Battery charger circuits using constant current/constant voltage mode using maintenance offset currents and methods of operating the same

• US 20050007075A1
• Filed: 06/02/2004
• Published: 01/13/2005
• Est. Priority Date: 06/19/2003
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Sub, Choi Jin, Woo, Lee Won
• Granted Patent: US 7,612,539 B2
• Time in Patent Office: Days
• US Class Current: 320/148
• CPC Class Codes: H02J 7/0071 with a programmable schedule
• CPC Class Codes: Y02B 40/00 Technologies aiming at improving the efficiency of home appliances, e.g. induction cooking or efficient technologies for refrigerators, freezers or dish washers
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02E 60/13 Energy storage using capacitors

Abstract

Battery charging circuits can change from charging a battery in a constant current mode using an amplifier circuit output to control a voltage controlled current source to provide substantially constant current to the battery to charging the battery in a constant voltage mode using the amplifier circuit output to control the voltage controlled current source to provide a varied current to the battery. Related methods are disclosed.

Claims

1. A method of charging a battery comprising:

changing from charging a battery in a constant current mode using an amplifier circuit output to control a voltage controlled current source to provide substantially constant current to the battery to charging the battery in a constant voltage mode using the amplifier circuit output to control the voltage controlled current source to provide a varied current to the battery.

2. A method according to claim 1 wherein changing further comprises:

charging the battery in the constant current mode by providing a substantially constant current to the battery;

comparing a voltage at the input of the battery to a predetermined threshold voltage beyond which the constant voltage mode is used to charge the battery;

ceasing charging the battery in the constant current mode upon determining that the voltage at the input of the battery equals the predetermined threshold voltage; and

charging the battery in the constant voltage mode by providing a varied current to the battery.

3. A method according to claim 2 wherein comparing comprises:

providing the predetermined threshold voltage to a first terminal of a load;

providing the voltage at the input of the battery to a second terminal of the load to develop a voltage difference between the first and second terminals of the load to provide a current between the first and second terminals.

4. A method according to claim 2 wherein charging the battery in the constant current mode comprises:

generating the substantially constant current using the output of the amplifier circuit to the voltage controlled current source responsive to a voltage across a load, that is separate from the battery, at an input to the amplifier circuit.

5. A method according to claim 4 wherein the voltage across the load is developed in response to the substantially constant current provided by the voltage controlled current source.

6. A method according to claim 2 wherein charging the battery in the constant voltage mode comprises:

generating the substantially constant voltage using the output of the amplifier circuit to the voltage controlled current source responsive to a voltage across a load, that is separate from the battery, at an input to the amplifier circuit.

7. A method according to claim 6 wherein the voltage across the load is provided in response to a current provided by the voltage controlled current source and a variable maintenance current provided by a voltage maintenance circuit each provided to the load at the input to the amplifier.

8. A method according to claim 7 wherein the variable maintenance current is based on a difference between the predetermined threshold voltage and the voltage at the input of the battery.

9. A method according to claim 2 wherein charging the battery in the constant current mode comprises generating the substantially constant current using the output of the amplifier circuit to the voltage controlled current source responsive to a voltage across a load, that is separate from the battery, at an input to the amplifier circuit;

and

wherein charging the battery in the constant voltage mode comprises generating the substantially constant current using the output of the amplifier circuit to the voltage controlled current source responsive to a voltage across a load, that is separate from the battery, at an input to the amplifier circuit.

10. A method according to claim 2 wherein comparing the voltage at the input of the battery to the threshold voltage further comprises:

reducing an offset in the voltage at the input of the battery by amplifying the voltage by a voltage gain; and

then

comparing the voltage to the predetermined threshold value.

11. A circuit for charging a battery comprising:

an amplifier circuit configured to charge a battery in a constant current mode using an output thereof to control a voltage controlled current source coupled thereto to provide substantially constant current to the battery and configured to charge the battery in a constant voltage mode using the output to control the voltage controlled current source to provide a varied current to the battery.

12. A circuit according to claim 11 further comprising:

a voltage maintenance circuit coupled between an input to the battery and a load coupled to an input to the amplifier, wherein the voltage maintenance circuit is configured to apply a predetermined threshold voltage to a first terminal of a load and configured to apply the voltage at the input to the battery to a second terminal of the load.

13. A circuit according to claim 11 wherein the voltage maintenance circuit further comprises:

a first buffer circuit coupled to the first terminal of the load to provide a stabilized predetermined threshold voltage to the first terminal based on the predetermined threshold voltage; and

a second buffer circuit coupled to the second terminal of the load to provide a stabilized input battery voltage to the second terminal based on the voltage at the input to the battery.

15. A circuit according to claim 13 further comprising:

a voltage detector circuit coupled to an input of the second buffer circuit and configured to provide the stabilized input battery voltage having an offset included in the voltage at the input to the battery reduced in the stabilized input battery voltage.

16. A circuit according to claim 15 wherein the voltage detector circuit comprises:

an offset amplifier circuit coupled to the input to the battery and configured to reduce an offset voltage included in the voltage at the input to the battery.

17. A circuit according to claim 16 wherein the voltage detector circuit comprises:

a comparator circuit coupled to an output of the offset amplifier circuit and configured to compare the stabilized input battery voltage to the predetermined threshold voltage to provide a signal indicating that the battery is to be charged using the constant voltage mode.

18. A circuit according to claim 17 wherein:

a current amplifier circuit coupled to an output of the comparator circuit and configured to amplify the preliminary maintenance current when the signal is active to provide the variable maintenance current to the load coupled to the input of the amplifier.

14. A circuit according to clam 13 wherein a preliminary maintenance current is developed between the first ad second terminals of the load based on a difference between the stabilized predetermined threshold voltage and the stabilized input battery voltage.

19. A circuit for charging a battery comprising:

means for changing from charging a battery in a constant current mode using an amplifier circuit output to control a voltage controlled current source to provide substantially constant current to the battery to charging the battery in a constant voltage mode using the amplifier circuit output to control the voltage controlled current source to provide a varied current to the battery.

20. A circuit according to claim 19 wherein means for changing further comprises:

means for charging the battery in the constant current mode by providing a substantially constant current to the battery;

means for comparing a voltage at the input of the battery to a predetermined threshold voltage beyond which the constant voltage mode is used to charge the battery;

means for ceasing charging the battery in the constant current mode upon determining that the voltage at the input of the battery equals the predetermined threshold voltage; and

means for charging the battery in the constant voltage mode by providing a varied current to the battery.

21. A circuit according to claim 20 wherein means for comparing comprises:

means for providing the predetermined threshold voltage to a first terminal of a load;

means for providing the voltage at the input of the battery to a second terminal of the load to develop a voltage difference between the first and second terminals of the load to provide a current between the first and second terminals.

22. A circuit according to claim 20 wherein the means for charging the battery in the constant current mode comprises:

means for generating the substantially constant current using the output of the amplifier circuit to the voltage controlled current source responsive to a voltage across a load, that is separate from the battery, at an input to the amplifier circuit.

23. A circuit according to claim 22 wherein the voltage across the load is developed in response to the substantially constant current provided by the voltage controlled current source.

24. A circuit according to claim 20 wherein the means for charging the battery in the constant voltage mode comprises:

means for generating the substantially constant voltage using the output of the amplifier circuit to the voltage controlled current source responsive to a voltage across a load, that is separate from the battery, at an input to the amplifier circuit.

25. A circuit according to claim 24 wherein the voltage across the load is provided in response to a current provided by the voltage controlled current source and a variable maintenance current provided by a voltage maintenance circuit each provided to the load at the input to the amplifier.

26. A circuit according to claim 25 wherein the variable maintenance current is based on a difference between the predetermined threshold voltage and the voltage at the input of the battery.

27. A circuit according to claim 20 wherein the means for charging the battery in the constant current mode comprises means for generating the substantially constant current using the output of the amplifier circuit to the voltage controlled current source responsive to a voltage across a load, that is separate from the battery, at an input to the amplifier circuit;

and

wherein the means for charging the battery in the constant voltage mode comprises means for generating the substantially constant current using the output of the amplifier circuit to the voltage controlled current source responsive to a voltage across a load, that is separate from the battery, at an input to the amplifier circuit.

28. A circuit according to claim 20 wherein the means for comparing the voltage at the input of the battery to the threshold voltage further comprises:

means for reducing an offset in the voltage at the input of the battery by amplifying the voltage by a voltage gain; and

then

means for comparing the voltage to the predetermined threshold value.