METHOD FOR INITIALIZING AND OPERATING A BATTERY MANAGEMENT SYSTEM

• US 20120262126A1
• Filed: 08/18/2010
• Published: 10/18/2012
• Est. Priority Date: 10/09/2009
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH, Samsung SDI Company Limited
• Original Assignee: SB Limotive Germany GmbH (Robert Bosch GmbH), SB LiMotive Co. Ltd (Samsung SDI Company Limited)
• Inventors: Boehm, Andre, Wickert, Stefan
• Granted Patent: US 9,643,508 B2
• Time in Patent Office: Days
• US Class Current: 320/162
• CPC Class Codes: B60L 58/12 responding to state of charge [SoC]
• CPC Class Codes: B60L 58/15 Preventing overcharging
• CPC Class Codes: G01R 31/3835 involving only voltage measurements
• CPC Class Codes: G01R 31/392 Determining battery ageing or deterioration, e.g. state of health
• CPC Class Codes: H01M 10/4257 Smart batteries, e.g. electronic circuits inside the housing of the cells or batteries
• CPC Class Codes: H01M 10/44 Methods for charging or discharging circuits for charging H02J7/00
• CPC Class Codes: H01M 10/48 Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte constructional details of current conducting connections for detecting conditions inside cells or batteries, e.g. details of voltage sensing terminals, H01M50/569
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

Abstract

A method for initializing and operating a battery management system is disclosed. The method comprises the following steps. First, start the battery management system. Next, read battery variables which are stored in a nonvolatile memory of the battery and comprise the last state of charge of the battery. Then measure the open-circuit voltage of the battery. Next, determine an instantaneous state of charge value on the basis of the measured open-circuit voltage. Then determine an estimated value of the state of charge of the battery as a function of both the stored last state of charge of the battery and the instantaneous state of charge value. Then initialize the state of charge in the battery management system using the determined estimated value of the state of charge. Finally, operate the battery management system with the initialized values.

Claims

1. A method for initializing and operating a battery management system, comprising the steps of:

starting the battery management system (S1);

reading battery variables which are stored in a nonvolatile memory of the battery and comprise the last state of charge (SOC_old) of the battery (S2);

measuring the open-circuit voltage of the battery (S3);

determining an instantaneous state of charge value (SOC_inst) on the basis of the measured open-circuit voltage (S4);

determining an estimated value of the state of charge (SOC_est) of the battery as a function of both the stored last state of charge (SOC_old) of the battery and the instantaneous state of charge value (SOC_inst) (S5);

initializing the state of charge in the battery management system using the determined estimated value of the state of charge (SOC_est) (S6); and

operating the battery management system with the initialized values (S7).

2. The method as claimed in claim 1, wherein a plausibility check of the state detection by the battery management system is also carried out, comprising the steps of:

comparing the instantaneous state of charge (SOC_inst) and the state of charge stored last (SOC_old) (S8);

switching off the battery if the difference between the instantaneous state of charge (SOC_inst) and the state of charge stored last (SOC_old) is above a predetermined threshold value (S9);

or

initializing the battery management system with the determined estimated value of the state of charge (SOC_est) if the difference between the instantaneous state of charge (SOC_inst) and the state of charge stored last (SOC_old) is below the predetermined threshold value (S6).

3. The method as claimed in claim 2, wherein, before the battery management system is switched off or before initialization, a further plausibility check of the values is also carried out by comparing the calculated state of charge (SOC_inst) dependent on the open-circuit voltage with a current integral.

4. The method as claimed in one of the preceding claims, wherein the instantaneous state of charge (SOC_inst) is determined using the measured open-circuit voltage and a family of characteristics dependent on the temperature/open-circuit voltage.

5. The method as claimed in one of the preceding claims, wherein the state of charge estimator (SOC_est) is determined by means of weighted averaging of the stored last state of charge (SOC_old) and the instantaneous state of charge (SOC_inst).

6. The method as claimed in claim 5, wherein the state of charge stored last (SOC_old) and the instantaneous state of charge (SOC_inst) are balanced during the weighted averaging operation.

7. The method as claimed in one of claims 1 to 4, wherein the weighting operation is carried out in the weighted averaging operation on the basis of the period of time between the last storage of the state of charge (SOC_old) and the determination of the instantaneous state of charge (SOC_inst).

8. The method as claimed in one of the preceding claims, wherein, during the initialization of the first measured value acquisition of the open-circuit voltage and current after the battery has been started, the battery variables stored last are directly used as initialization values of the corresponding battery variables.

9. The method as claimed in one of the preceding claims, wherein the determined battery characteristic variables comprising the state of charge of the battery are stored in the nonvolatile memory of the battery and/or battery variables such as voltage, temperature and model parameters of a mathematical ageing process are stored while switching off and/or operating the battery management system.

10. The method as claimed in one of the preceding claims, wherein the state of charge estimator (SOC_est) is also adapted over a plurality of measured value cycles during operation of the battery.

11. The method as claimed in claim 10, wherein the state of charge is adapted using the following input variables of an ageing model:

the measured voltage, the temperature, the integrated charging current and the state of charge value (SOC_old) during the last operation of switching off the battery, and

the standstill duration, the measured voltage, the temperature and the instantaneous state of charge (SOC_inst) when starting the system.