Methods and systems for controlling an AC adapter and battery charger in a closed loop configuration

• US 7,755,330 B2
• Filed: 11/05/2004
• Issued: 07/13/2010
• Est. Priority Date: 03/31/2004
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Formenti, Jose Antonio Vieira, Martinez, Robert
• Primary Examiner(s): Tso; Edward
• Assistant Examiner(s): Muralidar; Richard V
• Application Number:
  US10/983,284
• Publication Number:
  US 20050225304A1
• Time in Patent Office: 2,076 Days
• Field of Search: 320/148, 320/164, 320/159, 323/211, 323/267, 323282-285, 307 31- 33
• US Class Current: 320/164
• CPC Class Codes: H02J 5/00 Circuit arrangements for transfer of electric power between ac networks and dc networks H02J3/36 takes precedence
• CPC Class Codes: H02J 7/0031 using battery or load disconnect circuits H02J9/002 takes precedence
• CPC Class Codes: H02J 7/02 for charging batteries from ac mains by converters

Abstract

Disclosed are methods, circuits, and systems for implementing an AC voltage adapter and battery charger system in a closed loop topology. Embodiments of the invention include methods for controlling an AC adapter charging a battery with steps for using a closed loop configuration to monitor one or more selected parameters in the charging loop. Feedback to the AC adapter is used for dynamically controlling the adapter output voltage. A preferred embodiment exemplifies a closed loop circuit for battery charging. The circuit includes an AC adapter and a monitoring circuit for monitoring the closed loop and for providing feedback to the AC adapter, controlling the adapter output voltage.

Claims

1. A method for charging a battery comprising:

coupling an end equipment system to an AC adapter that provides an AC adapter output voltage to charge the battery of the end equipment system;

monitoring, at the end equipment system, a plurality of parameters associated with the charging of the battery;

determining a plurality of error signals from a plurality of error amplifiers by comparing the monitored plurality of parameters to a plurality of preprogrammed references;

adding the plurality of error signals to provide a total error signal;

converting the total error signal to a control signal;

sending the control signal to the AC adapter;

determining whether to actuate or deactuate a plurality of switches based at least in part on the control signal; and

adjusting the AC adapter output voltage in response to the control signal.

2. The method according to claim 1, wherein the plurality of parameters further comprise battery charge current and battery charge voltage.

3. The method according to claim 1, wherein the plurality of parameters further comprise at least two of system parameters, battery parameters, and input voltage.

4. The method according to claim 1, wherein the AC adapter output voltage is set higher than the voltage of the battery by an amount required to achieve regulation to overcome voltage drops in the path from the AC adapter to the battery.

5. The method according to claim 4, wherein the amount is defined by an ohmic impedance in the path.

6. The method according to claim 5, wherein the ohmic impedance in the path is based on the ohmic impedance of fault condition switches located in the path.

7. The method according to claim 5, wherein the AC adapter output voltage is set to a lowest value required to supply a system load of the end equipment and a battery charge current to the battery.

8. A system for charging a battery comprising:

an AC adapter that provides an AC adapter output voltage to charge the battery; and

an end equipment system coupled to the AC adapter, the end equipment system including;

the battery;

a plurality of control loops, wherein each control loop includes an error amplifier that generates an error signal by comparing at least one of a plurality of parameters associated with the charging of the battery to at least one of a plurality of preprogrammed references;

an adder that adds each of the error signals together to provide a total error signal;

an adapter voltage control that converts the total error signal to a control signal, wherein the AC adapter is configured to adjust the AC adapter output voltage in response to the control signal;

control logic that is coupled to the adapter voltage control; and

a driver that is coupled to the control logic, wherein the driver is adapted to provide actuation signals.

9. The system according to claim 8, wherein each of the plurality of control loops further comprises an error amplifier that determines an error signal based on one parameter of the plurality of parameters and one preprogrammed reference of the plurality of preprogrammed references.

10. The system according to claim 8, wherein the plurality of parameters further comprise battery charge current and battery charge voltage.

11. The system according to claim 8, wherein the plurality of parameters further comprise at least two of system parameters, battery parameters, and input voltage.

12. The system according to claim 8, wherein the AC adapter is configured to set the AC adapter output voltage higher than the voltage of the battery by an amount required to achieve regulation to overcome voltage drops in the path from the AC adapter to the battery.

13. The system according to claim 12, wherein the amount is defined by an ohmic impedance in the path.

14. The system according to claim 8, wherein the system further comprises fault condition switches located in the path between an AC adapter output voltage terminal and a system power bus of the end equipment, the fault condition switches being turned on in a normal operation and turning off under a fault condition to avoid damage to the end equipment system.

15. The system according to claim 14, wherein the system power bus is coupled to the battery.

16. The system according to claim 8, wherein the AC adapter output voltage is set to a lowest value required to supply a system load of the end equipment and a battery charge current to the battery.

17. A system for charging a battery comprising:

an AC adapter that provides an AC adapter output voltage to charge a battery of an end equipment system, the AC adapter being configured to adjust the AC adapter output voltage in response to a control signal; and

an end equipment system coupled to the AC adapter, the end equipment system including;

a battery;

a plurality of error amplifiers configured to determine a respective error signal by comparing a parameter associated with the charging of the battery to a respective preprogrammed reference;

an adder that adds the error signals of the plurality of error amplifiers to provide a total error signal;

an adapter voltage control that converts the total error signal to the control signal that is employed to adjust the AC adapter output voltage;

control logic that is coupled to the adapter voltage control; and

a driver that is coupled to the control logic, wherein the driver is adapted to provide actuation signals.

18. The system according to claim 17, wherein the plurality of error amplifiers further comprises a first error amplifier that determines an error signal based on a battery charge current and a maximum charge current limit of the battery and a second error amplifier that determines an error signal based on a battery charge voltage and an acceptable charge voltage level limit.

19. The system according to claim 18, wherein the plurality of error amplifiers further comprises a third error amplifier that determines an error signal based on one of another battery charge parameter and a system parameter of the end equipment system.

20. The system according to claim 17, wherein the control signal is one of an analog current, an analog voltage, and a digital signal.