CIRCUITS AND METHODS FOR CONTROLLING A CURRENT FLOWING THROUGH A BATTERY

• US 20110084667A1
• Filed: 10/12/2009
• Published: 04/14/2011
• Est. Priority Date: 10/12/2009
• Status: Active Grant

• Current Assignee: O2 Micro International Limited (O2 Micro Incorporated)
• Original Assignee: O2 Micro International Limited (O2 Micro Incorporated)
• Inventors: LI, Guoxing
• Granted Patent: US 8,143,863 B2
• Time in Patent Office: Days
• US Class Current: 320/145
• CPC Class Codes: H02J 7/0029 with safety or protection devices or circuits
• CPC Class Codes: H02J 7/0071 with a programmable schedule

Abstract

A circuit for controlling a current flowing through a battery includes a driver and a filter coupled to the driver. The driver can generate a pulse signal in a first operating mode and generate a first signal in a second operating mode to control the current through the battery. The filter can filter the pulse signal to provide a filtered DC signal to adjust an on-resistance of a switch in series with the battery based on a duty cycle of the pulse signal in the first operating mode. The filter can receive the first signal and provide a second signal to drive the switch in a linear region in the second operating mode.

Claims

1. A circuit for energy efficient controlling of a current flowing through a battery comprising a rechargeable multi-cell battery pack, said circuit comprising:

a driver operable for generating a pulse signal in a first operating mode and for generating a first signal in a second operating mode, wherein said driver controls said current through said battery; and

a filter coupled to said driver and operable for filtering said pulse signal to provide a filtered DC signal to adjust an on-resistance of a first switch in series with said battery based on a duty cycle of said pulse signal in said first operating mode, and operable for receiving said first signal and for providing a second signal to drive said first switch in a linear region in said second operating mode.

2. The circuit of claim 1, wherein said current in said first operating mode is less than said current in said second operating mode.

3. The circuit of claim 1, wherein said first operating mode comprises a trickle charging mode, and wherein said second operating mode comprises a normal charging mode.

4. The circuit of claim 1, wherein said first operating mode comprises a trickle discharging mode, and wherein said second operating mode comprises a normal discharging mode.

5. The circuit of claim 1, wherein said filter comprises a gate capacitance of said first switch and a resistor in series with said gate capacitance, and wherein said filtered DC signal is substantially constant.

6. The circuit of claim 1, wherein said driver receives a control signal, wherein said control signal comprises a pulse width modulation (PWM) signal in said first operating mode, and wherein said control signal comprises a substantially constant DC signal in said second operating mode.

7. The circuit of claim 1, wherein said driver receives a mode selection signal which indicates whether said circuit is in said first operating mode or said second operating mode.

8. The circuit of claim 1, wherein said driver receives a control signal, wherein said control signal comprises a first pulse width modulation (PWM) signal in said first operating mode, and wherein said control signal comprises a second PWM signal in said second operating mode.

9. The circuit of claim 1, wherein said driver comprises:

a second switch operable for receiving a control signal; and

a resistor coupled to said second switch and operable for providing said pulse signal in said first operating mode and providing said first signal in said second operating mode according to said control signal.

12. The circuit of claim 9, wherein said driver further comprises a third switch coupled to said first switch and said filter and operable for generating a turn-on resistance coupled to said filter, wherein said third switch is turned on for disabling said current flowing through said battery.

13. The circuit of claim 9, wherein said driver further comprises a third switch operable for generating a turn-on resistance coupled in parallel with said resistor and said second switch, wherein said third switch is turned on for enabling said current flowing through said battery.

14. The circuit of claim 1, wherein said duty cycle of said pulse signal is adjusted based on a status of said battery.

10-11. -11. (canceled)

15. A battery system with energy efficient controlling of a current flowing through a battery comprising a rechargeable multi-cell battery pack, comprising:

a switch coupled in series with said battery; and

a circuit coupled to said battery and said switch and operable for selectively operating in a first operating mode and a second operating mode to drive said switch to operate in a saturation region and a linear region respectively so as to adjust a current flowing through said battery, said circuit comprising;

a driver operable for generating a first pulse width modulation (PWM) signal in said first operating mode; and

a filter coupled to said driver and operable for receiving said first PWM signal and generating a substantially constant DC signal to control said switch in said saturation region.

16. The system of claim 15, wherein a duty cycle of said first PWM signal is adjusted based on a status of said battery.

18. The system of claim 15, wherein said filter comprises a gate capacitance of said switch and a resistor in series with said gate capacitance.

19. The system of claim 15, wherein said driver receives a control signal, wherein said control signal comprises a second pulse width modulation (PWM) signal in said first operating mode, and wherein said control signal comprises a substantially constant DC signal in said second operating mode.

20. The system of claim 15, wherein said driver receives a mode selection signal which indicates whether said circuit is in said first operating mode or said second operating mode.

21. The system of claim 15, wherein said driver receives a control signal, wherein said control signal comprises a second pulse width modulation (PWM) signal in said first operating mode, wherein said control signal comprises a third PWM signal in said second operating mode.

17. (canceled)

22. A method for energy efficient controlling of a current flowing through a battery comprising a rechargeable multi-cell battery pack, said method comprising:

generating a pulse signal in a first operating mode;

filtering said pulse signal to provide a filtered DC signal having a substantially constant level determined by a duty cycle of said pulse signal;

adjusting an on-resistance of a switch in series with said battery by said filtered DC signal in said first operating mode; and

driving said switch in a linear region in a second operating mode.

23. The method of claim 22, further comprising:

adjusting said duty cycle of said pulse signal based on a status of said battery, wherein said status is selected from a group consisting of;

a voltage of said battery and a current of said battery.

24-25. -25. (canceled)