Battery charging controller and battery module using the same

• US 8,154,250 B2
• Filed: 03/09/2009
• Issued: 04/10/2012
• Est. Priority Date: 06/20/2008
• Status: Active Grant

• Current Assignee: Green Solution Technology Co., Ltd.
• Original Assignee: Green Solution Technology Co., Ltd.
• Inventors: Yu, Chung-Che, Shiu, Shian-Sung
• Primary Examiner(s): Assouad, Patrick
• Assistant Examiner(s): Chung, Steve T
• Application Number:
  US12/400,375
• Publication Number:
  US 20090315515A1
• Time in Patent Office: 1,128 Days
• Field of Search: 320/116, 320/120, 320/124, 320/135, 320/118, 307/41
• US Class Current: 320/116
• CPC Class Codes: H02J 7/0016 using shunting, discharge or bypass circuits

Abstract

The present invention discloses a battery charging controller for achieving a balanced battery charge. The battery charging controller includes a voltage divider, a switch module and a balance circuit. A reference voltage generated by the voltage divide is used to determine which battery unit in a battery module has an insufficient voltage lower than the others, so that the balance circuit controls the switch module to allow a larger current to charge a lower-voltage battery than a higher-voltage battery, so as to result in substantially the same voltage for each fully charged battery of the battery module.

Claims

1. A battery balanced charging controller, for balancing a battery change of a first battery and a second battery, and a negative terminal of the first battery being electrically coupled to a positive terminal of the second battery to form a connecting point, and a positive terminal of the first battery forming a first terminal, and a negative terminal of the second battery forming a second terminal, and the battery balanced charging controller comprising:

a voltage divider, coupled between the first terminal and the second terminal, for providing an upper reference potential level and a lower reference potential level, and the upper reference potential level being higher than the lower reference potential level;

a switch module including a first switch and a second switch, and the first switch being coupled to the first terminal and the connecting point, and the second switch being coupled to the second terminal and the connecting point;

a balance circuit, coupled to the connecting point, the voltage divider and the switch module, and the balance circuit determining whether to pass a balanced charging current through the first switch or the second switch according to a potential level of the connecting point, the upper reference potential level and the lower reference potential level; and

an under voltage lockout unit coupled to the first terminal and the second terminal, such that if the potential difference between the first terminal and the second terminal is lower than a predetermined starting voltage, the under voltage lockout unit generates an under voltage signal for stopping the operation of the battery balanced charging controller.

2. The battery balanced charging controller of claim 1, wherein the balance circuit comprises a first comparator and a second comparator, and the first comparator is provided for receiving the lower reference potential level and the potential level of the connecting point to output a first comparison signal, and the second comparator is provided for receiving the upper reference potential level and the potential level of the connecting point to output a second comparison signal, and the balance circuit generates a first control signal and a second control signal according to the first comparison signal and the second comparison signal to control the first switch and the second switch respectively, such that if the potential level of the connecting point is lower than the lower reference potential level, the balanced charging current is passed through the first switch, and if the potential level of the connecting point is higher than the upper reference potential level, the balanced charging current is passed through the second switch.

3. The battery balanced charging controller of claim 2, further comprising a resistor coupled to the connecting point and the switch module.

4. The battery balanced charging controller of claim 2, wherein the voltage divider comprises a first resistor, a second resistor and a third resistor, serially connected, and the first resistor is coupled to the first terminal, and the third resistor is coupled to the second terminal, and the second resistor is coupled to the first resistor for producing the upper reference potential level and coupled to the third resistor for producing the lower reference potential level, and impedance of the first resistor and the third resistor are equal, and the impedance of the second resistor is smaller than the impedance of the first resistor.

5. The battery balanced charging controller of claim 2, further comprising a time delay unit coupled to the balance circuit and the switch module, such that one of the first switch and the second switch is conducted after a predetermined time period from the other being cutoff.

6. The battery balanced charging controller of claim 2, further comprising an over-temperature protection unit, for detecting a temperature of the battery balanced charging controller, such that if the temperature exceeds an over-temperature protection point, the over-temperature protection unit generates an over-temperature protection signal to stop the operation of the battery balanced charging controller.

7. The battery balanced charging controller of claim 2, further comprising a start detection circuit, for starting the battery balanced charging controller after receiving a start signal.

8. A battery module, comprising (N+1) battery units, electrically coupled in series, and N being an integer greater than zero;

and

N battery balanced charging controller, and the M_th battery balanced charging controller being coupled to a first terminal, a second terminal and a connecting point of serially connected the M_th battery unit and the (M+1)_th battery unit, and the M_th battery balanced charging controller determining a battery potential level of the M_th battery unit and the (M+1)_th battery units according to the first terminal, the second terminal and the connecting point, such that if a potential difference between the M_th battery unit and the (M+1)_th battery unit exceeds a predetermined percentage, a balanced charging current is conducted to the battery unit with a lower battery potential level; and

an under voltage lockout unit coupled to the first terminal and the second terminal, such that if the potential difference of the first terminal and the second terminal is lower than a predetermined starting voltage, the under voltage lockout unit generates an under voltage signal to stop the operation of the battery balanced charging controller.

9. The battery module of claim 8, wherein each battery balanced charging controller comprises a first comparator and a second comparator, and the first comparator is provided for receiving a lower reference potential level and a potential level of the connecting point to output a first comparison signal, and the second comparator is provided for receiving an upper reference potential level and the potential level of the connecting point to output a second comparison signal, and the battery balanced charging controller determining whether or not to generate the balanced charging current according to the first comparison signal and the second comparison signal.

10. The battery module of claim 9, wherein each battery balanced charging controller further comprises a voltage divider coupled to the first terminal and the second terminal, for providing the upper reference potential level and the lower reference potential level, and the upper reference potential level is higher than the lower reference potential level.

11. The battery module of claim 10, wherein the voltage divider comprises a first resistor, a second resistor and a third resistor connected in series, and the first resistor is coupled to the first terminal, and the third resistor is coupled to the second terminal, and the second resistor is coupled to the first resistor for producing the upper reference potential level and coupled to the third resistor for producing the lower reference potential level, and the impedance of the first resistor and the third resistor are equal and the impedance of the second resistor is smaller than the impedance of the first resistor.

12. The battery module of claim 9, wherein each the battery balanced charging controller further comprises a switch module including a first switch and a second switch, and the first switch is coupled to the first terminal and the connecting point, and the second switch is coupled to the second terminal and the connecting point, and the battery balanced charging controller determines whether to pass the balanced charging current through the first switch or the second switch according to the first comparison signal and the second comparison signal.

13. The battery module of claim 12, wherein each battery balanced charging controller further comprising a time delay unit, such that one of the first switch and the second switch is conducted after a predetermined time period from the other being cutoff.

14. The battery module of claim 9, wherein each battery balanced charging controller is coupled to the connecting point by a resistor.

15. The battery module of claim 10, wherein each battery balanced charging controller further comprises an over-temperature protection unit, for detecting a temperature of the battery balanced charging controller, and if the temperature exceeds an over-temperature protection point, then the over-temperature protection unit generates an over-temperature protection signal to stop the operation of the battery balanced charging controller.

16. The battery module of claim 10, wherein each battery balanced charging controller further comprises a start detection circuit for starting the battery balanced charging controller after receiving a start signal.