BATTERY MANAGEMENT SYSTEM AND DRIVING METHOD THEREOF

• US 20080036421A1
• Filed: 06/22/2007
• Published: 02/14/2008
• Est. Priority Date: 08/11/2006
• Status: Active Grant

• Current Assignee: Samsung SDI Company Limited
• Original Assignee: Samsung SDI Company Limited
• Inventors: SEO, Se-Wook, Choi, Soo-Seok, Park, Ho-Young, Lee, Young-Jo, Kim, Beom-Gyu, Lim, Gye-Jong, Yun, Han-Seok, Tae, Yong-Jun
• Granted Patent: US 8,669,741 B2
• Time in Patent Office: Days
• US Class Current: 320/132
• CPC Class Codes: B60K 2001/005 the electric storage means
• CPC Class Codes: B60K 6/28 characterised by the electric energy storing means, e.g. batteries or capacitors
• CPC Class Codes: B60L 58/15 Preventing overcharging
• CPC Class Codes: B60L 58/24 for controlling the temperature of batteries
• CPC Class Codes: B60L 58/26 by cooling
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 10/08 including control of electric propulsion units, e.g. motors or generators
• 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 2510/24 Energy storage means
• CPC Class Codes: B60W 2510/244 Charge state
• CPC Class Codes: B60W 2510/246 Temperature
• 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 (BMS) manages a battery for a hybrid vehicle including an engine control unit and a motor generator controlled by the engine control unit and connected to a battery including at least one battery pack, each pack including a plurality of battery cells. The BMS includes a sensor and an MCU unit. The sensor detects temperature, current, and open circuit voltage (OCV) of the battery. The MCU receives the detected temperature, current, and OCV, calculates a key-off time period which is a period between a time point when a battery key-on state ends and a time point when a subsequent battery key-on state begins, calculates an OCV error range corresponding to an SOC error range detected at the key-off time point, and infers an initial SOC of the battery.

Claims

1. A battery management system (BMS) for a hybrid vehicle that includes an engine control unit, a motor generator controlled by the engine control unit, and a battery in which a plurality of battery cells are grouped into a plurality of battery packs, comprising:

a sensor that senses temperature, current, and open circuit voltage (OCV) of the battery at a present key-on time point; and

a main control unit (MCU) that calculates a 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, that calculates a difference between temperatures of the battery respectively detected at the key-on time point and the key-off time point by receiving data of the temperature of the battery, that detects an OCV error range corresponding to an SOC error range at the key-off time point, and that infers an initial SOC of the battery by using the OCV and the OCV error range.

2. The BMS of claim 1, wherein the MCU takes the SOC detected at the key-off time point as the initial SOC when the key-off time period is shorter than a reference time period.

3. The BMS of claim of claim 2, wherein, if the key-off time period is longer than the reference time period,

the MCU receives the temperatures and the OCVs of the battery respectively detected at the key-on time point and the key-off time point, detects the OCV error range corresponding to an SOC error range at the key-off time point, and infers the initial SOC using a table that relates SOCs to OCVs based on temperature if the OCV detected at the key-on time point is a voltage that is not within the OCV error range corresponding to the SOC error range detected at the key-off time point.

4. The BMS of claim 3, wherein the MCU takes the SOC detected at the key-off time point as the initial SOC of the battery when the OCV detected at the key-on time point is a voltage within the OCV error range corresponding to the SOC error range detected at the key-off time point and when a difference between temperatures of the battery at the key-on time point and the key-off time point is less than a reference temperature value.

5. The BMS of claim 4, wherein the MCU assumes an initial SOC using a table that relates SOCs to OCVs based on temperature when the OCV at the key-on time point is a voltage within the OCV error range corresponding to the SOC error range detected at the key-off time point and when the difference between temperatures detected at the key-on time point and key-off time point is greater than the reference temperature value.

6. The BMS according to claim 1, wherein the reference time period is a predetermined time period representing an amount of time that elapses after a key-on time point while the OCV becomes stabilized.

7. The BMS of claim 4, wherein the reference temperature value is a predetermined temperature value that is determined based on a temperature history of temperature differences of the battery detected at a key-on time point and a key-off time point.

8. A hybrid vehicle comprising

an engine control unit;

a motor generator controlled by the engine control unit, and

a battery connected to the motor generator and comprising a plurality of battery cells grouped into a plurality of battery packs; and

the battery management system of claim 1.

18. The driving method of claim of claim 8, wherein the reference time period is a time period that elapses while the OCV at the key-on time point is stabilized.

19. The driving method of claim 8, wherein the reference temperature value is a predetermined temperature value that is determined based on a temperature history of temperature differences of the battery detected at the key-on time point and a key-off time point.

9. A method of determining an initial state of charge (SOC) of a battery of a hybrid vehicle at a key-on time point following a key-off time period, the key-off time period beginning with a key-off time point and ending with the key-on time point, the method comprising:

comparing the key-off time period with a reference time period, wherein if the key-off time period is less than the reference time period, the initial SOC is determined to be the SOC at the key-off time point, and

if the key-off time period is not less than the reference time period, determining whether an open circuit voltage (OCV) detected at the key-on time point is a voltage within an OCV error range corresponding to an SOC error range detected at the key-off time point, wherein, if the OCV detected at the key-on time point is not a voltage within an OCV error range corresponding to an SOC error range detected at the key-off time point, the initial SOC is determined according to the OCV and temperature of the battery at the key-on time point from a table that relates SOCs to OCVs based on temperature, and

if the OCV detected at the key-on time point is a voltage within the OCV error range corresponding to an SOC error range detected at the key-off time point, determining whether an absolute value of a difference between temperatures of the battery detected at the key-on time point and the key-off time point is greater than a reference temperature value, wherein if the difference between temperatures detected at the key-on time point and the key-off time point is greater than the reference temperature, the initial SOC is determined according to the OCV and temperature at the key-on time point from a table that relates SOCs to OCVs based on temperature and wherein, if the difference between temperatures detected at the key-on time point and the key-off time point is not greater than the reference temperature, the initial SOC is determined to be the SOC at the key-off time point.

10. The method of claim 9, wherein the reference time period is a predetermined time period representing an amount of time that elapses after a key-on time point while the OCV becomes stabilized.

11. The method of claim 9, wherein, if the key-off time period is not less than the reference time period, a main control unit (MCU) of a battery management system (BMS) of the battery receives the temperature of the battery detected at the key-on time point and the key-off time point, respectively, and the OCV error range at the key-on time point, and detects the OCV error range corresponding to the SOC error range at the key-off time point.

12. A driving method of a battery management system (BMS) for a hybrid vehicle including an engine control unit and a motor generator controlled by the engine control unit and connected to a battery including a plurality of battery cells grouped into a plurality of battery packs, comprising:

comparing a key-off time period with a reference time period;

determining whether an open circuit voltage (OCV) detected at the key-on time point is a voltage within an OCV error range corresponding to an SOC error range detected at the key-off time point;

comparing a difference between temperatures of the battery detected at the key-on time point and the key-off time point with a reference temperature value; and

determining an initial state of charge (SOC) as the result of the comparing of the key-off time period with the reference time period, determining whether the OCV detected at the key-on time point is a voltage within the OCV error range corresponding to an SOC error range detected at the key-off time point and comparing a difference between temperatures detected at the key-on time point and the key-off time point with the reference temperature value.

13. The driving method of claim 12, wherein the initial SOC is determined to be the SOC detected at the key-off time point when the Ken-off time period is shorter than the reference time period.

14. The driving method of claim 12, wherein the a main control unit (MCU of the BMS receives temperatures of the battery detected at the key-on time point and a key-off time point, respectively, and the OCV error range at the key-on time point, and detects the OCV error range corresponding to the SOC error range at a key-off time point if the key-off time period is longer than the reference time period.

15. The driving method of claim 12, wherein the determining of whether the OCV detected at the key-on time point is a voltage within the OCV error range corresponding to the SOC error range detected at the key-off time point includes inferring the initial SOC using a table based on SOC and OCV for temperature if the OCV at the key-on time point is a voltage that is not within the OCV error range corresponding to the SOC error range of the key-off time point.

16. The driving method of claim 12, wherein the SOC at the key-off time point is determined to be the initial SOC of the battery when the OCV at the key-on time point is a voltage within the OCV error range corresponding to the SOC error range detected at the key-off time point, and when a difference between temperatures detected at the key-on time point and the key-off time point is less than a reference temperature value.

17. The driving method of claim 12, wherein the determining of the initial SOC comprises inferring the initial SOC using a table based on SOC and OCV for temperature when an OCV at the key-on time point is a voltage within the OCV error range corresponding to an SOC error range detected at a key-off time point and a difference between temperatures detected at the key-on time point and the key-off time point is greater than the reference temperature.