SYSTEMS AND METHODS OF ADAPTIVE BATTERY CHARGING

• US 20150130419A1
• Filed: 11/06/2014
• Published: 05/14/2015
• Est. Priority Date: 11/12/2013
• Status: Active Grant

• Current Assignee: SG Micro Limited
• Original Assignee: Grenotek Integrated, Inc.
• Inventors: Zhai, Jerry Zhijun
• Granted Patent: US 9,853,477 B2
• Time in Patent Office: Days
• US Class Current: 320/112
• CPC Class Codes: H02J 7/0071 with a programmable schedule

Abstract

Systems and methods of charging battery power that can be selectively controlled by the overall voltage of a battery pack and specified voltages of battery cells within the battery pack, and that can selectively perform current-controlled and voltage-controlled battery charging (referred to herein as “adaptive battery cell charging”). The systems and methods employ a digital core for managing the charging of battery power provided by the battery pack. By using the overall voltage of the battery pack and specified voltages of battery cells to selectively control the charging of battery power, battery charging times can be reduced. By employing current/voltage sense amplifiers to monitor the battery pack voltage, the battery cell voltage(s), and a battery charging current, the effect of cable resistance to/from the battery pack can be reduced. By performing adaptive battery cell charging, battery charging times and battery stress can be reduced, while increasing battery charge/discharge life cycles.

Claims

1. A system for charging battery power in a battery pack, the battery pack including one or more battery cells, the system comprising:

a first voltage sense amplifier operative to sense a level of a battery pack voltage;

at least one second voltage sense amplifier operative to sense at least one level of at least one battery cell voltage;

a battery charging manager operative;

to set predetermined target voltage levels for the battery pack voltage and the at least one battery cell voltage; and

to select one or more of the battery pack voltage and the at least one battery cell voltage to control the charging of the battery power in the battery pack; and

a charging signal generator operative to generate a charging signal, the charging signal being operative to minimize error deviations in the levels of the selected one or more of the battery pack voltage and the at least one battery cell voltage from the respective predetermined target voltage levels.

2. The system of claim 1 further comprising a power stage operative to receive the charging signal from the charging signal generator, and to generate a battery charging current using the charging signal.

3. The system of claim 2 further comprising a current sense amplifier operative to sense a level of the battery charging current.

4. The system of claim 3 wherein the battery charging manager is further operative to select one or more of the battery pack voltage and the at least one battery cell voltage based at least on one or more of the level of the battery pack voltage, the at least one level of the at least one battery cell voltage, and the level of the battery charging current.

5. The system of claim 2 wherein the battery charging manager is further operative to set a predetermined target current level for the battery charging current.

6. The system of claim 5 wherein the charging signal is further operative to minimize an error deviation in the level of the battery charging current from the predetermined target current level.

7. A method of charging battery power in a battery pack that includes one or more battery cells, comprising:

monitoring a level of a battery pack voltage;

monitoring at least one level of at least one battery cell voltage;

setting predetermined target voltage levels for the battery pack voltage and the at least one battery cell voltage;

selecting at least one of the battery pack voltage and the at least one battery cell voltage to control the charging of the battery power in the battery pack; and

generating a charging signal for minimizing error deviations in the levels of the selected one or more of the battery pack voltage and the at least one battery cell voltage from the respective predetermined target voltage levels.

8. The method of claim 7 further comprising generating a battery charging current using the charging signal.

9. The method of claim 8 further comprising monitoring a level of the battery charging current, and wherein the selecting of the at least one of the battery pack voltage and the at least one battery cell voltage includes selecting at least one of the battery pack voltage and the at least one battery cell voltage based at least on one or more of the level of the battery pack voltage, the at least one level of the at least one battery cell voltage, and the level of the battery charging current.

10. The method of claim 8 further comprising setting a predetermined target current level for the battery charging current, and wherein the generating of the charging signal includes generating the charging signal for minimizing an error deviation in the level of the battery charging current from the predetermined target current level.

11. A system for charging battery power in a battery pack, the battery pack including one or more battery cells, the system comprising:

at least one voltage sense amplifier operative, during a current-controlled charging period of the battery pack, to sense a plurality of increasing voltage levels of a battery charging voltage;

a battery charging manager operative, during the current-controlled charging period of the battery pack, to reduce, at each of the plurality of increasing voltage levels of the battery charging voltage, a level of a battery charging current by a predetermined amount until the battery charging voltage reaches a specified voltage saturation level; and

a current sense amplifier operative, during a voltage-controlled charging period of the battery pack, to sense further reduction in the battery charging current to less than a specified current saturation level,

wherein, during the voltage-controlled charging period of the battery pack, the battery charging manager is further operative, while the battery charging current is less than the specified current saturation level but greater than a specified current cutoff level, to reduce the battery charging voltage to a specified battery float voltage level.

12. The system of claim 11 further comprising a power adapter operative to provide an adapter current, the power adapter having an associated adapter output current limit and an associated adapter voltage.

13. The system of claim 12 wherein the battery charging manager is further operative:

to obtain a difference between the adapter output current limit and the adapter current;

to filter the difference to obtain a filtered output power limit;

to obtain a ratio of the adapter voltage and one of a battery pack voltage and a battery cell voltage;

to multiply the ratio by a predetermined constant; and

to obtain a sum of the filtered output power limit and the ratio multiplied by the predetermined constant, thereby generating a limit for the battery charging current with reduced delay.

14. The system of claim 13 wherein the battery charging manager is further operative:

to compare the limit for the battery charging current with a specified minimum battery charging current; and

in the event the limit for the battery charging current is less than the specified minimum battery charging current, to terminate the charging of the battery power in the battery pack.

15. The system of claim 11 wherein the plurality of voltage levels of the battery charging voltage define a charging voltage profile, wherein the levels of the battery charging current define a charging current profile, and wherein the battery charging manager includes at least a first set of internal registers and a second set of internal registers, the plurality of voltage levels defining the charging voltage profile being loadable in the first set of internal registers, and the levels defining the charging current profile being loadable in the second set of internal registers.

16. The system of claim 15 wherein the battery charging manager further includes a communications interface, the plurality of voltage levels defining the charging voltage profile being loadable in the first set of internal registers over the communications interface, and the levels defining the charging current profile being loadable in the second set of internal registers over the communications interface.

17. A method of charging battery power in a battery pack that includes one or more battery cells, comprising:

performing current-controlled charging of the battery pack, including;

monitoring a plurality of increasing voltage levels of a battery charging voltage; and

at each of the plurality of increasing voltage levels of the battery charging voltage, reducing a battery charging current by a predetermined amount until the battery charging voltage reaches a specified voltage saturation level; and

performing voltage-controlled charging of the battery pack, including;

monitoring further reduction in the battery charging current to less than a specified current saturation level; and

while the battery charging current is less than the specified current saturation level but greater than a specified current cutoff level, reducing the battery charging voltage to a specified battery float voltage level.

18. The method of claim 17 further comprising:

obtaining a difference between an adapter output current limit and an adapter current;

filtering the difference to obtain a filtered output power limit;

obtaining a ratio of an adapter voltage and one of a battery pack voltage and a battery cell voltage;

multiplying the ratio by a predetermined constant; and

obtaining a sum of the filtered output power limit and the ratio multiplied by the predetermined constant, thereby generating a limit for the battery charging current with reduced delay.

19. The method of claim 18 further comprising:

comparing the limit for the battery charging current with a specified minimum battery charging current; and

in the event the limit for the battery charging current is less than the specified minimum battery charging current, terminating the charging of the battery power in the battery pack.

20. The method of claim 17 wherein the plurality of voltage levels of the battery charging voltage define a charging voltage profile, wherein levels of the battery charging current define a charging current profile, and wherein the method further comprises:

providing a battery charging manager for performing one or more of the current-controlled charging and the voltage-controlled charging of the battery pack, the battery charging manager including at least a first set of internal registers and a second set of internal registers, the plurality of voltage levels defining the charging voltage profile being loadable in the first set of internal registers, and the levels defining the charging current profile being loadable in the second set of internal registers.

21. The method of claim 20 wherein the battery charging manager further includes a communications interface, and wherein the method further comprises:

modifying one or more of the plurality of voltage levels defining the charging voltage profile loadable in the first set of internal registers by remotely loading, over the communications interface, the one or more of the the plurality of voltage levels in respective ones of the first set of internal registers.

22. The method of claim 20 wherein the battery charging manager further includes a communications interface, and wherein the method further comprises:

modifying one or more of the levels defining the charging current profile loadable in the second set of internal registers by remotely loading, over the communications interface, the one or more of the levels in respective ones of the second set of internal registers.

23. A method of charging battery power in a battery pack that includes one or more battery cells, comprising:

monitoring a level of a battery pack voltage;

monitoring at least one level of at least one battery cell voltage;

setting predetermined target voltage levels for the battery pack voltage and the at least one battery cell voltage;

selecting at least one of the battery pack voltage and the at least one battery cell voltage to control the charging of the battery power in the battery pack;

generating a charging signal for minimizing error deviations in the levels of the selected one or more of the battery pack voltage and the at least one battery cell voltage from the respective predetermined target voltage levels;

generating a battery charging current at a corresponding battery charging voltage using the charging signal;

performing current-controlled charging of the battery pack, including;

monitoring a plurality of increasing voltage levels of a battery charging voltage; and

at each of the plurality of increasing voltage levels of the battery charging voltage, reducing the battery charging current by a predetermined amount until the battery charging voltage reaches a specified voltage saturation level; and

performing voltage-controlled charging of the battery pack, including;

monitoring further reduction in the battery charging current to less than a specified current saturation level; and

while the battery charging current is less than the specified current saturation level but greater than a specified current cutoff level, reducing the battery charging voltage to a specified battery float voltage level.

24. The method of claim 23 further comprising, in the event the battery charging current is less than the specified current cutoff level, terminating the charging of the battery power in the battery pack.

25. The method of claim 23 wherein the generating of the charging signal includes generating a pulse width modulation (PWM) signal, and wherein the method further comprises controlling, by the PWM signal, gate drive circuitry for providing the battery charging current.