BATTERY MANAGEMENT SYSTEM AND DRIVING METHOD THEREOF

• US 20080054850A1
• Filed: 07/17/2007
• Published: 03/06/2008
• Est. Priority Date: 09/05/2006
• Status: Active Grant

• Current Assignee: Samsung SDI Company Limited
• Original Assignee: Samsung SDI Company Limited
• Inventors: Choi, Soo-Seok, Park, Ho-Young, Lee, Young-Jo, Kim, Beom-Gyu, Seo, Se-Wook, Lim, Gye-Jong, Yun, Han-Seok, Tae, Yong-Jun
• Granted Patent: US 7,902,829 B2
• Time in Patent Office: Days
• US Class Current: 320/136
• CPC Class Codes: B60K 6/48 Parallel type
• CPC Class Codes: B60L 2240/547 Voltage
• CPC Class Codes: B60L 2240/549 Current
• CPC Class Codes: B60L 58/15 Preventing overcharging
• CPC Class Codes: B60W 10/26 for electrical energy, e.g. batteries or capacitors
• CPC Class Codes: B60W 20/00 Control systems specially adapted for hybrid vehicles hybrid vehicle design, B60K6/00; electric vehicles B60L
• CPC Class Codes: B60W 20/13 in order to stay within battery power input or output limits; in order to prevent overcharging or battery depletion
• 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 31/396 Acquisition or processing of data for testing or for monitoring individual cells or groups of cells within a battery
• CPC Class Codes: Y02T 10/62 Hybrid vehicles
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

Abstract

A battery management system for managing a battery including a plurality of battery cells and a driving method are provided. The system includes a sensor, and a main control unit (MCU). The sensor senses a voltage and a current of the battery. The MCU receives the voltage and the current of the battery, measures an open circuit voltage (OCV) in key-on using the battery voltage, and estimates an initial SOC depending on the OCV in the key-on. The MCU divides the OCV into first and second OCV regions, and, when the OCV in the key-on is in the first OCV region, estimates the initial SOC using a linear equation.

Claims

1. A battery management system comprising a plurality of battery cells, the system comprising:

a voltage and current sensor for the battery that generates voltage and current signals concerning the battery; and

a main controller that receives the voltage and current signals from the sensor and is configured to;

(a) measure a key-on open circuit voltage (OCV) using the battery voltage signal, (b) determine whether the key-on OCV belongs to a first OCV region, and (c) estimate an initial state of charge (SOC) of the battery using a linear equation when the key-on OCV belongs to the first OCV region.

2. The system of claim 1, wherein the main controller is further configured to calculate the key-off time period, the key-off time period being an amount of time that the battery has been in a key-off state from a key-off time point to a time point at which the present key-on state begins, and to compare the key-off time with a reference time.

3. The system of claim 2, wherein when the key-off time is longer than the reference time the main controller determines whether the key-on OCV belongs to the first OCV region.

4. The system of claim 3, wherein the linear equation is obtained experimentally.

5. The system of claim 3, wherein the main controller estimates the initial SOC using a table of OCV and SOC when the key-on OCV belongs to a second OCV region.

6. The system of claim 2, wherein when the key-off time is shorter than the reference time the main controller estimates the initial SOC of the battery to be substantially identical to a key-off SOC.

7. The system of claim 2, wherein the reference time comprises a time taken for the OCV in the key-on to reach a stabilization state.

8. The system of claim 1, wherein the sensor is further configured to sense temperature and terminal voltage of the battery.

9. The system of claim 1, wherein the main controller comprises:

a timer;

a controller; and

a storage unit.

10. The system of claim 9, wherein the timer is configured to measure key-on time and key-off time and to transmit the measured key-on and key-off times to the storage unit.

11. The system of claim 9, wherein the controller receives the voltage and the current of the battery from the sensor, measures the key-on OCV, controls the timer and the storage unit, and estimates the initial SOC.

12. A method of estimating an initial state of charge (SOC) of a battery, comprising:

(a) sensing voltage and current from the battery to obtain voltage and current signals;

(b) measuring a key-on open circuit voltage (OCV) using the voltage signal;

(c) determining whether the key-on OCV belongs to a first OCV region; and

(d) estimating the initial SOC using a linear equation when the key-on OCV belongs to the first OCV region.

13. The method of claim 12, wherein step (c) comprises:

comparing a key-off time of the battery with a reference time; and

determining the key-on OCV to be in the first OCV region when the key-off time is longer than the reference time.

14. The method of claim 13, wherein when the key-off time is longer than the reference time, the key-on OCV is in a second region, and the initial SOC is estimated using a table of OCV and SOC.

15. The method of claim 13, wherein when the key-off time is shorter than the reference time the initial SOC is estimated to be substantially identical to a key-off SOC.

16. The method of claim 13, wherein the reference time comprises a time taken for the OCV in the key-on to reach a stabilization state.