METHOD AND SYSTEM FOR DETERMINING AND CHARGING LI-ION BATTERY IN AN INTEGRATED POWER SYSTEM

• US 20090309551A1
• Filed: 02/27/2009
• Published: 12/17/2009
• Est. Priority Date: 06/12/2008
• Status: Active Grant

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: LAZAROVICH, DAVID, RUSAN, ILEANA, MICHALKO, RODNEY
• Granted Patent: US 8,330,413 B2
• Time in Patent Office: Days
• US Class Current: 320/138
• 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 2240/662 Temperature
• CPC Class Codes: B60L 3/0046 relating to electric energy storage systems, e.g. batteries or capacitors
• CPC Class Codes: B60L 58/15 Preventing overcharging
• CPC Class Codes: B60L 58/22 Balancing the charge of battery modules
• CPC Class Codes: G01R 31/382 Arrangements for monitoring battery or accumulator variables, e.g. SoC
• CPC Class Codes: H02J 7/0071 with a programmable schedule
• CPC Class Codes: H02J 7/34 Parallel operation in networks using both storage and other dc sources, e.g. providing buffering H02J7/14 takes precedence
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/72 Electric energy management in electromobility
• CPC Class Codes: Y02T 90/16 Information or communication technologies improving the operation of electric vehicles

Abstract

A method and apparatus of determining the state of charge and charging Li-ion batteries while the batteries remain floating on the direct current (DC) bus without the need for a dedicated charger is described. The system includes a battery, a DC generator and a converter, each electrically connected to a DC bus. A charging control algorithm may be used to monitor and control the charging current supplied to the battery. The voltage on the DC bus may be varied to help control the charging current supplied to the battery, based on the battery'"'"'s internal impedance and the battery'"'"'s state of charge.

Claims

1. An apparatus for monitoring and charging a battery in an integrated power system, the apparatus comprising:

a DC bus electrically connected to the battery;

a DC generator electrically connected to the DC bus; and

a converter electrically connected to the DC bus, wherein

the battery is charged while floating on the DC bus, and

a dedicated battery charger is not required to charge the battery.

2. The apparatus of claim 1, further comprising an external power source to supply power to the converter.

3. The apparatus of claim 1, further comprising a generator control unit to regulate the output voltage of the generator.

4. The apparatus of claim 1, further comprising:

a DC generator contactor for electrically disconnecting the DC generator from the DC bus; and

a converter contactor for electrically disconnecting the converter from the DC bus.

5. The apparatus of claim 3, further comprising a current sensor positioned between the DC bus and the battery, wherein the current sensor sends a signal to the generator control unit, thereby regulating the charging current supplied to the battery.

6. The apparatus of claim 1, further comprising a computational device for monitoring the battery temperature and for balancing cells of the battery.

7. The apparatus of claim 3, wherein either the generator control unit, the converter, or both, limit the current supplied to a battery to a predetermined maximum by reducing the voltage of the DC bus.

8. The apparatus of claim 1, wherein the battery is charged to about 1% of the battery nominal amp-hour capacity before battery charging is discontinued.

9. An apparatus for monitoring and charging a battery in an integrated power system comprising:

an external power source providing a first source of power;

a converter connected to said first power source to convert the external power source into a direct current;

a direct current bus connected to the converter to receive the first source of power;

a direct current generator also connected to the direct current bus providing a second source of power; and

a generator control unit connected to the direct current generator to control the second source of power;

wherein a charging algorithm used to charge the battery is implemented in the generator control unit or said converter, or both.

10. The apparatus of claim 9, wherein the charging algorithm controls an output of the direct current generator or an output of the converter, or both, to provide a predetermined maximum charging current to the battery.

11. The apparatus of claim 9, further comprising a current sensor positioned between the direct current bus and the battery, wherein the current sensor sends a signal to the generator control unit, thereby regulating the charging current supplied to the battery.

12. The apparatus of claim 9, wherein the battery is charged directly while floating on the direct current bus.

13. The apparatus of claim 9, wherein a dedicated charger is not used to charge the battery.

14. A method for charging a battery in an integrated power system, the method comprising:

regulating a charging current to a constant predetermined maximum current value by decreasing a voltage level on a DC bus;

supplying the charging current to the battery until a state of charge of the battery reaches a predetermined SOC value while increasing the voltage level as the internal impedance of the battery increases;

reducing the charging current to the battery while maintaining a constant voltage on the DC bus after the state of charge of the battery surpasses the predetermined SOC value; and

discontinuing charging of the battery when the charging current decreases to a value of about 1% of the battery nominal amp-hour capacity.

15. The method of claim 14, further comprising controlling the charging current supplied to the battery with a generator control unit.

16. The method of claim 14, further comprising controlling the charging current supplied to the battery with a converter.

17. The method of claim 14, wherein the charging of the battery is done while the battery is floating on the DC bus.

18. The method of claim 14, wherein the charging of the battery is done without a dedicated charger.