CHARGING CONTROL APPARATUS CONTROLLING CHARGING CURRENT AND CONTROL METHOD THEREFORE

• US 20090153100A1
• Filed: 08/21/2008
• Published: 06/18/2009
• Est. Priority Date: 12/14/2007
• Status: Abandoned Application

• Current Assignee: Fujitsu Limited, Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Fujitsu Limited
• Inventors: OKUMURA, Masafumi, Fukuda, Hideo
• Application Number:
  US12/195,631
• Publication Number:
  US 20090153100A1
• Time in Patent Office: Days
• US Class Current: 320/116
• CPC Class Codes: H02J 7/0014 Circuits for equalisation of charge between batteries
• CPC Class Codes: H02J 7/00302 Overcharge protection
• CPC Class Codes: H02J 7/0071 with a programmable schedule

Abstract

Provided is a control apparatus that controls a battery circuit, including a voltage detector that detects a battery voltage, a battery protection circuit that stops charging current when the battery voltage detected by the voltage detecting unit exceeds a protection voltage, and a charging circuit being capable of changing a charging current value for charging a battery. The control apparatus includes an input interface that reads the battery voltage detected by the voltage detecting unit, a decision unit that decides whether or not the read battery voltage has approached the protection voltage to a predetermined limit value, an output interface that outputs a signal for controlling the charging current, and a current control unit that limits the charging current to a predetermined limit value via the output interface when the read battery voltage is decided to have approached the protection voltage to the predetermined limit value.

Claims

1. A charging control apparatus controlling charging current comprising:

a voltage detector that detects a battery voltage;

a battery protection circuit that stops charging current when the battery voltage detected by the voltage detecting unit exceeds a protection voltage;

a charging circuit being capable of changing a charging current value for charging a battery; and

a control unit including;

an input interface that reads the battery voltage detected by the voltage detecting unit;

a decision unit that decides whether or not the read battery voltage has approached the protection voltage to a predetermined limit value;

an output interface that outputs a signal for controlling the charging current; and

a current control unit that limits the charging current to a predetermined limit value via the output interface when the read battery voltage is decided to have approached the protection voltage to the predetermined limit value.

2. A charging control apparatus controlling charging current according to claim 1 wherein,

the battery is made up of a plurality of cell blocks connected in series, each of which includes one cell or a plurality of cells,

the voltage detecting unit includes a measuring circuit that detects a voltage of each of the cell blocks,

the decision unit decides whether or not a voltage of any one of the cell blocks has approached the protection voltage of the cell block to a predetermined limit value, and

the current control unit limits the charging current to the predetermined limit value when the voltage of any one of the cell blocks is decided to have approached the protection voltage of the cell block to the predetermined limit value.

3. A charging control apparatus controlling charging current according to claim 1, wherein the input interface reads the voltage detected by the voltage detecting unit, via a serial communication.

4. A charging control apparatus controlling charging current according to claim 1, wherein the output interface adjusts the charging current with a D/A converter.

5. A charging control apparatus controlling charging current according to claim 1, wherein when the battery voltage is decided to have approached the predetermined limit value, the current limiting unit decreases the charging current stepwise over time.

6. A charging control apparatus controlling charging current according to claim 1, wherein when the battery voltage is decided to have approached the predetermined limit value, the current limiting unit decreases the charging current by a first change amount and then increases the charging current stepwise over time by a second change amount smaller than the first change amount.

7. A charging control apparatus controlling charging current according to claim 1, wherein when the battery voltage is decided to have approached the predetermined limit value, the current limiting unit decreases the charging current according to a difference between the protection voltage and the battery voltage.

8. A charging control apparatus controlling charging current according to claim 1, wherein the current limiting unit decreases the charging current along with a decrease in a difference between the battery voltage and the protection voltage.

9. A charging control apparatus controlling charging current according to claim 2, wherein when the voltage of any one of the cell blocks is decided to have approached the protection voltage of the cell block to the predetermined limit value, the current limiting unit decreases the charging current stepwise over time.

10. A charging control apparatus controlling charging current according to claim 2, wherein when the voltage of any one of the cell blocks is decided to have approached the protection voltage of the cell block to a predetermined limit value, the current limiting unit decreases the charging current by a first change amount and then increases the charging current stepwise over time by a second change amount smaller than the first change amount.

11. A charging control apparatus controlling charging current according to claim 2, wherein when the voltage of any one of the cell blocks is decided to have approached the protection voltage of the cell block to a predetermined limit value, the current limiting unit decreases the charging current according to a difference between the protection voltage and the battery voltage.

12. A charging control apparatus controlling charging current according to claim 2, wherein the current limiting unit decreases the charging current along with a decrease in a difference between the voltage of any one of the cell blocks and the protection voltage of the cell block.

13. A charging control apparatus controlling charging current according to claim 1, wherein the control apparatus includes:

a state decision unit that decides whether or not the battery voltage has exceeded the protection voltage after the battery protection circuit stopped the charging current; and

a canceling unit that cancels a protection process performed by the battery protection circuit if the battery voltage has not exceeded the protection voltage.

14. A charging control apparatus controlling charging current according to claim 2, wherein the control apparatus includes:

a state decision unit that decides whether or not the voltage of any one of the cell blocks has exceeded the protection voltage of the cell block after the battery protection circuit stopped the charging current; and

a canceling unit that cancels a protection process performed by the battery protection circuit if the voltages of all the cell blocks are decided not to have exceeded the protection voltage of the cell block.

15. A method of controlling a battery circuit comprising:

reading the battery voltage detected by a voltage detector, via an input interface;

deciding whether or not the read battery voltage has approached the protection voltage to a predetermined limit value; and

limiting the charging current to a predetermined limit value via an output interface when the read battery voltage is decided to have approached the protection voltage to the predetermined limit value.

16. A charging control apparatus controlling charging current comprising:

a voltage detector that detects a battery voltage;

a battery protection circuit that stops charging current when the battery voltage detected by the voltage detecting unit reaches a protection voltage;

a charging circuit being capable of changing a charging current value for charging a battery; and

a control apparatus including;

an input interface that inputs a signal indicating an operating state of the battery protection circuit;

an output interface that outputs a signal for controlling the charging current;

a protection state decision unit that decides whether or not the battery protection circuit has stopped the charging current;

a voltage state decision unit that decides whether or not the battery voltage has reached the protection voltage, after the battery protection circuit stopped the charging current; and

a charging control unit that cancels the stopping process of the charging current performed by the battery protection circuit and restarts the charging with the charging current limited to a predetermined limit value via the output interface when the battery voltage has not reached the protection voltage.

17. A charging control apparatus controlling charging current according to claim 16 wherein,

the battery is made up of a plurality of cell blocks connected in series, each of which includes one cell or a plurality of cells,

the battery protection circuit stops the charging current when the voltage of any one of the cell blocks reaches the protection voltage of the cell block,

the voltage detecting unit includes a measuring circuit that detects a voltage of each of the cell blocks,

the voltage state decision unit decides whether or not the voltage of any one of the cell blocks has reached the protection voltage of the cell block, after the battery protection circuit stopped the charging current, and

the charging control unit cancels the stopping process of the charging current performed by the battery protection circuit and restarts the charging with the charging current limited to the limit value when voltages of all the cell blocks are lower than the protection voltage of the cell block.

18. A method of controlling a battery circuit including a voltage detector that detects a battery voltage, a battery protection circuit that stops charging current when the battery voltage detected by the voltage detecting unit reaches a protection voltage, a charging circuit being capable of changing a charging current value for charging a battery, the method comprising:

inputting a signal indicating an operating state of the battery protection circuit via an input interface;

deciding whether or not the battery protection circuit has stopped the charging current;

deciding whether or not the battery voltage has reached the protection voltage after the battery protection circuit stopped the charging current; and

canceling a stopping process of the charging current performed by the battery protection circuit and restarting a charging with the charging current limited to a predetermined limit value via an output interface when the battery voltage has not reached the protection voltage.