Method for determining a fault state of a battery, a battery sensor and a vehicle onboard power supply system

• US 10,753,983 B2
• Filed: 02/20/2017
• Issued: 08/25/2020
• Est. Priority Date: 03/24/2016
• Status: Active Grant

• Current Assignee: Continental Automotive GmbH (Continental AG)
• Original Assignee: Continental Automotive GmbH (Continental AG)
• Inventors: Graf, Hans-Michael
• Primary Examiner(s): Nguyen, Vinh P
• Application Number:
  US16/068,209
• Publication Number:
  US 20190018068A1
• Time in Patent Office: 1,282 Days
• CPC Class Codes: B60R 16/033 characterised by the use of electrical cells or batteries for propulsion puposes B60K1/04; supplying batteries to, or removing batteries from, vehicles B60S5/06; testing of charge state G01R31/36
• CPC Class Codes: G01R 27/08 Measuring resistance by measuring both voltage and current
• CPC Class Codes: G01R 31/3648 comprising digital calculation means, e.g. for performing an algorithm
• CPC Class Codes: G01R 31/3842 combining voltage and current measurements
• CPC Class Codes: G01R 31/389 Measuring internal impedance, internal conductance or related variables

Abstract

A method for determining a fault state of a battery, which method is based on a calculation of a differential conductance. An associated battery sensor and to an associated onboard power supply system is also disclosed.

Claims

1. A method for determining a fault state of a battery or the connection points thereof to an onboard power supply system, the method comprising:

periodically measuring, by a battery sensor, voltage samples of a voltage change of the battery,

periodically measuring, by the battery sensor, current samples of a current change of the battery,

calculating, by a control apparatus, for each of the voltage samples and for each of the current samples, a differential conductance, and

ascertaining, by the control apparatus, the fault state when the differential conductance undershoots a conductance threshold value.

2. The method as claimed in claim 1,

wherein the fault state corresponds to a failure or a high-impedance state of the battery or the connection lines thereof.

3. The method as claimed in claim 2, wherein the method is carried out in a battery sensor, which is connected to the battery.

4. The method as claimed in claim 1,

wherein the method is carried out in a battery sensor, which is connected to the battery.

5. The method as claimed in claim 1,

wherein the voltage change and the current change, are measured over an identical period of time.

6. The method as claimed in claim 1,

wherein the voltage change is calculated as the difference between a second voltage value and a first voltage value measured temporally before said second voltage value;

and/or

wherein the current change is calculated as the difference between a second current value and a first current value measured temporally before said second current value.

7. The method as claimed in claim 1,

wherein the current change and/or the voltage change are measured at a frequency between 50 Hz and 20 kHz.

8. The method as claimed in claim 1,

wherein the differential conductance is calculated by division of the current change by the voltage change.

9. The method as claimed in claim 1,

wherein the differential conductance is calculated by means of a least-squares analysis over a plurality of current changes and/or voltage changes.

10. The method as claimed in claim 1,

wherein a disabling of an internal combustion engine is deactivated in response to the ascertainment of the fault state.

11. The method as claimed in claim 1,

wherein the differential conductance is calculated only when the voltage change is above a voltage change threshold value.

12. The method as claimed in claim 1,

wherein a differential resistance is calculated based on the current change and the voltage change when the current change is above a current change threshold value, and

wherein the fault state is ascertained when the differential resistance exceeds a resistance threshold value.

13. The method as claimed in claim 12,

wherein a final differential resistance is calculated by addition of the differential resistance and the inverse of the differential conductance and division of the result by the number 2.

14. The method as claimed in claim 12,

wherein a final differential conductance is calculated by addition of the differential conductance and the inverse of the differential resistance and division of the result by the number 2.

15. A battery sensor, which is designed to be connected to a battery and also to a vehicle chassis, and which is configured to carry out a method as claimed in claim 1.

16. A vehicle onboard power supply system, comprising:

a battery,

a battery sensor as claimed in claim 15 connected to the battery, and

a generator, which is driven by an internal combustion engine,

wherein the battery, the battery sensor and the generator have a common positive line and also have a common ground.

17. The method as claimed in claim 1, wherein the current change and/or the voltage change are measured at a frequency between 200 Hz and 8 kHz.

18. The method as claimed in claim 1, wherein the current change and/or the voltage change are measured at a frequency of about 1 kHz.