BATTERY SENSOR

Abstract

A battery sensor for sensing at least one battery parameter including at least two measuring units. The measuring units each include at least one sensing device for sensing at least one measured value and at least one evaluation circuit for determining at least one battery parameter from the respectively sensed at least one measured value. An evaluation unit is provided, which compares the battery parameters determined by the evaluation circuits and outputs an error signal in the event that a defined difference between the battery parameters is exceeded.

Claims

1. A battery sensor comprising: a first measuring unit, the first measuring unit comprising: a first sensor configured to sense a first measured value; and a first evaluation circuit configured to determine a first battery parameter of a battery from the first measured value; a second measuring unit, the second measuring unit comprising: a second sensor configured to sense a second measured value; and a second evaluation circuit configured to determine a second battery parameter of the battery from the second measured value; and an evaluation unit configured to compare the first battery parameter and the second battery parameter, and output an error signal based on a difference between the first battery parameter and the second battery parameter exceeding a threshold.

2. The battery sensor as claimed in claim 1, wherein the evaluation unit is integrated in the first evaluation circuit or the second evaluation circuit, and wherein the first evaluation circuit and the second evaluation circuit are connected to each other by a signal line, via which the battery parameters are transferred to the evaluation unit.

3. The battery sensor as claimed in claim 1, wherein the first measuring unit comprises a first diagnostics unit configured to perform a self-test of the first measuring unit and/or the first sensor, and wherein the second measuring unit comprises a second diagnostics unit configured to perform a self-test of the second measuring unit and/or the second sensor.

4. The battery sensor as claimed in claim 1, further comprising a filter connected in front of at least one of the first sensor and the second sensor.

5. The battery sensor as claimed in claim 1, wherein the first measuring unit comprises a first temperature-sensing circuit comprising a first temperature sensor configured to output a first temperature to the evaluation circuit, wherein the second measuring unit comprises a second temperature-sensing circuit comprising a second temperature sensor configured to output a second temperature to the evaluation circuit, wherein the first evaluation unit is configured to determine the first battery parameter from the first measured value and the determined first temperature, and wherein the second evaluation unit is configured to determine the second battery parameter from the second measured value and the second temperature.

6. The battery sensor as claimed in claim 5, wherein the first temperature-sensing circuit and the second temperature-sensing circuit are connected to a temperature sensor arranged external to the first measuring unit and the second measuring unit.

7. The battery sensor as claimed in claim 1, wherein the first measuring unit comprises a first reference circuit configured to output a first reference signal, and wherein the second measuring unit comprises a second reference circuit configured to output a second reference signal.

8. The battery sensor as claimed in claim 1, wherein the first measuring unit and the second measuring unit are arranged on opposing faces of a shared circuit board.

9. The battery sensor as claimed in claim 1, wherein the first sensor comprises a voltage-sensing device for sensing a battery voltage of the battery, and wherein the first sensor comprises a first contact for making contact with a battery pole of the battery.

10. The battery sensor as claimed in claim 9, wherein the second sensor comprises a current-sensing device for sensing a battery current of the battery.

11. The battery sensor as claimed in claim 10, wherein the current-sensing device comprises a measurement segment, and wherein a first measured value is sensed at a first contact at a first end of the measurement segment, and a second measured value is sensed at a second contact at a second end of the measurement segment.

12. The battery sensor as claimed in claim 11, wherein the measurement segment comprises at least one measurement resistor of defined electrical resistance, and wherein the first measured value and the second measured value are voltages.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Further advantages and features will be apparent when taken in conjunction with the following drawing:

[0024] FIG. 1 is a block diagram illustrating a schematic design of a battery sensor according to an embodiment.

DETAILED DESCRIPTION

[0025] FIG. 1 shows a battery sensor 10 for sensing battery parameters of a vehicle battery 12, which is arranged in a circuit 14 in a motor vehicle.

[0026] 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 both measuring units 16, 18 sense the same battery parameters. A first sensing device of the measuring units is a voltage-sensing device 20, 22 respectively for sensing the battery voltage; a second sensing device is a current-sensing device 24, 26 respectively for sensing the battery current. In addition, each measuring unit 16, 18 comprises a temperature-sensing device 28, 30.

[0027] The voltage-sensing devices 20, 22 are connected via a shared filter 32 to an input 34 of the battery sensor 10. The input 34 is electrically connected to a battery pole 36, so that the voltage-sensing devices 20, 22 receive and output the same measured value to an evaluation circuit 38, 40, which determines from this measured value the battery voltage of the vehicle battery 12.

[0028] The current-sensing devices 24, 26 comprise a shared measurement segment 42, which is arranged in the load current path and is formed by a measurement resistor having a defined electrical resistance. The measurement resistor can be formed by a plurality of resistive elements arranged in series and/or in parallel. The first measured value is a voltage sensed at a first end of the measurement segment; a second measured value is a voltage sensed at a second end of the measurement segment. In each evaluation circuit 38, 40, the voltage drop across the measurement segment 42, i.e. across the measurement resistor, can be calculated from these voltages, and can be used, together with the known electrical resistance of the measurement resistor, to determine the current flowing via the measurement segment, i.e. the battery current. The fact that both measuring units 16, 18 use a shared measurement segment ensures that they receive the same measured values 42, and thus, given correct operation of the measuring units 16, 18, must output the same battery parameters. A shared filter 48 is also provided in front of the current-sensing devices 24, 26.

[0029] The temperature-sensing circuit 28 of the first measuring unit 16 comprises an internal temperature sensor 50, the signal from which is likewise output to the evaluation circuit 38. The temperature signal can be used, for example, to correct or improve the measurements from the current-sensing device 20 or the voltage-sensing device 24. The temperature-sensing circuit 30 of the second measuring unit 18 similarly 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 additional temperature data, for instance in order to improve the measurement by the battery sensor 10.

[0030] A signal line 56 is provided between the evaluation circuits 38, 40, via 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 measuring unit 16. The evaluation unit 58 compares the battery parameters from the evaluation circuit 38 with the battery parameters from the evaluation circuit 40. Since these each arise on the same measured values, they should be identical or may exhibit only slight differences. If the difference between the corresponding battery parameters from the evaluation circuits 38, 40 exceeds, an error signal is output, in particular via the output 60, to a higher-level controller 62 in order to indicate a malfunction of the battery sensor 10.

[0031] The battery parameters determined by both measuring units 16, 18 are thus checked inside the battery sensor 10, wherein the battery parameters relate respectively to the same measured values. The error sources can thus 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 measured values, the number of contacts to the circuit 14 or to the vehicle battery 12 can be reduced. Hence a redundant measurement of the battery parameters is performed, and error-checking is carried out inside the battery sensor. The battery sensor is thus very reliable and has only a small overall size, because there is no need for separate contacts and/or measurement segments for both measurement paths.

[0032] In addition, each of the measuring units 16, 18 comprises a diagnostics unit 64, 66 in order to perform a self-diagnosis. The diagnostics units 64, 66 can be used, for example, for testing or calibrating the sensing devices 20, 22, 24, 26, 28, 30, in particular at regular intervals, during routine operation, and/or for testing the sensing devices 20, 22, 24, 26, 28, 30 or the entire measuring units 16, 18 after the output of an error signal.

[0033] In the embodiment shown here, the measuring units 16, 18 have substantially 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 technique. It is also possible, however, that these use the same measured values but different evaluation methods in order to avoid systemic error sources. In particular, additional elements, for instance 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 instance from a shared root cause.

[0034] In the embodiment shown of the battery sensor 10, a reference-voltage source 68 for the voltage-sensing devices 22 is provided, for example, which can apply a defined voltage of known magnitude to the voltage-sensing devices 22, for instance to test or calibrate said devices. In addition, an external temperature sensor 54 is provided at the temperature-sensing circuit 30 in order to calibrate this circuit or to be able to provide the evaluation circuit 40 with an additional temperature value. Further elements may be, for example, filters 32, 48, which filter only the measured values of one of the two measuring units 16, 18.

[0035] In the embodiment shown here, the measuring units 16, 18 are arranged, in particular adjacently, on a shared circuit board 70. The measuring units 16, 18 are preferably arranged on opposite sides of the circuit board 70 in order to be able to make the circuit board smaller.

[0036] Optionally, the evaluation unit 48 can also be arranged outside the measuring units 16, 18, in particular also outside the battery sensor 10.