Method and device for determining an open-circuit voltage profile of a vehicle battery, dependent on a state of charge

• US 10,191,115 B2
• Filed: 09/25/2014
• Issued: 01/29/2019
• Est. Priority Date: 10/14/2013
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Rueger, Michael, Boehm, Andre
• Primary Examiner(s): Miller, Daniel
• Application Number:
  US15/028,882
• Publication Number:
  US 20160259008A1
• Time in Patent Office: 1,587 Days
• CPC Class Codes: B60L 58/12 responding to state of charge [SoC]
• CPC Class Codes: G01R 31/367 Software therefor, e.g. for battery testing using modelling or look-up tables
• CPC Class Codes: G01R 31/3835 involving only voltage measurements
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

Abstract

The present invention relates to a method and to a battery management system which are suitable for determining an open-circuit voltage profile (3) of a vehicle battery, dependent on a state of charge, in a vehicle. In this context, the following occur: complete discharging (S1) of the vehicle battery by vehicle-internal loads of the vehicle, sensing (S2) of a first sensed, state-of-charge-dependent voltage profile (1) during the discharging (S1) of the vehicle battery, complete charging (S3) of the vehicle battery by a charging device, sensing (S4) of a second sensed state-of-charge-dependent voltage profile (2) during the charging (S3) of the vehicle battery, and determination (S5) of the state-of-charge-dependent open-circuit voltage profile (3) by means of a weighted interpolation of the first sensed voltage profile (1) and of the second sensed voltage profile (2).

Claims

1. A method for determining an open-circuit voltage profile of a vehicle battery, dependent on a state of charge, in a vehicle, the method comprising:

completely discharging the vehicle battery by vehicle-internal loads of the vehicle,

sensing a first sensed, state-of-charge-dependent voltage profile during the discharging of the vehicle battery,

completely charging of the vehicle battery by a charging device,

sensing a second sensed, state-of-charge-dependent voltage profile during the charging of the vehicle battery and

determining the state-of-charge-dependent open-circuit voltage profile by means of a weighted interpolation of the first sensed voltage profile and the second sensed voltage profile.

2. The method according to claim 1, wherein a first decision parameter is queried in an introductory procedural step and a decision ensues on the basis of a comparison of the first decision parameter to a given threshold value as to whether the method is continued, wherein the first decision parameter is a parameter selected from the group consisting of a parameter that describes a period of time, a parameter that described the mileage on the vehicle, a parameter that describes a charging throughput of the vehicle battery, a parameter that describes an energy throughput of the vehicle battery.

3. The method according to claim 1, wherein a query of a connection status takes place, which describes the availability of a charging voltage for charging the vehicle battery, prior to the procedural step of completely discharging the vehicle battery, and the method is only continued if a charging voltage is available.

4. The method according to claim 1, wherein a query of a second decision parameter takes place prior to the procedural step of completely discharging the vehicle battery.

5. The method according to claim 1, wherein a query of a delay time takes place prior to the procedural step of completely discharging the vehicle battery, and wherein the method, in a step following the query of the delay time, is delayed for the duration of the defined delay time in the event of the delay time not being equal to zero.

6. The method according to claim 1, wherein a query of an execution time period takes place prior to the procedural step of completely discharging the vehicle battery, and wherein a battery current which flows during the discharging of the vehicle battery and/or the charging of the vehicle battery is selected in such a way that the method is completed in the predefined execution time period.

7. The method according to claim 1, wherein a pre-charging of the vehicle battery, in which said vehicle battery is completely charged, occurs prior to the procedural step of completely discharging the vehicle battery, wherein:

a sensing of a third sensed, state-of-charge-dependent voltage profile occurs during the pre-charging of the vehicle battery, and

the determination of the state-of-charge-dependent open-circuit voltage profile takes place by means of a weighted interpolation of the first sensed, state-of-charge-dependent voltage profile, of the second sensed, state-of-charge-dependent voltage profile and of the third sensed, state-of-charge-dependent voltage profile.

8. The method according to claim 1, wherein a temperature of the vehicle battery is maintained above a temperature threshold value during the charging and the discharging of the vehicle battery, and in that the temperature is maintained at a constant value above the temperature threshold value.

9. The method according to claim 1, wherein the method furthermore comprises a calculation step, in which a calculation of a resulting state-of-charge-dependent open-circuit voltage profile takes place by means of a weighted interpolation of the state-of-charge-dependent open-circuit voltage profile with a state-of-charge-dependent open-circuit voltage profile determined at an earlier point in time.

10. A battery management system, suitable for determining a state-of-charge-dependent open-circuit voltage profile of a vehicle battery in a vehicle, comprising:

a discharging unit which is designed to completely discharge a vehicle battery by vehicle-internal consumers of the vehicle,

a charging unit which is designed to completely charge the vehicle battery by means of a charging device,

a sensing unit which is designed to sense a first sensed, state-of-charge-dependent voltage profile during the discharging of the vehicle battery and a second sensed, state-of-charge-dependent voltage profile during the charging of the vehicle battery, and

a determination unit which is designed to determine the state-of-charge-dependent open-circuit voltage profile by means of a weighted interpolation of the first sensed voltage profile and of the second sensed voltage profile.