Characterization of external short circuit faults in electric vehicle Li-ion battery packs and prediction using artificial neural networks

To investigate the characteristics of lithium-ion battery packs under the condition that one cell is short-circuited when the whole battery pack is being discharged or charged, systematic battery external short circuit (ESC) experiments are conducted. Since not all battery cells are equipped with current sensors because of the space limitation and manufacturing cost, an artificial neural network (ANN)-based method is proposed to estimate the current of the short-circuited cell using only the voltage information, which is the feasible practice in electric vehicle application. Furthermore, the estimated current is used to predict maximum temperature increase as well as internal and surface temperature distribution of the ESC cell based on a 3D electro-thermal coupling model. Two experimental groups under constant current charging condition and constant power discharging condition are employed to validate the stability and accuracy of the proposed method. The results indicate that the root-mean-square-error between the estimated and measured current are 3.72 A and 6.61 A under the two validation experiments respectively, and the maximum estimation errors of temperature increase are 4.9 degrees C and 7.3 degrees C respectively.