Systems and methods for regulating pulsed pre-charge current in a battery system

• US 7,378,819 B2
• Filed: 01/13/2005
• Issued: 05/27/2008
• Est. Priority Date: 01/13/2005
• Status: Active Grant

• Current Assignee: Dell Products LP (Dell Technologies Inc.)
• Original Assignee: Dell Products LP (Dell Technologies Inc.)
• Inventors: Wang, Ligong, Breen, John J., Goodroe, Joey M.
• Primary Examiner(s): Vu; Bao Q.
• Assistant Examiner(s): WILLIAMS, ARUN C
• Application Number:
  US11/034,624
• Publication Number:
  US 20060152194A1
• Time in Patent Office: 1,230 Days
• Field of Search: 320/121, 320/163
• US Class Current: 320/121
• CPC Class Codes: H02J 7/0071 with a programmable schedule
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

Systems and methods for regulating pre-charge current in a battery system, such as a battery system of an information handling system, by controlling duty cycle of the charging current provided to battery cell/s of the battery system.

Claims

1. A method of charging one or more battery cells of a battery pack coupled to a battery charging apparatus, comprising:

providing said battery pack as a replaceable battery pack of an information handling system coupled to said battery charging apparatus;

receiving a charging current in said battery pack from said battery charging apparatus, said charging current having a first current value that is the full value of charging current provided to said battery pack by said battery charging apparatus;

adjusting the duty cycle of said charging current after it is received in said battery pack to produce a pulsed pre-charging current having a second current value, said second current value being less than said first current value; and

charging said one or more battery cells of said battery pack by first entering a pre-charging mode when a voltage of said one or more battery cells of said battery pack is below a low voltage threshold by controlling the duty cycle of said charging current after it is received in said battery pack from said battery charging apparatus to limit the level of said pulsed pre-charging current to said second current value that is lower than said first current value provided by said battery charging apparatus, and then entering a full charge mode when a voltage of said one or more battery cells of said battery pack reaches said low voltage threshold by increasing the duty cycle of said charging current after it is received in said battery pack from said battery charging apparatus to a higher duty cycle to allow said charging current from said battery charging apparatus having said first current value to be provided to said battery pack until said one or more battery cells are fully charged;

wherein a duty cycle of said charging current is represented by t1/(t1+t2), with t1 representing time that current is on and t2 representing time that current is off such that a duty cycle of 100% provides said full value of said charging current from said battery charging apparatus to said one or more battery cells, and such that a duty cycle of 0% stops flow of said charging current from said battery charging apparatus to said one or more battery cells.

2. The method of claim 1, wherein said battery pack comprises a battery pack of a portable information handling system.

3. The method of claim 2, wherein said one or more battery cells of said battery pack comprise Li-ion or NiMH battery cells.

4. The method of claim 1, wherein said battery pack comprises:

battery current control circuitry coupled between said battery charging apparatus and said one or more battery cells, said battery current control circuitry including a charge circuit having a charge FET switching element;

a battery management unit (BMU) including a microcontroller and an analog front end (AFE) circuitry, said BMU being coupled to said battery current control circuitry and being configured to control said charge FET switching element, and said AFE being coupled to said one or more battery cells and being configured to monitor said voltage of said one or more battery cells; and

wherein said method further comprises;

using said BMU to adjust the duty cycle of said charging current received in said battery pack by controlling said charge FET switching element to produce said pulsed pre-charging current having said second current value to provide said pre-charging current to said one or more battery cells of said battery pack when said voltage of said one or more battery cells of said battery pack monitored by said AFE is below said low voltage threshold, and

using said BMU to adjust the duty cycle of said charging current received in said battery pack by controlling said charge FET switching element to provide said charging current having said first current value to said one or more battery cells of said battery pack when said voltage of said one or more battery cells of said battery pack monitored by said AFE reaches said low voltage threshold.

5. The method of claim 4, wherein said battery pack comprises a battery pack of a portable information handling system.

6. The method of claim 5, wherein said one or more battery cells of said battery pack comprise Li-ion or NiMH battery cells.

7. The method of claim 5, wherein said portable information handling system comprises a notebook computer.

8. The method of claim 4, wherein said AFE is further coupled to monitor current provided to said one or more battery cells or from said one or more battery cells;

and wherein a duty cycle of said pulsed pre-charging current is higher than the current monitoring sampling rate of said AFE.

9. The battery pack of claim 8, wherein a frequency of said duty cycle is greater than about 2 times the current monitoring sampling rate of said AFE.

10. The method of claim 4, wherein said charging current is received from said battery charging apparatus at terminals of said battery pack, and wherein said method further comprises using said BMU to adjust the duty cycle of said charging current received in said battery pack by:

determining said duty cycle based on a desired level of pre-charge current and based on said first current value of said full value of said charging current provided to said terminals of said battery pack by said battery charging apparatus, said desired level of pre-charge current having said second current value; and

adjusting said duty cycle of said charging current after it is received at said terminals of said battery pack to produce said pulsed pre-charging current having said desired second current value.

11. The method of claim 1, wherein said battery pack is configured to be temporarily coupled to receive current from said battery charging apparatus.

12. The method of claim 1, wherein said charging current is received from said battery charging apparatus at terminals of said battery pack, and wherein said method further comprises:

determining said duty cycle based on a desired level of pre-charge current and based on said first current value of said full value of said charging current provided to said terminals of said battery pack by said battery charging apparatus, said desired level of pre-charge current having said second current value; and

adjusting said duty cycle of said charging current after it is received at said terminals of said battery pack to produce said pulsed pre-charging current having said desired second current value.

13. The method of claim 12, further comprising determining said desired second level of pre-charge current based on a number and capacity of battery cells of said battery pack.

14. A battery pack configured to be coupled to a battery charging apparatus, said battery pack comprising:

one or more battery cells;

battery current control circuitry configured to be coupled between said battery charging apparatus and said one or more battery cells, said battery current control circuitry being configured to receive a charging current having a first current value from said battery charging apparatus that is the full value of charging current provided to said battery pack by said battery charging apparatus, and to control flow of said charging current to said battery cells from said battery charging apparatus; and

a duty cycle controller coupled to said battery current control circuitry, said duty cycle controller being configured to control operation of said battery current circuitry so as to adjust a duty cycle of said charging current after it is received in said battery pack from said battery charging apparatus to provide a pulsed pre-charging current having a second current value to said one or more battery cells, said second current value being less than said first current value;

wherein said duty cycle controller is further configured to first enter a pre-charging mode when a voltage of said one or more battery cells of said battery pack is below a low voltage threshold by controlling the duty cycle of said charging current after it is received in said battery pack from said battery charging apparatus to limit the level of said pulsed pre-charging current to said second current value that is lower than said first current value provided by said battery charging apparatus, and then to enter a full charge mode when a voltage of said one or more battery cells of said battery pack reaches said low voltage threshold by increasing the duty cycle of said charging current after it is received in said battery pack from said battery charging apparatus to a higher duty cycle to allow said charging current from said battery charging apparatus having said first current value to be provided to said battery pack until said one or more battery cells are fully charged;

wherein said duty cycle controller is further configured to control operation of said battery current circuitry to produce a duty cycle of said charging current that is represented by t1/(t1+t2), with t1 representing time that current is on and t2 representing time that current is off and such that a duty cycle of 100% provides said full value of said charging current from said battery charging apparatus to said one or more battery cells, and such that a duty cycle of 0% stops flow of said charging current from said battery charging apparatus to said one or more battery cells; and

wherein said battery pack is a replaceable battery pack of an information handling system.

15. The battery pack of claim 14, further comprising a battery cell voltage detector coupled to monitor voltage of said one or more battery cells, and coupled to provide a signal representative of said monitored voltage to said duty cycle controller.

16. The battery pack of claim 15, wherein said battery current control circuitry comprises a charge circuit having a charge FET switching element;

wherein said duty cycle controller comprises a microcontroller of a battery management unit (BMU); and

wherein said battery voltage detector comprises an analog front end (AFE) of said BMU.

17. The battery pack of claim 16, wherein said AFE is further coupled to monitor current provided to said one or more battery cells or from said one or more battery cells;

and wherein a frequency of said duty cycle is greater than about 2 times the current monitoring sampling rate of said AFE.

18. The battery pack of claim 14, wherein said battery pack comprises a battery pack of a portable information handling system.

19. The battery pack of claim 18, wherein said one or more battery cells of said battery pack comprise Li-ion or NiMH battery cells.

20. The battery pack of claim 18, wherein portable information handling system comprises a notebook computer.

21. The battery pack of claim 14, wherein said battery pack is configured to be temporarily coupled to receive current from said battery charging apparatus.

22. The battery pack of claim 14, wherein said battery pack comprises terminals configure to receive said charging current from said battery charging apparatus;

and wherein said duty cycle controller is further configured to;

determine said duty cycle based on a desired level of pre-charge current and based on said first current value of said full value of said charging current provided to said terminals of said battery pack by said battery charging apparatus, said desired level of pre-charge current having said second current value; and

control operation of said battery current circuitry so as to adjust said duty cycle of said charging current after it is received at said terminals of said battery pack to produce said pulsed pre-charging current having said desired second current value.

23. A battery pack for a portable information handling system configured to be coupled to a battery charging apparatus, said battery pack comprising:

one or more battery cells;

a charge circuit configured to be coupled between said battery charging apparatus and said one or more battery cells, said charge circuit comprising a charge FET switching element and being configured to receive a charging current having a first current value from said battery charging apparatus that is the full value of charging current provided to said battery pack by said battery charging apparatus; and

a battery management unit (BMU) coupled to said charge circuit, said BMU comprising a microcontroller;

wherein said BMU is configured to control operation of said charge FET switching element of said charge circuit so as to adjust a duty cycle of said charging current after it is received in said battery pack from said battery charging apparatus to provide a pulsed pre-charging current having a second current value to said one or more battery cells, said second current value being less than said first current value;

wherein said BMU is further configured to first enter a pre-charging mode when a voltage of said one or more battery cells of said battery pack is below a low voltage threshold by controlling the duty cycle of said charging current after it is received in said battery pack from said battery charging apparatus to limit the level of said pulsed pre-charging current to said second current value that is lower than said first current value provided by said battery charging apparatus, and then to enter a full charge mode when a voltage of said one or more battery cells of said battery pack reaches said low voltage threshold by increasing the duty cycle of said charging current after it is received in said battery pack from said battery charging apparatus to a higher duty cycle to allow said charging current from said battery charging apparatus having said first current value to be provided to said battery pack until said one or more battery cells are fully charged;

wherein said BMU is further configured to control operation of said battery current circuitry to produce a duty cycle of said charging current that is represented by t1/(t1+t2), with t1 representing time that current is on and t2 representing time that current is off and such that a duty cycle of 100% provides said full value of said charging current from said battery charging apparatus to said one or more battery cells, and such that a duty cycle of 0% stops flow of said charging current from said battery charging apparatus to said one or more battery cells; and

wherein said battery pack is a replaceable, battery pack of said portable information handling system.

24. The battery pack of claim 23, wherein said BMU further comprises an analog front end (AFE) coupled to monitor said voltage of said one or more battery cells.

25. The battery pack of claim 24, wherein said AFE further comprises a current sensor coupled to monitor current provided to said one or more battery cells or from said one or more battery cells;

and wherein a frequency of said duty cycle is higher than the sampling rate of said current sensor.

26. The battery pack of claim 25, wherein a frequency of said duty cycle is greater than about 2 times the sampling rate of said current sensor.

27. The battery pack of claim 23, wherein said one or more battery cells of said battery pack comprise Li-ion or NiMH battery cells.

28. The battery pack of claim 23, wherein portable information handling system comprises a notebook computer.

29. The battery pack of claim 23, wherein said battery pack is configured to be temporarily coupled to receive current from said battery charging apparatus.

30. The battery pack of claim 23, wherein said battery pack comprises terminals configure to receive said charging current from said battery charging apparatus;

and wherein said BMU is further configured to;

determine said duty cycle based on a desired level of pre-charge current and based on said first current value of said full value of said charging current provided to said terminals of said battery pack by said battery charging apparatus, said desired level of pre-charge current having said second current value; and

control operation of said charge FET switching element of said charge circuit so as to adjust said duty cycle of said charging current after it is received at said terminals of said battery pack to produce said pulsed pre-charging current having said desired second current value.

31. A method of charging one or more battery cells of a battery pack coupled to a battery charging apparatus, comprising:

providing said battery pack as a replaceable battery pack of an information handling system coupled to said battery charging apparatus;

receiving a charging current in said battery pack from said battery charging apparatus, said charging current having a first current value that is the full value of charging current provided to said battery pack by said battery charging apparatus;

adjusting a duty cycle of said charging current after it is received in said battery pack to produce a pulsed pre-charging current having a second current value, said second current value being equal to said first current value provided by said battery charging apparatus times said duty cycle; and

charging said one or more battery cells of said battery pack by first entering a pre-charging mode when a voltage of said one or more battery cells of said battery pack is below a low voltage threshold by controlling the duty cycle of said charging current after it is received in said battery pack from said battery charging apparatus to limit the level of said pulsed pre-charging current to said second current value that is equal to said first current value provided by said battery charging apparatus times said duty cycle, and then entering a full charge mode when a voltage of said one or more battery cells of said battery pack reaches said low voltage threshold by increasing the duty cycle of said charging current after it is received in said battery pack from said battery charging apparatus to a higher duty cycle to allow said charging current from said battery charging apparatus having said first current value to be provided to said battery pack until said one or more battery cells are fully charged;

wherein a duty cycle of said charging current is represented by t1/(t1+t2), with t1 representing time that current is on and t2 representing time that current is off such that a duty cycle of 100% provides said full value of said charging current from said battery charging apparatus to said one or more battery cells, and such that a duty cycle of 0% stops flow of said charging current from said battery charging apparatus to said one or more battery cells;

wherein a micro-controller determines a required duty cycle based on a desired second current value and based on said first current value from said battery charging apparatus; and

wherein said microcontroller controls a frequency of said pulsed pre-charging current.

32. A battery pack configured to be coupled to a battery charging apparatus, said battery pack comprising:

one or more battery cells;

battery current control circuitry configured to be coupled between said battery charging apparatus and said one or more battery cells, said battery current control circuitry being configured to receive a charging current having a first current value from said battery charging apparatus that is the full value of charging current provided to said battery pack by said battery charging apparatus, and to control flow of said charging current to said battery cells from said battery charging apparatus; and

a duty cycle controller coupled to said battery current control circuitry, said duty cycle controller being configured to control operation of said battery current circuitry so as to adjust a duty cycle of said charging current after it is received in said battery pack from said battery charging apparatus to provide a pulsed pre-charging current having a second current value to said one or more battery cells, said second current value being equal to said first current value provided by said batter charging apparatus times said duty cycle;

wherein said micro-controller is configured to determine a required duty cycle based on a desired second current value and based on said first current value from said battery charging apparatus, and wherein said microcontroller is configured to control a frequency of said pulsed pre-charging current;

wherein said duty cycle controller is further configured to first enter a pre-charging mode when a voltage of said one or more battery cells of said battery pack is below a low voltage threshold by controlling the duty cycle of said charging current after it is received in said battery pack from said battery charging apparatus to limit the level of said pulsed pre-charging current to said second current value that is equal to said first current value provided by said battery charging apparatus times said duty cycle, and then to enter a full charge mode when a voltage of said one or more battery cells of said battery pack reaches said low voltage threshold by increasing the duty cycle of said charging current after it is received in said battery pack from said battery charging apparatus to a higher duty cycle to allow said charging current from said battery charging apparatus having said first current value to be provided to said battery pack until said one or more battery cells are fully charged;

wherein said duty cycle controller is further configured to control operation of said battery current circuitry to produce a duty cycle of said charging current that is represented by t1/(t1+t2), with t1 representing time that current is on and t2 representing time that current is off and such that a duty cycle of 100% provides said full value of said charging current from said battery charging apparatus to said one or more battery cells, and such that a duty cycle of 0% stops flow of said charging current from said battery charging apparatus to said one or more battery cells; and

wherein said battery pack is a replaceable battery pack of an information handling system.

33. A battery pack for a portable information handling system configured to be coupled to a battery charging apparatus, said battery pack comprising:

one or more battery cells;

a charge circuit configured to be coupled between said battery charging apparatus and said one or more battery cells, said charge circuit comprising a charge FET switching element and being configured to receive a charging current having a first current value from said battery charging apparatus that is the full value of charging current provided to said battery pack by said battery charging apparatus; and

a battery management unit (BMU) coupled to said charge circuit, said BMU comprising a microcontroller;

wherein said BMU is configured to control operation of said charge FET switching element of said charge circuit so as to adjust a duty cycle of said charging current after it is received in said battery pack from said battery charging apparatus to provide a pulsed pre-charging current having a second current value to said one or more battery cells, said second current value being equal to said first current value provided by said batter charging apparatus times said duty cycle;

wherein said BMU is further configured to first enter a pre-charging mode when a voltage of said one or more battery cells of said battery pack is below a low voltage threshold by controlling the duty cycle of said charging current after it is received in said battery pack from said battery charging apparatus to limit the level of said pulsed pre-charging current to said second current value that is said first current value, provided by said battery charging apparatus, times duty cycle and then to enter a full charge mode when a voltage of said one or more battery cells of said battery pack reaches said low voltage threshold by increasing the duty cycle of said charging current after it is received in said battery pack from said battery charging apparatus to a higher duty cycle to allow said charging current from said battery charging apparatus having said first current value to be provided to said battery pack until said one or more battery cells are fully charged;

wherein said BMU is further configured to control operation of said battery current circuitry to produce a duty cycle of said charging current that is represented by t1/(t1+t2), with t1 representing time that current is on and t2 representing time that current is off and such that a duty cycle of 100% provides said full value of said charging current from said battery charging apparatus to said one or more battery cells, and such that a duty cycle of 0% stops flow of said charging current from said battery charging apparatus to said one or more battery cells;

wherein said BMU comprises a micro-controller configured to determine a required duty cycle based on a desired second current value and based on said first current value from said battery charging apparatus, and wherein said microcontroller is configured to control a frequency of said pulsed pre-charging current; and

wherein said battery pack is a replaceable battery pack of said portable information handling system.