Battery management unit, system and method

• US 20040164706A1
• Filed: 04/19/2004
• Published: 08/26/2004
• Est. Priority Date: 03/30/2001
• Status: Active Grant

• Current Assignee: Wonderland Investment Group Inc
• Original Assignee: DesignLine International Holdings, LLC (Designline International Holding LLC /Private Group/)
• Inventors: Osborne, Jeffrey Roger
• Granted Patent: US 7,400,113 B2
• Time in Patent Office: Days
• US Class Current: 320/116
• CPC Class Codes: H02J 7/0018 using separate charge circuits
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

Abstract

A battery management unit and system for managing the state of charge of cells or batteries (B1-B10). Each battery management unit (1) measures cell or battery terminal voltage and provides this information to a central controller (3) via a communication medium (2). Each battery management unit (1) monitors a plurality of batteries (B1-B10) and can selectively charge a selected battery (B1-B10) via a charger (7) and switch circuit (8, 17) or can selectively discharge a selected battery (B1-B10) via a load (10) and switch circuit (8, 17) under the control of a controller (6). The controller (6) may control charging and discharging in accordance with measurements from voltage sensors (15a-j) or may convey information from a voltage sensors (15a-15j) to the central controller (3) and receive charging and discharging commands from the central controller (3). Charging and discharging is controlled to maintain all batteries within a desired state of charge ranged. The central controller (3) may selectively connect a main charger (20) or generator (21) to a bank of batteries associated with a battery management unit (1).

Claims

1. A battery management unit for managing the state of charge of a plurality of cells or batteries connected thereto including:

a state of charge sensor for measuring the state of charge of the cells or batteries;

a multiplexer for selectively connecting the state of the charge sensor to a cell or battery to be measured;

a charger for charging a cell or battery;

a discharger for discharging a cell or battery;

a controller which selectively connects the state of the charge sensor to a cell to be measured via the multiplexer, receives state of charge information from the state of charge sensor and selectively connects the charger or the discharger to a cell or battery to dynamically maintain the state of charge of the cells or batteries within a predetermined range.

2. A battery management unit as claimed in claim 1 wherein the state of charge sensor measures the voltage of each cell or battery to determine the state of charge of each cell or battery.

3. A battery management unit as claimed in claim 2 wherein a voltage sensor measures the voltage of each cell or battery and the outputs of the voltage sensors are multiplexed to the controller.

4. A battery management unit as claimed in any preceding claim including a temperature sensor for measuring the temperature of the cells or batteries and providing temperature information to the controller.

5. A battery management unit as claimed in any one of the preceding claims wherein the controller charges and discharges selected cells or batteries so as to maintain the state of charge of the cells or batteries within a desired range.

6. A battery management unit as claimed in claim 5 wherein the cell or battery having the lowest terminal voltage, below a predetermined low voltage threshold, is connected to the charger for a predetermined period until all cells have a terminal voltage above the low voltage threshold.

9. A battery management unit as claimed in any preceding claim wherein the controller includes a relay matrix for selectively connecting output terminals of the charger or discharger across the selected cell or battery.

11. A battery management system comprising a plurality of battery management units as claimed in any one of the preceding claims and a central control unit, the battery management units being in communication with the central control unit via respective communication paths.

12. A system as claimed in claim 11 including a main charger for simultaneously charging a plurality of cells or batteries associated with a selected battery management unit in response to control commands from the central control unit.

13. A system as claimed in claim 11 or claim 12 including a generator responsive to the central control unit to charge selected cells or batteries associated with a battery management unit.

14. A system as claimed in claim 13 wherein the central control unit estimates the energy removed from the battery groups during a predetermined period and dynamically varies the supply of power to cells or batteries associated with selected battery management units to maintain substantially equal states of charge of the battery groups.

15. A system as claimed in any one of claims 11 to 14 wherein the central control unit receives state of charge information from each battery management unit and controls the local charging and discharging of selected cells or batteries via commands to the battery management units sent over the communication medium.

16. A system as claimed in any one of claims 11 to 14 wherein each individual battery management unit controls the charging and discharging of cells or batteries to maintain the states of charge of its associated cells or batteries within a prescribed range.

28. An electric vehicle including a battery management unit or system as claimed in any one of claims 1 to 16.

7. A battery management unit as claimed in any proceeding claim wherein the battery or cell having the highest terminal voltage, above a predetermined high, voltage threshold, is connected to the discharger for a predetermined period until all cells have a terminal voltage below the high voltage threshold.

8. A battery management unit as claimed in any one of the proceeding claims including a power sensor for monitoring the power supplied by the charger to a cell or battery and supplying the information to the controller.

10. A battery management unit as claimed in any one of the proceeding claims including a communications port for facilitating communication of battery information to a central control unit and for receiving commands from the central control unit to control the charging or discharging of selected cells or batteries.

17. A method of charging and equalising the state of charge of a plurality of cells or batteries comprising the steps of:

simultaneously charging the cells or batteries by a main charger; and

discharging the cell or battery having the highest terminal voltage, above a high voltage threshold, for a predetermined period until all cells or batteries are below the high voltage threshold.

18. A method as claimed in claim 17 wherein the state of charge of each cell or battery is determined by measuring the voltage of each cell or battery.

19. A method as claimed in claim 17 or claim 18 wherein cells or batteries having a state of charge below a prescribed low voltage threshold are selectively charged.

20. A method as claimed in claim 19 wherein the cell or battery having the lowest terminal voltage, below a low voltage threshold level, is charged by a secondary charger until all cells or batteries have a terminal voltage above the low voltage threshold level.

21. A method as claimed in any one of claims 17 to 20 wherein the temperature of the cells or batteries is monitored and battery charging or discharging is controlled so that cell or battery temperature does not exceed the predetermined threshold.

22. A method as claimed in any one of claims 17 to 21 wherein a plurality of groups of batteries are simultaneously charged so as to maintain all cells or batteries within a desired range of state of charge.

23. A method as claimed in any one claims 17 to 22 wherein a plurality of battery management units monitor the state of charge of each associated cell or battery and supply state of charge information to a central controller which controls the charging or discharging of cells or batteries according the state of charge information.

24. A method as claimed in claim 23 wherein the central controller selectively connects the output of a generator to selected cells or batteries based on power usage of the cells or batteries over a preceding period.

25. A method as claimed in claim 24 wherein the central controller monitors power consumption for a predetermined period and connects the generator to selected cells or batteries so as to replace the amount of energy consumed during the preceding period.

26. A method as claimed in any one of claims 23 to 25 wherein the central control unit controls all charging and discharging of the cells or batteries.

27. A method as claimed in any one of claims 23 to 25 wherein the central control unit controls the charging of groups of cells or batteries via the main charger or generator and battery management units control the charging and discharging of individual cells or batteries independently.