Apparatus and method for sensing leakage current of battery, and battery-driven apparatus and battery pack comprising the apparatus

1. An apparatus for sensing a leakage current of a battery, comprising:

a floating capacitor charged with a voltage detected from a cathode terminal or an anode terminal of a battery;

a terminal selection switching unit for selecting a voltage detection path for the cathode or anode terminal;

a charge switching unit for charging the floating capacitor with a detection voltage of the cathode or anode terminal, detected through the selected voltage detection path;

a polarity reverse switching unit for reversing a polarity of the detection voltage of the anode terminal charged to the floating capacitor; and

a leakage current determining unit for sensing the detection voltage of the cathode terminal charged to the floating capacitor and the polarity-reversed detection voltage of the anode terminal charged to the floating capacitor to calculate a leakage resistance, and then comparing the calculated leakage resistance with a criterion insulation resistance to determine whether or not a leakage current occurs.

2. The apparatus for sensing a leakage current of a battery according to claim 1 , further comprising a voltage distribution node installed on a first line formed between the cathode and anode terminals of the battery,

wherein the terminal selection switching unit comprises:

a first switch and a second switch respectively installed between the voltage distribution node and the cathode terminal of the battery and between the voltage distribution node and the anode terminal of the battery; and

a third switch installed on a second line extending from the voltage distribution node.

3. The apparatus for sensing a leakage current of a battery according to claim 2 , wherein the floating capacitor is installed on a third line arranged in parallel with the second line.

4. The apparatus for sensing a leakage current of a battery according to claim 2 , wherein the charge switching unit comprises: a fourth switch for switching the connection between a first terminal of the floating capacitor and the selected voltage detection path; and a fifth switch for switching the connection between a second terminal of the floating capacitor and the ground.

5. The apparatus for sensing a leakage current of a battery according to claim 4 , wherein the polarity reverse switching unit comprises: a sixth switch for switching the connection between a first terminal of the floating capacitor and the ground; and a seventh switch for switching the connection between a second terminal of the floating capacitor and the selected voltage detection path.

6. The apparatus for sensing a leakage current of a battery according to claim 1 ,

wherein the leakage current determining unit comprises:

a switch controller for controlling operations of the terminal selection switching unit, the charge switching unit and the polarity reverse switching unit;

a voltage detection unit for sensing the detection voltage of the cathode terminal and the polarity-reversed detection voltage of the anode terminal output from the floating capacitor and then outputting an analog voltage signal corresponding thereto;

an A/D (Analog/Digital) converter for converting the output analog voltage signal into a digital voltage signal; and

a CPU (Central Processing Unit) for calculating a leakage resistance using the digital voltage signal received from the A/D converter and then comparing the leakage resistance with the criterion insulation resistance to determine whether or not a leakage current occurs.

7. The apparatus for sensing a leakage current of a battery according to claim 6 ,

wherein the voltage detection unit comprises a differential amplifier for sensing the detection voltage of the cathode terminal applied from the floating capacitor and the polarity-reversed detection voltage of the anode terminal applied from the floating capacitor.

8. The apparatus for sensing a leakage current of a battery according to claim 1 ,

wherein the leakage current determining unit calculates a leakage resistance according to the following equation:

R

leakage

=

R

i

×

(

E

-

V

A

+

V

B

)

(

V

A

-

V

B

)

where Ri is an internal resistance of the apparatus, E is a voltage of both ends of the battery, VA is the detection voltage of the cathode terminal charged to the floating capacitor, and VB is the polarity-reversed detection voltage of the anode terminal charged to the floating capacitor.

9. The apparatus for sensing a leakage current of a battery according to claim 1 ,

wherein the leakage current determining unit comprises a leakage current alarming unit for giving a visual or audible alarm when a leakage resistance occurs.

10. The apparatus for sensing a leakage current of a battery according to claim 1 ,

wherein the leakage current determining unit determines that a leakage current occurs on the condition that the calculated leakage resistance is smaller than a criterion insulation resistance.

11. A battery-driven apparatus comprising the apparatus for sensing a leakage current of a battery according to the claim 1 .

12. A battery pack comprising the apparatus for sensing a leakage current of a battery according to the claim 1 .

13. A method for sensing a leakage current of a battery comprising:

(a) charging a floating capacitor with a detection voltage of a cathode terminal of a battery by selecting a voltage detection path for the cathode terminal of the battery, and then sensing the charged detection voltage of the cathode terminal;

(b) charging the floating capacitor with a detection voltage of an anode terminal of the battery by selecting a voltage detection path for the anode terminal of the battery, and then reversing a polarity of the charged detection voltage of the anode terminal and sensing the polarity-reversed detection voltage of the anode terminal;

(c) calculating a leakage current by using the sensed detection voltage of the cathode terminal and the polarity-reversed detection voltage of the anode terminal; and

(d) comparing the calculated leakage resistance with a criterion insulation resistance to determine whether or not a leakage current occurs.

14. The method for sensing a leakage current of a battery according to claim 13 ,

wherein, in the step (c), the leakage current is calculated according to the following equation:

R

leakage

=

R

i

×

(

E

-

V

A

+

V

B

)

(

V

A

-

V

B

)

where Ri is an internal resistance of a leakage current sensing apparatus that executes the method, E is a voltage of both ends of the battery, VA is the detection voltage of the cathode terminal charged to the floating capacitor, and VB is the polarity-reversed detection voltage of the anode terminal charged to the floating capacitor.

15. The method for sensing a leakage current of a battery according to claim 13 , further comprising:

making a visual or audible alarm when a leakage resistance occurs.

16. The method for sensing a leakage current of a battery according to claim 13 ,

wherein, in the step (d), it is determined that a leakage current occurs on the condition that the calculated leakage resistance is smaller than a criterion insulation resistance.