperature sensing circuit 28 of the first measurement unit 16 comprises an internal temperature sensor 50, a signal from which is likewise output to the evaluation circuit 38. The temperature signal can be used, for example, to correct or improve the measurement values from the current sensing device 20 or the voltage sensing device 24. Similarly, the temperature sensing circuit 30 of the second measurement unit 18 comprises an internal temperature sensor 52. In addition, the temperature sensing circuit 30 comprises a second external temperature sensor 54. This makes it possible, for example, to check the internal temperature sensor 52 or to sense further temperature data in order to improve the measurements made by the battery sensor 10.

[0028] A signal line 56 is provided between the evaluation circuit 38 and the evaluation circuit 40, through which the determined battery parameters can be output to the other evaluation circuit 38, 40, respectively. An evaluation unit 58 is additionally provided in the evaluation circuit 38 of the first measurement unit 16 which compares the battery parameters from the evaluation circuit 38 with the battery parameters from the evaluation circuit 40. Since these battery parameters each arise on the basis of the same measurement values, these battery parameters are necessarily identical or can only exhibit slight differences. If the difference between the corresponding battery parameters of the evaluation circuits 38, 40 is exceeded, an error signal is output to a higher-level controller 62, in particular via an output 60, in order to indicate a malfunction of the battery sensor 10.

[0029] Thus, the battery parameters determined by the two measuring units 16, 18 are checked within the battery sensor 10, wherein the battery parameters are each related to the same measurement value. Thus, the error sources can be reduced to the sensing devices 20, 22, 24, 26, 28, 30 and / or the evaluation circuits 38, 40. Since the sensing devices 20, 22, 24, 26, 28, 30 each use the same measurement value, the number of contacts to the circuit 14 or to the vehicle battery 12 can be reduced. Thus, the battery parameters are redundantly measured and the error check is performed within the battery sensor. Thus, the battery sensor is very reliable and has only a small overall size since the two measurement paths do not require separate contacts and / or measurement sections.

[0030] In addition, each of the measuring units 16, 18 comprises a diagnostic unit 64, 66 in order to perform a self-diagnosis. The diagnostic units 64, 66 can be used, for example, to test or calibrate the sensing devices 20, 22, 24, 26, 28, 30 during routine operation, in particular at regular intervals, and / or to test the sensing devices 20, 22, 24, 26, 28, 30 or the measuring units 16, 18 after an output error signal.

[0031] In the embodiment shown here, the measuring units 16, 18 have essentially the same construction, i.e. the corresponding sensing devices 20, 22, 24, 26, 28, 30 have the same construction or are based on the same measurement technology. However, it is possible that the measuring units use the same measurement values but use different evaluation methods in order to avoid systematic error sources. In particular, further elements, for example filters, temperature sensors or calibration devices, can be provided in the individual measuring units 16, 18 in order to be able to detect shared measurement errors in the measuring units 14, 18, for example caused by a shared root cause.

[0032] In the embodiment of the battery sensor 10 shown, a reference voltage source 68 is provided for the voltage sensing device 22, which can apply a defined voltage of a known amplitude to the voltage sensing device 22, for example in order to test or calibrate the device. In addition, an external temperature sensor 54 is provided at the temperature sensing circuit 30 in order to calibrate this circuit with a further temperature value or to be able to provide a further temperature value to the evaluation circuit 40. Further elements can be, for example, filters 32, 48 which filter the measurement values of only one of the two measuring units 16, 18.

[0033] In the embodiment shown here, the measuring units 16, 18 are arranged, in particular adjacently arranged, on a shared circuit board 70. Preferably, the measuring units 16, 18 are arranged on opposite sides of the circuit board 70 in order to be able to make the circuit board smaller.

[0034] Optionally, the evaluation unit 48 can also be arranged outside the measuring units 16, 18, in particular also outside the battery sensor 10.

Claims

1. A battery sensor (10) for sensing at least one battery parameter, the battery sensor having at least two measuring units (16, 18), wherein, The measuring units (16, 18) each comprise at least one sensing device (20, 22, 24, 26, 28, 30) for sensing at least one measured value, wherein the measuring units (16, 18) each comprise at least one evaluation circuit (38, 40) for determining at least one battery parameter from the at least one respectively sensed measured value, characterized in that at least one evaluation unit (58) is provided, which compares the battery parameters determined by the evaluation circuits (38, 40) and outputs an error signal in the event of an exceedance of a defined difference between the battery parameters, corresponding sensing devices (20, 22, 24, 26, 28, 30) of the measuring units (16, 18) sensing the same measured value, at least one pair of corresponding sensing devices (20, 22, 24, 26, 28, 30) of the measuring units (16, 18) having a shared measurement section and / or shared contacts, the at least one pair of corresponding sensing devices measuring the same measured value of the shared measurement section and / or of the shared contacts.

2. The battery sensor of claim 1, wherein, The evaluation unit (58) is integrated in the at least one evaluation circuit (38, 40), wherein the evaluation circuits (38, 40) are connected to one another by a signal line (56) via which the battery parameters are transmitted to the evaluation unit (58).

3. The battery sensor according to claim 1 or 2, characterized in that, The at least one measuring unit (16, 18) comprises at least one diagnostic unit (64, 66) for self-testing of the measuring unit (16, 18) and / or of the at least one sensing device (20, 22, 24, 26, 28, 30).

4. The battery sensor according to claim 1 or 2, characterized in that, A filter (32, 48) for the measured value is connected in front of the at least one sensing device (20, 22, 24, 26, 28, 30) of the measuring unit (16, 18).

5. The battery sensor according to claim 1 or 2, characterized in that, The at least one measuring unit (16, 18) comprises a temperature sensing circuit (28, 30) having a temperature sensor (50, 52) arranged inside the measuring unit (16, 18), wherein the determined temperature is output to the evaluation circuit (38, 40) respectively, wherein at least one battery parameter is determined from the at least one respectively sensed measured value and the determined temperature.

6. The battery sensor of claim 5, wherein, The at least one temperature sensing circuit (28, 30) is connected with a temperature sensor (54) arranged outside the measuring unit (16, 18).

7. The battery sensor of claim 1 or 2, wherein, The at least one measuring unit (16, 18) comprises a reference circuit (68) for providing a reference signal.

8. The battery sensor of claim 1 or 2, wherein, The measuring units (16, 18) are arranged on a shared circuit board (70), the measuring units (16, 18) being arranged on opposite sides of the circuit board (70).

9. The battery sensor of claim 1 or 2, wherein, The first sensing devices (20, 22) of the measuring units (16, 18) are respectively voltage sensing devices (20, 22) for sensing a battery voltage, wherein the first sensing devices (20, 22) comprise a first contact (34) for contacting a battery pole (36) of a vehicle battery (12).

10. The battery sensor of claim 9, wherein, The second sensing means (24, 26) of the measuring unit (16, 18) are accordingly current sensing means (24, 26) for sensing the battery current.

11. The battery sensor of claim 10, wherein, The current sensing means (24, 26) comprise a shared measurement section (42), wherein a first measurement value is sensed at a first contact at a first end (44) of the measurement section (42) and a second measurement value is sensed at a second contact at a second end (46) of the measurement section (42).

12. The battery sensor of claim 11, wherein, The measurement section (42) comprises at least one measurement resistor with a defined resistance, and the measurement values are voltages.

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