Charging Circuit for Parallel Charging in Multiple Battery Systems

• US 20060244420A1
• Filed: 06/20/2006
• Published: 11/02/2006
• Est. Priority Date: 08/17/2001
• Status: Active Grant

• Current Assignee: O2 Micro International Limited (O2 Micro Incorporated)
• Original Assignee: O2 Micro International Limited (O2 Micro Incorporated)
• Inventors: Bucur, Constantin, Niculae, Marian, Stanesti, Vlad Popescu
• Granted Patent: US 7,414,381 B2
• Time in Patent Office: Days
• US Class Current: 320/128
• CPC Class Codes: H02J 2207/20 Charging or discharging characterised by the power electronics converter
• CPC Class Codes: H02J 7/0018 using separate charge circuits
• CPC Class Codes: H02J 7/0019 using switched or multiplexed charge circuits
• CPC Class Codes: H02J 7/0025 Sequential battery discharge in systems with a plurality of batteries
• CPC Class Codes: H02J 7/0068 Battery or charger load switching, e.g. concurrent charging and load supply H02J7/0013 takes precedence
• CPC Class Codes: H02J 7/0069 Charging or discharging for charge maintenance, battery initiation or rejuvenation
• CPC Class Codes: H02J 7/02 for charging batteries from ac mains by converters
• 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: H02M 1/0045 Converters combining the concepts of switch-mode regulation and linear regulation, e.g. linear pre-regulator to switching converter, linear and switching converter in parallel, same converter or same transistor operating either in linear or switching mode
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

Abstract

A charging circuit for controlling a system charging parameter provided to a host of rechargeable batteries, wherein the host of batteries includes at least a first battery and second battery that may be coupled in parallel. The charging circuit provides for fast charging of rechargeable batteries in parallel. Independent current and voltage sensing for each battery enables parallel charging of batteries at different charging currents. The charging circuit may be configured to accept either analog or digital signals from an associated power management unit.

Claims

1. A charging circuit for controlling a system charging parameter comprising:

a host power management unit configured to execute a power management routine;

a charging control circuit for controlling a system charging parameter provided to a plurality of batteries by a DC to DC converter; and

a regulating circuit configured to reduce said system charging parameter provided to said plurality of batteries if a first battery charging current exceeds a first maximum charging current level or a second battery charging current exceeds a second maximum charging current level, or a first battery charging voltage exceeds a first maximum charging voltage level, or a second battery charging voltage exceeds a second maximum charging voltage level, said first and said second maximum charging current levels and said first and said second maximum charging voltage levels provided to at least one input terminal of said charging circuit by said host power management unit.

2. The charging circuit of claim 1, wherein said charging control circuit further comprises:

a first path configured to monitor said first battery charging current provided to a first battery;

a second path configured to monitor said second battery charging current provided to a second battery;

a third path configured to monitor said first battery charging voltage provided to said first battery; and

a fourth path configured to monitor said second battery charging voltage provided to said second battery.

3. The charging circuit of claim 1, wherein said first maximum charging current level is substantially equal to said second maximum charging current level.

4. The charging circuit of claim 1, wherein said first maximum charging voltage level is substantially equal to said second maximum charging voltage level.

5. The charging circuit of claim 2, wherein said first path comprises a first error amplifier configured to receive a first monitoring signal representative of said first battery charging current and a first comparison signal representative of said first maximum charging current level, and to provide a first control signal to said regulating circuit based on a difference between said first monitoring signal and said first comparison signal, and wherein said second path comprises a second error amplifier configured to receive a second monitoring signal representative of said second battery charging current and a second comparison signal representative of said second maximum charging current level, and to provide a second control signal to said regulating circuit based on a difference between said second monitoring signal and said second comparison signal, an output of said first and second error amplifiers coupled directly to said regulating circuit, and wherein said first error amplifier controls said regulating circuit if said first error amplifier detects said first charging current is greater than said first maximum charging current level before said second error amplifier detects said second charging current is greater than said second maximum charging current level.

6. The charging circuit of claim 5, wherein said second error amplifier configured to provide a second control signal to said regulating circuit based on a difference between said second monitoring signal and said second comparison signal, an output of said first and said second error amplifiers coupled directly to said regulating circuit, and wherein said first error amplifier controls said regulated circuit if said first error amplifier detects said first battery charging current is greater than said first maximum charging current level before said second error amplifier detects said second battery charging current is greater than said second maximum charging current level.

7. A method for controlling a system charging parameter comprising:

providing a control signal to a DC to DC converter by a regulating circuit; and

reducing said system charging parameter provided to a plurality of batteries that may be coupled in parallel, if a first battery charging current exceeds a first maximum charging current level or a second battery charging current exceeds a second maximum charging current level, or a first battery charging voltage exceeds a first maximum charging voltage level, or a second battery charging voltage exceeds a second maximum charging voltage level, said first and said second maximum charging current levels and said first and said second maximum charging voltage levels provided to at least one input terminal of a charging circuit by a host power management unit.

8. The method of controlling a system charging parameter in claim 7, further comprising:

monitoring said first battery charging current provided to a first battery by a first path;

monitoring said second battery charging current provided to a second battery by a second path;

monitoring said first battery charging voltage provided to said first battery by a third path; and

monitoring said second battery charging voltage provided to said second battery by a fourth path.

9. The method of controlling a system charging parameter of claim 8, wherein said first path comprises a first error amplifier configured to receive a first monitoring signal representative of said first battery charging current and a first comparison signal representative of said first maximum charging current level, and to provide a first control signal to said regulating circuit based on a difference between said first monitoring signal and said first comparison signal, and wherein said second path comprises a second error amplifier configured to receive a second monitoring signal representative of said second battery charging current and a second comparison signal representative of said second maximum charging current level, and to provide a second control signal to said regulating circuit based on a difference between said second monitoring signal and said second comparison signal, an output of said first and said second error amplifiers coupled directly to said regulating circuit, and wherein said first error amplifier controls said regulating circuit if said first error amplifier detects said first charging current is greater than said first maximum charging current level before said second error amplifier detects said second charging current is greater than said second maximum charging current level.

10. The method of claim 7, wherein said first maximum charging current level is substantially equal to said second maximum charging current level.

11. The method of claim 7, wherein said first maximum charging voltage level is substantially equal to said second maximum charging voltage level.

12. An electronic device comprising:

a power management unit configured to provide an output signal representative of at least a first maximum charging current level, a second maximum charging current level, a first maximum charging voltage level, and a second maximum charging voltage level;

a charging control circuit for controlling a system charging parameter provided to said plurality of batteries by a DC to DC converter; and

a regulating circuit configured to reduce said system charging parameter provided to a plurality of batteries if a first battery charging current exceeds said first maximum charging current level or a second battery charging current exceeds said second maximum charging current level, or a first battery charging voltage exceeds said first maximum charging voltage level, or a second battery charging voltage exceeds said second maximum charging voltage level, said first and said second maximum charging current levels and said first and said second maximum charging voltage levels provided to at least one input terminal of said charging circuit by said power management unit.

13. The electronic device of claim 12, wherein said charging control circuit comprising:

a first path configured to monitor said first battery charging current provided to a first battery and compare said first battery charging current to said first maximum charging current level;

a second path configured to monitor said second battery charging current level provided to a second battery and compare said second battery charging current to said second maximum charging current level;

a third path configured to monitor said first battery charging voltage provided to said first battery and compare said first battery charging voltage to said first maximum charging voltage level; and

a fourth path configured to monitor said second battery charging voltage provided to said second battery and compare said second battery charging voltage to said second maximum charging voltage level.

14. The electronic device of claim 12, wherein said output signal from said power management unit comprises an analog signal.

15. The electronic device of claim 12, wherein said output signal from said power management unit comprises a digital signal.

16. The electronic device of claim 15, wherein said charging circuit further comprising:

a digital interface configured to receive said digital signal from said power management unit and provide an interface output signal;

a DAC configured to receive said interface output signal and convert said signal to an analog signal representative of said interface output signal; and

a multiplexer to separate said analog signal into a plurality of analog signals representative of at least said maximum charging current level, said second maximum charging current level, said first maximum charging voltage level, and said second maximum charging circuit voltage level.

17. An electronic device comprising:

means for running a power management routine;

means for providing a control signal to a DC to DC converter; and

means for reducing a system charging parameter provided to a plurality of batteries if a first battery charging current exceeds a first maximum charging current level or a second battery charging current exceeds a second maximum charging current level, or a first battery charging voltage exceeds a first maximum charging voltage level, or a second battery charging voltage exceeds a second maximum charging voltage level, said first and said second maximum charging current levels and said first and said second maximum charging voltage levels provided to at least one input terminal of a charging circuit.

18. The electronic device of claim 17, further comprising:

means for controlling a charge of said plurality of batteries;

means for monitoring a first battery charging current level provided to a first battery and compare said first battery charging current level to said first maximum charging current level;

means for monitoring a second battery charging current level provided to a second battery and compare said second battery charging current level to said second maximum charging current level;

means for monitoring a first battery charging voltage provided to said first battery and compare said first battery charging voltage to said first maximum charging voltage level;

means for monitoring a second battery charging voltage provided to said second battery and compare said second battery charging voltage to said second maximum charging voltage level;

means for selecting at least one of said DC source and said plurality of batteries in response to a power management unit (PMU) output signal; and

means for monitoring and identifying power crisis conditions.

19. The electronic device of claim 18, further comprising:

means for providing a control signal to a selector circuit of a detected power crisis condition.