Device and method for detecting a missing electrical connection of an energy store to an energy-supply system, particularly an electrical system of a motor vehicle

1. A method for detecting a missing electrical connection of an energy store to an energy-supply system, the energy-supply system being an electrical system of a motor vehicle, the method comprising:

sensing, by at least one current-sensing device, at least one electrical current flowing in the energy-supply system or energy store;

determining at least one dispersion of the current, wherein the dispersion is a measure of a magnitude and/or frequency of a deviation of sensed values of the current from a mean value of the current;

comparing the determined dispersion to at least one threshold value; and

detecting a missing electrical connection of the energy store to the energy-supply system in response to the comparison indicating that the determined dispersion is below the threshold.

2. The method as recited in claim 1 , wherein the threshold value: (i) is a function of a dispersion of the current-sensing device, and/or (ii) lies in the range of 1 mA to 500 mA.

3. The method as recited in claim 1 , further comprising:

determining a mean value of the current; and

comparing the mean value of the current to a second threshold value;

wherein the determining the detection of the missing electrical connection of the energy store to the energy-supply system is further based on the comparison of the mean value indicating that the mean value is below the second threshold value.

4. The method as recited in claim 1 , wherein a missing electrical connection between the energy store and the energy-supply system is inferred only if the missing electrical connection is recognized for a certain period of time on the order of 100 ms to 120s.

5. The method as recited in claim 1 , wherein a state in which a missing electrical connection between the energy store and the energy-supply system is inferred, is terminated if a missing electrical connection between the energy store and the energy-supply system is no longer inferred within a predetermined period of time.

6. The method as recited in claim 1 , wherein an idle state of (i) the energy-supply system, and/or (ii) the motor vehicle, is taken into account to further check a plausibility of a missing electrical connection between the energy store and the energy-supply system.

7. The method as recited in claim 1 , wherein the energy-supply system is excited in such a way that the current is changed by a value which is greater than the threshold value for the dispersion.

8. The method as recited in claim 7 , wherein the excitation of the energy-supply system is carried out when a previously ascertained dispersion is less than the threshold value for the dispersion.

9. The method as recited in claim 1 , further comprising:

sensing at least one voltage in the energy-supply system;

determining a dispersion of the voltage based on the sensed voltage;

comparing the dispersion voltage to a threshold value; and

determining a plausibility of a missing electrical connection of the energy store and the energy-supply system, based on the comparison.

10. The method as recited in claim 1 , wherein the dispersion is a measure of a magnitude of the deviation of the sensed values of the current from the mean value of the current.

11. The method as recited in claim 1 , wherein the dispersion is determined as a variance of the current.

12. The method as recited in claim 1 , wherein the dispersion is determined as a standard deviation of the current.

13. The method as recited in claim 1 , wherein the dispersion is determined as a noise level of the current.

14. The method as recited in claim 1 , wherein the dispersion is determined as a ripple of the current.

15. A device for detecting a missing electrical connection of an energy store to an energy-supply system, the electrical-supply system being an electrical system of a motor vehicle, the device comprising:

at least one current-sensing device configured to sense at least one electrical current flowing in the energy-supply system or the energy store; and

at least one processing unit configured to (i) determine a dispersion of the current, the dispersion being determined is a measure of a magnitude and/or frequency of a deviation of sensed values of the current from a mean value of the current, (ii) to compare the determined dispersion of the current to at least one threshold value, and (iii) to detect a missing electrical connection of the energy store to the energy-supply system in response to the comparison indicating that the determined dispersion is below the threshold.

16. The device as recited in claim 15 , wherein the device is configured to determine a mean value of the current, and compare the mean value of the current to a second threshold value, wherein the detection of the missing electrical connection of the energy store to the energy-supply system is further based on the comparison of the mean value indicating that the mean value is below the second threshold value.