Welding inspection apparatus for battery modules

1 . A welding inspection apparatus for battery modules, the welding inspection apparatus comprising:

a bank constituted by two or more battery cells connected in parallel;

a battery module constituted by one or more banks connected in series;

an alternating current application unit configured to apply an alternating current to an entirety of the battery module; and

a measurement unit configured to measure an impedance of each of the one or more banks,

wherein, when a resistance value of each of the one or more banks is greater than a predetermined resistance value, a determination is made that a welding of at least one of the two or more battery cells in the bank is defective, and a quantity of defects in each of the one or more banks is determined based on resistance values with respect to a frequency of the alternating current of the one or more banks that is greater than a predetermined frequency, and

wherein the resistance value increases as a number of welding defects present in a relevant bank increases, such that welding defects occurring in the relevant bank is quantitatively identified.

2 . The welding inspection apparatus according to claim 1 , further comprising a controller configured to control the alternating current application unit and the measurement unit.

3 . The welding inspection apparatus according to claim 1 , further comprising a current transformer (CT) connected to a positive electrode terminal of the battery module.

4 . The welding inspection apparatus according to claim 1 , wherein the alternating current has the predetermined frequency of 10 kHz or higher.

5 . The welding inspection apparatus according to claim 1 , wherein the resistance value is a resistance value corresponding to a real part of the impedance.

6 . A method of inspecting a welding of the battery module using the welding inspection apparatus according to claim 1 , the method comprising:

applying the alternating current to the entirety of the battery module;

measuring the alternating current that flows in the entirety of the battery module and a voltage of each bank of the one or more banks;

calculating the impedance and a resistance value of the each bank; and

when the resistance value of the each bank is greater than the predetermined resistance value, determining that the welding of at least one battery cell in the each bank is defective.

7 . The method according to claim 6 , wherein the alternating current has the predetermined frequency of 10 kHz or higher.

8 . The method according to claim 6 , wherein the alternating current has a maximum current of 1 A peak .

9 . The method according to claim 6 , wherein the resistance value is a resistance value corresponding to a real part of the impedance.

10 . The method according to claim 6 , wherein, when the resistance value of the each bank is greater than the predetermined resistance value, it is determined that the resistance value of the each bank is greater than a resistance value of a normal bank measured in advance or that the resistance value of the each bank is greater than a resistance value of another bank.

11 . The welding inspection apparatus according to claim 1 , wherein a number of abnormal welds of the two or more battery cells is determined based on an impedance spectrum of the battery module.

12 . The welding inspection apparatus according to claim 1 , wherein the welding of the at least one of the two or more battery cells in the bank is defective is determined based on an impedance spectrum of the battery module using the frequency of the alternating current peaking at about 15 kHz to 20 kHz.

13 . The welding inspection apparatus according to claim 1 , wherein the alternating current has the predetermined frequency of about 100 kHz or higher.