Method of estimating state of charge for battery and battery management system using the same

• US 20070090803A1
• Filed: 10/19/2006
• Published: 04/26/2007
• Est. Priority Date: 10/20/2005
• Status: Active Grant

• Current Assignee: Samsung SDI Company Limited
• Original Assignee: Samsung SDI Company Limited
• Inventors: Seo, Se-Wook, Lim, Gye-Jong, Yun, Han-Seok
• Granted Patent: US 7,928,736 B2
• Time in Patent Office: Days
• US Class Current: 320/128
• CPC Class Codes: B60L 2240/545 Temperature
• CPC Class Codes: B60L 2240/547 Voltage
• CPC Class Codes: B60L 2240/549 Current
• CPC Class Codes: B60L 3/0046 relating to electric energy storage systems, e.g. batteries or capacitors
• CPC Class Codes: B60L 58/14 Preventing excessive discharging
• CPC Class Codes: B60L 58/15 Preventing overcharging
• CPC Class Codes: B60L 58/16 responding to battery ageing, e.g. to the number of charging cycles or the state of health [SoH]
• CPC Class Codes: B60L 58/22 Balancing the charge of battery modules
• CPC Class Codes: B60L 58/26 by cooling
• CPC Class Codes: G01R 31/367 Software therefor, e.g. for battery testing using modelling or look-up tables
• CPC Class Codes: G01R 31/3828 using current integration
• CPC Class Codes: G01R 31/392 Determining battery ageing or deterioration, e.g. state of health
• CPC Class Codes: G01R 31/396 Acquisition or processing of data for testing or for monitoring individual cells or groups of cells within a battery
• CPC Class Codes: H02J 7/0048 Detection of remaining charge capacity or state of charge [SOC]
• CPC Class Codes: H02J 7/005 Detection of state of health [SOH]
• 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

The battery management system (BMS) measures a state of charge (SOC) of a battery by using a total amount of charge corresponding to a total amount of discharge accumulation. The BMS, outputting a SOC of a battery to an engine control unit (ECU), includes a sensor, state of health (SOH) and SOC measurers, a total amount of charge (TAC) determiner, and an output unit. The sensor detects a pack current and a pack voltage of the battery. The SOH measurer outputs a SOH of the battery by using the pack current and voltage. The SOC measurer measures a SOC of the battery by using the pack current and a TAC of the battery. The TAC determiner accumulates a total amount of discharge accumulation by using the pack current, determines a TAC corresponding to the total amount of discharge accumulation, and delivers the determined TAC to the SOC measurer. The output unit outputs the SOC and SOH to the ECU.

Claims

1. A battery management system, comprising:

a sensor for detecting a pack current and a pack voltage of a battery;

a state of health measurer coupled to the sensor to receive the pack current and the pack voltage, and measuring a state of health of the battery from both of the pack current and the pack voltage;

a state of charge measurer coupled to the sensor to receive the pack current;

a total amount of charge determiner coupled to the state of charge measurer, determining a total amount of charge, and delivering the information of the total amount of charge to the state of charge measurer, the state of charge measurer measuring a state of charge from both of the pack current and the total amount of charge of the battery; and

an output unit coupled to both of the state of health measurer and the state of charge measurer, and receiving the state of health and the state of charge.

2. The battery management system of claim 1, comprised of the total amount of charge determiner comprising:

a total amount of discharge accumulator for determining a total amount of discharge accumulation; and

a look-up table including a relationship between the total amount of charge and the total amount of discharge accumulation, the total amount of charge determiner looking up the look-up table to determine the total amount of charge from both of the total amount of discharge accumulation and the relationship of the look-up table.

3. The battery management system of claim 2, comprised of the total amount of charge determiner delivering the information of the total amount of charge to the state of charge measurer either periodically with a predetermined time interval or each time when the total amount of discharge accumulation is changed by a predetermined value.

4. The battery management system of claim 2, comprised of the total amount of discharge accumulator determining the total amount of discharge accumulation from both of a discharge time period and a discharge pack current.

5. The battery management system of claim 2, comprised of the relationship of the look-up table including a plurality of sub-relationships between the total amount of charge and the total amount of discharge accumulation at predetermined temperatures.

6. The battery management system of claim 1, wherein the state of charge measurer measures the state of charge by using a formula of

7. The battery management system of claim 1, comprised of the output unit outputting the state of health and the state of charge to an engine control unit of a vehicle that uses electrical energy.

8. A method for measuring a state of charge of a battery employed to a battery management system, the method comprising:

measuring a pack voltage and a pack current of the battery;

obtaining a total amount of discharge accumulation of the battery from the measured pack current;

determining a total amount of charge from the obtained total amount of discharge accumulation;

measuring a state of charge of the battery from both of the total amount of charge and the pack current.

9. The method of claim 8, comprised of the step of measuring the state of charge of the battery including a step of obtaining the state of charge by the use of a formula of

10. The method of claim 8, comprised of the step of determining the total amount of charge including a step of looking up a look-up table that includes a relationship between the total amount of charge and the total amount of discharge accumulation.

11. The method of claim 8, comprised of the step of obtaining the total amount of discharge accumulation including a step of integrating the pack current over time during a discharge time period.

12. A recording medium used in a battery management system for measuring a state of charge of a battery, the recording medium comprising:

a measurement function for measuring a pack voltage and a pack current of the battery;

a calculation function for calculating a total amount of discharge accumulation from the measured pack current;

a determination function for determining a total amount of charge of the battery from the total amount of discharge accumulation; and

a calculation function for calculating a state of charge of the battery from both of the total amount of charge and the pack current.

13. The recording medium of claim 12, further comprising a look-up table including a relationship between the total amount of charge and the total amount of discharge accumulation.

14. The recording medium of claim 13, comprised of the determination function for determining the total amount of charge of the battery determining the total amount of charge by looking up the relation of the look-up table.

15. The recording medium of claim 12, comprised of the calculation function for calculating the total amount of discharge accumulation including an integration function integrating the pack current over time during a discharge time period.

16. The recording medium of claim 12, comprised of the calculation function for calculating the state of charge of the battery including a formula of